Reversible effects of sphingomyelin degradation on cholesterol distribution and metabolism in fibroblasts and transformed neuroblastoma cells.

PubMed Central

Pörn, M I; Slotte, J P

1990-01-01

Plasma-membrane sphingomyelin appears to be one of the major determinants of the preferential allocation of cell cholesterol into the plasma-membrane compartment, since removal of sphingomyelin leads to a dramatic redistribution of cholesterol within the cell [Slotte & Bierman (1988) Biochem. J. 250, 653-658]. In the present study we examined the long-term effects of sphingomyelin degradation on cholesterol redistribution in cells and determined the reversibility of the process. In a human lung fibroblast-cell line, removal of 80% of the sphingomyelin led to a rapid and transient up-regulation (3-fold) of acyl-CoA:cholesterol acyltransferase (ACAT) activity, and also, within 30 h, to the translocation of about 50% of the cell non-esterified cholesterol from a cholesterol oxidase-susceptible compartment (i.e. the cell surface) to oxidase-resistant compartments. At 49 h after the initial sphingomyelin degradation, the cell sphingomyelin level was back to 45% of the control level, and the direction of cell cholesterol flow was toward the cell surface, although the original distribution was not achieved. In a transformed neuroblastoma cell line (SH-SY5Y), the depletion of sphingomyelin led to a similarly rapid and transient up-regulation of ACAT activity, and to the translocation of about 25% of cell-surface cholesterol into internal membranes (within 3 h). The flow of cholesterol back to the cholesterol oxidase-susceptible pool was rapid, and a pretreatment cholesterol distribution was reached within 20-49 h. Also, the resynthesis of sphingomyelin was faster in SH-SY5Y neuroblastoma cells and reached control levels within 24 h. The findings of the present study show that the cellular redistribution of cholesterol, as induced by sphingomyelin degradation, is reversible and suggest that the normalization of cellular cholesterol distribution is linked to the re-synthesis of sphingomyelin. PMID:2222406

Assembly of high density lipoprotein by the ABCA1/apolipoprotein pathway.

PubMed

Yokoyama, Shinji

2005-06-01

Mammalian somatic cells do not catabolize cholesterol and therefore need to export it for sterol homeostasis at the levels of cells and whole bodies. This mechanism may reduce intracellularly accumulated cholesterol in excess, and thereby would contribute to the prevention or cure of the initial stage of atherosclerotic vascular lesions. HDL is thought to play a main role in this reaction on the basis of epidemiological evidence and in-vitro experimental data. Two independent mechanisms have been identified for this reaction. One is non-specific diffusion-mediated cholesterol 'efflux' from the cell surface, and cholesterol is trapped by various extracellular acceptors including lipoproteins. Extracellular cholesterol esterification on HDL provides a driving force for the net removal of cell cholesterol, and some cellular factors may enhance this reaction. The other mechanism is an apolipoprotein-mediated process to generate HDL by removing cellular phospholipid and cholesterol. This reaction is mediated by a membrane protein ABCA1, and lipid-free or lipid-poor helical apolipoproteins recruit cellular phospholipid and cholesterol to assemble HDL particles. The reaction is composed of two elements: the assembly of HDL particles with phospholipid by apolipoprotein, and cholesterol enrichment in HDL. ABCA1 is essential for the former step, and the latter step requires further intracellular events. ABCA1 is a rate-limiting factor of HDL assembly and is regulated by transcriptional factors and posttranscriptional factors. Posttranscriptional regulation of ABCA1 involves the modulation of its calpain-mediated degradation.

Excess cholesterol inhibits glucose-stimulated fusion pore dynamics in insulin exocytosis.

PubMed

Xu, Yingke; Toomre, Derek K; Bogan, Jonathan S; Hao, Mingming

2017-11-01

Type 2 diabetes is caused by defects in both insulin sensitivity and insulin secretion. Glucose triggers insulin secretion by causing exocytosis of insulin granules from pancreatic β-cells. High circulating cholesterol levels and a diminished capacity of serum to remove cholesterol from β-cells are observed in diabetic individuals. Both of these effects can lead to cholesterol accumulation in β-cells and contribute to β-cell dysfunction. However, the molecular mechanisms by which cholesterol accumulation impairs β-cell function remain largely unknown. Here, we used total internal reflection fluorescence microscopy to address, at the single-granule level, the role of cholesterol in regulating fusion pore dynamics during insulin exocytosis. We focused particularly on the effects of cholesterol overload, which is relevant to type 2 diabetes. We show that excess cholesterol reduced the number of glucose-stimulated fusion events, and modulated the proportion of full fusion and kiss-and-run fusion events. Analysis of single exocytic events revealed distinct fusion kinetics, with more clustered and compound exocytosis observed in cholesterol-overloaded β-cells. We provide evidence for the involvement of the GTPase dynamin, which is regulated in part by cholesterol-induced phosphatidylinositol 4,5-bisphosphate enrichment in the plasma membrane, in the switch between full fusion and kiss-and-run fusion. Characterization of insulin exocytosis offers insights into the role that elevated cholesterol may play in the development of type 2 diabetes. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Alcohol consumption stimulates early steps in reverse cholesterol transport.

PubMed

van der Gaag, M S; van Tol, A; Vermunt, S H; Scheek, L M; Schaafsma, G; Hendriks, H F

2001-12-01

Alcohol consumption is associated with increased HDL cholesterol levels, which may indicate stimulated reverse cholesterol transport. The mechanism is, however, not known. The aim of this study was to evaluate the effects of alcohol consumption on the first two steps of the reverse cholesterol pathway: cellular cholesterol efflux and plasma cholesterol esterification. Eleven healthy middle-aged men consumed four glasses (40 g of alcohol) of red wine, beer, spirits (Dutch gin), or carbonated mineral water (control) daily with evening dinner, for 3 weeks, according to a 4 x 4 Latin square design. After 3 weeks of alcohol consumption the plasma ex vivo cholesterol efflux capacity, measured with Fu5AH cells, was raised by 6.2% (P < 0.0001) and did not differ between the alcoholic beverages. Plasma cholesterol esterification was increased by 10.8% after alcohol (P = 0.008). Changes were statistically significant after beer and spirits, but not after red wine consumption (P = 0.16). HDL lipids changed after alcohol consumption; HDL total cholesterol, HDL cholesteryl ester, HDL free cholesterol, HDL phospholipids and plasma apolipoprotein A-I all increased (P < 0.01). In conclusion, alcohol consumption stimulates cellular cholesterol efflux and its esterification in plasma. These effects were mostly independent of the kind of alcoholic beverage

Assembly of high-density lipoprotein.

PubMed

Yokoyama, Shinji

2006-01-01

Mammalian somatic cells do not catabolize cholesterol and need to export it for its homeostasis at the levels of cells and whole bodies. This reaction may reduce intracellularly accumulated cholesterol in excess and would contribute to prevention or regression of the initial stage of atherosclerosis. High-density lipoprotein (HDL) is thought to play a main role in this reaction, and 2 independent mechanisms are proposed for this reaction. First, cholesterol is exchanged in a nonspecific physicochemical manner between cell surface and extracellular lipoproteins, and cholesterol esterification on HDL provides a driving force for net removal of cell cholesterol. Second, apolipoproteins directly interact with cells and generate HDL by removing cellular phospholipid and cholesterol. This reaction is a major source of plasma HDL and is mediated by a membrane protein, ABCA1. Lipid-free or lipid-poor helical apolipoproteins primarily recruit cellular phospholipid to assemble HDL particles, and cholesterol enrichment in these particles is regulated independently. ABCA1 is a rate-limiting factor of the HDL assembly and is regulated by transcriptional factors and posttranscriptional factors. Posttranscriptional regulation of ABCA1 includes modulation of its calpain-mediated degradation.

The structure of a cholesterol-trapping protein

Science.gov Websites

Date February 28, 2003 Date Berkeley Lab Science Beat Berkeley Lab Science Beat The structure of a Institute researchers determined the three-dimensional structure of a protein that controls cholesterol level in the bloodstream. Knowing the structure of the protein, a cellular receptor that ensnares

Cholesterol and Fatty Acids Regulate Dynamic Caveolin Trafficking through the Golgi Complex and between the Cell Surface and Lipid BodiesV⃞

PubMed Central

Pol, Albert; Martin, Sally; Fernández, Manuel A.; Ingelmo-Torres, Mercedes; Ferguson, Charles; Enrich, Carlos; Parton, Robert G.

2005-01-01

Caveolins are a crucial component of plasma membrane (PM) caveolae but have also been localized to intracellular compartments, including the Golgi complex and lipid bodies. Mutant caveolins associated with human disease show aberrant trafficking to the PM and Golgi accumulation. We now show that the Golgi pool of mainly newly synthesized protein is detergent-soluble and predominantly in a monomeric state, in contrast to the surface pool. Caveolin at the PM is not recognized by specific caveolin antibodies unless PM cholesterol is depleted. Exit from the Golgi complex of wild-type caveolin-1 or -3, but not vesicular stomatitis virus-G protein, is modulated by changing cellular cholesterol levels. In contrast, a muscular dystrophy-associated mutant of caveolin-3, Cav3P104L, showed increased accumulation in the Golgi complex upon cholesterol treatment. In addition, we demonstrate that in response to fatty acid treatment caveolin can follow a previously undescribed pathway from the PM to lipid bodies and can move from lipid bodies to the PM in response to removal of fatty acids. The results suggest that cholesterol is a rate-limiting component for caveolin trafficking. Changes in caveolin flux through the exocytic pathway can therefore be an indicator of cellular cholesterol and fatty acid levels. PMID:15689493

The GARP Complex Is Involved in Intracellular Cholesterol Transport via Targeting NPC2 to Lysosomes.

PubMed

Wei, Jian; Zhang, Ying-Yu; Luo, Jie; Wang, Ju-Qiong; Zhou, Yu-Xia; Miao, Hong-Hua; Shi, Xiong-Jie; Qu, Yu-Xiu; Xu, Jie; Li, Bo-Liang; Song, Bao-Liang

2017-06-27

Proper intracellular cholesterol trafficking is critical for cellular function. Two lysosome-resident proteins, NPC1 and NPC2, mediate the egress of low-density lipoprotein-derived cholesterol from lysosomes. However, other proteins involved in this process remain largely unknown. Through amphotericin B-based selection, we isolated two cholesterol transport-defective cell lines. Subsequent whole-transcriptome-sequencing analysis revealed two cell lines bearing the same mutation in the vacuolar protein sorting 53 (Vps53) gene. Depletion of VPS53 or other subunits of the Golgi-associated retrograde protein (GARP) complex impaired NPC2 sorting to lysosomes and caused cholesterol accumulation. GARP deficiency blocked the retrieval of the cation-independent mannose 6-phosphate receptor (CI-MPR) to the trans-Golgi network. Further, Vps54 mutant mice displayed reduced cellular NPC2 protein levels and increased cholesterol accumulation, underscoring the physiological role of the GARP complex in cholesterol transport. We conclude that the GARP complex contributes to intracellular cholesterol transport by targeting NPC2 to lysosomes in a CI-MPR-dependent manner. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Necroptosis-like Neuronal Cell Death Caused by Cellular Cholesterol Accumulation.

PubMed

Funakoshi, Takeshi; Aki, Toshihiko; Tajiri, Masateru; Unuma, Kana; Uemura, Koichi

2016-11-25

Aberrant cellular accumulation of cholesterol is associated with neuronal lysosomal storage disorders such as Niemann-Pick disease Type C (NPC). We have shown previously that l-norephedrine (l-Nor), a sympathomimetic amine, induces necrotic cell death associated with massive cytoplasmic vacuolation in SH-SY5Y human neuroblastoma cells. To reveal the molecular mechanism underling necrotic neuronal cell death caused by l-Nor, we examined alterations in the gene expression profile of cells during l-Nor exposure. DNA microarray analysis revealed that the gene levels for cholesterol transport (LDL receptor and NPC2) as well as cholesterol biosynthesis (mevalonate pathway enzymes) are increased after exposure to 3 mm l-Nor for ∼6 h. Concomitant with this observation, the master transcriptional regulator of cholesterol homeostasis, SREBP-2, is activated by l-Nor. The increase in cholesterol uptake as well as biosynthesis is not accompanied by an increase in cholesterol in the plasma membrane, but rather by aberrant accumulation in cytoplasmic compartments. We also found that cell death by l-Nor can be suppressed by nec-1s, an inhibitor of a regulated form of necrosis, necroptosis. Abrogation of SREBP-2 activation by the small molecule inhibitor betulin or by overexpression of dominant-negative SREBP-2 efficiently reduces cell death by l-Nor. The mobilization of cellular cholesterol in the presence of cyclodextrin also suppresses cell death. These results were also observed in primary culture of striatum neurons. Taken together, our results indicate that the excessive uptake as well as synthesis of cholesterol should underlie neuronal cell death by l-Nor exposure, and suggest a possible link between lysosomal cholesterol storage disorders and the regulated form of necrosis in neuronal cells. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Necroptosis-like Neuronal Cell Death Caused by Cellular Cholesterol Accumulation*

PubMed Central

Funakoshi, Takeshi; Aki, Toshihiko; Tajiri, Masateru; Unuma, Kana; Uemura, Koichi

2016-01-01

Aberrant cellular accumulation of cholesterol is associated with neuronal lysosomal storage disorders such as Niemann-Pick disease Type C (NPC). We have shown previously that l-norephedrine (l-Nor), a sympathomimetic amine, induces necrotic cell death associated with massive cytoplasmic vacuolation in SH-SY5Y human neuroblastoma cells. To reveal the molecular mechanism underling necrotic neuronal cell death caused by l-Nor, we examined alterations in the gene expression profile of cells during l-Nor exposure. DNA microarray analysis revealed that the gene levels for cholesterol transport (LDL receptor and NPC2) as well as cholesterol biosynthesis (mevalonate pathway enzymes) are increased after exposure to 3 mm l-Nor for ∼6 h. Concomitant with this observation, the master transcriptional regulator of cholesterol homeostasis, SREBP-2, is activated by l-Nor. The increase in cholesterol uptake as well as biosynthesis is not accompanied by an increase in cholesterol in the plasma membrane, but rather by aberrant accumulation in cytoplasmic compartments. We also found that cell death by l-Nor can be suppressed by nec-1s, an inhibitor of a regulated form of necrosis, necroptosis. Abrogation of SREBP-2 activation by the small molecule inhibitor betulin or by overexpression of dominant-negative SREBP-2 efficiently reduces cell death by l-Nor. The mobilization of cellular cholesterol in the presence of cyclodextrin also suppresses cell death. These results were also observed in primary culture of striatum neurons. Taken together, our results indicate that the excessive uptake as well as synthesis of cholesterol should underlie neuronal cell death by l-Nor exposure, and suggest a possible link between lysosomal cholesterol storage disorders and the regulated form of necrosis in neuronal cells. PMID:27756839

In Situ Probing of Cholesterol in Astrocytes at the Single Cell Level using Laser Desorption Ionization Mass Spectrometric Imaging with Colloidal Silver

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdian, D.C.; Cha, Sangwon; Oh, Jisun

2010-03-18

Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations atmore » the cellular level.« less

Ezetimibe suppresses cholesterol accumulation in lipid-loaded vascular smooth muscle cells in vitro via MAPK signaling

PubMed Central

Qin, Li; Yang, Yun-bo; Yang, Yi-xin; Zhu, Neng; Gong, Yong-zhen; Zhang, Cai-ping; Li, Shun-xiang; Liao, Duan-fang

2014-01-01

Aim: To investigate the mechanisms of anti-atherosclerotic action of ezetimibe in rat vascular smooth muscle cells (VSMCs) in vitro. Methods: VSMCs of SD rats were cultured in the presence of Chol:MβCD (10 μg/mL) for 72 h, and intracellular lipid droplets and cholesterol levels were evaluated using Oil Red O staining, HPLC and Enzymatic Fluorescence Assay, respectively. The expression of caveolin-1, sterol response element-binding protein-1 (SREBP-1) and ERK1/2 were analyzed using Western blot assays. Translocation of SREBP-1 and ERK1/2 was detected with immunofluorescence. Results: Treatment with Chol:MβCD dramatically increased the cellular levels of total cholesterol (TC), cholesterol ester (CE) and free cholesterol (FC) in VSMCs, which led to the formation of foam cells. Furthermore, Chol:MβCD treatment significantly decreased the expression of caveolin-1, and stimulated the expression and nuclear translocation of SREBP-1 in VSMCs. Co-treatment with ezetimibe (3 μmol/L) significantly decreased the cellular levels of TC, CE and FC, which was accompanied by elevation of caveolin-1 expression, and by a reduction of SREBP-1 expression and nuclear translocation. Co-treatment with ezetimibe dose-dependently decreased the expression of phosphor-ERK1/2 (p-ERK1/2) in VSMCs. The ERK1/2 inhibitor PD98059 (50 μmol/L) altered the cholesterol level and the expression of p-ERK1/2, SREBP-1 and caveolin-1 in the same manner as ezetimibe did. Conclusion: Ezetimibe suppresses cholesterol accumulation in rat VSMCs in vitro by regulating SREBP-1 and caveolin-1 expression, possibly via the MAPK signaling pathway. PMID:25087996

Membrane order in the plasma membrane and endocytic recycling compartment.

PubMed

Iaea, David B; Maxfield, Frederick R

2017-01-01

The cholesterol content of membranes plays an important role in organizing membranes for signal transduction and protein trafficking as well as in modulating the biophysical properties of membranes. While the properties of model or isolated membranes have been extensively studied, there has been little evaluation of internal membranes in living cells. Here, we use a Nile Red based probe, NR12S, and ratiometric live cell imaging, to analyze the membrane order of the plasma membrane and endocytic recycling compartment. We find that after a brief incubation to allow endocytosis, NR12S is distributed between the plasma membrane and the endocytic recycling compartment. The NR12S reports that the endocytic recycling compartment is more highly ordered than the plasma membrane. We also find that the plasma membrane and the endocytic recycling compartment are differentially affected by altering cellular cholesterol levels. The membrane order of the plasma membrane, but not the endocytic recycling compartment, is altered significantly when cellular cholesterol content is increased or decreased by 20%. These results demonstrate that changes in cellular cholesterol differentially alter membrane order within different organelles.

Membrane order in the plasma membrane and endocytic recycling compartment

PubMed Central

Iaea, David B.; Maxfield, Frederick R.

2017-01-01

The cholesterol content of membranes plays an important role in organizing membranes for signal transduction and protein trafficking as well as in modulating the biophysical properties of membranes. While the properties of model or isolated membranes have been extensively studied, there has been little evaluation of internal membranes in living cells. Here, we use a Nile Red based probe, NR12S, and ratiometric live cell imaging, to analyze the membrane order of the plasma membrane and endocytic recycling compartment. We find that after a brief incubation to allow endocytosis, NR12S is distributed between the plasma membrane and the endocytic recycling compartment. The NR12S reports that the endocytic recycling compartment is more highly ordered than the plasma membrane. We also find that the plasma membrane and the endocytic recycling compartment are differentially affected by altering cellular cholesterol levels. The membrane order of the plasma membrane, but not the endocytic recycling compartment, is altered significantly when cellular cholesterol content is increased or decreased by 20%. These results demonstrate that changes in cellular cholesterol differentially alter membrane order within different organelles. PMID:29125865

In situ probing of cholesterol in astrocytes at the single-cell level using laser desorption ionization mass spectrometric imaging with colloidal silver.

PubMed

Perdian, D C; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S; Yeung, Edward S; Lee, Young Jin

2010-04-30

Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level. Published in 2010 by John Wiley & Sons, Ltd.

Release of cellular cholesterol: molecular mechanism for cholesterol homeostasis in cells and in the body.

PubMed

Yokoyama, S

2000-12-15

Most mammalian somatic cells are unable to catabolize cholesterol and therefore need to export it in order to maintain sterol homeostasis. This mechanism may also function to reduce excessively accumulated cholesterol, which would thereby contribute to prevention or cure of the initial stage of atherosclerotic vascular lesion. High-density lipoprotein (HDL) has been believed to play a main role in this reaction based on epidemiological evidence and in vitro experimental data. At least two independent mechanisms are identified for this reaction. One is non-specific diffusion-mediated cholesterol 'efflux' from cell surface. Cholesterol molecules desorbed from cells can be trapped by various extracellular acceptors including various lipoproteins and albumin, and extracellular cholesterol esterification mainly on HDL may provide a driving force for the net removal of cell cholesterol by maintaining a cholesterol gradient between lipoprotein surface and cell membrane. The other is apolipoprotein-mediated process to generate new HDL by removing cellular phospholipid and cholesterol. The reaction is initiated by the interaction of lipid-free or lipid-poor helical apolipoproteins with cellular surface resulting in assembly of HDL particles with cellular phospholipid and incorporation of cellular cholesterol into the HDL being formed. Thus, HDL has dual functions as an active cholesterol acceptor in the diffusion-mediated pathway and as an apolipoprotein carrier for the HDL assembly reaction. The impairment of the apolipoprotein-mediated reaction was found in Tangier disease and other familial HDL deficiencies to strongly suggest that this is a main mechanism to produce plasma HDL. The causative mutations for this defect was identified in ATP binding cassette transporter protein A1, as a significant step for further understanding of the reaction and cholesterol homeostasis.

Serum starvation of ARPE-19 changes the cellular distribution of cholesterol and Fibulin3 in patterns reminiscent of age-related macular degeneration.

PubMed

Rajapakse, Dinusha; Peterson, Katherine; Mishra, Sanghamitra; Wistow, Graeme

2017-12-15

Retinal pigment epithelium (RPE) has been implicated as key source of cholesterol-rich deposits at Bruch's membrane (BrM) and in drusen in aging human eye. We have shown that serum-deprivation of confluent RPE cells is associated with upregulation of cholesterol synthesis and accumulation of unesterified cholesterol (UC). Here we investigate the cellular processes involved in this response. We compared the distribution and localization of UC and esterified cholesterol (EC); the age-related macular degeneration (AMD) associated EFEMP1/Fibulin3 (Fib3); and levels of acyl-coenzyme A (CoA): cholesterol acyltransferases (ACAT) ACAT1, ACAT2 and Apolipoprotein B (ApoB) in ARPE-19 cells cultured in serum-supplemented and serum-free media. The results were compared with distributions of these lipids and proteins in human donor eyes with AMD. Serum deprivation of ARPE-19 was associated with increased formation of FM dye-positive membrane vesicles, many of which co-labeled for UC. Additionally, UC colocalized with Fib3 in distinct granules. By day 5, serum-deprived cells grown on transwells secreted Fib3 basally into the matrix. While mRNA and protein levels of ACTA1 were constant over several days of serum-deprivation, ACAT2 levels increased significantly after serum-deprivation, suggesting increased formation of EC. The lower levels of intracellular EC observed under serum-deprivation were associated with increased formation and secretion of ApoB. The responses to serum-deprivation in RPE-derived cells: accumulation and secretion of lipids, lipoproteins, and Fib3 are very similar to patterns seen in human donor eyes with AMD and suggest that this model mimics processes relevant to disease progression. Published by Elsevier Inc.

The Effects of Altered Membrane Cholesterol Levels on Sodium Pump Activity in Subclinical Hypothyroidism.

PubMed

Roy, Suparna; Dasgupta, Anindya

2017-03-01

Metabolic dysfunctions characteristic of overt hypothyroidism (OH) start at the early stage of subclinical hypothyroidism (SCH). Na⁺/K⁺-ATPase (the sodium pump) is a transmembrane enzyme that plays a vital role in cellular activities in combination with membrane lipids. We evaluated the effects of early changes in thyroid hormone and membrane cholesterol on sodium pump activity in SCH and OH patients. In 32 SCH patients, 35 OH patients, and 34 euthyroid patients, sodium pump activity and cholesterol levels in red blood cell membranes were measured. Serum thyroxine (T₄) and thyroid stimulating hormone (TSH) levels were measured using enzyme-linked immunosorbent assays. Differences in their mean values were analysed using post hoc analysis of variance. We assessed the dependence of the sodium pump on other metabolites by multiple regression analysis. Sodium pump activity and membrane cholesterol were lower in both hypothyroid groups than in control group, OH group exhibiting lower values than SCH group. In SCH group, sodium pump activity showed a significant direct dependence on membrane cholesterol with an inverse relationship with serum TSH levels. In OH group, sodium pump activity depended directly on membrane cholesterol and serum T₄ levels. No dependence on serum cholesterol was observed in either case. Despite the presence of elevated serum cholesterol in hypothyroidism, membrane cholesterol contributed significantly to maintain sodium pump activity in the cells. A critical reduction in membrane cholesterol levels heralds compromised enzyme activity, even in the early stage of hypothyroidism, and this can be predicted by elevated TSH levels alone, without any evident clinical manifestations. Copyright © 2017 Korean Endocrine Society

Cellular cholesterol regulates ubiquitination and degradation of the cholesterol export proteins ABCA1 and ABCG1.

PubMed

Hsieh, Victar; Kim, Mi-Jurng; Gelissen, Ingrid C; Brown, Andrew J; Sandoval, Cecilia; Hallab, Jeannette C; Kockx, Maaike; Traini, Mathew; Jessup, Wendy; Kritharides, Leonard

2014-03-14

The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes.

Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1*

PubMed Central

Hsieh, Victar; Kim, Mi-Jurng; Gelissen, Ingrid C.; Brown, Andrew J.; Sandoval, Cecilia; Hallab, Jeannette C.; Kockx, Maaike; Traini, Mathew; Jessup, Wendy; Kritharides, Leonard

2014-01-01

The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes. PMID:24500716

Static pressure accelerates ox-LDL-induced cholesterol accumulation via SREBP-1-mediated caveolin-1 downregulation in cultured vascular smooth muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Di-xian, E-mail: luodixian_2@163.com; Institute of Pharmacy and Pharmacology, College of Science and Technology, University of South China, Hengyang 421001, Hunan; First People's Hospital of Chenzhou City, Chenzhou 423000, Hunan

Research highlights: {yields} Vertical static pressure accelerates ox-LDL-induced cholesterol accumulation in cultured vascular smooth muscle cells. {yields} Static pressure induces SREBP-1 activation. {yields} Static pressure downregulates the expressions of caveolin-1 by activating SREBP-1. {yields} Static pressure also downregulates the transcription of ABCA1 by activating SREBP-1. {yields} Static pressure increases ox-LDL-induced cholesterol accumulation by SREBP-1-mediated caveolin-1 downregulation in vascular smooth muscle cells cultured in vitro. -- Abstract: Objective: To investigate the effect of static pressure on cholesterol accumulation in vascular smooth muscle cells (VSMCs) and its mechanism. Methods: Rat-derived VSMC cell line A10 treated with 50 mg/L ox-LDL and different staticmore » pressures (0, 60, 90, 120, 150, 180 mm Hg) in a custom-made pressure incubator for 48 h. Intracellular lipid droplets and lipid levels were assayed by oil red O staining and HPLC; The mRNA levels of caveolin-1 and ABCA1, the protein levels of caveolin-1 SREBP-1 and mature SREBP-1 were respectively detected by RT-PCR or western blot. ALLN, an inhibitor of SREBP metabolism, was used to elevate SREBP-1 protein level in VSMCs treated with static pressure. Results: Static pressures significantly not only increase intracellular lipid droplets in VSMCs, but also elevate cellular lipid content in a pressure-dependent manner. Intracellular free cholesterol (FC), cholesterol ester (CE), total cholesterol (TC) were respectively increased from 60.5 {+-} 2.8 mg/g, 31.8 {+-} 0.7 mg/g, 92.3 {+-} 2.1 mg/g at atmosphere pressure (ATM, 0 mm Hg) to 150.8 {+-} 9.4 mg/g, 235.9 {+-} 3.0 mg/g, 386.7 {+-} 6.4 mg/g at 180 mm Hg. At the same time, static pressures decrease the mRNA and protein levels of caveolin-1, and induce the activation and nuclear translocation of SREBP-1. ALLN increases the protein level of mature SREBP-1 and decreases caveolin-1 expression, so that cellular lipid levels were upregulated. Conclusion: Static pressures stimulate ox-LDL-induced cholesterol accumulation in cultured VSMCs through decreasing caveolin-1 expression via inducing the maturation and nuclear translocation of SREBP-1.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Lei; Xiao, Yongsheng; Wang, Yinsheng, E-mail: yinsheng.wang@ucr.edu

Human exposure to arsenic in drinking water is a widespread public health concern, and such exposure is known to be associated with many human diseases. The detailed molecular mechanisms about how arsenic species contribute to the adverse human health effects, however, remain incompletely understood. Monomethylarsonous acid [MMA(III)] is a highly toxic and stable metabolite of inorganic arsenic. To exploit the mechanisms through which MMA(III) exerts its cytotoxic effect, we adopted a quantitative proteomic approach, by coupling stable isotope labeling by amino acids in cell culture (SILAC) with LC-MS/MS analysis, to examine the variation in the entire proteome of GM00637 humanmore » skin fibroblasts following acute MMA(III) exposure. Among the ∼ 6500 unique proteins quantified, ∼ 300 displayed significant changes in expression after exposure with 2 μM MMA(III) for 24 h. Subsequent analysis revealed the perturbation of de novo cholesterol biosynthesis, selenoprotein synthesis and Nrf2 pathways evoked by MMA(III) exposure. Particularly, MMA(III) treatment resulted in considerable down-regulation of several enzymes involved in cholesterol biosynthesis. In addition, real-time PCR analysis showed reduced mRNA levels of select genes in this pathway. Furthermore, MMA(III) exposure contributed to a distinct decline in cellular cholesterol content and significant growth inhibition of multiple cell lines, both of which could be restored by supplementation of cholesterol to the culture media. Collectively, the present study demonstrated that the cytotoxicity of MMA(III) may arise, at least in part, from the down-regulation of cholesterol biosynthesis enzymes and the resultant decrease of cellular cholesterol content. - Highlights: • MMA(III)-induced perturbation of the entire proteome of GM00637 cells is studied. • Quantitative proteomic approach revealed alterations of multiple cellular pathways. • MMA(III) inhibits de novo cholesterol biosynthesis. • MMA(III) perturbs Nrf2 pathway and selenoprotein synthesis.« less

27-Hydroxycholesterol upregulates the production of heat shock protein 60 of monocytic cells.

PubMed

Kim, Bo-Young; Son, Yonghae; Choi, Jeongyoon; Eo, Seong-Kug; Park, Young Chul; Kim, Koanhoi

2017-09-01

Investigating differentially expressed proteins in a milieu rich in cholesterol oxidation products, we found via mass spectrometry-based proteomics that surface levels of heat shock protein 60 (HSP60) were upregulated on monocytic cells in the presence of 27-hydroxycholesterol (27OHChol). The elevated levels of cytoplasmic membrane HSP60 were verified via Western blot analysis and visualized by confocal microscopy. Treatment with 27OHChol also resulted in increased levels of cellular HSP60 without altering its transcription. Cholesterol, however, did not affect cell-surface levels and cellular amount of HSP60. GSK 2033, an LXR antagonist, inhibited expression of live X receptor α, but not of HSP60, induced by 27OHChol. Treatment with 27OHChol also resulted in increased release of HSP60 from monocytic cells, but the release was significantly reduced by inhibitors of endoplasmic reticulum-Golgi protein trafficking, brefeldin A and monensin. Results of the current study indicate that 27OHChol upregulates not only cell-surface and cellular levels of HSP60 but also its release from monocytic cells, thereby contributing to activation of the immune system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Blood lipids, homocysteine, stress factors, and vitamins in clinically stable multiple sclerosis patients

PubMed Central

2010-01-01

Multiple Sclerosis (MS) patients present a decrease of antioxidants and neuroprotective and immunoregulatory vitamins and an increase of total homocysteine (tHcy), cholesterol (CHL), HDL-cholesterol, and of cellular stress markers, variably associated with the different phases of the disease. We compared the blood levels of uric acid, folic acid, vitamins B12, A, and E, tHcy, CHL, HDL-cholesterol, and triglycerides in forty MS patients during a phase of clinical inactivity with those of eighty healthy controls, matched for age and sex. We found higher levels of tHcy (p = 0.032) and of HDL-cholesterol (p = 0.001) and lower levels of vitamin E (p = 0.001) and the ratio vitamin E/CHL (p = 0.001) in MS patients. In conclusion, modifications of some biochemical markers of cell damage were detected in MS patients during a phase of clinical inactivity. PMID:20163740

Knockdown of FABP5 mRNA decreases cellular cholesterol levels and results in decreased apoB100 secretion and triglyceride accumulation in ARPE-19 cells

PubMed Central

Wu, Tinghuai; Tian, Jane; Cutler, Roy G.; Telljohann, Richard S.; Bernlohr, David; Mattson, Mark P.; Handa, James T.

2010-01-01

To maintain normal retinal function, retinal pigment epithelial (RPE) cells engulf photoreceptor outer segments (ROS) enriched in free fatty acids (FFAs). We have previously demonstrated fatty acid-binding protein 5 (FABP5) down-regulation in the RPE/choroidal complex in a mouse model of aging and early age-related macular degeneration. FABPs are involved in intracellular transport of FFAs and their targeting to specific metabolic pathways. To elucidate the role of FABP5 in lipid metabolism, the production of the FABP5 protein in a human RPE cell line was inhibited using RNA interference technology. As a result, the levels of cholesterol and cholesterol ester were decreased by about 40%, whereas FFAs and triglycerides were increased by 18 and 67% after siRNA treatment, respectively. Some species of phospholipids were decreased in siRNA-treated cells. Cellular lipid droplets were evident and apoB secretion was decreased by 76% in these cells. Additionally, we discovered that ARPE-19 cells could synthesize and secrete Apolipoprotein B100 (apoB100), which may serve as a backbone structure for the formation of lipoprotein particles in these cells. Our results indicate that FABP5 mRNA knockdown results in the accumulation of cellular triglycerides, decreased cholesterol levels, and reduced secretion of apoB100 protein and lipoprotein-like particles. These observations indicated that FABP5 plays a critical role in lipid metabolism in RPE cells, suggesting that FABP5 down-regulation in the RPE/choroid complex in vivo might contribute to aging and early age-related macular degeneration. PMID:19434059

Black pepper and piperine reduce cholesterol uptake and enhance translocation of cholesterol transporter proteins.

PubMed

Duangjai, Acharaporn; Ingkaninan, Kornkanok; Praputbut, Sakonwun; Limpeanchob, Nanteetip

2013-04-01

Black pepper (Piper nigrum L.) lowers blood lipids in vivo and inhibits cholesterol uptake in vitro, and piperine may mediate these effects. To test this, the present study aimed to compare actions of black pepper extract and piperine on (1) cholesterol uptake and efflux in Caco-2 cells, (2) the membrane/cytosol distribution of cholesterol transport proteins in these cells, and (3) the physicochemical properties of cholesterol micelles. Piperine or black pepper extract (containing the same amount of piperine) dose-dependently reduced cholesterol uptake into Caco-2 cells in a similar manner. Both preparations reduced the membrane levels of NPC1L1 and SR-BI proteins but not their overall cellular expression. Micellar cholesterol solubility of lipid micelles was unaffected except by 1 mg/mL concentration of black pepper extract. These data suggest that piperine is the active compound in black pepper and reduces cholesterol uptake by internalizing the cholesterol transporter proteins.

A novel intrinsically fluorescent probe for study of uptake and trafficking of 25-hydroxycholesterol[S

PubMed Central

Iaea, David B.; Gale, Sarah E.; Bielska, Agata A.; Krishnan, Kathiresan; Fujiwara, Hideji; Jiang, Hui; Maxfield, Frederick R.; Schlesinger, Paul H.; Covey, Douglas F.; Schaffer, Jean E.; Ory, Daniel S.

2015-01-01

Cholesterol homeostasis is regulated not only by cholesterol, but also by oxygenated cholesterol species, referred to as oxysterols. Side-chain oxysterols, such as 25-hydroxycholesterol (25-HC), regulate cholesterol homeostasis through feedback inhibition and feed-forward activation of transcriptional pathways that govern cholesterol synthesis, uptake, and elimination, as well as through direct nongenomic actions that modulate cholesterol accessibility in membranes. Elucidating the cellular distribution of 25-HC is required to understand its biological activity at the molecular level. However, studying oxysterol distribution and behavior within cells has proven difficult due to the lack of fluorescent analogs of 25-HC that retain its chemical and physical properties. To address this, we synthesized a novel intrinsically fluorescent 25-HC mimetic, 25-hydroxycholestatrienol (25-HCTL). We show that 25-HCTL modulates sterol homeostatic responses in a similar manner as 25-HC. 25-HCTL associates with lipoproteins in media and is taken up by cells through LDL-mediated endocytosis. In cultured cells, 25-HCTL redistributes among cellular membranes and, at steady state, has a similar distribution as cholesterol, being enriched in both the endocytic recycling compartment as well as the plasma membrane. Our findings indicate that 25-HCTL is a faithful fluorescent 25-HC mimetic that can be used to investigate the mechanisms through which 25-HC regulates sterol homeostatic pathways. PMID:26497473

Perfringolysin O Theta Toxin as a Tool to Monitor the Distribution and Inhomogeneity of Cholesterol in Cellular Membranes

PubMed Central

Maekawa, Masashi; Yang, Yanbo; Fairn, Gregory D.

2016-01-01

Cholesterol is an essential structural component of cellular membranes in eukaryotes. Cholesterol in the exofacial leaflet of the plasma membrane is thought to form membrane nanodomains with sphingolipids and specific proteins. Additionally, cholesterol is found in the intracellular membranes of endosomes and has crucial functions in membrane trafficking. Furthermore, cellular cholesterol homeostasis and regulation of de novo synthesis rely on transport via both vesicular and non-vesicular pathways. Thus, the ability to visualize and detect intracellular cholesterol, especially in the plasma membrane, is critical to understanding the complex biology associated with cholesterol and the nanodomains. Perfringolysin O (PFO) theta toxin is one of the toxins secreted by the anaerobic bacteria Clostridium perfringens and this toxin forms pores in the plasma membrane that causes cell lysis. It is well understood that PFO recognizes and binds to cholesterol in the exofacial leaflets of the plasma membrane, and domain 4 of PFO (D4) is sufficient for the binding of cholesterol. Recent studies have taken advantage of this high-affinity cholesterol-binding domain to create a variety of cholesterol biosensors by using a non-toxic PFO or the D4 in isolation. This review highlights the characteristics and usefulness of, and the principal findings related to, these PFO-derived cholesterol biosensors. PMID:27005662

Perfringolysin O Theta Toxin as a Tool to Monitor the Distribution and Inhomogeneity of Cholesterol in Cellular Membranes.

PubMed

Maekawa, Masashi; Yang, Yanbo; Fairn, Gregory D

2016-03-08

Cholesterol is an essential structural component of cellular membranes in eukaryotes. Cholesterol in the exofacial leaflet of the plasma membrane is thought to form membrane nanodomains with sphingolipids and specific proteins. Additionally, cholesterol is found in the intracellular membranes of endosomes and has crucial functions in membrane trafficking. Furthermore, cellular cholesterol homeostasis and regulation of de novo synthesis rely on transport via both vesicular and non-vesicular pathways. Thus, the ability to visualize and detect intracellular cholesterol, especially in the plasma membrane, is critical to understanding the complex biology associated with cholesterol and the nanodomains. Perfringolysin O (PFO) theta toxin is one of the toxins secreted by the anaerobic bacteria Clostridium perfringens and this toxin forms pores in the plasma membrane that causes cell lysis. It is well understood that PFO recognizes and binds to cholesterol in the exofacial leaflets of the plasma membrane, and domain 4 of PFO (D4) is sufficient for the binding of cholesterol. Recent studies have taken advantage of this high-affinity cholesterol-binding domain to create a variety of cholesterol biosensors by using a non-toxic PFO or the D4 in isolation. This review highlights the characteristics and usefulness of, and the principal findings related to, these PFO-derived cholesterol biosensors.

Cholesterol Regulates μ-Opioid Receptor-Induced β-Arrestin 2 Translocation to Membrane Lipid RaftsS⃞

PubMed Central

Qiu, Yu; Wang, Yan; Chen, Hong-Zhuan; Loh, Horace H.

2011-01-01

μ-Opioid receptor (OPRM1) is mainly localized in lipid raft microdomains but internalizes through clathrin-dependent pathways. Our previous studies demonstrated that disruption of lipid rafts by cholesterol-depletion reagent blocked the agonist-induced internalization of OPRM1 and G protein-dependent signaling. The present study demonstrated that reduction of cholesterol level decreased and culturing cells in excess cholesterol increased the agonist-induced internalization and desensitization of OPRM1, respectively. Further analyses indicated that modulation of cellular cholesterol level did not affect agonist-induced receptor phosphorylation but did affect membrane translocation of β-arrestins. The translocation of β-arrestins was blocked by cholesterol reduction, and the effect could be reversed by incubating with cholesterol. OptiPrep gradient separation of lipid rafts revealed that excess cholesterol retained more receptors in lipid raft domains and facilitated the recruitment of β-arrestins to these microdomains upon agonist activation. Moreover, excess cholesterol could evoke receptor internalization and protein kinase C-independent extracellular signal-regulated kinases activation upon morphine treatment. Therefore, these results suggest that cholesterol not only can influence OPRM1 localization in lipid rafts but also can effectively enhance the recruitment of β-arrestins and thereby affect the agonist-induced trafficking and agonist-dependent signaling of OPRM1. PMID:21518774

Targeting cholesterol synthesis increases chemoimmuno-sensitivity in chronic lymphocytic leukemia cells

PubMed Central

2014-01-01

Background Cholesterol plays an important role in cancer development, drug resistance and chemoimmuno-sensitivity. Statins, cholesterol lowering drugs, can induce apoptosis, but also negatively interfere with CD-20 and rituximab-mediated activity. Our goal is to identify the alternative targets that could reduce cholesterol levels but do not interfere with CD-20 in chemo immunotherapy of chronic lymphocytic leukemia (CLL). Methods MEC-2 cells, a CLL cell line, and the peripheral blood mononuclear cells (PBMCs) from CLL patients were treated with cholesterol lowering agents, and analyzed the effect of these agents on cholesterol levels, CD-20 expression and distribution, and cell viability in the presence or absence of fludarabine, rituximab or their combinations. Results We found that MEC-2 cells treated with cholesterol lowering agents (BIBB-515, YM-53601 or TAK-475) reduced 20% of total cellular cholesterol levels, but also significantly promoted CD-20 surface expression. Furthermore, treatment of cells with fludarabine, rituximab or their combinations in the presence of BIBB-515, YM-53601 or TAK-475 enhanced MEC-2 cell chemoimmuno-sensitivity measured by cell viability. More importantly, these cholesterol lowering agents also significantly enhanced chemoimmuno-sensitivity of the PBMCs from CLL patients. Conclusion Our data demonstrate that BIBB-515, YM53601 and TAK-475 render chemoimmuno-therapy resistant MEC-2 cells sensitive to chemoimmuno-therapy and enhance CLL cell chemoimmuno-sensitivity without CD-20 epitope presentation or its downstream signaling. These results provide a novel strategy which could be applied to CLL treatment. PMID:25401046

Targeting cholesterol synthesis increases chemoimmuno-sensitivity in chronic lymphocytic leukemia cells.

PubMed

Benakanakere, Indira; Johnson, Tyler; Sleightholm, Richard; Villeda, Virgilio; Arya, Monika; Bobba, Ravi; Freter, Carl; Huang, Chunfa

2014-01-01

Cholesterol plays an important role in cancer development, drug resistance and chemoimmuno-sensitivity. Statins, cholesterol lowering drugs, can induce apoptosis, but also negatively interfere with CD-20 and rituximab-mediated activity. Our goal is to identify the alternative targets that could reduce cholesterol levels but do not interfere with CD-20 in chemo immunotherapy of chronic lymphocytic leukemia (CLL). MEC-2 cells, a CLL cell line, and the peripheral blood mononuclear cells (PBMCs) from CLL patients were treated with cholesterol lowering agents, and analyzed the effect of these agents on cholesterol levels, CD-20 expression and distribution, and cell viability in the presence or absence of fludarabine, rituximab or their combinations. We found that MEC-2 cells treated with cholesterol lowering agents (BIBB-515, YM-53601 or TAK-475) reduced 20% of total cellular cholesterol levels, but also significantly promoted CD-20 surface expression. Furthermore, treatment of cells with fludarabine, rituximab or their combinations in the presence of BIBB-515, YM-53601 or TAK-475 enhanced MEC-2 cell chemoimmuno-sensitivity measured by cell viability. More importantly, these cholesterol lowering agents also significantly enhanced chemoimmuno-sensitivity of the PBMCs from CLL patients. Our data demonstrate that BIBB-515, YM53601 and TAK-475 render chemoimmuno-therapy resistant MEC-2 cells sensitive to chemoimmuno-therapy and enhance CLL cell chemoimmuno-sensitivity without CD-20 epitope presentation or its downstream signaling. These results provide a novel strategy which could be applied to CLL treatment.

Depletion of cellular cholesterol interferes with intracellular trafficking of liposome-encapsulated ovalbumin.

PubMed

Rao, Mangala; Peachman, Kristina K; Alving, Carl R; Rothwell, Stephen W

2003-12-01

Cholesterol is a major constituent of plasma cell membranes and influences the functions of proteins residing in the membrane. To assess the role of cholesterol in phagocytosis and intracellular trafficking of liposomal antigen, macrophages were treated with inhibitors of cholesterol biosynthesis for various time periods and levels of cholesterol depletion were assessed by thin layer chromatography. In control macrophages, cholesterol was present in the plasma membrane and in intracellular stores, as visualised by staining with the cholesterol-binding compound filipin, whereas macrophages treated with cholesterol inhibitors failed to stain with filipin. However, these macrophages were still capable of phagocytosis as evidenced by their internalisation of fluorescent-labelled bacteria and liposome-encapsulated Texas red labelled-ovalbumin, L(TR-OVA). While fluorescent ovalbumin (OVA) was consistently transported to the Golgi in macrophages incubated with L(TR-OVA), in cells treated with cholesterol inhibitors, OVA remained spread diffusely throughout the cytoplasm. Even though the mean fluorescence intensity of MHC class I molecules on cholesterol inhibitor-treated macrophages was equivalent to that of the control macrophages, the amount of MHC class I-liposomal OVA-peptide complex detected on the cell surface of cholesterol inhibitor-treated macrophages, was only 45.6 +/- 7.4% (n = 4, mean +/- SEM) of control levels after intracellular processing of L(OVA). We conclude that cholesterol depletion does not eliminate phagocytosis or MHC class I surface expression, but does affect the trafficking and consequently the MHC class I antigen-processing pathway.

Structural analysis of alterations in zebrafish muscle differentiation induced by simvastatin and their recovery with cholesterol.

PubMed

Campos, Laise M; Rios, Eduardo A; Midlej, Victor; Atella, Georgia C; Herculano-Houzel, Suzana; Benchimol, Marlene; Mermelstein, Claudia; Costa, Manoel Luís

2015-06-01

In vitro studies show that cholesterol is essential to myogenesis. We have been using zebrafish to overcome the limitations of the in vitro approach and to study the sub-cellular structures and processes involved during myogenesis. We use simvastatin--a drug widely used to prevent high levels of cholesterol and cardiovascular disease--during zebrafish skeletal muscle formation. Simvastatin is an efficient inhibitor of cholesterol synthesis that has various myotoxic consequences. Here, we employed simvastatin concentrations that cause either mild or severe morphological disturbances to observe changes in the cytoskeleton (intermediate filaments and microfilaments), extracellular matrix and adhesion markers by confocal microscopy. With low-dose simvastatin treatment, laminin was almost normal, and alpha-actinin was reduced in the myofibrils. With high simvastatin doses, laminin and vinculin were reduced and appeared discontinuous along the septa, with almost no myofibrils, and small amounts of desmin accumulating close to the septa. We also analyzed sub-cellular alterations in the embryos by electron microscopy, and demonstrate changes in embryo and somite size, septa shape, and in myofibril structure. These effects could be reversed by the addition of exogenous cholesterol. These results contribute to the understanding of the mechanisms of action of simvastatin in muscle cells in particular, and in the study of myogenesis in general. © The Author(s) 2015.

Structural Analysis of Alterations in Zebrafish Muscle Differentiation Induced by Simvastatin and Their Recovery with Cholesterol

PubMed Central

Campos, Laise M.; Rios, Eduardo A.; Midlej, Victor; Atella, Georgia C.; Herculano-Houzel, Suzana; Benchimol, Marlene; Mermelstein, Claudia; Costa, Manoel Luís

2015-01-01

In vitro studies show that cholesterol is essential to myogenesis. We have been using zebrafish to overcome the limitations of the in vitro approach and to study the sub-cellular structures and processes involved during myogenesis. We use simvastatin—a drug widely used to prevent high levels of cholesterol and cardiovascular disease—during zebrafish skeletal muscle formation. Simvastatin is an efficient inhibitor of cholesterol synthesis that has various myotoxic consequences. Here, we employed simvastatin concentrations that cause either mild or severe morphological disturbances to observe changes in the cytoskeleton (intermediate filaments and microfilaments), extracellular matrix and adhesion markers by confocal microscopy. With low-dose simvastatin treatment, laminin was almost normal, and alpha-actinin was reduced in the myofibrils. With high simvastatin doses, laminin and vinculin were reduced and appeared discontinuous along the septa, with almost no myofibrils, and small amounts of desmin accumulating close to the septa. We also analyzed sub-cellular alterations in the embryos by electron microscopy, and demonstrate changes in embryo and somite size, septa shape, and in myofibril structure. These effects could be reversed by the addition of exogenous cholesterol. These results contribute to the understanding of the mechanisms of action of simvastatin in muscle cells in particular, and in the study of myogenesis in general. PMID:25786435

A sensitive assay for ABCA1-mediated cholesterol efflux using BODIPY -cholesterol

USDA-ARS?s Scientific Manuscript database

Studies have shown a negative association between cellular cholesterol efflux and coronary artery disease (CAD). Standard protocol for quantifying cholesterol efflux involves labeling cells with [(3)H]cholesterol and measuring release of the labeled sterol. Using [(3)H]cholesterol is not ideal for...

Oxysterol Signatures Distinguish Age-Related Macular Degeneration from Physiologic Aging.

PubMed

Lin, Jonathan B; Sene, Abdoulaye; Santeford, Andrea; Fujiwara, Hideji; Sidhu, Rohini; Ligon, Marianne M; Shankar, Vikram A; Ban, Norimitsu; Mysorekar, Indira U; Ory, Daniel S; Apte, Rajendra S

2018-06-11

Macrophage aging is pathogenic in numerous diseases, including age-related macular degeneration (AMD), a leading cause of blindness in older adults. Although prior studies have explored the functional consequences of macrophage aging, less is known about its cellular basis or what defines the transition from physiologic aging to disease. Here, we show that despite their frequent self-renewal, macrophages from old mice exhibited numerous signs of aging, such as impaired oxidative respiration. Transcriptomic profiling of aged murine macrophages revealed dysregulation of diverse cellular pathways, especially in cholesterol homeostasis, that manifested in altered oxysterol signatures. Although the levels of numerous oxysterols in human peripheral blood mononuclear cells and plasma exhibited age-associated changes, plasma 24-hydroxycholesterol levels were specifically associated with AMD. These novel findings demonstrate that oxysterol levels can discriminate disease from physiologic aging. Furthermore, modulation of cholesterol homeostasis may be a novel strategy for treating age-associated diseases in which macrophage aging is pathogenic. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Soya phytoestrogens, genistein and daidzein, decrease apolipoprotein B secretion from HepG2 cells through multiple mechanisms.

PubMed Central

Borradaile, Nica M; de Dreu, Linda E; Wilcox, Lisa J; Edwards, Jane Y; Huff, Murray W

2002-01-01

Diets containing the soya-derived phytoestrogens, genistein and daidzein, decrease plasma cholesterol in humans and experimental animals. The mechanisms responsible for the hypocholesterolaemic effects of these isoflavones are unknown. The present study was conducted to determine if genistein and daidzein regulate hepatocyte cholesterol metabolism and apolipoprotein (apo) B secretion in cultured human hepatoma (HepG2) cells. ApoB secretion was decreased dose-dependently by up to 63% and 71% by genistein and daidzein (100 microM; P<0.0001) respectively. In contrast, no effect on apoAI secretion was observed. Cellular cholesterol synthesis was inhibited 41% by genistein (100 microM; P<0.005) and 18% by daidzein (100 microM; P<0.05), which was associated with significant increases in 3-hydroxy-3-methylglutaryl-CoA reductase mRNA. Cellular cholesterol esterification was decreased 56% by genistein (100 microM; P<0.04) and 29% by daidzein (100 microM; P<0.04); however, mRNA levels for acyl-CoA:cholesterol acyltransferase (ACAT) 1 and ACAT2 were unaffected. At 100 microM, both isoflavones equally inhibited the activities of both forms of ACAT in cells transfected with either ACAT1 or ACAT2. Genistein (100 microM) and daidzein (100 microM) significantly decreased the activity of microsomal triacylglycerol transfer protein (MTP) by 30% and 24% respectively, and significantly decreased MTP mRNA levels by 35% and 55%. Both isoflavones increased low-density lipoprotein (LDL)-receptor mRNA levels by 3- to 6-fold (100 microM; P<0.03) and significantly increased the binding, uptake and degradation of (125)I-labelled LDL, suggesting that enhanced reuptake of newly secreted apoB-containing lipoproteins contributed to the net decrease in apoB secretion. These results indicate that genistein and daidzein inhibit hepatocyte apoB secretion through several mechanisms, including inhibition of cholesterol synthesis and esterification, inhibition of MTP activity and expression and increased expression of the LDL-receptor. PMID:12030847

Endocytosis of beta-cyclodextrins is responsible for cholesterol reduction in Niemann-Pick type C mutant cells

PubMed Central

Rosenbaum, Anton I.; Zhang, Guangtao; Warren, J. David; Maxfield, Frederick R.

2010-01-01

Niemann-Pick type C disease (NPC) is a lysosomal storage disorder causing accumulation of unesterified cholesterol in lysosomal storage organelles. Recent studies have shown that hydroxypropyl-β-cyclodextrin injections in npc1−/− mice are partially effective in treating this disease. Using cultured fibroblasts, we have investigated the cellular mechanisms responsible for reduction of cholesterol accumulation. We show that decreased levels of cholesterol accumulation are maintained for several days after removal of cyclodextrin from the culture medium. This suggests that endocytosed cyclodextrin can reduce the cholesterol storage by acting from inside endocytic organelles rather than by removing cholesterol from the plasma membrane. To test this further, we incubated both NPC1 and NPC2 mutant cells with cholesterol-loaded cyclodextrin for 1 h, followed by chase in serum-containing medium. Although the cholesterol content of the treated cells increased after the 1-h incubation, the cholesterol levels in the storage organelles were later reduced significantly. We covalently coupled cyclodextrin to fluorescent dextran polymers. These cyclodextrin–dextran conjugates were delivered to cholesterol-enriched lysosomal storage organelles and were effective at reducing the cholesterol accumulation. We demonstrate that methyl-β-cyclodextrin is more potent than hydroxypropyl-β-cyclodextrin in reducing both cholesterol and bis(monoacylglycerol) phosphate accumulation in NPC mutant fibroblasts. Brief treatment of cells with cyclodextrins causes an increase in cholesterol esterification by acyl CoA:cholesterol acyl transferase, indicating increased cholesterol delivery to the endoplasmic reticulum. These findings suggest that cyclodextrin-mediated enhanced cholesterol transport from the endocytic system can reduce cholesterol accumulation in cells with defects in either NPC1 or NPC2. PMID:20212119

Viral MicroRNAs Repress the Cholesterol Pathway, and 25-Hydroxycholesterol Inhibits Infection.

PubMed

Serquiña, Anna K P; Kambach, Diane M; Sarker, Ontara; Ziegelbauer, Joseph M

2017-07-11

From various screens, we found that Kaposi's sarcoma-associated herpesvirus (KSHV) viral microRNAs (miRNAs) target several enzymes in the mevalonate/cholesterol pathway. 3-Hydroxy-3-methylglutaryl-coenzyme A (CoA) synthase 1 (HMGCS1), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR [a rate-limiting step in the mevalonate pathway]), and farnesyl-diphosphate farnesyltransferase 1 (FDFT1 [a committed step in the cholesterol branch]) are repressed by multiple KSHV miRNAs. Transfection of viral miRNA mimics in primary endothelial cells (human umbilical vein endothelial cells [HUVECs]) is sufficient to reduce intracellular cholesterol levels; however, small interfering RNAs (siRNAs) targeting only HMGCS1 did not reduce cholesterol levels. This suggests that multiple targets are needed to perturb this tightly regulated pathway. We also report here that cholesterol levels were decreased in de novo -infected HUVECs after 7 days. This reduction is at least partially due to viral miRNAs, since the mutant form of KSHV lacking 10 of the 12 miRNA genes had increased cholesterol compared to wild-type infections. We hypothesized that KSHV is downregulating cholesterol to suppress the antiviral response by a modified form of cholesterol, 25-hydroxycholesterol (25HC). We found that the cholesterol 25-hydroxylase (CH25H) gene, which is responsible for generating 25HC, had increased expression in de novo -infected HUVECs but was strongly suppressed in long-term latently infected cell lines. We found that 25HC inhibits KSHV infection when added exogenously prior to de novo infection. In conclusion, we found that multiple KSHV viral miRNAs target enzymes in the mevalonate pathway to modulate cholesterol in infected cells during latency. This repression of cholesterol levels could potentially be beneficial to viral infection by decreasing the levels of 25HC. IMPORTANCE A subset of viruses express unique microRNAs (miRNAs), which act like cellular miRNAs to generally repress host gene expression. A cancer virus, Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8 [HHV-8]), encodes multiple miRNAs that repress gene expression of multiple enzymes that are important for cholesterol synthesis. In cells with these viral miRNAs or with natural infection, cholesterol levels are reduced, indicating these viral miRNAs decrease cholesterol levels. A modified form of cholesterol, 25-hydroxycholesterol, is generated directly from cholesterol. Addition of 25-hydroxycholesterol to primary cells inhibited KSHV infection of cells, suggesting that viral miRNAs may decrease cholesterol levels to decrease the concentration of 25-hydroxycholesterol and to promote infection. These results suggest a new virus-host relationship and indicate a previously unidentified viral strategy to lower cholesterol levels. Copyright © 2017 Serquiña et al.

Human genetic variation in VAC14 regulates Salmonella invasion and typhoid fever through modulation of cholesterol.

PubMed

Alvarez, Monica I; Glover, Luke C; Luo, Peter; Wang, Liuyang; Theusch, Elizabeth; Oehlers, Stefan H; Walton, Eric M; Tram, Trinh Thi Bich; Kuang, Yu-Lin; Rotter, Jerome I; McClean, Colleen M; Chinh, Nguyen Tran; Medina, Marisa W; Tobin, David M; Dunstan, Sarah J; Ko, Dennis C

2017-09-12

Risk, severity, and outcome of infection depend on the interplay of pathogen virulence and host susceptibility. Systematic identification of genetic susceptibility to infection is being undertaken through genome-wide association studies, but how to expeditiously move from genetic differences to functional mechanisms is unclear. Here, we use genetic association of molecular, cellular, and human disease traits and experimental validation to demonstrate that genetic variation affects expression of VAC14, a phosphoinositide-regulating protein, to influence susceptibility to Salmonella enterica serovar Typhi ( S Typhi) infection. Decreased VAC14 expression increased plasma membrane cholesterol, facilitating Salmonella docking and invasion. This increased susceptibility at the cellular level manifests as increased susceptibility to typhoid fever in a Vietnamese population. Furthermore, treating zebrafish with a cholesterol-lowering agent, ezetimibe, reduced susceptibility to S Typhi. Thus, coupling multiple genetic association studies with mechanistic dissection revealed how VAC14 regulates Salmonella invasion and typhoid fever susceptibility and may open doors to new prophylactic/therapeutic approaches.

Human genetic variation in VAC14 regulates Salmonella invasion and typhoid fever through modulation of cholesterol

PubMed Central

Alvarez, Monica I.; Glover, Luke C.; Luo, Peter; Wang, Liuyang; Theusch, Elizabeth; Oehlers, Stefan H.; Walton, Eric M.; Tram, Trinh Thi Bich; Kuang, Yu-Lin; Rotter, Jerome I.; McClean, Colleen M.; Chinh, Nguyen Tran; Medina, Marisa W.; Dunstan, Sarah J.

2017-01-01

Risk, severity, and outcome of infection depend on the interplay of pathogen virulence and host susceptibility. Systematic identification of genetic susceptibility to infection is being undertaken through genome-wide association studies, but how to expeditiously move from genetic differences to functional mechanisms is unclear. Here, we use genetic association of molecular, cellular, and human disease traits and experimental validation to demonstrate that genetic variation affects expression of VAC14, a phosphoinositide-regulating protein, to influence susceptibility to Salmonella enterica serovar Typhi (S. Typhi) infection. Decreased VAC14 expression increased plasma membrane cholesterol, facilitating Salmonella docking and invasion. This increased susceptibility at the cellular level manifests as increased susceptibility to typhoid fever in a Vietnamese population. Furthermore, treating zebrafish with a cholesterol-lowering agent, ezetimibe, reduced susceptibility to S. Typhi. Thus, coupling multiple genetic association studies with mechanistic dissection revealed how VAC14 regulates Salmonella invasion and typhoid fever susceptibility and may open doors to new prophylactic/therapeutic approaches. PMID:28827342

HDL cholesterol transport during inflammation.

PubMed

van der Westhuyzen, Deneys R; de Beer, Frederick C; Webb, Nancy R

2007-04-01

The aim of this article is to review recent advances made towards understanding how inflammation and acute phase proteins, particularly serum amyloid A and group IIa secretory phospholipase A2, may alter reverse cholesterol transport by HDL during inflammation and the acute phase response. Findings suggest that the decreased apoA-I content and markedly increased serum amyloid A content in HDL during the acute phase response result from reciprocal and coordinate transcriptional regulation of these proteins as well as HDL remodeling by group IIa secretory phospholipase A2. Serum amyloid A functions efficiently in a lipid-free or lipid-poor form to promote cholesterol efflux by ATP binding cassette protein ABCA1, evidently by functioning directly as an acceptor for cholesterol efflux as well as by increasing the availability of cellular free cholesterol. Serum amyloid A increases the ability of acute phase HDL to serve as an acceptor for SR-BI-dependent cellular cholesterol efflux. Altered remodeling of HDL by group IIa secretory phospholipase A2 in concert with cholesterol ester transfer protein may contribute to the generation of lipid-poor apoA-I and serum amyloid A acceptors for cholesterol efflux. Current data support a model for the acute phase response in which serum amyloid A and sPLA2-IIa, present at sites of inflammation and tissue damage, play a protective role by enhancing cellular cholesterol efflux, thereby promoting the removal of excess cholesterol from macrophages.

Remnant Cholesterol Elicits Arterial Wall Inflammation and a Multilevel Cellular Immune Response in Humans.

PubMed

Bernelot Moens, Sophie J; Verweij, Simone L; Schnitzler, Johan G; Stiekema, Lotte C A; Bos, Merijn; Langsted, Anne; Kuijk, Carlijn; Bekkering, Siroon; Voermans, Carlijn; Verberne, Hein J; Nordestgaard, Børge G; Stroes, Erik S G; Kroon, Jeffrey

2017-05-01

Mendelian randomization studies revealed a causal role for remnant cholesterol in cardiovascular disease. Remnant particles accumulate in the arterial wall, potentially propagating local and systemic inflammation. We evaluated the impact of remnant cholesterol on arterial wall inflammation, circulating monocytes, and bone marrow in patients with familial dysbetalipoproteinemia (FD). Arterial wall inflammation and bone marrow activity were measured using 18 F-FDG PET/CT. Monocyte phenotype was assessed with flow cytometry. The correlation between remnant levels and hematopoietic activity was validated in the CGPS (Copenhagen General Population Study). We found a 1.2-fold increase of 18 F-FDG uptake in the arterial wall in patients with FD (n=17, age 60±8 years, remnant cholesterol: 3.26 [2.07-5.71]) compared with controls (n=17, age 61±8 years, remnant cholesterol 0.29 [0.27-0.40]; P <0.001). Monocytes from patients with FD showed increased lipid accumulation (lipid-positive monocytes: Patients with FD 92% [86-95], controls 76% [66-81], P =0.001, with an increase in lipid droplets per monocyte), and a higher expression of surface integrins (CD11b, CD11c, and CD18). Patients with FD also exhibited monocytosis and leukocytosis, accompanied by a 1.2-fold increase of 18 F-FDG uptake in bone marrow. In addition, we found a strong correlation between remnant levels and leukocyte counts in the CGPS (n=103 953, P for trend 5×10-276). In vitro experiments substantiated that remnant cholesterol accumulates in human hematopoietic stem and progenitor cells coinciding with myeloid skewing. Patients with FD have increased arterial wall and cellular inflammation. These findings imply an important inflammatory component to the atherogenicity of remnant cholesterol, contributing to the increased cardiovascular disease risk in patients with FD. © 2017 American Heart Association, Inc.

Complementary probes reveal that phosphatidylserine is required for the proper transbilayer distribution of cholesterol.

PubMed

Maekawa, Masashi; Fairn, Gregory D

2015-04-01

Cholesterol is an essential component of metazoan cellular membranes and it helps to maintain the structural integrity and fluidity of the plasma membrane. Here, we developed a cholesterol biosensor, termed D4H, based on the fourth domain of Clostridium perfringens theta-toxin, which recognizes cholesterol in the cytosolic leaflet of the plasma membrane and organelles. The D4H probe disassociates from the plasma membrane upon cholesterol extraction and after perturbations in cellular cholesterol trafficking. When used in combination with a recombinant version of the biosensor, we show that plasmalemmal phosphatidylserine is essential for retaining cholesterol in the cytosolic leaflet of the plasma membrane. In vitro experiments reveal that 1-stearoy-2-oleoyl phosphatidylserine can induce phase separation in cholesterol-containing lipid bilayers and shield cholesterol from cholesterol oxidase. Finally, the altered transbilayer distribution of cholesterol causes flotillin-1 to relocalize to endocytic organelles. This probe should be useful in the future to study pools of cholesterol in the cytosolic leaflet of the plasma membrane and organelles. © 2015. Published by The Company of Biologists Ltd.

Angiogenin activates phospholipase C and elicits a rapid incorporation of fatty acid into cholesterol esters in vascular smooth muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, F.; Riordan, J.F.

1990-01-09

Angiogenin activates the phosphoinositide-specific phospholipase C (PLC) in cultured rat aortic smooth muscle cells to yield a transient (30 s) peak of 1,2-diacylglycerol (DG) and inositol trisphosphate. Within 1 min, the DG level falls below that of the control and remains so for at least 20 min. A transient increase in monoacylglycerol indicates that depletion of DG may be the consequence of hydrolysis by DG lipase. In addition to these changes in second messengers, a rapid increase in incorporating of radiolabeled tracer into cellular cholesterol esters is observed. Stimulated cholesterol ester labeling is inhibited by preincubation with either the DGmore » lipase inhibitor RHC 80267 or the acyl coenzyme A:cholesterol acyltransferase inhibitor Sandoz 58035. Cells prelabeled with ({sup 3}H)arachidonate show a sustained increase in labeling of cholesterol esters following exposure to angiogenin. In contrast, cells prelabeled with ({sup 3}H)oleate show only a transient elevation that returns to the basal level by 5 min. This suggests initial cholesterol esterification by oleate followed by arachidonate that is released by stimulation of the PLC/DG lipase pathway.« less

Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane

PubMed Central

Iaea, David B.; Mao, Shu; Lund, Frederik W.; Maxfield, Frederick R.

2017-01-01

Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t1/2 =12–15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC. PMID:28209730

α-Synuclein Regulates Neuronal Cholesterol Efflux.

PubMed

Hsiao, Jen-Hsiang T; Halliday, Glenda M; Kim, Woojin Scott

2017-10-19

α-Synuclein is a neuronal protein that is at the center of focus in understanding the etiology of a group of neurodegenerative diseases called α-synucleinopathies, which includes Parkinson's disease (PD). Despite much research, the exact physiological function of α-synuclein is still unclear. α-Synuclein has similar biophysical properties as apolipoproteins and other lipid-binding proteins and has a high affinity for cholesterol. These properties suggest a possible role for α-synuclein as a lipid acceptor mediating cholesterol efflux (the process of removing cholesterol out of cells). To test this concept, we "loaded" SK-N-SH neuronal cells with fluorescently-labelled cholesterol, applied exogenous α-synuclein, and measured the amount of cholesterol removed from the cells using a classic cholesterol efflux assay. We found that α-synuclein potently stimulated cholesterol efflux. We found that the process was dose and time dependent, and was saturable at 1.0 µg/mL of α-synuclein. It was also dependent on the transporter protein ABCA1 located on the plasma membrane. We reveal for the first time a novel role of α-synuclein that underscores its importance in neuronal cholesterol regulation, and identify novel therapeutic targets for controlling cellular cholesterol levels.

Triglycerides, total cholesterol, high density lipoprotein cholesterol and low density lipoprotein cholesterol in rats exposed to premium motor spirit fumes.

PubMed

Aberare, Ogbevire L; Okuonghae, Patrick; Mukoro, Nathaniel; Dirisu, John O; Osazuwa, Favour; Odigie, Elvis; Omoregie, Richard

2011-06-01

Deliberate and regular exposure to premium motor spirit fumes is common and could be a risk factor for liver disease in those who are occupationally exposed. A possible association between premium motor spirit fumes and plasma levels of triglyceride, total cholesterol, high density lipoprotein cholesterol and low density lipoprotein cholesterol using a rodent model could provide new insights in the pathology of diseases where cellular dysfunction is an established risk factor. The aim of this study was to evaluate the possible effect of premium motor spirit fumes on lipids and lipoproteins in workers occupationally exposed to premium motor spirit fumes using rodent model. Twenty-five Wister albino rats (of both sexes) were used for this study between the 4(th) of August and 7(th) of September, 2010. The rats were divided into five groups of five rats each. Group 1 rats were not exposed to premium motor spirit fumes (control group), group 2 rats were exposed for 1 hour daily, group 3 for 3 hours daily, group 4 for 5 hours daily and group 5 for 7 hours daily. The experiment lasted for a period of 4 weeks. Blood samples obtained from all the groups after 4 weeks of exposure were used for the estimation of plasma levels of triglyceride, total cholesterol, high density lipoprotein- cholesterol and low density lipoprotein- cholesterol. Results showed significant increase in means of plasma total cholesterol and low density lipoprotein levels (P<0.05). The mean triglyceride and total body weight were significantly lower (P<0.05) in the exposed group when compared with the unexposed. The plasma level of high density lipoprotein, the ratio of low density lipoprotein to high density lipoprotein and the ratio of total cholesterol to high density lipoprotein did not differ significantly in exposed subjects when compared with the control group. These results showed that frequent exposure to petrol fumes may be highly deleterious to the liver cells.

Diversity of glycosphingolipid GM2 and cholesterol accumulation in NPC1 patient-specific iPSC-derived neurons.

PubMed

Trilck, Michaela; Peter, Franziska; Zheng, Chaonan; Frank, Marcus; Dobrenis, Kostantin; Mascher, Hermann; Rolfs, Arndt; Frech, Moritz J

2017-02-15

Niemann-Pick disease Type C1 (NPC1) is a rare progressive neurodegenerative disorder caused by mutations in the NPC1 gene. On the cellular level NPC1 mutations lead to an accumulation of cholesterol and gangliosides. As a thorough analysis of the severely affected neuronal cells is unfeasible in NPC1 patients, we recently described the cellular phenotype of neuronal cells derived from NPC1 patient iPSCs carrying the compound heterozygous mutation c.1836A>C/c.1628delC. Here we expanded the analysis to cell lines carrying the prevalent mutation c.3182T>C and the novel mutation c.1180T>C, as well as to the determination of GM2 and GM3 gangliosides in NPC1 patient-specific iPSC-derived neurons and glia cells. Immunocytochemical detection of GM2 revealed punctated staining pattern predominantly localized in neurons. Detection of cholesterol by filipin staining showed a comparable staining pattern, colocalized with GM2, indicating a deposit of GM2 and cholesterol in the same cellular compartments. Accumulations were not only restricted to cell bodies, but were also found in the neuronal extensions. A quantification of the GM2 amount by HPLC-MS/MS confirmed significantly higher amounts in neurons carrying a mutation. Additionally, these cells displayed a lowered activity of the catabolic enzyme Hex A, but not B4GALNT1. Molecular docking simulations indicated binding of cholesterol to Hex A, suggesting cholesterol influences the GM2 degradation pathway and, subsequently, leading to the accumulation of GM2. Taken together, this is the first study showing an accumulation of GM2 in neuronal derivatives of patient-specific iPSCs and thus proving further disease-specific hallmarks in this human in vitro model of NPC1. Copyright © 2016 Elsevier B.V. All rights reserved.

Beneficial effects of cytokine induced hyperlipidemia.

PubMed

Feingold, K R; Hardardóttir, I; Grunfeld, C

1998-01-01

Infection, inflammation and trauma induce marked changes in the plasma levels of a wide variety of proteins (acute phase response), and these changes are mediated by cytokines. The acute phase response is thought to be beneficial to the host. The host's response to injury also results in dramatic alterations in lipid metabolism and circulating lipoprotein levels which are mediated by cytokines. A large number of cytokines including TNF, the interleukins, and the interferons increase serum triglyceride levels. This rapid increase (1-2 h) is predominantly due to an increase in hepatic VLDL secretion while the late increase may be due to a variety of factors including increased hepatic production of VLDL or delayed clearance secondary to a decrease in lipoprotein lipase activity and/or apolipoprotein E levels on VLDL. In animals other than primates, cytokines also increase serum cholesterol levels, most likely by increasing hepatic cholesterol. Cytokines increase hepatic cholesterol synthesis by stimulating HMG CoA reductase gene expression and decrease hepatic cholesterol catabolism by inhibiting cholesterol 7 alpha-hydroxylase, the key enzyme in bile acid synthesis. Injury and/or cytokines also decrease HDL cholesterol levels and induce alterations in the composition of HDL. The content of SAA and apolipoprotein J increase, apolipoprotein A1 may decrease, and the cholesterol ester content decreases while free cholesterol increases. Additionally, key proteins involved in HDL metabolism are altered by cytokines; LCAT activity, hepatic lipase activity, and CETP levels decrease. These changes in lipid and lipoprotein metabolism may be beneficial in a number of ways including: lipoproteins competing with viruses for cellular receptors, apolipoproteins neutralizing viruses, lipoproteins binding and targeting parasites for destruction, apolipoproteins lysing parasites, redistribution of nutrients to cells involved in the immune response and/or tissue repair, and lipoproteins binding toxic agents and neutralizing their harmful effects. Thus, cytokines induce marked changes in lipid metabolism that lead to hyperlipidemia which represents part of the innate immune response and may be beneficial to the host.

The 32-year relationship between cholesterol and dementia from midlife to late life.

PubMed

Mielke, M M; Zandi, P P; Shao, H; Waern, M; Östling, S; Guo, X; Björkelund, C; Lissner, L; Skoog, I; Gustafson, D R

2010-11-23

Cellular and animal studies suggest that hypercholesterolemia contributes to Alzheimer disease (AD). However, the relationship between cholesterol and dementia at the population level is less clear and may vary over the lifespan. The Prospective Population Study of Women, consisting of 1,462 women without dementia aged 38-60 years, was initiated in 1968-1969 in Gothenburg, Sweden. Follow-ups were conducted in 1974-1975, 1980-1981, 1992-1993, and 2000-2001. All-cause dementia was diagnosed according to DSM-III-R criteria and AD according to National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria. Cox proportional hazards regression examined baseline, time-dependent, and change in cholesterol levels in relation to incident dementia and AD among all participants. Analyses were repeated among participants who survived to the age of 70 years or older and participated in the 2000-2001 examination. Higher cholesterol level in 1968 was not associated with an increased risk of AD (highest vs lowest quartile: hazard ratio [HR] 2.82, 95% confidence interval [CI] 0.94-8.43) among those who survived to and participated in the 2000-2001 examination. While there was no association between cholesterol level and dementia when considering all participants over 32 years, a time-dependent decrease in cholesterol over the follow-up was associated with an increased risk of dementia (HR 2.35, 95% CI 1.22-4.58). These data suggest that midlife cholesterol level is not associated with an increased risk of AD. However, there may be a slight risk among those surviving to an age at risk for dementia. Declining cholesterol levels from midlife to late life may better predict AD risk than levels obtained at one timepoint prior to dementia onset. Analytic strategies examining this and other risk factors across the lifespan may affect interpretation of results.

A conserved degron containing an amphipathic helix regulates the cholesterol-mediated turnover of human squalene monooxygenase, a rate-limiting enzyme in cholesterol synthesis.

PubMed

Chua, Ngee Kiat; Howe, Vicky; Jatana, Nidhi; Thukral, Lipi; Brown, Andrew J

2017-12-08

Cholesterol biosynthesis in the endoplasmic reticulum (ER) is tightly controlled by multiple mechanisms to regulate cellular cholesterol levels. Squalene monooxygenase (SM) is the second rate-limiting enzyme in cholesterol biosynthesis and is regulated both transcriptionally and post-translationally. SM undergoes cholesterol-dependent proteasomal degradation when cholesterol is in excess. The first 100 amino acids of SM (designated SM N100) are necessary for this degradative process and represent the shortest cholesterol-regulated degron identified to date. However, the fundamental intrinsic characteristics of this degron remain unknown. In this study, we performed a series of deletions, point mutations, and domain swaps to identify a 12-residue region (residues Gln-62-Leu-73), required for SM cholesterol-mediated turnover. Molecular dynamics and circular dichroism revealed an amphipathic helix within this 12-residue region. Moreover, 70% of the variation in cholesterol regulation was dependent on the hydrophobicity of this region. Of note, the earliest known Doa10 yeast degron, Deg1, also contains an amphipathic helix and exhibits 42% amino acid similarity with SM N100. Mutating SM residues Phe-35/Ser-37/Leu-65/Ile-69 into alanine, based on the key residues in Deg1, blunted SM cholesterol-mediated turnover. Taken together, our results support a model whereby the amphipathic helix in SM N100 attaches reversibly to the ER membrane depending on cholesterol levels; with excess, the helix is ejected and unravels, exposing a hydrophobic patch, which then serves as a degradation signal. Our findings shed new light on the regulation of a key cholesterol synthesis enzyme, highlighting the conservation of critical degron features from yeast to humans. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Early steps in steroidogenesis: intracellular cholesterol trafficking

PubMed Central

Miller, Walter L.; Bose, Himangshu S.

2011-01-01

Steroid hormones are made from cholesterol, primarily derived from lipoproteins that enter cells via receptor-mediated endocytosis. In endo-lysosomes, cholesterol is released from cholesterol esters by lysosomal acid lipase (LAL; disordered in Wolman disease) and exported via Niemann-Pick type C (NPC) proteins (disordered in NPC disease). These diseases are characterized by accumulated cholesterol and cholesterol esters in most cell types. Mechanisms for trans-cytoplasmic cholesterol transport, membrane insertion, and retrieval from membranes are less clear. Cholesterol esters and “free” cholesterol are enzymatically interconverted in lipid droplets. Cholesterol transport to the cholesterol-poor outer mitochondrial membrane (OMM) appears to involve cholesterol transport proteins. Cytochrome P450scc (CYP11A1) then initiates steroidogenesis by converting cholesterol to pregnenolone on the inner mitochondrial membrane (IMM). Acute steroidogenic responses are regulated by cholesterol delivery from OMM to IMM, triggered by the steroidogenic acute regulatory protein (StAR). Chronic steroidogenic capacity is determined by CYP11A1 gene transcription. StAR mutations cause congenital lipoid adrenal hyperplasia, with absent steroidogenesis, potentially lethal salt loss, and 46,XY sex reversal. StAR mutations initially destroy most, but not all steroidogenesis; low levels of StAR-independent steroidogenesis are lost later due to cellular damage, explaining the clinical findings. Rare P450scc mutations cause a similar syndrome. This review addresses these early steps in steroid biosynthesis. PMID:21976778

Eicosapentaenoic acid membrane incorporation impairs ABCA1-dependent cholesterol efflux via a protein kinase A signaling pathway in primary human macrophages.

PubMed

Fournier, Natalie; Tardivel, Sylviane; Benoist, Jean-François; Vedie, Benoît; Rousseau-Ralliard, Delphine; Nowak, Maxime; Allaoui, Fatima; Paul, Jean-Louis

2016-04-01

A diet rich in n-3/n-6 polyunsaturated fatty acids (PUFAs) is cardioprotective. Dietary PUFAs affect the cellular phospholipids composition, which may influence the function of membrane proteins. We investigated the impact of the membrane incorporation of several PUFAs on ABCA1-mediated cholesterol efflux, a key antiatherogenic pathway. Arachidonic acid (AA) (C20:4 n-6) and docosahexaenoic acid (DHA) (C22:6 n-3) decreased or increased cholesterol efflux from J774 mouse macrophages, respectively, whereas they had no effect on efflux from human monocyte-derived macrophages (HMDM). Importantly, eicosapentaenoic acid (EPA) (C20:5 n-3) induced a dose-dependent reduction of ABCA1 functionality in both cellular models (-28% for 70μM of EPA in HMDM), without any alterations in ABCA1 expression. These results show that PUFA membrane incorporation does not have the same consequences on cholesterol efflux from mouse and human macrophages. The EPA-treated HMDM exhibited strong phospholipid composition changes, with high levels of both EPA and its elongation product docosapentaenoic acid (DPA) (C22:5 n-3), which is associated with a decreased level of AA. In HMDM, EPA reduced the ATPase activity of the membrane transporter. Moreover, the activation of adenylate cyclase by forskolin and the inhibition of cAMP phosphodiesterase by isobutylmethylxanthine restored ABCA1 cholesterol efflux in EPA-treated human macrophages. In conclusion, EPA membrane incorporation reduces ABCA1 functionality in mouse macrophages as well as in primary human macrophages and this effect seems to be PKA-dependent in human macrophages. Copyright © 2016 Elsevier B.V. All rights reserved.

LDL-C levels in older people: Cholesterol homeostasis and the free radical theory of ageing converge.

PubMed

Mc Auley, Mark T; Mooney, Kathleen M

2017-07-01

The cardiovascular disease (CVD) risk factor, low density lipoprotein cholesterol (LDL-C) increases with age, up until the midpoint of life in males and females. However, LDL-C can decrease with age in older men and women. Intriguingly, a recent systematic review also revealed an inverse association between LDL-C levels and cardiovascular mortality in older people; low levels of LDL-C were associated with reduced risk of mortality. Such findings are puzzling and require a biological explanation. In this paper a hypothesis is proposed to explain these observations. We hypothesize that the free radical theory of ageing (FRTA) together with disrupted cholesterol homeostasis can account for these observations. Based on this hypothesis, dysregulated hepatic cholesterol homeostasis in older people is characterised by two distinct metabolic states. The first state accounts for an older person who has elevated plasma LDL-C. This state is underpinned by the FRTA which suggests there is a decrease in cellular antioxidant capacity with age. This deficiency enables hepatic reactive oxidative species (ROS) to induce the total activation of HMG-CoA reductase, the key rate limiting enzyme in cholesterol biosynthesis. An increase in cholesterol synthesis elicits a corresponding rise in LDL-C, due to the downregulation of LDL receptor synthesis, and increased production of very low density lipoprotein cholesterol (VLDL-C). In the second state of dysregulation, ROS also trigger the total activation of HMG-CoA reductase. However, due to an age associated decrease in the activity of cholesterol-esterifying enzyme, acyl CoA: cholesterol acyltransferase, there is restricted conversion of excess free cholesterol (FC) to cholesterol esters. Consequently, the secretion of VLDL-C drops, and there is a corresponding decrease in LDL-C. As intracellular levels of FC accumulate, this state progresses to a pathophysiological condition akin to nonalcoholic fatty liver disease. It is our conjecture this deleterious state has the potential to account for the inverse association between LDL-C level and CVD risk observed in older people. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the synergistic action of androgen and FSH on progestin secretion of cultured rat granulosa cells. Cellular and mitochondrial cholesterol metabolism.

PubMed

Nimrod, A

1981-01-01

The effect of FSH and androgen on the conversion of cholesterol into progesterone by cultured rat granulosa cells (GC) was studied in intact cells or mitochondrial preparations. Culture of GC for immature hypophysectomized diethylstilbestrol-treated rats for 48 h in the presence of ovine FSH (5 microgram/ml) alone, or FSH + testosterone (Te; 0.5 microgram/ml) caused a slight increase in the activity of the mitochondrial marker enzyme succinic dehydrogenase, while Te had no effect. Culture with the hormones for 48 h had no significant effect on the levels of free and esterified cellular cholesterol. GC monolayers after 48 h with or without FSH and Te converted [3H]cholesterol into 4 major metabolites, 3 of which were secreted into the medium and, in thin-layer chromatographic behavior, resembled pregnenolone, progesterone and 20 alpha-dihydroprogesterone. The total amount of the 3 C-21 steroids was higher (p less than 0.01) in FSH- or Te-treated than in control cells, and combined treatment had a synergistic effect. The uptake of labeled cholesterol (4--10%) was significantly higher (p less than 0.01) in cells pretreated with FSH or Te, whereas a combined FSH and Te treatment had an additive effect. Mitochondria isolated from GC monolayers took up cholesterol in a temperature-dependent fashion, but this uptake was not affected by hormonal pretreatment. In the presence of cyanoketone, the mitochondrial fractions activity converted cholesterol into pregnenolone. This activity was enhanced by FSH or Te (p less than 0.01), and further enhancement was observed with FSH + Te; the combined effect appeared to be more than additive (p = 0.05). The results suggest that both FSH and Te enhance the activity of cholesterol side-chain cleavage, but do not affect the transport of cholesterol into the mitochondria. A possible hormonal effect on a pre-mitochondrial step is discussed.

Enzymatic Oxidation of Cholesterol: Properties and Functional Effects of Cholestenone in Cell Membranes

PubMed Central

Neuvonen, Maarit; Manna, Moutusi; Mokkila, Sini; Javanainen, Matti; Rog, Tomasz; Liu, Zheng; Bittman, Robert; Vattulainen, Ilpo; Ikonen, Elina

2014-01-01

Bacterial cholesterol oxidase is commonly used as an experimental tool to reduce cellular cholesterol content. That the treatment also generates the poorly degradable metabolite 4-cholesten-3-one (cholestenone) has received less attention. Here, we investigated the membrane partitioning of cholestenone using simulations and cell biological experiments and assessed the functional effects of cholestenone in human cells. Atomistic simulations predicted that cholestenone reduces membrane order, undergoes faster flip-flop and desorbs more readily from membranes than cholesterol. In primary human fibroblasts, cholestenone was released from membranes to physiological extracellular acceptors more avidly than cholesterol, but without acceptors it remained in cells over a day. To address the functional effects of cholestenone, we studied fibroblast migration during wound healing. When cells were either cholesterol oxidase treated or part of cellular cholesterol was exchanged for cholestenone with cyclodextrin, cell migration during 22 h was markedly inhibited. Instead, when a similar fraction of cholesterol was removed using cyclodextrin, cells replenished their cholesterol content in 3 h and migrated similarly to control cells. Thus, cholesterol oxidation produces long-term functional effects in cells and these are in part due to the generated membrane active cholestenone. PMID:25157633

Evidence That Chromium Modulates Cellular Cholesterol Homeostasis and ABCA1 Functionality Impaired By Hyperinsulinemia

PubMed Central

Sealls, Whitney; Penque, Brent A.; Elmendorf, Jeffrey S.

2011-01-01

Objective Trivalent chromium (Cr3+) is an essential micronutrient. Findings since the 1950s suggest that Cr3+ might benefit cholesterol homeostasis. Here we present mechanistic evidence in support of this role of Cr3+. Method and Results High-density lipoprotein cholesterol generation in 3T3-L1 adipocytes, rendered ineffective by hyperinsulinemia, known to accompany disorders of lipid metabolism was corrected by Cr3+. Mechanistically, Cr3+ reversed hyperinsulinemia-induced cellular cholesterol accrual and associated defects in cholesterol transporter ABCA1 trafficking and apolipoprotein A1-mediated cholesterol efflux. Moreover, direct activation of AMP-activated protein kinase (AMPK), known to be activated by Cr3+, and/or inhibition of hexosamine biosynthesis pathway (HBP) activity, known to be elevated by hyperinsulinemia, mimics Cr3+ action. Conclusion These findings suggest a mechanism of Cr3+ action that fits with long-standing claims of its role in cholesterol homeostasis. Furthermore, these data implicate a mechanistic basis for the coexistence of dyslipidemia with hyperinsulinemia. PMID:21311039

Cholesterol efflux is differentially regulated in neurons and astrocytes: implications for brain cholesterol homeostasis

PubMed Central

Chen, Jing; Zhang, Xiaolu; Kusumo, Handojo; Costa, Lucio G.; Guizzetti, Marina

2012-01-01

Disruption of cholesterol homeostasis in the central nervous system (CNS) has been associated with neurological, neurodegenerative, and neurodevelopmental disorders. The CNS is a closed system with regard to cholesterol homeostasis, as cholesterol-delivering lipoproteins from the periphery cannot pass the blood-brain-barrier and enter the brain. Different cell types in the brain have different functions in the regulation of cholesterol homeostasis, with astrocytes producing and releasing apolipoprotein E and lipoproteins, and neurons metabolizing cholesterol to 24(S)-hydroxycholesterol. We present evidence that astrocytes and neurons adopt different mechanisms also in regulating cholesterol efflux. We found that in astrocytes cholesterol efflux is induced by both lipid-free apolipoproteins and lipoproteins, while cholesterol removal from neurons is triggered only by lipoproteins. The main pathway by which apolipoproteins induce cholesterol efflux is through ABCA1. By upregulating ABCA1 levels and by inhibiting its activity and silencing its expression, we show that ABCA1 is involved in cholesterol efflux from astrocytes but not from neurons. Furthermore, our results suggest that ABCG1 is involved in cholesterol efflux to apolipoproteins and lipoproteins from astrocytes but not from neurons, while ABCG4, whose expression is much higher in neurons than astrocytes, is involved in cholesterol efflux from neurons but not astrocytes. These results indicate that different mechanisms regulate cholesterol efflux from neurons and astrocytes, reflecting the different roles that these cell types play in brain cholesterol homeostasis. These results are important in understanding cellular targets of therapeutic drugs under development for the treatments of conditions associated with altered cholesterol homeostasis in the CNS. PMID:23010475

Clinically used selective estrogen receptor modulators affect different steps of macrophage-specific reverse cholesterol transport

PubMed Central

Fernández-Suárez, María E.; Escolà-Gil, Joan C.; Pastor, Oscar; Dávalos, Alberto; Blanco-Vaca, Francisco; Lasunción, Miguel A.; Martínez-Botas, Javier; Gómez-Coronado, Diego

2016-01-01

Selective estrogen receptor modulators (SERMs) are widely prescribed drugs that alter cellular and whole-body cholesterol homeostasis. Here we evaluate the effect of SERMs on the macrophage-specific reverse cholesterol transport (M-RCT) pathway, which is mediated by HDL. Treatment of human and mouse macrophages with tamoxifen, raloxifene or toremifene induced the accumulation of cytoplasmic vesicles of acetyl-LDL-derived free cholesterol. The SERMs impaired cholesterol efflux to apolipoprotein A-I and HDL, and lowered ABCA1 and ABCG1 expression. These effects were not altered by the antiestrogen ICI 182,780 nor were they reproduced by 17β-estradiol. The treatment of mice with tamoxifen or raloxifene accelerated HDL-cholesteryl ester catabolism, thereby reducing HDL-cholesterol concentrations in serum. When [3H]cholesterol-loaded macrophages were injected into mice intraperitoneally, tamoxifen, but not raloxifene, decreased the [3H]cholesterol levels in serum, liver and feces. Both SERMs downregulated liver ABCG5 and ABCG8 protein expression, but tamoxifen reduced the capacity of HDL and plasma to promote macrophage cholesterol efflux to a greater extent than raloxifene. We conclude that SERMs interfere with intracellular cholesterol trafficking and efflux from macrophages. Tamoxifen, but not raloxifene, impair M-RCT in vivo. This effect is primarily attributable to the tamoxifen-mediated reduction of the capacity of HDL to promote cholesterol mobilization from macrophages. PMID:27601313

The membrane as the gatekeeper of infection: Cholesterol in host-pathogen interaction.

PubMed

Kumar, G Aditya; Jafurulla, Md; Chattopadhyay, Amitabha

2016-09-01

The cellular plasma membrane serves as a portal for the entry of intracellular pathogens. An essential step for an intracellular pathogen to gain entry into a host cell therefore is to be able to cross the cell membrane. In this review, we highlight the role of host membrane cholesterol in regulating the entry of intracellular pathogens using insights obtained from work on the interaction of Leishmania and Mycobacterium with host cells. The entry of these pathogens is known to be dependent on host membrane cholesterol. Importantly, pathogen entry is inhibited either upon depletion (or complexation), or enrichment of membrane cholesterol. In other words, an optimum level of host membrane cholesterol is necessary for efficient infection by pathogens. In this overall context, we propose a general mechanism, based on cholesterol-induced conformational changes, involving cholesterol binding sites in host cell surface receptors that are implicated in this process. A therapeutic strategy targeting modulation of membrane cholesterol would have the advantage of avoiding the commonly encountered problem of drug resistance in tackling infection by intracellular pathogens. Insights into the role of host membrane cholesterol in pathogen entry would be instrumental in the development of novel therapeutic strategies to effectively tackle intracellular pathogenesis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Localization and role of NPC1L1 in cholesterol absorption in human intestine.

PubMed

Sané, Alain Théophile; Sinnett, Daniel; Delvin, Edgard; Bendayan, Moise; Marcil, Valérie; Ménard, Daniel; Beaulieu, Jean-François; Levy, Emile

2006-10-01

Recent studies have documented the presence of Niemann-Pick C1-Like 1 (NPC1L1) in the small intestine and its capacity to transport cholesterol in mice and rats. The current investigation was undertaken to explore the localization and function of NPC1L1 in human enterocytes. Cell fractionation experiments revealed an NPC1L1 association with apical membrane of the enterocyte in human jejunum. Signal was also detected in lysosomes, endosomes, and mitochondria. Confirmation of cellular NPC1L1 distribution was obtained by immunocytochemistry. Knockdown of NPC1L1 caused a decline in the ability of Caco-2 cells to capture micellar [(14)C]free cholesterol. Furthermore, this NPC1L1 suppression resulted in increased and decreased mRNA levels and activity of HMG-CoA reductase, the rate-limiting step in cholesterol synthesis, and of ACAT, the key enzyme in cholesterol esterification, respectively. An increase was also noted in the transcriptional factor sterol-regulatory element binding protein that modulates cholesterol homeostasis. Efforts were devoted to define the impact of NPC1L1 knockdown on other mediators of cholesterol uptake. RT-PCR evidence is presented to show the significant decrease in the levels of scavenger receptor class B type I (SR-BI) with no changes in ABCA1, ABCG5, and cluster determinant 36 in NPC1L1-deficient Caco-2 cells. Together, our data suggest that NPC1L1 contributes to intestinal cholesterol homeostasis and possibly cooperates with SR-BI to mediate cholesterol absorption in humans.

Influence of Cholesterol on the Oxygen Permeability of Membranes: Insight from Atomistic Simulations.

PubMed

Dotson, Rachel J; Smith, Casey R; Bueche, Kristina; Angles, Gary; Pias, Sally C

2017-06-06

Cholesterol is widely known to alter the physical properties and permeability of membranes. Several prior works have implicated cell membrane cholesterol as a barrier to tissue oxygenation, yet a good deal remains to be explained with regard to the mechanism and magnitude of the effect. We use molecular dynamics simulations to provide atomic-resolution insight into the influence of cholesterol on oxygen diffusion across and within the membrane. Our simulations show strong overall agreement with published experimental data, reproducing the shapes of experimental oximetry curves with high accuracy. We calculate the upper-limit transmembrane oxygen permeability of a 1-palmitoyl,2-oleoylphosphatidylcholine phospholipid bilayer to be 52 ± 2 cm/s, close to the permeability of a water layer of the same thickness. With addition of cholesterol, the permeability decreases somewhat, reaching 40 ± 2 cm/s at the near-saturating level of 62.5 mol % cholesterol and 10 ± 2 cm/s in a 100% cholesterol mimic of the experimentally observed noncrystalline cholesterol bilayer domain. These reductions in permeability can only be biologically consequential in contexts where the diffusional path of oxygen is not water dominated. In our simulations, cholesterol reduces the overall solubility of oxygen within the membrane but enhances the oxygen transport parameter (solubility-diffusion product) near the membrane center. Given relatively low barriers to passing from membrane to membrane, our findings support hydrophobic channeling within membranes as a means of cellular and tissue-level oxygen transport. In such a membrane-dominated diffusional scheme, the influence of cholesterol on oxygen permeability is large enough to warrant further attention. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

In vitro fatty acid enrichment of macrophages alters inflammatory response and net cholesterol accumulation

PubMed Central

Wang, Shu; Wu, Dayong; Lamon-Fava, Stefania; Matthan, Nirupa R.; Honda, Kaori L.; Lichtenstein, Alice H.

2010-01-01

Dietary long-chain PUFA, both n-3 and n-6, have unique benefits with respect to CVD risk. The aim of the present study was to determine the mechanisms by which n-3 PUFA (EPA, DHA) and n-6 PUFA (linoleic acid (LA), arachidonic acid (AA)) relative to SFA (myristic acid (MA), palmitic acid (PA)) alter markers of inflammation and cholesterol accumulation in macrophages (MΦ). Cells treated with AA and EPA elicited significantly less inflammatory response than control cells or those treated with MA, PA and LA, with intermediate effects for DHA, as indicated by lower levels of mRNA and secretion of TNFα, IL-6 and monocyte chemoattractant protein-1. Differences in cholesterol accumulation after exposure to minimally modified LDL were modest. AA and EPA resulted in significantly lower MΦ scavenger receptor 1 mRNA levels relative to control or MA-, PA-, LA- and DHA-treated cells, and ATP-binding cassette A1 mRNA levels relative to control or MA-, PA- and LA-treated cells. These data suggest changes in the rate of bidirectional cellular cholesterol flux. In summary, individual long-chain PUFA have differential effects on inflammatory response and markers of cholesterol flux in MΦ which are not related to the n position of the first double bond, chain length or degree of saturation. PMID:19660150

A mathematical model of the mevalonate cholesterol biosynthesis pathway.

PubMed

Pool, Frances; Currie, Richard; Sweby, Peter K; Salazar, José Domingo; Tindall, Marcus J

2018-04-14

We formulate, parameterise and analyse a mathematical model of the mevalonate pathway, a key pathway in the synthesis of cholesterol. Of high clinical importance, the pathway incorporates rate limiting enzymatic reactions with multiple negative feedbacks. In this work we investigate the pathway dynamics and demonstrate that rate limiting steps and negative feedbacks within it act in concert to tightly regulate intracellular cholesterol levels. Formulated using the theory of nonlinear ordinary differential equations and parameterised in the context of a hepatocyte, the governing equations are analysed numerically and analytically. Sensitivity and mathematical analysis demonstrate the importance of the two rate limiting enzymes 3-hydroxy-3-methylglutaryl-CoA reductase and squalene synthase in controlling the concentration of substrates within the pathway as well as that of cholesterol. The role of individual feedbacks, both global (between that of cholesterol and sterol regulatory element-binding protein 2; SREBP-2) and local internal (between substrates in the pathway) are investigated. We find that whilst the cholesterol SREBP-2 feedback regulates the overall system dynamics, local feedbacks activate within the pathway to tightly regulate the overall cellular cholesterol concentration. The network stability is analysed by constructing a reduced model of the full pathway and is shown to exhibit one real, stable steady-state. We close by addressing the biological question as to how farnesyl-PP levels are affected by CYP51 inhibition, and demonstrate that the regulatory mechanisms within the network work in unison to ensure they remain bounded. Copyright © 2018 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yan; Wu, Jian-Feng; Tang, Yan-Yan

Highlights: • U II reduces cholesterol efflux in THP-1 macrophages. • U II decreases the expression of ABCA1. • Inhibition of the ERK/NF-κB pathway reduces U II effects on ABCA1 expression and cholesterol efflux. - Abstract: Objective: Foam cell formation in the arterial wall plays a key role in the development of atherosclerosis. Recent studies showed that Urotensin II (U II) is involved in the pathogenesis of atherosclerosis. Here we examined the effects of human U II on ATP-binding cassette transporter A1 (ABCA1) expression and the underlying mechanism in THP-1 macrophages. Methods and results: Cultured THP-1 macrophages were treated withmore » U II, followed by measuring the intracellular lipid contents, cholesterol efflux and ABCA1 levels. The results showed that U II dramatically decreased ABCA1 levels and impaired cholesterol efflux. However, the effects of U II on ABCA1 protein expression and cellular cholesterol efflux were partially reversed by inhibition of extracellular signal regulated kinase 1/2 (ERK1/2) and nuclear factor kappa B (NF-κB) activity, suggesting the potential roles of ERK1/2 and NF-κB in ABCA1 expression, respectively. Conclusion: Our current data indicate that U II may have promoting effects on the progression of atherosclerosis, likely through suppressing ABCA1 expression via activation of the ERK/NF-κB pathway and reducing cholesterol efflux to promote macrophage foam cell formation.« less

Elevated Cholesterol in the Coxiella burnetii Intracellular Niche Is Bacteriolytic

PubMed Central

Mulye, Minal; Samanta, Dhritiman; Winfree, Seth; Heinzen, Robert A.

2017-01-01

ABSTRACT Coxiella burnetii is an intracellular bacterial pathogen and a significant cause of culture-negative endocarditis in the United States. Upon infection, the nascent Coxiella phagosome fuses with the host endocytic pathway to form a large lysosome-like vacuole called the parasitophorous vacuole (PV). The PV membrane is rich in sterols, and drugs perturbing host cell cholesterol homeostasis inhibit PV formation and bacterial growth. Using cholesterol supplementation of a cholesterol-free cell model system, we found smaller PVs and reduced Coxiella growth as cellular cholesterol concentration increased. Further, we observed in cells with cholesterol a significant number of nonfusogenic PVs that contained degraded bacteria, a phenotype not observed in cholesterol-free cells. Cholesterol had no effect on axenic Coxiella cultures, indicating that only intracellular bacteria are sensitive to cholesterol. Live-cell microscopy revealed that both plasma membrane-derived cholesterol and the exogenous cholesterol carrier protein low-density lipoprotein (LDL) traffic to the PV. To test the possibility that increasing PV cholesterol levels affects bacterial survival, infected cells were treated with U18666A, a drug that traps cholesterol in lysosomes and PVs. U18666A treatment led to PVs containing degraded bacteria and a significant loss in bacterial viability. The PV pH was significantly more acidic in cells with cholesterol or cells treated with U18666A, and the vacuolar ATPase inhibitor bafilomycin blocked cholesterol-induced PV acidification and bacterial death. Additionally, treatment of infected HeLa cells with several FDA-approved cholesterol-altering drugs led to a loss of bacterial viability, a phenotype also rescued by bafilomycin. Collectively, these data suggest that increasing PV cholesterol further acidifies the PV, leading to Coxiella death. PMID:28246364

Moringa oleifera-based diet protects against nickel-induced hepatotoxicity in rats.

PubMed

Stephen Adeyemi, Oluyomi; Sokolayemji Aroge, Cincin; Adewumi Akanji, Musbau

2017-07-13

Multiple health-promoting effects have been attributed to the consumption of Moringa oleifera leaves, as part of diet without adequate scientific credence. This study evaluated the effect of M. oleifera-based diets on nickel (Ni) - induced hepatotoxicity in rats. Male rats assigned into six groups were given oral administration of 20 mg/kg body weight nickel sulfate in normal saline and either fed normal diet orM. oleifera-based diets for 21 days. All animals were sacrificed under anesthesia 24 hours after the last treatment. Ni exposure elevated the rat plasma activities of alanine transaminase, aspartate transaminase and alkaline phosphatase significantly. Ni exposure also raised the levels of triglyceride, total cholesterol and low-density lipoprotein cholesterol while depleting the high-density lipoprotein cholesterol concentration. Further, Ni exposure raised rat plasma malondialdehyde but depleted reduced glutathione concentrations. The histopathological presentations revealed inflammation and cellular degeneration caused by Ni exposure. We show evidence thatM. oleifera-based diets protected against Ni-induced hepatotoxicity by improving the rat liver function indices, lipid profile as well as restoring cellular architecture and integrity. Study lends credence to the health-promoting value ofM. oleifera as well as underscores its potential to attenuate hepatic injury.

Box C/D small nucleolar RNA (snoRNA) U60 regulates intracellular cholesterol trafficking.

PubMed

Brandis, Katrina A; Gale, Sarah; Jinn, Sarah; Langmade, Stephen J; Dudley-Rucker, Nicole; Jiang, Hui; Sidhu, Rohini; Ren, Aileen; Goldberg, Anna; Schaffer, Jean E; Ory, Daniel S

2013-12-13

Mobilization of plasma membrane (PM) cholesterol to the endoplasmic reticulum is essential for cellular cholesterol homeostasis. The mechanisms regulating this retrograde, intermembrane cholesterol transfer are not well understood. Because mutant cells with defects in PM to endoplasmic reticulum cholesterol trafficking can be isolated on the basis of resistance to amphotericin B, we conducted an amphotericin B loss-of-function screen in Chinese hamster ovary (CHO) cells using insertional mutagenesis to identify genes that regulate this trafficking mechanism. Mutant line A1 displayed reduced cholesteryl ester formation from PM-derived cholesterol and increased de novo cholesterol synthesis, indicating a deficiency in retrograde cholesterol transport. Genotypic analysis revealed that the A1 cell line contained one disrupted allele of the U60 small nucleolar RNA (snoRNA) host gene, resulting in haploinsufficiency of the box C/D snoRNA U60. Complementation and mutational studies revealed the U60 snoRNA to be the essential feature from this locus that affects cholesterol trafficking. Lack of alteration in predicted U60-mediated site-directed methylation of 28 S rRNA in the A1 mutant suggests that the U60 snoRNA modulates cholesterol trafficking by a mechanism that is independent of this canonical function. Our study adds to a growing body of evidence for participation of small noncoding RNAs in cholesterol homeostasis and is the first to implicate a snoRNA in this cellular function.

Cellular Localization and Trafficking of the Human ABCG1 Transporter

PubMed Central

Neufeld, Edward B.; O’Brien, Katherine; Walts, Avram D.; Stonik, John A.; Demosky, Steven J.; Malide, Daniela; Combs, Christian A.; Remaley, Alan T.

2014-01-01

We have developed a suitable heterologous cell expression system to study the localization, trafficking, and site(s) of function of the human ABCG1 transporter. Increased plasma membrane (PM) and late endosomal (LE) cholesterol generated by ABCG1 was removed by lipoproteins and liposomes, but not apoA-I. Delivery of ABCG1 to the PM and LE was required for ABCG1-mediated cellular cholesterol efflux. ABCG1 LEs frequently contacted the PM, providing a collisional mechanism for transfer of ABCG1-mobilized cholesterol, similar to ABCG1-mediated PM cholesterol efflux to lipoproteins. ABCG1-mobilized LE cholesterol also trafficked to the PM by a non-vesicular pathway. Transfer of ABCG1-mobilized cholesterol from the cytoplasmic face of LEs to the PM and concomitant removal of cholesterol from the outer leaflet of the PM bilayer by extracellular acceptors suggests that ABCG1 mobilizes cholesterol on both sides of the lipid bilayer for removal by acceptors. ABCG1 increased uptake of HDL into LEs, consistent with a potential ABCG1-mediated cholesterol efflux pathway involving HDL resecretion. Thus, ABCG1 at the PM mobilizes PM cholesterol and ABCG1 in LE/LYS generates mobile pools of cholesterol that can traffic by both vesicular and non-vesicular pathways to the PM where it can also be transferred to extracellular acceptors with a lipid surface. PMID:25405320

Cholesterol removal from adult skeletal muscle impairs excitation–contraction coupling and aging reduces caveolin-3 and alters the expression of other triadic proteins

PubMed Central

Barrientos, Genaro; Llanos, Paola; Hidalgo, Jorge; Bolaños, Pura; Caputo, Carlo; Riquelme, Alexander; Sánchez, Gina; Quest, Andrew F. G.; Hidalgo, Cecilia

2015-01-01

Cholesterol and caveolin are integral membrane components that modulate the function/location of many cellular proteins. Skeletal muscle fibers, which have unusually high cholesterol levels in transverse tubules, express the caveolin-3 isoform but its association with transverse tubules remains contentious. Cholesterol removal impairs excitation–contraction (E–C) coupling in amphibian and mammalian fetal skeletal muscle fibers. Here, we show that treating single muscle fibers from adult mice with the cholesterol removing agent methyl-β-cyclodextrin decreased fiber cholesterol by 26%, altered the location pattern of caveolin-3 and of the voltage dependent calcium channel Cav1.1, and suppressed or reduced electrically evoked Ca2+ transients without affecting membrane integrity or causing sarcoplasmic reticulum (SR) calcium depletion. We found that transverse tubules from adult muscle and triad fractions that contain ~10% attached transverse tubules, but not SR membranes, contained caveolin-3 and Cav1.1; both proteins partitioned into detergent-resistant membrane fractions highly enriched in cholesterol. Aging entails significant deterioration of skeletal muscle function. We found that triad fractions from aged rats had similar cholesterol and RyR1 protein levels compared to triads from young rats, but had lower caveolin-3 and glyceraldehyde 3-phosphate dehydrogenase and increased Na+/K+-ATPase protein levels. Both triad fractions had comparable NADPH oxidase (NOX) activity and protein content of NOX2 subunits (p47phox and gp91phox), implying that NOX activity does not increase during aging. These findings show that partial cholesterol removal impairs E–C coupling and alters caveolin-3 and Cav1.1 location pattern, and that aging reduces caveolin-3 protein content and modifies the expression of other triadic proteins. We discuss the possible implications of these findings for skeletal muscle function in young and aged animals. PMID:25914646

Short-term cooling increases serum triglycerides and small high-density lipoprotein levels in humans.

PubMed

Hoeke, Geerte; Nahon, Kimberly J; Bakker, Leontine E H; Norkauer, Sabine S C; Dinnes, Donna L M; Kockx, Maaike; Lichtenstein, Laeticia; Drettwan, Diana; Reifel-Miller, Anne; Coskun, Tamer; Pagel, Philipp; Romijn, Fred P H T M; Cobbaert, Christa M; Jazet, Ingrid M; Martinez, Laurent O; Kritharides, Leonard; Berbée, Jimmy F P; Boon, Mariëtte R; Rensen, Patrick C N

Cold exposure and β3-adrenergic receptor agonism, which both activate brown adipose tissue, markedly influence lipoprotein metabolism by enhancing lipoprotein lipase-mediated catabolism of triglyceride-rich lipoproteins and increasing plasma high-density lipoprotein (HDL) levels and functionality in mice. However, the effect of short-term cooling on human lipid and lipoprotein metabolism remained largely elusive. The objective was to assess the effect of short-term cooling on the serum lipoprotein profile and HDL functionality in men. Body mass index-matched young, lean men were exposed to a personalized cooling protocol for 2 hours. Before and after cooling, serum samples were collected for analysis of lipids and lipoprotein composition by 1 H-nuclear magnetic resonance. Adenosine triphosphate-binding cassette A1 (ABCA1)-mediated cholesterol efflux capacity of HDL was measured using [ 3 H]cholesterol-loaded ABCA1-transfected Chinese hamster ovary cells. Short-term cooling increased serum levels of free fatty acids, triglycerides, and cholesterol. Cooling increased the concentration of large very low-density lipoprotein (VLDL) particles accompanied by increased mean size of VLDL particles. In addition, cooling enhanced the concentration of small LDL and small HDL particles as well as the cholesterol levels within these particles. The increase in small HDL was accompanied by increased ABCA1-dependent cholesterol efflux in vitro. Our data show that short-term cooling increases the concentration of large VLDL particles and increases the generation of small LDL and HDL particles. We interpret that cooling increases VLDL production and turnover, which results in formation of surface remnants that form small HDL particles that attract cellular cholesterol. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

The novel selective PPARα modulator (SPPARMα) pemafibrate improves dyslipidemia, enhances reverse cholesterol transport and decreases inflammation and atherosclerosis.

PubMed

Hennuyer, Nathalie; Duplan, Isabelle; Paquet, Charlotte; Vanhoutte, Jonathan; Woitrain, Eloise; Touche, Véronique; Colin, Sophie; Vallez, Emmanuelle; Lestavel, Sophie; Lefebvre, Philippe; Staels, Bart

2016-06-01

Atherosclerosis is characterized by lipid accumulation and chronic inflammation in the arterial wall. Elevated levels of apolipoprotein (apo) B-containing lipoproteins are a risk factor for cardiovascular disease (CVD). By contrast, plasma levels of functional high-density lipoprotein (HDL) and apoA-I are protective against CVD by enhancing reverse cholesterol transport (RCT). Activation of peroxisome proliferator-activated receptor-α (PPARα), a ligand-activated transcription factor, controls lipid metabolism, cellular cholesterol trafficking in macrophages and influences inflammation. To study whether pharmacological activation of PPARα with a novel highly potent and selective PPARα modulator, pemafibrate, improves lipid metabolism, macrophage cholesterol efflux, inflammation and consequently atherosclerosis development in vitro and in vivo using human apolipoprotein E2 Knock-In (apoE2KI) and human apoA-I transgenic (hapoA-I tg) mice. Pemafibrate treatment decreases apoB secretion in chylomicrons by polarized Caco-2/TC7 intestinal epithelium cells and reduces triglyceride levels in apoE2KI mice. Pemafibrate treatment of hapoA-I tg mice increases plasma HDL cholesterol, apoA-I and stimulates RCT to feces. In primary human macrophages, pemafibrate promotes macrophage cholesterol efflux to HDL and exerts anti-inflammatory activities. Pemafibrate also reduces markers of inflammation and macrophages in the aortic crosses as well as aortic atherosclerotic lesion burden in western diet-fed apoE2KI mice. These results demonstrate that the novel selective PPARα modulator pemafibrate exerts beneficial effects on lipid metabolism, RCT and inflammation resulting in anti-atherogenic properties. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Reduced levels of TNF alpha in hypercholesterolemic individuals after treatment with pravastatin for 8 weeks.

PubMed

Solheim, S; Seljeflot, I; Arnesen, H; Eritsland, J; Eikvar, L

2001-08-01

cellular adhesion molecules (CAMs) expressed on the endothelial surface play a key role in the inflammatory process of atherosclerosis, and increased expression of CAMs has been shown in hypercholesterolemic individuals. The expression of CAMs is mediated by several cytokines including tumor necrosis factor alpha (TNF alpha) and interleukin 6 (IL-6). The aim of the present study was to assess the influence of pravastatin 40 mg per day on selected soluble CAMs; intercellular adhesion molecule 1 (ICAM-1), vascular cellular adhesion molecule 1 (VCAM-1), E-selectin, P-selectin and some circulating markers of inflammation; C-reactive protein (CRP) and the cytokines TNF alpha and IL-6. 40 non-diabetic men, age below 70 years, with serum total cholesterol 6--10 mmol/l combined with HDL-cholesterol < or =1.2 mmol/l were included. The study was randomized, double blinded, placebo controlled, cross over designed with 8 weeks intervention periods. Fasting blood samples were drawn after 8 and 16 weeks. significant reduction of total cholesterol was achieved after treatment with pravastatin (7.8 on placebo vs. 5.7 mmol/l on pravastatin). TNF alpha was significantly reduced after treatment with pravastatin (1.33 on placebo vs. 1.10 pg/ml on pravastatin, P=0.032), whereas no differences in the levels of the measured sCAMs, CRP and IL-6 were found. Subgroup analysis among smokers versus non-smokers showed a significant reduction in the level of TNF alpha only among the smokers. hypercholesterolemic individuals treated with pravastatin 40 mg per day for 8 weeks showed a statistically significant reduction in the levels of TNF alpha as compared with placebo.

Apocynin alleviated hepatic oxidative burden and reduced liver injury in hypercholesterolaemia.

PubMed

Lu, Long-Sheng; Wu, Chau-Chung; Hung, Li-Man; Chiang, Meng-Tsan; Lin, Ching-Ting; Lin, Chii-Wann; Su, Ming-Jai

2007-05-01

This study addressed the effects of apocynin, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, on hepatic oxidative burden and liver injury during diet-induced hypercholesterolaemia. Male Wistar rats were fed a 4% cholesterol-enriched diet for 3 weeks. Apocynin was administered in drinking water concurrently. The high-cholesterol diet (HC) significantly increased the serum level of cholesterol and hepatic cholesterol ester deposition, and these parameters were similar between the HC and high-cholesterol diet plus apocynin (HCA) groups. The HC group showed abnormal liver function tests [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (Alk-P)] as well as increased Evans blue extravasation and macrophages infiltration. Apocynin treatment could suppress these inflammation-related parameters. In vivo measurement of NADPH-derived cellular autofluorescence suggested that HC increased oxidative stress in hepatocytes. Biochemical analysis of redox status including thiobarbituric acid reactive substances, reduced glutathione, and oxidized glutathione also confirmed the phenomenon. Apocynin treatment was able to alleviate these indices of oxidative burden owing to HC. Furthermore, apocynin-abrogated HC induced gp91(phox) expression, suggesting the involvement of NADPH oxidase in the pathogenesis. We concluded that apocynin suppressed NADPH oxidase activation and subsequent liver injuries owing to high-cholesterol intake in rats. The impacts of cholesterol metabolism disorders on pathogenesis and progression of steatohepatitis warrant further clinical investigation.

13-hydroxy linoleic acid increases expression of the cholesterol transporters ABCA1, ABCG1 and SR-BI and stimulates apoA-I-dependent cholesterol efflux in RAW264.7 macrophages

PubMed Central

2011-01-01

Background Synthetic activators of peroxisome proliferator-activated receptors (PPARs) stimulate cholesterol removal from macrophages through PPAR-dependent up-regulation of liver × receptor α (LXRα) and subsequent induction of cholesterol exporters such as ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type 1 (SR-BI). The present study aimed to test the hypothesis that the hydroxylated derivative of linoleic acid (LA), 13-HODE, which is a natural PPAR agonist, has similar effects in RAW264.7 macrophages. Methods RAW264.7 macrophages were treated without (control) or with LA or 13-HODE in the presence and absence of PPARα or PPARγ antagonists and determined protein levels of LXRα, ABCA1, ABCG1, SR-BI, PPARα and PPARγ and apolipoprotein A-I mediated lipid efflux. Results Treatment of RAW264.7 cells with 13-HODE increased PPAR-transactivation activity and protein concentrations of LXRα, ABCA1, ABCG1 and SR-BI when compared to control treatment (P < 0.05). In addition, 13-HODE enhanced cholesterol concentration in the medium but decreased cellular cholesterol concentration during incubation of cells with the extracellular lipid acceptor apolipoprotein A-I (P < 0.05). Pre-treatment of cells with a selective PPARα or PPARγ antagonist completely abolished the effects of 13-HODE on cholesterol efflux and protein levels of genes investigated. In contrast to 13-HODE, LA had no effect on either of these parameters compared to control cells. Conclusion 13-HODE induces cholesterol efflux from macrophages via the PPAR-LXRα-ABCA1/SR-BI-pathway. PMID:22129452

Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane.

PubMed

Iaea, David B; Mao, Shu; Lund, Frederik W; Maxfield, Frederick R

2017-04-15

Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t 1/2 =12-15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC. © 2017 Iaea et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

A pH-responsive drug nanovehicle constructed by reversible attachment of cholesterol to PEGylated poly(l-lysine) via catechol-boronic acid ester formation.

PubMed

Yang, Bin; Lv, Yin; Zhu, Jing-Yi; Han, Yun-Tao; Jia, Hui-Zhen; Chen, Wei-Hai; Feng, Jun; Zhang, Xian-Zheng; Zhuo, Ren-Xi

2014-08-01

The present work reports the construction of a drug delivery nanovehicle via a pH-sensitive assembly strategy for improved cellular internalization and intracellular drug liberation. Through spontaneous formation of boronate linkage in physiological conditions, phenylboronic acid-modified cholesterol was able to attach onto catechol-pending methoxypoly(ethylene glycol)-block-poly(l-lysine). This comb-type polymer can self-organize into a micellar nanoconstruction that is able to effectively encapsulate poorly water-soluble agents. The blank micelles exhibited negligible in vitro cytotoxicity, yet doxorubicin (DOX)-loaded micelles could effectively induce cell death at a level comparable to free DOX. Owing to the acid-labile feature of the boronate linkage, a reduction in environmental pH from pH 7.4 to 5.0 could trigger the dissociation of the nanoconstruction, which in turn could accelerate the liberation of entrapped drugs. Importantly, the blockage of endosomal acidification in HeLa cells by NH4Cl treatment significantly decreased the nuclear uptake efficiency and cell-killing effect mediated by the DOX-loaded nanoassembly, suggesting that acid-triggered destruction of the nanoconstruction is of significant importance in enhanced drug efficacy. Moreover, confocal fluorescence microscopy and flow cytometry assay revealed the effective internalization of the nanoassemblies, and their cellular uptake exhibited a cholesterol dose-dependent profile, indicating the contribution of introduced cholesterol functionality to the transmembrane process of the nanoassembly. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Helical synthetic peptides that stimulate cellular cholesterol efflux

DOEpatents

Bielicki, John K.; Natarajan, Pradeep

2010-04-06

The present invention provides peptides comprising at least one amphipathic alpha helix and having an cholesterol mediating activity and a ABCA stabilization activity. The invention further provides methods of using such peptides.

C1q/TNF-related protein 9 inhibits the cholesterol-induced Vascular smooth muscle cell phenotype switch and cell dysfunction by activating AMP-dependent kinase.

PubMed

Liu, Qi; Zhang, Hui; Lin, Jiale; Zhang, Ruoxi; Chen, Shuyuan; Liu, Wei; Sun, Meng; Du, Wenjuan; Hou, Jingbo; Yu, Bo

2017-11-01

Vascular smooth muscle cells (VSMCs) switch to macrophage-like cells after cholesterol loading, and this change may play an important role in the progression of atherosclerosis. C1q/TNF-related protein 9 (CTRP9) is a recently discovered adipokine that has been shown to have beneficial effects on glucose metabolism and vascular function, particularly in regard to cardiovascular disease. The question of whether CTRP9 can protect VSMCs from cholesterol damage has not been addressed. In this study, the impact of CTRP9 on cholesterol-damaged VSMCs was observed. Our data show that in cholesterol-treated VSMCs, CTRP9 significantly reversed the cholesterol-induced increases in pro-inflammatory factor secretion, monocyte adhesion, cholesterol uptake and expression of the macrophage marker CD68. Meanwhile, CTRP9 prevented the cholesterol-induced activation of the TLR4-MyD88-p65 pathway and upregulated the expression of proteins important for cholesterol efflux. Mechanistically, as siRNA-induced selective gene ablation of AMPKα1 abolished these effects of CTRP9, we concluded that CTRP9 achieves these protective effects in VSMCs through the AMP-dependent kinase (AMPK) pathway. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Chromium picolinate positively influences the glucose transporter system via affecting cholesterol homeostasis in adipocytes cultured under hyperglycemic diabetic conditions

PubMed Central

Pattar, Guruprasad R.; Tackett, Lixuan; Liu, Ping; Elmendorf, Jeffrey S.

2008-01-01

Since trivalent chromium (Cr3+) enhances glucose metabolism, interest in the use of Cr3+as a therapy for type 2 diabetes has grown in the mainstream medical community. Moreover, accumulating evidence suggests that Cr3+ may also benefit cardiovascular disease (CVD) and atypical depression. We have found that cholesterol, a lipid implicated in both CVD and neurodegenerative disorders, also influences cellular glucose uptake. A recent study in our laboratory shows that exposure of 3T3-L1 adipocytes to chromium picolinate (CrPic, 10 nM) induces a loss of plasma membrane cholesterol. Concomitantly, accumulation of intracellularly sequestered glucose transporter GLUT4 at the plasma membrane was dependent on the CrPic-induced cholesterol loss. Since CrPic supplementation has the greatest benefit on glucose metabolism in hyperglycemic insulin-resistant individuals, we asked here if the CrPic effect on cells was glucose-dependent. We found that GLUT4 redistribution in cells treated with CrPic occurs only in cells cultured under high glucose (25 mM) conditions that resemble the diabetic-state, and not in cells cultured under non-diabetic (5.5 mM glucose) conditions. Examination of the effect of CrPic on proteins involved in cholesterol homeostasis revealed that the activity of sterol regulatory element-binding protein (SREBP), a membrane-bound transcription factor ultimately responsible for controlling cellular cholesterol balance, was upregulated by CrPic. In addition, ABCA1, a major player in mediating cholesterol efflux was decreased, consistent with SREBP transcriptional repression of the ABCA1 gene. Although the exact mechanism of Cr3+-induced cholesterol loss remains to be determined, these cellular responses highlight a novel and significant effect of chromium on cholesterol homeostasis. Furthermore, these findings provide an important clue to our understanding of how chromium supplementation might benefit hypercholesterolemia-associated disorders. PMID:16870493

Chromium picolinate positively influences the glucose transporter system via affecting cholesterol homeostasis in adipocytes cultured under hyperglycemic diabetic conditions.

PubMed

Pattar, Guruprasad R; Tackett, Lixuan; Liu, Ping; Elmendorf, Jeffrey S

2006-11-07

Since trivalent chromium (Cr(3+)) enhances glucose metabolism, interest in the use of Cr(3+)as a therapy for type 2 diabetes has grown in the mainstream medical community. Moreover, accumulating evidence suggests that Cr(3+) may also benefit cardiovascular disease (CVD) and atypical depression. We have found that cholesterol, a lipid implicated in both CVD and neurodegenerative disorders, also influences cellular glucose uptake. A recent study in our laboratory shows that exposure of 3T3-L1 adipocytes to chromium picolinate (CrPic, 10 nM) induces a loss of plasma membrane cholesterol. Concomitantly, accumulation of intracellularly sequestered glucose transporter GLUT4 at the plasma membrane was dependent on the CrPic-induced cholesterol loss. Since CrPic supplementation has the greatest benefit on glucose metabolism in hyperglycemic insulin-resistant individuals, we asked here if the CrPic effect on cells was glucose-dependent. We found that GLUT4 redistribution in cells treated with CrPic occurs only in cells cultured under high glucose (25 mM) conditions that resemble the diabetic-state, and not in cells cultured under non-diabetic (5.5 mM glucose) conditions. Examination of the effect of CrPic on proteins involved in cholesterol homeostasis revealed that the activity of sterol regulatory element-binding protein (SREBP), a membrane-bound transcription factor ultimately responsible for controlling cellular cholesterol balance, was upregulated by CrPic. In addition, ABCA1, a major player in mediating cholesterol efflux was decreased, consistent with SREBP transcriptional repression of the ABCA1 gene. Although the exact mechanism of Cr(3+)-induced cholesterol loss remains to be determined, these cellular responses highlight a novel and significant effect of chromium on cholesterol homeostasis. Furthermore, these findings provide an important clue to our understanding of how chromium supplementation might benefit hypercholesterolemia-associated disorders.

Adaptation of retrovirus producer cells to serum deprivation: Implications in lipid biosynthesis and vector production.

PubMed

Rodrigues, A F; Amaral, A I; Veríssimo, V; Alves, P M; Coroadinha, A S

2012-05-01

The manufacture of enveloped virus, particularly retroviral (RV) and lentiviral (LV) vectors, faces the challenge of low titers that are aggravated under serum deprivation culture conditions. Also, the scarce knowledge on the biochemical pathways related with virus production is still limiting the design of rational strategies for improved production yields. This work describes the adaptation to serum deprivation of two human RV packaging cell lines, 293 FLEX and Te Fly and its effects on lipid biosynthetic pathways and infectious vector production. Total lipid content as well as cellular cholesterol were quantified and lipid biosynthesis was assessed by (13)C-NMR spectroscopy; changes in gene expression of lipid biosynthetic enzymes were also evaluated. The effects of adaptation to serum deprivation in lipid biosynthesis were cell line specific and directly correlated with infectious virus titers: 293 FLEX cells faced severe lipid starvation-up to 50% reduction in total lipid content-along with a 68-fold reduction in infectious vector titers; contrarily, Te Fly cells were able to maintain identical levels of total lipid content by rising de novo lipid biosynthesis, particularly for cholesterol-50-fold increase-with the consequent recovery of infectious vector productivities. Gene expression analysis of lipid biosynthetic enzymes further confirmed cholesterol production pathway to be prominently up-regulated under serum deprivation conditions for Te Fly cells, providing a genotype-phenotype validation for enhanced cholesterol synthesis. These results highlight lipid metabolism dynamics and the ability to activate lipid biosynthesis under serum deprivation as an important feature for high retroviral titers. Mechanisms underlying virus production and its relationship with lipid biosynthesis, with special focus on cholesterol, are discussed as potential targets for cellular metabolic engineering. Copyright © 2011 Wiley Periodicals, Inc.

Upregulation of cholesterol 24-hydroxylase following hypoxia-ischemia in neonatal mouse brain.

PubMed

Lu, Fuxin; Zhu, Jun; Guo, Selena; Wong, Brandon J; Chehab, Farid F; Ferriero, Donna M; Jiang, Xiangning

2018-06-01

BackgroundMaintenance of cholesterol homeostasis is crucial for brain development. Brain cholesterol relies on de novo synthesis and is cleared primarily by conversion to 24S-hydroxycholesterol (24S-HC) with brain-specific cholesterol 24-hydroxylase (CYP46A1). We aimed to investigate the impact of hypoxia-ischemia (HI) on brain cholesterol metabolism in the neonatal mice.MethodsPostnatal day 9 C57BL/6 pups were subjected to HI using the Vannucci model. CYP46A1 expression was assessed with western blotting and its cellular localization was determined using immunofluorescence staining. The amount of brain cholesterol, 24S-HC in the cortex and in the serum, was measured with enzyme-linked immunosorbent assay (ELISA).ResultsThere was a transient cholesterol loss at 6 h after HI. CYP46A1 was significantly upregulated at 6 and 24 h following HI with a concomitant increase of 24S-HC in the ipsilateral cortex and in the serum. The serum levels of 24S-HC correlated with those in the brain, as well as with necrotic and apoptotic cell death evaluated by the expression of spectrin breakdown products and cleaved caspase-3 at 6 and 24 h after HI.ConclusionEnhanced cholesterol turnover by activation of CYP46A1 represents disrupted brain cholesterol homeostasis early after neonatal HI. 24S-HC might be a novel blood biomarker for severity of hypoxic-ischemic encephalopathy with potential clinical application.

Retinal and Nonocular Abnormalities in Cyp27a1−/−Cyp46a1−/− Mice with Dysfunctional Metabolism of Cholesterol

PubMed Central

Saadane, Aicha; Mast, Natalia; Charvet, Casey D.; Omarova, Saida; Zheng, Wenchao; Huang, Suber S.; Kern, Timothy S.; Peachey, Neal S.; Pikuleva, Irina A.

2015-01-01

Cholesterol elimination from nonhepatic cells involves metabolism to side-chain oxysterols, which serve as transport forms of cholesterol and bioactive molecules modulating a variety of cellular processes. Cholesterol metabolism is tissue specific, and its significance has not yet been established for the retina, where cytochromes P450 (CYP27A1 and CYP46A1) are the major cholesterol-metabolizing enzymes. We generated Cyp27a1−/−Cyp46a1−/− mice, which were lean and had normal serum cholesterol and glucose levels. These animals, however, had changes in the retinal vasculature, retina, and several nonocular organs (lungs, liver, and spleen). Changes in the retinal vasculature included structural abnormalities (retinal-choroidal anastomoses, arteriovenous shunts, increased permeability, dilation, nonperfusion, and capillary degeneration) and cholesterol deposition and oxidation in the vascular wall, which also exhibited increased adhesion of leukocytes and activation of the complement pathway. Changes in the retina included increased content of cholesterol and its metabolite, cholestanol, which were focally deposited at the apical and basal sides of the retinal pigment epithelium. Retinal macrophages of Cyp27a1−/−Cyp46a1−/− mice were activated, and oxidative stress was noted in their photoreceptor inner segments. Our findings demonstrate the importance of retinal cholesterol metabolism for maintenance of the normal retina, and suggest new targets for diseases affecting the retinal vasculature. PMID:25065682

Inhibition of Bufo arenarum oocyte maturation induced by cholesterol depletion by methyl-beta-cyclodextrin. Role of low-density caveolae-like membranes.

PubMed

Buschiazzo, Jorgelina; Bonini, Ida C; Alonso, Telma S

2008-06-01

The invaginated structure of caveolae seems to provide an optimal environment for hormone binding leading to oocyte meiotic maturation. We conducted a quantitative analysis of lipids and proteins of detergent-free low-density membranes isolated from Bufo arenarum oocytes and we modulated cellular cholesterol to further understand how these domains perform their regulatory functions in the amphibian system. Light membranes derive from the plasma membrane as suggested by the enrichment in the activity of 5'nucleotidase. Lipid analysis by chromatography techniques revealed that this fraction is enriched in phosphatidylserine and cholesterol and that it evidences an important level of sphingomyelin. The finding of a single 21 kDa caveolin in light membranes indicates the presence of caveolae-like structures in B. arenarum oocytes. In support of this finding, c-Src is significantly associated to this fraction. Cholesterol content of oocytes treated with methyl-beta-cyclodextrin (MbetaCD) decreased when compared to control oocytes. Drug treatment inhibited meiotic maturation in a dose-dependent manner and affected the localization of caveolin and c-Src among membrane fractions. Repletion of cholesterol showed a recovery of the ability of MbetaCD-treated oocytes to mature, particularly at the 25 mM concentration in which reversibility was close to the control level. Results highlight the importance of caveolae-like microdomains for maturation signaling in Bufo oocytes.

AMP-activated protein kinase: Role in metabolism and therapeutic implications.

PubMed

Schimmack, Greg; Defronzo, Ralph A; Musi, Nicolas

2006-11-01

AMP-activated protein kinase (AMPK) is an enzyme that works as a fuel gauge which becomes activated in situations of energy consumption. AMPK functions to restore cellular ATP levels by modifying diverse metabolic and cellular pathways. In the skeletal muscle, AMPK is activated during exercise and is involved in contraction-stimulated glucose transport and fatty acid oxidation. In the heart, AMPK activity increases during ischaemia and functions to sustain ATP, cardiac function and myocardial viability. In the liver, AMPK inhibits the production of glucose, cholesterol and triglycerides and stimulates fatty acid oxidation. Recent studies have shown that AMPK is involved in the mechanism of action of metformin and thiazolidinediones, and the adipocytokines leptin and adiponectin. These data, along with evidence that pharmacological activation of AMPK in vivo improves blood glucose homeostasis, cholesterol concentrations and blood pressure in insulin-resistant rodents, make this enzyme an attractive pharmacological target for the treatment of type 2 diabetes, ischaemic heart disease and other metabolic diseases.

Cholesterol-dependent energy transfer between fluorescent proteins-insights into protein proximity of APP and BACE1 in different membranes in Niemann-Pick type C disease cells.

PubMed

von Einem, Bjoern; Weber, Petra; Wagner, Michael; Malnar, Martina; Kosicek, Marko; Hecimovic, Silva; Arnim, Christine A F von; Schneckenburger, Herbert

2012-11-26

Förster resonance energy transfer (FRET) -based techniques have recently been applied to study the interactions between β-site APP-cleaving enzyme-GFP (BACE1-GFP) and amyloid precursor protein-mRFP (APP-mRFP) in U373 glioblastoma cells. In this context, the role of APP-BACE1 proximity in Alzheimer's disease (AD) pathogenesis has been discussed. FRET was found to depend on intracellular cholesterol levels and associated alterations in membrane stiffness. Here, NPC1 null cells (CHO-NPC1-/-), exhibiting increased cholesterol levels and disturbed cholesterol transport similar to that observed in Niemann-Pick type C disease (NPC), were used to analyze the influence of altered cholesterol levels on APP-BACE1 proximity. Fluorescence lifetime measurements of whole CHO-wild type (WT) and CHO-NPC1-/- cells (EPI-illumination microscopy), as well as their plasma membranes (total internal reflection fluorescence microscopy, TIRFM), were performed. Additionally, generalized polarization (GP) measurements of CHO-WT and CHO-NPC1-/- cells incubated with the fluorescence marker laurdan were performed to determine membrane stiffness of plasma- and intracellular-membranes. CHO-NPC1-/- cells showed higher membrane stiffness at intracellular- but not plasma-membranes, equivalent to cholesterol accumulation in late endosomes/lysosomes. Along with higher membrane stiffness, the FRET efficiency between BACE1-GFP and APP-mRFP was reduced at intracellular membranes, but not within the plasma membrane of CHO-NPC1-/-. Our data show that FRET combined with TIRF is a powerful technique to determine protein proximity and membrane fluidity in cellular models of neurodegenerative diseases.

Polyphenol-rich black chokeberry (Aronia melanocarpa) extract regulates the expression of genes critical for intestinal cholesterol flux in Caco-2 cells.

PubMed

Kim, Bohkyung; Park, Youngki; Wegner, Casey J; Bolling, Bradley W; Lee, Jiyoung

2013-09-01

Black chokeberry (Aronia melanocarpa) is a rich source of polyphenols. The hypolipidemic effects of polyphenol-rich black chokeberry extract (CBE) have been reported, but underlying mechanisms have not been well characterized. We investigated the effect of CBE on the expression of genes involved in intestinal lipid metabolism. Caco-2 cells were incubated with 50 or 100 μg/ml of CBE for 24 h for quantitative realtime polymerase chain reaction analysis. Expression of genes for cholesterol synthesis (3-hydroxy-3-methylglutaryl coenzyme A reductase and sterol regulatory element binding protein 2), apical cholesterol uptake (Niemann-Pick C1 Like 1 and scavenger receptor class B Type 1) and basolateral cholesterol efflux [ATP-binding cassette transporter A1 (ABCA1)] was significantly decreased by CBE compared with control. Western blot analysis confirmed that CBE inhibited expression of these proteins. In contrast, CBE markedly induced mRNA and/or protein levels of ABCG5 and ABCG8 that mediate apical cholesterol efflux to the intestinal lumen. Furthermore, CBE significantly increased mRNA and protein levels of low-density lipoprotein (LDL) receptor, and cellular LDL uptake. Expression of genes involved in lipid metabolism and lipoprotein assembly, including sterol regulatory element-binding protein 1c, fatty acid synthase and acyl-CoA oxidase 1, was significantly decreased by CBE in a dose-dependent manner. Concomitantly, CBE significantly increased sirtuin 1, 3 and 5 mRNA levels, while it decreased SIRT-2. Our data suggest that hypolipidemic effects of CBE may be attributed, at least in part, to increased apical efflux of LDL-derived cholesterol and to decreased chylomicron formation in the intestine; and specific isoforms of SIRT may play an important role in this process. Copyright © 2013 Elsevier Inc. All rights reserved.

Gender specific effect of LIPC C-514T polymorphism on obesity and relationship with plasma lipid levels in Chinese children.

PubMed

Wang, Hao; Zhang, Dandan; Ling, Jie; Lu, Wenhui; Zhang, Shuai; Zhu, Yimin; Lai, Maode

2015-09-01

Hepatic lipase (LIPC) is a key rate-limiting enzyme in lipoprotein catabolism pathways involved in the development of obesity. The C-514T polymorphism in the promoter region is associated with decreased LIPC activity. We performed a case-controlled study (850 obese children and 2119 controls) and evaluated the association between LIPC C-514T polymorphism, obesity and plasma lipid profile in Chinese children and adolescents. Additionally, we conducted a meta-analysis of all results from published studies as well as our own data. A significant association between the polymorphism and obesity is observed in boys (P = 0.042), but not in girls. And we observed a significant relationship of the polymorphism with total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) independent of obesity in boys. The T allele carriers have higher levels of low density lipoprotein cholesterol (LDL-C) in obese boys, and triglyceride (TG), TC and LDL-C in non-obese girls (all P < 0.05). In the meta-analysis, under dominant model the T allele increased body mass index (BMI) level in boys, while it decreased BMI in girls, and increased the levels of TC both in the overall and subgroups, TG and HDL-C in the overall and boys, and LDL-C in the overall (all P < 0.05). Our results suggest that the T allele might carry an increased risk of obesity in Chinese boys. The meta-analysis suggests that T allele acts as a risk allele for higher BMI levels in male childhood, while it is a protective allele in female childhood. And the polymorphism is associated with the levels of plasma lipids, which may be modulated by obesity and gender. © 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Mechanisms of Alcohol Induced Effects on Cellular Cholesterol Dynamics

DTIC Science & Technology

2004-09-01

intracellular heavy drinking (25 and 50 maM) significantly inhibited trafficking of cholesterol [26]. SCP-2 decreases the half- cholesterol efflux...at least 5-6 drinks contain more cholesterol as com- brane and other structures [10]. Chronic ethanol con- pared to moderate drinkers. Therefore...tetramer BODIPY TR ceramide, N-((4-(4,4-difluoro-5-(2-thienyl)-4- bora -3a,4a- (28), and such structural differences could alter the behavior of diaza-s

Ombuin-3-O-β-D-glucopyranoside from Gynostemma pentaphyllum is a dual agonistic ligand of peroxisome proliferator-activated receptors α and δ/β

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malek, Mastura Abd; Hoang, Minh-Hien; Jia, Yaoyao

Highlights: ► Ombuin-3-O-β-D-glucopyranoside is a dual ligand for PPARα and δ/β. ► Ombuin-3-O-β-D-glucopyranoside reduces cellular lipid levels in multiple cell types. ► Cells stimulated with ombuine up-regulated target genes in cholesterol efflux. ► Cells stimulated with ombuine regulated target fatty acid β-oxidation and synthesis. ► Ombuin-3-O-β-D-glucopyranoside could ameliorate hyperlipidemia and hepatic steatosis. -- Abstract: We demonstrated that ombuin-3-O-β-D-glucopyranoside (ombuine), a flavonoid from Gynostemma pentaphyllum, is a dual agonist for peroxisome proliferator-activated receptors (PPARs) α and δ/β. Using surface plasmon resonance (SPR), time-resolved fluorescence resonance energy transfer (FRET) analyses, and reporter gene assays, we showed that ombuine bound directly to PPARαmore » and δ/β but not to PPARγ or liver X receptors (LXRs). Cultured HepG2 hepatocytes stimulated with ombuine significantly reduced intracellular concentrations of triglyceride and cholesterol and downregulated the expression of lipogenic genes, including sterol regulatory element binding protein-1c (SREBP1c) and stearoyl-CoA desaturase-1 (SCD-1), with activation of PPARα and δ/β. Activation of LXRs by ombuine was confirmed by reporter gene assays, however, SPR and cell-based FRET assays showed no direct binding of ombuine to either of the LXRs suggesting LXR activation by ombuine may be operated via PPARα stimulation. Ombuine-stimulated macrophages showed significantly induced transcription of ATP binding cassette cholesterol transporter A1 (ABCA1) and G1 (ABCG1), the key genes in reverse cholesterol transport, which led to reduced cellular cholesterol concentrations. These results suggest that ombuine is a dual PPAR ligand for PPARα and δ/β with the ability to decrease lipid concentrations by reducing lipogenic gene expression in hepatocytes and inducing genes involved in cholesterol efflux in macrophages.« less

Simvastatin promotes NPC1-mediated free cholesterol efflux from lysosomes through CYP7A1/LXRα signalling pathway in oxLDL-loaded macrophages.

PubMed

Xu, Xiaoyang; Zhang, Aolin; Halquist, Matthew S; Yuan, Xinxu; Henderson, Scott C; Dewey, William L; Li, Pin-Lan; Li, Ningjun; Zhang, Fan

2017-02-01

Statins, 3-hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors, are the first-line medications prescribed for the prevention and treatment of coronary artery diseases. The efficacy of statins has been attributed not only to their systemic cholesterol-lowering actions but also to their pleiotropic effects that are unrelated to cholesterol reduction. These pleiotropic effects have been increasingly recognized as essential in statins therapy. This study was designed to investigate the pleiotropic actions of simvastatin, one of the most commonly prescribed statins, on macrophage cholesterol homeostasis with a focus on lysosomal free cholesterol egression. With simultaneous nile red and filipin staining, analysis of confocal/multi-photon imaging demonstrated that simvastatin markedly attenuated unesterified (free) cholesterol buildup in macrophages loaded with oxidized low-density lipoprotein but had little effect in reducing the sizes of cholesteryl ester-containing lipid droplets; the reduction in free cholesterol was mainly attributed to decreases in lysosome-compartmentalized cholesterol. Functionally, the egression of free cholesterol from lysosomes attenuated pro-inflammatory cytokine secretion. It was determined that the reduction of lysosomal free cholesterol buildup by simvastatin was due to the up-regulation of Niemann-Pick C1 (NPC1), a lysosomal residing cholesterol transporter. Moreover, the enhanced enzymatic production of 7-hydroxycholesterol by cytochrome P450 7A1 and the subsequent activation of liver X receptor α underscored the up-regulation of NPC1. These findings reveal a novel pleiotropic effect of simvastatin in affecting lysosomal cholesterol efflux in macrophages and the associated significance in the treatment of atherosclerosis. © 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Activation of AMP-kinase by Policosanol Requires Peroxisomal Metabolism

PubMed Central

Banerjee, Subhashis; Ghoshal, Sarbani

2011-01-01

Policosanol, a well-defined mixture of very long chain primary alcohols that is available as a nutraceutical product, has been reported to lower blood cholesterol levels. The present studies demonstrate that policosanol promotes the phosphorylation of AMP-kinase and HMG-CoA reductase in hepatoma cells and in mouse liver after intragastric administration, providing a possible means by which policosanol might lower blood cholesterol levels. Treatment of hepatoma cells with policosanol produced a 2.5-fold or greater increase in the phosphorylation of AMP-kinase and HMG-CoA reductase, and increased the phosphorylation of Ca++/calmodulin-dependent kinase kinase (CaMKK), an upstream AMP-kinase kinase. Intra-gastric administration of policosanol to mice similarly increased the phosphorylation of hepatic HMG-CoA reductase and AMP-kinase by greater than 2-fold. siRNA-mediated suppression of fatty aldehyde dehydrogenase, fatty acyl-CoA synthetase 4, and acyl-CoA acetyltransferase expression in hepatoma cells prevented the phosphorylation of AMP-kinase and HMG-CoA reductase by policosanol, indicating that metabolism of these very long chain alcohols to activated fatty acids is necessary for the suppression of cholesterol synthesis, presumably by increasing cellular AMP levels. Subsequent peroxisomal β-oxidation probably augments this effect. PMID:21359855

Cellular Cholesterol Accumulation Facilitates Ubiquitination and Lysosomal Degradation of Cell Surface-Resident ABCA1.

PubMed

Mizuno, Tadahaya; Hayashi, Hisamitsu; Kusuhara, Hiroyuki

2015-06-01

By excreting cellular cholesterol to apolipoprotein A-I, ATP-binding cassette transporter A1 (ABCA1) mediates the biogenesis of high-density lipoprotein in hepatocytes and prevents foam cell formation from macrophages. We recently showed that cell surface-resident ABCA1 (csABCA1) undergoes ubiquitination and later lysosomal degradation through the endosomal sorting complex required for transport system. Herein, we investigated the relevance of this degradation pathway to the turnover of csABCA1 in hypercholesterolemia. Immunoprecipitation and cell surface-biotinylation studies with HepG2 cells and mouse peritoneal macrophages showed that the ubiquitination level and degradation of csABCA1 were facilitated by treatment with a liver X receptor (LXR) agonist and acetylated low-density lipoprotein. The effects of an LXR agonist and acetylated low-density lipoprotein on the degradation of csABCA1 were repressed completely by treatment with bafilomycin, an inhibitor of lysosomal degradation, and by depletion of tumor susceptibility gene 101, a major component of endosomal sorting complex required for transport-I. RNAi analysis indicated that LXRβ inhibited the accelerated lysosomal degradation of csABCA1 by the LXR agonist, regardless of its transcriptional activity. Cell surface coimmunoprecipitation with COS1 cells expressing extracellularly hemagglutinin-tagged ABCA1 showed that LXRβ interacted with csABCA1 and inhibited the ubiquitination of csABCA1. Immunoprecipitates with anti-ABCA1 antibodies from the liver plasma membranes showed less LXRβ and a higher ubiquitination level of ABCA1 in high-fat diet-fed mice than in normal chow-fed mice. Under conditions of high cellular cholesterol content, csABCA1 became susceptible to ubiquitination by dissociation of LXRβ from csABCA1, which facilitated the lysosomal degradation of csABCA1 through the endosomal sorting complex required for transport system. © 2015 American Heart Association, Inc.

The Bladder Tumor Suppressor Protein TERE1 (UBIAD1)Modulates Cell Cholesterol: Implications for Tumor Progression

PubMed Central

McGarvey, Terry; Wang, Huiyi; Lal, Priti; Puthiyaveettil, Raghunath; Tomaszewski, John; Sepulveda, Jorge; Labelle, Ed; Weiss, Jayne S.; Nickerson, Michael L.; Kruth, Howard S.; Brandt, Wolfgang; Wessjohann, Ludger A.; Malkowicz, S. Bruce

2011-01-01

Convergent evidence implicates the TERE1 protein in human bladder tumor progression and lipid metabolism. Previously, reduced TERE1 expression was found in invasive urologic cancers and inhibited cell growth upon re-expression. A role in lipid metabolism was suggested by TERE1 binding to APOE, a cholesterol carrier, and to TBL2, a candidate protein in triglyceride disorders. Natural TERE1 mutations associate with Schnyder's corneal dystrophy, characterized by lipid accumulation. TERE1 catalyzes menaquinone synthesis, known to affect cholesterol homeostasis. To explore this relationship, we altered TERE1 and TBL2 dosage via ectopic expression and interfering RNA and measured cholesterol by Amplex red. Protein interactions of wild-type and mutant TERE1 with GST-APOE were evaluated by binding assays and molecular modeling. We conducted a bladder tumor microarray TERE1 expression analysis and assayed tumorigenicity of J82 cells ectopically expressing TERE1. TERE1 expression was reduced in a third of invasive specimens. Ectopic TERE1 expression in J82 bladder cancer cells dramatically inhibited nude mouse tumorigenesis. TERE1 and TBL2 proteins inversely modulated cellular cholesterol in HEK293 and bladder cancer cells from 20% to 50%. TERE1 point mutations affected APOE interactions, and resulted in cholesterol levels that differed from wild type. Elevated tumor cell cholesterol is known to affect apoptosis and growth signaling; thus, loss of TERE1 in invasive bladder cancer may represent a defect in menaquinone-mediated cholesterol homeostasis that contributes to progression. PMID:21740188

Phospholipase A2-treated human high-density lipoprotein and cholesterol movements: exchange processes and lecithin: cholesterol acyltransferase reactivity.

PubMed

Chollet, F; Perret, B P; Chap, H; Douste-Blazy, L

1986-02-12

Human HDL3 (d 1.125-1.21 g/ml) were treated by an exogenous phospholipase A2 from Crotalus adamenteus in the presence of albumin. Phosphatidylcholine hydrolysis ranged between 30 and 90% and the reisolated particle was essentially devoid of lipolysis products. (1) An exchange of free cholesterol was recorded between radiolabelled erythrocytes at 5-10% haematocrit and HDL3 (0.6 mM total cholesterol) from 0 to 12-15 h. Isotopic equilibration was reached. Kinetic analysis of the data indicated a constant rate of free cholesterol exchange of 13.0 microM/h with a half-time of equilibration around 3 h. Very similar values of cholesterol exchange, specific radioactivities and kinetic parameters were measured when phospholipase-treated HDL replaced control HDL. (2) The lecithin: cholesterol acyltransferase reactivity of HDL3, containing different amounts of phosphatidylcholine, as achieved by various degrees of phospholipase A2 treatment, was measured using a crude preparation of lecithin: cholesterol acyltransferase (the d 1.21-1.25 g/ml plasma fraction). The rate of esterification was determined between 0 and 12 h. Following a 15-30% lipolysis, the lecithin: cholesterol acyltransferase reactivity of HDL3 was reduced about 30-40%, and then continued to decrease, though more slowly, as the phospholipid content was further lowered in the particle. (3) The addition of the lecithin: cholesterol acyltransferase preparation into an incubation medium made of labelled erythrocytes and HDL3 promoted a movement of radioactive cholesterol out of cells, above the values of exchange, and an accumulation of cholesteryl esters in HDL. This reflected a mass consumption of free cholesterol, from both the cellular and the lipoprotein compartments upon the lecithin: cholesterol acyltransferase action. As a consequence of a decreased reactivity, phospholipase-treated HDL (with 2/3 of phosphatidylcholine hydrolyzed) proved much less effective in the lecithin: cholesterol acyltransferase-induced removal of cellular cholesterol.

The 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductases

PubMed Central

Friesen, Jon A; Rodwell, Victor W

2004-01-01

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase catalyzes the conversion of HMG-CoA to mevalonate, a four-electron oxidoreduction that is the rate-limiting step in the synthesis of cholesterol and other isoprenoids. The enzyme is found in eukaryotes and prokaryotes; and phylogenetic analysis has revealed two classes of HMG-CoA reductase, the Class I enzymes of eukaryotes and some archaea and the Class II enzymes of eubacteria and certain other archaea. Three-dimensional structures of the catalytic domain of HMG-CoA reductases from humans and from the bacterium Pseudomonas mevalonii, in conjunction with site-directed mutagenesis studies, have revealed details of the mechanism of catalysis. The reaction catalyzed by human HMG-CoA reductase is a target for anti-hypercholesterolemic drugs (statins), which are intended to lower cholesterol levels in serum. Eukaryotic forms of the enzyme are anchored to the endoplasmic reticulum, whereas the prokaryotic enzymes are soluble. Probably because of its critical role in cellular cholesterol homeostasis, mammalian HMG-CoA reductase is extensively regulated at the transcriptional, translational, and post-translational levels. PMID:15535874

Nogo-B Receptor stabilizes Niemann-Pick Type C2 protein and regulates intracellular cholesterol trafficking

PubMed Central

Harrison, Kenneth D.; Miao, Robert Qing; Fernandez-Hernándo, Carlos; Suárez, Yajaira; Dávalos, Alberto; Sessa, William C.

2009-01-01

Summary The Nogo-B Receptor (NgBR) is a recently identified receptor for the N-terminus of Reticulon 4B/Nogo-B. Other than its role in binding Nogo-B, little is known about the biology of NgBR. To elucidate a basic cellular role for NgBR, we performed a yeast-2-hybrid screen for interacting proteins using the C-terminal domain as bait and identified Niemann-Pick Type C2 protein (NPC2) as an NgBR-interacting protein. NPC2 protein levels are increased in the presence of NgBR and NgBR enhances NPC2 protein stability. NgBR localizes primarily to the endoplasmic reticulum (ER), and regulates the stability of nascent NPC2. RNAi-mediated disruption of NgBR or genetic deficiency in NgBR leads to a decrease in NPC2 levels, increased intracellular cholesterol accumulation and a loss of sterol sensing, all hallmarks of an NPC2 mutation. These data identify NgBR as an NPC2-interacting protein and provide evidence of a role for NgBR in intracellular cholesterol trafficking. PMID:19723497

Hypolipidemic effect of dietary pea proteins: Impact on genes regulating hepatic lipid metabolism.

PubMed

Rigamonti, Elena; Parolini, Cinzia; Marchesi, Marta; Diani, Erika; Brambilla, Stefano; Sirtori, Cesare R; Chiesa, Giulia

2010-05-01

Controversial data on the lipid-lowering effect of dietary pea proteins have been provided and the mechanisms behind this effect are not completely understood. The aim of the study was to evaluate a possible hypolipidemic activity of a pea protein isolate and to determine whether pea proteins could affect the hepatic lipid metabolism through regulation of genes involved in cholesterol and fatty acid homeostasis. Rats were fed Nath's hypercholesterolemic diets for 28 days, the protein sources being casein or a pea protein isolate from Pisum sativum. After 14 and 28 days of dietary treatment, rats fed pea proteins had markedly lower plasma cholesterol and triglyceride levels than rats fed casein (p<0.05). Pea protein-fed rats displayed higher hepatic mRNA levels of LDL receptor versus those fed casein (p<0.05). Hepatic mRNA concentration of genes involved in fatty acids synthesis, such as fatty acid synthase and stearoyl-CoA desaturase, was lower in pea protein-fed rats than in rats fed casein (p<0.05). In conclusion, the present study demonstrates a marked cholesterol and triglyceride-lowering activity of pea proteins in rats. Moreover, pea proteins appear to affect cellular lipid homeostasis by upregulating genes involved in hepatic cholesterol uptake and by downregulating fatty acid synthesis genes.

Synthesis and Characterization of Biomimetic High Density Lipoprotein Nanoparticles To Treat Lymphoma

NASA Astrophysics Data System (ADS)

Damiano, Marina Giacoma

High density lipoproteins (HDLs), natural nanoparticles that function as vehicles for cholesterol transport, have enhanced uptake by several human cancers. This uptake is mediated, in part, by the high affinity HDL receptor, scavenger receptor B-1 (SR-B1). More specifically, studies show that the rate of cellular proliferation of lymphoma, a cancer of the lymphocytes, is directly proportional to the amount of HDL-cholesterol available. Thus, targeting of HDL-cholesterol uptake by these cells could be an effective therapeutic approach that may have lower toxicity to healthy cells compared to conventional therapies. Biomimetic HDL can be synthesized using a gold nanoparticle template (HDL-AuNPs), which provides control over size, shape, and surface chemistry. Like their natural counterparts, HDL-AuNPs sequester cholesterol. However, since the gold nanoparticle replaces the cholesterol core of natural HDL, HDL-AuNPs inherently deliver less cholesterol. We show that HDL-AuNPs are able to induce dose dependent apoptosis in B cell lymphoma cell lines and reduce tumor volume following systemic administration to mice bearing B cell lymphoma tumors. Furthermore, HDL-AuNPs are neither toxic to healthy human lymphocytes (SR-B1-), nor to hepatocytes and macrophages (SR-B1+), which are cells naturally encountered by HDLs. Manipulation of cholesterol flux and targeting of SR-B1 are responsible for the efficacy of HDL-AuNPs against B cell lymphoma. HDL-AuNPs could be used to treat B cell lymphomas and other diseases that involve pathologic accumulation of cholesterol. Titanium dioxide nanoparticle (TiO2 NP) core HDLs (HDL-TiO 2 NPs) have been synthesized for high resolution cellular localization studies and for future use as a therapeutic and imaging agent. In initial studies, HDL-TiO(2 NPs display maximum uptake in B cell lymphoma cell lines. X-ray fluorescence microscopy studies show interaction between HDL-TiO2 NPs and cells 10 minutes after treatment and internalization after 1 hour. HDL-TiO2 NPs induce apoptosis in B cell lymphoma cell lines. These results suggest that HDL-TiO2 NPs may be used as therapeutics for lymphoma and other cancers by inducing apoptosis through manipulation of cellular cholesterol flux.

Synergetic cholesterol-lowering effects of main alkaloids from Rhizoma Coptidis in HepG2 cells and hypercholesterolemia hamsters.

PubMed

Kou, Shuming; Han, Bing; Wang, Yue; Huang, Tao; He, Kai; Han, Yulong; Zhou, Xia; Ye, Xiaoli; Li, Xuegang

2016-04-15

Hyperlipidemia contributes to the progression of cardiovascular diseases. Main alkaloids from Rhizoma Coptidis including berberine (BBR), coptisine (COP), palmatine (PAL), epiberberine (EPI) and jatrorrhizine (JAT), improved dyslipidemia in hypercholesterolemic hamsters to a different degree. In this study, HepG2 cells and hypercholesterolemic hamsters were used to investigate the synergetic cholesterol-lowering efficacy of these five main alkaloids. The cellular lipid and cholesterol accumulation and in HepG2 cells were evaluated by Oil Red O staining and HPLC analysis. LDL receptor, 3-Hydroxy-3-methylglutaryl CoA reductase (HMGCR) and cholesterol 7-alpha-hydroxylase (CYP7A1) that involving cholesterol metabolism in HepG2 cells were measured by qRT-PCR, western blot and immunofluorescence analysis. The serum profiles including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c), as well as TC and total bile acids (TBA) of feces in hypercholesterolemic hamsters were also measured. As compared to single alkaloids, the combination of five main alkaloids (COM) reduced the lipid and cholesterol accumulation in HepG2 cells more effectively and performed an advantageous effect on controlling TC, TG, LDL-c and HDL-c in hypercholesterolemic hamsters. More effective reduction of TBA and TC levels in feces of hamsters were achieved after the administration of COM. These effects were derived from the up-regulation of LDL receptor and CYP7A1, as well as HMGCR downregulation. Our results demonstrated that COM showed a synergetic cholesterol-lowering efficacy, which was better than single alkaloids and it might be considered as a potential therapy for hypercholesterolemia. Copyright © 2016 Elsevier Inc. All rights reserved.

Addressable Cholesterol Analogs for Live Imaging of Cellular Membranes.

PubMed

Rakers, Lena; Grill, David; Matos, Anna L L; Wulff, Stephanie; Wang, Da; Börgel, Jonas; Körsgen, Martin; Arlinghaus, Heinrich F; Galla, Hans-Joachim; Gerke, Volker; Glorius, Frank

2018-05-01

Cholesterol is an essential component of most biological membranes and serves important functions in controlling membrane integrity, organization, and signaling. However, probes to follow the dynamic distribution of cholesterol in live cells are scarce and so far show only limited applicability. Herein, we addressed this problem by synthesizing and characterizing a class of versatile and clickable cholesterol-based imidazolium salts. We show that these cholesterol analogs faithfully mimic the biophysical properties of natural cholesterol in phospholipid mono- and bilayers, and that they integrate into the plasma membrane of cultured and primary human cells. The membrane-incorporated cholesterol analogs can be specifically labeled by click chemistry and visualized in live-cell imaging experiments that show a distribution and behavior comparable with that of endogenous membrane cholesterol. These results indicate that the cholesterol analogs can be used to reveal the dynamic distribution of cholesterol in live cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

In situ localization of the genetic locus encoding the lysosomal acid lipase/cholesteryl esterase (LIPA) deficient in wolman disease to chromosome 10q23. 2-q23. 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, R.A.; Rao, N.; Byrum, R.S.

1993-01-01

Human acid lipase/cholesteryl esterase (EC 3.1.1.13) is a 46-kDa glycoprotein required for the lysosomal hydrolysis of cholesteryl esters and triglycerides that cells acquire through the receptor-mediated endocytosis of low-density lipoproteins. This activity is essential in the provision of free cholesterol for cell metabolism as well as for the feedback signal that modulates endogenous cellular cholesterol production. The extremely low level of lysosomal acid lipase in patients afflicted with the hereditary, allelic lysosomal storage disorders Woman disease (WD) and cholesteryl ester storage disease (CESD) (MIM Number 278000 (6)) is associated with the massive intralysosomal lipid storage and derangements in the regulationmore » of cellular cholesterol production (10). Both WD and CESD cells lack a specific acid lipase isoenzyme and it is thought that the different mutations associated with WD and CESD are in the structural gene for this isoenzyme, LIPA. Analysis of the activity of the acid lipase isoenzyme in cell extracts from human-Chinese hamster somatic cell hybrids (4, 11) demonstrated the concordant segregation of the gene locus for lysosomal acid lipase with the glutamate oxaloacetate transaminase-1 (GOT1) enzyme marker for human chromosome 10 which was subsequently localized to 10q24.1 q25.1 (8). 11 refs., 1 figs.« less

In Situ and Real-Time SFG Measurements Revealing Organization and Transport of Cholesterol Analogue 6-Ketocholestanol in a Cell Membrane.

PubMed

Ma, Sulan; Li, Hongchun; Tian, Kangzhen; Ye, Shuji; Luo, Yi

2014-02-06

Cholesterol organization and transport within a cell membrane are essential for human health and many cellular functions yet remain elusive so far. Using cholesterol analogue 6-ketocholestanol (6-KC) as a model, we have successfully exploited sum frequency generation vibrational spectroscopy (SFG-VS) to track the organization and transport of cholesterol in a membrane by combining achiral-sensitive ssp (ppp) and chiral-sensitive psp polarization measurements. It is found that 6-KC molecules are aligned at the outer leaflet of the DMPC lipid bilayer with a tilt angle of about 10°. 6-KC organizes itself by forming an α-β structure at low 6-KC concentration and most likely a β-β structure at high 6-KC concentration. Among all proposed models, our results favor the so-called umbrella model with formation of a 6-KC cluster. Moreover, we have found that the long anticipated flip-flop motion of 6-KC in the membrane takes time to occur, at least much longer than previously thought. All of these interesting findings indicate that it is critical to explore in situ, real-time, and label-free methodologies to obtain a precise molecular description of cholesterol's behavior in membranes. This study represents the first application of SFG to reveal the cholesterol-lipid interaction mechanism at the molecular level.

Effects of cholesterol on pore formation in lipid bilayers induced by human islet amyloid polypeptide fragments: A coarse-grained molecular dynamics study

NASA Astrophysics Data System (ADS)

Xu, Weixin; Wei, Guanghong; Su, Haibin; Nordenskiöld, Lars; Mu, Yuguang

2011-11-01

Disruption of the cellular membrane by the amyloidogenic peptide, islet amyloid polypeptide (IAPP), has been considered as one of the mechanisms of β-cell death during type 2 diabetes. The N-terminal region (residues 1-19) of the human version of IAPP is suggested to be primarily responsible for the membrane-disrupting effect of the full-length hIAPP peptide. However, the detailed assembly mode of hIAPP1-19 with membrane remains unclear. To gain insight into the interactions of hIAPP1-19 oligomer with the model membrane, we have employed coarse-grained molecular dynamics self-assembly simulations to study the aggregation of hIAPP1-19 fragments in the binary lipid made of zwitterionic dipalmitoylphosphatidylcholine (DPPC) and anionic dipalmitoylphosphatidylserine (DPPS) in the presence and absence of different levels of cholesterol content. The membrane-destabilizing effect of hIAPP1-19 is found to be modulated by the presence of cholesterol. In the absence of cholesterol, hIAPP1-19 aggregates prefer to locate inside the bilayer, forming pore-like assemblies. While in the presence of cholesterol molecules, the lipid bilayer becomes more ordered and stiff, and the hIAPP1-19 aggregates are dominantly positioned at the bilayer-water interface. The action of cholesterol may suggest a possible way to maintain the membrane integrity by small molecule interference.

Prevention of coronary heart disease: the role of essential fatty acids.

PubMed Central

Sinclair, H. M.

1980-01-01

There are 2 classes of essential fatty acids (EFA), the linoleic (n-6) and linolenic (n-3). They are required for the glycerophosphatides (phospholipids) of cellular membranes; the transport and oxidation of cholesterol; the formation of prostaglandins. In deficiency of EFA, cellular membranes are imperfectly formed which causes increased susceptibility to various insults and increased permeability. Low-density lipoproteins (LDL) transport cholesterol mainly as cholesteryl linoleate and supply EFA to tissue. A relative deficiency of EFA (i.e. a high ratio in the body of non-EFA such as long-chain saturated fatty acids to EFA) causes an increase in plasma cholesterol. EFAs cause decreased aggregation of platelets. Atherosclerosis is not caused by increased aggregation of platelets, and can be prevalent in a population in which coronary thrombosis is rare. PMID:7465462

LRP1 integrates murine macrophage cholesterol homeostasis and inflammatory responses in atherosclerosis

PubMed Central

Zhou, Li; Plattner, Florian; Liu, Mingxia; Parks, John S; Hammer, Robert E; Boucher, Philippe; Tsai, Shirling

2017-01-01

Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifunctional cell surface receptor with diverse physiological roles, ranging from cellular uptake of lipoproteins and other cargo by endocytosis to sensor of the extracellular environment and integrator of a wide range of signaling mechanisms. As a chylomicron remnant receptor, LRP1 controls systemic lipid metabolism in concert with the LDL receptor in the liver, whereas in smooth muscle cells (SMC) LRP1 functions as a co-receptor for TGFβ and PDGFRβ in reverse cholesterol transport and the maintenance of vascular wall integrity. Here we used a knockin mouse model to uncover a novel atheroprotective role for LRP1 in macrophages where tyrosine phosphorylation of an NPxY motif in its intracellular domain initiates a signaling cascade along an LRP1/SHC1/PI3K/AKT/PPARγ/LXR axis to regulate and integrate cellular cholesterol homeostasis through the expression of the major cholesterol exporter ABCA1 with apoptotic cell removal and inflammatory responses. PMID:29144234

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daily, Michael D.; Olsen, Brett N.; Schlesinger, Paul H.

In mammalian cells cholesterol is essential for membrane function, but in excess can be cytototoxic. The cellular response to acute cholesterol loading involves biophysical-based mechanisms that regulate cholesterol levels, through modulation of the “activity” or accessibility of cholesterol to extra-membrane acceptors. Experiments and united atom (UA) simulations show that at high concentrations of cholesterol, lipid bilayers thin significantly and cholesterol availability to external acceptors increases substantially. Such cholesterol activation is critical to its trafficking within cells. Here we aim to reduce the computational cost to enable simulation of large and complex systems involved in cholesterol regulation, such as those includingmore » oxysterols and cholesterol-sensing proteins. To accomplish this, we have modified the published MARTINI coarse-grained force field to improve its predictions of cholesterol-induced changes in both macroscopic and microscopic properties of membranes. Most notably, MARTINI fails to capture both the (macroscopic) area condensation and membrane thickening seen at less than 30% cholesterol and the thinning seen above 40% cholesterol. The thinning at high concentration is critical to cholesterol activation. Microscopic properties of interest include cholesterol-cholesterol radial distribution functions (RDFs), tilt angle, and accessible surface area. First, we develop an “angle-corrected” model wherein we modify the coarse-grained bond angle potentials based on atomistic simulations. This modification significantly improves prediction of macroscopic properties, most notably the thickening/thinning behavior, and also slightly improves microscopic property prediction relative to MARTINI. Second, we add to the angle correction a “volume correction” by also adjusting phospholipid bond lengths to achieve a more accurate volume per molecule. The angle + volume correction substantially further improves the quantitative agreement of the macroscopic properties (area per molecule and thickness) with united atom simulations. However, this improvement also reduces the accuracy of microscopic predictions like radial distribution functions and cholesterol tilt below that of either MARTINI or the angle-corrected model. Thus, while both of our forcefield corrections improve MARTINI, the combined angle and volume correction should be used for problems involving sterol effects on the overall structure of the membrane, while our angle-corrected model should be used in cases where the properties of individual lipid and sterol models are critically important.« less

Neutrophil Membrane Cholesterol Content is a Key Factor in Cystic Fibrosis Lung Disease.

PubMed

White, Michelle M; Geraghty, Patrick; Hayes, Elaine; Cox, Stephen; Leitch, William; Alfawaz, Bader; Lavelle, Gillian M; McElvaney, Oliver J; Flannery, Ryan; Keenan, Joanne; Meleady, Paula; Henry, Michael; Clynes, Martin; Gunaratnam, Cedric; McElvaney, Noel G; Reeves, Emer P

2017-09-01

Identification of mechanisms promoting neutrophil trafficking to the lungs of patients with cystic fibrosis (CF) is a challenge for next generation therapeutics. Cholesterol, a structural component of neutrophil plasma membranes influences cell adhesion, a key step in transmigration. The effect of chronic inflammation on neutrophil membrane cholesterol content in patients with CF (PWCF) remains unclear. To address this we examined neutrophils of PWCF to evaluate the cause and consequence of altered membrane cholesterol and identified the effects of lung transplantation and ion channel potentiator therapy on the cellular mechanisms responsible for perturbed membrane cholesterol and increased cell adhesion. PWCF homozygous for the ΔF508 mutation or heterozygous for the G551D mutation were recruited (n=48). Membrane protein expression was investigated by mass spectrometry. The effect of lung transplantation or ivacaftor therapy was assessed by ELISAs, and calcium fluorometric and μ-calpain assays. Membranes of CF neutrophils contain less cholesterol, yet increased integrin CD11b expression, and respond to inflammatory induced endoplasmic reticulum (ER) stress by activating μ-calpain. In vivo and in vitro, increased μ-calpain activity resulted in proteolysis of the membrane cholesterol trafficking protein caveolin-1. The critical role of caveolin-1 for adequate membrane cholesterol content was confirmed in caveolin-1 knock-out mice. Lung transplant therapy or treatment of PWCF with ivacaftor, reduced levels of circulating inflammatory mediators and actuated increased caveolin-1 and membrane cholesterol, with concurrent normalized neutrophil adhesion. Results demonstrate an auxiliary benefit of lung transplant and potentiator therapy, evident by a reduction in circulating inflammation and controlled neutrophil adhesion. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

A novel therapeutic effect of statins on nephrogenic diabetes insipidus

PubMed Central

Bonfrate, Leonilde; Procino, Giuseppe; Wang, David Q-H; Svelto, Maria; Portincasa, Piero

2015-01-01

Statins competitively inhibit hepatic 3-hydroxy-3-methylglutaryl-coenzyme A reductase, resulting in reduced plasma total and low-density lipoprotein cholesterol levels. Recently, it has been shown that statins exert additional ‘pleiotropic’ effects by increasing expression levels of the membrane water channels aquaporin 2 (AQP2). AQP2 is localized mainly in the kidney and plays a critical role in determining cellular water content. This additional effect is independent of cholesterol homoeostasis, and depends on depletion of mevalonate-derived intermediates of sterol synthetic pathways, i.e. farnesylpyrophosphate and geranylgeranylpyrophosphate. By up-regulating the expression levels of AQP2, statins increase water reabsorption by the kidney, thus opening up a new avenue in treating patients with nephrogenic diabetes insipidus (NDI), a hereditary disease that yet lacks high-powered and limited side effects therapy. Aspects related to water balance determined by AQP2 in the kidney, as well as standard and novel therapeutic strategies of NDI are discussed. PMID:25594563

Impact of oxLDL on Cholesterol-Rich Membrane Rafts

PubMed Central

Levitan, Irena; Shentu, Tzu-Pin

2011-01-01

Numerous studies have demonstrated that cholesterol-rich membrane rafts play critical roles in multiple cellular functions. However, the impact of the lipoproteins on the structure, integrity and cholesterol composition of these domains is not well understood. This paper focuses on oxidized low-density lipoproteins (oxLDLs) that are strongly implicated in the development of the cardiovascular disease and whose impact on membrane cholesterol and on membrane rafts has been highly controversial. More specifically, we discuss three major criteria for the impact of oxLDL on membrane rafts: distribution of different membrane raft markers, changes in membrane cholesterol composition, and changes in lipid packing of different membrane domains. We also propose a model to reconcile the controversy regarding the relationship between oxLDL, membrane cholesterol, and the integrity of cholesterol-rich membrane domains. PMID:21490811

Engineering the lipid layer of lipid-PLGA hybrid nanoparticles for enhanced in vitro cellular uptake and improved stability.

PubMed

Hu, Yun; Hoerle, Reece; Ehrich, Marion; Zhang, Chenming

2015-12-01

Lipid-polymer hybrid nanoparticles (NPs), consisting of a polymeric core and a lipid shell, have been intensively examined as delivery systems for cancer drugs, imaging agents, and vaccines. For applications in vaccine particularly, the hybrid NPs need to be able to protect the enclosed antigens during circulation, easily be up-taken by dendritic cells, and possess good stability for prolonged storage. However, the influence of lipid composition on the performance of hybrid NPs has not been well studied. In this study, we demonstrate that higher concentrations of cholesterol in the lipid layer enable slower and more controlled antigen release from lipid-poly(lactide-co-glycolide) acid (lipid-PLGA) NPs in human serum and phosphate buffered saline (PBS). Higher concentrations of cholesterol also promoted in vitro cellular uptake of hybrid NPs, improved the stability of the lipid layer, and protected the integrity of the hybrid structure during long-term storage. However, stabilized hybrid structures of high cholesterol content tended to fuse with each other during storage, resulting in significant size increase and lowered cellular uptake. Additional experiments demonstrated that PEGylation of NPs could effectively minimize fusion-caused size increase after long term storage, leading to improved cellular uptake, although excessive PEGylation will not be beneficial and led to reduced improvement. This paper reports the engineering of the lipid layer that encloses a polymeric nanoparticle, which can be used as a carrier for drug and vaccine molecules for targeted delivery. We demonstrated that the concentration of cholesterol is critical for the stability and uptake of the hybrid nanoparticles by dendritic cells, a targeted cell for the delivery of immune effector molecules. However, we found that hybrid nanoparticles with high cholesterol concentration tend to fuse during storage resulting in larger particles with decreased cellular uptake. This problem is subsequently solved by PEGylating the hybrid nanoparticles. With increased research and clinical applications of lipid-polymer hybrid nanoparticles in drug and vaccine delivery, this work will significantly impact the design of the hybrid nanoparticles for minimized molecule release during circulation and increased bioavailability of the target molecules. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Lipid accumulation in smooth muscle cells under LDL loading is independent of LDL receptor pathway and enhanced by hypoxic conditions.

PubMed

Wada, Youichiro; Sugiyama, Akira; Yamamoto, Takashi; Naito, Makoto; Noguchi, Noriko; Yokoyama, Shinji; Tsujita, Maki; Kawabe, Yoshiki; Kobayashi, Mika; Izumi, Akashi; Kohro, Takahide; Tanaka, Toshiya; Taniguchi, Hirokazu; Koyama, Hidenori; Hirano, Ken-ichi; Yamashita, Shizuya; Matsuzawa, Yuji; Niki, Etsuo; Hamakubo, Takao; Kodama, Tatsuhiko

2002-10-01

The effect of a variety of hypoxic conditions on lipid accumulation in smooth muscle cells (SMCs) was studied in an arterial wall coculture and monocultivation model. Low density lipoprotein (LDL) was loaded under various levels of oxygen tension. Oil red O staining of rabbit and human SMCs revealed that lipid accumulation was greater under lower oxygen tension. Cholesterol esters were shown to accumulate in an oxygen tension-dependent manner by high-performance liquid chromatographic analysis. Autoradiograms using radiolabeled LDL indicated that LDL uptake was more pronounced under hypoxia. This result holds in the case of LDL receptor-deficient rabbit SMCs. However, cholesterol biosynthesis and cellular cholesterol release were unaffected by oxygen tension. Hypoxia significantly increases LDL uptake and enhances lipid accumulation in arterial SMCs, exclusive of LDL receptor activity. Although the molecular mechanism is not clear, the model is useful for studying lipid accumulation in arterial wall cells and the difficult-to-elucidate events in the initial stage of atherogenesis.

Gene expression analysis of murine cells producing amphotropic mouse leukaemia virus at a cultivation temperature of 32 and 37 degrees C.

PubMed

Beer, Christiane; Buhr, Petra; Hahn, Heidi; Laubner, Daniela; Wirth, Manfred

2003-07-01

Cultivation of retrovirus packaging cells at 32 degrees C represents a common procedure to achieve high titres in mouse retrovirus production. Gene expression profiling of mouse NIH 3T3 cells producing amphotropic mouse leukaemia virus 4070A revealed that 10 % of the 1176 cellular genes investigated were regulated by temperature shift (37/32 degrees C), while 5 % were affected by retrovirus infection. Strikingly, retrovirus production at 32 degrees C activated the cholesterol biosynthesis/transport pathway and caused an increase in plasma membrane cholesterol levels. Furthermore, these conditions resulted in transcriptional activation of smoothened (smo), patched (ptc) and gli-1; Smo, Ptc and Gli-1, as well as cholesterol, are components of the Sonic hedgehog (Shh) signalling pathway, which directs pattern formation, diversification and tumourigenesis in mammalian cells. These findings suggest a link between cultivation at 32 degrees C, production of MLV-A and the Shh signalling pathway.

C282Y-HFE Gene Variant Affects Cholesterol Metabolism in Human Neuroblastoma Cells

PubMed Central

Ali-Rahmani, Fatima; Huang, Michael A.; Schengrund, C.-L.; Connor, James R.; Lee, Sang Y.

2014-01-01

Although disruptions in the maintenance of iron and cholesterol metabolism have been implicated in several cancers, the association between variants in the HFE gene that is associated with cellular iron uptake and cholesterol metabolism has not been studied. The C282Y-HFE variant is a risk factor for different cancers, is known to affect sphingolipid metabolism, and to result in increased cellular iron uptake. The effect of this variant on cholesterol metabolism and its possible relevance to cancer phenotype was investigated using wild type (WT) and C282Y-HFE transfected human neuroblastoma SH-SY5Y cells. Expression of C282Y-HFE in SH-SY5Y cells resulted in a significant increase in total cholesterol as well as increased transcription of a number of genes involved in its metabolism compared to cells expressing WT-HFE. The marked increase in expression of NPC1L1 relative to that of most other genes, was accompanied by a significant increase in expression of NPC1, a protein that functions in cholesterol uptake by cells. Because inhibitors of cholesterol metabolism have been proposed to be beneficial for treating certain cancers, their effect on the viability of C282Y-HFE neuroblastoma cells was ascertained. C282Y-HFE cells were significantly more sensitive than WT-HFE cells to U18666A, an inhibitor of desmosterol Δ24-reductase the enzyme catalyzing the last step in cholesterol biosynthesis. This was not seen for simvastatin, ezetimibe, or a sphingosine kinase inhibitor. These studies indicate that cancers presenting in carriers of the C282Y-HFE allele might be responsive to treatment designed to selectively reduce cholesterol content in their tumor cells. PMID:24533143

C282Y-HFE gene variant affects cholesterol metabolism in human neuroblastoma cells.

PubMed

Ali-Rahmani, Fatima; Huang, Michael A; Schengrund, C-L; Connor, James R; Lee, Sang Y

2014-01-01

Although disruptions in the maintenance of iron and cholesterol metabolism have been implicated in several cancers, the association between variants in the HFE gene that is associated with cellular iron uptake and cholesterol metabolism has not been studied. The C282Y-HFE variant is a risk factor for different cancers, is known to affect sphingolipid metabolism, and to result in increased cellular iron uptake. The effect of this variant on cholesterol metabolism and its possible relevance to cancer phenotype was investigated using wild type (WT) and C282Y-HFE transfected human neuroblastoma SH-SY5Y cells. Expression of C282Y-HFE in SH-SY5Y cells resulted in a significant increase in total cholesterol as well as increased transcription of a number of genes involved in its metabolism compared to cells expressing WT-HFE. The marked increase in expression of NPC1L1 relative to that of most other genes, was accompanied by a significant increase in expression of NPC1, a protein that functions in cholesterol uptake by cells. Because inhibitors of cholesterol metabolism have been proposed to be beneficial for treating certain cancers, their effect on the viability of C282Y-HFE neuroblastoma cells was ascertained. C282Y-HFE cells were significantly more sensitive than WT-HFE cells to U18666A, an inhibitor of desmosterol Δ24-reductase the enzyme catalyzing the last step in cholesterol biosynthesis. This was not seen for simvastatin, ezetimibe, or a sphingosine kinase inhibitor. These studies indicate that cancers presenting in carriers of the C282Y-HFE allele might be responsive to treatment designed to selectively reduce cholesterol content in their tumor cells.

The Endoplasmic Reticulum Coat Protein II Transport Machinery Coordinates Cellular Lipid Secretion and Cholesterol Biosynthesis*

PubMed Central

Fryer, Lee G. D.; Jones, Bethan; Duncan, Emma J.; Hutchison, Claire E.; Ozkan, Tozen; Williams, Paul A.; Alder, Olivia; Nieuwdorp, Max; Townley, Anna K.; Mensenkamp, Arjen R.; Stephens, David J.; Dallinga-Thie, Geesje M.; Shoulders, Carol C.

2014-01-01

Triglycerides and cholesterol are essential for life in most organisms. Triglycerides serve as the principal energy storage depot and, where vascular systems exist, as a means of energy transport. Cholesterol is essential for the functional integrity of all cellular membrane systems. The endoplasmic reticulum is the site of secretory lipoprotein production and de novo cholesterol synthesis, yet little is known about how these activities are coordinated with each other or with the activity of the COPII machinery, which transports endoplasmic reticulum cargo to the Golgi. The Sar1B component of this machinery is mutated in chylomicron retention disorder, indicating that this Sar1 isoform secures delivery of dietary lipids into the circulation. However, it is not known why some patients with chylomicron retention disorder develop hepatic steatosis, despite impaired intestinal fat malabsorption, and why very severe hypocholesterolemia develops in this condition. Here, we show that Sar1B also promotes hepatic apolipoprotein (apo) B lipoprotein secretion and that this promoting activity is coordinated with the processes regulating apoB expression and the transfer of triglycerides/cholesterol moieties onto this large lipid transport protein. We also show that although Sar1A antagonizes the lipoprotein secretion-promoting activity of Sar1B, both isoforms modulate the expression of genes encoding cholesterol biosynthetic enzymes and the synthesis of cholesterol de novo. These results not only establish that Sar1B promotes the secretion of hepatic lipids but also adds regulation of cholesterol synthesis to Sar1B's repertoire of transport functions. PMID:24338480

Influence of the membrane environment on cholesterol transfer.

PubMed

Breidigan, Jeffrey Michael; Krzyzanowski, Natalie; Liu, Yangmingyue; Porcar, Lionel; Perez-Salas, Ursula

2017-12-01

Cholesterol, an essential component in biological membranes, is highly unevenly distributed within the cell, with most localized in the plasma membrane while only a small fraction is found in the endoplasmic reticulum, where it is synthesized. Cellular membranes differ in lipid composition and protein content, and these differences can exist across their leaflets too. This thermodynamic landscape that cellular membranes impose on cholesterol is expected to modulate its transport. To uncover the role the membrane environment has on cholesterol inter- and intra-membrane movement, we used time-resolved small angle neutron scattering to study the passive movement of cholesterol between and within membranes with varying degrees of saturation content. We found that cholesterol moves systematically slower as the degree of saturation in the membranes increases, from a palmitoyl oleyl phosphotidylcholine membrane, which is unsaturated, to a dipalmitoylphosphatidylcholine (DPPC) membrane, which is fully saturated. Additionally, we found that the energetic barrier to move cholesterol in these phosphatidylcholine membranes is independent of their relative lipid composition and remains constant for both flip-flop and exchange at ∼100 kJ/mol. Further, by replacing DPPC with the saturated lipid palmitoylsphingomyelin, an abundant saturated lipid of the outer leaflet of the plasma membrane, we found the rates decreased by a factor of two. This finding is in stark contrast with recent molecular dynamic simulations that predict a dramatic slow-down of seven orders of magnitude for cholesterol flipping in membranes with a similar phosphocholine and SM lipid composition. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsen, Brett N.; Bielska, Agata; Lee, Tiffany

Although the majority of free cellular cholesterol is present in the plasma membrane, cholesterol homeostasis is principally regulated through sterol-sensing proteins that reside in the cholesterol-poor endoplasmic reticulum (ER). In response to acute cholesterol loading or depletion, there is rapid equilibration between the ER and plasma membrane cholesterol pools, suggesting a biophysical model in which the availability of plasma membrane cholesterol for trafficking to internal membranes modulates ER membrane behavior. Previous studies have predominantly examined cholesterol availability in terms of binding to extramembrane acceptors, but have provided limited insight into the structural changes underlying cholesterol activation. In this study, wemore » use both molecular dynamics simulations and experimental membrane systems to examine the behavior of cholesterol in membrane bilayers. We find that cholesterol depth within the bilayer provides a reasonable structural metric for cholesterol availability and that this is correlated with cholesterol-acceptor binding. Further, the distribution of cholesterol availability in our simulations is continuous rather than divided into distinct available and unavailable pools. This data provide support for a revised cholesterol activation model in which activation is driven not by saturation of membrane-cholesterol interactions but rather by bulk membrane remodeling that reduces membrane-cholesterol affinity.« less

Accumulation of cholesterol and increased demand for zinc in serum-deprived RPE cells

PubMed Central

Mishra, Sanghamitra; Peterson, Katherine; Yin, Lili; Berger, Alan; Fan, Jianguo

2016-01-01

Purpose Having observed that confluent ARPE-19 cells (derived from human RPE) survive well in high-glucose serum-free medium (SFM) without further feeding for several days, we investigated the expression profile of RPE cells under the same conditions. Methods Expression profiles were examined with microarray and quantitative PCR (qPCR) analyses, followed by western blot analysis of key regulated proteins. The effects of low-density lipoprotein (LDL) and zinc supplementation were examined with qPCR. Immunofluorescence was used to localize the LDL receptor and to examine LDL uptake. Cellular cholesterol levels were measured with filipin binding. Expression patterns in primary fetal RPE cells were compared using qPCR. Results Microarray analyses of gene expression in ARPE-19, confirmed with qPCR, showed upregulation of lipid and cholesterol biosynthesis pathways in SFM. At the protein level, the cholesterol synthesis control factor SRBEF2 was activated, and other key lipid synthesis proteins increased. Supplementation of SFM with LDL reversed the upregulation of lipid and cholesterol synthesis genes, but not of cholesterol transport genes. The LDL receptor relocated to the plasma membrane, and LDL uptake was activated by day 5–7 in SFM, suggesting increased demand for cholesterol. Confluent ARPE-19 cells in SFM accumulated intracellular cholesterol, compared with cells supplemented with serum, over 7 days. Over the same time course in SFM, the expression of metallothioneins decreased while the major zinc transporter was upregulated, consistent with a parallel increase in demand for zinc. Supplementation with zinc reversed expression changes for metallothionein genes, but not for other zinc-related genes. Similar patterns of regulation were also seen in primary fetal human RPE cells in SFM. Conclusions ARPE-19 cells respond to serum deprivation and starvation with upregulation of the lipid and cholesterol pathways, accumulation of intracellular cholesterol, and increased demand for zinc. Similar trends are seen in primary fetal RPE cells. Cholesterol accumulation basal to RPE is a prominent feature of age-related macular degeneration (AMD), while dietary zinc is protective. It is conceivable that accumulating defects in Bruch’s membrane and dysfunction of the choriocapillaris could impede transport between RPE and vasculature in AMD. Thus, this pattern of response to serum deprivation in RPE-derived cells may have relevance for some aspects of the progression of AMD. PMID:28003730

Regulation of CD4+ T-Cell Function by Membrane Cholesterol

DTIC Science & Technology

2012-03-13

hypercholesterolemia in mice was associated with an increased number of 97 splenic CD4 T-cells [65]. In contrast, Atorvastatin -induced inhibition of HMG...Mauri C, Ehrenstein MR (2006) Atorvastatin restores Lck expression and lipid raft-associated signaling in T cells from patients with systemic lupus...J, Rehm C, et al. (2011) High dose atorvastatin decreases cellular markers of immune activation without affecting HIV-1 RNA levels: results of a

Dexamethasone inhibits activation of monocytes/macrophages in a milieu rich in 27-oxygenated cholesterol.

PubMed

Kim, Bo-Young; Son, Yonghae; Lee, Jeonga; Choi, Jeongyoon; Kim, Chi Dae; Bae, Sun Sik; Eo, Seong-Kug; Kim, Koanhoi

2017-01-01

Molecular mechanisms underlying the decreased number of macrophages and T cells in the arteries of cholesterol-fed-rabbits following dexamethasone administration are unknown. We investigated the possibility that dexamethasone could affect activation of monocytic cells induced by oxygenated derivatives of cholesterol (oxysterols) using THP-1 monocyte/macrophage cells. 27-Hydroxycholesterol (27OHChol), an oxysterol elevated with hypercholesterolemia, enhanced production of CCL2, known as MCP1, chemokine from monocytes/macrophages and migration of the monocytic cells, but the CCL2 production and the cell migration were reduced by treatment with dexamethasone. Dexamethasone inhibited superproduction of CCL2 induced by 27OHChol plus LPS and attenuated transcription of matrix metalloproteinase 9 as well as secretion of its active gene product induced by 27OHChol. The drug downregulated cellular and surface levels of CD14 and blocked release of soluble CD14 without altering transcription of the gene. Dexamethasone also inhibited expression and phosphorylation of the NF-κB p65 subunit enhanced by 27OHChol. Collectively, these results indicate that dexamethasone inhibits activation of monocytes/macrophages in response to 27OHChol, thereby leading to decreased migration of inflammatory cells in milieu rich in oxygenated derivatives of cholesterol.

Dexamethasone inhibits activation of monocytes/macrophages in a milieu rich in 27-oxygenated cholesterol

PubMed Central

Kim, Bo-Young; Son, Yonghae; Lee, Jeonga; Choi, Jeongyoon; Kim, Chi Dae; Bae, Sun Sik; Eo, Seong-Kug

2017-01-01

Molecular mechanisms underlying the decreased number of macrophages and T cells in the arteries of cholesterol-fed-rabbits following dexamethasone administration are unknown. We investigated the possibility that dexamethasone could affect activation of monocytic cells induced by oxygenated derivatives of cholesterol (oxysterols) using THP-1 monocyte/macrophage cells. 27-Hydroxycholesterol (27OHChol), an oxysterol elevated with hypercholesterolemia, enhanced production of CCL2, known as MCP1, chemokine from monocytes/macrophages and migration of the monocytic cells, but the CCL2 production and the cell migration were reduced by treatment with dexamethasone. Dexamethasone inhibited superproduction of CCL2 induced by 27OHChol plus LPS and attenuated transcription of matrix metalloproteinase 9 as well as secretion of its active gene product induced by 27OHChol. The drug downregulated cellular and surface levels of CD14 and blocked release of soluble CD14 without altering transcription of the gene. Dexamethasone also inhibited expression and phosphorylation of the NF-κB p65 subunit enhanced by 27OHChol. Collectively, these results indicate that dexamethasone inhibits activation of monocytes/macrophages in response to 27OHChol, thereby leading to decreased migration of inflammatory cells in milieu rich in oxygenated derivatives of cholesterol. PMID:29236764

Evacetrapib and Cardiovascular Outcomes in High-Risk Vascular Disease.

PubMed

Lincoff, A Michael; Nicholls, Stephen J; Riesmeyer, Jeffrey S; Barter, Philip J; Brewer, H Bryan; Fox, Keith A A; Gibson, C Michael; Granger, Christopher; Menon, Venu; Montalescot, Gilles; Rader, Daniel; Tall, Alan R; McErlean, Ellen; Wolski, Kathy; Ruotolo, Giacomo; Vangerow, Burkhard; Weerakkody, Govinda; Goodman, Shaun G; Conde, Diego; McGuire, Darren K; Nicolau, Jose C; Leiva-Pons, Jose L; Pesant, Yves; Li, Weimin; Kandath, David; Kouz, Simon; Tahirkheli, Naeem; Mason, Denise; Nissen, Steven E

2017-05-18

The cholesteryl ester transfer protein inhibitor evacetrapib substantially raises the high-density lipoprotein (HDL) cholesterol level, reduces the low-density lipoprotein (LDL) cholesterol level, and enhances cellular cholesterol efflux capacity. We sought to determine the effect of evacetrapib on major adverse cardiovascular outcomes in patients with high-risk vascular disease. In a multicenter, randomized, double-blind, placebo-controlled phase 3 trial, we enrolled 12,092 patients who had at least one of the following conditions: an acute coronary syndrome within the previous 30 to 365 days, cerebrovascular atherosclerotic disease, peripheral vascular arterial disease, or diabetes mellitus with coronary artery disease. Patients were randomly assigned to receive either evacetrapib at a dose of 130 mg or matching placebo, administered daily, in addition to standard medical therapy. The primary efficacy end point was the first occurrence of any component of the composite of death from cardiovascular causes, myocardial infarction, stroke, coronary revascularization, or hospitalization for unstable angina. At 3 months, a 31.1% decrease in the mean LDL cholesterol level was observed with evacetrapib versus a 6.0% increase with placebo, and a 133.2% increase in the mean HDL cholesterol level was seen with evacetrapib versus a 1.6% increase with placebo. After 1363 of the planned 1670 primary end-point events had occurred, the data and safety monitoring board recommended that the trial be terminated early because of a lack of efficacy. After a median of 26 months of evacetrapib or placebo, a primary end-point event occurred in 12.9% of the patients in the evacetrapib group and in 12.8% of those in the placebo group (hazard ratio, 1.01; 95% confidence interval, 0.91 to 1.11; P=0.91). Although the cholesteryl ester transfer protein inhibitor evacetrapib had favorable effects on established lipid biomarkers, treatment with evacetrapib did not result in a lower rate of cardiovascular events than placebo among patients with high-risk vascular disease. (Funded by Eli Lilly; ACCELERATE ClinicalTrials.gov number, NCT01687998 .).

Quantifying lipid changes in various membrane compartments using lipid binding protein domains.

PubMed

Várnai, Péter; Gulyás, Gergő; Tóth, Dániel J; Sohn, Mira; Sengupta, Nivedita; Balla, Tamas

2017-06-01

One of the largest challenges in cell biology is to map the lipid composition of the membranes of various organelles and define the exact location of processes that control the synthesis and distribution of lipids between cellular compartments. The critical role of phosphoinositides, low-abundant lipids with rapid metabolism and exceptional regulatory importance in the control of almost all aspects of cellular functions created the need for tools to visualize their localizations and dynamics at the single cell level. However, there is also an increasing need for methods to determine the cellular distribution of other lipids regulatory or structural, such as diacylglycerol, phosphatidic acid, or other phospholipids and cholesterol. This review will summarize recent advances in this research field focusing on the means by which changes can be described in more quantitative terms. Published by Elsevier Ltd.

Blood biochemical and cellular changes during a decompression procedure involving eight hours of oxygen prebreathing

NASA Technical Reports Server (NTRS)

Jauchem, J. R.

1989-01-01

Chemical and cellular parameters were measured in human subjects before and after exposure to a decompression schedule involving 8 h of oxygen prebreathing. The exposure was designed to simulate space-flight extravehicular activity (EVA) for 6 h. Several statistically significant changes in blood parameters were observed following the exposure: increases in calcium, magnesium, osmolality, low-density lipoprotein cholesterol, monocytes, and prothrombin time, and decreases in chloride, creatine phosphokinase and eosinophils. The changes, however, were small in magnitude and blood factor levels remained within normal clinical ranges. Thus, the decompression profile used in this study is not likely to result in blood changes that would pose a threat to astronauts during EVA.

Effects of Dietary Flavonoids on Reverse Cholesterol Transport, HDL Metabolism, and HDL Function12

PubMed Central

Millar, Courtney L; Duclos, Quinn

2017-01-01

Strong experimental evidence confirms that HDL directly alleviates atherosclerosis. HDL particles display diverse atheroprotective functions in reverse cholesterol transport (RCT), antioxidant, anti-inflammatory, and antiapoptotic processes. In certain inflammatory disease states, however, HDL particles may become dysfunctional and proatherogenic. Flavonoids show the potential to improve HDL function through their well-documented effects on cellular antioxidant status and inflammation. The aim of this review is to summarize the basic science and clinical research examining the effects of dietary flavonoids on RCT and HDL function. Based on preclinical studies that used cell culture and rodent models, it appears that many flavonoids (e.g., anthocyanidins, flavonols, and flavone subclasses) influence RCT and HDL function beyond simple HDL cholesterol concentration by regulating cellular cholesterol efflux from macrophages and hepatic paraoxonase 1 expression and activity. In clinical studies, dietary anthocyanin intake is associated with beneficial changes in serum biomarkers related to HDL function in a variety of human populations (e.g., in those who are hyperlipidemic, hypertensive, or diabetic), including increased HDL cholesterol concentration, as well as HDL antioxidant and cholesterol efflux capacities. However, clinical research on HDL functionality is lacking for some flavonoid subclasses (e.g., flavanols, flavones, flavanones, and isoflavones). Although there has been a tremendous effort to develop HDL-targeted drug therapies, more research is warranted on how the intake of foods or specific nutrients affects HDL function. PMID:28298268

Loss of the Liver X Receptors Disrupts the Balance of Hematopoietic Populations, With Detrimental Effects on Endothelial Progenitor Cells.

PubMed

Rasheed, Adil; Tsai, Ricky; Cummins, Carolyn L

2018-05-08

The liver X receptors (LXRs; α/β) are nuclear receptors known to regulate cholesterol homeostasis and the production of select hematopoietic populations. The objective of this study was to determine the importance of LXRs and a high-fat high-cholesterol diet on global hematopoiesis, with special emphasis on endothelial progenitor cells (EPCs), a vasoreparative cell type that is derived from bone marrow hematopoietic stem cells. Wild-type and LXR double-knockout ( Lxr αβ -/- ) mice were fed a Western diet (WD) to increase plasma cholesterol levels. In WD-fed Lxr αβ -/- mice, flow cytometry and complete blood cell counts revealed that hematopoietic stem cells, a myeloid progenitor, and mature circulating myeloid cells were increased; EPC numbers were significantly decreased. Hematopoietic stem cells from WD-fed Lxr αβ -/- mice showed increased cholesterol content, along with increased myeloid colony formation compared with chow-fed mice. In contrast, EPCs from WD-fed Lxr αβ -/- mice also demonstrated increased cellular cholesterol content that was associated with greater expression of the endothelial lineage markers Cd144 and Vegfr2 , suggesting accelerated differentiation of the EPCs. Treatment of human umbilical vein endothelial cells with conditioned medium collected from these EPCs increased THP-1 monocyte adhesion. Increased monocyte adhesion to conditioned medium-treated endothelial cells was recapitulated with conditioned medium from Lxr αβ -/- EPCs treated with cholesterol ex vivo, suggesting cholesterol is the main component of the WD inducing EPC dysfunction. LXRs are crucial for maintaining the balance of hematopoietic cells in a hypercholesterolemic environment and for mitigating the negative effects of cholesterol on EPC differentiation/secretome changes that promote monocyte-endothelial adhesion. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

LRP5 and plasma cholesterol levels modulate the canonical Wnt pathway in peripheral blood leukocytes.

PubMed

Borrell-Pages, Maria; Carolina Romero, July; Badimon, Lina

2015-08-01

Inflammation is triggered after invasion or injury to restore homeostasis. Although the activation of Wnt/β-catenin signaling is one of the first molecular responses to cellular damage, its role in inflammation is still unclear. It was our hypothesis that the low-density lipoprotein (LDL) receptor-related protein 5 (LRP5) and the canonical Wnt signaling pathway are modulators of inflammatory mechanisms. Wild-type (WT) and LRP5(-/-) mice were fed a hypercholesterolemic (HC) diet to trigger dislipidemia and chronic inflammation. Diets were supplemented with plant sterol esters (PSEs) to induce LDL cholesterol lowering and the reduction of inflammation. HC WT mice showed increased serum cholesterol levels that correlated with increased Lrp5 and Wnt/β-catenin gene expression while in the HC LRP5(-/-) mice Wnt/β-catenin pathway was shut down. Functionally, HC induced pro-inflammatory gene expression in LRP5(-/-) mice, suggesting an inhibitory role of the Wnt pathway in inflammation. Dietary PSE administration downregulated serum cholesterol levels in WT and LRP5(-/-) mice. Furthermore, in WT mice PSE increased anti-inflammatory genes expression and inhibited Wnt/β-catenin activation. Hepatic gene expression of Vldlr, Lrp2 and Lrp6 was increased after HC feeding in WT mice but not in LRP5(-/-) mice, suggesting a role for these receptors in the clearance of plasmatic lipoproteins. Finally, an antiatherogenic role for LRP5 was demonstrated as HC LRP5(-/-) mice developed larger aortic atherosclerotic lesions than WT mice. Our results show an anti-inflammatory, pro-survival role for LRP5 and the Wnt signaling pathway in peripheral blood leukocytes.

Phospholipid Chain Interactions with Cholesterol Drive Domain Formation in Lipid Membranes.

PubMed

Bennett, W F Drew; Shea, Joan-Emma; Tieleman, D Peter

2018-06-05

Cholesterol is a key component of eukaryotic membranes, but its role in cellular biology in general and in lipid rafts in particular remains controversial. Model membranes are used extensively to determine the phase behavior of ternary mixtures of cholesterol, a saturated lipid, and an unsaturated lipid with liquid-ordered and liquid-disordered phase coexistence. Despite many different experiments that determine lipid-phase diagrams, we lack an understanding of the molecular-level driving forces for liquid phase coexistence in bilayers with cholesterol. Here, we use atomistic molecular dynamics computer simulations to address the driving forces for phase coexistence in ternary lipid mixtures. Domain formation is directly observed in a long-timescale simulation of a mixture of 1,2-distearoyl-sn-glycero-3-phosphocholine, unsaturated 1,2-dilinoleoyl-sn-glycero-3-phosphocholine, and cholesterol. Free-energy calculations for the exchange of the saturated and unsaturated lipids between the ordered and disordered phases give insight into the mixing behavior. We show that a large energetic contribution to domain formation is favorable enthalpic interactions of the saturated lipid in the ordered phase. This favorable energy for forming an ordered, cholesterol-rich phase is opposed by a large unfavorable entropy. Martini coarse-grained simulations capture the unfavorable free energy of mixing but do not reproduce the entropic contribution because of the reduced representation of the phospholipid tails. Phospholipid tails and their degree of unsaturation are key energetic contributors to lipid phase separation. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Hypercholesterolemia Impaired Sperm Functionality in Rabbits

PubMed Central

Monclus, Maria A.; Cabrillana, Maria E.; Clementi, Marisa A.; Espínola, Leandro S.; Cid Barría, Jose L.; Vincenti, Amanda E.; Santi, Analia G.; Fornés, Miguel W.

2010-01-01

Hypercholesterolemia represents a high risk factor for frequent diseases and it has also been associated with poor semen quality that may lead to male infertility. The aim of this study was to analyze semen and sperm function in diet-induced hypercholesterolemic rabbits. Twelve adult White New Zealand male rabbits were fed ad libitum a control diet or a diet supplemented with 0.05% cholesterol. Rabbits under cholesterol-enriched diet significantly increased total cholesterol level in the serum. Semen examination revealed a significant reduction in semen volume and sperm motility in hypercholesterolemic rabbits (HCR). Sperm cell morphology was seriously affected, displaying primarily a “folded head”-head fold along the major axe-, and the presence of cytoplasmic droplet on sperm flagellum. Cholesterol was particularly increased in acrosomal region when detected by filipin probe. The rise in cholesterol concentration in sperm cells was determined quantitatively by Gas chromatographic-mass spectrometric analyses. We also found a reduction of protein tyrosine phosphorylation in sperm incubated under capacitating conditions from HCR. Interestingly, the addition of Protein Kinase A pathway activators -dibutyryl-cyclic AMP and iso-butylmethylxanthine- to the medium restored sperm capacitation. Finally, it was also reported a significant decrease in the percentage of reacted sperm in the presence of progesterone. In conclusion, our data showed that diet-induced hypercholesterolemia adversely affects semen quality and sperm motility, capacitation and acrosomal reaction in rabbits; probably due to an increase in cellular cholesterol content that alters membrane related events. PMID:20976152

6-Gingerol Regulates Hepatic Cholesterol Metabolism by Up-regulation of LDLR and Cholesterol Efflux-Related Genes in HepG2 Cells.

PubMed

Li, Xiao; Guo, Jingting; Liang, Ning; Jiang, Xinwei; Song, Yuan; Ou, Shiyi; Hu, Yunfeng; Jiao, Rui; Bai, Weibin

2018-01-01

Gingerols, the pungent ingredients in ginger, are reported to possess a cholesterol-lowering activity. However, the underlying mechanism remains unclear. The present study was to investigate how 6-gingerol (6-GN), the most abundant gingerol in fresh ginger, regulates hepatic cholesterol metabolism. HepG2 cells were incubated with various concentrations of 6-GN ranging from 50 to 200 μM for 24 h. Results showed that both cellular total cholesterol and free cholesterol decreased in a dose-dependent manner. Besides, 6-GN ranging from 100 to 200 μM increased the LDLR protein and uptake of fluorescent-labeled LDL. Moreover, the mRNA and protein expressions of cholesterol metabolism-related genes were also examined. It was found that 6-GN regulated cholesterol metabolism via up-regulation of LDLR through activation of SREBP2 as well as up-regulation of cholesterol efflux-related genes LXRα and ABCA1.

Mitofusin 2 decreases intracellular lipids in macrophages by regulating peroxisome proliferator-activated receptor-γ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chun; Ge, Beihai; He, Chao

2014-07-18

Highlights: • Mfn2 decreases cellular lipid accumulation by activating cholesterol transporters. • PPARγ is involved in the Mfn2-mediated increase of cholesterol transporter expressions. • Inactivation of ERK1/2 and p38 is involved in Mfn2-induced PPARγ expression. - Abstract: Mitofusin 2 (Mfn2) inhibits atherosclerotic plaque formation, but the underlying mechanism remains elusive. This study aims to reveal how Mfn2 functions in the atherosclerosis. Mfn2 expression was found to be significantly reduced in arterial atherosclerotic lesions of both mice and human compared with healthy counterparts. Here, we observed that Mfn2 increased cellular cholesterol transporter expression in macrophages by upregulating peroxisome proliferator-activated receptor-γ, anmore » effect achieved at least partially by inhibiting extracellular signal-regulated kinase1/2 (ERK1/2) and p38 mitogen-activated protein kinases (MAPKs) pathway. These findings provide insights into potential mechanisms of Mfn2-mediated alterations in cholesterol transporter expression, which may have significant implications for the treatment of atherosclerotic heart disease.« less

Modulation by geraniol of gene expression involved in lipid metabolism leading to a reduction of serum-cholesterol and triglyceride levels.

PubMed

Galle, Marianela; Kladniew, Boris Rodenak; Castro, María Agustina; Villegas, Sandra Montero; Lacunza, Ezequiel; Polo, Mónica; de Bravo, Margarita García; Crespo, Rosana

2015-07-15

Geraniol (G) is a natural isoprenoid present in the essential oils of several aromatic plants, with various biochemical and pharmacologic properties. Nevertheless, the mechanisms of action of G on cellular metabolism are largely unknown. We propose that G could be a potential agent for the treatment of hyperlipidemia that could contribute to the prevention of cardiovascular disease. The aim of the present study was to advance our understanding of its mechanism of action on cholesterol and TG metabolism. NIH mice received supplemented diets containing 25, 50, and 75 mmol G/kg chow. After a 3-week treatment, serum total-cholesterol and triglyceride levels were measured by commercial kits and lipid biosynthesis determined by the [(14)C] acetate incorporated into fatty acids plus nonsaponifiable and total hepatic lipids of the mice. The activity of the mRNA encoding HMGCR-the rate-limiting step in cholesterol biosynthesis-along with the enzyme levels and catalysis were assessed by real-time RT-PCR, Western blotting, and HMG-CoA-conversion assays, respectively. In-silico analysis of several genes involved in lipid metabolism and regulated by G in cultured cells was also performed. Finally, the mRNA levels encoded by the genes for the low-density-lipoprotein receptor (LDLR), the sterol-regulatory-element-binding transcription factor (SREBF2), the very-low-density-lipoprotein receptor (VLDLR), and the acetyl-CoA carboxylase (ACACA) were determined by real-time RT-PCR. Plasma total-cholesterol and triglyceride levels plus hepatic fatty-acid, total-lipid, and nonsaponifiable-lipid biosynthesis were significantly reduced by feeding with G. Even though an up-regulation of the mRNA encoding HMGCR occurred in the G treated mouse livers, the protein levels and specific activity of the enzyme were both inhibited. G also enhanced the mRNAs encoding the LDL and VLDL receptors and reduced ACACA mRNA, without altering the transcription of the mRNA encoding the SREBF2. The following mechanisms may have mediated the decrease in plasma lipids levels in mice: a down-regulation of hepatocyte-cholesterol synthesis occurred as a result of decreased HMGCR protein levels and catalytic activity; the levels of LDLR mRNA became elevated, thus suggesting an increase in the uptake of serum LDL, especially by the liver; and TG synthesis became reduced very likely because of a decrease in fatty-acid synthesis. Copyright © 2015 Elsevier GmbH. All rights reserved.

The cholesterol-dependent cytolysins pneumolysin and streptolysin O require binding to red blood cell glycans for hemolytic activity

PubMed Central

Shewell, Lucy K.; Harvey, Richard M.; Higgins, Melanie A.; Day, Christopher J.; Hartley-Tassell, Lauren E.; Chen, Austen Y.; Gillen, Christine M.; James, David B. A.; Alonzo, Francis; Torres, Victor J.; Walker, Mark J.; Paton, Adrienne W.; Paton, James C.; Jennings, Michael P.

2014-01-01

The cholesterol-dependent cytolysin (CDC) pneumolysin (Ply) is a key virulence factor of Streptococcus pneumoniae. Membrane cholesterol is required for the cytolytic activity of this toxin, but it is not clear whether cholesterol is the only cellular receptor. Analysis of Ply binding to a glycan microarray revealed that Ply has lectin activity and binds glycans, including the Lewis histo-blood group antigens. Surface plasmon resonance analysis showed that Ply has the highest affinity for the sialyl LewisX (sLeX) structure, with a Kd of 1.88 × 10−5 M. Ply hemolytic activity against human RBCs showed dose-dependent inhibition by sLeX. Flow cytometric analysis and Western blots showed that blocking binding of Ply to the sLeX glycolipid on RBCs prevents deposition of the toxin in the membrane. The lectin domain responsible for sLeX binding is in domain 4 of Ply, which contains candidate carbohydrate-binding sites. Mutagenesis of these predicted carbohydrate-binding residues of Ply resulted in a decrease in hemolytic activity and a reduced affinity for sLeX. This study reveals that this archetypal CDC requires interaction with the sLeX glycolipid cellular receptor as an essential step before membrane insertion. A similar analysis conducted on streptolysin O from Streptococcus pyogenes revealed that this CDC also has glycan-binding properties and that hemolytic activity against RBCs can be blocked with the glycan lacto-N-neotetraose by inhibiting binding to the cell surface. Together, these data support the emerging paradigm shift that pore-forming toxins, including CDCs, have cellular receptors other than cholesterol that define target cell tropism. PMID:25422425

The cholesterol-dependent cytolysins pneumolysin and streptolysin O require binding to red blood cell glycans for hemolytic activity.

PubMed

Shewell, Lucy K; Harvey, Richard M; Higgins, Melanie A; Day, Christopher J; Hartley-Tassell, Lauren E; Chen, Austen Y; Gillen, Christine M; James, David B A; Alonzo, Francis; Torres, Victor J; Walker, Mark J; Paton, Adrienne W; Paton, James C; Jennings, Michael P

2014-12-09

The cholesterol-dependent cytolysin (CDC) pneumolysin (Ply) is a key virulence factor of Streptococcus pneumoniae. Membrane cholesterol is required for the cytolytic activity of this toxin, but it is not clear whether cholesterol is the only cellular receptor. Analysis of Ply binding to a glycan microarray revealed that Ply has lectin activity and binds glycans, including the Lewis histo-blood group antigens. Surface plasmon resonance analysis showed that Ply has the highest affinity for the sialyl LewisX (sLeX) structure, with a K(d) of 1.88 × 10(-5) M. Ply hemolytic activity against human RBCs showed dose-dependent inhibition by sLeX. Flow cytometric analysis and Western blots showed that blocking binding of Ply to the sLeX glycolipid on RBCs prevents deposition of the toxin in the membrane. The lectin domain responsible for sLeX binding is in domain 4 of Ply, which contains candidate carbohydrate-binding sites. Mutagenesis of these predicted carbohydrate-binding residues of Ply resulted in a decrease in hemolytic activity and a reduced affinity for sLeX. This study reveals that this archetypal CDC requires interaction with the sLeX glycolipid cellular receptor as an essential step before membrane insertion. A similar analysis conducted on streptolysin O from Streptococcus pyogenes revealed that this CDC also has glycan-binding properties and that hemolytic activity against RBCs can be blocked with the glycan lacto-N-neotetraose by inhibiting binding to the cell surface. Together, these data support the emerging paradigm shift that pore-forming toxins, including CDCs, have cellular receptors other than cholesterol that define target cell tropism.

Early Cellular Changes in the Ascending Aorta and Myocardium in a Swine Model of Metabolic Syndrome.

PubMed

Saraf, Rabya; Huang, Thomas; Mahmood, Feroze; Owais, Khurram; Bardia, Amit; Khabbaz, Kamal R; Liu, David; Senthilnathan, Venkatachalam; Lassaletta, Antonio D; Sellke, Frank; Matyal, Robina

2016-01-01

Metabolic syndrome is associated with pathological remodeling of the heart and adjacent vessels. The early biochemical and cellular changes underlying the vascular damage are not fully understood. In this study, we sought to establish the nature, extent, and initial timeline of cytochemical derangements underlying reduced ventriculo-arterial compliance in a swine model of metabolic syndrome. Yorkshire swine (n = 8 per group) were fed a normal diet (ND) or a high-cholesterol (HCD) for 12 weeks. Myocardial function and blood flow was assessed before harvesting the heart. Immuno-blotting and immuno-histochemical staining were used to assess the cellular changes in the myocardium, ascending aorta and left anterior descending artery (LAD). There was significant increase in body mass index, blood glucose and mean arterial pressures (p = 0.002, p = 0.001 and p = 0.024 respectively) in HCD group. At the cellular level there was significant increase in anti-apoptotic factors p-Akt (p = 0.007 and p = 0.002) and Bcl-xL (p = 0.05 and p = 0.01) in the HCD aorta and myocardium, respectively. Pro-fibrotic markers TGF-β (p = 0.01), pSmad1/5 (p = 0.03) and MMP-9 (p = 0.005) were significantly increased in the HCD aorta. The levels of pro-apoptotic p38MAPK, Apaf-1 and cleaved Caspase3 were significantly increased in aorta of HCD (p = 0.03, p = 0.04 and p = 0.007 respectively). Similar changes in coronary arteries were not observed in either group. Functionally, the high cholesterol diet resulted in significant increase in ventricular end systolic pressure and-dp/dt (p = 0.05 and p = 0.007 respectively) in the HCD group. Preclinical metabolic syndrome initiates pro-apoptosis and pro-fibrosis pathways in the heart and ascending aorta, while sparing coronary arteries at this early stage of dietary modification.

Chronic kidney disease alters lipid trafficking and inflammatory responses in macrophages: effects of liver X receptor agonism.

PubMed

Kaseda, Ryohei; Tsuchida, Yohei; Yang, Hai-Chun; Yancey, Patricia G; Zhong, Jianyong; Tao, Huan; Bian, Aihua; Fogo, Agnes B; Linton, Mac Rae F; Fazio, Sergio; Ikizler, Talat Alp; Kon, Valentina

2018-01-27

Our aim was to evaluate lipid trafficking and inflammatory response of macrophages exposed to lipoproteins from subjects with moderate to severe chronic kidney disease (CKD), and to investigate the potential benefits of activating cellular cholesterol transporters via liver X receptor (LXR) agonism. LDL and HDL were isolated by sequential density gradient ultracentrifugation of plasma from patients with stage 3-4 CKD and individuals without kidney disease (HDL CKD and HDL Cont , respectively). Uptake of LDL, cholesterol efflux to HDL, and cellular inflammatory responses were assessed in human THP-1 cells. HDL effects on inflammatory markers (MCP-1, TNF-α, IL-1β), Toll-like receptors-2 (TLR-2) and - 4 (TLR-4), ATP-binding cassette class A transporter (ABCA1), NF-κB, extracellular signal regulated protein kinases 1/2 (ERK1/2) were assessed by RT-PCR and western blot before and after in vitro treatment with an LXR agonist. There was no difference in macrophage uptake of LDL isolated from CKD versus controls. By contrast, HD CKD was significantly less effective than HDL Cont in accepting cholesterol from cholesterol-enriched macrophages (median 20.8% [IQR 16.1-23.7] vs control (26.5% [IQR 19.6-28.5]; p = 0.008). LXR agonist upregulated ABCA1 expression and increased cholesterol efflux to HDL of both normal and CKD subjects, although the latter continued to show lower efflux capacity. HDL CKD increased macrophage cytokine response (TNF-α, MCP-1, IL-1β, and NF-κB) versus HDL Cont . The heightened cytokine response to HDL CKD was further amplified in cells treated with LXR agonist. The LXR-augmentation of inflammation was associated with increased TLR-2 and TLR-4 and ERK1/2. Moderate to severe impairment in kidney function promotes foam cell formation that reflects impairment in cholesterol acceptor function of HDL CKD . Activation of cellular cholesterol transporters by LXR agonism improves but does not normalize efflux to HDL CKD . However, LXR agonism actually increases the pro-inflammatory effects of HDL CKD through activation of TLRs and ERK1/2 pathways.

NRF1 Is an ER Membrane Sensor that Is Central to Cholesterol Homeostasis.

PubMed

Widenmaier, Scott B; Snyder, Nicole A; Nguyen, Truc B; Arduini, Alessandro; Lee, Grace Y; Arruda, Ana Paula; Saksi, Jani; Bartelt, Alexander; Hotamisligil, Gökhan S

2017-11-16

Cholesterol is a critical nutrient requiring tight constraint in the endoplasmic reticulum (ER) due to its uniquely challenging biophysical properties. While the mechanisms by which the ER defends against cholesterol insufficiency are well described, it remains unclear how the ER senses and effectively defends against cholesterol excess. Here, we identify the ER-bound transcription factor nuclear factor erythroid 2 related factor-1, Nrf1/Nfe2L1, as a critical mediator of this process. We show that Nrf1 directly binds to and specifically senses cholesterol in the ER through a defined domain and that cholesterol regulates Nrf1 turnover, processing, localization, and activity. In Nrf1 deficiency, in vivo cholesterol challenges induce massive hepatic cholesterol accumulation and damage, which is rescued by replacing Nrf1 exogenously. This Nrf1-mediated mechanism involves the suppression of CD36-driven inflammatory signaling and derepression of liver X receptor activity. These findings reveal Nrf1 as a guardian of cholesterol homeostasis and a core component of adaptive responses to excess cellular cholesterol. Copyright © 2017. Published by Elsevier Inc.

Mevalonate Biosynthesis Intermediates Are Key Regulators of Innate Immunity in Bovine Endometritis

PubMed Central

Collier, Christine; Griffin, Sholeem; Schuberth, Hans-Joachim; Sandra, Olivier; Smith, David G.; Mahan, Suman; Dieuzy-Labaye, Isabelle; Sheldon, I. Martin

2016-01-01

Metabolic changes can influence inflammatory responses to bacteria. To examine whether localized manipulation of the mevalonate pathway impacts innate immunity, we exploited a unique mucosal disease model, endometritis, where inflammation is a consequence of innate immunity. IL responses to pathogenic bacteria and LPS were modulated in bovine endometrial cell and organ cultures by small molecules that target the mevalonate pathway. Treatment with multiple statins, bisphosphonates, squalene synthase inhibitors, and small interfering RNA showed that inhibition of farnesyl-diphosphate farnesyl transferase (squalene synthase), but not 3-hydroxy-3-methylglutaryl-CoA reductase or farnesyl diphosphate synthase, reduced endometrial organ and cellular inflammatory responses to pathogenic bacteria and LPS. Although manipulation of the mevalonate pathway reduced cellular cholesterol, impacts on inflammation were independent of cholesterol concentration as cholesterol depletion using cyclodextrins did not alter inflammatory responses. Treatment with the isoprenoid mevalonate pathway-intermediates, farnesyl diphosphate and geranylgeranyl diphosphate, also reduced endometrial cellular inflammatory responses to LPS. These data imply that manipulating the mevalonate pathway regulates innate immunity within the endometrium, and that isoprenoids are regulatory molecules in this process, knowledge that could be exploited for novel therapeutic strategies. PMID:26673142

Cholesterol is required for stability and infectivity of influenza A and respiratory syncytial viruses.

PubMed

Bajimaya, Shringkhala; Frankl, Tünde; Hayashi, Tsuyoshi; Takimoto, Toru

2017-10-01

Cholesterol-rich lipid raft microdomains in the plasma membrane are considered to play a major role in the enveloped virus lifecycle. However, the functional role of cholesterol in assembly, infectivity and stability of respiratory RNA viruses is not fully understood. We previously reported that depletion of cellular cholesterol by cholesterol-reducing agents decreased production of human parainfluenza virus type 1 (hPIV1) particles by inhibiting virus assembly. In this study, we analyzed the role of cholesterol on influenza A virus (IAV) and respiratory syncytial virus (RSV) production. Unlike hPIV1, treatment of human airway cells with the agents did not decrease virus particle production. However, the released virions were less homogeneous in density and unstable. Addition of exogenous cholesterol to the released virions restored virus stability and infectivity. Collectively, these data indicate a critical role of cholesterol in maintaining IAV and RSV membrane structure that is essential for sustaining viral stability and infectivity. Copyright © 2017 Elsevier Inc. All rights reserved.

Regulatory mechanism of mineral-balanced deep sea water on hypocholesterolemic effects in HepG2 hepatic cells.

PubMed

Lee, Kyu-Shik; Kwon, Yun-Suk; Kim, Soyoung; Moon, Deok-Soo; Kim, Hyeon Ju; Nam, Kyung-Soo

2017-02-01

Several previous studies have shown the benefits of deep sea water (DSW) in lipid metabolism. However, the effects of DSW on cellular cholesterol accumulation and synthesis induced by high glucose or free fatty acid plus high glucose [4.5g/L] (FFA/glucose) have not been fully elucidated to date. Herein, we showed the effects of mineral-balanced DSW [magnesium (Mg):calcium (Ca)=3:1] (MB-DSW) on cholesterol metabolism induced by high glucose or FFA/glucose in HepG2 hepatic cells. Moreover, the effects of high ratio Mg DSW [Mg:Ca=40:1] (Mg40) were also investigated. MB-DSW and Mg40 prevented the increase of cellular total cholesterol content in high glucose- or FFA/glucose-treated HepG2 hepatic cells. Furthermore, the inhibition by MB-DSW was closely related to the down-regulation of 3-hydroxy-3-methylglutatryl-CoA reductase (HMGCR) expression and an increase in the AMP-activated protein kinase (AMPK) phosphorylation, leading to decreased cholesterol synthesis in both high glucose- and FFA/glucose-treated conditions. However, this effect was not seen in case of Mg40. In addition, both MB-DSW and Mg40 induced the low-density lipoprotein receptor (LDLR) and diminished the proprotein convertase subtilisin/kexin type 9 (PCSK9) transcriptions in high glucose-treated HepG2 hepatic cells. This result demonstrates that the hypocholesterolemic effects of MB-DSW and Mg40 are mediated with LDL-c clearance through increases of LDLR and its transcription factors, such as peroxisome proliferator-activated receptor-α (PPAR-α), sterol regulatory element-binding protein (SREBP)-1a, and SREBP-2, mRNA synthesis and suppression of PCSK9 transcription. Moreover, apolipoprotein (Apo) A1 transcription was enhanced by MB-DSW and Mg40 without decreasing the expression of Apo B in high glucose-treated HepG2 hepatic cells. However, ApoA1 protein expression was not changed. Taken together, the present investigation suggests that DSW may prevent the high glucose- or FFA/glucose-induced increase of cellular cholesterol levels by inducing LDLR and ApoA1 transcriptions and inhibiting PCSK9 mRNA expression in HepG2 hepatic cells. Additionally, the ratio of Mg in DSW is an important factor that determines whether HMGCR expression and/or AMPK phosphorylation participate in the hypocholesterolemic effects of DSW. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Ganoderic Acid A improves high fat diet-induced obesity, lipid accumulation and insulin sensitivity through regulating SREBP pathway.

PubMed

Zhu, Jing; Jin, Jie; Ding, Jiexia; Li, Siying; Cen, Panpan; Wang, Keyi; Wang, Hai; Xia, Junbo

2018-06-25

Obesity and its major co-morbidity, type 2 diabetes, have been an alarming epidemic prevalence without an effective treatment available. Sterol regulatory element-binding proteins (SREBPs) are major transcription factors regulating the expression of genes involved in biosynthesis of cholesterol, fatty acid and triglyceride. Therefore, inhibition of SREBP pathway may be a useful strategy to treat obesity with type 2 diabetes. Here, we identify a small molecule, Ganoderic Acid A (GAA), inhibits the SREBP expression and decreases the cellular levels of cholesterol and fatty acid in vitro. GAA also ameliorates body weight gain and fat accumulation in liver or adipose tissues, and improves serum lipid levels and insulin sensitivity in high fat diet (HFD)-induced obese mice. Consistently, GAA regulates SREBPs target genes and metabolism associated genes in liver or adipose tissues, which may directly contribute to the lower lipid level and improvement of insulin resistance. Taken together, GAA could be a potential leading compound for development of drugs for the prevention of obesity and insulin resistance. Copyright © 2018. Published by Elsevier B.V.

Apolipoprotein A-1 (apoA-1) deposition in, and release from, the enterocyte brush border: a possible role in transintestinal cholesterol efflux (TICE)?

PubMed

Danielsen, E Michael; Hansen, Gert H; Rasmussen, Karina; Niels-Christiansen, Lise-Lotte; Frenzel, Franz

2012-03-01

Transintestinal cholesterol efflux (TICE) has been proposed to represent a non-hepatobiliary route of cholesterol secretion directly "from blood to gut" and to play a physiologically significant role in excretion of neutral sterols, but so far little is known about the proteins involved in the process. We have previously observed that apolipoprotein A-1 (apoA-1) synthesized by enterocytes of the small intestine is mainly secreted apically into the gut lumen during fasting where its assembly into chylomicrons and basolateral discharge is at a minimal level. In the present work we showed, both by immunomicroscopy and subcellular fractionation, that a fraction of the apically secreted apoA-1 in porcine small intestine was not released from the cell surface but instead deposited in the brush border. Cholesterol was detected in immunoisolated microvillar apoA-1, and it was partially associated with detergent resistant membranes (DRMs), indicative of localization in lipid raft microdomains. The apolipoprotein was not readily released from microvillar vesicles by high salt or by incubation with phosphatidylcholine-specific phospholipase C or trypsin, indicating a relatively firm attachment to the membrane bilayer. However, whole bile or taurocholate efficiently released apoA-1 at low concentrations that did not solubilize the transmembrane microvillar protein aminopeptidase N. Based on these findings and the well known role played by apoA-1 in extrahepatic cellular cholesterol removal and reverse cholesterol transport (RCT), we propose that brush border-deposited apoA-1 in the small intestine acts in TICE by mediating cholesterol efflux into the gut lumen. Copyright © 2011 Elsevier B.V. All rights reserved.

Camphene, a Plant-Derived Monoterpene, Reduces Plasma Cholesterol and Triglycerides in Hyperlipidemic Rats Independently of HMG-CoA Reductase Activity

PubMed Central

Vallianou, Ioanna; Peroulis, Nikolaos; Pantazis, Panayotis; Hadzopoulou-Cladaras, Margarita

2011-01-01

Background Central to the pathology of coronary heart disease is the accumulation of lipids, cholesterol and triglycerides, within the intima of arterial blood vessels. The search for drugs to treat dislipidemia, remains a major pharmaceutical focus. In this study, we evaluated the hypolipidemic properties of the essential oil from Chios mastic gum (MGO). Methodology/Principal Findings The hypolipidemic effect of MGO was investigated in naïve as well as in rats susceptible to detergent-induced hyperlipidemia. Serum cholesterol and triglycerides were determined using commercial kits. HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase activity was measured in HepG2 cell extracts using a radioactive assay; cellular cholesterol and cholesterol esters were assessed using gas chromatography. MGO administration into naïve rats resulted in a dose-dependent reduction in the constitutive synthesis of serum cholesterol and triglycerides. In hyperlipidemic rats, MGO treatment had also a strong hypolipidemic effect. By testing various components of MGO, we show for the first time that the hypolipidemic action is associated with camphene. Administration of camphene at a dose of 30 µg/gr of body weight in hyperlipidemic rats resulted in a 54.5% reduction of total cholesterol (p<0.001), 54% of Low Density Lipoprotein (LDL)-cholesterol (p<0.001) and 34.5% of triglycerides (p<0.001). Treatment of HepG2 cells with camphene led to a decrease in cellular cholesterol content to the same extend as mevinolin, a known HMG-CoA reductase inhibitor. The hypolipidemic action of camphene is independent of HMG-CoA reductase activity, suggesting that its hypocholesterolemic and hypotriglyceridemic effects are associated with a mechanism of action different than that of statins. Conclusions Given the critical role that the control of hyperlipidemia plays in cardiovascular disease, the results of our study provide insights into the use of camphene as an alternative lipid lowering agent and merits further evaluation. PMID:22073134

Effect of tamoxifen on cholesterol synthesis in HepG2 cells and cultured rat hepatocytes.

PubMed

Holleran, A L; Lindenthal, B; Aldaghlas, T A; Kelleher, J K

1998-12-01

The objective of this study was to investigate the mechanisms by which tamoxifen modifies cholesterol metabolism in cellular models of liver metabolism, HepG2 cells and rat hepatocytes. The effect of tamoxifen on cholesterol and triglyceride-palmitate synthesis was measured using isotopomer spectral analysis (ISA) and gas chromatography-mass spectrometry (GC-MS) and compared with the effects of progesterone, estradiol, the antiestrogen ICI 182,780, and an oxysterol, 25-hydroxycholesterol (25OHC). Cholesterol synthesis in cells incubated in the presence of either [1-(13)C]acetate, [U-13C]glucose, or [4,5-(13)C]mevalonate for 48 hours was reduced in the presence of 10 micromol/L tamoxifen and 12.4 micromol/L 25OHC in both HepG2 cells and rat hepatocytes. The ISA methodology allowed a clear distinction between effects on synthesis and effects on precursor enrichment, and indicated that these compounds did not affect enrichment of the precursors of squalene. Progesterone was effective in both cell types at 30 micromol/L and only in HepG2 cells at 10 micromol/L. Estradiol and ICI 182,780 at 10 micromol/L did not inhibit cholesterol synthesis. None of the compounds altered the synthesis of triglyceride-palmitate in either cell type. Treatment of cells with tamoxifen produced accumulation of three sterol precursors of cholesterol, zymosterol, desmosterol, and delta8 cholesterol. This pattern of precursors indicates inhibition of delta24,25 reduction in addition to the previously described inhibition of delta8 isomerase. We conclude that tamoxifen is an effective inhibitor of the conversion of lanosterol to cholesterol in cellular models at concentrations comparable to those present in the plasma of tamoxifen-treated individuals. Our findings indicate that this mechanism may contribute to the effect of tamoxifen in reducing plasma cholesterol in humans.

Caveolin, sterol carrier protein-2, membrane cholesterol-rich microdomains and intracellular cholesterol trafficking.

PubMed

Schroeder, Friedhelm; Huang, Huan; McIntosh, Avery L; Atshaves, Barbara P; Martin, Gregory G; Kier, Ann B

2010-01-01

While the existence of membrane lateral microdomains has been known for over 30 years, interest in these structures accelerated in the past decade due to the discovery that cholesterol-rich microdomains serve important biological functions. It is increasingly appreciated that cholesterol-rich microdomains in the plasma membranes of eukaryotic cells represent an organizing nexus for multiple cellular proteins involved in transmembrane nutrient uptake (cholesterol, fatty acid, glucose, etc.), cell-signaling, immune recognition, pathogen entry, and many other roles. Despite these advances, however, relatively little is known regarding the organization of cholesterol itself in these plasma membrane microdomains. Although a variety of non-sterol markers indicate the presence of microdomains in the plasma membranes of living cells, none of these studies have demonstrated that cholesterol is enriched in these microdomains in living cells. Further, the role of cholesterol-rich membrane microdomains as targets for intracellular cholesterol trafficking proteins such as sterol carrier protein-2 (SCP-2) that facilitate cholesterol uptake and transcellular transport for targeting storage (cholesterol esters) or efflux is only beginning to be understood. Herein, we summarize the background as well as recent progress in this field that has advanced our understanding of these issues.

A mechanism by which dietary trans fats cause atherosclerosis.

PubMed

Chen, Chun-Lin; Tetri, Laura H; Neuschwander-Tetri, Brent A; Huang, Shuan Shian; Huang, Jung San

2011-07-01

Dietary trans fats (TFs) have been causally linked to atherosclerosis, but the mechanism by which they cause the disease remains elusive. Suppressed transforming growth factor (TGF)-β responsiveness in aortic endothelium has been shown to play an important role in the pathogenesis of atherosclerosis in animals with hypercholesterolemia. We investigated the effects of a high TF diet on TGF-β responsiveness in aortic endothelium and integration of cholesterol in tissues. Here, we show that normal mice fed a high TF diet for 24 weeks exhibit atherosclerotic lesions and suppressed TGF-β responsiveness in aortic endothelium. The suppressed TGF-β responsiveness is evidenced by markedly reduced expression of TGF-β type I and II receptors and profoundly decreased levels of phosphorylated Smad2, an important TGF-β response indicator, in aortic endothelium. These mice exhibit greatly increased integration of cholesterol into tissue plasma membranes. These results suggest that dietary TFs cause atherosclerosis, at least in part, by suppressing TGF-β responsiveness. This effect is presumably mediated by the increased deposition of cholesterol into cellular plasma membranes in vascular tissue, as in hypercholesterolemia. Copyright © 2011 Elsevier Inc. All rights reserved.

Hsp27 promotes ABCA1 expression and cholesterol efflux through the PI3K/PKCζ/Sp1 pathway in THP-1 macrophages.

PubMed

Kuang, Hai-Jun; Zhao, Guo-Jun; Chen, Wu-Jun; Zhang, Min; Zeng, Gao-Feng; Zheng, Xi-Long; Tang, Chao-Ke

2017-09-05

Heat shock protein 27 (Hsp27) is a putative biomarker and therapeutic target in atherosclerosis. This study was to explore the potential mechanisms underlying Hsp27 effects on ATP-binding cassette transporter A1 (ABCA1) expression and cellular cholesterol efflux. THP-1 macrophage-derived foam cells were infected with adenovirus to express wild-type Hsp27, hyper-phosphorylated Hsp27 mimic (3D Hsp27), antisense Hsp27 or hypo-phosphorylated Hsp27 mimic (3A Hsp27). Wild-type and 3D Hsp27 were found to up-regulate ABCA1 mRNA and protein expression and increase cholesterol efflux from cells. Expression of antisense or 3A Hsp27 suppressed the expression of ABCA1 and cholesterol efflux. Furthermore, over-expression of wild-type and 3D Hsp27 significantly increased the levels of phosphorylated specificity protein 1 (Sp1), protein kinase C ζ (PKCζ) and phosphatidylinositol 3-kinase (PI3K). In addition, the up-regulation of ABCA1 expression and cholesterol efflux induced by 3D Hsp27 was suppressed by inhibition of Sp1, PKCζ and PI3K with specific kinase inhibitors. Taken together, our results revealed that Hsp27 may up-regulate the expression of ABCA1 and promotes cholesterol efflux through activation of the PI3K/PKCζ/Sp1 signal pathway in THP-1 macrophage-derived foam cells. Our findings may partly explain the mechanisms underlying the anti-atherogenic effect of Hsp27. Copyright © 2017 Elsevier B.V. All rights reserved.

Leucine supplementation attenuates macrophage foam-cell formation: Studies in humans, mice, and cultured macrophages.

PubMed

Grajeda-Iglesias, Claudia; Rom, Oren; Hamoud, Shadi; Volkova, Nina; Hayek, Tony; Abu-Saleh, Niroz; Aviram, Michael

2018-02-05

Whereas atherogenicity of dietary lipids has been largely studied, relatively little is known about the possible contribution of dietary amino acids to macrophage foam-cell formation, a hallmark of early atherogenesis. Recently, we showed that leucine has antiatherogenic properties in the macrophage model system. In this study, an in-depth investigation of the role of leucine in macrophage lipid metabolism was conducted by supplementing humans, mice, or cultured macrophages with leucine. Macrophage incubation with serum obtained from healthy adults supplemented with leucine (5 g/d, 3 weeks) significantly decreased cellular cholesterol mass by inhibiting the rate of cholesterol biosynthesis and increasing cholesterol efflux from macrophages. Similarly, leucine supplementation to C57BL/6 mice (8 weeks) resulted in decreased cholesterol content in their harvested peritoneal macrophages (MPM) in relation with reduced cholesterol biosynthesis rate. Studies in J774A.1 murine macrophages revealed that leucine dose-dependently decreased cellular cholesterol and triglyceride mass. Macrophages treated with leucine (0.2 mM) showed attenuated uptake of very low-density lipoproteins and triglyceride biosynthesis rate, with a concurrent down-regulation of diacylglycerol acyltransferase-1, a key enzyme catalyzing triglyceride biosynthesis in macrophages. Similar effects were observed when macrophages were treated with α-ketoisocaproate, a key leucine metabolite. Finally, both in vivo and in vitro leucine supplementation significantly improved macrophage mitochondrial respiration and ATP production. The above studies, conducted in human, mice, and cultured macrophages, highlight a protective role for leucine attenuating macrophage foam-cell formation by mechanisms related to the metabolism of cholesterol, triglycerides, and energy production. © 2018 BioFactors, 2018. © 2018 International Union of Biochemistry and Molecular Biology.

Association between blood cholesterol level with periodontal status of coronary heart disease patients

NASA Astrophysics Data System (ADS)

Valensia, Rosy; Masulili, Sri Lelyati C.; Lessang, Robert; Radi, Basuni

2017-02-01

Coronary heart disease (CHD) is an abnormal narrowing of heart arteries associated with local accumulation of lipids, in the form of cholesterol and triglycerides. Periodontal disease is a chronic inflammatory that suggests link to the development of CHD. In periodontitis have been reported changes in lipid profile, include increased of cholesterol levels of blood. Objective: to analyse correlation between blood cholesterol level with periodontal status of CHD and non CHD subjects. Methods: Periodontal status and blood cholesterol level of 60 CHD and 40 non CHD subjects was measured. Result: Blood cholesterol level in CHD subjects differs from non CHD subjects (p=0.032). Blood cholesterol level correlates with pocket depth (p=0.003) and clinical attachment loss (CAL) (p=0.000) in CHD subjects. Blood cholesterol level correlates with pocket depth (p=0.010) in non CHD subjects. There is no significant correlation between blood cholesterol level and bleeding on probing (BOP) in CHD subjects. There is no significant correlation between blood cholesterol level with BOP and CAL in non CHD subjects. Conclusion: Blood cholesterol level in control group is higher than CHD patients. Blood cholesterol level positively associated with pocket depth (r=0.375) and CAL (r=0.450) in CHD patients. Blood cholesterol level is positively associated with pocket depth (r=0.404) in control group.

Estimation and correlation of stress and cholesterol levels in college teachers and housewives of Hyderabad-Pakistan.

PubMed

Wattoo, Feroza Hamid; Memon, Muhammad Saleh; Memon, Allah Nawaz; Wattoo, Muhammad Hamid Sarwar; Tirmizi, Syed Ahmed; Iqbal, Javed

2008-01-01

To evaluate environmental, psychological and physiological stresses in college teachers and housewives, and to correlate with their serum total cholesterol, HDL cholesterol, and LDL cholesterol, and triglyceride levels. This cohort study was performed at the Institute of Biochemistry, University of Sindh, Jamshoro, Pakistan during 2003-2005. Eighty females from middle socioeconomic groups, college teachers (40) and housewives (40) aged between 25-45 years participated in this study and subjects were selected from Hyderabad and its adjoining areas. Environmental, psychological and physiological stress levels were measured with Likert scale. Total cholesterol, LDL cholesterol and HDL cholesterol were measured by CHOD-PAP method and triglyceride levels were measured by GPO method. Housewives had high levels of total cholesterol, LDL cholesterol and triglyceride but low levels of HDL cholesterol were found in college teachers. Environmental, psychological and physiological stresses were significantly higher in housewives as compared to college teachers. Housewives were under more stress than college teachers. High levels of total cholesterol, LDL cholesterol and triglyceride but low levels of HDL cholesterol were found in housewives compared to college teachers.

Methotrexate in Atherogenesis and Cholesterol Metabolism

PubMed Central

Coomes, Eric; Chan, Edwin S. L.; Reiss, Allison B.

2011-01-01

Methotrexate is a disease-modifying antirheumatic drug commonly used to treat inflammatory conditions such as rheumatoid arthritis which itself is linked to increased cardiovascular risk. Treatments that target inflammation may also impact the cardiovascular system. While methotrexate improves cardiovascular risk, inhibition of the cyclooxygenase (COX)-2 enzyme promotes atherosclerosis. These opposing cardiovascular influences may arise from differing effects on the expression of proteins involved in cholesterol homeostasis. These proteins, ATP-binding cassette transporter (ABC) A1 and cholesterol 27-hydroxylase, facilitate cellular cholesterol efflux and defend against cholesterol overload. Methotrexate upregulates expression of cholesterol 27-hydroxylase and ABCA1 via adenosine release, while COX-2 inhibition downregulates these proteins. Adenosine, acting through the A2A and A3 receptors, may upregulate proteins involved in reverse cholesterol transport by cAMP-PKA-CREB activation and STAT inhibition, respectively. Elucidating underlying cardiovascular mechanisms of these drugs provides a framework for developing novel cardioprotective anti-inflammatory medications, such as selective A2A receptor agonists. PMID:21490773

A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

PubMed Central

Robinet, Peggy; Wang, Zeneng; Hazen, Stanley L.; Smith, Jonathan D.

2010-01-01

A precise and sensitive method for measuring cellular free and esterified cholesterol is required in order to perform studies of macrophage cholesterol loading, metabolism, storage, and efflux. Until now, the use of an enzymatic cholesterol assay, commonly used for aqueous phase plasma cholesterol assays, has not been optimized for use with solid phase samples such as cells, due to inefficient solubilization of total cholesterol in enzyme compatible solvents. We present an efficient solubilization protocol compatible with an enzymatic cholesterol assay that does not require chemical saponification or chromatographic separation. Another issue with enzyme compatible solvents is the presence of endogenous peroxides that interfere with the enzymatic cholesterol assay. We overcame this obstacle by pretreatment of the reaction solution with the enzyme catalase, which consumed endogenous peroxides resulting in reduced background and increased sensitivity in our method. Finally, we demonstrated that this method for cholesterol quantification in macrophages yields results that are comparable to those measured by stable isotope dilution gas chromatography with mass spectrometry detection. In conclusion, we describe a sensitive, simple, and high-throughput enzymatic method to quantify cholesterol in complex matrices such as cells. PMID:20688754

Haploid Genetic Screen Reveals a Profound and Direct Dependence on Cholesterol for Hantavirus Membrane Fusion

PubMed Central

Kleinfelter, Lara M.; Jangra, Rohit K.; Jae, Lucas T.; Herbert, Andrew S.; Mittler, Eva; Stiles, Katie M.; Wirchnianski, Ariel S.; Kielian, Margaret; Brummelkamp, Thijn R.

2015-01-01

ABSTRACT Hantaviruses cause hemorrhagic fever with renal syndrome (HFRS) in the Old World and a highly fatal hantavirus cardiopulmonary syndrome (HCPS) in the New World. No vaccines or antiviral therapies are currently available to prevent or treat hantavirus disease, and gaps in our understanding of how hantaviruses enter cells challenge the search for therapeutics. We performed a haploid genetic screen in human cells to identify host factors required for entry by Andes virus, a highly virulent New World hantavirus. We found that multiple genes involved in cholesterol sensing, regulation, and biosynthesis, including key components of the sterol response element-binding protein (SREBP) pathway, are critical for Andes virus entry. Genetic or pharmacological disruption of the membrane-bound transcription factor peptidase/site-1 protease (MBTPS1/S1P), an SREBP control element, dramatically reduced infection by virulent hantaviruses of both the Old World and New World clades but not by rhabdoviruses or alphaviruses, indicating that this pathway is broadly, but selectively, required by hantaviruses. These results could be fully explained as arising from the modest depletion of cellular membrane cholesterol that accompanied S1P disruption. Mechanistic studies of cells and with protein-free liposomes suggested that high levels of cholesterol are specifically needed for hantavirus membrane fusion. Taken together, our results indicate that the profound dependence on target membrane cholesterol is a fundamental, and unusual, biophysical property of hantavirus glycoprotein-membrane interactions during entry. PMID:26126854

Regulation of raft-dependent endocytosis

PubMed Central

Lajoie, P; Nabi, IR

2007-01-01

Abstract Raft-dependent endocytosis is in large part defined as the cholesterol-sensitive, clathrin-independent internalization of ligands and receptors from the plasma membrane. It encompasses the endocytosis of caveo-lae, smooth plasmalemmal vesicles that form a subdomain of cholesterol and sphingolipid-rich lipid rafts and that are enriched for caveolin-1. While sharing common mechanisms, like cholesterol sensitivity, raft endocytic routes show differential regulation by various cellular components including caveolin-1, dynamin-2 and regulators of the actin cytoskeleton. Dynamin-dependent raft pathways, mediated by caveolae and morphologically equivalent non-caveolin vesicular intermediates, are referred to as caveolae/raft-dependent endocytosis. In contrast, dynamin-independent raft pathways are mediated by non-caveolar intermediates. Raft-dependent endocytosis is regulated by tyrosine kinase inhibitors and, through the regulation of the internalization of various ligands, receptors and effectors, is also a determinant of cellular signaling. In this review, we characterize and discuss the regulation of raft-dependent endocytic pathways and the role of key regulators such as caveolin-1. PMID:17760830

Purification and ATPase activity of human ABCA1.

PubMed

Takahashi, Kei; Kimura, Yasuhisa; Kioka, Noriyuki; Matsuo, Michinori; Ueda, Kazumitsu

2006-04-21

ATP-binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high density lipoprotein metabolism. Apolipoprotein A-I binds to ABCA1 and cellular cholesterol and phospholipids, mainly phosphatidylcholine, are loaded onto apoA-I to form pre-beta high density lipoprotein (HDL). It is proposed that ABCA1 translocates phospholipids and cholesterol directly or indirectly to form pre-beta HDL. To explore the mechanism of ABCA1-mediated pre-beta HDL formation, we expressed human ABCA1 in insect Sf9 cells and purified it. Trypsin limited-digestion of purified ABCA1 in the detergent-soluble form suggested that it retained conformation similar to ABCA1 expressed in the membranes of human fibroblast WI-38 cells. Purified ABCA1 showed robust ATPase activity when reconstituted in liposomes made of synthetic phosphatidylcholine. ABCA1 showed lower ATPase activity when reconstituted in liposomes containing phosphatidylserine, phosphatidylethanolamine, or phosphatidylglycerol and also showed weak specificity in acyl chain species. ATPase activity was reduced by the addition of cholesterol and decreased by 25% in the presence of 20% cholesterol. Beta-sitosterol and campesterol showed similar inhibitory effects but stigmasterol did not, suggesting structure-specific interaction between ABCA1 and sterols. Glibenclamide suppressed ABCA1 ATPase, suggesting that it inhibits apoA-I-dependent cellular cholesterol efflux by suppressing ABCA1 ATPase activity. These results suggest that the ATPase activity of ABCA1 is stimulated preferentially by phospholipids with choline head groups, phosphatidylcholine and sphingomyelin. This study with purified human ABCA1 provides the first biochemical basis of the mechanism for HDL formation mediated by ABCA1.

STABILITY AND STOICHIOMETRY OF BILAYER PHOSPHOLIPID-CHOLESTEROL COMPLEXES: RELATIONSHIP TO CELLULAR STEROL DISTRIBUTION AND HOMEOSTASIS&

PubMed Central

Lange, Yvonne; Ali Tabei, S. M.; Ye, Jin; Steck, Theodore L.

2013-01-01

Does cholesterol distribute among intracellular compartments by passive equilibration down its chemical gradient? If so, its distribution should reflect the relative cholesterol affinity of the constituent membrane phospholipids as well as their ability to form stoichiometric cholesterol complexes. We tested this hypothesis by analyzing the reactivity to cholesterol oxidase of large unilamellar vesicles (LUVs) containing biological phospholipids plus varied cholesterol. The rates of cholesterol oxidation differed among the various phospholipid environments by roughly four orders of magnitude. Furthermore, accessibility to the enzyme increased by orders of magnitude at cholesterol thresholds that suggested stoichiometries of association of 1:1, 2:3 or 1:2 cholesterol:phospholipid (mol:mol). Cholesterol accessibility above the threshold was still constrained by its particular phospholipid environment. One phospholipid, 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidylserine, exhibited no threshold. The analysis suggested values for the relative stabilities of the cholesterol-phospholipid complexes and for the fractions of bilayer cholesterol not in complexes at the threshold equivalence points; predictably, the saturated phosphorylcholine species had the lowest stoichiometries and the strongest affinities for cholesterol. These results were in general agreement with the equilibrium distribution of cholesterol between the various LUVs and methyl-β-cyclodextrin. In addition, the properties of the cholesterol in intact human red blood cells matched predictions made from LUVs of the corresponding composition. These results support a passive mechanism for the intracellular distribution of cholesterol that can provide a signal for its homeostatic regulation. PMID:24000774

Cholesterol - what to ask your doctor

MedlinePlus

... your doctor; What to ask your doctor about cholesterol ... What is my cholesterol level? What should my cholesterol level be? What are HDL ("good") cholesterol and LDL ("bad") cholesterol? Does my cholesterol ...

Lipid Absorption Defects in Intestine-specific Microsomal Triglyceride Transfer Protein and ATP-binding Cassette Transporter A1-deficient Mice*

PubMed Central

Iqbal, Jahangir; Parks, John S.; Hussain, M. Mahmood

2013-01-01

We have previously described apolipoprotein B (apoB)-dependent and -independent cholesterol absorption pathways and the role of microsomal triglyceride transfer protein (MTP) and ATP-binding cassette transporter A1 (ABCA1) in these pathways. To assess the contribution of these pathways to cholesterol absorption and to determine whether there are other pathways, we generated mice that lack MTP and ABCA1, individually and in combination, in the intestine. Intestinal deletions of Mttp and Abca1 decreased plasma cholesterol concentrations by 45 and 24%, respectively, whereas their combined deletion reduced it by 59%. Acute cholesterol absorption was reduced by 28% in the absence of ABCA1, and it was reduced by 92–95% when MTP was deleted in the intestine alone or together with ABCA1. MTP deficiency significantly reduced triglyceride absorption, although ABCA1 deficiency had no effect. ABCA1 deficiency did not affect cellular lipids, but Mttp deficiency significantly increased intestinal levels of triglycerides and free fatty acids. Accumulation of intestinal free fatty acids, but not triglycerides, in Mttp-deficient intestines was prevented when mice were also deficient in intestinal ABCA1. Combined deficiency of these genes increased intestinal fatty acid oxidation as a consequence of increased expression of peroxisome proliferator-activated receptor-γ (PPARγ) and carnitine palmitoyltransferase 1α (CPT1α). These studies show that intestinal MTP and ABCA1 are critical for lipid absorption and are the main determinants of plasma and intestinal lipid levels. Reducing their activities might lower plasma lipid concentrations. PMID:24019513

Differential Membrane Dipolar Orientation Induced by Acute and Chronic Cholesterol Depletion.

PubMed

Sarkar, Parijat; Chakraborty, Hirak; Chattopadhyay, Amitabha

2017-06-30

Cholesterol plays a crucial role in cell membrane organization, dynamics and function. Depletion of cholesterol represents a popular approach to explore cholesterol-sensitivity of membrane proteins. An emerging body of literature shows that the consequence of membrane cholesterol depletion often depends on the actual process (acute or chronic), although the molecular mechanism underlying the difference is not clear. Acute depletion, using cyclodextrin-type carriers, is faster relative to chronic depletion, in which inhibitors of cholesterol biosynthesis are used. With the overall goal of addressing molecular differences underlying these processes, we monitored membrane dipole potential under conditions of acute and chronic cholesterol depletion in CHO-K1 cells, using a voltage-sensitive fluorescent dye in dual wavelength ratiometric mode. Our results show that the observed membrane dipole potential exhibits difference under acute and chronic cholesterol depletion conditions, even when cholesterol content was identical. To the best of our knowledge, these results provide, for the first time, molecular insight highlighting differences in dipolar reorganization in these processes. A comprehensive understanding of processes in which membrane cholesterol gets modulated would provide novel insight in its interaction with membrane proteins and receptors, thereby allowing us to understand the role of cholesterol in cellular physiology associated with health and disease.

Residual Cardiovascular Risk in Chronic Kidney Disease: Role of High-density Lipoprotein

PubMed Central

Kon, Valentina; Yang, Haichun; Fazio, Sergio

2016-01-01

Although reducing low-density lipoprotein-cholesterol (LDL-C) levels with lipid-lowering agents (statins) decreases cardiovascular disease (CVD) risk, a substantial residual risk (up to 70% of baseline) remains after treatment in most patient populations. High-density lipoprotein (HDL) is a potential contributor to residual risk, and low HDL-cholesterol (HDL-C) is an established risk factor for CVD. However, in contrast to conventional lipid-lowering therapies, recent studies show that pharmacologic increases in HDL-C levels do not bring about clinical benefits. These observations have given rise to the concept of dysfunctional HDL where increases in serum HDL-C may not be beneficial because HDL loss of function is not corrected by or even intensified by the therapy. Chronic kidney disease (CKD) increases CVD risk, and patients whose CKD progresses to end-stage renal disease (ESRD) requiring dialysis are at the highest CVD risk of any patient type studied. The ESRD population is also unique in its lack of significant benefit from standard lipid-lowering interventions. Recent studies indicate that HDL-C levels do not predict CVD in the CKD population. Moreover, CKD profoundly alters metabolism and composition of HDL particles and impairs their protective effects on functions such as cellular cholesterol efflux, endothelial protection, and control of inflammation and oxidation. Thus, CKD-induced perturbations in HDL may contribute to the excess CVD in CKD patients. Understanding the mechanisms of vascular protection in renal disease can present new therapeutic targets for intervention in this population. PMID:26009251

NPC1L1 and Cholesterol Transport

PubMed Central

Betters, Jenna L.; Yu, Liqing

2010-01-01

The polytopic transmembrane protein, Niemann-Pick C1-Like 1 (NPC1L1), is enriched in the apical membrane of small intestine absorptive enterocytes where it mediates extracellular sterol transport across the brush border membrane. It is essential for intestinal sterol absorption and is the molecular target of ezetimibe, a potent cholesterol absorption inhibitor that lowers blood cholesterol in humans. NPC1L1 is also highly expressed in human liver. The hepatic function of NPC1L1 may be to limit excessive biliary cholesterol loss. NPC1L1-dependent sterol uptake seems to be a clathrin-mediated endocytic process and is regulated by cellular cholesterol content. Recently, NPC1L1 inhibition has been shown to have beneficial effects on components of the metabolic syndrome, such as obesity, insulin resistance, fatty liver, in addition to atherosclerosis. PMID:20307540

Model of OSBP-Mediated Cholesterol Supply to Aichi Virus RNA Replication Sites Involving Protein-Protein Interactions among Viral Proteins, ACBD3, OSBP, VAP-A/B, and SAC1.

PubMed

Ishikawa-Sasaki, Kumiko; Nagashima, Shigeo; Taniguchi, Koki; Sasaki, Jun

2018-04-15

Positive-strand RNA viruses, including picornaviruses, utilize cellular machinery for genome replication. Previously, we reported that each of the 2B, 2BC, 2C, 3A, and 3AB proteins of Aichi virus (AiV), a picornavirus, forms a complex with the Golgi apparatus protein ACBD3 and phosphatidylinositol 4-kinase IIIβ (PI4KB) at viral RNA replication sites (replication organelles [ROs]), enhancing PI4KB-dependent phosphatidylinositol 4-phosphate (PI4P) production. Here, we demonstrate AiV hijacking of the cellular cholesterol transport system involving oxysterol-binding protein (OSBP), a PI4P-binding cholesterol transfer protein. AiV RNA replication was inhibited by silencing cellular proteins known to be components of this pathway, OSBP, the ER membrane proteins VAPA and VAPB (VAP-A/B), the PI4P-phosphatase SAC1, and PI-transfer protein β. OSBP, VAP-A/B, and SAC1 were present at RNA replication sites. We also found various previously unknown interactions among the AiV proteins (2B, 2BC, 2C, 3A, and 3AB), ACBD3, OSBP, VAP-A/B, and SAC1, and the interactions were suggested to be involved in recruiting the component proteins to AiV ROs. Importantly, the OSBP-2B interaction enabled PI4P-independent recruitment of OSBP to AiV ROs, indicating preferential recruitment of OSBP among PI4P-binding proteins. Protein-protein interaction-based OSBP recruitment has not been reported for other picornaviruses. Cholesterol was accumulated at AiV ROs, and inhibition of OSBP-mediated cholesterol transfer impaired cholesterol accumulation and AiV RNA replication. Electron microscopy showed that AiV-induced vesicle-like structures were close to ER membranes. Altogether, we conclude that AiV directly recruits the cholesterol transport machinery through protein-protein interactions, resulting in formation of membrane contact sites between the ER and AiV ROs and cholesterol supply to the ROs. IMPORTANCE Positive-strand RNA viruses utilize host pathways to modulate the lipid composition of viral RNA replication sites for replication. Previously, we demonstrated that Aichi virus (AiV), a picornavirus, forms a complex comprising certain proteins of AiV, the Golgi apparatus protein ACBD3, and the lipid kinase PI4KB to synthesize PI4P lipid at the sites for AiV RNA replication. Here, we confirmed cholesterol accumulation at the AiV RNA replication sites, which are established by hijacking the host cholesterol transfer machinery mediated by a PI4P-binding cholesterol transfer protein, OSBP. We showed that the component proteins of the machinery, OSBP, VAP, SAC1, and PITPNB, are all essential host factors for AiV replication. Importantly, the machinery is directly recruited to the RNA replication sites through previously unknown interactions of VAP/OSBP/SAC1 with the AiV proteins and with ACBD3. Consequently, we propose a specific strategy employed by AiV to efficiently accumulate cholesterol at the RNA replication sites via protein-protein interactions. Copyright © 2018 American Society for Microbiology.

The HDL receptor SR-BI is associated with human prostate cancer progression and plays a possible role in establishing androgen independence.

PubMed

Schörghofer, David; Kinslechner, Katharina; Preitschopf, Andrea; Schütz, Birgit; Röhrl, Clemens; Hengstschläger, Markus; Stangl, Herbert; Mikula, Mario

2015-08-07

Human prostate cancer represents one of the most frequently diagnosed cancers in men worldwide. Currently, diagnostic methods are insufficient to identify patients at risk for aggressive prostate cancer, which is essential for early treatment. Recent data indicate that elevated cholesterol levels in the plasma are a prerequisite for the progression of prostate cancer. Here, we analyzed clinical prostate cancer samples for the expression of receptors involved in cellular cholesterol uptake. We screened mRNA microarray files of prostate cancer samples for alterations in the expression levels of cholesterol transporters. Furthermore, we performed immunohistochemistry analysis on human primary prostate cancer tissue sections derived from patients to investigate the correlation of SR-BI with clinicopathological parameters and the mTOR target pS6. In contrast to LDLR, we identified SR-BI mRNA and protein expression to be induced in high Gleason grade primary prostate cancers. Histologic analysis of prostate biopsies revealed that 53.6 % of all cancer samples and none of the non-cancer samples showed high SR-BI staining intensity. The disease-free survival time was reduced (P = 0.02) in patients expressing high intra-tumor levels of SR-BI. SR-BI mRNA correlated with HSD17B1 and HSD3B1 and SR-BI protein staining showed correlation with active ribosomal protein S6 (RS = 0.828, P < 0.00001). We identified SR-BI to indicate human prostate cancer formation, suggesting that increased levels of SR-BI may be involved in the generation of a castration-resistant phenotype.

Moderate red wine consumption and cardiovascular disease risk: beyond the "French paradox".

PubMed

Lippi, Giuseppe; Franchini, Massimo; Favaloro, Emmanuel J; Targher, Giovanni

2010-02-01

The term FRENCH PARADOX was coined in 1992 to describe the relatively low incidence of cardiovascular disease in the French population, despite a relatively high dietary intake of saturated fats, and potentially attributable to the consumption of red wine. After nearly 20 years, several studies have investigated the fascinating, overwhelmingly positive biological and clinical associations of red wine consumption with cardiovascular disease and mortality. Light to moderate intake of red wine produces a kaleidoscope of potentially beneficial effects that target all phases of the atherosclerotic process, from atherogenesis (early plaque development and growth) to vessel occlusion (flow-mediated dilatation, thrombosis). Such beneficial effects involve cellular signaling mechanisms, interactions at the genomic level, and biochemical modifications of cellular and plasma components. Red wine components, especially alcohol, resveratrol, and other polyphenolic compounds, may decrease oxidative stress, enhance cholesterol efflux from vessel walls (mainly by increasing levels of high-density lipoprotein cholesterol), and inhibit lipoproteins oxidation, macrophage cholesterol accumulation, and foam-cell formation. These components may also increase nitric oxide bioavailability, thereby antagonizing the development of endothelial dysfunction, decrease blood viscosity, improve insulin sensitivity, counteract platelet hyperactivity, inhibit platelet adhesion to fibrinogen-coated surfaces, and decrease plasma levels of von Willebrand factor, fibrinogen, and coagulation factor VII. Light to moderate red wine consumption is also associated with a favorable genetic modulation of fibrinolytic proteins, ultimately increasing the surface-localized endothelial cell fibrinolysis. Overall, therefore, the "French paradox" may have its basis within a milieu containing several key molecules, so that favorable cardiovascular benefits might be primarily attributable to combined, additive, or perhaps synergistic effects of alcohol and other wine components on atherogenesis, coagulation, and fibrinolysis. Conversely, chronic heavy alcohol consumption and binge drinking are associated with increased risk of cardiovascular events. In conclusion, although mounting evidence strongly supports beneficial cardiovascular effects of moderate red wine consumption (one to two drinks per day; 10-30 g alcohol) in most populations, clinical advice to abstainers to initiate daily alcohol consumption has not yet been substantiated in the literature and must be considered with caution on an individual basis.

Functional rescue of mutant ABCA1 proteins by sodium 4-phenylbutyrate.

PubMed

Sorrenson, Brie; Suetani, Rachel J; Williams, Michael J A; Bickley, Vivienne M; George, Peter M; Jones, Gregory T; McCormick, Sally P A

2013-01-01

Mutations in the ATP-binding cassette transporter A1 (ABCA1) are a major cause of decreased HDL cholesterol (HDL-C), which infers an increased risk of cardiovascular disease (CVD). Many ABCA1 mutants show impaired localization to the plasma membrane. The aim of this study was to investigate whether the chemical chaperone, sodium 4-phenylbutyrate (4-PBA) could improve cellular localization and function of ABCA1 mutants. Nine different ABCA1 mutants (p.A594T, p.I659V, p.R1068H, p.T1512M, p.Y1767D, p.N1800H, p.R2004K, p.A2028V, p.Q2239N) expressed in HEK293 cells, displaying different degrees of mislocalization to the plasma membrane and discrete impacts on cholesterol efflux, were subject to treatment with 4-PBA. Treatment restored localization to the plasma membrane and increased cholesterol efflux function for the majority of mutants. Treatment with 4-PBA also increased ABCA1 protein expression in all transfected cell lines. In fibroblast cells obtained from low HDL-C subjects expressing two of the ABCA1 mutants (p.R1068H and p.N1800H), 4-PBA increased cholesterol efflux without any increase in ABCA1 expression. Our study is the first to investigate the effect of the chemical chaperone, 4-PBA on ABCA1 and shows that it is capable of restoring plasma membrane localization and enhancing the cholesterol efflux function of mutant ABCA1s both in vitro and ex vivo. These results suggest 4-PBA may warrant further investigation as a potential therapy for increasing cholesterol efflux and HDL-C levels.

The molecular mechanism of the cholesterol-lowering effect of dill and kale: The influence of the food matrix components.

PubMed

Danesi, Francesca; Govoni, Marco; D'Antuono, Luigi Filippo; Bordoni, Alessandra

2016-07-01

Foods are complex matrices containing many different compounds, all of which contribute to the overall effect of the food itself, although they have different mechanisms of action. While evaluating the effect of bioactive compounds, it is important to consider that the use of a single compound can hide the effects of the other molecules that can act synergistically or antagonistically in the same food. The aim of the present study was to evaluate the influence of food matrix components by comparing two edible plants (dill and kale) with cholesterol-lowering potential and similar contents of their most representative bioactive, quercetin. The molecular effects of the extracts were evaluated in HepG2 cells by measuring the expression of sterol-regulatory element-binding proteins (SREBPs), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and low density lipoprotein receptor (LDLR) at the mRNA and protein level. The results reported here show that both extracts reduced the cellular cholesterol level with a similar trend and magnitude. It is conceivable that the slightly different results are due to the diverse composition of minor bioactive compounds, indicating that only by considering food as a whole is it possible to understand the complex relationship between food, nutrition, and health in a foodomics vision. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

CRISPR Correction of a Homozygous Low-Density Lipoprotein Receptor Mutation in Familial Hypercholesterolemia Induced Pluripotent Stem Cells.

PubMed

Omer, Linda; Hudson, Elizabeth A; Zheng, Shirong; Hoying, James B; Shan, Yuan; Boyd, Nolan L

2017-11-01

Familial hypercholesterolemia (FH) is a hereditary disease primarily due to mutations in the low-density lipoprotein receptor (LDLR) that lead to elevated cholesterol and premature development of cardiovascular disease. Homozygous FH patients (HoFH) with two dysfunctional LDLR alleles are not as successfully treated with standard hypercholesterol therapies, and more aggressive therapeutic approaches to control cholesterol levels must be considered. Liver transplant can resolve HoFH, and hepatocyte transplantation has shown promising results in animals and humans. However, demand for donated livers and high-quality hepatocytes overwhelm the supply. Human pluripotent stem cells can differentiate to hepatocyte-like cells (HLCs) with the potential for experimental and clinical use. To be of future clinical use as autologous cells, LDLR genetic mutations in derived FH-HLCs need to be corrected. Genome editing technology clustered-regularly-interspaced-short-palindromic-repeats/CRISPR-associated 9 (CRISPR/Cas9) can repair pathologic genetic mutations in human induced pluripotent stem cells. We used CRISPR/Cas9 genome editing to permanently correct a 3-base pair homozygous deletion in LDLR exon 4 of patient-derived HoFH induced pluripotent stem cells. The genetic correction restored LDLR-mediated endocytosis in FH-HLCs and demonstrates the proof-of-principle that CRISPR-mediated genetic modification can be successfully used to normalize HoFH cholesterol metabolism deficiency at the cellular level.

[Effect of healthy diet and physical activity on the level of non-HDL cholesterol in obese subjects without cardiovascular disease and diabetes mellitus].

PubMed

Móczár, Csaba

2015-10-18

Prevention program including lifestyle changes was initiated with the participation of obese and overweight subjects recruited from the practices of 29 family doctors. The aim of the author was to analyse changes of non-HDL-cholesterol levels, especially when triglyceride levels were above 2.26 mmol/l, and when non-HDL cholesterol levels were high in association with low HDL-cholesterol levels in overweight or obese subjects who had no cardiovascular disease and diabetes mellitus. Data obtained from 1192 subjects (424 men and 768 women) before and 12 month after inclusion into the prevention program was analysed. The average level of non-HDL-cholesterol in the whole group of subjects decreased from 4.74 to 4.64 mmol/l, but the change was not significant. However, the average concentration of non-HDL-cholesterol was reduced significantly from 4.87 to 4.4 mmol/l in men, whereas no significant change was detected in women. In cases when triglyceride levels were higher than 2.26 mmol/l, the non-HDL-cholesterol level was reduced by 0.65 mmol/l. In cases when the non-HDL-cholesterol level was high in association with low HDL-cholesterol level, the non-HDL-cholesterol was significantly decreased from 5.22 to 4.48 mmol/l. In addition, in cases when HDL-cholesterol levels were low, the average level of the HDL-cholesterol significantly increased from 0.84 to 1.3 mmol/l. Lifestyle changes decrease the level of atherogenic lipid fractions, particularly in men with high triglyceride levels. Improvement of the atherogenic lipid profile in response to lifestyle changes is related not only to the reduction of atherogenic lipid fractions, but also to the increase of HDL-cholesterol level.

Maternal plasma polyunsaturated fatty acid levels during pregnancy and childhood lipids and insulin levels

PubMed Central

Vidakovic, Aleksandra Jelena; Jaddoe, Vincent WV; Voortman, Trudy; Demmelmair, Hans; Koletzko, Berthold; Gaillard, Romy

2017-01-01

Background and Aims Maternal polyunsaturated fatty acid (PUFA) levels are associated with cord blood lipid and insulin levels. Not much is known about the influence of maternal PUFAs during pregnancy on long-term offspring lipid and insulin metabolism. We examined the associations of maternal plasma n-3 and n-6 PUFA levels during pregnancy with childhood lipids and insulin levels. Methods and Results In a population-based prospective cohort study among 3,230 mothers and their children, we measured maternal second trimester n-3 and n-6 PUFA plasma levels. At the median age of 6.0 years (95% range, 5.6-7.9), we measured childhood total-cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol, triglycerides, insulin and c-peptide levels. Higher maternal total n-3 PUFA levels, and specifically DHA levels, were associated with higher childhood total-cholesterol, HDL-cholesterol and insulin levels (p-values <0.05), but not with LDL-cholesterol and triglycerides. Maternal total n-6 PUFA levels were not associated with childhood outcomes, but higher levels of the individual n-6 PUFAs, EDA and DGLA were associated with a lower childhood HDL-cholesterol, and higher AA levels with higher childhood total-cholesterol and HDL-cholesterol levels (all p-values <0.05). A higher maternal n-6/n-3 PUFA ratio was only associated with lower childhood HDL-cholesterol and insulin levels (p-values <0.05). These associations were not explained by childhood body mass index. Conclusions Higher maternal total n-3 PUFAs and specifically DHA levels during pregnancy are associated with higher childhood total-cholesterol, HDL-cholesterol and insulin levels. Only individual maternal n-6 PUFAs, not total maternal n-6 PUFA levels, tended to be associated with childhood lipids and insulin levels. PMID:27919543

Free cholesterol and cholesterol esters in bovine oocytes: Implications in survival and membrane raft organization after cryopreservation

PubMed Central

Ríos, Glenda L.; Canizo, Jesica R.; Antollini, Silvia S.; Alberio, Ricardo H.

2017-01-01

Part of the damage caused by cryopreservation of mammalian oocytes occurs at the plasma membrane. The addition of cholesterol to cell membranes as a strategy to make it more tolerant to cryopreservation has been little addressed in oocytes. In order to increase the survival of bovine oocytes after cryopreservation, we proposed not only to increase cholesterol level of oocyte membranes before vitrification but also to remove the added cholesterol after warming, thus recovering its original level. Results from our study showed that modulation of membrane cholesterol by methyl-β-cyclodextrin (MβCD) did not affect the apoptotic status of oocytes and improved viability after vitrification yielding levels of apoptosis closer to those of fresh oocytes. Fluorometric measurements based on an enzyme-coupled reaction that detects both free cholesterol (membrane) and cholesteryl esters (stored in lipid droplets), revealed that oocytes and cumulus cells present different levels of cholesterol depending on the seasonal period. Variations at membrane cholesterol level of oocytes were enough to account for the differences found in total cholesterol. Differences found in total cholesterol of cumulus cells were explained by the differences found in both the content of membrane cholesterol and of cholesterol esters. Cholesterol was incorporated into the oocyte plasma membrane as evidenced by comparative labeling of a fluorescent cholesterol. Oocytes and cumulus cells increased membrane cholesterol after incubation with MβCD/cholesterol and recovered their original level after cholesterol removal, regardless of the season. Finally, we evaluated the effect of vitrification on the putative raft molecule GM1. Cholesterol modulation also preserved membrane organization by maintaining ganglioside level at the plasma membrane. Results suggest a distinctive cholesterol metabolic status of cumulus-oocyte complexes (COCs) among seasons and a dynamic organizational structure of cholesterol homeostasis within the COC. Modulation of membrane cholesterol by MβCD improved survival of bovine oocytes and preserved integrity of GM1-related rafts after vitrification. PMID:28686720

Properties of the Products Formed by the Activity of Serum Opacity Factor against Human Plasma High Density Lipoproteins

PubMed Central

Pownall, Henry J.; Courtney, Harry S.; Gillard, Baiba K.; Massey, John B.

2010-01-01

Serum opacity factor from Streptococcus pyogenes transfers the cholesteryl esters (CE) of ~100,000 plasma high density lipoprotein particles (HDL) to a CE-rich microemulsion (CERM) while forming neo HDL, a cholesterol-poor HDL-like particle. HDL, neo HDL, and CERM are distinct. Neo HDL is lower in free cholesterol and has lower surface and total microviscosities than HDL; the surface polarity of neo HDL and HDL are similar. CERM is much larger than HDL and richer in cholesterol and CE. Although the surface microviscosity of HDL is higher than that of CERM, they have similar total microviscosities because cholesterol partitions into the neutral lipid core. Because of its unique surface properties apo E preferentially associates with the CERM. In contrast, the composition and properties of neo HDL make it a potential acceptor of cellular cholesterol and its esterification. Thus, neo HDL and CERM are possible vehicles for improving cholesterol transport to the liver. PMID:18838065

The Comparison of Gemfibrozil and Lovastatin Therapy in Patients with High LDL and Low HDL Cholesterol Levels

DTIC Science & Technology

1990-08-01

cholesterol with same method as for TC; however, precision of the HDL measurements were (±SD) ±1.5 mg/dl. Triglycerides ( TG ) were...placebo lipid levels (TC and TG levels), lipoprotein cholesterol levels (LDL, VLDL, and HDL cholesterol levels), and the cholesterol ratios between... high density lipoprotein cholesterol in the serum and risk of mortality: evidence of a threshold effect. Br Med J. 1985; 290:1239-43. 7. Gordon

Characterization of Cholesterol Homeostasis in Telomerase-immortalized Tangier Disease Fibroblasts Reveals Marked Phenotype Variability*

PubMed Central

Kannenberg, Frank; Gorzelniak, Kerstin; Jäger, Kathrin; Fobker, Manfred; Rust, Stephan; Repa, Joyce; Roth, Mike; Björkhem, Ingemar; Walter, Michael

2013-01-01

We compared the consequences of an ABCA1 mutation that produced an apparent lack of atherosclerosis (Tangier family 1, N935S) with an ABCA1 mutation with functional ABCA1 knockout that was associated with severe atherosclerosis (Tangier family 2, Leu548:Leu575-End), using primary and telomerase-immortalized fibroblasts. Telomerase-immortalized Tangier fibroblasts of family 1 (TT1) showed 30% residual cholesterol efflux capacity in response to apolipoprotein A-I, whereas telomerase-immortalized Tangier fibroblasts of family 2 (TT2) showed only 20%. However, there were a number of secondary differences that were often stronger and may help to explain the more rapid development of atherosclerosis in family 2. First, the total cellular cholesterol content increase was 2–3-fold and 3–5-fold in TT1 and TT2 cells, respectively. The corresponding increase in esterified cholesterol concentration was 10- and 40-fold, respectively. Second, 24-, 25-, and 27-hydroxycholesterol concentrations were moderately increased in TT1 cells, but were increased as much as 200-fold in TT2 cells. Third, cholesterol biosynthesis was moderately decreased in TT1 cells, but was markedly decreased in TT2 cells. Fourth, potentially atheroprotective LXR-dependent SREBP1c signaling was normal in TT1, but was rather suppressed in TT2 cells. Cultivated primary Tangier fibroblasts were characterized by premature aging in culture and were associated with less obvious biochemical differences. In summary, these results may help to understand the differential atherosclerotic susceptibility in Tangier disease and further demonstrate the usefulness of telomerase-immortalized cells in studying this cellular phenotype. The data support the contention that side chain-oxidized oxysterols are strong suppressors of cholesterol biosynthesis under specific pathological conditions in humans. PMID:24196952

Characterization of cholesterol homeostasis in telomerase-immortalized Tangier disease fibroblasts reveals marked phenotype variability.

PubMed

Kannenberg, Frank; Gorzelniak, Kerstin; Jäger, Kathrin; Fobker, Manfred; Rust, Stephan; Repa, Joyce; Roth, Mike; Björkhem, Ingemar; Walter, Michael

2013-12-27

We compared the consequences of an ABCA1 mutation that produced an apparent lack of atherosclerosis (Tangier family 1, N935S) with an ABCA1 mutation with functional ABCA1 knockout that was associated with severe atherosclerosis (Tangier family 2, Leu(548):Leu(575)-End), using primary and telomerase-immortalized fibroblasts. Telomerase-immortalized Tangier fibroblasts of family 1 (TT1) showed 30% residual cholesterol efflux capacity in response to apolipoprotein A-I, whereas telomerase-immortalized Tangier fibroblasts of family 2 (TT2) showed only 20%. However, there were a number of secondary differences that were often stronger and may help to explain the more rapid development of atherosclerosis in family 2. First, the total cellular cholesterol content increase was 2-3-fold and 3-5-fold in TT1 and TT2 cells, respectively. The corresponding increase in esterified cholesterol concentration was 10- and 40-fold, respectively. Second, 24-, 25-, and 27-hydroxycholesterol concentrations were moderately increased in TT1 cells, but were increased as much as 200-fold in TT2 cells. Third, cholesterol biosynthesis was moderately decreased in TT1 cells, but was markedly decreased in TT2 cells. Fourth, potentially atheroprotective LXR-dependent SREBP1c signaling was normal in TT1, but was rather suppressed in TT2 cells. Cultivated primary Tangier fibroblasts were characterized by premature aging in culture and were associated with less obvious biochemical differences. In summary, these results may help to understand the differential atherosclerotic susceptibility in Tangier disease and further demonstrate the usefulness of telomerase-immortalized cells in studying this cellular phenotype. The data support the contention that side chain-oxidized oxysterols are strong suppressors of cholesterol biosynthesis under specific pathological conditions in humans.

Effect of open-label infusion of an apoA-I-containing particle (CER-001) on RCT and artery wall thickness in patients with FHA[S

PubMed Central

Kootte, Ruud S.; Smits, Loek P.; van der Valk, Fleur M.; Dasseux, Jean-Louis; Keyserling, Constance H.; Barbaras, Ronald; Paolini, John F.; Santos, Raul D.; van Dijk, Theo H.; Dallinga-van Thie, Geesje M.; Nederveen, Aart J.; Mulder, Willem J. M.; Hovingh, G. Kees; Kastelein, John J. P.; Groen, Albert K.; Stroes, Erik S.

2015-01-01

Reverse cholesterol transport (RCT) contributes to the anti-atherogenic effects of HDL. Patients with the orphan disease, familial hypoalphalipoproteinemia (FHA), are characterized by decreased tissue cholesterol removal and an increased atherogenic burden. We performed an open-label uncontrolled proof-of-concept study to evaluate the effect of infusions with a human apoA-I-containing HDL-mimetic particle (CER-001) on RCT and the arterial vessel wall in FHA. Subjects received 20 infusions of CER-001 (8 mg/kg) during 6 months. Efficacy was assessed by measuring (apo)lipoproteins, plasma-mediated cellular cholesterol efflux, fecal sterol excretion (FSE), and carotid artery wall dimension by MRI and artery wall inflammation by 18F-fluorodeoxyglucose-positron emission tomography/computed tomography scans. We included seven FHA patients: HDL-cholesterol (HDL-c), 13.8 [1.8–29.1] mg/dl; apoA-I, 28.7 [7.9–59.1] mg/dl. Following nine infusions in 1 month, apoA-I and HDL-c increased directly after infusion by 27.0 and 16.1 mg/dl (P = 0.018). CER-001 induced a 44% relative increase (P = 0.018) in in vitro cellular cholesterol efflux with a trend toward increased FSE (P = 0.068). After nine infusions of CER-001, carotid mean vessel wall area decreased compared with baseline from 25.0 to 22.8 mm2 (P = 0.043) and target-to-background ratio from 2.04 to 1.81 (P = 0.046). In FHA-subjects, CER-001 stimulates cholesterol mobilization and reduces artery wall dimension and inflammation, supporting further evaluation of CER-001 in FHA patients. PMID:25561459

Effect of open-label infusion of an apoA-I-containing particle (CER-001) on RCT and artery wall thickness in patients with FHA.

PubMed

Kootte, Ruud S; Smits, Loek P; van der Valk, Fleur M; Dasseux, Jean-Louis; Keyserling, Constance H; Barbaras, Ronald; Paolini, John F; Santos, Raul D; van Dijk, Theo H; Dallinga-van Thie, Geesje M; Nederveen, Aart J; Mulder, Willem J M; Hovingh, G Kees; Kastelein, John J P; Groen, Albert K; Stroes, Erik S

2015-03-01

Reverse cholesterol transport (RCT) contributes to the anti-atherogenic effects of HDL. Patients with the orphan disease, familial hypoalphalipoproteinemia (FHA), are characterized by decreased tissue cholesterol removal and an increased atherogenic burden. We performed an open-label uncontrolled proof-of-concept study to evaluate the effect of infusions with a human apoA-I-containing HDL-mimetic particle (CER-001) on RCT and the arterial vessel wall in FHA. Subjects received 20 infusions of CER-001 (8 mg/kg) during 6 months. Efficacy was assessed by measuring (apo)lipoproteins, plasma-mediated cellular cholesterol efflux, fecal sterol excretion (FSE), and carotid artery wall dimension by MRI and artery wall inflammation by (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography scans. We included seven FHA patients: HDL-cholesterol (HDL-c), 13.8 [1.8-29.1] mg/dl; apoA-I, 28.7 [7.9-59.1] mg/dl. Following nine infusions in 1 month, apoA-I and HDL-c increased directly after infusion by 27.0 and 16.1 mg/dl (P = 0.018). CER-001 induced a 44% relative increase (P = 0.018) in in vitro cellular cholesterol efflux with a trend toward increased FSE (P = 0.068). After nine infusions of CER-001, carotid mean vessel wall area decreased compared with baseline from 25.0 to 22.8 mm(2) (P = 0.043) and target-to-background ratio from 2.04 to 1.81 (P = 0.046). In FHA-subjects, CER-001 stimulates cholesterol mobilization and reduces artery wall dimension and inflammation, supporting further evaluation of CER-001 in FHA patients. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

microRNAs and HDL life cycle.

PubMed

Canfrán-Duque, Alberto; Ramírez, Cristina M; Goedeke, Leigh; Lin, Chin-Sheng; Fernández-Hernando, Carlos

2014-08-01

miRNAs have emerged as important regulators of lipoprotein metabolism. Work over the past few years has demonstrated that miRNAs control the expression of most of the genes associated with high-density lipoprotein (HDL) metabolism, including the ATP transporters, ABCA1 and ABCG1, and the scavenger receptor SRB1. These findings strongly suggest that miRNAs regulate HDL biogenesis, cellular cholesterol efflux, and HDL cholesterol (HDL-C) uptake in the liver, thereby controlling all of the steps of reverse cholesterol transport. Recent work in animal models has demonstrated that manipulating miRNA levels including miR-33 can increase circulating HDL-C. Importantly, antagonizing miR-33 in vivo enhances the regression and reduces the progression of atherosclerosis. These findings support the idea of developing miRNA inhibitors for the treatment of dyslipidaemia and related cardiovascular disorders such as atherosclerosis. This review article focuses on how HDL metabolism is regulated by miRNAs and how antagonizing miRNA expression could be a potential therapy for treating cardiometabolic diseases. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Sphingolipid Organization in the Plasma Membrane and the Mechanisms That Influence It

PubMed Central

Kraft, Mary L.

2017-01-01

Sphingolipids are structural components in the plasma membranes of eukaryotic cells. Their metabolism produces bioactive signaling molecules that modulate fundamental cellular processes. The segregation of sphingolipids into distinct membrane domains is likely essential for cellular function. This review presents the early studies of sphingolipid distribution in the plasma membranes of mammalian cells that shaped the most popular current model of plasma membrane organization. The results of traditional imaging studies of sphingolipid distribution in stimulated and resting cells are described. These data are compared with recent results obtained with advanced imaging techniques, including super-resolution fluorescence detection and high-resolution secondary ion mass spectrometry (SIMS). Emphasis is placed on the new insight into the sphingolipid organization within the plasma membrane that has resulted from the direct imaging of stable isotope-labeled lipids in actual cell membranes with high-resolution SIMS. Super-resolution fluorescence techniques have recently revealed the biophysical behaviors of sphingolipids and the unhindered diffusion of cholesterol analogs in the membranes of living cells are ultimately in contrast to the prevailing hypothetical model of plasma membrane organization. High-resolution SIMS studies also conflicted with the prevailing hypothesis, showing sphingolipids are concentrated in micrometer-scale membrane domains, but cholesterol is evenly distributed within the plasma membrane. Reductions in cellular cholesterol decreased the number of sphingolipid domains in the plasma membrane, whereas disruption of the cytoskeleton eliminated them. In addition, hemagglutinin, a transmembrane protein that is thought to be a putative raft marker, did not cluster within sphingolipid-enriched regions in the plasma membrane. Thus, sphingolipid distribution in the plasma membrane is dependent on the cytoskeleton, but not on favorable interactions with cholesterol or hemagglutinin. The alternate views of plasma membrane organization suggested by these findings are discussed. PMID:28119913

Sphingolipid Organization in the Plasma Membrane and the Mechanisms That Influence It.

PubMed

Kraft, Mary L

2016-01-01

Sphingolipids are structural components in the plasma membranes of eukaryotic cells. Their metabolism produces bioactive signaling molecules that modulate fundamental cellular processes. The segregation of sphingolipids into distinct membrane domains is likely essential for cellular function. This review presents the early studies of sphingolipid distribution in the plasma membranes of mammalian cells that shaped the most popular current model of plasma membrane organization. The results of traditional imaging studies of sphingolipid distribution in stimulated and resting cells are described. These data are compared with recent results obtained with advanced imaging techniques, including super-resolution fluorescence detection and high-resolution secondary ion mass spectrometry (SIMS). Emphasis is placed on the new insight into the sphingolipid organization within the plasma membrane that has resulted from the direct imaging of stable isotope-labeled lipids in actual cell membranes with high-resolution SIMS. Super-resolution fluorescence techniques have recently revealed the biophysical behaviors of sphingolipids and the unhindered diffusion of cholesterol analogs in the membranes of living cells are ultimately in contrast to the prevailing hypothetical model of plasma membrane organization. High-resolution SIMS studies also conflicted with the prevailing hypothesis, showing sphingolipids are concentrated in micrometer-scale membrane domains, but cholesterol is evenly distributed within the plasma membrane. Reductions in cellular cholesterol decreased the number of sphingolipid domains in the plasma membrane, whereas disruption of the cytoskeleton eliminated them. In addition, hemagglutinin, a transmembrane protein that is thought to be a putative raft marker, did not cluster within sphingolipid-enriched regions in the plasma membrane. Thus, sphingolipid distribution in the plasma membrane is dependent on the cytoskeleton, but not on favorable interactions with cholesterol or hemagglutinin. The alternate views of plasma membrane organization suggested by these findings are discussed.

ABCA1 agonist peptides for the treatment of disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bielicki, John K.

Purpose of review The review summarizes information pertaining to the preclinical development of new apolipoprotein (apo) E mimetic peptides that stimulate cellular cholesterol efflux. Recent findings Small α-helical peptides based on the C-terminal domain of apoE have been developed for therapeutic applications. These peptides stimulate cellular cholesterol efflux via the ATP-binding cassette transporter A1 (ABCA1) with high potency, like native apolipoproteins on a molar basis. This potent activity has been related to the unique ability of these peptides to maintain α-helix structure upon dilution. Recent structure-activity studies improving the safety features of these mimetic peptides have greatly improved their potentialmore » for clinical use. Structural features of the class A α-helix motif that induce muscle toxicity and hypertriglyceridemia have been identified. These may have implications for the design of other HDL mimetic peptides. Summary ABCA1 is an integral membrane protein that plays a central role in biology. Its principal function is to mediate the efflux of cholesterol and phospholipid from cells to extracellular apo, preventing a build-up of excess cholesterol in membranes. This process generates HDL particles that perform a variety of functions to protect against disease. A number of these functions can be viewed as directly or indirectly supporting ABCA1 activity, thus constituting a positive feedback system to optimize cellular lipid efflux responses and disease prevention. Consequently, therapeutic approaches that mimic the activities of apos may prove highly effective to combat disease. One such approach involves the use of peptides. The broad biological relevance of ABCA1 suggests these apo mimetic peptides may be useful for the treatment of a number of diseases, such as atherosclerosis, diabetes, and Alzheimer's disease.« less

ABCA1 agonist peptides for the treatment of disease

DOE PAGES

Bielicki, John K.

2016-02-01

Purpose of review The review summarizes information pertaining to the preclinical development of new apolipoprotein (apo) E mimetic peptides that stimulate cellular cholesterol efflux. Recent findings Small α-helical peptides based on the C-terminal domain of apoE have been developed for therapeutic applications. These peptides stimulate cellular cholesterol efflux via the ATP-binding cassette transporter A1 (ABCA1) with high potency, like native apolipoproteins on a molar basis. This potent activity has been related to the unique ability of these peptides to maintain α-helix structure upon dilution. Recent structure-activity studies improving the safety features of these mimetic peptides have greatly improved their potentialmore » for clinical use. Structural features of the class A α-helix motif that induce muscle toxicity and hypertriglyceridemia have been identified. These may have implications for the design of other HDL mimetic peptides. Summary ABCA1 is an integral membrane protein that plays a central role in biology. Its principal function is to mediate the efflux of cholesterol and phospholipid from cells to extracellular apo, preventing a build-up of excess cholesterol in membranes. This process generates HDL particles that perform a variety of functions to protect against disease. A number of these functions can be viewed as directly or indirectly supporting ABCA1 activity, thus constituting a positive feedback system to optimize cellular lipid efflux responses and disease prevention. Consequently, therapeutic approaches that mimic the activities of apos may prove highly effective to combat disease. One such approach involves the use of peptides. The broad biological relevance of ABCA1 suggests these apo mimetic peptides may be useful for the treatment of a number of diseases, such as atherosclerosis, diabetes, and Alzheimer's disease.« less

A comparative study on fluorescent cholesterol analogs as versatile cellular reporters[S

PubMed Central

Sezgin, Erdinc; Can, Fatma Betul; Schneider, Falk; Clausen, Mathias P.; Galiani, Silvia; Stanly, Tess A.; Waithe, Dominic; Colaco, Alexandria; Honigmann, Alf; Wüstner, Daniel; Platt, Frances; Eggeling, Christian

2016-01-01

Cholesterol (Chol) is a crucial component of cellular membranes, but knowledge of its intracellular dynamics is scarce. Thus, it is of utmost interest to develop tools for visualization of Chol organization and dynamics in cells and tissues. For this purpose, many studies make use of fluorescently labeled Chol analogs. Unfortunately, the introduction of the label may influence the characteristics of the analog, such as its localization, interaction, and trafficking in cells; hence, it is important to get knowledge of such bias. In this report, we compared different fluorescent lipid analogs for their performance in cellular assays: 1) plasma membrane incorporation, specifically the preference for more ordered membrane environments in phase-separated giant unilamellar vesicles and giant plasma membrane vesicles; 2) cellular trafficking, specifically subcellular localization in Niemann-Pick type C disease cells; and 3) applicability in fluorescence correlation spectroscopy (FCS)-based and super-resolution stimulated emission depletion-FCS-based measurements of membrane diffusion dynamics. The analogs exhibited strong differences, with some indicating positive performance in the membrane-based experiments and others in the intracellular trafficking assay. However, none showed positive performance in all assays. Our results constitute a concise guide for the careful use of fluorescent Chol analogs in visualizing cellular Chol dynamics. PMID:26701325

African swine fever virus infects macrophages, the natural host cells, via clathrin- and cholesterol-dependent endocytosis.

PubMed

Galindo, Inmaculada; Cuesta-Geijo, Miguel Angel; Hlavova, Karolina; Muñoz-Moreno, Raquel; Barrado-Gil, Lucía; Dominguez, Javier; Alonso, Covadonga

2015-03-16

The main cellular target for African swine fever virus (ASFV) is the porcine macrophage. However, existing data about the early phases of infection were previously characterized in non-leukocyte cells such as Vero cells. Here, we report that ASFV enters the natural host cell using dynamin-dependent and clathrin-mediated endocytosis. This pathway is strongly pH-dependent during the first steps of infection in porcine macrophages. We investigated the effect of drugs inhibiting several endocytic pathways in macrophages and compared ASFV with vaccinia virus (VV), which apparently involves different entry pathways. The presence of cholesterol in cellular membranes was found to be essential for a productive ASFV infection while actin-dependent endocytosis and the participation of phosphoinositide-3-kinase (PI3K) activity were other cellular factors required in the process of viral entry. These findings improved our understanding of the ASFV interactions with macrophages that allow for successful viral replication. Copyright © 2015 Elsevier B.V. All rights reserved.

Interaction of pathogens with host cholesterol metabolism.

PubMed

Sviridov, Dmitri; Bukrinsky, Michael

2014-10-01

Pathogens of different taxa, from prions to protozoa, target cellular cholesterol metabolism to advance their own development and to impair host immune responses, but also causing metabolic complications, for example, atherosclerosis. This review describes recent findings of how pathogens do it. A common theme in interaction between pathogens and host cholesterol metabolism is pathogens targeting lipid rafts of the host plasma membrane. Many intracellular pathogens use rafts as an entry gate, taking advantage of the endocytic machinery and high abundance of outward-looking molecules that can be used as receptors. At the same time, disruption of the rafts' functional capacity, achieved by the pathogens through a number of various means, impairs the ability of the host to generate immune response, thus helping pathogen to thrive. Pathogens cannot synthesize cholesterol, and salvaging host cholesterol helps pathogens build advanced cholesterol-containing membranes and assembly platforms. Impact on cholesterol metabolism is not limited to the infected cells; proteins and microRNAs secreted by infected cells affect lipid metabolism systemically. Given an essential role that host cholesterol metabolism plays in pathogen development, targeting this interaction may be a viable strategy to fight infections, as well as metabolic complications of the infections.

Non-high-density lipoprotein cholesterol vs low-density lipoprotein cholesterol as a risk factor for ischemic stroke: a result from the Kailuan study.

PubMed

Wu, Jianwei; Chen, Shengyun; Liu, Liping; Gao, Xiang; Zhou, Yong; Wang, Chunxue; Zhang, Qian; Wang, Anxin; Hussain, Mohammed; Sun, Baoying; Wu, Shouling; Zhao, Xingquan

2013-06-01

To compare the predictive value of serum low-density lipoprotein (LDL) cholesterol and non-high-density lipoprotein (non-HDL) cholesterol levels for ischemic stroke in the Chinese population. We performed a four-year cohort study of 95 778 men and women, aged 18-98 years, selected from the Kailuan study (2006-2007). Baseline LDL cholesterol levels were estimated using direct test method. Total cholesterol levels were estimated using endpoint test method. The predictive values of LDL cholesterol and non-HDL cholesterol for ischemic stroke were compared. During the follow-up period, there were 1153 incident cases of ischemic stroke. The hazard ratio (HR) for ischemic stroke in the top quintile of LDL cholesterol was the highest among five quintiles (HR: 1·25; 95% confidence interval (CI), 1·01-1·53). The HR in the top quintile of non-HDL cholesterol for ischemic stroke was also the highest among five quintiles (HR: 1·53; 95% CI, 1·24-1·88). Analysis of trends showed a significant positive relationship between ischemic stroke incidence and serum LDL cholesterol level, and non-HDL cholesterol level, respectively (both P < 0·05). The area under the curve of LDL cholesterol and non-HDL cholesterol for ischemic stroke was 0·51 and 0·56, respectively (P < 0·05 for the difference). Serum Non-HDL cholesterol level is a stronger predictor for the risk of ischemic stroke than serum LDL cholesterol level in the Chinese population.

MicroRNA 302a is a novel modulator of cholesterol homeostasis and atherosclerosis

PubMed Central

Meiler, Svenja; Baumer, Yvonne; Toulmin, Emma; Seng, Kosal; Boisvert, William A.

2014-01-01

Objective Macrophage foam cell formation is a key feature of atherosclerosis. Recent studies have shown that specific microRNAs (miRs) are regulated in modified low-density lipoprotein (LDL)- treated macrophages, which can affect the cellular cholesterol homeostasis. Undertaking a genome-wide screen of microRNAs regulated in primary macrophages by modified LDL, miR-302a emerged as a potential candidate that may play a key role in macrophage cholesterol homeostasis. Approach and Results The objective of this study was to assess the involvement of miR-302a in macrophage lipid homeostasis and if it can influence circulating lipid levels and atherosclerotic development when it is inhibited in a murine atherosclerosis model. We found that transfection of primary macrophages with either miR-302a or anti-miR-302a regulated the expression of ATP-binding cassette (ABC) transporter ABCA1 mRNA and protein. Luciferase reporter assays showed that miR-302a repressed the 3′UTR activity of mouse Abca1 by 48% and human ABCA1 by 45%. Additionally, transfection of murine macrophages with miR-302a attenuated cholesterol efflux to apolipoprotein A-1 (apoA-1) by 38%. Long-term in vivo administration of anti-miR-302a to mice with LDL receptor deficiency (Ldlr−/−) fed an atherogenic diet led to an increase in ABCA1 in the liver and aorta as well as an increase in circulating plasma HDL levels by 35% compared with that of control mice. The anti-miR-302a-treated mice also displayed reduced atherosclerotic plaque size by approximately 25% as well as a more stable plaque morphology with reduced signs of inflammation. Conclusions These studies identify miR-302a as a novel modulator of cholesterol efflux and a potential therapeutic target for suppressing atherosclerosis. PMID:25524771

MicroRNA 302a is a novel modulator of cholesterol homeostasis and atherosclerosis.

PubMed

Meiler, Svenja; Baumer, Yvonne; Toulmin, Emma; Seng, Kosal; Boisvert, William A

2015-02-01

Macrophage foam cell formation is a key feature of atherosclerosis. Recent studies have shown that specific microRNAs (miRs) are regulated in modified low-density lipoprotein-treated macrophages, which can affect the cellular cholesterol homeostasis. Undertaking a genome-wide screen of miRs regulated in primary macrophages by modified low-density lipoprotein, miR-302a emerged as a potential candidate that may play a key role in macrophage cholesterol homeostasis. The objective of this study was to assess the involvement of miR-302a in macrophage lipid homeostasis and if it can influence circulating lipid levels and atherosclerotic development when it is inhibited in a murine atherosclerosis model. We found that transfection of primary macrophages with either miR-302a or anti-miR-302a regulated the expression of ATP-binding cassette (ABC) transporter ABCA1 mRNA and protein. Luciferase reporter assays showed that miR-302a repressed the 3' untranslated regions (UTR) activity of mouse Abca1 by 48% and human ABCA1 by 45%. In addition, transfection of murine macrophages with miR-302a attenuated cholesterol efflux to apolipoprotein A-1 (apoA-1) by 38%. Long-term in vivo administration of anti-miR-302a to mice with low-density lipoprotein receptor deficiency (Ldlr(-/-)) fed an atherogenic diet led to an increase in ABCA1 in the liver and aorta as well as an increase in circulating plasma high-density lipoprotein levels by 35% compared with that of control mice. The anti-miR-302a-treated mice also displayed reduced atherosclerotic plaque size by ≈25% and a more stable plaque morphology with reduced signs of inflammation. These studies identify miR-302a as a novel modulator of cholesterol efflux and a potential therapeutic target for suppressing atherosclerosis. © 2014 American Heart Association, Inc.

Integration of carbohydrate metabolism and redox state controls dauer larva formation in Caenorhabditis elegans.

PubMed

Penkov, Sider; Kaptan, Damla; Erkut, Cihan; Sarov, Mihail; Mende, Fanny; Kurzchalia, Teymuras V

2015-08-20

Under adverse conditions, Caenorhabditis elegans enters a diapause stage called the dauer larva. External cues signal the nuclear hormone receptor DAF-12, the activity of which is regulated by its ligands: dafachronic acids (DAs). DAs are synthesized from cholesterol, with the last synthesis step requiring NADPH, and their absence stimulates dauer formation. Here we show that NADPH levels determine dauer formation in a regulatory mechanism involving key carbohydrate and redox metabolic enzymes. Elevated trehalose biosynthesis diverts glucose-6-phosphate from the pentose phosphate pathway, which is the major source of cellular NADPH. This enhances dauer formation due to the decrease in the DA level. Moreover, DAF-12, in cooperation with DAF-16/FoxO, induces negative feedback of DA synthesis via activation of the trehalose-producing enzymes TPS-1/2 and inhibition of the NADPH-producing enzyme IDH-1. Thus, the dauer developmental decision is controlled by integration of the metabolic flux of carbohydrates and cellular redox potential.

A Comparison of Raman Spectral Features of Frozen and Deparaffinized Tissues in Neuroblastoma and Ganglioneuroma

NASA Astrophysics Data System (ADS)

Devpura, Suneetha; Thakur, Jagdish S.; Poulik, Janet M.; Rabah, Raja; Naik, Vaman M.; Naik, Ratna

2012-02-01

We have investigated the cellular regions in neuroblastoma and ganglioneuroma using Raman spectroscopy and compared their spectral characteristics with those of normal adrenal gland. Thin sections from both frozen and deparaffinized tissues, obtained from the same tissue specimen, were studied in conjunction with the pathological examination of the tissues. We found a significant difference in the spectral features of frozen sections of normal adrenal gland, neuroblastoma, and ganglioneuroma when compared to deparaffinized tissues. The quantitative analysis of the Raman data using chemometric methods of principal component analysis and discriminant function analysis obtained from the frozen tissues show a sensitivity and specificity of 100% each. The biochemical identification based on the spectral differences shows that the normal adrenal gland tissues have higher levels of carotenoids, lipids, and cholesterol compared to the neuroblastoma and ganglioneuroma frozen tissues. However, deparaffinized tissues show complete removal of these biochemicals in adrenal tissues. This study demonstrates that Raman spectroscopy combined with chemometric methods can successfully distinguish neuroblastoma and ganglioneuroma at cellular level.

Lower Squalene Epoxidase and Higher Scavenger Receptor Class B Type 1 Protein Levels Are Involved in Reduced Serum Cholesterol Levels in Stroke-Prone Spontaneously Hypertensive Rats.

PubMed

Michihara, Akihiro; Mido, Mayuko; Matsuoka, Hiroshi; Mizutani, Yurika

2015-01-01

A lower serum cholesterol level was recently shown to be one of the causes of stroke in an epidemiological study. Spontaneously hypertensive rats stroke-prone (SHRSP) have lower serum cholesterol levels than normotensive Wistar-Kyoto rats (WKY). To elucidate the mechanisms responsible for the lower serum cholesterol levels in SHRSP, we determined whether the amounts of cholesterol biosynthetic enzymes or the receptor and transporter involved in cholesterol uptake and efflux in the liver were altered in SHRSP. When the mRNA levels of seven cholesterol biosynthetic enzymes were measured using real-time polymerase chain reaction (PCR), farnesyl pyrophosphate synthase and squalene epoxidase (SQE) levels in the liver of SHRSP were significantly lower than those in WKY. SQE protein levels were significantly reduced in tissues other than the brain of SHRSP. No significant differences were observed in low-density lipoprotein (LDL) receptor (uptake of serum LDL-cholesterol) or ATP-binding cassette transporter A1 (efflux of cholesterol from the liver/formation of high-density lipoprotein (HDL)) protein levels in the liver and testis between SHRSP and WKY, whereas scavenger receptor class B type 1 (SRB1: uptake of serum HDL-cholesterol) protein levels were higher in the livers of SHRSP. These results indicated that the lower protein levels of SQE and higher protein levels of SRB1 in the liver were involved in the reduced serum cholesterol levels in SHRSP.

Structure-function relationships in reconstituted HDL: Focus on antioxidative activity and cholesterol efflux capacity.

PubMed

Cukier, Alexandre M O; Therond, Patrice; Didichenko, Svetlana A; Guillas, Isabelle; Chapman, M John; Wright, Samuel D; Kontush, Anatol

2017-09-01

High-density lipoprotein (HDL) contains multiple components that endow it with biological activities. Apolipoprotein A-I (apoA-I) and surface phospholipids contribute to these activities; however, structure-function relationships in HDL particles remain incompletely characterised. Reconstituted HDLs (rHDLs) were prepared from apoA-I and soy phosphatidylcholine (PC) at molar ratios of 1:50, 1:100 and 1:150. Oxidative status of apoA-I was varied using controlled oxidation of Met112 residue. HDL-mediated inactivation of PC hydroperoxides (PCOOH) derived from mildly pre-oxidized low-density lipoprotein (LDL) was evaluated by HPLC with chemiluminescent detection in HDL+LDL mixtures and re-isolated LDL. Cellular cholesterol efflux was characterised in RAW264.7 macrophages. rHDL inactivated LDL-derived PCOOH in a dose- and time-dependent manner. The capacity of rHDL to both inactivate PCOOH and efflux cholesterol via ATP-binding cassette transporter A1 (ABCA1) increased with increasing apoA-I/PC ratio proportionally to the apoA-I content in rHDL. Controlled oxidation of apoA-I Met112 gradually decreased PCOOH-inactivating capacity of rHDL but increased ABCA1-mediated cellular cholesterol efflux. Increasing apoA-I content in rHDL enhanced its antioxidative activity towards oxidized LDL and cholesterol efflux capacity via ABCA1, whereas oxidation of apoA-I Met112 decreased the antioxidative activity but increased the cholesterol efflux. These findings provide important considerations in the design of future HDL therapeutics. Non-standard abbreviations and acronyms: AAPH, 2,2'-azobis(-amidinopropane) dihydrochloride; ABCA1, ATP-binding cassette transporter A1; apoA-I, apolipoprotein A-I; BHT, butylated hydroxytoluene; CV, cardiovascular; EDTA, ethylenediaminetetraacetic acid; HDL-C, high-density lipoprotein cholesterol; LOOH, lipid hydroperoxides; Met(O), methionine sulfoxide; Met112, methionine 112 residue; Met86, methionine 86 residue; oxLDL, oxidized low-density lipoprotein; PBS, phosphate-buffered saline; PC, phosphatidylcholine; PL, phospholipid; PCOOH, phosphatidylcholine hydroperoxide; PLOOH, phospholipid hydroperoxide. Copyright © 2017 Elsevier B.V. All rights reserved.

Lipid profile lowering effect of Soypro fermented with lactic acid bacteria isolated from Kimchi in high-fat diet-induced obese rats.

PubMed

Kim, Na-Hyung; Moon, Phil-Dong; Kim, Su-Jin; Choi, In-Young; An, Hyo-Jin; Myung, Noh-Yil; Jeong, Hyun-Ja; Um, Jae-Young; Hong, Seung-Heon; Kim, Hyung-Min

2008-01-01

Lactic acid bacteria are known to exert various physiologic functions in humans. In the current study, we investigated the effects of Soypro, a new soymilk fermented with lactic acid bacteria, like Leuconostoc kimchii, Leuconostoc citreum, and Lactobacillus plantarum, isolated from Kimchi, on adipocyte differentiation in preadipocyte 3T3-L1 cell lines and weight gain or the plasma lipid profile in Sprague-Dawley rats. Adipocyte 3T3-L1 cells treated with Soypro (10 microg/ml) significantly reduced the contents of cellular triglyceride and inhibited cell differentiation by Oil red O staining. Treatment with Soypro (10 microg/ml) for an additional two days in adipocytes inhibited the expression of peroxisome proliferator-activated receptor-gamma2 and CCAAT/enhancer binding protein-alpha, transcription factors of adipocyte differentiation. Based on these in vitro studies, we examined the anti-obesity effect of Soypro in rats for six weeks. Soypro had no significant effect on high-fat diet-induced increases in body weight, food intake, or feed gain ratio. However, the administration of Soypro significantly reduced the concentration of the plasma low density lipoprotein cholesterol. Changes in the plasma levels of total cholesterol and glucose were inclined to decrease in Soypro administrated groups compared with saline treated group. Triglyceride and high density lipoprotein cholesterol values in Soypro fed groups were similar compared to those of saline fed groups. Although further research is needed, these findings suggest that Soypro decreased the levels of low density lipoprotein cholesterol in high-fat diet-induced obesity and might partially inhibit the adipocyte differentiation through the suppression of a transcription factors peroxisome proliferator-activated receptor-gamma2 and CCAAT/enhancer binding protein-alpha.

Synthesis and Live-Cell Imaging of Fluorescent Sterols for Analysis of Intracellular Cholesterol Transport.

PubMed

Modzel, Maciej; Lund, Frederik W; Wüstner, Daniel

2017-01-01

Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE). CTL differs from cholesterol only in having two additional double bonds in the ring system, which is why it is slightly fluorescent in the ultraviolet (UV). In the first part of this protocol, we describe how to synthesize and image CTL in living cells relative to caveolin, a structural component of caveolae. In the second part, we explain in detail how to perform time-lapse experiments of commercially available BODIPY-tagged cholesterol (TopFluor-cholesterol ® ; TF-Chol) in comparison to DHE. Finally, using two-photon time-lapse imaging data of TF-Chol, we demonstrate how to use our imaging toolbox SpatTrack for tracking sterol rich vesicles in living cells over time.

Prenatal Ethanol Exposure Up-Regulates the Cholesterol Transporters ATP-Binding Cassette A1 and G1 and Reduces Cholesterol Levels in the Developing Rat Brain.

PubMed

Zhou, Chunyan; Chen, Jing; Zhang, Xiaolu; Costa, Lucio G; Guizzetti, Marina

2014-11-01

Cholesterol plays a pivotal role in many aspects of brain development; reduced cholesterol levels during brain development, as a consequence of genetic defects in cholesterol biosynthesis, leads to severe brain damage, including microcephaly and mental retardation, both of which are also hallmarks of the fetal alcohol syndrome. We had previously shown that ethanol up-regulates the levels of two cholesterol transporters, ABCA1 (ATP binding cassette-A1) and ABCG1, leading to increased cholesterol efflux and decreased cholesterol content in astrocytes in vitro. In the present study we investigated whether similar effects could be seen in vivo. Pregnant Sprague-Dawley rats were fed liquid diets containing 36% of the calories from ethanol from gestational day (GD) 6 to GD 21. A pair-fed control groups and an ad libitum control group were included in the study. ABCA1 and ABCG1 protein expression and cholesterol and phospholipid levels were measured in the neocortex of female and male fetuses at GD 21. Body weights were decreased in female fetuses as a consequence of ethanol treatments. ABCA1 and ABCG1 protein levels were increased, and cholesterol levels were decreased, in the neocortex of ethanol-exposed female, but not male, fetuses. Levels of phospholipids were unchanged. Control female fetuses fed ad libitum displayed an up-regulation of ABCA1 and a decrease in cholesterol content compared with pair-fed controls, suggesting that a compensatory up-regulation of cholesterol levels may occur during food restriction. Maternal ethanol consumption may affect fetal brain development by increasing cholesterol transporters' expression and reducing brain cholesterol levels. © The Author 2014. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Enhanced cellular uptake of maleimide-modified liposomes via thiol-mediated transport

PubMed Central

Li, Tianshu; Takeoka, Shinji

2014-01-01

With a small amount of maleimide modification on the liposome surface, enhanced cellular uptake of liposomes and drug-delivery efficiency can be obtained both in vitro and in vivo. Herein, we describe the mechanisms underlying this enhanced cellular uptake. Suppression of the cellular uptake of maleimide-modified liposomes (M-GGLG, composed of 1,5-dihexadecyl N,N-diglutamyl-lysyl-L-glutamate [GGLG]/cholesterol/poly(ethylene glycol) – 1,2-distearoyl-sn-glycero-3-phosphoethanolamine [PEG5000-DSPE]/maleimide [M]-PEG5000-Glu2C18 at a molar ratio of 5:5:0.03:0.03) caused by temperature block and addition of serum was alleviated compared with that of liposomes without maleimide modification (GGLG liposomes, composed of GGLG/cholesterol/PEG5000-DSPE/PEG5000-Glu2C18 at a molar ratio of 5:5:0.03:0.03). When 0.01 nM N-ethylmaleimide was used to pre-block cellular thiols, the cellular uptake of M-GGLG liposomes was decreased to approximately 70% in HeLa, HCC1954, MDA-MB-468, and COS-7 cell lines. Moreover, inhibition of a thiol-related reductase such as protein disulfide isomerase resulted in a 15%–45% inhibition of the cellular uptake of M-GGLG liposomes, whereas GGLG liposomes were not influenced. Further, single and mixed inhibitors of clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis did not efficiently inhibit the cellular uptake of M-GGLG liposomes. Using confocal microscopy, we verified that M-GGLG liposomes were localized partially in lysosomes after inhibition of the mentioned conventional endocytic pathways. Therefore, it was hypothesized that the mechanisms underlying the enhanced cellular uptake of liposomes by maleimide modification was thiol-mediated membrane trafficking, including endocytosis and energy-independent transport. PMID:24940060

Enhanced cellular uptake of maleimide-modified liposomes via thiol-mediated transport.

PubMed

Li, Tianshu; Takeoka, Shinji

2014-01-01

With a small amount of maleimide modification on the liposome surface, enhanced cellular uptake of liposomes and drug-delivery efficiency can be obtained both in vitro and in vivo. Herein, we describe the mechanisms underlying this enhanced cellular uptake. Suppression of the cellular uptake of maleimide-modified liposomes (M-GGLG, composed of 1,5-dihexadecyl N,N-diglutamyl-lysyl-L-glutamate [GGLG]/cholesterol/poly(ethylene glycol) - 1,2-distearoyl-sn-glycero-3-phosphoethanolamine [PEG₅₀₀₀-DSPE]/maleimide [M]-PEG₅₀₀₀-Glu2C18 at a molar ratio of 5:5:0.03:0.03) caused by temperature block and addition of serum was alleviated compared with that of liposomes without maleimide modification (GGLG liposomes, composed of GGLG/cholesterol/PEG₅₀₀₀-DSPE/PEG₅₀₀₀-Glu2C₁₈ at a molar ratio of 5:5:0.03:0.03). When 0.01 nM N-ethylmaleimide was used to pre-block cellular thiols, the cellular uptake of M-GGLG liposomes was decreased to approximately 70% in HeLa, HCC1954, MDA-MB-468, and COS-7 cell lines. Moreover, inhibition of a thiol-related reductase such as protein disulfide isomerase resulted in a 15%-45% inhibition of the cellular uptake of M-GGLG liposomes, whereas GGLG liposomes were not influenced. Further, single and mixed inhibitors of clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis did not efficiently inhibit the cellular uptake of M-GGLG liposomes. Using confocal microscopy, we verified that M-GGLG liposomes were localized partially in lysosomes after inhibition of the mentioned conventional endocytic pathways. Therefore, it was hypothesized that the mechanisms underlying the enhanced cellular uptake of liposomes by maleimide modification was thiol-mediated membrane trafficking, including endocytosis and energy-independent transport.

FABP4-mediated homocysteine-induced cholesterol accumulation in THP-1 monocyte-derived macrophages and the potential epigenetic mechanism.

PubMed

Jiang, Yideng; Ma, Shengchao; Zhang, Huiping; Yang, Xiaoling; Lu, Guan Jun; Zhang, Hui; He, Yangyang; Kong, Fanqi; Yang, Anning; Xu, Hua; Zhang, Minghao; Jiao, Yun; Li, Guizhong; Cao, Jun; Jia, Yuexia; Jin, Shaoju; Wei, Jun; Shi, Yingkang

2016-07-01

Hyperhomocysteinemia (HHcy) is an independent risk factor for the development of atherosclerosis (AS), according to overwhelming number of clinical and epidemiological studies. However, the underlying pathogenic molecular mechanisms by which HHcy promotes AS remain to be fully elucidated. Fatty acid binding protein 4 (FABP4) has been shown to be important in macrophage cholesterol trafficking. The objective of the present study was to determine whether homocysteine (Hcy) accelerates AS through regulating FABP4, and then mediates cholesterol accumulation in macrophages. Hcy concentrations of 0, 50, 100, 200 and 500 µM, and 100 µM Hcy+30 µM vitamin B12 (VB12)+30 µM folic acid (FA) were respectively added to cultured THP‑1 monocyte‑derived macrophages for 24 h. The levels of FABP4, which acts as a key factor connecting cellular lipid accumulation to inflammation, were determined using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blot analyses in the macrophages. The present study used a nested touchdown methylation‑specific PCR assay to detect the DNA methylation status of the FABP4 promoter region. In addition, the FABP4 gene fragment was inserted into the cloning vector, pcDNA3.1‑EGFP, to construct the recombinant plasmid, pcDNA3.1‑EGFP/FABP4, which was identified using restriction endonuclease digestion analysis and DNA sequencing. The pcDNA3.1‑EGFP/FABP4 expression plasmid was transfected into THP‑1 monocyte‑derived macrophages, mediated by liposome reagent, following which the expression levels of FABP4 were detected using RT‑qPCR and western blot analyses. The present study also determined the intracellular accumulation of total cholesterol in the macrophages. The results indicated that Hcy decreased the levels of FABP4 promoter methylation, but increased the mRNA and protein expression levels of FABP4 in the macrophages, compared with the control group (0 µM Hcy). However, no dose‑dependent changes were observed with increasing concentrations of Hcy. The recombinant fluorescent eukaryotic expression vector, pcDNA3.1‑EGFP/FABP4, was successfully constructed and effectively expressed in the THP‑1 macrophages. The results also showed that FABP4 accelerated the accumulation of cholesterol in the macrophages. Taken together, the results of the present study suggested that FABP4 DNA hypomethylation induced by Hcy may be involved in the overexpression of FABP4, thereby inducing cholesterol accumulation in macrophages.

Effects of NS lactobacillus strains on lipid metabolism of rats fed a high-cholesterol diet

PubMed Central

2013-01-01

Background Elevated serum cholesterol level is generally considered to be a risk factor for the development of cardiovascular diseases which seriously threaten human health. The cholesterol-lowering effects of lactic acid bacteria have recently become an area of great interest and controversy for many researchers. In this study, we investigated the effects of two NS lactobacillus strains, Lactobacillus plantarum NS5 and Lactobacillus delbrueckii subsp. bulgaricus NS12, on lipid metabolism of rats fed a high cholesterol diet. Methods Thirty-two SD rats were assigned to four groups and fed either a normal or a high-cholesterol diet. The NS lactobacillus treated groups received the high-cholesterol diet supplemented with Lactobacillus plantarum NS5 or Lactobacillus delbrueckii subsp. bulgaricus NS12 in drinking water. The rats were sacrificed after a 6-week feeding period. Body weights, visceral organ and fat weights, serum and liver cholesterol and lipid levels, intestinal microbiota and liver mRNA expression levels related to cholesterol metabolism were analyzed. Liver lipid deposition and adipocyte size were evaluated histologically. Results Compared with rats fed a high cholesterol diet, serum total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B and free fatty acids levels were decreased and apolipoprotein A-I level was increased in NS5 or NS12 strain treated rats, and with no significant change in high-density lipoprotein cholesterol level. Liver cholesterol and triglyceride levels were also significantly decreased in NS lactobacillus strains treated groups. Meanwhile, the NS lactobacillus strains obviously alleviated hepatic injuries, decreased liver lipid deposition and reduced adipocyte size of high cholesterol diet fed rats. NS lactobacillus strains restored the changes in intestinal microbiota compositions, such as the increase in Bacteroides and the decrease in Clostridium. NS lactobacillus strains also regulated the mRNA expression levels of liver enzymes related to cholesterol metabolism, including the down regulation of acyl-CoA:cholesterol acyltransferase (ACAT) and the upregulation of cholesterol 7α-hydroxylase (CYP7A1). Conclusion This study suggested that the two NS lactobacillus strains may affect lipid metabolism and have cholesterol-lowering effects in rats fed a high cholesterol diet. PMID:23656797

The additive effects of the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism

PubMed Central

Chen, Lizhen; Du, Shuixian; Lu, Linlin; Lin, Zhonghua; Jin, Wenwen; Hu, Doudou; Jiang, Xiangjun; Xin, Yongning; Xuan, Shiying

2017-01-01

There is a genetic susceptibility for nonalcoholic fatty liver disease (NAFLD). To examine the role of genetic factors in the disease, a Bayesian analysis was performed to model gene relationships in NAFLD pathogenesis. The Bayesian analysis indicated a potential gene interaction between the TM6SF2 and PNPLA3 genes. Next, to explore the underlying mechanism at the cellular level, we evaluated the additive effects between the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism. Hepa 1-6 cells were transfected with a control vector or with overexpression vectors for TM6SF2/PNPLA3-wild type, TM6SF2-mutant type, PNPLA3-mutant type, or TM6SF2/PNPLA3-mutant type. Commercial kits were used to measure triglyceride and total cholesterol levels in each of the five groups. The mRNA and protein expression levels of sterol regulatory element-binding transcription factor 1c and fatty acid synthase were analyzed using real-time PCR and western blotting. The triglyceride and total cholesterol contents were significantly different among the groups. The triglyceride and total cholesterol contents and the sterol regulatory element-binding transcription factor 1c and fatty acid synthase mRNA and protein expression levels were significantly higher in the TM6SF2/PNPLA3-mutant type group than in the TM6SF2-mutant type group or the PNPLA3-mutant type group. The TM6SF2 E167K and PNPLA3 I148M polymorphisms may have additive effects on lipid metabolism by increasing the expression of sterol regulatory element-binding transcription factor 1c and fatty acid synthase. PMID:29088779

The additive effects of the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism.

PubMed

Chen, Lizhen; Du, Shuixian; Lu, Linlin; Lin, Zhonghua; Jin, Wenwen; Hu, Doudou; Jiang, Xiangjun; Xin, Yongning; Xuan, Shiying

2017-09-26

There is a genetic susceptibility for nonalcoholic fatty liver disease (NAFLD). To examine the role of genetic factors in the disease, a Bayesian analysis was performed to model gene relationships in NAFLD pathogenesis. The Bayesian analysis indicated a potential gene interaction between the TM6SF2 and PNPLA3 genes. Next, to explore the underlying mechanism at the cellular level, we evaluated the additive effects between the TM6SF2 E167K and PNPLA3 I148M polymorphisms on lipid metabolism. Hepa 1-6 cells were transfected with a control vector or with overexpression vectors for TM6SF2/PNPLA3-wild type, TM6SF2-mutant type, PNPLA3-mutant type, or TM6SF2/PNPLA3-mutant type. Commercial kits were used to measure triglyceride and total cholesterol levels in each of the five groups. The mRNA and protein expression levels of sterol regulatory element-binding transcription factor 1c and fatty acid synthase were analyzed using real-time PCR and western blotting. The triglyceride and total cholesterol contents were significantly different among the groups. The triglyceride and total cholesterol contents and the sterol regulatory element-binding transcription factor 1c and fatty acid synthase mRNA and protein expression levels were significantly higher in the TM6SF2/PNPLA3-mutant type group than in the TM6SF2-mutant type group or the PNPLA3-mutant type group. The TM6SF2 E167K and PNPLA3 I148M polymorphisms may have additive effects on lipid metabolism by increasing the expression of sterol regulatory element-binding transcription factor 1c and fatty acid synthase.

miR-27b inhibits LDLR and ABCA1 expression but does not influence plasma and hepatic lipid levels in mice

PubMed Central

Goedeke, Leigh; Rotllan, Noemi; Ramírez, Cristina M.; Aranda, Juan F.; Canfrán-Duque, Alberto; Araldi, Elisa; Fernández-Hernando, Ana; Langhi, Cedric; de Cabo, Rafael; Baldán, Ángel; Suárez, Yajaira; Fernández-Hernando, Carlos

2015-01-01

Rationale Recently, there has been significant interest in the therapeutic administration of miRNA mimics and inhibitors to treat cardiovascular disease. In particular, miR-27b has emerged as a regulatory hub in cholesterol and lipid metabolism and potential therapeutic target for treating atherosclerosis. Despite this, the impact of miR-27b on lipid levels in vivo remains to be determined. As such, here we set out to further characterize the role of miR-27b in regulating cholesterol metabolism in vitro and to determine the effect of miR-27b overexpression and inhibition on circulating and hepatic lipids in mice. Methods and Results Our results identify miR-27b as an important regulator of LDLR activity in human and mouse hepatic cells through direct targeting of LDLR and LDLRAP1. In addition, we report that modulation of miR-27b expression affects ABCA1 protein levels and cellular cholesterol efflux to ApoA1 in human hepatic Huh7 cells. Overexpression of pre-miR-27b in the livers of wild-type mice using AAV8 vectors increased pre-miR-27b levels 50–fold and reduced hepatic ABCA1 and LDLR expression by 50% and 20%, respectively, without changing circulating and hepatic cholesterol and triglycerides. To determine the effect of endogenous miR-27b on circulating lipids, wild-type mice were fed a Western diet for one month and injected with 5 mg/kg of LNA control or LNA anti-miR-27b oligonucleotides. Following two weeks of treatment, the expression of ABCA1 and LDLR were increased by 10–20% in the liver, demonstrating effective inhibition of miR-27b function. Intriguingly, no differences in circulating and hepatic lipids were observed between treatment groups. Conclusions The results presented here provide evidence that short-term modulation of miR-27b expression in wild-type mice regulates hepatic LDLR and ABCA1 expression but does not influence plasma and hepatic lipid levels. PMID:26520906

Cholesterol effectively blocks entry of flavivirus.

PubMed

Lee, Chyan-Jang; Lin, Hui-Ru; Liao, Ching-Len; Lin, Yi-Ling

2008-07-01

Japanese encephalitis virus (JEV) and dengue virus serotype 2 (DEN-2) are enveloped flaviviruses that enter cells through receptor-mediated endocytosis and low pH-triggered membrane fusion and then replicate in intracellular membrane structures. Lipid rafts, cholesterol-enriched lipid-ordered membrane domains, are platforms for a variety of cellular functions. In this study, we found that disruption of lipid raft formation by cholesterol depletion with methyl-beta-cyclodextrin or cholesterol chelation with filipin III reduces JEV and DEN-2 infection, mainly at the intracellular replication steps and, to a lesser extent, at viral entry. Using a membrane flotation assay, we found that several flaviviral nonstructural proteins are associated with detergent-resistant membrane structures, indicating that the replication complex of JEV and DEN-2 localizes to the membranes that possess the lipid raft property. Interestingly, we also found that addition of cholesterol readily blocks flaviviral infection, a result that contrasts with previous reports of other viruses, such as Sindbis virus, whose infectivity is enhanced by cholesterol. Cholesterol mainly affected the early step of the flavivirus life cycle, because the presence of cholesterol during viral adsorption greatly blocked JEV and DEN-2 infectivity. Flavirial entry, probably at fusion and RNA uncoating steps, was hindered by cholesterol. Our results thus suggest a stringent requirement for membrane components, especially with respect to the amount of cholesterol, in various steps of the flavivirus life cycle.

New agents and approaches to treatment in Niemann-Pick type C disease.

PubMed

Pérez-Poyato, María S; Pineda, Mercé

2011-06-01

Niemann-Pick disease type C is an autosomal recessive disorder caused by mutations in either one of the two genes, NPC1 or NPC2, which encode proteins involved in the regulation of normal transport and/or processing of free cholesterol. Several types of lipids including free cholesterol (unesterified), sphingosine, sphingomyelin, phospholipids and glycosphingolipids (glucosylceramide and gangliosides GM2 and GM3) are accumulated in lysosomes and late endosomes of cells, with pronounced concentrations in the liver and the spleen. The key laboratory diagnostic test for NP-C is filliping staining of cultured skin fibroblasts from the patient, to demonstrate free cholesterol accumulation in lysosomes secondary to impaired intracellular cholesterol transport. The symptomatology and rate of disease progression are strongly influenced by age at disease onset and different clinical forms have been described on this basis: Perinatal, Early-infantile (EI), late-infantile (LI), juvenile and adult forms. Clinical symptoms include progressive neurological deterioration and visceral organomegaly. Nowadays there is no fully effective treatment, only supportive measures for relief of specific manifestations of the disease. The intervention to slow disease progression is the most promising therapy. A number of experimental disease - specific therapies, based on the molecular pathology of NP-C, have been tested in cell culture and animal models including neurosteroids, cholesterol - binding agents, curcumin and Miglustat. This paper summarizes the recent developments that have been investigated for the treatment in patients and animal models with NPC. Current therapeutic approaches have been classified based on the targeting of cellular function, the anti - apoptotic cellular mechanisms and the stem cells therapy.

Deficiency in the Lipid Exporter ABCA1 Impairs Retrograde Sterol Movement and Disrupts Sterol Sensing at the Endoplasmic Reticulum*♦

PubMed Central

Yamauchi, Yoshio; Iwamoto, Noriyuki; Rogers, Maximillian A.; Abe-Dohmae, Sumiko; Fujimoto, Toyoshi; Chang, Catherine C. Y.; Ishigami, Masato; Kishimoto, Takuma; Kobayashi, Toshihide; Ueda, Kazumitsu; Furukawa, Koichi; Chang, Ta-Yuan; Yokoyama, Shinji

2015-01-01

Cellular cholesterol homeostasis involves sterol sensing at the endoplasmic reticulum (ER) and sterol export from the plasma membrane (PM). Sterol sensing at the ER requires efficient sterol delivery from the PM; however, the macromolecules that facilitate retrograde sterol transport at the PM have not been identified. ATP-binding cassette transporter A1 (ABCA1) mediates cholesterol and phospholipid export to apolipoprotein A-I for the assembly of high density lipoprotein (HDL). Mutations in ABCA1 cause Tangier disease, a familial HDL deficiency. Several lines of clinical and experimental evidence suggest a second function of ABCA1 in cellular cholesterol homeostasis in addition to mediating cholesterol efflux. Here, we report the unexpected finding that ABCA1 also plays a key role in facilitating retrograde sterol transport from the PM to the ER for sterol sensing. Deficiency in ABCA1 delays sterol esterification at the ER and activates the SREBP-2 cleavage pathway. The intrinsic ATPase activity in ABCA1 is required to facilitate retrograde sterol transport. ABCA1 deficiency causes alternation of PM composition and hampers a clathrin-independent endocytic activity that is required for ER sterol sensing. Our finding identifies ABCA1 as a key macromolecule facilitating bidirectional sterol movement at the PM and shows that ABCA1 controls retrograde sterol transport by modulating a certain clathrin-independent endocytic process. PMID:26198636

Fish protein hydrolysates affect cholesterol metabolism in rats fed non-cholesterol and high-cholesterol diets.

PubMed

Hosomi, Ryota; Fukunaga, Kenji; Arai, Hirofumi; Kanda, Seiji; Nishiyama, Toshimasa; Yoshida, Munehiro

2012-03-01

Fish consumption is well known to provide health benefits in both experimental animals and human subjects. Numerous studies have demonstrated the beneficial effects of various protein hydrolysates on lipid metabolism. In this context, this study examined the effect of fish protein hydrolysates (FPH) on cholesterol metabolism compared with the effect of casein. FPHs were prepared from Alaska pollock meat using papain as a protease. Male Wistar rats were divided into the following four dietary groups of seven rats each: either casein (20%) or FPH (10%) + casein (10%), with or without 0.5% cholesterol and 0.1% sodium cholate. Serum and liver lipid levels, fecal cholesterol and bile acid excretions, and the hepatic expression of genes encoding proteins involved in cholesterol homeostasis were examined. In rats fed the FPH diets compared with casein diets with or without cholesterol and sodium cholate, the indexes of cholesterol metabolism-namely, serum cholesterol, triglyceride, and low-density lipoprotein-cholesterol levels-were significantly lower, whereas fecal cholesterol and bile acid excretions were higher. Rats fed the FPH diets compared with casein with cholesterol exhibited a lower liver cholesterol level via an increased liver cholesterol 7α-hydroxylase (CYP7A1) expression level. This study demonstrates that the intake of FPH has hypocholesterolemic effects through the enhancement of fecal cholesterol and bile acid excretions and CYP7A1 expression levels. Therefore, fish peptides prepared by papain digestion might provide health benefits by decreasing the cholesterol content in the blood, which would contribute to the prevention of circulatory system diseases such as arteriosclerosis.

Diet, atherosclerosis, and fish oil.

PubMed

Connor, W E; Connor, S L

1990-01-01

The principal goal of dietary prevention and treatment of atherosclerotic coronary heart disease is the achievement of physiological levels of the plasma total and LDL cholesterol, triglyceride, and VLDL. These goals have been well delineated by the National Cholesterol Education Program of the National Heart, Lung and Blood Institute and the American Heart Association. Dietary treatment is first accomplished by enhancing LDL receptor activity and at the same time depressing liver synthesis of cholesterol and triglyceride. Both dietary cholesterol and saturated fat decrease LDL receptor activity and inhibit the removal of LDL from the plasma by the liver. Saturated fat decreases LDL receptor activity, especially when cholesterol is concurrently present in the diet. The total amount of dietary fat is of importance also. The greater the flux of chylomicron remnants is into the liver, the greater is the influx of cholesterol ester. In addition, factors that affect VLDL and LDL synthesis could be important. These include excessive calories (obesity), which enhance triglyceride and VLDL and hence LDL synthesis. Weight loss and omega-3 fatty acids from fish oil depress synthesis of both VLDL and triglyceride in the liver. The optimal diet for the treatment of children and adults to prevent coronary disease has the following characteristics: cholesterol (100 mg/day), total fat (20% of calories, 6% saturated with the balance from omega-3 and omega-6 polyunsaturated and monounsaturated fat), carbohydrate (65% of calories, two thirds from starch including 11 to 15 gm of soluble fiber), and protein (15% of calories). This low-fat, high-carbohydrate diet can lower the plasma cholesterol 18% to 21%. This diet is also an antithrombotic diet, thrombosis being another major consideration in preventing coronary heart disease. Dietary therapy is the mainstay of the prevention and treatment of coronary heart disease through the control of plasma lipid and lipoprotein levels. The exact place of the omega-3 fatty acids from fish and fish oil remains to be defined. However, this much seems certain. Fish provides an excellent substitute for meat in the diet. Fish is lower in fat, especially saturated fat, and contains the omega-3 fatty acids. Fish oil may have promise as a therapeutic agent in certain hyperlipidemic states, especially the chylomicronemia of type V hyperlipidemia. Fish oil has logical and well-defined antithrombotic and anti-atherosclerotic activities since it depresses thromboxane A2 production and inhibits cellular proliferation responsible for the progression of atherosclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Juvenile-onset loss of lipid-raft domains in attractin-deficient mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azouz, Abdallah; Gunn, Teresa M.; Duke-Cohan, Jonathan S.

2007-02-15

Mutations at the attractin (Atrn) locus in mice result in altered pigmentation on an agouti background, higher basal metabolic rate and juvenile-onset hypomyelination leading to neurodegeneration, while studies on human immune cells indicate a chemotaxis regulatory function. The underlying biochemical defect remains elusive. In this report we identify a role for attractin in plasma membrane maintenance. In attractin's absence there is a decline in plasma membrane glycolipid-enriched rafts from normal levels at 8 weeks to a complete absence by 24 weeks. The structural integrity of lipid rafts depends upon cholesterol and sphingomyelin, and can be identified by partitioning within ofmore » ganglioside GM{sub 1}. Despite a significant fall in cellular cholesterol with maturity, and a lesser fall in both membrane and total cellular GM{sub 1}, these parameters lag behind raft loss, and are normal when hypomyelination/neurodegeneration has already begun thus supporting consequence rather than cause. These findings can be recapitulated in Atrn-deficient cell lines propagated in vitro. Further, signal transduction through complex membrane receptor assemblies is not grossly disturbed despite the complete absence of lipid rafts. We find these results compatible with a role for attractin in plasma membrane maintenance and consistent with the proposal that the juvenile-onset hypomyelination and neurodegeneration represent a defect in attractin-mediated raft-dependent myelin biogenesis.« less

Curcumin as a potential candidate for treating hyperlipidemia: A review of cellular and metabolic mechanisms.

PubMed

Panahi, Yunes; Ahmadi, Yasin; Teymouri, Manouchehr; Johnston, Thomas P; Sahebkar, Amirhossein

2018-01-01

Curcumin is an herbal polyphenol extensively investigated for antioxidant, anti-inflammatory, and hypolipidaemic properties. In the present review, the efficacy of curcumin for improving a plasma lipid profile has been evaluated and compared with statins, a well-known class of medicines for treating hypercholesterolemia and hyperlipidaemia. Curcumin is presumably most effective in reducing triglyceride (TG), while statins are most efficient in lowering low-density lipoproteins-cholesterol (LDL-C). Additionally, various molecular and metabolic mediators of cholesterol and plasma lipid homeostasis are discussed in relation to how they are modulated by curcumin or statins. Overall, curcumin influences the same mediators of plasma lipid alteration as statins do. Almost all the pathways through which cholesterol trafficking takes place are affected by these agents. These include gastrointestinal absorption of dietary cholesterol, hepatocellular removal of plasma cholesterol, the mediators of reverse cholesterol transport, and removal of cholesterol from peripheral tissues. Moreover, the reactive oxygen species (ROS) scavenging potential of curcumin limits the risk of lipid peroxidation that triggers inflammatory responses causing cardiovascular diseases (CVD) and atherosclerosis. Taken together, curcumin could be used as a safe and well-tolerated adjunct to statins to control hyperlipidaemia more effectively than statins alone. © 2017 Wiley Periodicals, Inc.

Constitutive hippocampal cholesterol loss underlies poor cognition in old rodents

PubMed Central

Martin, Mauricio G; Ahmed, Tariq; Korovaichuk, Alejandra; Venero, Cesar; Menchón, Silvia A; Salas, Isabel; Munck, Sebastian; Herreras, Oscar; Balschun, Detlef; Dotti, Carlos G

2014-01-01

Cognitive decline is one of the many characteristics of aging. Reduced long-term potentiation (LTP) and long-term depression (LTD) are thought to be responsible for this decline, although the precise mechanisms underlying LTP and LTD dampening in the old remain unclear. We previously showed that aging is accompanied by the loss of cholesterol from the hippocampus, which leads to PI3K/Akt phosphorylation. Given that Akt de-phosphorylation is required for glutamate receptor internalization and LTD, we hypothesized that the decrease in cholesterol in neuronal membranes may contribute to the deficits in LTD typical of aging. Here, we show that cholesterol loss triggers p-Akt accumulation, which in turn perturbs the normal cellular and molecular responses induced by LTD, such as impaired AMPA receptor internalization and its reduced lateral diffusion. Electrophysiology recordings in brain slices of old mice and in anesthetized elderly rats demonstrate that the reduced hippocampal LTD associated with age can be rescued by cholesterol perfusion. Accordingly, cholesterol replenishment in aging animals improves hippocampal-dependent learning and memory in the water maze test. PMID:24878762

Fluorescent Sterols and Cholesteryl Esters as Probes for Intracellular Cholesterol Transport

PubMed Central

Solanko, Katarzyna A.; Modzel, Maciej; Solanko, Lukasz M.; Wüstner, Daniel

2015-01-01

Cholesterol transport between cellular organelles comprised vesicular trafficking and nonvesicular exchange; these processes are often studied by quantitative fluorescence microscopy. A major challenge for using this approach is producing analogs of cholesterol with suitable brightness and structural and chemical properties comparable with those of cholesterol. This review surveys currently used fluorescent sterols with respect to their behavior in model membranes, their photophysical properties, as well as their transport and metabolism in cells. In the first part, several intrinsically fluorescent sterols, such as dehydroergosterol or cholestatrienol, are discussed. These polyene sterols (P-sterols) contain three conjugated double bonds in the steroid ring system, giving them slight fluorescence in ultraviolet light. We discuss the properties of P-sterols relative to cholesterol, outline their chemical synthesis, and explain how to image them in living cells and organisms. In particular, we show that P-sterol esters inserted into low-density lipoprotein can be tracked in the fibroblasts of Niemann–Pick disease using high-resolution deconvolution microscopy. We also describe fluorophore-tagged cholesterol probes, such as BODIPY-, NBD-, Dansyl-, or Pyrene-tagged cholesterol, and eventual esters of these analogs. Finally, we survey the latest developments in the synthesis and use of alkyne cholesterol analogs to be labeled with fluorophores by click chemistry and discuss the potential of all approaches for future applications. PMID:27330304

Opioid doses required for pain management in lung cancer patients with different cholesterol levels: negative correlation between opioid doses and cholesterol levels.

PubMed

Huang, Zhenhua; Liang, Lining; Li, Lingyu; Xu, Miao; Li, Xiang; Sun, Hao; He, Songwei; Lin, Lilong; Zhang, Yixin; Song, Yancheng; Yang, Man; Luo, Yuling; Loh, Horace H; Law, Ping-Yee; Zheng, Dayong; Zheng, Hui

2016-03-08

Pain management has been considered as significant contributor to broad quality-of-life improvement for cancer patients. Modulating serum cholesterol levels affects analgesia abilities of opioids, important pain killer for cancer patients, in mice system. Thus the correlation between opioids usages and cholesterol levels were investigated in human patients with lung cancer. Medical records of 282 patients were selected with following criteria, 1) signed inform consent, 2) full medical records on total serum cholesterol levels and opioid administration, 3) opioid-naïve, 4) not received/receiving cancer-related or cholesterol lowering treatment, 5) pain level at level 5-8. The patients were divided into different groups basing on their gender and cholesterol levels. Since different opioids, morphine, oxycodone, and fentanyl, were all administrated at fixed low dose initially and increased gradually only if pain was not controlled, the percentages of patients in each group who did not respond to the initial doses of opioids and required higher doses for pain management were determined and compared. Patients with relative low cholesterol levels have larger percentage (11 out of 28 in female and 31 out of 71 in male) to not respond to the initial dose of opioids than those with high cholesterol levels (0 out of 258 in female and 8 out of 74 in male). Similar differences were obtained when patients with different opioids were analyzed separately. After converting the doses of different opioids to equivalent doses of oxycodone, significant correlation between opioid usages and cholesterol levels was also observed. Therefore, more attention should be taken to those cancer patients with low cholesterol levels because they may require higher doses of opioids as pain killer.

A Statistical Study of Serum Cholesterol Level by Gender and Race.

PubMed

Tharu, Bhikhari Prasad; Tsokos, Chris P

2017-07-25

Cholesterol level (CL) is growing concerned as health issue in human health since it is considered one of the causes in heart diseases. A study of cholesterol level can provide insight about its nature and characteristics. A cross-sectional study. National Health and Nutrition Examination Survey (NHANS) II was conducted on a probability sample of approximately 28,000 persons in the USA and cholesterol level is obtained from laboratory results. Samples were selected so that certain population groups thought to be at high risk of malnutrition. Study included 11,864 persons for CL cases with 9,602 males and 2,262 females with races: whites, blacks, and others. Non-parametric statistical tests and goodness of fit test have been used to identify probability distributions. The study concludes that the cholesterol level exhibits significant racial and gender differences in terms of probability distributions. The study has concluded that white people are relatively higher at risk than black people to have risk line and high risk cholesterol. The study clearly indicates that black males normally have higher cholesterol. Females have lower variation in cholesterol than males. There exists gender and racial discrepancies in cholesterol which has been identified as lognormal and gamma probability distributions. White individuals seem to be at a higher risk of having high risk cholesterol level than blacks. Females tend to have higher variation in cholesterol level than males.

SRB1 as a new redox target of cigarette smoke in human sebocytes.

PubMed

Crivellari, Ilaria; Sticozzi, Claudia; Belmonte, Giuseppe; Muresan, Ximena M; Cervellati, Franco; Pecorelli, Alessandra; Cavicchio, Carlotta; Maioli, Emanuela; Zouboulis, Christos C; Benedusi, Mascia; Cervellati, Carlo; Valacchi, Giuseppe

2017-01-01

For its critical location, the skin represents the major interface between the body and the environment, therefore is one of the major biological barriers against the outdoor environmental stressors. Among the several oxidative environmental stressors, cigarette smoke (CS) has been associated with the development and worsening of many skin pathologies such as acne, dermatitis, delayed wound healing, aging and skin cancer. In our previous work we have demonstrated that CS is able to affect genes involved in skin cholesterol trafficking, among which SRB1, a receptor involved in the uptake of cholesterol from HDL, seems to be very susceptible to the oxidative stress induced by CS. In the present work we wanted to investigate the presence of SRB1 in human sebocytes and whether CS can affect cholesterol cellular uptake via the redox modulation of SRB1. By using a co-culture system of keratinocytes/sebocytes, we found that CS exposure induced a SRB1 protein loss without affecting sebocytes viability. The decrease of SRB1 levels was a consequence of SRB1/HNE adducts formation that leads to SRB1 ubiquitination and degradation. Moreover, the CS-induced loss of SRB1 induced an alteration of sebocytes lipid content, also demonstrated by cholesterol quantification in SRB1 siRNA experiments. In conclusion, exposure to CS, induced SRB1 post-translational modifications in sebocytes and this might affect sebocytes/skin functionality. Copyright © 2016 Elsevier Inc. All rights reserved.

ABCA1, ABCG1, and ABCG4 are distributed to distinct membrane meso-domains and disturb detergent-resistant domains on the plasma membrane.

PubMed

Sano, Osamu; Ito, Shiho; Kato, Reiko; Shimizu, Yuji; Kobayashi, Aya; Kimura, Yasuhisa; Kioka, Noriyuki; Hanada, Kentaro; Ueda, Kazumitsu; Matsuo, Michinori

2014-01-01

ATP-binding cassette A1 (ABCA1), ABCG1, and ABCG4 are lipid transporters that mediate the efflux of cholesterol from cells. To analyze the characteristics of these lipid transporters, we examined and compared their distributions and lipid efflux activity on the plasma membrane. The efflux of cholesterol mediated by ABCA1 and ABCG1, but not ABCG4, was affected by a reduction of cellular sphingomyelin levels. Detergent solubility and gradient density ultracentrifugation assays indicated that ABCA1, ABCG1, and ABCG4 were distributed to domains that were solubilized by Triton X-100 and Brij 96, resistant to Triton X-100 and Brij 96, and solubilized by Triton X-100 but resistant to Brij 96, respectively. Furthermore, ABCG1, but not ABCG4, was colocalized with flotillin-1 on the plasma membrane. The amounts of cholesterol extracted by methyl-β-cyclodextrin were increased by ABCA1, ABCG1, or ABCG4, suggesting that cholesterol in non-raft domains was increased. Furthermore, ABCG1 and ABCG4 disturbed the localization of caveolin-1 to the detergent-resistant domains and the binding of cholera toxin subunit B to the plasma membrane. These results suggest that ABCA1, ABCG1, and ABCG4 are localized to distinct membrane meso-domains and disturb the meso-domain structures by reorganizing lipids on the plasma membrane; collectively, these observations may explain the different substrate profiles and lipid efflux roles of these transporters.

Mobility of human immunodeficiency virus type 1 Pr55Gag in living cells.

PubMed

Gomez, Candace Y; Hope, Thomas J

2006-09-01

Human immunodeficiency virus type 1 (HIV-1) assembly requires the converging of thousands of structural proteins on cellular membranes to form a tightly packed immature virion. The Gag polyprotein contains all of the determinants important for viral assembly and must move around in the cell in order to form particles. This work has focused on Gag mobility in order to provide more insights into the dynamics of particle assembly. Key to these studies was the use of several fluorescently labeled Gag derivatives. We used fluorescence recovery after photobleaching as well as photoactivation to determine Gag mobility. Upon expression, Gag can be localized diffusely in the cytoplasm, associated with the plasma membrane, or in virus-like particles (VLPs). Here we show that Gag VLPs are primarily localized in the plasma membrane and do not colocalize with CD63. We have shown using full-length Gag as well as truncation mutants fused to green fluorescent protein that Gag is highly mobile in live cells when it is not assembled into VLPs. Results also showed that this mobility is highly dependent upon cholesterol. When cholesterol is depleted from cells expressing Gag, mobility is significantly decreased. Once cholesterol was replenished, Gag mobility returned to wild-type levels. Taken together, results from these mobility studies suggest that Gag is highly mobile and that as the assembly process proceeds, mobility decreases. These studies also suggest that Gag assembly must occur in cholesterol-rich domains in the plasma membrane.

The natural compound berberine positively affects macrophage functions involved in atherogenesis.

PubMed

Zimetti, F; Adorni, M P; Ronda, N; Gatti, R; Bernini, F; Favari, E

2015-02-01

We investigated the effect of berberine (BBR), an alkaloid showing antiatherogenic properties beyond the cholesterol lowering capacity, on macrophage cholesterol handling upon exposure to human serum and on macrophage responses to excess free cholesterol (FC) loading. Mouse and human macrophages were utilized as cellular models. Cholesterol content was measured by a fluorimetric assay; cholesterol efflux, cytotoxicity and membrane FC distribution were evaluated by radioisotopic assays. Monocyte chemotactic protein-1 (MCP-1) secretion was measured by ELISA; membrane ruffling and macropinocytosis were visualized by confocal microscopy. Exposure of cholesterol-enriched MPM to serum in the presence of 1 μM BBR resulted in a reduction of intracellular cholesterol content twice greater than exposure to serum alone (-52%; p < 0.01 and -21%; p < 0.05), an effect not mediated by an increase of cholesterol efflux, but rather by the inhibition of cholesterol uptake from serum. Consistently, BBR inhibited in a dose-dependent manner cholesterol accumulation in human macrophages exposed to hypercholesterolemic serum. Confocal microscope analysis revealed that BBR inhibited macropinocytosis, an independent-receptor process involved in LDL internalization. Macrophage FC-enrichment increased MCP-1 release by 1.5 folds, increased cytotoxicity by 2 fold, and induced membrane ruffling; all these responses were markedly inhibited by BBR. FC-enrichment led to an increase in plasma membrane cholesterol by 4.5 folds, an effect counteracted by BBR. We showed novel potentially atheroprotective activities of BBR in macrophages, consisting in the inhibition of serum-induced cholesterol accumulation, occurring at least in part through an impairment of macropinocytosis, and of FC-induced deleterious effects. Copyright © 2014 Elsevier B.V. All rights reserved.

Pathogens: raft hijackers.

PubMed

Mañes, Santos; del Real, Gustavo; Martínez-A, Carlos

2003-07-01

Throughout evolution, organisms have developed immune-surveillance networks to protect themselves from potential pathogens. At the cellular level, the signalling events that regulate these defensive responses take place in membrane rafts--dynamic microdomains that are enriched in cholesterol and glycosphingolipids--that facilitate many protein-protein and lipid-protein interactions at the cell surface. Pathogens have evolved many strategies to ensure their own survival and to evade the host immune system, in some cases by hijacking rafts. However, understanding the means by which pathogens exploit rafts might lead to new therapeutic strategies to prevent or alleviate certain infectious diseases, such as those caused by HIV-1 or Ebola virus.

Membrane Cholesterol Modulates Superwarfarin Toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marangoni, M. Natalia; Martynowycz, Michael W.; Kuzmenko, Ivan

Superwarfarins are modified analogs of warfarin with additional lipophilic aromatic rings, up to 100-fold greater potency, and longer biological half-lives. We hypothesized that increased hydrophobicity allowed interactions with amphiphilic membranes and modulation of biological responses. We find that superwarfarins brodifacoum and difenacoum increase lactate production and cell death in neuroblastoma cells. In contrast, neither causes changes in glioma cells that have higher cholesterol content. After choleterol depletion, lactate production was increased and cell viability was reduced. Drug-membrane interactions were examined by surface X-ray scattering using Langmuir monolayers of dipalmitoylphosphatidylcholine and/or cholesterol. Specular X-ray reflectivity data revealed that superwarfarins, but notmore » warfarin, intercalate between dipalmitoylphosphatidylcholine molecules, whereas grazing incidence X-ray diffraction demonstrated changes in lateral crystalline order of the film. Neither agent showed significant interactions with monolayers containing >20% cholesterol. These findings demonstrate an affinity of superwarfarins to biomembranes and suggest that cellular responses to these agents are regulated by cholesterol content.« less

The Lipid domain Phase diagram in a Dipalmitoyl-PC/Docosahaexnoic Acid-PE/Cholesterol System

NASA Astrophysics Data System (ADS)

Lor, Chai; Hirst, Linda

2011-03-01

Lipid domains in bilayer membrane and polyunsaturated fatty acids (PUFAs) are thought to play an important role in cellular activities. In particular, lipids containing docosahaexnoic acid are an interesting class of PUFAs due to their health benefits. In this project, we perform oxidation measurements of DHA-PE to determine the rate of oxidation in combination with antioxidants. A ternary diagram of DPPC/DHA-PE/cholesterol is mapped out to identify phase separation phenomena using atomic force microscope (AFM). Fluorescence microscopy is also used to image lipid domains in a flat bilayer with fluorescent labels. As expected, we observe the phase, shape, and size of lipid domains changes with varying composition. Moreover, we find that the roughness of the domains changes possibly due to overpacking of cholesterol in domains. This model study provides further understanding of the role of cholesterol in the bilayer membrane leading towards a better understanding of cell membranes. NSF award # DMR 0852791, ``CAREER: Self-Assembly of Polyunsaturated Lipids and Cholesterol In The Cell Membrane.''

Tripterygium regelii decreases the biosynthesis of triacylglycerol and cholesterol in HepG2 cells.

PubMed

Kang, Myung-Ji; Kwon, Eun-Bin; Yuk, Heung Joo; Ryu, Hyung Won; Kim, Soo-Yeon; Lee, Mi-Kyeong; Moon, Dong-Oh; Lee, Su Ui; Oh, Sei-Ryang; Lee, Hyun-Sun; Kim, Mun-Ock

2017-12-01

In the course of screening to find a plant material decreasing the activity of triacylglycerol and cholesterol, we identified Tripterygium regelii (TR). The methanol extract of TR leaves (TR-LM) was shown to reduce the intracellular lipid contents consisting of triacylglycerol (TG) and cholesterol in HepG2 cells. TR-LM also downregulated the mRNA and protein expression of the lipogenic genes such as SREBP-1 and its target enzymes. Consequently, TR-LM reduced the TG biosynthesis in HepG2 cells. In addition, TR-LM decreased SREBP2 and its target enzyme HMG-CoA reductase, which is involved in cholesterol synthesis. In this study, we evaluated that TR-LM attenuated cellular lipid contents through the suppression of de novo TG and cholesterol biosynthesis in HepG2 cells. All these taken together, TR-LM could be beneficial in regulating lipid metabolism and useful preventing the hyperlipidemia and its complications, in that liver is a crucial tissue for the secretion of serum lipids.

Step by Step: Eating To Lower Your High Blood Cholesterol. Revised.

ERIC Educational Resources Information Center

National Heart, Lung, and Blood Inst. (DHHS/NIH), Bethesda, MD.

This booklet offers advice for adults who want to lower their blood cholesterol level. The first section, "What You Need To Know about High Blood Cholesterol," discusses blood cholesterol and why it matters, what cholesterol numbers mean, and what affects blood cholesterol levels. Section 2, "What You Need To Do To Lower Blood…

Biphasic modulation of atherosclerosis induced by graded dietary copper supplementation in the cholesterol-fed rabbit

PubMed Central

LAMB, DAVID J; AVADES, TONY Y; FERNS, GORDON AA

2001-01-01

There has been considerable debate about how copper status may affect the biochemical and cellular processes associated with atherogenesis. We have investigated the effects of graded dietary copper supplementation on processes likely to contribute to atherogenesis, using the cholesterol-fed New Zealand White rabbit model. Rabbits (n = 40) were fed a 0.25–1% cholesterol diet deficient in copper. Animals received either 0, 1, 3 or 20 mg copper/day and were killed after 13 weeks. Plasma cholesterol levels were similar in each dietary group. Aortic concentrations of copper were higher in the 20 mg copper/day animals compared to those receiving 0 mg copper/day (3.70 ± 0.78 vs. 1.33 ± 0.46 µg/g wet tissue; P < 0.05). Aortic superoxide dismutase activity was higher in animals receiving 20 mg copper/day (323 ± 21 IU/mg tissue) compared to the other groups (187 ± 21; 239 ± 53; 201 ± 33 IU/mg tissue) (P > 0.05). En face staining of aortae with oil red O showed that both high copper supplementation (20 mg/day) (67.1 ± 5.5%) and a deficient diet (0 mg/day) (63.1 ± 4.8%) was associated with significantly larger lesions (P < 0.05) compared to moderately supplemented animals (1 mg/day and 3 mg/day) (51.3 ± 6.3 and 42.8 ± 7.9%). These data indicate that in the cholesterol-fed rabbit, there is an optimal dietary copper intake and that dietary copper deficiency or excess are associated with an increased susceptibility to aortic atherosclerosis. Many Western diets contain insufficient copper and these findings indicate that a moderate dietary copper content may confer a degree of cardiac protection to the human population. PMID:11703538

Differential Regulation of Gene Expression by Cholesterol Biosynthesis Inhibitors That Reduce (Pravastatin) or Enhance (Squalestatin 1) Nonsterol Isoprenoid Levels in Primary Cultured Mouse and Rat Hepatocytes

PubMed Central

Rondini, Elizabeth A.; Duniec-Dmuchowski, Zofia; Cukovic, Daniela; Dombkowski, Alan A.

2016-01-01

Squalene synthase inhibitors (SSIs), such as squalestatin 1 (SQ1), reduce cholesterol biosynthesis but cause the accumulation of isoprenoids derived from farnesyl pyrophosphate (FPP), which can modulate the activity of nuclear receptors, including the constitutive androstane receptor (CAR), farnesoid X receptor, and peroxisome proliferator-activated receptors (PPARs). In comparison, 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (e.g., pravastatin) inhibit production of both cholesterol and nonsterol isoprenoids. To characterize the effects of isoprenoids on hepatocellular physiology, microarrays were used to compare orthologous gene expression from primary cultured mouse and rat hepatocytes that were treated with either SQ1 or pravastatin. Compared with controls, 47 orthologs were affected by both inhibitors, 90 were affected only by SQ1, and 51 were unique to pravastatin treatment (P < 0.05, ≥1.5-fold change). When the effects of SQ1 and pravastatin were compared directly, 162 orthologs were found to be differentially coregulated between the two treatments. Genes involved in cholesterol and unsaturated fatty acid biosynthesis were up-regulated by both inhibitors, consistent with cholesterol depletion; however, the extent of induction was greater in rat than in mouse hepatocytes. SQ1 induced several orthologs associated with microsomal, peroxisomal, and mitochondrial fatty acid oxidation and repressed orthologs involved in cell cycle regulation. By comparison, pravastatin repressed the expression of orthologs involved in retinol and xenobiotic metabolism. Several of the metabolic genes altered by isoprenoids were inducible by a PPARα agonist, whereas cytochrome P450 isoform 2B was inducible by activators of CAR. Our findings indicate that SSIs uniquely influence cellular lipid metabolism and cell cycle regulation, probably due to FPP catabolism through the farnesol pathway. PMID:27225895

Phospholipid Transfer Protein Is Expressed in Cerebrovascular Endothelial Cells and Involved in High Density Lipoprotein Biogenesis and Remodeling at the Blood-Brain Barrier*

PubMed Central

Chirackal Manavalan, Anil Paul; Kober, Alexandra; Metso, Jari; Lang, Ingrid; Becker, Tatjana; Hasslitzer, Karin; Zandl, Martina; Fanaee-Danesh, Elham; Pippal, Jyotsna Brijesh; Sachdev, Vinay; Kratky, Dagmar; Stefulj, Jasminka; Jauhiainen, Matti; Panzenboeck, Ute

2014-01-01

Phospholipid transfer protein (PLTP) is a key protein involved in biogenesis and remodeling of plasma HDL. Several neuroprotective properties have been ascribed to HDL. We reported earlier that liver X receptor (LXR) activation promotes cellular cholesterol efflux and formation of HDL-like particles in an established in vitro model of the blood-brain barrier (BBB) consisting of primary porcine brain capillary endothelial cells (pBCEC). Here, we report PLTP synthesis, regulation, and its key role in HDL metabolism at the BBB. We demonstrate that PLTP is highly expressed and secreted by pBCEC. In a polarized in vitro model mimicking the BBB, pBCEC secreted phospholipid-transfer active PLTP preferentially to the basolateral (“brain parenchymal”) compartment. PLTP expression levels and phospholipid transfer activity were enhanced (up to 2.5-fold) by LXR activation using 24(S)-hydroxycholesterol (a cerebral cholesterol metabolite) or TO901317 (a synthetic LXR agonist). TO901317 administration elevated PLTP activity in BCEC from C57/BL6 mice. Preincubation of HDL3 with human plasma-derived active PLTP resulted in the formation of smaller and larger HDL particles and enhanced the capacity of the generated HDL particles to remove cholesterol from pBCEC by up to 3-fold. Pre-β-HDL, detected by two-dimensional crossed immunoelectrophoresis, was generated from HDL3 in pBCEC-derived supernatants, and their generation was markedly enhanced (1.9-fold) upon LXR activation. Furthermore, RNA interference-mediated PLTP silencing (up to 75%) reduced both apoA-I-dependent (67%) and HDL3-dependent (30%) cholesterol efflux from pBCEC. Based on these findings, we propose that PLTP is actively involved in lipid transfer, cholesterol efflux, HDL genesis, and remodeling at the BBB. PMID:24369175

Haemophilus parasuis encodes two functional cytolethal distending toxins: CdtC contains an atypical cholesterol recognition/interaction region.

PubMed

Zhou, Mingguang; Zhang, Qiang; Zhao, Jianping; Jin, Meilin

2012-01-01

Haemophilus parasuis is the causative agent of Glässer's disease of pigs, a disease associated with fibrinous polyserositis, polyarthritis and meningitis. We report here H. parasuis encodes two copies of cytolethal distending toxins (Cdts), which these two Cdts showed the uniform toxin activity in vitro. We demonstrate that three Cdt peptides can form an active tripartite holotoxin that exhibits maximum cellular toxicity, and CdtA and CdtB form a more active toxin than CdtB and CdtC. Moreover, the cellular toxicity is associated with the binding of Cdt subunits to cells. Further analysis indicates that CdtC subunit contains an atypical cholesterol recognition/interaction amino acid consensus (CRAC) region. The mutation of CRAC site resulted in decreased cell toxicity. Finally, western blot analysis show all the 15 H. parasuis reference strains and 109 clinical isolates expressed CdtB subunit, indicating that Cdt is a conservative putative virulence factor for H. parasuis. This is the first report of the molecular and cellular basis of Cdt host interactions in H. parasuis.

Potential of BODIPY-cholesterol for analysis of cholesterol transport and diffusion in living cells.

PubMed

Wüstner, Daniel; Lund, Frederik W; Röhrl, Clemens; Stangl, Herbert

2016-01-01

Cholesterol is an abundant and important lipid component of cellular membranes. Analysis of cholesterol transport and diffusion in living cells is hampered by the technical challenge of designing suitable cholesterol probes which can be detected for example by optical microscopy. One strategy is to use intrinsically fluorescent sterols, as dehydroergosterol (DHE), having minimal chemical alteration compared to cholesterol but giving low fluorescence signals in the UV region of the spectrum. Alternatively, one can use dye-tagged cholesterol analogs and in particular BODIPY-cholesterol (BChol), whose synthesis and initial characterization was pioneered by Robert Bittman. Here, we give a general overview of the properties and applications but also limitations of BODIPY-tagged cholesterol probes for analyzing intracellular cholesterol trafficking. We describe our own experiences and collaborative efforts with Bob Bittman for studying diffusion in the plasma membrane (PM) and uptake of BChol in a quantitative manner. For that purpose, we used a variety of fluorescence approaches including fluorescence correlation spectroscopy and its imaging variants, fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP). We also describe pulse-chase studies from the PM using BChol in direct comparison to DHE. Based on the gathered imaging data, we present a two-step kinetic model for sterol transport between PM and recycling endosomes. In addition, we highlight the suitability of BChol for determining transport of lipoprotein-derived sterol using electron microscopy (EM) and show that this approach ideally complements fluorescence studies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Blood biochemical and cellular changes during decompression and simulated extravehicular activity

NASA Technical Reports Server (NTRS)

Jauchem, J. R.; Waligora, J. M.; Johnson, P. C. Jr

1990-01-01

Blood biochemical and cellular parameters were measured in human subjects before and after exposure to a decompression schedule involving 6 h of oxygen prebreathing. The exposure was designed to simulate extravehicular activity for 6 h (subjects performed exercise while exposed to 29.6 kPa). There were no significant differences between blood samples from subjects who were susceptible (n = 11) versus those who were resistant (n = 27) to formation of venous gas emboli. Although several statistically significant (P less than 0.05) changes in blood parameters were observed following the exposure (increases in white blood cell count, prothrombin time, and total bilirubin, and decreases in triglycerides, very-low-density lipoprotein cholesterol, and blood urea nitrogen), the changes were small in magnitude and blood factor levels remained within normal clinical ranges. Thus, the decompression schedule used in this study is not likely to result in blood changes that would pose a threat to astronauts during extravehicular activity.

Nonlinear Associations between Plasma Cholesterol Levels and Neuropsychological Function

PubMed Central

Wendell, Carrington R.; Zonderman, Alan B.; Katzel, Leslie I.; Rosenberger, William F.; Plamadeala, Victoria V.; Hosey, Megan M.; Waldstein, Shari R.

2016-01-01

Objective Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery. Method Participants were 190 older adults (53% men, ages 54–83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed/dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as <70 vs. 70+) as an effect modifier. Results A significant quadratic effect of total cholesterol2 × age was identified for Logical Memory II (b=−.0013, p=.039), such that the 70+ group performed best at high and low levels of total cholesterol than at mid-range total cholesterol (U-shaped), and the <70 group performed worse at high and low levels of total cholesterol than at mid-range total cholesterol (inverted U-shape). Similarly, significant U- and J-shaped effects of LDL cholesterol2 × age were identified for Visual Reproduction II (b=−.0020, p=.026) and log of Trails B (b=.0001, p=.044). Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant. Conclusions Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. PMID:27280580

Characteristics of human hypo- and hyperresponders to dietary cholesterol.

PubMed

Katan, M B; Beynen, A C

1987-03-01

The characteristics of people whose serum cholesterol level is unusually susceptible to consumption of cholesterol were investigated. Thirty-two volunteers from the general population of Wageningen, the Netherlands, each participated in three controlled dietary trials in 1982. A low-cholesterol diet was fed during the first half and a high-cholesterol diet during the second half of each trial, and the change (response) of serum cholesterol was measured. The responses in the three trials were averaged to give each subject's mean responsiveness. Fecal excretion of cholesterol and its metabolites were measured in the second trial, and body cholesterol synthesis was calculated. Responsiveness showed a positive correlation with serum high density lipoprotein2 (HDL2) cholesterol (r = 0.41, p less than 0.05) and with serum total cholesterol level on a high-cholesterol diet (r = 0.31, p = 0.09). A negative relation was found with habitual cholesterol consumption (r = -0.62, p less than 0.01), with body mass index (r = -0.50, p less than 0.01), and with the rate of endogenous cholesterol synthesis (r = -0.40, p less than 0.05), but not with the reaction of endogenous cholesterol synthesis rate to an increased intake of cholesterol. No relation was found with age, sex, total caloric needs, or the ratio of primary to secondary fecal steroids. Upon multiple regression analysis, only habitual cholesterol intake and serum total and HDL2 cholesterol levels contributed significantly to the explanation of variance in responsiveness. Thus, a low habitual cholesterol intake, a high serum HDL2 cholesterol level, or a low body weight do not make one less susceptible to dietary cholesterol-induced hypercholesterolemia.

The Effect of Deployment on Cholesterol Levels of Active Duty Personnel

DTIC Science & Technology

2006-05-01

fairly good results regarding cholesterol levels. It was noted that several members returned from deployment with elevated levels, sometimes to the...LDL cholesterol and low HDL cholesterol (Downs, John R., Beere, Polly A., Whitney, Edwin, Clearfield, Michael, Weis, Stephen, Rochen, Jeffrey, Stein...specific ages, including cholesterol screenings beginning at age 25. Given the age of the majority of this population, one might expect relatively good

Regulation of Adaptive Immunity in Health and Disease by Cholesterol Metabolism

PubMed Central

Fessler, Michael B.

2015-01-01

Four decades ago, it was observed that stimulation of T cells induces rapid changes in cellular cholesterol that are required before proliferation can commence. Investigators returning to this phenomenon have finally revealed its molecular underpinnings. Cholesterol trafficking and its dysregulation are now also recognized to strongly influence dendritic cell function, T cell polarization, and antibody responses. In this review, the state of the literature is reviewed on how cholesterol and its trafficking regulate the cells of the adaptive immune response and in vivo disease phenotypes of dysregulated adaptive immunity, including allergy, asthma, and autoimmune disease. Emerging evidence supporting a potential role for statins and other lipid-targeted therapies in the treatment of these diseases is presented. Just as vascular biologists have embraced immunity in the pathogenesis and treatment of atherosclerosis, so should basic and clinical immunologists in allergy, pulmonology, and other disciplines seek to encompass a basic understanding of lipid science. PMID:26149587

Curcumin-loaded chitosan-cholesterol micelles: evaluation in monolayers and 3D cancer spheroid model.

PubMed

Muddineti, Omkara Swami; Kumari, Preeti; Ray, Eupa; Ghosh, Balaram; Biswas, Swati

2017-06-02

To improve the bioavailability and anticancer potential of curcumin by using a cholesterol-conjugated chitosan micelle. Methods & methods: Cholesterol was conjugated to chitosan (15 kDa) to form self-assembled micelles, which loaded curcumin. Physicochemical characterization and formulation optimization of the drug-loaded micelles (curcumin-loaded chitosan-cholesterol micelles [C-CCM]) were performed. In vitro cellular uptake and viability of C-CCM were investigated in melanoma and breast cancer cell lines. The antitumor efficacy was evaluated in 3D lung cancer spheroid model. The optimized C-CCM had size of approximately 162 nm with loading efficiency of approximately 36%. C-CCM was taken up efficiently by the cells, and it reduced cancer cell viability significantly compared with free curcumin. C-CCM enhanced the antitumor efficacy in spheroids, suggesting that C-CCM could be used as an effective chemotherapy in cancer.

Highlights of the Report of the Expert Panel on Blood Cholesterol Levels in Children and Adolescents.

ERIC Educational Resources Information Center

National Heart, Lung, and Blood Inst. (DHHS/NIH), Bethesda, MD.

Studies have shown that high blood cholesterol levels play a role in the development of coronary heart disease in adults, and that the process leading to atherosclerosis begins in childhood. To address the problem of high cholesterol levels in children, the Panel on Blood Cholesterol Levels recommends complementary approaches for individuals and…

Hypercholesterolemia is associated with hyperactive cardiac mTORC1 and mTORC2 signaling.

PubMed

Glazer, Hilary P; Osipov, Robert M; Clements, Richard T; Sellke, Frank W; Bianchi, Cesario

2009-06-01

Nutritional excess and hyperlipidemia increase the heart's susceptibility to ischemic injury. Mammalian target of rapamycin (mTOR) controls the cellular response to nutritional status and may play a role in ischemic injury. To explore the effect of hypercholesterolemia on cardiac mTOR signaling, we assessed mTOR signaling in hypercholesterolemic swine (HC) that are also susceptible to increased cardiac ischemia-reperfusion injury. Yucatan pigs were fed a high-fat/high-cholesterol diet for 4 weeks to induce hypercholesterolemia, and mTOR signaling was measured by immunoblotting and immunofluorescence in the non-ischemic left ventricular area. Total myocardial mTOR and raptor levels were markedly increased in the HC group compared to the normocholesterolemic group, and directly correlated with serum cholesterol levels. mTOR exhibited intense perinuclear staining in myocytes only in the HC group. Hypercholesterolemia was associated with hyperactive signaling upstream and downstream of both mTOR complexes, including myocardial Akt, S6K1, 4EBP1, S6 and PKC-alpha, increased levels of cardiac hypertrophy markers, and a trend toward lower levels of myocardial autophagy. Hypercholesterolemia can now be added to the growing list of conditions associated with aberrant mTOR signaling. Hypercholesterolemia produces a unique profile of alterations in cardiac mTOR signaling, which is a potential target in cardiac diseases associated with hypercholesterolemia and nutritional excess.

Glycemic control and high-density lipoprotein characteristics in adolescents with type 1 diabetes.

PubMed

Medina-Bravo, Patricia; Medina-Urrutia, Aída; Juárez-Rojas, Juan Gabriel; Cardoso-Saldaña, Guillermo; Jorge-Galarza, Esteban; Posadas-Sánchez, Rosalinda; Coyote-Estrada, Ninel; Nishimura-Meguro, Elisa; Posadas-Romero, Carlos

2013-09-01

Recent evidence suggests that high-density lipoprotein (HDL) physicochemical characteristics and functional capacity may be more important that HDL-C levels in predicting coronary heart disease. There is little data regarding HDL subclasses distribution in youth with type 1 diabetes. To assess the relationships between glycemic control and HDL subclasses distribution, composition, and function in adolescents with type 1 diabetes. This cross-sectional study included 52 adolescents with type 1 diabetes aged 12-16 years and 43 age-matched non-diabetic controls. Patients were divided into two groups: one in fair control [hemoglobin A1c (HbA1c) < 9.6%] and the second group with poor glycemic control (HbA1c ≥ 9.6%). In all participants, we determined HDL subclasses distribution, composition, and the ability of plasma and of isolated HDL to promote cellular cholesterol efflux. Levels of soluble adhesion molecules were also measured. Although both groups of patients and the control group had similar HDL-C levels, linear regression analyses showed that compared with non-diabetic subjects, the poor control group had a lower proportion of HDL2b subclass (p = 0.029), triglyceride enriched (p = 0.045), and cholesteryl ester depleted (p = 0.028) HDL particles. Despite these HDL changes, cholesterol efflux was comparable among the three groups. The poor control group also had significantly higher intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 plasma concentrations. In adolescents with type 1 diabetes, poor glycemic control is associated with abnormalities in HDL subclasses distribution and HDL lipid composition, however, in spite of these HDL changes, the ability of HDL to promote cholesterol efflux remains comparable to that of healthy subjects. © 2012 John Wiley & Sons A/S.

Phytosterol and cholesterol precursor levels indicate increased cholesterol excretion and biosynthesis in gallstone disease.

PubMed

Krawczyk, Marcin; Lütjohann, Dieter; Schirin-Sokhan, Ramin; Villarroel, Luis; Nervi, Flavio; Pimentel, Fernando; Lammert, Frank; Miquel, Juan Francisco

2012-05-01

In hepatocytes and enterocytes sterol uptake and secretion is mediated by Niemann-Pick C1-like 1 (NPC1L1) and ATP-binding cassette (ABC)G5/8 proteins, respectively. Whereas serum levels of phytosterols represent surrogate markers for intestinal cholesterol absorption, cholesterol precursors reflect cholesterol biosynthesis. Here we compare serum and biliary sterol levels in ethnically different populations of patients with gallstone disease (GSD) and stone-free controls to identify differences in cholesterol transport and synthesis between these groups. In this case-control study four cohorts were analyzed: 112 German patients with GSD and 152 controls; two distinct Chilean ethnic groups: Hispanics (100 GSD, 100 controls), and Amerindians (20 GSD, 20 controls); additionally an 8-year follow-up of 70 Hispanics was performed. Serum sterols were measured by gas chromatography / mass spectrometry. Gallbladder bile sterol levels were analyzed in cholesterol GSD and controls. Common ABCG5/8 variants were genotyped. Comparison of serum sterols showed lower levels of phytosterols and higher levels of cholesterol precursors in GSD patients than in controls. The ratios of phytosterols to cholesterol precursors were lower in GSD patients, whereas biliary phytosterol and cholesterol concentrations were elevated as compared with controls. In the follow-up study, serum phytosterol levels were significantly lower even before GSD was detectable by ultrasound. An ethnic gradient in the ratios of phytosterols to cholesterol precursors was apparent (Germans > Hispanics > Amerindians). ABCG5/8 variants did not fully explain the sterol metabolic trait of GSD in any of the cohorts. Individuals predisposed to GSD display increased biliary output of cholesterol in the setting of relatively low intestinal cholesterol absorption, indicating enhanced whole-body sterol clearance. This metabolic trait precedes gallstone formation and is a feature of ethnic groups at higher risk of cholesterol GSD. Copyright © 2012 American Association for the Study of Liver Diseases.

Docosahexaenoic acid modifies the clustering and size of lipid rafts and the lateral organization and surface expression of MHC class I of EL4 cells.

PubMed

Shaikh, Saame Raza; Rockett, Benjamin Drew; Salameh, Muhammad; Carraway, Kristen

2009-09-01

An emerging molecular mechanism by which docosahexaenoic acid (DHA) exerts its effects is modification of lipid raft organization. The biophysical model, based on studies with liposomes, shows that DHA avoids lipid rafts because of steric incompatibility between DHA and cholesterol. The model predicts that DHA does not directly modify rafts; rather, it incorporates into nonrafts to modify the lateral organization and/or conformation of membrane proteins, such as the major histocompatibility complex (MHC) class I. Here, we tested predictions of the model at a cellular level by incorporating oleic acid, eicosapentaenoic acid (EPA), and DHA, compared with a bovine serum albumin (BSA) control, into the membranes of EL4 cells. Quantitative microscopy showed that DHA, but not EPA, treatment, relative to the BSA control diminished lipid raft clustering and increased their size. Approximately 30% of DHA was incorporated directly into rafts without changing the distribution of cholesterol between rafts and nonrafts. Quantification of fluorescence colocalization images showed that DHA selectively altered MHC class I lateral organization by increasing the fraction of the nonraft protein into rafts compared with BSA. Both DHA and EPA treatments increased antibody binding to MHC class I compared with BSA. Antibody titration showed that DHA and EPA did not change MHC I conformation but increased total surface levels relative to BSA. Taken together, our findings are not in agreement with the biophysical model. Therefore, we propose a model that reconciles contradictory viewpoints from biophysical and cellular studies to explain how DHA modifies lipid rafts on several length scales. Our study supports the notion that rafts are an important target of DHA's mode of action.

Nonlinear associations between plasma cholesterol levels and neuropsychological function.

PubMed

Wendell, Carrington R; Zonderman, Alan B; Katzel, Leslie I; Rosenberger, William F; Plamadeala, Victoria V; Hosey, Megan M; Waldstein, Shari R

2016-11-01

Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery. Participants were 190 older adults (53% men, ages 54-83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed and dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as <70 vs. 70+) as an effect modifier. A significant quadratic effect of Total Cholesterol² × Age was identified for Logical Memory II ( b = -.0013, p = .039), such that the 70+ group performed best at high and low levels of total cholesterol than at midrange total cholesterol (U-shaped) and the <70 group performed worse at high and low levels of total cholesterol than at midrange total cholesterol (inverted U shape). Similarly, significant U- and J-shaped effects of LDL Cholesterol² × Age were identified for Visual Reproduction II ( b = -.0020, p = .026) and log of the Trail Making Test, Part B (b = .0001, p = .044). Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant. Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Cholesterol as a Causative Factor in Alzheimer Disease: A Debatable Hypothesis

PubMed Central

Wood, W. Gibson; Li, Ling; Müller, Walter E.; Eckert, Gunter P.

2014-01-01

High serum/plasma cholesterol levels have been suggested as a risk factor for Alzheimer disease (AD). Some reports, mostly retrospective epidemiological studies, have observed a decreased prevalence of AD in patients taking the cholesterol lowering drugs, statins. The strongest evidence causally linking cholesterol to AD is provided by experimental studies showing that adding/reducing cholesterol alters amyloid precursor protein (APP) and amyloid beta-protein (Aβ) levels. However, there are problems with the cholesterol-AD hypothesis. Cholesterol levels in serum/plasma and brain of AD patients do not support cholesterol as a causative factor in AD. Prospective studies on statins and AD have largely failed to show efficacy. Even the experimental data are open to interpretation given that it is well-established that modification of cholesterol levels has effects on multiple proteins, not only APP and Aβ. The purpose of this review, therefore, is to examine the above-mentioned issues and discuss the pros and cons of the cholesterol-AD hypothesis, and the involvement of other lipids in the mevalonate pathway, such as isoprenoids and oxysterols, in AD. PMID:24329875

BMI, body fat mass and plasma leptin level in relation to cardiovascular diseases risk factors among adolescents in Taitung.

PubMed

Wu, Ya-Ke; Chu, Nain-Feng; Huang, Ya-Hsien; Syu, Jhu-Ting; Chang, Jin-Biou

2016-01-01

To investigate the risk factors associated with cardiovascular diseases and its relation to BMI, body fat mass and plasma leptin level among adolescents in Taitung, Taiwan. A cross-sectional Taitung Children Heart Study for 500 young adolescents between ages 13 and 15 was conducted. Gender-specific regression models were used to determine the associations between BMI, percentage of body fat mass, plasma leptin level and seven CVDs risk factors (systolic and diastolic blood pressure, mean arterial pressure, triglycerides, total cholesterol, HDL-cholesterol and LDL-cholesterol) before and after adjusting for weight status and age. After adjusting for weight status and age, BMI was positively associated with systolic BP, triglycerides, LDL-cholesterol levels but negatively associated with HDL-cholesterol level in boys while positively associated with systolic and diastolic BP, mean arterial pressure, and LDL-cholesterol level in girls. The percentage of body fat mass was positively associated with triglycerides, total cholesterol, and LDL-cholesterol in boys while positively associated with systolic BP, total cholesterol, and LDL-cholesterol in girls. Plasma leptin was positively associated with triglycerides, total cholesterol and LDL-cholesterol in boys but no statistically significant associations with CVDs risk factors in girls. A strong relationship between the percentage of body fat mass and plasma leptin appeared among all participants (r=0.59, p<0.01). BMI, body fat mass and plasma leptin level may be used to identify certain CVDs risk factors among Taitung adolescents. Future researches could consider measuring body fat mass in the relationship of CVDs risk factors instead of plasma leptin among young adolescents. Copyright © 2015 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

Localization of ABCG5 and ABCG8 proteins in human liver, gall bladder and intestine

PubMed Central

Klett, Eric L; Lee, Mi-Hye; Adams, David B; Chavin, Kenneth D; Patel, Shailendra B

2004-01-01

Background The molecular mechanisms that regulate the entry of dietary sterols into the body and their removal via hepatobiliary secretion are now beginning to be defined. These processes are specifically disrupted in the rare autosomal recessive disease, Sitosterolemia (MIM 210250). Mutations in either, but not both, of two genes ABCG5 or ABCG8, comprising the STSL locus, are now known to cause this disease and their protein products are proposed to function as heterodimers. Under normal circumstances cholesterol, but not non-cholesterol sterols, is preferentially absorbed from the diet. Additionally, any small amounts of non-cholesterol sterols that are absorbed are rapidly taken up by the liver and preferentially excreted into bile. Based upon the defects in sitosterolemia, ABCG5 and ABCG8 serve specifically to exclude non-cholesterol sterol entry at the intestinal level and are involved in sterol excretion at the hepatobiliary level. Methods Here we report the biochemical and immuno-localization of ABCG5 and ABCG8 in human liver, gallbladder and intestine using cell fractionation and immunohistochemical analyses. Results We raised peptide antibodies against ABCG5 and ABCG8 proteins. Using human liver samples, cell fractionation studies showed both proteins are found in membrane fractions, but they did not co-localize with caveolin-rafts, ER, Golgi or mitochondrial markers. Although their distribution in the sub-fractions was similar, they were not completely contiguous. Immunohistochemical analyses showed that while both proteins were readily detectable in the liver, ABCG5 was found predominately lining canalicular membranes, whereas ABCG8 was found in association with bile duct epithelia. At the cellular level, ABCG5 appeared to be apically expressed, whereas ABCG8 had a more diffuse expression pattern. Both ABCG5 and ABCG8 appeared to localize apically as shown by co-localization with MRP2. The distribution patterns of ABCG5 and ABCG8 in the gallbladder were very similar to each other. In the small intestine both ABCG5 and ABCG8 appear to line the brush border. However, at the level of the enterocyte, the cellular distribution patterns of ABCG5 and ABCG8 differed, such that ABCG5 was more diffuse, but ABCG8 was principally apical. Using standard deglycosylation methods, ABCG5 and ABCG8 do not appear to be glycosylated, suggesting a difference between human and mouse proteins. Conclusion We report the distribution patterns of ABCG5 and ABCG8 in human tissues. Cell fractionation studies showed that both proteins co-fractionated in general, but could also be found independent of each other. As predicted, they are expressed apically in both intestine and liver, although their intracellular expression patterns are not completely congruent. These studies support the concept of heterodimerization of ABCG5 and ABCG8, but also support the notion that these proteins may have an independent function. PMID:15383151

Sulforaphane Protects against High Cholesterol-Induced Mitochondrial Bioenergetics Impairments, Inflammation, and Oxidative Stress and Preserves Pancreatic β-Cells Function.

PubMed

Carrasco-Pozo, Catalina; Tan, Kah Ni; Gotteland, Martin; Borges, Karin

2017-01-01

Cholesterol plays an important role in inducing pancreatic β -cell dysfunction, leading to an impaired insulin secretory response to glucose. This study aimed to determine the protective effects of sulforaphane, a natural isothiocyanate Nrf2-inducer, against cholesterol-induced pancreatic β -cells dysfunction, through molecular and cellular mechanisms involving mitochondrial bioenergetics. Sulforaphane prevented cholesterol-induced alterations in the coupling efficiency of mitochondrial respiration, improving ATP turnover and spare capacity, and averted the impairment of the electron flow at complexes I, II, and IV. Sulforaphane also attenuated the cholesterol-induced activation of the NF κ B pathway, normalizing the expression of pro- and anti-inflammatory cytokines. In addition, it also inhibited the decrease in sirtuin 1 expression and greatly increased Pgc-1α expression in Min6 cells. Sulforaphane increased the expression of antioxidant enzymes downstream of the Nrf2 pathway and prevented lipid peroxidation induced by cholesterol. The antioxidant and anti-inflammatory properties of sulforaphane and its ability to protect and improve mitochondrial bioenergetic function contribute to its protective action against cholesterol-induced pancreatic β -cell dysfunction. Our data provide a scientifically tested foundation upon which sulforaphane can be developed as nutraceutical to preserve β -cell function and eventually control hyperglycemia.

Sulforaphane Protects against High Cholesterol-Induced Mitochondrial Bioenergetics Impairments, Inflammation, and Oxidative Stress and Preserves Pancreatic β-Cells Function

PubMed Central

Tan, Kah Ni; Gotteland, Martin

2017-01-01

Cholesterol plays an important role in inducing pancreatic β-cell dysfunction, leading to an impaired insulin secretory response to glucose. This study aimed to determine the protective effects of sulforaphane, a natural isothiocyanate Nrf2-inducer, against cholesterol-induced pancreatic β-cells dysfunction, through molecular and cellular mechanisms involving mitochondrial bioenergetics. Sulforaphane prevented cholesterol-induced alterations in the coupling efficiency of mitochondrial respiration, improving ATP turnover and spare capacity, and averted the impairment of the electron flow at complexes I, II, and IV. Sulforaphane also attenuated the cholesterol-induced activation of the NFκB pathway, normalizing the expression of pro- and anti-inflammatory cytokines. In addition, it also inhibited the decrease in sirtuin 1 expression and greatly increased Pgc-1α expression in Min6 cells. Sulforaphane increased the expression of antioxidant enzymes downstream of the Nrf2 pathway and prevented lipid peroxidation induced by cholesterol. The antioxidant and anti-inflammatory properties of sulforaphane and its ability to protect and improve mitochondrial bioenergetic function contribute to its protective action against cholesterol-induced pancreatic β-cell dysfunction. Our data provide a scientifically tested foundation upon which sulforaphane can be developed as nutraceutical to preserve β-cell function and eventually control hyperglycemia. PMID:28386307

Dyslipidemia and dementia: current epidemiology, genetic evidence and mechanisms behind the associations

PubMed Central

Reitz, Christiane

2013-01-01

The role of cholesterol in the etiology of Alzheimer’s disease (AD) is still controversial. Some studies aiming to explore the association between lipids and/or lipid lowering treatment and AD indicate a harmful effect of dyslipidemia and a beneficial effect of statin therapy on AD risk. The findings are supported by genetic linkage and association studies that have clearly identified several genes involved in cholesterol metabolism or transport as AD susceptibility genes, including Apolipoprotein E (APOE), Apolipoprotein J (APOJ, CLU) and the sortilin-related receptor (SORL1). Functional cell biology studies support a critical involvement of lipid raft cholesterol in the modulation of AbetaPP processing by β- and γ-secretase resulting in altered Aβ production. Contradictory evidence comes from epidemiological studies showing no or controversial association between dyslipidemia and AD risk, cell biology studies suggesting that there is little exchange between circulating and brain cholesterol, that increased membrane cholesterol is protective by inhibiting loss of membrane integrity through amyloid cytotoxicity, and that cellular cholesterol inhibits co-localization of BACE1 and AbetaPP in non-raft membrane domains and thereby increasing generation of plasmin, an Aβ-degrading enzyme. The aim of this review is to summarize the findings of epidemiologic and cell biologic studies aiming to elucidate the role of cholesterol in AD etiology. PMID:21965313

Potential Mechanisms Leading to the Abnormal Lipid Profile in Patients With Rheumatoid Arthritis Versus Healthy Volunteers and Reversal by Tofacitinib†, ‡

PubMed Central

Fleischmann, Roy; Davignon, Jean; Schwartz, Howard; Turner, Scott M.; Beysen, Carine; Milad, Mark; Hellerstein, Marc K.; Luo, Zhen; Kaplan, Irina V.; Riese, Richard; Zuckerman, Andrea; McInnes, Iain B.

2015-01-01

Objective Tofacitinib is an oral JAK inhibitor for the treatment of rheumatoid arthritis (RA). Systemic inflammation is proposed to play a fundamental role in the altered lipid metabolism associated with RA; however, the underlying mechanisms are unknown. We undertook this study to compare cholesterol and lipoprotein kinetics in patients with active RA with those in matched healthy volunteers. Methods This was a phase I open‐label mechanism‐of‐action study. Cholesterol and lipoprotein kinetics were assessed with 13C‐cholesterol and 13C‐leucine infusions. RA patients were reevaluated after receiving oral tofacitinib 10 mg twice daily for 6 weeks. Results Levels of high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, total cholesterol, and apolipoprotein A‐I (Apo A‐I) as well as HDL cholesterol particle number were lower in RA patients (n = 36) than in healthy volunteers (n = 33). In contrast, the cholesterol ester fractional catabolic rate was higher in RA patients, but no differences were observed in cholesterol ester transfer protein, cholesterol ester production rate, HDL‐associated Apo A‐I fractional catabolic rate, or LDL‐associated Apo B fractional catabolic rate. Following tofacitinib treatment in RA patients, the cholesterol ester fractional catabolic rate decreased and cholesterol levels increased. The decrease in cholesterol ester fractional catabolic rate correlated significantly with the increase in HDL cholesterol. Additionally, HDL cholesterol particle number increased and markers of HDL cholesterol function improved. Conclusion This is the first study to assess cholesterol and lipoprotein kinetics in patients with active RA and matched healthy volunteers. The data suggest that low cholesterol levels in patients with active RA may be driven by increases in cholesterol ester catabolism. Tofacitinib treatment reduced cholesterol ester catabolism, thereby increasing cholesterol levels toward those in healthy volunteers, and markers of antiatherogenic HDL function improved. PMID:25470338

Effects of Yogurt Containing Fermented Pepper Juice on the Body Fat and Cholesterol Level in High Fat and High Cholesterol Diet Fed Rat.

PubMed

Yeon, Su-Jung; Hong, Go-Eun; Kim, Chang-Kyu; Park, Woo Joon; Kim, Soo-Ki; Lee, Chi-Ho

2015-01-01

This experiment investigated whether yogurt containing fermented pepper juice (FPJY) affects cholesterol level in high fat and high cholesterol diet (HFCD) fed rat. Twenty five Sprague-Dawley male rats of 7 wk were divided into 5 groups, and fed following diets for 9 wk; CON (control diet), HFCD (HFCD), PY (HFCD supplemented with 2% of plain yogurt), LFY (HFCD supplemented with 2% of FPJY), and HFY (HFCD supplemented with 5% of FPJY). In the LFY group, hepatic total lipid level decreased significantly compared to the HFCD group (p<0.05). Serum HDL cholesterol level tended to increase and hepatic total cholesterol level decreased and were comparable to the CON group (p>0.05). In HFY group, body weight and hepatic total lipid level significantly decreased over the HFCD group (p<0.05). Serum and hepatic total cholesterol level, kidney, and body fat weights decreased, and were compared to the CON group (p>0.05). Liver weight decreased as FPJY content was increased. Results suggested FPJY would inhibit organ hypertrophy and accumulation of body fat, hepatic lipid, and cholesterol in HFCD fed rat.

Synthesis and validation of novel cholesterol-based fluorescent lipids designed to observe the cellular trafficking of cationic liposomes.

PubMed

Kim, Bieong-Kil; Seu, Young-Bae; Choi, Jong-Soo; Park, Jong-Won; Doh, Kyung-Oh

2015-09-15

Cholesterol-based fluorescent lipids with ether linker were synthesized using NBD (Chol-E-NBD) or Rhodamine B (Chol-E-Rh), and the usefulnesses as fluorescent probes for tracing cholesterol-based liposomes were validated. The fluorescent intensities of liposomes containing these modified lipids were measured and observed under a microscope. Neither compound interfered with the expression of GFP plasmid, and live cell images were obtained without interferences. Changes in the fluorescent intensity of liposomes containing Chol-E-NBD were followed by flow cytometry for up to 24h. These fluorescent lipids could be useful probes for trafficking of cationic liposome-mediated gene delivery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Genomic Evidence that Methanotrophic Endosymbionts Likely Provide Deep-Sea Bathymodiolus Mussels with a Sterol Intermediate in Cholesterol Biosynthesis

PubMed Central

Takaki, Yoshihiro; Chikaraishi, Yoshito; Ikuta, Tetsuro; Ozawa, Genki; Yoshida, Takao; Ohkouchi, Naohiko; Fujikura, Katsunori

2017-01-01

Sterols are key cyclic triterpenoid lipid components of eukaryotic cellular membranes, which are synthesized through complex multi-enzyme pathways. Similar to most animals, Bathymodiolus mussels, which inhabit deep-sea chemosynthetic ecosystems and harbor methanotrophic and/or thiotrophic bacterial endosymbionts, possess cholesterol as their main sterol. Based on the stable carbon isotope analyses, it has been suggested that host Bathymodiolus mussels synthesize cholesterol using a sterol intermediate derived from the methanotrophic endosymbionts. To test this hypothesis, we sequenced the genome of the methanotrophic endosymbiont in Bathymodiolus platifrons. The genome sequence data demonstrated that the endosymbiont potentially generates up to 4,4-dimethyl-cholesta-8,14,24-trienol, a sterol intermediate in cholesterol biosynthesis, from methane. In addition, transcripts for a subset of the enzymes of the biosynthetic pathway to cholesterol downstream from a sterol intermediate derived from methanotroph endosymbionts were detected in our transcriptome data for B. platifrons. These findings suggest that this mussel can de novo synthesize cholesterol from methane in cooperation with the symbionts. By in situ hybridization analyses, we showed that genes associated with cholesterol biosynthesis from both host and endosymbionts were expressed exclusively in the gill epithelial bacteriocytes containing endosymbionts. Thus, cholesterol production is probably localized within these specialized cells of the gill. Considering that the host mussel cannot de novo synthesize cholesterol and depends largely on endosymbionts for nutrition, the capacity of endosymbionts to synthesize sterols may be important in establishing symbiont–host relationships in these chemosynthetic mussels. PMID:28453654

Sterol Regulation of Voltage-Gated K+ Channels.

PubMed

Balajthy, Andras; Hajdu, Peter; Panyi, Gyorgy; Varga, Zoltan

2017-01-01

Cholesterol is an essential lipid building block of the cellular plasma membrane. In addition to its structural role, it regulates the fluidity and raft structure of the membrane and influences the course of numerous membrane-linked signaling pathways and the function of transmembrane proteins, including ion channels. This is supported by a vast body of scientific data, which demonstrates the modulation of ion channels with a great variety of ion selectivity, gating, and tissue distribution by changes in membrane cholesterol. Here, we review what is currently known about the modulation of voltage-gated K + (Kv) channels by changes in membrane cholesterol content, considering raft association of the channels, the roles of cholesterol recognition sites, and those of adaptor proteins in cholesterol-Kv channel interactions. We specifically focus on Kv1.3, the dominant K + channel of human T cells. Effects of cholesterol depletion and enrichment and 7-dehydrocholesterol enrichment on Kv1.3 gating are discussed in the context of the immunological synapse and the comparison of the in vitro effects of sterol modifications on Kv1.3 function with ex vivo effects on cells from hypercholesterolemic and Smith-Lemli-Opitz patients. © 2017 Elsevier Inc. All rights reserved.

An optimized method for measuring fatty acids and cholesterol in stable isotope-labeled cells

PubMed Central

Argus, Joseph P.; Yu, Amy K.; Wang, Eric S.; Williams, Kevin J.; Bensinger, Steven J.

2017-01-01

Stable isotope labeling has become an important methodology for determining lipid metabolic parameters of normal and neoplastic cells. Conventional methods for fatty acid and cholesterol analysis have one or more issues that limit their utility for in vitro stable isotope-labeling studies. To address this, we developed a method optimized for measuring both fatty acids and cholesterol from small numbers of stable isotope-labeled cultured cells. We demonstrate quantitative derivatization and extraction of fatty acids from a wide range of lipid classes using this approach. Importantly, cholesterol is also recovered, albeit at a modestly lower yield, affording the opportunity to quantitate both cholesterol and fatty acids from the same sample. Although we find that background contamination can interfere with quantitation of certain fatty acids in low amounts of starting material, our data indicate that this optimized method can be used to accurately measure mass isotopomer distributions for cholesterol and many fatty acids isolated from small numbers of cultured cells. Application of this method will facilitate acquisition of lipid parameters required for quantifying flux and provide a better understanding of how lipid metabolism influences cellular function. PMID:27974366

Effects of cholesterol on plasma membrane lipid order in MCF-7 cells by two-photon microscopy

NASA Astrophysics Data System (ADS)

Zeng, Yixiu; Chen, Jianling; Yang, Hongqin; Wang, Yuhua; Li, Hui; Xie, Shusen

2014-09-01

Lipid rafts are cholesterol- and glycosphingolipids- enriched microdomains on plasma membrane surface of mammal cells, involved in a variety of cellular processes. Depleting cholesterol from the plasma membrane by drugs influences the trafficking of lipid raft markers. Optical imaging techniques are powerful tools to study lipid rafts in live cells due to its noninvasive feature. In this study, breast cancer cells MCF-7 were treated with different concentrations of MβCD to deplete cholesterol and an environmentally sensitive fluorescence probe, Laurdan was loaded to image lipid order by two-photon microscopy. The generalized polarization (GP) values were calculated to distinguish the lipid order and disorder phase. GP images and GP distributions of native and cholesterol-depleted MCF-7 cells were obtained. Our results suggest that even at low concentration (0.5 mM) of MβCD, the morphology of the MCF-7 cells changes. Small high GP areas (lipid order phase) decrease more rapidly than low GP areas (lipid disorder phase), indicating that lipid raft structure was altered more severely than nonraft domains. The data demonstrates that cholesterol dramatically affect raft coverage and plasma membrane fluidity in living cells.

Cholesterol-directed nanoparticle assemblies based on single amino acid peptide mutations activate cellular uptake and decrease tumor volume† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc02616a Click here for additional data file.

PubMed Central

Li, Shang; Zou, Rongfeng; Tu, Yaoquan

2017-01-01

Peptide drugs have been difficult to translate into effective therapies due to their low in vivo stability. Here, we report a strategy to develop peptide-based therapeutic nanoparticles by screening a peptide library differing by single-site amino acid mutations of lysine-modified cholesterol. Certain cholesterol-modified peptides are found to promote and stabilize peptide α-helix formation, resulting in selectively cell-permeable peptides. One cholesterol-modified peptide self-assembles into stable nanoparticles with considerable α-helix propensity stabilized by intermolecular van der Waals interactions between inter-peptide cholesterol molecules, and shows 68.3% stability after incubation with serum for 16 h. The nanoparticles in turn interact with cell membrane cholesterols that are disproportionately present in cancer cell membranes, inducing lipid raft-mediated endocytosis and cancer cell death. Our results introduce a strategy to identify peptide nanoparticles that can effectively reduce tumor volumes when administered to in in vivo mice models. Our results also provide a simple platform for developing peptide-based anticancer drugs. PMID:29163910

Cholesterol Hydroperoxide Generation, Translocation, and Reductive Turnover in Biological Systems.

PubMed

Girotti, Albert W; Korytowski, Witold

2017-12-01

Cholesterol is like other unsaturated lipids in being susceptible to peroxidative degradation upon exposure to strong oxidants like hydroxyl radical or peroxynitrite generated under conditions of oxidative stress. In the eukaryotic cell plasma membrane, where most of the cellular cholesterol resides, peroxidation leads to membrane structural and functional damage from which pathological states may arise. In low density lipoprotein, cholesterol and phospholipid peroxidation have long been associated with atherogenesis. Among the many intermediates/products of cholesterol oxidation, hydroperoxide species (ChOOHs) have a number of different fates and deserve special attention. These fates include (a) damage-enhancement via iron-catalyzed one-electron reduction, (b) damage containment via two-electron reduction, and (c) inter-membrane, inter-lipoprotein, and membrane-lipoprotein translocation, which allows dissemination of one-electron damage or off-site suppression thereof depending on antioxidant location and capacity. In addition, ChOOHs can serve as reliable and conveniently detected mechanistic reporters of free radical-mediated reactions vs. non-radical (e.g., singlet oxygen)-mediated reactions. Iron-stimulated peroxidation of cholesterol and other lipids underlies a newly discovered form of regulated cell death called ferroptosis. These and other deleterious consequences of radical-mediated lipid peroxidation will be discussed in this review.

Correlation between plasma component levels of cultured fish and resistance to bacterial infection

USGS Publications Warehouse

Maita, M.; Satoh, K.-I.; Fukuda, Y.; Lee, H.-K.; Winton, J.R.; Okamoto, N.

1998-01-01

Mortalities of yellowtail Seriola quinqueradiata artificially infected with Lactococcus garvieae and of rainbow trout Oncorhynchus mykiss artificially infected with Vibrio anguillarum were compared with the levels of plasma components measured prior to challenge. The levels of plasma total cholesterol, free cholesterol and phospholipid of fish surviving infection were significantly higher in both yellowtail and rainbow trout than those of fish which died during the challenge test. Mortality of yellowtail with plasma total cholesterol levels lower than 250 mg/100 ml was significantly higher than that of fish which had cholesterol levels higher than 275 mg/100 ml (p < 0.05). Rainbow trout whose cholesterol was lower than 520 mg/100 ml suffered a significantly higher mortality due to vibriosis than fish having cholesterol levels higher than 560 mg/100 ml (p < 0.005). These results indicate that low levels of plasma lipid components may be an indicator of lowered disease resistance in cultured fish.

Hypocholesterolemia is an independent risk factor for depression disorder and suicide attempt in Northern Mexican population.

PubMed

Segoviano-Mendoza, Marcela; Cárdenas-de la Cruz, Manuel; Salas-Pacheco, José; Vázquez-Alaniz, Fernando; La Llave-León, Osmel; Castellanos-Juárez, Francisco; Méndez-Hernández, Jazmín; Barraza-Salas, Marcelo; Miranda-Morales, Ernesto; Arias-Carrión, Oscar; Méndez-Hernández, Edna

2018-01-15

Cholesterol has been associated as a risk factor for cardiovascular disease. Recently, however, there is growing evidence about crucial requirement of neuron membrane cholesterol in the organization and function of the 5-HT 1A serotonin receptor. For this, low cholesterol level has been reported to be associated with depression and suicidality. However there have been inconsistent reports about this finding and the exact relationship between these factors remains controversial. Therefore, we investigated the link between serum cholesterol and its fractions with depression disorder and suicide attempt in 467 adult subjects in Mexican mestizo population. Plasma levels of total cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-c) and low density lipoprotein cholesterol (LDL-c) were determined in 261 MDD patients meeting the DSM-5 criteria for major depressive disorder (MDD), 59 of whom had undergone an episode of suicide attempt, and 206 healthy controls. A significant decrease in total cholesterol, LDL-cholesterol, VLDL-cholesterol and triglyceride serum levels was observed in the groups of MDD patients and suicide attempt compared to those without suicidal behavior (p < 0.05). After adjusting for covariates, lower cholesterol levels were significantly associated with MDD (OR 4.229 CI 95% 2.555 - 7.000, p<.001) and suicide attempt (OR 5.540 CI 95% 2.825 - 10.866, p<.001) CONCLUSIONS: These results support the hypothesis that lower levels of cholesterol are associated with mood disorders like MDD and suicidal behavior. More mechanistic studies are needed to further explain this association.

Reasons for the upsetting cholesterol level during the community investigation from residents, physicians, and social aspects: the China Cholesterol Education Program (CCEP).

PubMed

Xie, Jiang; Guan, Fei; Wang, Jia-Hong; Hu, Da-Yi

2011-10-01

The community medical center is the first barrier for lipid control. We aimed to survey the residents' cholesterol condition in the community, and pursue the reasons for the upsetting results from various aspects. Residents and physicians were recruited from four community centers. Residents completed questionnaires and a physical examination as well as biochemical analysis. Physicians were also asked to complete a questionnaire, some of which were about basic knowledge of lipids. About 37.0% male and 48.1% female had elevated cholesterol levels. Residents' blood pressure (BP), fasting glucose (FG), body mass index (BMI), and waist circumference (WC) were positively associated with their low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC). Framingham risk scoring (FRS) was strongly related to cholesterol (P < 0.001 for LDL-C and TC). Residents' higher education grade was positively related to a normal cholesterol condition (P < 0.001), while personal income was negatively related to it. Rural residents had higher percent of population with normal cholesterol level (normal cholesterol rate) than their city counterpart (P < 0.001). Although physicians with college education had a much higher lipid knowledge level themselves, the physicians' factors had almost no relationship with the residents' cholesterol levels. Management of hypercholesterolemia should be an important component of health strategy in Beijing. Education is imperative for residents as well as for physicians.

Inclisiran in Patients at High Cardiovascular Risk with Elevated LDL Cholesterol.

PubMed

Ray, Kausik K; Landmesser, Ulf; Leiter, Lawrence A; Kallend, David; Dufour, Robert; Karakas, Mahir; Hall, Tim; Troquay, Roland P T; Turner, Traci; Visseren, Frank L J; Wijngaard, Peter; Wright, R Scott; Kastelein, John J P

2017-04-13

In a previous study, a single injection of inclisiran, a chemically synthesized small interfering RNA designed to target PCSK9 messenger RNA, was found to produce sustained reductions in low-density lipoprotein (LDL) cholesterol levels over the course of 84 days in healthy volunteers. We conducted a phase 2, multicenter, double-blind, placebo-controlled, multiple-ascending-dose trial of inclisiran administered as a subcutaneous injection in patients at high risk for cardiovascular disease who had elevated LDL cholesterol levels. Patients were randomly assigned to receive a single dose of placebo or 200, 300, or 500 mg of inclisiran or two doses (at days 1 and 90) of placebo or 100, 200, or 300 mg of inclisiran. The primary end point was the change from baseline in LDL cholesterol level at 180 days. Safety data were available through day 210, and data on LDL cholesterol and proprotein convertase subtilisin-kexin type 9 (PCSK9) levels were available through day 240. A total of 501 patients underwent randomization. Patients who received inclisiran had dose-dependent reductions in PCSK9 and LDL cholesterol levels. At day 180, the least-squares mean reductions in LDL cholesterol levels were 27.9 to 41.9% after a single dose of inclisiran and 35.5 to 52.6% after two doses (P<0.001 for all comparisons vs. placebo). The two-dose 300-mg inclisiran regimen produced the greatest reduction in LDL cholesterol levels: 48% of the patients who received the regimen had an LDL cholesterol level below 50 mg per deciliter (1.3 mmol per liter) at day 180. At day 240, PCSK9 and LDL cholesterol levels remained significantly lower than at baseline in association with all inclisiran regimens. Serious adverse events occurred in 11% of the patients who received inclisiran and in 8% of the patients who received placebo. Injection-site reactions occurred in 5% of the patients who received injections of inclisiran. In our trial, inclisiran was found to lower PCSK9 and LDL cholesterol levels among patients at high cardiovascular risk who had elevated LDL cholesterol levels. (Funded by the Medicines Company; ORION-1 ClinicalTrials.gov number, NCT02597127 .).

ERICA: prevalence of dyslipidemia in Brazilian adolescents

PubMed Central

Faria, José Rocha; Bento, Vivian Freitas Rezende; Baena, Cristina Pellegrino; Olandoski, Marcia; Gonçalves, Luis Gonzaga de Oliveira; Abreu, Gabriela de Azevedo; Kuschnir, Maria Cristina Caetano; Bloch, Katia Vergetti

2016-01-01

ABSTRACT OBJECTIVE To determine the distribution of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides in Brazilian adolescents, as well as the prevalence of altered levels of such parameters. METHODS Data from the Study of Cardiovascular Risks in Adolescents (ERICA) were used. This is a country-wide, school-based cross-sectional study that evaluated 12 to 17-year old adolescents living in cities with over 100,000 inhabitants. The average and distribution of plasma levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides were evaluated. Dyslipidemia was determined by levels of total cholesterol ≥ 170 mg/dl, LDL cholesterol ≥ 130 mg/dl, HDL cholesterol < 45 mg/dL, or triglycerides ≥ 130 mg/dl. The data were analyzed by gender, age, and regions in Brazil. RESULTS We evaluated 38,069 adolescents – 59.9% of females, and 54.2% between 15 and 17 years. The average values found were: total cholesterol = 148.1 mg/dl (95%CI 147.1-149.1), HDL cholesterol = 47.3 mg/dl (95%CI 46.7-47.9), LDL cholesterol = 85.3 mg/dl (95%CI 84.5-86.1), and triglycerides = 77.8 mg/dl (95%CI 76.5-79.2). The female adolescents had higher average levels of total cholesterol, LDL cholesterol, and HDL cholesterol, without differences in the levels of triglycerides. We did not observe any significant differences between the average values among 12 to 14 and 15- to 17-year old adolescents. The most prevalent lipid alterations were low HDL cholesterol (46.8% [95%CI 44.8-48.9]), hypercholesterolemia (20.1% [95%CI 19.0-21.3]), and hypertriglyceridemia (7.8% [95%CI 7.1-8.6]). High LDL cholesterol was found in 3.5% (95%CI 3.2-4.0) of the adolescents. Prevalence of low HDL cholesterol was higher in Brazil’s North and Northeast regions. CONCLUSIONS A significant proportion of Brazilian adolescents has alterations in their plasma lipids. The high prevalence of low HDL cholesterol and hypertriglyceridemia, especially in Brazil’s North and Northeast regions, must be analyzed in future studies, to support the creation of strategies for efficient interventions. PMID:26910544

Effects of dietary cholesterol supplementation on growth and cholesterol metabolism of rainbow trout (Oncorhynchus mykiss) fed diets with cottonseed meal or rapeseed meal.

PubMed

Deng, Junming; Zhang, Xi; Long, Xiaowen; Tao, Linli; Wang, Zhen; Niu, Guoyi; Kang, Bin

2014-12-01

This study was conducted to evaluate the effects of cholesterol on growth and cholesterol metabolism of rainbow trout (Oncorhynchus mykiss) fed diets with cottonseed meal (CSM) or rapeseed meal (RSM). Four experimental diets were formulated to contain 550 g kg(-1) CSM or 450 g kg(-1) RSM with or without 9 g kg(-1) supplemental cholesterol. Growth rate and feed utilization efficiency of fish fed diets with 450 g kg(-1) RSM were inferior to fish fed diets with 550 g kg(-1) CSM regardless of cholesterol level. Dietary cholesterol supplementation increased the growth rate of fish fed diets with RSM, and growth rate and feed utilization efficiency of fish fed diets with CSM. Similarly, dietary cholesterol supplementation increased the plasma total cholesterol (TC), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triiodothyronine levels, but decreased the plasma triglycerides and cortisol levels of fish fed diets with RSM or CSM. In addition, supplemental cholesterol increased the free cholesterol and TC levels in intestinal contents, but decreased the hepatic 3-hydroxy-3-methyl-glutaryl-CoA reductase activity of fish fed diets with RSM or CSM. These results indicate that 9 g kg(-1) cholesterol supplementation seems to improve the growth of rainbow trout fed diets with CSM or RSM, and the growth-promoting action may be related to the alleviation of the negative effects caused by antinutritional factors and/or make up for the deficiency of endogenous cholesterol in rainbow trout.

Effect of Powder Leaf Breadfruit Disposals (Arthocarpus Altilis) in Oil Mandar District and Polman Against Cholesterol and Glucose Mice (Mus Musculus)

NASA Astrophysics Data System (ADS)

Mu'nisa, A.; Asmawati, A.; Farida, A.; FA, Fressy; Erni

2018-01-01

The purpose of this study was to determine the effect of powdered leaves of breadfruit (Arthocarpus altilis) on oil is mandated origin of the Polman glucose and cholesterol levels in mice (Mus musculus). This study comprised 4 treatments and each treatment consisted of 5 replicates, ie groups of mice were fed a standard (negative control); 2 groups: group of mice fed with standard and cholesterol feed (positive control); Group 3 that mice fed with standard and Selayar oil; and group 4: group of mice fed with standard and Mandar oil that has been given powdered leaves of breadfruit. Measurement of glucose and blood cholesterol levels in mice done 3 times ie 2 weeks after the adaptation period (phase 1), 2 weeks after administration of the oil (phase 2) and 2 weeks after feeding cholesterol (stage 3). Based on the analysis of data both cholesterol and glucose levels showed that in a group of 4 decreased glucose and cholesterol levels in stage 2 but at stage 3 an increase in the group of mice given only the oil while in the group of mice given the oil and powdered leaves of breadfruit indicate glucose levels and normal cholesterol. The conclusion of this study show that the addition of powdered leaves of breadfruit into cooking oil Mandar influential in glucose levels and normalize blood cholesterol levels in mice.

A novel compound inhibits rHDL assembly and blocks nascent HDL biogenesis downstream of apoAI binding to ABCA1 expressing cells

PubMed Central

Lyssenko, Nicholas N.; Brubaker, Gregory; Smith, Bradley D.; Smith, Jonathan D.

2011-01-01

Objective Nascent high-density lipoprotein (HDL) particles form from cellular lipids and extracellular lipid-free apolipoprotein AI (apoAI) in a process mediated by ATP-binding cassette transporter A1 (ABCA1). We have sought out compounds that inhibit nascent HDL biogenesis without affecting ABCA1 activity. Methods and Results Reconstituted HDL (rHDL) formation and cellular cholesterol efflux assays were used to show that two compounds that bond via hydrogen with phospholipids inhibit rHDL and nascent HDL production. In rHDL formation assays, the inhibitory effect of compound 1 (methyl 3α-acetoxy-7α,12α-di[(phenylaminocarbonyl)amino]-5β-cholan-24-oate), the more active of the two, depended on its ability to associate with phospholipids. In cell assays, compound 1 suppressed ABCA1-mediated cholesterol efflux to apoAI, the 18A peptide, and taurocholate with high specificity, without affecting ABCA1-independent cellular cholesterol efflux to HDL and endocytosis of acetylated low-density lipoprotein (AcLDL) and transferrin. Furthermore, compound 1 did not affect ABCA1 activity adversely, as ABCA1-mediated shedding of microparticles proceeded unabated and apoAI binding to ABCA1-expressing cells increased in its presence. Conclusions The inhibitory effects of compound 1 support a three-step model of nascent HDL biogenesis: plasma membrane remodeling by ABCA1, apoAI binding to ABCA1, and lipoprotein particle assembly. The compound inhibits the final step, causing accumulation of apoAI in ABCA1-expressing cells. PMID:21836073

Aspirin Increases the Solubility of Cholesterol in Lipid Membranes

NASA Astrophysics Data System (ADS)

Alsop, Richard; Barrett, Matthew; Zheng, Sonbo; Dies, Hannah; Rheinstadter, Maikel

2014-03-01

Aspirin (ASA) is often prescribed for patients with high levels of cholesterol for the secondary prevention of myocardial events, a regimen known as the Low-Dose Aspirin Therapy. We have recently shown that Aspirin partitions in lipid bilayers. However, a direct interplay between ASA and cholesterol has not been investigated. Cholesterol is known to insert itself into the membrane in a dispersed state at moderate concentrations (under ~37.5%) and decrease fluidity of membranes. We prepared model lipid membranes containing varying amounts of both ASA and cholesterol molecules. The structure of the bilayers as a function of ASA and cholesterol concentration was determined using high-resolution X-ray diffraction. At cholesterol levels of more than 40mol%, immiscible cholesterol plaques formed. Adding ASA to the membranes was found to dissolve the cholesterol plaques, leading to a fluid lipid bilayer structure. We present first direct evidence for an interaction between ASA and cholesterol on the level of the cell membrane.

Influenza A Virus Encoding Secreted Gaussia Luciferase as Useful Tool to Analyze Viral Replication and Its Inhibition by Antiviral Compounds and Cellular Proteins

PubMed Central

Palanisamy, Navaneethan; Goedecke, Ulrike; Jäger, Nils; Pöhlmann, Stefan; Winkler, Michael

2014-01-01

Reporter genes inserted into viral genomes enable the easy and rapid quantification of virus replication, which is instrumental to efficient in vitro screening of antiviral compounds or in vivo analysis of viral spread and pathogenesis. Based on a published design, we have generated several replication competent influenza A viruses carrying either fluorescent proteins or Gaussia luciferase. Reporter activity could be readily quantified in infected cultures, but the virus encoding Gaussia luciferase was more stable than viruses bearing fluorescent proteins and was therefore analyzed in detail. Quantification of Gaussia luciferase activity in the supernatants of infected culture allowed the convenient and highly sensitive detection of viral spread, and enzymatic activity correlated with the number of infectious particles released from infected cells. Furthermore, the Gaussia luciferase encoding virus allowed the sensitive quantification of the antiviral activity of the neuraminidase inhibitor (NAI) zanamivir and the host cell interferon-inducible transmembrane (IFITM) proteins 1–3, which are known to inhibit influenza virus entry. Finally, the virus was used to demonstrate that influenza A virus infection is sensitive to a modulator of endosomal cholesterol, in keeping with the concept that IFITMs inhibit viral entry by altering cholesterol levels in the endosomal membrane. In sum, we report the characterization of a novel influenza A reporter virus, which allows fast and sensitive detection of viral spread and its inhibition, and we show that influenza A virus entry is sensitive to alterations of endosomal cholesterol levels. PMID:24842154

ABCA1, ABCG1, and ABCG4 Are Distributed to Distinct Membrane Meso-Domains and Disturb Detergent-Resistant Domains on the Plasma Membrane

PubMed Central

Sano, Osamu; Ito, Shiho; Kato, Reiko; Shimizu, Yuji; Kobayashi, Aya; Kimura, Yasuhisa; Kioka, Noriyuki; Hanada, Kentaro; Ueda, Kazumitsu; Matsuo, Michinori

2014-01-01

ATP-binding cassette A1 (ABCA1), ABCG1, and ABCG4 are lipid transporters that mediate the efflux of cholesterol from cells. To analyze the characteristics of these lipid transporters, we examined and compared their distributions and lipid efflux activity on the plasma membrane. The efflux of cholesterol mediated by ABCA1 and ABCG1, but not ABCG4, was affected by a reduction of cellular sphingomyelin levels. Detergent solubility and gradient density ultracentrifugation assays indicated that ABCA1, ABCG1, and ABCG4 were distributed to domains that were solubilized by Triton X-100 and Brij 96, resistant to Triton X-100 and Brij 96, and solubilized by Triton X-100 but resistant to Brij 96, respectively. Furthermore, ABCG1, but not ABCG4, was colocalized with flotillin-1 on the plasma membrane. The amounts of cholesterol extracted by methyl-β-cyclodextrin were increased by ABCA1, ABCG1, or ABCG4, suggesting that cholesterol in non-raft domains was increased. Furthermore, ABCG1 and ABCG4 disturbed the localization of caveolin-1 to the detergent-resistant domains and the binding of cholera toxin subunit B to the plasma membrane. These results suggest that ABCA1, ABCG1, and ABCG4 are localized to distinct membrane meso-domains and disturb the meso-domain structures by reorganizing lipids on the plasma membrane; collectively, these observations may explain the different substrate profiles and lipid efflux roles of these transporters. PMID:25302608

Functional analysis of the zebrafish ortholog of HMGCS1 reveals independent functions for cholesterol and isoprenoids in craniofacial development

PubMed Central

Hernandez, Jose A.; Gonzalez, Cesar G.

2017-01-01

There are 8 different human syndromes caused by mutations in the cholesterol synthesis pathway. A subset of these disorders such as Smith-Lemli-Opitz disorder, are associated with facial dysmorphia. However, the molecular and cellular mechanisms underlying such facial deficits are not fully understood, primarily because of the diverse functions associated with the cholesterol synthesis pathway. Recent evidence has demonstrated that mutation of the zebrafish ortholog of HMGCR results in orofacial clefts. Here we sought to expand upon these data, by deciphering the cholesterol dependent functions of the cholesterol synthesis pathway from the cholesterol independent functions. Moreover, we utilized loss of function analysis and pharmacological inhibition to determine the extent of sonic hedgehog (Shh) signaling in animals with aberrant cholesterol and/or isoprenoid synthesis. Our analysis confirmed that mutation of hmgcs1, which encodes the first enzyme in the cholesterol synthesis pathway, results in craniofacial abnormalities via defects in cranial neural crest cell differentiation. Furthermore targeted pharmacological inhibition of the cholesterol synthesis pathway revealed a novel function for isoprenoid synthesis during vertebrate craniofacial development. Mutation of hmgcs1 had no effect on Shh signaling at 2 and 3 days post fertilization (dpf), but did result in a decrease in the expression of gli1, a known Shh target gene, at 4 dpf, after morphological deficits in craniofacial development and chondrocyte differentiation were observed in hmgcs1 mutants. These data raise the possibility that deficiencies in cholesterol modulate chondrocyte differentiation by a combination of Shh independent and Shh dependent mechanisms. Moreover, our results describe a novel function for isoprenoids in facial development and collectively suggest that cholesterol regulates craniofacial development through versatile mechanisms. PMID:28686747

Bacterial Colonization of Host Cells in the Absence of Cholesterol

PubMed Central

Gilk, Stacey D.; Cockrell, Diane C.; Luterbach, Courtney; Hansen, Bryan; Knodler, Leigh A.; Ibarra, J. Antonio; Steele-Mortimer, Olivia; Heinzen, Robert A.

2013-01-01

Reports implicating important roles for cholesterol and cholesterol-rich lipid rafts in host-pathogen interactions have largely employed sterol sequestering agents and biosynthesis inhibitors. Because the pleiotropic effects of these compounds can complicate experimental interpretation, we developed a new model system to investigate cholesterol requirements in pathogen infection utilizing DHCR24−/− mouse embryonic fibroblasts (MEFs). DHCR24−/− MEFs lack the Δ24 sterol reductase required for the final enzymatic step in cholesterol biosynthesis, and consequently accumulate desmosterol into cellular membranes. Defective lipid raft function by DHCR24−/− MEFs adapted to growth in cholesterol-free medium was confirmed by showing deficient uptake of cholera-toxin B and impaired signaling by epidermal growth factor. Infection in the absence of cholesterol was then investigated for three intracellular bacterial pathogens: Coxiella burnetii, Salmonella enterica serovar Typhimurium, and Chlamydia trachomatis. Invasion by S. Typhimurium and C. trachomatis was unaltered in DHCR24−/− MEFs. In contrast, C. burnetii entry was significantly decreased in −cholesterol MEFs, and also in +cholesterol MEFs when lipid raft-associated αVβ3 integrin was blocked, suggesting a role for lipid rafts in C. burnetii uptake. Once internalized, all three pathogens established their respective vacuolar niches and replicated normally. However, the C. burnetii-occupied vacuole within DHCR24−/− MEFs lacked the CD63-postive material and multilamellar membranes typical of vacuoles formed in wild type cells, indicating cholesterol functions in trafficking of multivesicular bodies to the pathogen vacuole. These data demonstrate that cholesterol is not essential for invasion and intracellular replication by S. Typhimurium and C. trachomatis, but plays a role in C. burnetii-host cell interactions. PMID:23358892

Association of Cholesterol Efflux Capacity With Clinical Features of Metabolic Syndrome: Relevance to Atherosclerosis.

PubMed

Gall, Julie; Frisdal, Eric; Bittar, Randa; Le Goff, Wilfried; Bruckert, Eric; Lesnik, Philippe; Guerin, Maryse; Giral, Philippe

2016-11-23

The contribution of high-density lipoprotein to cardiovascular benefit is closely linked to its role in the cellular cholesterol efflux process; however, various clinical and biochemical variables are known to modulate the overall cholesterol efflux process. The aim of this study was to evaluate the extent to which clinical and biological anomalies associated with the establishment of the metabolic syndrome modulate cholesterol efflux capacity and contribute to development of atherosclerosis. This study involved patients (n=1202) displaying atherogenic dyslipidemia in primary prevention who were referred to our prevention center. Among these patients, 25% presented at least 3 criteria of the metabolic syndrome, as defined by the National Cholesterol Education Program Adult Treatment Panel III. We measured the capacity of 40-fold diluted serum to mediate cholesterol efflux from cholesterol-loaded human THP-1 macrophages. Cholesterol efflux capacity was reduced progressively by 4% to 11% (P<0.0001) as a function of the increasing number of coexisting criteria for the metabolic syndrome from 1 to 5. This observation was primarily related to reductions in scavenger receptor class B member 1 and ATP binding cassette subfamily G member 1-dependent efflux. Multivariate analyses indicate that serum efflux capacity was significantly associated with established metabolic syndrome (odds ratio 0.45; 95% CI 0.28-0.72; P=0.009) independent of age, low-density lipoprotein cholesterol, status with regard to lipid-lowering therapy, smoking status, and alcohol consumption. Our study revealed that individual criteria of metabolic syndrome are closely related synergistically to cholesterol efflux capacity. In addition, established metabolic syndrome and cholesterol efflux capacity were independently associated with clinical features of atherosclerosis. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Bioorthogonal probes for imaging sterols in cells.

PubMed

Jao, Cindy Y; Nedelcu, Daniel; Lopez, Lyle V; Samarakoon, Thilani N; Welti, Ruth; Salic, Adrian

2015-03-02

Cholesterol is a fundamental lipid component of eukaryotic membranes and a precursor of potent signaling molecules, such as oxysterols and steroid hormones. Cholesterol and oxysterols are also essential for Hedgehog signaling, a pathway critical in embryogenesis and cancer. Despite their importance, the use of imaging sterols in cells is currently very limited. We introduce a robust and versatile method for sterol microscopy based on C19 alkyne cholesterol and oxysterol analogues. These sterol analogues are fully functional; they rescue growth of cholesterol auxotrophic cells and faithfully recapitulate the multiple roles that sterols play in Hedgehog signal transduction. Alkyne sterol analogues incorporate efficiently into cellular membranes and can be imaged with high resolution after copper(I)-catalyzed azide-alkyne cycloaddition reaction with fluorescent azides. We demonstrate the use of alkyne sterol probes for visualizing the subcellular distribution of cholesterol and for two-color imaging of sterols and choline phospholipids. Our imaging strategy should be broadly applicable to studying the role of sterols in normal physiology and disease. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Knee osteoarthritis, dyslipidemia syndrome and exercise.

PubMed

Păstrăiguş, Carmen; Ancuţa, Codrina; Miu, Smaranda; Ancuţa, E; Chirieac, Rodica

2012-01-01

The aim of our study was to evaluate the influence of aerobic training on the dyslipedemia in patients with knee osteoarthritis (KOA). Prospective observational six-month study performed on 40 patients with KOA, fulfilling the inclusion criteria, classified according to their participation in specific aerobic training program (30 minutes/day, 5 days/ week) in two subgroups. A standard evaluation protocol was followed assessing lipid parameters (total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol levels) at baseline, three and six months. Statistical analysis was performed in SPSS 16.0, p < 0.05. Subgroup analysis has demonstrated a statistical significant improvement in plasma lipids levels in all patients performing regular aerobic training (cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol) (p < 0.05). Although the difference reported for total cholesterol, triglycerides and LDL-cholesterol after six months between subgroups was not significant (p > 0.05), the mean level of HDL-cholesterol was significantly higher in patients performing aerobic training, reaching the cardio-vascular protective levels. Regular aerobic exercise has a positive effect on plasma lipoprotein concentrations; further research is needed for the assessment of long-term effects of physical exercises for both KOA and lipid pattern.

Association of lifestyle with serum lipid levels: a study of middle-aged Japanese men.

PubMed

Nakanishi, N; Tatara, K; Nakamura, K; Suzuki, K

2000-07-01

Cross-sectional associations between lifestyle and serum lipid levels were examined in 1591 Japanese male office workers aged 35 to 59 years in Osaka, Japan. From multiple linear regression analyses, significant correlates with low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and Log triglyceride levels and the ratio of LDL cholesterol to HDL cholesterol were, in the order of relative importance: BMI, alcohol intake (negative) and age for LDL cholesterol level; BMI (negative), cigarette smoking (negative), alcohol intake, consideration for nutritional balance, hours of brisk walking, hours of walking at an ordinary pace and physical exercise for HDL cholesterol level; BMI, cigarette smoking, consideration for nutritional balance (negative), hours of work (negative), alcohol intake and coffee drinking (negative) for Log triglyceride level; and BMI, alcohol intake (negative), cigarette smoking, consideration for nutritional balance (negative), age, hours of brisk walking (negative) and the frequency of snack intake between meals for the ratio of LDL cholesterol to HDL cholesterol. Our data suggest that obesity, cigarette smoking and snack intake between meals are atherogenic whereas alcohol consumption, consideration for nutritional balance and walking long hours, especially at a brisk pace, are anti-atherogenic in middle-aged Japanese men.

[Hypercholesterolemia: a therapeutic approach].

PubMed

Moráis López, A; Lama More, R A; Dalmau Serra, J

2009-05-01

High blood cholesterol levels represent an important cardiovascular risk factor. Hypercholesterolemia is defined as levels of total cholesterol and low-density lipoprotein cholesterol above 95th percentile for age and gender. For the paediatric population, selective screening is recommended in children older than 2 years who are overweight, with a family history of early cardiovascular disease or whose parents have high cholesterol levels. Initial therapeutic approach includes diet therapy, appropriate physical activity and healthy lifestyle changes. Drug treatment should be considered in children from the age of 10 who, after having followed appropriate diet recommendations, still have very high LDL-cholesterol levels or moderately high levels with concomitant risk factors. In case of extremely high LDL-cholesterol levels, drug treatment should be taken into consideration at earlier ages (8 years old). Modest response is usually observed with bile acid-binding resins. Statins can be considered first-choice drugs, once evidence on their efficacy and safety has been shown.

Hypercholesterolemia Induces Angiogenesis and Accelerates Growth of Breast Tumors in Vivo

PubMed Central

Pelton, Kristine; Coticchia, Christine M.; Curatolo, Adam S.; Schaffner, Carl P.; Zurakowski, David; Solomon, Keith R.; Moses, Marsha A.

2015-01-01

Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo. PMID:24952430

Statins increase hepatic cholesterol synthesis and stimulate fecal cholesterol elimination in mice.

PubMed

Schonewille, Marleen; de Boer, Jan Freark; Mele, Laura; Wolters, Henk; Bloks, Vincent W; Wolters, Justina C; Kuivenhoven, Jan A; Tietge, Uwe J F; Brufau, Gemma; Groen, Albert K

2016-08-01

Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Statins reduce plasma cholesterol levels, but whether this is actually caused by inhibition of de novo cholesterol synthesis has not been clearly established. Using three different statins, we investigated the effects on cholesterol metabolism in mice in detail. Surprisingly, direct measurement of whole body cholesterol synthesis revealed that cholesterol synthesis was robustly increased in statin-treated mice. Measurement of organ-specific cholesterol synthesis demonstrated that the liver is predominantly responsible for the increase in cholesterol synthesis. Excess synthesized cholesterol did not accumulate in the plasma, as plasma cholesterol decreased. However, statin treatment led to an increase in cholesterol removal via the feces. Interestingly, enhanced cholesterol excretion in response to rosuvastatin and lovastatin treatment was mainly mediated via biliary cholesterol secretion, whereas atorvastatin mainly stimulated cholesterol removal via the transintestinal cholesterol excretion pathway. Moreover, we show that plasma cholesterol precursor levels do not reflect cholesterol synthesis rates during statin treatment in mice. In conclusion, cholesterol synthesis is paradoxically increased upon statin treatment in mice. However, statins potently stimulate the excretion of cholesterol from the body, which sheds new light on possible mechanisms underlying the cholesterol-lowering effects of statins. Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.

Statins increase hepatic cholesterol synthesis and stimulate fecal cholesterol elimination in mice

PubMed Central

Schonewille, Marleen; Freark de Boer, Jan; Mele, Laura; Wolters, Henk; Bloks, Vincent W.; Wolters, Justina C.; Kuivenhoven, Jan A.; Tietge, Uwe J. F.; Brufau, Gemma; Groen, Albert K.

2016-01-01

Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Statins reduce plasma cholesterol levels, but whether this is actually caused by inhibition of de novo cholesterol synthesis has not been clearly established. Using three different statins, we investigated the effects on cholesterol metabolism in mice in detail. Surprisingly, direct measurement of whole body cholesterol synthesis revealed that cholesterol synthesis was robustly increased in statin-treated mice. Measurement of organ-specific cholesterol synthesis demonstrated that the liver is predominantly responsible for the increase in cholesterol synthesis. Excess synthesized cholesterol did not accumulate in the plasma, as plasma cholesterol decreased. However, statin treatment led to an increase in cholesterol removal via the feces. Interestingly, enhanced cholesterol excretion in response to rosuvastatin and lovastatin treatment was mainly mediated via biliary cholesterol secretion, whereas atorvastatin mainly stimulated cholesterol removal via the transintestinal cholesterol excretion pathway. Moreover, we show that plasma cholesterol precursor levels do not reflect cholesterol synthesis rates during statin treatment in mice. In conclusion, cholesterol synthesis is paradoxically increased upon statin treatment in mice. However, statins potently stimulate the excretion of cholesterol from the body, which sheds new light on possible mechanisms underlying the cholesterol-lowering effects of statins. PMID:27313057

Isoflavone and Protein Constituents of Lactic Acid-Fermented Soy Milk Combine to Prevent Dyslipidemia in Rats Fed a High Cholesterol Diet

PubMed Central

Kobayashi, Maki; Egusa, Shintaro; Fukuda, Mitsuru

2014-01-01

A high cholesterol diet induces dyslipidemia. This study investigated whether isoflavone aglycones in lactic acid-fermented soy milk (LFS) improve lipid metabolism in rats fed a high cholesterol diet. Male Sprague-Dawley rats aged seven weeks were fed an AIN-93G diet, a 1% cholesterol diet (a high cholesterol diet), a high-cholesterol diet containing 4% isoflavone extract of LFS (LFS extract diet), a high-cholesterol diet containing 19.4% ethanol-washed LFS (ethanol-washed LFS diet, isoflavone-poor diet), or a high cholesterol diet containing 23.2% intact LFS (intact LFS diet) for five weeks. The plasma total cholesterol (TC) level was increased in the rats fed the LFS extract diet compared with those fed the high cholesterol diet. The TC level was decreased by the intact LFS and ethanol-washed LFS diets. The cholesterol-lowering effect was stronger in the rats fed the intact LFS diet than those fed the ethanol-washed LFS diet. The plasma triglyceride (TG) level was unchanged in the rats fed the LFS extract diet, but it decreased in rats fed the intact LFS and ethanol-washed LFS diets. Although, compared with the high cholesterol diet, the LFS extract and ethanol-washed LFS diets did not reduce hepatic cholesterol and TG, both levels were remarkably lowered by the intact LFS diet. These results suggest that the improvement in lipid metabolism of rats fed a high-cholesterol diet containing LFS isoflavone aglycones is not due to an independent effect but due to a cooperative effect with soy protein. PMID:25514389

The influence of saponins on cell membrane cholesterol.

PubMed

Böttger, Stefan; Melzig, Matthias F

2013-11-15

We studied the influence of structurally different saponins on the cholesterol content of cellular membranes. Therefore a cell culture model using ECV-304 urinary bladder carcinoma cells was developed. To measure the cholesterol content we used radiolabeled (3)H-cholesterol which is chemically and physiologically identical to natural cholesterol. The cells were pre-incubated with (3)H-cholesterol and after a medium change, they were treated with saponins to assess a saponin-induced cholesterol liberation from the cell membrane. In another experiment the cells were pre-incubated with saponins and after a medium change, they were treated with (3)H-cholesterol to assess a saponin-induced inhibition of cholesterol uptake into the cell membrane. Furthermore, the membrane toxicity of all applied saponins was analyzed using extracellular LDH quantification and the general cytotoxicity was analyzed using a colorimetric MTT-assay and DNA quantification. Our results revealed a correlation between membrane toxicity and general cytotoxicity. We also compared the results from the experiments on the saponin-induced cholesterol liberation as well as the saponin-induced inhibition of cholesterol uptake with the membrane toxicity. A significant reduction in the cell membrane cholesterol content was noted for those saponins who showed membrane toxicity (IC50 <60 μM). These potent membrane toxic saponins either liberated (3)H-cholesterol from intact cell membranes or blocked the integration of supplemented (3)H-cholesterol into the cell membrane. Saponins with little influence on the cell membrane (IC50 >100 μM) insignificantly altered the cell membrane cholesterol content. The results suggested that the general cytotoxicity of saponins is mainly dependent on their membrane toxicity and that the membrane toxicity might be caused by the loss of cholesterol from the cell membrane. We also analyzed the influence of a significantly membrane toxic saponin on the cholesterol content of intracellular membranes such as those of endosomes and lysosomes. In these experiments ECV-304 cells were either incubated with (3)H-cholesterol or with (3)H-cholesterol and 5 μM saponin. After isolation of the endosomes/lysosomes their (3)H-cholesterol content was measured. A significant influence of the saponins on the cholesterol content of endosomal/lysosomal membranes was not detected. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pathological levels of glucosylceramide change the biophysical properties of artificial and cell membranes.

PubMed

Varela, Ana R P; Ventura, Ana E; Carreira, Ana C; Fedorov, Aleksander; Futerman, Anthony H; Prieto, Manuel; Silva, Liana C

2016-12-21

Glucosylceramide (GlcCer) plays an active role in the regulation of various cellular events. Moreover, GlcCer is also a key modulator of membrane biophysical properties, which might be linked to the mechanism of its biological action. In order to understand the biophysical implications of GlcCer on membranes of living cells, we first studied the effect of GlcCer on artificial membranes containing 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM) and cholesterol (Chol). Using an array of biophysical methods, we demonstrate that at lower GlcCer/Chol ratios, GlcCer stabilizes SM/Chol-enriched liquid-ordered domains. However, upon decreasing the Chol content, GlcCer significantly increased membrane order through the formation of gel domains. Changes in pH disturbed the packing properties of GlcCer-containing membranes, leading to an increase in membrane fluidity and reduced membrane electronegativity. To address the biophysical impact of GlcCer in biological membranes, studies were performed in wild type and in fibroblasts treated with conduritol-B-epoxide (CBE), which causes intracellular GlcCer accumulation, and in fibroblasts from patients with type I Gaucher disease (GD). Decreased membrane fluidity was observed in cells containing higher levels of GlcCer, such as in CBE-treated and GD cells. Together, we demonstrate that elevated GlcCer levels change the biophysical properties of cellular membranes, which might compromise membrane-associated cellular events and be of relevance for understanding the pathology of diseases, such as GD, in which GlcCer accumulates at high levels.

Corn silk extract improves cholesterol metabolism in C57BL/6J mouse fed high-fat diets.

PubMed

Cha, Jae Hoon; Kim, Sun Rim; Kang, Hyun Joong; Kim, Myung Hwan; Ha, Ae Wha; Kim, Woo Kyoung

2016-10-01

Corn silk (CS) extract contains large amounts of maysin, which is a major flavonoid in CS. However, studies regarding the effect of CS extract on cholesterol metabolism is limited. Therefore, the purpose of this study was to determine the effect of CS extract on cholesterol metabolism in C57BL/6J mouse fed high-fat diets. Normal-fat group fed 7% fat diet, high-fat (HF) group fed 25% fat diet, and high-fat with corn silk (HFCS) group were orally administered CS extract (100 mg/kg body weight) daily. Serum and hepatic levels of total lipids, triglycerides, and total cholesterol as well as serum free fatty acid, glucose, and insulin levels were determined. The mRNA expression levels of acyl-CoA: cholesterol acyltransferase (ACAT), cholesterol 7-alpha hydroxylase (CYP7A1), farnesoid X receptor (FXR), lecithin cholesterol acyltransferase (LCAT), low-density lipoprotein receptor, 3-hyroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase), adiponectin, leptin, and tumor necrosis factor α were determined. Oral administration of CS extract with HF improved serum glucose and insulin levels as well as attenuated HF-induced fatty liver. CS extracts significantly elevated mRNA expression levels of adipocytokines and reduced mRNA expression levels of HMG-CoA reductase, ACAT, and FXR. The mRNA expression levels of CYP7A1 and LCAT between the HF group and HFCS group were not statistically different. CS extract supplementation with a high-fat diet improves levels of adipocytokine secretion and glucose homeostasis. CS extract is also effective in decreasing the regulatory pool of hepatic cholesterol, in line with decreased blood and hepatic levels of cholesterol though modulation of mRNA expression levels of HMG-CoA reductase, ACAT, and FXR.

[Study on the dynamic variations and influencing factors of serum lipid levels during pregnancy and postpartum].

PubMed

Xu, D; Liang, C; Chen, L; Wu, X D; He, J

2018-04-25

Objective: To study the variations and influencing factors of serum triglycerides and cholesterol levels during pregnancy and postpartum. Methods: A retrospective study was performed among 5 020 healthy singleton (95.10%, 4 774/5 020) and twin (4.90%, 246/5 020) women who had delivery in Women's Hospital, Zhejiang University School of Medicine from January 2011 to December 2016. Serum triglycerides and cholesterol levels during pregnancy and postpartum of all the cases were collected. Both singleton and twin pregnant women were divided into advanced age and appropriate age groups, and then data of serum sample were assigned to 3 groups according to the gestation weeks, which were second trimester pregnancy (24-28 gestation weeks) , third trimester pregnancy (32-41 gestation weeks) and postpartum (within 72 hours after delivery) . The serum triglycerides and cholesterol levels in each groups were compared. Results: (1) Serum triglycerides and cholesterol levels during the second trimester pregnancy, third trimester pregnancy and postpartum were higher than levels of non-pregnancy in both singleton and twin groups (all P< 0.05) . (2) Serum triglycerides and cholesterol levels in the third trimester pregnancy group were higher than those of second trimester pregnancy group in both advanced age and appropriate aged women regardless singleton or twin pregnancy (all P< 0.05) . The 95% CI of serum lipid levels in each group during second and third trimester pregnancy were as follows: in appropriate aged singleton group, the triglycerides levels were 1.07-4.13 and 1.52-7.21 mmol/L, and the cholesterol levels were 2.77-12.11 and 4.44-9.36 mmol/L. In advanced aged singleton group, the triglycerides levels were 1.28-4.61 and 1.70-7.80 mmol/L, and the cholesterol levels were 4.35-8.40 and 4.46-9.35 mmol/L; in appropriate aged twin group, the triglycerides levels were 1.39-7.16 and 1.90-9.29 mmol/L, and the cholesterol levels were 4.99-12.16 and 4.52-10.07 mmol/L; in advanced aged twin group, the triglycerides levels were 1.61-5.32 and 1.94-9.29 mmol/L, and the cholesterol levels were 5.24-8.10 and 4.53-8.86 mmol/L. (3) Serum lipids levels rapidly decreased during postpartum compared to the third trimester pregnancy. The 95% CI of blood lipid levels in each group were as follows: in appropriate aged singleton group, the triglycerides level was 0.90-5.64 mmol/L and the cholesterol level was 4.70-8.52 mmol/L; in advanced aged singleton group, the triglycerides level was 0.87-5.43 mmol/L and the cholesterol level was 4.68-9.04 mmol/L; in appropriate aged twin group, the triglycerides level was 1.20-8.21 mmol/L and the cholesterol level was 4.66-8.45 mmol/L; in advanced aged twin group, the triglycerides level was 1.32-6.61 mmol/L, and the cholesterol level was 5.01-7.94 mmol/L. (4) Serum triglycerides and cholesterol levels in twin pregnant women were significantly higher than in singleton during the second trimester and third trimester pregnancy both in advanced age and appropriate age groups (all P< 0.05) . During postpartum, there was no difference in serum lipid levels between the singleton and twin pregnant women in appropriate age group (triglycerides: P= 0.982; cholesterol: P= 0.759, respectively) . While the serum lipid levels in twin pregnant women were significantly higher than those of singleton women in advanced age group (triglycerides: P= 0.000; cholesterol: P= 0.000, respectively) . Conclusions: The standard of serum lipid levels of non-pregnant adults is not suitable for assessing that in pregnant women. Regardless of singleton or twin pregnancy, serum triglyceride and cholesterol levels during pregnancy elevate with the increasing gestational week and then rapidly decrease during postpartum. Age and twins are the influencing factors of the elevated physiological lipid levels during pregnancy.

High plasma level of remnant-like particle cholesterol in the metabolic syndrome.

PubMed

Satoh, Akira; Adachi, Hisashi; Tsuruta, Makoto; Hirai, Yuji; Hiratsuka, Akiko; Enomoto, Mika; Furuki, Kumiko; Hino, Asuka; Takeuchi, Tomohiro; Imaizumi, Tsutomu

2005-10-01

The metabolic syndrome is associated with a high incidence of cardiovascular disease even when the abnormalities present in the syndrome are mild. The underlying mechanism of the metabolic syndrome has not been elucidated. We investigated whether a strong atherogenic lipoprotein, remnant-like particle (RLP) lipoprotein cholesterol, is elevated in the metabolic syndrome. We performed a health examination among the residents of a rural community in Japan. Complete datasets, including fasting RLP cholesterol levels, were obtained in 1,261 subjects (509 men and 752 women) without diabetes and who were not taking lipid-lowering drugs. The subjects' medical history, use of alcohol, and smoking habits were ascertained by a questionnaire. All of the components of the metabolic syndrome were significantly related to RLP cholesterol by univariate analysis. Total cholesterol and smoking habits were also positively associated with RLP cholesterol. The subjects with the metabolic syndrome showed only mild abnormalities of each component. When RLP cholesterol levels were stratified by the number of the components of the metabolic syndrome, there was a strong association between RLP cholesterol levels and the number of components (P < 0.001 and F = 72.7). RLP cholesterol levels are elevated in the metabolic syndrome, and this elevation may underlie the high incidence of cardiovascular disease in the metabolic syndrome.

Carrier-free cellular uptake and the gene-silencing activity of the lipophilic siRNAs is strongly affected by the length of the linker between siRNA and lipophilic group.

PubMed

Petrova, Natalya S; Chernikov, Ivan V; Meschaninova, Mariya I; Dovydenko, Iiya S; Venyaminova, Aliya G; Zenkova, Marina A; Vlassov, Valentin V; Chernolovskaya, Elena L

2012-03-01

The conjugation of siRNA to molecules, which can be internalized into the cell via natural transport mechanisms, can result in the enhancement of siRNA cellular uptake. Herein, the carrier-free cellular uptake of nuclease-resistant anti-MDR1 siRNA equipped with lipophilic residues (cholesterol, lithocholic acid, oleyl alcohol and litocholic acid oleylamide) attached to the 5'-end of the sense strand via oligomethylene linker of various length was investigated. A convenient combination of H-phosphonate and phosphoramidite methods was developed for the synthesis of 5'-lipophilic conjugates of siRNAs. It was found that lipophilic siRNA are able to effectively penetrate into HEK293, HepG2 and KB-8-5 cancer cells when used in a micromolar concentration range. The efficiency of the uptake is dependent upon the type of lipophilic moiety, the length of the linker between the moiety and the siRNA and cell type. Among all the conjugates tested, the cholesterol-conjugated siRNAs with linkers containing from 6 to 10 carbon atoms demonstrate the optimal uptake and gene silencing properties: the shortening of the linker reduces the efficiency of the cellular uptake of siRNA conjugates, whereas the lengthening of the linker facilitates the uptake but retards the gene silencing effect and decreases the efficiency of the silencing.

Serum HDL cholesterol concentration in patients with squamous cell and small cell lung cancer.

PubMed

Siemianowicz, K; Gminski, J; Stajszczyk, M; Wojakowski, W; Goss, M; Machalski, M; Telega, A; Brulinski, K; Magiera-Molendowska, H

2000-09-01

Cancer patients often present altered serum lipid profile including changes of HDL cholesterol level. The aim of our work was to evaluate serum level of HDL cholesterol in patients with squamous cell and small cell lung cancer and its dependence on histological type and clinical stage of lung cancer. Fasting serum level of HDL cholesterol was analysed in 135 patients with newly diagnosed lung cancer and compared to a control group of healthy men. All lung cancer patients, as well as subgroups of squamous cell and small cell lung cancer had statistically significantly lower HDL cholesterol concentration than controls. There were no statistically significant differences of HDL cholesterol level between the histological types or between clinical stages of each histological type of lung cancer.

PEG-lipid micelles enable cholesterol efflux in Niemann-Pick Type C1 disease-based lysosomal storage disorder

PubMed Central

Brown, Anna; Patel, Siddharth; Ward, Carl; Lorenz, Anna; Ortiz, Mauren; DuRoss, Allison; Wieghardt, Fabian; Esch, Amanda; Otten, Elsje G.; Heiser, Laura M.; Korolchuk, Viktor I.; Sun, Conroy; Sarkar, Sovan; Sahay, Gaurav

2016-01-01

2-Hydroxy-propyl-β-cyclodextrin (HPβCD), a cholesterol scavenger, is currently undergoing Phase 2b/3 clinical trial for treatment of Niemann Pick Type C-1 (NPC1), a fatal neurodegenerative disorder that stems from abnormal cholesterol accumulation in the endo/lysosomes. Unfortunately, the extremely high doses of HPβCD required to prevent progressive neurodegeneration exacerbates ototoxicity, pulmonary toxicity and autophagy-based cellular defects. We present unexpected evidence that a poly (ethylene glycol) (PEG)-lipid conjugate enables cholesterol clearance from endo/lysosomes of Npc1 mutant (Npc1−/−) cells. Herein, we show that distearyl-phosphatidylethanolamine-PEG (DSPE-PEG), which forms 12-nm micelles above the critical micelle concentration, accumulates heavily inside cholesterol-rich late endosomes in Npc1−/− cells. This potentially results in cholesterol solubilization and leakage from lysosomes. High-throughput screening revealed that DSPE-PEG, in combination with HPβCD, acts synergistically to efflux cholesterol without significantly aggravating autophagy defects. These well-known excipients can be used as admixtures to treat NPC1 disorder. Increasing PEG chain lengths from 350 Da-30 kDa in DSPE-PEG micelles, or increasing DSPE-PEG content in an array of liposomes packaged with HPβCD, improved cholesterol egress, while Pluronic block copolymers capable of micelle formation showed slight effects at high concentrations. We postulate that PEG-lipid based nanocarriers can serve as bioactive drug delivery systems for effective treatment of lysosomal storage disorders. PMID:27572704

PEG-lipid micelles enable cholesterol efflux in Niemann-Pick Type C1 disease-based lysosomal storage disorder

NASA Astrophysics Data System (ADS)

Brown, Anna; Patel, Siddharth; Ward, Carl; Lorenz, Anna; Ortiz, Mauren; Duross, Allison; Wieghardt, Fabian; Esch, Amanda; Otten, Elsje G.; Heiser, Laura M.; Korolchuk, Viktor I.; Sun, Conroy; Sarkar, Sovan; Sahay, Gaurav

2016-08-01

2-Hydroxy-propyl-β-cyclodextrin (HPβCD), a cholesterol scavenger, is currently undergoing Phase 2b/3 clinical trial for treatment of Niemann Pick Type C-1 (NPC1), a fatal neurodegenerative disorder that stems from abnormal cholesterol accumulation in the endo/lysosomes. Unfortunately, the extremely high doses of HPβCD required to prevent progressive neurodegeneration exacerbates ototoxicity, pulmonary toxicity and autophagy-based cellular defects. We present unexpected evidence that a poly (ethylene glycol) (PEG)-lipid conjugate enables cholesterol clearance from endo/lysosomes of Npc1 mutant (Npc1-/-) cells. Herein, we show that distearyl-phosphatidylethanolamine-PEG (DSPE-PEG), which forms 12-nm micelles above the critical micelle concentration, accumulates heavily inside cholesterol-rich late endosomes in Npc1-/- cells. This potentially results in cholesterol solubilization and leakage from lysosomes. High-throughput screening revealed that DSPE-PEG, in combination with HPβCD, acts synergistically to efflux cholesterol without significantly aggravating autophagy defects. These well-known excipients can be used as admixtures to treat NPC1 disorder. Increasing PEG chain lengths from 350 Da-30 kDa in DSPE-PEG micelles, or increasing DSPE-PEG content in an array of liposomes packaged with HPβCD, improved cholesterol egress, while Pluronic block copolymers capable of micelle formation showed slight effects at high concentrations. We postulate that PEG-lipid based nanocarriers can serve as bioactive drug delivery systems for effective treatment of lysosomal storage disorders.

Cholesterol trafficking and raft-like membrane domain composition mediate scavenger receptor class B type 1-dependent lipid sensing in intestinal epithelial cells.

PubMed

Morel, Etienne; Ghezzal, Sara; Lucchi, Géraldine; Truntzer, Caroline; Pais de Barros, Jean-Paul; Simon-Plas, Françoise; Demignot, Sylvie; Mineo, Chieko; Shaul, Philip W; Leturque, Armelle; Rousset, Monique; Carrière, Véronique

2018-02-01

Scavenger receptor Class B type 1 (SR-B1) is a lipid transporter and sensor. In intestinal epithelial cells, SR-B1-dependent lipid sensing is associated with SR-B1 recruitment in raft-like/ detergent-resistant membrane domains and interaction of its C-terminal transmembrane domain with plasma membrane cholesterol. To clarify the initiating events occurring during lipid sensing by SR-B1, we analyzed cholesterol trafficking and raft-like domain composition in intestinal epithelial cells expressing wild-type SR-B1 or the mutated form SR-B1-Q445A, defective in membrane cholesterol binding and signal initiation. These features of SR-B1 were found to influence both apical cholesterol efflux and intracellular cholesterol trafficking from plasma membrane to lipid droplets, and the lipid composition of raft-like domains. Lipidomic analysis revealed likely participation of d18:0/16:0 sphingomyelin and 16:0/0:0 lysophosphatidylethanolamine in lipid sensing by SR-B1. Proteomic analysis identified proteins, whose abundance changed in raft-like domains during lipid sensing, and these included molecules linked to lipid raft dynamics and signal transduction. These findings provide new insights into the role of SR-B1 in cellular cholesterol homeostasis and suggest molecular links between SR-B1-dependent lipid sensing and cell cholesterol and lipid droplet dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Cholesterol binding, efflux, and a PDZ-interacting domain of scavenger receptor–BI mediate HDL-initiated signaling

PubMed Central

Assanasen, Chatchawin; Mineo, Chieko; Seetharam, Divya; Yuhanna, Ivan S.; Marcel, Yves L.; Connelly, Margery A.; Williams, David L.; de la Llera-Moya, Margarita; Shaul, Philip W.; Silver, David L.

2005-01-01

The binding of HDL to scavenger receptor–BI (SR-BI) mediates cholesterol movement. HDL also induces multiple cellular signals, which in endothelium occur through SR-BI and converge to activate eNOS. To determine the molecular basis of a signaling event induced by HDL, we examined the proximal mechanisms in HDL activation of eNOS. In endothelial cells, HDL and methyl-β-cyclodextrin caused comparable eNOS activation, whereas cholesterol-loaded methyl-β-cyclodextrin had no effect. Phosphatidylcholine-loaded HDL caused greater stimulation than native HDL, and blocking antibody against SR-BI, which prevents cholesterol efflux, prevented eNOS activation. In a reconstitution model in COS-M6 cells, wild-type SR-BI mediated eNOS activation by both HDL and small unilamellar vesicles (SUVs), whereas the SR-BI mutant AVI, which is incapable of efflux to SUV, transmitted signal by only HDL. In addition, eNOS activation by methyl-β-cyclodextrin was SR-BI dependent. Studies of mutant and chimeric class B scavenger receptors revealed that the C-terminal cytoplasmic PDZ-interacting domain and the C-terminal transmembrane domains of SR-BI are both necessary for HDL signaling. Furthermore, we demonstrated direct binding of cholesterol to the C-terminal transmembrane domain using a photoactivated derivative of cholesterol. Thus, HDL signaling requires cholesterol binding and efflux and C-terminal domains of SR-BI, and SR-BI serves as a cholesterol sensor on the plasma membrane. PMID:15841181

Characterization of pneumolysin from Streptococcus pneumoniae, interacting with carbohydrate moiety and cholesterol as a component of cell membrane.

PubMed

Lim, Jong Eun; Park, Seong Ah; Bong, Seoung Min; Chi, Young Min; Lee, Ki Seog

2013-01-11

The cytolytic mechanism of cholesterol-dependent cytolysins (CDCs) requires the presence of cholesterol in the target cell membrane. Membrane cholesterol was thought to serve as the common receptor for these toxins, but not all CDCs require cholesterol for binding. One member of this toxin family, pneumolysin (PLY) is a major virulence factor of Streptococcus pneumoniae, and the mechanism via which PLY binds to its putative receptor or cholesterol on the cell membrane is still poorly understood. Here, we demonstrated that PLY interacted with carbohydrate moiety and cholesterol as a component of the cell membrane, using the inhibitory effect of hemolytic activity. The hemolytic activity of PLY was inhibited by cholesterol-MβCD, which is in a 3β configuration at the C3-hydroxy group, but is not in a 3α-configuration. In the interaction between PLY and carbohydrate moiety, the mannose showed a dose-dependent increase in the inhibition of PLY hemolytic activity. The binding ability of mannose with truncated PLYs, as determined by the pull-down assay, showed that mannose might favor binding to domain 4 rather than domains 1-3. These studies provide a new model for the mechanism of cellular recognition by PLY, as well as a foundation for future investigations into whether non-sterol molecules can serve as receptors for other members of the CDC family of toxins. Copyright © 2012 Elsevier Inc. All rights reserved.

Pitfalls in the detection of cholesterol in Huntington's disease models.

PubMed

Marullo, Manuela; Valenza, Marta; Leoni, Valerio; Caccia, Claudio; Scarlatti, Chiara; De Mario, Agnese; Zuccato, Chiara; Di Donato, Stefano; Carafoli, Ernesto; Cattaneo, Elena

2012-10-11

Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington's disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods show reduced levels of cholesterol precursors and cholesterol in HD cells and in the brains of several HD animal models. Abnormal brain cholesterol homeostasis was also inferred from studies in HD patients. In contrast, colorimetric and enzymatic methods indicate cholesterol accumulation in HD cells and tissues. Here we used several methods to investigate cholesterol levels in cultured cells in the presence or absence of mutant HTT protein. Results Colorimetric and enzymatic methods with low sensitivity gave variable results, whereas results from a sensitive analytical method, gas chromatography-mass spectrometry, were more reliable. Sample preparation, high cell density and cell clonality also influenced the detection of intracellular cholesterol. Conclusions Detection of cholesterol in HD samples by colorimetric and enzymatic assays should be supplemented by detection using more sensitive analytical methods. Care must be taken to prepare the sample appropriately. By evaluating lathosterol levels using isotopic dilution mass spectrometry, we confirmed reduced cholesterol biosynthesis in knock-in cells expressing the polyQ mutation in a constitutive or inducible manner. *Correspondence should be addressed to Elena Cattaneo: elena.cattaneo@unimi.it.

Disparities in Intratumoral Steroidogenesis

DTIC Science & Technology

2014-07-01

shown), but does raise cholesterol levels significantly(18-22) (Fig 5). The diets are used with and without ezetimibe , a cholesterol reducing drug...yielding 4 base diet groups: 1) LFNC; 2) LFNC + ezetimibe (30 mg/kg/day); 3) HFHC; and 4) HFHC + ezetimibe (30 mg/kg/day). Critical comments...Serum Cholesterol Levels. Mice were fed either high fat, high cholesterol (HFHC) or a low fat, no cholesterol (LFNC) diet ± ezetimibe (Z) and bled

Non-Cholesterol Sterol Levels Predict Hyperglycemia and Conversion to Type 2 Diabetes in Finnish Men

PubMed Central

Cederberg, Henna; Gylling, Helena; Miettinen, Tatu A.; Paananen, Jussi; Vangipurapu, Jagadish; Pihlajamäki, Jussi; Kuulasmaa, Teemu; Stančáková, Alena; Smith, Ulf; Kuusisto, Johanna; Laakso, Markku

2013-01-01

We investigated the levels of non-cholesterol sterols as predictors for the development of hyperglycemia (an increase in the glucose area under the curve in an oral glucose tolerance test) and incident type 2 diabetes in a 5-year follow-up study of a population-based cohort of Finnish men (METSIM Study, N = 1,050) having non-cholesterol sterols measured at baseline. Additionally we determined the association of 538,265 single nucleotide polymorphisms (SNP) with non-cholesterol sterol levels in a cross-sectional cohort of non-diabetic offspring of type 2 diabetes (the Kuopio cohort of the EUGENE2 Study, N = 273). We found that in a cross-sectional METSIM Study the levels of sterols indicating cholesterol absorption were reduced as a function of increasing fasting glucose levels, whereas the levels of sterols indicating cholesterol synthesis were increased as a function of increasing 2-hour glucose levels. A cholesterol synthesis marker desmosterol significantly predicted an increase, and two absorption markers (campesterol and avenasterol) a decrease in the risk of hyperglycemia and incident type 2 diabetes in a 5-year follow-up of the METSIM cohort, mainly attributable to insulin sensitivity. A SNP of ABCG8 was associated with fasting plasma glucose levels in a cross-sectional study but did not predict hyperglycemia or incident type 2 diabetes. In conclusion, the levels of some, but not all non-cholesterol sterols are markers of the worsening of hyperglycemia and type 2 diabetes. PMID:23840693

The role of antisense oligonucleotide therapy in patients with familial hypercholesterolemia: risks, benefits, and management recommendations.

PubMed

Agarwala, Anandita; Jones, Peter; Nambi, Vijay

2015-01-01

Antisense oligonucleotide therapy is a promising approach for the treatment of a broad variety of medical conditions. It functions at the cellular level by interfering with RNA function, often leading to degradation of specifically targeted abnormal gene products implicated in the disease process. Mipomersen is a novel antisense oligonucleotide directed at apolipoprotein (apoB)-100, the primary apolipoprotein associated with low-density lipoprotein cholesterol (LDL-C), which has recently been approved for the treatment of familial hypercholesterolemia. A number of clinical studies have demonstrated its efficacy in lowering LDL-C and apoB levels in patients with elevated LDL-C despite maximal medical therapy using conventional lipid-lowering agents. This review outlines the risks and benefits of therapy and provides recommendations on the use of mipomersen.

Requirement of cholesterol in the viral envelope for dengue virus infection.

PubMed

Carro, Ana C; Damonte, Elsa B

2013-06-01

The role of cholesterol in the virus envelope or in the cellular membranes for dengue virus (DENV) infection was examined by depletion with methyl-beta-cyclodextrin (MCD) or nystatin. Pretreatment of virions with MCD or nystatin significantly reduced virus infectivity in a dose-dependent manner. By contrast, pre-treatment of diverse human cell lines with MCD or nystatin did not affect DENV infection. The four DENV serotypes were similarly inactivated by cholesterol-extracting drugs and infectivity was partially rescued when virion suspensions were treated with MCD in the presence of bovine serum. The addition of serum or exogenous water-soluble cholesterol after MCD treatment did not produce a reversion of MCD inactivating effect. Furthermore, virion treatment with extra cholesterol exerted also a virucidal effect. Binding and uptake of cholesterol-deficient DENV into the host cell were not impaired, whereas the next step of fusion between virion envelope and endosome membrane leading to virion uncoating and release of nucleocapsids to the cytoplasm appeared to be prevented, as determined by the retention of capsid protein in cells infected with MCD inactivated-DENV virions. Thereafter, the infection was almost completely inhibited, given the failure of viral RNA synthesis and viral protein expression in cells infected with MCD-treated virions. These data suggest that envelope cholesterol is a critical factor in the fusion process for DENV entry. Copyright © 2013 Elsevier B.V. All rights reserved.

Cholesterol depletion induces dynamic confinement of the G-protein coupled serotonin(1A) receptor in the plasma membrane of living cells.

PubMed

Pucadyil, Thomas J; Chattopadhyay, Amitabha

2007-03-01

Cholesterol is an essential constituent of eukaryotic membranes and plays a crucial role in membrane organization, dynamics, function, and sorting. It is often found distributed non-randomly in domains or pools in biological and model membranes and is thought to contribute to a segregated distribution of membrane constituents. Signal transduction events mediated by seven transmembrane domain G-protein coupled receptors (GPCRs) are the primary means by which cells communicate with and respond to their external environment. We analyzed the role of cholesterol in the plasma membrane organization of the G-protein coupled serotonin(1A) receptor by fluorescence recovery after photobleaching (FRAP) measurements with varying bleach spot sizes. Our results show that lateral diffusion parameters of serotonin(1A) receptors in normal cells are consistent with models describing diffusion of molecules in a homogenous membrane. Interestingly, these characteristics are altered in cholesterol-depleted cells in a manner that is consistent with dynamic confinement of serotonin(1A) receptors in the plasma membrane. Importantly, analysis of ligand binding and downstream signaling of the serotonin(1A) receptor suggests that receptor function is affected in a significantly different manner when intact cells or isolated membranes are depleted of cholesterol. These results assume significance in the context of interpreting effects of cholesterol depletion on diffusion characteristics of membrane proteins in particular, and cholesterol-dependent cellular processes in general.

Antilithiasic and Hypolipidaemic Effects of Raphanus sativus L. var. niger on Mice Fed with a Lithogenic Diet

PubMed Central

Castro-Torres, Ibrahim Guillermo; Naranjo-Rodríguez, Elia Brosla; Domínguez-Ortíz, Miguel Ángel; Gallegos-Estudillo, Janeth; Saavedra-Vélez, Margarita Virginia

2012-01-01

In Mexico, Raphanus sativus L. var. niger (black radish) has uses for the treatment of gallstones and for decreasing lipids serum levels. We evaluate the effect of juice squeezed from black radish root in cholesterol gallstones and serum lipids of mice. The toxicity of juice was analyzed according to the OECD guidelines. We used female C57BL/6 mice fed with a lithogenic diet. We performed histopathological studies of gallbladder and liver, and measured concentrations of cholesterol, HDL cholesterol and triglycerides. The juice can be considered bioactive and non-toxic; the lithogenic diet significantly induced cholesterol gallstones; increased cholesterol and triglycerides levels, and decreased HDL levels; gallbladder wall thickness increased markedly, showing epithelial hyperplasia and increased liver weight. After treatment with juice for 6 days, cholesterol gallstones were eradicated significantly in the gallbladder of mice; cholesterol and triglycerides levels decreased too, and there was also an increase in levels of HDL (P < 0.05). Gallbladder tissue continued to show epithelial hyperplasia and granulocyte infiltration; liver tissue showed vacuolar degeneration. The juice of black radish root has properties for treatment of cholesterol gallstones and for decreasing serum lipids levels; therefore, we confirm in a preclinical study the utility that people give it in traditional medicine. PMID:23093836

Hypercholesterolemia induces angiogenesis and accelerates growth of breast tumors in vivo.

PubMed

Pelton, Kristine; Coticchia, Christine M; Curatolo, Adam S; Schaffner, Carl P; Zurakowski, David; Solomon, Keith R; Moses, Marsha A

2014-07-01

Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

A new HDL mimetic peptide that stimulates cellular cholesterol efflux with high efficiency greatly reduces atherosclerosis in mice

PubMed Central

Bielicki, John K.; Zhang, Haiyan; Cortez, Yuan; Zheng, Ying; Narayanaswami, Vasanthy; Patel, Arti; Johansson, Jan; Azhar, Salman

2010-01-01

Here, we report the creation of a single-helix peptide (ATI-5261) that stimulates cellular cholesterol efflux with Km molar efficiency approximating native apolipoproteins. Anti-atherosclerosis activity of ATI-5261 was evaluated in LDLR−/− and apolipoprotein (apo)E−/− mice ∼5–7 months of age, following 13–18 weeks on a high-fat Western diet (HFWD). Treatment of fat-fed LDLR−/− mice with daily intraperitoneal injections of ATI-5261 (30 mg/kg) for 6 weeks reduced atherosclerosis by 30%, as judged by lesion area covering the aorta (7.9 ± 2 vs.11.3 ± 2.5% control, P = 0.011) and lipid-content of aortic sinus plaque (25 ± 5.8 vs. 33 ± 4.9% control, P = 0.014). In apoE−/− mice, the peptide administered 30 mg/kg ip on alternate days for 6 weeks reduced atherosclerosis by ∼45% (lesion area = 15 ± 7 vs. 25 ± 8% control, P = 0.00016; plaque lipid-content = 20 ± 6 vs. 32 ± 8% control, P < 0.0001). Similar reductions in atherosclerosis were achieved using ATI-5261:POPC complexes. Single intraperitoneal injection of ATI-5261 increased reverse cholesterol transport from macrophage foam-cells to feces over 24–48 h. In summary, relatively short-term treatment of mice with the potent cholesterol efflux peptide ATI-5261 reduced substantial atherosclerosis. This was achieved using an L-amino acid peptide, in the presence of severe hypercholesterolemia/HFWD, and did not require daily injections or formulation with phospholipids when administered via intraperitoneal injection. PMID:20075422

Association of common JAK2 variants with body fat, insulin sensitivity and lipid profile

PubMed Central

Ge, Dongliang; Gooljar, Sakina B; Kyriakou, Theodosios; Collins, Laura J; Swaminathan, Ramasamyiyer; Snieder, Harold; Spector, Tim D; O'Dell, Sandra D

2007-01-01

The leptin signal is transduced via the JAK2-STAT3 pathway at the leptin receptor. JAK2 also phosphorylates IRS, integral to insulin and leptin action and is required for optimum ABCA1-dependent transport of lipids from cells to apoA-I. We hypothesised that common variation in the JAK2 gene may be associated with body fat, insulin sensitivity and modulation of the serum lipid profile in the general population. Ten tagging SNPs spanning the gene were genotyped in 2760 Caucasian female twin subjects (mean age 47.3±12.6 years) from the St Thomas' UK Adult Twin Registry (Twins UK). Minor allele frequencies were between 0.170 and 0.464. The major allele of rs7849191 was associated with higher central fat (P=0.030), % central fat (P=0.014) and waist circumference (P=0.027) and the major allele of rs3780378 with higher serum apoA (P=0.026), total cholesterol (P=0.014) and LDL cholesterol (P=0.012) and lower triglyceride (P=0.023). However, no associations were significant at a level which took account of multiple testing. Although JAK2 is a critical element in leptin and insulin signalling and has a role in cellular cholesterol transport, we failed to establish associations of common SNPs with relevant phenotypes in this human study. PMID:18239666

Effects of zinc and cholesterol/choleate on serum lipoproteins and the liver in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, C.H.; Chen, S.M.; Ogle, C.W.

1989-01-01

The effects of short-term treatment with orally-administered zinc sulfate and/or a mixture of cholesterol/choleate on serum lipoprotein and hepatic enzyme levels were studied. Administration of graded doses of zinc sulfate for 5 days, dose-dependently increased serum and hepatic zinc levels but depressed the serum high-density lipoprotein-cholesterol (HDL-C) concentration and liver cytochrome P-450 activity. However, it did not affect hepatic concentrations of malondialdehyde and free {beta}-glucuronidase. Cholesterol/choleate treatment for 5 days markedly damaged the liver, as reflected by elevations of hepatic concentrations of malondialdehyde (both in the mitochondrial and microsomal fractions) and of free {beta}-glucuronidase; total cholesterol and low-density lipoprotein-cholesterol inmore » the blood were increased, whereas HDL-C was decreased significantly. Concomitant administration of zinc sulfate with cholesterol/choleate further lowered HDL-C levels, but reversed the high hepatic concentrations of both malondialdehyde and free {beta}-glucuronidase. The present study indicates that both zinc ions and cholesterol can decrease circulatory HDL-C levels and that zinc protects against cholesterol-induced hepatic damage by reducing lysosomal enzyme release and preventing lipid peroxidation in the liver.« less

Reduction in levels of 24S-hydroxycholesterol by statin treatment in patients with Alzheimer disease.

PubMed

Vega, Gloria Lena; Weiner, Myron F; Lipton, Anne M; Von Bergmann, Klaus; Lutjohann, Dieter; Moore, Carol; Svetlik, Doris

2003-04-01

The statin treatment of dyslipidemia is associated with a reduced risk of development of Alzheimer disease (AD). The effect may be mediated by a reduction in cholesterol biosynthesis in the brain, by lowering levels of apolipoprotein E (apo E)-containing lipoproteins, or by pleitropic effects such as reduction in beta-amyloid production. In the brain, cholesterol from damaged or dying neurons is converted to 24S-hydroxycholesterol by cholesterol 24-hydroxylase (CYP46). The oxysterol is subsequently transferred across the blood-brain barrier, transported to the liver by low-density lipoproteins (LDLs), and excreted as bile acids. Most of plasma 24S-hydroxycholesterol is derived from brain cholesterol; consequently, plasma levels of the oxysterol reflect brain cholesterol catabolism. To examine the effect of 3 statins and a nonstatin hypolipidemic agent on plasma levels of 24S-hydroxycholesterol and apo E in patients with AD. The study had a sequential parallel design. It was open-labeled and involved lipoprotein and 24S-hydroxycholesterol evaluations at baseline and at 6 weeks of treatment with 40 mg of lovastatin, simvastatin, or pravastatin sodium per day, or 1 g of extended-release niacin per day. Blood samples were drawn after a 12-hour fast for measurement of plasma sterols, oxysterols, lipoprotein cholesterol, and levels of apo E, plasma transaminases, and glucose. Measurements were made at baseline and during treatment. Statin treatment reduced levels of plasma lathosterol by 49.5%, 24S-hydroxycholesterol by 21.4%, LDL cholesterol by 34.9%, and total cholesterol by 25%. The ratios of lathosterol-campesterol and 24S-hydroxycholesterol-LDL cholesterol were reduced significantly, but the ratio of 24S-hydroxycholesterol-total cholesterol was unchanged. Extended-release niacin also significantly reduced levels of 24S-hydroxycholesterol by 10% and LDL cholesterol by 18.1%. None of the agents lowered plasma concentration of apo E. Statins lowered levels of plasma 24S-hydroxycholesterol without affecting levels of apo E. The LDL lowering was more pronounced than 24S-hydroxycholesterol reductions. The effect of statins on LDL partially explains the reduction of plasma oxysterol level.

Quantitation of the rates of hepatic and intestinal cholesterol synthesis in lysosomal acid lipase-deficient mice before and during treatment with ezetimibe.

PubMed

Chuang, Jen-Chieh; Lopez, Adam M; Turley, Stephen D

2017-07-01

Esterified cholesterol (EC) and triglycerides, contained within lipoproteins taken up by cells, are hydrolysed by lysosomal acid lipase (LAL) in the late endosomal/lysosomal (E/L) compartment. The resulting unesterified cholesterol (UC) is transported via Niemann-Pick type C2 and C1 into the cytosolic compartment where it enters a putative pool of metabolically active cholesterol that is utilized in accordance with cellular needs. Loss-of-function mutations in LIPA, the gene encoding LAL, result in dramatic increases in tissue concentrations of EC, a hallmark feature of Wolman disease and cholesteryl ester storage disease (CESD). The lysosomal sequestration of EC causes cells to respond to a perceived deficit of sterol by increasing their rate of cholesterol synthesis, particularly in the liver. A similar compensatory response occurs with treatments that disrupt the enterohepatic movement of cholesterol or bile acids. Here we measured rates of cholesterol synthesis in vivo in the liver and small intestine of a mouse model for CESD given the cholesterol absorption inhibitor ezetimibe from weaning until early adulthood. Consistent with previous findings, this treatment significantly reduced the amount of EC sequestered in the liver (from 132.43±7.35 to 70.07±6.04mg/organ) and small intestine (from 2.78±0.21 to 1.34±0.09mg/organ) in the LAL-deficient mice even though their rates of hepatic and intestinal cholesterol synthesis were either comparable to, or exceeded those in matching untreated Lal -/- mice. These data reveal the role of intestinal cholesterol absorption in driving the expansion of tissue EC content and disease progression in LAL deficiency. Copyright © 2017 Elsevier Inc. All rights reserved.

Exchanging partially hydrogenated fat for palmitic acid in the diet increases LDL-cholesterol and endogenous cholesterol synthesis in normocholesterolemic women.

PubMed

Sundram, Kalyana; French, Margaret A; Clandinin, M Thomas

2003-08-01

Partial hydrogenation of oil results in fats containing unusual isomeric fatty acids characterized by cis and trans configurations. Hydrogenated fats containing trans fatty acids increase plasma total cholesterol (TC) and LDL-cholesterol while depressing HDL-cholesterol levels. Identifying the content of trans fatty acids by food labeling is overshadowed by a reluctance of health authorities to label saturates and trans fatty acids separately. Thus, it is pertinent to compare the effects of trans to saturated fatty acids using stable isotope methodology to establish if the mechanism of increase in TC and LDL-cholesterol is due to the increase in the rate of endogenous synthesis of cholesterol. Ten healthy normocholesterolemic female subjects consumed each of two diets containing approximately 30% of energy as fat for a fourweek period. One diet was high in palmitic acid (10.6% of energy) from palm olein and the other diet exchanged 5.6% of energy as partially hydrogenated fat for palmitic acid. This fat blend resulted in monounsaturated fatty acids decreasing by 4.9 % and polyunsaturated fats increasing by 2.7%. The hydrogenated fat diet treatment provided 3.1% of energy as elaidic acid. For each dietary treatment, the fractional synthesis rates for cholesterol were measured using deuterium-labeling procedures and blood samples were obtained for blood lipid and lipoprotein measurements. Subjects exhibited a higher total cholesterol and LDL-cholesterol level when consuming the diet containing trans fatty acids while also depressing the HDL-cholesterol level. Consuming the partially hydrogenated fat diet treatment increased the fractional synthesis rate of free cholesterol. Consumption of hydrogenated fats containing trans fatty acids in comparison to a mixtur e of palmitic and oleic acids increase plasma cholesterol levels apparently by increasing endogenous synthesis of cholesterol.

Neopterin negatively regulates expression of ABCA1 and ABCG1 by the LXRα signaling pathway in THP-1 macrophage-derived foam cells.

PubMed

Yan, Jin-quan; Tan, Chun-zhi; Wu, Jin-hua; Zhang, Dong-cui; Chen, Ji-ling; Zeng, Bin-yuan; Jiang, Yu-ping; Nie, Jin; Liu, Wei; Liu, Qin; Dai, Hao

2013-07-01

To investigate the effects of neopterin on ABCA1 expression and cholesterol efflux in human THP-1 macrophage-derived foam cells, and to explore the role of the liver X receptor alpha (LXRα) involved. In the present study, THP-1 cells were pre-incubated with ox-LDL to become foam cells. The protein and mRNA expression were examined by Western blot assays and real-time quantitative PCR, respectively. Liquid scintillation counting and high performance liquid chromatography assays were used to test cellular cholesterol efflux and cholesterol content. Neopterin decreased ABCA1 expression and cholesterol efflux in a time- and concentration-dependent manner in THP-1 macrophage-derived foam cells, and the LXRα siRNA can reverse the inhibitory effects induced by neopterin. Neoterin has a negative regulation on ABCA1 expression via the LXRα signaling pathway, which suggests the aggravated effects of neopterin on atherosclerosis.

Transcriptional Regulation of T-Cell Lipid Metabolism: Implications for Plasma Membrane Lipid Rafts and T-Cell Function.

PubMed

Robinson, George A; Waddington, Kirsty E; Pineda-Torra, Ines; Jury, Elizabeth C

2017-01-01

It is well established that cholesterol and glycosphingolipids are enriched in the plasma membrane (PM) and form signaling platforms called lipid rafts, essential for T-cell activation and function. Moreover, changes in PM lipid composition affect the biophysical properties of lipid rafts and have a role in defining functional T-cell phenotypes. Here, we review the role of transcriptional regulators of lipid metabolism including liver X receptors α/β, peroxisome proliferator-activated receptor γ, estrogen receptors α/β (ERα/β), and sterol regulatory element-binding proteins in T-cells. These receptors lie at the interface between lipid metabolism and immune cell function and are endogenously activated by lipids and/or hormones. Importantly, they regulate cellular cholesterol, fatty acid, glycosphingolipid, and phospholipid levels but are also known to modulate a broad spectrum of immune responses. The current evidence supporting a role for lipid metabolism pathways in controlling immune cell activation by influencing PM lipid raft composition in health and disease, and the potential for targeting lipid biosynthesis pathways to control unwanted T-cell activation in autoimmunity is reviewed.

Transcriptional Regulation of T-Cell Lipid Metabolism: Implications for Plasma Membrane Lipid Rafts and T-Cell Function

PubMed Central

Robinson, George A.; Waddington, Kirsty E.; Pineda-Torra, Ines; Jury, Elizabeth C.

2017-01-01

It is well established that cholesterol and glycosphingolipids are enriched in the plasma membrane (PM) and form signaling platforms called lipid rafts, essential for T-cell activation and function. Moreover, changes in PM lipid composition affect the biophysical properties of lipid rafts and have a role in defining functional T-cell phenotypes. Here, we review the role of transcriptional regulators of lipid metabolism including liver X receptors α/β, peroxisome proliferator-activated receptor γ, estrogen receptors α/β (ERα/β), and sterol regulatory element-binding proteins in T-cells. These receptors lie at the interface between lipid metabolism and immune cell function and are endogenously activated by lipids and/or hormones. Importantly, they regulate cellular cholesterol, fatty acid, glycosphingolipid, and phospholipid levels but are also known to modulate a broad spectrum of immune responses. The current evidence supporting a role for lipid metabolism pathways in controlling immune cell activation by influencing PM lipid raft composition in health and disease, and the potential for targeting lipid biosynthesis pathways to control unwanted T-cell activation in autoimmunity is reviewed. PMID:29225604

Anti-Obesity Property of Lichen Thamnolia vermicularis Extract in 3T3-L1 Cells and Diet-Induced Obese Mice

PubMed Central

Choi, Ra-Yeong; Ham, Ju Ri; Yeo, Jiyoung; Hur, Jae-Seoun; Park, Seok-Kyu; Kim, Myung-Joo; Lee, Mi-Kyung

2017-01-01

Thamnolia vermicularis (TV) is an edible lichen that is prevalent in the alpine zone of East Asia. This study evaluated the feasibility of using TV acetone extracts as a functional food based on experiments using cell line and obese mice. The cellular triglyceride levels and Oil red O staining of 3T3-L1 cells indicated that TV extracts (5 and 10 μg/mL) dose-dependently suppressed adipocyte differentiation and lipid accumulation compared with the control. The TV extract (0.4%, w/w) in a high-fat diet (HFD) was supplemented to C57BL/6N mice for 12 weeks, and TV extract supplement significantly reduced visceral fat mass and body weight compared with HFD feeding alone. The TV extract also induced significant decreases in serum and hepatic lipids, whereas it increased the serum high-density lipoproteins-cholesterol/total cholesterol ratio and fecal lipids levels. Moreover, the TV extract led to significantly lower homeostasis model assessment of insulin resistance in diet-induced obese mice. Taken together, these results suggest that the TV extract may have anti-obesity effects, including lipid-lowering, and it is a natural resource with the potential for use in obesity management. PMID:29333380

The Canadian experience: why Canada decided against an upper limit for cholesterol.

PubMed

McDonald, Bruce E

2004-12-01

Canada, like the United States, held a "consensus conference on cholesterol" in 1988. Although the final report of the consensus panel recommended that total dietary fat not exceed 30 percent and saturated fat not exceed 10 percent of total energy intake, it did not specify an upper limit for dietary cholesterol. Similarly, the 1990, Health Canada publication "Nutrition Recommendations: The Report of the Scientific Review Committee" specified upper limits for total and saturated fat in the diet but did not specify an upper limit for cholesterol. Canada's Guidelines for Healthy Eating, a companion publication from Health Canada, suggested that Canadians "choose low-fat dairy products, lean meats, and foods prepared with little or no fat" while enjoying "a variety of foods." Many factors contributed to this position but a primary element was the belief that total dietary fat and saturated fat were primary dietary determinants of serum total and low-density lipoprotein (LDL) cholesterol levels, not dietary cholesterol. Hence, Canadian health authorities focused on reducing saturated fat and trans fats in the Canadian diet to help lower blood cholesterol levels rather than focusing on limiting dietary cholesterol. In an effort to allay consumer concern with the premise that blood cholesterol level is linked to dietary cholesterol, organizations such as the Canadian Egg Marketing Agency (CEMA) reminded health professionals, including registered dietitians, family physicians and nutrition educators, of the extensive data showing that there is little relationship between dietary cholesterol intake and cardiovascular mortality. In addition, it was pointed out that for most healthy individuals, endogenous synthesis of cholesterol by the liver adjusts to the level of dietary cholesterol intake. Educating health professionals about the relatively weak association between dietary cholesterol and the relatively strong association between serum cholesterol and saturated fat and trans fats helped keep consumers informed about healthy diets and ways to control blood cholesterol.

Cholesterol Level: Can It Be Too Low?

MedlinePlus

... total cholesterol level has been associated with some health problems. Doctors are still trying to find out more about the connection between low cholesterol and health risks. There is no consensus on how to ...

Lysosomal pH-inducible supramolecular dissociation of polyrotaxanes possessing acid-labile N-triphenylmethyl end groups and their therapeutic potential for Niemann-Pick type C disease

NASA Astrophysics Data System (ADS)

Tamura, Atsushi; Nishida, Kei; Yui, Nobuhiko

2016-01-01

Niemann-Pick type C (NPC) disease is characterized by the accumulation of cholesterol in lysosomes. We have previously reported that biocleavable polyrotaxanes (PRXs) composed of β-cyclodextrins (β-CDs) threaded onto a linear polymer capped with bulky stopper molecules via intracellularly cleavable linkers show remarkable cholesterol reducing effects in NPC disease patient-derived fibroblasts owing to the stimuli-responsive intracellular dissociation of PRXs and subsequent β-CD release from the PRXs. Herein, we describe a series of novel acid-labile 2-(2-hydroxyethoxy)ethyl group-modified PRXs (HEE-PRXs) bearing terminal N-triphenylmethyl (N-Trt) groups as a cleavable component for the treatment of NPC disease. The N-Trt end groups of the HEE-PRXs underwent acidic pH-induced cleavage and led to the dissociation of their supramolecular structure. A kinetic study revealed that the number of HEE groups on the PRX did not affect the cleavage kinetics of the N-Trt end groups of the HEE-PRXs. The effect of the number of HEE groups of the HEE-PRXs, which was modified to impart water solubility to the PRXs, on cellular internalization efficiency, lysosomal localization efficiency, and cholesterol reduction ability in NPC disease-derived fibroblasts (NPC1 fibroblasts) was also investigated. The cellular uptake and lysosomal localization efficiency were almost equivalent for HEE-PRXs with different numbers of HEE groups. However, the cholesterol reducing ability of the HEE-PRXs in NPC1 fibroblasts was affected by the number of HEE groups, and HEE-PRXs with a high number of HEE groups were unable to reduce lysosomal cholesterol accumulation. This deficiency is most likely due to the cholesterol-solubilizing ability of HEE-modified β-CDs released from the HEE-PRXs. We conclude that the N-Trt group acts as a cleavable component to induce the lysosomal dissociation of HEE-PRXs, and acid-labile HEE-PRXs with an optimal number of HEE groups (4.1 to 5.4 HEE groups per single β-CD threaded onto the PRX) have great therapeutic potential for treating NPC disease.

Characterization of the Role of a Highly Conserved Sequence in ATP Binding Cassette Transporter G (ABCG) Family in ABCG1 Stability, Oligomerization, and Trafficking

PubMed Central

2013-01-01

ATP-binding cassette transporter G1 (ABCG1) mediates cholesterol and oxysterol efflux onto lipidated lipoproteins and plays an important role in macrophage reverse cholesterol transport. Here, we identified a highly conserved sequence present in the five ABCG transporter family members. The conserved sequence is located between the nucleotide binding domain and the transmembrane domain and contains five amino acid residues from Asn at position 316 to Phe at position 320 in ABCG1 (NPADF). We found that cells expressing mutant ABCG1, in which Asn316, Pro317, Asp319, and Phe320 in the conserved sequence were replaced with Ala simultaneously, showed impaired cholesterol efflux activity compared with wild type ABCG1-expressing cells. A more detailed mutagenesis study revealed that mutation of Asn316 or Phe 320 to Ala significantly reduced cellular cholesterol and 7-ketocholesterol efflux conferred by ABCG1, whereas replacement of Pro317 or Asp319 with Ala had no detectable effect. To confirm the important role of Asn316 and Phe320, we mutated Asn316 to Asp (N316D) and Gln (N316Q), and Phe320 to Ile (F320I) and Tyr (F320Y). The mutant F320Y showed the same phenotype as wild type ABCG1. However, the efflux of cholesterol and 7-ketocholesterol was reduced in cells expressing ABCG1 mutant N316D, N316Q, or F320I compared with wild type ABCG1. Further, mutations N316Q and F320I impaired ABCG1 trafficking while having no marked effect on the stability and oligomerization of ABCG1. The mutant N316Q and F320I could not be transported to the cell surface efficiently. Instead, the mutant proteins were mainly localized intracellularly. Thus, these findings indicate that the two highly conserved amino acid residues, Asn and Phe, play an important role in ABCG1-dependent export of cellular cholesterol, mainly through the regulation of ABCG1 trafficking. PMID:24320932

Laser-induced lipolysis on adipose cells

NASA Astrophysics Data System (ADS)

Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

2004-10-01

Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

Maternal-fetal cholesterol transport in the second half of mouse pregnancy does not involve LDL receptor-related protein 2.

PubMed

Zwier, M V; Baardman, M E; van Dijk, T H; Jurdzinski, A; Wisse, L J; Bloks, V W; Berger, R M F; DeRuiter, M C; Groen, A K; Plösch, T

2017-08-01

LDL receptor-related protein type 2 (LRP2) is highly expressed on both yolk sac and placenta. Mutations in the corresponding gene are associated with severe birth defects in humans, known as Donnai-Barrow syndrome. We here characterized the contribution of LRP2 and maternal plasma cholesterol availability to maternal-fetal cholesterol transport and fetal cholesterol levels in utero in mice. Lrp2 +/- mice were mated heterozygously to yield fetuses of all three genotypes. Half of the dams received a 0.5% probucol-enriched diet during gestation to decrease maternal HDL cholesterol. At E13.5, the dams received an injection of D7-labelled cholesterol and were provided with 1- 13 C acetate-supplemented drinking water. At E16.5, fetal tissues were collected and maternal cholesterol transport and fetal synthesis quantified by isotope enrichments in fetal tissues by GC-MS. The Lrp2 genotype did not influence maternal-fetal cholesterol transport and fetal cholesterol. However, lowering of maternal plasma cholesterol levels by probucol significantly reduced maternal-fetal cholesterol transport. In the fetal liver, this was associated with increased cholesterol synthesis rates. No indications were found for an interaction between the Lrp2 genotype and maternal probucol treatment. Maternal-fetal cholesterol transport and endogenous fetal cholesterol synthesis depend on maternal cholesterol concentrations but do not involve LRP2 in the second half of murine pregnancy. Our results suggest that the mouse fetus can compensate for decreased maternal cholesterol levels. It remains a relevant question how the delicate system of cholesterol transport and synthesis is regulated in the human fetus and placenta. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Pharmacological activation of LXRs decreases amyloid-β levels in Niemann-Pick type C model cells.

PubMed

Stefulj, Jasminka; Peric, Maja; Malnar, Martina; Kosicek, Marko; Schweinzer, Cornelia; Zivkovic, Jelena; Scholler, Monika; Panzenboeck, Ute; Hecimovic, Silva

2013-01-01

Niemann-Pick type C disease (NPC) is an inherited disorder mainly caused by loss-of-function mutations in the NPC1 gene, that lead to intracellular cholesterol accumulation and disturbed cholesterol homeostasis. Similarly to Alzheimer's disease (AD), NPC is associated with progressive neurodegeneration and altered metabolism of amyloid precursor protein (APP). Liver X receptors (LXRs), the key transcriptional regulators of cholesterol homeostasis, were reported to play neuroprotective roles in NPC mice. We investigated the impacts of LXRs on APP metabolism in mutant CHO cells lacking the NPC1 gene (-NPC1 cells). Pharmacological activation of LXRs in -NPC1 cells tended to reduce the ratio of total secreted APP (sAPP) to full length APP (flAPP) levels and sAPPβ levels as well as to increase the ratio of APP Cterminal fragments to flAPP levels, resulting in decreased levels of amyloid β (Aβ) peptides. -NPC1 cells treated with LXR agonist TO901317 (TO90) displayed a modest increase in cholesterol efflux to apolipoprotein A-I (apoA-I) but not to HDL3, or in the absence of extracellular cholesterol acceptors. The observed similar reduction of Aβ levels upon TO90 treatment in the presence or in the absence of extracellular apoA-I indicated a cholesterol-efflux independent effect of TO90 on Aβ levels. Furthermore, TO90 had no effect on the cholesterol synthesis rate in -NPC1 cells, while it reduced the rate of cholesterol esterification. The obtained results indicate that LXR activation may decrease Aβ levels in NPC1- deficient conditions. The underlying mechanism of this action does not appear to be related to effects on cholesterol efflux or synthesis rates.

Hypocholesterolemic effect of sericin-derived oligopeptides in high-cholesterol fed rats.

PubMed

Lapphanichayakool, Phakhamon; Sutheerawattananonda, Manote; Limpeanchob, Nanteetip

2017-01-01

The beneficial effect of cholesterol-lowering proteins and/or peptides derived from various dietary sources is continuously reported. A non-dietary protein from silk cocoon, sericin, has also demonstrated cholesterol-lowering activity. A sericin hydrolysate prepared by enzymatic hydrolysis was also expected to posses this effect. The present study was aimed at investigating the cholesterol-lowering effect of sericin peptides, so called "sericin-derived oligopeptides" (SDO) both in vivo and in vitro. The results showed that SDO at all three doses tested (10 mg kg -1  day -1 , 50 mg kg -1  day -1 , and 200 mg kg -1  day -1 ) suppressed serum total and non-HDL cholesterol levels in rats fed a high-cholesterol diet. Triglyceride and HDL-cholesterol levels were not significantly changed among all groups. The fecal contents of bile acids and cholesterol did not differ among high-cholesterol fed rats. SDO dose-dependently reduced cholesterol solubility in lipid micelles, and inhibited cholesterol uptake in monolayer Caco-2 cells. SDO also effectively bound to all three types of bile salts including taurocholate, deoxytaurocholate, and glycodeoxycholate. Direct interaction with bile acids of SDO may disrupt micellar cholesterol solubility, and subsequently reduce the absorption of dietary cholesterol in intestines. Taking all data together, SDO or sericin peptides exhibit a beneficial effect on blood cholesterol levels and could be potentially used as a health-promoting dietary supplement or nutraceutical product.

Serum Lipid Levels in Patients with Eating Disorders.

PubMed

Nakai, Yoshikatsu; Noma, Shun'ichi; Fukusima, Mitsuo; Taniguchi, Ataru; Teramukai, Satoshi

2016-01-01

Objective To evaluate some risk factors for cardiovascular diseases in feeding and eating disorders, the degree of lipid abnormalities was investigated in a large Japanese cohort of different groups of feeding and eating disorders, according to the Japan Atherosclerosis Society Guidelines for the Prevention of Atherosclerotic Cardiovascular Diseases 2012 (JAS Guidelines 2012). Methods Participants in the current study included 732 women divided into four groups of feeding and eating disorders: anorexia nervosa, restricting type (AN-R); anorexia nervosa, binge-eating/purging type; bulimia nervosa (BN); and binge-eating disorder (BED). We measured the serum levels of total cholesterol, high-density-lipoprotein (HDL) cholesterol, and triglyceride in these participants. Low-density-lipoprotein (LDL) cholesterol and non-HDL cholesterol levels were also calculated. Results The concentrations of LDL cholesterol and non-HDL cholesterol were widely distributed in all groups. When the LDL cholesterol risk was defined as ≥120 mg/dL and the non-HDL cholesterol risk as ≥150 mg/dL, according to the JAS Guidelines 2012, the proportion of LDL cholesterol risk ranged from 29.6% (BN) to 38.6% (AN-R), and the proportion of non-HDL cholesterol risk ranged from 17.8% (BN) to 30.1% (BED). Conclusion The present findings suggest the existence of LDL cholesterol risk and non-HDL cholesterol risk in all groups of eating disorders. Given the chronicity of this condition, the development of elevated concentrations of LDL cholesterol and non-HDL cholesterol at an early age may increase the risk of cardiovascular diseases.

Sterol Carrier Protein-2: Binding Protein for Endocannabinoids

PubMed Central

Liedhegner, Elizabeth Sabens; Vogt, Caleb D.; Sem, Daniel S.; Cunningham, Christopher W.

2015-01-01

The endocannabinoid (eCB) system, consisting of eCB ligands and the type 1 cannabinoid receptor (CB1R), subserves retrograde, activity-dependent synaptic plasticity in the brain. eCB signaling occurs “on-demand,” thus the processes regulating synthesis, mobilization and degradation of eCBs are also primary mechanisms for the regulation of CB1R activity. The eCBs, N-arachidonylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG), are poorly soluble in water. We hypothesize that their aqueous solubility, and, therefore, their intracellular and transcellular distribution, are facilitated by protein binding. Using in silico docking studies, we have identified the nonspecific lipid binding protein, sterol carrier protein 2 (SCP-2), as a potential AEA binding protein. The docking studies predict that AEA and AM404 associate with SCP-2 at a putative cholesterol binding pocket with ΔG values of −3.6 and −4.6 kcal/mol, respectively. These values are considerably higher than cholesterol (−6.62 kcal/mol) but consistent with a favorable binding interaction. In support of the docking studies, SCP-2-mediated transfer of cholesterol in vitro is inhibited by micromolar concentrations of AEA; and heterologous expression of SCP-2 in HEK 293 cells increases time-related accumulation of AEA in a temperature-dependent fashion. These results suggest that SCP-2 facilitates cellular uptake of AEA. However, there is no effect of SCP-2 transfection on the cellular accumulation of AEA determined at equilibrium or the IC50 values for AEA, AM404 or 2-AG to inhibit steady state accumulation of radiolabelled AEA. We conclude that SCP-2 is a low affinity binding protein for AEA that can facilitate its cellular uptake but does not contribute significantly to intracellular sequestration of AEA. PMID:24510313

Serum Cholesterol Levels in College Students: Opportunities for Education and Intervention.

ERIC Educational Resources Information Center

Sparling, Phillip B.; Snow, Teresa K.; Beavers, Bill D.

1999-01-01

Analyzed lipid profiles in 1,088 college students at a university where lipid profiles were available to students in selected health/wellness courses. Mean total cholesterol levels were similar for men and women, but men had significantly lower high-density lipoprotein cholesterol and higher low-density lipoprotein cholesterol than women. About 11…

Pitfalls in the detection of cholesterol in Huntington’s disease models

PubMed Central

Marullo, Manuela; Valenza, Marta; Leoni, Valerio; Caccia, Claudio; Scarlatti, Chiara; De Mario, Agnese; Zuccato, Chiara; Di Donato, Stefano; Carafoli, Ernesto; Cattaneo, Elena

2012-01-01

Background Abnormalities in brain cholesterol homeostasis have been reported in Huntington’s disease (HD), an adult-onset neurodegenerative disorder caused by an expansion in the number of CAG repeats in the huntingtin (HTT) gene. However, the results have been contradictory with respect to whether cholesterol levels increase or decrease in HD models. Biochemical and mass spectrometry methods show reduced levels of cholesterol precursors and cholesterol in HD cells and in the brains of several HD animal models. Abnormal brain cholesterol homeostasis was also inferred from studies in HD patients. In contrast, colorimetric and enzymatic methods indicate cholesterol accumulation in HD cells and tissues. Here we used several methods to investigate cholesterol levels in cultured cells in the presence or absence of mutant HTT protein. Results Colorimetric and enzymatic methods with low sensitivity gave variable results, whereas results from a sensitive analytical method, gas chromatography-mass spectrometry, were more reliable. Sample preparation, high cell density and cell clonality also influenced the detection of intracellular cholesterol. Conclusions Detection of cholesterol in HD samples by colorimetric and enzymatic assays should be supplemented by detection using more sensitive analytical methods. Care must be taken to prepare the sample appropriately. By evaluating lathosterol levels using isotopic dilution mass spectrometry, we confirmed reduced cholesterol biosynthesis in knock-in cells expressing the polyQ mutation in a constitutive or inducible manner. *Correspondence should be addressed to Elena Cattaneo: elena.cattaneo@unimi.it PMID:23145355

Royal Jelly Reduces Cholesterol Levels, Ameliorates Aβ Pathology and Enhances Neuronal Metabolic Activities in a Rabbit Model of Alzheimer's Disease.

PubMed

Pan, Yongming; Xu, Jianqin; Chen, Cheng; Chen, Fangming; Jin, Ping; Zhu, Keyan; Hu, Chenyue W; You, Mengmeng; Chen, Minli; Hu, Fuliang

2018-01-01

Alzheimer's disease (AD) is the most common form of dementia characterized by aggregation of amyloid β (Aβ) and neuronal loss. One of the risk factors for AD is high cholesterol levels, which are known to promote Aβ deposition. Previous studies have shown that royal jelly (RJ), a product of worker bees, has potential neuroprotective effects and can attenuate Aβ toxicity. However, little is known about how RJ regulates Aβ formation and its effects on cholesterol levels and neuronal metabolic activities. Here, we investigated whether RJ can reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in an AD rabbit model induced by 2% cholesterol diet plus copper drinking water. Our results suggest that RJ significantly reduced the levels of plasma total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C), and decreased the level of Aβ in rabbit brains. RJ was also shown to markedly ameliorate amyloid deposition in AD rabbits from Aβ immunohistochemistry and thioflavin-T staining. Furthermore, our study suggests that RJ can reduce the expression levels of β-site APP cleaving enzyme-1 (BACE1) and receptor for advanced glycation end products (RAGE), and increase the expression levels of low density lipoprotein receptor-related protein 1 (LRP-1) and insulin degrading enzyme (IDE). In addition, we found that RJ remarkably increased the number of neurons, enhanced antioxidant capacities, inhibited activated-capase-3 protein expression, and enhanced neuronal metabolic activities by increasing N-acetyl aspartate (NAA) and glutamate and by reducing choline and myo-inositol in AD rabbits. Taken together, our data demonstrated that RJ could reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in AD rabbits, providing preclinical evidence that RJ treatment has the potential to protect neurons and prevent AD.

Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring.

PubMed

Xu, Dan; Luo, Hanwen W; Hu, Wen; Hu, Shuwei W; Yuan, Chao; Wang, Guihua H; Zhang, Li; Yu, Hong; Magdalou, Jacques; Chen, Liaobin B; Wang, Hui

2018-05-02

Clinical and animal studies have indicated that hypercholesterolemia and its associated diseases have intrauterine developmental origins. Our previous studies showed that prenatal caffeine exposure (PCE) led to fetal overexposure to maternal glucocorticoids (GCs) and increased serum total cholesterol levels in adult rat offspring. This study further confirms the intrauterine programming of PCE-induced hypercholesterolemia in female adult rat offspring. Pregnant Wistar rats were intragastrically administered caffeine (30, 60, and 120 mg/kg/d) from gestational day (GD)9 to 20. Female rat offspring were euthanized at GD20 and postnatal wk 12; several adult rat offspring were additionally subjected to ice-water swimming stimulation to induce chronic stress prior to death. The effects of GCs on cholesterol metabolism and epigenetic regulation were verified using the L02 cell line. The results showed that PCE induced hypercholesterolemia in adult offspring, which manifested as significantly higher levels of serum total cholesterol and LDL cholesterol (LDL-C) as well as higher ratios of LDL-C/HDL cholesterol. We further found that the cholesterol levels were increased in fetal livers but were decreased in fetal blood, accompanied by increased maternal blood cholesterol levels and reduced placental cholesterol transport. Furthermore, analysis of PCE offspring in the uterus and in a postnatal basal/chronic stress state and the results of in vitro experiments showed that hepatic cholesterol metabolism underwent GC-dependent changes and was associated with cholesterol synthase via abnormalities in 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) histone acetylation. We concluded that, to compensate for intrauterine placentally derived decreases in fetal blood cholesterol levels, high intrauterine GC levels activated fetal hepatic CCAAT enhancer binding protein α signaling and down-regulated Sirtuin1 expression, which mediated the high levels of histone acetylation ( via H3K9ac and H3K14ac) and expression of HMGCR. This GC-dependent cholesterol metabolism programming effect was sustained through adulthood, leading to the occurrence of hypercholesterolemia.-Xu, D., Luo, H. W., Hu, W., Hu, S. W., Yuan, C., Wang, G. H., Zhang, L., Yu, H., Magdalou, J., Chen, L. B., Wang, H. Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring.

The association of very-low-density lipoprotein with ankle-brachial index in peritoneal dialysis patients with controlled serum low-density lipoprotein cholesterol level

PubMed Central

2013-01-01

Background Peripheral artery disease (PAD) represents atherosclerotic disease and is a risk factor for death in peritoneal dialysis (PD) patients, who tend to show an atherogenic lipid profile. In this study, we investigated the relationship between lipid profile and ankle-brachial index (ABI) as an index of atherosclerosis in PD patients with controlled serum low-density lipoprotein (LDL) cholesterol level. Methods Thirty-five PD patients, whose serum LDL cholesterol level was controlled at less than 120mg/dl, were enrolled in this cross-sectional study in Japan. The proportions of cholesterol level to total cholesterol level (cholesterol proportion) in 20 lipoprotein fractions and the mean size of lipoprotein particles were measured using an improved method, namely, high-performance gel permeation chromatography. Multivariate linear regression analysis was adjusted for diabetes mellitus and cardiovascular and/or cerebrovascular diseases. Results The mean (standard deviation) age was 61.6 (10.5) years; PD vintage, 38.5 (28.1) months; ABI, 1.07 (0.22). A low ABI (0.9 or lower) was observed in 7 patients (low-ABI group). The low-ABI group showed significantly higher cholesterol proportions in the chylomicron fraction and large very-low-density lipoproteins (VLDLs) (Fractions 3–5) than the high-ABI group (ABI>0.9). Adjusted multivariate linear regression analysis showed that ABI was negatively associated with serum VLDL cholesterol level (parameter estimate=-0.00566, p=0.0074); the cholesterol proportions in large VLDLs (Fraction 4, parameter estimate=-3.82, p=0.038; Fraction 5, parameter estimate=-3.62, p=0.0039) and medium VLDL (Fraction 6, parameter estimate=-3.25, p=0.014); and the size of VLDL particles (parameter estimate=-0.0352, p=0.032). Conclusions This study showed that the characteristics of VLDL particles were associated with ABI among PD patients. Lowering serum VLDL level may be an effective therapy against atherosclerosis in PD patients after the control of serum LDL cholesterol level. PMID:24093487

Effect of Lactobacillus acidophilus NS1 on plasma cholesterol levels in diet-induced obese mice.

PubMed

Song, M; Park, S; Lee, H; Min, B; Jung, S; Park, S; Kim, E; Oh, S

2015-03-01

We investigated the probiotic properties of Lactobacillus acidophilus NS1, such as acid resistance, bile tolerance, adherence to HT-29 cells, and cholesterol assimilation activity. In an animal study, 7-wk-old male C57BL/6 mice were fed a normal diet, a high-fat diet (HFD), or an HFD with L. acidophilus NS1 (ca. 1.0×10(8) cfu/mL) for 10 wk. Total cholesterol and low-density lipoprotein (LDL) cholesterol levels were significantly lower in mice fed an HFD with L. acidophilus NS1 than in those fed an HFD only, whereas high-density lipoprotein cholesterol levels were similar between these 2 groups. To understand the mechanism of the cholesterol-lowering effect of L. acidophilus NS1 on the HFD-mediated increase in plasma cholesterol levels, we determined mRNA levels of genes involved in cholesterol homeostasis in the liver. Expression of sterol regulatory element-binding protein 2 (Srebp2) and LDL receptor (Ldlr) in the liver was dramatically reduced in mice fed a HFD compared with those fed a normal diet. When L. acidophilus NS1 was administered orally to HFD-fed mice, an HFD-induced suppression of Srebp2 and Ldlr expression in the liver was abolished. These results suggest that the oral administration of L. acidophilus NS1 to mice fed an HFD increased the expression of Srebp2 and Ldlr in the liver, which was inhibited by high fat intake, thus leading to a decrease in plasma cholesterol levels. Lactobacillus acidophilus NS1 could be a useful probiotic microorganism for cholesterol-lowering dairy products and the improvement of hyperlipidemia and hepatic lipid metabolism. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Regulation of plasma cholesterol by hepatic low-density lipoprotein receptors.

PubMed

Kovanen, P T

1987-02-01

The endogenous lipoprotein system (very low-density lipoprotein [VLDL], intermediate-density lipoprotein [IDL], low-density lipoprotein [LDL] cascade) holds the key to understanding the mechanisms by which hormones, diet, and drugs interact to regulate the plasma cholesterol level. Crucial components of this system are hepatic LDL receptors that mediate the uptake and degradation of plasma LDL. With experimental animals, it has been possible to demonstrate that hepatic LDL receptors are sensitive to hormonal, dietary, and pharmacologic manipulation. The decrease in number of hepatic LDL receptors in hypothyroidism or after cholesterol feeding leads to elevation of plasma LDL cholesterol levels. Conversely, the increase in number of hepatic LDL receptors results in lowering of plasma LDL cholesterol levels. This can be observed in hyperthyroidism, during administration of pharmacologic doses of 17 alpha-ethinyl estradiol, or during treatment with cholesterol-lowering drugs such as the bile acid-binding resins and cholesterol-synthesis inhibitors. Since cholesterol excretion from the body occurs via the liver, the increased efficiency of disposal of plasma cholesterol by increasing hepatic LDL receptors will ultimately lead to depletion of excessive body cholesterol. Pharmacologic regulation of hepatic LDL receptors should be a valuable tool in the prevention and therapy of atherosclerosis.

Cholesterol metabolism and transport in the pathogenesis of Alzheimer's disease.

PubMed

Martins, Ian J; Berger, Tamar; Sharman, Matthew J; Verdile, Giuseppe; Fuller, Stephanie J; Martins, Ralph N

2009-12-01

Alzheimer's disease (AD) is the most common neurodegenerative disorder, affecting millions of people worldwide. Apart from age, the major risk factor identified so far for the sporadic form of AD is possession of the epsilon4 allele of apolipoprotein E (APOE), which is also a risk factor for coronary artery disease (CAD). Other apolipoproteins known to play an important role in CAD such as apolipoprotein B are now gaining attention for their role in AD as well. AD and CAD share other risk factors, such as altered cholesterol levels, particularly high levels of low density lipoproteins together with low levels of high density lipoproteins. Statins--drugs that have been used to lower cholesterol levels in CAD, have been shown to protect against AD, although the protective mechanism(s) involved are still under debate. Enzymatic production of the beta amyloid peptide, the peptide thought to play a major role in AD pathogenesis, is affected by membrane cholesterol levels. In addition, polymorphisms in several proteins and enzymes involved in cholesterol and lipoprotein transport and metabolism have been linked to risk of AD. Taken together, these findings provide strong evidence that changes in cholesterol metabolism are intimately involved in AD pathogenic processes. This paper reviews cholesterol metabolism and transport, as well as those aspects of cholesterol metabolism that have been linked with AD.

Reduced aortic lesions and elevated high density lipoprotein levels in transgenic mice overexpressing mouse apolipoprotein A-IV.

PubMed Central

Cohen, R D; Castellani, L W; Qiao, J H; Van Lenten, B J; Lusis, A J; Reue, K

1997-01-01

Transgenic mouse lines carrying several copies of the mouse apo A-IV gene were produced. Lipoprotein composition and function, and aortic lesion development were examined. Apo A-IV levels in the plasma of transgenic mice were elevated threefold compared with nontransgenic littermates on a chow diet, and sixfold in mice fed an atherogenic diet. Plasma concentrations of total cholesterol, HDL cholesterol, triglycerides, and free fatty acids were similar in transgenic and control mice fed a chow diet. However, with the atherogenic diet, male transgenic mice exhibited significantly higher levels of plasma triglycerides (P < 0.05), total cholesterol (P < 0.01), HDL cholesterol (P < 0.0001), and free fatty acids (P < 0.05), and lower levels of unesterified cholesterol (P < 0.05), than nontransgenic littermates. Expression of the apo A-IV transgene had a protective effect against the formation of diet-induced aortic lesions, with transgenics exhibiting lesion scores of approximately 30% those seen in control mice. HDL-sized lipoproteins isolated from transgenic mice fed the atherogenic diet promoted cholesterol efflux from cholesterol-loaded human monocytes more efficiently than comparable lipoproteins from nontransgenic counterparts. Plasma from transgenics also exhibited higher endogenous cholesterol esterification rates. Taken together, these results suggest that apo A-IV levels influence the metabolism and antiatherogenic properties of HDL. PMID:9109435

Chlorogenic acid-enriched extract from Eucommia ulmoides leaves inhibits hepatic lipid accumulation through regulation of cholesterol metabolism in HepG2 cells.

PubMed

Hao, Shun; Xiao, Yuan; Lin, Yan; Mo, Zhentao; Chen, Yang; Peng, Xiaofeng; Xiang, Canhui; Li, Yiqi; Li, Wenna

2016-01-01

Eucommia ulmoides Oliver (Eucommiaceae) leaf exhibits beneficial lipid-lowering and anti-obesity effects. However, the mechanisms remain unknown. The objective of this study is to investigate the lipid-lowering effects of chlorogenic acid (CGA)-enriched extract from this plant (CAEF) in human hepatoma HepG2 cells, focusing on cholesterol metabolism. HepG2 cells were treated with CAEF (10, 20, 25, 40, 60, and 80 mg/L), CGA (0.3, 3, 30, 300, and 600 μmol/L), and simvastatin (0.1, 1, 10, 50, and 100 μmol/L) for 24 or 48 h. The cytotoxicity, Oil red O staining, total cholesterol, and triacylglycerol in supernatants were determined. The mRNA expression of genes involved in cholesterol metabolism was determined with RT-PCR. The protein expression of HMG-CoA reductase (HMGCR) was examined by immunocytochemistry and western-blot. The IC50 values were 59.2 mg/L for CAEF, 335.9 μmol/L for CGA, and 10.5 μmol/L for simvastatin. By treating cells with CAEF (25 mg/L), CGA (30 μmol/L), or simvastatin (10 μmol/L) for 48 h, the efflux of total cholesterol and triacylglycerol was increased (CAEF, 4.06- and 31.00-folds; CGA, 2.94- and 2.17-folds; and simvastatin, 3.94- and 24.67-folds), and the cellular lipid droplets were reduced in Oil red O staining. CAEF and CGA increased mRNA expression of ABCA1, CYP7A1, and AMPKα2, while CAEF and simvastatin decreased SREBP2. However, their effects on LXRα mRNA expression were variable. Importantly, all drugs significantly inhibited protein expression of HMGCR at mRNA and protein levels. CAEF is a promising dietary supplement to prevent obesity and dyslipidemia and the effects appear to be due, at least in part, to regulating cholesterol metabolism through inhibition of HMGCR in HepG2 cells.

Quantitative analysis of Hedgehog gradient formation using an inducible expression system

PubMed Central

Su, Vivian F; Jones, Kelly A; Brodsky, Michael; The, Inge

2007-01-01

Background The Hedgehog (Hh) family of secreted growth factors are morphogens that act in development to direct growth and patterning. Mutations in human Hh and other Hh pathway components have been linked to human diseases. Analysis of Hh distribution during development indicates that cholesterol modification and receptor mediated endocytosis affect the range of Hh signaling and the cellular localization of Hh. Results We have used an inducible, cell type-specific expression system to characterize the three-dimensional distribution of newly synthesized, GFP-tagged Hh in the developing Drosophila wing. Following induction of Hh-GFP expression in posterior producing cells, punctate structures containing Hh-GFP were observed in the anterior target cells. The distance of these particles from the expressing cells was quantified to determine the shape of the Hh gradient at different time points following induction. The majority of cholesterol-modified Hh-GFP was found associated with cells near the anterior/posterior (A/P) boundary, which express high levels of Hh target genes. Without cholesterol, the Hh gradient was flatter, with a lower percentage of particles near the source and a greater maximum distance. Inhibition of Dynamin-dependent endocytosis blocked formation of intracellular Hh particles, but did not prevent movement of newly synthesized Hh to the apical or basolateral surfaces of target cells. In the absence of both cholesterol and endocytosis, Hh particles accumulated in the extracellular space. Staining for the Hh receptor Ptc revealed four categories of Hh particles: cytoplasmic with and without Ptc, and cell surface with and without Ptc. Interestingly, mainly cholesterol-modified Hh is detected in the cytoplasmic particles lacking Ptc. Conclusion We have developed a system to quantitatively analyze Hh distribution during gradient formation. We directly demonstrate that inhibition of Dynamin-dependent endocytosis is not required for movement of Hh across target cells, indicating that transcytosis is not required for Hh gradient formation. The localization of Hh in these cells suggests that Hh normally moves across both apical and basolateral regions of the target cells. We also conclude that cholesterol modification is required for formation of a specific subset of Hh particles that are both cytoplasmic and not associated with the receptor Ptc. PMID:17484784

Quantitative analysis of Hedgehog gradient formation using an inducible expression system.

PubMed

Su, Vivian F; Jones, Kelly A; Brodsky, Michael; The, Inge

2007-05-07

The Hedgehog (Hh) family of secreted growth factors are morphogens that act in development to direct growth and patterning. Mutations in human Hh and other Hh pathway components have been linked to human diseases. Analysis of Hh distribution during development indicates that cholesterol modification and receptor mediated endocytosis affect the range of Hh signaling and the cellular localization of Hh. We have used an inducible, cell type-specific expression system to characterize the three-dimensional distribution of newly synthesized, GFP-tagged Hh in the developing Drosophila wing. Following induction of Hh-GFP expression in posterior producing cells, punctate structures containing Hh-GFP were observed in the anterior target cells. The distance of these particles from the expressing cells was quantified to determine the shape of the Hh gradient at different time points following induction. The majority of cholesterol-modified Hh-GFP was found associated with cells near the anterior/posterior (A/P) boundary, which express high levels of Hh target genes. Without cholesterol, the Hh gradient was flatter, with a lower percentage of particles near the source and a greater maximum distance. Inhibition of Dynamin-dependent endocytosis blocked formation of intracellular Hh particles, but did not prevent movement of newly synthesized Hh to the apical or basolateral surfaces of target cells. In the absence of both cholesterol and endocytosis, Hh particles accumulated in the extracellular space. Staining for the Hh receptor Ptc revealed four categories of Hh particles: cytoplasmic with and without Ptc, and cell surface with and without Ptc. Interestingly, mainly cholesterol-modified Hh is detected in the cytoplasmic particles lacking Ptc. We have developed a system to quantitatively analyze Hh distribution during gradient formation. We directly demonstrate that inhibition of Dynamin-dependent endocytosis is not required for movement of Hh across target cells, indicating that transcytosis is not required for Hh gradient formation. The localization of Hh in these cells suggests that Hh normally moves across both apical and basolateral regions of the target cells. We also conclude that cholesterol modification is required for formation of a specific subset of Hh particles that are both cytoplasmic and not associated with the receptor Ptc.

Dietary capsanthin, the main carotenoid in paprika (Capsicum annuum), alters plasma high-density lipoprotein-cholesterol levels and hepatic gene expression in rats.

PubMed

Aizawa, Koichi; Inakuma, Takahiro

2009-12-01

The effects of dietary capsanthin, the main carotenoid in paprika (Capsicum annuum), on lipid metabolism were examined. Young male Wistar rats were fed diets containing paprika powder, paprika organic solvent extract, residue of paprika extract, and purified capsanthin. Administration of purified capsanthin for 2 weeks resulted in a significant increase in plasma HDL-cholesterol (P < 0.05) without detectable differences in plasma total cholesterol and TAG concentrations. A statistically significant correlation (r 0.567; P < 0.001) was found between dietary capsanthin concentrations and plasma HDL-cholesterol concentrations. Animals receiving diets containing two different capsanthin concentrations exhibited dose-dependent increases in plasma HDL-cholesterol (r 0.597; P < 0.005). While capsanthin was absent in the liver of animals fed the basal diet, it increased markedly in capsanthin-fed animals (P < 0.001). Quantitative analyses of hepatic mRNA levels revealed that capsanthin administration resulted in up-regulation of mRNA for apoA5 and lecithin cholesterol acyltransferase (LCAT), without significant differences in other mRNA levels related to HDL-cholesterol metabolism. These results suggest that capsanthin had an HDL-cholesterol-raising effect on plasma, and the potential to increase cholesterol efflux to HDL particles by increasing apoA5 levels and/or enhancement of LCAT activity.

High-Density Lipoprotein-Targeted Therapy and Apolipoprotein A-I Mimetic Peptides.

PubMed

Uehara, Yoshinari; Chiesa, Giulia; Saku, Keijiro

2015-01-01

Numerous randomized clinical trials have established statins as the major standard therapy for atherosclerotic diseases because these molecules decrease the plasma level of low-density lipoprotein (LDL) cholesterol and moderately increase that of plasma high-density lipoprotein (HDL) cholesterol. The reverse cholesterol transport pathway, mediated by HDL particles, has a relevant antiatherogenic potential. An important approach to HDL-targeted therapy is optimization of the HDL-cholesterol level and enhanced removal of plasma cholesterol, together with the prevention and mitigation of inflammation related to atherosclerosis. Small-molecule inhibitors of cholesteryl ester transfer protein (CETP) increase the HDL-cholesterol level in subjects with normal or low HDL-cholesterol. However, CETP inhibitors do not seem to reduce the risk of atherosclerotic diseases. HDL therapies using reconstituted HDL, including apolipoprotein (Apo) A-I Milano, ApoA-I mimetics, or full-length ApoA-I, are dramatically effective in animal models. Of those, the ApoA-I-mimetic peptide called FAMP effectively removes cholesterol via the ABCA1 transporter and acts as an antiatherosclerotic agent by enhancing the biological functions of HDL without elevating the HDL-cholesterol level. Our review of the literature leads us to conclude that HDL-targeted therapies have significant atheroprotective potential and thus may effectively treat patients with cardiovascular diseases.

Results of a heart disease risk-factor screening among traditional college students.

PubMed

Spencer, Leslie

2002-05-01

The author collected data on serum cholesterol, blood pressure, and self-reported health behavior in 226 college students aged 18 to 26 years. Twenty-nine percent had undesirable total cholesterol levels, 10% had high cholesterol, 10% had high systolic blood pressure, and 11% had high diastolic blood pressure. Half or more of the participants consumed a diet high in saturated fats, engaged in binge drinking, had a parental risk for high cholesterol or blood pressure, or reported they experienced elevated stress levels. Men had higher risk-factor levels than women. Findings from a regression analysis revealed that smoking, binge drinking, lack of cardiovascular exercise, and eating a high saturated-fat diet were predictive of undesirable cholesterol levels. Study limitations included self-selection of participants and single measurements of blood pressure and cholesterol. Trained students served as screeners in the program for providing an effective, low-cost screening intervention.

Membrane Cholesterol in Skeletal Muscle: A Novel Player in Excitation-Contraction Coupling and Insulin Resistance

PubMed Central

Barrientos, G.; Sánchez-Aguilera, P.; Jaimovich, E.; Hidalgo, C.

2017-01-01

Membrane cholesterol is critical for signaling processes in a variety of tissues. We will address here current evidence supporting an emerging role of cholesterol on excitation-contraction coupling and glucose transport in skeletal muscle. We have centered our review on the transverse tubule system, a complex network of narrow plasma membrane invaginations that propagate membrane depolarization into the fiber interior and allow nutrient delivery into the fibers. We will discuss current evidence showing that transverse tubule membranes have remarkably high cholesterol levels and we will address how modifications of cholesterol content influence excitation-contraction coupling. In addition, we will discuss how membrane cholesterol levels affect glucose transport by modulating the insertion into the membrane of the main insulin-sensitive glucose transporter GLUT4. Finally, we will address how the increased membrane cholesterol levels displayed by obese animals, which also present insulin resistance, affect these two particular skeletal muscle functions. PMID:28367451

[Changes in nutritional recommendations for a healthy population and their influence on a diabetic diet].

PubMed

Anděl, Michal; Brunerová, Ludmila; Dlouhý, Pavel; Polák, Jan; Gojda, Jan; Kraml, Pavel

Recently, thousands of papers brought knowledge about effects of nutrients on cellular level, in experimental animals and in human experiments on one side, the results of epidemiological studies on the other side have suggested the nutrients and foods for healthy diet and nutrients and foods, which should be consumed only in limited amount. Among foods, which should be avoided, those with higher content of trans-fatty acids. Their daily intake should not exceed 1 % of total energy intake. Similar should be limited saturated fatty acid, added sugar and salt. On the contrary, the intake of monounsaturated and polyunsaturated fatty acids in foods should be basic part of fat intake. In these conditions the amount of consumed fat could create up to 35 % of all daily energy intake. Beneficial carbohydrates are those with low glycemic index, i.e. whole grain and brown rice products and legumes. The intake of salt is necessary to limit fewer than 6 g per day and alcohol intake should not exceed 10 g per day in women and 20 g per day in men. The recommendation in last years do not limit cholesterol daily intake. The food of animal origin with high content of saturated fatty acids, i.e. meat and milk products parallel contains also cholesterol. On the other hand, the oils of vegetable origin mostly from tropical oils, which contents high amount of saturated fatty acids represents the risk? On the contrary eggs and shellfish contents high amount of cholesterol and very low amounts of saturated fatty acids. Therefore, there is no reason for their strict limitation in the diet. carbohydrate - diabetes - dietary recommendation - energy intake - fat - healthy diet - iron - cholesterol - protein.

Suppression of Cytochrome P450 Reductase (POR) Expression in Hepatoma Cells Replicates the Hepatic Lipidosis Observed in Hepatic POR-Null Mice

PubMed Central

Banerjee, Subhashis; Stolarczyk, Elzbieta I.; Zou, Ling

2011-01-01

Cytochrome P450 reductase (POR) is a microsomal electron transport protein essential to cytochrome P450-mediated drug metabolism and sterol and bile acid synthesis. The conditional deletion of hepatic POR gene expression in mice results in a marked decrease in plasma cholesterol levels counterbalanced by the accumulation of triglycerides in lipid droplets in hepatocytes. To evaluate the role of cholesterol and bile acid synthesis in this hepatic lipidosis, as well as the possible role of lipid transport from peripheral tissues, we developed a stable, small interfering RNA (siRNA)-mediated cell culture model for the suppression of POR. POR mRNA and protein expression were decreased by greater than 50% in McArdle-RH7777 rat hepatoma cells 10 days after transfection with a POR-siRNA expression plasmid, and POR expression was nearly completely extinguished by day 20. Immunofluorescent analysis revealed a marked accumulation of lipid droplets in cells by day 15, accompanied by a nearly 2-fold increase in cellular triglyceride content, replicating the lipidosis seen in hepatic POR-null mouse liver. In contrast, suppression of CYP51A1 (lanosterol demethylase) did not result in lipid accumulation, indicating that loss of cholesterol synthesis is not the basis for this lipidosis. Indeed, addition of cholesterol to the medium appeared to augment the lipidosis in POR-suppressed cells, whereas removal of lipids from the medium reversed the lipidosis. Oxysterols did not accumulate in POR-suppressed cells, discounting a role for liver X receptor in stimulating triglyceride synthesis, but addition of chenodeoxycholate significantly repressed lipid accumulation, suggesting that the absence of bile acids and loss of farnesoid X receptor stimulation lead to excessive triglyceride synthesis. PMID:21368239

Circadian rhythm of the Leydig cells endocrine function is attenuated during aging.

PubMed

Baburski, Aleksandar Z; Sokanovic, Srdjan J; Bjelic, Maja M; Radovic, Sava M; Andric, Silvana A; Kostic, Tatjana S

2016-01-01

Although age-related hypofunction of Leydig cells is well illustrated across species, its circadian nature has not been analyzed. Here we describe changes in circadian behavior in Leydig cells isolated from adult (3-month) and aged (18- and 24-month) rats. The results showed reduced circadian pattern of testosterone secretion in both groups of aged rats despite unchanged LH circadian secretion. Although arrhythmic, the expression of Insl3, another secretory product of Leydig cells, was decreased in both groups. Intracellular cAMP and most important steroidogenic genes (Star, Cyp11a1 and Cyp17a1), together with positive steroidogenic regulator (Nur77), showed preserved circadian rhythm in aging although rhythm robustness and expression level were attenuated in both aged groups. Aging compromised cholesterol mobilization and uptake by Leydig cells: the oscillatory transcription pattern of genes encoding HDL-receptor (Scarb1), hormone sensitive lipase (Lipe, enzyme that converts cholesterol esters from lipid droplets into free cholesterol) and protein responsible for forming the cholesterol esters (Soat2) were flattened in 24-month group. The majority of examined clock genes displayed circadian behavior in expression but only a few of them (Bmal1, Per1, Per2, Per3 and Rev-Erba) were reduced in 24-month-old group. Furthermore, aging reduced oscillatory expression pattern of Sirt1 and Nampt, genes encoding key enzymes that connect cellular metabolism and circadian network. Altogether circadian amplitude of Leydig cell's endocrine function decreased during aging. The results suggest that clock genes are more resistant to aging than genes involved in steroidogenesis supporting the hypothesis about peripheral clock involvement in rhythm maintenance during aging. Copyright © 2015 Elsevier Inc. All rights reserved.

Suppression of cytochrome P450 reductase (POR) expression in hepatoma cells replicates the hepatic lipidosis observed in hepatic POR-null mice.

PubMed

Porter, Todd D; Banerjee, Subhashis; Stolarczyk, Elzbieta I; Zou, Ling

2011-06-01

Cytochrome P450 reductase (POR) is a microsomal electron transport protein essential to cytochrome P450-mediated drug metabolism and sterol and bile acid synthesis. The conditional deletion of hepatic POR gene expression in mice results in a marked decrease in plasma cholesterol levels counterbalanced by the accumulation of triglycerides in lipid droplets in hepatocytes. To evaluate the role of cholesterol and bile acid synthesis in this hepatic lipidosis, as well as the possible role of lipid transport from peripheral tissues, we developed a stable, small interfering RNA (siRNA)-mediated cell culture model for the suppression of POR. POR mRNA and protein expression were decreased by greater than 50% in McArdle-RH7777 rat hepatoma cells 10 days after transfection with a POR-siRNA expression plasmid, and POR expression was nearly completely extinguished by day 20. Immunofluorescent analysis revealed a marked accumulation of lipid droplets in cells by day 15, accompanied by a nearly 2-fold increase in cellular triglyceride content, replicating the lipidosis seen in hepatic POR-null mouse liver. In contrast, suppression of CYP51A1 (lanosterol demethylase) did not result in lipid accumulation, indicating that loss of cholesterol synthesis is not the basis for this lipidosis. Indeed, addition of cholesterol to the medium appeared to augment the lipidosis in POR-suppressed cells, whereas removal of lipids from the medium reversed the lipidosis. Oxysterols did not accumulate in POR-suppressed cells, discounting a role for liver X receptor in stimulating triglyceride synthesis, but addition of chenodeoxycholate significantly repressed lipid accumulation, suggesting that the absence of bile acids and loss of farnesoid X receptor stimulation lead to excessive triglyceride synthesis.

Acyl-CoA:cholesterol acyltransferases (ACATs/SOATs): Enzymes with multiple sterols as substrates and as activators.

PubMed

Rogers, Maximillian A; Liu, Jay; Song, Bao-Liang; Li, Bo-Liang; Chang, Catherine C Y; Chang, Ta-Yuan

2015-07-01

Cholesterol is essential to the growth and viability of cells. The metabolites of cholesterol include: steroids, oxysterols, and bile acids, all of which play important physiological functions. Cholesterol and its metabolites have been implicated in the pathogenesis of multiple human diseases, including: atherosclerosis, cancer, neurodegenerative diseases, and diabetes. Thus, understanding how cells maintain the homeostasis of cholesterol and its metabolites is an important area of study. Acyl-coenzyme A:cholesterol acyltransferases (ACATs, also abbreviated as SOATs) converts cholesterol to cholesteryl esters and play key roles in the regulation of cellular cholesterol homeostasis. ACATs are most unusual enzymes because (i) they metabolize diverse substrates including both sterols and certain steroids; (ii) they contain two different binding sites for steroidal molecules. In mammals, there are two ACAT genes that encode two different enzymes, ACAT1 and ACAT2. Both are allosteric enzymes that can be activated by a variety of sterols. In addition to cholesterol, other sterols that possess the 3-beta OH at C-3, including PREG, oxysterols (such as 24(S)-hydroxycholesterol and 27-hydroxycholesterol, etc.), and various plant sterols, could all be ACAT substrates. All sterols that possess the iso-octyl side chain including cholesterol, oxysterols, various plant sterols could all be activators of ACAT. PREG can only be an ACAT substrate because it lacks the iso-octyl side chain required to be an ACAT activator. The unnatural cholesterol analogs epi-cholesterol (with 3-alpha OH in steroid ring B) and ent-cholesterol (the mirror image of cholesterol) contain the iso-octyl side chain but do not have the 3-beta OH at C-3. Thus, they can only serve as activators and cannot serve as substrates. Thus, within the ACAT holoenzyme, there are site(s) that bind sterol as substrate and site(s) that bind sterol as activator; these sites are distinct from each other. These features form the basis to further pursue ACAT structure-function analysis, and can be explored to develop novel allosteric ACAT inhibitors for therapeutic purposes. This article is part of a Special Issue entitled 'Steroid/Sterol signaling'. Copyright © 2014. Published by Elsevier Ltd.

Diphenyl diselenide decreases serum levels of total cholesterol and tissue oxidative stress in cholesterol-fed rabbits.

PubMed

de Bem, Andreza Fabro; Portella, Rafael de Lima; Colpo, Elisângela; Duarte, Marta Maria Medeiros Frescura; Frediane, Andressa; Taube, Paulo Sergio; Nogueira, Cristina Wayne; Farina, Marcelo; da Silva, Edson Luiz; Teixeira Rocha, João Batista

2009-07-01

Hypercholesterolaemia and oxidative stress are well-known risk factors in coronary artery diseases. Diphenyl diselenide is a synthetic organoselenium compound that has been shown to have in vitro and in vivo antioxidant properties. In this study, we investigated whether diphenyl diselenide could reduce the hypercholesterolaemia and diminish the tissue oxidative stress in cholesterol-fed rabbits. Twenty-four New Zealand white male rabbits were randomly divided into four groups. Each group was fed a different diet as follows: Control group--regular chow; Cholesterol group--1% cholesterol-enriched diet; diphenyl diselenide group--regular diet supplemented with 10 ppm diphenyl diselenide; and Chol/diphenyl diselenide group--the same cholesterol-rich supplemented with 10 ppm diphenyl diselenide. After 45 days of treatment, the rabbits were killed and the blood, liver, and brain were used for laboratory analysis. The results showed that the serum levels of total cholesterol were markedly increased in cholesterol-fed rabbits and the consumption of diphenyl diselenide decreased these levels approximately twofold in Chol/diphenyl diselenide rabbits (P < 0.05). The intake of diphenyl diselenide by hypercholesterolaemic rabbits diminished the serum and hepatic thiobarbituric acid reactive substances levels as well as the production of reactive oxygen species in the blood and brain (P < 0.05) when compared to the cholesterol group. In addition, diphenyl diselenide supplementation increased hepatic and cerebral delta-aminolevulinic dehydratase activity and hepatic non-protein thiol groups levels despite hypercholesterolaemia (P < 0.05). In summary, the results showed that diphenyl diselenide reduced the hypercholesterolaemia and the oxidative stress in cholesterol-fed rabbits.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Armstrong, Clare L; Marquardt, Drew; Dies, Hannah

Rafts, or functional domains, are transient nano- or mesoscopic structures in the exoplasmic leaflet of the plasma membrane, and are thought to be essential for many cellular processes. Using neutron diffraction and computer modelling, we present evidence for the existence of highly ordered lipid domains in the cholesterol-rich (32.5 mol%) liquid-ordered (lo) phase of dipalmitoylphosphatidylcholine membranes. The liquid ordered phase in one-component lipid membranes has previously been thought to be a homogeneous phase. The presence of highly ordered lipid domains embedded in a disordered lipid matrix implies non-uniform distribution of cholesterol between the two phases. The experimental results are inmore » excellent agreement with recent computer simulations of DPPC/cholesterol complexes [Meinhardt, Vink and Schmid (2013). Proc Natl Acad Sci USA 110(12): 4476 4481], which reported the existence of nanometer size lo domains in a liquid disordered lipid environment.« less

The membrane-associated form of α(s1)-casein interacts with cholesterol-rich detergent-resistant microdomains.

PubMed

Le Parc, Annabelle; Honvo Houéto, Edith; Pigat, Natascha; Chat, Sophie; Leonil, Joëlle; Chanat, Eric

2014-01-01

Caseins, the main milk proteins, interact with colloidal calcium phosphate to form the casein micelle. The mesostructure of this supramolecular assembly markedly influences its nutritional and technological functionalities. However, its detailed molecular organization and the cellular mechanisms involved in its biogenesis have been only partially established. There is a growing body of evidence to support the concept that α(s1)-casein takes center stage in casein micelle building and transport in the secretory pathway of mammary epithelial cells. Here we have investigated the membrane-associated form of α(s1)-casein in rat mammary epithelial cells. Using metabolic labelling we show that α(s1)-casein becomes associated with membranes at the level of the endoplasmic reticulum, with no subsequent increase at the level of the Golgi apparatus. From morphological and biochemical data, it appears that caseins are in a tight relationship with membranes throughout the secretory pathway. On the other hand, we have observed that the membrane-associated form of α(s1)-casein co-purified with detergent-resistant membranes. It was poorly solubilised by Tween 20, partially insoluble in Lubrol WX, and substantially insoluble in Triton X-100. Finally, we found that cholesterol depletion results in the release of the membrane-associated form of α(s1)-casein. These experiments reveal that the insolubility of α(s1)-casein reflects its partial association with a cholesterol-rich detergent-resistant microdomain. We propose that the membrane-associated form of α(s1)-casein interacts with the lipid microdomain, or lipid raft, that forms within the membranes of the endoplasmic reticulum, for efficient forward transport and sorting in the secretory pathway of mammary epithelial cells.

The Membrane-Associated Form of αs1-Casein Interacts with Cholesterol-Rich Detergent-Resistant Microdomains

PubMed Central

Le Parc, Annabelle; Honvo Houéto, Edith; Pigat, Natascha; Chat, Sophie; Leonil, Joëlle; Chanat, Eric

2014-01-01

Caseins, the main milk proteins, interact with colloidal calcium phosphate to form the casein micelle. The mesostructure of this supramolecular assembly markedly influences its nutritional and technological functionalities. However, its detailed molecular organization and the cellular mechanisms involved in its biogenesis have been only partially established. There is a growing body of evidence to support the concept that αs1-casein takes center stage in casein micelle building and transport in the secretory pathway of mammary epithelial cells. Here we have investigated the membrane-associated form of αs1-casein in rat mammary epithelial cells. Using metabolic labelling we show that αs1-casein becomes associated with membranes at the level of the endoplasmic reticulum, with no subsequent increase at the level of the Golgi apparatus. From morphological and biochemical data, it appears that caseins are in a tight relationship with membranes throughout the secretory pathway. On the other hand, we have observed that the membrane-associated form of αs1-casein co-purified with detergent-resistant membranes. It was poorly solubilised by Tween 20, partially insoluble in Lubrol WX, and substantially insoluble in Triton X-100. Finally, we found that cholesterol depletion results in the release of the membrane-associated form of αs1-casein. These experiments reveal that the insolubility of αs1-casein reflects its partial association with a cholesterol-rich detergent-resistant microdomain. We propose that the membrane-associated form of αs1-casein interacts with the lipid microdomain, or lipid raft, that forms within the membranes of the endoplasmic reticulum, for efficient forward transport and sorting in the secretory pathway of mammary epithelial cells. PMID:25549363

Beneficial effects of coconut water feeding on lipid metabolism in cholesterol-fed rats.

PubMed

Sandhya, V G; Rajamohan, T

2006-01-01

The purpose of this study was to determine the effect of coconut water feeding in cholesterol-fed rats. Male albino rats were fed tender coconut water and mature coconut water at a dose level of 4 mL/100 g of body weight. Cholesterol feeding caused a marked increase in total cholesterol, very low-density lipoprotein (VLDL) + low-density lipoprotein (LDL) cholesterol, and triglycerides in serum. Administration of coconut water counteracts the increase in total cholesterol, VLDL + LDL cholesterol, and triglycerides, while high-density lipoprotein cholesterol was higher. Lipid levels in the tissues viz. liver, heart, kidney, and aorta were markedly decreased in cholesterol-fed rats supplemented with coconut water. Feeding coconut water resulted in increased activities of 3-hydroxy-3-methylglutaryl-CoA reductase in liver, lipoprotein lipase in heart and adipose tissue, and plasma lecithin:cholesterol acyl transferase, while lipogenic enzymes showed decreased activities. An increased rate of cholesterol conversion to bile acid and an increased excretion of bile acids and neutral sterols were observed in rats fed coconut water. Histopathological studies of liver and aorta revealed much less fatty accumulation in these tissues in cholesterol-fed rats supplemented with coconut water. Feeding coconut water resulted in increased plasma L-arginine content, urinary nitrite level, and nitric oxide synthase activity. These results indicate that both tender and mature coconut water has beneficial effects on serum and tissue lipid parameters in rats fed cholesterol-containing diet.

Excess dietary cholesterol may have an adverse effect on growth performance of early post-larval Litopenaeus vannamei

PubMed Central

2012-01-01

One experiment was conducted to determine the nutritive value of cholesterol for post-larval shrimp, Litopenaeus vannamei. Four isoenergetic and isonitrogenous diets supplemented with four levels of cholesterol (D1, D2, D3 and D4 with 0, 0.5%, 1% and 2% cholesterol, respectively) were fed to triplicate groups of L. vannamei shrimp (mean initial wet weight 0.8 mg) for 27 days. After the trial, shrimp fed the D1 diet had the best growth performance (final body weights: FBW; weight gain: WG; specific growth rate: SGR), while there was no significant difference between diet treatments with respect to survival. The whole body crude protein level in the shrimp decreased with the increase in dietary cholesterol levels, while the whole body crude lipid level in shrimps in the D4 diet treatment was significantly higher (P < 0.05) than in other diet treatments. Dietary analysis indicated that the D1 diet contained 0.92% cholesterol prior to supplementation, which may have satisfied the dietary cholesterol requirement of post-larval L. vannamei; excess dietary cholesterol may thus lead to adverse effects on the growth performance of post-larval shrimp. PMID:22958647

Trends in lipid profiles and descriptive characteristics of U.S. adults with and without diabetes and cholesterol-lowering medication use-National Health and Nutrition Examination Survey, 2003-2012, United States.

PubMed

Mercado, Carla I; Gregg, Edward; Gillespie, Cathleen; Loustalot, Fleetwood

2018-01-01

With a cholesterol-lowering focus for diabetic adults and in the age of polypharmacy, it is important to understand how lipid profile levels differ among those with and without diabetes. Investigate the means, differences, and trends in lipid profile measures [TC, total cholesterol; LDL-c, low-density lipoprotein; HDL-c, high-density lipoprotein; and TG, triglycerides] among US adults by diabetes status and cholesterol-lowering medication. Population number and proportion of adults aged ≥21 years with diabetes and taking cholesterol-lowering medication were estimated using data on 10,384 participants from NHANES 2003-2012. Age-standardized means, trends, and differences in lipid profile measures were estimated by diabetes status and cholesterol medication use. For trends and differences, linear regression analysis were used adjusted for age, gender, and race/ethnicity. Among diabetic adults, 52% were taking cholesterol-lowering medication compared to the 14% taking cholesterol-lowering medication without diabetes. Although diabetic adults had significantly lower TC and LDL-c levels than non-diabetic adults [% difference (95% confidence interval): TC = -5.2% (-6.8 --3.5), LDL-c = -8.0% (-10.4 --5.5)], the percent difference was greater among adults taking cholesterol medication [TC = -8.0% (-10.3 --5.7); LDL-c = -13.7% (-17.1 --10.2)] than adults not taking cholesterol medication [TC = -3.5% (-5.2 --1.6); LDL-c = -4.3% (-7.1 --1.5)] (interaction p-value: TC = <0.001; LDL-c = <0.001). From 2003-2012, mean TC and HDL-c significantly decreased among diabetic adults taking cholesterol medication [% difference per survey cycle (p-value for linear trend): TC = -2.3% (0.003) and HDL-c = -2.3% (0.033)]. Mean TC, HDL-c, and LDL-c levels did not significantly change from 2003 to 2012 in non-diabetic adults taking cholesterol medication or for adults not taking cholesterol medications. Diabetic adults were more likely to have lower lipid levels, except for triglyceride levels, than non-diabetic adults with profound differences when considering cholesterol medication use, possibly due to the positive effects from clinical diabetes management.

ChoG is the main inducible extracellular cholesterol oxidase of Rhodococcus sp. strain CECT3014.

PubMed

Fernández de Las Heras, Laura; Mascaraque, Victoria; García Fernández, Esther; Navarro-Llorens, Juana María; Perera, Julián; Drzyzga, Oliver

2011-07-20

Cholesterol catabolism has been reported in different bacteria and particularly in several Rhodococcus species, but the genetic of this complex pathway is not yet very well defined. In this work we report the isolation and sequencing of a 9.8 kb DNA fragment of Rhodococcus sp. strain CECT3014, a bacterial strain that we here identify as a Rhodococcus erythropolis strain. In this DNA fragment we found several ORF that are probably involved in steroid catabolism, and choG, a gene encoding a putative cholesterol oxidase whose functional characterization we here report. ChoG protein is a class II cholesterol oxidase with all the structural features of the enzymes of this group. The disruption of the choG gene does not alter the ability of strain CECT3014 cells to grow on cholesterol, but it abolishes the production of extracellular cholesterol oxidase. This later effect is reverted when the mutant cells are transformed with a plasmid expressing choG. We conclude that choG is the gene responsible for the inducible extracellular cholesterol oxidase activity of strain CECT3014. This activity distributes between the cellular membrane and the culture supernatant in a way that suggests it is produced by the same ChoG protein that occurs in two different locations. RT-PCR transcript analysis showed a dual scheme of choG expression: a low constitutive independent transcription, plus a cholesterol induced transcription of choG into a polycistronic kstD-hsd4B-choG mRNA. Copyright © 2010 Elsevier GmbH. All rights reserved.

Variability of cholesterol accessibility in human red blood cells measured using a bacterial cholesterol-binding toxin

PubMed Central

Chakrabarti, Rima S; Ingham, Sally A; Kozlitina, Julia; Gay, Austin; Cohen, Jonathan C; Radhakrishnan, Arun; Hobbs, Helen H

2017-01-01

Cholesterol partitions into accessible and sequestered pools in cell membranes. Here, we describe a new assay using fluorescently-tagged anthrolysin O, a cholesterol-binding bacterial toxin, to measure accessible cholesterol in human red blood cells (RBCs). Accessible cholesterol levels were stable within individuals, but varied >10 fold among individuals. Significant variation was observed among ethnic groups (Blacks>Hispanics>Whites). Variation in accessibility of RBC cholesterol was unrelated to the cholesterol content of RBCs or plasma, but was associated with the phospholipid composition of the RBC membranes and with plasma triglyceride levels. Pronase treatment of RBCs only modestly altered cholesterol accessibility. Individuals on hemodialysis, who have an unexplained increase in atherosclerotic risk, had significantly higher RBC cholesterol accessibility. Our data indicate that RBC accessible cholesterol is a stable phenotype with significant inter-individual variability. Factors both intrinsic and extrinsic to the RBC contribute to variation in its accessibility. This assay provides a new tool to assess cholesterol homeostasis among tissues in humans. DOI: http://dx.doi.org/10.7554/eLife.23355.001 PMID:28169829

Cholesterol transport from plasma membranes to intracellular membranes is inhibited by 3 beta-[2-(diethylamino)ethoxy]androst-5-en-17-one.

PubMed

Härmälä, A S; Pörn, M I; Mattjus, P; Slotte, J P

1994-03-24

The compound U1866A (3 beta-[2-(diethylamino)ethoxy]androst-5-en-17-one) has been shown to inhibit the cellular transfer of low-density lipoprotein-derived cholesterol from lysosomes to plasma membranes (Liscum and Faust (1989) J. Biol. Chem. 264, 11796-806). We have in this study examined the effects of U18666A on cholesterol translocation from plasma membranes to intracellular membranes. Translocation of plasma membrane cholesterol was induced by degradation of plasma membrane sphingomyelin. The sphingomyelinase-induced activation of the acyl-CoA cholesterol acyl transferase (ACAT) reaction was completely inhibited in a dose-dependent manner by U18666A, both in cultured human skin fibroblasts and baby hamster kidney cells. Half-maximal inhibition (within 60 min) was obtained with 0.5-1 microgram/ml of U18666A. A time-course study indicated that the onset of inhibition was rapid (within 10-15 min), and reversible if U18666A was removed from the incubation mixture. Using a cholesterol oxidase assay, we observed that the extent of plasma membrane cholesterol translocation in sphingomyelinase-treated HSF cells was significantly lowered in the presence of U18666A (at 3 micrograms/ml). The effect of U18666A on cholesterol translocation was also fully reversible when the drug was withdrawn. In mouse Leydig tumor cells, labeled to constant specific activity with [3H]cholesterol, the compound U18666A inhibited in a dose-dependent manner the cyclic AMP-stimulated secretion of [3H]steroid hormones. The effects seen with compound U18666A appeared to be specific for this molecule, since another hydrophobic amine, imipramine, did not in our experiments affect cholesterol translocation or ACAT activation. Since different cell types display sensitivity to U18666A in various intracellular cholesterol transfer processes, they appear to have a common U18666A-sensitive regulatory mechanism.

Higher total serum cholesterol levels are associated with less severe strokes and lower all-cause mortality: ten-year follow-up of ischemic strokes in the Copenhagen Stroke Study.

PubMed

Olsen, Tom Skyhøj; Christensen, Rune Haubo Bojesen; Kammersgaard, Lars Peter; Andersen, Klaus Kaae

2007-10-01

Evidence of a causal relation between serum cholesterol and stroke is inconsistent. We investigated the relation between total serum cholesterol and both stroke severity and poststroke mortality to test the hypothesis that hypercholesterolemia is primarily associated with minor stroke. In the study, 652 unselected patients with ischemic stroke arrived at the hospital within 24 hours of stroke onset. A measure of total serum cholesterol was obtained in 513 (79%) within the 24-hour time window. Stroke severity was measured with the Scandinavian Stroke Scale (0=worst, 58=best); a full cardiovascular risk profile was established for all. Death within 10 years after stroke onset was obtained from the Danish Registry of Persons. Mean+/-SD age of the 513 patients was 75+/-10 years, 54% were women, and the mean+/-SD Scandinavian Stroke Scale score was 39+/-17. Serum cholesterol was inversely and almost linearly related to stroke severity: an increase of 1 mmol/L in total serum cholesterol resulted in an increase in the Scandinavian Stroke Scale score of 1.32 (95% CI, 0.28 to 2.36, P=0.013), meaning that higher cholesterol levels are associated with less severe strokes. A survival analysis revealed an inverse linear relation between serum cholesterol and mortality, meaning that an increase of 1 mmol/L in cholesterol results in a hazard ratio of 0.89 (95% CI, 0.82 to 0.97, P=0.01). The results of our study support the hypothesis that a higher cholesterol level favors development of minor strokes. Because of selection, therefore, major strokes are more often seen in patients with lower cholesterol levels. Poststroke mortality, therefore, is inversely related to cholesterol.

Probiotic Properties of Lactobacillus Strains Isolated from Tibetan Kefir Grains

PubMed Central

Zheng, Yongchen; Lu, Yingli; Wang, Jinfeng; Yang, Longfei; Pan, Chenyu; Huang, Ying

2013-01-01

The objective of this study was to evaluate the functional properties of lactic acid bacteria (LAB) isolated from Tibetan kefir grains. Three Lactobacillus isolates identified as Lactobacillus acidophilus LA15, Lactobacillus plantarum B23 and Lactobacillus kefiri D17 that showed resistance to acid and bile salts were selected for further evaluation of their probiotic properties. The 3 selected strains expressed high in vitro adherence to Caco-2 cells. They were sensitive to gentamicin, erythromycin and chloramphenicol and resistant to vancomycin with MIC values of 26 µg/ml. All 3 strains showed potential bile salt hydrolase (BSH) activity, cholesterol assimilation and cholesterol co-precipitation ability. Additionally, the potential effect of these strains on plasma cholesterol levels was evaluated in Sprague-Dawley (SD) rats. Rats in 4 treatment groups were fed the following experimental diets for 4 weeks: a high-cholesterol diet, a high-cholesterol diet plus LA15, a high-cholesterol diet plus B23 or a high-cholesterol diet plus D17. The total cholesterol, triglyceride and low-density lipoprotein cholesterol levels in the serum were significantly (P<0.05) decreased in the LAB-treated rats compared with rats fed a high-cholesterol diet without LAB supplementation. The high-density lipoprotein cholesterol levels in groups B23 and D17 were significantly (P<0.05) higher than those in the control and LA15 groups. Additionally, both fecal cholesterol and bile acid levels were significantly (P<0.05) increased after LAB administration. Fecal lactobacilli counts were significantly (P<0.05) higher in the LAB treatment groups than in the control groups. Furthermore, the 3 strains were detected in the rat small intestine, colon and feces during the feeding trial. The bacteria levels remained high even after the LAB administration had been stopped for 2 weeks. These results suggest that these strains may be used in the future as probiotic starter cultures for manufacturing novel fermented foods. PMID:23894554

EFFECT OF THE LEVEL AND TYPE OF DIETARY FAT ON THE METABOLISM OF CHOLESTEROL AND BETA LIPOPROTEINS IN THE CEBUS MONKEY

PubMed Central

Portman, Oscar W.; Hegsted, D. Mark; Stare, Fredrick J.; Bruno, Dorothy; Murphy, Robert; Sinisterra, Leonardo

1956-01-01

A study was carried out to determine the effect of the level and type of dietary fat on the concentration of cholesterol and beta lipoproteins in the sera of Cebus monkeys. Three groups of monkeys were fed isocaloric diets containing a fixed ratio of alpha protein and cholesterol to calories but with different amounts of corn oil and sucrose. Corn oil provided 10, 32, and 45 per cent of the calories in the three diets, and the level of sucrose was varied inversely. After 8 weeks the serum cholesterol and Sf 12 to 100 beta lipoprotein concentrations were significantly greater in the medium and high fat groups. When corn oil was decreased from 45 to 10 per cent of dietary calories and sucrose was increased, the serum cholesterol fell in all cases, and when the reverse change was made, the concentration of serum cholesterol increased. Variation in dietary sucrose had no specific effect. Substitution of starch for sucrose with diets otherwise constant did not cause significant change in the concentration of serum cholesterol. When monkeys fed corn oil diets at any of three levels were changed to hydrogenated cottonseed oil diets at the same level, the serum cholesterol and Sf 12 to 100 beta lipoproteins rose. However, hydrogenated cottonseed oil had no greater hypercholesteremic effect than did corn oil in the absence of dietary cholesterol. Diets containing lard with cholesterol also produced strikingly greater serum lipide responses than did diets based on corn oil and cholesterol. Hydrogenated cottonseed oil had a greater hypercholesteremic effect than an unhydrogenated cottonseed oil from the same lot. Preliminary studies indicated that the saturated fats (hydrogenated cottonseed oil) produced the most striking elevation of serum cholesterol values (above controls fed corn oil) when casein was the dietary protein. PMID:13376806

DIETARY FAT AND HYPERCHOLESTEREMIA IN THE CEBUS MONKEY

PubMed Central

Portman, Oscar W.; Sinisterra, Leonardo

1957-01-01

A series of studies of cholesterol metabolism in the Cebus monkey were carried out in an attempt to understand the mechanisms responsible for the great differences in serum cholesterol levels when different dietary fats were used. Three groups of monkeys, one fed diets including 45 per cent of calories as corn oil, a second corn oil plus cholesterol (0.1 gm./100 calories), and a third lard plus cholesterol for 5 months (mean serum cholesterol values were 237, 268, and 601 mg. per cent, respectively) were injected with emulsions of cholesterol-4-C14. The mean biological half-lives for the disappearance of serum radiocholesterol were 8.8, 8.4, and 6.6 days respectively. Esterification of radiocholesterol as measured by equilibration of specific activities of serum-free cholesterol and total cholesterol was delayed in the monkeys fed lard plus cholesterol. When cholesterol-4-C-14-stearate was given intravenously to a series of monkeys, an erratic non-exponential biological decay curve resulted. Specific activity for free serum cholesterol was greater than that for total cholesterol within 1 hour after the injection. After 7 months on experimental diets including corn oil with added cholesterol and lard with added cholesterol the levels of lipides in most tissues were not different for the two dietary groups, nor were they appreciably elevated above previous control figures for monkeys not fed cholesterol. Total lipide levels in the adrenals of monkeys fed corn oil were twice those of monkeys fed lard. Monkeys were fasted before and after intragastric administration of cholesterol-4-C14 in small formula meals including various fats and fatty acids. The disappearance of total cholesterol from the serum consisted of a rapid followed by a slow exponential function. The type of fat and fatty acid appeared to influence the rate of disappearance of radiocholesterol. There was a broad range of apparent activity of the different fats and fatty acids in promoting cholesterol absorption. PMID:13475627

Serum cholesterol levels, HMG-CoA reductase inhibitors and the risk of intracerebral haemorrhage. The Multicenter Study on Cerebral Haemorrhage in Italy (MUCH-Italy).

PubMed

Pezzini, Alessandro; Grassi, Mario; Iacoviello, Licia; Zedde, Marialuisa; Marcheselli, Simona; Silvestrelli, Giorgio; DeLodovici, Maria Luisa; Sessa, Maria; Zini, Andrea; Paciaroni, Maurizio; Azzini, Cristiano; Gamba, Massimo; Del Sette, Massimo; Toriello, Antonella; Gandolfo, Carlo; Bonifati, Domenico Marco; Tassi, Rossana; Cavallini, Anna; Chiti, Alberto; Calabrò, Rocco Salvatore; Musolino, Rossella; Bovi, Paolo; Tomelleri, Giampaolo; Di Castelnuovo, Augusto; Vandelli, Laura; Ritelli, Marco; Agnelli, Giancarlo; De Vito, Alessandro; Pugliese, Nicola; Martini, Giuseppe; Lanari, Alessia; Ciccone, Alfonso; Lodigiani, Corrado; Malferrari, Giovanni; Del Zotto, Elisabetta; Morotti, Andrea; Costa, Paolo; Poli, Loris; De Giuli, Valeria; Bonaiti, Silvia; La Spina, Paolo; Marcello, Norina; Micieli, Giuseppe; de Gaetano, Giovanni; Colombi, Marina; Padovani, Alessandro

2016-09-01

Although a concern exists that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) might increase the risk of intracerebral haemorrhage (ICH), the contribution of these agents to the relationship between serum cholesterol and disease occurrence has been poorly investigated. We compared consecutive patients having ICH with age and sex-matched stroke-free control subjects in a case-control analysis, as part of the Multicenter Study on Cerebral Haemorrhage in Italy (MUCH-Italy), and tested the presence of interaction effects between total serum cholesterol levels and statins on the risk of ICH. A total of 3492 cases (mean age, 73.0±12.7 years; males, 56.6%) and 3492 control subjects were enrolled. Increasing total serum cholesterol levels were confirmed to be inversely associated with ICH. We observed a statistical interaction between total serum cholesterol levels and statin use for the risk of haemorrhage (Interaction OR (IOR), 1.09; 95% CI 1.05 to 1.12). Increasing levels of total serum cholesterol were associated with a decreased risk of ICH within statin strata (average OR, 0.87; 95% CI 0.86 to 0.88 for every increase of 0.26 mmol/l of total serum cholesterol concentrations), while statin use was associated with an increased risk (OR, 1.54; 95% CI 1.31 to 1.81 of the average level of total serum cholesterol). The protective effect of serum cholesterol against ICH was reduced by statins in strictly lobar brain regions more than in non-lobar ones. Statin therapy and total serum cholesterol levels exhibit interaction effects towards the risk of ICH. The magnitude of such effects appears higher in lobar brain regions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Cholesterol modulates the cellular localization of Orai1 channels and its disposition among membrane domains.

PubMed

Bohórquez-Hernández, A; Gratton, Enrico; Pacheco, Jonathan; Asanov, Alexander; Vaca, Luis

2017-12-01

Store Operated Calcium Entry (SOCE) is one of the most important mechanisms for calcium mobilization in to the cell. Two main proteins sustain SOCE: STIM1 that acts as the calcium sensor in the endoplasmic reticulum (ER) and Orai1 responsible for calcium influx upon depletion of ER. There are many studies indicating that SOCE is modulated by the cholesterol content of the plasma membrane (PM). However, a myriad of questions remain unanswered concerning the precise molecular mechanism by which cholesterol modulates SOCE. In the present study we found that reducing PM cholesterol results in the internalization of Orai1 channels, which can be prevented by overexpressing caveolin 1 (Cav1). Furthermore, Cav1 and Orai1 associate upon SOCE activation as revealed by FRET and coimmunoprecipitation assays. The effects of reducing cholesterol were not limited to an increased rate of Orai1 internalization, but also, affects the lateral movement of Orai1, inducing movement in a linear pattern (unobstructed diffusion) opposite to basal cholesterol conditions were most of Orai1 channels moves in a confined space, as assessed by Fluorescence Correlation Spectroscopy, Cav1 overexpression inhibited these alterations maintaining Orai1 into a confined and partially confined movement. These results not only highlight the complex effect of cholesterol regulation on SOCE, but also indicate a direct regulatory effect on Orai1 localization and compartmentalization by this lipid. Copyright © 2017 Elsevier B.V. All rights reserved.

Malnutrition-Inflammation Modifies the Relationship of Cholesterol with Cardiovascular Disease

PubMed Central

Astor, Brad C.; Greene, Tom; Erlinger, Thomas; Kusek, John W.; Lipkowitz, Michael; Lewis, Julia A.; Randall, Otelio S.; Hebert, Lee; Wright, Jackson T; Kendrick, Cynthia A.; Gassman, Jennifer; Bakris, George; Kopple, Joel D.; Appel, Lawrence J.

2010-01-01

In moderate and severe CKD, the association of cholesterol with subsequent cardiovascular disease (CVD) is weak. We examined whether malnutrition or inflammation (M-I) modifies the risk relationship between cholesterol levels and CVD events in African Americans with hypertensive CKD and a GFR between 20 and 65 ml/min per 1.73 m2. We stratified 990 participants by the presence or absence of M-I, defined as body mass index <23 kg/m2 or C-reactive protein >10 mg/L at baseline. The primary composite outcome included cardiovascular death or first hospitalization for coronary artery disease, stroke, or congestive heart failure occurring during a median follow-up of 77 months. Baseline total cholesterol (212 ± 48 versus 212 ± 44 mg/dl) and overall incidence of the primary CVD outcome (19 versus 21%) were similar in participants with (n = 304) and without (n = 686) M-I. In adjusted analyses, the CVD composite outcome exhibited a significantly stronger relationship with total cholesterol for participants without M-I than for participants with M-I at baseline (P < 0.02). In the non–M-I group, the cholesterol-adjusted hazard ratio (HR) for CVD increased progressively across cholesterol levels: HR = 1.19 [95% CI; 0.77, 1.84] and 2.18 [1.43, 3.33] in participants with cholesterol 200 to 239 and ≥240 mg/dl, respectively (reference: cholesterol <200). In the M-I group, the corresponding HRs did not vary significantly by cholesterol level. In conclusion, the presence of M-I modifies the risk relationship between cholesterol level and CVD in African Americans with hypertensive CKD. PMID:20864686

Review of 5 years of a combined dietary and physical fitness intervention for control of serum cholesterol

NASA Technical Reports Server (NTRS)

Angotti, C. M.; Levine, M. S.

1994-01-01

A chart review covering the first 5 years of clinical experience with a combined dietary and exercise intervention program for the reduction of hypercholesterolemia at the National Aeronautics and Space Administration headquarters demonstrated the program's success in maintaining high-density lipoprotein cholesterol (HDL-C) levels while significantly lowering total serum cholesterol levels. This combined program also resulted in improved ratios of total serum cholesterol to HDL-C and lowered levels of low-density lipoprotein cholesterol, thus further reducing the risk for cardiovascular disease. The National Aeronautics and Space Administration Cardiovascular Risk Reduction Program was developed after it was determined that although dietary intervention alone improved total cholesterol levels, it often resulted in a more than proportionate decrease in HDL-C and a worsening of the ratio of cholesterol to HDL-C. An approach was needed that would positively affect all factors of the lipid profile. The findings from the program indicate that reduction of cardiovascular risk can be accomplished easily and effectively at the worksite through dietary intervention, personal monitoring, and a reasonable exercise program.

Infection of Hepatocytes With HCV Increases Cell Surface Levels of Heparan Sulfate Proteoglycans, Uptake of Cholesterol and Lipoprotein, and Virus Entry by Up-regulating SMAD6 and SMAD7.

PubMed

Zhang, Fang; Sodroski, Catherine; Cha, Helen; Li, Qisheng; Liang, T Jake

2017-01-01

The signaling molecule and transcriptional regulator SMAD6, which inhibits the transforming growth factor β signaling pathway, is required for infection of hepatocytes by hepatitis C virus (HCV). We investigated the mechanisms by which SMAD6 and another inhibitory SMAD (SMAD7) promote HCV infection in human hepatoma cells and hepatocytes. We infected Huh7 and Huh7.5.1 cells and primary human hepatocytes with Japanese fulminant hepatitis-1 (JFH1) HCV cell culture system (HCVcc). We then measured HCV binding, intracellular levels of HCV RNA, and expression of target genes. We examined HCV entry in HepG2/microRNA (miR) 122/CD81 cells, which support entry and replication of HCV, were transfected these cells with small interfering RNAs targeting inhibitory SMADs to analyze gene expression profiles. Uptake of labeled low-density lipoprotein (LDL) and cholesterol was measured. Cell surface proteins were quantified by flow cytometry. We obtained liver biopsy samples from 69 patients with chronic HCV infection and 19 uninfected individuals (controls) and measured levels of syndecan 1 (SDC1), SMAD7, and SMAD6 messenger RNAs (mRNAs). Small interfering RNA knockdown of SMAD6 blocked the binding and infection of hepatoma cell lines and primary human hepatocytes by HCV, whereas SMAD6 overexpression increased HCV infection. We found levels of mRNAs encoding heparan sulfate proteoglycans (HSPGs), particularly SDC1 mRNA, and cell surface levels of heparan sulfate to be reduced in cells after SMAD6 knockdown. SMAD6 knockdown also reduced transcription of genes encoding lipoprotein and cholesterol uptake receptors, including the LDL receptor (LDLR), the very LDLR, and the scavenger receptor class B member 1 in hepatocytes; knockdown of SMAD6 also inhibited cell uptake of cholesterol and lipoprotein. Overexpression of SMAD6 increased the expression of these genes. Similar effects were observed with knockdown and overexpression of SMAD7. In addition, HCV infection of cells increased the expression of SMAD6, which required the activity of nuclear factor-κB, but not transforming growth factor β. Liver tissues from patients with chronic HCV infection had significantly higher levels of SMAD6, SMAD7, and HSPG mRNAs than controls. In studies of hepatoma cell lines and primary human hepatocytes, we found that infection with HCV leads to activation of nuclear factor-κB, resulting in increased expression of SMAD6 and SMAD7. Up-regulation of SMAD6 and SMAD7 induces the expression of HSPGs, such as SDC1, as well as LDLR, very LDLR, and the scavenger receptor class B member 1, which promote HCV entry and propagation, as well as cellular uptake of cholesterol and lipoprotein. Copyright © 2017 AGA Institute. Published by Elsevier Inc. All rights reserved.

Lipid nanocapsules containing the non-ionic surfactant Solutol HS15 inhibit the transport of calcium through hyperforin-activated channels in neuronal cells.

PubMed

Chauvet, Sylvain; Barras, Alexandre; Boukherroub, Rabah; Bouron, Alexandre

2015-12-01

Hyperforin is described as a natural antidepressant inhibiting the reuptake of neurotransmitters and also activating cation channels. However the blood-brain barrier limits the access to the brain of this biomolecule. To circumvent this problem it was envisaged to encapsulate hyperforin into biomimetic lipid nano-carriers like lipid nanocapsules (LNCs). When testing the safety of 25 nm LNCs it appeared that they strongly blocked hyperforin-activated Ca2+ channels of cultured cortical neurons. This inhibition was due to one of their main component: solutol HS15 (polyoxyethylene-660-12-hydroxy stearate), a non-ionic soluble surfactant. Solutol HS15 rapidly depresses in a concentration-dependent manner the entry of Ca2+ through hyperforin-activated channels without influencing store-operated channels. This effect is mimicked by Brij58 but not by PEG600, indicating that the lipid chain of Solutol HS15 is important in determining its effects on the channels. The inhibition of the Ca2+ fluxes depends on the cellular cholesterol content; it is stronger after depleting cholesterol with methyl-β-cyclodextrin and is nearly absent on cells cultured in a cholesterol-rich medium. When chronically applied for 24 h, Solutol HS15 slightly up-regulates the entry of Ca2+ through hyperforin-activated channels. Similar observations were made when testing 25 nm lipid nanocapsules containing the surfactant Solutol HS15. Altogether, this study shows that Solutol HS15 perturbs in a cholesterol-dependent manner the activity of some neuronal channels. This is the first demonstration that LNCs containing this surfactant can influence cellular calcium signaling in the brain, a finding that can have important clinical implications. Copyright © 2015 Elsevier Ltd. All rights reserved.

Critical role of the lipid rafts in caprine herpesvirus type 1 infection in vitro.

PubMed

Pratelli, Annamaria; Colao, Valeriana

2016-01-04

The fusion machinery for herpesvirus entry in the host cells involves the interactions of viral glycoproteins with cellular receptors, although additional viral and cellular domains are required. Extensive areas of the plasma membrane surface consist of lipid rafts organized into cholesterol-rich microdomains involved in signal transduction, protein sorting, membrane transport and in many processes of viruses infection. Because of the extraction of cholesterol leads to disorganization of lipid microdomains and to dissociation of proteins bound to the lipid rafts, we investigated the effect of cholesterol depletion by methyl-β-cyclodextrin (MβCD) on caprine herpesvirus 1 (CpHV.1) in three important phases of virus infection such as binding, entry and post-entry. MβCD treatment did not prejudice virus binding to cells, while a dose-dependent reduction of the virus yield was observed at the virus entry stage, and 30 mM MβCD reduced infectivity evidently. Treatment of MDBK after virus entry revealed a moderate inhibitory effect suggesting that cholesterol is mainly required during virus entry rather than during the post-entry stage. Alteration of the envelope lipid composition affected virus entry and a noticeable reduction in virus infectivity was detected in the presence of 15 mM MβCD. Considering that the recognition of a host cell receptor is a crucial step in the start-up phase of infection, these data are essential for the study of CpHV.1 pathogenesis. To date virus receptors for CpHV.1 have not yet been identified and further investigations are required to state that MβCD treatment affects the expression of the viral receptors. Copyright © 2015 Elsevier B.V. All rights reserved.

Addition of Garlic Extract in Ration to Reduce Cholesterol Level of Broiler

NASA Astrophysics Data System (ADS)

Utami, M. M. D.; Pantaya, D.; Agus, A.

2018-01-01

The purpose of this research is to know the effect of garlic extract (GE) in reducing cholesterol level of broiler chicken by analyzing cholesterol level of broiler chicken blood. Two hundred one day broiler age were used in this study for 35 days. The chickens were randomly divided into four treatments, each treatment consist of five replications and each repetition consist of ten chickens. This research is used completely randomized design, such as: T0: 0% EBP, T1: 2%, T2: 4% and T3: 6%. Furthermore, at age 35 days each chicken was taken blood to be analyzed cholesterol levels, low density lipoprotein (LDL), high density lipoprotein (HDL) and calculated the ratio of LDL and HDL levels. The data obtained were analyzed using software from Statistical Product and Service Solution (SPSS 16.0). The results of significant analysis continued by Duncan’s New Multiple Range Test. Addition of GE from the 2% level decreases (P <0.05) of LDL and total cholesterol, and increases HDL and HDL-LDL ratio. The conclusions is obtained garlic extract plays an important role in lowering cholesterol levels of broiler meat.

Intracellular trafficking of the free cholesterol derived from LDL cholesteryl ester is defective in vivo in Niemann-Pick C disease: insights on normal metabolism of HDL and LDL gained from the NP-C mutation.

PubMed

Shamburek, R D; Pentchev, P G; Zech, L A; Blanchette-Mackie, J; Carstea, E D; VandenBroek, J M; Cooper, P S; Neufeld, E B; Phair, R D; Brewer, H B; Brady, R O; Schwartz, C C

1997-12-01

Niemann-Pick C disease (NP-C) is a rare inborn error of metabolism with hepatic involvement and neurological sequelae that usually manifest in childhood. Although in vitro studies have shown that the lysosomal distribution of LDL-derived cholesterol is defective in cultured cells of NP-C subjects, no unusual characteristics mark the plasma lipoprotein profiles. We set out to determine whether anomalies exist in vivo in the cellular distribution of newly synthesized, HDL-derived or LDL-derived cholesterol under physiologic conditions in NP-C subjects. Three affected and three normal male subjects were administered [14C]mevalonate as a tracer of newly synthesized cholesterol and [3H]cholesteryl linoleate in either HDL or LDL to trace the distribution of lipoprotein-derived free cholesterol. The rate of appearance of free [14C]- and free [3H]cholesterol in the plasma membrane was detected indirectly by monitoring their appearance in plasma and bile. The plasma disappearance of [3H]cholesteryl linoleate was slightly faster in NP-C subjects regardless of its lipoprotein origin. Appearance of free [14C] cholesterol ill the plasma (and in bile) was essentially identical in normal and affected individuals as was the initial appearance of free [3H]cholesterol derived from HDL, observed before extensive exchange occurred of the [3H]cholesteryl linoleate among lipoproteins. In contrast, the rate of appearance of LDL-derived free [3H]cholesterol in the plasma membrane of NP-C subjects, as detected in plasma and bile, was retarded to a similar extent that LDL cholesterol metabolism was defective in cultured fibroblasts of these affected subjects. These findings show that intracellular distribution of both newly synthesized and HDL-derived cholesterol are essentially unperturbed by the NP-C mutation, and therefore occur by lysosomal-independent paths. In contrast, in NP-C there is defective trafficking of LDL-derived cholesterol to the plasma membrane in vivo as well as in vitro. The in vivo assay of intracellular cholesterol distribution developed herein should prove useful to quickly evaluate therapeutic interventions for NP-C.

Cholesterol blocks spontaneous insertion of membrane proteins into liposomes of phosphatidylcholine.

PubMed

Nakamura, Shota; Suzuki, Sonomi; Saito, Hiroaki; Nishiyama, Ken-Ichi

2018-04-01

Spontaneous insertion of membrane proteins into liposomes formed from Escherichia coli polar phospholipids is blocked by diacylglycerol (DAG) at a physiological level. We found that cholesterol also blocks this spontaneous insertion, although a much larger amount is necessary for sufficient blockage. Reversely, sphingomyelin enhanced the spontaneous insertion. DAG at a physiological level was found not to block spontaneous insertion into liposomes formed from phosphatidylcholine (PC), while non-physiologically high concentrations of DAG reduced it. On the other hand, cholesterol blocked the spontaneous insertion into PC liposomes at a physiological level, explaining that both PC and cholesterol are absent in E. coli. While sphingomyelin did not enhance spontaneous insertion into PC liposomes, the effect of cholesterol on blockage of spontaneous insertion was dominant over that of sphingomyelin, suggesting that cholesterol functions as a blocker of disordered spontaneous insertion in eukaryotic cells. Lower amount of cholesterol was necessary to block spontaneous insertion into ER-mimic liposomes, explaining that ER membranes contain less amount of cholesterol. These results also explain that cholesterol, but not DAG, is involved in blockage of spontaneous insertion in eukaryotic cells, since DAG plays an important role as a second messenger in signal transduction.

Randomized controlled trial of a nonpharmacologic cholesterol reduction program at the worksite.

PubMed

Bruno, R; Arnold, C; Jacobson, L; Winick, M; Wynder, E

1983-07-01

Under experimental clinical conditions diet modification has been shown to reduce serum cholesterol levels. This paper reports such a positive response to a nonpharmacologic, behavioral education program at the worksite. Employees at the New York Telephone Company corporate headquarters were assigned randomly to treatment and control groups. Treatment consisted of an 8-week group cholesterol reduction program conducted during employee lunch hours. It comprised a multiple-treatment approach--food behavior change techniques combined with nutrition education, physical activity planning, and self-management skills. The treatment group showed substantial change compared with the control group at the program's completion. Those treated displayed a significant 6.4% reduction in total serum cholesterol (266 mg% average at baseline) as compared with control subjects with a corresponding decrease in high-density lipoprotein levels. A significant increase in nutrition knowledge and moderate weight loss were also documented for this group. The magnitudes of a participant's baseline serum cholesterol level and his/her reduction in percentage of ideal body weight were positively and independently correlated with percentage changes in serum cholesterol levels. Over the same period, decreases in high-density lipoprotein levels and no changes in serum cholesterol, weight, and nutrition knowledge were observed for the control group. Overall, participants in the treatment program successfully reduced the coronary heart disease risk factors of elevated cholesterol and weight. Directions for future study are suggested.

Relationship between Icodextrin use and decreased level of small low-density lipoprotein cholesterol fractioned by high-performance gel permeation chromatography

PubMed Central

2013-01-01

Background Because of the absorption of glucose in peritoneal dialysis (PD) solution, PD patients show an atherogenic lipid profile, which is predictive of poor survival in PD patients. Lipoprotein subclasses consist of a continuous spectrum of particles of different sizes and densities (fraction). In this study, we investigated the lipoprotein fractions in PD patients with controlled serum low-density lipoprotein (LDL) cholesterol level, and evaluated the effects of icodextrin on lipid metabolism. Methods Forty-nine PD patients were enrolled in this cross-sectional study in Japan. The proportions of cholesterol levels to total cholesterol level (cholesterol proportion) in 20 lipoprotein fractions were measured using an improved method of high-performance gel permeation chromatography (HPGPC). Results Twenty-six patients used icodextrin. Although no significant differences in cholesterol levels in LDL and high-density lipoprotein (HDL) were observed between the patients using icodextrin (icodextrin group) and control groups, HPGPC showed that the icodextrin group had significantly lower cholesterol proportions in the small LDL (t-test, p=0.053) and very small LDL (p=0.019), and significantly higher cholesterol proportions in the very large HDL and large HDL than the control group (p=0.037; p=0.066, respectively). Multivariate analysis adjusted for patient characteristics and statin use showed that icodextrin use was negatively associated with the cholesterol proportions in the small LDL (p=0.037) and very small LDL (p=0.026), and positively with those in the very large HDL (p=0.040), large HDL (p=0.047), and medium HDL (p=0.009). Conclusions HPGPC showed the relationship between icodextrin use and the cholesterol proportions in lipoprotein fractions in PD patients. These results suggest that icodextrin may improve atherogenic lipid profiles in a manner different from statin. PMID:24161017

A dietary cholesterol challenge study to assess Chlorella supplementation in maintaining healthy lipid levels in adults: a double-blinded, randomized, placebo-controlled study.

PubMed

Kim, Sangmi; Kim, Joohee; Lim, Yeni; Kim, You Jin; Kim, Ji Yeon; Kwon, Oran

2016-05-13

Previous animal studies suggested that Chlorella, a unicellular green alga, has a preventive role in maintaining serum cholesterol levels against excess dietary cholesterol intake. This study aimed to conduct a pioneering investigation to clarify this issue in healthy subjects by adopting a dietary cholesterol challenge, which has not been used previously in similar studies of Chlorella in hypercholesterolemia. In this double blind, randomized, placebo-controlled study, 34 participants ingested 510 mg of dietary cholesterol from three eggs concomitantly with a usual dose of Chlorella (5 g/d) or a matched placebo for 4 weeks. The dietary cholesterol challenge induced consistently higher concentrations of serum total cholesterol (TC, P < 0.001), LDL-C (P = 0.004), and HDL-C (P = 0.010) compared with baseline values, suggesting that the challenge was reliable. Thus, we observed a preventive action of Chlorella in maintaining serum TC versus placebo levels (3.5 % versus 9.8 %, respectively; P = 0.037) and LDL-C versus placebo levels (1.7 % versus 14.3 %, respectively; P = 0.012) against excessive dietary cholesterol intake and in augmenting HDL-C versus placebo levels (8.3 % versus 3.8 %, respectively). Furthermore, serum α-carotene showed the best separation between the placebo and Chlorella groups (R(2)X and R(2)Y > 0.5; Q(2) > 0.4). The results suggest that a fully replicated dietary cholesterol challenge may be useful in assessing the effectiveness of dietary supplements in maintaining the serum lipid profiles of adults whose habitual diets are high in cholesterol. WHO International Clinical Trials Registry Platform ( KCT0000258 ).

Effect of Cholesterol on the Structure of a Five-Component Mitochondria-Like Phospholipid Membrane.

PubMed

Cathcart, Kelly; Patel, Amit; Dies, Hannah; Rheinstädter, Maikel C; Fradin, Cécile

2015-10-30

Cellular membranes have a complex phospholipid composition that varies greatly depending on the organism, cell type and function. In spite of this complexity, most structural data available for phospholipid bilayers concern model systems containing only one or two different phospholipids. Here, we examine the effect of cholesterol on the structure of a complex membrane reflecting the lipid composition of mitochondrial membranes, with five different types of headgroups (phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS) and cardiolipin (CL)) and a variety of hydrocarbon tails. This particular system was chosen because elevated cholesterol contents in mitochondrial membranes have been linked to a breaking down of Bax-mediated membrane permeabilization and resistance to cancer treatments. High resolution electron density profiles were determined by X-ray reflectivity, while the area per phospholipid chain, Apc, and the chain order parameter, SX-ray, were determined by wide-angle X-ray scattering (WAXS). We show that chain order increases upon the addition of cholesterol, resulting in both a thickening of the lipid bilayer and a reduction in the average surface area per phospholipid chain. This effect, well known as cholesterol's condensation effect, is similar, but not as pronounced as for single-component phospholipid membranes. We conclude by discussing the relevance of these findings for the insertion of the pro-apoptotic protein Bax in mitochondrial membranes with elevated cholesterol content.

THE PATHOGENESIS OF HYPERLIPEMIA INDUCED BY MEANS OF SURFACE-ACTIVE AGENTS

PubMed Central

Hirsch, Robert L.; Kellner, Aaron

1956-01-01

Rabbits subjected to subtotal hepatectomy failed to develop increased serum cholesterol levels following parenteral injection of triton WR 1339, the finding indicating that the liver is essential for the establishment of the hypercholesterolemia induced by surface-active agents. The cholesterol content of the livers of rabbits rendered hyperlipemic by means of triton remained unchanged both during the rapid rise of the serum cholesterol levels and during the return to normal values. By contrast, the cholesterol content of the livers of rabbits fed cholesterol rose progressively over a period of 5 weeks, concommittant with the increase in serum cholesterol levels. The findings provide support for the hypothesis that surface-active agents bring about hyperlipemia by altering the circulating lipoproteins in some manner so that they are retained in the circulating body fluids. PMID:13332177

Enterococcus faecium WEFA23 from infant lessens high-fat-diet-induced hyperlipidemia via cholesterol 7-alpha-hydroxylase gene by altering the composition of gut microbiota in rats.

PubMed

Huang, Fuqing; Zhang, Fen; Xu, Di; Zhang, Zhihong; Xu, Feng; Tao, Xueying; Qiu, Liang; Wei, Hua

2018-06-20

Enterococcus faecium WEFA23 is a potential probiotic strain from Chinese infants with the ability to decrease cholesterol levels. Aiming to explore the mechanism of E. faecium WEFA23 in lowering cholesterol in vivo, we examined the gene transcriptions related to cholesterol metabolism, the composition of bile acids in feces, the synthesis of trimethylamine N-oxide (TMAO) in liver, and the composition of the gut microbiota of rats. We found that E. faecium WEFA23 enhanced the synthesis of bile acids by promoting cholesterol excretion, upregulating the genes transcript level relevant to cholesterol decomposition and transportation, and downregulating the genes involved in cholesterol synthesis. In addition, E. faecium WEFA23 not only downregulated the transcript levels of farnesoid X receptor and fibroblast growth factor 15 as well as flavin-containing monooxygenase 3, but also decreased the TMAO production followed by increasing the CYP7A1 transcript level. Furthermore, when orally administered to rats for 35 d, E. faecium WEFA23 improved the gut microbiota diversity of rats fed a high-fat diet. Therein, the ratio of Bacteroidetes to Firmicutes and the abundance of Rikenellaceae increased, whereas the number of Veillonellaceae decreased. These results suggest that reduction of cholesterol level by E. faecium WEFA23 might be related to the changes in the gut microbiota. Our finding provides important information on lowering cholesterol by E. faecium and reveals that Enterococcus spp. might have the potential to decrease the TMAO level. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The isoform-specific pathological effects of apoE4 in vivo are prevented by a fish oil (DHA) diet and are modified by cholesterol.

PubMed

Kariv-Inbal, Zehavit; Yacobson, Shiri; Berkecz, Robert; Peter, Maria; Janaky, Tamas; Lütjohann, Dieter; Broersen, Laus M; Hartmann, Tobias; Michaelson, Daniel M

2012-01-01

Apolipoprotein E4 (apoE4) is the most prevalent genetic risk factor for Alzheimer's disease (AD). Epidemiological studies revealed that consumption of docosahexaenoic acid (DHA: 22 : 6 (ω3)), a major brain polyunsaturated fatty acid, is protective for AD and that elevated cholesterol levels are an AD risk factor. We presently investigated the extent to which the pathological effects of apoE4 in vivo can be prevented by consuming fish oil (DHA) or can be modified by cholesterol. Accordingly, apoE3- and apoE4-targeted replacement mice were subjected, following weaning, to a fish oil diet enriched in DHA and to a cholesterol-containing diet under regular and enriched environments. Cholesterol metabolism in the hippocampus and the corresponding phospholipid and fatty acid levels were affected by fish oil (DHA) and cholesterol diets and by environmental stimulation. Importantly, cholesterol metabolism and the fatty acid levels were not affected by apoE4. The phospholipid levels were, however, affected by apoE4. This effect was most pronounced in the cholesterol-fed mice and was abolished by the fish oil (DHA) diet. ApoE4 elevated hippocampal intraneuronal amyloid-β levels under regular conditions and lowered them following environmental stimulation, relative to those of the apoE3 mice. ApoE4 also elevated the levels of the presynaptic transporters Vglut and Vgat, and decreased behavioral performance in an object recognition test. Importantly, all of these apoE4 phenotypes were abolished by the fish oil (DHA) diet, whereas the cholesterol diet modified them. These findings suggest that a fish oil (DHA) diet could be used to attenuate the effects of apoE4 in AD.

Polycaprolactone/maltodextrin nanocarrier for intracellular drug delivery: formulation, uptake mechanism, internalization kinetics, and subcellular localization.

PubMed

Korang-Yeboah, Maxwell; Gorantla, Yamini; Paulos, Simon A; Sharma, Pankaj; Chaudhary, Jaideep; Palaniappan, Ravi

2015-01-01

Prostate cancer (PCa) disease progression is associated with significant changes in intracellular and extracellular proteins, intracellular signaling mechanism, and cancer cell phenotype. These changes may have direct impact on the cellular interactions with nanocarriers; hence, there is the need for a much-detailed understanding, as nanocarrier cellular internalization and intracellular sorting mechanism correlate directly with bioavailability and clinical efficacy. In this study, we report the differences in the rate and mechanism of cellular internalization of a biocompatible polycaprolactone (PCL)/maltodextrin (MD) nanocarrier system for intracellular drug delivery in LNCaP, PC3, and DU145 PCa cell lines. PCL/MD nanocarriers were designed and characterized. PCL/MD nanocarriers significantly increased the intracellular concentration of coumarin-6 and fluorescein isothiocyanate-labeled bovine serum albumin, a model hydrophobic and large molecule, respectively. Fluorescence microscopy and flow cytometry analysis revealed rapid internalization of the nanocarrier. The extent of nanocarrier cellular internalization correlated directly with cell line aggressiveness. PCL/MD internalization was highest in PC3 followed by DU145 and LNCaP, respectively. Uptake in all PCa cell lines was metabolically dependent. Extraction of endogenous cholesterol by methyl-β-cyclodextrin reduced uptake by 75%±4.53% in PC3, 64%±6.01% in LNCaP, and 50%±4.50% in DU145, indicating the involvement of endogenous cholesterol in cellular internalization. Internalization of the nanocarrier in LNCaP was mediated mainly by macropinocytosis and clathrin-independent pathways, while internalization in PC3 and DU145 involved clathrin-mediated endocytosis, clathrin-independent pathways, and macropinocytosis. Fluorescence microscopy showed a very diffused and non-compartmentalized subcellular localization of the PCL/MD nanocarriers with possible intranuclear localization and minor colocalization in the lysosomes with time.

Regulation of Kv7.2/Kv7.3 channels by cholesterol: Relevance of an optimum plasma membrane cholesterol content.

PubMed

Delgado-Ramírez, Mayra; Sánchez-Armass, Sergio; Meza, Ulises; Rodríguez-Menchaca, Aldo A

2018-05-01

Kv7.2/Kv7.3 channels are the molecular correlate of the M-current, which stabilizes the membrane potential and controls neuronal excitability. Previous studies have shown the relevance of plasma membrane lipids on both M-currents and Kv7.2/Kv7.3 channels. Here, we report the sensitive modulation of Kv7.2/Kv7.3 channels by membrane cholesterol level. Kv7.2/Kv7.3 channels transiently expressed in HEK-293 cells were significantly inhibited by decreasing the cholesterol level in the plasma membrane by three different pharmacological strategies: methyl-β-cyclodextrin (MβCD), Filipin III, and cholesterol oxidase treatment. Surprisingly, Kv7.2/Kv7.3 channels were also inhibited by membrane cholesterol loading with the MβCD/cholesterol complex. Depletion or enrichment of plasma membrane cholesterol differentially affected the biophysical parameters of the macroscopic Kv7.2/Kv7.3 currents. These results indicate a complex mechanism of Kv7.2/Kv7.3 channels modulation by membrane cholesterol. We propose that inhibition of Kv7.2/Kv7.3 channels by membrane cholesterol depletion involves a loss of a direct cholesterol-channel interaction. However, the inhibition of Kv7.2/Kv7.3 channels by membrane cholesterol enrichment could include an additional direct cholesterol-channel interaction, or changes in the physical properties of the plasma membrane. In summary, our results indicate that an optimum cholesterol level in the plasma membrane is required for the proper functioning of Kv7.2/Kv7.3 channels. Copyright © 2018 Elsevier B.V. All rights reserved.

Cinnamon improves glucose and lipids of people with type 2 diabetes.

PubMed

Khan, Alam; Safdar, Mahpara; Ali Khan, Mohammad Muzaffar; Khattak, Khan Nawaz; Anderson, Richard A

2003-12-01

The objective of this study was to determine whether cinnamon improves blood glucose, triglyceride, total cholesterol, HDL cholesterol, and LDL cholesterol levels in people with type 2 diabetes. A total of 60 people with type 2 diabetes, 30 men and 30 women aged 52.2 +/- 6.32 years, were divided randomly into six groups. Groups 1, 2, and 3 consumed 1, 3, or 6 g of cinnamon daily, respectively, and groups 4, 5, and 6 were given placebo capsules corresponding to the number of capsules consumed for the three levels of cinnamon. The cinnamon was consumed for 40 days followed by a 20-day washout period. After 40 days, all three levels of cinnamon reduced the mean fasting serum glucose (18-29%), triglyceride (23-30%), LDL cholesterol (7-27%), and total cholesterol (12-26%) levels; no significant changes were noted in the placebo groups. Changes in HDL cholesterol were not significant. The results of this study demonstrate that intake of 1, 3, or 6 g of cinnamon per day reduces serum glucose, triglyceride, LDL cholesterol, and total cholesterol in people with type 2 diabetes and suggest that the inclusion of cinnamon in the diet of people with type 2 diabetes will reduce risk factors associated with diabetes and cardiovascular diseases.

Effect of a modified guar gum preparation on glucose and lipid levels in diabetics and healthy volunteers.

PubMed

Smith, U; Holm, G

1982-10-01

Six healthy volunteers and 17 diabetics (6 insulin-dependent and 11 diet- and tablet-treated) were treated with a special processed, palatable guar gum (10 g b.i.d. immediately before meals) for periods of one or three weeks or, in some cases, up to 13 weeks. A standardized test meal was given to study the effect of the fiber on postprandial glucose levels. Ten g guar was stirred in water and taken immediately before the test meal. The postprandial blood glucose levels were similar in the healthy volunteers but significantly lower in the diabetics following treatment with guar for one and three weeks, respectively. Furthermore, the fasting blood glucose levels were significantly lower in the diabetics after three, but not one, weeks of treatment. The lower postprandial glucose levels were coupled with attenuated and delayed insulin levels in accordance with an effect of guar gum on the rate of carbohydrate absorption. The cholesterol levels were on average reduced with 14% in the diabetics following three weeks' treatment with guar. The higher the initial cholesterol level, the greater the reduction in cholesterol; 26% reduction was achieved in four patients with initial levels above 7 mM. The alpha-lipoprotein cholesterol levels were not significantly changed, thus an increase in the alpha-lipoprotein cholesterol/total serum cholesterol ratio was obtained. Neither plasma triglycerides nor body weights altered during treatment. The reported side-effects were as expected and were usually mild and transient (e.g. increased flatulence). The data show that guar gum also reduces postprandial glucose levels on a long-term basis and may improve the diabetic control. Additionally, treatment with this fiber leads to a concentration-dependent decrease in cholesterol levels.

Inhibition of cholesterol biosynthesis through RNF145-dependent ubiquitination of SCAP.

PubMed

Zhang, Li; Rajbhandari, Prashant; Priest, Christina; Sandhu, Jaspreet; Wu, Xiaohui; Temel, Ryan; Castrillo, Antonio; de Aguiar Vallim, Thomas Q; Sallam, Tamer; Tontonoz, Peter

2017-10-25

Cholesterol homeostasis is maintained through concerted action of the SREBPs and LXRs. Here, we report that RNF145, a previously uncharacterized ER membrane ubiquitin ligase, participates in crosstalk between these critical signaling pathways. RNF145 expression is induced in response to LXR activation and high-cholesterol diet feeding. Transduction of RNF145 into mouse liver inhibits the expression of genes involved in cholesterol biosynthesis and reduces plasma cholesterol levels. Conversely, acute suppression of RNF145 via shRNA-mediated knockdown, or chronic inactivation of RNF145 by genetic deletion, potentiates the expression of cholesterol biosynthetic genes and increases cholesterol levels both in liver and plasma. Mechanistic studies show that RNF145 triggers ubiquitination of SCAP on lysine residues within a cytoplasmic loop essential for COPII binding, potentially inhibiting its transport to Golgi and subsequent processing of SREBP-2. These findings define an additional mechanism linking hepatic sterol levels to the reciprocal actions of the SREBP-2 and LXR pathways.

Association of ADRB2 polymorphism with triglyceride levels in Tongans.

PubMed

Naka, Izumi; Ohashi, Jun; Kimura, Ryosuke; Inaoka, Tsukasa; Matsumura, Yasuhiro

2013-07-23

Our previous study demonstrated that the A-allele of the single nucleotide polymorphism (SNP) rs34623097 located in the upstream region of the β2 adrenergic receptor gene (ADRB2) is significantly associated with risk for obesity in Oceanic populations. To investigate whether the ADRB2 polymorphisms explain part of the individual differences in lipid mobilization, energy expenditure and glycogen breakdown, the associations of 10 ADRB2 SNPs with total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride levels were examined in 128 adults in Tonga. A multiple linear regression analysis adjusted for age, sex, and body mass index revealed that rs34623097 was significantly associated with triglyceride levels (P-value = 0.037). A copy of the rs34623097-A allele increased serum triglyceride levels by 70.1 mg/dL (0.791 mmol/L). None of the ADRB2 SNPs showed a significant association with total-cholesterol, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol. In a Tongan population, a SNP located in the upstream region of ADRB2 is associated with triglyceride levels independent of body mass index.

Royal Jelly Reduces Cholesterol Levels, Ameliorates Aβ Pathology and Enhances Neuronal Metabolic Activities in a Rabbit Model of Alzheimer’s Disease

PubMed Central

Pan, Yongming; Xu, Jianqin; Chen, Cheng; Chen, Fangming; Jin, Ping; Zhu, Keyan; Hu, Chenyue W.; You, Mengmeng; Chen, Minli; Hu, Fuliang

2018-01-01

Alzheimer’s disease (AD) is the most common form of dementia characterized by aggregation of amyloid β (Aβ) and neuronal loss. One of the risk factors for AD is high cholesterol levels, which are known to promote Aβ deposition. Previous studies have shown that royal jelly (RJ), a product of worker bees, has potential neuroprotective effects and can attenuate Aβ toxicity. However, little is known about how RJ regulates Aβ formation and its effects on cholesterol levels and neuronal metabolic activities. Here, we investigated whether RJ can reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in an AD rabbit model induced by 2% cholesterol diet plus copper drinking water. Our results suggest that RJ significantly reduced the levels of plasma total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C), and decreased the level of Aβ in rabbit brains. RJ was also shown to markedly ameliorate amyloid deposition in AD rabbits from Aβ immunohistochemistry and thioflavin-T staining. Furthermore, our study suggests that RJ can reduce the expression levels of β-site APP cleaving enzyme-1 (BACE1) and receptor for advanced glycation end products (RAGE), and increase the expression levels of low density lipoprotein receptor-related protein 1 (LRP-1) and insulin degrading enzyme (IDE). In addition, we found that RJ remarkably increased the number of neurons, enhanced antioxidant capacities, inhibited activated-capase-3 protein expression, and enhanced neuronal metabolic activities by increasing N-acetyl aspartate (NAA) and glutamate and by reducing choline and myo-inositol in AD rabbits. Taken together, our data demonstrated that RJ could reduce cholesterol levels, regulate Aβ levels and enhance neuronal metabolic activities in AD rabbits, providing preclinical evidence that RJ treatment has the potential to protect neurons and prevent AD. PMID:29556189

Treating elevated cholesterol levels: the great Satan in perspective.

PubMed

Gibaldi, M; Kradjan, W

1996-03-01

The purpose of this review is to provide perspective on the developments leading to the recognition of high cholesterol levels as a risk factor for coronary heart disease (CHD). Another objective is to consider the unfolding controversies regarding the relative value of cholesterol-lowering drug therapy in primary and secondary prevention. Should physicians use lipid-lowering drugs to treat patients with elevated cholesterol levels but no clinical evidence of coronary disease, or limit intervention to patients with a previous history of angina, coronary angioplasty, coronary artery bypass surgery, or myocardial infarction? This review finds inadequate data to support a recommendation for screening large populations for the presence of elevated cholesterol levels or for primary prevention in those known to have high cholesterol. On the other hand, there is mounting evidence to support vigorous intervention in those with known coronary disease. Further study is needed to determine whether a subset of patients with one or more well-defined risk factors would benefit from primary prevention.

You Sank My Lipid Rafts!

ERIC Educational Resources Information Center

Campbell, Tessa N.

2009-01-01

The plasma membrane is the membrane that serves as a boundary between the interior of a cell and its extracellular environment. Lipid rafts are microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids containing longer fatty acids. These domains are involved in many…

Blood Cholesterol Measurement in Clinical Laboratories in the United States. Current Status. A Report from the Laboratory Standardization Panel of the National Cholesterol Education Program.

ERIC Educational Resources Information Center

National Heart, Lung, and Blood Inst. (DHHS/NIH), Bethesda, MD.

Precise and accurate cholesterol measurements are required to identify and treat individuals with high blood cholesterol levels. However, the current state of reliability of blood cholesterol measurements suggests that considerable inaccuracy in cholesterol testing exists. This report describes the Laboratory Standardization Panel findings on the…

Influence of liver cancer on lipid and lipoprotein metabolism

PubMed Central

Jiang, Jingting; Nilsson-Ehle, Peter; Xu, Ning

2006-01-01

Liver plays a key role in the metabolism of plasma apolipoproteins, endogenous lipids and lipoproteins. Hepatocellular carcinoma (HCC) is one of the most common fatal malignant tumors in China and in other Southeast Asian countries. This has been attributed to the high incidence of hepatitis B infection. Hepatitis B proteins, such as the hepatitis B X protein (HBx) that is large hepatitis B surface protein could regulate transcription of many candidate genes for liver carcinogenesis. It has known that patients who suffered from acute hepatitis B could have lipid disorders such as decreased plasma level of high-density lipoproteins (HDL). Furthermore, aberrations of lipid metabolism are often seen in the chronic hepatitis B infection. Plasma lipid profiles could be changed under HCC. In majority of the reports in HCC, plasma levels of triglycerides (TG), cholesterol, free fatty acids (FFA), HDL, low-density lipoproteins (LDL), lipoprotein (a) (Lp(a)), apolipoprotein AI (apoAI) and apoB were slight to significantly decreased, however, in some cases plasma levels of TG and Lp(a) might be increased. It has been suggested that analysis of plasma levels of lipids, lipoproteins and apolipoproteins in the patients suffered from HCC reflects on the hepatic cellular impairment status. Studies revealed that alterations seen in the plasma levels of lipids, lipoproteins and apolipoproteins reflecting patients' pathologic conditions. Decreased serum levels of cholesterol and apoAI may indicate a poor prognosis. Human leukaemic cells and certain tumor tissues have a higher receptor-mediated uptake of HDL and LDL than the corresponding normal cells or tissues. LDL and HDL have therefore been proposed as a carrier for the water-insoluble anti-cancer agents. PMID:16515689

Prevalence of Low High-density Lipoprotein Cholesterol Among Adults, by Physical Activity: United States, 2011-2014.

PubMed

Zwald, Marissa L; Akinbami, Lara J; Fakhouri, Tala H I; Fryar, Chryl D

2017-03-01

Data from the National Health and Nutrition Examination Survey •The prevalence of low high-density lipoprotein (HDL) cholesterol was significantly higher among adults who did not meet recommended physical activity guidelines (21.0%) than adults who met the guidelines (17.7%). •Low HDL cholesterol prevalence differed significantly for both men and women by adherence to physical activity guidelines. •Prevalence of low HDL cholesterol declined as age increased for both those who did and did not meet the physical activity guidelines. •Non-Hispanic white and non-Hispanic black adults who did not meet the physical activity guidelines had a higher prevalence than those who met the guidelines. •Low HDL cholesterol prevalence declined with increasing education level regardless of adherence to physical activity guidelines. Regular physical activity can improve cholesterol levels among adults, including increasing high-density lipoprotein (HDL) cholesterol (1). HDL cholesterol is known as "good" cholesterol because high levels can reduce cardiovascular disease risk (2). The 2008 Physical Activity Guidelines for Americans recommend that adults engage in 150 minutes or more of moderate-intensity aerobic activity per week, 75 minutes of vigorous-intensity aerobic activity per week, or an equivalent combination (3). Adherence to these guidelines is expected to decrease the prevalence of low HDL cholesterol levels (4-8). This report presents national data for 2011-2014 on low HDL cholesterol prevalence among U.S. adults aged 20 and over, by whether they met these guidelines. All material appearing in this report is in the public domain and may be reproduced or copied without permission; citation as to source, however, is appreciated.

Analysis of lipid profile and atherogenic index in hyperlipidemic rat (Rattus norvegicus Berkenhout, 1769) that given the methanolic extract of Parijoto (Medinilla speciosa)

NASA Astrophysics Data System (ADS)

Sa'adah, Noor Nailis; Purwani, Kristanti Indah; Nurhayati, Awik Puji Dyah; Ashuri, Nova Maulidina

2017-06-01

Diet of high lipids cause hyperlipidemia, which marked by an increase of total cholesterols, triglycerides, LDL-C, and decreasing of HDL-C. Hyperlipidemia lead the occurrence of atherosclerosis, one of factors that trigger cardiovascular disease, as hypertention; coronary heart and stroke. Parijoto (M. speciosa) is endemic plants in Asia with a distribution center in Malaysia, Indonesia and Philippines. Parijoto contain phytochemical components such as flavonoids, saponins and kardenolin. Flavonoid potensial as an antioxidants and can improve the hyperlipidemia condition. This study was aimed to determine lipid profiles and atherogenic index of hyperlipidemic Wistar rats (R. norvegicus Berkenhout, 1769) which given the methanolic extract of Parijoto (M. speciosa). The research was done with pre and post test randomized control group design. Rats were given a mixture of duck yolk and reused cooking oil (1:1) orally as much as 1% of body weight (BW) for 30 days. After hyperlipidemia achieved, rats were divided into 5 group: normal rats, hyperlipidemic rats, hyperlipidemic rats were given the methanolic extract of Parijoto (M. speciosa) 500 mg/kg, 1000 mg/kg, and 1500 mg/kg BW. Blood samples were collected when rats in hyperlipidemia conditions and after treatment with the methanolic extract of Parijoto (M. speciosa) for 30 days. The data of total cholesterol, HDL-Cholesterol, LDL-Cholesterol level, and atherogenic index were analyzed using ANOVA followed by Tukey test at 5% significance level. The result showed that giving of methanolic extract of Parijoto (M. speciosa) in hyperlipidemic rats reduced the total cholesterol, LDL-Cholesterol levels, and increased of HDL-cholesterol levels significantly (p<0.01), so atherogenic index reduced significantly too (p<0.01). Total cholesterol and LDL-Cholesterol levels were positively correlated with the atherogenic index, whereas HDL-cholesterol levels were negatively correlated with the atherogenic index.

Angiotensin converting enzyme gene polymorphism is associated with severity of coronary artery disease in men with high total cholesterol levels.

PubMed

Borzyszkowska, Joanna; Stanislawska-Sachadyn, Anna; Wirtwein, Marcin; Sobiczewski, Wojciech; Ciecwierz, Dariusz; Targonski, Radoslaw; Gruchala, Marcin; Rynkiewicz, Andrzej; Limon, Janusz

2012-05-01

This study examines whether renin-angiotensin-aldosterone system gene polymorphisms: ACE (encoding for angiotensin converting enzyme) c.2306-117_404 I/D, AGTR1 (encoding for angiotensin II type-1 receptor) c.1080*86A>C and CYP11B2 (encoding for aldosterone synthase) c.-344C>T are associated with the extension of coronary atherosclerosis in a group of 647 patients who underwent elective coronary angiography. The extension of CAD was evaluated using the Gensini score. The polymorphisms were determined by PCR and RFLP assays. The associations between genotypes and the extent of coronary atherosclerosis were tested by the Kruskal-Wallis test, followed by pairwise comparisons using Wilcoxon test. The population has been divided into groups defined by: sex, smoking habit, past myocardial infarction, BMI (>, ≤ 25), age (>, ≤ 55), diabetes mellitus, level of total cholesterol (>, ≤ 200 mg/dl), LDL cholesterol (>, ≤ 130 mg/dl), HDL cholesterol (>, ≤ 40 mg/dl), triglycerides (>, ≤ 150 mg/dl). Significant associations between the ACE c.2306-117_404 I/D polymorphism and the Gensini score in men with high total cholesterol levels (P(Kruskal-Wallis) = 0.008; P(adjusted) = 0.009), high level of LDL cholesterol (P(Kruskal-Wallis) = 0.016; P(adjusted) = 0.028) and low level of HDL cholesterol (P(Kruskal-Wallis) = 0.04; P(adjusted) = 0.055) have been found. No association between the AGTR1 c.1080*86A>C and CYP11B2 c.-344C>T and the Gensini score has been found. These results suggest that men who carry ACE c.2306-117_404 DD genotype and have high total cholesterol, high LDL cholesterol and low HDL cholesterol levels may be predisposed to the development of more severe CAD.

Diosgenin inhibits atherosclerosis via suppressing the MiR-19b-induced downregulation of ATP-binding cassette transporter A1.

PubMed

Lv, Yun-cheng; Yang, Jing; Yao, Feng; Xie, Wei; Tang, Yan-yan; Ouyang, Xin-ping; He, Ping-ping; Tan, Yu-lin; Li, Liang; Zhang, Min; Liu, Dan; Cayabyab, Francisco S; Zheng, Xi-Long; Tang, Chao-ke

2015-05-01

Diosgenin (Dgn), a structural analogue of cholesterol, has been reported to have the hypolipidemic and antiatherogenic properties, but the underlying mechanisms are not fully understood. Given the key roles of macrophages in cholesterol metabolism and atherogenesis, it is critical to investigate macrophage cholesterol efflux and development of atherosclerotic lesion after Dgn treatment. This study was designed to evaluate the potential effects of Dgn on macrophage cholesterol metabolism and the development of aortic atherosclerosis, and to explore its underlying mechanisms. Dgn significantly up-regulated the expression of ATP-binding cassette transporter A1 (ABCA1) protein, but didn't affect liver X receptor α levels in foam cells derived from human THP-1 macrophages and mouse peritoneal macrophages (MPMs) as determined by western blotting. The miR-19b levels were markedly down-regulated in Dgn-treated THP-1 macrophages/MPM-derived foam cells. Cholesterol transport assays revealed that treatment with Dgn alone or together with miR-19b inhibitor notably enhanced ABCA1-dependent cholesterol efflux, resulting in the reduced levels of total cholesterol, free cholesterol and cholesterol ester as determined by high-performance liquid chromatography. The fecal 3H-sterol originating from cholesterol-laden MPMs was increased in apolipoprotein E knockout mice treated with Dgn or both Dgn and antagomiR-19b. Treatment with Dgn alone or together with antagomiR-19b elevated plasma high-density lipoprotein levels, but reduced plasma low-density lipoprotein levels. Accordingly, aortic lipid deposition and plaque area were reduced, and collagen content and ABCA1 expression were increased in mice treated with Dgn alone or together with antagomiR-19b. However, miR-19b overexpression abrogated the lipid-lowering and atheroprotective effects induced by Dgn. The present study demonstrates that Dgn enhances ABCA1-dependent cholesterol efflux and inhibits aortic atherosclerosis progression by suppressing macrophage miR-19b expression. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Intracellular cholesterol level regulates sensitivity of glioblastoma cells against temozolomide-induced cell death by modulation of caspase-8 activation via death receptor 5-accumulation and activation in the plasma membrane lipid raft.

PubMed

Yamamoto, Yutaro; Tomiyama, Arata; Sasaki, Nobuyoshi; Yamaguchi, Hideki; Shirakihara, Takuya; Nakashima, Katsuhiko; Kumagai, Kosuke; Takeuchi, Satoru; Toyooka, Terushige; Otani, Naoki; Wada, Kojiro; Narita, Yoshitaka; Ichimura, Koichi; Sakai, Ryuichi; Namba, Hiroki; Mori, Kentaro

2018-01-01

Development of resistance against temozolomide (TMZ) in glioblastoma (GBM) after continuous treatment with TMZ is one of the critical problems in clinical GBM therapy. Intracellular cholesterol regulates cancer cell biology, but whether intracellular cholesterol is involved in TMZ resistance of GBM cells remains unclear. The involvement of intracellular cholesterol in acquired resistance against TMZ in GBM cells was investigated. Intracellular cholesterol levels were measured in human U251 MG cells with acquired TMZ resistance (U251-R cells) and TMZ-sensitive control U251 MG cells (U251-Con cells), and found that the intracellular cholesterol level was significantly lower in U251-R cells than in U251-Con cells. In addition, treatment by intracellular cholesterol remover, methyl-beta cyclodextrin (MβCD), or intracellular cholesterol inducer, soluble cholesterol (Chol), regulated TMZ-induced U251-Con cell death in line with changes in intracellular cholesterol level. Involvement of death receptor 5 (DR5), a death receptor localized in the plasma membrane, was evaluated. TMZ without or with MβCD and/or Chol caused accumulation of DR5 into the plasma membrane lipid raft and formed a complex with caspase-8, an extrinsic caspase cascade inducer, reflected in the induction of cell death. In addition, treatment with caspase-8 inhibitor or knockdown of DR5 dramatically suppressed U251-Con cell death induced by combination treatment with TMZ, MβCD, and Chol. Combined treatment of Chol with TMZ reversed the TMZ resistance of U251-R cells and another GBM cell model with acquired TMZ resistance, whereas clinical antihypercholesterolemia agents at physiological concentrations suppressed TMZ-induced cell death of U251-Con cells. These findings suggest that intracellular cholesterol level affects TMZ treatment of GBM mediated via a DR5-caspase-8 mechanism. Copyright © 2017 Elsevier Inc. All rights reserved.

Integrative genomic analysis implicates limited peripheral adipose storage capacity in the pathogenesis of human insulin resistance.

PubMed

Lotta, Luca A; Gulati, Pawan; Day, Felix R; Payne, Felicity; Ongen, Halit; van de Bunt, Martijn; Gaulton, Kyle J; Eicher, John D; Sharp, Stephen J; Luan, Jian'an; De Lucia Rolfe, Emanuella; Stewart, Isobel D; Wheeler, Eleanor; Willems, Sara M; Adams, Claire; Yaghootkar, Hanieh; Forouhi, Nita G; Khaw, Kay-Tee; Johnson, Andrew D; Semple, Robert K; Frayling, Timothy; Perry, John R B; Dermitzakis, Emmanouil; McCarthy, Mark I; Barroso, Inês; Wareham, Nicholas J; Savage, David B; Langenberg, Claudia; O'Rahilly, Stephen; Scott, Robert A

2017-01-01

Insulin resistance is a key mediator of obesity-related cardiometabolic disease, yet the mechanisms underlying this link remain obscure. Using an integrative genomic approach, we identify 53 genomic regions associated with insulin resistance phenotypes (higher fasting insulin levels adjusted for BMI, lower HDL cholesterol levels and higher triglyceride levels) and provide evidence that their link with higher cardiometabolic risk is underpinned by an association with lower adipose mass in peripheral compartments. Using these 53 loci, we show a polygenic contribution to familial partial lipodystrophy type 1, a severe form of insulin resistance, and highlight shared molecular mechanisms in common/mild and rare/severe insulin resistance. Population-level genetic analyses combined with experiments in cellular models implicate CCDC92, DNAH10 and L3MBTL3 as previously unrecognized molecules influencing adipocyte differentiation. Our findings support the notion that limited storage capacity of peripheral adipose tissue is an important etiological component in insulin-resistant cardiometabolic disease and highlight genes and mechanisms underpinning this link.

Balancing Low-density Lipoprotein Cholesterol Reduction and Hepatotoxicity With Lomitapide Mesylate and Mipomersen in Patients With Homozygous Familial Hypercholesterolemia.

PubMed

Won, Jane I; Zhang, Jun; Tecson, Kristen M; McCullough, Peter A

2017-01-01

Homozygous familial hypercholesterolemia (HoFH) is an autosomal codominant disorder manifested by high concentrations of total cholesterol and low-density lipoprotein (LDL) cholesterol, and premature cardiovascular disease. Despite conventional lipid-lowering therapy, LDL cholesterol levels remain elevated in patients with HoFH; these patients are considered to be at high risk for cardiovascular events. In 2012-2013, two drugs with novel mechanisms of action were approved by the US Food and Drug Administration for the treatment of HoFH: lomitapide mesylate and mipomersen. Both of these treatments reduce total cholesterol, LDL cholesterol, non-high-density lipoprotein cholesterol, apolipoprotein B, lipoprotein a, and triglyceride levels. This review describes the clinical tradeoffs in efficacy and hepatotoxicity of these drugs in two cases of HoFH.

Alterations of Mg2+ After Hemorrhagic Shock.

PubMed

Lee, Mun-Young; Yang, Dong Kwon; Kim, Shang-Jin

2017-11-01

Hemorrhagic shock is generally characterized by hemodynamic instability with cellular hypoxia and diminishing cellular function, resulting from an imbalance between systemic oxygen delivery and consumption and redistribution of fluid and electrolytes. Magnesium (Mg) is the fourth most abundant cation overall and second most abundant intracellular cation in the body and an essential cofactor for the energy production and cellular metabolism. Data for blood total Mg (tMg; free-ionized, protein-bound, and anion-bound forms) and free Mg 2+ levels after a traumatic injury are inconsistent and only limited information is available on hemorrhagic effects on free Mg 2+ as the physiologically active form. The aim of this study was to determine changes in blood Mg 2+ and tMg after hemorrhage in rats identifying mechanism and origin of the changes in blood Mg 2+ . Hemorrhagic shock produced significant increases in blood Mg 2+ , plasma tMg, Na + , K + , Cl - , anion gap, partial pressures of oxygen, glucose, and blood urea nitrogen but significant decreases in RBC tMg, blood Ca 2+ , HCO 3 - , pH, partial pressures of carbon dioxide, hematocrit, hemoglobin, total cholesterol, and plasma/RBC ATP. During hemorrhagic shock, K + , anion gap, and BUN showed significant positive correlations with changes in blood Mg 2+ level, while Ca 2+ , pH, and T-CHO correlated to Mg 2+ in a negative manner. In conclusion, hemorrhagic shock induced an increase in both blood-free Mg 2+ and tMg, resulted from Mg 2+ efflux from metabolic damaged cell with acidosis and ATP depletion.

Regulation of lipid metabolism by obeticholic acid in hyperlipidemic hamsters[S

PubMed Central

Dong, Bin; Young, Mark; Liu, Xueqing; Singh, Amar Bahadur; Liu, Jingwen

2017-01-01

The farnesoid X receptor (FXR) plays critical roles in plasma cholesterol metabolism, in particular HDL-cholesterol (HDL-C) homeostasis. Obeticholic acid (OCA) is a FXR agonist being developed for treating various chronic liver diseases. Previous studies reported inconsistent effects of OCA on regulating plasma cholesterol levels in different animal models and in different patient populations. The mechanisms underlying its divergent effects have not yet been thoroughly investigated. The scavenger receptor class B type I (SR-BI) is a FXR-modulated gene and the major receptor for HDL-C. We investigated the effects of OCA on hepatic SR-BI expression and correlated such effects with plasma HDL-C levels and hepatic cholesterol efflux in hyperlipidemic hamsters. We demonstrated that OCA induced a time-dependent reduction in serum HDL-C levels after 14 days of treatment, which was accompanied by a significant reduction of liver cholesterol content and increases in fecal cholesterol in OCA-treated hamsters. Importantly, hepatic SR-BI mRNA and protein levels in hamsters were increased to 1.9- and 1.8-fold of control by OCA treatment. Further investigations in normolipidemic hamsters did not reveal OCA-induced changes in serum HDL-C levels or hepatic SR-BI expression. We conclude that OCA reduces plasma HDL-C levels and promotes transhepatic cholesterol efflux in hyperlipidemic hamsters via a mechanism involving upregulation of hepatic SR-BI. PMID:27940481

Regulation of lipid metabolism by obeticholic acid in hyperlipidemic hamsters.

PubMed

Dong, Bin; Young, Mark; Liu, Xueqing; Singh, Amar Bahadur; Liu, Jingwen

2017-02-01

The farnesoid X receptor (FXR) plays critical roles in plasma cholesterol metabolism, in particular HDL-cholesterol (HDL-C) homeostasis. Obeticholic acid (OCA) is a FXR agonist being developed for treating various chronic liver diseases. Previous studies reported inconsistent effects of OCA on regulating plasma cholesterol levels in different animal models and in different patient populations. The mechanisms underlying its divergent effects have not yet been thoroughly investigated. The scavenger receptor class B type I (SR-BI) is a FXR-modulated gene and the major receptor for HDL-C. We investigated the effects of OCA on hepatic SR-BI expression and correlated such effects with plasma HDL-C levels and hepatic cholesterol efflux in hyperlipidemic hamsters. We demonstrated that OCA induced a time-dependent reduction in serum HDL-C levels after 14 days of treatment, which was accompanied by a significant reduction of liver cholesterol content and increases in fecal cholesterol in OCA-treated hamsters. Importantly, hepatic SR-BI mRNA and protein levels in hamsters were increased to 1.9- and 1.8-fold of control by OCA treatment. Further investigations in normolipidemic hamsters did not reveal OCA-induced changes in serum HDL-C levels or hepatic SR-BI expression. We conclude that OCA reduces plasma HDL-C levels and promotes transhepatic cholesterol efflux in hyperlipidemic hamsters via a mechanism involving upregulation of hepatic SR-BI.

Work, sleep, and cholesterol levels of U.S. long-haul truck drivers

PubMed Central

LEMKE, Michael K.; APOSTOLOPOULOS, Yorghos; HEGE, Adam; WIDEMAN, Laurie; SÖNMEZ, Sevil

2016-01-01

Long-haul truck drivers in the United States experience elevated cardiovascular health risks, possibly due to hypercholesterolemia. The current study has two objectives: 1) to generate a cholesterol profile for U.S. long-haul truck drivers; and 2) to determine the influence of work organization characteristics and sleep quality and duration on cholesterol levels of long-haul truck drivers. Survey and biometric data were collected from 262 long-haul truck drivers. Descriptive analyses were performed for demographic, work organization, sleep, and cholesterol measures. Linear regression and ordinal logistic regression analyses were conducted to examine for possible predictive relationships between demographic, work organization, and sleep variables, and cholesterol outcomes. The majority (66.4%) of drivers had a low HDL (<40 mg/dL), and nearly 42% of drivers had a high-risk total cholesterol to HDL cholesterol ratio. Sleep quality was associated with HDL, LDL, and total cholesterol, and daily work hours were associated with LDL cholesterol. Workday sleep duration was associated with non-HDL cholesterol, and driving experience and sleep quality were associated with cholesterol ratio. Long-haul truck drivers have a high risk cholesterol profile, and sleep quality and work organization factors may induce these cholesterol outcomes. Targeted worksite health promotion programs are needed to curb these atherosclerotic risks. PMID:28049935

Pla2g12b and Hpn Are Genes Identified by Mouse ENU Mutagenesis That Affect HDL Cholesterol

PubMed Central

Aljakna, Aleksandra; Choi, Seungbum; Savage, Holly; Hageman Blair, Rachael; Gu, Tongjun; Svenson, Karen L.; Churchill, Gary A.; Hibbs, Matt; Korstanje, Ron

2012-01-01

Despite considerable progress understanding genes that affect the HDL particle, its function, and cholesterol content, genes identified to date explain only a small percentage of the genetic variation. We used N-ethyl-N-nitrosourea mutagenesis in mice to discover novel genes that affect HDL cholesterol levels. Two mutant lines (Hlb218 and Hlb320) with low HDL cholesterol levels were established. Causal mutations in these lines were mapped using linkage analysis: for line Hlb218 within a 12 Mbp region on Chr 10; and for line Hlb320 within a 21 Mbp region on Chr 7. High-throughput sequencing of Hlb218 liver RNA identified a mutation in Pla2g12b. The transition of G to A leads to a cysteine to tyrosine change and most likely causes a loss of a disulfide bridge. Microarray analysis of Hlb320 liver RNA showed a 7-fold downregulation of Hpn; sequencing identified a mutation in the 3′ splice site of exon 8. Northern blot confirmed lower mRNA expression level in Hlb320 and did not show a difference in splicing, suggesting that the mutation only affects the splicing rate. In addition to affecting HDL cholesterol, the mutated genes also lead to reduction in serum non-HDL cholesterol and triglyceride levels. Despite low HDL cholesterol levels, the mice from both mutant lines show similar atherosclerotic lesion sizes compared to control mice. These new mutant mouse models are valuable tools to further study the role of these genes, their affect on HDL cholesterol levels, and metabolism. PMID:22912808

Effect of increased magnesium intake on plasma cholesterol, triglyceride and oxidative stress in alloxan-diabetic rats.

PubMed

Olatunji, L A; Soladoye, A O

2007-06-01

Cardiovascular disorders are the primary causes of morbidity and mortality in patients with diabetes mellitus (DM). Agents that improve lipid profile and reduce oxidative stress have been shown to reduce the ensuing risk factors. In the present study, we investigated whether increased magnesium intake could improve hyperglycaemia, dyslipidaemia, and reduce oxidative stress in alloxan-induced diabetic rats. Male Wistar rats were divided into non-diabetic (ND), diabetic (DM) and diabetic fed on a high magnesium diet (DM-Mg) groups. Plasma concentrations of thiobarbituric acid reactive substances (TBARS) were used as markers of oxidative stress. Plasma levels of ascorbic acid, magnesium and calcium were also determined. Diabetes was induced by injecting alloxan (100 mg/kg B.W). The fasting blood glucose levels were significantly lower in the DM-Mg rats than in the DM rats. Plasma total cholesterol, triglyceride, TBARS levels were significantly higher while plasma HDL-cholesterol, HDL-cholesterol/total cholesterol ratio, ascorbic acid levels were significantly lowered in DM rats compared with the ND rats. Increased intake of magnesium significantly abrogated these alterations. There were no significant differences in the plasma levels of magnesium and calcium between the DM and ND groups. However, plasma levels of magnesium but not calcium were significantly elevated in DM-Mg rats when compared with other groups. In conclusion, these results suggest that diet rich in magnesium could exert cardioprotective effect through reduced plasma total cholesterol, triglyceride, oxidative stress and ameliorated HDL-cholesterol/total cholesterol ratio as well as increased plasma ascorbic acid and magnesium in diabetic rats.

Lupin protein isolate versus casein modifies cholesterol excretion and mRNA expression of intestinal sterol transporters in a pig model

PubMed Central

2014-01-01

Background Lupin proteins exert hypocholesterolemic effects in man and animals, although the underlying mechanism remains uncertain. Herein we investigated whether lupin proteins compared to casein modulate sterol excretion and mRNA expression of intestinal sterol transporters by use of pigs as an animal model with similar lipid metabolism as humans, and cellular cholesterol-uptake by Caco-2 cells. Methods Two groups of pigs were fed cholesterol-containing diets with either 230 g/kg of lupin protein isolate from L. angustifolius or 230 g/kg casein, for 4 weeks. Faeces were collected quantitatively over a 5 d period for analysis of neutral sterols and bile acids by gas chromatographically methods. The mRNA abundances of intestinal lipid transporters were analysed by real-time RT-PCR. Cholesterol-uptake studies were performed with Caco-2 cells that were incubated with lupin conglutin γ, phytate, ezetimibe or albumin in the presence of labelled [4-14C]-cholesterol. Results Pigs fed the lupin protein isolate revealed lower cholesterol concentrations in total plasma, LDL and HDL than pigs fed casein (P < 0.05). Analysis of faeces revealed a higher output of cholesterol in pigs that were fed lupin protein isolate compared to pigs that received casein (+57.1%; P < 0.05). Relative mRNA concentrations of intestinal sterol transporters involved in cholesterol absorption (Niemann-Pick C1-like 1, scavenger receptor class B, type 1) were lower in pigs fed lupin protein isolate than in those who received casein (P < 0.05). In vitro data showed that phytate was capable of reducing the uptake of labelled [4-14C]-cholesterol into the Caco-2 cells to the same extend as ezetimibe when compared to control (−20.5% vs. −21.1%; P < 0.05). Conclusions Data reveal that the cholesterol-lowering effect of lupin protein isolate is attributable to an increased faecal output of cholesterol and a reduced intestinal uptake of cholesterol. The findings indicate phytate as a possible biofunctional ingredient of lupin protein isolate. PMID:24490902

Localization of the Placental BCRP/ABCG2 Transporter to Lipid Rafts: Role for Cholesterol in Mediating Efflux Activity

PubMed Central

Szilagyi, John T.; Vetrano, Anna M.; Laskin, Jeffrey D.; Aleksunes, Lauren M.

2017-01-01

Introduction The breast cancer resistance protein (BCRP/ABCG2) is an efflux transporter in the placental barrier. By transporting chemicals from the fetal to the maternal circulation, BCRP limits fetal exposure to a range of drugs, toxicants, and endobiotics such as bile acids and hormones. The purpose of the present studies was to 1) determine whether BCRP localizes to highly-ordered, cholesterol-rich lipid raft microdomains in placenta microvillous membranes, and 2) determine the impact of cholesterol on BCRP-mediated placental transport in vitro. Methods BCRP expression was analyzed in lipid rafts isolated from placentas from healthy, term pregnancies and BeWo trophoblasts by density gradient ultracentrifugation. BeWo cells were also tested for their ability to efflux BCRP substrates after treatment with the cholesterol sequestrant methyl-β-cyclodextrin (MβCD, 5mM, 1 h) or the cholesterol synthesis inhibitor pravastatin (200μM, 48 h). Results and Discussion BCRP was found to co-localize with lipid raft proteins in detergent-resistant, lipid raft-containing fractions from placental microvillous membranes and BeWo cells. Treatment of BeWo cells with MβCD redistributed BCRP protein into higher density non-lipid raft fractions. Repletion of the cells with cholesterol restored BCRP localization to lipid raft-containing fractions. Treatment of BeWo cells with MβCD or pravastatin increased cellular retention of two BCRP substrates, the fluorescent dye Hoechst 33342 and the mycotoxin zearalenone. Repletion with cholesterol restored BCRP transporter activity. Taken together, these data demonstrate that cholesterol may play a critical role in the post-translational regulation of BCRP in placental lipid rafts. PMID:28623970

Effect of the combinations between pea proteins and soluble fibres on cholesterolaemia and cholesterol metabolism in rats.

PubMed

Parolini, Cinzia; Manzini, Stefano; Busnelli, Marco; Rigamonti, Elena; Marchesi, Marta; Diani, Erika; Sirtori, Cesare R; Chiesa, Giulia

2013-10-01

Many functional foods and dietary supplements have been reported to be beneficial for the management of dyslipidaemia, one of the major risk factors for CVD. Soluble fibres and legume proteins are known to be a safe and practical approach for cholesterol reduction. The present study aimed at investigating the hypocholesterolaemic effect of the combinations of these bioactive vegetable ingredients and their possible effects on the expression of genes regulating cholesterol homeostasis. A total of six groups of twelve rats each were fed, for 28 d, Nath's hypercholesterolaemic diets, differing in protein and fibre sources, being, respectively, casein and cellulose (control), pea proteins and cellulose (pea), casein and oat fibres (oat), casein and apple pectin (pectin), pea proteins and oat fibres (pea+oat) and pea proteins and apple pectin (pea+pectin). Administration of each vegetable-containing diet was associated with lower total cholesterol concentrations compared with the control. The combinations (pea+oat and pea+pectin) were more efficacious than fibres alone in modulating cholesterolaemia ( - 53 and - 54%, respectively, at 28 d; P< 0·005). In rats fed the diets containing oat fibres or apple pectin, alone or in combination with pea proteins, a lower hepatic cholesterol content (P< 0·005) and higher hepatic mRNA concentrations of CYP7A1 and NTCP were found when compared with the control rats (P< 0·05). In summary, the dietary combinations of pea proteins and oat fibres or apple pectin are extremely effective in lowering plasma cholesterol concentrations in rats and affect cellular cholesterol homeostasis by up-regulating genes involved in hepatic cholesterol turnover.

Changes in membrane biophysical properties induced by the Budesonide/Hydroxypropyl-β-cyclodextrin complex.

PubMed

Dos Santos, Andreia G; Bayiha, Jules César; Dufour, Gilles; Cataldo, Didier; Evrard, Brigitte; Silva, Liana C; Deleu, Magali; Mingeot-Leclercq, Marie-Paule

2017-10-01

Budesonide (BUD), a poorly soluble anti-inflammatory drug, is used to treat patients suffering from asthma and COPD (Chronic Obstructive Pulmonary Disease). Hydroxypropyl-β-cyclodextrin (HPβCD), a biocompatible cyclodextrin known to interact with cholesterol, is used as a drug-solubilizing agent in pharmaceutical formulations. Budesonide administered as an inclusion complex within HPβCD (BUD:HPβCD) required a quarter of the nominal dose of the suspension formulation and significantly reduced neutrophil-induced inflammation in a COPD mouse model exceeding the effect of each molecule administered individually. This suggests the role of lipid domains enriched in cholesterol for inflammatory signaling activation. In this context, we investigated the effect of BUD:HPβCD on the biophysical properties of membrane lipids. On cellular models (A549, lung epithelial cells), BUD:HPβCD extracted cholesterol similarly to HPβCD. On large unilamellar vesicles (LUVs), by using the fluorescent probes diphenylhexatriene (DPH) and calcein, we demonstrated an increase in membrane fluidity and permeability induced by BUD:HPβCD in vesicles containing cholesterol. On giant unilamellar vesicles (GUVs) and lipid monolayers, BUD:HPβCD induced the disruption of cholesterol-enriched raft-like liquid ordered domains as well as changes in lipid packing and lipid desorption from the cholesterol monolayers, respectively. Except for membrane fluidity, all these effects were enhanced when HPβCD was complexed with budesonide as compared with HPβCD. Since cholesterol-enriched domains have been linked to membrane signaling including pathways involved in inflammation processes, we hypothesized the effects of BUD:HPβCD could be partly mediated by changes in the biophysical properties of cholesterol-enriched domains. Copyright © 2017 Elsevier B.V. All rights reserved.

Antidiabetogenic Effects of Chromium Mitigate Hyperinsulinemia-Induced Cellular Insulin Resistance via Correction of Plasma Membrane Cholesterol Imbalance

PubMed Central

Horvath, Emily M.; Tackett, Lixuan; McCarthy, Alicia M.; Raman, Priya; Brozinick, Joseph T.; Elmendorf, Jeffrey S.

2008-01-01

Previously, we found that a loss of plasma membrane (PM) phosphatidylinositol 4,5-bisphosphate (PIP2)-regulated filamentous actin (F-actin) structure contributes to insulin-induced insulin resistance. Interestingly, we also demonstrated that chromium picolinate (CrPic), a dietary supplement thought to improve glycemic status in insulin-resistant individuals, augments insulin-regulated glucose transport in insulin-sensitive 3T3-L1 adipocytes by lowering PM cholesterol. Here, to gain mechanistic understanding of these separate observations, we tested the prediction that CrPic would protect against insulin-induced insulin resistance by improving PM features important in cytoskeletal structure and insulin sensitivity. We found that insulin-induced insulin-resistant adipocytes display elevated PM cholesterol with a reciprocal decrease in PM PIP2. This lipid imbalance and insulin resistance was corrected by the cholesterol-lowering action of CrPic. The PM lipid imbalance did not impair insulin signaling, nor did CrPic amplify insulin signal transduction. In contrast, PM analyses corroborated cholesterol and PIP2 interactions influencing cytoskeletal structure. Because extensive in vitro study documents an essential role for cytoskeletal capacity in insulin-regulated glucose transport, we next evaluated intact skeletal muscle from obese, insulin-resistant Zucker (fa/fa) rats. Because insulin resistance in these animals likely involves multiple mechanisms, findings that cholesterol-lowering restored F-actin cytoskeletal structure and insulin sensitivity to that witnessed in lean control muscle were striking. Also, experiments using methyl-β-cyclodextrin to shuttle cholesterol into or out of membranes respectively recapitulated the insulin-induced insulin-resistance and protective effects of CrPic on membrane/cytoskeletal interactions and insulin sensitivity. These data predict a PM cholesterol basis for hyperinsulinemia-associated insulin resistance and importantly highlight the reversible nature of this abnormality. PMID:18165437

Localization of the placental BCRP/ABCG2 transporter to lipid rafts: Role for cholesterol in mediating efflux activity.

PubMed

Szilagyi, John T; Vetrano, Anna M; Laskin, Jeffrey D; Aleksunes, Lauren M

2017-07-01

The breast cancer resistance protein (BCRP/ABCG2) is an efflux transporter in the placental barrier. By transporting chemicals from the fetal to the maternal circulation, BCRP limits fetal exposure to a range of drugs, toxicants, and endobiotics such as bile acids and hormones. The purpose of the present studies was to 1) determine whether BCRP localizes to highly-ordered, cholesterol-rich lipid raft microdomains in placenta microvillous membranes, and 2) determine the impact of cholesterol on BCRP-mediated placental transport in vitro. BCRP expression was analyzed in lipid rafts isolated from placentas from healthy, term pregnancies and BeWo trophoblasts by density gradient ultracentrifugation. BeWo cells were also tested for their ability to efflux BCRP substrates after treatment with the cholesterol sequestrant methyl-β-cyclodextrin (MβCD, 5 mM, 1 h) or the cholesterol synthesis inhibitor pravastatin (200 μM, 48 h). BCRP was found to co-localize with lipid raft proteins in detergent-resistant, lipid raft-containing fractions from placental microvillous membranes and BeWo cells. Treatment of BeWo cells with MβCD redistributed BCRP protein into higher density non-lipid raft fractions. Repletion of the cells with cholesterol restored BCRP localization to lipid raft-containing fractions. Treatment of BeWo cells with MβCD or pravastatin increased cellular retention of two BCRP substrates, the fluorescent dye Hoechst 33342 and the mycotoxin zearalenone. Repletion with cholesterol restored BCRP transporter activity. Taken together, these data demonstrate that cholesterol may play a critical role in the post-translational regulation of BCRP in placental lipid rafts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Modulation of ileal bile acid transporter (ASBT) activity by depletion of plasma membrane cholesterol: association with lipid rafts

PubMed Central

Annaba, Fadi; Sarwar, Zaheer; Kumar, Pradeep; Saksena, Seema; Turner, Jerrold R.; Dudeja, Pradeep K.; Gill, Ravinder K.; Alrefai, Waddah A.

2016-01-01

Apical sodium-dependent bile acid transporter (ASBT) represents a highly efficient conservation mechanism of bile acids via mediation of their active transport across the luminal membrane of terminal ileum. To gain insight into the cellular regulation of ASBT, we investigated the association of ASBT with cholesterol and sphingolipid-enriched specialized plasma membrane microdomains known as lipid rafts and examined the role of membrane cholesterol in maintaining ASBT function. Human embryonic kidney (HEK)-293 cells stably transfected with human ASBT, human ileal brush-border membrane vesicles, and human intestinal epithelial Caco-2 cells were utilized for these studies. Floatation experiments on Optiprep density gradients demonstrated the association of ASBT protein with lipid rafts. Disruption of lipid rafts by depletion of membrane cholesterol with methyl-β-cyclodextrin (MβCD) significantly reduced the association of ASBT with lipid rafts, which was paralleled by a decrease in ASBT activity in Caco-2 and HEK-293 cells treated with MβCD. The inhibition in ASBT activity by MβCD was blocked in the cells treated with MβCD-cholesterol complexes. Kinetic analysis revealed that MβCD treatment decreased the Vmax of the transporter, which was not associated with alteration in the plasma membrane expression of ASBT. Our study illustrates that cholesterol content of lipid rafts is essential for the optimal activity of ASBT and support the association of ASBT with lipid rafts. These findings suggest a novel mechanism by which ASBT activity may be rapidly modulated by alterations in cholesterol content of plasma membrane and thus have important implications in processes related to maintenance of bile acid and cholesterol homeostasis. PMID:18063707

The effect of cholesterol overload on mouse kidney and kidney-derived cells.

PubMed

Honzumi, Shoko; Takeuchi, Miho; Kurihara, Mizuki; Fujiyoshi, Masachika; Uchida, Masashi; Watanabe, Kenta; Suzuki, Takaaki; Ishii, Itsuko

2018-11-01

Dyslipidemia is one of the onset and risk factors of chronic kidney disease and renal function drop is seen in lipoprotein abnormal animal models. However, the detailed molecular mechanism of renal lipotoxicity has not been clarified. Therefore, the present study aimed to investigate the influence of cholesterol overload using mouse kidney tissue and kidney-derived cultured cells. C57BL/6 mice were fed normal diet (ND) or 1.25% cholesterol-containing high-cholesterol diet (HCD) for 11 weeks, and we used megalin as a proximal tubule marker for immunohistology. We added beta-very low density lipoprotein (βVLDL) to kidney-derived cells and examined the effect of cholesterol overload on megalin protein and mRNA expression level, cell proliferation and cholesterol content in cells. In the kidney of HCD mice, the gap between glomerulus and the surrounding Bowman's capsule decreased and the expression level of megalin decreased. After βVLDL treatment to the cells, the protein expression and mRNA expression level of megalin decreased and cell proliferation was restrained. We also observed an increase in cholesterol accumulation in the cell and free cholesterol/phospholipid ratios increased. These findings suggest that the increased cholesterol load on kidney contribute to the decrease of megalin and the overloaded cholesterol is taken into the renal tubule epithelial cells, causing suppression on cell proliferation, which may be the cause of kidney damage.

High blood cholesterol levels

MedlinePlus

Cholesterol - high; Lipid disorders; Hyperlipoproteinemia; Hyperlipidemia; Dyslipidemia; Hypercholesterolemia ... A cholesterol test is done to diagnose a lipid disorder. Different experts recommend different starting ages. Recommended ...

TSHB mRNA is linked to cholesterol metabolism in adipose tissue.

PubMed

Moreno-Navarrete, José María; Moreno, María; Ortega, Francisco; Xifra, Gemma; Hong, Shangyu; Asara, John M; Serrano, José C E; Jové, Mariona; Pissios, Pavlos; Blüher, Matthias; Ricart, Wifredo; Portero-Otin, Manuel; Fernández-Real, José Manuel

2017-10-01

Subclinical hypothyroidism is known to be associated with increased serum cholesterol. Since thyroid-stimulating hormone (TSH) exerts an inductor effect on cholesterol biosynthesis, we aimed to investigate the relationship between TSH mRNA and cholesterol metabolism in human adipose tissue (AT). Cross-sectionally, AT TSH-β ( TSHB ) mRNA was evaluated in 4 independent cohorts in association with serum total and LDL cholesterol, and AT lipidomics. Longitudinally, the effects of statins and of diet and exercise on AT TSHB mRNA were also examined. The bidirectional relationship between cholesterol and TSHB were studied in isolated human adipocytes. TSHB mRNA was consistently detected in AT from euthyroid subjects, and positively associated with serum total- and LDL-cholesterol, and with AT-specific cholesterol metabolism-associated lipids [arachidonoyl cholesteryl ester, C8-dihydroceramide, N -stearoyl-d-sphingosine, and GlcCer(18:0, 24:1)]. Reduction of cholesterol with statins and with diet and exercise interventions led to decreased TSHB mRNA in human AT, whereas excess cholesterol up-regulated TSHB mRNA in human adipocytes. In addition, recombinant human TSH α/β administration resulted in increased HMGCR mRNA levels in human adipocytes. In mice, subcutaneous AT Tshb expression levels correlated directly with circulating cholesterol levels. In summary, current results provide novel evidence of TSHB as a paracrine factor that is modulated in parallel with cholesterol metabolism in human AT.-Moreno-Navarrete, J. M., Moreno, M., Ortega, F., Xifra, G., Hong, S., Asara, J. M., Serrano, J. C. E., Jové, M., Pissios, P., Blüher, M., Ricart, W., Portero-Otin, M., Fernández-Real, J. M. TSHB mRNA is linked to cholesterol metabolism in adipose tissue. © FASEB.

National Survey on Internal Quality Control Practice for Lipid Parameters in Laboratories of China from 2014 to 2016.

PubMed

Ye, Yuanyuan; Wang, Wei; Zhao, Haijian; He, Falin; Zhong, Kun; Yuan, Shuai; Wang, Zhiguo

2017-09-01

To investigate the situation of Internal Quality Control (IQC) practice for total cholesterol, triglycerides, HDL-cholesterol and LDL-cholesterol from 2014 to 2016 in laboratories in China and provide improvement measurements. A web-based External Quality Assessment (EQA) system was used to collect IQC data of lipid parameters in laboratories which continuously participated in the national EQA programs in China from 2014 to 2016. Pass rate of the coefficients of variation (CVs) of two level quality controls in four lipid parameters were calculated according to six quality specifications for precision to evaluate the current status of precision level of the four lipid parameters and their change over time in China. 533, 512, 504, and 466 laboratories continuously reported the data of level one for total cholesterol, triglyceride, HDL-cholesterol and LDL-cholesterol, and 212, 210, 208 and 198 laboratories reported the level two, respectively. The percentage of laboratories meeting the quality specification varied based on different criteria. Non-significant change can be found in the pass rate of CVs over time. The number of laboratories using a closed system increased over time, but still only accounted for a small proportion. There is no significant difference in the pass rate of CVs between closed and open systems. Triglycerides currently have a fairly good performance in China. While the performance of laboratories on total cholesterol, HDL-cholesterol and LDL-cholesterol has yet to be improved.

Impact of a public cholesterol screening program.

PubMed

Fischer, P M; Guinan, K H; Burke, J J; Karp, W B; Richards, J W

1990-12-01

The National Cholesterol Education Program (NCEP) has endorsed physician case finding as the primary method to detect individuals with elevated cholesterol levels. Despite this recommendation, promotional and for-profit public screening programs have flourished. We surveyed participants of a mall-based cholesterol screening program 1 year after their screening. Sixty-four percent of those screened had not previously known their cholesterol levels. Those who were newly screened were less likely to benefit from this testing than the general public, since they were older (mean age, 55.3 years), more likely to be female (67.4%), and nonsmokers (88%). Screenees had excellent recall of their cholesterol level (mean absolute reporting error, 0.24 mmol/L [9 mg/dL]) and a good understanding of cholesterol as a coronary heart disease risk. Those with elevated cholesterol levels reported high distress from screening but no reduction in overall psychosocial well-being and an actual decrease in absenteeism. Only 53.7% of all who were advised to seek follow-up because of an elevated screening value had done so within the year following the screening program. However, of those with values greater than 6.2 mmol/L (240 mg/dL), 68% had sought follow-up. Many of those who participate in public screening programs have been previously tested, fall into low-benefit groups, or fail to comply with recommended follow-up. We therefore conclude that cholesterol screening programs of the type now commonly offered are unlikely to contribute greatly to the national efforts to further reduce coronary heart disease.

The effects of coffee consumption on serum lipids and lipoprotein in healthy individuals.

PubMed

Onuegbu, A J; Agbedana, E O

2001-01-01

The changes in total serum cholestrol, serum triglyceride, HDL-cholesterol and LDL-cholesterol after twenty eight (28) days of consumption of moderate quantity of a commercial coffee preparation (NESCAFE brand) were studied in 30 human subjects consisting of 20 male and 10 female healthy adults. Significant increases in the mean total serum cholesterol concentration (110.8-126.5 mg/100 mls) and LDL- cholesterol concentration (78.4-94.5 mg/100 ml) were observed in the subjects. No significant differences were obtained in the mean HDL cholesterol concentration and in the mean serum triglyceride levels. The differences observed in the mean total serum cholesterol, LDL cholesterol, HDL- cholesterol and triglyceride concentrations in the individual male and female groups studied were not statistically significant. The results from this study suggest that short-term consumption of coffee may increase the total serum cholesterol and LDL cholesterol levels. It is therefore possible that long-term consumption of coffee may lead to clinically significant alterations in serum lipid profile and could be important in the aetiology of atherosclerotic vascular diseases such as coronary heart disease.

Colorimetric detection of cholesterol based on enzyme modified gold nanoparticles

NASA Astrophysics Data System (ADS)

Nirala, Narsingh R.; Saxena, Preeti S.; Srivastava, Anchal

2018-02-01

We develop a simple colorimetric method for determination of free cholesterol in aqueous solution based on functionalized gold nanoparticles with cholesterol oxidase. Functionalized gold nanoparticles interact with free cholesterol to produce H2O2 in proportion to the level of cholesterol visually is being detected. The quenching in optical properties and agglomeration of functionalized gold nanoparticles play a key role in cholesterol sensing due to the electron accepting property of H2O2. While the lower ranges of cholesterol (lower detection limit i.e. 0.2 mg/dL) can be effectively detected using fluorescence study, the absorption study attests evident visual color change which becomes effective for detection of higher ranges of cholesterol (lower detection limit i.e. 19 mg/dL). The shades of red gradually change to blue/purple as the level of cholesterol detected (as evident at 100 mg/dL) using unaided eye without the use of expensive instruments. The potential of the proposed method to be applied in the field is shown by the proposed cholesterol measuring color wheel.

Contemporary trends in dyslipidemia in the Framingham Heart Study

USDA-ARS?s Scientific Manuscript database

Recent cross-sectional population studies in the United States have shown an increase in obesity, a decrease in cholesterol values, but no changes in levels of high-density lipoprotein cholesterol (HDL-C) or triglycerides (TG). Plasma total cholesterol, HDL-C, and TG levels, measured by the same met...

Effects of maximal doses of atorvastatin versus rosuvastatin on small dense low-density lipoprotein cholesterol levels

USDA-ARS?s Scientific Manuscript database

Maximal doses of atorvastatin and rosuvastatin are highly effective in lowering low-density lipoprotein (LDL) cholesterol and triglyceride levels; however, rosuvastatin has been shown to be significantly more effective than atorvastatin in lowering LDL cholesterol and in increasing high-density lipo...

δ-Tocopherol Reduces Lipid Accumulation in Niemann-Pick Type C1 and Wolman Cholesterol Storage Disorders*

PubMed Central

Xu, Miao; Liu, Ke; Swaroop, Manju; Porter, Forbes D.; Sidhu, Rohini; Finkes, Sally; Ory, Daniel S.; Marugan, Juan J.; Xiao, Jingbo; Southall, Noel; Pavan, William J.; Davidson, Cristin; Walkley, Steven U.; Remaley, Alan T.; Baxa, Ulrich; Sun, Wei; McKew, John C.; Austin, Christopher P.; Zheng, Wei

2012-01-01

Niemann-Pick disease type C (NPC) and Wolman disease are two members of a family of storage disorders caused by mutations of genes encoding lysosomal proteins. Deficiency in function of either the NPC1 or NPC2 protein in NPC disease or lysosomal acid lipase in Wolman disease results in defective cellular cholesterol trafficking. Lysosomal accumulation of cholesterol and enlarged lysosomes are shared phenotypic characteristics of both NPC and Wolman cells. Utilizing a phenotypic screen of an approved drug collection, we found that δ-tocopherol effectively reduced lysosomal cholesterol accumulation, decreased lysosomal volume, increased cholesterol efflux, and alleviated pathological phenotypes in both NPC1 and Wolman fibroblasts. Reduction of these abnormalities may be mediated by a δ-tocopherol-induced intracellular Ca2+ response and subsequent enhancement of lysosomal exocytosis. Consistent with a general mechanism for reduction of lysosomal lipid accumulation, we also found that δ-tocopherol reduces pathological phenotypes in patient fibroblasts from other lysosomal storage diseases, including NPC2, Batten (ceroid lipofuscinosis, neuronal 2, CLN2), Fabry, Farber, Niemann-Pick disease type A, Sanfilippo type B (mucopolysaccharidosis type IIIB, MPSIIIB), and Tay-Sachs. Our data suggest that regulated exocytosis may represent a potential therapeutic target for reduction of lysosomal storage in this class of diseases. PMID:23035117

Inhibition of Nipah virus infection in vivo: targeting an early stage of paramyxovirus fusion activation during viral entry.

PubMed

Porotto, Matteo; Rockx, Barry; Yokoyama, Christine C; Talekar, Aparna; Devito, Ilaria; Palermo, Laura M; Liu, Jie; Cortese, Riccardo; Lu, Min; Feldmann, Heinz; Pessi, Antonello; Moscona, Anne

2010-10-28

In the paramyxovirus cell entry process, receptor binding triggers conformational changes in the fusion protein (F) leading to viral and cellular membrane fusion. Peptides derived from C-terminal heptad repeat (HRC) regions in F have been shown to inhibit fusion by preventing formation of the fusogenic six-helix bundle. We recently showed that the addition of a cholesterol group to HRC peptides active against Nipah virus targets these peptides to the membrane where fusion occurs, dramatically increasing their antiviral effect. In this work, we report that unlike the untagged HRC peptides, which bind to the postulated extended intermediate state bridging the viral and cell membranes, the cholesterol tagged HRC-derived peptides interact with F before the fusion peptide inserts into the target cell membrane, thus capturing an earlier stage in the F-activation process. Furthermore, we show that cholesterol tagging renders these peptides active in vivo: the cholesterol-tagged peptides cross the blood brain barrier, and effectively prevent and treat in an established animal model what would otherwise be fatal Nipah virus encephalitis. The in vivo efficacy of cholesterol-tagged peptides, and in particular their ability to penetrate the CNS, suggests that they are promising candidates for the prevention or therapy of infection by Nipah and other lethal paramyxoviruses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfe, Adam R.; Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas; Atkinson, Rachel L.

Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL),more » or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients and IBC patient-derived cell lines. A more expansive study is needed to verify these observations.« less

Retinoic Acid Isomers Up-Regulate ATP Binding Cassette A1 and G1 and Cholesterol Efflux in Rat Astrocytes: Implications for Their Therapeutic and Teratogenic Effects

PubMed Central

Chen, Jing; Costa, Lucio G.

2011-01-01

Recent studies suggest that retinoids may be effective in the treatment of Alzheimer's disease, although exposure to an excess of retinoids during gestation causes teratogenesis. Cholesterol is essential for brain development, but high levels of cholesterol have been associated with Alzheimer's disease. We hypothesized that retinoic acid may affect cholesterol homeostasis in rat astrocytes, which regulate cholesterol distribution in the brain, through the up-regulation of cholesterol transporters ATP binding cassette (Abc)a1 and Abcg1. Tretinoin, 13-cis retinoic acid (13-cis-RA), 9-cis-RA, and the selective retinoid X receptor (RXR) agonist methoprene significantly increased cholesterol efflux induced by cholesterol acceptors and protein levels of Abca1 by 2.3- (±0.25), 3.6- (±0.42), 4.1- (±0.5), and 1.75- (±0.43) fold, respectively, and Abcg1 by 2.1- (±0.26), 2.2- (±0.33), 2.5- (±0.23), and 2.2- (±0.21) fold, respectively. 13-cis-RA and 9-cis-RA also significantly increased mRNA levels of Abca1 (maximal induction 7.3 ± 0.42 and 2.7 ± 0.17, respectively) and Abcg1 (maximal induction 2.0 ± 0.18 and 1.8 ± 0.09, respectively), and the levels of membrane-bound Abca1 (2.5 ± 0.3 and 2.5 ± 0.40-fold increase, respectively), whereas they significantly decreased intracellular cholesterol content without affecting cholesterol synthesis. The effect of 9-cis-RA on cholesterol homeostasis in astrocytes can be ascribed to the activation of RXR, whereas the effects of 13-cis-RA and tretinoin were independent of either RXRs or retinoic acid receptors. These findings suggest that retinoids affect cholesterol homeostasis in astrocytes and that this effect may be involved in both their therapeutic and teratogenic actions. PMID:21628419

Cholesterol lipoproteins and prevalence of dyslipidemias in urban Asian Indians: A cross sectional study

PubMed Central

Guptha, Soneil; Gupta, Rajeev; Deedwania, Prakash; Bhansali, Anil; Maheshwari, Anuj; Gupta, Arvind; Gupta, Balkishan; Saboo, Banshi; Singh, Jitendra; Achari, Vijay; Sharma, Krishna Kumar

2014-01-01

Objective To determine levels of cholesterol lipoproteins and prevalence of dyslipidemias in urban Asian Indians. Methods Population based 6123 subjects (men 3388) were evaluated. Mean±1SD of various cholesterol lipoproteins (total, HDL, LDL and non-HDL cholesterol) and triglycerides were reported. Subjects were classified according to US National Cholesterol Education Program. Results Age-adjusted levels in men and women were cholesterol total 178.4 ± 39 and 184.6 ± 39, HDL 44.9 ± 11 and 51.1 ± 11, LDL 102.5 ± 33 and 106.2 ± 33, total:HDL 4.15 ± 1.2 and 3.79 ± 1.0 and triglycerides 162.5 ± 83 and 143.7 ± 83 mg/dl. Age-adjusted prevalence (%) in men and women, respectively were, total cholesterol ≥200 mg/dl 25.1 and 24.9, LDL cholesterol ≥130 mg/dl 16.3 and 15.1 and ≥100 mg/dl 49.5 and 49.7, HDL cholesterol <40/<50 mg/dl 33.6 and 52.8, total:HDL cholesterol ≥4.5 29.4 and 16.8, and triglycerides ≥150 mg/dl 42.1 and 32.9%. Cholesterol level was significantly greater in subjects with better socioeconomic status, body mass index and waist circumference while triglycerides were more among those with high socioeconomic status, fat intake, body mass index and waist circumference (p < 0.05). Hypercholesterolemia awareness (15.6%), treatment (7.2%) and control (4.1%) were low. Conclusions Mean cholesterol and LDL cholesterol are low and triglycerides were high in urban Asian Indians. Most prevalent dyslipidemias are borderline high LDL, low HDL and high triglycerides. Subjects with high socioeconomic status, high fat intake and greater adiposity have higher total and LDL cholesterol and triglyceride and lower HDL cholesterol. PMID:24973832

Plasma lipid levels predict dysglycemia in a biracial cohort of nondiabetic subjects: Potential mechanisms

PubMed Central

Owei, Ibiye; Umekwe, Nkiru; Wan, Jim

2016-01-01

Dyslipidemia and dysglycemia are etiologically associated, but the direction, chronology, and mechanisms of the association are not fully understood. We, therefore, analyzed data from 335 healthy adults (184 black, 151 white) enrolled in the Pathobiology of Prediabetes in A Biracial Cohort study. Subjects underwent oral glucose tolerance test (OGTT) and were enrolled if they had normal fasting and 2-h plasma glucose levels. Assessments during year 1 included anthropometry, fasting lipid profile, insulin sensitivity, and insulin secretion. Thereafter, OGTT was assessed annually for 5.5 years. The primary outcome was occurrence of prediabetes (impaired fasting glucose or impaired glucose tolerance) or diabetes. During a mean follow-up of 2.62 years, 110 participants (32.8%) developed prediabetes (N = 100) or diabetes (N = 10). In multivariate logistic regression models, higher baseline low-density lipoprotein (LDL) cholesterol and triglyceride levels and lower HDL cholesterol levels significantly increased the risk of incident prediabetes. The combined relative risk (95% confidence interval [CI]) of prediabetes for participants with lower baseline HDL cholesterol (10th vs. 90th percentile), higher LDL cholesterol (90th vs. 10th percentile) and high triglycerides levels (90th vs. 10th percentile) was 4.12 (95% CI 1.61–10.56), P = 0.0032. At baseline, lipid values showed significant associations with measures of adiposity, glycemia, insulin sensitivity, and secretion. In both ethnic groups, waist circumference correlated positively with triglycerides and inversely with HDL cholesterol levels (P = 0.0004–<0.0001); fasting plasma glucose correlated positively with triglycerides and LDL cholesterol levels and inversely with HDL cholesterol levels (P = 0.006–<0.0001); insulin sensitivity correlated positively with HDL cholesterol and inversely with triglyceride levels (P < 0.0001), and insulin secretion correlated positively with triglycerides (P = 0.01) and inversely with HDL cholesterol (P < 0.0001). We conclude that a baseline lipidemic signature identifies normoglycemic individuals at high risk for future glycemic progression, via congruent associations with adiposity and glucoregulatory mechanisms. These findings suggest that early lifestyle intervention could ameliorate progressive dyslipidemia and dysglycemia. PMID:27430991

Mendelian randomization analysis in three Japanese populations supports a causal role of alcohol consumption in lowering low-density lipid cholesterol levels and particle numbers.

PubMed

Tabara, Yasuharu; Ueshima, Hirotsugu; Takashima, Naoyuki; Hisamatsu, Takashi; Fujiyoshi, Akira; Zaid, Maryam; Sumi, Masaki; Kohara, Katsuhiko; Miki, Tetsuro; Miura, Katsuyuki

2016-11-01

While alcohol consumption is known to increase plasma high-density lipoprotein (HDL) cholesterol levels, its relationship with low-density lipoprotein (LDL) cholesterol levels is unclear. Aldehyde dehydrogenase 2 (ALDH2) is a rate-controlling enzyme in alcohol metabolism, but a large number of Japanese people have the inactive allele. Here, we conducted a Mendelian randomization analysis using the ALDH2 genotype to clarify a causal role of alcohol on circulating cholesterol levels and lipoprotein particle numbers. This study was conducted in three independent general Japanese populations (men, n = 2289; women, n = 1940; mean age 63.3 ± 11.2 years). Alcohol consumption was assessed using a questionnaire. Lipoprotein particle numbers were determined by nuclear magnetic resonance spectroscopy. Alcohol consumption increased linearly in proportion to the number of subjects carrying the enzymatically active *1 allele in men (p < 0.001). The *1 allele was also positively associated with HDL cholesterol level (adjusted mean ± standard error, *1*1: 60 ± 0.5, *1*2: 56 ± 0.6, *2*2: 55 ± 1.3 mg/dl, p < 0.001) and inversely associated with LDL cholesterol level (116 ± 0.9, 124 ± 1.1, 130 ± 2.6 mg/dl, p < 0.001). The *1 allele was also positively associated with HDL particle numbers (per-allele: 2.60 ± 0.32 μmol/l, p < 0.001) and inversely associated with LDL particle numbers (-67.8 ± 19.6 nmol/l, p = 0.001). Additional Mendelian randomization analysis failed to clarify the involvement of cholesteryl ester transfer protein in alcohol-related changes in lipoprotein cholesterol levels. No significant association was observed in women, presumably due to their small amount of alcohol intake. Alcohol consumption has a causal role in not only increasing HDL cholesterol levels but also decreasing LDL cholesterol levels and particle numbers. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Modeling total cholesterol as predictor of mortality: the low-cholesterol paradox.

PubMed

Wesley, David; Cox, Hugh F

2011-01-01

Elevated total cholesterol is well-established as a risk factor for coronary artery disease and cardiovascular mortality. However, less attention is paid to the association between low cholesterol levels and mortality--the low cholesterol paradox. In this paper, restricted cubic splines (RCS) and complex survey methodology are used to show the low-cholesterol paradox is present in the laboratory, examination, and mortality follow-up data from the Third National Health and Nutrition Examination Survey (NHANES III). A series of Cox proportional hazard models, demonstrate that RCS are necessary to incorporate desired covariates while avoiding the use of categorical variables. Valid concerns regarding the accuracy of such predictive models are discussed. The one certain conclusion is that low cholesterol levels are markers for excess mortality, just as are high levels. Restricted cubic splines provide the necessary flexibility to demonstrate the U-shaped relationship between cholesterol and mortality without resorting to binning results. Cox PH models perform well at identifying associations between risk factors and outcomes of interest such as mortality. However, the predictions from such a model may not be as accurate as common statistics suggest and predictive models should be used with caution.

Effects of stress on serum triglycerides, nonsterified fatty acids, and total cholesterol levels in male rats after ethanol administration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershock, D.; Vogel, W.H.

1989-02-09

Serum triglycerides, nonesterified fatty acids (NEFA), and total cholesterol were determined during one hour immobilization stress in adult male Sprague-Dawley rats after ethanol administration (2g/kg, i.p.). Stress and ethanol effects were evaluated in two experiments: (1) rats maintained on Purina Rodent Chow for six weeks and fasted for 24 hours; and (2) rats maintained on the same diet supplemented with 1% cholesterol and 10% peanut oil for six weeks and nonfasted prior to experimentation. Blood was obtained from indwelling jugular catheters. In each experiment, differences were seen in triglyceride and NEFA levels but not in total cholesterol. In the regularmore » diet-fed rats (1), serum triglyceride levels were not affected by either stress or ethanol. However, NEFA levels did show differences in the response to ethanol and stress. A 63% decrease from baseline after 5{prime} of stress was partially abolished by ethanol; instead, a 24% increase was observed. Also, a stress-induced increase in NEFA which occurred after 15{prime} was not observed in the ethanol treated rats; rather, a decrease in NEFA was noted. Total cholesterol did not change in response to stress or ethanol. In the high cholesterol diet-fed rats (2), ethanol did not suppress a stress-induced increase in triglyceride levels. NEFA levels in ethanol-treated rats were higher during the first 15{prime} of stress as compared to stress alone. A decrease in NEFA was however seen in the ethanol-treated rats after 30{prime} of stress and these levels remained lower than the stress alone group. A diet-induced increase in total cholesterol levels was observed; however, no changes were seen due to either or ethanol. Thus, ethanol administration prior to acute immobilization stress did affect serum triglyceride and NEFA levels but did not change total cholesterol.« less

Serum lipid levels for a multicultural population in Auckland, New Zealand: results from the Diabetes Heart and Health Survey (DHAH) 2002-2003.

PubMed

Gentles, Dudley; Metcalf, Patricia; Dyall, Lorna; Scragg, Robert; Sundborn, Gerhard; Schaaf, David; Black, Peter N; Jackson, Rodney T

2007-11-09

To describe mean serum lipid concentrations for Maori, Pacific people (mostly of Samoan, Tongan, Niuean, or Cook Islands origin), and Others (mostly New Zealand-born Europeans), and to identify risk factors for an adverse lipid profile. A cross-sectional survey of adults aged between 35-74 years within the Auckland area. There were 1006 Maori, 996 Pacific people, and 2021 'Others' Fasting blood samples were collected from participants, and total cholesterol, high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides were measured. Maori and Pacific people had similar mean serum total and LDL cholesterol levels but lower HDL levels and higher total to HDL cholesterol ratios compared to Others (adjusted for age and gender). Maori also had higher triglycerides than Others. High BMI and cigarette smoking were positively associated with unfavourable lipid profiles, while current alcohol drinking and vigorous leisure time activity were associated with increased HDL cholesterol and lower total to HDL cholesterol ratios. Over 90% of all ethnic groups had total cholesterol levels above currently accepted optimal levels (>4 mmol/L) and two-thirds were above 5 mmol/L. While 30% of Others had a total to HDL cholesterol ratio above the 'optimal' threshold of 4.5, 40% of Maori and 44% of pacific people were above this level. This is the first study to simultaneously assess lipid levels in Maori, Pacific people, and Others in one population-based study. Despite similar total and LDL cholesterol levels in all ethnic groups; overweight, obesity, and current cigarette smoking were the main risk factors for their adverse lipid profiles. Engaging in leisure-time activity and alcohol consumption (and not surprisingly lipid-lowering drugs) were associated with better lipid profiles. We confirm that the main lipid-related cardiovascular disease risk in Maori and Pacific people is due to their low HDL and high triglyceride levels.

Elevated plasma low-density lipoprotein and high-density lipoprotein cholesterol levels in amenorrheic athletes: effects of endogenous hormone status and nutrient intake.

PubMed

Friday, K E; Drinkwater, B L; Bruemmer, B; Chesnut, C; Chait, A

1993-12-01

To determine the interactive effects of hormones, exercise, and diet on plasma lipids and lipoproteins, serum estrogen and progesterone levels, nutrient intake, and plasma lipid, lipoprotein, and apolipoprotein concentrations were measured in 24 hypoestrogenic amenorrheic and 44 eumenorrheic female athletes. When compared to eumenorrheic athletes, amenorrheic athletes had higher levels of plasma cholesterol (5.47 +/- 0.17 vs. 4.84 +/- 0.12 mmol/L, P = 0.003), triglyceride (0.75 +/- 0.06 vs. 0.61 +/- 0.03 mmol/L, P = 0.046), low-density lipoprotein (LDL; 3.16 +/- 0.15 vs. 2.81 +/- 0.09 mmol/L, P = 0.037), high-density lipoprotein (HDL; 1.95 +/- 0.07 vs. 1.73 +/- 0.05 mmol/L, P = 0.007), and HDL2 (0.84 +/- 0.06 vs. 0.68 +/- 0.04 mmol/L, P = 0.02) cholesterol. Plasma LDL/HDL cholesterol ratios, very low-density lipoprotein and HDL3 cholesterol, and apolipoprotein A-I and A-II levels were similar in the two groups. Amenorrheic athletes consumed less fat than eumenorrheic subjects (52 +/- 5 vs. 75 +/- 3 g/day, P = 0.02), but similar amounts of calories, cholesterol, protein, carbohydrate, and ethanol. HDL cholesterol levels in amenorrheic subjects correlated positively with the percent of dietary calories from fat (r = 0.42, n = 23, P = 0.045) but negatively with the percent from protein (r = -0.49, n = 23, P = 0.017). Thus, exercise-induced amenorrhea may adversely affect cardiovascular risk by increasing plasma LDL and total cholesterol. However, cardioprotective elevations in plasma HDL and HDL2 cholesterol may neutralize the risk of cardiovascular disease in amenorrheic athletes.

COMPOSITION OF CELLULAR MEMBRANES IN THE PANCREAS OF THE GUINEA PIG

PubMed Central

Meldolesi, J.; Jamieson, J. D.; Palade, G. E.

1971-01-01

The lipid composition of rough and smooth microsomal membranes, zymogen granule membranes, and a plasmalemmal fraction from the guinea pig pancreatic exocrine cell has been determined. As a group, membranes of the smooth variety (i.e., smooth microsomes, zymogen granule membranes, and the plasmalemma) were similar in their content of phospholipids, cholesterol and neutral lipids, and in the ratio of total lipids to membrane proteins. In contrast, rough microsomal membranes contained much less sphingomyelin and cholesterol and possessed a smaller lipid/protein ratio. All membrane fractions were unusually high in their content of lysolecithin (up to ∼20% of the total phospholipids) and of neutral lipids, especially fatty acids. The lysolecithin content was shown to be due to the hydrolysis of membrane lecithin by pancreatic lipase; the fatty acids, liberated by the action of lipase on endogenous triglyceride stores, are apparently scavenged by the membranes from the suspending media. Similar artifactually high levels of lysolecithin and fatty acids were noted in hepatic microsomes incubated with pancreatic postmicrosomal supernatant. E 600, an inhibitor of lipase, largely prevented the appearance of lysolecithin and fatty acids in pancreatic microsomes and in liver microsomes treated with pancreatic supernatant. PMID:5555573

Suicidal behaviour and lipid levels in unipolar and bipolar depression.

PubMed

Ainiyet, Babajohn; Rybakowski, Janusz K

2014-10-01

Evidence for a possible association between a low level of cholesterol and increased suicidal behaviour has accumulated in the recent 3 decades. The present study investigates whether lipid levels can make state-dependent markers of suicidal behaviour in Polish patients with mood disorder recently admitted to a psychiatric hospital owing to an acute depressive episode. The study was conducted on 223 patients (73 male and 150 female) with unipolar (n=171) and bipolar (n=52) depression. They were interviewed to assess any occurrence of suicidal thoughts, suicidal tendencies and/or suicidal attempts during the 3 months before admission. Laboratory measurements [total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides and total lipids] were obtained within 24-72 h after hospital admission. Suicidal thoughts, tendencies, and attempts were associated with low total cholesterol, LDL cholesterol, and total lipids in both male and female patients, in both diagnostic categories. Triglycerides were significantly lower in male and female patients with suicidal thoughts compared with their non-suicidal counterparts. No association with suicidality was found with HDL cholesterol. The results of our study support a majority of research showing the association in depressed patients between suicidal behaviour and low levels of total and LDL cholesterol. In addition, the data suggest a similar association with low total lipids, and in some instances, with low triglycerides.

Development of a new LDL-based transport system for hydrophobic/amphiphilic drug delivery to cancer cells.

PubMed

Huntosova, Veronika; Buzova, Diana; Petrovajova, Dana; Kasak, Peter; Nadova, Zuzana; Jancura, Daniel; Sureau, Franck; Miskovsky, Pavol

2012-10-15

Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic/amphiphilic photosensitizers to tumor cells in photodynamic therapy of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by dextran. Fluorescence spectroscopy, confocal fluorescence imaging, stopped-flow experiments and flow-cytometry were used to characterize redistribution of hypericin (Hyp), a natural occurring potent photosensitizer, loaded in LDL/dextran complex to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It is shown that the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. The modification of LDL molecules by dextran does not inhibit their recognition by cellular LDL receptors and U-87 MG cellular uptake of Hyp loaded in LDL/dextran complex appears to be similar to that one observed for Hyp transported by unmodified LDL particles. Thus, it is proposed that dextran modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic/amphiphilic drugs to cancer cells expressing high level of LDL receptors. Copyright © 2012 Elsevier B.V. All rights reserved.

Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family. Quantitative genetics and identification of a minor founder effect.

PubMed

Brink, P A; Brink, L T; Torrington, M; Bester, A J

1990-03-17

Overlap of clinical and biochemical characteristics between hypercholesterolaemia in members of the general population and familial hypercholesterolaemic (FH) individuals may lead to misdiagnosis. Quantitative analysis of family data may circumvent this problem. A way of looking for an association between plasma cholesterol levels and restriction fragment length polymorphism markers (RFLP) on the low-density lipoprotein (LDL) receptor gene by using reference cholesterol distributions was explored. Linkage, with a logarithm of the odds (LOD) score of 6.8 at theta 0, was detected between cholesterol levels and the LDL receptor in an extended Afrikaner family. Two RFLP-haplotypes, one previously found in a majority of Afrikaner FH homozygotes, and a second, Stu I-, BstE II+, Pvu II+, Nco I+, were associated with high cholesterol levels in this pedigree.

Gene networks and toxicity pathways induced by acute cadmium exposure in adult largemouth bass (Micropterus salmoides).

PubMed

Mehinto, Alvine C; Prucha, Melinda S; Colli-Dula, Reyna C; Kroll, Kevin J; Lavelle, Candice M; Barber, David S; Vulpe, Christopher D; Denslow, Nancy D

2014-07-01

Cadmium is a heavy metal that can accumulate to toxic levels in the environment leading to detrimental effects in animals and humans including kidney, liver and lung injuries. Using a transcriptomics approach, genes and cellular pathways affected by a low dose of cadmium were investigated. Adult largemouth bass were intraperitoneally injected with 20μg/kg of cadmium chloride (mean exposure level - 2.6μg of cadmium per fish) and microarray analyses were conducted in the liver and testis 48h after injection. Transcriptomic profiles identified in response to cadmium exposure were tissue-specific with the most differential expression changes found in the liver tissues, which also contained much higher levels of cadmium than the testis. Acute exposure to a low dose of cadmium induced oxidative stress response and oxidative damage pathways in the liver. The mRNA levels of antioxidants such as catalase increased and numerous transcripts related to DNA damage and DNA repair were significantly altered. Hepatic mRNA levels of metallothionein, a molecular marker of metal exposure, did not increase significantly after 48h exposure. Carbohydrate metabolic pathways were also disrupted with hepatic transcripts such as UDP-glucose, pyrophosphorylase 2, and sorbitol dehydrogenase highly induced. Both tissues exhibited a disruption of steroid signaling pathways. In the testis, estrogen receptor beta and transcripts linked to cholesterol metabolism were suppressed. On the contrary, genes involved in cholesterol metabolism were highly increased in the liver including genes encoding for the rate limiting steroidogenic acute regulatory protein and the catalytic enzyme 7-dehydrocholesterol reductase. Integration of the transcriptomic data using functional enrichment analyses revealed a number of enriched gene networks associated with previously reported adverse outcomes of cadmium exposure such as liver toxicity and impaired reproduction. Copyright © 2014 Elsevier B.V. All rights reserved.

Association of ADRB2 polymorphism with triglyceride levels in Tongans

PubMed Central

2013-01-01

Background Our previous study demonstrated that the A-allele of the single nucleotide polymorphism (SNP) rs34623097 located in the upstream region of the β2 adrenergic receptor gene (ADRB2) is significantly associated with risk for obesity in Oceanic populations. Methods To investigate whether the ADRB2 polymorphisms explain part of the individual differences in lipid mobilization, energy expenditure and glycogen breakdown, the associations of 10 ADRB2 SNPs with total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride levels were examined in 128 adults in Tonga. Results A multiple linear regression analysis adjusted for age, sex, and body mass index revealed that rs34623097 was significantly associated with triglyceride levels (P-value = 0.037). A copy of the rs34623097-A allele increased serum triglyceride levels by 70.1 mg/dL (0.791 mmol/L). None of the ADRB2 SNPs showed a significant association with total-cholesterol, high-density lipoprotein cholesterol, or low-density lipoprotein cholesterol. Conclusions In a Tongan population, a SNP located in the upstream region of ADRB2 is associated with triglyceride levels independent of body mass index. PMID:23875540

Effect of cholesterol and triglycerides levels on the rheological behavior of human blood

NASA Astrophysics Data System (ADS)

Moreno, Leonardo; Calderas, Fausto; Sanchez-Olivares, Guadalupe; Medina-Torres, Luis; Sanchez-Solis, Antonio; Manero, Octavio

2015-02-01

Important public health problems worldwide such as obesity, diabetes, hyperlipidemia and coronary diseases are quite common. These problems arise from numerous factors, such as hyper-caloric diets, sedentary habits and other epigenetic factors. With respect to Mexico, the population reference values of total cholesterol in plasma are around 200 mg/dL. However, a large proportion has higher levels than this reference value. In this work, we analyze the rheological properties of human blood obtained from 20 donors, as a function of cholesterol and triglyceride levels, upon a protocol previously approved by the health authorities. Samples with high and low cholesterol and triglyceride levels were selected and analyzed by simple-continuous and linear-oscillatory shear flow. Rheometric properties were measured and related to the structure and composition of human blood. In addition, rheometric data were modeled by using several constitutive equations: Bautista-Manero-Puig (BMP) and the multimodal Maxwell equations to predict the flow behavior of human blood. Finally, a comparison was made among various models, namely, the BMP, Carreau and Quemada equations for simple shear rate flow. An important relationship was found between cholesterol, triglycerides and the structure of human blood. Results show that blood with high cholesterol levels (400 mg/dL) has flow properties fully different (higher viscosity and a more pseudo-plastic behavior) than blood with lower levels of cholesterol (tendency to Newtonian behavior or viscosity plateau at low shear rates).

Association between dietary habits, education, serum triglycerides and blood cholesterol among women of Cabildo, Buenos Aires.

PubMed

Schneider, Raul J; Barengo, Noel; Haapala, Irja; Tavella, Marcelo

2006-01-01

A cross sectional study of 107 women between 20 and 69 years old, living in the town of Cabildo, province of Buenos Aires, Argentina, which describes food intake and analyses its relation to their education, blood cholesterol and serum triglyceride levels. A food frequency questionnaire including questions regarding meal patterns and food use were completed by the participants. Questions regarding educational status were included. A nutritional risk score was created from nine food groups. Total blood cholesterol and serum triglyceride levels were determined. Average total blood cholesterol levels of the women who participated in the present study were higher (209 mg/dl) than those recommended by the National Cholesterol Education Program, while triglyceride values remained within the normal range (124 mg/dl). Total blood cholesterol levels increased with age. Bread, biscuits and cakes were consumed on a daily basis by 98% of the participants and dairy products by 92%, these being mainly full-fat. Meat and fast food intake were very high (96% and 100% respectively). Vegetable and fish intakes were higher among the more educated women. Mayonnaise (58%) and butter (43%) are popular as food dressings and bread spreads respectively, and sunflower oil was the most commonly used for cooking by 94% of the participants. Women with low educational levels (less than 7 years) had higher nutritional risk scores, and thus unhealthier dietary habits than those with more years of formal education. No statistically significant association was found between food groups and cholesterol or triglyceride levels.

TSH-controlled L-thyroxine therapy reduces cholesterol levels and clinical symptoms in subclinical hypothyroidism: a double blind, placebo-controlled trial (Basel Thyroid Study).

PubMed

Meier, C; Staub, J J; Roth, C B; Guglielmetti, M; Kunz, M; Miserez, A R; Drewe, J; Huber, P; Herzog, R; Müller, B

2001-10-01

This study evaluated the effect of physiological, TSH-guided, L-thyroxine treatment on serum lipids and clinical symptoms in patients with subclinical hypothyroidism. Sixty-six women with proven subclinical hypothyroidism (TSH, 11.7 +/- 0.8 mIU/liter) were randomly assigned to receive L-thyroxine or placebo for 48 wk. Individual L-thyroxine replacement (mean dose, 85.5 +/- 4.3 microg/d) was performed based on blinded TSH monitoring, resulting in euthyroid TSH levels (3.1 +/- 0.3 mIU/liter). Lipid concentrations and clinical scores were measured before and after treatment. Sixty-three of 66 patients completed the study. In the L-thyroxine group (n = 31) total cholesterol and low density lipoprotein cholesterol were significantly reduced [-0.24 mmol/liter, 3.8% (P = 0.015) and -0.33 mmol/liter, 8.2% (P = 0.004), respectively]. Low density lipoprotein cholesterol decrease was more pronounced in patients with TSH levels greater than 12 mIU/liter or elevated low density lipoprotein cholesterol levels at baseline. A significant decrease in apolipoprotein B-100 concentrations was observed (P = 0.037), whereas high density lipoprotein cholesterol, triglycerides, apolipoprotein AI, and lipoprotein(a) levels remained unchanged. Two clinical scores assessing symptoms and signs of hypothyroidism (Billewicz and Zulewski scores) improved significantly (P = 0.02). This is the first double blind study to show that physiological L-thyroxine replacement in patients with subclinical hypothyroidism has a beneficial effect on low density lipoprotein cholesterol levels and clinical symptoms of hypothyroidism. An important risk reduction of cardiovascular mortality of 9-31% can be estimated from the observed improvement in low density lipoprotein cholesterol.

Animal source food intake and association with blood cholesterol, glycerophospholipids and sphingolipids in a northern Swedish population.

PubMed

Igl, Wilmar; Kamal-Eldin, Afaf; Johansson, Asa; Liebisch, Gerhard; Gnewuch, Carsten; Schmitz, Gerd; Gyllensten, Ulf

2013-01-01

The high intake of game meat in populations with a subsistence-based diet may affect their blood lipids and health status. To examine the association between diet and circulating levels of blood lipid levels in a northern Swedish population. We compared a group with traditional lifestyle (TLS) based on reindeer herding (TLS group) with those from the same area with a non-traditional lifestyle (NTLS) typical of more industrialized regions of Sweden (NTLS group). The analysis was based on self-reported intake of animal source food (i.e. non-game meat, game meat, fish, dairy products and eggs) and the serum blood level of a number of lipids [total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), triglycerides (TG), glycerophospholipids and sphingolipids]. The TLS group had higher cholesterol, LDL and HDL levels than the reference group. Of the TLS group, 65% had cholesterol levels above the threshold for increased risk of coronary heart disease (≥ 240 mg/dl), as compared to 38% of the NTLS group. Self-reported consumption of game meat was positively associated with TC and LDL. The high game meat consumption of the TLS group is associated with increased cholesterol levels. High intake of animal protein and fat and low fibre is known to increase the risk of cardiovascular disease, but other studies of the TLS in northern Sweden have shown comparable incidences of cardiovascular disease to the reference (NTLS) group from the same geographical area. This indicates that factors other than TC influence disease risk. One such possible factor is dietary phospholipids, which are also found in high amounts specifically in game meat and have been shown to inhibit cholesterol absorption.

Effects of atorvastatin on biomarkers of immune activation, inflammation, and lipids in virologically suppressed, human immunodeficiency virus-1-infected individuals with low-density lipoprotein cholesterol <130 mg/dL (AIDS Clinical Trials Group Study A5275).

PubMed

Nixon, Daniel E; Bosch, Ronald J; Chan, Ellen S; Funderburg, Nicholas T; Hodder, Sally; Lake, Jordan E; Lederman, Michael M; Klingman, Karin L; Aberg, Judith A

Persistent immune activation and inflammation in virologically suppressed human immunodeficiency virus (HIV) infection are linked to excess cardiovascular risk. To evaluate atorvastatin as a strategy to reduce cardiovascular risk. A5275 was a multicenter, prospective, randomized, double-blind, placebo-controlled, cross-over pilot study of atorvastatin (10 mg/day for 4 weeks then 20 mg/day for 16 weeks) with a planned enrollment of 97 HIV-infected participants ≥18 years old, receiving boosted protease inhibitor-based antiretroviral therapy for ≥6 months, with plasma HIV-1 RNAs below limits of quantification ≥180 days, and fasting low-density lipoprotein (LDL) cholesterol ≥70 and <130 mg/dL. Primary endpoints were differences of changes ([week 44-week 24]-[week 20-baseline]) in CD4+ and CD8+ T-lymphocyte activation (% CD38 + /DR + ) and plasma levels of IL-6 and D-dimer. Arms were compared using the Wilcoxon rank-sum tests and also summarized changes pre-to-post atorvastatin treatment. Analyses were as-treated. Ninety-eight participants were enrolled at 31 U S sites and 73 completed study treatment. Atorvastatin treatment did not decrease T-lymphocyte or monocyte activation, circulating biomarker levels (interleukin-6, D-dimer, soluble CD14, soluble CD163, monocyte chemoattractant protein-1, interferon-gamma-induced protein-10, high-sensitivity C-reactive protein, CD40L, and P-selectin) or white blood cell Krüppel-like Factor 2/4 messenger RNA levels. Pre-to-post atorvastatin reductions in calculated LDL (-38%), oxidized-LDL (-33%), and lipoprotein-associated phospholipase A2 (-31%) were significant (P < .01). In virologically suppressed individuals with HIV infection, atorvastatin did not significantly decrease levels of soluble or cellular biomarkers of immune activation and inflammation but resulted in robust reductions in LDL cholesterol, oxLDL, and lipoprotein-associated phospholipase A 2 , biomarkers associated with cardiovascular risk. Copyright © 2016 National Lipid Association. All rights reserved.

Association of salivary triglycerides and cholesterol with dental caries in children with type 1 diabetes mellitus.

PubMed

Subramaniam, Priya; Sharma, Akhliesh; Kaje, Keerthan

2015-01-01

Metabolic disturbances in diabetes mellitus can affect oral health. Altered levels of salivary lipids have been suggested as a risk for dental caries. There has been lack of research in this regard and in children with type 1 diabetes mellitus. To assess the salivary triglycerides and cholesterol levels in children with type 1 diabetes mellitus and correlate them with their dental caries status. Thirty children aged 12-16 years with type 1 diabetes mellitus and 30 age- and gender-matched healthy children were included in the study. Unstimulated saliva was collected from each child and evaluated for salivary triglyceride and cholesterol levels. Dental caries status (DMFT) was recorded. Salivary cholesterol and triglyceride levels were significantly higher in children with type 1 diabetes mellitus (p ≤ 0.05). In comparison to controls, mean DMFT score was higher in the diabetic children. Salivary triglycerides showed a significant correlation with dental caries status in the study group (p = 0.035). In normal children, salivary cholesterol levels showed a significant association with dental caries. (p = 0.008). Both salivary cholesterol and triglycerides levels were significantly higher in children with type 1 diabetes mellitus. Salivary triglycerides showed a significant association with dental caries in these children. © 2014 Special Care Dentistry Association and Wiley Periodicals, Inc.

Dynamics of hepatic and intestinal cholesterol and bile acid pathways: The impact of the animal model of estrogen deficiency and exercise training

PubMed Central

Lavoie, Jean-Marc

2016-01-01

Plasma cholesterol level is determined by a complex dynamics that involves transport lipoproteins which levels are tightly dependent on how the liver and the intestine regulate cholesterol and biliary acid metabolism. Regulation of cholesterol and biliary acids by the liver and the intestine is in turn coupled to a large array of enzymes and transporters that largely influence the inflow and the outflow of cholesterol and biliary acids through these organs. The activity of the key regulators of cholesterol and biliary acids may be influenced by several external factors such as pharmacological drugs and the nutritional status. In recent years, more information has been gathered about the impact of estrogens on regulation of cholesterol in the body. Exposure to high levels of estrogens has been reported to promote cholesterol gallstone formation and women are twice as likely as men to develop cholesterol gallstones. The impact of estrogen withdrawal, such as experienced by menopausal women, is therefore of importance and more information on how the absence of estrogens influence cholesterol regulation is started to come out, especially through the use of animal models. An interesting alternative to metabolic deterioration due to estrogen deficiency is exercise training. The present review is intended to summarize the present information that links key regulators of cholesterol and biliary acid pathways in liver and intestine to the absence of estrogens in an animal model and to discuss the potential role of exercise training as an alternative. PMID:27621762

Prevalence of dyslipidemia according to the nutritional status in a representative sample of São Paulo.

PubMed

Garcez, Marcela Riccioppo; Pereira, Jaqueline Lopes; Fontanelli, Mariane de Mello; Marchioni, Dirce Maria Lobo; Fisberg, Regina Mara

2014-12-01

Overweight is one of the major public health problems in Brazil; it is associated with dyslipidemia, which is an important risk factor for cardiovascular diseases. To evaluate the lipid profile of residents of the municipality of São Paulo, state of São Paulo, according to the nutritional status. Data from the population-based cross-sectional study ISA-Capital 2008 on a sample of residents of São Paulo were used. Participants were categorized into groups according to body mass index and age range. The levels of total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and non-HDL cholesterol were measured. The association between lipid profile, nutricional status, and waist circumference was investigated. The data were processed using the survey mode of the Stata 11.0 software. The prevalence of any type of dyslipidemia in the population was 59.74%, with low HDL-cholesterol dyslipidemia being the most common type. Not overweight individuals had higher mean levels of HDL-cholesterol and lower levels of LDL-cholesterol, total cholesterol, triglycerides, and non-HDL cholesterol when compared with the overweight group. The rate of inadequacy of these variables was higher in the overweight individuals, regardless of the age group, to the exception of LDL-cholesterol in the adults and elderly. A higher prevalence of isolated hypertriglyceridemia was observed in individuals with higher waist circumference among the adults and the total population. The results indicate an association between dyslipidemia and overweight in the population of the city of São Paulo. The most prevalent dyslipidemia in this population was low HDL-cholesterol.

Preferential invasion of mitotic cells by Salmonella reveals that cell surface cholesterol is maximal during metaphase.

PubMed

Santos, António J M; Meinecke, Michael; Fessler, Michael B; Holden, David W; Boucrot, Emmanuel

2013-07-15

Cell surface-exposed cholesterol is crucial for cell attachment and invasion of many viruses and bacteria, including the bacterium Salmonella, which causes typhoid fever and gastroenteritis. Using flow cytometry and 3D confocal fluorescence microscopy, we found that mitotic cells, although representing only 1-4% of an exponentially growing population, were much more efficiently targeted for invasion by Salmonella. This targeting was not dependent on the spherical shape of mitotic cells, but was instead SipB and cholesterol dependent. Thus, we measured the levels of plasma membrane and cell surface cholesterol throughout the cell cycle using, respectively, brief staining with filipin and a fluorescent ester of polyethylene glycol-cholesterol that cannot flip through the plasma membrane, and found that both were maximal during mitosis. This increase was due not only to the rise in global cell cholesterol levels along the cell cycle but also to a transient loss in cholesterol asymmetry at the plasma membrane during mitosis. We measured that cholesterol, but not phosphatidylserine, changed from a ∼2080 outerinner leaflet repartition during interphase to ∼5050 during metaphase, suggesting this was specific to cholesterol and not due to a broad change of lipid asymmetry during metaphase. This explains the increase in outer surface levels that make dividing cells more susceptible to Salmonella invasion and perhaps to other viruses and bacteria entering cells in a cholesterol-dependent manner. The change in cholesterol partitioning also favoured the recruitment of activated ERM (Ezrin, Radixin, Moesin) proteins at the plasma membrane and thus supported mitotic cell rounding.

OSBPL10, a novel candidate gene for high triglyceride trait in dyslipidemic Finnish subjects, regulates cellular lipid metabolism.

PubMed

Perttilä, Julia; Merikanto, Krista; Naukkarinen, Jussi; Surakka, Ida; Martin, Nicolas W; Tanhuanpää, Kimmo; Grimard, Vinciane; Taskinen, Marja-Riitta; Thiele, Christoph; Salomaa, Veikko; Jula, Antti; Perola, Markus; Virtanen, Ismo; Peltonen, Leena; Olkkonen, Vesa M

2009-08-01

Analysis of variants in three genes encoding oxysterol-binding protein (OSBP) homologues (OSBPL2, OSBPL9, OSBPL10) in Finnish families with familial low high-density lipoprotein (HDL) levels (N = 426) or familial combined hyperlipidemia (N = 684) revealed suggestive linkage of OSBPL10 single-nucleotide polymorphisms (SNPs) with extreme end high triglyceride (TG; >90th percentile) trait. Prompted by this initial finding, we carried out association analysis in a metabolic syndrome subcohort (Genmets) of Health2000 examination survey (N = 2,138), revealing association of multiple OSBPL10 SNPs with high serum TG levels (>95th percentile). To investigate whether OSBPL10 could be the gene underlying the observed linkage and association, we carried out functional experiments in the human hepatoma cell line Huh7. Silencing of OSBPL10 increased the incorporation of [(3)H]acetate into cholesterol and both [(3)H]acetate and [(3)H]oleate into triglycerides and enhanced the accumulation of secreted apolipoprotein B100 in growth medium, suggesting that the encoded protein ORP10 suppresses hepatic lipogenesis and very-low-density lipoprotein production. ORP10 was shown to associate dynamically with microtubules, consistent with its involvement in intracellular transport or organelle positioning. The data introduces OSBPL10 as a gene whose variation may contribute to high triglyceride levels in dyslipidemic Finnish subjects and provides evidence for ORP10 as a regulator of cellular lipid metabolism.

Optimization of bioactive compounds in buckwheat sprouts and their effect on blood cholesterol in hamsters.

PubMed

Lin, Li-Yun; Peng, Chiung-Chi; Yang, Ya-Lu; Peng, Robert Y

2008-02-27

Nutrient levels in buckwheats that were maximized in day 8 sprouts (D8SP) included total phenolics, quercetin, and l-ascorbic acid, whereas those of oxalic, malic, tartaric, and citric acids, rutin, and gamma-aminobutyric acid (GABA) were found to reach maximum levels on day 10. Ethanolic extract of D8SP (2.5 mg/mL) revealed potent free-radical scavenging (FRS) and antioxidative (ANO) capabilities. However, its Fe2+-chelating capability was only moderate. To further study the hypolipidemic activity of D8SP, 36 Syrian hamsters were grouped into six groups and fed for 28 days, respectively, with (i) control meal, (ii) high fat plus high cholesterol meal, (iii) high fat plus high cholesterol plus 2.5% of buckwheat seeds, (iv) high fat plus high cholesterol plus 25% of buckwheat seeds, (v) high fat plus high cholesterol plus 2.5% of D8SP, and (vi) high fat plus high cholesterol plus 25% of D8SP. High seed meal prominently enhanced body weight gain, whereas high sprout meal exhibited the highest feed efficiency. Ratios of liver/body weight (L/B) were significantly lowered by all BS meals. Although low seed meal reduced serum total cholesterol (TC) levels (p<0.05), its effect was still inferior to the high seed and sprout meals (p<0.01). In contrast, serum triglyceride (TG) levels were lowered only by the high seed and sprout meals (p<0.05). Alternatively, levels of serum low-density lipoprotein cholesterol (LDL-C) were significantly suppressed by all buckwheat meals (p<0.01). Serum high-density lipoprotein cholesterol (HDL-C) levels were increased, however, insignificantly. Nutraceutically more meaningful is that both LDL-C/HDL-C and TC/HDL-C ratios were significantly lowered (p<0.01). Apparently, hepatic TC levels were significantly reduced, whereas hepatic TG levels were totally unaffected. Conclusively, sprouting triggers a variety of nutritional changes in buckwheats. Day 8 sprouts, consisting of high polyphenolic and moderate quercetin contents, are nutraceutically maximized when hypocholesterolemic, hypotriglyceridemic, and antioxidative activities are concerned.

Changes in cholesterol homeostasis modify the response of F1B hamsters to dietary very long chain n-3 and n-6 polyunsaturated fatty acids

PubMed Central

2011-01-01

Background The plasma lipoprotein response of F1B Golden-Syrian hamsters fed diets high in very long chain (VLC) n-3 polyunsaturated fatty acids (PUFA) is paradoxical to that observed in humans. This anomaly is attributed, in part, to low lipoprotein lipase activity and is dependent on cholesterol status. To further elucidate the mechanism(s) for these responses, hamsters were fed diets containing supplemental fish oil (VLC n-3 PUFA) or safflower oil (n-6 PUFA) (both 10% [w/w]) and either cholesterol-supplemented (0.1% cholesterol [w/w]) or cholesterol-depleted (0.01% cholesterol [w/w] and 10 days prior to killing fed 0.15% lovastatin+2% cholestyramine [w/w]). Results Cholesterol-supplemented hamsters fed fish oil, relative to safflower oil, had higher non-high density lipoprotein (HDL) cholesterol and triglyceride concentrations (P < 0.001) which were associated with lower hepatic low density lipoprotein (LDL) receptor, sterol regulatory element binding protein (SREBP)-1c and acyl-CoA: cholesterol acyl transferase-2 (ACAT) mRNA and protein (p < 0.05), and higher hepatic apolipoprotein (apo) B-100 and apo E protein levels. In contrast, cholesterol-depleted hamsters fed fish oil, relative to safflower oil, had lower non-HDL cholesterol and triglyceride concentrations (P < 0.001) which were associated with lower hepatic SREBP-1c (p < 0.05) but not apo B-100, apo E or ACAT-2 mRNA or protein levels. Independent of cholesterol status, fish oil fed hamsters had lower HDL cholesterol concentrations (p < 0.001), which were associated with lower hepatic apoA-I protein levels (p < 0.05). Conclusion These data suggest disturbing cholesterol homeostasis in F1B hamsters alters their response to dietary fatty acids, which is reflected in altered plasma lipoprotein patterns and regulation of genes associated with their metabolism. PMID:22018327

Changes in cholesterol homeostasis modify the response of F1B hamsters to dietary very long chain n-3 and n-6 polyunsaturated fatty acids.

PubMed

Lecker, Jaime L; Matthan, Nirupa R; Billheimer, Jeffrey T; Rader, Daniel J; Lichtenstein, Alice H

2011-10-21

The plasma lipoprotein response of F1B Golden-Syrian hamsters fed diets high in very long chain (VLC) n-3 polyunsaturated fatty acids (PUFA) is paradoxical to that observed in humans. This anomaly is attributed, in part, to low lipoprotein lipase activity and is dependent on cholesterol status. To further elucidate the mechanism(s) for these responses, hamsters were fed diets containing supplemental fish oil (VLC n-3 PUFA) or safflower oil (n-6 PUFA) (both 10% [w/w]) and either cholesterol-supplemented (0.1% cholesterol [w/w]) or cholesterol-depleted (0.01% cholesterol [w/w] and 10 days prior to killing fed 0.15% lovastatin+2% cholestyramine [w/w]). Cholesterol-supplemented hamsters fed fish oil, relative to safflower oil, had higher non-high density lipoprotein (HDL) cholesterol and triglyceride concentrations (P < 0.001) which were associated with lower hepatic low density lipoprotein (LDL) receptor, sterol regulatory element binding protein (SREBP)-1c and acyl-CoA: cholesterol acyl transferase-2 (ACAT) mRNA and protein (p < 0.05), and higher hepatic apolipoprotein (apo) B-100 and apo E protein levels. In contrast, cholesterol-depleted hamsters fed fish oil, relative to safflower oil, had lower non-HDL cholesterol and triglyceride concentrations (P < 0.001) which were associated with lower hepatic SREBP-1c (p < 0.05) but not apo B-100, apo E or ACAT-2 mRNA or protein levels. Independent of cholesterol status, fish oil fed hamsters had lower HDL cholesterol concentrations (p < 0.001), which were associated with lower hepatic apoA-I protein levels (p < 0.05). These data suggest disturbing cholesterol homeostasis in F1B hamsters alters their response to dietary fatty acids, which is reflected in altered plasma lipoprotein patterns and regulation of genes associated with their metabolism.

The effect of olive oil-based ketogenic diet on serum lipid levels in epileptic children.

PubMed

Güzel, Orkide; Yılmaz, Unsal; Uysal, Utku; Arslan, Nur

2016-03-01

Ketogenic diet (KD) is one of the most effective therapies for intractable epilepsy. Olive oil is rich in monounsaturated fatty acids and antioxidant molecules and has some beneficial effects on lipid profile, inflammation and oxidant status. The aim of this study was to evaluate the serum lipid levels of children who were receiving olive oil-based KD for intractable seizures at least 1 year. 121 patients (mean age 7.45 ± 4.21 years, 57 girls) were enrolled. At baseline and post-treatment 1, 3, 6, and 12 months body mass index-SDS, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol and triglyceride levels were measured. Repeated measure ANOVA with post hoc Bonferroni correction was used for data analysis. The mean duration of KD was 15.4 ± 4.1 months. Mean total cholesterol, LDL-cholesterol and triglyceride levels were significantly higher at 1st, 3rd, 6th and 12th months of the KD treatment, compared to pre-treatment levels (p = 0.001), but showed no difference among during-treatment measurements. Mean body mass index-SDS and HDL-cholesterol levels were not different among the baseline and follow-up time points (p = 0.113 and p = 0.067, respectively). No child in this study discontinued the KD because of dyslipidemia. Even if rich in olive oil, high-fat KD causes significant increase in LDL-cholesterol and triglyceride levels. More studies are needed to determine the effect of KD on serum lipids in children using different fat sources in the diet.

A genetically informed test of cholesterol levels and self-control, depressive symptoms, antisocial behavior, and neuroticism.

PubMed

Schwartz, Joseph A; Rowland, Meghan W; Beaver, Kevin M

2014-08-01

Low cholesterol levels have been found to be associated with a wide range of behavioral problems, including violent and criminal behavior, and a wide range of psychological problems including impulsivity, depression, and other internalizing problems. The casual mechanisms underlying these associations remain largely unknown, but genetic factors may play a role in the etiology of such associations as previous research has found significant genetic influence on cholesterol levels and various deleterious behavioral and psychological outcomes. The current study addressed this existing gap in the literature by performing a genetically sensitive test of the association between cholesterol levels and various outcomes including levels of self-control, depressive symptoms, anger expression, and neuroticism. DeFries-Fulker (DF) analysis was used to analyze data from 388 twin pairs nested within the Survey of Midlife Development in the United States (MIDUS). The results of the genetically informed models revealed that high-density lipoprotein (HDL) cholesterol levels were negatively and significantly associated with depressive symptoms, had a marginally significant effect on neuroticism, and a nonsignificant effect on both anger expression and self-control. The findings may not extrapolate to the larger population of American adults since the subsample of twins with cholesterol information may not be nationally representative. Genetic influences play a significant role in the association between cholesterol levels and various deleterious outcomes and failing to control for these influences may result in model misspecification and may increase the probability of detecting a significant association when one does not actually exist. Copyright © 2014 Elsevier B.V. All rights reserved.

Apo AI/ABCA1-dependent and HDL3-mediated lipid efflux from compositionally distinct cholesterol-based microdomains.

PubMed

Drobnik, Wolfgang; Borsukova, Hana; Böttcher, Alfred; Pfeiffer, Alexandra; Liebisch, Gerhard; Schütz, Gerhard J; Schindler, Hansgeorg; Schmitz, Gerd

2002-04-01

We have investigated whether a raft heterogeneity exists in human monocyte-derived macrophages and fibroblasts and whether these microdomains are modulated by lipid efflux. Triton X-100 (Triton) or Lubrol WX (Lubrol) detergent-resistant membranes from cholesterol-loaded monocytes were associated with the following findings: (i) Lubrol-DRM contained most of the cellular cholesterol and at least 75% of Triton-detergent-resistant membranes. (ii) 'Lubrol rafts', defined by their solubility in Triton but insolubility in Lubrol, were enriched in unsaturated phosphatidylcholine and showed a lower cholesterol to choline-phospholipid ratio compared to Triton rafts. (iii) CD14 and CD55 were recovered in Triton- and Lubrol-detergent-resistant membranes, whereas CD11b was found exclusively in Triton DRM. ABCA1 implicated in apo AI-mediated lipid efflux and CDC42 were partially localized in Lubrol- but not in Triton-detergent-resistant membranes. (iv) Apo AI preferentially depleted cholesterol and choline-phospholipids from Lubrol rafts, whereas HDL3 additionally decreased the cholesterol content of Triton rafts. In fibroblasts, neither ABCA1 nor CDC42 was found in Lubrol rafts, and both apo AI and HDL3 reduced the lipid content in Lubrol- as well as in Triton-detergent-resistant membranes. In summary, we provide evidence for the existence of compositionally distinct membrane microdomains in human cells and their modulation by apo AI/ABCA1-dependent and HDL3-mediated lipid efflux.

Impact of Circulating Cholesterol Levels on Growth and Intratumoral Androgen Concentration of Prostate Tumors

PubMed Central

Pelton, Kristine; Freeman, Michael R.; Montgomery, R. Bruce

2012-01-01

Prostate cancer (PCa) is the second most common cancer in men. Androgen deprivation therapy (ADT) leads to tumor involution and reduction of tumor burden. However, tumors eventually reemerge that have overcome the absence of gonadal androgens, termed castration resistant PCa (CRPC). Theories underlying the development of CRPC include androgen receptor (AR) mutation allowing for promiscuous activation by non-androgens, AR amplification and overexpression leading to hypersensitivity to low androgen levels, and/or tumoral uptake and conversion of adrenally derived androgens. More recently it has been proposed that prostate tumor cells synthesize their own androgens through de novo steroidogenesis, which involves the step-wise synthesis of androgens from cholesterol. Using the in vivo LNCaP PCa xenograft model, previous data from our group demonstrated that a hypercholesterolemia diet potentiates prostatic tumor growth via induction of angiogenesis. Using this same model we now demonstrate that circulating cholesterol levels are significantly associated with tumor size (R = 0.3957, p = 0.0049) and intratumoral levels of testosterone (R = 0.41, p = 0.0023) in LNCaP tumors grown in hormonally intact mice. We demonstrate tumoral expression of cholesterol uptake genes as well as the spectrum of steroidogenic enzymes necessary for androgen biosynthesis from cholesterol. Moreover, we show that circulating cholesterol levels are directly correlated with tumoral expression of CYP17A, the critical enzyme required for de novo synthesis of androgens from cholesterol (R = 0.4073, p = 0.025) Since hypercholesterolemia does not raise circulating androgen levels and the adrenal gland of the mouse synthesizes minimal androgens, this study provides evidence that hypercholesterolemia increases intratumoral de novo steroidogenesis. Our results are consistent with the hypothesis that cholesterol-fueled intratumoral androgen synthesis may accelerate the growth of prostate tumors, and suggest that treatment of CRPC may be optimized by inclusion of cholesterol reduction therapies in conjunction with therapies targeting androgen synthesis and the AR. PMID:22279565

MUC Expression in Gallbladder Epithelial Tissues in Cholesterol-Associated Gallbladder Disease

PubMed Central

Yoo, Kyo-Sang; Choi, Ho Soon; Jun, Dae Won; Lee, Hang Lak; Lee, Oh Young; Yoon, Byung Chul; Lee, Kyeong Geun; Paik, Seung Sam; Kim, Yong Seok; Lee, Jin

2016-01-01

Background/Aims Gallstone pathogenesis is linked to mucin hypersecretion and bacterial infection. Several mucin genes have been identified in gallbladder epithelial cells (GBECs). We investigated MUC expression in cholesterol-associated gallbladder disease and evaluated the relationship between mucin and bacterial infection. Methods The present study involved 20 patients with cholesterol stones with cholecystitis, five with cholesterol stones with cholesterolosis, six with cholesterol polyps, two with gallbladder cancer, and six controls. Canine GBECs treated with lipopolysaccharide were also studied. MUC3, MUC5AC, MUC5B, and MUC6 antibodies were used for dot/slot immunoblotting and immunohistochemical studies of the gallbladder epithelial tissues, canine GBECs, and bile. Reverse-transcription polymerase chain reaction was performed to evaluate MUC3 and MUC5B expression. Results MUC3, MUC5AC, MUC5B, and MUC6 were expressed in the normal gallbladder epithelium, and of those, MUC3 and MUC5B exhibited the highest expression levels. Greatly increased levels of MUC3 and MUC5B expression were observed in the cholesterol stone group, and slightly increased levels were observed in the cholesterol polyp group; MUC3 and MUC5B mRNA was also upregulated in those groups. Canine GBECs treated with lipopolysaccharide also showed upregulation of MUC3 and MUC5B. Conclusions The mucin genes with the highest expression levels in gallbladder tissue in cholesterol-associated diseases were MUC3 and MUC5B. Cholesterol stones and gallbladder infections were associated with increased MUC3 and MUC5B expression. PMID:27563024

Serum cholesterol levels of Seventh-day Adventists.

PubMed

Taylor, C B; Allen, E S; Mikkelson, B; Kang-Jey, H

1976-10-01

Serum cholesterol levels and dietary habits were surveyed in 27 male and 34 female Seventh-day Adventist. All subjects studied were lacto-ovo-vegetarians and a few consumed some meat products. Their serum cholesterol levels, significantly lower than those of the United States general population, showed no sex difference but increased with age and were higher in overweight males. Their levels, however, were much higher than those of true vegetarians which was most likely attributable to their consumption, even though to a limited acount, of dairy foods.

Measurement of Mitochondrial Cholesterol Import Using a Mitochondria-Targeted CYP11A1 Fusion Construct.

PubMed

Kennedy, Barry E; Charman, Mark; Karten, Barbara

2017-01-01

All animal membranes require cholesterol as an essential regulator of biophysical properties and function, but the levels of cholesterol vary widely among different subcellular compartments. Mitochondria, and in particular the inner mitochondrial membrane, have the lowest levels of cholesterol in the cell. Nevertheless, mitochondria need cholesterol for membrane maintenance and biogenesis, as well as oxysterol, steroid, and hepatic bile acid production. Alterations in mitochondrial cholesterol have been associated with a range of pathological conditions, including cancer, hepatosteatosis, cardiac ischemia, Alzheimer's, and Niemann-Pick Type C Disease. The mechanisms of mitochondrial cholesterol import are not fully elucidated yet, and may vary in different cell types and environmental conditions. Measuring cholesterol trafficking to the mitochondrial membranes is technically challenging because of its low abundance; for example, traditional pulse-chase experiments with isotope-labeled cholesterol are not feasible. Here, we describe improvements to a method first developed by the Miller group at the University of California to measure cholesterol trafficking to the inner mitochondrial membrane (IMM) through the conversion of cholesterol to pregnenolone. This method uses a mitochondria-targeted, ectopically expressed fusion construct of CYP11A1, ferredoxin reductase and ferredoxin. Pregnenolone is formed exclusively from cholesterol at the IMM, and can be analyzed with high sensitivity and specificity through ELISA or radioimmunoassay of the medium/buffer to reflect mitochondrial cholesterol import. This assay can be used to investigate the effects of genetic or pharmacological interventions on mitochondrial cholesterol import in cultured cells or isolated mitochondria.

The relationship between job stress and dyslipidemia.

PubMed

Catalina-Romero, C; Calvo, E; Sánchez-Chaparro, M A; Valdivielso, P; Sainz, J C; Cabrera, M; González-Quintela, A; Román, J

2013-03-01

To investigate whether there is an association between job stress, lipid profile and dyslipidemia diagnosis. This study used a questionnaire to evaluate job stress and lifestyle variables in 91,593 workers undergoing periodic checkups. Serum lipid levels were measured in all cases. The prevalence of job stress was 8.7% (95% CI, 8.5-8.8%). In bivariate analyses, job stress was significantly associated with previous dyslipidemia diagnosis (p < 0.001), lipid-lowering therapy (p < 0.001), and altered total-cholesterol (p = 0.001), HDL-cholesterol (p < 0.001) and LDL-cholesterol levels (p = 0.025). After adjusting for potential confounding variables, job stress was still associated with current dyslipidemia diagnosis (OR = 1.10; 95% CI, 1.04-1.17), high LDL-cholesterol (OR = 1.14; 95% CI, 1.05-1.23), low HDL-cholesterol (OR 1.08; 95% CI, 1.01-1.15), high total cholesterol/HDL-cholesterol ratio (OR 1.13; 95% CI, 1.05-1.23) and high LDL-cholesterol/HDL-cholesterol ratio (OR 1.11; 95% CI, 1.04-1.19). These results support the hypothesis of an association between job stress and lipid disturbances.

A new cholesterol biosynthesis and absorption disorder associated with epilepsy, hypogonadism, and cerebro-cerebello-bulbar degeneration.

PubMed

Korematsu, Seigo; Uchiyama, Shin-ichi; Honda, Akira; Izumi, Tatsuro

2014-06-01

Cholesterol is one of the main components of human cell membranes and constitutes an essential substance in the central nervous system, endocrine system, and its hormones, including sex hormones. A 19-year-old male patient presented with failure to thrive, psychomotor deterioration, intractable epilepsy, hypogonadism, and cerebro-cerebello-bulbar degeneration. His serum level of cholesterol was low, ranging from 78.7 to 116.5 mg/dL. The serum concentrations of intermediates in the cholesterol biosynthesis pathway, such as 7-dehydrocholesterol, 8-dehydrocholesterol, desmosterol, lathosterol, and dihydrolanosterol, were not increased. In addition, the levels of the urinary cholesterol biosynthesis marker mevalonic acid, the serum cholesterol absorption markers, campesterol and sitosterol, and the serum cholesterol catabolism marker, 7α-hydroxycholesterol, were all low. A serum biomarker analysis indicated that the patient's basic abnormality differed from that of Smith-Lemli-Opitz syndrome and other known disorders of cholesterol metabolism. Therefore, this individual may have a new metabolic disorder with hypocholesterolemia because of decreased biosynthesis and absorption of cholesterol. Copyright © 2014 Elsevier Inc. All rights reserved.

Cholesterol metabolism and serum non-cholesterol sterols: summary of 13 plant stanol ester interventions

PubMed Central

2014-01-01

Background The efficacy and safety of plant stanols added to food products as serum cholesterol lowering agents have been demonstrated convincingly, but their effects on cholesterol metabolism and on serum non-cholesterol sterols is less evaluated. The aim of this study was to assess the validity of serum non-cholesterol sterols and squalene as bioindices of cholesterol synthesis and absorption, and to examine how the individual serum non-cholesterol sterols respond to consumption of plant stanols. Methods We collected all randomized, controlled plant stanol ester (STAEST) interventions in which serum cholestanol, plant sterols campesterol and sitosterol, and at least two serum cholesterol precursors had been analysed. According to these criteria, there was a total of 13 studies (total 868 subjects without lipid-lowering medication; plant stanol doses varied from 0.8 to 8.8 g/d added in esterified form; the duration of the studies varied from 4 to 52 weeks). Serum non-cholesterol sterols were assayed with gas–liquid chromatography, cholesterol synthesis with the sterol balance technique, and fractional cholesterol absorption with the dual continuous isotope feeding method. Results The results demonstrated that during the control and the STAEST periods, the serum plant sterol/cholesterol- and the cholestanol/cholesterol-ratios reflected fractional cholesterol absorption, and the precursor sterol/cholesterol-ratios reflected cholesterol synthesis. Plant sterol levels were dose-dependently reduced by STAEST so that 2 g of plant stanols reduced serum campesterol/cholesterol-ratio on average by 32%. Serum cholestanol/cholesterol-ratio was reduced less frequently than those of the plant sterols by STAEST, and the cholesterol precursor sterol ratios did not change consistently in the individual studies emphasizing the importance of monitoring more than one surrogate serum marker. Conclusions Serum non-cholesterol sterols are valid markers of cholesterol absorption and synthesis even during cholesterol absorption inhibition with STAEST. Serum plant sterol concentrations decrease dose-dependently in response to plant stanols suggesting that the higher the plant stanol dose, the more cholesterol absorption is inhibited and the greater the reduction in LDL cholesterol level is that can be achieved. Trial registration Clinical Trials Register # NCT00698256 [Eur J Nutr 2010, 49:111-117] PMID:24766766

Cholesterol metabolism and serum non-cholesterol sterols: summary of 13 plant stanol ester interventions.

PubMed

Hallikainen, Maarit; Simonen, Piia; Gylling, Helena

2014-04-27

The efficacy and safety of plant stanols added to food products as serum cholesterol lowering agents have been demonstrated convincingly, but their effects on cholesterol metabolism and on serum non-cholesterol sterols is less evaluated. The aim of this study was to assess the validity of serum non-cholesterol sterols and squalene as bioindices of cholesterol synthesis and absorption, and to examine how the individual serum non-cholesterol sterols respond to consumption of plant stanols. We collected all randomized, controlled plant stanol ester (STAEST) interventions in which serum cholestanol, plant sterols campesterol and sitosterol, and at least two serum cholesterol precursors had been analysed. According to these criteria, there was a total of 13 studies (total 868 subjects without lipid-lowering medication; plant stanol doses varied from 0.8 to 8.8 g/d added in esterified form; the duration of the studies varied from 4 to 52 weeks). Serum non-cholesterol sterols were assayed with gas-liquid chromatography, cholesterol synthesis with the sterol balance technique, and fractional cholesterol absorption with the dual continuous isotope feeding method. The results demonstrated that during the control and the STAEST periods, the serum plant sterol/cholesterol- and the cholestanol/cholesterol-ratios reflected fractional cholesterol absorption, and the precursor sterol/cholesterol-ratios reflected cholesterol synthesis. Plant sterol levels were dose-dependently reduced by STAEST so that 2 g of plant stanols reduced serum campesterol/cholesterol-ratio on average by 32%. Serum cholestanol/cholesterol-ratio was reduced less frequently than those of the plant sterols by STAEST, and the cholesterol precursor sterol ratios did not change consistently in the individual studies emphasizing the importance of monitoring more than one surrogate serum marker. Serum non-cholesterol sterols are valid markers of cholesterol absorption and synthesis even during cholesterol absorption inhibition with STAEST. Serum plant sterol concentrations decrease dose-dependently in response to plant stanols suggesting that the higher the plant stanol dose, the more cholesterol absorption is inhibited and the greater the reduction in LDL cholesterol level is that can be achieved. Clinical Trials Register # NCT00698256 [Eur J Nutr 2010, 49:111-117].

Lactic acid bacteria affect serum cholesterol levels, harmful fecal enzyme activity, and fecal water content.

PubMed

Lee, Do Kyung; Jang, Seok; Baek, Eun Hye; Kim, Mi Jin; Lee, Kyung Soon; Shin, Hea Soon; Chung, Myung Jun; Kim, Jin Eung; Lee, Kang Oh; Ha, Nam Joo

2009-06-11

Lactic acid bacteria (LAB) are beneficial probiotic organisms that contribute to improved nutrition, microbial balance, and immuno-enhancement of the intestinal tract, as well as lower cholesterol. Although present in many foods, most trials have been in spreads or dairy products. Here we tested whether Bifidobacteria isolates could lower cholesterol, inhibit harmful enzyme activities, and control fecal water content. In vitro culture experiments were performed to evaluate the ability of Bifidobacterium spp. isolated from healthy Koreans (20 approximately 30 years old) to reduce cholesterol-levels in MRS broth containing polyoxyethanylcholesterol sebacate. Animal experiments were performed to investigate the effects on lowering cholesterol, inhibiting harmful enzyme activities, and controlling fecal water content. For animal studies, 0.2 ml of the selected strain cultures (108 approximately 109 CFU/ml) were orally administered to SD rats (fed a high-cholesterol diet) every day for 2 weeks. B. longum SPM1207 reduced serum total cholesterol and LDL levels significantly (p < 0.05), and slightly increased serum HDL. B. longum SPM1207 also increased fecal LAB levels and fecal water content, and reduced body weight and harmful intestinal enzyme activities. Daily consumption of B. longum SPM1207 can help in managing mild to moderate hypercholesterolemia, with potential to improve human health by helping to prevent colon cancer and constipation.

Association between cholesterol plasma levels and craving among heroin users.

PubMed

Lin, Shih-Hsien; Yang, Yen Kuang; Lee, Sheng-Yu; Hsieh, Pei Chun; Chen, Po See; Lu, Ru-Band; Chen, Kao Chin

2012-12-01

Lipids may play some roles in the central nervous system functions that are associated with drug addiction. To date, cholesterol is known to influence relapse of cocaine use. However, the relationship between cholesterol and heroin craving is unclear. This study examined the concurrent association between cholesterol and craving. The serum lipid levels of 70 heroin users who were undergoing or had undergone a methadone maintenance therapy were measured. Their craving and demographic data were assessed. Total cholesterol and low-density lipoprotein cholesterol are negatively associated with craving before (r = -0.33, P < 0.01, and r = -0.36, P < 0.01, respectively) and after controlling for the effects of potential confounders (β = -0.38, P < 0.01, and β = -0.42, P < 0.01, respectively). Cholesterol could be associated with the cognitive aspect of craving and may be a potential marker to predict risk of drug relapse.

The inhibitory effect of black soybean on hepatic cholesterol accumulation in high cholesterol and high fat diet-induced non-alcoholic fatty liver disease.

PubMed

Jung, Ji-Hye; Kim, Hyun-Sook

2013-10-01

Non-alcoholic fatty liver disease (NAFLD) is defined as excess of fat in the liver. We investigated the effects of black soybean on the cholesterol metabolism and insulin resistance of mice fed high cholesterol/fat diets. Mice were randomly allocated into four groups that were fed different diets: the normal cholesterol/fat diet; high cholesterol/fat diets (HCD); and HCD with 1%, and 4% black soybean powder (1B-HCD, and 4B-HCD). Liver total cholesterol and triglyceride concentrations were significantly lower in the black soybean-supplemented groups than that in the HCD group. PCR revealed significantly lower hepatic SREBP2 and HMG-CoA reductase mRNA levels of black soybean-supplemented mice. Real-time PCR revealed significantly higher hepatic ABCA1 mRNA level of black soybean-supplemented mice, which may increase cholesterol efflux. Liver bile acids concentration was significantly high in the 4B-HCD group. Black soybean stimulated secretion of adiponectin, activation of pAMPK, and eliminated free fatty acids in the liver. Black soybean supplementation decreased MDA and nitrate level. The activities of SOD, catalase, and GPx were restored by black soybean supplementation. Our data strongly indicate that black soybean influences the balance between oxidative and antioxidative stress. We suggest that black soybean improves cholesterol metabolism, insulin resistance, and alleviates oxidative damage in NAFLD. Published by Elsevier Ltd.

Vitamin D Levels and Lipid Response to Atorvastatin

PubMed Central

Pérez-Castrillón, José Luis; Abad Manteca, Laura; Vega, Gemma; del Pino Montes, Javier; de Luis, Daniel; Dueňas Laita, Antonio

2010-01-01

Adequate vitamin D levels are necessary for good vascular health. 1,25-dihydroxycholecalciferol activates CYP3A4, an enzyme of the cytochrome P450 system, which metabolizes atorvastatin to its main metabolites. The objective of this study was to evaluate the response of cholesterol and triglycerides to atorvastatin according to vitamin D levels. Sixty-three patients with acute myocardial infarction treated with low and high doses of atorvastatin were included. Levels of total cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol were measured at baseline and at 12 months of follow-up. Baseline levels of 25-hydroxyvitamin D (25-OHD) were classified as deficient (<30 nmol/L), insufficient (30–50 nmol/L), and normal (>50 nmol/L). In patients with 25-OHD <30 nmol/L, there were no significant changes in levels of total cholesterol (173 ± 47 mg/dL versus 164 ± 51 mg/dL), triglycerides (151 ± 49 mg/dL versus 177 ± 94 mg/dL), and LDL cholesterol (111 ± 48 mg/dL versus 92 45 ± mg/dL); whereas patients with insufficient (30–50 nmol/L) and normal vitamin D (>50 nmol/L) had a good response to atorvastatin. We suggest that vitamin D concentrations >30 nmol/L may be required for atorvastatin to reduce lipid levels in patients with acute myocardial infarction. PMID:20016682

Cholesterol and Women's Health

MedlinePlus

... having a high LDL cholesterol level lead to cardiovascular disease? • Besides abnormal cholesterol, what are other risk factors for cardiovascular disease? • What are some risk factors for cardiovascular disease ...

Structured triglycerides containing caprylic (8:0) and oleic (18:1) fatty acids reduce blood cholesterol concentrations and aortic cholesterol accumulation in hamsters.

PubMed

Wilson, Thomas A; Kritchevsky, David; Kotyla, Timothy; Nicolosi, Robert J

2006-03-01

The effects of structured triglycerides containing one long chain fatty acid (oleic acid, C18:1) and one short chain saturated fatty acid (caprylic acid, 8:0) on lipidemia, liver and aortic cholesterol, and fecal neutral sterol excretion were investigated in male Golden Syrian hamsters fed a hypercholesterolemic regimen consisting of 89.9% commercial ration to which was added 10% coconut oil and 0.1% cholesterol (w/w). After 2 weeks on the HCD diet, the hamsters were bled, following an overnight fast (16 h) and placed into one of three dietary treatments of eight animals each based on similar plasma cholesterol levels. The hamsters either continued on the HCD diet or were placed on diets in which the coconut oil was replaced by one of two structured triglycerides, namely, 1(3),2-dicaproyl-3(1)-oleoylglycerol (OCC) or 1,3-dicaproyl-2-oleoylglycerol (COC) at 10% by weight. Plasma total cholesterol (TC) in hamsters fed the OCC and COC compared to the HCD were reduced 40% and 49%, respectively (P<0.05). Similarly, hamsters fed the OCC and COC diets reduced their plasma nonHDL cholesterol levels by 47% and 57%, respectively (P<0.05), compared to hamsters fed the HCD after 2 weeks of dietary treatment. Although hamsters fed the OCC (-26%) and COC (-32%) had significantly lower plasma HDL levels compared to HCD, (P<0.05), the plasma nonHDL/HDL cholesterol ratio was significantly lower (P<0.05) compared to the HCD for the OCC-fed (-27%) and the COC-fed (-38%) hamsters, respectively. Compared to the HCD group, aortic esterified cholesterol was 20% and 53% lower for the OCC and COC groups, respectively, with the latter reaching statistical significance, P<0.05. In conclusion, the hamsters fed the structured triglyceride oils had lower blood cholesterol levels and lower aortic accumulation of cholesterol compared to the control fed hamsters.

Endogenous sterol biosynthesis is important for mitochondrial function and cell morphology in procyclic forms of Trypanosoma brucei.

PubMed

Pérez-Moreno, Guiomar; Sealey-Cardona, Marco; Rodrigues-Poveda, Carlos; Gelb, Michael H; Ruiz-Pérez, Luis Miguel; Castillo-Acosta, Víctor; Urbina, Julio A; González-Pacanowska, Dolores

2012-10-01

Sterol biosynthesis inhibitors are promising entities for the treatment of trypanosomal diseases. Insect forms of Trypanosoma brucei, the causative agent of sleeping sickness, synthesize ergosterol and other 24-alkylated sterols, yet also incorporate cholesterol from the medium. While sterol function has been investigated by pharmacological manipulation of sterol biosynthesis, molecular mechanisms by which endogenous sterols influence cellular processes remain largely unknown in trypanosomes. Here we analyse by RNA interference, the effects of a perturbation of three specific steps of endogenous sterol biosynthesis in order to dissect the role of specific intermediates in proliferation, mitochondrial function and cellular morphology in procyclic cells. A decrease in the levels of squalene synthase and squalene epoxidase resulted in a depletion of cellular sterol intermediates and end products, impaired cell growth and led to aberrant morphologies, DNA fragmentation and a profound modification of mitochondrial structure and function. In contrast, cells deficient in sterol methyl transferase, the enzyme involved in 24-alkylation, exhibited a normal growth phenotype in spite of a complete abolition of the synthesis and content of 24-alkyl sterols. Thus, the data provided indicates that while the depletion of squalene and post-squalene endogenous sterol metabolites results in profound cellular defects, bulk 24-alkyl sterols are not strictly required to support growth in insect forms of T. brucei in vitro. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Palm oil: a healthful and cost-effective dietary component.

PubMed

Ong, A S H; Goh, S H

2002-03-01

Palm oil is an excellent choice for food manufacturers because of its nutritional benefits and versatility. The oil is highly structured to contain predominantly oleic acid at the sn2-position in the major triacylglycerols to account for the beneficial effects described in numerous nutritional studies. Oil quality and nutritional benefits have been assured for the variety of foods that can be manufactured from the oil directly or from blends with other oils while remaining trans-free. The oxidative stability coupled with the cost-effectiveness is unparalleled among cholesterol-free oils, and these values can be extended to blends of polyunsaturated oils to provide long shelf-life. Presently the supply of genetic-modification-free palm oil is assured at economic prices, since the oil palm is a perennial crop with unparalleled productivity. Numerous studies have confirmed the nutritional value of palm oil as a result of the high monounsaturation at the crucial 2-position of the oil's triacylglycerols, making the oil as healthful as olive oil. It is now recognized that the contribution of dietary fats to blood lipids and cholesterol modulation is a consequence of the digestion, absorption, and metabolism of the fats. Lipolytic hydrolysis of palm oil glycerides containing predominantly oleic acid at the 2 position and palmitic and stearic acids at the 1 and 3 positions allows for the ready absorption of the 2-monoacrylglycerols while the saturated free fatty acids remain poorly absorbed. Dietary palm oil in balanced diets generally reduced blood cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides while raising the high-density lipoprotein (HDL) cholesterol. Improved lipoprotein(a) and apo-A1 levels were also demonstrated from palm oil diets; an important benefits also comes from the lowering of blood triglycerides (or reduced fat storage) as compared with those from polyunsaturated fat diets. Virgin palm oil also provides carotenes apart from tocotrienols and tocopherols that have been shown to be powerful antioxidants and potential mediators of cellular functions. These compounds can be antithrombotic, cause an increase of the prostacyclin/thromboxane ratio, reduce restenosis, and inhibit HMG-CoA-reductase (thus reducing) cholesterol biosynthesis). Red palm oil is a rich source of beta-carotene as well as of alpha-tocopherol and tocotrienols.

G-protein estrogen receptor as a regulator of low-density lipoprotein cholesterol metabolism: cellular and population genetic studies.

PubMed

Hussain, Yasin; Ding, Qingming; Connelly, Philip W; Brunt, J Howard; Ban, Matthew R; McIntyre, Adam D; Huff, Murray W; Gros, Robert; Hegele, Robert A; Feldman, Ross D

2015-01-01

Estrogen deficiency is linked with increased low-density lipoprotein (LDL) cholesterol. The hormone receptor mediating this effect is unknown. G-protein estrogen receptor (GPER) is a recently recognized G-protein-coupled receptor that is activated by estrogens. We recently identified a common hypofunctional missense variant of GPER, namely P16L. However, the role of GPER in LDL metabolism is unknown. Therefore, we examined the association of the P16L genotype with plasma LDL cholesterol level. Furthermore, we studied the role of GPER in regulating expression of the LDL receptor and proprotein convertase subtilisin kexin type 9. Our discovery cohort was a genetically isolated population of Northern European descent, and our validation cohort consisted of normal, healthy women aged 18 to 56 years from London, Ontario. In addition, we examined the effect of GPER on the regulation of proprotein convertase subtilisin kexin type 9 and LDL receptor expression by the treatment with the GPER agonist, G1. In the discovery cohort, GPER P16L genotype was associated with a significant increase in LDL cholesterol (mean±SEM): 3.18±0.05, 3.25±0.08, and 4.25±0.33 mmol/L, respectively, in subjects with CC (homozygous for P16), CT (heterozygotes), and TT (homozygous for L16) genotypes (P<0.05). In the validation cohort (n=339), the GPER P16L genotype was associated with a similar increase in LDL cholesterol: 2.17±0.05, 2.34±0.06, and 2.42±0.16 mmol/L, respectively, in subjects with CC, CT, and TT genotypes (P<0.05). In the human hepatic carcinoma cell line, the GPER agonist, G1, mediated a concentration-dependent increase in LDL receptor expression, blocked by either pretreatment with the GPER antagonist G15 or by shRNA-mediated GPER downregulation. G1 also mediated a GPER- and concentration-dependent decrease in proprotein convertase subtilisin kexin type 9 expression. GPER activation upregulates LDL receptor expression, probably at least, in part, via proprotein convertase subtilisin kexin type 9 downregulation. Furthermore, humans carrying the hypofunctional P16L genetic variant of GPER have increased plasma LDL cholesterol. In aggregate, these data suggest an important role of GPER in the regulation of LDL receptor expression and consequently LDL metabolism. © 2014 American Heart Association, Inc.

[Effect of raw and cooked nopal (Opuntia ficus indica) ingestion on growth and profile of total cholesterol, lipoproteins, and blood glucose in rats].

PubMed

Cárdenas Medellín, M L; Serna Saldívar, S O; Velazco de la Garza, J

1998-12-01

Two different concentrations (approx. 6 and 12%) and two presentations (raw and cooked) of dehydrated nopal were fed to laboratory rats and growth and serum total cholesterol, lipoprotein profile and glucose determined. Samples of raw and cooked nopal were chemically characterized for moisture, protein, ash, crude fiber, ether extract, total dietary fiber, reducing sugars, amino acids, minerals and gross energy. Cooking slightly affected some of the nutrients analyzed. After one month feeding, blood was withdrawn via intracardiac puncture and serum glucose, total cholesterol, HDL, LDL, and VLDL were determined. Rats fed 12% nopal had lower weight gains (P < 0.05) when compared with counterparts fed 6% nopal or the control diet. Consumption of nopal did not affect (P > 0.05) glucose, total cholesterol and HDL cholesterol levels. However, rats fed raw nopal at the 12% concentration level had a 34% reduction in LDL cholesterol levels; thus, it was concluded that raw nopal had a potentially beneficial effect for hypercholesterolemic individuals.

Detection of virgin coconut oil adulteration with animal fats using quantitative cholesterol by GC × GC-TOF/MS analysis.

PubMed

Xu, Baocheng; Li, Peiwu; Ma, Fei; Wang, Xiuping; Matthäus, Bertrand; Chen, Ran; Yang, Qingqing; Zhang, Wen; Zhang, Qi

2015-07-01

A new method based on the cholesterol level was developed to detect the presence of animal fats in virgin coconut oil (VCO). In this study, the sterols in VCO and animal fats was separated using conventional one-dimensional gas chromatography (1D GC) and comprehensive two-dimensional gas chromatography (GC×GC). Compared with 1D GC, the GC×GC system could obtain a complete baseline separation of the sterol trimethylsilyl ethers derived from cholesterol and cholestanol, so that the cholesterol content in pure VCO and false VCO adulterated with animal fats could be accurately determined. Cholesterol, a main sterol found in animal fats, represented less than 5mg/kg of VCO. The study demonstrated that the determination of the cholesterol level in VCO could be used for reliable detection of the presence of lard, chicken fat, mutton tallow, beef tallow, or their mixture in VCO at a level as little as 0.25%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Vaccinium bracteatum Thunb. leaves extract on blood glucose and plasma lipid levels in streptozotocin-induced diabetic mice.

PubMed

Wang, Li; Zhang, Xue Tong; Zhang, Hai Yan; Yao, Hui Yuan; Zhang, Hui

2010-08-09

To investigate the hypoglycemic effects of Vaccinium bracteatum Thunb. leaves (VBTL) extract in streptozotocin-induced diabetic mice. After administration of VBTL extract for 4 weeks, the body weight, organ weight, blood glucose (BG), insulin and plasma lipid levels of streptozotocin-induced diabetic mice were measured. Body weights of diabetic mice treated with VBTL extract were partly recovered. The BG levels of AEG (diabetic mice treated with VBTL aqueous extract) were reduced to 91.52 and 85.82% at week 2 and week 4, respectively (P<0.05), while those of EEG (diabetic mice treated with VBTL ethanolic extract) were reduced slightly (P>0.05). The insulin levels of AEG and EEG were obviously higher (P<0.05) than those of MC (diabetic mice in model control group). Comparing with MC, AEG and EEG had significantly lower (P<0.05) TC or TG levels and similar HDL-cholesterol or LDL-cholesterol levels. In comparison with non-diabetic control mice, AEG had similar plasma lipid levels except higher LDL-cholesterol level, while EEG had higher TC, TG and LDL-cholesterol levels and lower HDL-cholesterol levels. Both aqueous and ethanolic extract of VBTL possess a potential hypoglycemic effect in streptozotocin-induced diabetic mice. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Acidic Polysaccharide Extracts from Gastrodia Rhizomes Suppress the Atherosclerosis Risk Index through Inhibition of the Serum Cholesterol Composition in Sprague Dawley Rats Fed a High-Fat Diet

PubMed Central

Kim, Kui-Jin; Lee, Ok-Hwan; Han, Chan-Kyu; Kim, Young-Chan; Hong, Hee-Do

2012-01-01

Obesity is associated with a broad spectrum of cardio-metabolic disturbances, including atherosclerosis and cardiovascular disease (CDV). A high-fat diet has been shown to cause an elevation of the plasma cholesterol levels in humans, and the control of serum cholesterol has been demonstrated to be important in the prevention of CVD and atherosclerosis. The aims of this study were to demonstrate that crude and acidic polysaccharide extracts from Gastrodia rhizomes suppress atherosclerosis through the regulation of serum lipids in Sprague Dawley (SD) rats fed a high-fat diet. We examined the concentrations of serum lipids, including total cholesterol, triglycerides, high-density lipoproteins (HDL) cholesterol, and low-density lipoproteins (LDL) cholesterol, in SD rats fed a high-fat diet and evaluated the atherogenic index. Here, we show that both crude and acidic polysaccharide extracts from Gastrodia rhizomes inhibited the total cholesterol and LDL levels. Moreover, there was a significantly suppressed atherosclerosis risk due to the acidic polysaccharide extract from Gastrodia rhizome. Taken together, our results suggested that acidic polysaccharide extracts from Gastrodia rhizomes might be beneficial for lowering the incidence of CVD and atherosclerosis by reducing the de novo synthesis of total cholesterol and the LDL levels. PMID:22408412

Acidic polysaccharide extracts from Gastrodia Rhizomes suppress the atherosclerosis risk index through inhibition of the serum cholesterol composition in Sprague Dawley rats fed a high-fat diet.

PubMed

Kim, Kui-Jin; Lee, Ok-Hwan; Han, Chan-Kyu; Kim, Young-Chan; Hong, Hee-Do

2012-01-01

Obesity is associated with a broad spectrum of cardio-metabolic disturbances, including atherosclerosis and cardiovascular disease (CDV). A high-fat diet has been shown to cause an elevation of the plasma cholesterol levels in humans, and the control of serum cholesterol has been demonstrated to be important in the prevention of CVD and atherosclerosis. The aims of this study were to demonstrate that crude and acidic polysaccharide extracts from Gastrodia rhizomes suppress atherosclerosis through the regulation of serum lipids in Sprague Dawley (SD) rats fed a high-fat diet. We examined the concentrations of serum lipids, including total cholesterol, triglycerides, high-density lipoproteins (HDL) cholesterol, and low-density lipoproteins (LDL) cholesterol, in SD rats fed a high-fat diet and evaluated the atherogenic index. Here, we show that both crude and acidic polysaccharide extracts from Gastrodia rhizomes inhibited the total cholesterol and LDL levels. Moreover, there was a significantly suppressed atherosclerosis risk due to the acidic polysaccharide extract from Gastrodia rhizome. Taken together, our results suggested that acidic polysaccharide extracts from Gastrodia rhizomes might be beneficial for lowering the incidence of CVD and atherosclerosis by reducing the de novo synthesis of total cholesterol and the LDL levels.

Protonated nanostructured aluminosilicate (NSAS) reduces plasma cholesterol concentrations and atherosclerotic lesions in Apolipoprotein E deficient mice fed a high cholesterol and high fat diet

PubMed Central

Sivak, Olena; Darlington, Jerry; Gershkovich, Pavel; Constantinides, Panayiotis P; Wasan, Kishor M

2009-01-01

The aim of this work was to assess the effect of chronic administration of protonated nanostructured aluminosilicate (NSAS) on the plasma cholesterol levels and development of atherosclerotic lesions in Apolipoprotein (ApoE) deficient mice fed a high cholesterol and high fat diet. Apolipoprotein E (ApoE) deficient mice were divided into the following treatment groups: protonated NSAS 1.4% (w/w), untreated control and 2% (w/w) stigmastanol mixed with high-cholesterol/high-fat diet. Animals were treated for 12 weeks, blood samples were withdrawn every 4 weeks for determination of plasma cholesterol and triglyceride levels. At the end of the study the aortic roots were harvested for assessment of atherosclerotic lesions. NSAS at 1.4% (w/w) and stigmastanol at 2% (w/w) treatment groups showed significant decreases in plasma cholesterol concentrations at all time points relative to the control animals. The lesion sum area in 1.4% (w/w) NSAS and 2% (w/w) stigmastanol groups were significantly less from the control animals. In conclusion, in this study, the effectiveness of chronic administration of protonated NSAS material in the reduction of plasma cholesterol levels and decrease in development of atherosclerotic lesions was demonstrated in Apo-E deficient mice model. PMID:19638223

Protonated nanostructured aluminosilicate (NSAS) reduces plasma cholesterol concentrations and atherosclerotic lesions in Apolipoprotein E deficient mice fed a high cholesterol and high fat diet.

PubMed

Sivak, Olena; Darlington, Jerry; Gershkovich, Pavel; Constantinides, Panayiotis P; Wasan, Kishor M

2009-07-28

The aim of this work was to assess the effect of chronic administration of protonated nanostructured aluminosilicate (NSAS) on the plasma cholesterol levels and development of atherosclerotic lesions in Apolipoprotein (ApoE) deficient mice fed a high cholesterol and high fat diet. Apolipoprotein E (ApoE) deficient mice were divided into the following treatment groups: protonated NSAS 1.4% (w/w), untreated control and 2% (w/w) stigmastanol mixed with high-cholesterol/high-fat diet. Animals were treated for 12 weeks, blood samples were withdrawn every 4 weeks for determination of plasma cholesterol and triglyceride levels. At the end of the study the aortic roots were harvested for assessment of atherosclerotic lesions. NSAS at 1.4% (w/w) and stigmastanol at 2% (w/w) treatment groups showed significant decreases in plasma cholesterol concentrations at all time points relative to the control animals. The lesion sum area in 1.4% (w/w) NSAS and 2% (w/w) stigmastanol groups were significantly less from the control animals. In conclusion, in this study, the effectiveness of chronic administration of protonated NSAS material in the reduction of plasma cholesterol levels and decrease in development of atherosclerotic lesions was demonstrated in Apo-E deficient mice model.

Palm oil: biochemical, physiological, nutritional, hematological, and toxicological aspects: a review.

PubMed

Edem, D O

2002-01-01

The link between dietary fats and cardiovascular diseases has necessitated a growing research interest in palm oil, the second largest consumed vegetable oil in the world. Palm oil, obtained from a tropical plant, Elaeis guineensis contains 50% saturated fatty acids, yet it does not promote atherosclerosis and arterial thrombosis. The saturated fatty acid to unsaturated fatty acid ratio of palm oil is close to unity and it contains a high amount of the antioxidants, beta-carotene, and vitamin E. Although palm oil-based diets induce a higher blood cholesterol level than do corn, soybean, safflower seed, and sunflower oils, the consumption of palm oil causes the endogenous cholesterol level to drop. This phenomenon seems to arise from the presence of the tocotrienols and the peculiar isomeric position of its fatty acids. The benefits of palm oil to health include reduction in risk of arterial thrombosis and atherosclerosis, inhibition of endogenous cholesterol biosynthesis, platelet aggregation, and reduction in blood pressure. Palm oil has been used in the fresh state and/or at various levels of oxidation. Oxidation is a result of processing the oil for various culinary purposes. However, a considerable amount of the commonly used palm oil is in the oxidized state, which poses potential dangers to the biochemical and physiological functions of the body. Unlike fresh palm oil, oxidized palm oil induces an adverse lipid profile, reproductive toxicity and toxicity of the kidney, lung, liver, and heart. This may be as a result of the generation of toxicants brought on by oxidation. In contrast to oxidized palm oil, red or refined palm oil at moderate levels in the diet of experimental animals promotes efficient utilization of nutrients, favorable body weight gains, induction of hepatic drug metabolizing enzymes, adequate hemoglobinization of red cells and improvement of immune function. Howerer, high palm oil levels in the diet induce toxicity to the liver as shown by loss of cellular radial architecture and cell size reductions which are corroborated by alanine transaminase to asparate transaminase ratios which are higher than unity. The consumtion of moderate amounts of palm oil and reduction in the level of oxidation may reduce the health risk believed to be associated with the consumption of palm oil. Red palm oil, by virtue of its beta-carotene content, may protect against vitamin A deficiency and certain forms of cancer.

Serum cholesterol reduction by feeding a high-cholesterol diet containing a lower-molecular-weight polyphenol fraction from peanut skin.

PubMed

Tamura, Tomoko; Inoue, Naoko; Shimizu-Ibuka, Akiko; Tadaishi, Miki; Takita, Toshichika; Arai, Soichi; Mura, Kiyoshi

2012-01-01

Feeding a high-cholesterol diet with a water-soluble peanut skin polyphenol fraction to rats reduced their plasma cholesterol level, with an increase in fecal cholesterol excretion. The hypocholesterolemic effect was greater with the lower-molecular-weight rather than higher-molecular-weight polyphenol fraction. This effect was possibly due to some oligomeric polyphenols which reduced the solubility of dietary cholesterol in intestinal bile acid-emulsified micelles.

The effect of ghee (clarified butter) on serum lipid levels and microsomal lipid peroxidation.

PubMed

Sharma, Hari; Zhang, Xiaoying; Dwivedi, Chandradhar

2010-04-01

Ghee, also known as clarified butter, has been utilized for thousands of years in Ayurveda as a therapeutic agent. In ancient India, ghee was the preferred cooking oil. In the last several decades, ghee has been implicated in the increased prevalence of coronary artery disease (CAD) in Asian Indians due to its content of saturated fatty acids and cholesterol and, in heated ghee, cholesterol oxidation products. Our previous research on Sprague-Dawley outbred rats, which serve as a model for the general population, showed no effect of 5 and 10% ghee-supplemented diets on serum cholesterol and triglycerides. However, in Fischer inbred rats, which serve as a model for genetic predisposition to diseases, results of our previous research showed an increase in serum total cholesterol and triglyceride levels when fed a 10% ghee-supplemented diet. In the present study, we investigated the effect of 10% dietary ghee on microsomal lipid peroxidation, as well as serum lipid levels in Fischer inbred rats to assess the effect of ghee on free radical mediated processes that are implicated in many chronic diseases including cardiovascular disease. Results showed that 10% dietary ghee fed for 4 weeks did not have any significant effect on levels of serum total cholesterol, but did increase triglyceride levels in Fischer inbred rats. Ghee at a level of 10% in the diet did not increase liver microsomal lipid peroxidation or liver microsomal lipid peroxide levels. Animal studies have demonstrated many beneficial effects of ghee, including dose-dependent decreases in serum total cholesterol, low density lipoprotein (LDL), very low density lipoprotein (VLDL), and triglycerides; decreased liver total cholesterol, triglycerides, and cholesterol esters; and a lower level of nonenzymatic-induced lipid peroxidation in liver homogenate. Similar results were seen with heated (oxidized) ghee which contains cholesterol oxidation products. A preliminary clinical study showed that high doses of medicated ghee decreased serum cholesterol, triglycerides, phospholipids, and cholesterol esters in psoriasis patients. A study on a rural population in India revealed a significantly lower prevalence of coronary heart disease in men who consumed higher amounts of ghee. Research on Maharishi Amrit Kalash-4 (MAK-4), an Ayurvedic herbal mixture containing ghee, showed no effect on levels of serum cholesterol, high density lipoprotein (HDL), LDL, or triglycerides in hyperlipidemic patients who ingested MAK-4 for 18 weeks. MAK-4 inhibited the oxidation of LDL in these patients. The data available in the literature do not support a conclusion of harmful effects of the moderate consumption of ghee in the general population. Factors that may be involved in the rise of CAD in Asian Indians include the increased use of vanaspati (vegetable ghee) which contains 40% trans fatty acids, psychosocial stress, insulin resistance, and altered dietary patterns. Research findings in the literature support the beneficial effects of ghee outlined in the ancient Ayurvedic texts and the therapeutic use of ghee for thousands of years in the Ayurvedic system of medicine.

Serum levels of lipoprotein(a) and homocysteine in patients on hemodialysis who take hydroxymethylglutaryl-CoA reductase inhibitors, vitamin B6, and folic acid.

PubMed

Shojaei, Mir Hatef; Djalali, Mamhmoud; Siassi, Fereydoun; Khatami, Mohammad Reza; Boroumand, Mohammad Ali; Eshragian, Mohammad Reza

2009-07-01

High serum levels of lipoprotein(a) and homocysteine are risk factors of cardiovascular disease which are prevalent in patients on hemodialysis. Controversy exists about the effects of hydroxymethylglutaryl-CoA reductase inhibitors on serum lipoprotein(a) levels in patients on hemodialysis. Also, deficiency of some water soluble vitamins and administration of statins may raise serum levels of homocysteine in these patients. This study was designed to investigate serum levels of lipoprotein(a) and homocysteine in patients on hemodialysis who were taking a statin, vitamin B6, and folic acid. We investigated on 152 patients with maintenance hemodialysis who were taking atorvastatin or lovastatin, vitamin B6, and folic acid for at least 6 months. Their serum levels were obtained to measure lipoprotein(a) and homocysteine levels, as well as triglyceride, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. The mean serum values of total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol and triglyceride were significantly less than the maximum reference values (P < .001). The mean serum level of lipoprotein(a) was also less than the reference value (P = .009), but homocysteine level was 33% higher on average than the reference value (P < .001). Our study demonstrated that in our patients on hemodialysis, the mean serum level of homocysteine was about 30% higher than the reference value although they were receiving vitamin B6 and folic acid. Hence, they were still exposed to the risk of cardiovascular disease.

Microsomal triglyceride transfer protein -164 T > C gene polymorphism and risk of cardiovascular disease: results from the EPIC-Potsdam case-cohort study.

PubMed

di Giuseppe, Romina; Pechlivanis, Sonali; Fisher, Eva; Arregui, Maria; Weikert, Beate; Knüppel, Sven; Buijsse, Brian; Fritsche, Andreas; Willich, Stefan N; Joost, Hans-Georg; Boeing, Heiner; Moebus, Susanne; Weikert, Cornelia

2013-01-29

The microsomal triglyceride transfer protein (MTTP) is encoded by the MTTP gene that is regulated by cholesterol in humans. Previous studies investigating the effect of MTTP on ischemic heart disease have produced inconsistent results. Therefore, we have tested the hypothesis that the rare allele of the -164T > C polymorphism in MTTP alters the risk of cardiovascular disease (CVD), depending on the cholesterol levels. The -164T > C polymorphism was genotyped in a case-cohort study (193 incident myocardial infarction (MI) and 131 incident ischemic stroke (IS) cases and 1 978 non-cases) nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study, comprising 27 548 middle-aged subjects. The Heinz Nixdorf Recall study (30 CVD cases and 1 188 controls) was used to replicate our findings. Genotype frequencies were not different between CVD and CVD free subjects (P = 0.79). We observed an interaction between the -164T > C polymorphism and total cholesterol levels in relation to future CVD. Corresponding stratified analyses showed a significant increased risk of CVD (HR(additve) = 1.38, 95% CI: 1.07 to 1.78) for individuals with cholesterol levels <200 mg/dL in the EPIC-Potsdam study. HR(additive) was 1.06, 95% CI: 0.33 to 3.40 for individuals in the Heinz Nixdorf Recall study. A borderline significant decrease in CVD risk was observed in subjects with cholesterol levels ≥ 200 mg/dL (HR(additve) = 0.77, 95% CI: 0.58 to 1.03) in the EPIC-Potsdam study. A similar trend was observed in the independent cohort (HR(additve) = 0.60, 95% CI: 0.29 to 1.25). Our study suggests an interaction between MTTP -164T > C functional polymorphism with total cholesterol levels. Thereby risk allele carriers with low cholesterol levels may be predisposed to an increased risk of developing CVD, which seems to be abolished among risk allele carriers with high cholesterol levels.

The effect of simvastatin, aspirin, and their combination in reduction of atheroma plaque

NASA Astrophysics Data System (ADS)

Kurniati, Neng Fisheri; Permatasari, Anita

2015-09-01

Atherosclerosis is one of the risk factors of cardiovascular disease. Atherosclerosis is a chronic inflammatory disease caused by high level of cholesterol especially low density lipoprotein (LDL) and accumulation of neutrophil and macrophage in the artery wall. Thickness of aortic wall is an early stage of atherosclerosis plaque formation. Identification of atherosclerosis plaque formation was done by measuring level of total cholesterol, triglycerides, HDL, LDL, interleukin-18 (IL-18), myeloperoxidase (MPO) and measuring the thickness of aortic wall. Atherosclerosis's model induced by high fat diet and CCT (cholesterol, cholic acid, and propyltiouracil) oral administration. Rats induced cholesterol divided into positive control, simvastatin 25 mg/kg bw, aspirin 20 mg/kg bw, and combination simvastatin 25 mg/kg and aspirin 20 mg/kg bw group for 3 weeks. In the third week, therapy was given to atherosclerosis's model. Then, in the fourth and fifth week, therapy was given but induction of high cholesterol was stopped due to the massive loss of body weight. Total cholesterol, triglycerides, HDL, LDL, MPO, and IL-18 measured by uv-vis spectrophotometry and ELISA. In the end of therapy, aorta's rats was isolated to identify the thickness of aorta wall. In the fourth week, after 1 week of treatment, only combination group showed significantly higher total cholesterol, LDL and MPO compared to positive control group. Level of triglycerides and HDL in all groups did not significantly differ compared to positive control group. After 2 weeks continuing drug treatment, the level of total cholesterol, MPO, and IL-18 were decreased in all groups, and aspirin group showed the lowest level. The level of triglycerides was decreased in simvastatin and aspirin group, and aspirin group showed the lowest. Only combination group showed the lowest level of LDL. Based on histopathology result, the thickness of aortic wall was reduced in all groups and aspirin group showed the lowest.

MicroRNA-19b promotes macrophage cholesterol accumulation and aortic atherosclerosis by targeting ATP-binding cassette transporter A1.

PubMed

Lv, Yun-Cheng; Tang, Yan-Yan; Peng, Juan; Zhao, Guo-Jun; Yang, Jing; Yao, Feng; Ouyang, Xin-Ping; He, Ping-Ping; Xie, Wei; Tan, Yu-Lin; Zhang, Min; Liu, Dan; Tang, Deng-Pei; Cayabyab, Francisco S; Zheng, Xi-Long; Zhang, Da-Wei; Tian, Guo-Ping; Tang, Chao-Ke

2014-09-01

Macrophage accumulation of cholesterol leads to foam cell formation which is a major pathological event of atherosclerosis. Recent studies have shown that microRNA (miR)-19b might play an important role in cholesterol metabolism and atherosclerotic diseases. Here, we have identified miR-19b binding to the 3'UTR of ATP-binding cassette transporter A1 (ABCA1) transporters, and further determined the potential roles of this novel interaction in atherogenesis. To investigate the molecular mechanisms involved in a miR-19b promotion of macrophage cholesterol accumulation and the development of aortic atherosclerosis. We performed bioinformatics analysis using online websites, and found that miR-19b was highly conserved during evolution and directly bound to ABCA1 mRNA with very low binding free energy. Luciferase reporter assay confirmed that miR-19b bound to 3110-3116 sites within ABCA1 3'UTR. MiR-19b directly regulated the expression levels of endogenous ABCA1 in foam cells derived from human THP-1 macrophages and mouse peritoneal macrophages (MPMs) as determined by qRT-PCR and western blot. Cholesterol transport assays revealed that miR-19b dramatically suppressed apolipoprotein AI-mediated ABCA1-dependent cholesterol efflux, resulting in the increased levels of total cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE) as revealed by HPLC. The excretion of (3)H-cholesterol originating from cholesterol-laden MPMs into feces was decreased in mice overexpressing miR-19b. Finally, we evaluated the proatherosclerotic role of miR-19b in apolipoprotein E deficient (apoE(-/-)) mice. Treatment with miR-19b precursor reduced plasma high-density lipoprotein (HDL) levels, but increased plasma low-density lipoprotein (LDL) levels. Consistently, miR-19b precursor treatment increased aortic plaque size and lipid content, but reduced collagen content and ABCA1 expression. In contrast, treatment with the inhibitory miR-19b antisense oligonucleotides (ASO) prevented or reversed these effects. MiR-19b promotes macrophage cholesterol accumulation, foam cell formation and aortic atherosclerotic development by targeting ABCA1. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Effect of VCO and olive oil on HDL, LDL, and cholesterol level of hyperglycemic Rattus Rattus Norvegicus

NASA Astrophysics Data System (ADS)

Yusuf Wachidah Yuiwarti, Enny; Rini Saraswati, Tyas; Kusdiyantini, Endang

2018-05-01

Virgin coconut oil (VCO) and olive oil are edible oil containing an antioxidant that can prevent free radicals in Rattus rattus norvegicus hypoglycemic due to the damage of pancreatic beta cell after alloxan injection. Virgin coconut oil and olive oil are fatty acids when being consumed will affect lipid metabolism particularly HDL, LDL and cholesterol in serum. This research aims to determine the effect of VCO and Olive oil on cholesterol levels in hyperglycemic rats. Research materials were twenty male Rattus rattus norvegicus. Randomized Factorial Design was used in four treatment groups including P1(control), P2 (mice injected with alloxan), P3 (mice injected with alloxan plus 0.1 ml/BW of each VCO and vitamin E) and P4 (mice injected with alloxan plus 0.1 ml/BW of each olive oil and vitamin E. Each treatment was replicated 5 times. Feed and water were provided adlibitum for four weeks. The result showed that there was no significant difference in the level of HDL serum across the treatments, but P4 had a significantly higher LDL than the other treatments. Moreover, total cholesterol was significantly increased in P4 compared to the other groups. It can be concluded that olive oil could increase the level of cholesterol and LDL in serum, while VCO did not increase the level of cholesterol and LDL so VCO more potential to maintain cholesterol in hyperglycemic Rattus rattus norvegicus.

Cholesterol, APOE genotype, and Alzheimer disease: an epidemiologic study of Nigerian Yoruba.

PubMed

Hall, K; Murrell, J; Ogunniyi, A; Deeg, M; Baiyewu, O; Gao, S; Gureje, O; Dickens, J; Evans, R; Smith-Gamble, V; Unverzagt, F W; Shen, J; Hendrie, H

2006-01-24

To examine the relationship between cholesterol and other lipids, APOE genotype, and risk of Alzheimer disease (AD) in a population-based study of elderly Yoruba living in Ibadan, Nigeria. Blood samples and clinical data were collected from Yoruba study participants aged 70 years and older (N = 1,075) as part of the Indianapolis-Ibadan Dementia Project, a longitudinal epidemiologic study of AD. Cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride levels were measured in fasting blood samples. DNA was extracted and APOE was genotyped. Diagnoses of AD were made by consensus using National Institute of Neurologic Disorders/Stroke-Alzheimer's Disease and Related Disorders Association criteria. Logistic regression models showed interaction after adjusting for age and gender between APOE-epsilon4 genotype and biomarkers in the risk of AD cholesterol*genotype (p = 0.022), LDL*genotype (p= 0.018), and triglyceride*genotype (p = 0.036). Increasing levels of cholesterol and LDL were associated with increased risk of AD in individuals without the APOE-epsilon4 allele, but not in those with APOE-epsilon4. There was no significant association between levels of triglycerides and AD risk in those without APOE-epsilon4. There was a significant interaction between cholesterol, APOE-epsilon4, and the risk of Alzheimer disease (AD) in the Yoruba, a population that has lower cholesterol levels and lower incidence rates of AD compared to African Americans. APOE status needs to be considered when assessing the relationship between lipid levels and AD risk in population studies.

Cholesterol, APOE genotype, and Alzheimer disease

PubMed Central

Hall, K.; Murrell, J.; Ogunniyi, A.; Deeg, M.; Baiyewu, O.; Gao, S.; Gureje, O.; Dickens, J.; Evans, R.; Smith-Gamble, V.; Unverzagt, F.W.; Shen, J.; Hendrie, H.

2010-01-01

Objective To examine the relationship between cholesterol and other lipids, APOE genotype, and risk of Alzheimer disease (AD) in a population-based study of elderly Yoruba living in Ibadan, Nigeria. Methods Blood samples and clinical data were collected from Yoruba study participants aged 70 years and older (N = 1,075) as part of the Indianapolis-Ibadan Dementia Project, a longitudinal epidemiologic study of AD. Cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglyceride levels were measured in fasting blood samples. DNA was extracted and APOE was genotyped. Diagnoses of AD were made by consensus using National Institute of Neurologic Disorders/Stroke-Alzheimer's Disease and Related Disorders Association criteria. Results Logistic regression models showed interaction after adjusting for age and gender between APOE-ε4 genotype and biomarkers in the risk of AD cholesterol*genotype (p = 0.022), LDL*genotype (p = 0.018), and triglyceride*genotype (p = 0.036). Increasing levels of cholesterol and LDL were associated with increased risk of AD in individuals without the APOE-ε4 allele, but not in those with APOE-ε4. There was no significant association between levels of triglycerides and AD risk in those without APOE-ε4. Conclusions There was a significant interaction between cholesterol, APOE-ε4, and the risk of Alzheimer disease (AD) in the Yoruba, a population that has lower cholesterol levels and lower incidence rates of AD compared to African Americans. APOE status needs to be considered when assessing the relationship between lipid levels and AD risk in population studies. PMID:16434658

Anti-TNFα therapy transiently improves high density lipoprotein cholesterol levels and microvascular endothelial function in patients with rheumatoid arthritis: a Pilot Study

PubMed Central

2012-01-01

Background Rheumatoid arthritis (RA) is associated with increased morbidity and mortality from cardiovascular disease (CVD). This can be only partially attributed to traditional CVD risk factors such as dyslipidaemia and their downstream effects on endothelial function. The most common lipid abnormality in RA is reduced levels of high-density lipoprotein (HDL) cholesterol, probably due to active inflammation. In this longitudinal study we hypothesised that anti-tumor necrosis factor-α (anti-TNFα) therapy in patients with active RA improves HDL cholesterol, microvascular and macrovascular endothelial function. Methods Twenty-three RA patients starting on anti-TNFα treatment were assessed for HDL cholesterol level, and endothelial-dependent and -independent function of microvessels and macrovessels at baseline, 2-weeks and 3 months of treatment. Results Disease activity (CRP, fibrinogen, DAS28) significantly decreased during the follow-up period. There was an increase in HDL cholesterol levels at 2 weeks (p < 0.05) which was paralleled by a significant increase in microvascular endothelial-dependent function (p < 0.05). However, both parameters returned towards baseline at 12 weeks. Conclusion Anti-TNFα therapy in RA patients appears to be accompanied by transient but significant improvements in HDL cholesterol levels, which coexists with an improvement in microvascular endothelial-dependent function. PMID:22824166

Dietary fish oil stimulates hepatic low density lipoprotein transport in the rat.

PubMed Central

Ventura, M A; Woollett, L A; Spady, D K

1989-01-01

These studies were undertaken to examine the effect of fish oil, safflower oil, and hydrogenated coconut oil on the major processes that determine the concentration of low density lipoprotein (LDL) in plasma, i.e., the rate of LDL production and the rates of receptor-dependent and receptor-independent LDL uptake in the various organs of the body. When fed at the 20% level, fish oil reduced plasma LDL-cholesterol levels by 38% primarily by increasing LDL receptor activity in the liver. Dietary safflower oil also increased hepatic LDL receptor activity; however, since the rate of LDL production also increased, plasma LDL-cholesterol levels remained essentially unchanged. Hydrogenated coconut oil had no effect on LDL receptor activity but increased the rate of LDL-cholesterol production causing plasma LDL-cholesterol levels to increase 46%. Dietary fish oil had no effect on the receptor-dependent transport of asialofetuin by the liver, suggesting that the effect of fish oil on hepatic LDL receptor activity was specific and not due to a generalized alteration in the physical properties of hepatic membranes. Finally, dietary fish oil increased hepatic cholesteryl ester levels and suppressed hepatic cholesterol synthesis rates, suggesting that the up-regulation of hepatic LDL receptor activity in these animals was not simply a response to diminished cholesterol availability in the liver. PMID:2760200