Intestinal ABCA1 directly contributes to HDL biogenesis in vivo

PubMed Central

Brunham, Liam R.; Kruit, Janine K.; Iqbal, Jahangir; Fievet, Catherine; Timmins, Jenelle M.; Pape, Terry D.; Coburn, Bryan A.; Bissada, Nagat; Staels, Bart; Groen, Albert K.; Hussain, M. Mahmood; Parks, John S.; Kuipers, Folkert; Hayden, Michael R.

2006-01-01

Plasma HDL cholesterol levels are inversely related to risk for atherosclerosis. The ATP-binding cassette, subfamily A, member 1 (ABCA1) mediates the rate-controlling step in HDL particle formation, the assembly of free cholesterol and phospholipids with apoA-I. ABCA1 is expressed in many tissues; however, the physiological functions of ABCA1 in specific tissues and organs are still elusive. The liver is known to be the major source of plasma HDL, but it is likely that there are other important sites of HDL biogenesis. To assess the contribution of intestinal ABCA1 to plasma HDL levels in vivo, we generated mice that specifically lack ABCA1 in the intestine. Our results indicate that approximately 30% of the steady-state plasma HDL pool is contributed by intestinal ABCA1 in mice. In addition, our data suggest that HDL derived from intestinal ABCA1 is secreted directly into the circulation and that HDL in lymph is predominantly derived from the plasma compartment. These data establish a critical role for intestinal ABCA1 in plasma HDL biogenesis in vivo. PMID:16543947

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.

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.

IL-8 negatively regulates ABCA1 expression and cholesterol efflux via upregulating miR-183 in THP-1 macrophage-derived foam cells.

PubMed

Tang, Xiao-Er; Li, Heng; Chen, Ling-Yan; Xia, Xiao-Dan; Zhao, Zhen-Wang; Zheng, Xi-Long; Zhao, Guo-Jun; Tang, Chao-Ke

2018-04-24

Previous studies suggest that IL-8 has an important role in the regulation of cholesterol efflux, but whether miRNAs are involved in this process is still unknown. The purpose of this study is to explore whether IL-8 promotes cholesterol accumulation by enhancing miR-183 expression in macrophages and its underlying mechanism. Treatment of THP-1 macrophage-derived foam cells with IL-8 decreased ABCA1 expression and cholesterol efflux. Using bioinformatics analyses and dual-luciferase reporter assays, we found that miR-183 was highly conserved during evolution and directly inhibited ABCA1 protein and mRNA expression by targeting ABCA1 3'UTR. MiR-183 directly regulated endogenous ABCA1 expression levels. Furthermore, IL-8 enhanced the expression of miR-183 and decrease ABCA1 expression. Cholesterol transport assays confirmed that IL-8 dramatically inhibited apolipoprotein AI-mediated ABCA1-dependent cholesterol efflux by increasing miR-183 expression. In contrast, treatment with anti-IL-8 antibody reversed these effects. IL-8 enhances the expression of miR-183, which then inhibits ABCA1 expression and cholesterol efflux. Our studies suggest that the IL-8-miR-183-ABCA1 axis may play an intermediary role in the development of atherosclerosis. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Inhibition of mitogen-activated protein kinase Erk1/2 promotes protein degradation of ATP binding cassette transporters A1 and G1 in CHO and HuH7 cells.

PubMed

Mulay, Vishwaroop; Wood, Peta; Manetsch, Melanie; Darabi, Masoud; Cairns, Rose; Hoque, Monira; Chan, Karen Cecilia; Reverter, Meritxell; Alvarez-Guaita, Anna; Rye, Kerry-Anne; Rentero, Carles; Heeren, Joerg; Enrich, Carlos; Grewal, Thomas

2013-01-01

Signal transduction modulates expression and activity of cholesterol transporters. We recently demonstrated that the Ras/mitogen-activated protein kinase (MAPK) signaling cascade regulates protein stability of Scavenger Receptor BI (SR-BI) through Proliferator Activator Receptor (PPARα) -dependent degradation pathways. In addition, MAPK (Mek/Erk 1/2) inhibition has been shown to influence liver X receptor (LXR) -inducible ATP Binding Cassette (ABC) transporter ABCA1 expression in macrophages. Here we investigated if Ras/MAPK signaling could alter expression and activity of ABCA1 and ABCG1 in steroidogenic and hepatic cell lines. We demonstrate that in Chinese Hamster Ovary (CHO) cells and human hepatic HuH7 cells, extracellular signal-regulated kinase 1/2 (Erk1/2) inhibition reduces PPARα-inducible ABCA1 protein levels, while ectopic expression of constitutively active H-Ras, K-Ras and MAPK/Erk kinase 1 (Mek1) increases ABCA1 protein expression, respectively. Furthermore, Mek1/2 inhibitors reduce ABCG1 protein levels in ABCG1 overexpressing CHO cells (CHO-ABCG1) and human embryonic kidney 293 (HEK293) cells treated with LXR agonist. This correlates with Mek1/2 inhibition reducing ABCG1 cell surface expression and decreasing cholesterol efflux onto High Density Lipoproteins (HDL). Real Time reverse transcriptase polymerase chain reaction (RT-PCR) and protein turnover studies reveal that Mek1/2 inhibitors do not target transcriptional regulation of ABCA1 and ABCG1, but promote ABCA1 and ABCG1 protein degradation in HuH7 and CHO cells, respectively. In line with published data from mouse macrophages, blocking Mek1/2 activity upregulates ABCA1 and ABCG1 protein levels in human THP1 macrophages, indicating opposite roles for the Ras/MAPK pathway in the regulation of ABC transporter activity in macrophages compared to steroidogenic and hepatic cell types. In summary, this study suggests that Ras/MAPK signaling modulates PPARα- and LXR-dependent protein degradation

Investigation of ABCA1 C69T polymorphism in patients with type 2 diabetes mellitus.

PubMed

Ergen, H Arzu; Zeybek, Umit; Gök, Ozlem; Karaali, Z Ermis

2012-01-01

Non insulin dependent diabetes mellitus is the most common type of diabetes. Genetic factors, lipid profiles, hypertension are potential risk factors for diabetes mellitus. Adenosine binding cassette transporter proteins 1 (ABCA1) plays a role in cholesterol metabolism, especially high density lipoprotein (HDL-cholesterol). There are multiple mechanisms by which HDL-cholesterol can be atheroprotective, it is clear that the relative activity of ABCA1 plays a major role. We aimed to investigate association of ABCA1 C69T gene polymorphism with lipid levels in Turkish type 2 diabetic patients. After isolation of DNA by ethanol precipitation we determined ABCA1 gene polymorphism by using polimerase chain reaction--restriction fragment lenght polymorphism (PCR-RFLP) method in 107 type 2 diabetic patients and 50 healthy controls. We have observed that the frequency of TT genotype is significantly higher in healthy controls compared to patients (14% vs. 3%; P = 0.008). Also frequency of T allele was higher in controls than in patients (34% vs. 21%; P = 0.020; OR (95% CI) = 0.52 (0.30-0.88)). There was no association of lipid levels and ABCA1 C69T polymorphism subgroups. We have found significantly higher frequency of both T allele and genotype in control group when compared to patients that made us think that T allele may be a protective factor against diabetes mellitus. But, we could not find a relationship between genotypes and lipid concentrations in our two groups. Larger studies will help us to understand the relationship between ABCA1 C69T genotype and lipid parameters in diabetes mellitus.

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

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.

Myeloid-specific genetic ablation of ATP-binding cassette transporter ABCA1 is protective against cancer

PubMed Central

Zamanian-Daryoush, Maryam; Lindner, Daniel J.; DiDonato, Joseph A.; Wagner, Matthew; Buffa, Jennifer; Rayman, Patricia; Parks, John S.; Westerterp, Marit; Tall, Alan R.; Hazen, Stanley L.

2017-01-01

Increased circulating levels of apolipoprotein A-I (apoA-I), the major protein of high-density lipoprotein (HDL), by genetic manipulation or infusion, protects against melanoma growth and metastasis. Herein, we explored potential roles in melanoma tumorigenesis for host scavenger receptor class B, type 1 (SR-B1), and ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), all mediators of apoA-I and HDL sterol and lipid transport function. In a syngeneic murine melanoma tumor model, B16F10, mice with global deletion of SR-B1 expression exhibited increased plasma HDL cholesterol (HDLc) levels and decreased tumor volume, indicating host SR-B1 does not directly contribute to HDL-associated anti-tumor activity. In mice with myeloid-specific loss of ABCA1 (Abca1−M/−M; A1−M/−M), tumor growth was inhibited by ∼4.8-fold relative to wild type (WT) animals. Abcg1−M/−M (G1−M/−M) animals were also protected by 2.5-fold relative to WT, with no further inhibition of tumor growth in Abca1/Abcg1 myeloid-specific double knockout animals (DKO). Analyses of tumor-infiltrating immune cells revealed a correlation between tumor protection and decreased presence of the immune suppressive myeloid-derived suppressor cell (MDSC) subsets, Ly-6G+Ly-6CLo and Ly-6GnegLy-6CHi cells. The growth of the syngeneic MB49 murine bladder cancer cells was also inhibited in A1−M/−M mice. Collectively, our studies provide further evidence for an immune modulatory role for cholesterol homeostasis pathways in cancer. PMID:29069761

Differential regulation of ATP binding cassette protein A1 expression and ApoA-I lipidation by Niemann-Pick type C1 in murine hepatocytes and macrophages.

PubMed

Wang, Ming-Dong; Franklin, Vivian; Sundaram, Meenakshi; Kiss, Robert S; Ho, Kenneth; Gallant, Michel; Marcel, Yves L

2007-08-03

Niemann-Pick type C1 (Npc1) protein inactivation results in lipid accumulation in late endosomes and lysosomes, leading to a defect of ATP binding cassette protein A1 (Abca1)-mediated lipid efflux to apolipoprotein A-I (apoA-I) in macrophages and fibroblasts. However, the role of Npc1 in Abca1-mediated lipid efflux to apoA-I in hepatocytes, the major cells contributing to HDL formation, is still unknown. Here we show that, whereas lipid efflux to apoA-I in Npc1-null macrophages is impaired, the lipidation of endogenously synthesized apoA-I by low density lipoprotein-derived cholesterol or de novo synthesized cholesterol or phospholipids in Npc1-null hepatocytes is significantly increased by about 1-, 3-, and 8-fold, respectively. The increased cholesterol efflux reflects a major increase of Abca1 protein in Npc1-null hepatocytes, which contrasts with the decrease observed in Npc1-null macrophages. The increased Abca1 expression is largely post-transcriptional, because Abca1 mRNA is only slightly increased and Lxr alpha mRNA is not changed, and Lxr alpha target genes are reduced. This differs from the regulation of Abcg1 expression, which is up-regulated at both mRNA and protein levels in Npc1-null cells. Abca1 protein translation rate is higher in Npc1-null hepatocytes, compared with wild type hepatocytes as measured by [(35)S]methionine incorporation, whereas there is no difference for the degradation of newly synthesized Abca1 in these two types of hepatocytes. Cathepsin D, which we recently identified as a positive modulator of Abca1, is markedly increased at both mRNA and protein levels by Npc1 inactivation in hepatocytes but not in macrophages. Consistent with this, inhibition of cathepsin D with pepstatin A reduced the Abca1 protein level in both Npc1-inactivated and WT hepatocytes. Therefore, Abca1 expression is specifically regulated in hepatocytes, where Npc1 activity modulates cathepsin D expression and Abca1 protein translation rate.

Large-scale deletions of the ABCA1 gene in patients with hypoalphalipoproteinemia.

PubMed

Dron, Jacqueline S; Wang, Jian; Berberich, Amanda J; Iacocca, Michael A; Cao, Henian; Yang, Ping; Knoll, Joan; Tremblay, Karine; Brisson, Diane; Netzer, Christian; Gouni-Berthold, Ioanna; Gaudet, Daniel; Hegele, Robert A

2018-06-04

Copy-number variations (CNVs) have been studied in the context of familial hypercholesterolemia but have not yet been evaluated in patients with extremes of high-density lipoprotein (HDL) cholesterol levels. We evaluated targeted next-generation sequencing data from patients with very low HDL cholesterol (i.e. hypoalphalipoproteinemia) using the VarSeq-CNV caller algorithm to screen for CNVs disrupting the ABCA1, LCAT or APOA1 genes. In four individuals, we found three unique deletions in ABCA1: a heterozygous deletion of exon 4, a heterozygous deletion spanning exons 8 to 31, and a heterozygous deletion of the entire ABCA1 gene. Breakpoints were identified using Sanger sequencing, and the full-gene deletion was also confirmed using exome sequencing and the Affymetrix CytoScanTM HD Array. Before now, large-scale deletions in candidate HDL genes have not been associated with hypoalphalipoproteinemia; our findings indicate that CNVs in ABCA1 may be a previously unappreciated genetic determinant of low HDL cholesterol levels. By coupling bioinformatic analyses with next-generation sequencing data, we can successfully assess the spectrum of genetic determinants of many dyslipidemias, now including hypoalphalipoproteinemia. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

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

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

Differences in ABCA1 R219K Polymorphisms and Serum Indexes in Alzheimer and Parkinson Diseases in Northern China

PubMed Central

Ya, Lagai; Lu, Zuneng

2017-01-01

Background ABCA1 R219K single-nucleotide polymorphisms (SNPs) was related to Alzheimer disease (AD) but not Parkinson disease (PD). Here, we analyzed the associations among ABCA1 R219K distribution, serum biomarkers, AD, and PD in a population in northern China. Material/Methods We used the Mini-Mental State Examination (MMSE) and the Hoehn and Yahr scale (H-Y) to evaluate AD and PD progression, separately. ABCA1 R219K was analyzed by matrix-assisted laser desorption ionization time of flight time mass spectrometry (MALDI-TOF-MS). Serum indexes were determined by enzyme-linked immunosorbent assay (ELISA). Results ABCA1 R219K RR+RK genotype frequency in AD and PD patients was lower than that in normal controls (NC), while ABCA1 R219K KK genotype frequency was significantly higher. ABCA1 R219K RR genotype frequency in AD patients and NC was lower than that in PD patients, while ABCA1 R219K RK+KK genotype frequency was significantly higher. ABCA1 R219K RR genotype was positively correlated to MMSE value in AD patients, while ABCA1 R219K KK genotype was negatively correlated to H-Y value in PD patients. Serum factors were significantly different among AD and PD patients and NC. Serum ABCA1, ApoA1, ApoA2, ApoB, HDL, TC, IL-1β, IL-6, and TNF-α were significantly different between AD and PD patients. Conclusions ABCA1 R219K R allele was the risk factor inducing abnormal serum levels of ApoA2, LDL, and TG in AD patients, and abnormal levels of serum ABCA1, HDL, IL-1β, IL-6, and TNF-α in PD patients, while ABCA1 R219K K allele was the risk factor inducing lower ABCA1 in AD patients. IL-1β, IL-6, and TNF-α were negatively correlated to MMSE in AD patients but positively correlated to H-Y in PD patients, while HDL was positively related to H-Y in PD patients. PMID:28943632

Differences in ABCA1 R219K Polymorphisms and Serum Indexes in Alzheimer and Parkinson Diseases in Northern China.

PubMed

Ya, Lagai; Lu, Zuneng

2017-09-25

BACKGROUND ABCA1 R219K single-nucleotide polymorphisms (SNPs) was related to Alzheimer disease (AD) but not Parkinson disease (PD). Here, we analyzed the associations among ABCA1 R219K distribution, serum biomarkers, AD, and PD in a population in northern China. MATERIAL AND METHODS We used the Mini-Mental State Examination (MMSE) and the Hoehn and Yahr scale (H-Y) to evaluate AD and PD progression, separately. ABCA1 R219K was analyzed by matrix-assisted laser desorption ionization time of flight time mass spectrometry (MALDI-TOF-MS). Serum indexes were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS ABCA1 R219K RR+RK genotype frequency in AD and PD patients was lower than that in normal controls (NC), while ABCA1 R219K KK genotype frequency was significantly higher. ABCA1 R219K RR genotype frequency in AD patients and NC was lower than that in PD patients, while ABCA1 R219K RK+KK genotype frequency was significantly higher. ABCA1 R219K RR genotype was positively correlated to MMSE value in AD patients, while ABCA1 R219K KK genotype was negatively correlated to H-Y value in PD patients. Serum factors were significantly different among AD and PD patients and NC. Serum ABCA1, ApoA1, ApoA2, ApoB, HDL, TC, IL-1β, IL-6, and TNF-α were significantly different between AD and PD patients. CONCLUSIONS ABCA1 R219K R allele was the risk factor inducing abnormal serum levels of ApoA2, LDL, and TG in AD patients, and abnormal levels of serum ABCA1, HDL, IL-1b, IL-6, and TNF-α in PD patients, while ABCA1 R219K K allele was the risk factor inducing lower ABCA1 in AD patients. IL-1β, IL-6, and TNF-α were negatively correlated to MMSE in AD patients but positively correlated to H-Y in PD patients, while HDL was positively related to H-Y in PD patients.

A survey of ABCA1 sequence variation confirms association with dementia

PubMed Central

Reynolds, Chandra A.; Hong, Mun-Gwan; Eriksson, Ulrika K.; Blennow, Kaj; Bennet, Anna M.; Johansson, Boo; Malmberg, Bo; Berg, Stig; Wiklund, Fredrik; Gatz, Margaret; Pedersen, Nancy L.; Prince, Jonathan A.

2009-01-01

We and others have conducted targeted genetic association analyses of ABCA1 in relation to Alzheimer disease risk with a resultant mixture of both support and refutation, but all previous studies have been based upon only a few markers. Here, a detailed survey of genetic variation in the ABCA1 region has been performed in a total of 1567 Swedish dementia cases (including 1275 with Alzheimer disease) and 2203 controls, providing evidence of association with maximum significance at marker rs2230805 (OR = 1.39; 95% CI 1.23–1.57, P = 7.7 × 10−8). Haplotype-based tests confirmed association of this genomic region after excluding rs2230805, and imputation did not reveal additional markers with greater support. Significantly associating markers reside in two distinct linkage disequilibrium blocks with maxima near the promoter and in the terminal exon of a truncated ABCA1 splice-form. The putative risk allele of rs2230805 was also found to be associated with reduced cerebrospinal fluid levels of β-amyloid. The strongest evidence of association was obtained when all forms of dementia were considered together, but effect sizes were similar when only confirmed Alzheimer disease cases were assessed. Results further implicate ABCA1 in dementia, reinforcing the putative involvement of lipid transport in neurodegenerative disease. PMID:19606474

Proteomic analysis of HDL from inbred mouse strains implicates APOE associated with HDL in reduced cholesterol efflux capacity via the ABCA1 pathway[S

PubMed Central

Pamir, Nathalie; Hutchins, Patrick; Ronsein, Graziella; Vaisar, Tomas; Reardon, Catherine A.; Getz, Godfrey S.; Lusis, Aldons J.; Heinecke, Jay W.

2016-01-01

Cholesterol efflux capacity associates strongly and negatively with the incidence and prevalence of human CVD. We investigated the relationships of HDL’s size and protein cargo with its cholesterol efflux capacity using APOB-depleted serum and HDLs isolated from five inbred mouse strains with different susceptibilities to atherosclerosis. Like humans, mouse HDL carried >70 proteins linked to lipid metabolism, the acute-phase response, proteinase inhibition, and the immune system. HDL’s content of specific proteins strongly correlated with its size and cholesterol efflux capacity, suggesting that its protein cargo regulates its function. Cholesterol efflux capacity with macrophages strongly and positively correlated with retinol binding protein 4 (RBP4) and PLTP, but not APOA1. In contrast, ABCA1-specific cholesterol efflux correlated strongly with HDL’s content of APOA1, APOC3, and APOD, but not RBP4 and PLTP. Unexpectedly, APOE had a strong negative correlation with ABCA1-specific cholesterol efflux capacity. Moreover, the ABCA1-specific cholesterol efflux capacity of HDL isolated from APOE-deficient mice was significantly greater than that of HDL from wild-type mice. Our observations demonstrate that the HDL-associated APOE regulates HDL’s ABCA1-specific cholesterol efflux capacity. These findings may be clinically relevant because HDL’s APOE content associates with CVD risk and ABCA1 deficiency promotes unregulated cholesterol accumulation in human macrophages. PMID:26673204

Increase in HDL-C concentration by a dietary portfolio with soy protein and soluble fiber is associated with the presence of the ABCA1R230C variant in hyperlipidemic Mexican subjects.

PubMed

Guevara-Cruz, Martha; Tovar, Armando R; Larrieta, Elena; Canizales-Quinteros, Samuel; Torres, Nimbe

2010-01-01

A dietary portfolio has been used to reduce blood lipids in hyperlipidemic subjects. To increase the effectiveness of these dietary treatments in specific populations, it is important to study the genetic variability associated with the development of certain types of hyperlipidemias. Low plasma high-density lipoprotein cholesterol (HDL-C) levels are the most common dyslipidemia in Mexican adults and are coupled with the presence of the ABCA1 R230C genotype. Therefore, the aim of this study was to assess the response of HDL-C concentration to a dietary portfolio in a group of Mexican hyperlipidemic subjects with ABCA1R230C (rs9282541) and R219K (rs2230806) polymorphisms. Forty-three hyperlipidemic subjects (20 men and 23 women) were given a low saturated fat (LSF) diet for one month, followed by a LSF diet that included 25g of soy protein and 15g of soluble fiber daily for 2months. We analyzed two ABCA1 polymorphisms and studied their association with serum lipids before and after treatment. Hyperlipidemic subjects with the ABCA1 R230C genotype showed lower HDL-C concentrations at the beginning of the study and were better responders to the dietary treatment than subjects with the ABCA1 R230R genotype (+4.6% vs. +14.6%) (p=.05). According to gender and the presence of the R230C genotype, women responded more significantly to the dietary treatment, reflected by an increase of 21.9% in HDL concentration (p=.022), than women with R230R genotype who only experienced an increase of 2.7% in HDL-C concentration. There was no association between the presence of the ABCA1 R219K variant (p=.544) and HDL concentration. Hyperlipidemic Mexican subjects with the ABCA1 R230C genotype showed lower HDL-concentrations and were better responders to dietary portfolio treatments for increasing HDL-C concentrations than subjects with the R230R genotype. Copyright © 2010 Elsevier Inc. All rights reserved.

ABCA1, ABCG1 and SR-BI: hormonal regulation in primary rat hepatocytes and human cell lines

PubMed Central

Sporstøl, Marita; Mousavi, Seyed Ali; Eskild, Winnie; Roos, Norbert; Berg, Trond

2007-01-01

Background Scavenger receptor type B class I (SR-BI), ABC transporter A1 (ABCA1) -and G1 (ABCG1) all play important roles in the reverse cholesterol transport. Reverse cholesterol transport is a mechanism whereby the body can eliminate excess cholesterol. Here, the regulation of SR-BI, ABCA1, and ABCG1 by dexamethasone (a synthetic glucocorticoid) and insulin were studied in order to gain more insight into the role of these two hormones in the cholesterol metabolism. Results By use of real time RT-PCR and Western blotting we examined the expression of our target genes. The results show that SR-BI, ABCA1 and ABCG1 mRNA expression increased in response to dexamethasone while insulin treatment reduced the expression in primary rat hepatocytes. The stimulatory effect of dexamethasone was reduced by the addition of the anti-glucocorticoid mifepristone. In HepG2 cells and THP-1 macrophages, however, the effect of dexamethasone was absent or inhibitory with no significant change in the presence of mifepristone. The latter observation may be a result of the low protein expression of glucocorticoid receptor (GR) in these cell lines. Conclusion Our results illustrates that insulin and glucocorticoids, two hormones crucial in the carbohydrate metabolism, also play an important role in the regulation of genes central in reverse cholesterol transport. We found a marked difference in mRNA expression between the primary cells and the two established cell lines when studying the effect of dexamethasone which may result from the varying expression levels of GR. PMID:17241464

ABCA1, ABCG1 and SR-BI: hormonal regulation in primary rat hepatocytes and human cell lines.

PubMed

Sporstøl, Marita; Mousavi, Seyed Ali; Eskild, Winnie; Roos, Norbert; Berg, Trond

2007-01-22

Scavenger receptor type B class I (SR-BI), ABC transporter A1 (ABCA1) -and G1 (ABCG1) all play important roles in the reverse cholesterol transport. Reverse cholesterol transport is a mechanism whereby the body can eliminate excess cholesterol. Here, the regulation of SR-BI, ABCA1, and ABCG1 by dexamethasone (a synthetic glucocorticoid) and insulin were studied in order to gain more insight into the role of these two hormones in the cholesterol metabolism. By use of real time RT-PCR and Western blotting we examined the expression of our target genes. The results show that SR-BI, ABCA1 and ABCG1 mRNA expression increased in response to dexamethasone while insulin treatment reduced the expression in primary rat hepatocytes. The stimulatory effect of dexamethasone was reduced by the addition of the anti-glucocorticoid mifepristone. In HepG2 cells and THP-1 macrophages, however, the effect of dexamethasone was absent or inhibitory with no significant change in the presence of mifepristone. The latter observation may be a result of the low protein expression of glucocorticoid receptor (GR) in these cell lines. Our results illustrates that insulin and glucocorticoids, two hormones crucial in the carbohydrate metabolism, also play an important role in the regulation of genes central in reverse cholesterol transport. We found a marked difference in mRNA expression between the primary cells and the two established cell lines when studying the effect of dexamethasone which may result from the varying expression levels of GR.

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.

ABCA Transporter Gene Expression and Poor Outcome in Epithelial Ovarian Cancer

PubMed Central

Hedditch, Ellen L.; Gao, Bo; Russell, Amanda J.; Lu, Yi; Emmanuel, Catherine; Beesley, Jonathan; Johnatty, Sharon E.; Chen, Xiaoqing; Harnett, Paul; George, Joshy; Williams, Rebekka T.; Flemming, Claudia; Lambrechts, Diether; Despierre, Evelyn; Lambrechts, Sandrina; Vergote, Ignace; Karlan, Beth; Lester, Jenny; Orsulic, Sandra; Walsh, Christine; Fasching, Peter; Beckmann, Matthias W.; Ekici, Arif B.; Hein, Alexander; Matsuo, Keitaro; Hosono, Satoyo; Nakanishi, Toru; Yatabe, Yasushi; Pejovic, Tanja; Bean, Yukie; Heitz, Florian; Harter, Philipp; du Bois, Andreas; Schwaab, Ira; Hogdall, Estrid; Kjaer, Susan K.; Jensen, Allan; Hogdall, Claus; Lundvall, Lene; Engelholm, Svend Aage; Brown, Bob; Flanagan, James; Metcalf, Michelle D; Siddiqui, Nadeem; Sellers, Thomas; Fridley, Brooke; Cunningham, Julie; Schildkraut, Joellen; Iversen, Ed; Weber, Rachel P.; Berchuck, Andrew; Goode, Ellen; Bowtell, David D.; Chenevix-Trench, Georgia; deFazio, Anna; Norris, Murray D.; MacGregor, Stuart; Haber, Michelle; Henderson, Michelle J.

2014-01-01

Background ATP-binding cassette (ABC) transporters play various roles in cancer biology and drug resistance, but their association with outcomes in serous epithelial ovarian cancer (EOC) is unknown. Methods The relationship between clinical outcomes and ABC transporter gene expression in two independent cohorts of high-grade serous EOC tumors was assessed with real-time quantitative polymerase chain reaction, analysis of expression microarray data, and immunohistochemistry. Associations between clinical outcomes and ABCA transporter gene single nucleotide polymorphisms were tested in a genome-wide association study. Impact of short interfering RNA–mediated gene suppression was determined by colony forming and migration assays. Association with survival was assessed with Kaplan–Meier analysis and log-rank tests. All statistical tests were two-sided. Results Associations with outcome were observed with ABC transporters of the “A” subfamily, but not with multidrug transporters. High-level expression of ABCA1, ABCA6, ABCA8, and ABCA9 in primary tumors was statistically significantly associated with reduced survival in serous ovarian cancer patients. Low levels of ABCA5 and the C-allele of rs536009 were associated with shorter overall survival (hazard ratio for death = 1.50; 95% confidence interval [CI] =1.26 to 1.79; P = 6.5e−6). The combined expression pattern of ABCA1, ABCA5, and either ABCA8 or ABCA9 was associated with particularly poor outcome (mean overall survival in group with adverse ABCA1, ABCA5 and ABCA9 gene expression = 33.2 months, 95% CI = 26.4 to 40.1; vs 55.3 months in the group with favorable ABCA gene expression, 95% CI = 49.8 to 60.8; P = .001), independently of tumor stage or surgical debulking status. Suppression of cholesterol transporter ABCA1 inhibited ovarian cancer cell growth and migration in vitro, and statin treatment reduced ovarian cancer cell migration. Conclusions Expression of ABCA transporters was associated with poor

ABCA transporter gene expression and poor outcome in epithelial ovarian cancer.

PubMed

Hedditch, Ellen L; Gao, Bo; Russell, Amanda J; Lu, Yi; Emmanuel, Catherine; Beesley, Jonathan; Johnatty, Sharon E; Chen, Xiaoqing; Harnett, Paul; George, Joshy; Williams, Rebekka T; Flemming, Claudia; Lambrechts, Diether; Despierre, Evelyn; Lambrechts, Sandrina; Vergote, Ignace; Karlan, Beth; Lester, Jenny; Orsulic, Sandra; Walsh, Christine; Fasching, Peter; Beckmann, Matthias W; Ekici, Arif B; Hein, Alexander; Matsuo, Keitaro; Hosono, Satoyo; Nakanishi, Toru; Yatabe, Yasushi; Pejovic, Tanja; Bean, Yukie; Heitz, Florian; Harter, Philipp; du Bois, Andreas; Schwaab, Ira; Hogdall, Estrid; Kjaer, Susan K; Jensen, Allan; Hogdall, Claus; Lundvall, Lene; Engelholm, Svend Aage; Brown, Bob; Flanagan, James; Metcalf, Michelle D; Siddiqui, Nadeem; Sellers, Thomas; Fridley, Brooke; Cunningham, Julie; Schildkraut, Joellen; Iversen, Ed; Weber, Rachel P; Berchuck, Andrew; Goode, Ellen; Bowtell, David D; Chenevix-Trench, Georgia; deFazio, Anna; Norris, Murray D; MacGregor, Stuart; Haber, Michelle; Henderson, Michelle J

2014-07-01

ATP-binding cassette (ABC) transporters play various roles in cancer biology and drug resistance, but their association with outcomes in serous epithelial ovarian cancer (EOC) is unknown. The relationship between clinical outcomes and ABC transporter gene expression in two independent cohorts of high-grade serous EOC tumors was assessed with real-time quantitative polymerase chain reaction, analysis of expression microarray data, and immunohistochemistry. Associations between clinical outcomes and ABCA transporter gene single nucleotide polymorphisms were tested in a genome-wide association study. Impact of short interfering RNA-mediated gene suppression was determined by colony forming and migration assays. Association with survival was assessed with Kaplan-Meier analysis and log-rank tests. All statistical tests were two-sided. Associations with outcome were observed with ABC transporters of the "A" subfamily, but not with multidrug transporters. High-level expression of ABCA1, ABCA6, ABCA8, and ABCA9 in primary tumors was statistically significantly associated with reduced survival in serous ovarian cancer patients. Low levels of ABCA5 and the C-allele of rs536009 were associated with shorter overall survival (hazard ratio for death = 1.50; 95% confidence interval [CI] =1.26 to 1.79; P = 6.5e-6). The combined expression pattern of ABCA1, ABCA5, and either ABCA8 or ABCA9 was associated with particularly poor outcome (mean overall survival in group with adverse ABCA1, ABCA5 and ABCA9 gene expression = 33.2 months, 95% CI = 26.4 to 40.1; vs 55.3 months in the group with favorable ABCA gene expression, 95% CI = 49.8 to 60.8; P = .001), independently of tumor stage or surgical debulking status. Suppression of cholesterol transporter ABCA1 inhibited ovarian cancer cell growth and migration in vitro, and statin treatment reduced ovarian cancer cell migration. Expression of ABCA transporters was associated with poor outcome in serous ovarian cancer, implicating lipid

ABCA1 in adipocytes regulates adipose tissue lipid content, glucose tolerance, and insulin sensitivity.

PubMed

de Haan, Willeke; Bhattacharjee, Alpana; Ruddle, Piers; Kang, Martin H; Hayden, Michael R

2014-03-01

Adipose tissue contains one of the largest reservoirs of cholesterol in the body. Adipocyte dysfunction in obesity is associated with intracellular cholesterol accumulation, and alterations in cholesterol homeostasis have been shown to alter glucose metabolism in cultured adipocytes. ABCA1 plays a major role in cholesterol efflux, suggesting a role for ABCA1 in maintaining cholesterol homeostasis in the adipocyte. However, the impact of adipocyte ABCA1 on adipose tissue function and glucose metabolism is unknown. Our aim was to determine the impact of adipocyte ABCA1 on adipocyte lipid metabolism, body weight, and glucose metabolism in vivo. To address this, we used mice lacking ABCA1 specifically in adipocytes (ABCA1(-ad/-ad)). When fed a high-fat, high-cholesterol diet, ABCA1(-ad/-ad) mice showed increased cholesterol and triglyceride stores in adipose tissue, developed enlarged fat pads, and had increased body weight. Associated with these phenotypic changes, we observed significant changes in the expression of genes involved in cholesterol and glucose homeostasis, including ldlr, abcg1, glut-4, adiponectin, and leptin. ABCA1(-ad/-ad) mice also demonstrated impaired glucose tolerance, lower insulin sensitivity, and decreased insulin secretion. We conclude that ABCA1 in adipocytes influences adipocyte lipid metabolism, body weight, and whole-body glucose homeostasis.

Lactobacillus acidophilus K301 Inhibits Atherogenesis via Induction of 24 (S), 25-Epoxycholesterol-Mediated ABCA1 and ABCG1 Production and Cholesterol Efflux in Macrophages

PubMed Central

Kim, Hye Sun; Park, Woo Jung; Kim, Joo-Yun; Chung, Dae Kyun

2016-01-01

Lactobacillus acidophilus species are well-known probiotics with the beneficial activity of regulating cholesterol levels. In this study, we showed that L. acidophilus K301 reduced the level of cholesterol through reverse transport in macrophages. L. acidophilus K301 upregulated the mRNA and protein levels of genes such as ATP-binding cassette A1 (ABCA1) and ATP-binding cassette G1 (ABCG1) under the control of liver X receptor (LXR), resulting in increased apoA-I-dependent cholesterol efflux in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells. L. acidophilus K301 induced both ABCA1 and ABCG1 through the endogenous LXR agonist 24(S), 25-epoxcycholesterol, which is synthesized by intracellular cholesterol synthetic pathways. In vivo studies using L. acidophilus K301-treated ApoE-/- mice showed reduced accumulation of lipoproteins in the arterial lumen. The inhibitory effects of L. acidophilus K301 on accumulation of lipoprotein in atherosclerotic plaques were mediated by the induction of squalene reductase (SQLE) and oxidosqualene cyclase (OSC) and resulted in ABCA1-mediated cholesterol efflux. Taken together, our findings revealed that Lactobacillus acidophilus K301 regulates the expression of genes related to cholesterol reverse transport via the induction of endogenous LXR agonist, suggesting the therapeutic potential of Lactobacillus acidophilus K301 as an anti-atherosclerotic agent. PMID:27120199

Lactobacillus acidophilus K301 Inhibits Atherogenesis via Induction of 24 (S), 25-Epoxycholesterol-Mediated ABCA1 and ABCG1 Production and Cholesterol Efflux in Macrophages.

PubMed

Hong, Yi-Fan; Kim, Hangeun; Kim, Hye Sun; Park, Woo Jung; Kim, Joo-Yun; Chung, Dae Kyun

2016-01-01

Lactobacillus acidophilus species are well-known probiotics with the beneficial activity of regulating cholesterol levels. In this study, we showed that L. acidophilus K301 reduced the level of cholesterol through reverse transport in macrophages. L. acidophilus K301 upregulated the mRNA and protein levels of genes such as ATP-binding cassette A1 (ABCA1) and ATP-binding cassette G1 (ABCG1) under the control of liver X receptor (LXR), resulting in increased apoA-I-dependent cholesterol efflux in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 cells. L. acidophilus K301 induced both ABCA1 and ABCG1 through the endogenous LXR agonist 24(S), 25-epoxcycholesterol, which is synthesized by intracellular cholesterol synthetic pathways. In vivo studies using L. acidophilus K301-treated ApoE-/- mice showed reduced accumulation of lipoproteins in the arterial lumen. The inhibitory effects of L. acidophilus K301 on accumulation of lipoprotein in atherosclerotic plaques were mediated by the induction of squalene reductase (SQLE) and oxidosqualene cyclase (OSC) and resulted in ABCA1-mediated cholesterol efflux. Taken together, our findings revealed that Lactobacillus acidophilus K301 regulates the expression of genes related to cholesterol reverse transport via the induction of endogenous LXR agonist, suggesting the therapeutic potential of Lactobacillus acidophilus K301 as an anti-atherosclerotic agent.

Retinoid Binding Properties of Nucleotide Binding Domain 1 of the Stargardt Disease-associated ATP Binding Cassette (ABC) Transporter, ABCA4*

PubMed Central

Biswas-Fiss, Esther E.; Affet, Stephanie; Ha, Malissa; Biswas, Subhasis B.

2012-01-01

The retina-specific ATP binding cassette transporter, ABCA4 protein, is associated with a broad range of inherited macular degenerations, including Stargardt disease, autosomal recessive cone rod dystrophy, and fundus flavimaculatus. In order to understand its role in retinal transport in rod out segment discs, we have investigated the interactions of the soluble domains of ABCA4 with both 11-cis- and all-trans-retinal. Using fluorescence anisotropy-based binding analysis and recombinant polypeptides derived from the amino acid sequences of the four soluble domains of ABCA4, we demonstrated that the nucleotide binding domain 1 (NBD1) specifically bound 11-cis-retinal. Its affinity for all-trans-retinal was markedly reduced. Stargardt disease-associated mutations in this domain resulted in attenuation of 11-cis-retinal binding. Significant differences in 11-cis-retinal binding affinities were observed between NBD1 and other cytoplasmic and lumenal domains of ABCA4. The results suggest a possible role of ABCA4 and, in particular, the NBD1 domain in 11-cis-retinal binding. These results also correlate well with a recent report on the in vivo role of ABCA4 in 11-cis-retinal transport. PMID:23144455

Mutations in the Cholesterol Transporter Gene ABCA5 Are Associated with Excessive Hair Overgrowth

PubMed Central

DeStefano, Gina M.; Kurban, Mazen; Anyane-Yeboa, Kwame; Dall'Armi, Claudia; Di Paolo, Gilbert; Feenstra, Heather; Silverberg, Nanette; Rohena, Luis; López-Cepeda, Larissa D.; Jobanputra, Vaidehi; Fantauzzo, Katherine A.; Kiuru, Maija; Tadin-Strapps, Marija; Sobrino, Antonio; Vitebsky, Anna; Warburton, Dorothy; Levy, Brynn; Salas-Alanis, Julio C.; Christiano, Angela M.

2014-01-01

Inherited hypertrichoses are rare syndromes characterized by excessive hair growth that does not result from androgen stimulation, and are often associated with additional congenital abnormalities. In this study, we investigated the genetic defect in a case of autosomal recessive congenital generalized hypertrichosis terminalis (CGHT) (OMIM135400) using whole-exome sequencing. We identified a single base pair substitution in the 5′ donor splice site of intron 32 in the ABC lipid transporter gene ABCA5 that leads to aberrant splicing of the transcript and a decrease in protein levels throughout patient hair follicles. The homozygous recessive disruption of ABCA5 leads to reduced lysosome function, which results in an accumulation of autophagosomes, autophagosomal cargos as well as increased endolysosomal cholesterol in CGHT keratinocytes. In an unrelated sporadic case of CGHT, we identified a 1.3 Mb cryptic deletion of chr17q24.2-q24.3 encompassing ABCA5 and found that ABCA5 levels are dramatically reduced throughout patient hair follicles. Collectively, our findings support ABCA5 as a gene underlying the CGHT phenotype and suggest a novel, previously unrecognized role for this gene in regulating hair growth. PMID:24831815

ABCA1 in adipocytes regulates adipose tissue lipid content, glucose tolerance, and insulin sensitivity[S

PubMed Central

de Haan, Willeke; Bhattacharjee, Alpana; Ruddle, Piers; Kang, Martin H.; Hayden, Michael R.

2014-01-01

Adipose tissue contains one of the largest reservoirs of cholesterol in the body. Adipocyte dysfunction in obesity is associated with intracellular cholesterol accumulation, and alterations in cholesterol homeostasis have been shown to alter glucose metabolism in cultured adipocytes. ABCA1 plays a major role in cholesterol efflux, suggesting a role for ABCA1 in maintaining cholesterol homeostasis in the adipocyte. However, the impact of adipocyte ABCA1 on adipose tissue function and glucose metabolism is unknown. Our aim was to determine the impact of adipocyte ABCA1 on adipocyte lipid metabolism, body weight, and glucose metabolism in vivo. To address this, we used mice lacking ABCA1 specifically in adipocytes (ABCA1−ad/−ad). When fed a high-fat, high-cholesterol diet, ABCA1−ad/−ad mice showed increased cholesterol and triglyceride stores in adipose tissue, developed enlarged fat pads, and had increased body weight. Associated with these phenotypic changes, we observed significant changes in the expression of genes involved in cholesterol and glucose homeostasis, including ldlr, abcg1, glut-4, adiponectin, and leptin. ABCA1−ad/−ad mice also demonstrated impaired glucose tolerance, lower insulin sensitivity, and decreased insulin secretion. We conclude that ABCA1 in adipocytes influences adipocyte lipid metabolism, body weight, and whole-body glucose homeostasis. PMID:24443560

Genetic variants of ABCA1 modify Alzheimer disease risk and quantitative traits related to beta-amyloid metabolism.

PubMed

Katzov, Hagit; Chalmers, Katy; Palmgren, Juni; Andreasen, Niels; Johansson, Boo; Cairns, Nigel J; Gatz, Margaret; Wilcock, Gordon K; Love, Seth; Pedersen, Nancy L; Brookes, Anthony J; Blennow, Kaj; Kehoe, Patrick G; Prince, Jonathan A

2004-04-01

Linkage studies have provided evidence that one or more loci on chromosome 9q influence Alzheimer disease (AD). The gene encoding the ATP-binding cassette A1 transporter (ABCA1) resides within proximity of previously identified linkage peaks and represents a plausible biological candidate for AD due to its central role in cellular lipid homeostasis. Several single nucleotide polymorphisms (SNPs) spanning ABCA1 have been genotyped and haplotype-based association analyses performed in four independent case-control samples, consisting of over 1,750 individuals from three European populations representing both early and late-onset AD. Prominent effects were observed for a common (H2) and rarer haplotype (H5) that were enriched in AD cases across studied populations (odds ratio [OR] 1.59, 95% confidence interval [CI] 1.36-1.82; P<0.00001 and OR 2.90; 95% CI 2.54-3.27; P<0.00001, respectively). Two other common haplotypes in the studied region (H1 and H3) were significantly under-represented in AD cases, suggesting that they may harbor alleles that decrease disease risk (OR 0.79, 95% CI 0.64-0.94; P=0.0065 and OR 0.70, 95% CI 0.46-0.93; P=0.011, respectively). While findings were significant in both early and late-onset samples, haplotype effects were more distinct in early-onset materials. For late-onset samples, ancillary evidence was obtained that both single marker alleles and haplotypes of ABCA1 contribute to variable cerebrospinal fluid tau and beta amyloid (Abeta42) protein levels, and brain Abeta load. Results indicate that variants of ABCA1 may affect the risk of AD, providing further support for a genetic link between AD and cholesterol metabolism. Copyright 2004 Wiley-Liss, Inc.

The cholesterol transporter ABCA1 is expressed in stallion spermatozoa and reproductive tract tissues.

PubMed

Merkl, M; Ertl, R; Handschuh, S; Aurich, C; Schäfer-Somi, S

2016-04-01

strong signals in Leydig cells were present in prepubertal stallions. In prepubertal stallions, the ABCA1 messenger RNA level in testicular tissue was significantly higher than in adult stallions. We conclude that the ABCA1 transport molecule is present in adult and prepubertal stallion spermatozoa as well as testicular and epididymal tissue. ABCA1 is supposed to contribute to cholesterol transport and to support capacitation; however, this remains to be proven by functional studies. Species-specific differences concerning the localization inside the spermatozoa membrane are alike. Copyright © 2016 Elsevier Inc. All rights reserved.

Deficiency of ABCA1 and ABCG1 in Macrophages Increases Inflammation and Accelerates Atherosclerosis in Mice

PubMed Central

Westerterp, Marit; Murphy, Andrew J.; Wang, Mi; Pagler, Tamara A.; Vengrenyuk, Yuliya; Kappus, Mojdeh S.; Gorman, Darren J.; Nagareddy, Prabhakara R.; Zhu, Xuewei; Abramowicz, Sandra; Parks, John S.; Welch, Carrie; Fisher, Edward A.; Wang, Nan; Yvan-Charvet, Laurent; Tall, Alan R.

2013-01-01

Rationale Plasma HDL levels are inversely correlated with atherosclerosis. Although it is widely assumed that this is due to the ability of HDL to promote cholesterol efflux from macrophage foam cells, direct experimental support for this hypothesis is lacking. Objective To assess the role of macrophage cholesterol efflux pathways in atherogenesis. Methods and Results We developed MAC-ABCDKO mice with efficient deletion of the ATP Binding Cassette Transporters A1 and G1 (ABCA1 and ABCG1) in macrophages but not in hematopoietic stem or progenitor populations. MAC-ABCDKO bone marrow (BM) was transplanted into Ldlr-/- recipients. On the chow diet, these mice had similar plasma cholesterol and blood monocyte levels but increased atherosclerosis compared to controls. On the Western type diet (WTD), MAC-ABCDKO BM transplanted Ldlr-/- mice had disproportionate atherosclerosis, considering they also had lower VLDL/LDL cholesterol levels than controls. ABCA1/G1 deficient macrophages in lesions showed increased inflammatory gene expression. Unexpectedly, WTD-fed MAC-ABCDKO BM transplanted Ldlr-/- mice displayed monocytosis and neutrophilia in the absence of HSPC proliferation. Mechanistic studies revealed increased expression of M-CSF and G-CSF in splenic macrophage foam cells, driving BM monocyte and neutrophil production. Conclusion These studies 1) show that macrophage deficiency of ABCA1/G1 is pro-atherogenic likely by promoting plaque inflammation and 2) uncover a novel positive feedback loop in which cholesterol-laden splenic macrophages signal BM progenitors to produce monocytes, with suppression by macrophage cholesterol efflux pathways. PMID:23572498

A Mouse Model of Harlequin Ichthyosis Delineates a Key Role for Abca12 in Lipid Homeostasis

PubMed Central

Smyth, Ian; Mukhamedova, Nigora; Meikle, Peter J.; Ellis, Sarah; Slattery, Keith; Collinge, Janelle E.; de Graaf, Carolyn A.; Bahlo, Melanie; Sviridov, Dmitri

2008-01-01

Harlequin Ichthyosis (HI) is a severe and often lethal hyperkeratotic skin disease caused by mutations in the ABCA12 transport protein. In keratinocytes, ABCA12 is thought to regulate the transfer of lipids into small intracellular trafficking vesicles known as lamellar bodies. However, the nature and scope of this regulation remains unclear. As part of an original recessive mouse ENU mutagenesis screen, we have identified and characterised an animal model of HI and showed that it displays many of the hallmarks of the disease including hyperkeratosis, loss of barrier function, and defects in lipid homeostasis. We have used this model to follow disease progression in utero and present evidence that loss of Abca12 function leads to premature differentiation of basal keratinocytes. A comprehensive analysis of lipid levels in mutant epidermis demonstrated profound defects in lipid homeostasis, illustrating for the first time the extent to which Abca12 plays a pivotal role in maintaining lipid balance in the skin. To further investigate the scope of Abca12's activity, we have utilised cells from the mutant mouse to ascribe direct transport functions to the protein and, in doing so, we demonstrate activities independent of its role in lamellar body function. These cells have severely impaired lipid efflux leading to intracellular accumulation of neutral lipids. Furthermore, we identify Abca12 as a mediator of Abca1-regulated cellular cholesterol efflux, a finding that may have significant implications for other diseases of lipid metabolism and homeostasis, including atherosclerosis. PMID:18802465

Effect Of G2706A and G1051A polymorphisms of the ABCA1 gene on the lipid, oxidative stress and homocystein levels in Turkish patients with polycystıc ovary syndrome

PubMed Central

2011-01-01

Background Obesity, insulin resistance and hyperandrogenism, crucial parameters of Polycystic ovary syndrome (PCOS) play significant pathophysiological roles in lipidemic aberrations associated within the syndrome. Parts of the metabolic syndrome (low HDL and insulin resistance) appeared to facilitate the association between PCOS and coronary artery disease, independently of obesity. ABCA1 gene polymorphism may be altered this components in PCOS patients. In this study, we studied 98 PCOS patients and 93 healthy controls. All subjects underwent venous blood drawing for complete hormonal assays, lipid profile, glucose, insulin, malondialdehyde, nitric oxide, disulfide levels and ABCA genetic study. Results In PCOS group fasting glucose, DHEAS, 17-OHP, free testosterone, total-cholesterol, triglyceride, LDL-cholesterol and fibrinogen were significantly different compare to controls. The genotype ABCA G2706A distribution differed between the control group (GG 60.7%, GA 32.1%, AA 7.1%) and the PCOS patients (GG 8.7%, GA 8.7%, AA 76.8%). The frequency of the A allele (ABCAG2706A) was higher in PCOS patients than control group with 13,0% and 23,2%, respectively. In this study, the homocystein and insulin levels were significantly higher in PCOS patients with ABCA G1051A mutant genotype than those with heterozygote and wild genotypes. Conclusions We found higher percentage of AA genotype and A allele of ABCA G2706A in PCOS patients compare to controls. The fasting insulin and homocystein levels were significantly higher in PCOS patients with ABCA G1051A mutant genotype than those with heterozygote and wild genotypes. PMID:22035022

ABCA1 gene variants regulate postprandial lipid metabolism in healthy men

PubMed Central

Delgado-Lista, Javier; Perez-Martinez, Pablo; Perez-Jimenez, Francisco; Garcia-Rios, Antonio; Fuentes, Francisco; Marin, Carmen; Gómez-Luna, Purificación; Camargo, Antonio; Parnell, Laurence D; Ordovas, Jose Maria; Lopez-Miranda, Jose

2010-01-01

Objective Genetic variants of ABCA1, an ATP-binding cassette (ABC) transporter, have been linked to altered atherosclerosis progression and fasting lipid concentration, mainly high density lipoproteins (HDL) and Apolipoprotein A1 (APOA1), but results from different studies have been inconsistent. Methods and results In order to further characterize the effects of ABCA1 variants in human postprandial lipid metabolism, we studied the influence of three single nucleotide polymorphisms (SNPs) [i27943 (rs2575875); i48168 (rs4149272); R219K (rs2230806)] in the postprandial lipemia of 88 normolipidemic young men, who were given a fatty meal. For i27943 and i48168 SNPs, fasting and postprandial values of APOA1 were higher, and postprandial lipemia was much lower in homozygotes for the major alleles, for total triglycerides in plasma, and large-triglyceride rich lipoproteins (TRL) triglycerides. These persons also showed higher APOA1/APOB ratio. Major allele homozygotes for i48168 and i27943 showed additionally higher HDL and lower postprandial Apolipoprotein B (ApoB). Conclusions Our work shows that major allele homozygotes for ABCA1 SNPs i27943 and i48168 have a lower postprandial response as compared to minor allele carriers. This finding may further characterize the role of ABCA1 in lipid metabolism. PMID:20185793

Tangshen Formula Attenuates Diabetic Nephropathy by Promoting ABCA1-Mediated Renal Cholesterol Efflux in db/db Mice.

PubMed

Liu, Peng; Peng, Liang; Zhang, Haojun; Tang, Patrick Ming-Kuen; Zhao, Tingting; Yan, Meihua; Zhao, Hailing; Huang, Xiaoru; Lan, Huiyao; Li, Ping

2018-01-01

The commonly prescribed Tangshen Formula (TSF) is a traditional Chinese formulation that has been shown to reduce plasma lipid metabolism and proteinuria and improve the estimated glomerular filtration rate (eGFR) in patients with diabetic kidney disease. This study investigated the underlying mechanism whereby TSF regulates renal lipid accumulation and ameliorates diabetic renal injuries in spontaneous diabetic db/db mice and in vitro in sodium palmitate (PA)-stimulated and Abca1-SiRNA-transfected mouse tubular epithelial cells (mTECs). The results revealed that TSF treatment significantly ameliorated the renal injuries by lowering urinary albumin excretion and improving renal tissue injuries in diabetic (db/db) mice. Interestingly, the treatment with TSF also resulted in decreased cholesterol levels in the renal tissues of db/db mice, which was associated with increased expression of the peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α), the Liver X receptors (LXR), and ATP-binding cassette subfamily A member 1 (ABCA1), suggesting that TSF might attenuate diabetic kidney injury via a mechanism associated with improving cholesterol efflux in the diabetic kidney. This was investigated in vitro in mTECs, and the results showed that TSF reduced the PA-stimulated cholesterol accumulation in mTECs. Mechanistically, the addition of TSF was capable of reversing PA-induced downregulation of PGC-1α, LXR, and ABCA1 expression and cholesterol accumulation in mTECs, suggesting that TSF might act the protection via the PGC-1α-LXR-ABCA1 pathway to improve the cholesterol efflux in the renal tissues of db/db mice. This was further confirmed by silencing ABCA1 to block the promotive effect of TSF on cholesterol efflux in vitro . In conclusion, TSF might ameliorate diabetic kidney injuries by promoting ABCA1-mediated renal cholesterol efflux.

Effects of miR-33a-5P on ABCA1/G1-Mediated Cholesterol Efflux under Inflammatory Stress in THP-1 Macrophages

PubMed Central

Mao, Min; Lei, Han; Liu, Qing; Chen, Yaxi; Zhao, Lei; Li, Qing; Luo, Suxin; Zuo, Zhong; He, Quan; Huang, Wei; Zhang, Nan; Zhou, Chao; Ruan, Xiong Z.

2014-01-01

The present study is to investigate whether inflammatory cytokines inhibit ABCA1/ABCG1-mediated cholesterol efflux by regulating miR-33a-5P in THP-1 macrophages. We used interleukin-6 and tumor necrosis factor-alpha in the presence or absence of native low density lipoprotein (LDL) to stimulate THP-1 macrophages. THP-1 macrophages were infected by either control lentivirus vectors or lentivirus encoding miR-33a-5P or antisense miR-33a-5P. The effects of inflammatory cytokines, miR-33a-5P and antisense miR-33a-5P on intracellular lipids accumulation and intracellular cholesterol contents were assessed by oil red O staining and quantitative intracellular cholesterol assay. ApoA-I-mediated cholesterol efflux was examined using the fluorescent sterol (BODIPY-cholesterol). The gene and protein expressions of the molecules involved in cholesterol trafficking were examined using quantitative real-time polymerase chain reaction and Western blotting. Inflammatory cytokines or miR-33a-5P increased intracellular lipid accumulation and decreased apoA-I-mediated cholesterol efflux via decreasing the expression of ABCA1 and ABCG1 in the absence or presence of LDL in THP-1 macrophages. However, antisense miR-33a-5P reversed the effects of inflammatory cytokines on intracellular lipid accumulation, cholesterol efflux, and the expression of miR-33a-5P, ABCA1 and ABCG1 in the absence or presence of LDL in THP-1 macrophages. This study indicated that inflammatory cytokines inhibited ABCA1/ABCG1-mediated cholesterol efflux by up-regulating miR-33a-5P in THP-1 macrophages. PMID:25329888

Effects of miR-33a-5P on ABCA1/G1-mediated cholesterol efflux under inflammatory stress in THP-1 macrophages.

PubMed

Mao, Min; Lei, Han; Liu, Qing; Chen, Yaxi; Zhao, Lei; Li, Qing; Luo, Suxin; Zuo, Zhong; He, Quan; Huang, Wei; Zhang, Nan; Zhou, Chao; Ruan, Xiong Z

2014-01-01

The present study is to investigate whether inflammatory cytokines inhibit ABCA1/ABCG1-mediated cholesterol efflux by regulating miR-33a-5P in THP-1 macrophages. We used interleukin-6 and tumor necrosis factor-alpha in the presence or absence of native low density lipoprotein (LDL) to stimulate THP-1 macrophages. THP-1 macrophages were infected by either control lentivirus vectors or lentivirus encoding miR-33a-5P or antisense miR-33a-5P. The effects of inflammatory cytokines, miR-33a-5P and antisense miR-33a-5P on intracellular lipids accumulation and intracellular cholesterol contents were assessed by oil red O staining and quantitative intracellular cholesterol assay. ApoA-I-mediated cholesterol efflux was examined using the fluorescent sterol (BODIPY-cholesterol). The gene and protein expressions of the molecules involved in cholesterol trafficking were examined using quantitative real-time polymerase chain reaction and Western blotting. Inflammatory cytokines or miR-33a-5P increased intracellular lipid accumulation and decreased apoA-I-mediated cholesterol efflux via decreasing the expression of ABCA1 and ABCG1 in the absence or presence of LDL in THP-1 macrophages. However, antisense miR-33a-5P reversed the effects of inflammatory cytokines on intracellular lipid accumulation, cholesterol efflux, and the expression of miR-33a-5P, ABCA1 and ABCG1 in the absence or presence of LDL in THP-1 macrophages. This study indicated that inflammatory cytokines inhibited ABCA1/ABCG1-mediated cholesterol efflux by up-regulating miR-33a-5P in THP-1 macrophages.

Allicin induces the upregulation of ABCA1 expression via PPARγ/LXRα signaling in THP-1 macrophage-derived foam cells

PubMed Central

Lin, Xiao-Long; Hu, Hui-Jun; Liu, Yuan-Bo; Hu, Xue-Mei; Fan, Xiao-Juan; Zou, Wei-Wen; Pan, Yong-Quan; Zhou, Wen-Quan; Peng, Min-Wen; Gu, Cai-Hong

2017-01-01

Allicin is considered anti-atherosclerotic due to its antioxidant and anti-inflammatory effects, which makes it an important drug for the prevention and treatment of atherosclerosis. However, the effects of allicin on foam cells are unclear. Thus, in this study, we examined the effects of allicin on lipid accumulation via peroxisome proliferator-activated receptor γ (PPARγ)/liver X receptor α (LXRα) in THP-1 macrophage-derived foam cells. THP-1 cells were exposed to 100 nM phorbol myristate acetate (PMA) for 24 h, and then to oxydized low-density lipoprotein (ox-LDL; 50 mg/ml) to induce foam cell formation. The results of Oil Red O staining and high-performance liquid chromatography (HPLC) revealed showed that pre-treatment of the foam cells with allicin decreased total cholesterol, free cholesterol (FC) and cholesterol ester levels in cells, and also decreased lipid accumulation. Moreover, allicin upregulated ATP binding cassette transporter A1 (ABCA1) expression and promoted cholesterol efflux. However, these effects were significantly abolished by transfection with siRNA targeting ABCA1. Furthermore, PPARγ/LXRα signaling was activated by allicin treatment. The allicin-induced upregulation of ABCA1 expression was also abolished by PPARγ inhibitor (GW9662) and siRNA or LXRα siRNA co-treatment. Overall, our data demonstrate that the allicin-induced upregulation of ABCA1 promotes cholesterol efflux and reduces lipid accumulation via PPARγ/LXRα signaling in THP-1 macrophage-derived foam cells. PMID:28440421

HDL and CER-001 Inverse-Dose Dependent Inhibition of Atherosclerotic Plaque Formation in apoE-/- Mice: Evidence of ABCA1 Down-Regulation

PubMed Central

Tardy, Claudine; Goffinet, Marine; Boubekeur, Nadia; Cholez, Guy; Ackermann, Rose; Sy, Gavin; Keyserling, Constance; Lalwani, Narendra; Paolini, John F.; Dasseux, Jean-Louis; Barbaras, Ronald; Baron, Rudi

2015-01-01

Objective CER-001 is a novel engineered HDL-mimetic comprised of recombinant human apoA-I and charged phospholipids that was designed to mimic the beneficial properties of nascent pre-ß HDL. In this study, we have evaluated the dose-dependent regulation of ABCA1 expression in vitro and in vivo in the presence of CER-001 and native HDL (HDL3). Methods and Results CER-001 induced cholesterol efflux from J774 macrophages in a dose-dependent manner similar to natural HDL. A strong down-regulation of the ATP-binding cassette A1 (ABCA1) transporter mRNA (- 50%) as well as the ABCA1 membrane protein expression (- 50%) was observed at higher doses of CER-001 and HDL3 compared to non-lipidated apoA-I. In vivo, in an apoE-/- mouse “flow cessation model,” in which the left carotid artery was ligatured to induce local inflammation, the inhibition of atherosclerotic plaque burden progression in response to a dose-range of every-other-day CER-001 or HDL in the presence of a high-fat diet for two weeks was assessed. We observed a U-shaped dose-response curve: inhibition of the plaque total cholesterol content increased with increasing doses of CER-001 or HDL3 up to a maximum inhibition (- 51%) at 5 mg/kg; however, as the dose was increased above this threshold, a progressively less pronounced inhibition of progression was observed, reaching a complete absence of inhibition of progression at doses of 20 mg/kg and over. ABCA1 protein expression in the same atherosclerotic plaque was decreased by-45% and-68% at 50 mg/kg for CER-001 and HDL respectively. Conversely, a-12% and 0% decrease in ABCA1 protein expression was observed at the 5 mg/kg dose for CER-001 and HDL respectively. Conclusions These data demonstrate that high doses of HDL and CER-001 are less effective at slowing progression of atherosclerotic plaque in apoE-/- mice compared to lower doses, following a U-shaped dose-response curve. A potential mechanism for this phenomenon is supported by the observation that

HDL and CER-001 Inverse-Dose Dependent Inhibition of Atherosclerotic Plaque Formation in apoE-/- Mice: Evidence of ABCA1 Down-Regulation.

PubMed

Tardy, Claudine; Goffinet, Marine; Boubekeur, Nadia; Cholez, Guy; Ackermann, Rose; Sy, Gavin; Keyserling, Constance; Lalwani, Narendra; Paolini, John F; Dasseux, Jean-Louis; Barbaras, Ronald; Baron, Rudi

2015-01-01

CER-001 is a novel engineered HDL-mimetic comprised of recombinant human apoA-I and charged phospholipids that was designed to mimic the beneficial properties of nascent pre-ß HDL. In this study, we have evaluated the dose-dependent regulation of ABCA1 expression in vitro and in vivo in the presence of CER-001 and native HDL (HDL3). CER-001 induced cholesterol efflux from J774 macrophages in a dose-dependent manner similar to natural HDL. A strong down-regulation of the ATP-binding cassette A1 (ABCA1) transporter mRNA (- 50%) as well as the ABCA1 membrane protein expression (- 50%) was observed at higher doses of CER-001 and HDL3 compared to non-lipidated apoA-I. In vivo, in an apoE-/- mouse "flow cessation model," in which the left carotid artery was ligatured to induce local inflammation, the inhibition of atherosclerotic plaque burden progression in response to a dose-range of every-other-day CER-001 or HDL in the presence of a high-fat diet for two weeks was assessed. We observed a U-shaped dose-response curve: inhibition of the plaque total cholesterol content increased with increasing doses of CER-001 or HDL3 up to a maximum inhibition (- 51%) at 5 mg/kg; however, as the dose was increased above this threshold, a progressively less pronounced inhibition of progression was observed, reaching a complete absence of inhibition of progression at doses of 20 mg/kg and over. ABCA1 protein expression in the same atherosclerotic plaque was decreased by-45% and-68% at 50 mg/kg for CER-001 and HDL respectively. Conversely, a-12% and 0% decrease in ABCA1 protein expression was observed at the 5 mg/kg dose for CER-001 and HDL respectively. These data demonstrate that high doses of HDL and CER-001 are less effective at slowing progression of atherosclerotic plaque in apoE-/- mice compared to lower doses, following a U-shaped dose-response curve. A potential mechanism for this phenomenon is supported by the observation that high doses of HDL and CER-001 induce a rapid and

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.

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

Activation of Liver X Receptor Decreases Atherosclerosis in Ldlr−/− mice in the Absence of ABCA1 and ABCG1 in Myeloid Cells

PubMed Central

Kappus, Mojdeh S.; Murphy, Andrew J.; Abramowicz, Sandra; Ntonga, Vusisizwe; Welch, Carrie L.; Tall, Alan R.; Westerterp, Marit

2014-01-01

Objective Liver X Receptor (LXR) activators decrease atherosclerosis in mice. LXR activators (1) directly up-regulate genes involved in reverse cholesterol transport (RCT) and (2) exert anti-inflammatory effects mediated by transrepression of NFκB target genes. We investigated whether myeloid cell deficiency of ATP-binding cassette transporters A1 and G1 (ABCA1/G1), principal targets of LXR that promote macrophage cholesterol efflux and initiate RCT, would abolish the beneficial effects of LXR activation on atherosclerosis. Approach and Results LXR activator T0901317 (T0) substantially reduced inflammatory gene expression in macrophages lacking ABCA1/G1. Ldlr−/− mice were transplanted with Abca1−/−Abcg1−/− or wild-type bone marrow (BM) and fed a Western-type diet (WTD) for 6 weeks with or without T0 supplementation. Abca1/g1 BM deficiency increased atherosclerotic lesion complexity and inflammatory cell infiltration into the adventitia and myocardium. T0 markedly decreased lesion area, complexity and inflammatory cell infiltration in the Abca1−/−Abcg1−/− BM transplanted mice. To investigate whether this was due to macrophage Abca1/g1 deficiency, Ldlr−/− mice were transplanted with LysmCreAbca1fl/flAbcg1fl/fl or Abca1fl/flAbcg1fl/fl BM and fed WTD with or without the more specific LXR agonist GW3965 for 12 weeks. GW3965 decreased lesion size in both groups and the decrease was more prominent in the LysmCreAbca1fl/flAbcg1fl/fl group. Conclusions The results suggest that anti-inflammatory effects of LXR activators are of key importance to their anti-atherosclerotic effects in vivo independent of cholesterol efflux pathways mediated by macrophage ABCA1/G1. This has implications for the development of LXR activators that lack adverse effects on lipogenic genes while maintaining the ability to trans-repress inflammatory genes. PMID:24311381

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

Association studies of several cholesterol-related genes (ABCA1, CETP and LIPC) with serum lipids and risk of Alzheimer’s disease

PubMed Central

2012-01-01

Objectives Accumulating evidence suggested that dysregulation of cholesterol homeostasis might be a major etiologic factor in initiating and promoting neurodegeneration in Alzheimer’s disease (AD). ATP-binding cassette transporter A1 (ABCA1), hepatic lipase (HL, coding genes named LIPC) and cholesteryl ester transfer protein (CETP) are important components of high-density lipoprotein (HDL) metabolism and reverse cholesterol transport (RCT) implicated in atherosclerosis and neurodegenerative diseases. In the present study, we will investigate the possible association of several common polymorphisms (ABCA1R219K, CETPTaqIB and LIPC-250 G/A) with susceptibility to AD and plasma lipid levels. Methods Case–control study of 208 Han Chinese (104 AD patients and 104 non-demented controls) from Changsha area in Hunan Province was performed using the PCR-RFLP analysis. Cognitive decline was assessed using Mini Mental State Examination (MMSE) as a standardized method. Additionally, fasting lipid profile and the cognitive testing scores including Wechsler Memory Scale (WMS) and Wisconsin Card Sorting Test (WCST) were recorded. Results and conclusions We found significant differences among the genotype distributions of these three genes in AD patients when compared with controls. But after adjusting other factors, multivariate logistic regression analysis showed only ABCA1R219K (B = −0.903, P = 0.005, OR = 0.405, 95%CI:0.217-0.758) and LIPC-250 G/A variants(B = −0.905, P = 0.018, OR = 0.405, 95%CI:0.191-0.858) were associated with decreased AD risk. There were significantly higher levels of high-density lipoprotein cholesterol (HDL-C) and apolipoproteinA-I in the carriers of KK genotype and K allele (P < 0.05), and B2B2 genotype of CETP Taq1B showed significant association with higher HDL-C levels than other genotypes (F = 5.598, P = 0.004), while -250 G/A polymorphisms had no significant effect on HDL-C. In total population, subjects

A Computational Approach From Gene to Structure Analysis of the Human ABCA4 Transporter Involved in Genetic Retinal Diseases.

PubMed

Trezza, Alfonso; Bernini, Andrea; Langella, Andrea; Ascher, David B; Pires, Douglas E V; Sodi, Andrea; Passerini, Ilaria; Pelo, Elisabetta; Rizzo, Stanislao; Niccolai, Neri; Spiga, Ottavia

2017-10-01

The aim of this article is to report the investigation of the structural features of ABCA4, a protein associated with a genetic retinal disease. A new database collecting knowledge of ABCA4 structure may facilitate predictions about the possible functional consequences of gene mutations observed in clinical practice. In order to correlate structural and functional effects of the observed mutations, the structure of mouse P-glycoprotein was used as a template for homology modeling. The obtained structural information and genetic data are the basis of our relational database (ABCA4Database). Sequence variability among all ABCA4-deposited entries was calculated and reported as Shannon entropy score at the residue level. The three-dimensional model of ABCA4 structure was used to locate the spatial distribution of the observed variable regions. Our predictions from structural in silico tools were able to accurately link the functional effects of mutations to phenotype. The development of the ABCA4Database gathers all the available genetic and structural information, yielding a global view of the molecular basis of some retinal diseases. ABCA4 modeled structure provides a molecular basis on which to analyze protein sequence mutations related to genetic retinal disease in order to predict the risk of retinal disease across all possible ABCA4 mutations. Additionally, our ABCA4 predicted structure is a good starting point for the creation of a new data analysis model, appropriate for precision medicine, in order to develop a deeper knowledge network of the disease and to improve the management of patients.

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

Gene-Gene Combination Effect and Interactions among ABCA1, APOA1, SR-B1, and CETP Polymorphisms for Serum High-Density Lipoprotein-Cholesterol in the Japanese Population

PubMed Central

Nakamura, Akihiko; Niimura, Hideshi; Kuwabara, Kazuyo; Takezaki, Toshiro; Morita, Emi; Wakai, Kenji; Hamajima, Nobuyuki; Nishida, Yuichiro; Turin, Tanvir Chowdhury; Suzuki, Sadao; Ohnaka, Keizo; Uemura, Hirokazu; Ozaki, Etsuko; Hosono, Satoyo; Mikami, Haruo; Kubo, Michiaki; Tanaka, Hideo

2013-01-01

Background/Objective Gene-gene interactions in the reverse cholesterol transport system for high-density lipoprotein-cholesterol (HDL-C) are poorly understood. The present study observed gene-gene combination effect and interactions between single nucleotide polymorphisms (SNPs) in ABCA1, APOA1, SR-B1, and CETP in serum HDL-C from a cross-sectional study in the Japanese population. Methods The study population comprised 1,535 men and 1,515 women aged 35–69 years who were enrolled in the Japan Multi-Institutional Collaborative Cohort (J-MICC) Study. We selected 13 SNPs in the ABCA1, APOA1, CETP, and SR-B1 genes in the reverse cholesterol transport system. The effects of genetic and environmental factors were assessed using general linear and logistic regression models after adjusting for age, sex, and region. Principal Findings Alcohol consumption and daily activity were positively associated with HDL-C levels, whereas smoking had a negative relationship. The T allele of CETP, rs3764261, was correlated with higher HDL-C levels and had the highest coefficient (2.93 mg/dL/allele) among the 13 SNPs, which was statistically significant after applying the Bonferroni correction (p<0.001). Gene-gene combination analysis revealed that CETP rs3764261 was associated with high HDL-C levels with any combination of SNPs from ABCA1, APOA1, and SR-B1, although no gene-gene interaction was apparent. An increasing trend for serum HDL-C was also observed with an increasing number of alleles (p<0.001). Conclusions The present study identified a multiplier effect from a polymorphism in CETP with ABCA1, APOA1, and SR-B1, as well as a dose-dependence according to the number of alleles present. PMID:24376512

Retinal-specific ATP-binding cassette transporter (ABCR/ABCA4) is expressed at the choroid plexus in rat brain.

PubMed

Bhongsatiern, Jiraganya; Ohtsuki, Sumio; Tachikawa, Masanori; Hori, Satoko; Terasaki, Tetsuya

2005-03-01

ATP-binding cassette (ABC) transporter A4 is a member of the ABC transporter subfamily A which has been reported to be exclusively expressed in the retina. In contrast, a previous report has suggested a possible relationship between ABCA4 and CNS function. The purpose of the present study was to investigate the localization of ABCA4 mRNA and protein in rat brain. In situ hybridization analysis revealed that ABCA4 mRNA was localized in the lateral ventricles. RT-PCR analysis detected ABCA4 mRNA in isolated rat choroid plexus and conditionally immortalized rat choroid plexus epithelial cells (TR-CSFB). Furthermore, ABCA4 protein was also detected in the isolated rat choroid plexus at about 250 kDa by western blot analysis, and its apparent molecular size was reduced by N-glycosidase F treatment. These results suggest that glycosylated ABCA4 protein is expressed in rat choroid plexus epithelial cells. ABCA4 may play a role in the function of the blood-cerebrospinal fluid barrier and affect CSF conditions.

Amphipathic Polyproline Peptides Stimulate Cholesterol Efflux by the ABCA1 Transporter

PubMed Central

Sviridov, D.O.; Drake, S.K.; Freeman, L.A.; Remaley, A.T.

2016-01-01

ApoA-I mimetics are short synthetic peptides that contain an amphipathic αα-helix and stimulate cholesterol efflux by the ABCA1 transporter in a detergent-like extraction mechanism. We investigated the use of amphipathic peptides with a polypro helix for stimulating cholesterol efflux by ABCA1. Polypro peptides were synthesized with modified prolines, containing either a hydrophobic phenol group (Prop) or a polar N-acetylgalactosamine (Prog) attached to the pyrrolidine ring and were designated as either PP-2, 3, 4, or 5, depending on the number of 3 amino acid repeat units (Prop - Prog - Prop). Based on molecular modeling, these peptides were predicted to be relatively rigid and to bind to a phospholipid bilayer. By CD spectroscopy, PP peptides formed a Type-II polypro helix in an aqueous solution. PP-2 was inactive in promoting cholesterol efflux, but peptides with more than 2 repeat units were active. PP-4 showed a similar Vmax as a much longer amphipathic α-αhelical peptide, containing 37 amino acids, but had a Km that was approximately 20-fold lower. PP peptides were specific in that they did not stimulate cholesterol efflux from cells not expressing ABCA1 and were also non-cytotoxic. Addition of PP-3, 4 and 5 to serum promoted the formation of smaller size HDL species (7 nM) and increased its capacity for ABCA1-dependent cholesterol efflux by approximately 20-35% (p<0.05). Because of their relatively small size and increased potency, amphipathic peptides with a polypro helix may represent an alternative structural motif for the development of apoA-I mimetic peptides. PMID:26879139

Novel Apo E-Derived ABCA1 Agonist Peptide (CS-6253) Promotes Reverse Cholesterol Transport and Induces Formation of preβ-1 HDL In Vitro

PubMed Central

Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; Genest, Jacques

2015-01-01

Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from the carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

Novel apo E-derived ABCA1 agonist peptide (CS-6253) promotes reverse cholesterol transport and induces formation of preβ-1 HDL in vitro

DOE PAGES

Hafiane, Anouar; Bielicki, John K.; Johansson, Jan O.; ...

2015-07-24

Apolipoprotein (apo) mimetic peptides replicate some aspects of HDL function. We have previously reported the effects of compound ATI-5261 on its ability to replicate many functions of native apo A-I in the process of HDL biogenesis. ATI-5261 induced muscle toxicity in wild type C57Bl/6 mice, increased CPK, ALT and AST and increase in triglyceride (Tg) levels. Aromatic phenylalanine residues on the non-polar face of ATI-5261, together with positively charged arginine residues at the lipid-water interface were responsible for these effects. This information was used to create a novel analog (CS-6253) that was non-toxic. We evaluated this peptide designed from themore » carboxyl terminus of apo E, in its ability to mimic apo A-I functionality. Our data shows that the lipidated particles generated by incubating cells overexpressing ABCA1 with lipid free CS-6253 enhances the rate of ABCA1 lipid efflux with high affinity interactions with native ABCA1 oligomeric forms and plasma membrane micro-domains. Interaction between ABCA1 and lipid free CS-6253 resulted in formation of nascent HDL-CS-6253 particles that are actively remodeled in plasma. Mature HDL-CS-6253 particles deliver cholesterol to liver cells via SR-BI in-vitro. CS-6253 significantly increases cholesterol efflux in murine macrophages and in human THP-1 macrophage-derived foam cells expressing ABCA1. Addition of CS-6253 to plasma dose-dependently displaced apo A-I from α-HDL particles and led to de novo formation of preβ-1 HDL that stimulates ABCA1 dependent cholesterol efflux efficiently. When incubated with human plasma CS-6253 was also found to bind with HDL and LDL and promoted the transfer of cholesterol from HDL to LDL predominantly. Our data shows that CS-6253 mimics apo A-I in its ability to promote ABCA1-mediated formation of nascent HDL particles, and enhances formation of preβ-1 HDL with increase in the cycling of apo A-I between the preβ and α-HDL particles in-vitro. These mechanisms are

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.

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

Quercetin-3-O-glucuronide induces ABCA1 expression by LXRα activation in murine macrophages

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

Ohara, Kazuaki, E-mail: Kazuaki_Ohara@kirin.co.jp; Wakabayashi, Hideyuki; Taniguchi, Yoshimasa

Highlights: •The major circulating quercetin metabolite (Q3GA) activated LXRα. •Q3GA induced ABCA1 via LXRα activation in macrophages. •Nelumbo nucifera leaf extracts contained quercetin glycosides. •N. nucifera leaf extract feeding elevated HDLC in mice. -- Abstract: Reverse cholesterol transport (RCT) removes excess cholesterol from macrophages to prevent atherosclerosis. ATP-binding cassette, subfamily A, member 1 (ABCA1) is a crucial cholesterol transporter involved in RCT to produce high density lipoprotein-cholesterol (HDLC), and is transcriptionally regulated by liver X receptor alpha (LXRα), a nuclear receptor. Quercetin is a widely distributed flavonoid in edible plants which prevented atherosclerosis in an animal model. We found thatmore » quercetin-3-O-glucuronide (Q3GA), a major quercetin metabolite after absorption from the digestive tract, enhanced ABCA1 expression, in vitro, via LXRα in macrophages. In addition, leaf extracts of a traditional Asian edible plant, Nelumbo nucifera (NNE), which contained abundant amounts of quercetin glycosides, significantly elevated plasma HDLC in mice. We are the first to present experimental evidence that Q3GA induced ABCA1 in macrophages, and to provide an alternative explanation to previous studies on arteriosclerosis prevention by quercetin.« less

Novel association of the R230C variant of the ABCA1 gene with high triglyceride levels and low high-density lipoprotein cholesterol levels in Mexican school-age children with high prevalence of obesity.

PubMed

Gamboa-Meléndez, Marco Alberto; Galindo-Gómez, Carlos; Juárez-Martínez, Liliana; Gómez, F Enrique; Diaz-Diaz, Eulises; Ávila-Arcos, Marco Antonio; Ávila-Curiel, Abelardo

2015-08-01

Metabolic syndrome (MetS) is a disorder that includes a cluster of several risk factors for the development of type 2 diabetes and cardiovascular disease. The R230C variant of the ABCA1 gene has been associated with low HDL-cholesterol in several studies, but its association with MetS in children remains to be determined. The aim of this study was to analyze the association of the R230C variant with MetS and other metabolic traits in school-aged Mexican children. The study was performed in seven urban primary schools in the State of Mexico. Four hundred thirty-two Mexican school-age children 6-13 years old were recruited. MetS was identified using the International Diabetes Federation definition. The R230C variant of the ABCA1 gene was genotyped to seek associations with MetS and other metabolic traits. The prevalence of MetS was 29% in children aged 10-13 years. The R230C variant was not associated with MetS (OR = 1.65; p = 0.139). Furthermore, in the whole population, the R230C variant was associated with low HDL-cholesterol levels (β coefficient = -3.28, p <0.001). Interestingly, in the total population we found a novel association of this variant with high triglyceride levels (β coefficient = 14.34; p = 0.027). We found a new association of the R230C variant of the ABCA1 gene with high triglyceride levels. Our findings also replicate the association of this variant with low HDL-cholesterol levels in Mexican school-age children. Copyright © 2015 IMSS. Published by Elsevier Inc. All rights reserved.

Macrophage ABCA1 reduces MyD88-dependent Toll-like receptor trafficking to lipid rafts by reduction of lipid raft cholesterol[S

PubMed Central

Zhu, Xuewei; Owen, John S.; Wilson, Martha D.; Li, Haitao; Griffiths, Gary L.; Thomas, Michael J.; Hiltbold, Elizabeth M.; Fessler, Michael B.; Parks, John S.

2010-01-01

We previously showed that macrophages from macrophage-specific ATP-binding cassette transporter A1 (ABCA1) knockout (Abca1-M/-M) mice had an enhanced proinflammatory response to the Toll-like receptor (TLR) 4 agonist, lipopolysaccharide (LPS), compared with wild-type (WT) mice. In the present study, we demonstrate a direct association between free cholesterol (FC), lipid raft content, and hyper-responsiveness of macrophages to LPS in WT mice. Abca1-M/-M macrophages were also hyper-responsive to specific agonists to TLR2, TLR7, and TLR9, but not TLR3, compared with WT macrophages. We hypothesized that ABCA1 regulates macrophage responsiveness to TLR agonists by modulation of lipid raft cholesterol and TLR mobilization to lipid rafts. We demonstrated that Abca1-M/-M vs. WT macrophages contained 23% more FC in isolated lipid rafts. Further, mass spectrometric analysis suggested raft phospholipid composition was unchanged. Although cell surface expression of TLR4 was similar between Abca1-M/-M and WT macrophages, significantly more TLR4 was distributed in membrane lipid rafts in Abca1-M/-M macrophages. Abca1-M/-M macrophages also exhibited increased trafficking of the predominantly intracellular TLR9 into lipid rafts in response to TLR9-specific agonist (CpG). Collectively, our data suggest that macrophage ABCA1 dampens inflammation by reducing MyD88-dependent TLRs trafficking to lipid rafts by selective reduction of FC content in lipid rafts. PMID:20650929

N-retinylidene-phosphatidylethanolamine is the preferred retinoid substrate for the photoreceptor-specific ABC transporter ABCA4 (ABCR).

PubMed

Beharry, Seelochan; Zhong, Ming; Molday, Robert S

2004-12-24

ABCA4, a member of the family of ATP binding cassette (ABC) proteins found in rod and cone photoreceptors, has been implicated in the transport of retinoid compounds across the outer segment disk membrane following the photoactivation of rhodopsin. Mutations in the ABCA4 gene are responsible for Stargardt macular dystrophy and related retinal degenerative diseases that cause a loss in vision. To identify the retinoid substrate that interacts with ABCA4, we have isolated ABCA4 from rod outer segment disk membranes on an immunoaffinity matrix and analyzed retinoid compounds that bind to ABCA4 using high performance liquid chromatography and radiolabeling methods. When all-trans-retinal was added to ABCA4 in the presence of phosphatidylethanolamine, approximately 0.9 mol of N-retinylidene-phosphatidylethanolamine and 0.3 mol of all-trans-retinal were bound per mol of ABCA4 with an apparent K(d) of 2-5 microm. ATP and GTP released these retinoids from ABCA4, whereas ADP, GDP, and nonhydrolyzable derivatives, adenosine 5'-(beta,gamma-imido)triphosphate and guanosine 5'-(beta,gamma-imido)triphosphate, were ineffective. One mole of N-retinyl-phosphatidylethanolamine, the reduced form of N-retinylidene-phosphatidylethanolamine, bound per mol of ABCA4, whereas 0.3 mol of all-trans-retinal were bound in the absence of phosphatidylethanolamine. No binding of all-trans-retinol to ABCA4 was observed. Our results indicate that ABCA4 preferentially binds N-retinylidene-phosphatidylethanolamine with high affinity in the absence of ATP. Our studies further suggest that ATP binding and hydrolysis induces a protein conformational change that causes N-retinylidene-phosphatidylethanolamine to dissociate from ABCA4.

Deleterious ABCA7 mutations and transcript rescue mechanisms in early onset Alzheimer's disease.

PubMed

De Roeck, Arne; Van den Bossche, Tobi; van der Zee, Julie; Verheijen, Jan; De Coster, Wouter; Van Dongen, Jasper; Dillen, Lubina; Baradaran-Heravi, Yalda; Heeman, Bavo; Sanchez-Valle, Raquel; Lladó, Albert; Nacmias, Benedetta; Sorbi, Sandro; Gelpi, Ellen; Grau-Rivera, Oriol; Gómez-Tortosa, Estrella; Pastor, Pau; Ortega-Cubero, Sara; Pastor, Maria A; Graff, Caroline; Thonberg, Håkan; Benussi, Luisa; Ghidoni, Roberta; Binetti, Giuliano; de Mendonça, Alexandre; Martins, Madalena; Borroni, Barbara; Padovani, Alessandro; Almeida, Maria Rosário; Santana, Isabel; Diehl-Schmid, Janine; Alexopoulos, Panagiotis; Clarimon, Jordi; Lleó, Alberto; Fortea, Juan; Tsolaki, Magda; Koutroumani, Maria; Matěj, Radoslav; Rohan, Zdenek; De Deyn, Peter; Engelborghs, Sebastiaan; Cras, Patrick; Van Broeckhoven, Christine; Sleegers, Kristel

2017-09-01

Premature termination codon (PTC) mutations in the ATP-Binding Cassette, Sub-Family A, Member 7 gene (ABCA7) have recently been identified as intermediate-to-high penetrant risk factor for late-onset Alzheimer's disease (LOAD). High variability, however, is observed in downstream ABCA7 mRNA and protein expression, disease penetrance, and onset age, indicative of unknown modifying factors. Here, we investigated the prevalence and disease penetrance of ABCA7 PTC mutations in a large early onset AD (EOAD)-control cohort, and examined the effect on transcript level with comprehensive third-generation long-read sequencing. We characterized the ABCA7 coding sequence with next-generation sequencing in 928 EOAD patients and 980 matched control individuals. With MetaSKAT rare variant association analysis, we observed a fivefold enrichment (p = 0.0004) of PTC mutations in EOAD patients (3%) versus controls (0.6%). Ten novel PTC mutations were only observed in patients, and PTC mutation carriers in general had an increased familial AD load. In addition, we observed nominal risk reducing trends for three common coding variants. Seven PTC mutations were further analyzed using targeted long-read cDNA sequencing on an Oxford Nanopore MinION platform. PTC-containing transcripts for each investigated PTC mutation were observed at varying proportion (5-41% of the total read count), implying incomplete nonsense-mediated mRNA decay (NMD). Furthermore, we distinguished and phased several previously unknown alternative splicing events (up to 30% of transcripts). In conjunction with PTC mutations, several of these novel ABCA7 isoforms have the potential to rescue deleterious PTC effects. In conclusion, ABCA7 PTC mutations play a substantial role in EOAD, warranting genetic screening of ABCA7 in genetically unexplained patients. Long-read cDNA sequencing revealed both varying degrees of NMD and transcript-modifying events, which may influence ABCA7 dosage, disease severity, and may

ABCA1-dependent sterol release: sterol molecule specificity and potential membrane domain for HDL biogenesis

PubMed Central

Yamauchi, Yoshio; Yokoyama, Shinji; Chang, Ta-Yuan

2016-01-01

Mammalian cells synthesize various sterol molecules, including the C30 sterol, lanosterol, as cholesterol precursors in the endoplasmic reticulum. The build-up of precursor sterols, including lanosterol, displays cellular toxicity. Precursor sterols are found in plasma HDL. How these structurally different sterols are released from cells is poorly understood. Here, we show that newly synthesized precursor sterols arriving at the plasma membrane (PM) are removed by extracellular apoA-I in a manner dependent on ABCA1, a key macromolecule for HDL biogenesis. Analysis of sterol molecules by GC-MS and tracing the fate of radiolabeled acetate-derived sterols in normal and mutant Niemann-Pick type C cells reveal that ABCA1 prefers newly synthesized sterols, especially lanosterol, as the substrates before they are internalized from the PM. We also show that ABCA1 resides in a cholesterol-rich membrane domain resistant to the mild detergent, Brij 98. Blocking ACAT activity increases the cholesterol contents of this domain. Newly synthesized C29/C30 sterols are transiently enriched within this domain, but rapidly disappear from this domain with a half-life of less than 1 h. Our work shows that substantial amounts of precursor sterols are transported to a certain PM domain and are removed by the ABCA1-dependent pathway. PMID:26497474

A functional ABCA1 gene variant is associated with low HDL-cholesterol levels and shows evidence of positive selection in Native Americans

PubMed Central

Acuña-Alonzo, Víctor; Flores-Dorantes, Teresa; Kruit, Janine K.; Villarreal-Molina, Teresa; Arellano-Campos, Olimpia; Hünemeier, Tábita; Moreno-Estrada, Andrés; Ortiz-López, Ma Guadalupe; Villamil-Ramírez, Hugo; León-Mimila, Paola; Villalobos-Comparan, Marisela; Jacobo-Albavera, Leonor; Ramírez-Jiménez, Salvador; Sikora, Martin; Zhang, Lin-Hua; Pape, Terry D.; de Ángeles Granados-Silvestre, Ma; Montufar-Robles, Isela; Tito-Alvarez, Ana M.; Zurita-Salinas, Camilo; Bustos-Arriaga, José; Cedillo-Barrón, Leticia; Gómez-Trejo, Celta; Barquera-Lozano, Rodrigo; Vieira-Filho, Joao P.; Granados, Julio; Romero-Hidalgo, Sandra; Huertas-Vázquez, Adriana; González-Martín, Antonio; Gorostiza, Amaya; Bonatto, Sandro L.; Rodríguez-Cruz, Maricela; Wang, Li; Tusié-Luna, Teresa; Aguilar-Salinas, Carlos A.; Lisker, Ruben; Moises, Regina S.; Menjivar, Marta; Salzano, Francisco M.; Knowler, William C.; Bortolini, M. Cátira; Hayden, Michael R.; Baier, Leslie J.; Canizales-Quinteros, Samuel

2010-01-01

It has been suggested that the higher susceptibility of Hispanics to metabolic disease is related to their Native American heritage. A frequent cholesterol transporter ABCA1 (ATP-binding cassette transporter A1) gene variant (R230C, rs9282541) apparently exclusive to Native American individuals was associated with low high-density lipoprotein cholesterol (HDL-C) levels, obesity and type 2 diabetes in Mexican Mestizos. We performed a more extensive analysis of this variant in 4405 Native Americans and 863 individuals from other ethnic groups to investigate genetic evidence of positive selection, to assess its functional effect in vitro and to explore associations with HDL-C levels and other metabolic traits. The C230 allele was found in 29 of 36 Native American groups, but not in European, Asian or African individuals. C230 was observed on a single haplotype, and C230-bearing chromosomes showed longer relative haplotype extension compared with other haplotypes in the Americas. Additionally, single-nucleotide polymorphism data from the Human Genome Diversity Panel Native American populations were enriched in significant integrated haplotype score values in the region upstream of the ABCA1 gene. Cells expressing the C230 allele showed a 27% cholesterol efflux reduction (P< 0.001), confirming this variant has a functional effect in vitro. Moreover, the C230 allele was associated with lower HDL-C levels (P = 1.77 × 10−11) and with higher body mass index (P = 0.0001) in the combined analysis of Native American populations. This is the first report of a common functional variant exclusive to Native American and descent populations, which is a major determinant of HDL-C levels and may have contributed to the adaptive evolution of Native American populations. PMID:20418488

Insulin-like Growth Factor 1 Regulates the Expression of ATP-Binding Cassette Transporter A1 in Pancreatic Beta Cells.

PubMed

Lyu, J; Imachi, H; Iwama, H; Zhang, H; Murao, K

2016-05-01

ATP-binding cassette transporter A1 (ABCA1) in pancreatic beta cells influences insulin secretion and cholesterol homeostasis. The present study investigates whether insulin-like growth factor 1 (IGF-1), which mediates stimulation of ABCA1 gene expression, could also interfere with the phosphatidylinositol 3-kinase (PI3-K) cascade.ABCA1 expression was examined by real-time polymerase chain reaction (PCR), Western blot analysis, and a reporter gene assay in rat insulin-secreting INS-1 cells incubated with IGF-1. The binding of forkhead box O1 (FoxO1) protein to the ABCA1 promoter was assessed by a chromatin immunoprecipitation (ChIP) assay. ABCA1 protein levels increased in response to rising concentrations of IGF-1. Real-time PCR analysis showed a significant increase in ABCA1 mRNA expression. However, both effects were suppressed after silencing the IGF-1 receptor. In parallel with its effect on endogenous ABCA1 mRNA levels, IGF-1 induced the activity of a reporter construct containing the ABCA1 promoter, while it was abrogated by LY294002, a specific inhibitor of PI3-K. Constitutively active Akt stimulated activity of the ABCA1 promoter, and a dominant-negative mutant of Akt or mutagenesis of the FoxO1 response element in the ABCA1 promoter abolished the ability of IGF-1 to stimulate promoter activity. A ChIP assay showed that FoxO1 mediated its transcriptional activity by directly binding to the ABCA1 promoter region. The knockdown of FoxO1 disrupted the effect of IGF-1 on ABCA1 expression. Furthermore, IGF-1 promoted cholesterol efflux and reduced the pancreatic lipotoxicity. These results demonstrate that the PI3-K/Akt/FoxO1 pathway contributes to the regulation of ABCA1 expression in response to IGF-1 stimulation. © Georg Thieme Verlag KG Stuttgart · New York.

On the mechanism for PPAR agonists to enhance ABCA1 gene expression

PubMed Central

Ogata, Masaki; Tsujita, Maki; Hossain, Mohammad Anwar; Akita, Nobukatsu; Gonzalez, Frank J.; Staels, Bart; Suzuki, Shogo; Fukutomi, Tatsuya; Kimura, Genjiro; Yokoyama, Shinji

2009-01-01

Expression of ATP binding cassette transporter A1 (ABCA1), a major regulator of high density lipoprotein (HDL) biogenesis, is known to be up-regulated by the transcription factor liver X receptor (LXR) α, and expression is further enhanced by activation of the peroxisome proliferator activated receptors (PPARs). We investigated this complex regulatory network using specific PPAR agonists: four fibrates (fenofibrate, bezafibrate, gemfibrozil and LY518674), a PPAR δ agonist (GW501516) and a PPAR γ agonist (pioglitazone). All of these compounds increased the expression of LXRs, PPARs and ABCA1 mRNAs, and associated apoA-I-mediated lipid release in THP-1 macrophage, WI38 fibroblast and mouse fibroblast. When mouse fibroblasts lacking expression of PPAR α were examined, the effects of fenofibrate and LY518674 were markedly diminished while induction by other ligands were retained. The PPAR α promoter was activated by all of these compounds in an LXR α-dependent manner, and partially in a PPAR α-dependent manner, in mouse fibroblast. The LXR responsive element (LXRE)-luciferase activity was enhanced by all the compounds in an LXR α-dependent manner in mouse fibroblast. This activation was exclusively PPAR α-dependent by fenofibrate and LY518674, but nonexclusively by the others. We conclude that PPARs and LXRs are involved in the regulation of ABCA1 expression and HDL biogenesis in a cooperative signal transduction pathway. PMID:19201410

ABCA1-dependent sterol release: sterol molecule specificity and potential membrane domain for HDL biogenesis.

PubMed

Yamauchi, Yoshio; Yokoyama, Shinji; Chang, Ta-Yuan

2016-01-01

Mammalian cells synthesize various sterol molecules, including the C30 sterol, lanosterol, as cholesterol precursors in the endoplasmic reticulum. The build-up of precursor sterols, including lanosterol, displays cellular toxicity. Precursor sterols are found in plasma HDL. How these structurally different sterols are released from cells is poorly understood. Here, we show that newly synthesized precursor sterols arriving at the plasma membrane (PM) are removed by extracellular apoA-I in a manner dependent on ABCA1, a key macromolecule for HDL biogenesis. Analysis of sterol molecules by GC-MS and tracing the fate of radiolabeled acetate-derived sterols in normal and mutant Niemann-Pick type C cells reveal that ABCA1 prefers newly synthesized sterols, especially lanosterol, as the substrates before they are internalized from the PM. We also show that ABCA1 resides in a cholesterol-rich membrane domain resistant to the mild detergent, Brij 98. Blocking ACAT activity increases the cholesterol contents of this domain. Newly synthesized C29/C30 sterols are transiently enriched within this domain, but rapidly disappear from this domain with a half-life of less than 1 h. Our work shows that substantial amounts of precursor sterols are transported to a certain PM domain and are removed by the ABCA1-dependent pathway. Copyright © 2016 by the American Society for Biochemistry and Molecular Biology, Inc.

The Role of the Photoreceptor ABC Transporter ABCA4 in Lipid Transport and Stargardt Macular Degeneration

PubMed Central

Molday, Robert S.; Zhong, Ming; Quazi, Faraz

2009-01-01

ABCA4 is a member of the ABCA subfamily of ATP binding cassette (ABC) transporters that is expressed in rod and cone photoreceptors of the vertebrate retina. ABCA4, also known as the Rim protein and ABCR, is a large 2273 amino acid glycoprotein organized as two tandem halves, each containing a single membrane spanning segment followed sequentially by a large exocytoplasmic domain, a multispanning membrane domain and a nucleotide binding domain. Over 500 mutations in the gene encoding ABCA4 are associated with a spectrum of related autosomal recessive retinal degenerative diseases including Stargardt macular degeneration, cone-rod dystrophy and a subset of retinitis pigmentosa. Biochemical studies on the purified ABCA4 together with analysis of abca4 knockout mice and patients with Stargardt disease have implicated ABCA4 as a retinylidene-phosphatidylethanolamine transporter that facilitates the removal of potentially reactive retinal derivatives from photoreceptors following photoexcitation. Knowledge of the genetic and molecular basis for ABCA4 related retinal degenerative diseases is being used to develop rationale therapeutic treatments for this set of disorders. PMID:19230850

Multi-Layer Identification of Highly-Potent ABCA1 Up-Regulators Targeting LXRβ Using Multiple QSAR Modeling, Structural Similarity Analysis, and Molecular Docking.

PubMed

Chen, Meimei; Yang, Fafu; Kang, Jie; Yang, Xuemei; Lai, Xinmei; Gao, Yuxing

2016-11-29

In this study, in silico approaches, including multiple QSAR modeling, structural similarity analysis, and molecular docking, were applied to develop QSAR classification models as a fast screening tool for identifying highly-potent ABCA1 up-regulators targeting LXRβ based on a series of new flavonoids. Initially, four modeling approaches, including linear discriminant analysis, support vector machine, radial basis function neural network, and classification and regression trees, were applied to construct different QSAR classification models. The statistics results indicated that these four kinds of QSAR models were powerful tools for screening highly potent ABCA1 up-regulators. Then, a consensus QSAR model was developed by combining the predictions from these four models. To discover new ABCA1 up-regulators at maximum accuracy, the compounds in the ZINC database that fulfilled the requirement of structural similarity of 0.7 compared to known potent ABCA1 up-regulator were subjected to the consensus QSAR model, which led to the discovery of 50 compounds. Finally, they were docked into the LXRβ binding site to understand their role in up-regulating ABCA1 expression. The excellent binding modes and docking scores of 10 hit compounds suggested they were highly-potent ABCA1 up-regulators targeting LXRβ. Overall, this study provided an effective strategy to discover highly potent ABCA1 up-regulators.

Genome of the Netherlands population-specific imputations identify an ABCA6 variant associated with cholesterol levels

PubMed Central

van Leeuwen, Elisabeth M.; Karssen, Lennart C.; Deelen, Joris; Isaacs, Aaron; Medina-Gomez, Carolina; Mbarek, Hamdi; Kanterakis, Alexandros; Trompet, Stella; Postmus, Iris; Verweij, Niek; van Enckevort, David J.; Huffman, Jennifer E.; White, Charles C.; Feitosa, Mary F.; Bartz, Traci M.; Manichaikul, Ani; Joshi, Peter K.; Peloso, Gina M.; Deelen, Patrick; van Dijk, Freerk; Willemsen, Gonneke; de Geus, Eco J.; Milaneschi, Yuri; Penninx, Brenda W.J.H.; Francioli, Laurent C.; Menelaou, Androniki; Pulit, Sara L.; Rivadeneira, Fernando; Hofman, Albert; Oostra, Ben A.; Franco, Oscar H.; Leach, Irene Mateo; Beekman, Marian; de Craen, Anton J.M.; Uh, Hae-Won; Trochet, Holly; Hocking, Lynne J.; Porteous, David J.; Sattar, Naveed; Packard, Chris J.; Buckley, Brendan M.; Brody, Jennifer A.; Bis, Joshua C.; Rotter, Jerome I.; Mychaleckyj, Josyf C.; Campbell, Harry; Duan, Qing; Lange, Leslie A.; Wilson, James F.; Hayward, Caroline; Polasek, Ozren; Vitart, Veronique; Rudan, Igor; Wright, Alan F.; Rich, Stephen S.; Psaty, Bruce M.; Borecki, Ingrid B.; Kearney, Patricia M.; Stott, David J.; Adrienne Cupples, L.; Neerincx, Pieter B.T.; Elbers, Clara C.; Francesco Palamara, Pier; Pe'er, Itsik; Abdellaoui, Abdel; Kloosterman, Wigard P.; van Oven, Mannis; Vermaat, Martijn; Li, Mingkun; Laros, Jeroen F.J.; Stoneking, Mark; de Knijff, Peter; Kayser, Manfred; Veldink, Jan H.; van den Berg, Leonard H.; Byelas, Heorhiy; den Dunnen, Johan T.; Dijkstra, Martijn; Amin, Najaf; Joeri van der Velde, K.; van Setten, Jessica; Kattenberg, Mathijs; van Schaik, Barbera D.C.; Bot, Jan; Nijman, Isaäc J.; Mei, Hailiang; Koval, Vyacheslav; Ye, Kai; Lameijer, Eric-Wubbo; Moed, Matthijs H.; Hehir-Kwa, Jayne Y.; Handsaker, Robert E.; Sunyaev, Shamil R.; Sohail, Mashaal; Hormozdiari, Fereydoun; Marschall, Tobias; Schönhuth, Alexander; Guryev, Victor; Suchiman, H. Eka D.; Wolffenbuttel, Bruce H.; Platteel, Mathieu; Pitts, Steven J.; Potluri, Shobha; Cox, David R.; Li, Qibin; Li, Yingrui; Du, Yuanping; Chen, Ruoyan; Cao, Hongzhi; Li, Ning; Cao, Sujie; Wang, Jun; Bovenberg, Jasper A.; Jukema, J. Wouter; van der Harst, Pim; Sijbrands, Eric J.; Hottenga, Jouke-Jan; Uitterlinden, Andre G.; Swertz, Morris A.; van Ommen, Gert-Jan B.; de Bakker, Paul I.W.; Eline Slagboom, P.; Boomsma, Dorret I.; Wijmenga, Cisca; van Duijn, Cornelia M.

2015-01-01

Variants associated with blood lipid levels may be population-specific. To identify low-frequency variants associated with this phenotype, population-specific reference panels may be used. Here we impute nine large Dutch biobanks (~35,000 samples) with the population-specific reference panel created by the Genome of the Netherlands Project and perform association testing with blood lipid levels. We report the discovery of five novel associations at four loci (P value <6.61 × 10−4), including a rare missense variant in ABCA6 (rs77542162, p.Cys1359Arg, frequency 0.034), which is predicted to be deleterious. The frequency of this ABCA6 variant is 3.65-fold increased in the Dutch and its effect (βLDL-C=0.135, βTC=0.140) is estimated to be very similar to those observed for single variants in well-known lipid genes, such as LDLR. PMID:25751400

ABCA7 frameshift deletion associated with Alzheimer disease in African Americans

PubMed Central

Cukier, Holly N.; Kunkle, Brian W.; Vardarajan, Badri N.; Rolati, Sophie; Hamilton-Nelson, Kara L.; Kohli, Martin A.; Whitehead, Patrice L.; Dombroski, Beth A.; Van Booven, Derek; Lang, Rosalyn; Dykxhoorn, Derek M.; Farrer, Lindsay A.; Cuccaro, Michael L.; Vance, Jeffery M.; Gilbert, John R.; Beecham, Gary W.; Martin, Eden R.; Carney, Regina M.; Mayeux, Richard; Schellenberg, Gerard D.; Byrd, Goldie S.; Haines, Jonathan L.

2016-01-01

Objective: To identify a causative variant(s) that may contribute to Alzheimer disease (AD) in African Americans (AA) in the ATP-binding cassette, subfamily A (ABC1), member 7 (ABCA7) gene, a known risk factor for late-onset AD. Methods: Custom capture sequencing was performed on ∼150 kb encompassing ABCA7 in 40 AA cases and 37 AA controls carrying the AA risk allele (rs115550680). Association testing was performed for an ABCA7 deletion identified in large AA data sets (discovery n = 1,068; replication n = 1,749) and whole exome sequencing of Caribbean Hispanic (CH) AD families. Results: A 44-base pair deletion (rs142076058) was identified in all 77 risk genotype carriers, which shows that the deletion is in high linkage disequilibrium with the risk allele. The deletion was assessed in a large data set (531 cases and 527 controls) and, after adjustments for age, sex, and APOE status, was significantly associated with disease (p = 0.0002, odds ratio [OR] = 2.13 [95% confidence interval (CI): 1.42–3.20]). An independent data set replicated the association (447 cases and 880 controls, p = 0.0117, OR = 1.65 [95% CI: 1.12–2.44]), and joint analysis increased the significance (p = 1.414 × 10−5, OR = 1.81 [95% CI: 1.38–2.37]). The deletion is common in AA cases (15.2%) and AA controls (9.74%), but in only 0.12% of our non-Hispanic white cohort. Whole exome sequencing of multiplex, CH families identified the deletion cosegregating with disease in a large sibship. The deleted allele produces a stable, detectable RNA strand and is predicted to result in a frameshift mutation (p.Arg578Alafs) that could interfere with protein function. Conclusions: This common ABCA7 deletion could represent an ethnic-specific pathogenic alteration in AD. PMID:27231719

Recurrent amplification of RTEL1 and ABCA13 and its synergistic effect associated with clinicopathological data of gastric adenocarcinoma.

PubMed

Araújo, T M; Seabra, A D; Lima, E M; Assumpção, P P; Montenegro, R C; Demachki, S; Burbano, R M; Khayat, A S

2016-01-01

Despite progression in treatment of gastric cancer, prognosis of patients remains poor, in part due to the low rate of diagnosis during its early stages. This paradigm implies the necessity to identify molecular biomarkers for early gastric cancer diagnosis, as well as for disease monitoring, thus contributing to the development of new therapeutic approaches. In a previous study, performed by array-Comparative Genomic Hybridization, we described for the first time in literature recurrent amplification of RTEL1 and ABCA13 genes in gastric cancer. Thus, the aim of the present study was to validate recurrent amplification of RTEL1 and ABCA13 genes and associate CNV status with clinicopathological data. Results showed RTEL1 and ABCA13 amplification in 38 % of samples. Statistical analysis demonstrated that RTEL amplification is more common in older patients and more associated with intestinal type and ABCA13 amplification increases the risk of lymph node metastasis and is more common in men. Co-amplification of these genes showed a significant association with advanced staging. aCGH is a very useful tool for investigating novel genes associated with carcinogenesis and RTEL1 amplification may be important for the development of gastric cancer in older patients, besides being a probable event contributing for chromosomal instability in intestinal gastric carcinogenesis. ABCA13 amplification may have age-specific function and could be considered a useful marker for predicting lymph node metastasis in resected gastric cancer patients in early stage. Lastly, RTEL1 and ABCA13 synergistic effect may be considered as a putative marker for advanced staging in gastric cancer patients.

Glucagon-like peptide-1 contributes to increases ABCA1 expression by downregulating miR-758 to regulate cholesterol homeostasis.

PubMed

Yao, Yue; Li, Qiang; Gao, Ping; Wang, Wei; Chen, Lili; Zhang, Jinchao; Xu, Yi

2018-03-04

Abnormal regulation of lipid metabolism is associated with type 2 diabetes mellitus (T2DM). GLP-1 as a new treatment for T2DM, has unique effects in modulating cholesterol homeostasis. However, the mechanism of this effect is largely missing. The aim of this study was to determine the effects of GLP-1 on cholesterol-induced lipotoxicity in hepatocytes and examine the underlying mechanisms. The cell viability was determined, and caspase-3 was used to detect the effects of GLP-1 on cholesterol-induced apoptosis. The alterations of miR-758 and ATP-binding cassette transporter A1 (ABCA1) resulting from cholesterol incubation or GLP-1 were detected by qRT-PCR and Western blot assays. Overexpression of miR-758 abrogated the GLP-1-mediated ABCA1 expression, and conversely, down-regulation of miR-758 aggravated GLP-1's action and revealed significant promotion effects. BODIPY-Cholesterol efflux assay revealed that treatment with miR-758 inhibitor significantly enhanced ABCA1-dependent cholesterol efflux, resulting in reduced total cholesterol. Furthermore, Oil red O staining and cholesterol measurement were used to detect lipid accumulation. As a result, cholesterol significantly attenuated cell viability, promoted cell apoptosis, and facilitated lipid accumulation, and these effects were reversed by GLP-1. This study provides evidence that, in HepG2 cells, GLP-1 may affect cholesterol homeostasis by regulating the expression of miR-758 and ABCA1. These data can inform the development of biomarkers for miR-758, and potentially other drugs, on the key pathways of lipid metabolism. Copyright © 2018 Elsevier Inc. All rights reserved.

Gender-specific association of ATP-binding cassette transporter 1 (ABCA1) polymorphisms with the risk of late-onset Alzheimer's disease.

PubMed

Sundar, Purnima Desai; Feingold, Eleanor; Minster, Ryan L; DeKosky, Steven T; Kamboh, M Ilyas

2007-06-01

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder caused by a complex interaction of genetic and environmental factors. Increasing evidence highlights a potential role for cholesterol in the pathophysiology of AD. The ABCA1 gene, located in close vicinity to the 9q linkage peaks identified by genome-wide AD linkage studies, plays an important role in cellular cholesterol efflux, and is likely a good candidate gene. However, results from published genetic association studies between ABCA1 and AD are ambiguous. In the present study, we examined the role of two ABCA1 polymorphisms, R219K (rs2230806) and G-17C (rs2740483) in modifying the risk of late-onset AD (LOAD) in a large American white cohort of 992 AD cases and 699 controls. We observed significant gender x R219K interaction (p=0.00008). Female carriers of the 219K allele showed a 1.75-fold increased risk of developing AD compared to non-219K carrier females (95% CI 1.34-2.29; p=0.00004). The overall two-site haplotype distribution was also significant between female AD cases and controls (p=0.017). The risk associated with the R219K polymorphism was independent of the recently reported significant association in the ubiquilin (UBQLN1) gene in this region on chromosome 9q. Our data suggest a gender-specific and APOE and UBQLN1 independent association between the ABCA1/R219K polymorphism and LOAD.

Interaction between FTO rs9939609 and the Native American-origin ABCA1 rs9282541 affects BMI in the admixed Mexican population.

PubMed

Villalobos-Comparán, Marisela; Antuna-Puente, Bárbara; Villarreal-Molina, María Teresa; Canizales-Quinteros, Samuel; Velázquez-Cruz, Rafael; León-Mimila, Paola; Villamil-Ramírez, Hugo; González-Barrios, Juan Antonio; Merino-García, José Luis; Thompson-Bonilla, María Rocío; Jarquin, Diego; Sánchez-Hernández, Osvaldo Erik; Rodríguez-Arellano, Martha Eunice; Posadas-Romero, Carlos; Vargas-Alarcón, Gilberto; Campos-Pérez, Francisco; Quiterio, Manuel; Salmerón-Castro, Jorge; Carnevale, Alessandra; Romero-Hidalgo, Sandra

2017-05-02

The aim of this study was to explore whether interactions between FTO rs9939609 and ABCA1 rs9282541 affect BMI and waist circumference (WC), and could explain previously reported population differences in FTO-obesity and FTO-BMI associations in the Mexican and European populations. A total of 3938 adults and 636 school-aged children from Central Mexico were genotyped for both polymorphisms. Subcutaneous and visceral adipose tissue biopsies from 22 class III obesity patients were analyzed for FTO and ABCA1 mRNA expression. Generalized linear models were used to test for associations and gene-gene interactions affecting BMI, WC and FTO expression. FTO and ABCA1 risk alleles were not individually associated with higher BMI or WC. However, in the absence of the ABCA1 risk allele, the FTO risk variant was significantly associated with higher BMI (P = 0.043) and marginally associated with higher WC (P = 0.067), as reported in Europeans. The gene-gene interaction affecting BMI and WC was statistically significant only in adults. FTO mRNA expression in subcutaneous abdominal adipose tissue according to ABCA1 genotype was consistent with these findings. This is the first report showing evidence of FTO and ABCA1 gene variant interactions affecting BMI, which may explain previously reported population differences. Further studies are needed to confirm this interaction.

Improved dual AAV vectors with reduced expression of truncated proteins are safe and effective in the retina of a mouse model of Stargardt disease

PubMed Central

Trapani, Ivana; Toriello, Elisabetta; de Simone, Sonia; Colella, Pasqualina; Iodice, Carolina; Polishchuk, Elena V.; Sommella, Andrea; Colecchi, Linda; Rossi, Settimio; Simonelli, Francesca; Giunti, Massimo; Bacci, Maria L.; Polishchuk, Roman S.; Auricchio, Alberto

2015-01-01

Stargardt disease (STGD1) due to mutations in the large ABCA4 gene is the most common inherited macular degeneration in humans. We have shown that dual adeno-associated viral (AAV) vectors effectively transfer ABCA4 to the retina of Abca4−/− mice. However, they express both lower levels of transgene compared with a single AAV and truncated proteins. To increase productive dual AAV concatemerization, which would overcome these limitations, we have explored the use of either various regions of homology or heterologous inverted terminal repeats (ITR). In addition, we tested the ability of various degradation signals to decrease the expression of truncated proteins. We found the highest levels of transgene expression using regions of homology based on either alkaline phosphatase or the F1 phage (AK). The use of heterologous ITR does not decrease the levels of truncated proteins relative to full-length ABCA4 and impairs AAV vector production. Conversely, the inclusion of the CL1 degradation signal results in the selective degradation of truncated proteins from the 5′-half without affecting full-length protein production. Therefore, we developed dual AAV hybrid ABCA4 vectors including homologous ITR2, the photoreceptor-specific G protein-coupled receptor kinase 1 promoter, the AK region of homology and the CL1 degradation signal. We show that upon subretinal administration these vectors are both safe in pigs and effective in Abca4−/− mice. Our data support the use of improved dual AAV vectors for gene therapy of STGD1. PMID:26420842

Improved dual AAV vectors with reduced expression of truncated proteins are safe and effective in the retina of a mouse model of Stargardt disease.

PubMed

Trapani, Ivana; Toriello, Elisabetta; de Simone, Sonia; Colella, Pasqualina; Iodice, Carolina; Polishchuk, Elena V; Sommella, Andrea; Colecchi, Linda; Rossi, Settimio; Simonelli, Francesca; Giunti, Massimo; Bacci, Maria L; Polishchuk, Roman S; Auricchio, Alberto

2015-12-01

Stargardt disease (STGD1) due to mutations in the large ABCA4 gene is the most common inherited macular degeneration in humans. We have shown that dual adeno-associated viral (AAV) vectors effectively transfer ABCA4 to the retina of Abca4-/- mice. However, they express both lower levels of transgene compared with a single AAV and truncated proteins. To increase productive dual AAV concatemerization, which would overcome these limitations, we have explored the use of either various regions of homology or heterologous inverted terminal repeats (ITR). In addition, we tested the ability of various degradation signals to decrease the expression of truncated proteins. We found the highest levels of transgene expression using regions of homology based on either alkaline phosphatase or the F1 phage (AK). The use of heterologous ITR does not decrease the levels of truncated proteins relative to full-length ABCA4 and impairs AAV vector production. Conversely, the inclusion of the CL1 degradation signal results in the selective degradation of truncated proteins from the 5'-half without affecting full-length protein production. Therefore, we developed dual AAV hybrid ABCA4 vectors including homologous ITR2, the photoreceptor-specific G protein-coupled receptor kinase 1 promoter, the AK region of homology and the CL1 degradation signal. We show that upon subretinal administration these vectors are both safe in pigs and effective in Abca4-/- mice. Our data support the use of improved dual AAV vectors for gene therapy of STGD1. © The Author 2015. Published by Oxford University Press.

Targeted inactivation of the murine Abca3 gene leads to respiratory failure in newborns with defective lamellar bodies

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

Hammel, Markus; Michel, Geert; Hoefer, Christina

2007-08-10

Mutations in the human ABCA3 gene, encoding an ABC-transporter, are associated with respiratory failure in newborns and pediatric interstitial lung disease. In order to study disease mechanisms, a transgenic mouse model with a disrupted Abca3 gene was generated by targeting embryonic stem cells. While heterozygous animals developed normally and were fertile, individuals homozygous for the altered allele (Abca3-/-) died within one hour after birth from respiratory failure, ABCA3 protein being undetectable. Abca3-/- newborns showed atelectasis of the lung in comparison to a normal gas content in unaffected or heterozygous littermates. Electron microscopy demonstrated the absence of normal lamellar bodies inmore » type II pneumocytes. Instead, condensed structures with apparent absence of lipid content were found. We conclude that ABCA3 is required for the formation of lamellar bodies and lung surfactant function. The phenotype of respiratory failure immediately after birth corresponds to the clinical course of severe ABCA3 mutations in human newborns.« less

Gene therapy for Stargardt disease associated with ABCA4 gene.

PubMed

Han, Zongchao; Conley, Shannon M; Naash, Muna I

2014-01-01

Mutations in the photoreceptor-specific flippase ABCA4 lead to accumulation of the toxic bisretinoid A2E, resulting in atrophy of the retinal pigment epithelium (RPE) and death of the photoreceptor cells. Many blinding diseases are associated with these mutations including Stargardt's disease (STGD1), cone-rod dystrophy, retinitis pigmentosa (RP), and increased susceptibility to age-related macular degeneration. There are no curative treatments for any of these dsystrophies. While the monogenic nature of many of these conditions makes them amenable to treatment with gene therapy, the ABCA4 cDNA is 6.8 kb and is thus too large for the AAV vectors which have been most successful for other ocular genes. Here we review approaches to ABCA4 gene therapy including treatment with novel AAV vectors, lentiviral vectors, and non-viral compacted DNA nanoparticles. Lentiviral and compacted DNA nanoparticles in particular have a large capacity and have been successful in improving disease phenotypes in the Abca4 (-/-) murine model. Excitingly, two Phase I/IIa clinical trials are underway to treat patients with ABCA4-associated Startgardt's disease (STGD1). As a result of the development of these novel technologies, effective therapies for ABCA4-associated diseases may finally be within reach.

Common variants near ABCA1, AFAP1 and GMDS confer risk of primary open-angle glaucoma

PubMed Central

Fogarty, Rhys; Sharma, Shiwani; Hewitt, Alex W.; Martin, Sarah; Law, Matthew H.; Cremin, Katie; Bailey, Jessica N. Cooke; Loomis, Stephanie J.; Pasquale, Louis R.; Haines, Jonathan L.; Hauser, Michael A.; Viswanathan, Ananth C.; McGuffin, Peter; Topouzis, Fotis; Foster, Paul J.; Graham, Stuart L; Casson, Robert J; Chehade, Mark; White, Andrew J; Zhou, Tiger; Souzeau, Emmanuelle; Landers, John; Fitzgerald, Jude T; Klebe, Sonja; Ruddle, Jonathan B; Goldberg, Ivan; Healey, Paul R; Mills, Richard A.; Wang, Jie Jin; Montgomery, Grant W.; Martin, Nicholas G.; Radford-Smith, Graham; Whiteman, David C.; Brown, Matthew A.; Wiggs, Janey L.; Mackey, David A; Mitchell, Paul; MacGregor, Stuart; Craig, Jamie E.

2014-01-01

Primary open-angle glaucoma (POAG) is a major cause of irreversible blindness worldwide. We performed a genome-wide association study in an Australian discovery cohort comprising 1,155 advanced POAG cases and 1,992 controls. Association of the top SNPs from the discovery stage was investigated in two Australian replication cohorts (total 932 cases, 6,862 controls) and two US replication cohorts (total 2,616 cases, 2,634 controls). Meta-analysis of all cohorts revealed three novel loci associated with development of POAG. These loci are located upstream of ABCA1 (rs2472493 [G] OR=1.31, P= 2.1 × 10−19), within AFAP1 (rs4619890 [G] OR=1.20, P= 7.0 × 10−10) and within GMDS (rs11969985 [G] OR=1.31, and P= 7.7 × 10−10). Using RT-PCR and immunolabelling, we also showed that these genes are expressed within human retina, optic nerve and trabecular meshwork and that ABCA1 and AFAP1 are also expressed in retinal ganglion cells. PMID:25173105

Mutations in GPR143/OA1 and ABCA4 Inform Interpretations of Short-Wavelength and Near-Infrared Fundus Autofluorescence

PubMed Central

Paavo, Maarjaliis; Zhao, Jin; Kim, Hye Jin; Lee, Winston; Zernant, Jana; Cai, Carolyn; Allikmets, Rando; Tsang, Stephen H.; Sparrow, Janet R.

2018-01-01

Purpose We sought to advance interpretations and quantification of short-wavelength fundus autofluorescence (SW-AF) emitted from bisretinoid lipofuscin and near-infrared autofluoresence (NIR-AF) originating from melanin. Methods Carriers of mutations in X-linked GPR143/OA1, a common form of ocular albinism; patients with confirmed mutations in ABCA4 conferring increased SW-AF; and subjects with healthy eyes were studied. SW-AF (488 nm excitation, 500–680 nm emission) and NIR-AF (excitation 787 nm, emission >830 nm) images were acquired with a confocal scanning laser ophthalmoscope. SW-AF images were analyzed for quantitative autofluoresence (qAF). Analogous methods of image acquisition and analysis were performed in albino and pigmented Abca4−/− mice and wild-type mice. Results Quantitation of SW-AF (qAF), construction of qAF color-coded maps, and examination of NIR-AF images from GPR143/OA1 carriers revealed mosaics in which patches of fundus exhibiting NIR-AF signal had qAF levels within normal limits whereas the hypopigmented areas in the NIR-AF image corresponded to foci of elevated qAF. qAF also was increased in albino versus pigmented mice. Although melanin contributes to fundus infrared reflectance, the latter appeared to be uniform in en face reflectance images of GPR143/OA1-carriers. In patients diagnosed with ABCA4-associated disease, NIR-AF increased in tandem with increased qAF originating in bisretinoid lipofuscin. Similarly in Abca4−/− mice having increased SW-AF, NIR-AF was more pronounced than in wild-type mice. Conclusions These studies corroborate RPE melanin as the major source of NIR-AF but also indicate that bisretinoid lipofuscin, when present at sufficient concentrations, contributes to the NIR-AF signal. Ocular melanin attenuates the SW-AF signal.

Overlap between Parkinson disease and Alzheimer disease in ABCA7 functional variants

PubMed Central

Nuytemans, Karen; Maldonado, Lizmarie; Ali, Aleena; John-Williams, Krista; Beecham, Gary W.; Martin, Eden; Scott, William K.

2016-01-01

Objective: Given their reported function in phagocytosis and clearance of protein aggregates in Alzheimer disease (AD), we hypothesized that variants in ATP-binding cassette transporter A7 (ABCA7) might be involved in Parkinson disease (PD). Methods: ABCA7 variants were identified using whole-exome sequencing (WES) on 396 unrelated patients with PD and 222 healthy controls. In addition, we used the publicly available WES data from the Parkinson's Progression Markers Initiative (444 patients and 153 healthy controls) as a second, independent data set. Results: We observed a higher frequency of loss-of-function (LOF) variants and rare putative highly functional variants (Combined Annotation Dependent Depletion [CADD] >20) in clinically diagnosed patients with PD than in healthy controls in both data sets. Overall, we identified LOF variants in 11 patients and 1 healthy control (odds ratio [OR] 4.94, Fisher exact p = 0.07). Four of these variants have been previously implicated in AD risk (p.E709AfsX86, p.W1214X, p.L1403RfsX7, and rs113809142). In addition, rare variants with CADD >20 were observed in 19 patients vs 3 healthy controls (OR 2.85, Fisher exact p = 0.06). Conclusion: The presence of ABCA7 LOF variants in clinically defined PD suggests that they might be risk factors for neurodegeneration in general, especially those variants hallmarked by protein aggregation. More studies will be needed to evaluate the overall impact of this transporter in neurodegenerative disease. PMID:27066581

Atheroprotective Effects of Methotrexate on Reverse Cholesterol Transport Proteins and Foam Cell Transformation in THP-1 Human Monocytes/Macrophages

PubMed Central

Reiss, Allison B.; Carsons, Steven E.; Anwar, Kamran; Rao, Soumya; Edelman, Sari D.; Zhang, Hongwei; Fernandez, Patricia; Cronstein, Bruce N.; Chan, Edwin S.L.

2008-01-01

OBJECTIVE: To determine whether MTX can overcome the atherogenic effect of COX-2 inhibitors and IFN-γ, both of which suppress cholesterol efflux protein levels and promote foam cell transformation in THP-1 human monocytes/macrophages. METHODS: Message and protein level of the reverse cholesterol transport (RCT) proteins cholesterol 27-hydroxylase and ABCA1 in THP-1 cells were evaluated by real-time polymerase chain reaction and immunoblot, respectively. Expression was evaluated in cells incubated in the presence or absence of the COX-2 inhibitor NS398 or IFN-γ with/without MTX. Foam cell transformation of lipid-loaded THP-1 macrophages was detected with oil red O staining and light microscopy. RESULTS: MTX increased 27-hydroxylase message and completely blocked NS398-induced downregulation of 27-hydroxylase (112.8±13.1% for NS398+MTX versus 71.1±4.3% for NS398 alone, with untreated as 100%, n=3, p<0.01). MTX also negated COX-2 inhibitor-mediated downregulation of ABCA1. Reversal of inhibitory effects on 27-hydroxylase and ABCA1 in the presence of MTX were blocked by the adenosine A2A receptor-specific antagonist ZM-241385. MTX also prevented NS398 and IFN-γ from increasing transformation of lipid-loaded THP-1 macrophages into foam cells. CONCLUSIONS: This study provides evidence supporting the atheroprotective effect of MTX. Through adenosine A2A receptor activation, MTX promotes RCT and limits foam cell formation in THP-1 macrophages. This is the first evidence that any commonly used medication can increase expression of anti-atherogenic RCT proteins and can counteract the effects of COX-2 inhibition. Our results suggest that one mechanism by which MTX protects against cardiovascular mortality in RA patients is through facilitation of cholesterol outflow from cells of the artery wall. PMID:19035488

Advanced glycation end products affect cholesterol homeostasis by impairing ABCA1 expression on macrophages.

PubMed

Kamtchueng Simo, Olivier; Ikhlef, Souade; Berrougui, Hicham; Khalil, Abdelouahed

2017-08-01

Reverse cholesterol transport (RCT), which is intimately linked to high-density lipoproteins (HDLs), plays a key role in cholesterol homeostasis and the prevention of atherosclerosis. The goal of the present study was to investigate the effect of aging and advanced glycation end products (AGEs) on RCT as well as on other factors that may affect the antiatherogenic property of HDLs. The transfer of macrophage-derived cholesterol to the plasma and liver and then to the feces for elimination was significantly lower in aged mice than in young mice. Chronic injection of d -galactose (D-gal) or AGEs also significantly reduced RCT (65.3% reduction in [ 3 H]cholesterol levels in the plasma of D-gal-treated mice after 48 h compared with control mice, P < 0.01). The injection of both D-gal and aminoguanidine hydrochloride increased [ 3 H]cholesterol levels in the plasma, although the levels were lower than those of control mice. The in vitro incubation of HDLs with dicarbonyl compounds increased the carbonyl and conjugated diene content of HDLs and significantly reduced PON1 paraoxonase activity (87.4% lower than control HDLs, P < 0.0001). Treating J774A.1 macrophages with glycated fetal bovine serum increased carbonyl formation (39.5% increase, P < 0.003) and reduced ABCA1 protein expression and the capacity of macrophages to liberate cholesterol (69.1% decrease, P < 0.0001). Our results showed, for the first time, that RCT is altered with aging and that AGEs contribute significantly to this alteration.

Allelic and Phenotypic Heterogeneity in ABCA4 mutations

PubMed Central

Burke, Tomas R; Tsang, Stephen H

2011-01-01

Since the discovery of the ABCA4 gene as the cause of autosomal recessive Stargardt disease/fundus flavimaculatus much has been written of the phenotypic variability in ABCA4 retinopathy. In this review the authors discuss the findings seen on examination and the disease features detected using various clinical tests. Important differential diagnoses are presented and unusual presentations of ABCA4 disease highlighted. PMID:21510770

Reduced Plasma HDL Cholesterol in Hyperthyroid Mice Coincides with Decreased Hepatic ABCA1 Expression

PubMed Central

TANCEVSKI, IVAN; WEHINGER, ANDREAS; DEMETZ, EGON; ELLER, PHILIPP; DUWENSEE, KRISTINA; HUBER, JULIA; HOCHEGGER, KATHRIN; SCHGOER, WILFRIED; FIEVET, CATHERINE; STELLAARD, FRANS; RUDLING, MATS; PATSCH, JOSEF R.; RITSCH, ANDREAS

2010-01-01

The aim of the study was to investigate the influence of severe hyperthyroidism on plasma high-density lipoprotein cholesterol (HDL-C). Recently, it was shown in mice that increasing doses of triiodothyronine (T3) upregulate hepatic expression of scavenger receptor-BI (SR-BI), resulting in increased clearance of plasma HDL-C. Here we show that severe hyperthyroidism in mice did not affect hepatic expression of SR-BI, but reduced hepatic expression of ATP-binding cassette transporter 1 (ABCA1), accompanied by a 40%-reduction of HDL-C. Sterol content of bile, liver and feces was markedly increased, accompanied by upregulation of hepatic CYP7A1, and ATP-binding cassette half-transporter ABCG5, which is known to promote biliary sterol secretion upon dimerization with ABCG8. Both control and hyperthyroid mice exerted identical plasma clearance of intravenously injected [3H] HDL-C, supporting the view that severe hyperthyroidism does not affect HDL-C clearance, but rather its formation via hepatic ABCA1. PMID:18388200

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

Regulation of Expression of abcA and Its Response to Environmental Conditions

PubMed Central

Villet, Regis A.; Truong-Bolduc, Que Chi; Wang, Yin; Estabrooks, Zoe; Medeiros, Heidi

2014-01-01

The ATP-dependent transporter gene abcA in Staphylococcus aureus confers resistance to hydrophobic β-lactams. In strain ISP794, abcA is regulated by the transcriptional regulators MgrA and NorG and shares a 420-nucleotide intercistronic region with the divergently transcribed pbp4 gene, which encodes the transpeptidase Pbp4. Exposure of exponentially growing cells to iron-limited media, oxidative stress, and acidic pH (5.5) for 0.5 to 2 h had no effect on abcA expression. In contrast, nutrient limitation produced a significant increase in abcA transcripts. We identified three additional regulators (SarA, SarZ, and Rot) that bind to the overlapping promoter region of abcA and pbp4 in strain MW2 and investigated their role in the regulation of abcA expression. Expression of abcA is decreased by 10.0-fold in vivo in a subcutaneous abscess model. In vitro, abcA expression depends on rot and sarZ regulators. Moenomycin A exposure of strain MW2 produced an increase in abcA transcripts. Relative to MW2, the MIC of moenomycin was decreased 8-fold for MW2ΔabcA and increased 10-fold for the MW2 abcA overexpresser, suggesting that moenomycin is a substrate of AbcA. PMID:24509312

High glucose upregulates BACE1-mediated Aβ production through ROS-dependent HIF-1α and LXRα/ABCA1-regulated lipid raft reorganization in SK-N-MC cells

PubMed Central

Lee, Hyun Jik; Ryu, Jung Min; Jung, Young Hyun; Lee, Sei-Jung; Kim, Jeong Yeon; Lee, Sang Hun; Hwang, In Koo; Seong, Je Kyung; Han, Ho Jae

2016-01-01

There is an accumulation of evidence indicating that the risk of Alzheimer’s disease is associated with diabetes mellitus, an indicator of high glucose concentrations in blood plasma. This study investigated the effect of high glucose on BACE1 expression and amyloidogenesis in vivo, and we present details of the mechanism associated with those effects. Our results, using ZLC and ZDF rat models, showed that ZDF rats have high levels of amyloid-beta (Aβ), phosphorylated tau, BACE1, and APP-C99. In vitro result with mouse hippocampal neuron and SK-N-MC, high glucose stimulated Aβ secretion and apoptosis in a dose-dependent manner. In addition, high glucose increased BACE1 and APP-C99 expressions, which were reversed by a reactive oxygen species (ROS) scavenger. Indeed, high glucose increased intracellular ROS levels and HIF-1α expression, associated with regulation of BACE1 and Liver X Receptor α (LXRα). In addition, high glucose induced ATP-binding cassette transporter A1 (ABCA1) down-regulation, was associated with LXR-induced lipid raft reorganization and BACE1 localization on the lipid raft. Furthermore, silencing of BACE1 expression was shown to regulate Aβ secretion and apoptosis of SK-N-MC. In conclusion, high glucose upregulates BACE1 expression and activity through HIF-1α and LXRα/ABCA1-regulated lipid raft reorganization, leading to Aβ production and apoptosis of SK-N-MC. PMID:27829662

Mutations in ABCA12 Underlie the Severe Congenital Skin Disease Harlequin Ichthyosis

PubMed Central

Kelsell, David P.; Norgett, Elizabeth E.; Unsworth, Harriet; Teh, Muy-Teck; Cullup, Thomas; Mein, Charles A.; Dopping-Hepenstal, Patricia J.; Dale, Beverly A.; Tadini, Gianluca; Fleckman, Philip; Stephens, Karen G.; Sybert, Virginia P.; Mallory, Susan B.; North, Bernard V.; Witt, David R.; Sprecher, Eli; E. M. Taylor, Aileen; Ilchyshyn, Andrew; Kennedy, Cameron T.; Goodyear, Helen; Moss, Celia; Paige, David; Harper, John I.; Young, Bryan D.; Leigh, Irene M.; Eady, Robin A. J.; O’Toole, Edel A.

2005-01-01

Harlequin ichthyosis (HI) is the most severe and frequently lethal form of recessive congenital ichthyosis. Although defects in lipid transport, protein phosphatase activity, and differentiation have been described, the genetic basis underlying the clinical and cellular phenotypes of HI has yet to be determined. By use of single-nucleotide–polymorphism chip technology and homozygosity mapping, a common region of homozygosity was observed in five patients with HI in the chromosomal region 2q35. Sequencing of the ABCA12 gene, which maps within the minimal region defined by homozygosity mapping, revealed disease-associated mutations, including large intragenic deletions and frameshift deletions in 11 of the 12 screened individuals with HI. Since HI epidermis displays abnormal lamellar granule formation, ABCA12 may play a critical role in the formation of lamellar granules and the discharge of lipids into the intercellular spaces, which would explain the epidermal barrier defect seen in this disorder. This finding paves the way for early prenatal diagnosis. In addition, functional studies of ABCA12 will lead to a better understanding of epidermal differentiation and barrier formation. PMID:15756637

Mutations in the ABCA4 (ABCR) gene are the major cause of autosomal recessive cone-rod dystrophy.

PubMed

Maugeri, A; Klevering, B J; Rohrschneider, K; Blankenagel, A; Brunner, H G; Deutman, A F; Hoyng, C B; Cremers, F P

2000-10-01

The photoreceptor cell-specific ATP-binding cassette transporter gene (ABCA4; previously denoted "ABCR") is mutated, in most patients, with autosomal recessive (AR) Stargardt disease (STGD1) or fundus flavimaculatus (FFM). In addition, a few cases with AR retinitis pigmentosa (RP) and AR cone-rod dystrophy (CRD) have been found to have ABCA4 mutations. To evaluate the importance of the ABCA4 gene as a cause of AR CRD, we selected 5 patients with AR CRD and 15 patients from Germany and The Netherlands with isolated CRD. Single-strand conformation-polymorphism analysis and sequencing revealed 19 ABCA4 mutations in 13 (65%) of 20 patients. In six patients, mutations were identified in both ABCA4 alleles; in seven patients, mutations were detected in one allele. One complex ABCA4 allele (L541P;A1038V) was found exclusively in German patients with CRD; one patient carried this complex allele homozygously, and five others were compound heterozygous. These findings suggest that mutations in the ABCA4 gene are the major cause of AR CRD. A primary role of the ABCA4 gene in STGD1/FFM and AR CRD, together with the gene's involvement in an as-yet-unknown proportion of cases with AR RP, strengthens the idea that mutations in the ABCA4 gene could be the most frequent cause of inherited retinal dystrophy in humans.

Atheroprotective effects of methotrexate on reverse cholesterol transport proteins and foam cell transformation in human THP-1 monocyte/macrophages.

PubMed

Reiss, Allison B; Carsons, Steven E; Anwar, Kamran; Rao, Soumya; Edelman, Sari D; Zhang, Hongwei; Fernandez, Patricia; Cronstein, Bruce N; Chan, Edwin S L

2008-12-01

To determine whether methotrexate (MTX) can overcome the atherogenic effects of cyclooxygenase 2 (COX-2) inhibitors and interferon-gamma (IFNgamma), both of which suppress cholesterol efflux protein and promote foam cell transformation in human THP-1 monocyte/macrophages. Message and protein levels of the reverse cholesterol transport proteins cholesterol 27-hydroxylase and ATP-binding cassette transporter A1 (ABCA1) in THP-1 cells were evaluated by real-time polymerase chain reaction and immunoblot, respectively. Expression was evaluated in cells incubated in the presence or absence of the COX-2 inhibitor NS398 or IFNgamma, with and without MTX. Foam cell transformation of lipid-laden THP-1 macrophages was detected with oil red O staining and light microscopy. MTX increased 27-hydroxylase message and completely blocked NS398-induced down-regulation of 27-hydroxylase (mean +/- SEM 112.8 +/- 13.1% for NS398 plus MTX versus 71.1 +/- 4.3% for NS398 alone; P < 0.01). MTX also negated COX-2 inhibitor-mediated down-regulation of ABCA1. The ability of MTX to reverse inhibitory effects on 27-hydroxylase and ABCA1 was blocked by the adenosine A2A receptor-specific antagonist ZM241385. MTX also prevented NS398 and IFNgamma from increasing transformation of lipid-laden THP-1 macrophages into foam cells. This study provides evidence supporting the notion of an atheroprotective effect of MTX. Through adenosine A2A receptor activation, MTX promotes reverse cholesterol transport and limits foam cell formation in THP-1 macrophages. This is the first reported evidence that any commonly used medication can increase expression of antiatherogenic reverse cholesterol transport proteins and can counteract the effects of COX-2 inhibition. Our results suggest that one mechanism by which MTX protects against cardiovascular disease in rheumatoid arthritis patients is through facilitation of cholesterol outflow from cells of the artery wall.

Mutations in the ABCA4 (ABCR) Gene Are the Major Cause of Autosomal Recessive Cone-Rod Dystrophy

PubMed Central

Maugeri, Alessandra; Klevering, B. Jeroen; Rohrschneider, Klaus; Blankenagel, Anita; Brunner, Han G.; Deutman, August F.; Hoyng, Carel B.; Cremers, Frans P. M.

2000-01-01

The photoreceptor cell–specific ATP-binding cassette transporter gene (ABCA4; previously denoted “ABCR”) is mutated in most patients with autosomal recessive (AR) Stargardt disease (STGD1) or fundus flavimaculatus (FFM). In addition, a few cases with AR retinitis pigmentosa (RP) and AR cone-rod dystrophy (CRD) have been found to have ABCA4 mutations. To evaluate the importance of the ABCA4 gene as a cause of AR CRD, we selected 5 patients with AR CRD and 15 patients with isolated CRD, all from Germany and The Netherlands . Single-strand conformation–polymorphism analysis and sequencing revealed 19 ABCA4 mutations in 13 (65%) of 20 patients. In six patients, mutations were identified in both ABCA4 alleles; in seven patients, mutations were detected in one allele. One complex ABCA4 allele (L541P;A1038V) was found exclusively in German patients with CRD; one patient carried this complex allele homozygously, and five others were compound heterozygous. These findings suggest that mutations in the ABCA4 gene are the major cause of AR CRD. A primary role of the ABCA4 gene in STGD1/FFM and AR CRD, together with the gene's involvement in an as-yet-unknown proportion of cases with AR RP, strengthens the idea that mutations in the ABCA4 gene could be the most frequent cause of inherited retinal dystrophy in humans. PMID:10958761

Presenting Papers at ABCA Conferences: Opinions and Recommendations.

ERIC Educational Resources Information Center

Mier, Denise; Myers, Robert

1981-01-01

Offers guidelines for preparing and presenting papers at American Business Communication Association (ABCA) conferences. Topics covered include: (1) types of delivery, (2) extemporaneous speaking, and (3) manuscript speaking. (FL)

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.

Ligand, receptor, and cell type-dependent regulation of ABCA1 and ABCG1 mRNA in prostate cancer epithelial cells

USDA-ARS?s Scientific Manuscript database

Recent evidence suggests that the liver X receptor (LXR) is a potential anti-cancer target in prostate carcinoma. There is little characterization, however, of how the two major isoforms LXRa or LXRß regulate the LXR-responsive genes ATP-binding cassette sub-family A 1 (ABCA1) and sub-family member ...

Phenotype/genotype correlation in a case series of Stargardt's patients identifies novel mutations in the ABCA4 gene.

PubMed

Gemenetzi, M; Lotery, A J

2013-11-01

To investigate phenotypic variability in terms of best-corrected visual acuity (BCVA) in patients with Stargardt disease (STGD) and confirmed ABCA4 mutations. Entire coding region analysis of the ABCA4 gene by direct sequencing of seven patients with clinical findings of STGD seen in the Retina Clinics of Southampton Eye Unit between 2002 and 2011.Phenotypic variables recorded were BCVA, fluorescein angiographic appearance, electrophysiology, and visual fields. All patients had heterozygous amino acid-changing variants (missense mutations) in the ABCA4 gene. A splice sequence change was found in a 30-year-old patient with severly affected vision. Two novel sequence changes were identified: a missense mutation in a mildly affected 44-year-old patient and a frameshift mutation in a severly affected 34-year-old patient. The identified ABCA4 mutations were compatible with the resulting phenotypes in terms of BCVA. Higher BCVAs were recorded in patients with missense mutations. Sequence changes, predicted to have more deleterious effect on protein function, resulted in a more severe phenotype. This case series of STGD patients demonstrates novel genotype/phenotype correlations, which may be useful to counselling of patients. This information may prove useful in selection of candidates for clinical trials in ABCA4 disease.

Extremely hypomorphic and severe deep intronic variants in the ABCA4 locus result in varying Stargardt disease phenotypes.

PubMed

Zernant, Jana; Lee, Winston; Nagasaki, Takayuki; Collison, Frederick T; Fishman, Gerald A; Bertelsen, Mette; Rosenberg, Thomas; Gouras, Peter; Tsang, Stephen H; Allikmets, Rando

2018-05-30

Autosomal recessive Stargardt disease (STGD1, MIM 248200) is caused by mutations in the ABCA4 gene. Complete sequencing of the ABCA4 locus in STGD1 patients identifies two expected disease-causing alleles in ~75% of patients and only one mutation in ~15% of patients. Recently, many possibly pathogenic variants in deep intronic sequences of ABCA4 have been identified in the latter group. We extended our analyses of deep intronic ABCA4 variants and determined that one of these, c.4253+43G>A (rs61754045), is present in 29/1155 (2.6%) of STGD1 patients. The variant is found at statistically significantly higher frequency in patients with only one pathogenic ABCA4 allele, 23/160 (14.38%), MAF=0.072, compared to MAF=0.013 in all STGD1 cases and MAF=0.006 in the matching general population (P<1x10-7). The variant, which is not predicted to have any effect on splicing, is the first reported intronic "extremely hypomorphic allele" in the ABCA4 locus; i.e., it is pathogenic only when in trans with a loss-of-function ABCA4 allele. It results in a distinct clinical phenotype characterized by late-onset of symptoms and foveal sparing. In ~70% of cases the variant was allelic with the c.6006-609T>A (rs575968112) variant, which was deemed non-pathogenic. Another rare deep intronic variant, c.5196+1056A>G (rs886044749), found in 5/834 (0.6%) of STGD1 cases is, conversely, a severe allele. This study determines pathogenicity for three non-coding variants in STGD1 patients of European descent accounting for ~3% of the disease. Defining disease-associated alleles in the non-coding sequences of the ABCA4 locus can be accomplished by integrated clinical and genetic analyses. Cold Spring Harbor Laboratory Press.

Genetic and Epigenetic Factors at COL2A1 and ABCA4 Influence Clinical Outcome in Congenital Toxoplasmosis

PubMed Central

Jamieson, Sarra E.; de Roubaix, Lee-Anne; Cortina-Borja, Mario; Tan, Hooi Kuan; Mui, Ernest J.; Cordell, Heather J.; Kirisits, Michael J.; Miller, E. Nancy; Peacock, Christopher S.; Hargrave, Aubrey C.; Coyne, Jessica J.; Boyer, Kenneth; Bessieres, Marie-Hélène; Buffolano, Wilma; Ferret, Nicole; Franck, Jacqueline; Kieffer, François; Meier, Paul; Nowakowska, Dorota E.; Paul, Malgorzata; Peyron, François; Stray-Pedersen, Babill; Prusa, Andrea-Romana; Thulliez, Philippe; Wallon, Martine; Petersen, Eskild; McLeod, Rima; Gilbert, Ruth E.; Blackwell, Jenefer M.

2008-01-01

Background Primary Toxoplasma gondii infection during pregnancy can be transmitted to the fetus. At birth, infected infants may have intracranial calcification, hydrocephalus, and retinochoroiditis, and new ocular lesions can occur at any age after birth. Not all children who acquire infection in utero develop these clinical signs of disease. Whilst severity of disease is influenced by trimester in which infection is acquired by the mother, other factors including genetic predisposition may contribute. Methods and Findings In 457 mother-child pairs from Europe, and 149 child/parent trios from North America, we show that ocular and brain disease in congenital toxoplasmosis associate with polymorphisms in ABCA4 encoding ATP-binding cassette transporter, subfamily A, member 4. Polymorphisms at COL2A1 encoding type II collagen associate only with ocular disease. Both loci showed unusual inheritance patterns for the disease allele when comparing outcomes in heterozygous affected children with outcomes in affected children of heterozygous mothers. Modeling suggested either an effect of mother's genotype, or parent-of-origin effects. Experimental studies showed that both ABCA4 and COL2A1 show isoform-specific epigenetic modifications consistent with imprinting. Conclusions These associations between clinical outcomes of congenital toxoplasmosis and polymorphisms at ABCA4 and COL2A1 provide novel insight into the molecular pathways that can be affected by congenital infection with this parasite. PMID:18523590

Quantitative targeted absolute proteomic analysis of transporters, receptors and junction proteins for validation of human cerebral microvascular endothelial cell line hCMEC/D3 as a human blood-brain barrier model.

PubMed

Ohtsuki, Sumio; Ikeda, Chiemi; Uchida, Yasuo; Sakamoto, Yumi; Miller, Florence; Glacial, Fabienne; Decleves, Xavier; Scherrmann, Jean-Michel; Couraud, Pierre-Olivier; Kubo, Yoshiyuki; Tachikawa, Masanori; Terasaki, Tetsuya

2013-01-07

Human cerebral microvascular endothelial cell line hCMEC/D3 is an established model of the human blood-brain barrier (BBB). The purpose of the present study was to determine, by means of quantitative targeted absolute proteomics, the protein expression levels in hCMEC/D3 cells of multiple transporters, receptors and junction proteins for comparison with our previously reported findings in isolated human brain microvessels. Among 91 target molecules, 12 transporters, 2 receptors, 1 junction protein and 1 membrane marker were present at quantifiable levels in plasma membrane fraction of hCMEC/D3 cells. ABCA2, MDR1, MRP4, BCRP, GLUT1, 4F2hc, MCT1, ENT1, transferrin and insulin receptors and claudin-5 were detected in both hCMEC/D3 cells and human brain microvessels. After normalization based on Na(+)/K(+) ATPase expression, the differences in protein expression levels between hCMEC/D3 cells and human brain microvessels were within 4-fold for these proteins, with the exceptions of ENT1, transferrin receptor and claudin-5. ABCA8, LAT1, LRP1 and γ-GTP were below the limit of quantification in the cells, but were found in human brain microvessels. ABCA3, ABCA6, MRP1 and ATA1 were found only in hCMEC/D3 cells. Furthermore, compared with human umbilical vein endothelial cells (HUVECs) as reference nonbrain endothelial cells, MDR1 was found only in hCMEC/D3 cells, and GLUT1 expression was 15-fold higher in hCMEC/D3 cells than in HUVECs. In conclusion, this is the first study to examine the suitability and limitations of the hCMEC/D3 cell line as a BBB functional model in terms of quantitative expression levels of transporters, receptors and tight junction proteins.

Increased Risk of Interstitial Lung Disease in Children with a Single R288K Variant of ABCA3

PubMed Central

Wittmann, Thomas; Frixel, Sabrina; Höppner, Stefanie; Schindlbeck, Ulrike; Schams, Andrea; Kappler, Matthias; Hegermann, Jan; Wrede, Christoph; Liebisch, Gerhard; Vierzig, Anne; Zacharasiewicz, Angela; Kopp, Matthias Volkmar; Poets, Christian F; Baden, Winfried; Hartl, Dominik; van Kaam, Anton H; Lohse, Peter; Aslanidis, Charalampos; Zarbock, Ralf; Griese, Matthias

2016-01-01

The ABCA3 gene encodes a lipid transporter in type II pneumocytes critical for survival and normal respiratory function. The frequent ABCA3 variant R288K increases the risk for neonatal respiratory distress syndrome among term and late preterm neonates, but its role in children’s interstitial lung disease has not been studied in detail. In a retrospective cohort study of 228 children with interstitial lung disease related to the alveolar surfactant system, the frequency of R288K was assessed and the phenotype of patients carrying a single R288K variant further characterized by clinical course, lung histology, computed tomography and bronchoalveolar lavage phosphatidylcholine PC 32:0. Cell lines stably transfected with ABCA3-R288K were analyzed for intracellular transcription, processing and targeting of the protein. ABCA3 function was assessed by detoxification assay of doxorubicin, and the induction and volume of lamellar bodies. We found nine children with interstitial lung disease carrying a heterozygous R288K variant, a frequency significantly higher than in the general Caucasian population. All identified patients had neonatal respiratory insufficiency, recovered and developed chronic interstitial lung disease with intermittent exacerbations during early childhood. In vitro analysis showed normal transcription, processing, and targeting of ABCA3-R288K, but impaired detoxification function and smaller lamellar bodies. We propose that the R288K variant can underlie interstitial lung disease in childhood due to reduced function of ABCA3, demonstrated by decelerated detoxification of doxorubicin, reduced PC 32:0 content and decreased lamellar body volume. PMID:26928390

Association of a homozygous nonsense mutation in the ABCA4 (ABCR) gene with cone-rod dystrophy phenotype in an Italian family.

PubMed

Simonelli, Francesca; Testa, Francesco; Zernant, Jana; Nesti, Anna; Rossi, Settimio; Rinaldi, Ernesto; Allikmets, Rando

2004-01-01

Genetic variation in the ABCA4 (ABCR) gene has been associated with several distinct retinal phenotypes, including Stargardt disease/fundus flavimaculatus (STGD/FFM), cone-rod dystrophy (CRD), retinitis pigmentosa (RP) and age-related macular degeneration. The current model of genotype/phenotype association suggests that patients harboring deleterious mutations in both ABCR alleles would develop RP-like retinal pathology. Here we describe ABCA4-associated phenotypes, including a proband with a homozygous nonsense mutation in a family from Southern Italy. The proband had been originally diagnosed with STGD. Ophthalmologic examination included kinetic perimetry, electrophysiological studies and fluorescein angiography. DNA of the affected individual and family members was analyzed for variants in all 50 exons of the ABCA4 gene by screening on the ABCR400 microarray. A homozygous nonsense mutation 2971G>T (G991X) was detected in a patient initially diagnosed with STGD based on funduscopic evidence, including bull's eye depigmentation of the fovea and flecks at the posterior pole extending to the mid-peripheral retina. Since this novel nucleotide substitution results in a truncated, nonfunctional, ABCA4 protein, the patient was examined in-depth for the severity of the disease phenotype. Indeed, subsequent electrophysiological studies determined severely reduced cone amplitude as compared to the rod amplitude, suggesting the diagnosis of CRD. ABCR400 microarray is an efficient tool for determining causal genetic variation, including new mutations. A homozygous protein-truncating mutation in ABCA4 can cause a phenotype ranging from STGD to CRD as diagnosed at an early stage of the disease. Only a combination of comprehensive genotype/phenotype correlation studies will determine the proper diagnosis and prognosis of ABCA4-associated pathology. Copyright 2004 S. Karger AG, Basel

Evaluation of the Association Between Common Genetic Variants Near the ABCA1 Gene and Primary Angle Closure Glaucoma in a Han Chinese Population.

PubMed

Luo, Huaichao; Chen, Yuhong; Ye, Zimeng; Sun, Xinghuai; Shi, Yi; Luo, Qian; Gong, Bo; Shuai, Ping; Yang, Jiyun; Zhou, Yu; Liu, Xiaoqi; Zhang, Kaijiong; Tan, Chang; Li, Yuanfeng; Lin, Ying; Yang, Zhenglin

2015-10-01

Recently, three large genome-wide association studies have identified multiple variants associated with primary open angle glaucoma (POAG) near the ABCA1 gene. Considering that POAG and primary angle closure glaucoma (PACG) share many similar clinical manifestations, the present study was conducted to investigate whether these genetic variants were also associated with PACG in a Han Chinese population. A case-control association study of 1122 cases (PACG/PAC) and 1311 normal, matched controls was undertaken. Seven single-nucleotide polymorphisms (SNPs) near the ABCA1 gene, including rs2422493, rs2487042, rs2472496, rs2472493, rs2487032, rs2472459, and rs2472519, were genotyped. Genotype and allele frequencies were assessed using χ² tests. Linkage disequilibrium (LD) structure was analyzed by computer software. Among the SNPs genotyped, no association was observed between these SNPs and PACG. However, we discovered that two haplotypes, CATTTAC (corrected P = 0.048) and CGCCCGC (corrected P = 0.048), remained significantly associated with PACG/PAC after Bonferroni correction. Subjects with the CATTTAC haplotype have a 1.71-fold increased possibility of having PACG/PAC, whereas subjects with the CGCCCGC haplotype have 0.47-fold decreased possibility of developing PACG. Our findings suggest that the genetic backgrounds of PACG and POAG might be different. However, whether or not ABCA1 plays a role in the development of PACG is still not made certain by this study. Thus, further research is needed to find the role of ABCA1 in the progress of PACG.

Seminal Plasma Characteristics and Expression of ATP-binding Cassette Transporter A1 (ABCA1) in Canine Spermatozoa from Ejaculates with Good and Bad Freezability.

PubMed

Schäfer-Somi, S; Palme, N

2016-04-01

The composition of seminal plasma and the localization of the ATP-binding cassette transporter A1 (ABCA1) in spermatozoa from good and bad freezers were compared to frozen-thawed spermatozoa from the same dog. Ejaculates were obtained from 31 stud dogs, and the sperm-rich fraction (SRF) was kept for analysis. One aliquot was used for the analysis of concentration, progressive motility (P; CASA), viability (V; CASA) and leucocyte count, and the analysis was performed by flow cytometry (FITC-PNA/PI), SCSA and HOST. In seminal plasma, concentration of albumin, cholesterol, calcium, inorganic phosphate, sodium, potassium, zinc and copper was measured. Semen smears were prepared and evaluated for the expression of ABCA1. The remainder of each ejaculate was frozen. After thawing, the quality assessment was repeated and further smears were prepared. According to post-thaw semen quality, dogs were assigned to good freezers (n = 20) or bad freezers (n = 11), the latter were defined as < 50% progressive motility and/or > 40% morphologically abnormal sperm and/or < 50% viability. Bad freezers were older than good freezers (5.3 vs 3.4 years, p < 0.05). In bad freezers, the percentage of sperm with ABCA1 signal in the acrosome was lower (26.3% vs 35.7%, p < 0.01) and the percentage of sperm with complete loss of ABCA1 signal higher (46.7% vs 30%, p < 0.01); the percentage of dead spermatozoa was higher (36.1% vs 25.5%, p < 0.05), and the concentration of cholesterol and sodium in seminal plasma was lower than in good freezers (p < 0.05). We conclude that in thawed bad freezer sperm, an increase in acrosome damages coincided with an increased loss of cholesterol transporters and cell death, and a lower cholesterol concentration in seminal plasma. Follow-up studies revealed whether a relation exists between these findings. © 2016 Blackwell Verlag GmbH.

The R230C variant of the ATP binding cassette protein A1 (ABCA1) gene is associated with a decreased response to glyburide therapy in patients with type 2 diabetes mellitus.

PubMed

Aguilar-Salinas, Carlos A; Muñoz-Hernandez, Linda Liliana; Cobos-Bonilla, Monica; Ramírez-Márquez, Marcos Rafael; Ordoñez-Sanchez, Maria Luisa; Mehta, Roopa; Medina-Santillan, Roberto; Tusie-Luna, Maria Teresa

2013-05-01

To test the hypothesis that persons with the R230C allele of ABCA1 show a decreased glycemic response to glyburide. This polymorphism is exclusively found in Ameri-indian populations and is associated with type 2 diabetes. This is a single blind controlled study including participants with type 2 diabetes (fasting glucose levels 126-250 mg/dl and HbA1c 7%-10%) managed with metformin and a lifestyle program. Each person with the risk allele (R230C) was matched by age, gender and BMI to three others with the wild type variant (R230R). Following a four week stabilization period, only participants with a greater than 70% adherence to metformin and a stable body weight were prescribed glyburide therapy for a further 16 weeks. The main outcome variable was the glyburide dose required to achieve treatment goals. No significant difference was observed in the glucose lowering effect of glyburide between subjects with the R230C and R230R alleles. However, the dose of sulfonylurea was significantly higher in the R230C participants compared with the R230R subjects (3.3±2.1 vs 6.3±5 mg/day, p<0.001). A higher percentage of R230C participants required at least 5mg of glyburide per day to achieve treatment goals. The glyburide dose was determined by the presence of the risk allele, among other factors. Patients with type 2 diabetes who have the R230C allele of ABCA1 needed a higher dose of glyburide in order to achieve the same glucose lowering effect as that in persons with the wild type variant. Copyright © 2013 Elsevier Inc. All rights reserved.

The impact of APOA5, APOB, APOC3 and ABCA1 gene polymorphisms on ischemic stroke: Evidence from a meta-analysis.

PubMed

Au, Anthony; Griffiths, Lyn R; Irene, Looi; Kooi, Cheah Wee; Wei, Loo Keat

2017-10-01

Genetic studies have been reported on the association between APOA5, APOB, APOC3 and ABCA1 gene polymorphisms and ischemic stroke, but results remain controversial. Hence, this meta-analysis aimed to infer the causal relationships of APOA5 (rs662799, rs3135506), APOB (rs693, rs1042031, rs1801701), APOC3 (rs4520, rs5128, rs2854116, rs2854117) and ABCA1 rs2230806 with ischemic stroke risk. A systematic review was performed for all the articles retrieved from multiple databases, up until March 2017. Data were extracted from all eligible studies, and meta-analysis was carried out using RevMan 5.3 and R package 3.2.1. The strength of association between each studied polymorphism and ischemic stroke risk was measured as odds ratios (ORs) and 95% confidence intervals (CIs), under fixed- and random-effect models. A total of 79 studies reporting on the association between the studied polymorphisms and ischemic stroke risk were identified. The pooled data indicated that all genetic models of APOA5 rs662799 (ORs = 1.23-1.43), allelic and over-dominant models of APOA5 rs3135506 (ORs = 1.77-1.97), APOB rs1801701 (ORs = 1.72-2.13) and APOB rs1042031 (ORs = 1.66-1.88) as well as dominant model of ABCA1 rs2230806 (OR = 1.31) were significantly associated with higher risk of ischemic stroke. However, no significant associations were observed between ischemic stroke and the other five polymorphisms, namely ApoB (rs693) and APOC3 (rs4520, rs5128, rs2854116 and rs2854117), under any genetic model. The present meta-analysis confirmed a significant association of APOA5 rs662799 CC, APOA5 rs3135506 CG, APOB rs1801701 GA, APOB rs1042031 GA and ABCA1 rs2230806 GG with increased risk of ischemic stroke. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of ABCA4 in mixed Spanish families segregating different retinal dystrophies.

PubMed

Paloma, Eva; Coco, Rosa; Martínez-Mir, Amalia; Vilageliu, Lluïsa; Balcells, Susana; Gonzàlez-Duarte, Roser

2002-12-01

Genotype-phenotype correlations highlighted the function of ABCA4 in retinitis pigmentosa (RP),cone-rod dystrophy (CRD) and Stargardt/Fundus Flavimaculatus disease (STGD/FFM). Initial screening of ABCA4 variants showed a correlation between the type of mutation and the severity of the disease. In the present study we have undertaken mutational and haplotype analysis of ABCA4 in three mixed pedigrees segregating different retinal dystrophies. In family I, we have shown cosegregation of different ABCA4 alleles with CRD (homozygosity for L1940P) and three subtypes of STGD/FFM. The first, a mild form, consisting on fundus flavimaculatus-like distribution of flecks, but good visual acuity and absence of dark choroid, was found to cosegregate with alleles R1097C and F553L; the second, a conventional Stargardt phenotype was associated to alleles L1940P/R1097C and the third, displaying severely reduced visual acuity and dark choroid (named FFM), was associated to L1940P/F553L. In family II, segregating STGD and RP phenotypes, while the involvement of ABCA4 in STGD seems clear this is not the case for RP. Finally, in family III, also segregating STGD and RP, ABCA4 fails to explain either phenotype. Our data highlight the wide allelic heterogeneity involving this gene and support the genetic variability (beyond ABCA4) of mixed STGD/RP pedigrees. Copyright 2002 Wiley-Liss, Inc.

Bilirubin Decreases Macrophage Cholesterol Efflux and ATP-Binding Cassette Transporter A1 Protein Expression.

PubMed

Wang, Dongdong; Tosevska, Anela; Heiß, Elke H; Ladurner, Angela; Mölzer, Christine; Wallner, Marlies; Bulmer, Andrew; Wagner, Karl-Heinz; Dirsch, Verena M; Atanasov, Atanas G

2017-04-28

Mild but chronically elevated circulating unconjugated bilirubin is associated with reduced total and low-density lipoprotein cholesterol concentration, which is associated with reduced cardiovascular disease risk. We aimed to investigate whether unconjugated bilirubin influences macrophage cholesterol efflux, as a potential mechanism for the altered circulating lipoprotein concentrations observed in hyperbilirubinemic individuals. Cholesterol efflux from THP-1 macrophages was assessed using plasma obtained from normo- and hyperbilirubinemic (Gilbert syndrome) humans (n=60 per group) or (heterozygote/homozygote Gunn) rats (n=20 per group) as an acceptor. Hyperbilirubinemic plasma from patients with Gilbert syndrome and Gunn rats induced significantly reduced cholesterol efflux compared with normobilirubinemic plasma. Unconjugated bilirubin (3-17.1 μmol/L) exogenously added to plasma- or apolipoprotein A1-supplemented media also decreased macrophage cholesterol efflux in a concentration- and time-dependent manner. We also showed reduced protein expression of the ATP-binding cassette transporter A1 (ABCA1), a transmembrane cholesterol transporter involved in apolipoprotein A1-mediated cholesterol efflux, in THP-1 macrophages treated with unconjugated bilirubin and in peripheral blood mononuclear cells obtained from hyperbilirubinemic individuals. Furthermore, we demonstrated that bilirubin accelerates the degradation rate of the ABCA1 protein in THP-1 macrophages. Cholesterol efflux from THP-1 macrophages is decreased in the presence of plasma obtained from humans and rats with mild hyperbilirubinemia. A direct effect of unconjugated bilirubin on cholesterol efflux was demonstrated and is associated with decreased ABCA1 protein expression. These data improve our knowledge concerning bilirubin's impact on cholesterol transport and represent an important advancement in our understanding of bilirubin's role in cardiovascular disease. © 2017 The Authors. Published on

Hepatic Overexpression of Endothelial Lipase Lowers HDL (High-Density Lipoprotein) but Maintains Reverse Cholesterol Transport in Mice: Role of SR-BI (Scavenger Receptor Class B Type I)/ABCA1 (ATP-Binding Cassette Transporter A1)-Dependent Pathways.

PubMed

Takiguchi, Shunichi; Ayaori, Makoto; Yakushiji, Emi; Nishida, Takafumi; Nakaya, Kazuhiro; Sasaki, Makoto; Iizuka, Maki; Uto-Kondo, Harumi; Terao, Yoshio; Yogo, Makiko; Komatsu, Tomohiro; Ogura, Masatsune; Ikewaki, Katsunori

2018-05-10

Reverse cholesterol transport (RCT) is a major mechanism by which HDL (high-density lipoprotein) protects against atherosclerosis. Endothelial lipase (EL) reportedly reduces HDL levels, which, in theory, would increase atherosclerosis. However, it remains unclear whether EL affects RCT in vivo. Adenoviral vectors expressing EL or luciferase were intravenously injected into mice, and a macrophage RCT assay was performed. As expected, hepatic EL overexpression markedly reduced HDL levels. In parallel, plasma 3 H-cholesterol counts from the EL-expressing mice decreased by 85% compared with control. Surprisingly, there was no difference in fecal 3 H-cholesterol excretion between the groups. Kinetic studies revealed increased catabolism/hepatic uptake of 3 HDL-cholesteryl ether, resulting in no change in fecal HDL-cholesteryl ester excretion in the mice. To explore underlying mechanisms for the preservation of RCT despite low HDL levels in the EL-expressing mice, we investigated the effects of hepatic SR-BI (scavenger receptor class B type I) knockdown. RCT assay revealed that knockdown of SR-BI alone reduced fecal excretion of macrophage-derived 3 H-cholesterol. Interestingly, hepatic EL overexpression under SR-BI inhibition further attenuated fecal tracer counts as compared with control. Finally, we observed that EL overexpression enhanced in vivo RCT under pharmacological inhibition of hepatic ABCA1 (ATP-binding cassette transporter A1) by probucol. Hepatic EL expression compensates for reduced macrophage-derived cholesterol efflux to plasma because of low HDL levels by promoting cholesterol excretion to bile/feces via an SR-BI pathway, maintaining overall RCT in vivo. In contrast, EL-modified HDL might negatively regulate RCT via hepatic ABCA1. Despite extreme hypoalphalipoproteinemia, RCT is maintained in EL-expressing mice via SR-BI/ABCA1-dependent pathways. © 2018 American Heart Association, Inc.

Synonymous ABCA3 Variants Do Not Increase Risk for Neonatal Respiratory Distress Syndrome

PubMed Central

Wambach, Jennifer A.; Wegner, Daniel J.; Heins, Hillary B.; Druley, Todd E.; Mitra, Robi D.; Hamvas, Aaron; Cole, F. Sessions

2014-01-01

Objective To determine whether synonymous variants in the adenosine triphosphate-binding cassette A3 transporter (ABCA3) gene increase the risk for neonatal respiratory distress syndrome (RDS) in term and late preterm infants of European and African descent. Study design Using next-generation pooled sequencing of race-stratified DNA samples from infants of European and African descent at $34 weeks gestation with and without RDS (n = 503), we scanned all exons of ABCA3, validated each synonymous variant with an independent genotyping platform, and evaluated race-stratified disease risk associated with common synonymous variants and collapsed frequencies of rare synonymous variants. Results The synonymous ABCA3 variant frequency spectrum differs between infants of European descent and those of African descent. Using in silico prediction programs and statistical strategies, we found no potentially disruptive synonymous ABCA3 variants or evidence of selection pressure. Individual common synonymous variants and collapsed frequencies of rare synonymous variants did not increase disease risk in term and late-preterm infants of European or African descent. Conclusion In contrast to rare, nonsynonymous ABCA3 mutations, synonymous ABCA3 variants do not increase the risk for neonatal RDS among term and late-preterm infants of European or African descent. PMID:24657120

Association of Brain DNA methylation in SORL1, ABCA7, HLA-DRB5, SLC24A4, and BIN1 with pathological diagnosis of Alzheimer disease.

PubMed

Yu, Lei; Chibnik, Lori B; Srivastava, Gyan P; Pochet, Nathalie; Yang, Jingyun; Xu, Jishu; Kozubek, James; Obholzer, Nikolaus; Leurgans, Sue E; Schneider, Julie A; Meissner, Alexander; De Jager, Philip L; Bennett, David A

2015-01-01

Recent large-scale genome-wide association studies have discovered several genetic variants associated with Alzheimer disease (AD); however, the extent to which DNA methylation in these AD loci contributes to the disease susceptibility remains unknown. To examine the association of brain DNA methylation in 28 reported AD loci with AD pathologies. Ongoing community-based clinical pathological cohort studies of aging and dementia (the Religious Orders Study and the Rush Memory and Aging Project) among 740 autopsied participants 66.0 to 108.3 years old. DNA methylation levels at individual CpG sites generated from dorsolateral prefrontal cortex tissue using a bead assay. Pathological diagnosis of AD by National Institute on Aging-Reagan criteria following a standard postmortem examination. Overall, 447 participants (60.4%) met the criteria for pathological diagnosis of AD. Brain DNA methylation in SORL1, ABCA7, HLA-DRB5, SLC24A4, and BIN1 was associated with pathological AD. The association was robustly retained after replacing the binary trait of pathological AD with 2 quantitative and molecular specific hallmarks of AD, namely, Aβ load and paired helical filament tau tangle density. Furthermore, RNA expression of transcripts of SORL1 and ABCA7 was associated with paired helical filament tau tangle density, and the expression of BIN1 was associated with Aβ load. Brain DNA methylation in multiple AD loci is associated with AD pathologies. The results provide further evidence that disruption of DNA methylation is involved in the pathological process of AD.

Molecular and cellular characteristics of ABCA3 mutations associated with diffuse parenchymal lung diseases in children

PubMed Central

Flamein, Florence; Riffault, Laure; Muselet-Charlier, Céline; Pernelle, Julie; Feldmann, Delphine; Jonard, Laurence; Durand-Schneider, Anne-Marie; Coulomb, Aurore; Maurice, Michèle; Nogee, Lawrence M.; Inagaki, Nobuya; Amselem, Serge; Dubus, Jean Christophe; Rigourd, Virginie; Brémont, François; Marguet, Christophe; Brouard, Jacques; de Blic, Jacques; Clement, Annick; Epaud, Ralph; Guillot, Loïc

2012-01-01

ABCA3 (ATP-binding cassette subfamily A, member 3) is expressed in the lamellar bodies of alveolar type II cells and is crucial to pulmonary surfactant storage and homeostasis. ABCA3 gene mutations have been associated with neonatal respiratory distress (NRD) and pediatric interstitial lung disease (ILD). The objective of this study was to look for ABCA3 gene mutations in patients with severe NRD and/or ILD. The 30 ABCA3 coding exons were screened in 47 patients with severe NRD and/or ILD. ABCA3 mutations were identified in 10 out of 47 patients, including 2 homozygous, 5 compound heterozygous and 3 heterozygous patients. SP-B and SP-C expression patterns varied across patients. Among patients with ABCA3 mutations, five died shortly after birth and five developed ILD (including one without NRD). Functional studies of p.D253H and p.T1173R mutations revealed that p.D253H and p.T1173R induced abnormal lamellar bodies. Additionally, p.T1173R increased IL-8 secretion in vitro. In conclusion, we identified new ABCA3 mutations in patients with life-threatening NRD and/or ILD. Two mutations associated with ILD acted via different pathophysiological mechanisms despite similar clinical phenotypes. PMID:22068586

Double hyperautofluorescent ring on fundus autofluorescence in ABCA4.

PubMed

Abalem, Maria Fernanda; Qian, Cynthia X; Branham, Kari; Schlegel, Dana; Fahim, Abigail T; Khan, Naheed W; Heckenlively, John R; Jayasundera, K Thiran

2018-01-01

We report an unusual phenotype in a child with a clinical diagnosis of recessive Stargardt disease (STGD1) and two pathogenic variants in the ABCA4 gene. Typically, the diagnosis of early-onset STGD1 is challenging because children may present with a variety of fundus changes and a variable rate of progression. At the time of his initial visit, the 6-year-old boy presented with 20/200 OD (right eye) and 20/150 OS (left eye), symmetrical mild foveal atrophy without flecks on fundus exam, and foveal hypoautofluorescence surrounded by a homogeneous hyperautofluorescent background on wide-field fundus autofluorescence. Over 4 years of follow-up, the retinal atrophy continued to progress, resulting in two well-defined and concentric hyperautofluorescent rings: one ring located at the posterior pole and the other located around the peripapillary region. Visual acuity also deteriorated to counting fingers at 4ft OD and 20/500 OS. To the best of our knowledge, this phenotype has not been previously described with the ABCA4 gene.

Heart ABCA1 and PPAR- α Genes Expression Responses in Male rats: Effects of High Intensity Treadmill Running Training and Aqueous Extraction of Black Crataegus-Pentaegyna.

PubMed

Ghanbari-Niaki, Abbass; Ghanbari-Abarghooi, Safieyh; Rahbarizadeh, Fatemeh; Zare-Kookandeh, Navabeh; Gholizadeh, Monireh; Roudbari, Fatemeh; Zare-Kookandeh, Asghar

2013-11-01

Heart as a high metabolic and aerobic tissue is consuming lipid as a fuel for its energy provision at rest during light and moderate exercise, except when lactate level is higher in blood circulation. It has been shown that any type of regular exercise and crataegus species would improve cardiovascular function and minimizes several risk factors via stimulating lipid metabolism by acting on enzymes and genes expression such as ABCA1 and PPAR α which are involving in this process. Twenty Wistar male rats (4-6 weeks old, 140-173 g weight) were used. Animals were randomly classified into training (n = 10) and control (n = 10) groups and then divided into saline-control (SC), saline-training (ST), Crataegus-Pentaegyna -control (CPC), and Crataegus-Pentaegyna -training (CPT) groups. Training groups have performed a high-intensity running program (at 34 m/min (0% grade), 60 min/day, 5 days/week) on a motor-driven treadmill for eight weeks. Animals were orally fed with Crataegus-Pentaegyna extraction (500mg/kg) and saline solution for six weeks. Seventy- two hours after the last training session, rats were sacrificed, hearts were excised, cleaned and immediately frozen in liquid nitrogen and stored at -80 °C until RNA extraction. Plasma also was collected for plasma variable measurements. Statistical analysis was performed using a two way analysis of variance, and significance was accepted at P < 0.05. A non-significant (P < 0.4, P < 0.79, respectively) increase in ABCA1 and PPAR α genes expression was accompanied by a significant (P < 0.01, P < 0.04, P < 0.04, respectively) reduction in TC, TG, and VLDL-C levels in Crataegus-Pentaegyna groups. Our findings show that a high intensity treadmill running was able to express ABCA1 and PPAR α in rat heart. Data also possibly indicate that the Crataeguse-Pentaegyna supplementation solely could mimic training effect on the mentioned genes and lipid profiles via different mechanism(s).

Heart ABCA1 and PPAR- α Genes Expression Responses in Male rats: Effects of High Intensity Treadmill Running Training and Aqueous Extraction of Black Crataegus-Pentaegyna

PubMed Central

Ghanbari-Niaki, Abbass; Ghanbari-Abarghooi, Safieyh; Rahbarizadeh, Fatemeh; Zare-Kookandeh, Navabeh; Gholizadeh, Monireh; Roudbari, Fatemeh; Zare-Kookandeh, Asghar

2013-01-01

Introduction: Heart as a high metabolic and aerobic tissue is consuming lipid as a fuel for its energy provision at rest during light and moderate exercise, except when lactate level is higher in blood circulation. It has been shown that any type of regular exercise and crataegus species would improve cardiovascular function and minimizes several risk factors via stimulating lipid metabolism by acting on enzymes and genes expression such as ABCA1 and PPAR α which are involving in this process. Materials and Methods: Twenty Wistar male rats (4-6 weeks old, 140-173 g weight) were used. Animals were randomly classified into training (n = 10) and control (n = 10) groups and then divided into saline-control (SC), saline-training (ST), Crataegus-Pentaegyna -control (CPC), and Crataegus-Pentaegyna -training (CPT) groups. Training groups have performed a high-intensity running program (at 34 m/min (0% grade), 60 min/day, 5 days/week) on a motor-driven treadmill for eight weeks. Animals were orally fed with Crataegus-Pentaegyna extraction (500mg/kg) and saline solution for six weeks. Seventy- two hours after the last training session, rats were sacrificed, hearts were excised, cleaned and immediately frozen in liquid nitrogen and stored at -80 °C until RNA extraction. Plasma also was collected for plasma variable measurements. Statistical analysis was performed using a two way analysis of variance, and significance was accepted at P < 0.05. Results: A non-significant (P < 0.4, P < 0.79, respectively) increase in ABCA1 and PPAR α genes expression was accompanied by a significant (P < 0.01, P < 0.04, P < 0.04, respectively) reduction in TC, TG, and VLDL-C levels in Crataegus-Pentaegyna groups. Conclusions: Our findings show that a high intensity treadmill running was able to express ABCA1 and PPAR α in rat heart. Data also possibly indicate that the Crataeguse-Pentaegyna supplementation solely could mimic training effect on the mentioned genes and lipid profiles via

Functional Validation of ABCA3 as a Miltefosine Transporter in Human Macrophages: IMPACT ON INTRACELLULAR SURVIVAL OF LEISHMANIA (VIANNIA) PANAMENSIS.

PubMed

Dohmen, Luuk C T; Navas, Adriana; Vargas, Deninson Alejandro; Gregory, David J; Kip, Anke; Dorlo, Thomas P C; Gomez, Maria Adelaida

2016-04-29

Within its mammalian host, Leishmania resides and replicates as an intracellular parasite. The direct activity of antileishmanials must therefore depend on intracellular drug transport, metabolism, and accumulation within the host cell. In this study, we explored the role of human macrophage transporters in the intracellular accumulation and antileishmanial activity of miltefosine (MLF), the only oral drug available for the treatment of visceral and cutaneous leishmaniasis (CL). Membrane transporter gene expression in primary human macrophages infected in vitro with Leishmania Viannia panamensis and exposed to MLF showed modulation of ABC and solute liquid carrier transporters gene transcripts. Among these, ABCA3, a lipid transporter, was significantly induced after exposure to MLF, and this induction was confirmed in primary macrophages from CL patients. Functional validation of MLF as a substrate for ABCA3 was performed by shRNA gene knockdown (KD) in THP-1 monocytes. Intracellular accumulation of radiolabeled MLF was significantly higher in ABCA3(KD) macrophages. ABCA3(KD) resulted in increased cytotoxicity induced by MLF exposure. ABCA3 gene expression inversely correlated with intracellular MLF content in primary macrophages from CL patients. ABCA3(KD) reduced parasite survival during macrophage infection with an L. V. panamensis strain exhibiting low in vitro susceptibility to MLF. Confocal microscopy showed ABCA3 to be located in the cell membrane of resting macrophages and in intracellular compartments in L. V. panamensis-infected cells. These results provide evidence of ABCA3 as an MLF efflux transporter in human macrophages and support its role in the direct antileishmanial effect of this alkylphosphocholine drug. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Single residue AAV capsid mutation improves transduction of photoreceptors in the Abca4-/- mouse and bipolar cells in the rd1 mouse and human retina ex vivo.

PubMed

De Silva, Samantha R; Charbel Issa, Peter; Singh, Mandeep S; Lipinski, Daniel M; Barnea-Cramer, Alona O; Walker, Nathan J; Barnard, Alun R; Hankins, Mark W; MacLaren, Robert E

2016-11-01

Gene therapy using adeno-associated viral (AAV) vectors for the treatment of retinal degenerations has shown safety and efficacy in clinical trials. However, very high levels of vector expression may be necessary for the treatment of conditions such as Stargardt disease where a dual vector approach is potentially needed, or in optogenetic strategies for end-stage degeneration in order to achieve maximal light sensitivity. In this study, we assessed two vectors with single capsid mutations, rAAV2/2(Y444F) and rAAV2/8(Y733F) in their ability to transduce retina in the Abca4 -/- and rd1 mouse models of retinal degeneration. We noted significantly increased photoreceptor transduction using rAAV2/8(Y733F) in the Abca4 -/- mouse, in contrast to previous work where vectors tested in this model have shown low levels of photoreceptor transduction. Bipolar cell transduction was achieved following subretinal delivery of both vectors in the rd1 mouse, and via intravitreal delivery of rAAV2/2(Y444F). The successful use of rAAV2/8(Y733F) to target bipolar cells was further validated on human tissue using an ex vivo culture system of retinal explants. Capsid mutant AAV vectors transduce human retinal cells and may be particularly suited to treat retinal degenerations in which high levels of transgene expression are required.

Interaction of Extracellular Domain 2 of the Human Retina-specific ATP-binding Cassette Transporter (ABCA4) with All-trans-retinal*

PubMed Central

Biswas-Fiss, Esther E.; Kurpad, Deepa S.; Joshi, Kinjalben; Biswas, Subhasis B.

2010-01-01

The retina-specific ATP-binding cassette (ABC) transporter, ABCA4, is essential for transport of all-trans-retinal from the rod outer segment discs in the retina and is associated with a broad range of inherited retinal diseases, including Stargardt disease, autosomal recessive cone rod dystrophy, and fundus flavimaculatus. A unique feature of the ABCA subfamily of ABC transporters is the presence of highly conserved, long extracellular loops or domains (ECDs) with unknown function. The high degree of sequence conservation and mapped disease-associated mutations in these domains suggests an important physiological significance. Conformational analysis using CD spectroscopy of purified, recombinant ECD2 protein demonstrated that it has an ordered and stable structure composed of 27 ± 3% α-helix, 20 ± 3% β-pleated sheet, and 53 ± 3% coil. Significant conformational changes were observed in disease-associated mutant proteins. Using intrinsic tryptophan fluorescence emission spectrum of ECD2 polypeptide and fluorescence anisotropy, we have demonstrated that this domain specifically interacts with all-trans-retinal. Furthermore, the retinal interaction appeared preferential for the all-trans-isomer and was directly measurable through fluorescence anisotropy analysis. Our results demonstrate that the three macular degeneration-associated mutations lead to significant changes in the secondary structure of the ECD2 domain of ABCA4, as well as in its interaction with all-trans-retinal. PMID:20404325

Novel mutations in CRB1 and ABCA4 genes cause Leber congenital amaurosis and Stargardt disease in a Swedish family

PubMed Central

Jonsson, Frida; Burstedt, Marie S; Sandgren, Ola; Norberg, Anna; Golovleva, Irina

2013-01-01

This study aimed to identify genetic mechanisms underlying severe retinal degeneration in one large family from northern Sweden, members of which presented with early-onset autosomal recessive retinitis pigmentosa and juvenile macular dystrophy. The clinical records of affected family members were analysed retrospectively and ophthalmological and electrophysiological examinations were performed in selected cases. Mutation screening was initially performed with microarrays, interrogating known mutations in the genes associated with recessive retinitis pigmentosa, Leber congenital amaurosis and Stargardt disease. Searching for homozygous regions with putative causative disease genes was done by high-density SNP-array genotyping, followed by segregation analysis of the family members. Two distinct phenotypes of retinal dystrophy, Leber congenital amaurosis and Stargardt disease were present in the family. In the family, four patients with Leber congenital amaurosis were homozygous for a novel c.2557C>T (p.Q853X) mutation in the CRB1 gene, while of two cases with Stargardt disease, one was homozygous for c.5461-10T>C in the ABCA4 gene and another was carrier of the same mutation and a novel ABCA4 mutation c.4773+3A>G. Sequence analysis of the entire ABCA4 gene in patients with Stargardt disease revealed complex alleles with additional sequence variants, which were evaluated by bioinformatics tools. In conclusion, presence of different genetic mechanisms resulting in variable phenotype within the family is not rare and can challenge molecular geneticists, ophthalmologists and genetic counsellors. PMID:23443024

Macular Pigment and Lutein Supplementation in ABCA4-associated Retinal Degenerations

PubMed Central

Aleman, Tomas S.; Cideciyan, Artur V.; Windsor, Elizabeth A. M.; Schwartz, Sharon B.; Swider, Malgorzata; Chico, John D.; Sumaroka, Alexander; Pantelyat, Alexander Y.; Duncan, Keith G.; Gardner, Leigh M.; Emmons, Jessica M.; Steinberg, Janet D.; Stone, Edwin M.; Jacobson, Samuel G.

2008-01-01

PURPOSE To determine macular pigment (MP) optical density (OD) in patients with ABCA4-associated retinal degenerations (ABCA4-RD) and the response of MP and vision to supplementation with lutein. METHODS Stargardt disease or cone-rod dystrophy patients with foveal fixation and with known or suspected disease-causing mutations in the ABCA4 gene were included. MPOD profiles were measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity and retinal thickness were quantified. Changes in MPOD and central vision were determined in a subset of patients receiving oral supplementation with lutein for 6 months. RESULTS MPOD in patients ranged from normal to markedly abnormal. As a group, ABCA4-RD patients had reduced foveal MPOD and there was strong correlation with retinal thickness. Average foveal tissue concentration of MP, estimated by dividing MPOD by retinal thickness, was normal in patients whereas serum concentration of lutein and zeaxanthin was significantly lower than normal. After oral lutein supplementation for 6 months, 91% of the patients showed significant increases in serum lutein and 63% of the patient eyes showed a significant augmentation in MPOD. The retinal responders tended to be female, and have lower serum lutein and zeaxanthin, lower MPOD and greater retinal thickness at baseline. Responding eyes had significantly lower baseline MP concentration compared to non-responding eyes. Central vision was unchanged after the period of supplementation. CONCLUSIONS MP is strongly affected by the stage of ABCA4 disease leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in some patients. There was no change in central vision after 6 months of lutein supplementation. Long-term influences on the natural history of this supplement on macular degenerations require further study. PMID:17325179

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

Microarray-based mutation analysis of the ABCA4 (ABCR) gene in autosomal recessive cone-rod dystrophy and retinitis pigmentosa.

PubMed

Klevering, B Jeroen; Yzer, Suzanne; Rohrschneider, Klaus; Zonneveld, Marijke; Allikmets, Rando; van den Born, L Ingeborgh; Maugeri, Alessandra; Hoyng, Carel B; Cremers, Frans P M

2004-12-01

Mutations in the ABCA4 gene have been associated with autosomal recessive Stargardt disease (STGD1), cone-rod dystrophy (CRD), and retinitis pigmentosa (RP). We employed a recently developed genotyping microarray, the ABCR400-chip, to search for known ABCA4 mutations in patients with isolated or autosomal recessive CRD (54 cases) or RP (90 cases). We performed detailed ophthalmologic examinations and identified at least one ABCA4 mutation in 18 patients (33%) with CRD and in five patients (5.6%) with RP. Single-strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing revealed four novel missense mutations (R24C, E161K, P597S, G618E) and a novel 1-bp deletion (5888delG). Ophthalmoscopic abnormalities in CRD patients ranged from minor granular pigmentary changes in the posterior pole to widespread atrophy. In 12 patients with recordable electroretinogram (ERG) tracings, a cone-rod pattern was detected. Three patients demonstrated progression from a retinal dystrophy resembling STGD1 to a more widespread degeneration, and were subsequently diagnosed as CRD. In addition to a variable degree of atrophy, all RP patients displayed ophthalmologic characteristics of classic RP. When detectable, ERG recordings in these patients demonstrated rod-cone patterns of photoreceptor degeneration. In conclusion, in this study, we show that the ABCA4 mutation chip is an efficient first screening tool for arCRD.

Clinical and genetic analyses reveal novel pathogenic ABCA4 mutations in Stargardt disease families

PubMed Central

Lin, Bing; Cai, Xue-Bi; Zheng, Zhi-Li; Huang, Xiu-Feng; Liu, Xiao-Ling; Qu, Jia; Jin, Zi-Bing

2016-01-01

Stargardt disease (STGD1) is a juvenile macular degeneration predominantly inherited in an autosomal recessive pattern, characterized by decreased central vision in the first 2 decades of life. The condition has a genetic basis due to mutation in the ABCA4 gene, and arises from the deposition of lipofuscin-like substance in the retinal pigmented epithelium (RPE) with secondary photoreceptor cell death. In this study, we describe the clinical and genetic features of Stargardt patients from four unrelated Chinese cohorts. The targeted exome sequencing (TES) was carried out in four clinically confirmed patients and their family members using a gene panel comprising 164 known causative inherited retinal dystrophy (IRD) genes. Genetic analysis revealed eight ABCA4 mutations in all of the four pedigrees, including six mutations in coding exons and two mutations in adjacent intronic areas. All the affected individuals showed typical manifestations consistent with the disease phenotype. We disclose two novel ABCA4 mutations in Chinese patients with STGD disease, which will expand the existing spectrum of disease-causing variants and will further aid in the future mutation screening and genetic counseling, as well as in the understanding of phenotypic and genotypic correlations. PMID:27739528

[A novel compound heterozygous mutation in ABCA3 gene in a child with diffuse parenchymal lung disease].

PubMed

Bao, Y M; Liu, X L; Liu, X L; Chen, J H; Zheng, Y J

2017-11-02

Objective: To summarize the clinical characteristics of the diffuse parenchymal lung diseases in a child caused by a novel compound heterozygous ABCA3 mutation and explore the association between the phenotype and ABCA3 mutation. Method: The clinical material of a patient diagnosed with diffuse parenchymal lung disease with ABCA3 mutation in December 2016 in Shenzhen Children's Hospital was analyzed. The information about ABCA3 gene mutation updated before April, 2017 was searched and collected from the gene databases (including 1000Genomes, HGMD, EXAC) and the literatures (including Wanfang Chinese database and Pubmed). Result: The girl was one year and nine months old. She presented with chronic cough, tachypnea, cyanosis and failure to thrive since she was one year and three months old. Her condition gradually deteriorated after she was empirically treated. Physical examination showed malnutrition, tachypnea and clubbed-fingers. Her high resolution computed tomography (HRCT) revealed diffused ground-glass opacities, thickened interlobular septum, and multiple subpleural small air-filled lung cysts. The second generation sequencing study identified a novel compound heterozygous mutation (c.1755delC+c.2890G>A) in her ABCA3 gene, which derived respectively from her parents and has not been reported in the database and the literatures mentioned above. Conclusion: c.1755delC+c.2890G>A is a new kind of compound heterozygous mutation in ABCA3, which can cause children's diffuse parenchymal lung disease. Its phenotype is related to its genotype.

Does soy protein affect circulating levels of unbound IGF-1?

PubMed

Messina, Mark; Magee, Pamela

2018-03-01

Despite the enormous amount of research that has been conducted on the role of soyfoods in the prevention and treatment of chronic disease, the mechanisms by which soy exerts its physiological effects are not fully understood. The clinical data show that neither soyfoods nor soy protein nor isoflavones affect circulating levels of reproductive hormones in men or women. However, some research suggests that soy protein, but not isoflavones, affects insulin-like growth factor I (IGF-1). Since IGF-1 may have wide-ranging physiological effects, we sought to determine the effect of soy protein on IGF-1 and its major binding protein insulin-like growth factor-binding protein (IGFBP-3). Six clinical studies were identified that compared soy protein with a control protein, albeit only two studies measured IGFBP-3 in addition to IGF-1. Although the data are difficult to interpret because of the different experimental designs employed, there is some evidence that large amounts of soy protein (>25 g/day) modestly increase IGF-1 levels above levels observed with the control protein. The clinical data suggest that a decision to incorporate soy into the diet should not be based on its possible effects on IGF-1.

Non-exomic and synonymous variants in ABCA4 are an important cause of Stargardt disease

PubMed Central

Braun, Terry A.; Mullins, Robert F.; Wagner, Alex H.; Andorf, Jeaneen L.; Johnston, Rebecca M.; Bakall, Benjamin B.; Deluca, Adam P.; Fishman, Gerald A.; Lam, Byron L.; Weleber, Richard G.; Cideciyan, Artur V.; Jacobson, Samuel G.; Sheffield, Val C.; Tucker, Budd A.; Stone, Edwin M.

2013-01-01

Mutations in ABCA4 cause Stargardt disease and other blinding autosomal recessive retinal disorders. However, sequencing of the complete coding sequence in patients with clinical features of Stargardt disease sometimes fails to detect one or both mutations. For example, among 208 individuals with clear clinical evidence of ABCA4 disease ascertained at a single institution, 28 had only one disease-causing allele identified in the exons and splice junctions of the primary retinal transcript of the gene. Haplotype analysis of these 28 probands revealed 3 haplotypes shared among ten families, suggesting that 18 of the 28 missing alleles were rare enough to be present only once in the cohort. We hypothesized that mutations near rare alternate splice junctions in ABCA4 might cause disease by increasing the probability of mis-splicing at these sites. Next-generation sequencing of RNA extracted from human donor eyes revealed more than a dozen alternate exons that are occasionally incorporated into the ABCA4 transcript in normal human retina. We sequenced the genomic DNA containing 15 of these minor exons in the 28 one-allele subjects and observed five instances of two different variations in the splice signals of exon 36.1 that were not present in normal individuals (P < 10−6). Analysis of RNA obtained from the keratinocytes of patients with these mutations revealed the predicted alternate transcript. This study illustrates the utility of RNA sequence analysis of human donor tissue and patient-derived cell lines to identify mutations that would be undetectable by exome sequencing. PMID:23918662

Deducing the pathogenic contribution of recessive ABCA4 alleles in an outbred population.

PubMed

Schindler, Emily I; Nylen, Erik L; Ko, Audrey C; Affatigato, Louisa M; Heggen, Andrew C; Wang, Kai; Sheffield, Val C; Stone, Edwin M

2010-10-01

Accurate prediction of the pathogenic effects of specific genotypes is important for the design and execution of clinical trials as well as for meaningful counseling of individual patients. However, for many autosomal recessive diseases, it can be difficult to deduce the relative pathogenic contribution of individual alleles because relatively few affected individuals share the same two disease-causing variations. In this study, we used multiple regression analysis to estimate the pathogenicity of specific alleles of ABCA4 in patients with retinal phenotypes ranging from Stargardt disease to retinitis pigmentosa. This analysis revealed quantitative allelic effects on two aspects of the visual phenotype, visual acuity (P < 10(-3)) and visual field (P < 10(-7)). Discordance between visual acuity and visual field in individual patients suggests the existence of at least two non-ABCA4 modifying factors. The findings of this study will facilitate the discovery of factors that modify ABCA4 disease and will also aid in the optimal selection of subjects for clinical trials of new therapies.

Outcome of ABCA4 disease-associated alleles in autosomal recessive retinal dystrophies: retrospective analysis in 420 Spanish families.

PubMed

Riveiro-Alvarez, Rosa; Lopez-Martinez, Miguel-Angel; Zernant, Jana; Aguirre-Lamban, Jana; Cantalapiedra, Diego; Avila-Fernandez, Almudena; Gimenez, Ascension; Lopez-Molina, Maria-Isabel; Garcia-Sandoval, Blanca; Blanco-Kelly, Fiona; Corton, Marta; Tatu, Sorina; Fernandez-San Jose, Patricia; Trujillo-Tiebas, Maria-Jose; Ramos, Carmen; Allikmets, Rando; Ayuso, Carmen

2013-11-01

To provide a comprehensive overview of all detected mutations in the ABCA4 gene in Spanish families with autosomal recessive retinal disorders, including Stargardt's disease (arSTGD), cone-rod dystrophy (arCRD), and retinitis pigmentosa (arRP), and to assess genotype-phenotype correlation and disease progression in 10 years by considering the type of variants and age at onset. Case series. A total of 420 unrelated Spanish families: 259 arSTGD, 86 arCRD, and 75 arRP. Spanish families were analyzed through a combination of ABCR400 genotyping microarray, denaturing high-performance liquid chromatography, and high-resolution melting scanning. Direct sequencing was used as a confirmation technique for the identified variants. Screening by multiple ligation probe analysis was used to detect possible large deletions or insertions in the ABCA4 gene. Selected families were analyzed further by next generation sequencing. DNA sequence variants, mutation detection rates, haplotypes, age at onset, central or peripheral vision loss, and night blindness. Overall, we detected 70.5% and 36.6% of all expected ABCA4 mutations in arSTGD and arCRD patient cohorts, respectively. In the fraction of the cohort where the ABCA4 gene was sequenced completely, the detection rates reached 73.6% for arSTGD and 66.7% for arCRD. However, the frequency of possibly pathogenic ABCA4 alleles in arRP families was only slightly higher than that in the general population. Moreover, in some families, mutations in other known arRP genes segregated with the disease phenotype. An increasing understanding of causal ABCA4 alleles in arSTGD and arCRD facilitates disease diagnosis and prognosis and also is paramount in selecting patients for emerging clinical trials of therapeutic interventions. Because ABCA4-associated diseases are evolving retinal dystrophies, assessment of age at onset, accurate clinical diagnosis, and genetic testing are crucial. We suggest that ABCA4 mutations may be associated with a

Identification of a Novel Mutation in the ABCA4 Gene in a Chinese Family with Retinitis Pigmentosa Using Exome Sequencing.

PubMed

Huang, Xiangjun; Yuan, Lamei; Xu, Hongbo; Zheng, Wen; Cao, Yanna; Yi, Junhui; Guo, Yi; Yang, Zhijian; Li, Yu; Deng, Hao

2018-02-05

Retinitis pigmentosa (RP) is a group of hereditary, degenerative retinal disorders characterized by progressive retinal dysfunction, outer retina cell loss, and retinal tissue atrophy. It eventually leads to tunnel vision and legal, or total blindness. Here we aimed to reveal the causal gene and mutation contributing to the development of autosomal recessive RP (arRP) in a consanguineous family. A novel homozygous mutation, c.4845delT (p.K1616Rfs*46), in the ATP-binding cassette subfamily A member 4gene ( ABCA4 ) was identified. It may reduce ABCA4 protein activity, leading to progressive degeneration of both rod and cone photoreceptors. The study extends the arRP genotypic spectrum and confirms a genotype-phenotype relationship. This study may also disclose some new clues for RP genetic causes and pathogenesis, as well as clinical and genetic diagnosis. The research findings may contribute to improvement in clinical care, therapy, genetic screening, and counseling. ©2018 The Author(s).

HIV-1 Tat protein induces glial cell autophagy through enhancement of BAG3 protein levels.

PubMed

Bruno, Anna Paola; De Simone, Francesca Isabella; Iorio, Vittoria; De Marco, Margot; Khalili, Kamel; Sariyer, Ilker Kudret; Capunzo, Mario; Nori, Stefania Lucia; Rosati, Alessandra

2014-01-01

BAG3 protein has been described as an anti-apoptotic and pro-autophagic factor in several neoplastic and normal cells. We previously demonstrated that BAG3 expression is elevated upon HIV-1 infection of glial and T lymphocyte cells. Among HIV-1 proteins, Tat is highly involved in regulating host cell response to viral infection. Therefore, we investigated the possible role of Tat protein in modulating BAG3 protein levels and the autophagic process itself. In this report, we show that transfection with Tat raises BAG3 levels in glioblastoma cells. Moreover, BAG3 silencing results in highly reducing Tat- induced levels of LC3-II and increasing the appearance of sub G0/G1 apoptotic cells, in keeping with the reported role of BAG3 in modulating the autophagy/apoptosis balance. These results demonstrate for the first time that Tat protein is able to stimulate autophagy through increasing BAG3 levels in human glial cells.

Celecoxib sensitizes imatinib-resistant K562 cells to imatinib by inhibiting MRP1-5, ABCA2 and ABCG2 transporters via Wnt and Ras signaling pathways.

PubMed

Dharmapuri, Gangappa; Doneti, Ravinder; Philip, Gundala Harold; Kalle, Arunasree M

2015-07-01

Imatinib mesylate, a tyrosine kinase inhibitor, is very effective in the treatment of chronic myeloid leukemia (CML). However, development of resistance to imatinib therapy is also a very common mechanism observed with long-term administration of the drug. Our previous studies have highlighted the role of cyclooxygenase-2 (COX-2) in regulating the expression of multidrug resistant protein-1 (MDR1), P-gp, in imatinib-resistant K562 cells (IR-K562) via PGE2-cAMP-PKC-NF-κB pathway and inhibition of COX-2 by celecoxib, a COX-2 specific inhibitor, inhibits this pathway and reverses the drug resistance. Studies have identified that not only MDR1 but other ATP-binding cassette transport proteins (ABC transporters) are involved in the development of imatinib resistance. Here, we tried to study the role of COX-2 in the regulation of other ABC transporters such as MRP1, MRP2, MRP3, ABCA2 and ABCG2 that have been already implicated in imatinib resistance development. The results of the study clearly indicated that overexpression of COX-2 lead to upregulation of MRP family proteins in IR-K562 cells and celecoxib down-regulated the ABC transporters through Wnt and MEK signaling pathways. The study signifies that celecoxib in combination with the imatinib can be a good alternate treatment strategy for the reversal of imatinib resistance. Copyright © 2015 Elsevier Ltd. All rights reserved.

IL-17A, MCP-1, CCR-2, and ABCA1 polymorphisms in children with non-alcoholic fatty liver disease.

PubMed

Akbulut, Ulas Emre; Emeksiz, Hamdi Cihan; Citli, Senol; Cebi, Alper Han; Korkmaz, Hatice Ayca Ata; Baki, Gaye

2018-05-05

The prevalence of non-alcoholic fatty liver disease in children has risen significantly, owing to the worldwide childhood obesity epidemic in the last two decades. Non-alcoholic fatty liver disease is closely linked to sedentary lifestyle, increased body mass index, and visceral adiposity. In addition, individual genetic variations also have a role in the development and progression of non-alcoholic fatty liver disease. The aim of this study was to investigate the gene polymorphisms of MCP-1 (-2518 A/G) (rs1024611), CCR-2 (190 G/A) (rs1799864), ABCA1 (883 G/A) (rs4149313), and IL-17A (-197 G/A) (rs2275913) in obese Turkish children with non-alcoholic fatty liver disease. The study recruited 186 obese children aged 10-17 years, including 101 children with non-alcoholic fatty liver disease and 85 children without non-alcoholic fatty liver disease. Anthropometric measurements, insulin resistance, a liver panel, a lipid profile, liver ultrasound examination, and genotyping of the four variants were performed. No difference was found between the groups in respect to age and gender, body mass index, waist/hip ratio, or body fat ratio. In addition to the elevated ALT levels, AST and GGT levels were found significantly higher in the non-alcoholic fatty liver disease group compared to the non non-alcoholic fatty liver disease group (p<0.05). The A-allele of IL-17A (-197 G/A) (rs2275913) was associated with non-alcoholic fatty liver disease (odds ratio 2.05, 95% confidence interval: 1.12-3.77, p=0.02). The findings of this study suggest that there may be an association between IL-17A (-197 G/A) (rs2275913) polymorphism and non-alcoholic fatty liver disease development in obese Turkish children. Copyright © 2018 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Phenotypic spectrum of autosomal recessive cone-rod dystrophies caused by mutations in the ABCA4 (ABCR) gene.

PubMed

Klevering, B Jeroen; Blankenagel, Anita; Maugeri, Alessandra; Cremers, Frans P M; Hoyng, Carel B; Rohrschneider, Klaus

2002-06-01

To describe the phenotype of 12 patients with autosomal recessive or isolated cone-rod types of progressive retinal degeneration (CRD) caused by mutations in the ABCA4 gene. The charts of patients who had originally received a diagnosis of isolated or autosomal recessive CRD were reviewed after molecular analysis revealed mutations in the ABCA4 gene. In two of the patients both the photopic and scotopic electroretinogram were nonrecordable. In the remainder, the photopic cone b-wave amplitudes appeared to be more seriously affected than the scotopic rod b-wave amplitudes. Although the clinical presentation was heterogeneous, all patients experienced visual loss early in life, impaired color vision, and a central scotoma. Fundoscopy revealed evidence of early-onset maculopathy, sometimes accompanied by involvement of the retinal periphery in the later stages of the disease. Mutations in the ABCA4 gene are the pathologic cause of the CRD-like dystrophy in these patients, and the resultant clinical pictures are complex and heterogeneous. Given this wide clinical spectrum of CRD-like phenotypes associated with ABCA4 mutations, detailed clinical subclassifications are difficult and may not be very useful.

Mutation Spectrum of the ABCA4 Gene in a Greek Cohort with Stargardt Disease: Identification of Novel Mutations and Evidence of Three Prevalent Mutated Alleles

PubMed Central

Vassiliki, Kokkinou; George, Koutsodontis; Polixeni, Stamatiou; Christoforos, Giatzakis; Minas, Aslanides Ioannis; Stavrenia, Koukoula; Ioannis, Datseris

2018-01-01

Aim To evaluate the frequency and pattern of disease-associated mutations of ABCA4 gene among Greek patients with presumed Stargardt disease (STGD1). Materials and Methods A total of 59 patients were analyzed for ABCA4 mutations using the ABCR400 microarray and PCR-based sequencing of all coding exons and flanking intronic regions. MLPA analysis as well as sequencing of two regions in introns 30 and 36 reported earlier to harbor deep intronic disease-associated variants was used in 4 selected cases. Results An overall detection rate of at least one mutant allele was achieved in 52 of the 59 patients (88.1%). Direct sequencing improved significantly the complete characterization rate, that is, identification of two mutations compared to the microarray analysis (93.1% versus 50%). In total, 40 distinct potentially disease-causing variants of the ABCA4 gene were detected, including six previously unreported potentially pathogenic variants. Among the disease-causing variants, in this cohort, the most frequent was c.5714+5G>A representing 16.1%, while p.Gly1961Glu and p.Leu541Pro represented 15.2% and 8.5%, respectively. Conclusions By using a combination of methods, we completely molecularly diagnosed 48 of the 59 patients studied. In addition, we identified six previously unreported, potentially pathogenic ABCA4 mutations. PMID:29854428

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

Local TNF causes NFATc1-dependent cholesterol-mediated podocyte injury

PubMed Central

Pedigo, Christopher E.; Ducasa, Gloria Michelle; Leclercq, Farah; Sloan, Alexis; Hashmi, Tahreem; Molina-David, Judith; Ge, Mengyuan; Lassenius, Mariann I.; Groop, Per-Henrik; Kretzler, Matthias; Martini, Sebastian; Reich, Heather; Wahl, Patricia; Ghiggeri, GianMarco; Burke, George W.; Kretz, Oliver; Huber, Tobias B.; Mendez, Armando J.; Merscher, Sandra

2016-01-01

High levels of circulating TNF and its receptors, TNFR1 and TNFR2, predict the progression of diabetic kidney disease (DKD), but their contribution to organ damage in DKD remains largely unknown. Here, we investigated the function of local and systemic TNF in podocyte injury. We cultured human podocytes with sera collected from DKD patients, who displayed elevated TNF levels, and focal segmental glomerulosclerosis (FSGS) patients, whose TNF levels resembled those of healthy patients. Exogenous TNF administration or local TNF expression was equally sufficient to cause free cholesterol–dependent apoptosis in podocytes by acting through a dual mechanism that required a reduction in ATP-binding cassette transporter A1–mediated (ABCA1-mediated) cholesterol efflux and reduced cholesterol esterification by sterol-O-acyltransferase 1 (SOAT1). TNF-induced albuminuria was aggravated in mice with podocyte-specific ABCA1 deficiency and was partially prevented by cholesterol depletion with cyclodextrin. TNF-stimulated free cholesterol–dependent apoptosis in podocytes was mediated by nuclear factor of activated T cells 1 (NFATc1). ABCA1 overexpression or cholesterol depletion was sufficient to reduce albuminuria in mice with podocyte-specific NFATc1 activation. Our data implicate an NFATc1/ABCA1-dependent mechanism in which local TNF is sufficient to cause free cholesterol–dependent podocyte injury irrespective of TNF, TNFR1, or TNFR2 serum levels. PMID:27482889

Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway.

PubMed

Xu, Xiaolin; Li, Qian; Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian; Wang, Yiqing

2013-11-15

Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α. Copyright © 2013 Elsevier Inc. All rights reserved.

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

Single nucleotide polymorphisms in CETP, SLC46A1, SLC19A1, CD36, BCMO1, APOA5, and ABCA1 are significant predictors of plasma HDL in healthy adults

PubMed Central

2013-01-01

Background In a marker-trait association study we estimated the statistical significance of 65 single nucleotide polymorphisms (SNP) in 23 candidate genes on HDL levels of two independent Caucasian populations. Each population consisted of men and women and their HDL levels were adjusted for gender and body weight. We used a linear regression model. Selected genes corresponded to folate metabolism, vitamins B-12, A, and E, and cholesterol pathways or lipid metabolism. Methods Extracted DNA from both the Sacramento and Beltsville populations was analyzed using an allele discrimination assay with a MALDI-TOF mass spectrometry platform. The adjusted phenotype, y, was HDL levels adjusted for gender and body weight only statistical analyses were performed using the genotype association and regression modules from the SNP Variation Suite v7. Results Statistically significant SNP (where P values were adjusted for false discovery rate) included: CETP (rs7499892 and rs5882); SLC46A1 (rs37514694; rs739439); SLC19A1 (rs3788199); CD36 (rs3211956); BCMO1 (rs6564851), APOA5 (rs662799), and ABCA1 (rs4149267). Many prior association trends of the SNP with HDL were replicated in our cross-validation study. Significantly, the association of SNP in folate transporters (SLC46A1 rs37514694 and rs739439; SLC19A1 rs3788199) with HDL was identified in our study. Conclusions Given recent literature on the role of niacin in the biogenesis of HDL, focus on status and metabolism of B-vitamins and metabolites of eccentric cleavage of β-carotene with lipid metabolism is exciting for future study. PMID:23656756

Phenotypic characteristics of Alzheimer patients carrying an ABCA7 mutation.

PubMed

Van den Bossche, Tobi; Sleegers, Kristel; Cuyvers, Elise; Engelborghs, Sebastiaan; Sieben, Anne; De Roeck, Arne; Van Cauwenberghe, Caroline; Vermeulen, Steven; Van den Broeck, Marleen; Laureys, Annelies; Peeters, Karin; Mattheijssens, Maria; Vandenbulcke, Mathieu; Vandenberghe, Rik; Martin, Jean-Jacques; De Deyn, Peter P; Cras, Patrick; Van Broeckhoven, Christine

2016-06-07

To generate a clinical and pathologic phenotype of patients carrying rare loss-of-function mutations in ABCA7, identified in a Belgian Alzheimer patient cohort and in an autosomal dominant family. We performed a retrospective review of available data records, medical records, results of CSF analyses and neuroimaging studies, and neuropathology data. The mean onset age of the mutation carriers (n = 22) was 73.4 ± 8.4 years with a wide age range of 36 (54-90) years, which was independent of APOE genotype and cerebrovascular disease. The mean disease duration was 5.7 ± 3.0 years (range 2-12 years). A positive family history was recorded for 10 carriers (45.5%). All patient carriers except one presented with memory complaints. The 4 autopsied brains showed typical immunohistochemical changes of late-onset Alzheimer disease. All patients carrying a loss-of-function mutation in ABCA7 exhibited a classical Alzheimer disease phenotype, though with a striking wide onset age range, suggesting the influence of unknown modifying factors. © 2016 American Academy of Neurology.

Phenotypic characteristics of Alzheimer patients carrying an ABCA7 mutation

PubMed Central

Van den Bossche, Tobi; Sleegers, Kristel; Cuyvers, Elise; Engelborghs, Sebastiaan; Sieben, Anne; De Roeck, Arne; Van Cauwenberghe, Caroline; Vermeulen, Steven; Van den Broeck, Marleen; Laureys, Annelies; Peeters, Karin; Mattheijssens, Maria; Vandenbulcke, Mathieu; Vandenberghe, Rik; Martin, Jean-Jacques; De Deyn, Peter P.; Cras, Patrick

2016-01-01

Objective: To generate a clinical and pathologic phenotype of patients carrying rare loss-of-function mutations in ABCA7, identified in a Belgian Alzheimer patient cohort and in an autosomal dominant family. Methods: We performed a retrospective review of available data records, medical records, results of CSF analyses and neuroimaging studies, and neuropathology data. Results: The mean onset age of the mutation carriers (n = 22) was 73.4 ± 8.4 years with a wide age range of 36 (54–90) years, which was independent of APOE genotype and cerebrovascular disease. The mean disease duration was 5.7 ± 3.0 years (range 2–12 years). A positive family history was recorded for 10 carriers (45.5%). All patient carriers except one presented with memory complaints. The 4 autopsied brains showed typical immunohistochemical changes of late-onset Alzheimer disease. Conclusions: All patients carrying a loss-of-function mutation in ABCA7 exhibited a classical Alzheimer disease phenotype, though with a striking wide onset age range, suggesting the influence of unknown modifying factors. PMID:27037232

Preventive effects of heregulin-beta1 on macrophage foam cell formation and atherosclerosis.

PubMed

Xu, Gang; Watanabe, Takuya; Iso, Yoshitaka; Koba, Shinji; Sakai, Tetsuo; Nagashima, Masaharu; Arita, Shigeko; Hongo, Shigeki; Ota, Hidekazu; Kobayashi, Youichi; Miyazaki, Akira; Hirano, Tsutomu

2009-08-28

Human heregulins, neuregulin-1 type I polypeptides that activate proliferation, differentiation, and survival of glial cells, neurons, and myocytes, are expressed in macrophage foam cells within human coronary atherosclerotic lesions. Macrophage foam cell formation, characterized by cholesterol ester accumulation, is modulated by scavenger receptor class A (SR-A), acyl-coenzyme A:cholesterol acyltransferase (ACAT)1, and ATP-binding cassette transporter (ABC)A1. The present study clarified the roles of heregulins in macrophage foam cell formation and atherosclerosis. Plasma heregulin-beta(1) levels were significantly decreased in 31 patients with acute coronary syndrome and 33 patients with effort angina pectoris compared with 34 patients with mild hypertension and 40 healthy volunteers (1.3+/-0.3, 2.0+/-0.4 versus 7.6+/-1.4, 8.2+/-1.2 ng/mL; P<0.01). Among all patients with acute coronary syndrome and effort angina pectoris, plasma heregulin-beta(1) levels were further decreased in accordance with the severity of coronary artery lesions. Expression of heregulin-beta(1) was observed at trace levels in intracoronary atherothrombosis obtained by aspiration thrombectomy from acute coronary syndrome patients. Heregulin-beta(1), but not heregulin-alpha, significantly reduced acetylated low-density lipoprotein-induced cholesterol ester accumulation in primary cultured human monocyte-derived macrophages by reducing SR-A and ACAT1 expression and by increasing ABCA1 expression at both mRNA and protein levels. Heregulin-beta(1) significantly decreased endocytic uptake of [(125)I]acetylated low-density lipoprotein and ACAT activity, and increased cholesterol efflux to apolipoprotein (Apo)A-I from human macrophages. Chronic infusion of heregulin-beta(1) into ApoE(-/-) mice significantly suppressed the development of atherosclerotic lesions. This study provided the first evidence that heregulin-beta(1) inhibits atherogenesis and suppresses macrophage foam cell formation via SR

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

Stargardt macular dystrophy: common ABCA4 mutations in South Africa—establishment of a rapid genetic test and relating risk to patients

PubMed Central

Nossek, Christel A.; Greenberg, L. Jacquie; Ramesar, Rajkumar S.

2012-01-01

Purpose Based on the previous indications of founder ATP-binding cassette sub-family A member 4 gene (ABCA4) mutations in a South African subpopulation, the purpose was to devise a mechanism for identifying common disease-causing mutations in subjects with ABCA4-associated retinopathies (AARs). Facilitating patient access to this data and determining the frequencies of the mutations in the South African population would enhance the current molecular diagnostic service offered. Methods The majority of subjects in this study were of Caucasian ancestry and affected with Stargardt macular dystrophy. The initial cohort consisted of DNA samples from 181 patients, and was screened using the ABCR400 chip. An assay was then designed to screen a secondary cohort of 72 patients for seven of the most commonly occurring ABCA4 mutations in this population. A total of 269 control individuals were also screened for the seven ABCA4 mutations. Results Microarray screening results from a cohort of 181 patients affected with AARs revealed that seven ABCA4 mutations (p.Arg152*, c.768G>T, p.Arg602Trp, p.Gly863Ala, p.Cys1490Tyr, c.5461–10T>C, and p.Leu2027Phe) occurred at a relatively high frequency. The newly designed genetic assay identified two of the seven disease-associated mutations in 28/72 patients in a secondary patient cohort. In the control cohort, 12/269 individuals were found to be heterozygotes, resulting in an estimated background frequency of these mutations in this particular population of 4.46 per 100 individuals. Conclusions The relatively high detection rate of seven ABCA4 mutations in the primary patient cohort led to the design and subsequent utility of a multiplex assay. This assay can be used as a viable screening tool and to reduce costs and laboratory time. The estimated background frequency of the seven ABCA4 mutations, together with the improved diagnostic service, could be used by counselors to facilitate clinical and genetic management of South African

Genetic regulation of IL1RL1 methylation and IL1RL1-a protein levels in asthma.

PubMed

Dijk, F Nicole; Xu, Chengjian; Melén, Erik; Carsin, Anne-Elie; Kumar, Asish; Nolte, Ilja M; Gruzieva, Olena; Pershagen, Goran; Grotenboer, Neomi S; Savenije, Olga E M; Antó, Josep Maria; Lavi, Iris; Dobaño, Carlota; Bousquet, Jean; van der Vlies, Pieter; van der Valk, Ralf J P; de Jongste, Johan C; Nawijn, Martijn C; Guerra, Stefano; Postma, Dirkje S; Koppelman, Gerard H

2018-03-01

Interleukin-1 receptor-like 1 ( IL1RL1 ) is an important asthma gene. (Epi)genetic regulation of IL1RL1 protein expression has not been established. We assessed the association between IL1RL1 single nucleotide polymorphisms (SNPs), IL1RL1 methylation and serum IL1RL1-a protein levels, and aimed to identify causal pathways in asthma.Associations of IL1RL1 SNPs with asthma were determined in the Dutch Asthma Genome-wide Association Study cohort and three European birth cohorts, BAMSE (Children/Barn, Allergy, Milieu, Stockholm, an Epidemiological survey), INMA (Infancia y Medio Ambiente) and PIAMA (Prevention and Incidence of Asthma and Mite Allergy), participating in the Mechanisms of the Development of Allergy study. We performed blood DNA IL1RL1 methylation quantitative trait locus (QTL) analysis (n=496) and (epi)genome-wide protein QTL analysis on serum IL1RL1-a levels (n=1462). We investigated the association of IL1RL1 CpG methylation with asthma (n=632) and IL1RL1-a levels (n=548), with subsequent causal inference testing. Finally, we determined the association of IL1RL1-a levels with asthma and its clinical characteristics (n=1101). IL1RL1 asthma-risk SNPs strongly associated with IL1RL1 methylation (rs1420101; p=3.7×10 -16 ) and serum IL1RL1-a levels (p=2.8×10 -56 ). IL1RL1 methylation was not associated with asthma or IL1RL1-a levels. IL1RL1-a levels negatively correlated with blood eosinophil counts, whereas there was no association between IL1RL1-a levels and asthma.In conclusion, asthma-associated IL1RL1 SNPs strongly regulate IL1RL1 methylation and serum IL1RL1-a levels, yet neither these IL1RL1- methylation CpG sites nor IL1RL1-a levels are associated with asthma. Copyright ©ERS 2018.

Possible protective role of the ABCA4 gene c.1268A>G missense variant in Stargardt disease and syndromic retinitis pigmentosa in a Sicilian family: Preliminary data.

PubMed

D'Angelo, Rosalia; Donato, Luigi; Venza, Isabella; Scimone, Concetta; Aragona, Pasquale; Sidoti, Antonina

2017-04-01

In the wide horizon of ophthalmologically rare diseases among retinitis pigmentosa forms, Stargardt disease has gradually assumed a significant role due to its heterogeneity. In the present study, we aimed to support one of two opposite hypotheses concerning the causative or protective role of heterozygous c.1268A>G missense variant of the ABCA4 gene in Stargardt disease and in syndromic retinitis pigmentosa. This study was based on a family consisting of three members: proband, age 54, with high myopia, myopic chorioretinitis and retinal dystrophy; wife, age 65, with mild symptoms; daughter, age 29, asymptomatic. After genetic counseling, ABCA4 and RP1 gene analysis was performed. The results highlighted an important genetic picture. The proband was found to carry two variant RP1 SNPs, rs2293869 (c.2953A>T) and rs61739567 (c.6098G>A), and, a wild-type condition for four RP1 polymorphisms, rs444772 (c.2623G>A) and three SNPs in the 'hot-spot' region, exon 4. The proband's wife, instead, showed an opposite condition compared to her husband: a homozygous mutated condition for the first four SNPs analyzed, while the last two were wild-type. Regarding the ABCA4 gene, the proband evidenced a wild-type condition. Furthermore, the wife showed a heterozygous condition of ABCA4 rs3112831 (c.1268A>G). As expected, the daughter presented heterozygosity for all variants of both genes. In conclusion, even though the c.1268A>G missense variant of the ABCA4 gene has often been reported as causative of disease, and in other cases protective of disease, in our family case, the variant appears to reduce or delay the risk of onset of Stargardt disease.

ATP-binding cassette transporter ABCA4 and chemical isomerization protect photoreceptor cells from the toxic accumulation of excess 11-cis-retinal.

PubMed

Quazi, Faraz; Molday, Robert S

2014-04-01

The visual cycle is a series of enzyme-catalyzed reactions which converts all-trans-retinal to 11-cis-retinal for the regeneration of visual pigments in rod and cone photoreceptor cells. Although essential for vision, 11-cis-retinal like all-trans-retinal is highly toxic due to its highly reactive aldehyde group and has to be detoxified by either reduction to retinol or sequestration within retinal-binding proteins. Previous studies have focused on the role of the ATP-binding cassette transporter ABCA4 associated with Stargardt macular degeneration and retinol dehydrogenases (RDH) in the clearance of all-trans-retinal from photoreceptors following photoexcitation. How rod and cone cells prevent the accumulation of 11-cis-retinal in photoreceptor disk membranes in excess of what is required for visual pigment regeneration is not known. Here we show that ABCA4 can transport N-11-cis-retinylidene-phosphatidylethanolamine (PE), the Schiff-base conjugate of 11-cis-retinal and PE, from the lumen to the cytoplasmic leaflet of disk membranes. This transport function together with chemical isomerization to its all-trans isomer and reduction to all-trans-retinol by RDH can prevent the accumulation of excess 11-cis-retinal and its Schiff-base conjugate and the formation of toxic bisretinoid compounds as found in ABCA4-deficient mice and individuals with Stargardt macular degeneration. This segment of the visual cycle in which excess 11-cis-retinal is converted to all-trans-retinol provides a rationale for the unusually high content of PE and its long-chain unsaturated docosahexaenoyl group in photoreceptor membranes and adds insight into the molecular mechanisms responsible for Stargardt macular degeneration.

Reduced-illuminance autofluorescence imaging in ABCA4-associated retinal degenerations

NASA Astrophysics Data System (ADS)

Cideciyan, Artur V.; Swider, Malgorzata; Aleman, Tomas S.; Roman, Marisa I.; Sumaroka, Alexander; Schwartz, Sharon B.; Stone, Edwin M.; Jacobson, Samuel G.

2007-05-01

The health of the retinal pigment epithelium (RPE) can be estimated with autofluorescence (AF) imaging of lipofuscin, which accumulates as a byproduct of retinal exposure to light. Lipofuscin may be toxic to the RPE, and its toxicity may be enhanced by short-wavelength (SW) illumination. The high-intensity and SW excitation light used in conventional AF imaging could, at least in principle, increase the rate of lipofuscin accumulation and/or increase its toxicity. We considered two reduced-illuminance AF imaging (RAFI) methods as alternatives to conventional AF imaging. RAFI methods use either near-infrared (NIR) light or reduced-radiance SW illumination for excitation of fluorophores. We quantified the distribution of RAFI signals in relation to retinal structure and function in patients with the prototypical lipofuscin accumulation disease caused by mutations in ABCA4. There was evidence for two subclinical stages of macular ABCA4 disease involving hyperautofluorescence of both SW- and NIR-RAFI with and without associated loss of visual function. Use of RAFI methods and microperimetry in future clinical trials involving lipofuscinopathies should allow quantification of subclinical disease expression and progression without subjecting the diseased retina/RPE to undue light exposure.

The multi-PDZ domain protein-1 (MUPP-1) expression regulates cellular levels of the PALS-1/PATJ polarity complex.

PubMed

Assémat, Emeline; Crost, Emmanuelle; Ponserre, Marion; Wijnholds, Jan; Le Bivic, Andre; Massey-Harroche, Dominique

2013-10-15

MUPP-1 (multi-PDZ domain protein-1) and PATJ (PALS-1-associated tight junction protein) proteins are closely related scaffold proteins and bind to many common interactors including PALS-1 (protein associated with Lin seven) a member of the Crumbs complex. Our goal is to understand how MUPP-1 and PATJ and their interaction with PALS-1 are regulated in the same cells. We have shown that in MCF10A cells there are at least two different and co-existing complexes, PALS-1/MUPP-1 and PALS-1/PATJ. Surprisingly, MUPP-1 levels inversely correlated with PATJ protein levels by acting on the stabilization of the PATJ/PALS-1 complex. Upon MUPP-1 depletion, the increased amounts of PATJ are in part localized at the migrating front of MCF10A cells and are able to recruit more PAR3 (partition defective 3). All together these data indicate that a precise balance between MUPP-1 and PATJ is achieved in epithelial cells by regulating their association with PALS-1. © 2013 Elsevier Inc. All rights reserved.

Mechanism for the decrease in the FIP1L1-PDGFRalpha protein level in EoL-1 cells by histone deacetylase inhibitors.

PubMed

Ishihara, Kenji; Kaneko, Motoko; Kitamura, Hajime; Takahashi, Aki; Hong, Jang Ja; Seyama, Toshio; Iida, Koji; Wada, Hiroshi; Hirasawa, Noriyasu; Ohuchi, Kazuo

2008-01-01

Acetylation and deacetylation of proteins occur in cells in response to various stimuli, and are reversibly catalyzed by histone acetyltransferase and histone deacetylase (HDAC), respectively. EoL-1 cells have an FIP1L1-PDGFRA fusion gene that causes transformation of eosinophilic precursor cells into leukemia cells. The HDAC inhibitors apicidin and n-butyrate suppress the proliferation of EoL-1 cells and induce differentiation into eosinophils by a decrease in the protein level of FIP1L1-PDGFRalpha without affecting the mRNA level for FIP1L1-PDGFRA. In this study, we analyzed the mechanism by which the protein level of FIP1L1-PDGFRalpha is decreased by apicidin and n-butyrate. EoL-1 cells were incubated in the presence of the HDAC inhibitors apicidin, trichostatin A or n-butyrate. The protein levels of FIP1L1-PDGFRalpha and phosphorylated eIF-2alpha were determined by Western blotting. Actinomycin D and cycloheximide were used to block RNA synthesis and protein synthesis, respectively, in the chasing experiment of the amount of FIP1L1-PDGFRalpha protein. When apicidin- and n-butyrate-treated EoL-1 cells were incubated in the presence of actinomycin D, the decrease in the protein level of FIP1L1-PDGFRalpha was significantly enhanced when compared with controls. In contrast, the protein levels were not changed by cycloheximide among these groups. Apicidin and n-butyrate induced the continuous phosphorylation of eIF-2alpha for up to 8 days. The decrease in the level of FIP1L1-PDGFRalpha protein by continuous inhibition of HDAC may be due to the decrease in the translation rate of FIP1L1-PDGFRA. Copyright 2008 S. Karger AG, Basel.

Hydrogen Sulfide Up-Regulates the Expression of ATP-Binding Cassette Transporter A1 via Promoting Nuclear Translocation of PPARα.

PubMed

Li, Dong; Xiong, Qinghui; Peng, Jin; Hu, Bin; Li, Wanzhen; Zhu, Yizhun; Shen, Xiaoyan

2016-04-29

ATP binding cassette transporter A1 (ABCA1) plays a key role in atherogenesis. Hydrogen sulfide (H₂S), a gasotransmitter, has been reported to play an anti-atherosclerotic role. However, the underlying mechanisms are largely unknown. In this study we examined whether and how H₂S regulates ABCA1 expression. The effect of H₂S on ABCA1 expression and lipid metabolism were assessed in vitro by cultured human hepatoma cell line HepG2, and in vivo by ApoE(-/-) mice with a high-cholesterol diet. NaHS (an exogenous H₂S donor) treatment significantly increased the expression of ABCA1, ApoA1, and ApoA2 and ameliorated intracellular lipid accumulation in HepG2 cells. Depletion of the endogenous H₂S generator cystathionine γ-lyase (CSE) by small RNA interference (siRNA) significantly decreased the expression of ABCA1 and resulted in the accumulation of lipids in HepG2 cells. In vivo NaHS treatment significantly reduced the serum levels of total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL), diminished atherosclerotic plaque size, and increased hepatic ABCA1 expression in fat-fed ApoE(-/-) mice. Further study revealed that NaHS upregulated ABCA1 expression by promoting peroxisome proliferator-activated receptor α (PPARα) nuclear translocation. H₂S up-regulates the expression of ABCA1 by promoting the nuclear translocation of PPARα, providing a fundamental mechanism for the anti-atherogenic activity of H₂S. H₂S may be a promising potential drug candidate for the treatment of atherosclerosis.

ABCA4 midigenes reveal the full splice spectrum of all reported noncanonical splice site variants in Stargardt disease.

PubMed

Sangermano, Riccardo; Khan, Mubeen; Cornelis, Stéphanie S; Richelle, Valerie; Albert, Silvia; Garanto, Alejandro; Elmelik, Duaa; Qamar, Raheel; Lugtenberg, Dorien; van den Born, L Ingeborgh; Collin, Rob W J; Cremers, Frans P M

2018-01-01

Stargardt disease is caused by variants in the ABCA4 gene, a significant part of which are noncanonical splice site (NCSS) variants. In case a gene of interest is not expressed in available somatic cells, small genomic fragments carrying potential disease-associated variants are tested for splice abnormalities using in vitro splice assays. We recently discovered that when using small minigenes lacking the proper genomic context, in vitro results do not correlate with splice defects observed in patient cells. We therefore devised a novel strategy in which a bacterial artificial chromosome was employed to generate midigenes, splice vectors of varying lengths (up to 11.7 kb) covering almost the entire ABCA4 gene. These midigenes were used to analyze the effect of all 44 reported and three novel NCSS variants on ABCA4 pre-mRNA splicing. Intriguingly, multi-exon skipping events were observed, as well as exon elongation and intron retention. The analysis of all reported NCSS variants in ABCA4 allowed us to reveal the nature of aberrant splicing events and to classify the severity of these mutations based on the residual fraction of wild-type mRNA. Our strategy to generate large overlapping splice vectors carrying multiple exons, creating a toolbox for robust and high-throughput analysis of splice variants, can be applied to all human genes. © 2018 Sangermano et al.; Published by Cold Spring Harbor Laboratory Press.

HDL-cholesterol concentration in pregnant Chinese Han women of late second trimester associated with genetic variants in CETP, ABCA1, APOC3, and GALNT2.

PubMed

Cui, Mingxuan; Li, Wei; Ma, Liangkun; Ping, Fan; Liu, Juntao; Wu, Xueyan; Mao, Jiangfeng; Wang, Xi; Nie, Min

2017-08-22

To investigate whether HDL-C level in pregnant Chinese Han women of late second trimester correlated with loci in high-density lipoprotein-cholesterol (HDL-C)-related genes found in genome-wide association studies (GWAS). Seven single-nucleotide polymorphisms (rs3764261 in CETP , rs1532085 in LIPC , rs7241918 in LIPG , rs1883025 in ABCA1 , rs4225 in APOC3 , rs1059611 in LPL , and rs16851339 in GALNT2 ) were genotyped using the Sequenom MassArray system for 1,884 pregnant women. The following polymorphisms were statistically associated with HDL-C level after adjusting for age, gestational week, pre-pregnancy BMI and state of GDM or HOMAIR: (i) rs3764261 (b = -0.055 mmol/L, 95% CI -0.101 to -0.008, p = 0.021), (ii) rs1883025 (b = -0.054 mmol/L, 95% CI -0.097 to -0.012, p = 0.013), (iii) rs4225 (b = -0.071 mmol/L, 95% CI -0.116 to -0.027, p = 1.79E-3) and (iv) rs16851339 (b = -0.064 mmol/L, 95% CI -0.120 to -0.008, p = 0.025). The more risk alleles the pregnant women have, the lower the plasma HDL-C levels of the subjects are. Several risk alleles found to be related to HDL-C in GWAS are also associated with HDL-C levels in pregnant Chinese Han women and these risk loci contribute additively to low HDL-C levels.

HDL-cholesterol concentration in pregnant Chinese Han women of late second trimester associated with genetic variants in CETP, ABCA1, APOC3, and GALNT2

PubMed Central

Cui, Mingxuan; Li, Wei; Ma, Liangkun; Ping, Fan; Liu, Juntao; Wu, Xueyan; Mao, Jiangfeng; Wang, Xi; Nie, Min

2017-01-01

Objective To investigate whether HDL-C level in pregnant Chinese Han women of late second trimester correlated with loci in high-density lipoprotein-cholesterol (HDL-C)-related genes found in genome-wide association studies (GWAS). Methods Seven single-nucleotide polymorphisms (rs3764261 in CETP, rs1532085 in LIPC, rs7241918 in LIPG, rs1883025 in ABCA1, rs4225 in APOC3, rs1059611 in LPL, and rs16851339 in GALNT2) were genotyped using the Sequenom MassArray system for 1,884 pregnant women. Results The following polymorphisms were statistically associated with HDL-C level after adjusting for age, gestational week, pre-pregnancy BMI and state of GDM or HOMAIR: (i) rs3764261 (b = -0.055 mmol/L, 95% CI -0.101 to -0.008, p = 0.021), (ii) rs1883025 (b = -0.054 mmol/L, 95% CI -0.097 to -0.012, p = 0.013), (iii) rs4225 (b = -0.071 mmol/L, 95% CI -0.116 to -0.027, p = 1.79E-3) and (iv) rs16851339 (b = -0.064 mmol/L, 95% CI -0.120 to -0.008, p = 0.025). The more risk alleles the pregnant women have, the lower the plasma HDL-C levels of the subjects are. Conclusions Several risk alleles found to be related to HDL-C in GWAS are also associated with HDL-C levels in pregnant Chinese Han women and these risk loci contribute additively to low HDL-C levels. PMID:28915626

The ABCA4 2588G>C Stargardt mutation: single origin and increasing frequency from South-West to North-East Europe.

PubMed

Maugeri, Alessandra; Flothmann, Kris; Hemmrich, Nadine; Ingvast, Sofie; Jorge, Paula; Paloma, Eva; Patel, Reshma; Rozet, Jean-Michel; Tammur, Jaana; Testa, Francesco; Balcells, Susana; Bird, Alan C; Brunner, Han G; Hoyng, Carel B; Metspalu, Andres; Simonelli, Francesca; Allikmets, Rando; Bhattacharya, Shomi S; D'Urso, Michele; Gonzàlez-Duarte, Roser; Kaplan, Josseline; te Meerman, Gerard J; Santos, Rosário; Schwartz, Marianne; Van Camp, Guy; Wadelius, Claes; Weber, Bernhard H F; Cremers, Frans P M

2002-03-01

Inherited retinal dystrophies represent the most important cause of vision impairment in adolescence, affecting approximately 1 out of 3000 individuals. Mutations of the photoreceptor-specific gene ABCA4 (ABCR) are a common cause of retinal dystrophy. A number of mutations have been repeatedly reported for this gene, notably the 2588G>C mutation which is frequent in both patients and controls. Here we ascertained the frequency of the 2588G>C mutation in a total of 2343 unrelated random control individuals from 11 European countries and 241 control individuals from the US, as well as in 614 patients with STGD both from Europe and the US. We found an overall carrier frequency of 1 out of 54 in Europe, compared with 1 out of 121 in the US, confirming that the 2588G>C ABCA4 mutation is one of the most frequent autosomal recessive mutations in the European population. Carrier frequencies show an increasing gradient in Europe from South-West to North-East. The lowest carrier frequency, 0 out of 199 (0%), was found in Portugal; the highest, 11 out of 197 (5.5%), was found in Sweden. Haplotype analysis in 16 families segregating the 2588G>C mutation showed four intragenic polymorphisms invariably present in all 16 disease chromosomes and sharing of the same allele for several markers flanking the ABCA4 locus in most of the disease chromosomes. These results indicate a single origin of the 2588G>C mutation which, to our best estimate, occurred between 2400 and 3000 years ago.

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

Hydrogen Sulfide Up-Regulates the Expression of ATP-Binding Cassette Transporter A1 via Promoting Nuclear Translocation of PPARα

PubMed Central

Li, Dong; Xiong, Qinghui; Peng, Jin; Hu, Bin; Li, Wanzhen; Zhu, Yizhun; Shen, Xiaoyan

2016-01-01

ATP binding cassette transporter A1 (ABCA1) plays a key role in atherogenesis. Hydrogen sulfide (H2S), a gasotransmitter, has been reported to play an anti-atherosclerotic role. However, the underlying mechanisms are largely unknown. In this study we examined whether and how H2S regulates ABCA1 expression. The effect of H2S on ABCA1 expression and lipid metabolism were assessed in vitro by cultured human hepatoma cell line HepG2, and in vivo by ApoE−/− mice with a high-cholesterol diet. NaHS (an exogenous H2S donor) treatment significantly increased the expression of ABCA1, ApoA1, and ApoA2 and ameliorated intracellular lipid accumulation in HepG2 cells. Depletion of the endogenous H2S generator cystathionine γ-lyase (CSE) by small RNA interference (siRNA) significantly decreased the expression of ABCA1 and resulted in the accumulation of lipids in HepG2 cells. In vivo NaHS treatment significantly reduced the serum levels of total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL), diminished atherosclerotic plaque size, and increased hepatic ABCA1 expression in fat-fed ApoE−/− mice. Further study revealed that NaHS upregulated ABCA1 expression by promoting peroxisome proliferator-activated receptor α (PPARα) nuclear translocation. H2S up-regulates the expression of ABCA1 by promoting the nuclear translocation of PPARα, providing a fundamental mechanism for the anti-atherogenic activity of H2S. H2S may be a promising potential drug candidate for the treatment of atherosclerosis. PMID:27136542

Fundus Autofluorescence in the Abca4−/− Mouse Model of Stargardt Disease—Correlation With Accumulation of A2E, Retinal Function, and Histology

PubMed Central

Charbel Issa, Peter; Barnard, Alun R.; Singh, Mandeep S.; Carter, Emma; Jiang, Zhichun; Radu, Roxana A.; Schraermeyer, Ulrich; MacLaren, Robert E.

2013-01-01

Purpose. To investigate fundus autofluorescence (AF) characteristics in the Abca4−/− mouse, an animal model for AMD and Stargardt disease, and to correlate findings with functional, structural, and biochemical assessments. Methods. Blue (488 nm) and near-infrared (790 nm) fundus AF images were quantitatively and qualitatively analyzed in pigmented Abca4−/− mice and wild type (WT) controls in vivo. Functional, structural, and biochemical assessments included electroretinography (ERG), light and electron microscopic analysis, and A2E quantification. All assessments were performed across age groups. Results. In Abca4−/− mice, lipofuscin-related 488 nm AF increased early in life with a ceiling effect after 6 months. This increase was first paralleled by an accumulation of typical lipofuscin granules in the retinal pigment epithelium (RPE). Later, lipofuscin and melanin granules decreased in number, whereas melanolipofuscin granules increased. This increase in melanolipofuscin granules paralleled an increase in melanin-related 790 nm AF. Old Abca4−/− mice revealed a flecked fundus AF pattern at both excitation wavelengths. The amount of A2E, a major lipofuscin component, increased 10- to 12-fold in 6- to 9-month-old Abca4−/− mice compared with controls, while 488 nm AF intensity only increased 2-fold. Despite pronounced lipofuscin accumulation in the RPE of Abca4−/− mice, ERG and histology showed a slow age-related thinning of the photoreceptor layer similar to WT controls up to 12 months. Conclusions. Fundus AF can be used to monitor lipofuscin accumulation and melanin-related changes in vivo in mouse models of retinal disease. High RPE lipofuscin may not adversely affect retinal structure or function over prolonged time intervals, and melanin-related changes (melanolipofuscin formation) may occur before the decline in retinal function. PMID:23761084

Inhibition of cholesterol absorption associated with a PPAR alpha-dependent increase in ABC binding cassette transporter A1 in mice.

PubMed

Knight, Brian L; Patel, Dilip D; Humphreys, Sandy M; Wiggins, David; Gibbons, Geoffrey F

2003-11-01

Dietary supplementation with the peroxisome proliferator-activated receptor alpha (PPAR alpha) ligand WY 14,643 gave rise to a 4- to 5-fold increase in the expression of mRNA for the ATP binding cassette transporter A1 (ABCA1) in the intestine of normal mice. There was no effect in the intestine of PPAR alpha-null mice. Consumption of a high-cholesterol diet also increased intestinal ABCA1 expression. The effects of WY 14,643 and the high-cholesterol diet were not additive. WY 14,643 feeding reduced intestinal absorption of cholesterol in the normal mice, irrespective of the dietary cholesterol concentration, and this resulted in lower diet-derived cholesterol and cholesteryl ester concentrations in plasma and liver. At each concentration of dietary cholesterol, there was a similar significant inverse correlation between intestinal ABCA1 mRNA content and the amount of cholesterol absorbed. The fibrate-induced changes in the intestines of the normal mice were accompanied by an increased concentration of the mRNA encoding the sterol-regulatory element binding protein-1c gene (SREBP-1c), a known target gene for the oxysterol receptor liver X receptor alpha (LXR alpha). There was a correlation between intestinal ABCA1 mRNA and SREBP-1c mRNA contents, but not between SREBP-1c mRNA content and cholesterol absorption. These results suggest that PPAR alpha influences cholesterol absorption through modulating ABCA1 activity in the intestine by a mechanism involving LXR alpha.

Caffeine Increases Apolipoprotein A-1 and Paraoxonase-1 but not Paraoxonase-3 Protein Levels in Human-Derived Liver (HepG2) Cells.

PubMed

Sayılan Özgün, Gülben; Özgün, Eray; Tabakçıoğlu, Kıymet; Süer Gökmen, Selma; Eskiocak, Sevgi; Çakır, Erol

2017-12-01

Apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 are antioxidant and anti-atherosclerotic structural high-density lipoprotein proteins that are mainly synthesized by the liver. No study has ever been performed to specifically examine the effects of caffeine on paraoxonase enzymes and on liver apolipoprotein A-1 protein levels. To investigate the dose-dependent effects of caffeine on liver apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 protein levels. In vitro experimental study. HepG2 cells were incubated with 0 (control), 10, 50 and 200 μM of caffeine for 24 hours. Cell viability was evaluated by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 protein levels were measured by western blotting. We observed a significant increase on apolipoprotein A-1 and paraoxonase-1 protein levels in the cells incubated with 50 µM of caffeine and a significant increase on paraoxonase-1 protein level in the cells incubated with 200 µM of caffeine. Our study showed that caffeine does not change paraoxonase-3 protein level, but the higher doses used in our study do cause an increase in both apolipoprotein A-1 and paraoxonase-1 protein levels in liver cells.

Activation of liver X receptor decreases atherosclerosis in Ldlr⁻/⁻ mice in the absence of ATP-binding cassette transporters A1 and G1 in myeloid cells.

PubMed

Kappus, Mojdeh S; Murphy, Andrew J; Abramowicz, Sandra; Ntonga, Vusisizwe; Welch, Carrie L; Tall, Alan R; Westerterp, Marit

2014-02-01

Liver X receptor (LXR) activators decrease atherosclerosis in mice. LXR activators (1) directly upregulate genes involved in reverse cholesterol transport and (2) exert anti-inflammatory effects mediated by transrepression of nuclear factor-κB target genes. We investigated whether myeloid cell deficiency of ATP-binding cassette transporters A1 and G1 (ABCA1/G1), principal targets of LXR that promote macrophage cholesterol efflux and initiate reverse cholesterol transport, would abolish the beneficial effects of LXR activation on atherosclerosis. LXR activator T0901317 substantially reduced inflammatory gene expression in macrophages lacking ABCA1/G1. Ldlr(-/-) mice were transplanted with Abca1(-/-)Abcg1(-/-) or wild-type bone marrow (BM) and fed a Western-type diet for 6 weeks with or without T0901317 supplementation. Abca1/g1 BM deficiency increased atherosclerotic lesion complexity and inflammatory cell infiltration into the adventitia and myocardium. T0901317 markedly decreased lesion area, complexity, and inflammatory cell infiltration in the Abca1(-/-)Abcg1(-/-) BM-transplanted mice. To investigate whether this was because of macrophage Abca1/g1 deficiency, Ldlr(-/-) mice were transplanted with LysmCreAbca1(fl/fl)Abcg1(fl/fl) or Abca1(fl/fl)Abcg1(fl/fl) BM and fed Western-type diet with or without the more specific LXR agonist GW3965 for 12 weeks. GW3965 decreased lesion size in both groups, and the decrease was more prominent in the LysmCreAbca1(fl/fl)Abcg1(fl/fl) group. The results suggest that anti-inflammatory effects of LXR activators are of key importance to their antiatherosclerotic effects in vivo independent of cholesterol efflux pathways mediated by macrophage ABCA1/G1. This has implications for the development of LXR activators that lack adverse effects on lipogenic genes while maintaining the ability to transrepress inflammatory genes.

7-ketocholesteryl-9-carboxynonanoate enhances ATP binding cassette transporter A1 expression mediated by PPARγ in THP-1 macrophages.

PubMed

Chi, Yan; Wang, Le; Liu, Yuanyuan; Ma, Yanhua; Wang, Renjun; Han, Xiaofei; Qiao, Hui; Lin, Jiabin; Matsuura, Eiji; Liu, Shuqian; Liu, Qingping

2014-06-01

ATP binding cassette transporter A1 (ABCA1) is a member of the ATP-binding cassette transporter family. It plays an essential role in mediating the efflux of excess cholesterol. It is known that peroxisome proliferator-activated receptor gamma (PPARγ) promoted ABCA1 expression. We previously found 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) upregulated ABCA1 partially through CD36 mediated signals. In the present study, we intended to test if PPARγ signally is involved in the upregulation mediated by oxLig-1. First, we docked oxLig-1 and the ligand-binding domain (LBD) of PPARγ by using AutoDock 3.05 and subsequently confirmed the binding by ELISA assay. Western blotting analyses showed that oxLig-1 induces liver X receptor alpha (LXRα), PPARγ and consequently ABCA1 expression. Furthermore, oxLig-1 significantly enhanced ApoA-I-mediated cholesterol efflux. Pretreatment with an inhibitor for PPARγ (GW9662) or/and LXRα (GGPP) attenuated oxLig-1-induced ABCA1 expression. Under PPARγ knockdown by using PPARγ-shRNA, oxLig-1-induced ABCA1 expression and cholesterol efflux in THP-1 macrophages was blocked by 62% and 25% respectively. These observations suggest that oxLig-1 is a novel PPARγ agonist, promoting ApoA-I-mediated cholesterol efflux from THP-1 macrophages by increasing ABCA1 expression via induction of PPARγ. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

PhosphoLipid transfer protein (PLTP) exerts a direct pro-inflammatory effect on rheumatoid arthritis (RA) fibroblasts-like-synoviocytes (FLS) independently of its lipid transfer activity

PubMed Central

Deckert, Valérie; Daien, Claire I.; Che, Hélène; Elhmioui, Jamila; Lemaire, Stéphanie; Pais de Barros, Jean-Paul; Desrumaux, Catherine; Combe, Bernard; Hahne, Michael; Lagrost, Laurent; Morel, Jacques

2018-01-01

Rheumatoid arthritis (RA) is a chronic inflammatory rheumatic disease with modification of lipids profile and an increased risk of cardiovascular events related to inflammation. Plasma phospholipid transfer protein (PLTP) exerts a lipid transfer activity through its active form. PLTP can also bind to receptors such as ATP-binding cassette transporter A1 (ABCA1). In addition to its role in lipoprotein metabolism and atherosclerosis, the latest advances came in support of a complex role of PLTP in the regulation of the inflammatory response, both with pro-inflammatory or anti-inflammatory properties. The aim of the present study was to decipher the role of PLTP in joint inflammation and to assess its relevance in the context of RA. PLTP expression was examined by western-blot and by immunochemistry. ABCA1 expression was analyzed by flow cytometry. Lipid transfer activity of PLTP and pro-inflammatory cytokines were measured in sera and synovial fluid (SF) from RA patients and controls (healthy subjects or osteoarthritis patients [OA]). FLS were treated with both lipid-transfer active form and inactive form of recombinant human PLTP. IL-8, IL-6, VEGF and MMP3 produced by FLS were assessed by ELISA, and proliferation by measuring 3H-Thymidine incorporation. RA synovial tissues showed higher PLTP staining than OA and PLTP protein levels were also significantly higher in RA-FLS. In addition, RA, unlike OA patients, displayed elevated levels of PLTP activity in SF, which correlated with pro-inflammatory cytokines. Both lipid-transfer active and inactive forms of PLTP significantly increased the production of cytokines and proliferation of FLS. ABCA1 was expressed on RAFLS and PLTP activated STAT3 pathway. To conclude, PLTP is highly expressed in the joints of RA patients and may directly trigger inflammation and FLS proliferation, independently of its lipid transfer activity. These results suggest a pro-inflammatory role for PLTP in RA. PMID:29565987

Novel Mutation in the ATP-Binding Cassette Transporter A3 (ABCA3) Encoding Gene Causes Respiratory Distress Syndrome in A Term Newborn in Southwest Iran

PubMed Central

Rezaei, Farideh; Shafiei, Mohammad; Shariati, Gholamreza; Dehdashtian, Ali; Mohebbi, Maryam; Galehdari, Hamid

2016-01-01

Introduction ABCA3 glycoprotein belongs to the ATP-binding cassette (ABC) superfamily of transporters, which utilize the energy derived from hydrolysis of ATP for the translocation of a wide variety of substrates across the plasma membrane. Mutations in the ABCA3 gene are knowingly causative for fatal surfactant deficiency, particularly respiratory distress syndrome (RDS) in term babies. Case Presentation In this study, Sanger sequencing of the whole ABCA3 gene (NCBI NM_001089) was performed in a neonatal boy with severe RDS. A homozygous mutation has been identified in the patient. Parents were heterozygous for the same missense mutation GGA > AGA at position 202 in exon 6 of the ABCA3 gene (c.604G > A; p.G202R). Furthermore, 70 normal individuals have been analyzed for the mentioned change with negative results. Conclusions Regarding Human Genome Mutation Database (HGMD) and other literature recherche, the detected change is a novel mutation and has not been reported before. Bioinformatics mutation predicting tools prefer it as pathogenic. PMID:27437095

hnRNP A2/B1 interacts with influenza A viral protein NS1 and inhibits virus replication potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nuclear export

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

Wang, Yimeng; Zhou, Jianhong; Du, Yuchun, E-mail: ydu@uark.edu

The NS1 protein of influenza viruses is a major virulence factor and exerts its function through interacting with viral/cellular RNAs and proteins. In this study, we identified heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) as an interacting partner of NS1 proteins by a proteomic method. Knockdown of hnRNP A2/B1 by small interfering RNA (siRNA) resulted in higher levels of NS vRNA, NS1 mRNA, and NS1 protein in the virus-infected cells. In addition, we demonstrated that hnRNP A2/B1 proteins are associated with NS1 and NS2 mRNAs and that knockdown of hnRNP A2/B1 promotes transport of NS1 mRNA from the nucleus to themore » cytoplasm in the infected cells. Lastly, we showed that knockdown of hnRNP A2/B1 leads to enhanced virus replication. Our results suggest that hnRNP A2/B1 plays an inhibitory role in the replication of influenza A virus in host cells potentially through suppressing NS1 RNA/protein levels and NS1 mRNA nucleocytoplasmic translocation. - Highlights: • Cellular protein hnRNP A2/B1 interacts with influenza viral protein NS1. • hnRNP A2/B1 suppresses the levels of NS1 protein, vRNA and mRNA in infected cells. • hnRNP A2/B1 protein is associated with NS1 and NS2 mRNAs. • hnRNP A2/B1 inhibits the nuclear export of NS1 mRNAs. • hnRNP A2/B1 inhibits influenza virus replication.« less

Genetic variant of V825I in the ATP-binding cassette transporter A1 gene and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

PubMed Central

2011-01-01

Background Several genetic variants in the ATP-binding cassette transporter A1 (ABCA1) gene have associated with modifications of serum high-density lipoprotein cholesterol (HDL-C) levels and the susceptibility for coronary heart disease, but the findings are still controversial in diverse racial/ethnic groups. Bai Ku Yao is an isolated subgroup of the Yao minority in southern China. The present study was undertaken to detect the possible association of V825I (rs2066715) polymorphism in the ABCA1 gene and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations. Methods A total of 677 subjects of Bai Ku Yao and 646 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Polymerase chain reaction and restriction fragment length polymorphism assay combined with gel electrophoresis were performed for the genotyping of V825I variant, and then confirmed by direct sequencing. Results The levels of serum total cholesterol (TC), HDL-C, apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of G and A alleles was 57.4% and 42.6% in Bai Ku Yao, and 57.7% and 42.3% in Han (P > 0.05); respectively. The frequency of GG, GA and AA genotypes was 33.7%, 47.4% and 18.9% in Bai Ku Yao, and 33.4%, 48.6% and 18.0% in Han (P > 0.05); respectively. There was no difference in the genotypic and allelic frequencies between males and females in the both ethnic groups. The subjects with AA genotype in Bai Ku Yao had higher serum TC levels than the subjects with GG and GA genotypes (P < 0.05). The participants with AA genotype in Han had lower serum HDL-C and ApoAI levels than the participants with GG and GA genotypes (P < 0.05 for each), but these results were found in males but not in females. Multivariate linear regression analysis showed that the levels of TC in Bai Ku Yao and HDL-C and ApoAI in male Han were correlated with genotypes (P < 0

Fine-tuning of ULK1 mRNA and protein levels is required for autophagy oscillation

PubMed Central

Ciccosanti, Fabiola

2016-01-01

Autophagy is an intracellular degradation pathway whose levels are tightly controlled to secure cell homeostasis. Unc-51–like kinase 1 (ULK1) is a conserved serine–threonine kinase that plays a central role in the initiation of autophagy. Here, we report that upon autophagy progression, ULK1 protein levels are specifically down-regulated by the E3 ligase NEDD4L, which ubiquitylates ULK1 for degradation by the proteasome. However, whereas ULK1 protein is degraded, ULK1 mRNA is actively transcribed. Upon reactivation of mTOR-dependent protein synthesis, basal levels of ULK1 are promptly restored, but the activity of newly synthesized ULK1 is inhibited by mTOR. This prepares the cell for a new possible round of autophagy stimulation. Our results thus place NEDD4L and ULK1 in a key position to control oscillatory activation of autophagy during prolonged stress to keep the levels of this process under a safe and physiological threshold. PMID:27932573

Omega-3 Fatty Acids Supplementation: Therapeutic Potential in a Mouse Model of Stargardt Disease.

PubMed

Prokopiou, Ekatherine; Kolovos, Panagiotis; Kalogerou, Maria; Neokleous, Anastasia; Nicolaou, Orthodoxia; Sokratous, Kleitos; Kyriacou, Kyriacos; Georgiou, Tassos

2018-06-01

To evaluate the therapeutic effects of omega-3 (ω3) fatty acids on retinal degeneration in the ABCA4-/- model of Stargardt disease when the blood level of arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio is between 1 and 1.5. Eight-month-old mice were allocated to three groups: wild type (129S1), ABCA4-/- untreated, and ABCA4-/- ω3 treated. ω3 treatment lasted 3 months and comprised daily gavage administration of EPA and docosahexaenoic acid (DHA). Blood and retinal fatty acid analysis was performed using gas chromatography to adjust the blood AA/EPA ∼1 to 1.5. Eyecups were histologically examined using transmission electron microscopy and confocal microscopy to evaluate lipofuscin granules and the photoreceptor layer. Retinal N-retinylidene-N-retinylethanolamine (A2E), a major component of retinal pigment epithelium lipofuscin, was quantified using liquid chromatography and tandem mass spectrometry, in addition to retinal proteomic analysis to determine changes in inflammatory proteins. EPA levels increased and AA levels decreased in the blood and retinas of the treatment group. Significantly less A2E and lipofuscin granules were observed in the treatment group. The thickness of the outer nuclear layer was significantly greater in the treatment group (75.66 ± 4.80 μm) than in the wild-type (61.40 ± 1.84 μm) or untreated ABCA4-/- (56.50 ± 3.24 μm) groups. Proteomic analysis indicated lower levels of complement component 3 (C3) in the treatment group, indicative of lower complement-induced inflammatory response. Three months of ω3 supplementation (AA/EPA ∼1-1.5) reduces A2E levels, lipofuscin granules, and C3 levels in the ABCA4-/- mouse model of Stargardt disease, consistent with slowing of the disease.

Protein levels of ADAM10, BACE1, and PSEN1 in platelets and leukocytes of Alzheimer's disease patients.

PubMed

Bram, Jessyka Maria de França; Talib, Leda Leme; Joaquim, Helena Passarelli Giroud; Sarno, Tamires Alves; Gattaz, Wagner Farid; Forlenza, Orestes Vicente

2018-05-29

The clinical diagnosis of Alzheimer's disease (AD) is a probabilistic formulation that may lack accuracy particularly at early stages of the dementing process. Abnormalities in amyloid-beta precursor protein (APP) metabolism and in the level of APP secretases have been demonstrated in platelets, and to a lesser extent in leukocytes, of AD patients, with conflicting results. The aim of the present study was to compare the protein level of the APP secretases A-disintegrin and metalloprotease 10 (ADAM10), Beta-site APP-cleaving enzyme 1 (BACE1), and presenilin-1 (PSEN1) in platelets and leukocytes from 20 non-medicated older adults with AD and 20 healthy elders, and to determine the potential use of these biomarkers to discriminate cases of AD from controls. The protein levels of all APP secretases were significantly higher in platelets compared to leukocytes. We found statistically a significant decrease in ADAM10 (52.5%, p < 0.0001) and PSEN1 (32%, p = 0.02) in platelets from AD patients compared to controls, but not in leukocytes. Combining all three secretases to generate receiver-operating characteristic (ROC) curves, we found a good discriminatory effect (AD vs. controls) when using platelets (the area under the curve-AUC-0.90, sensitivity 88.9%, specificity 66.7%, p = 0.003), but not in leukocytes (AUC 0.65, sensitivity 77.8%, specificity 50.0%, p = 0.2). Our findings indicate that platelets represent a better biological matrix than leukocytes to address the peripheral level of APP secretases. In addition, combining the protein level of ADAM10, BACE1, and PSEN1 in platelets, yielded a good accuracy to discriminate AD from controls.

Increased cerebrospinal fluid levels of cytokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1β (MIP-1β) in patients with amyotrophic lateral sclerosis.

PubMed

Martínez, H R; Escamilla-Ocañas, C E; Camara-Lemarroy, C R; González-Garza, M T; Moreno-Cuevas, J; García Sarreón, M A

2017-10-10

Neuroinflammation has recently been described in amyotrophic lateral sclerosis (ALS). However, the precise role of such proinflammatory cytokines as monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1β (MIP-1β) in ALS has not yet been determined. In this study, we determined cerebrospinal fluid (CSF) MCP-1 and MIP-1β levels and assessed their association with the duration and severity of ALS. Concentrations of MCP-1 and MIP-1β were determined in the CSF of 77 patients diagnosed with ALS and 13 controls. Cytokine levels were analysed in relation to ALS duration (<12months vs. >12months) and severity (<30points vs. >30points on the ALS Functional Rating Scale administered at hospital admission). Higher CSF MIP-1β (10.68pg/mL vs. 4.69pg/mL, P<.0001) and MCP-1 (234.89pg/mL vs. 160.95pg/mL, P=.011) levels were found in the 77 patients with ALS compared to controls. There were no differences in levels of either cytokine in relation to disease duration or severity. However, we did observe a significant positive correlation between MIP-1β and MCP-1 in patients with ALS. The increase in MIP-1β and MCP-1 levels suggests that these cytokines may have a synergistic effect on ALS pathogenesis. However, in our cohort, no association was found with either the duration or the clinical severity of the disease. Copyright © 2017 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

MicroRNA-20a/b regulates cholesterol efflux through post-transcriptional repression of ATP-binding cassette transporter A1.

PubMed

Liang, Bin; Wang, Xin; Song, Xiaosu; Bai, Rui; Yang, Huiyu; Yang, Zhiming; Xiao, Chuanshi; Bian, Yunfei

2017-09-01

ATP-binding cassette transporter A1 (ABCA1) plays a crucial role in reverse cholesterol transport and exhibits anti-atherosclerosis effects. Some microRNAs (miRs) regulate ABCA1 expression, and recent studies have shown that miR-20a/b might play a critical role in atherosclerotic diseases. Here, we attempted to clarify the potential contribution of miR-20a/b in post-transcriptional regulation of ABCA1, cholesterol efflux, and atherosclerosis. We performed bioinformatics analysis and found that miR-20a/b was highly conserved and directly bound to ABCA1 mRNA with low binding free energy. Luciferase-reporter assay also confirmed that miR-20a/b significantly reduced luciferase activity associated with the ABCA1 3' untranslated region reporter construct. Additionally, miR-20a/b decreased ABCA1 expression, which, in turn, decreased cholesterol efflux and increased cholesterol content in THP-1 and RAW 264.7 macrophage-derived foam cells. In contrast, miR-20a/b inhibitors increased ABCA1 expression and cholesterol efflux, decreased cholesterol content, and inhibited foam-cell formation. Consistent with our in vitro results, miR-20a/b-treated ApoE -/- mice showed decreased ABCA1expression in the liver and reductions of reverse cholesterol transport in vivo. Furthermore, miR-20a/b regulated the formation of nascent high-density lipoprotein and promoted atherosclerotic development, whereas miR-20a/b knockdown attenuated atherosclerotic formation. miR-20 is a new miRNA capable of targeting ABCA1 and regulating ABCA1 expression. Therefore, miR-20 inhibition constitutes a new strategy for ABCA1-based treatment of atherosclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Kimchi methanol extract and the kimchi active compound, 3'-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, downregulate CD36 in THP-1 macrophages stimulated by oxLDL.

PubMed

Yun, Ye-Rang; Kim, Hyun-Ju; Song, Yeong-Ok

2014-08-01

Macrophage foam cell formation by oxidized low-density lipoprotein (oxLDL) is a key step in the progression of atherosclerosis, which is involved in cholesterol influx and efflux in macrophages mediated by related proteins such as peroxisome proliferator-activated receptor γ (PPARγ), CD36, PPARα, liver-X receptor α (LXRα), and ATP-binding cassette transporter A1 (ABCA1). The aim of this study was to investigate the beneficial effects of kimchi methanol extract (KME) and a kimchi active compound, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA) on cholesterol flux in THP-1-derived macrophages treated with oxLDL. The effects of KME and HDMPPA on cell viability and lipid peroxidation were determined. Furthermore, the protein expression of PPARγ, CD36, PPARα, LXRα, and ABCA1 was examined. OxLDL strongly induced cell death and lipid peroxidation in THP-1-derived macrophages. However, KME and HDMPPA significantly improved cell viability and inhibited lipid peroxidation induced by oxLDL in THP-1-derived macrophages (P<.05). Moreover, KME and HDMPPA suppressed CD36 and PPARγ expressions, both of which participate in cholesterol influx. In contrast, KME and HDMPPA augmented LXRα, PPARα, and ABCA1 expression, which are associated with cholesterol efflux. Consequently, KME and HDMPPA suppressed lipid accumulation. These results indicate that KME and HDMPPA may inhibit lipid accumulation, in part, by regulating cholesterol influx- and efflux-related proteins. These findings will thus be useful for future prevention strategies against atherosclerosis.

Rod outer segment retinol formation is independent of Abca4, arrestin, rhodopsin kinase, and rhodopsin palmitylation.

PubMed

Blakeley, Lorie R; Chen, Chunhe; Chen, Ching-Kang; Chen, Jeannie; Crouch, Rosalie K; Travis, Gabriel H; Koutalos, Yiannis

2011-06-01

The reactive aldehyde all-trans retinal is released in rod photoreceptor outer segments by photoactivated rhodopsin and is eliminated through reduction to all-trans retinol. This study was undertaken to determine whether all-trans retinol formation depends on Abca4, arrestin, rhodopsin kinase, and the palmitylation of rhodopsin, all of which are factors that affect the release and sequestration of all-trans retinal. Experiments were performed in isolated retinas and single living rods derived from 129/sv wild-type mice and Abca4-, arrestin-, and rhodopsin kinase-deficient mice and in genetically modified mice containing unpalmitylated rhodopsin. Formation of all-trans retinol was measured by imaging its fluorescence and by HPLC of retina extracts. The release of all-trans retinal from photoactivated rhodopsin was measured in purified rod outer segment membranes according to the increase in tryptophan fluorescence. All experiments were performed at 37°C. The kinetics of all-trans retinol formation in the different types of genetically modified mice are in reasonable agreement with those in wild-type animals. The kinetics of all-trans retinol formation in 129/sv mice are similar to those in C57BL/6, although the latter are known to regenerate rhodopsin much more slowly. The release of all-trans retinal from rhodopsin in purified membranes is significantly faster than the formation of all-trans retinol in intact cells and is independent of the presence of the palmitate groups. The regeneration of rhodopsin and the recycling of its chromophore are not strongly coupled. Neither the activities of Abca4, rhodopsin kinase, and arrestin, nor the palmitylation of rhodopsin affects the formation of all-trans retinol.

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

Yue, Jianmei; Department of Endocrinology, The First Hospital of Zibo, 4# E Mei Shan Dong Road, Zibo 255200; Li, Bo, E-mail: libosubmit@163.com

Objectives: Cholesterol efflux has been thought to be the main and basic mechanism by which free cholesterol is transferred from extra hepatic cells to the liver or intestine for excretion. Salvianolic acid B (Sal B) has been widely used for the prevention and treatment of atherosclerotic diseases. Here, we sought to investigate the effects of Sal B on the cholesterol efflux in THP-1 macrophages. Methods: After PMA-stimulated THP-1 cells were exposed to 50 mg/L of oxLDL and [{sup 3}H] cholesterol (1.0 μCi/mL) for another 24 h, the effect of Sal B on cholesterol efflux was evaluated in the presence of apoA-1, HDL{sub 2}more » or HDL{sub 3}. The expression of ATP binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-gamma (PPAR-γ), and liver X receptor-alpha (LXRα) was detected both at protein and mRNA levels in THP-1 cells after the stimulation of Sal B. Meanwhile, specific inhibition of PPAR-γ and LXRα were performed to investigate the mechanism. Results: The results showed that Sal B significantly accelerated apoA-I- and HDL-mediated cholesterol efflux in both dose- and time-dependent manners. Meanwhile, Sal B treatment also enhanced the expression of ABCA1 at both mRNA and protein levels. Then the data demonstrated that Sal B increased the expression of PPAR-γ and LXRα. And the application of specific agonists and inhibitors of further confirmed that Sal exert the function through PPAR-γ and LXRα. Conclusion: These results demonstrate that Sal B promotes cholesterol efflux in THP-1 macrophages through ABCA1/PPAR-γ/LXRα pathway. - Highlights: • Sal B promotes the expression of ABCA1. • Sal B promotes cholesterol efflux in macrophages. • Sal B promotes the expression of ABCA1 and cholesterol efflux through PPAR-γ/LXRα signaling pathway.« less

Retinal phenotypic characterization of patients with ABCA4 retinopathydue to the homozygous p.Ala1773Val mutation

PubMed Central

López-Rubio, Salvador; Chacon-Camacho, Oscar F.; Matsui, Rodrigo; Guadarrama-Vallejo, Dalia; Astiazarán, Mirena C.

2018-01-01

Purpose To describe the retinal clinical features of a group of Mexican patients with Stargardt disease carrying the uncommon p.Ala1773Val founder mutation in ABCA4. Methods Ten patients carrying the p.Ala1773Val mutation, nine of them homozygously, were included. Visual function studies included best-corrected visual acuity, electroretinography, Goldmann kinetic visual fields, and full-field electroretinography (ERG). In addition, imaging studies, such as optical coherence tomography (OCT), short-wave autofluorescence imaging, and quantitative analyses of hypofluorescence, were performed in each patient. Results Best-corrected visual acuities ranged from 20/200 to 4/200. The median age of the patients at diagnosis was 23.3 years. The majority of the patients had photophobia and nyctalopia, and were classified as Fishman stage 4 (widespread choriocapillaris atrophy, resorption of flecks, and greatly reduced ERG amplitudes). An atypical retinal pigmentation pattern was observed in the patients, and the majority showed cone-rod dystrophy on full-field ERG. In vivo retinal microstructure assessment with OCT demonstrated central retinal thinning, variable loss of photoreceptors, and three different patterns of structural retinal degeneration. Two dissimilar patterns of abnormal autofluorescence were observed. No apparent age-related differences in the pattern of retinal degeneration were observed. Conclusions The results indicate that this particular mutation in ABCA4 is associated with a severe retinal phenotype and thus, could be classified as null. Careful phenotyping of patients carrying specific mutations in ABCA4 is essential to enhance our understanding of disease expression linked to particular mutations and the resulting genotype–phenotype correlations. PMID:29422768

Predicting Progression of ABCA4-Associated Retinal Degenerations Based on Longitudinal Measurements of the Leading Disease Front

PubMed Central

Cideciyan, Artur V.; Swider, Malgorzata; Schwartz, Sharon B.; Stone, Edwin M.; Jacobson, Samuel G.

2015-01-01

Purpose To evaluate the progression of the earliest stage of disease in ABCA4-associated retinal degenerations (RDs). Methods Near-infrared excited reduced-illuminance autofluorescence imaging was acquired across the retina up to 80 degrees eccentricity in 44 patients with two ABCA4 alleles. The eccentricity of the leading disease front (LDF) corresponding to the earliest stage of disease was measured along the four meridians. A mathematical model describing the expansion of the LDF was developed based on 6 years of longitudinal follow-up. Results The extent of LDF along the superior, inferior, and temporal meridians showed a wide spectrum from 3.5 to 70 degrees. In patients with longitudinal data, the average centrifugal expansion rate was 2 degrees per year. The nasal extent of LDF between the fovea and ONH ranged from 4.3 to 16.5 degrees and expanded at 0.35 degrees per year. The extent of LDF beyond ONH ranged from 19 to 75 degrees and expanded on average at 2 degrees per year. A mathematical model fit well to the longitudinal data describing the expansion of the LDF. Conclusions The eccentricity of the LDF in ABCA4-RD shows a continuum from parafovea to far periphery along all four meridians consistent with a wide spectrum of severity observed clinically. The model of progression may provide a quantitative prediction of the LDF expansion based on the age and eccentricity of the LDF at a baseline visit, and thus contribute significantly to the enrollment of candidates appropriate for clinical trials planning specific interventions, efficacy outcomes, and durations. PMID:26377081

Deficiency of ATP-binding cassette transporters A1 and G1 in macrophages increases inflammation and accelerates atherosclerosis in mice.

PubMed

Westerterp, Marit; Murphy, Andrew J; Wang, Mi; Pagler, Tamara A; Vengrenyuk, Yuliya; Kappus, Mojdeh S; Gorman, Darren J; Nagareddy, Prabhakara R; Zhu, Xuewei; Abramowicz, Sandra; Parks, John S; Welch, Carrie; Fisher, Edward A; Wang, Nan; Yvan-Charvet, Laurent; Tall, Alan R

2013-05-24

Plasma high-density lipoprotein levels are inversely correlated with atherosclerosis. Although it is widely assumed that this is attributable to the ability of high-density lipoprotein to promote cholesterol efflux from macrophage foam cells, direct experimental support for this hypothesis is lacking. To assess the role of macrophage cholesterol efflux pathways in atherogenesis. We developed mice with efficient deletion of the ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1) in macrophages (MAC-ABC(DKO) mice) but not in hematopoietic stem or progenitor populations. MAC-ABC(DKO) bone marrow (BM) was transplanted into Ldlr(-/-) recipients. On the chow diet, these mice had similar plasma cholesterol and blood monocyte levels but increased atherosclerosis compared with controls. On the Western-type diet, MAC-ABC(DKO) BM-transplanted Ldlr(-/-) mice had disproportionate atherosclerosis, considering they also had lower very low-density lipoprotein/low-density lipoprotein cholesterol levels than controls. ABCA1/G1-deficient macrophages in lesions showed increased inflammatory gene expression. Unexpectedly, Western-type diet-fed MAC-ABC(DKO) BM-transplanted Ldlr(-/-) mice displayed monocytosis and neutrophilia in the absence of hematopoietic stem and multipotential progenitor cells proliferation. Mechanistic studies revealed increased expressions of machrophage colony stimulating factor and granulocyte colony stimulating factor in splenic macrophage foam cells, driving BM monocyte and neutrophil production. These studies show that macrophage deficiency of ABCA1/G1 is proatherogenic likely by promoting plaque inflammation and uncover a novel positive feedback loop in which cholesterol-laden splenic macrophages signal BM progenitors to produce monocytes, with suppression by macrophage cholesterol efflux pathways.

Overexpression and deletion of phospholipid transfer protein reduce HDL mass and cholesterol efflux capacity but not macrophage reverse cholesterol transport[S

PubMed Central

Kuwano, Takashi; Bi, Xin; Cipollari, Eleonora; Yasuda, Tomoyuki; Lagor, William R.; Szapary, Hannah J.; Tohyama, Junichiro; Millar, John S.; Billheimer, Jeffrey T.; Lyssenko, Nicholas N.; Rader, Daniel J.

2017-01-01

Phospholipid transfer protein (PLTP) may affect macrophage reverse cholesterol transport (mRCT) through its role in the metabolism of HDL. Ex vivo cholesterol efflux capacity and in vivo mRCT were assessed in PLTP deletion and PLTP overexpression mice. PLTP deletion mice had reduced HDL mass and cholesterol efflux capacity, but unchanged in vivo mRCT. To directly compare the effects of PLTP overexpression and deletion on mRCT, human PLTP was overexpressed in the liver of wild-type animals using an adeno-associated viral (AAV) vector, and control and PLTP deletion animals were injected with AAV-null. PLTP overexpression and deletion reduced plasma HDL mass and cholesterol efflux capacity. Both substantially decreased ABCA1-independent cholesterol efflux, whereas ABCA1-dependent cholesterol efflux remained the same or increased, even though preβ HDL levels were lower. Neither PLTP overexpression nor deletion affected excretion of macrophage-derived radiocholesterol in the in vivo mRCT assay. The ex vivo and in vivo assays were modified to gauge the rate of cholesterol efflux from macrophages to plasma. PLTP activity did not affect this metric. Thus, deviations in PLTP activity from the wild-type level reduce HDL mass and ex vivo cholesterol efflux capacity, but not the rate of macrophage cholesterol efflux to plasma or in vivo mRCT. PMID:28137768

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.

Adaptor protein containing PH domain, PTB domain and leucine zipper (APPL1) regulates the protein level of EGFR by modulating its trafficking

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

Lee, Jae-Rin; Hahn, Hwa-Sun; Kim, Young-Hoon

2011-11-11

Highlights: Black-Right-Pointing-Pointer APPL1 regulates the protein level of EGFR in response to EGF stimulation. Black-Right-Pointing-Pointer Depletion of APPL1 accelerates the movement of EGF/EGFR from the cell surface to the perinuclear region in response to EGF. Black-Right-Pointing-Pointer Knockdown of APPL1 enhances the activity of Rab5. -- Abstract: The EGFR-mediated signaling pathway regulates multiple biological processes such as cell proliferation, survival and differentiation. Previously APPL1 (adaptor protein containing PH domain, PTB domain and leucine zipper 1) has been reported to function as a downstream effector of EGF-initiated signaling. Here we demonstrate that APPL1 regulates EGFR protein levels in response to EGF stimulation.more » Overexpression of APPL1 enhances EGFR stabilization while APPL1 depletion by siRNA reduces EGFR protein levels. APPL1 depletion accelerates EGFR internalization and movement of EGF/EGFR from cell surface to the perinuclear region in response to EGF treatment. Conversely, overexpression of APPL1 decelerates EGFR internalization and translocation of EGF/EGFR to the perinuclear region. Furthermore, APPL1 depletion enhances the activity of Rab5 which is involved in internalization and trafficking of EGFR and inhibition of Rab5 in APPL1-depleted cells restored EGFR levels. Consistently, APPL1 depletion reduced activation of Akt, the downstream signaling effector of EGFR and this is restored by inhibition of Rab5. These findings suggest that APPL1 is required for EGFR signaling by regulation of EGFR stabilities through inhibition of Rab5.« less

COPS5 (Jab1) protein increases β site processing of amyloid precursor protein and amyloid β peptide generation by stabilizing RanBP9 protein levels.

PubMed

Wang, Hongjie; Dey, Debleena; Carrera, Ivan; Minond, Dmitriy; Bianchi, Elisabetta; Xu, Shaohua; Lakshmana, Madepalli K

2013-09-13

Increased processing of amyloid precursor protein (APP) and accumulation of neurotoxic amyloid β peptide (Aβ) in the brain is central to the pathogenesis of Alzheimer's disease (AD). Therefore, the identification of molecules that regulate Aβ generation is crucial for future therapeutic approaches for AD. We demonstrated previously that RanBP9 regulates Aβ generation in a number of cell lines and primary neuronal cultures by forming tripartite protein complexes with APP, low-density lipoprotein-related protein, and BACE1, consequently leading to increased amyloid plaque burden in the brain. RanBP9 is a scaffold protein that exists and functions in multiprotein complexes. To identify other proteins that may bind RanBP9 and regulate Aβ levels, we used a two-hybrid analysis against a human brain cDNA library and identified COPS5 as a novel RanBP9-interacting protein. This interaction was confirmed by coimmunoprecipitation experiments in both neuronal and non-neuronal cells and mouse brain. Colocalization of COPS5 and RanBP9 in the same subcellular compartments further supported the interaction of both proteins. Furthermore, like RanBP9, COPS5 robustly increased Aβ generation, followed by increased soluble APP-β (sAPP-β) and decreased soluble-APP-α (sAPP-α) levels. Most importantly, down-regulation of COPS5 by siRNAs reduced Aβ generation, implying that endogenous COPS5 regulates Aβ generation. Finally, COPS5 levels were increased significantly in AD brains and APΔE9 transgenic mice, and overexpression of COPS5 strongly increased RanBP9 protein levels by increasing its half-life. Taken together, these results suggest that COPS5 increases Aβ generation by increasing RanBP9 levels. Thus, COPS5 is a novel RanBP9-binding protein that increases APP processing and Aβ generation by stabilizing RanBP9 protein levels.

The detection of autoantibodies to ATP-binding cassette transporter A1 and its role in the pathogenesis of atherosclerosis in patients with systemic lupus erythematosus.

PubMed

Zeng, Ting; Li, Shu-Jie; Ao, Wen; Zheng, Hui; Wu, Feng-Xia; Chen, Yi; Yang, Cheng-De

2012-11-01

To investigate the prevalence of autoantibodies against ATP-binding cassette transporter A1 (ABCA1) in SLE patients, and evaluate the association between anti-ABCA1 autoantibodies and atherosclerosis in SLE. The sera of 75 SLE patients and 75 healthy controls were tested by immunoblotting. Then, we examined the effect of anti-ABCA1 autoantibodies on cholesterol efflux in vitro. The prevalence of anti-ABCA1 antibodies in SLE patients was significantly higher than the controls (p<0.05). The prevalence in the SLE-plaque group was higher than that in the SLE-non-plaque group (p<0.05). The IgG purified from anti-ABCA1-antibody positive sera can inhibit cellular cholesterol efflux from THP-1 cells in vitro with a significantly higher inhibition ratio than that of the healthy controls. Our observations suggest that anti-ABCA1 autoantibodies are involved in the pathogenesis of lupus atherosclerosis and that autoantibodies against ABCA1 may act as biomarkers for atherosclerosis in SLE. Copyright © 2012 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Myb-binding protein 1a (Mybbp1a) regulates levels and processing of pre-ribosomal RNA.

PubMed

Hochstatter, Julia; Hölzel, Michael; Rohrmoser, Michaela; Schermelleh, Lothar; Leonhardt, Heinrich; Keough, Rebecca; Gonda, Thomas J; Imhof, Axel; Eick, Dirk; Längst, Gernot; Németh, Attila

2012-07-13

Ribosomal RNA gene transcription, co-transcriptional processing, and ribosome biogenesis are highly coordinated processes that are tightly regulated during cell growth. In this study we discovered that Mybbp1a is associated with both the RNA polymerase I complex and the ribosome biogenesis machinery. Using a reporter assay that uncouples transcription and RNA processing, we show that Mybbp1a represses rRNA gene transcription. In addition, overexpression of the protein reduces RNA polymerase I loading on endogenous rRNA genes as revealed by chromatin immunoprecipitation experiments. Accordingly, depletion of Mybbp1a results in an accumulation of the rRNA precursor in vivo but surprisingly also causes growth arrest of the cells. This effect can be explained by the observation that the modulation of Mybbp1a protein levels results in defects in pre-rRNA processing within the cell. Therefore, the protein may play a dual role in the rRNA metabolism, potentially linking and coordinating ribosomal DNA transcription and pre-rRNA processing to allow for the efficient synthesis of ribosomes.

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.

Roux-en-Y gastric bypass surgery suppresses hypothalamic PTP1B protein level and alleviates leptin resistance in obese rats

PubMed Central

Liu, Jia-Yu; Mu, Song; Zhang, Shu-Ping; Guo, Wei; Li, Qi-Fu; Xiao, Xiao-Qiu; Zhang, Jun; Wang, Zhi-Hong

2017-01-01

The present study aimed to explore the effect of Roux-en-Y gastric bypass (RYGB) surgery on protein tyrosine phosphatase 1B (PTP1B) expression levels and leptin activity in hypothalami of obese rats. Obese rats induced by a high-fat diet (HFD) that underwent RYGB (n=11) or sham operation (SO, n=9), as well as an obese control cohort (Obese, n=10) and an additional normal-diet group (ND, n=10) were used. Food efficiency was measured at 8 weeks post-operation. Plasma leptin levels were evaluated and hypothalamic protein tyrosine phosphatase 1B (PTP1B) levels and leptin signaling activity were examined at the genetic and protein levels. The results indicated that food efficiency was typically lower in RYGB rats compared with that in the Obese and SO rats. In the RYGB group, leptin receptor expression and proopiomelanocortin was significantly higher, while Neuropeptide Y levels were lower than those in the Obese and SO groups. Furthermore, the gene and protein expression levels of PTP1B in the RYGB group were lower, while levels of phosphorylated signal transducer and activator of transcription 3 protein were much higher compared with those in the Obese and SO groups. In conclusion, RYGB surgery significantly suppressed hypothalamic PTP1B protein expression. PTP1B regulation may partially alleviate leptin resistance. PMID:28947917

Roux-en-Y gastric bypass surgery suppresses hypothalamic PTP1B protein level and alleviates leptin resistance in obese rats.

PubMed

Liu, Jia-Yu; Mu, Song; Zhang, Shu-Ping; Guo, Wei; Li, Qi-Fu; Xiao, Xiao-Qiu; Zhang, Jun; Wang, Zhi-Hong

2017-09-01

The present study aimed to explore the effect of Roux-en-Y gastric bypass (RYGB) surgery on protein tyrosine phosphatase 1B (PTP1B) expression levels and leptin activity in hypothalami of obese rats. Obese rats induced by a high-fat diet (HFD) that underwent RYGB (n=11) or sham operation (SO, n=9), as well as an obese control cohort (Obese, n=10) and an additional normal-diet group (ND, n=10) were used. Food efficiency was measured at 8 weeks post-operation. Plasma leptin levels were evaluated and hypothalamic protein tyrosine phosphatase 1B (PTP1B) levels and leptin signaling activity were examined at the genetic and protein levels. The results indicated that food efficiency was typically lower in RYGB rats compared with that in the Obese and SO rats. In the RYGB group, leptin receptor expression and proopiomelanocortin was significantly higher, while Neuropeptide Y levels were lower than those in the Obese and SO groups. Furthermore, the gene and protein expression levels of PTP1B in the RYGB group were lower, while levels of phosphorylated signal transducer and activator of transcription 3 protein were much higher compared with those in the Obese and SO groups. In conclusion, RYGB surgery significantly suppressed hypothalamic PTP1B protein expression. PTP1B regulation may partially alleviate leptin resistance.

Effect of Lipoic Acid on Serum Paraoxonase-1 and Paraoxonase-3 Protein Levels and Activities in Diabetic Rats.

PubMed

Ozgun, E; Ozgun, G S; Gokmen, S S; Eskıocak, S; Sut, N; Akıncı, M; Goncu, E; Cakır, E

2016-02-05

The aim of the present study was to investigate the effect of streptozotocin-induced diabetes mellitus and lipoic acid treatment on serum paraoxonase-1 and paraoxonase-3 protein levels and paraoxonase, arylesterase and lactonase activities.36 rats were equally and randomly divided into 4 groups as control, lipoic acid, diabetes and diabetes+lipoic acid. To induce diabetes, a single dose of streptozotocin (40 mg/kg) was injected intraperitoneally to diabetes and diabetes+lipoic acid groups. Lipoic acid (10 mg/kg/day) was injected intraperitoneally for 14 days to lipoic acid and diabetes+lipoic acid groups. Serum PON1 and PON3 protein levels were measured by western blotting. Serum paraoxonase, arylesterase and lactonase activities were determined by the measuring initial rate of substrate (paraoxon, phenylacetate and dihydrocoumarin) hydrolysis.Streptozotocin-induced diabetes mellitus caused a significant decrease whereas lipoic acid treatment caused a significant increase in serum PON1 and PON3 protein levels and paraoxonase, arylesterase and lactonase activities. The increase percent of serum PON3 protein was higher than that of serum PON1 protein and the increase percent of serum lactonase activity was higher than that of serum paraoxonase and arylesterase activities in diabetes+lipoic acid group.We can report that, like PON1 protein, PON3 protein and actually its lactonase activity may also have a role as an antioxidant in diabetes mellitus and lipoic acid treatment may be useful for the prevention of the atherosclerotic complications of diabetes by increasing serum PON1 and PON3 protein levels and serum enzyme activities. © Georg Thieme Verlag KG Stuttgart · New York.

The influence of acute resistance exercise on cyclooxygenase-1 and -2 activity and protein levels in human skeletal muscle.

PubMed

Carroll, Chad C; O'Connor, Devin T; Steinmeyer, Robert; Del Mundo, Jonathon D; McMullan, David R; Whitt, Jamie A; Ramos, Jahir E; Gonzales, Rayna J

2013-07-01

This study evaluated the activity and content of cyclooxygenase (COX)-1 and -2 in response to acute resistance exercise (RE) in human skeletal muscle. Previous work suggests that COX-1, but not COX-2, is the primary COX isoform elevated with resistance exercise in human skeletal muscle. COX activity, however, has not been assessed after resistance exercise in humans. It was hypothesized that RE would increase COX-1 but not COX-2 activity. Muscle biopsies were taken from the vastus lateralis of nine young men (25 ± 1 yr) at baseline (preexercise), 4, and 24 h after a single bout of knee extensor RE (three sets of 10 repetitions at 70% of maximum). Tissue lysate was assayed for COX-1 and COX-2 activity. COX-1 and COX-2 protein levels were measured via Western blot analysis. COX-1 activity increased at 4 h (P < 0.05) compared with preexercise, but returned to baseline at 24 h (PRE: 60 ± 10, 4 h: 106 ± 22, 24 h: 72 ± 8 nmol PGH2·g total protein(-1)·min(-1)). COX-2 activity was elevated at 4 and 24 h after RE (P < 0.05, PRE: 51 ± 7, 4 h: 100 ± 19, 24 h: 98 ± 14 nmol PGH2·g total protein(-1)·min(-1)). The protein level of COX-1 was not altered (P > 0.05) with acute RE. In contrast, COX-2 protein levels were nearly 3-fold greater (P > 0.05) at 4 h and 5-fold greater (P = 0.06) at 24 h, compared with preexercise. In conclusion, COX-1 activity increases transiently with exercise independent of COX-1 protein levels. In contrast, both COX-2 activity and protein levels were elevated with exercise, and this elevation persisted to at least 24 h after RE.

Vitamin E Secretion by Caco-2 Monolayers to APOA1, but Not to HDL, Is Vitamer Selective12

PubMed Central

Nicod, Nathalie; Parker, Robert S.

2013-01-01

The aim of this study was to characterize the pathways of basolateral secretion of common dietary tocopherols from polarized Caco-2 monolayers, a model of intestinal absorption. Given differences in structure and physical properties, we hypothesized that secretion may differ between different forms of vitamin E, thus potentially contribute to the selectivity seen in vivo. Monolayers were incubated apically and simultaneously with 10 μmol/L α-, γ-, and δ-tocopherol (1:1:1) in lipid micelles. Treatment with the microsomal triglyceride transfer protein inhibitor BMS201038 revealed that the triglyceride-rich particle secretory pathway (apolipoprotein B–dependent pathway) accounted for ∼80% of total tocopherol secretion, without selectivity among the three forms of vitamin E. Apolipoprotein B–independent secretion of tocopherols (and cholesterol) was greatly enhanced by the liver X receptor agonist T0901317. T0901317 induced ATP-binding cassette transporter A1 (ABCA1) protein expression and basolateral secretion of tocopherols to apolipoprotein A1. ABCA1-dependent secretion demonstrated vitamer selectivity such that efficiency of secretion of α- and γ-tocopherols exceeded that of δ-tocopherol. Basal addition of HDL stimulated vitamin E secretion but without selectivity among the three forms, whereas LDL had no effect. Basal addition of scavenger receptor class B member I (SR-BI) blocking antibody, which inhibits the interaction between SR-BI and HDL, increased basal accumulation of all tocopherols, demonstrating a role for SR-BI in cellular re-uptake of secreted vitamin E. These findings demonstrated that vitamin E and cholesterol utilize common pathways of secretion and that secretion via the ABCA1 pathway favors certain forms of vitamin E. PMID:23946344

Increased maternal and fetal cholesterol efflux capacity and placental CYP27A1 expression in preeclampsia.

PubMed

Mistry, Hiten D; Kurlak, Lesia O; Mansour, Yosef T; Zurkinden, Line; Mohaupt, Markus G; Escher, Geneviève

2017-06-01

Preeclampsia is a pregnancy-specific condition that leads to increased cardiovascular risk in later life. A decrease in cholesterol efflux capacity is linked to CVD. We hypothesized that in preeclampsia there would be a disruption of maternal/fetal plasma to efflux cholesterol, as well as differences in the concentrations of both placental sterol 27-hydroxylase (CYP27A1) and apoA1 binding protein (AIBP). Total, HDL-, and ABCA1-mediated cholesterol effluxes were performed with maternal and fetal plasma from women with preeclampsia and normotensive controls (both n = 17). apoA1 and apoE were quantified by chemiluminescence, and 27-hydroxycholesterol (27-OHC) by GC-MS. Immunohistochemistry was used to determine placental expression/localization of CYP27A1, AIBP, apoA1, apoE, and SRB1. Maternal and fetal total and HDL-mediated cholesterol efflux capacities were increased in preeclampsia (by 10-20%), but ABCA1-mediated efflux was decreased (by 20-35%; P < 0.05). Maternal and fetal apoE concentrations were higher in preeclampsia. Fetal plasma 27-OHC levels were decreased in preeclamptic samples ( P < 0.05). Placental protein expression of both CYP27A1 and AIBP were localized around fetal vessels and significantly increased in preeclampsia ( P = 0.04). Placental 27-OHC concentrations were also raised in preeclampsia ( P < 0.05). Increased HDL-mediated cholesterol efflux capacity and placental CYP27A1/27-OHC could be a rescue mechanism in preeclampsia, to remove cholesterol from cells to limit lipid peroxidation and increase placental angiogenesis. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

Sequence variations and protein expression levels of the two immune evasion proteins Gpm1 and Pra1 influence virulence of clinical Candida albicans isolates.

PubMed

Luo, Shanshan; Hipler, Uta-Christina; Münzberg, Christin; Skerka, Christine; Zipfel, Peter F

2015-01-01

Candida albicans, the important human fungal pathogen uses multiple evasion strategies to control, modulate and inhibit host complement and innate immune attack. Clinical C. albicans strains vary in pathogenicity and in serum resistance, in this work we analyzed sequence polymorphisms and variations in the expression levels of two central fungal complement evasion proteins, Gpm1 (phosphoglycerate mutase 1) and Pra1 (pH-regulated antigen 1) in thirteen clinical C. albicans isolates. Four nucleotide (nt) exchanges, all representing synonymous exchanges, were identified within the 747-nt long GPM1 gene. For the 900-nt long PRA1 gene, sixteen nucleotide exchanges were identified, which represented synonymous, as well as non-synonymous exchanges. All thirteen clinical isolates had a homozygous exchange (A to G) at position 73 of the PRA1 gene. Surface levels of Gpm1 varied by 8.2, and Pra1 levels by 3.3 fold in thirteen tested isolates and these differences influenced fungal immune fitness. The high Gpm1/Pra1 expressing candida strains bound the three human immune regulators more efficiently, than the low expression strains. The difference was 44% for Factor H binding, 51% for C4BP binding and 23% for plasminogen binding. This higher Gpm1/Pra1 expressing strains result in enhanced survival upon challenge with complement active, Factor H depleted human serum (difference 40%). In addition adhesion to and infection of human endothelial cells was increased (difference 60%), and C3b surface deposition was less effective (difference 27%). Thus, variable expression levels of central immune evasion protein influences immune fitness of the human fungal pathogen C. albicans and thus contribute to fungal virulence.

Aerobic exercise improves reverse cholesterol transport in cholesteryl ester transfer protein transgenic mice.

PubMed

Rocco, D D F M; Okuda, L S; Pinto, R S; Ferreira, F D; Kubo, S K; Nakandakare, E R; Quintão, E C R; Catanozi, S; Passarelli, M

2011-07-01

We analyzed the effect of a 6-week aerobic exercise training program on the in vivo macrophage reverse cholesterol transport (RCT) in human cholesteryl ester transfer protein (CETP) transgenic (CETP-tg) mice. Male CETP-tg mice were randomly assigned to a sedentary group or a carefully supervised exercise training group (treadmill 15 m/min, 30 min sessions, five sessions per week). The levels of plasma lipids were determined by enzymatic methods, and the lipoprotein profile was determined by fast protein liquid chromatography (FPLC). CETP activity was determined by measuring the transfer rate of ¹⁴C-cholesterol from HDL to apo-B containing lipoproteins, using plasma from CETP-tg mice as a source of CETP. The reverse cholesterol transport was determined in vivo by measuring the [³H]-cholesterol recovery in plasma and feces (24 and 48 h) and in the liver (48 h) following a peritoneal injection of [³H]-cholesterol labeled J774-macrophages into both sedentary and exercise trained mice. The protein levels of liver receptors were determined by immunoblot, and the mRNA levels for liver enzymes were measured using RT-PCR. Exercise training did not significantly affect the levels of plasma lipids or CETP activity. The HDL fraction assessed by FPLC was higher in exercise-trained compared to sedentary mice. In comparison to the sedentary group, a greater recovery of [³H]-cholesterol from the injected macrophages was found in the plasma, liver and feces of exercise-trained animals. The latter occurred even with a reduction in the liver CYP7A1 mRNA level in exercised trained animals. Exercise training increased the liver LDL receptor and ABCA-1 protein levels, although the SR-BI protein content was unchanged. The RCT benefit in CETP-tg mice elicited by exercise training helps to elucidate the role of exercise in the prevention of atherosclerosis in humans.

A Comprehensive Survey of Sequence Variation in the ABCA4 (ABCR) Gene in Stargardt Disease and Age-Related Macular Degeneration

PubMed Central

Rivera, Andrea; White, Karen; Stöhr, Heidi; Steiner, Klaus; Hemmrich, Nadine; Grimm, Timo; Jurklies, Bernhard; Lorenz, Birgit; Scholl, Hendrik P. N.; Apfelstedt-Sylla, Eckhart; Weber, Bernhard H. F.

2000-01-01

Stargardt disease (STGD) is a common autosomal recessive maculopathy of early and young-adult onset and is caused by alterations in the gene encoding the photoreceptor-specific ATP-binding cassette (ABC) transporter (ABCA4). We have studied 144 patients with STGD and 220 unaffected individuals ascertained from the German population, to complete a comprehensive, population-specific survey of the sequence variation in the ABCA4 gene. In addition, we have assessed the proposed role for ABCA4 in age-related macular degeneration (AMD), a common cause of late-onset blindness, by studying 200 affected individuals with late-stage disease. Using a screening strategy based primarily on denaturing gradient gel electrophoresis, we have identified in the three study groups a total of 127 unique alterations, of which 90 have not been previously reported, and have classified 72 as probable pathogenic mutations. Of the 288 STGD chromosomes studied, mutations were identified in 166, resulting in a detection rate of ∼58%. Eight different alleles account for 61% of the identified disease alleles, and at least one of these, the L541P-A1038V complex allele, appears to be a founder mutation in the German population. When the group with AMD and the control group were analyzed with the same methodology, 18 patients with AMD and 12 controls were found to harbor possible disease-associated alterations. This represents no significant difference between the two groups; however, for detection of modest effects of rare alleles in complex diseases, the analysis of larger cohorts of patients may be required. PMID:10958763

A comprehensive survey of sequence variation in the ABCA4 (ABCR) gene in Stargardt disease and age-related macular degeneration.

PubMed

Rivera, A; White, K; Stöhr, H; Steiner, K; Hemmrich, N; Grimm, T; Jurklies, B; Lorenz, B; Scholl, H P; Apfelstedt-Sylla, E; Weber, B H

2000-10-01

Stargardt disease (STGD) is a common autosomal recessive maculopathy of early and young-adult onset and is caused by alterations in the gene encoding the photoreceptor-specific ATP-binding cassette (ABC) transporter (ABCA4). We have studied 144 patients with STGD and 220 unaffected individuals ascertained from the German population, to complete a comprehensive, population-specific survey of the sequence variation in the ABCA4 gene. In addition, we have assessed the proposed role for ABCA4 in age-related macular degeneration (AMD), a common cause of late-onset blindness, by studying 200 affected individuals with late-stage disease. Using a screening strategy based primarily on denaturing gradient gel electrophoresis, we have identified in the three study groups a total of 127 unique alterations, of which 90 have not been previously reported, and have classified 72 as probable pathogenic mutations. Of the 288 STGD chromosomes studied, mutations were identified in 166, resulting in a detection rate of approximately 58%. Eight different alleles account for 61% of the identified disease alleles, and at least one of these, the L541P-A1038V complex allele, appears to be a founder mutation in the German population. When the group with AMD and the control group were analyzed with the same methodology, 18 patients with AMD and 12 controls were found to harbor possible disease-associated alterations. This represents no significant difference between the two groups; however, for detection of modest effects of rare alleles in complex diseases, the analysis of larger cohorts of patients may be required.

TREM-1 SNP rs2234246 regulates TREM-1 protein and mRNA levels and is associated with plasma levels of L-selectin

PubMed Central

Aldasoro Arguinano, Alex-Ander; Dadé, Sébastien; Stathopoulou, Maria; Derive, Marc; Coumba Ndiaye, Ndeye; Xie, Ting; Masson, Christine; Gibot, Sébastien

2017-01-01

High levels of TREM-1 are associated with cardiovascular and inflammatory diseases risks and the most recent studies have showed that TREM-1 deletion or blockade is associated with up to 60% reduction of the development of atherosclerosis. So far, it is unknown whether the levels of TREM-1 protein are genetically regulated. Moreover, TREM family receptors have been suggested to regulate the cellular adhesion process. The goal of this study was to investigate whether polymorphisms within TREM-1 are regulating the variants of serum TREM-1 levels and the expression levels of their mRNA. Furthermore, we aimed to point out associations between polymorphisms on TREM-1 and blood levels of selectins. Among the 10 SNPs studied, the minor allele T of rs2234246, was associated with increased sTREM-1 in the discovery population (p-value = 0.003), explaining 33% of its variance, and with increased levels of mRNA (p-value = 0.007). The same allele was associated with increased soluble L-selectin levels (p-value = 0.011). The higher levels of sTREM-1 and L-selectin were confirmed in the replication population (p-value = 0.0007 and p-value = 0.018 respectively). We demonstrated for the first time one SNP on TREM-1, affecting its expression levels. These novel results, support the hypothesis that TREM-1 affects monocytes extravasation and accumulation processes leading to atherogenesis and atherosclerotic plaque progression, possibly through increased inflammation and subsequent higher expression of sL-selectin. PMID:28771614

Promoter polymorphisms in the ATP binding cassette transporter gene influence production of cell-derived microparticles and are highly associated with susceptibility to severe malaria in humans.

PubMed

Sahu, Upasana; Mohapatra, Biranchi N; Kar, Shantanu K; Ranjit, Manoranjan

2013-04-01

Microparticle (MP) efflux is known to be mediated by the ABCA1 protein, and the plasma level of these cell-derived MPs is elevated considerably during human malarial infection. Therefore, two polymorphisms at positions -477 and -320 in the promoter of the ABCA1 gene were genotyped and tested for association with the plasma MP level in four groups of malaria patients segregated according to the clinical severity, i.e., cerebral malaria (CM), multiorgan dysfunction (MOD), noncerebral severe malaria, and uncomplicated malaria (UM). The TruCount tube-based flow cytometric method was used for the exact quantification of different cell-derived MPs in patients. Polymorphisms in the ABCA1 gene promoter were analyzed by use of the PCR/two-primer-pair method, followed by restriction fragment length polymorphism, in 428 malaria patients. The level of circulating plasma MPs was significantly higher in febrile patients with Plasmodium falciparum infection, especially in CM patients compared to healthy individuals. The homozygous wild-type -477 and -320 genotype was observed to be significantly higher in patients with severe malaria. These patients also showed marked increases in the plasma MP numbers compared to UM patients. We report here for the first time an association of ABCA1 promoter polymorphisms with susceptibility to severe malaria, especially to CM and MOD, indicating the protective effect of the mutant variant of the polymorphism. We hypothesize that the -477T and -320G polymorphisms affect the downregulation of MP efflux and may be a predictor of organ complication during P. falciparum malarial infections.

An LXR–NCOA5 gene regulatory complex directs inflammatory crosstalk-dependent repression of macrophage cholesterol efflux

PubMed Central

Gillespie, Mark A; Gold, Elizabeth S; Ramsey, Stephen A; Podolsky, Irina; Aderem, Alan; Ranish, Jeffrey A

2015-01-01

LXR–cofactor complexes activate the gene expression program responsible for cholesterol efflux in macrophages. Inflammation antagonizes this program, resulting in foam cell formation and atherosclerosis; however, the molecular mechanisms underlying this antagonism remain to be fully elucidated. We use promoter enrichment-quantitative mass spectrometry (PE-QMS) to characterize the composition of gene regulatory complexes assembled at the promoter of the lipid transporter Abca1 following downregulation of its expression. We identify a subset of proteins that show LXR ligand- and binding-dependent association with the Abca1 promoter and demonstrate they differentially control Abca1 expression. We determine that NCOA5 is linked to inflammatory Toll-like receptor (TLR) signaling and establish that NCOA5 functions as an LXR corepressor to attenuate Abca1 expression. Importantly, TLR3–LXR signal crosstalk promotes recruitment of NCOA5 to the Abca1 promoter together with loss of RNA polymerase II and reduced cholesterol efflux. Together, these data significantly expand our knowledge of regulatory inputs impinging on the Abca1 promoter and indicate a central role for NCOA5 in mediating crosstalk between pro-inflammatory and anti-inflammatory pathways that results in repression of macrophage cholesterol efflux. PMID:25755249

Association of Circulating C1q/TNF-Related Protein 1 Levels with Coronary Artery Disease in Men

PubMed Central

Yuasa, Daisuke; Ohashi, Koji; Shibata, Rei; Takeshita, Kyosuke; Kikuchi, Ryosuke; Takahashi, Ryotaro; Kataoka, Yoshiyuki; Miyabe, Megumi; Joki, Yusuke; Kambara, Takahiro; Uemura, Yusuke; Matsuo, Kazuhiro; Hayakawa, Satoko; Hiramatsu-Ito, Mizuho; Ito, Masanori; Ikeda, Nobuo; Murohara, Toyoaki; Ouchi, Noriyuki

2014-01-01

Objective Obesity is a major risk factor for cardiovascular disease. Recent evidence demonstrates that dysregulation of fat-derived hormones, also known as adipokines, is linked with the pathogenesis of obesity-related disorders including coronary artery disease (CAD). Here, we investigated whether circulating level of an adipokine C1q/TNF-related protein (CTRP) 1 is associated with the prevalence of CAD. Methods and Results Consecutive 76 male CAD patients were enrolled from inpatients that underwent coronary angiography. Sixty four healthy male subjects served as controls. Plasma CTRP1 concentration was determined by enzyme-linked immunosorbent assay. CTRP1 levels were correlated positively with systolic blood pressure (BP) and triglyceride levels, and negatively with HDL cholesterol levels in all subjects. Plasma levels of CTRP1 were significantly higher in CAD patients than in control subjects (CAD: 443.3±18.6 ng/ml, control: 307.8±21.5 ng/ml, p<0.001). Multiple logistic regression analysis with body mass index, systolic BP, glucose, total cholesterol, HDL cholesterol, triglyceride, adiponectin and CTRP1 revealed that CTRP1 levels, together with systolic BP and HDL cholesterol, correlated with CAD. Conclusions Our data indicate the close association of high CTRP1 levels with CAD prevalence, suggesting that CTRP1 represents a novel biomarker for CAD. PMID:24945145

[Effect of ferulic acid on cholesterol efflux in macrophage foam cell formation and potential mechanism].

PubMed

Chen, Fu-xin; Wang, Lian-kai

2015-02-01

The formation of macrophage-derived foam cells is a typical feature of atherosclerosis (AS). Reverse cholesterol efflux (RCT) is one of important factors for the formation of macrophage foam cells. In this study, macrophage form cells were induced by oxidized low density lipoprotein (ox-LDL) and then treated with different concentrations of ferulic acid, so as to observe the effect of ferulic acid on the intracellular lipid metabolism in the ox-LDL-induced macrophage foam cell formation, the cholesterol efflux and the mRNA expression and protein levels of ATP binding cassette transporter A1 (ABCA1) and ATP binding cassette transporter G1 (ABCG1) that mediate cholesterol efflux, and discuss the potential mechanism of ferulic acid in resisting AS. According to the findings, compared with the control group, the ox-LDL-treated group showed significant increase in intracellular lipid content, especially for the cholesterol content; whereas the intracellular lipid accumulation markedly decreased, after the treatment with ferulic acid. The data also demonstrated that the mRNA and protein expressions of ABCA1 and ABCG1 significantly increased after macrophage foam cells were treated with different concentrations of ferulic acid. In summary, ferulic acid may show the anti-atherosclerosis effect by increasing the surface ABCA1 and ABCG1 expressions of macrophage form cells and promoting cholesterol efflux.

Levels of metacaspase1 and chaperones related to protein quality control in alcoholic and nonalcoholic steatohepatitis.

PubMed

Mendoza, Alejandro S; Dorce, Jacques; Peng, Yue; French, Barbara A; Tillman, Brittany; Li, Jun; French, Samuel W

2015-02-01

Efficient management of misfolded or aggregated proteins in ASH and NASH is crucial for continued hepatic viability. Cellular protein quality control systems play an important role in the pathogenesis and progression of ASH and NASH. In a recent study, elevated Mca1 expression counteracted aggregation and accumulation of misfolded proteins and extended the life span of the yeast Saccharomyces cerevisiae (Hill et al, 2014). Mca1 may also associate with Ssa1 and Hsp104 in disaggregation and fragmentation of aggregated proteins and their subsequent degradation through the ER-associated degradation (ERAD) pathway. If degradation is not available, protection of the cellular environment from a misfolded protein is accomplished by its sequestration into two distinct inclusion bodies (Kaganovich et al., 2008) called the JUNQ (JUxta Nuclear Quality control compartment) and the IPOD (Insoluble Protein Deposit). Mca1, Hsp104, Hsp40, Ydj1, Ssa1, VCP/p97, and p62 all play important roles in protein quality control systems. This study aims to measure the expression of Mca1 and related chaperones involved in protein quality control in alcoholic steatohepatitis (ASH), and nonalcoholic steatohepatitis (NASH) compared with normal control liver biopsies. Mca1, Hsp104, Hsp40, Ydj1, Ssa1, VCP/p97, and p62 expressions were measured in three to six formalin-fixed paraffin embedded ASH and NASH liver biopsies and control normal liver specimens by immunofluorescence staining and quantified by immunofluorescence intensity. Mca1, Hsp104, Ydj1 and p62 were significantly upregulated compared to control (p<0.05) in ASH specimens. Hsp40 and VCP/p97 were also uptrending in ASH. In NASH, the only significant difference was the increased expression of Hsp104 compared to control (p<0.05). Ssa1 levels were uptrending in both ASH and NASH specimens. The upregulation of Mca1, Hsp104, Ydj1 and p62 in ASH may be elicited as a response to the chronic exposure of the hepatocytes to the toxicity of alcohol

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

Xu, Xiaolin; Li, Qian; Pang, Liewen

Highlights: •Arctigenin enhanced cholesterol efflux in oxLDL-loaded THP-1 macrophages. •The expression of ABCA1, ABCG1 and apoE was upregulated in arctigenin-treated cells. •Arctigenin promoted the expression of PPAR-γ and LXR-α. •Inhibition of PPAR-γ or LXR-α reversed arctigenin-mediated biological effects. •Arctigenin promotes cholesterol efflux via activation of PPAR-γ/LXR-α/ABCA1 pathway. -- Abstract: Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-densitymore » lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α.« less

Altered surfactant homeostasis and recurrent respiratory failure secondary to TTF-1 nuclear targeting defect.

PubMed

Peca, Donatella; Petrini, Stefania; Tzialla, Chryssoula; Boldrini, Renata; Morini, Francesco; Stronati, Mauro; Carnielli, Virgilio P; Cogo, Paola E; Danhaive, Olivier

2011-08-25

Mutations of genes affecting surfactant homeostasis, such as SFTPB, SFTPC and ABCA3, lead to diffuse lung disease in neonates and children. Haploinsufficiency of NKX2.1, the gene encoding the thyroid transcription factor-1 (TTF-1)--critical for lung, thyroid and central nervous system morphogenesis and function--causes a rare form of progressive respiratory failure designated brain-lung-thyroid syndrome. Molecular mechanisms involved in this syndrome are heterogeneous and poorly explored. We report a novel TTF-1 molecular defect causing recurrent respiratory failure episodes in an infant. The subject was an infant with severe neonatal respiratory distress syndrome followed by recurrent respiratory failure episodes, hypopituitarism and neurological abnormalities. Lung histology and ultrastructure were assessed by surgical biopsy. Surfactant-related genes were studied by direct genomic DNA sequencing and array chromatine genomic hybridization (aCGH). Surfactant protein expression in lung tissue was analyzed by confocal immunofluorescence microscopy. For kinetics studies, surfactant protein B and disaturated phosphatidylcholine (DSPC) were isolated from serial tracheal aspirates after intravenous administration of stable isotope-labeled (2)H(2)O and (13)C-leucine; fractional synthetic rate was derived from gas chromatography/mass spectrometry (2)H and (13)C enrichment curves. Six intubated infants with no primary lung disease were used as controls. Lung biopsy showed desquamative interstitial pneumonitis and lamellar body abnormalities suggestive of genetic surfactant deficiency. Genetic studies identified a heterozygous ABCA3 mutation, L941P, previously unreported. No SFTPB, SFTPC or NKX2.1 mutations or deletions were found. However, immunofluorescence studies showed TTF-1 prevalently expressed in type II cell cytoplasm instead of nucleus, indicating defective nuclear targeting. This pattern has not been reported in human and was not found in two healthy controls and

Altered surfactant homeostasis and recurrent respiratory failure secondary to TTF-1 nuclear targeting defect

PubMed Central

2011-01-01

Background Mutations of genes affecting surfactant homeostasis, such as SFTPB, SFTPC and ABCA3, lead to diffuse lung disease in neonates and children. Haploinsufficiency of NKX2.1, the gene encoding the thyroid transcription factor-1 (TTF-1) - critical for lung, thyroid and central nervous system morphogenesis and function - causes a rare form of progressive respiratory failure designated brain-lung-thyroid syndrome. Molecular mechanisms involved in this syndrome are heterogeneous and poorly explored. We report a novel TTF-1 molecular defect causing recurrent respiratory failure episodes in an infant. Methods The subject was an infant with severe neonatal respiratory distress syndrome followed by recurrent respiratory failure episodes, hypopituitarism and neurological abnormalities. Lung histology and ultrastructure were assessed by surgical biopsy. Surfactant-related genes were studied by direct genomic DNA sequencing and array chromatine genomic hybridization (aCGH). Surfactant protein expression in lung tissue was analyzed by confocal immunofluorescence microscopy. For kinetics studies, surfactant protein B and disaturated phosphatidylcholine (DSPC) were isolated from serial tracheal aspirates after intravenous administration of stable isotope-labeled 2H2O and 13C-leucine; fractional synthetic rate was derived from gas chromatography/mass spectrometry 2H and 13C enrichment curves. Six intubated infants with no primary lung disease were used as controls. Results Lung biopsy showed desquamative interstitial pneumonitis and lamellar body abnormalities suggestive of genetic surfactant deficiency. Genetic studies identified a heterozygous ABCA3 mutation, L941P, previously unreported. No SFTPB, SFTPC or NKX2.1 mutations or deletions were found. However, immunofluorescence studies showed TTF-1 prevalently expressed in type II cell cytoplasm instead of nucleus, indicating defective nuclear targeting. This pattern has not been reported in human and was not found in two

Bimodal regulation of p21waf1 protein as function of DNA damage levels

PubMed Central

Buscemi, G; Ricci, C; Zannini, L; Fontanella, E; Plevani, P; Delia, D

2014-01-01

Human p21Waf1 protein is well known for being transcriptionally induced by p53 and activating the cell cycle checkpoint arrest in response to DNA breaks. Here we report that p21Waf1 protein undergoes a bimodal regulation, being upregulated in response to low doses of DNA damage but rapidly and transiently degraded in response to high doses of DNA lesions. Responsible for this degradation is the checkpoint kinase Chk1, which phosphorylates p21Waf1 on T145 and S146 residues and induces its proteasome-dependent proteolysis. The initial p21Waf1 degradation is then counteracted by the ATM-Chk2 pathway, which promotes the p53-dependent accumulation of p21Waf1 at any dose of damage. We also found that p21Waf1 ablation favors the activation of an apoptotic program to eliminate otherwise irreparable cells. These findings support a model in which in human cells a balance between ATM-Chk2-p53 and the ATR-Chk1 pathways modulates p21Waf1 protein levels in relation to cytostatic and cytotoxic doses of DNA damage. PMID:25486478

The protein level of hypoxia-inducible factor-1alpha is increased in the plateau pika (Ochotona curzoniae) inhabiting high altitudes.

PubMed

Li, Hong-Ge; Ren, Yong-Ming; Guo, Song-Chang; Cheng, Long; Wang, De-Peng; Yang, Jie; Chang, Zhi-Jie; Zhao, Xin-Quan

2009-02-01

The plateau pika (Ochotona curzoniae) is a high hypoxia-tolerant species living only at 3,000-5,000 m above sea-level on the Qinghai-Tibetan plateau. Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor that regulates a variety of cellular and systemic adaptations to hypoxia. To investigate how the plateau pika adapts to a high-altitude hypoxic environment at the molecular level, we examined the expression pattern of the HIF-1alpha protein in the pika by Western blot and immunohistochemical analysis. We found that HIF-1alpha protein is expressed at a significantly high level in the pika, which is higher in most tissues (particularly in the lung, liver, spleen and kidney) of the plateau pika than that of mice living at sea-level. Importantly, we found that the protein levels of HIF-1alpha in the lung, liver, spleen and kidney of the pika were increased with increased habitat altitudes. We observed that the plateau pika HIF-1alpha localized to the nucleus of cells by an immunostaining analysis, and enhanced HRE-driven gene expression by luciferase reporter assays. Our study suggests that the HIF-1alpha protein levels are related to the adaptation of the plateau pika to the high-altitude hypoxic environment.

AIBP reduces atherosclerosis by promoting reverse cholesterol transport and ameliorating inflammation in apoE-/- mice.

PubMed

Zhang, Min; Zhao, Guo-Jun; Yao, Feng; Xia, Xiao-Dan; Gong, Duo; Zhao, Zhen-Wang; Chen, Ling-Yan; Zheng, Xi-Long; Tang, Xiao-Er; Tang, Chao-Ke

2018-06-01

ApoA-1 binding protein (AIBP) is a secreted protein that interacts with apoA-I and accelerates cholesterol efflux from cells. We have recently reported that AIBP promotes apoA-1 binding to ABCA1 in the macrophage cell membrane, partially through 115-123 amino acids. However, the effects of AIBP on the development of atherosclerosis in vivo remain unknown. ApoE -/- mice with established atherosclerotic plaques were infected with rAAV-AIBP or rAAV-AIBP(Δ115-123), respectively. AIBP-treated mice showed reduction of atherosclerotic lesion formation, increase in circulating HDL levels and enhancement of reverse cholesterol transport to the plasma, liver, and feces. AIBP increased ABCA1 protein levels in aorta and peritoneal macrophages. Furthermore, AIBP could diminish atherosclerotic plaque macrophage content and the expression of chemotaxis-related factors. In addition, AIBP prevented macrophage inflammation by inactivating NF-κB and promoted the expression of M2 markers like Mrc-1 and Arg-1. However, lack of 115-123 amino acids of AIBP(Δ115-123) had no such preventive effects on the progression of atherosclerosis. Our observations demonstrate that AIBP inhibits atherosclerosis progression and suggest that it may be an effective target for prevention of atherosclerosis. Copyright © 2018 Elsevier B.V. All rights reserved.

Late-onset Stargardt disease is associated with missense mutations that map outside known functional regions of ABCR (ABCA4).

PubMed

Yatsenko, A N; Shroyer, N F; Lewis, R A; Lupski, J R

2001-04-01

Based on recent studies of the photoreceptor-specific ABC transporter gene ABCR (ABCA4) in Stargardt disease (STGD1) and other retinal dystrophies, we and others have developed a model in which the severity of retinal disease correlates inversely with residual ABCR activity. This model predicts that patients with late-onset STGDI may retain partial ABCR activity attributable to mild missense alleles. To test this hypothesis, we used late-onset STGDI patients (onset: > or =35 years) to provide an in vivo functional analysis of various combinations of mutant alleles. We sequenced directly the entire coding region of ABCR and detected mutations in 33/50 (66%) disease chromosomes, but surprisingly, 11/33 (33%) were truncating alleles. Importantly, all 22 missense mutations were located outside the known functional domains of ABCR (ATP-binding or transmembrane), whereas in our general cohort of STGDI subjects, alterations occurred with equal frequency across the entire protein. We suggest that these missense mutations in regions of unknown function are milder alleles and more susceptible to modifier effects. Thus, we have corroborated a prediction from the model of ABCR pathogenicity that (1) one mutant ABCR allele is always missense in late-onset STGD1 patients, and (2) the age-of-onset is correlated with the amount of ABCR activity of this allele. In addition, we report three new pseudodominant families that now comprise eight of 178 outbred STGD1 families and suggest a carrier frequency of STGD1-associated ABCR mutations of about 4.5% (approximately 1/22).

Melanocortin 1 Receptor Signaling Regulates Cholesterol Transport in Macrophages.

PubMed

Rinne, Petteri; Rami, Martina; Nuutinen, Salla; Santovito, Donato; van der Vorst, Emiel P C; Guillamat-Prats, Raquel; Lyytikäinen, Leo-Pekka; Raitoharju, Emma; Oksala, Niku; Ring, Larisa; Cai, Minying; Hruby, Victor J; Lehtimäki, Terho; Weber, Christian; Steffens, Sabine

2017-07-04

The melanocortin 1 receptor (MC1-R) is expressed by monocytes and macrophages, where it exerts anti-inflammatory actions on stimulation with its natural ligand α-melanocyte-stimulating hormone. The present study was designed to investigate the specific role of MC1-R in the context of atherosclerosis and possible regulatory pathways of MC1-R beyond anti-inflammation. Human and mouse atherosclerotic samples and primary mouse macrophages were used to study the regulatory functions of MC1-R. The impact of pharmacological MC1-R activation on atherosclerosis was assessed in apolipoprotein E-deficient mice. Characterization of human and mouse atherosclerotic plaques revealed that MC1-R expression localizes in lesional macrophages and is significantly associated with the ATP-binding cassette transporters ABCA1 and ABCG1, which are responsible for initiating reverse cholesterol transport. Using bone marrow-derived macrophages, we observed that α-melanocyte-stimulating hormone and selective MC1-R agonists similarly promoted cholesterol efflux, which is a counterregulatory mechanism against foam cell formation. Mechanistically, MC1-R activation upregulated the levels of ABCA1 and ABCG1. These effects were accompanied by a reduction in cell surface CD36 expression and in cholesterol uptake, further protecting macrophages from excessive lipid accumulation. Conversely, macrophages deficient in functional MC1-R displayed a phenotype with impaired efflux and enhanced uptake of cholesterol. Pharmacological targeting of MC1-R in atherosclerotic apolipoprotein E-deficient mice reduced plasma cholesterol levels and aortic CD36 expression and increased plaque ABCG1 expression and signs of plaque stability. Our findings identify a novel role for MC1-R in macrophage cholesterol transport. Activation of MC1-R confers protection against macrophage foam cell formation through a dual mechanism: It prevents cholesterol uptake while concomitantly promoting ABCA1- and ABCG1-mediated reverse

ATP-binding cassette transporter 1 participates in LDL oxidation by artery wall cells.

PubMed

Reddy, Srinivasa T; Hama, Susan; Ng, Carey; Grijalva, Victor; Navab, Mohamad; Fogelman, Alan M

2002-11-01

We have previously reported that products of the lipoxygenase pathway, hydroperoxyoctadecadienoic acid and hydroperoxyeicosatetraenoic acid, as well as cholesterol linoleate hydroperoxides, collectively termed seeding molecules, are removed by apolipoprotein A-I (apoA-I) from the artery wall cells and render low density lipoprotein (LDL) resistant to oxidation by human artery wall cells. The mechanisms by which oxidized lipids are transported and/or transferred to lipoproteins and the pathways by which apoA-I facilitates their removal remain unclear. ATP-binding cassette transporter 1 (ABCA1) is known to facilitate the release of cellular phospholipids and cholesterol from the plasma membrane to apoA-I and high density lipoprotein. Therefore, we evaluated whether ABCA1 participates in LDL oxidation. In this report, we show that (1) chemical inhibitors of ABCA1 function, glyburide and DIDS, block artery wall cell-mediated oxidative modification of LDL, (2) inhibition of ABCA1 with the use of antisense (but not sense) oligonucleotides prevents LDL-induced lipid hydroperoxide formation and LDL-induced monocyte chemotactic activity by the artery wall cells, and (3) oxysterols that induce ABCA1 expression, such as 22(R)hydroxycholesterol, enhance cell-mediated LDL oxidation. Furthermore, we also show that 22(R)hydroxycholesterol induces the production of reactive oxygen species in the artery wall cells, which can be removed by incubating the artery wall cells with apoA-I. Our data suggest that ABCA1 plays an important role in artery wall cell-mediated modification/oxidation of LDL by modulating the release of reactive oxygen species from artery wall cells that are necessary for LDL oxidation.

Andrographolide Inhibits Oxidized LDL-Induced Cholesterol Accumulation and Foam Cell Formation in Macrophages.

PubMed

Lin, Hung-Chih; Lii, Chong-Kuei; Chen, Hui-Chun; Lin, Ai-Hsuan; Yang, Ya-Chen; Chen, Haw-Wen

2018-01-01

oxLDL is involved in the pathogenesis of atherosclerotic lesions through cholesterol accumulation in macrophage foam cells. Andrographolide, the bioactive component of Andrographis paniculata, possesses several biological activities such as anti-inflammatory, anti-oxidant, and anticancer functions. Scavenger receptors (SRs), including class A SR (SR-A) and CD36, are responsible for the internalization of oxLDL. In contrast, receptors for reverse cholesterol transport, including ABCA1 and ABCG1, mediate the efflux of cholesterol from macrophage foam cells. Transcription factor liver X receptor [Formula: see text] (LXR[Formula: see text] plays a key role in lipid metabolism and inflammation as well as in the regulation of ABCA1 and ABCG1 expression. Because of the contribution of inflammation to macrophage foam cell formation and the potent anti-inflammatory activity of andrographolide, we hypothesized that andrographolide might inhibit oxLDL-induced macrophage foam cell formation. The results showed that andrographolide reduced oxLDL-induced lipid accumulation in macrophage foam cells. Andrographolide decreased the mRNA and protein expression of CD36 by inducing the degradation of CD36 mRNA; however, andrographolide had no effect on SR-A expression. In contrast, andrographolide increased the mRNA and protein expression of ABCA1 and ABCG1, which were dependent on LXR[Formula: see text]. Andrographolide enhanced LXR[Formula: see text] nuclear translocation and DNA binding activity. Treatment with the LXR[Formula: see text] antagonist GGPP and transfection with LXR[Formula: see text] siRNA reversed the ability of andrographolide to stimulate ABCA1 and ABCG1 protein expression. In conclusion, inhibition of CD36-mediated oxLDL uptake and induction of ABCA1- and ABCG1-dependent cholesterol efflux are two working mechanisms by which andrographolide inhibits macrophage foam cell formation, which suggests that andrographolide could be a potential candidate to prevent

Sequence specific peptidomimetic molecules inhibitors of a protein-protein interaction at the helix 1 level of c-Myc.

PubMed

Nieddu, Erika; Melchiori, A; Pescarolo, M P; Bagnasco, L; Biasotti, B; Licheri, B; Malacarne, D; Tortolina, L; Castagnino, N; Pasa, S; Cimoli, G; Avignolo, C; Ponassi, R; Balbi, C; Patrone, E; D'arrigo, C; Barboro, P; Vasile, F; Orecchia, P; Carnemolla, B; Damonte, G; Millo, E; Palomba, D; Fassina, G; Mazzei, M; Parodi, S

2005-04-01

Our work is focused in the broad area of strategies and efforts to inhibit protein-protein interactions. The possible strategies in this field are definitely much more varied than in the case of ATP-pocket inhibitors. In our previous work (10), we reported that a retro-inverso (RI) form of Helix1 (H1) of c-Myc, linked to an RI-internalization sequence arising from the third alpha-helix of Antennapedia (Int) was endowed with an antiproliferative and proapoptotic activity toward the cancer cell lines MCF-7 and HCT-116. The activity apparently was dependent upon the presence of the Myc motif. In this work, by ala-scan mapping of the H1 portion of our molecules with D-aa, we found two amino acids necessary for antiproliferative activity: D-Lys in 4 and D-Arg in 5 (numbers refer to L-forms). In the natural hetero-dimer, these two side chains project to the outside of the four alpha-helix bundle. Moreover, we were able to obtain three peptides more active than the original lead. They strongly reduced cell proliferation and survival (RI-Int-VV-H1-E2A,S6A,F8A; RI-Int-VV-H1-S6A,F8A,R11A; RI-Int-VV-H1-S6A,F8A,Q13A): after 8 days at 10 muM total cell number was approximately 1% of the number of cells initially seeded. In these more potent molecules, the ablated side chains project to the inside in the corresponding natural four alpha-helix bundle. In the present work, we also investigated the behavior of our molecules at the biochemical level. Using both a circular dichroism (CD) and a fluorescence anisotropy approach, we noted that side chains projecting at the interior of the four alpha-helix bundle are needed for inducing the partial unfolding of Myc-H2, without an opening of the leucine zipper. Side chains projecting at the outside are not required for this biochemical effect. However, antiproliferative activity had the opposite requirements: side chains projecting at the outside of the bundle were essential, and, on the contrary, ablation of one side chain at a time

Low levels of aflatoxin B1, ricin and milk enhance recombinant protein production in mammalian cells

USDA-ARS?s Scientific Manuscript database

Changing the optimal tissue culture medium by adding low levels of environmental stress such as 1 µM of the fungal toxin aflatoxin B1 (AFB1), 1 ng of the castor bean protein toxin ricin in transduced mammalian cells or 1% reconstituted milk enhances transcription and increases production of the foll...

Variants in the ATP-Binding Cassette Transporter (ABCA7), Apolipoprotein E ε4, and the Risk of Late-Onset Alzheimer Disease in African Americans

PubMed Central

Reitz, Christiane; Jun, Gyungah; Naj, Adam; Rajbhandary, Ruchita; Vardarajan, Badri Narayan; Wang, Li-San; Valladares, Otto; Lin, Chiao-Feng; Larson, Eric B.; Graff-Radford, Neill R.; Evans, Denis; De Jager, Philip L.; Crane, Paul K.; Buxbaum, Joseph D.; Murrell, Jill R.; Raj, Towfique; Ertekin-Taner, Nilufer; Logue, Mark; Baldwin, Clinton T.; Green, Robert C.; Barnes, Lisa L.; Cantwell, Laura B.; Fallin, M. Daniele; Go, Rodney C. P.; Griffith, Patrick; Obisesan, Thomas O.; Manly, Jennifer J.; Lunetta, Kathryn L.; Kamboh, M. Ilyas; Lopez, Oscar L.; Bennett, David A.; Hendrie, Hugh; Hall, Kathleen S.; Goate, Alison M.; Byrd, Goldie S.; Kukull, Walter A.; Foroud, Tatiana M.; Haines, Jonathan L.; Farrer, Lindsay A.; Pericak-Vance, Margaret A.; Schellenberg, Gerard D.; Mayeux, Richard

2013-01-01

Importance Genetic variants associated with susceptibility to late-onset Alzheimer disease are known for individuals of European ancestry, but whether the same or different variants account for the genetic risk of Alzheimer disease in African American individuals is unknown. Identification of disease-associated variants helps identify targets for genetic testing, prevention, and treatment. Objective To identify genetic loci associated with late-onset Alzheimer disease in African Americans. Design, Setting, and Participants The Alzheimer Disease Genetics Consortium (ADGC) assembled multiple data sets representing a total of 5896 African Americans (1968 case participants, 3928 control participants) 60 years or older that were collected between 1989 and 2011 at multiple sites. The association of Alzheimer disease with genotyped and imputed single-nucleotide polymorphisms (SNPs) was assessed in case-control and in family-based data sets. Results from individual data sets were combined to perform an inverse variance–weighted meta-analysis, first with genome-wide analyses and subsequently with gene-based tests for previously reported loci. Main Outcomes and Measures Presence of Alzheimer disease according to standardized criteria. Results Genome-wide significance in fully adjusted models (sex, age, APOE genotype, population stratification) was observed for a SNP in ABCA7 (rs115550680, allele = G; frequency, 0.09 cases and 0.06 controls; odds ratio [OR], 1.79 [95% CI, 1.47-2.12]; P = 2.2 × 10–9), which is in linkage disequilibrium with SNPs previously associated with Alzheimer disease in Europeans (0.8ABCA7 was comparable with that of the APOE ε4–determining SNP rs429358 (allele = C; frequency, 0.30 cases and 0.18 controls; OR, 2.31 [95% CI, 2.19-2.42]; P = 5.5 × 10–47). Several loci previously associated with Alzheimer disease but not reaching significance in genome-wide analyses were replicated in gene-based analyses

Variants in the ATP-binding cassette transporter (ABCA7), apolipoprotein E ϵ4,and the risk of late-onset Alzheimer disease in African Americans.

PubMed

Reitz, Christiane; Jun, Gyungah; Naj, Adam; Rajbhandary, Ruchita; Vardarajan, Badri Narayan; Wang, Li-San; Valladares, Otto; Lin, Chiao-Feng; Larson, Eric B; Graff-Radford, Neill R; Evans, Denis; De Jager, Philip L; Crane, Paul K; Buxbaum, Joseph D; Murrell, Jill R; Raj, Towfique; Ertekin-Taner, Nilufer; Logue, Mark; Baldwin, Clinton T; Green, Robert C; Barnes, Lisa L; Cantwell, Laura B; Fallin, M Daniele; Go, Rodney C P; Griffith, Patrick; Obisesan, Thomas O; Manly, Jennifer J; Lunetta, Kathryn L; Kamboh, M Ilyas; Lopez, Oscar L; Bennett, David A; Hendrie, Hugh; Hall, Kathleen S; Goate, Alison M; Byrd, Goldie S; Kukull, Walter A; Foroud, Tatiana M; Haines, Jonathan L; Farrer, Lindsay A; Pericak-Vance, Margaret A; Schellenberg, Gerard D; Mayeux, Richard

2013-04-10

Genetic variants associated with susceptibility to late-onset Alzheimer disease are known for individuals of European ancestry, but whether the same or different variants account for the genetic risk of Alzheimer disease in African American individuals is unknown. Identification of disease-associated variants helps identify targets for genetic testing, prevention, and treatment. To identify genetic loci associated with late-onset Alzheimer disease in African Americans. The Alzheimer Disease Genetics Consortium (ADGC) assembled multiple data sets representing a total of 5896 African Americans (1968 case participants, 3928 control participants) 60 years or older that were collected between 1989 and 2011 at multiple sites. The association of Alzheimer disease with genotyped and imputed single-nucleotide polymorphisms (SNPs) was assessed in case-control and in family-based data sets. Results from individual data sets were combined to perform an inverse variance-weighted meta-analysis, first with genome-wide analyses and subsequently with gene-based tests for previously reported loci. Presence of Alzheimer disease according to standardized criteria. Genome-wide significance in fully adjusted models (sex, age, APOE genotype, population stratification) was observed for a SNP in ABCA7 (rs115550680, allele = G; frequency, 0.09 cases and 0.06 controls; odds ratio [OR], 1.79 [95% CI, 1.47-2.12]; P = 2.2 × 10(-9)), which is in linkage disequilibrium with SNPs previously associated with Alzheimer disease in Europeans (0.8 < D' < 0.9). The effect size for the SNP in ABCA7 was comparable with that of the APOE ϵ4-determining SNP rs429358 (allele = C; frequency, 0.30 cases and 0.18 controls; OR, 2.31 [95% CI, 2.19-2.42]; P = 5.5 × 10(-47)). Several loci previously associated with Alzheimer disease but not reaching significance in genome-wide analyses were replicated in gene-based analyses accounting for linkage disequilibrium between markers and correcting for number of tests

Engineered mutations in fibrillin-1 leading to Marfan syndrome act at the protein, cellular and organismal levels.

PubMed

Zeyer, Karina A; Reinhardt, Dieter P

2015-01-01

Fibrillins are the major components of microfibrils in the extracellular matrix of elastic and non-elastic tissues. They are multi-domain proteins, containing primarily calcium binding epidermal growth factor-like (cbEGF) domains and 8-cysteine/transforming growth factor-beta binding protein-like (TB) domains. Mutations in the fibrillin-1 gene give rise to Marfan syndrome, a connective tissue disorder with clinical complications in the cardiovascular, skeletal, ocular and other organ systems. Here, we review the consequences of engineered Marfan syndrome mutations in fibrillin-1 at the protein, cellular and organismal levels. Representative point mutations associated with Marfan syndrome in affected individuals have been introduced and analyzed in recombinant fibrillin-1 fragments. Those mutations affect fibrillin-1 on a structural and functional level. Mutations which impair folding of cbEGF domains can affect protein trafficking. Protein folding disrupted by some mutations can lead to defective secretion in mutant fibrillin-1 fragments, whereas fragments with other Marfan mutations are secreted normally. Many Marfan mutations render fibrillin-1 more susceptible to proteolysis. There is also evidence that some mutations affect heparin binding. Few mutations have been further analyzed in mouse models. An extensively studied mouse model of Marfan syndrome expresses mouse fibrillin-1 with a missense mutation (p.C1039G). The mice display similar characteristics to human patients with Marfan syndrome. Overall, the analyses of engineered mutations leading to Marfan syndrome provide important insights into the pathogenic molecular mechanisms exerted by mutated fibrillin-1. Copyright © 2015 Elsevier B.V. All rights reserved.

Plasma levels of soluble interleukin 1 receptor accessory protein are reduced in obesity.

PubMed

Bozaoglu, Kiymet; Attard, Chantal; Kulkarni, Hemant; Cummings, Nik; Diego, Vincent P; Carless, Melanie A; Shields, Katherine A; Johnson, Matthew P; Kowlessur, Sudhir; Dyer, Thomas D; Comuzzie, Anthony G; Almasy, Laura; Zimmet, Paul; Moses, Eric K; Göring, Harald H H; Curran, Joanne E; Blangero, John; Jowett, Jeremy B M

2014-09-01

Adipokines actuate chronic, low-grade inflammation through a complex network of immune markers, but the current understanding of these networks is incomplete. The soluble isoform of the IL-1 receptor accessory protein (sIL1RAP) occupies an important position in the inflammatory pathways involved in obesity. The pathogenetic and clinical influences of sIL1RAP are unknown. The objective of the study was to elucidate whether plasma levels of sIL1RAP are reduced in obesity, using affluent clinical, biochemical, and genetic data from two diverse cohorts. The study was conducted in two cohorts: the San Antonio Family Heart Study (n = 1397 individuals from 42 families) and South Asians living in Mauritius, n = 230). Plasma sIL1RAP levels were measured using an ELISA. The genetic basis of sIL1RAP levels were investigated using both a large-scale gene expression profiling study and a genome-wide association study. A significant decrease in plasma sIL1RAP levels were observed in obese subjects, even after adjustment for age and sex. The sIL1RAP levels demonstrated a strong inverse association with obesity measures in both populations. All associations were more significant in females. Plasma sIL1RAP levels were significantly heritable, correlated with IL1RAP transcript levels (NM_134470), showed evidence for shared genetic influences with obesity measures and were significantly associated with the rs2885373 single-nucleotide polymorphism (P = 6.7 × 10(-23)) within the IL1RAP gene. Plasma sIL1RAP levels are reduced in obesity and can potentially act as biomarkers of obesity. Mechanistic studies are required to understand the exact contribution of sIL1RAP to the pathogenesis of obesity.

Plasma Levels of Soluble Interleukin 1 Receptor Accessory Protein Are Reduced in Obesity

PubMed Central

Attard, Chantal; Kulkarni, Hemant; Cummings, Nik; Diego, Vincent P.; Carless, Melanie A.; Shields, Katherine A.; Johnson, Matthew P.; Kowlessur, Sudhir; Dyer, Thomas D.; Comuzzie, Anthony G.; Almasy, Laura; Zimmet, Paul; Moses, Eric K.; Göring, Harald H. H.; Curran, Joanne E.; Blangero, John; Jowett, Jeremy B. M.

2014-01-01

Context: Adipokines actuate chronic, low-grade inflammation through a complex network of immune markers, but the current understanding of these networks is incomplete. The soluble isoform of the IL-1 receptor accessory protein (sIL1RAP) occupies an important position in the inflammatory pathways involved in obesity. The pathogenetic and clinical influences of sIL1RAP are unknown. Objective: The objective of the study was to elucidate whether plasma levels of sIL1RAP are reduced in obesity, using affluent clinical, biochemical, and genetic data from two diverse cohorts. Design, Setting, and Participants: The study was conducted in two cohorts: the San Antonio Family Heart Study (n = 1397 individuals from 42 families) and South Asians living in Mauritius, n = 230). Main Outcome Measures: Plasma sIL1RAP levels were measured using an ELISA. The genetic basis of sIL1RAP levels were investigated using both a large-scale gene expression profiling study and a genome-wide association study. Results: A significant decrease in plasma sIL1RAP levels were observed in obese subjects, even after adjustment for age and sex. The sIL1RAP levels demonstrated a strong inverse association with obesity measures in both populations. All associations were more significant in females. Plasma sIL1RAP levels were significantly heritable, correlated with IL1RAP transcript levels (NM_134470), showed evidence for shared genetic influences with obesity measures and were significantly associated with the rs2885373 single-nucleotide polymorphism (P = 6.7 × 10−23) within the IL1RAP gene. Conclusions: Plasma sIL1RAP levels are reduced in obesity and can potentially act as biomarkers of obesity. Mechanistic studies are required to understand the exact contribution of sIL1RAP to the pathogenesis of obesity. PMID:24915116

Level of supplemental protein does not influence the ruminally undegradable protein value.

PubMed

Legleiter, L R; Mueller, A M; Kerley, M S

2005-04-01

Two experiments were conducted to determine whether elevating the percentage of ruminally undegradable protein (RUP) in the diet would influence the RUP value of the protein feedstuff. A single-effluent, continuous-culture study was designed to test the effect of RUP inclusion rate in the diet on ruminal degradability of the protein. Treatments consisted (DM basis) of a control diet with no supplemental protein, control + 2.5% bloodmeal (BM-L), control + 5% bloodmeal (BM-H), control + 4.45% soybean meal (SBM-L), and control + 8.89% soybean meal (SBM-H). Proteolytic activity and total VFA concentration were not affected (P = 0.73 and P = 0.13) by treatment. Within protein source, dietary RUP value was not affected (P = 0.94) by level of inclusion. When corrected for control diet RUP flow, the RUP value of the blood meal (BM) protein was higher (P = 0.01) than soybean meal (SBM); however, level of supplementation did not affect (P = 0.07) the RUP value of BM or SBM. In Exp. 2, 32 British x Continental crossbred steers (276 +/- 26.3 kg) were fed for 72 d to examine the effects of balancing the AA:energy ratio, using BM as a RUP source, on ADG, G:F, and lean tissue deposition. Diets were formulated to provide increasing levels of arginine, while ruminally degradable protein and energy were held constant. Four dietary treatments provided 0.5, 1, 1.5, and 2x the required amount of arginine, whereas the control diet had no BM included. Daily DMI averaged 7.6 kg/steer and did not differ (P = 0.71) among treatments. Steers gained an average of 1.9 kg/d and average G:F was 0.260, with no differences (P = 0.60 and P = 0.97, respectively) among treatments. There was no difference (P = 0.48) in the change in 12th-rib fat depth during the study; however, change in LM area was affected quadratically as the level of BM increased in the diet, with the greatest increase in LM area occurring in steers fed the 1x and 1.5x required arginine treatments. Balancing the AA:energy ratio did

Levels of the E2 interacting protein TopBP1 modulate papillomavirus maintenance stage replication

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

Kanginakudru, Sriramana, E-mail: skangina@iu.edu; DeSmet, Marsha, E-mail: mdesmet@iupui.edu; Thomas, Yanique, E-mail: ysthomas@umail.iu.edu

2015-04-15

The evolutionarily conserved DNA topoisomerase II beta-binding protein 1 (TopBP1) functions in DNA replication, DNA damage response, and cell survival. We analyzed the role of TopBP1 in human and bovine papillomavirus genome replication. Consistent with prior reports, TopBP1 co-localized in discrete nuclear foci and was in complex with papillomavirus E2 protein. Similar to E2, TopBP1 is recruited to the region of the viral origin of replication during G1/S and early S phase. TopBP1 knockdown increased, while over-expression decreased transient virus replication, without affecting cell cycle. Similarly, using cell lines harboring HPV-16 or HPV-31 genome, TopBP1 knockdown increased while over-expression reducedmore » viral copy number relative to genomic DNA. We propose a model in which TopBP1 serves dual roles in viral replication: it is essential for initiation of replication yet it restricts viral copy number. - Highlights: • Protein interaction study confirmed In-situ interaction between TopBP1 and E2. • TopBP1 present at papillomavirus ori in G1/S and early S phase of cell cycle. • TopBP1 knockdown increased, over-expression reduced virus replication. • TopBP1 protein level change did not influence cell survival or cell cycle. • TopBP1 displaced from papillomavirus ori after initiation of replication.« less

Chitinase-3-like 1 protein (CHI3L1) locus influences cerebrospinal fluid levels of YKL-40.

PubMed

Deming, Yuetiva; Black, Kathleen; Carrell, David; Cai, Yefei; Del-Aguila, Jorge L; Fernandez, Maria Victoria; Budde, John; Ma, ShengMei; Saef, Benjamin; Howells, Bill; Bertelsen, Sarah; Huang, Kuan-Lin; Sutphen, Courtney L; Tarawneh, Rawan; Fagan, Anne M; Holtzman, David M; Morris, John C; Goate, Alison M; Dougherty, Joseph D; Cruchaga, Carlos

2016-11-10

Alzheimer's disease (AD) pathology appears several years before clinical symptoms, so identifying ways to detect individuals in the preclinical stage is imperative. The cerebrospinal fluid (CSF) Tau/Aβ 42 ratio is currently the best known predictor of AD status and cognitive decline, and the ratio of CSF levels of chitinase-3-like 1 protein (CHI3L1, YKL-40) and amyloid beta (Aβ 42 ) were reported as predictive, but individual variability and group overlap inhibits their utility for individual diagnosis making it necessary to find ways to improve sensitivity of these biomarkers. We used linear regression to identify genetic loci associated with CSF YKL-40 levels in 379 individuals (80 cognitively impaired and 299 cognitively normal) from the Charles F and Joanne Knight Alzheimer's Disease Research Center. We tested correlations between YKL-40 and CSF Tau/Aβ 42 ratio, Aβ 42 , tau, and phosphorylated tau (ptau 181 ). We used studentized residuals from a linear regression model of the log-transformed, standardized protein levels and the additive reference allele counts from the most significant locus to adjust YKL-40 values and tested the differences in correlations with CSF Tau/Aβ 42 ratio, Aβ 42 , tau, and ptau 181 . We found that genetic variants on the CH13L1 locus were significantly associated with CSF YKL-40 levels, but not AD risk, age at onset, or disease progression. The most significant variant is a reported expression quantitative trait locus for CHI3L1, the gene which encodes YKL-40, and explained 12.74 % of the variance in CSF YKL-40 in our study. YKL-40 was positively correlated with ptau 181 (r = 0.521) and the strength of the correlation significantly increased with the addition of genetic information (r = 0.573, p = 0.006). CSF YKL-40 levels are likely a biomarker for AD, but we found no evidence that they are an AD endophenotype. YKL-40 levels are highly regulated by genetic variation, and by including genetic information the

Dietary protein level and performance of growing Baladi kids.

PubMed

Abdelrahman, M M; Aljumaah, R S

2014-01-01

A study was conducted to evaluate the effect of feeding different levels of protein to black Baladi breed kids. Weanling Baladi kids (n=18; 75 to 90 days old) were selected and individually housed at our experimental farm. Kids were divided randomly to one of the three treatments for 12 weeks. The three dietary treatments were: T1: control ration, formulated according to NRC to cover the protein (level 1) and other nutrients requirements. T2: ration formulated to cover only 75% of protein (level 2) recommended by NRC. T3: control diet + 2.4 g undegradable methionine (Smartamine®)/day/kid (level 3). Feed intake, initial and monthly body weights were recorded. Blood samples were collected monthly and analyzed for metabolites and Co, Zn and Cu levels. Decreasing the dietary level of protein (T2) negatively affected (P<0.05) the total live weight gain, average daily gain and feed conversion ratio when compared with the control and T3 groups. Moreover, treatment, time and time × treatment caused a significant change on Co concentration in blood serum with higher value at the end of the experiment. Treatments had a significant effect (P<0.05) on blood serum cholesterol and protein levels. Undegradable methionine supplementation (T3) significantly increased longissimus dorsi weight, fat thickness and omental fat%. In conclusion, feeding Baladi kids below the NRC requirements of protein negatively affect the growth performance and feed efficiency. The recommended protein level by NRC for growing kids cover the requirements of growing black Baladi kids for maximum growth and productivity.

Dietary protein level and performance of growing Baladi kids

PubMed Central

Abdelrahman, M. M.; Aljumaah, R. S.

2014-01-01

A study was conducted to evaluate the effect of feeding different levels of protein to black Baladi breed kids. Weanling Baladi kids (n=18; 75 to 90 days old) were selected and individually housed at our experimental farm. Kids were divided randomly to one of the three treatments for 12 weeks. The three dietary treatments were: T1: control ration, formulated according to NRC to cover the protein (level 1) and other nutrients requirements. T2: ration formulated to cover only 75% of protein (level 2) recommended by NRC. T3: control diet + 2.4 g undegradable methionine (Smartamine®)/day/kid (level 3). Feed intake, initial and monthly body weights were recorded. Blood samples were collected monthly and analyzed for metabolites and Co, Zn and Cu levels. Decreasing the dietary level of protein (T2) negatively affected (P<0.05) the total live weight gain, average daily gain and feed conversion ratio when compared with the control and T3 groups. Moreover, treatment, time and time × treatment caused a significant change on Co concentration in blood serum with higher value at the end of the experiment. Treatments had a significant effect (P<0.05) on blood serum cholesterol and protein levels. Undegradable methionine supplementation (T3) significantly increased longissimus dorsi weight, fat thickness and omental fat%. In conclusion, feeding Baladi kids below the NRC requirements of protein negatively affect the growth performance and feed efficiency. The recommended protein level by NRC for growing kids cover the requirements of growing black Baladi kids for maximum growth and productivity. PMID:27175130

Cardiotonic Steroids Stabilize Regulator of G Protein Signaling 2 Protein Levels

PubMed Central

Sjögren, Benita; Parra, Sergio; Heath, Lauren J.; Atkins, Kevin B.; Xie, Zie-Jian

2012-01-01

Regulator of G protein signaling 2 (RGS2), a Gq-specific GTPase-activating protein, is strongly implicated in cardiovascular function. RGS2(−/−) mice are hypertensive and prone to heart failure, and several rare human mutations that accelerate RGS2 degradation have been identified among patients with hypertension. Therefore, pharmacological up-regulation of RGS2 protein levels might be beneficial. We used a β-galactosidase complementation method to screen several thousand compounds with known pharmacological functions for those that increased RGS2 protein levels. Several cardiotonic steroids (CTSs), including ouabain and digoxin, increased RGS2 but not RGS4 protein levels. CTSs increased RGS2 protein levels through a post-transcriptional mechanism, by slowing protein degradation. RGS2 mRNA levels in primary vascular smooth muscle cells were unaffected by CTS treatment, whereas protein levels were increased 2- to 3-fold. Na+/K+-ATPase was required for the increase in RGS2 protein levels, because the effect was lost in Na+/K+-ATPase-knockdown cells. Furthermore, we demonstrated that CTS-induced increases in RGS2 levels were functional and reduced receptor-stimulated, Gq-dependent, extracellular signal-regulated kinase phosphorylation. Finally, we showed that in vivo treatment with digoxin led to increased RGS2 protein levels in heart and kidney. CTS-induced increases in RGS2 protein levels and function might modify several deleterious mechanisms in hypertension and heart failure. This novel CTS mechanism might contribute to the beneficial actions of low-dose digoxin treatment in heart failure. Our results support the concept of small-molecule modulation of RGS2 protein levels as a new strategy for cardiovascular therapy. PMID:22695717

Cholesterol Accumulation in Dendritic Cells Links the Inflammasome to Acquired Immunity.

PubMed

Westerterp, Marit; Gautier, Emmanuel L; Ganda, Anjali; Molusky, Matthew M; Wang, Wei; Fotakis, Panagiotis; Wang, Nan; Randolph, Gwendalyn J; D'Agati, Vivette D; Yvan-Charvet, Laurent; Tall, Alan R

2017-06-06

Autoimmune diseases such as systemic lupus erythematosus (SLE) are associated with increased cardiovascular disease and reduced plasma high-density lipoprotein (HDL) levels. HDL mediates cholesterol efflux from immune cells via the ATP binding cassette transporters A1 and G1 (ABCA1/G1). The significance of impaired cholesterol efflux pathways in autoimmunity is unknown. We observed that Abca1/g1-deficient mice develop enlarged lymph nodes (LNs) and glomerulonephritis suggestive of SLE. This lupus-like phenotype was recapitulated in mice with knockouts of Abca1/g1 in dendritic cells (DCs), but not in macrophages or T cells. DC-Abca1/g1 deficiency increased LN and splenic CD11b + DCs, which displayed cholesterol accumulation and inflammasome activation, increased cell surface levels of the granulocyte macrophage-colony stimulating factor receptor, and enhanced inflammatory cytokine secretion. Consequently, DC-Abca1/g1 deficiency enhanced T cell activation and T h 1 and T h 17 cell polarization. Nlrp3 inflammasome deficiency diminished the enlarged LNs and enhanced T h 1 cell polarization. These findings identify an essential role of DC cholesterol efflux pathways in maintaining immune tolerance. Copyright © 2017 Elsevier Inc. All rights reserved.

Spectrum of ABCA4 (ABCR) gene mutations in Spanish patients with autosomal recessive macular dystrophies.

PubMed

Paloma, E; Martínez-Mir, A; Vilageliu, L; Gonzàlez-Duarte, R; Balcells, S

2001-06-01

The ABCA4 gene has been involved in several forms of inherited macular dystrophy. In order to further characterize the complex genotype-phenotype relationships involving this gene, we have performed a mutation analysis of ABCA4 in 14 Spanish patients comprising eight STGD (Stargardt), four FFM (fundus flavimaculatus), and two CRD (Cone-rod dystrophy) patients. SSCP (single-strand conformation polymorphism) analysis and DNA sequencing of the coding and 5' upstream regions of this gene allowed the identification of 16 putatively pathogenic alterations, nine of which are novel. Most of these were missense changes, and no patient was found to carry two null alleles. Overall, the new data agree with a working model relating the different pathogenic phenotypes to the severity of the mutations. When considering the information presented here together with that of previous reports, a picture of the geographic distribution of three particular mutations emerges. The R212C change has been found in French, Italian, Dutch, German, and Spanish but not in British patients. In the Spanish collection, R212C was found in a CRD patient, indicating that it may be a rather severe change. In contrast, c.2588G>C, a very common mild allele in the Dutch population, is rarely found in Southern Europe. Interestingly, the c.2588G>C mutation has been found in a double mutant allele together with the missense R1055W. Finally, the newly described L1940P was found in two unrelated Spanish patients, and may be a moderate to severe allele. Copyright 2001 Wiley-Liss, Inc.

The Time Required for Dormancy Release in Arabidopsis Is Determined by DELAY OF GERMINATION1 Protein Levels in Freshly Harvested Seeds[OA

PubMed Central

Nakabayashi, Kazumi; Bartsch, Melanie; Xiang, Yong; Miatton, Emma; Pellengahr, Silke; Yano, Ryoichi; Seo, Mitsunori; Soppe, Wim J.J.

2012-01-01

Seed dormancy controls the start of a plant’s life cycle by preventing germination of a viable seed in an unfavorable season. Freshly harvested seeds usually show a high level of dormancy, which is gradually released during dry storage (after-ripening). Abscisic acid (ABA) has been identified as an essential factor for the induction of dormancy, whereas gibberellins (GAs) are required for germination. The molecular mechanisms controlling seed dormancy are not well understood. DELAY OF GERMINATION1 (DOG1) was recently identified as a major regulator of dormancy in Arabidopsis thaliana. Here, we show that the DOG1 protein accumulates during seed maturation and remains stable throughout seed storage and imbibition. The levels of DOG1 protein in freshly harvested seeds highly correlate with dormancy. The DOG1 protein becomes modified during after-ripening, and its levels in stored seeds do not correlate with germination potential. Although ABA levels in dog1 mutants are reduced and GA levels enhanced, we show that DOG1 does not regulate dormancy primarily via changes in hormone levels. We propose that DOG1 protein abundance in freshly harvested seeds acts as a timer for seed dormancy release, which functions largely independent from ABA. PMID:22829147

[Level of selected antibacterial tear proteins in children with diabetes type 1].

PubMed

Moll, Agnieszka; Wyka, Krystyna; Młynarski, Wojciech; Niwald, Anna

2011-01-01

Antibacterial immunity in diabetes is impaired, which increases the risk of general and local infections. The aim of the study was to evaluate non-specific local antibacterial immunity based on lactoferrin and lysozyme concentration in tears in children with diabetes type 1. Children at the age of 10-18 years old were studied. Group 1. consisted of children without diabetes, group 2. included patients with new onset of diabetes and group 3. consisted of children with decade-long diabetes. Among all patients tears were collected from inferior coniunctival fornix with hematocrit glass capillaries in purpose to measure lactoferrin and lysozyme concentration. ELISA method was used in laboratory testing. Level of lactoferrin did not differ significantly among all groups. Concentration of lysozyme was statistically lower in group with decade-long diabetes (group 3.) compared to patients without diabetes. Mild correlation between lactoferrin and lysozyme levels was seen in individual patients in whole group of probands together. Diabetes type 1 in children is associated with significant changes in concentration of tear proteins, which contribute to antibacterial immunity.

Effects of High Estrogen Levels on Monocyte Chemoattractant Protein-1 and Wound Healing

PubMed Central

Plackett, Timothy P.; Gregory, Meredith S.; Kovacs, Elizabeth J.

2015-01-01

Objective: Herein, we tested the effects of high levels of supplemental estrogen treatment on cutaneous wound healing. Approach: Female mice were implanted with a 17β-estradiol (E2) secreting pellet or placebo before receiving a full-thickness dermal excisional wound. Mice receiving the E2 pellet attained hormone levels that are comparable to those achieved during pregnancy. At 1, 3, and 5 days after injury, the dermal excision wound was examined for their histologic appearance, rate of closure, and chemokine levels. Results: Wound closure, assessed by percent reepithelialization, was slower in E2-treated mice relative to placebo (42.6%±6.6% vs. 70.0%±5.3%, respectively, 3 days after injury). In addition, there was a marked reduction in the subepithelial inflammatory infiltrate and granulation tissue in E2-treated mice relative to placebo. Wound levels of monocyte chemoattractant protein-1 (MCP-1) were increased by 3 days after injury and continued to rise at 5 days after injury in placebo-treated mice (p<0.01). By contrast, MCP-1 levels were significantly reduced at 3 and 5 days after injury in E2-treated mice relative to placebo-treated controls (p<0.01). This attenuation could be reversed by treatment with an estrogen receptor antagonist. Innovation: High levels of estrogen are able to suppress normal wound closure. Conclusion: Dermal wound healing can be altered by manipulating the gonadal steroid hormone levels. In particular, high levels of estrogen can be utilized to slow down the rate of wound healing through a reduction in the inflammatory response. PMID:25713751

Influence of casein as a percentage of true protein and protein level on color and texture of milks containing 1 and 2% fat.

PubMed

Misawa, Noriko; Barbano, David M; Drake, MaryAnne

2016-07-01

Combinations of fresh liquid microfiltration retentate of skim milk, ultrafiltered retentate and permeate produced from microfiltration permeate, cream, and dried lactose monohydrate were used to produce a matrix of 20 milks. The milks contained 5 levels of casein as a percentage of true protein of about 5, 25, 50, 75, and 80% and 4 levels of true protein of 3.0, 3.76, 4.34, and 5.0% with constant lactose percentage of 5%. The experiment was replicated twice and repeated for both 1 and 2% fat content. Hunter color measurements, relative viscosity, and fat globule size distribution were measured, and a trained panel documented appearance and texture attributes on all milks. Overall, casein as a percentage of true protein had stronger effects than level of true protein on Hunter L, a, b values, relative viscosity, and fat globule size when using fresh liquid micellar casein concentrates and milk serum protein concentrates produced by a combination of microfiltration and ultrafiltration. As casein as a percentage of true protein increased, the milks became more white (higher L value), less green (lower negative a value), and less yellow (lower b value). Relative viscosity increased and d(0.9) generally decreased with increasing casein as a percentage of true protein. Panelists perceived milks with increasing casein as a percentage of true protein as more white, more opaque, and less yellow. Panelists were able to detect increased throat cling and mouthcoating with increased casein as a percentage of true protein in 2% milks, even when differences in appearance among milks were masked. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The redox protein thioredoxin-1 (Trx-1) increases hypoxia-inducible factor 1alpha protein expression: Trx-1 overexpression results in increased vascular endothelial growth factor production and enhanced tumor angiogenesis.

PubMed

Welsh, Sarah J; Bellamy, William T; Briehl, Margaret M; Powis, Garth

2002-09-01

Hypoxia-inducible factor 1 (HIF-1), a heterodimer of HIF-1alpha and HIF-1beta subunits, is a transcriptional activator central to the cellular response to low oxygen that includes metabolic adaptation, angiogenesis, metastasis, and inhibited apoptosis. Thioredoxin-1 (Trx-1) is a small redox protein overexpressed in a number of human primary tumors. We have examined the effects of Trx-1 on HIF activity and the activation of downstream genes. Stable transfection of human breast carcinoma MCF-7 cells with human Trx-1 caused a significant increase in HIF-1alpha protein levels under both normoxic (20% oxygen) and hypoxic (1% oxygen) conditions. Trx-1 increased hypoxia-induced HIF-1 transactivation activity measured using a luciferase reporter under the control of the hypoxia response element. Changes in HIF-1alpha mRNA levels did not account for the changes observed at the protein level, and HIF-1beta protein levels did not change. Trx-1 transfection also caused a significant increase in the protein products of hypoxia-responsive genes, including vascular endothelial growth factor (VEGF) and nitric oxide synthase 2 in a number of different cell lines (MCF-7 human breast and HT29 human colon carcinomas and WEHI7.2 mouse lymphoma cells) under both normoxic and hypoxic conditions. The pattern of expression of the different isoforms of VEGF was not changed by Trx-1. Transfection of a redox-inactive Trx-1 (C32S/C35S) markedly decreased levels of HIF-1alpha protein, HIF-1 transactivating activity, and VEGF protein in MCF-7 cells compared with empty vector controls. In vivo studies using WEHI7.2 cells transfected with Trx-1 showed significantly increased tumor VEGF and angiogenesis. The results suggest that Trx-1 increases HIF-1alpha protein levels in cancer cells and increases VEGF production and tumor angiogenesis.

Role of APOE Isoforms in the Pathogenesis of TBI induced Alzheimer’s Disease

DTIC Science & Technology

2016-10-01

deletion, APOE targeted replacement, complex breeding, CCI model optimization, mRNA library generation, high throughput massive parallel sequencing...demonstrate that the lack of Abca1 increases amyloid plaques and decreased APOE protein levels in AD-model mice. In this proposal we will test the hypothesis...injury, inflammatory reaction, transcriptome, high throughput massive parallel sequencing, mRNA-seq., behavioral testing, memory impairment, recovery 3

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.

A Cytogenetic Abnormality and Rare Coding Variants Identify ABCA13 as a Candidate Gene in Schizophrenia, Bipolar Disorder, and Depression

PubMed Central

Knight, Helen M.; Pickard, Benjamin S.; Maclean, Alan; Malloy, Mary P.; Soares, Dinesh C.; McRae, Allan F.; Condie, Alison; White, Angela; Hawkins, William; McGhee, Kevin; van Beck, Margaret; MacIntyre, Donald J.; Starr, John M.; Deary, Ian J.; Visscher, Peter M.; Porteous, David J.; Cannon, Ronald E.; St Clair, David; Muir, Walter J.; Blackwood, Douglas H.R.

2009-01-01

Schizophrenia and bipolar disorder are leading causes of morbidity across all populations, with heritability estimates of ∼80% indicating a substantial genetic component. Population genetics and genome-wide association studies suggest an overlap of genetic risk factors between these illnesses but it is unclear how this genetic component is divided between common gene polymorphisms, rare genomic copy number variants, and rare gene sequence mutations. We report evidence that the lipid transporter gene ABCA13 is a susceptibility factor for both schizophrenia and bipolar disorder. After the initial discovery of its disruption by a chromosome abnormality in a person with schizophrenia, we resequenced ABCA13 exons in 100 cases with schizophrenia and 100 controls. Multiple rare coding variants were identified including one nonsense and nine missense mutations and compound heterozygosity/homozygosity in six cases. Variants were genotyped in additional schizophrenia, bipolar, depression (n > 1600), and control (n > 950) cohorts and the frequency of all rare variants combined was greater than controls in schizophrenia (OR = 1.93, p = 0.0057) and bipolar disorder (OR = 2.71, p = 0.00007). The population attributable risk of these mutations was 2.2% for schizophrenia and 4.0% for bipolar disorder. In a study of 21 families of mutation carriers, we genotyped affected and unaffected relatives and found significant linkage (LOD = 4.3) of rare variants with a phenotype including schizophrenia, bipolar disorder, and major depression. These data identify a candidate gene, highlight the genetic overlap between schizophrenia, bipolar disorder, and depression, and suggest that rare coding variants may contribute significantly to risk of these disorders. PMID:19944402

High hydrostatic pressure extract of garlic increases the HDL cholesterol level via up-regulation of apolipoprotein A-I gene expression in rats fed a high-fat diet

PubMed Central

2012-01-01

Background Cardiovascular disease (CVD) is the number one cause of mortality worldwide and a low high-density lipoprotein cholesterol (HDL-C) level is an important marker of CVD risk. Garlic (Allium sativum) has been widely used in the clinic for treatment of CVD and regulation of lipid metabolism. This study investigated the effects of a high hydrostatic pressure extract of garlic (HEG) on HDL-C level and regulation of hepatic apolipoprotein A-I (apoA-I) gene expression. Methods Male Sprague–Dawley rats were divided into two groups and maintained on a high-fat control diet (CON) or high-fat control diet supplemented with high hydrostatic pressure extract of garlic (HEG) for 5 weeks. Changes in the expression of genes related to HDL-C metabolism were analyzed in liver, together with biometric and blood parameters. Results In the HEG group, the plasma triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased in comparison with the CON group (P < 0.05). Dietary HEG also lowered the hepatic TG and total cholesterol (TC) levels compared to the CON group. While the plasma HDL-C level and mRNA level of hepatic apoA-I, which is one of primarily proteins of HDL-C particle, were significantly increased in the HEG group compared to the CON group (P < 0.05). The gene expression of ATP-binding cassette transporter A1 (ABCA1) and lecithin:cholesterol acyltransferase (LCAT), importantly involved in the biogenesis in HDL, were also up-regulated by dietary HEG. Conclusions These results suggest that HEG ameliorates plasma lipid profiles and attenuates hepatic lipid accumulation in the high-fat fed rats. Our findings provides that the effects of HEG on the increase of the plasma HDL-C level was at least partially mediated by up-regulation of hepatic genes expression such as apoA-I, ABCA1, and LCAT in rats fed a high-fat diet. PMID:22713542

High hydrostatic pressure extract of garlic increases the HDL cholesterol level via up-regulation of apolipoprotein A-I gene expression in rats fed a high-fat diet.

PubMed

Lee, Seohyun; Joo, Hyunjin; Kim, Chong-Tai; Kim, In-Hwan; Kim, Yangha

2012-06-19

Cardiovascular disease (CVD) is the number one cause of mortality worldwide and a low high-density lipoprotein cholesterol (HDL-C) level is an important marker of CVD risk. Garlic (Allium sativum) has been widely used in the clinic for treatment of CVD and regulation of lipid metabolism. This study investigated the effects of a high hydrostatic pressure extract of garlic (HEG) on HDL-C level and regulation of hepatic apolipoprotein A-I (apoA-I) gene expression. Male Sprague-Dawley rats were divided into two groups and maintained on a high-fat control diet (CON) or high-fat control diet supplemented with high hydrostatic pressure extract of garlic (HEG) for 5 weeks. Changes in the expression of genes related to HDL-C metabolism were analyzed in liver, together with biometric and blood parameters. In the HEG group, the plasma triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) levels were significantly decreased in comparison with the CON group (P < 0.05). Dietary HEG also lowered the hepatic TG and total cholesterol (TC) levels compared to the CON group. While the plasma HDL-C level and mRNA level of hepatic apoA-I, which is one of primarily proteins of HDL-C particle, were significantly increased in the HEG group compared to the CON group (P < 0.05). The gene expression of ATP-binding cassette transporter A1 (ABCA1) and lecithin:cholesterol acyltransferase (LCAT), importantly involved in the biogenesis in HDL, were also up-regulated by dietary HEG. These results suggest that HEG ameliorates plasma lipid profiles and attenuates hepatic lipid accumulation in the high-fat fed rats. Our findings provides that the effects of HEG on the increase of the plasma HDL-C level was at least partially mediated by up-regulation of hepatic genes expression such as apoA-I, ABCA1, and LCAT in rats fed a high-fat diet.

Increased serum levels of high mobility group box 1 protein in patients with autistic disorder.

PubMed

Emanuele, Enzo; Boso, Marianna; Brondino, Natascia; Pietra, Stefania; Barale, Francesco; Ucelli di Nemi, Stefania; Politi, Pierluigi

2010-05-30

High mobility group box 1 (HMGB1) is a highly conserved, ubiquitous protein that functions as an activator for inducing the immune response and can be released from neurons after glutamate excitotoxicity. The objective of the present study was to measure serum levels of HMGB1 in patients with autistic disorder and to study their relationship with clinical characteristics. We enrolled 22 adult patients with autistic disorder (mean age: 28.1+/-7.7 years) and 28 age- and gender-matched healthy controls (mean age: 28.7+/-8.1 years). Serum levels of HMGB1 were measured by enzyme-linked immunosorbent assay (ELISA). Compared with healthy subjects, serum levels of HMGB1 were significantly higher in patients with autistic disorder (10.8+/-2.6 ng/mL versus 5.6+/-2.5 ng/mL, respectively, P<0.001). After adjustment for potential confounders, serum HMGB1 levels were independently associated with their domain A scores in the Autism Diagnostic Interview-Revised, which reflects their impairments in social interaction. These results suggest that HMGB1 levels may be affected in autistic disorder. Increased HMGB1 may be a biological correlate of the impaired reciprocal social interactions in this neurodevelopmental disorder. Copyright 2010 Elsevier Inc. All rights reserved.

ATP-binding cassette subfamily A, member 4 intronic variants c.4773+3A>G and c.5461-10T>C cause Stargardt disease due to defective splicing.

PubMed

Jonsson, Frida; Westin, Ida Maria; Österman, Lennart; Sandgren, Ola; Burstedt, Marie; Holmberg, Monica; Golovleva, Irina

2018-02-20

Inherited retinal dystrophies (IRDs) represent a group of progressive conditions affecting the retina. There is a great genetic heterogeneity causing IRDs, and to date, more than 260 genes are associated with IRDs. Stargardt disease, type 1 (STGD1) or macular degeneration with flecks, STGD1 represents a disease with early onset, central visual impairment, frequent appearance of yellowish flecks and mutations in the ATP-binding cassette subfamily A, member 4 (ABCA4) gene. A large number of intronic sequence variants in ABCA4 have been considered pathogenic although their functional effect was seldom demonstrated. In this study, we aimed to reveal how intronic variants present in patients with Stargardt from the same Swedish family affect splicing. The splicing of the ABCA4 gene was studied in human embryonic kidney cells, HEK293T, and in human retinal pigment epithelium cells, ARPE-19, using a minigene system containing variants c.4773+3A>G and c.5461-10T>C. We showed that both ABCA4 variants, c.4773+3A>G and c.5461-10T>C, cause aberrant splicing of the ABCA4 minigene resulting in exon skipping. We also demonstrated that splicing of ABCA4 has different outcomes depending on transfected cell type. Two intronic variants c.4773+3A>G and c.5461-10T>C, both predicted to affect splicing, are indeed disease-causing mutations due to skipping of exons 33, 34, 39 and 40 of ABCA4 gene. The experimental proof that ABCA4 mutations in STGD patients affect protein function is crucial for their inclusion to future clinical trials; therefore, functional testing of all ABCA4 intronic variants associated with Stargardt disease by minigene technology is desirable. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Oral vaccine of Lactococcus lactis harbouring pandemic H1N1 2009 haemagglutinin1 and nisP anchor fusion protein elevates anti-HA1 sIgA levels in mice.

PubMed

Joan, Stella Siaw Xiu; Pui-Fong, Jee; Song, Adelene Ai-Lian; Chang, Li-Yen; Yusoff, Khatijah; AbuBakar, Sazaly; Rahim, Raha Abdul

2016-05-01

An oral lactococcal-based vaccine which haboured the haemagglutinin1 (HA1) antigen fused to nisP anchor protein for the purpose of surface displaying the HA1 antigen was developed against H1N1 virus. Recombinant L. lactis strains expressed HA1-nisP fusion proteins when induced with nisin, as confirmed through western blotting. However, immunofluorescense did not detect any surface-displayed proteins, suggesting that the protein was either unsuccessfully translocated or improperly displayed. Despite this, oral administration of recombinant L. lactis strains to BALB/c mice revealed that significant levels of anti-HA1 sIgA antibodies were detected in mice fecal suspension samples of mice group NZ9000 (pNZ:HN) when compared to the negative control NZ9000 (pNZ8048) group. Specific anti-HA1 sIgA antibodies were locally produced and live recombinant lactococcal vaccine was able to elicit humoral response of BALB/c mice despite unsuccessful surface display of the HA1 epitope.

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.

BAG3 regulates total MAP1LC3B protein levels through a translational but not transcriptional mechanism.

PubMed

Rodríguez, Andrea E; López-Crisosto, Camila; Peña-Oyarzún, Daniel; Salas, Daniela; Parra, Valentina; Quiroga, Clara; Morawe, Tobias; Chiong, Mario; Behl, Christian; Lavandero, Sergio

2016-01-01

Autophagy is mainly regulated by post-translational and lipid modifications of ATG proteins. In some scenarios, the induction of autophagy is accompanied by increased levels of certain ATG mRNAs such as MAP1LC3B/LC3B, ATG5 or ATG12. However, little is known about the regulation of ATG protein synthesis at the translational level. The cochaperone of the HSP70 system BAG3 (BCL2-associated athanogene 3) has been associated to LC3B lipidation through an unknown mechanism. In the present work, we studied how BAG3 controls autophagy in HeLa and HEK293 cells. Our results showed that BAG3 regulates the basal amount of total cellular LC3B protein by controlling its mRNA translation. This effect was apparently specific to LC3B because other ATG protein levels were not affected. BAG3 knockdown did not affect LC3B lipidation induced by nutrient deprivation or proteasome inhibition. We concluded that BAG3 maintains the basal amount of LC3B protein by controlling the translation of its mRNA in HeLa and HEK293 cells.

BAG3 regulates total MAP1LC3B protein levels through a translational but not transcriptional mechanism

PubMed Central

Rodríguez, Andrea E.; López-Crisosto, Camila; Peña-Oyarzún, Daniel; Salas, Daniela; Parra, Valentina; Quiroga, Clara; Morawe, Tobias; Chiong, Mario; Behl, Christian; Lavandero, Sergio

2016-01-01

ABSTRACT Autophagy is mainly regulated by post-translational and lipid modifications of ATG proteins. In some scenarios, the induction of autophagy is accompanied by increased levels of certain ATG mRNAs such as MAP1LC3B/LC3B, ATG5 or ATG12. However, little is known about the regulation of ATG protein synthesis at the translational level. The cochaperone of the HSP70 system BAG3 (BCL2-associated athanogene 3) has been associated to LC3B lipidation through an unknown mechanism. In the present work, we studied how BAG3 controls autophagy in HeLa and HEK293 cells. Our results showed that BAG3 regulates the basal amount of total cellular LC3B protein by controlling its mRNA translation. This effect was apparently specific to LC3B because other ATG protein levels were not affected. BAG3 knockdown did not affect LC3B lipidation induced by nutrient deprivation or proteasome inhibition. We concluded that BAG3 maintains the basal amount of LC3B protein by controlling the translation of its mRNA in HeLa and HEK293 cells. PMID:26654586

Inhibition of soluble epoxide hydrolase in mice promotes reverse cholesterol transport and regression of atherosclerosis.

PubMed

Shen, Li; Peng, Hongchun; Peng, Ran; Fan, Qingsong; Zhao, Shuiping; Xu, Danyan; Morisseau, Christophe; Chiamvimonvat, Nipavan; Hammock, Bruce D

2015-04-01

Adipose tissue is the body largest free cholesterol reservoir and abundantly expresses ATP binding cassette transporter A1 (ABCA1), which maintains plasma high-density lipoprotein (HDL) levels. HDLs have a protective role in atherosclerosis by mediating reverse cholesterol transport (RCT). Soluble epoxide hydrolase (sEH) is a cytosolic enzyme whose inhibition has various beneficial effects on cardiovascular disease. The sEH is highly expressed in adipocytes, and it converts epoxyeicosatrienoic acids (EETs) into less bioactive dihydroxyeicosatrienoic acids. We previously showed that increasing EETs levels with a sEH inhibitor (sEHI) (t-AUCB) resulted in elevated ABCA1 expression and promoted ABCA1-mediated cholesterol efflux from 3T3-L1 adipocytes. The present study investigates the impacts of t-AUCB in mice deficient for the low density lipoprotein (LDL) receptor (Ldlr(-/-) mice) with established atherosclerotic plaques. The sEH inhibitor delivered in vivo for 4 weeks decreased the activity of sEH in adipose tissue, enhanced ABCA1 expression and cholesterol efflux from adipose depots, and consequently increased HDL levels. Furthermore, t-AUCB enhanced RCT to the plasma, liver, bile and feces. It also showed the reduction of plasma LDL-C levels. Consistently, t-AUCB-treated mice showed reductions in the size of atherosclerotic plaques. These studies establish that raising adipose ABCA1 expression, cholesterol efflux, and plasma HDL levels with t-AUCB treatment promotes RCT, decreasing LDL-C and atherosclerosis regression, suggesting that sEH inhibition may be a promising strategy to treat atherosclerotic vascular disease. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Identification of a Novel Hypocholesterolemic Protein, Major Royal Jelly Protein 1, Derived from Royal Jelly

PubMed Central

Asai, Saori; Kusada, Mio; Watanabe, Suzuyo; Kawashima, Takuji; Nakamura, Tadashi; Shimada, Masaya; Goto, Tsuyoshi; Nagaoka, Satoshi

2014-01-01

Royal jelly (RJ) intake lowers serum cholesterol levels in animals and humans, but the active component in RJ that lowers serum cholesterol level and its molecular mechanism are unclear. In this study, we set out to identify the bile acid-binding protein contained in RJ, because dietary bile acid-binding proteins including soybean protein and its peptide are effective in ameliorating hypercholesterolemia. Using a cholic acid-conjugated column, we separated some bile acid-binding proteins from RJ and identified the major RJ protein 1 (MRJP1), MRJP2, and MRJP3 as novel bile acid-binding proteins from RJ, based on matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Purified MRJP1, which is the most abundant protein of the bile acid-binding proteins in RJ, exhibited taurocholate-binding activity in vitro. The micellar solubility of cholesterol was significantly decreased in the presence of MRJP1 compared with casein in vitro. Liver bile acids levels were significantly increased, and cholesterol 7α-hydroxylase (CYP7A1) mRNA and protein tended to increase by MRJP1 feeding compared with the control. CYP7A1 mRNA and protein levels were significantly increased by MRJP1 tryptic hydrolysate treatment compared with that of casein tryptic hydrolysate in hepatocytes. MRJP1 hypocholesterolemic effect has been investigated in rats. The cholesterol-lowering action induced by MRJP1 occurs because MRJP1 interacts with bile acids induces a significant increase in fecal bile acids excretion and a tendency to increase in fecal cholesterol excretion and also enhances the hepatic cholesterol catabolism. We have identified, for the first time, a novel hypocholesterolemic protein, MRJP1, in RJ. Interestingly, MRJP1 exhibits greater hypocholesterolemic activity than the medicine β-sitosterol in rats. PMID:25144734

Flotillin proteins recruit sphingosine to membranes and maintain cellular sphingosine-1-phosphate levels

PubMed Central

Riento, Kirsi; Zhang, Qifeng; Clark, Jonathan; Begum, Farida; Stephens, Elaine; Wakelam, Michael J.

2018-01-01

Sphingosine-1-phosphate (S1P) is an important lipid signalling molecule. S1P is produced via intracellular phosphorylation of sphingosine (Sph). As a lipid with a single fatty alkyl chain, Sph may diffuse rapidly between cellular membranes and through the aqueous phase. Here, we show that the absence of microdomains generated by multimeric assemblies of flotillin proteins results in reduced S1P levels. Cellular phenotypes of flotillin knockout mice, including changes in histone acetylation and expression of Isg15, are recapitulated when S1P synthesis is perturbed. Flotillins bind to Sph in vitro and increase recruitment of Sph to membranes in cells. Ectopic re-localisation of flotillins within the cell causes concomitant redistribution of Sph. The data suggest that flotillins may directly or indirectly regulate cellular sphingolipid distribution and signalling. PMID:29787576

Serum and cerebrospinal fluid levels of visinin-like protein-1 in acute encephalopathy with biphasic seizures and late reduced diffusion.

PubMed

Hasegawa, Shunji; Matsushige, Takeshi; Inoue, Hirofumi; Takahara, Midori; Kajimoto, Madoka; Momonaka, Hiroshi; Oka, Momoko; Isumi, Hiroshi; Emi, Sakie; Hayashi, Megumi; Ichiyama, Takashi

2014-08-01

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) has recently been recognized as an encephalopathy subtype. Typical clinical symptoms of AESD are biphasic seizures, and MRI findings show reduced subcortical diffusion during clustering seizures with unconsciousness after the acute phase. Visinin-like protein-1 (VILIP-1) is a recently discovered protein that is abundant in the central nervous system, and some reports have shown that VILIP-1 may be a prognostic biomarker of conditions such as Alzheimer's disease, stroke, and brain injury. However, there have been no reports regarding serum and cerebrospinal fluid (CSF) levels of VILIP-1 in patients with AESD. We measured the serum and CSF levels of VILIP-1 in patients with AESD, and compared the levels to those in patients with prolonged febrile seizures (FS). Both serum and CSF levels of VILIP-1 were significantly higher in patients with AESD than in patients with prolonged FS. Serum and CSF VILIP-1 levels were normal on day 1 of AESD. Our results suggest that both serum and CSF levels of VILIP-1 may be one of predictive markers of AESD. Copyright © 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

The Heterotrimeric G-Protein Subunits GNG-1 and GNB-1 Form a Gβγ Dimer Required for Normal Female Fertility, Asexual Development, and Gα Protein Levels in Neurospora crassa

PubMed Central

Krystofova, Svetlana; Borkovich, Katherine A.

2005-01-01

We have identified a gene encoding a heterotrimeric G protein γ subunit, gng-1, from the filamentous fungus Neurospora crassa. gng-1 possesses a gene structure similar to that of mammalian Gγ genes, consisting of three exons and two introns, with introns present in both the open reading frame and 5′-untranslated region. The GNG-1 amino acid sequence displays high identity to predicted Gγ subunits from other filamentous fungi, including Giberella zeae, Cryphonectria parasitica, Trichoderma harzianum, and Magnaporthe grisea. Deletion of gng-1 leads to developmental defects similar to those previously characterized for Δgnb-1 (Gβ) mutants. Δgng-1, Δgnb-1, and Δgng-1 Δgnb-1 strains conidiate inappropriately in submerged cultures and are female sterile, producing aberrant female reproductive structures. Similar to previous results obtained with Δgnb-1 mutants, loss of gng-1 negatively influences levels of Gα proteins (GNA-1, GNA-2, and GNA-3) in plasma membrane fractions isolated from various tissues of N. crassa and leads to a significant reduction in the amount of intracellular cyclic AMP. In addition, we show that GNB-1 is essential for maintenance of normal steady-state levels of GNG-1, suggesting a functional interaction between GNB-1 and GNG-1. Direct evidence for a physical association between GNB-1 and GNG-1 in vivo was provided by coimmunoprecipitation. PMID:15701799

Fragile X Mental Retardation Protein Regulates the Levels of Scaffold Proteins and Glutamate Receptors in Postsynaptic Densities*

PubMed Central

Schütt, Janin; Falley, Katrin; Richter, Dietmar; Kreienkamp, Hans-Jürgen; Kindler, Stefan

2009-01-01

Functional absence of fragile X mental retardation protein (FMRP) causes the fragile X syndrome, a hereditary form of mental retardation characterized by a change in dendritic spine morphology. The RNA-binding protein FMRP has been implicated in regulating postsynaptic protein synthesis. Here we have analyzed whether the abundance of scaffold proteins and neurotransmitter receptor subunits in postsynaptic densities (PSDs) is altered in the neocortex and hippocampus of FMRP-deficient mice. Whereas the levels of several PSD components are unchanged, concentrations of Shank1 and SAPAP scaffold proteins and various glutamate receptor subunits are altered in both adult and juvenile knock-out mice. With the exception of slightly increased hippocampal SAPAP2 mRNA levels in adult animals, altered postsynaptic protein concentrations do not correlate with similar changes in total and synaptic levels of corresponding mRNAs. Thus, loss of FMRP in neurons appears to mainly affect the translation and not the abundance of particular brain transcripts. Semi-quantitative analysis of RNA levels in FMRP immunoprecipitates showed that in the mouse brain mRNAs encoding PSD components, such as Shank1, SAPAP1–3, PSD-95, and the glutamate receptor subunits NR1 and NR2B, are associated with FMRP. Luciferase reporter assays performed in primary cortical neurons from knock-out and wild-type mice indicate that FMRP silences translation of Shank1 mRNAs via their 3′-untranslated region. Activation of metabotropic glutamate receptors relieves translational suppression. As Shank1 controls dendritic spine morphology, our data suggest that dysregulation of Shank1 synthesis may significantly contribute to the abnormal spine development and function observed in brains of fragile X syndrome patients. PMID:19640847

Effects of Dietary Crude Protein Levels and Cysteamine Supplementation on Protein Synthetic and Degradative Signaling in Skeletal Muscle of Finishing Pigs.

PubMed

Zhou, Ping; Zhang, Lin; Li, Jiaolong; Luo, Yiqiu; Zhang, Bolin; Xing, Shen; Zhu, Yuping; Sun, Hui; Gao, Feng; Zhou, Guanghong

2015-01-01

Dietary protein levels and cysteamine (CS) supplementation can affect growth performance and protein metabolism of pigs. However, the influence of dietary protein intake on the growth response of CS-treated pigs is unclear, and the mechanisms involved in protein metabolism remain unknown. Hence, we investigated the interactions between dietary protein levels and CS supplementation and the effects of dietary crude protein levels and CS supplementation on protein synthetic and degradative signaling in skeletal muscle of finishing pigs. One hundred twenty barrows (65.84 ± 0.61 kg) were allocated to a 2 × 2 factorial arrangement with five replicates of six pigs each. The primary variations were dietary crude protein (CP) levels (14% or 10%) and CS supplemental levels (0 or 700 mg/kg). The low-protein (LP) diets (10% CP) were supplemented with enough essential amino acids (EAA) to meet the NRC AA requirements of pigs and maintain the balanced supply of eight EAA including lysine, methionine, threonine, tryptophan, valine, phenylalanine, isoleucine, and leucine. After 41 days, 10 pigs per treatment were slaughtered. We found that LP diets supplemented with EAA resulted in decreased concentrations of plasma somatostatin (SS) (P<0.01) and plasma urea nitrogen (PUN) (P<0.001), while dietary protein levels did not affect other traits. However, CS supplementation increased the average daily gain (P<0.001) and lean percentage (P<0.05), and decreased the feed conversion ratio (P<0.05) and back fat (P<0.05). CS supplementation also increased the concentrations of plasma insulin-like growth factor 1 (IGF-1) (P<0.001), and reduced the concentrations of leptin, SS, and PUN (P<0.001). Increased mRNA abundance of Akt1 and IGF-1 signaling (P<0.001) and decreased mRNA abundance of Forkhead Box O (FOXO) 4 (P<0.01) and muscle atrophy F-box (P<0.001) were observed in pigs receiving CS. Additionally, CS supplementation increased the protein levels for the phosphorylated mammalian target

Sex steroid-induced changes in circulating monocyte chemoattractant protein-1 levels may contribute to metabolic dysfunction in obese men.

PubMed

Ruige, Johannes B; Bekaert, Marlies; Lapauw, Bruno; Fiers, Tom; Lehr, Stefan; Hartwig, Sonja; Herzfeld de Wiza, Daniella; Schiller, Martina; Passlack, Waltraud; Van Nieuwenhove, Yves; Pattyn, Piet; Cuvelier, Claude; Taes, Youri E; Sell, Henrike; Eckel, Juergen; Kaufman, Jean-Marc; Ouwens, D Margriet

2012-07-01

Low testosterone accompanied by elevated estradiol associates with the development of metabolic dysfunction in men. The aim of the study was to explore the hypothesis that alterations in sex steroid levels induce metabolic dysfunction through adipokines. Circulating levels of sex steroids and 28 adipokines were determined in a cross-sectional study of morbidly obese men and aged-matched controls, as well as in a randomized clinical trial with healthy young men in which obesity-related alterations in sex steroid levels were mimicked by treatment with an aromatase inhibitor plus estradiol patches. Morbidly obese men had lower testosterone levels than normal-weight controls. Estradiol levels were increased in morbidly obese men (without DM2) as compared to normal-weight controls. Circulating levels of multiple proinflammatory cytokines, including IL-1Ra, IL-5, IL-6, IL-10, leptin, monocyte chemoattractant protein 1 (MCP1), and macrophage inflammatory protein 1α, positively associated with estradiol and negatively with testosterone. The associations with estradiol, but not with testosterone, remained significant after adjusting for adipocyte cell size. In a separate clinical trial, the direct adverse effects of lowering testosterone and raising estradiol on MCP1 were substantiated in vivo. Initial alterations in sex steroid levels may contribute to metabolic dysfunction through adverse effects on adipokine levels in obese men. The direct adverse effects on MCP1, a chemokine highly linked to the development of metabolic dysfunction, were substantiated in a trial mimicking obesity-related alterations of sex steroid levels in healthy young males.

Identification of a Chrysanthemic Ester as an Apolipoprotein E Inducer in Astrocytes

PubMed Central

Zhao, Wenchen; Shimizu, Yoko; Pfeifer, Tom A.; Tak, Jun-Hyung; Isman, Murray B.; Van den Hoven, Bernard; Duggan, Mark E.; Wood, Michael W.; Wellington, Cheryl L.

2016-01-01

The apolipoprotein E (APOE) gene is the most highly associated susceptibility locus for late onset Alzheimer’s Disease (AD), and augmenting the beneficial physiological functions of apoE is a proposed therapeutic strategy. In a high throughput phenotypic screen for small molecules that enhance apoE secretion from human CCF-STTG1 astrocytoma cells, we show the chrysanthemic ester 82879 robustly increases expressed apoE up to 9.4-fold and secreted apoE up to 6-fold and is associated with increased total cholesterol in conditioned media. Compound 82879 is unique as structural analogues, including pyrethroid esters, show no effect on apoE expression or secretion. 82879 also stimulates liver x receptor (LXR) target genes including ATP binding cassette A1 (ABCA1), LXRα and inducible degrader of low density lipoprotein receptor (IDOL) at both mRNA and protein levels. In particular, the lipid transporter ABCA1 was increased by up to 10.6-fold upon 82879 treatment. The findings from CCF-STTG1 cells were confirmed in primary human astrocytes from three donors, where increased apoE and ABCA1 was observed along with elevated secretion of high-density lipoprotein (HDL)-like apoE particles. Nuclear receptor transactivation assays revealed modest direct LXR agonism by compound 82879, yet 10 μM of 82879 significantly upregulated apoE mRNA in mouse embryonic fibroblasts (MEFs) depleted of both LXRα and LXRβ, demonstrating that 82879 can also induce apoE expression independent of LXR transactivation. By contrast, deletion of LXRs in MEFs completely blocked mRNA changes in ABCA1 even at 10 μM of 82879, indicating the ability of 82879 to stimulate ABCA1 expression is entirely dependent on LXR transactivation. Taken together, compound 82879 is a novel chrysanthemic ester capable of modulating apoE secretion as well as apoE-associated lipid metabolic pathways in astrocytes, which is structurally and mechanistically distinct from known LXR agonists. PMID:27598782

Chemotherapy Agents Alter Plasma Lipids in Breast Cancer Patients and Show Differential Effects on Lipid Metabolism Genes in Liver Cells.

PubMed

Sharma, Monika; Tuaine, Jo; McLaren, Blair; Waters, Debra L; Black, Katherine; Jones, Lynnette M; McCormick, Sally P A

2016-01-01

Cardiovascular complications have emerged as a major concern for cancer patients. Many chemotherapy agents are cardiotoxic and some appear to also alter lipid profiles, although the mechanism for this is unknown. We studied plasma lipid levels in 12 breast cancer patients throughout their chemotherapy. Patients received either four cycles of doxorubicin and cyclophosphamide followed by weekly paclitaxel or three cycles of epirubicin, cyclophosphamide and 5'-fluorouracil followed by three cycles of docetaxel. Patients demonstrated a significant reduction (0.32 mmol/L) in high density lipoprotein cholesterol (HDL-C) and apolipoprotein A1 (apoA1) levels (0.18 g/L) and an elevation in apolipoprotein B (apoB) levels (0.15 g/L) after treatment. Investigation of the individual chemotherapy agents for their effect on genes involved in lipoprotein metabolism in liver cells showed that doxorubicin decreased ATP binding cassette transporter A1 (ABCA1) via a downregulation of the peroxisomal proliferator activated receptor γ (PPARγ) and liver X receptor α (LXRα) transcription factors. In contrast, ABCA1 levels were not affected by cyclophosphamide or paclitaxel. Likewise, apoA1 levels were reduced by doxorubicin and remained unaffected by cyclophosphamide and paclitaxel. Doxorubicin and paclitaxel both increased apoB protein levels and paclitaxel also decreased low density lipoprotein receptor (LDLR) protein levels. These findings correlate with the observed reduction in HDL-C and apoA1 and increase in apoB levels seen in these patients. The unfavourable lipid profiles produced by some chemotherapy agents may be detrimental in the longer term to cancer patients, especially those already at risk of cardiovascular disease (CVD). This knowledge may be useful in tailoring effective follow-up care plans for cancer survivors.

Zinc transporters protein level in postmortem brain of depressed subjects and suicide victims.

PubMed

Rafalo-Ulinska, Anna; Piotrowska, Joanna; Kryczyk, Agata; Opoka, Włodzimierz; Sowa-Kucma, Magdalena; Misztak, Paulina; Rajkowska, Grazyna; Stockmeier, Craig A; Datka, Wojciech; Nowak, Gabriel; Szewczyk, Bernadeta

2016-12-01

Major depressive disorder (MDD) is a serious psychiatric illness, associated with an increasing rate of suicide. The pathogenesis of depression may be associated with the disruption of zinc (Zn) homeostasis. In the brain, several proteins that regulate Zn homeostasis are present, including Zn transporters (ZnTs) which remove Zn from the cytosol. The present study was designed to investigate whether depression and suicide are associated with alterations in the expression of the ZnTs protein. Protein levels of ZnT1, ZnT3, ZnT4, ZnT5 and ZnT6 were measured in postmortem brain tissue from two different cohorts. Cohort A contained 10 subjects diagnosed with MDD (7 were suicide victims) and 10 psychiatrically-normal control subjects and cohort B contained 11 non-diagnosed suicide victims and 8 sudden-death control subjects. Moreover, in cohort A we measured protein level of NMDA (GluN2A subunit), AMPA (GluA1 subunit) and 5-HT1A receptors and PSD-95. Proteins were measured in the prefrontal cortex (PFC) using Western blotting. In addition, Zn concentration was measured using a voltammetric method. There was a significant increase in protein levels of ZnT1, ZnT4, ZnT5 in the PFC in MDD, relative to control subjects, while ZnT3 protein level was decreased in MDD. There was no significant difference in the Zn concentration in the PFC between control and MDD subjects. Similarly, in the PFC of suicide victims (non-diagnosed), an increase in protein levels of ZnT1, ZnT4, ZnT5 and ZnT6 was observed. Conversely, protein levels of ZnT3 were decreased in both suicide victims and subjects with MDD, in comparison with control subjects. There was also a significant decrease in the protein level of GluA1, GluN2A, PSD-95 and 5-HT1A in MDD. Our studies suggest that alterations in Zn transport proteins are associated with the pathophysiology of MDD and suicide. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adipose tissue uncoupling protein 1 levels and function are increased in a mouse model of developmental obesity induced by maternal exposure to high-fat diet.

PubMed

Bytautiene Prewit, E; Porter, C; La Rosa, M; Bhattarai, N; Yin, H; Gamble, P; Kechichian, T; Sidossis, L S

2018-05-17

With brown adipose tissue (BAT) becoming a possible therapeutic target to counteract obesity, the prenatal environment could represent a critical window to modify BAT function and browning of white AT. We investigated if levels of uncoupling protein 1 (UCP1) and UCP1-mediated thermogenesis are altered in offspring exposed to prenatal obesity. Female CD-1 mice were fed a high-fat (HF) or standard-fat (SF) diet for 3 months before breeding. After weaning, all pups were placed on SF. UCP1 mRNA and protein levels were quantified using quantitative real-time PCR and Western blot analysis, respectively, in brown (BAT), subcutaneous (SAT) and visceral (VAT) adipose tissues at 6 months of age. Total and UCP1-dependent mitochondrial respiration were determined by high-resolution respirometry. A Student's t-test and Mann-Whitney test were used (significance: P<0.05). UCP1 mRNA levels were not different between the HF and SF offspring. UCP1 protein levels, total mitochondrial respiration and UCP1-dependent respiration were significantly higher in BAT from HF males (P=0.02, P=0.04, P=0.005, respectively) and females (P=0.01, P=0.04, P=0.02, respectively). In SAT, the UCP1 protein was significantly lower in HF females (P=0.03), and the UCP1-dependent thermogenesis was significantly lower from HF males (P=0.04). In VAT, UCP1 protein levels and UCP1-dependent respiration were significantly lower only in HF females (P=0.03, P=0.04, respectively). There were no differences in total respiration in SAT and VAT. Prenatal exposure to maternal obesity leads to significant increases in UCP1 levels and function in BAT in offspring with little impact on UCP1 levels and function in SAT and VAT.

Molecular characterization of a phloem-specific gene encoding the filament protein, phloem protein 1 (PP1), from Cucurbita maxima.

PubMed

Clark, A M; Jacobsen, K R; Bostwick, D E; Dannenhoffer, J M; Skaggs, M I; Thompson, G A

1997-07-01

Sieve elements in the phloem of most angiosperms contain proteinaceous filaments and aggregates called P-protein. In the genus Cucurbita, these filaments are composed of two major proteins: PP1, the phloem filament protein, and PP2, the phloem lactin. The gene encoding the phloem filament protein in pumpkin (Cucurbita maxima Duch.) has been isolated and characterized. Nucleotide sequence analysis of the reconstructed gene gPP1 revealed a continuous 2430 bp protein coding sequence, with no introns, encoding an 809 amino acid polypeptide. The deduced polypeptide had characteristics of PP1 and contained a 15 amino acid sequence determined by N-terminal peptide sequence analysis of PP1. The sequence of PP1 was highly repetitive with four 200 amino acid sequence domains containing structural motifs in common with cysteine proteinase inhibitors. Expression of the PP1 gene was detected in roots, hypocotyls, cotyledons, stems, and leaves of pumpkin plants. PP1 and its mRNA accumulated in pumpkin hypocotyls during the period of rapid hypocotyl elongation after which mRNA levels declined, while protein levels remained elevated. PP1 was immunolocalized in slime plugs and P-protein bodies in sieve elements of the phloem. Occasionally, PP1 was detected in companion cells. PP1 mRNA was localized by in situ hybridization in companion cells at early stages of vascular differentiation. The developmental accumulation and localization of PP1 and its mRNA paralleled the phloem lactin, further suggesting an interaction between these phloem-specific proteins.

Nrbf2 protein suppresses autophagy by modulating Atg14L protein-containing Beclin 1-Vps34 complex architecture and reducing intracellular phosphatidylinositol-3 phosphate levels.

PubMed

Zhong, Yu; Morris, Deanna H; Jin, Lin; Patel, Mittul S; Karunakaran, Senthil K; Fu, You-Jun; Matuszak, Emily A; Weiss, Heidi L; Chait, Brian T; Wang, Qing Jun

2014-09-19

Autophagy is a tightly regulated lysosomal degradation pathway for maintaining cellular homeostasis and responding to stresses. Beclin 1 and its interacting proteins, including the class III phosphatidylinositol-3 kinase Vps34, play crucial roles in autophagy regulation in mammals. We identified nuclear receptor binding factor 2 (Nrbf2) as a Beclin 1-interacting protein from Becn1(-/-);Becn1-EGFP/+ mouse liver and brain. We also found that Nrbf2-Beclin 1 interaction required the N terminus of Nrbf2. We next used the human retinal pigment epithelial cell line RPE-1 as a model system and showed that transiently knocking down Nrbf2 by siRNA increased autophagic flux under both nutrient-rich and starvation conditions. To investigate the mechanism by which Nrbf2 regulates autophagy, we demonstrated that Nrbf2 interacted and colocalized with Atg14L, suggesting that Nrbf2 is a component of the Atg14L-containing Beclin 1-Vps34 complex. Moreover, ectopically expressed Nrbf2 formed cytosolic puncta that were positive for isolation membrane markers. These results suggest that Nrbf2 is involved in autophagosome biogenesis. Furthermore, we showed that Nrbf2 deficiency led to increased intracellular phosphatidylinositol-3 phosphate levels and diminished Atg14L-Vps34/Vps15 interactions, suggesting that Nrbf2-mediated Atg14L-Vps34/Vps15 interactions likely inhibit Vps34 activity. Therefore, we propose that Nrbf2 may interact with the Atg14L-containing Beclin 1-Vps34 protein complex to modulate protein-protein interactions within the complex, leading to suppression of Vps34 activity, autophagosome biogenesis, and autophagic flux. This work reveals a novel aspect of the intricate mechanism for the Beclin 1-Vps34 protein-protein interaction network to achieve precise control of autophagy. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Multi-level machine learning prediction of protein-protein interactions in Saccharomyces cerevisiae.

PubMed

Zubek, Julian; Tatjewski, Marcin; Boniecki, Adam; Mnich, Maciej; Basu, Subhadip; Plewczynski, Dariusz

2015-01-01

Accurate identification of protein-protein interactions (PPI) is the key step in understanding proteins' biological functions, which are typically context-dependent. Many existing PPI predictors rely on aggregated features from protein sequences, however only a few methods exploit local information about specific residue contacts. In this work we present a two-stage machine learning approach for prediction of protein-protein interactions. We start with the carefully filtered data on protein complexes available for Saccharomyces cerevisiae in the Protein Data Bank (PDB) database. First, we build linear descriptions of interacting and non-interacting sequence segment pairs based on their inter-residue distances. Secondly, we train machine learning classifiers to predict binary segment interactions for any two short sequence fragments. The final prediction of the protein-protein interaction is done using the 2D matrix representation of all-against-all possible interacting sequence segments of both analysed proteins. The level-I predictor achieves 0.88 AUC for micro-scale, i.e., residue-level prediction. The level-II predictor improves the results further by a more complex learning paradigm. We perform 30-fold macro-scale, i.e., protein-level cross-validation experiment. The level-II predictor using PSIPRED-predicted secondary structure reaches 0.70 precision, 0.68 recall, and 0.70 AUC, whereas other popular methods provide results below 0.6 threshold (recall, precision, AUC). Our results demonstrate that multi-scale sequence features aggregation procedure is able to improve the machine learning results by more than 10% as compared to other sequence representations. Prepared datasets and source code for our experimental pipeline are freely available for download from: http://zubekj.github.io/mlppi/ (open source Python implementation, OS independent).

Effect of lipoic acid on paraoxonase-1 and paraoxonase-3 protein levels, mRNA expression and arylesterase activity in liver hepatoma cells.

PubMed

Ozgun, Eray; Sayilan Ozgun, Gulben; Tabakcioglu, Kiymet; Suer Gokmen, Selma; Sut, Necdet; Eskiocak, Sevgi

2017-10-01

Paraoxonase-1 (PON1) and PON3 (PON3) are anti-atherosclerotic enzymes, synthesized primarily in liver and bound to HDL in circulation. The aim of the present study was to investigate the effects of therapeutic doses of lipoic acid on PON1 and PON3 protein levels, mRNA expression and arylesterase activity in liver. We treated HepG2 cells with 10, 40 and 200 μM lipoic acid for 72 h. Cell viability was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. PON1 and PON3 protein levels were measured by Western blotting, their mRNA expression was measured by quantitative PCR and arylesterase activity was measured spectrophotometrically. 200 µM lipoic acid caused a significant increase on PON1 and PON3 protein levels and arylesterase activity as compared with control, 10 µM and 40 µM lipoic acid-treated cells. 200 µM lipoic acid also caused a significant decrease on PON1 mRNA expression whereas on a significant increase PON3 mRNA expression as compared with control, 10 µM and 40 µM lipoic acid-treated cells. Our study showed that although lipoic acid up-regulates PON3 but down-regulates PON1 mRNA expression, it increases both PON1 and PON3 protein levels and arylesterase activity in HepG2 cells. We can report that lipoic acid may be useful for preventing atherosclerosis at therapeutic doses.

Inhibition of the NLRP3 inflammasome attenuates foam cell formation of THP-1 macrophages by suppressing ox-LDL uptake and promoting cholesterol efflux.

PubMed

Chen, Liang; Yao, Qiying; Xu, Siwei; Wang, Hongyan; Qu, Peng

2018-01-01

The NOD-like receptor family, pyrin domain-containing protein 3 (NLRP3) inflammasome plays an important role in the development of atherosclerosis. The activated NLRP3 inflammasome has been reported to promote macrophage foam cell formation, but not all studies have obtained the same result, and how NLRP3 inflammasome is involved in the formation of foam cells remains elusive. We used selective NLRP3 inflammasome inhibitors and NLRP3-deficient THP-1 cells to assess the effect of NLRP3 inflammasome inhibition on macrophage foam cell formation, oxidized low-density lipoprotein (ox-LDL) uptake, esterification, and cholesterol efflux, as well as the expression of associated proteins. Inhibition of the NLRP3 inflammasome attenuated foam cell formation, diminished ox-LDL uptake, and promoted cholesterol efflux from THP-1 macrophages. Moreover, it downregulated CD36, acyl coenzyme A: cholesterol acyltransferase-1 and neutral cholesterol ester hydrolase expression; upregulated ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) expression; but had no effect on the expression of scavenger receptor class A and ATP-binding cassette transporter G1. Collectively, our findings show that inhibition of the NLRP3 inflammasome decreases foam cell formation of THP-1 macrophages via suppression of ox-LDL uptake and enhancement of cholesterol efflux, which may be due to downregulation of CD36 expression and upregulation of ABCA1 and SR-BI expression, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

Intestinal Alkaline Phosphatase Regulates Tight Junction Protein Levels

PubMed Central

Liu, Wei; Hu, Dong; Huo, Haizhong; Zhang, Weifeng; Adiliaghdam, Fatemeh; Morrison, Sarah; Ramirez, Juan M; Gul, Sarah S; Hamarneh, Sulaiman R; Hodin, Richard A

2017-01-01

BACKGROUND Intestinal alkaline phosphatase (IAP) plays a pivotal role in maintaining gut health and well-being. Oral supplementation with IAP in mice improves gut barrier function and prevents luminal proinflammatory factors from gaining access to the circulation. In this study, we sought to explore the relationship between IAP and tight junction protein (TJP) expression and function. STUDY DESIGN The effect of IAP deletion on TJP levels was studied in mouse embryonic fibroblasts (MEFs) generated from IAP-knockout and wild type mice. Regulation of TJPs by IAP was assayed in the human colon cancer Caco-2 and T84 cells by overexpressing the human IAP gene. Tight junction protein levels and localization were measured by using RT q-PCR and antibodies targeting the specific TJPs. Finally, the effect of IAP on inflammation-induced intestinal permeability was measured by in vitro trans-well epithelial electrical resistance (TEER). RESULTS Intestinal alkaline phosphatase gene deletion in MEFs resulted in significantly lower levels of ZO-1, ZO-2, and Occludin compared with levels in wild-type control cells; IAP over-expression in Caco-2 and T84 cells resulted in approximate 2-fold increases in the mRNA levels of ZO-1 and ZO-2. The IAP treatment ameliorated lipopolysaccharide-induced increased permeability in the Caco-2 trans-well system. Furthermore, IAP treatment preserved the localization of the ZO-1 and Occludin proteins during inflammation and was also associated with improved epithelial barrier function. CONCLUSIONS Intestinal alkaline phosphatase is a major regulator of gut mucosal permeability and appears to work at least partly through improving TJP levels and localization. These data provide a strong foundation to develop IAP as a novel therapy to maintain gut barrier function. PMID:27106638