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Sample records for adipocyte number insulin

  1. Adipocyte lipolysis and insulin resistance.

    PubMed

    Morigny, Pauline; Houssier, Marianne; Mouisel, Etienne; Langin, Dominique

    2016-06-01

    Obesity-induced insulin resistance is a major risk factor for the development of type 2 diabetes. Basal fat cell lipolysis (i.e., fat cell triacylglycerol breakdown into fatty acids and glycerol in the absence of stimulatory factors) is elevated during obesity and is closely associated with insulin resistance. Inhibition of adipocyte lipolysis may therefore be a promising therapeutic strategy for treating insulin resistance and preventing obesity-associated type 2 diabetes. In this review, we explore the relationship between adipose lipolysis and insulin sensitivity. After providing an overview of the components of fat cell lipolytic machinery, we describe the hypotheses that may support the causality between lipolysis and insulin resistance. Excessive circulating fatty acids may ectopically accumulate in insulin-sensitive tissues and impair insulin action. Increased basal lipolysis may also modify the secretory profile of adipose tissue, influencing whole body insulin sensitivity. Finally, excessive fatty acid release may also worsen adipose tissue inflammation, a well-known parameter contributing to insulin resistance. Partial genetic or pharmacologic inhibition of fat cell lipases in mice as well as short term clinical trials using antilipolytic drugs in humans support the benefit of fat cell lipolysis inhibition on systemic insulin sensitivity and glucose metabolism, which occurs without an increase of fat mass. Modulation of fatty acid fluxes and, putatively, of fat cell secretory pattern may explain the amelioration of insulin sensitivity whereas changes in adipose tissue immune response do not seem involved.

  2. FAK signalling controls insulin sensitivity through regulation of adipocyte survival

    PubMed Central

    Luk, Cynthia T.; Shi, Sally Yu; Cai, Erica P.; Sivasubramaniyam, Tharini; Krishnamurthy, Mansa; Brunt, Jara J.; Schroer, Stephanie A.; Winer, Daniel A.; Woo, Minna

    2017-01-01

    Focal adhesion kinase (FAK) plays a central role in integrin signalling, which regulates growth and survival of tumours. Here we show that FAK protein levels are increased in adipose tissue of insulin-resistant obese mice and humans. Disruption of adipocyte FAK in mice or in 3T3 L1 cells decreases adipocyte survival. Adipocyte-specific FAK knockout mice display impaired adipose tissue expansion and insulin resistance on prolonged metabolic stress from a high-fat diet or when crossed on an obese db/db or ob/ob genetic background. Treatment of these mice with a PPARγ agonist does not restore adiposity or improve insulin sensitivity. In contrast, inhibition of apoptosis, either genetically or pharmacologically, attenuates adipocyte death, restores normal adiposity and improves insulin sensitivity. Together, these results demonstrate that FAK is required for adipocyte survival and maintenance of insulin sensitivity, particularly in the context of adipose tissue expansion as a result of caloric excess. PMID:28165007

  3. Interacting Effects of TSH and Insulin on Human Differentiated Adipocytes.

    PubMed

    Felske, D; Gagnon, A; Sorisky, A

    2015-08-01

    Subclinical hypothyroidism, characterized by an isolated rise in TSH serum levels with normal thyroid function, is a pro-inflammatory state associated with insulin resistance. Adipocytes express TSH receptors, but it is not known if TSH can directly inhibit insulin signaling. Using primary human differentiated adipocytes, we examined the effects of TSH on insulin-stimulated Akt phosphorylation, and whether conventional PKC (cPKC) were involved. The effect of insulin on TSH-stimulated lipolysis was also investigated. TSH inhibited insulin-stimulated Akt phosphorylation in adipocytes by 54%. TSH activated cPKC, and Gö6976, a PKCα and -β1 inhibitor, prevented the inhibitory effect of TSH on the insulin response. Insulin reduced the ability of TSH to activate cPKC and to stimulate lipolysis.Our data reveal novel interactions between TSH and insulin. TSH inhibits insulin-stimulated Akt signaling in a cPKC-dependent fashion, whereas insulin blocks TSH-stimulated cPKC activity and lipolysis. TSH and insulin act on differentiated human adipocytes to modulate their respective intracellular signals.

  4. Macrophage-secreted factors induce adipocyte inflammation and insulin resistance

    SciTech Connect

    Permana, Paska A. . E-mail: Paska.Permana@med.va.gov; Menge, Christopher; Reaven, Peter D.

    2006-03-10

    Macrophage infiltration into adipose tissue increases with obesity, a condition associated with low-grade inflammation and insulin resistance. We investigated the direct effects of macrophage-secreted factors on adipocyte inflammation and insulin resistance. 3T3-L1 adipocytes incubated with media conditioned by RAW264.7 macrophages (RAW-CM) showed dramatically increased transcription of several inflammation-related genes, greater nuclear factor kappa B (NF-{kappa}B) activity, and enhanced binding of U937 monocytes. All of these effects were prevented by co-incubation with pyrrolidinedithiocarbamate, an NF-{kappa}B inhibitor. Adipocytes incubated with RAW-CM also released more non-esterified fatty acids and this increased lipolysis was not suppressed by insulin. In addition, RAW-CM treatment decreased insulin-stimulated glucose uptake in adipocytes. Taken together, these results indicate that macrophage-secreted factors induce inflammatory responses and reduce insulin responsiveness in adipocytes. These effects of macrophage-secreted factors on adipocytes may contribute significantly to the systemic inflammation and insulin resistance associated with obesity.

  5. Thioredoxin reductase 1 suppresses adipocyte differentiation and insulin responsiveness

    PubMed Central

    Peng, Xiaoxiao; Giménez-Cassina, Alfredo; Petrus, Paul; Conrad, Marcus; Rydén, Mikael; Arnér, Elias S. J.

    2016-01-01

    Recently thioredoxin reductase 1 (TrxR1), encoded by Txnrd1, was suggested to modulate glucose and lipid metabolism in mice. Here we discovered that TrxR1 suppresses insulin responsiveness, anabolic metabolism and adipocyte differentiation. Immortalized mouse embryonic fibroblasts (MEFs) lacking Txnrd1 (Txnrd1−/−) displayed increased metabolic flux, glycogen storage, lipogenesis and adipogenesis. This phenotype coincided with upregulated PPARγ expression, promotion of mitotic clonal expansion and downregulation of p27 and p53. Enhanced Akt activation also contributed to augmented adipogenesis and insulin sensitivity. Knockdown of TXNRD1 transcripts accelerated adipocyte differentiation also in human primary preadipocytes. Furthermore, TXNRD1 transcript levels in subcutaneous adipose tissue from 56 women were inversely associated with insulin sensitivity in vivo and lipogenesis in their isolated adipocytes. These results suggest that TrxR1 suppresses anabolic metabolism and adipogenesis by inhibition of intracellular signaling pathways downstream of insulin stimulation. PMID:27346647

  6. Neuropoietin attenuates adipogenesis and induces insulin resistance in adipocytes.

    PubMed

    White, Ursula A; Stewart, William C; Mynatt, Randall L; Stephens, Jacqueline M

    2008-08-15

    Recent findings have implicated gp130 receptor ligands, particularly ciliary neurotrophic factor (CNTF), as potential anti-obesity therapeutics. Neuropoietin (NP) is a recently discovered cytokine in the gp130 family that shares functional and structural features with CNTF and signals via the CNTF receptor tripartite complex comprised of CNTFRalpha, LIF receptor, and gp130. NP plays a role in the development of the nervous system, but the effects of NP on adipocytes have not been previously examined. Because CNTF exerts anti-obesogenic effects in adipocytes and NP shares the same receptor complex, we investigated the effects of NP on adipocyte development and insulin action. Using cultured 3T3-L1 adipocytes, we observed that NP has the ability to block adipogenesis in a dose- and time-dependent manner. We also observed that cultured adipocytes, as well as murine adipose tissue, are highly responsive to acute NP treatment. Rodents injected with NP had a substantial increase in STAT3 tyrosine phosphorylation and ERK 1 and 2 activation. We also observed the induction of SOCS-3 mRNA in 3T3-L1 adipocytes following NP treatment. Unlike CNTF, our studies have revealed that NP also substantially attenuates insulin-stimulated glucose uptake in 3T3-L1 adipocytes. In addition, NP blocks insulin action in adipose tissue in vivo. These observations are supported by data demonstrating that NP impairs insulin signaling via decreased activation of both IRS-1 and Akt. In summary, we have observed that both adipocytes in vitro and in vivo are highly responsive to NP, and this cytokine has the ability to affect insulin signaling in fat cells. These novel observations suggest that NP, unlike CNTF, may not be a viable obesity therapeutic.

  7. Neuropoietin Attenuates Adipogenesis and Induces Insulin Resistance in Adipocytes*

    PubMed Central

    White, Ursula A.; Stewart, William C.; Mynatt, Randall L.; Stephens, Jacqueline M.

    2008-01-01

    Recent findings have implicated gp130 receptor ligands, particularly ciliary neurotrophic factor (CNTF), as potential anti-obesity therapeutics. Neuropoietin (NP) is a recently discovered cytokine in the gp130 family that shares functional and structural features with CNTF and signals via the CNTF receptor tripartite complex comprised of CNTFRα, LIF receptor, and gp130. NP plays a role in the development of the nervous system, but the effects of NP on adipocytes have not been previously examined. Because CNTF exerts anti-obesogenic effects in adipocytes and NP shares the same receptor complex, we investigated the effects of NP on adipocyte development and insulin action. Using cultured 3T3-L1 adipocytes, we observed that NP has the ability to block adipogenesis in a dose- and time-dependent manner. We also observed that cultured adipocytes, as well as murine adipose tissue, are highly responsive to acute NP treatment. Rodents injected with NP had a substantial increase in STAT3 tyrosine phosphorylation and ERK 1 and 2 activation. We also observed the induction of SOCS-3 mRNA in 3T3-L1 adipocytes following NP treatment. Unlike CNTF, our studies have revealed that NP also substantially attenuates insulin-stimulated glucose uptake in 3T3-L1 adipocytes. In addition, NP blocks insulin action in adipose tissue in vivo. These observations are supported by data demonstrating that NP impairs insulin signaling via decreased activation of both IRS-1 and Akt. In summary, we have observed that both adipocytes in vitro and in vivo are highly responsive to NP, and this cytokine has the ability to affect insulin signaling in fat cells. These novel observations suggest that NP, unlike CNTF, may not be a viable obesity therapeutic. PMID:18562323

  8. Adipocyte SIRT1 controls systemic insulin sensitivity by modulating macrophages in adipose tissue.

    PubMed

    Hui, Xiaoyan; Zhang, Mingliang; Gu, Ping; Li, Kuai; Gao, Yuan; Wu, Donghai; Wang, Yu; Xu, Aimin

    2017-03-07

    Adipose tissue inflammation, characterized by augmented infiltration and altered polarization of macrophages, contributes to insulin resistance and its associated metabolic diseases. The NAD(+)-dependent deacetylase SIRT1 serves as a guardian against metabolic disorders in multiple tissues. To dissect the roles of SIRT1 in adipose tissues, metabolic phenotypes of mice with selective ablation of SIRT1 in adipocytes and myeloid cells were monitored. Compared to myeloid-specific SIRT1 depletion, mice with adipocyte-selective deletion of SIRT1 are more susceptible to diet-induced insulin resistance. The phenotypic changes in adipocyte-selective SIRT1 knockout mice are associated with an increased number of adipose-resident macrophages and their polarization toward the pro-inflammatory M1 subtype. Mechanistically, SIRT1 in adipocytes modulates expression and secretion of several adipokines, including adiponectin, MCP-1, and interleukin 4, which in turn alters recruitment and polarization of the macrophages in adipose tissues. In adipocytes, SIRT1 deacetylates the transcription factor NFATc1 and thereby enhances the binding of NFATc1 to the Il4 gene promoter. These findings suggest that adipocyte SIRT1 controls systemic glucose homeostasis and insulin sensitivity via the cross talk with adipose-resident macrophages.

  9. Insulin binding and glucose uptake of adipocytes in rats adapted to hypergravitational force

    NASA Technical Reports Server (NTRS)

    Kobayashi, M.; Mondon, C. E.; Oyama, J.

    1980-01-01

    Rats were exposed to 4.15 g for 1 yr and weight and age matched, and lean noncentrifuged rats were used as control groups. Rats exposed to chronic hypergravity (hypergravic rats) were found to show lower ambient insulin levels, greater food intake with smaller body weight gain, and decreased size of isolated adipocytes. The ability of adipocytes from the hypergravic rats to bind insulin was increased. With Scatchard analysis, both number and affinity of receptors were increased. In contrast to the increased binding, glucose transport was found to be decreased in adipocytes from these animals. However, when the data were expressed as a percentage of maximal effect, the half maximal insulin effect for both the hypergravic and lean control groups was produced at an insulin concentration of 0.23 + or - 0.02 ng/ml, which was lower than the insulin concentration of 0.31 + or - 0.02 ng/ml for the weight-matched control group (P less than 0.05). This increased insulin sensitivity in the hypergravic group was accounted for by an increased number of receptors.

  10. Body fat mass and the proportion of very large adipocytes in pregnant women are associated with gestational insulin resistance

    PubMed Central

    Svensson, H; Wetterling, L; Bosaeus, M; Odén, B; Odén, A; Jennische, E; Edén, S; Holmäng, A; Lönn, M

    2016-01-01

    Background/Objectives: Pregnancy is accompanied by fat gain and insulin resistance. Changes in adipose tissue morphology and function during pregnancy and factors contributing to gestational insulin resistance are incompletely known. We sought to characterize adipose tissue in trimesters 1 and 3 (T1/T3) in normal weight (NW) and obese pregnant women, and identify adipose tissue-related factors associated with gestational insulin resistance. Subjects/Methods: Twenty-two NW and 11 obese women were recruited early in pregnancy for the Pregnancy Obesity Nutrition and Child Health study. Examinations and sampling of blood and abdominal adipose tissue were performed longitudinally in T1/T3 to determine fat mass (air-displacement plethysmography); insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR); size, number and lipolytic activity of adipocytes; and adipokine release and density of immune cells and blood vessels in adipose tissue. Results: Fat mass and HOMA-IR increased similarly between T1 and T3 in the groups; all remained normoglycemic. Adipocyte size increased in NW women. Adipocyte number was not influenced, but proportions of small and large adipocytes changed oppositely in the groups. Lipolytic activity and circulating adipocyte fatty acid-binding protein increased in both groups. Adiponectin release was reduced in NW women. Fat mass and the proportion of very large adipocytes were most strongly associated with T3 HOMA-IR by multivariable linear regression (R2=0.751, P<0.001). Conclusions: During pregnancy, adipose tissue morphology and function change comprehensively. NW women accumulated fat in existing adipocytes, accompanied by reduced adiponectin release. In comparison with the NW group, obese women had signs of adipocyte recruitment and maintained adiponectin levels. Body fat and large adipocytes may contribute significantly to gestational insulin resistance. PMID:26563815

  11. CDK4 is an essential insulin effector in adipocytes

    PubMed Central

    Lagarrigue, Sylviane; Lopez-Mejia, Isabel C.; Denechaud, Pierre-Damien; Escoté, Xavier; Castillo-Armengol, Judit; Jimenez, Veronica; Chavey, Carine; Giralt, Albert; Lai, Qiuwen; Zhang, Lianjun; Martinez-Carreres, Laia; Delacuisine, Brigitte; Annicotte, Jean-Sébastien; Blanchet, Emilie; Huré, Sébastien; Abella, Anna; Tinahones, Francisco J.; Vendrell, Joan; Dubus, Pierre; Bosch, Fatima; Kahn, C. Ronald; Fajas, Lluis

    2015-01-01

    Insulin resistance is a fundamental pathogenic factor that characterizes various metabolic disorders, including obesity and type 2 diabetes. Adipose tissue contributes to the development of obesity-related insulin resistance through increased release of fatty acids, altered adipokine secretion, and/or macrophage infiltration and cytokine release. Here, we aimed to analyze the participation of the cyclin-dependent kinase 4 (CDK4) in adipose tissue biology. We determined that white adipose tissue (WAT) from CDK4-deficient mice exhibits impaired lipogenesis and increased lipolysis. Conversely, lipolysis was decreased and lipogenesis was increased in mice expressing a mutant hyperactive form of CDK4 (CDK4R24C). A global kinome analysis of CDK4-deficient mice following insulin stimulation revealed that insulin signaling is impaired in these animals. We determined that insulin activates the CCND3-CDK4 complex, which in turn phosphorylates insulin receptor substrate 2 (IRS2) at serine 388, thereby creating a positive feedback loop that maintains adipocyte insulin signaling. Furthermore, we found that CCND3 expression and IRS2 serine 388 phosphorylation are increased in human obese subjects. Together, our results demonstrate that CDK4 is a major regulator of insulin signaling in WAT. PMID:26657864

  12. Effect of a high glucose diet on insulin binding and insulin action in rat adipocytes. A longitudinal study.

    PubMed

    Oka, Y; Akanuma, Y; Kasuga, M; Kosaka, K

    1980-11-01

    To elucidate the mechanisms whereby changes in dietary composition affect the action of insulin on glucose metabolism, insulin binding and glucose uptake and oxidation have been studied in epididymal fat pad adipocytes from rats fed high glucose diets for 5 and 10 days. After 5 days, insulin binding was increased, the mainly to an increased number of receptors (3.4 X 10(5) vs. 2.4 X 10(5) sites per cell) in spite of increased plasma insulin levels (3.0 +/- 0.2 vs. 2.1 +/- 0.1 microgram/l; P < 0.05). The maximal response of glucose oxidation to insulin was increased (925 +/- 55 vs. 510 +/- 58 n moles/2 X 10(5) cells/2h; P < 0.01) and the dose-response curve of glucose uptake was shifted to the left. After 10 days, receptor number decreased to the control level and the effect of insulin on glucose uptake and oxidation (% basal) were similar to controls. Thus, in the early stage of high glucose feeding, insulin receptor number, and insulin sensitivity of glucose uptake, and insulin responsiveness of glucose oxidation were increased.

  13. SORLA facilitates insulin receptor signaling in adipocytes and exacerbates obesity

    PubMed Central

    Schmidt, Vanessa; Schulz, Nadja; Yan, Xin; Schürmann, Annette; Kempa, Stefan; Kern, Matthias; Blüher, Matthias; Poy, Matthew N.

    2016-01-01

    In humans, genetic variation of sortilin-related receptor, L(DLR class) A repeats containing (SORL1), which encodes the intracellular sorting receptor SORLA, is a major genetic risk factor for familial and sporadic forms of Alzheimer’s disease. Recent GWAS analysis has also associated SORL1 with obesity in humans and in mouse models, suggesting that this receptor may play a role in regulating metabolism. Here, using mouse models with genetic loss or tissue-specific overexpression of SORLA as well as data from obese human subjects, we observed a gene-dosage effect that links SORLA expression to obesity and glucose tolerance. Overexpression of human SORLA in murine adipose tissue blocked hydrolysis of triacylglycerides and caused excessive adiposity. In contrast, Sorl1 gene inactivation in mice accelerated breakdown of triacylglycerides in adipocytes and protected animals from diet-induced obesity. We then identified the underlying molecular mechanism whereby SORLA promotes insulin-induced suppression of lipolysis in adipocytes. Specifically, we determined that SORLA acts as a sorting factor for the insulin receptor (IR) that redirects internalized receptor molecules from endosomes to the plasma membrane, thereby enhancing IR surface expression and strengthening insulin signal reception in target cells. Our findings provide a molecular mechanism for the association of SORL1 with human obesity and confirm a genetic link between neurodegeneration and metabolism that converges on the receptor SORLA. PMID:27322061

  14. Fat intake leads to differential response of rat adipocytes to glucose, insulin and ascorbic acid.

    PubMed

    Garcia-Diaz, Diego F; Campion, Javier; Arellano, Arianna V; Milagro, Fermin I; Moreno-Aliaga, Maria J; Martinez, J Alfredo

    2012-04-01

    Antioxidant-based treatments have emerged as novel and interesting approaches to counteract fat accumulation in obesity and associated metabolic disturbances. Adipocytes from rats that were fed on chow or high-fat diet (HFD) for 50 d were isolated (primary adipocytes) and incubated (72 h) on low (LG; 5.6 mmol/L) or high (HG; 25 mmol/L) glucose levels, in the presence or absence of 1.6 nmol/L insulin and 200 μmol/L vitamin C (VC). Adipocytes from HFD-fed animals presented lower insulin-induced glucose uptake, lower lactate and glycerol release, and lower insulin-induced secretion of some adipokines as compared with controls. HG treatment restored the blunted response to insulin regarding apelin secretion in adipocytes from HFD-fed rats. VC treatment inhibited the levels of nearly all variables, irrespective of the adipocytes' dietary origin. The HG treatment reduced adipocyte viability, and VC protected from this toxic effect, although more drastically in control adipocytes. Summing up, in vivo chow or HFD intake determines a differential response to insulin and glucose treatments that appears to be dependent on the insulin-resistance status of the adipocytes, while VC modifies some responses from adipocytes independently of the previous dietary intake of the animals.

  15. Chronic hyperinsulinemia reduces insulin sensitivity and metabolic functions of brown adipocyte.

    PubMed

    Rajan, Sujith; Shankar, Kripa; Beg, Muheeb; Varshney, Salil; Gupta, Abhishek; Srivastava, Ankita; Kumar, Durgesh; Mishra, Raj K; Hussain, Zakir; Gayen, Jiaur R; Gaikwad, Anil N

    2016-09-01

    The growing pandemics of diabetes have become a real threat to world economy. Hyperinsulinemia and insulin resistance are closely associated with the pathophysiology of type 2 diabetes. In pretext of brown adipocytes being considered as the therapeutic strategy for the treatment of obesity and insulin resistance, we have tried to understand the effect of hyperinsulinemia on brown adipocyte function. We here with for the first time report that hyperinsulinemia-induced insulin resistance in brown adipocyte is also accompanied with reduced insulin sensitivity and brown adipocyte characteristics. CI treatment decreased expression of brown adipocyte-specific markers (such as PRDM16, PGC1α, and UCP1) and mitochondrial content as well as activity. CI-treated brown adipocytes showed drastic decrease in oxygen consumption rate (OCR) and spare respiratory capacity. Morphological study indicates increased accumulation of lipid droplets in CI-treated brown adipocytes. We have further validated these findings in vivo in C57BL/6 mice implanted with mini-osmotic insulin pump for 8weeks. CI treatment in mice leads to increased body weight gain, fat mass and impaired glucose intolerance with reduced energy expenditure and insulin sensitivity. CI-treated mice showed decreased BAT characteristics and function. We also observed increased inflammation and ER stress markers in BAT of CI-treated animals. The above results conclude that hyperinsulinemia has deleterious effect on brown adipocyte function, making it susceptible to insulin resistance. Thus, the above findings have greater implication in designing approaches for the treatment of insulin resistance and diabetes via recruitment of brown adipocytes.

  16. Endurance exercise training increases insulin responsiveness in isolated adipocytes through IRS/PI3-kinase/Akt pathway.

    PubMed

    Peres, Sidney B; de Moraes, Solange M Franzói; Costa, Cecilia E M; Brito, Luciana C; Takada, Julie; Andreotti, Sandra; Machado, Magaly A; Alonso-Vale, Maria Isabel C; Borges-Silva, Cristina N; Lima, Fabio B

    2005-03-01

    Endurance exercise training promotes important metabolic adaptations, and the adipose tissue is particularly affected. The aim of this study was to investigate how endurance exercise training modulates some aspects of insulin action in isolated adipocytes and in intact adipose tissue. Male Wistar rats were submitted to daily treadmill running (1 h/day) for 7 wk. Sedentary age-matched rats were used as controls. Final body weight, body weight gain, and epididymal fat pad weight did not show any statistical differences between groups. Adipocytes from trained rats were smaller than those from sedentary rats (205 +/- 16.8 vs. 286 +/- 26.4 pl; P < 0.05). Trained rats showed decreased plasma glucose (4.9 +/- 0.13 vs. 5.3 +/- 0.07 mM; P < 0.05) and insulin levels (0.24 +/- 0.012 vs. 0.41 +/- 0.049 mM; P < 0.05) and increased insulin-stimulated glucose uptake (23.1 +/- 3.1 vs. 12.1 +/- 2.9 pmol/cm(2); P < 0.05) compared with sedentary rats. The number of insulin receptors and the insulin-induced tyrosine phosphorylation of insulin receptor-beta subunit did not change between groups. Insulin-induced tyrosine phosphorylation insulin receptor substrates (IRS)-1 and -2 increased significantly (1.57- and 2.38-fold, respectively) in trained rats. Insulin-induced IRS-1/phosphatidylinositol 3 (PI3)-kinase (but not IRS-2/PI3-kinase) association and serine Akt phosphorylation also increased (2.06- and 3.15-fold, respectively) after training. The protein content of insulin receptor-beta subunit, IRS-1 and -2, did not differ between groups. Taken together, these data support the hypothesis that the increased adipocyte responsiveness to insulin observed after endurance exercise training is modulated by IRS/PI3-kinase/Akt pathway.

  17. Proteasome Dysfunction Associated to Oxidative Stress and Proteotoxicity in Adipocytes Compromises Insulin Sensitivity in Human Obesity

    PubMed Central

    Díaz-Ruiz, Alberto; Guzmán-Ruiz, Rocío; Moreno, Natalia R.; García-Rios, Antonio; Delgado-Casado, Nieves; Membrives, Antonio; Túnez, Isaac; El Bekay, Rajaa; Fernández-Real, José M.; Tovar, Sulay; Diéguez, Carlos; Tinahones, Francisco J.; Vázquez-Martínez, Rafael; López-Miranda, José

    2015-01-01

    Abstract Aims: Obesity is characterized by a low-grade systemic inflammatory state and adipose tissue (AT) dysfunction, which predispose individuals to the development of insulin resistance (IR) and metabolic disease. However, a subset of obese individuals, referred to as metabolically healthy obese (MHO) individuals, are protected from obesity-associated metabolic abnormalities. Here, we aim at identifying molecular factors and pathways in adipocytes that are responsible for the progression from the insulin-sensitive to the insulin-resistant, metabolically unhealthy obese (MUHO) phenotype. Results: Proteomic analysis of paired samples of adipocytes from subcutaneous (SC) and omental (OM) human AT revealed that both types of cells are altered in the MUHO state. Specifically, the glutathione redox cycle and other antioxidant defense systems as well as the protein-folding machinery were dysregulated and endoplasmic reticulum stress was increased in adipocytes from IR subjects. Moreover, proteasome activity was also compromised in adipocytes of MUHO individuals, which was associated with enhanced accumulation of oxidized and ubiquitinated proteins in these cells. Proteasome activity was also impaired in adipocytes of diet-induced obese mice and in 3T3-L1 adipocytes exposed to palmitate. In line with these data, proteasome inhibition significantly impaired insulin signaling in 3T3-L1 adipocytes. Innovation: This study provides the first evidence of the occurrence of protein homeostasis deregulation in adipocytes in human obesity, which, together with oxidative damage, interferes with insulin signaling in these cells. Conclusion: Our results suggest that proteasomal dysfunction and impaired proteostasis in adipocytes, resulting from protein oxidation and/or misfolding, constitute major pathogenic mechanisms in the development of IR in obesity. Antioxid. Redox Signal. 23, 597–612. PMID:25714483

  18. PPAR gamma mediates high-fat diet-induced adipocyte hypertrophy and insulin resistance.

    PubMed

    Kubota, N; Terauchi, Y; Miki, H; Tamemoto, H; Yamauchi, T; Komeda, K; Satoh, S; Nakano, R; Ishii, C; Sugiyama, T; Eto, K; Tsubamoto, Y; Okuno, A; Murakami, K; Sekihara, H; Hasegawa, G; Naito, M; Toyoshima, Y; Tanaka, S; Shiota, K; Kitamura, T; Fujita, T; Ezaki, O; Aizawa, S; Kadowaki, T

    1999-10-01

    Agonist-induced activation of peroxisome proliferator-activated receptor gamma (PPAR gamma) is known to cause adipocyte differentiation and insulin sensitivity. The biological role of PPAR gamma was investigated by gene targeting. Homozygous PPAR gamma-deficient embryos died at 10.5-11.5 dpc due to placental dysfunction. Quite unexpectedly, heterozygous PPAR gamma-deficient mice were protected from the development of insulin resistance due to adipocyte hypertrophy under a high-fat diet. These phenotypes were abrogated by PPAR gamma agonist treatment. Heterozygous PPAR gamma-deficient mice showed overexpression and hypersecretion of leptin despite the smaller size of adipocytes and decreased fat mass, which may explain these phenotypes at least in part. This study reveals a hitherto unpredicted role for PPAR gamma in high-fat diet-induced obesity due to adipocyte hypertrophy and insulin resistance, which requires both alleles of PPAR gamma.

  19. Expression of a mutant IRS inhibits metabolic and mitogenic signalling of insulin in human adipocytes.

    PubMed

    Stenkula, Karin G; Said, Lilian; Karlsson, Margareta; Thorn, Hans; Kjølhede, Preben; Gustavsson, Johanna; Söderström, Mats; Strålfors, Peter; Nystrom, Fredrik H

    2004-06-30

    Adipose tissue is a primary target of insulin, but knowledge about insulin signalling in human adipocytes is limited. We developed an electroporation technique for transfection of primary human adipocytes with a transfection efficiency of 15% +/- 5 (mean +/- S.D.). Human adipocytes were co-transfected with a mutant of IRS-3 (all four potential PI3-kinase binding motifs mutated: IRS-3F4) and HA-tagged protein kinase B (HA-PKB/Akt). HA-PKB/Akt was immunoprecipitated from cell lysates with anti-HA antibodies, resolved with SDS-PAGE, and immunoblotted with phospho-specific antibodies. We found that IRS-3F4 blocked insulin stimulation of HA-PKB/Akt phosphorylation and in further analyses also translocation of recombinant HA-tagged glucose transporter to the plasma membrane. IRS-3F4 also blocked insulin-induced activation of the transcription factor Elk-1. Our results demonstrate the critical importance of IRS for metabolic as well as mitogenic signalling by insulin. This method for transfection of primary human adipocytes will be useful for studying insulin signalling in human adipocytes with molecular biological techniques.

  20. Expression of Caveolin 1 is enhanced by DNA demethylation during adipocyte differentiation. status of insulin signaling.

    PubMed

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Milagro, Fermín Ignacio; Martínez, José Alfredo; de Miguel, Carlos

    2014-01-01

    Caveolin 1 (Cav-1) is an essential constituent of adipocyte caveolae which binds the beta subunit of the insulin receptor (IR) and is implicated in the regulation of insulin signaling. We have found that, during adipocyte differentiation of 3T3-L1 cells the promoter, exon 1 and first intron of the Cav-1 gene undergo a demethylation process that is accompanied by a strong induction of Cav-1 expression, indicating that epigenetic mechanisms must have a pivotal role in this differentiation process. Furthermore, IR, PKB-Akt and Glut-4 expression are also increased during the differentiation process suggesting a coordinated regulation with Cav-1. Activation of Cav-1 protein by phosphorylation arises during the differentiation process, yet in fully mature adipocytes insulin is no longer able to significantly increase Cav-1 phosphorylation. However, these long-term differentiated cells are still able to respond adequately to insulin, increasing IR and PKB-Akt phosphorylation and glucose uptake. The activation of Cav-1 during the adipocyte differentiation process could facilitate the maintenance of insulin sensitivity by these fully mature adipocytes isolated from additional external stimuli. However, under the influence of physiological conditions associated to obesity, such as chronic inflammation and hypoxia, insulin sensitivity would finally be compromised.

  1. Expression of Caveolin 1 Is Enhanced by DNA Demethylation during Adipocyte Differentiation. Status of Insulin Signaling

    PubMed Central

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Milagro, Fermín Ignacio; Martínez, José Alfredo; de Miguel, Carlos

    2014-01-01

    Caveolin 1 (Cav-1) is an essential constituent of adipocyte caveolae which binds the beta subunit of the insulin receptor (IR) and is implicated in the regulation of insulin signaling. We have found that, during adipocyte differentiation of 3T3-L1 cells the promoter, exon 1 and first intron of the Cav-1 gene undergo a demethylation process that is accompanied by a strong induction of Cav-1 expression, indicating that epigenetic mechanisms must have a pivotal role in this differentiation process. Furthermore, IR, PKB-Akt and Glut-4 expression are also increased during the differentiation process suggesting a coordinated regulation with Cav-1. Activation of Cav-1 protein by phosphorylation arises during the differentiation process, yet in fully mature adipocytes insulin is no longer able to significantly increase Cav-1 phosphorylation. However, these long-term differentiated cells are still able to respond adequately to insulin, increasing IR and PKB-Akt phosphorylation and glucose uptake. The activation of Cav-1 during the adipocyte differentiation process could facilitate the maintenance of insulin sensitivity by these fully mature adipocytes isolated from additional external stimuli. However, under the influence of physiological conditions associated to obesity, such as chronic inflammation and hypoxia, insulin sensitivity would finally be compromised. PMID:24751908

  2. Lipid droplets hypertrophy: a crucial determining factor in insulin regulation by adipocytes

    NASA Astrophysics Data System (ADS)

    Sanjabi, Bahram; Dashty, Monireh; Özcan, Behiye; Akbarkhanzadeh, Vishtaseb; Rahimi, Mehran; Vinciguerra, Manlio; van Rooij, Felix; Al-Lahham, Saad; Sheedfar, Fareeba; van Kooten, Theo G.; Spek, C. Arnold; Rowshani, Ajda T.; van der Want, Johannes; Klaassen, Rene; Sijbrands, Eric; Peppelenbosch, Maikel P.; Rezaee, Farhad

    2015-03-01

    Lipid droplets (LDs) hypertrophy in adipocytes is the main cause of energy metabolic system dysfunction, obesity and its afflictions such as T2D. However, the role of adipocytes in linking energy metabolic disorders with insulin regulation is unknown in humans. Human adipocytes constitutively synthesize and secrete insulin, which is biologically functional. Insulin concentrations and release are fat mass- and LDs-dependent respectively. Fat reduction mediated by bariatric surgery repairs obesity-associated T2D. The expression of genes, like PCSK1 (proinsulin conversion enzyme), GCG (Glucagon), GPLD1, CD38 and NNAT, involved in insulin regulation/release were differentially expressed in pancreas and adipose tissue (AT). INS (insulin) and GCG expression reduced in human AT-T2D as compared to AT-control, but remained unchanged in pancreas in either state. Insulin levels (mRNA/protein) were higher in AT derived from prediabetes BB rats with destructed pancreatic β-cells and controls than pancreas derived from the same rats respectively. Insulin expression in 10 human primary cell types including adipocytes and macrophages is an evidence for extrapancreatic insulin-producing cells. The data suggest a crosstalk between AT and pancreas to fine-tune energy metabolic system or may minimize the metabolic damage during diabetes. This study opens new avenues towards T2D therapy with a great impact on public health.

  3. Lipid droplets hypertrophy: a crucial determining factor in insulin regulation by adipocytes

    PubMed Central

    Sanjabi, Bahram; Dashty, Monireh; Özcan, Behiye; Akbarkhanzadeh, Vishtaseb; Rahimi, Mehran; Vinciguerra, Manlio; van Rooij, Felix; Al-Lahham, Saad; Sheedfar, Fareeba; van Kooten, Theo G.; Spek, C. Arnold; Rowshani, Ajda T.; van der Want, Johannes; Klaassen, Rene; Sijbrands, Eric; Peppelenbosch, Maikel P.; Rezaee, Farhad

    2015-01-01

    Lipid droplets (LDs) hypertrophy in adipocytes is the main cause of energy metabolic system dysfunction, obesity and its afflictions such as T2D. However, the role of adipocytes in linking energy metabolic disorders with insulin regulation is unknown in humans. Human adipocytes constitutively synthesize and secrete insulin, which is biologically functional. Insulin concentrations and release are fat mass- and LDs-dependent respectively. Fat reduction mediated by bariatric surgery repairs obesity-associated T2D. The expression of genes, like PCSK1 (proinsulin conversion enzyme), GCG (Glucagon), GPLD1, CD38 and NNAT, involved in insulin regulation/release were differentially expressed in pancreas and adipose tissue (AT). INS (insulin) and GCG expression reduced in human AT-T2D as compared to AT-control, but remained unchanged in pancreas in either state. Insulin levels (mRNA/protein) were higher in AT derived from prediabetes BB rats with destructed pancreatic β-cells and controls than pancreas derived from the same rats respectively. Insulin expression in 10 human primary cell types including adipocytes and macrophages is an evidence for extrapancreatic insulin-producing cells. The data suggest a crosstalk between AT and pancreas to fine-tune energy metabolic system or may minimize the metabolic damage during diabetes. This study opens new avenues towards T2D therapy with a great impact on public health. PMID:25743104

  4. The effect of prolactin and relaxin on insulin binding by adipocytes from pregnant women.

    PubMed

    Jarrett JC2nd; Ballejo, G; Saleem, T H; Tsibris, J C; Spellacy, W N

    1984-06-01

    The effects of prolactin and relaxin on insulin binding by isolated human adipocytes from women at term gestation were studied in vitro. It was found that prolactin decreases, and relaxin increases, insulin binding to the adipocytes. Both changes appear to be due to alterations in the affinity of the insulin receptors. These effects seem to be mediated through specific prolactin and relaxin receptors of the adipocyte and require the presence of an intact cellular cytoskeleton. This suggests that one hormone, for example, prolactin, can interact with its own specific receptor and thereby after the affinity of a heterologous receptor for its hormone (insulin). Heterologous hormone-receptor complex interactions ("cross-talk") may be widespread and could represent a fundamental mechanism in the functioning of the endocrine system.

  5. Honokiol enhances adipocyte differentiation by potentiating insulin signaling in 3T3-L1 preadipocytes.

    PubMed

    Choi, Sun-Sil; Cha, Byung-Yoon; Iida, Kagami; Sato, Masako; Lee, Young-Sil; Teruya, Toshiaki; Yonezawa, Takayuki; Nagai, Kazuo; Woo, Je-Tae

    2011-07-01

    Adipose tissue plays an essential role in energy homeostasis as a metabolic and endocrine organ. Accordingly, adipocytes are emerging as a major drug target for obesity and obesity-mediated metabolic syndrome. Dysfunction of enlarged adipocytes in obesity is involved in obesity-mediated metabolic syndrome. Adipocytokines, such as adiponectin released from small adipocytes, are able to prevent these disorders. In this study, we found that honokiol, an ingredient of Magnolia officinalis used in traditional Chinese and Japanese medicines, enhanced adipocyte differentiation in 3T3-L1 preadipocytes. Oil Red O staining showed that treatment with honokiol in the presence of insulin dose-dependently increased lipid accumulation in 3T3-L1 preadipoyctes although its activity was weak compared with rosiglitazone. During adipocyte differentiation, the expression of peroxisome proliferator-activated receptor γ2 (PPARγ2) mRNA and PPARγ target genes such as adipocyte protein 2 (aP2), adiponectin, and GLUT4 was induced by treatment with 10 μM honokiol. However, honokiol failed to show direct binding to the PPARγ ligand-binding domain in vitro. In preadipocytes, treatment with honokiol in the presence of insulin increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 protein and Akt protein, early insulin signaling pathways related to adipocyte differentiation, compared with insulin-only treatment. Taken together, our results suggest that honokiol promotes adipocyte differentiation through increased expression of PPARγ2 mRNA and potentiation of insulin signaling pathways such as the Ras/ERK1/2 and phosphoinositide-3-kinase (PI3K)/Akt signaling pathways.

  6. Adipocyte JAK2 mediates growth hormone–induced hepatic insulin resistance

    PubMed Central

    Corbit, Kevin C.; Camporez, João Paulo G.; Tran, Jennifer L.; Wilson, Camella G.; Lowe, Dylan A.; Nordstrom, Sarah M.; Ganeshan, Kirthana; Perry, Rachel J.; Weiss, Ethan J.

    2017-01-01

    For nearly 100 years, growth hormone (GH) has been known to affect insulin sensitivity and risk of diabetes. However, the tissue governing the effects of GH signaling on insulin and glucose homeostasis remains unknown. Excess GH reduces fat mass and insulin sensitivity. Conversely, GH insensitivity (GHI) is associated with increased adiposity, augmented insulin sensitivity, and protection from diabetes. Here, we induce adipocyte-specific GHI through conditional deletion of Jak2 (JAK2A), an obligate transducer of GH signaling. Similar to whole-body GHI, JAK2A mice had increased adiposity and extreme insulin sensitivity. Loss of adipocyte Jak2 augmented hepatic insulin sensitivity and conferred resistance to diet-induced metabolic stress without overt changes in circulating fatty acids. While GH injections induced hepatic insulin resistance in control mice, the diabetogenic action was absent in JAK2A mice. Adipocyte GH signaling directly impinged on both adipose and hepatic insulin signal transduction. Collectively, our results show that adipose tissue governs the effects of GH on insulin and glucose homeostasis. Further, we show that JAK2 mediates liver insulin sensitivity via an extrahepatic, adipose tissue–dependent mechanism. PMID:28194444

  7. Rapamycin negatively impacts insulin signaling, glucose uptake and uncoupling protein-1 in brown adipocytes.

    PubMed

    García-Casarrubios, Ester; de Moura, Carlos; Arroba, Ana I; Pescador, Nuria; Calderon-Dominguez, María; Garcia, Laura; Herrero, Laura; Serra, Dolors; Cadenas, Susana; Reis, Flavio; Carvalho, Eugenia; Obregon, Maria Jesus; Valverde, Ángela M

    2016-12-01

    New onset diabetes after transplantation (NODAT) is a metabolic disorder that affects 40% of patients on immunosuppressive agent (IA) treatment, such as rapamycin (also known as sirolimus). IAs negatively modulate insulin action in peripheral tissues including skeletal muscle, liver and white fat. However, the effects of IAs on insulin sensitivity and thermogenesis in brown adipose tissue (BAT) have not been investigated. We have analyzed the impact of rapamycin on insulin signaling, thermogenic gene-expression and mitochondrial respiration in BAT. Treatment of brown adipocytes with rapamycin for 16h significantly decreased insulin receptor substrate 1 (IRS1) protein expression and insulin-mediated protein kinase B (Akt) phosphorylation. Consequently, both insulin-induced glucose transporter 4 (GLUT4) translocation to the plasma membrane and glucose uptake were decreased. Early activation of the N-terminal Janus activated kinase (JNK) was also observed, thereby increasing IRS1 Ser 307 phosphorylation. These effects of rapamycin on insulin signaling in brown adipocytes were partly prevented by a JNK inhibitor. In vivo treatment of rats with rapamycin for three weeks abolished insulin-mediated Akt phosphorylation in BAT. Rapamycin also inhibited norepinephrine (NE)-induced lipolysis, the expression of peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) and uncoupling protein (UCP)-1 in brown adipocytes. Importantly, basal mitochondrial respiration, proton leak and maximal respiratory capacity were significantly decreased in brown adipocytes treated with rapamycin. In conclusion, we demonstrate, for the first time the important role of brown adipocytes as target cells of rapamycin, suggesting that insulin resistance in BAT might play a major role in NODAT development.

  8. 11β-Hydroxysteroid Dehydrogenase Type 1(11β-HSD1) mediates insulin resistance through JNK activation in adipocytes

    PubMed Central

    Peng, Kesong; Pan, Yong; Li, Jieli; Khan, Zia; Fan, Mendi; Yin, Haimin; Tong, Chao; Zhao, Yunjie; Liang, Guang; Zheng, Chao

    2016-01-01

    Glucocorticoids are used to treat a number of human diseases but often lead to insulin resistance and metabolic syndrome. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a key enzyme that catalyzes the intracellular conversion of cortisone to physiologically active cortisol. Despite the known role of 11β-HSD1 and active glucocorticoid in causing insulin resistance, the molecular mechanisms by which insulin resistance is induced remain elusive. The aim of this study is to identify these mechanisms in high fat diet (HFD) experimental models. Mice on a HFD were treated with 11β-HSD1 inhibitor as well as a JNK inhibitor. We then treated 3T3-L1-derived adipocytes with prednisone, a synthetic glucocorticoid, and cells with 11β-HSD1 overexpression to study insulin resistance. Our results show that 11β-HSD1 and JNK inhibition mitigated insulin resistance in HFD mice. Prednisone stimulation or overexpression of 11β-HSD1 also caused JNK activation in cultured adipocytes. Inhibition of 11β-HSD1 blocked the activation of JNK in adipose tissue of HFD mice as well as in cultured adipocytes. Furthermore, prednisone significantly impaired the insulin signaling pathway, and these effects were reversed by 11β-HSD1 and JNK inhibition. Our study demonstrates that glucocorticoid-induced insulin resistance was dependent on 11β-HSD1, resulting in the critical activation of JNK signaling in adipocytes. PMID:27841334

  9. St. John's Wort inhibits insulin signaling in murine and human adipocytes.

    PubMed

    Richard, Allison J; Amini, Zhaleh J; Ribnicky, David M; Stephens, Jacqueline M

    2012-04-01

    Adipocytes are insulin-sensitive cells that play a major role in energy homeostasis. Obesity is the primary disease of fat cells and a major risk factor for the development of Type 2 diabetes, cardiovascular disease, and metabolic syndrome. The use of botanicals in the treatment of metabolic diseases is an emerging area of research. In previous studies, we screened over 425 botanical extracts for their ability to modulate adipogenesis and insulin sensitivity. We identified St. John's Wort (SJW) extracts as inhibitors of adipogenesis of 3T3-L1 cells and demonstrated that these extracts also inhibited insulin-sensitive glucose uptake in mature fat cells. In these follow-up studies we have further characterized the effects of SJW on insulin action in both murine and human fat cells. We have shown that SJW also attenuates insulin-sensitive glucose uptake in human adipocytes. Moreover, SJW inhibits IRS-1 tyrosine phosphorylation in both murine and human fat cells. Botanical extracts are complex mixtures. Many bioactive compounds have been identified in SJW, including hypericin (HI) and hyperforin (HF). We have examined the ability of HI and HF, purified from SJW, to modulate adipocyte development and insulin action in mature adipocytes. Our novel studies indicate that the profound effects of SJW on adipogenesis, IRS-1 activation, and insulin-stimulated glucose uptake are not mediated by HI and/or HF. Nonetheless, we propose that extracts of SJW may contribute to adipocyte related diseases by limiting differentiation of preadipocytes and significantly inducing insulin resistance in mature fat cells.

  10. Insulin signaling in type 2 diabetes: experimental and modeling analyses reveal mechanisms of insulin resistance in human adipocytes.

    PubMed

    Brännmark, Cecilia; Nyman, Elin; Fagerholm, Siri; Bergenholm, Linnéa; Ekstrand, Eva-Maria; Cedersund, Gunnar; Strålfors, Peter

    2013-04-05

    Type 2 diabetes originates in an expanding adipose tissue that for unknown reasons becomes insulin resistant. Insulin resistance reflects impairments in insulin signaling, but mechanisms involved are unclear because current research is fragmented. We report a systems level mechanistic understanding of insulin resistance, using systems wide and internally consistent data from human adipocytes. Based on quantitative steady-state and dynamic time course data on signaling intermediaries, normally and in diabetes, we developed a dynamic mathematical model of insulin signaling. The model structure and parameters are identical in the normal and diabetic states of the model, except for three parameters that change in diabetes: (i) reduced concentration of insulin receptor, (ii) reduced concentration of insulin-regulated glucose transporter GLUT4, and (iii) changed feedback from mammalian target of rapamycin in complex with raptor (mTORC1). Modeling reveals that at the core of insulin resistance in human adipocytes is attenuation of a positive feedback from mTORC1 to the insulin receptor substrate-1, which explains reduced sensitivity and signal strength throughout the signaling network. Model simulations with inhibition of mTORC1 are comparable with experimental data on inhibition of mTORC1 using rapamycin in human adipocytes. We demonstrate the potential of the model for identification of drug targets, e.g. increasing the feedback restores insulin signaling, both at the cellular level and, using a multilevel model, at the whole body level. Our findings suggest that insulin resistance in an expanded adipose tissue results from cell growth restriction to prevent cell necrosis.

  11. Glucose-dependent insulinotropic polypeptide induces cytokine expression, lipolysis, and insulin resistance in human adipocytes.

    PubMed

    Timper, Katharina; Grisouard, Jean; Sauter, Nadine S; Herzog-Radimerski, Tanja; Dembinski, Kaethi; Peterli, Ralph; Frey, Daniel M; Zulewski, Henryk; Keller, Ulrich; Müller, Beat; Christ-Crain, Mirjam

    2013-01-01

    Obesity-related insulin resistance is linked to a chronic state of systemic and adipose tissue-derived inflammation. Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone also acting on adipocytes. We investigated whether GIP affects inflammation, lipolysis, and insulin resistance in human adipocytes. Human subcutaneous preadipocyte-derived adipocytes, differentiated in vitro, were treated with human GIP to analyze mRNA expression and protein secretion of cytokines, glycerol, and free fatty acid release and insulin-induced glucose uptake. GIP induced mRNA expression of IL-6, IL-1β, and the IL-1 receptor antagonist IL-1Ra, whereas TNFα, IL-8, and monocyte chemotactic protein (MCP)-1 remained unchanged. Cytokine induction involved PKA and the NF-κB pathway as well as an autocrine IL-1 effect. Furthermore, GIP potentiated IL-6 and IL-1Ra secretion in the presence of LPS, IL-1β, and TNFα. GIP induced lipolysis via activation of hormone-sensitive lipase and was linked to NF-κB activation. Finally, chronic GIP treatment impaired insulin-induced glucose uptake possibly due to the observed impaired translocation of glucose transporter GLUT4. In conclusion, GIP induces an inflammatory and prolipolytic response via the PKA -NF-κB-IL-1 pathway and impairs insulin sensitivity of glucose uptake in human adipocytes.

  12. Effect of insulin and glucocorticoids on glucose transporters in rat adipocytes

    SciTech Connect

    Carter-Su, C.; Okamoto, K.

    1987-04-01

    The ability of glucocorticoids to modify the effect of insulin on glucose (L-1-/sup 3/H(N))glucose and D-(/sup 14/C-U)glucose) transport was investigated in both intact isolated rat adipocytes and in membranes isolated from hormone-treated adipocytes. In intact adipocytes, dexamethasone, a potent synthetic glucocorticoid, inhibited insulin-stimulated 3-O-methylglucose transport at all concentrations of insulin tested. Insulin sensitivity, as well as the maximal response to insulin, was decreased by dexamethasone in the absence of a change in /sup 125/I insulin binding. The inhibition was observed regardless of which hormone acted first, was blocked by actinomycin D, and resulted from a decrease in V/sub max/ rather than an increase in K/sub t/ of transport. In plasma membranes isolated from insulin-treated adipocytes, glucose transport activity and the amount of glucose transporter covalently labeled with (/sup 3/H)cytochalasin B were increased in parallel in a dose-dependent fashion. The amount of labeled transporter in a low-density microsomal fraction (LDMF) was decreased in a reciprocal fashion. In contrast, addition of dexamethasone to insulin-stimulated cells caused decreases in both transport activity and amount of labeled transporter in the plasma membranes. This was accompanied by a small increase in the amount of (/sup 3/H)cytochalasin B incorporated into the glucose transporter in the LDMF. These results are consistent with both insulin and glucocorticoids altering the distribution of glucose transporters between the plasma membrane and LDMF, in opposite directions.

  13. Obestatin regulates adipocyte function and protects against diet-induced insulin resistance and inflammation.

    PubMed

    Granata, Riccarda; Gallo, Davide; Luque, Raul M; Baragli, Alessandra; Scarlatti, Francesca; Grande, Cristina; Gesmundo, Iacopo; Córdoba-Chacón, Jose; Bergandi, Loredana; Settanni, Fabio; Togliatto, Gabriele; Volante, Marco; Garetto, Stefano; Annunziata, Marta; Chanclón, Belén; Gargantini, Eleonora; Rocchietto, Stefano; Matera, Lina; Datta, Giacomo; Morino, Mario; Brizzi, Maria Felice; Ong, Huy; Camussi, Giovanni; Castaño, Justo P; Papotti, Mauro; Ghigo, Ezio

    2012-08-01

    The metabolic actions of the ghrelin gene-derived peptide obestatin are still unclear. We investigated obestatin effects in vitro, on adipocyte function, and in vivo, on insulin resistance and inflammation in mice fed a high-fat diet (HFD). Obestatin effects on apoptosis, differentiation, lipolysis, and glucose uptake were determined in vitro in mouse 3T3-L1 and in human subcutaneous (hSC) and omental (hOM) adipocytes. In vivo, the influence of obestatin on glucose metabolism was assessed in mice fed an HFD for 8 wk. 3T3-L1, hSC, and hOM preadipocytes and adipocytes secreted obestatin and showed specific binding for the hormone. Obestatin prevented apoptosis in 3T3-L1 preadipocytes by increasing phosphoinositide 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK)1/2 signaling. In both mice and human adipocytes, obestatin inhibited isoproterenol-induced lipolysis, promoted AMP-activated protein kinase phosphorylation, induced adiponectin, and reduced leptin secretion. Obestatin also enhanced glucose uptake in either the absence or presence of insulin, promoted GLUT4 translocation, and increased Akt phosphorylation and sirtuin 1 (SIRT1) protein expression. Inhibition of SIRT1 by small interfering RNA reduced obestatin-induced glucose uptake. In HFD-fed mice, obestatin reduced insulin resistance, increased insulin secretion from pancreatic islets, and reduced adipocyte apoptosis and inflammation in metabolic tissues. These results provide evidence of a novel role for obestatin in adipocyte function and glucose metabolism and suggest potential therapeutic perspectives in insulin resistance and metabolic dysfunctions.

  14. Characterization of lipid metabolism in insulin-sensitive adipocytes differentiated from immortalized human mesenchymal stem cells

    SciTech Connect

    Prawitt, Janne; Niemeier, Andreas; Kassem, Moustapha; Beisiegel, Ulrike; Heeren, Joerg

    2008-02-15

    There is a great demand for cell models to study human adipocyte function. Here we describe the adipogenic differentiation of a telomerase-immortalized human mesenchymal stem cell line (hMSC-Tert) that maintains numerous features of terminally differentiated adipocytes even after prolonged withdrawal of the peroxisome proliferator activated receptor {gamma} (PPAR{gamma}) agonist rosiglitazone. Differentiated hMSC-Tert developed the characteristic monolocular phenotype of mature adipocytes. The expression of adipocyte specific markers was highly increased during differentiation. Most importantly, the presence of the PPAR{gamma} agonist rosiglitazone was not required for the stable expression of lipoprotein lipase, adipocyte fatty acid binding protein and perilipin on mRNA and protein levels. Adiponectin expression was post-transcriptionally down-regulated in the absence of rosiglitazone. Insulin sensitivity as measured by insulin-induced phosphorylation of Akt and S6 ribosomal protein was also independent of rosiglitazone. In addition to commonly used adipogenic markers, we investigated further PPAR{gamma}-stimulated proteins with a role in lipid metabolism. We observed an increase of lipoprotein receptor (VLDLR, LRP1) and apolipoprotein E expression during differentiation. Despite this increased expression, the receptor-mediated endocytosis of lipoproteins was decreased in differentiated adipocytes, suggesting that these proteins may have an additional function in adipose tissue beyond lipoprotein uptake.

  15. Characterization of lipid metabolism in insulin-sensitive adipocytes differentiated from immortalized human mesenchymal stem cells.

    PubMed

    Prawitt, Janne; Niemeier, Andreas; Kassem, Moustapha; Beisiegel, Ulrike; Heeren, Joerg

    2008-02-15

    There is a great demand for cell models to study human adipocyte function. Here we describe the adipogenic differentiation of a telomerase-immortalized human mesenchymal stem cell line (hMSC-Tert) that maintains numerous features of terminally differentiated adipocytes even after prolonged withdrawal of the peroxisome proliferator activated receptor gamma (PPARgamma) agonist rosiglitazone. Differentiated hMSC-Tert developed the characteristic monolocular phenotype of mature adipocytes. The expression of adipocyte specific markers was highly increased during differentiation. Most importantly, the presence of the PPARgamma agonist rosiglitazone was not required for the stable expression of lipoprotein lipase, adipocyte fatty acid binding protein and perilipin on mRNA and protein levels. Adiponectin expression was post-transcriptionally down-regulated in the absence of rosiglitazone. Insulin sensitivity as measured by insulin-induced phosphorylation of Akt and S6 ribosomal protein was also independent of rosiglitazone. In addition to commonly used adipogenic markers, we investigated further PPARgamma-stimulated proteins with a role in lipid metabolism. We observed an increase of lipoprotein receptor (VLDLR, LRP1) and apolipoprotein E expression during differentiation. Despite this increased expression, the receptor-mediated endocytosis of lipoproteins was decreased in differentiated adipocytes, suggesting that these proteins may have an additional function in adipose tissue beyond lipoprotein uptake.

  16. Susceptibility to Apoptosis in Insulin-like Growth Factor-I Receptor-deficient Brown Adipocytes

    PubMed Central

    Valverde, Angela M.; Mur, Cecilia; Brownlee, Michael; Benito, Manuel

    2004-01-01

    Fetal brown adipocytes are insulin-like growth factor-I (IGF-I) target cells. To assess the importance of the IGF-I receptor (IGF-IR) in brown adipocytes during fetal life, we have generated immortalized brown adipocyte cell lines from the IGF-IR-/- mice. Using this experimental model, we demonstrate that the lack of IGF-IR in fetal brown adipocytes increased the susceptibility to apoptosis induced by serum withdrawal. Culture of cells in the absence of serum and growth factors produced rapid DNA fragmentation (4 h) in IGF-IR-/- brown adipocytes, compared with the wild type (16 h). Consequently, cell viability was decreased more rapidly in fetal brown adipocytes in the absence of IGF-IR. Furthermore, caspase-3 activity was induced much earlier in cells lacking IGF-IR. At the molecular level, IGF-IR deficiency in fetal brown adipocytes altered the balance of the expression of several proapoptotic (Bcl-xS and Bim) and antiapoptotic (Bcl-2 and Bcl-xL) members of the Bcl-2 family. This imbalance was irreversible even though in IGF-IR-reconstituted cells. Likewise, cytosolic cytochrome c levels increased rapidly in IGF-IR-deficient cells compared with the wild type. A rapid entry of Foxo1 into the nucleus accompanied by a rapid exit from the cytosol and an earlier activation of caspase-8 were observed in brown adipocytes lacking IGF-IR upon serum deprivation. Activation of caspase-8 was inhibited by 50% in both cell types by neutralizing anti-Fas-ligand antibody. Adenoviral infection of wild-type brown adipocytes with constitutively active Foxol (ADA) increased the expression of antiapoptotic genes, decreased Bcl-xL and induced caspase-8 and -3 activities, with the final outcome of DNA fragmentation. Up-regulation of uncoupling protein-1 (UCP-1) expression in IGF-IR-deficient cells by transduction with PGC-1α or UCP-1 ameliorated caspase-3 activation, thereby retarding apoptosis. Finally, insulin treatment prevented apoptosis in both cell types. However, the survival

  17. Loss of Oncostatin M Signaling in Adipocytes Induces Insulin Resistance and Adipose Tissue Inflammation in Vivo.

    PubMed

    Elks, Carrie M; Zhao, Peng; Grant, Ryan W; Hang, Hardy; Bailey, Jennifer L; Burk, David H; McNulty, Margaret A; Mynatt, Randall L; Stephens, Jacqueline M

    2016-08-12

    Oncostatin M (OSM) is a multifunctional gp130 cytokine. Although OSM is produced in adipose tissue, it is not produced by adipocytes. OSM expression is significantly induced in adipose tissue from obese mice and humans. The OSM-specific receptor, OSM receptor β (OSMR), is expressed in adipocytes, but its function remains largely unknown. To better understand the effects of OSM in adipose tissue, we knocked down Osmr expression in adipocytes in vitro using siRNA. In vivo, we generated a mouse line lacking Osmr in adiponectin-expressing cells (OSMR(FKO) mice). The effects of OSM on gene expression were also assessed in vitro and in vivo OSM exerts proinflammatory effects on cultured adipocytes that are partially rescued by Osmr knockdown. Osm expression is significantly increased in adipose tissue T cells of high fat-fed mice. In addition, adipocyte Osmr expression is increased following high fat feeding. OSMR(FKO) mice exhibit increased insulin resistance and adipose tissue inflammation and have increased lean mass, femoral length, and bone volume. Also, OSMR(FKO) mice exhibit increased expression of Osm, the T cell markers Cd4 and Cd8, and the macrophage markers F4/80 and Cd11c Interestingly, the same proinflammatory genes induced by OSM in adipocytes are induced in the adipose tissue of the OSMR(FKO) mouse, suggesting that increased expression of proinflammatory genes in adipose tissue arises both from adipocytes and other cell types. These findings suggest that adipocyte OSMR signaling is involved in the regulation of adipose tissue homeostasis and that, in obesity, OSMR ablation may exacerbate insulin resistance by promoting adipose tissue inflammation.

  18. Modulation of the cellular content of metabolites in adipocytes by insulin.

    PubMed

    Qiao, Yuhang; Tomonaga, Shozo; Matsui, Tohru; Funaba, Masayuki

    2016-03-15

    Although the insulin-mediated cell signaling pathway has been extensively examined, changes in the cellular content of metabolites currently remain unclear. We herein examined metabolite contents in 3T3-L1 adipocytes treated with insulin using a metabolomic analysis. Fifty-four compounds were detected, and the contents of metabolites from the citric acid cycle increased in response to the insulin treatment for 4 h, which was sensitive to U0126 and LY294002, inhibitors for mitogen-activated protein kinase kinase-1 and phosphoinositide 3-kinase, respectively. The cellular contents of fumaric acid and malic acid were increased more by insulin than those of citric acid and succinic acid. Time-course changes in metabolites from the citric acid cycle exhibited oscillations with a 2-h cycle. A metabolic pathway analysis also indicated that insulin affected the metabolism of alanine, aspartate and glutamate, as well as that of arginine and proline. The contents of free amino acids were slightly decreased by the insulin treatment, while the co-treatment with U0126 and LY294002 abrogated these insulin-mediated decreases. The present study revealed the unexpected accumulation of citric acid cycle metabolites in adipocytes by insulin. Our results indicate the usefulness of metabolomic analyses for obtaining a more comprehensive understanding of the regulation of metabolic pathways in cell-culture systems.

  19. Knockdown of LYRM1 rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes.

    PubMed

    Zhang, Min; Qin, Zhen-Ying; Dai, Yong-mei; Wang, Yu-Mei; Zhu, Guan-zhong; Zhao, Ya-Ping; Ji, Chen-Bo; Zhu, Jin-Gai; Shi, Chun-Mei; Qiu, Jie; Cao, Xin-Guo; Guo, Xi-Rong

    2014-09-01

    LYR motif-containing 1 (LYRM1) was recently discovered to be involved in adipose tissue homeostasis and obesity-associated insulin resistance. We previously demonstrated that LYRM1 overexpression might contribute to insulin resistance and mitochondrial dysfunction. Additionally, knockdown of LYRM1 enhanced insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes. We investigated whether knockdown of LYRM1 in 3T3-L1 adipocytes could rescue insulin resistance and mitochondrial dysfunction induced by the cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP), a mitochondrion uncoupler, to further ascertain the mechanism by which LYRM1 is involved in obesity-associated insulin resistance. Incubation of 3T3-L1 adipocytes with 1 µM FCCP for 12 h decreased insulin-stimulated glucose uptake, reduced intracellular ATP synthesis, increased intracellular reactive oxygen species (ROS) production, impaired insulin-stimulated Glucose transporter type 4 (GLUT4) translocation, and diminished insulin-stimulated tyrosine phosphorylation of Insulin receptor substrate-1 (IRS-1) and serine phosphorylation of Protein Kinase B (Akt). Knockdown of LYRM1 restored insulin-stimulated glucose uptake, rescued intracellular ATP synthesis, reduced intracellular ROS production, restored insulin-stimulated GLUT4 translocation, and rescued insulin-stimulated tyrosine phosphorylation of IRS-1 and serine phosphorylation of Akt in FCCP-treated 3T3-L1 adipocytes. This study indicates that FCCP-induced mitochondrial dysfunction and insulin resistance are ameliorated by knockdown of LYRM1.

  20. Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes

    PubMed Central

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Martínez, J. Alfredo; de Miguel, Carlos; Milagro, Fermín I.

    2016-01-01

    ABSTRACT Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure. PMID:27144098

  1. Effects of high glucose on caveolin-1 and insulin signaling in 3T3-L1 adipocytes.

    PubMed

    Palacios-Ortega, Sara; Varela-Guruceaga, Maider; Martínez, J Alfredo; de Miguel, Carlos; Milagro, Fermín I

    2016-01-01

    Adipocytes exposed to high glucose concentrations exhibit impaired metabolic function, including an increase of oxidative and proinflammatory factors that might favor the development of insulin resistance. Caveolin-1 (Cav-1) is a key mediator of the insulin transduction pathway whose expression is significantly enhanced during adipocyte differentiation. In this work, we studied the effects of high glucose concentration on the regulation of Cav-1 expression and activation and its relation to the insulin signaling pathway during the adipogenic process and in long-term differentiated adipocytes. Both, long-term high glucose exposure during adipogenesis and short-term glucose incubation of mature adipocytes, promoted triglyceride accumulation in 3T3-L1 cells. The short-term exposure of mature adipocytes to high glucose significantly reduced the sensitivity to insulin of Cav-1, insulin receptor (IR) and potein kinase B (AKT-2) phosphorylation, as well as insulin-induced deoxyglucose uptake. Adipocytes differentiated in the presence of high glucose lost Cav-1 and IR response to insulin-stimulated phosphorylation, but maintained the insulin sensitivity of AKT-2 phosphorylation and deoxyglucose uptake. Although long-term high glucose exposure increased DNA methylation in Cav-1 promoter, Cav-1 expression was not affected. Moreover, these cells showed an increase of Cav-1, IR and AKT-2 protein content, pointing to an adaptive response induced by the long-term high glucose exposure.

  2. Measuring phospholipase D activity in insulin-secreting pancreatic beta-cells and insulin-responsive muscle cells and adipocytes.

    PubMed

    Cazzolli, Rosanna; Huang, Ping; Teng, Shuzhi; Hughes, William E

    2009-01-01

    Phospholipase D (PLD) is an enzyme producing phosphatidic acid and choline through hydrolysis of phosphatidylcholine. The enzyme has been identified as a member of a variety of signal transduction cascades and as a key regulator of numerous intracellular vesicle trafficking processes. A role for PLD in regulating glucose homeostasis is emerging as the enzyme has recently been identified in events regulating exocytosis of insulin from pancreatic beta-cells and also in insulin-stimulated glucose uptake through controlling GLUT4 vesicle exocytosis in muscle and adipose tissue. We present methodologies for assessing cellular PLD activity in secretagogue-stimulated insulin-secreting pancreatic beta-cells and also insulin-stimulated adipocyte and muscle cells, two of the principal insulin-responsive cell types controlling blood glucose levels.

  3. Glucose and Insulin Stimulate Lipogenesis in Porcine Adipocytes: Dissimilar and Identical Regulation Pathway for Key Transcription Factors

    PubMed Central

    Hua, Zhang Guo; Xiong, Lu Jian; Yan, Chen; Wei, Dai Hong; YingPai, ZhaXi; Qing, Zhao Yong; Lin, Qiao Zi; Fei, Feng Ruo; Ling, Wang Ya; Ren, Ma Zhong

    2016-01-01

    Lipogenesis is under the concerted action of ChREBP, SREBP-1c and other transcription factors in response to glucose and insulin. The isolated porcine preadipocytes were differentiated into mature adipocytes to investigate the roles and interrelation of these transcription factors in the context of glucose- and insulin-induced lipogenesis in pigs. In ChREBP-silenced adipocytes, glucose-induced lipogenesis decreased by ~70%, however insulin-induced lipogenesis was unaffected. Moreover, insulin had no effect on ChREBP expression of unperturbed adipocytes irrespective of glucose concentration, suggesting ChREBP mediate glucose-induced lipogenesis. Insulin stimulated SREBP-1c expression and when SREBP-1c activation was blocked, and the insulin-induced lipogenesis decreased by ~55%, suggesting SREBP-1c is a key transcription factor mediating insulin-induced lipogenesis. LXRα activation promoted lipogenesis and lipogenic genes expression. In ChREBP-silenced or SREBP-1c activation blocked adipocytes, LXRα activation facilitated lipogenesis and SREBP-1c expression, but had no effect on ChREBP expression. Therefore, LXRα might mediate lipogenesis via SREBP-1c rather than ChREBP. When ChREBP expression was silenced and SREBP-1c activation blocked simultaneously, glucose and insulin were still able to stimulated lipogenesis and lipogenic genes expression, and LXRα activation enhanced these effects, suggesting LXRα mediated directly glucose- and insulin-induced lipogenesis. In summary, glucose and insulin stimulated lipogenesis through both dissimilar and identical regulation pathway in porcine adipocytes. PMID:27871177

  4. Interferon γ Attenuates Insulin Signaling, Lipid Storage, and Differentiation in Human Adipocytes via Activation of the JAK/STAT Pathway*

    PubMed Central

    McGillicuddy, Fiona C.; Chiquoine, Elise H.; Hinkle, Christine C.; Kim, Roy J.; Shah, Rachana; Roche, Helen M.; Smyth, Emer M.; Reilly, Muredach P.

    2009-01-01

    Recent reports demonstrate T-cell infiltration of adipose tissue in early obesity. We hypothesized that interferon (IFN) γ, a major T-cell inflammatory cytokine, would attenuate human adipocyte functions and sought to establish signaling mechanisms. Differentiated human adipocytes were treated with IFNγ ± pharmacological inhibitors prior to insulin stimulation. [3H]Glucose uptake and AKT phosphorylation were assessed as markers of insulin sensitivity. IFNγ induced sustained loss of insulin-stimulated glucose uptake in human adipocytes, coincident with reduced Akt phosphorylation and down-regulation of the insulin receptor, insulin receptor substrate-1, and GLUT4. Loss of adipocyte triglyceride storage was observed with IFNγ co-incident with reduced expression of peroxisome proliferator-activated receptor γ, adiponectin, perilipin, fatty acid synthase, and lipoprotein lipase. Treatment with IFNγ also blocked differentiation of pre-adipocytes to the mature phenotype. IFNγ-induced robust STAT1 phosphorylation and SOCS1 mRNA expression, with modest, transient STAT3 phosphorylation and SOCS3 induction. Preincubation with a non-selective JAK inhibitor restored glucose uptake and Akt phosphorylation while completely reversing IFNγ suppression of adipogenic mRNAs and adipocyte differentiation. Specific inhibition of JAK2 or JAK3 failed to block IFNγ effects suggesting a predominant role for JAK1-STAT1. We demonstrate that IFNγ attenuates insulin sensitivity and suppresses differentiation in human adipocytes, an effect most likely mediated via sustained JAK-STAT1 pathway activation. PMID:19776010

  5. Insulin continues to induce plasminogen activator inhibitor 1 gene expression in insulin-resistant mice and adipocytes.

    PubMed Central

    Samad, F.; Pandey, M.; Bell, P. A.; Loskutoff, D. J.

    2000-01-01

    BACKGROUND: Although the association between insulin resistance and cardiovascular risk is well established, the underlying molecular mechanisms are poorly understood. The antifibrinolytic molecule plasminogen activator inhibitor 1 (PAI-1) is a cardiovascular risk factor that is consistently elevated in insulin-resistant states such as obesity and non-insulin-dependent diabetes mellitus (NIDDM). The strong positive correlation between this elevated PAI-1 and the degree of hyperinsulinemia not only implicates insulin itself in this increase, but also suggests that PAI-1 is regulated by a pathway that does not become insulin resistant. The data in this report supports this hypothesis. MATERIALS AND METHODS: We show that insulin stimulates PAI-1 gene expression in metabolically insulin-resistant ob/ob mice and in insulin-resistant 3T3-L1 adipocytes. Moreover, we provide evidence that glucose transport and PAI-1 gene expression are mediated by different insulin signaling pathways. These observations suggest that the compensatory hyperinsulinemia that is frequently associated with insulin-resistant states, directly contribute to the elevated PAI-1. CONCLUSIONS: These results provide a potential mechanism for the abnormal increases in cardiovascular risk genes in obesity, NIDDM, and polycystic ovary disease. PMID:11055587

  6. Effects of decavanadate and insulin enhancing vanadium compounds on glucose uptake in isolated rat adipocytes.

    PubMed

    Pereira, Maria João; Carvalho, Eugénia; Eriksson, Jan W; Crans, Debbie C; Aureliano, Manuel

    2009-12-01

    The effects of different vanadium compounds namely pyridine-2,6-dicarboxylatedioxovanadium(V) (V5-dipic), bis(maltolato) oxovanadium(IV) (BMOV) and amavadine, and oligovanadates namely metavanadate and decavanadate were analysed on basal and insulin stimulated glucose uptake in rat adipocytes. Decavanadate (50 microM), manifest a higher increases (6-fold) on glucose uptake compared with basal, followed by BMOV (1 mM) and metavanadate (1 mM) solutions (3-fold) whereas V5 dipic and amavadine had no effect. Decavanadate (100 microM) also shows the highest insulin like activity when compared with the others compounds studied. In the presence of insulin (10 nM), only decavanadate increases (50%) the glucose uptake when compared with insulin stimulated glucose uptake whereas BMOV and metavanadate, had no effect and V5 dipic and amavadine prevent the stimulation to about half of the basal value. Decavanadate is also able to reduce or eradicate the suppressor effect caused by dexamethasone on glucose uptake at the level of the adipocytes. Altogether, vanadium compounds and oligovanadates with several structures and coordination spheres reveal different effects on glucose uptake in rat primary adipocytes.

  7. Trehalose prevents adipocyte hypertrophy and mitigates insulin resistance in mice with established obesity.

    PubMed

    Arai, Chikako; Miyake, Masaki; Matsumoto, Yohsuke; Mizote, Akiko; Yoshizane, Chiyo; Hanaya, Yohko; Koide, Kazuhiro; Yamada, Mika; Hanaya, Toshiharu; Arai, Shigeyuki; Fukuda, Shigeharu

    2013-01-01

    Our group recently demonstrated that simultaneous administration of trehalose with a high-fat diet (HFD) suppresses adipocyte hypertrophy and mitigates insulin resistance in mice. For the present study, we hypothesized that similar effects of trehalose would be observed in mice with previously-established obesity. Obese mice were fed a HFD and drinking water containing 0.3 or 2.5% (weight/volume) trehalose or distilled water (DW) ad libitum for 8 wk. After 7 wk intake of a HFD and trehalose, fasting serum insulin levels and homeostasis model assessment-insulin resistance (HOMA-IR) in the 0.3% Tre/HFD group were significantly lower than those in the DW/HFD group (p<0.05). After 8 wk of treatment, mesenteric adipocytes in the 0.3% Tre/HFD group showed significantly less hypertrophy than those in the DW/HFD group. Mechanistic analysis indicated that levels of high molecular weight (HMW) adiponectin in the serum of the 0.3% Tre/HFD group were significantly higher than those in the DW/HFD group. The expression levels of insulin receptor substrate-1 (IRS-1) and insulin receptor substrate-2 (IRS-2) messenger RNA (mRNA) in muscle were also significantly increased by trehalose intake. Our data therefore suggest that administration of trehalose to obese mice mitigates insulin resistance by suppressing adipocyte hypertrophy and increasing serum HMW adiponectin, resulting in upregulation of IRS-1, and IRS-2 expression in muscle. These results further suggest that trehalose is a functional saccharide that may be used to prevent the progression of insulin resistance.

  8. Glucose and insulin modify thrombospondin 1 expression and secretion in primary adipocytes from diet-induced obese rats.

    PubMed

    Garcia-Diaz, Diego F; Arellano, Arianna V; Milagro, Fermin I; Moreno-Aliaga, Maria Jesus; Portillo, Maria Puy; Martinez, J Alfredo; Campion, Javier

    2011-09-01

    Thrombospondin 1 (TSP-1), an antiangiogenic factor and transforming growth factor (TGF)-β activity regulator, has been recently recognized as an adipokine that correlates with obesity, inflammation and insulin resistance processes. In the present study, epididymal adipocytes of rats that were fed a chow or a high-fat diet (HFD) for 50 days were isolated and incubated (24-72 h) in low (5.6 mM) or high (HG; 25 mM) glucose, in the presence or absence of 1.6 nM insulin. Rats fed the HF diet showed an established obesity state. Serum TSP-1 levels and TSP-1 mRNA basal expression of adipocytes from HFD rats were higher than those from controls. Adipocytes from HFD animals presented an insulin resistance state, as suggested by the lower insulin-stimulated glucose uptake as compared to controls. TSP-1 expression in culture was higher in adipocytes from obese animals at 24 h, but when the adipocytes were treated with HG, these expression levels dropped dramatically. Later at 72 h, TSP-1 expression was lower in adipocytes from HFD rats, and no effects of the other treatments were observed. Surprisingly, the secretion levels of this protein at 72 h were increased significantly by the HG treatment in both types of adipocytes, although they were even higher in adipocytes from obese animals. Finally, cell viability was significantly reduced by HG treatment in both types of adipocytes. In summary, TSP-1 expression/secretion was modulated in an in vitro model of insulin-resistant adipocytes. The difference between expression and secretion patterns suggests a posttranscriptional regulation. The present study confirms that TPS-1 is closely associated with obesity-related mechanisms.

  9. mRNA concentrations of MIF in subcutaneous abdominal adipose cells are associated with adipocyte size and insulin action

    PubMed Central

    Koska, Juraj; Stefan, Norbert; Dubois, Severine; Trinidad, Cathy; Considine, Robert V.; Funahashi, Tohru; Bunt, Joy C.; Ravussin, Eric; Permana, Paska A.

    2009-01-01

    Objective To determine whether the mRNA concentrations of inflammation response genes in isolated adipocytes and in cultured preadipocytes are related to adipocyte size and in vivo insulin action in obese individuals. Design Cross-sectional inpatient study. Subjects Obese Pima Indians with normal glucose tolerance. Measurements Adipocyte diameter (by microscope technique; n=29), expression of candidate genes (by quantitative real-time PCR) in freshly isolated adipocytes (monocyte chemoattractant protein [MCP] 1 and MCP2, macrophage inflammatory protein [MIP] 1α, MIP1β and MIP2, macrophage migration inhibitory factor [MIF], tumor necrosis factor alpha, interleukin [IL] 6 and IL8; n=22) and cultured preadipocytes (MCP1, MIP1α, MIF, IL6 and matrix metalloproteinase 2; n=33) from subcutaneous abdominal adipose tissue (by aspiration biopsy, n=34), body fat by dual-energy X-ray absorptiometry, glucose tolerance by 75-gram oral glucose tolerance test, and insulin action by euglycemic-hyperinsulinemic clamp (insulin infusion rate 40 mU/m2.min)(all n=34). Results MIF was the only gene whose expression in both freshly isolated adipocytes and cultured preadipocytes was positively associated with adipocytes diameter and negatively associated with peripheral and hepatic insulin action (all P<0.05). In multivariate analysis, the association between adipocyte MIF mRNA concentrations and adipocytes diameter was independent of percent body fat (P=0.03), whereas adipocyte MIF mRNA concentrations but not adipocytes diameter independently predicted peripheral insulin action. The mRNA expression concentrations of MIF gene in adipocytes were not associated with plasma concentrations of MIF, but were negatively associated with plasma adiponectin concentrations (P=0.004). In multivariate analysis, adipocyte MIF RNA concentrations (P=0.03) but not plasma adiponectin concentrations (P=0.4) remained a significant predictor of insulin action. Conclusions Increased expression of MIF gene in

  10. Chromium and vanadate combination increases insulin-induced glucose uptake by 3T3-L1 adipocytes.

    PubMed

    Brautigan, David L; Kruszewski, Allison; Wang, Hong

    2006-09-01

    Insulin activates signaling pathways in target tissues through the insulin receptor and Tyr phosphorylation of intracellular proteins. Vanadate mimics insulin and enhances its actions through inhibition of protein Tyr phosphatases. Chromium is a micronutrient that enhances insulin action to normalize blood glucose, but the mechanism is not understood. Here we show that either vanadate or chromium stimulates Tyr phosphorylation of insulin receptor in mouse 3T3-L1 adipocytes compared to insulin alone, but a combination of vanadate and chromium is not additive. Phosphorylation of MAPK or 4E-BP1 as markers for insulin signaling is stimulated by vanadate plus insulin, and chromium does not enhance the effects. Vanadate robustly activates glucose uptake by 3T3-L1 adipocytes even without added insulin and increases insulin-stimulated glucose uptake. Chromium pretreatment of adipocytes slightly enhances glucose uptake in response to insulin, but significantly increases glucose uptake above that induced by insulin plus vanadate. These data show that chromium enhances glucose uptake even when Tyr phosphorylation levels are elevated by vanadate plus insulin, suggesting separate mechanisms of action for vanadate and chromium.

  11. The Novel Endocrine Disruptor Tolylfluanid Impairs Insulin Signaling in Primary Rodent and Human Adipocytes through a Reduction in Insulin Receptor Substrate-1 Levels

    PubMed Central

    Sargis, Robert M.; Neel, Brian A.; Brock, Clifton O.; Lin, Yuxi; Hickey, Allison T.; Carlton, Daniel A.; Brady, Matthew J.

    2012-01-01

    Emerging data suggest that environmental endocrine disrupting chemicals (EDCs) may contribute to the pathophysiology of obesity and diabetes. In prior work, the phenylsulfamide fungicide tolylfluanid (TF) was shown to augment adipocyte differentiation, yet its effects on mature adipocyte metabolism remain unknown. Because of the central role of adipose tissue in global energy regulation, the present study tested the hypothesis that TF modulates insulin action in primary rodent and human adipocytes. Alterations in insulin signaling in primary mammalian adipocytes were determined by the phosphorylation of Akt, a critical insulin signaling intermediate. Treatment of primary murine adipose tissue in vitro with 100 nM TF for 48 h markedly attenuated acute insulin-stimulated Akt phosphorylation in a strain- and species-independent fashion. Perigonadal, perirenal, and mesenteric fat were all sensitive to TF-induced insulin resistance. A similar TF-induced reduction in insulin-stimulated Akt phosphorylation was observed in primary human subcutaneous adipose tissue. TF-treatment led to a potent and specific reduction in insulin receptor substrate-1 (IRS-1) mRNA and protein levels, a key upstream mediator of insulin’s diverse metabolic effects. In contrast, insulin receptor-β, phosphatidylinositol 3-kinase, and Akt expression were unchanged, indicating a specific abrogation of insulin signaling. Additionally, TF-treated adipocytes exhibited altered endocrine function with a reduction in both basal and insulin-stimulated leptin secretion. These studies demonstrate that TF induces cellular insulin resistance in primary murine and human adipocytes through a reduction of IRS-1 expression and protein stability, raising concern about the potential for this fungicide to disrupt metabolism and thereby contribute to the pathogenesis of diabetes. PMID:22387882

  12. Growth hormone, but not insulin, activates STAT5 proteins in adipocytes in vitro and in vivo.

    PubMed

    Zvonic, Sanjin; Story, David J; Stephens, Jacqueline M; Mynatt, Randall L

    2003-03-07

    STAT 5 proteins are latent transcription factors which have been shown to be activated by growth hormone (GH) in many cell types. However, some recent studies also suggest that STAT 5B is a physiological substrate of the insulin receptor. In our studies, we have shown that physiological levels of insulin do not induce STAT 5 tyrosine phosphorylation or affect the nuclear distribution of STATs 5A or 5B in 3T3-L1 adipocytes. Moreover, we did not observe the activation of STAT 5 in the adipose tissue or skeletal muscle of mice following an acute intraperitoneal injection of insulin. However, acute GH administration, both in vitro and in vivo, resulted in the activation of STAT 5 proteins. In summary, our results indicate that STAT 5 proteins are not activated by physiological levels of insulin in adipose tissue.

  13. Stevioside from Stevia rebaudiana Bertoni Increases Insulin Sensitivity in 3T3-L1 Adipocytes

    PubMed Central

    Mohd-Radzman, Nabilatul Hani; Ismail, Wan Iryani Wan; Jaapar, Siti Safura; Adam, Zainah; Adam, Aishah

    2013-01-01

    Stevioside from Stevia rebaudiana has been reported to exert antihyperglycemic effects in both rat and human subjects. There have been few studies on these effects in vitro. In this paper, radioactive glucose uptake assay was implemented in order to assess improvements in insulin sensitivity in 3T3-L1 cells by elevation of glucose uptake following treatment with stevioside. Oil Red-O staining and MTT assay were utilized to confirm adipocyte differentiation and cell viability, respectively. Findings from this research showed a significant increase in absorbance values in mature adipocytes following Oil Red-O staining, confirming the differentiation process. Stevioside was noncytotoxic to 3T3-L1 cells as cell viability was reduced by a maximum of 17%, making it impossible to determine its IC50. Stevioside increased glucose uptake activities by 2.1 times (p < 0.001) in normal conditions and up to 4.4 times (p < 0.001) in insulin-resistant states. At times, this increase was higher than that seen in positive control group treated with rosiglitazone maleate, an antidiabetic agent. Expressions of pY20 and p-IRS1 which were measured via Western blot were improved by stevioside treatment. In conclusion, stevioside has direct effects on 3T3-L1 insulin sensitivity via increase in glucose uptake and enhanced expression of proteins involved in insulin-signalling pathway. PMID:24391675

  14. Stevioside from Stevia rebaudiana Bertoni Increases Insulin Sensitivity in 3T3-L1 Adipocytes.

    PubMed

    Mohd-Radzman, Nabilatul Hani; Ismail, Wan Iryani Wan; Jaapar, Siti Safura; Adam, Zainah; Adam, Aishah

    2013-01-01

    Stevioside from Stevia rebaudiana has been reported to exert antihyperglycemic effects in both rat and human subjects. There have been few studies on these effects in vitro. In this paper, radioactive glucose uptake assay was implemented in order to assess improvements in insulin sensitivity in 3T3-L1 cells by elevation of glucose uptake following treatment with stevioside. Oil Red-O staining and MTT assay were utilized to confirm adipocyte differentiation and cell viability, respectively. Findings from this research showed a significant increase in absorbance values in mature adipocytes following Oil Red-O staining, confirming the differentiation process. Stevioside was noncytotoxic to 3T3-L1 cells as cell viability was reduced by a maximum of 17%, making it impossible to determine its IC50. Stevioside increased glucose uptake activities by 2.1 times (p < 0.001) in normal conditions and up to 4.4 times (p < 0.001) in insulin-resistant states. At times, this increase was higher than that seen in positive control group treated with rosiglitazone maleate, an antidiabetic agent. Expressions of pY20 and p-IRS1 which were measured via Western blot were improved by stevioside treatment. In conclusion, stevioside has direct effects on 3T3-L1 insulin sensitivity via increase in glucose uptake and enhanced expression of proteins involved in insulin-signalling pathway.

  15. Regulation of macrophage migration inhibitory factor (MIF) expression by glucose and insulin in adipocytes in vitro.

    PubMed Central

    Sakaue, S.; Nishihira, J.; Hirokawa, J.; Yoshimura, H.; Honda, T.; Aoki, K.; Tagami, S.; Kawakami, Y.

    1999-01-01

    BACKGROUND: It has been reported that macrophage migration inhibitory factor (MIF) stimulated insulin secretion from pancreatic islet beta-cells in an autocrine manner, which suggests its pivotal role in the glucose metabolism. According to this finding, we evaluated MIF expression in cultured adipocytes and epididymal fat pads of obese and diabetic rats to investigate its role in adipose tissue. MATERIALS AND METHODS: The murine adipocyte cell line 3T3-L1 was used to examine MIF mRNA expression and production of MIF protein in response to various concentrations of glucose and insulin. Epididymal fat pads of Otsuka Long-Evans Tokushima fatty (OLETF) and Wistar fatty rats, animal models of obesity and diabetes, were subjected to Northern blot analysis to determine MIF mRNA levels. RESULTS: MIF mRNA of 3T3-L1 adipocytes was up-regulated by costimulation with glucose and insulin. Intracellular MIF content was significantly increased by stimulation, whereas its content in the culture medium was decreased. When the cells were treated with cytochalasin B, MIF secretion in the medium was increased. Pioglitazone significantly increased MIF content in the culture medium of 3T3-L1 cells. However, MIF mRNA expression of both epididymal fat pads of OLETF and Wistar fatty rats was down-regulated despite a high plasma glucose level. The plasma MIF level of Wistar fatty rats was significantly increased by treatment with pioglitazone. CONCLUSION: We show here that the intracellular glucose level is critical to determining the MIF mRNA level as well as its protein content in adipose tissue. MIF is known to play an important role in glucose metabolism as a positive regulator of insulin secretion. In this context, it is conceivable that MIF may affect the pathophysiology of obesity and diabetes. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:10415161

  16. Phytic acid and myo-inositol support adipocyte differentiation and improve insulin sensitivity in 3T3-L1 cells.

    PubMed

    Kim, Jin Nam; Han, Sung Nim; Kim, Hye-Kyeong

    2014-08-01

    Phytic acid, also known as myo-inositol hexaphosphate, has been shown to lower blood glucose levels and to improve insulin sensitivity in rodents. We investigated the effects of phytic acid and myo-inositol on differentiation, insulin-stimulated glucose uptake, and lipolysis of adipocytes to test the hypothesis that the antidiabetic properties of phytic acid and myo-inositol are mediated directly through adipocytes. 3T3-L1 cells were treated with 10, 50, or 200 μmol/L of phytic acid or myo-inositol. Oil Red O staining and an intracellular triacylglycerol assay were used to determine lipid accumulation during adipocyte differentiation. Immunoblotting and real-time polymerase chain reaction (PCR) were performed to evaluate expression of transcription factors, a target protein, and insulin signaling molecules. Phytic acid and myo-inositol exposures increased lipid accumulation in a dose-dependent manner (P < .01). The expression of key transcription factors associated with adipocyte differentiation, such as peroxisome proliferator-activated receptor γ (PPARγ) and sterol regulatory element-binding protein 1c, and the expression of fatty acid synthase increased upon treatments with phytic acid and myo-inositol (P < .05). Insulin-stimulated glucose uptake in mature adipocytes increased with phytic acid and myo-inositol treatments (P < .01). In addition, mRNA levels of insulin receptor substrate 1 (IRS1), mRNA levels of glucose transporter 4, and phosphorylation of tyrosine in IRS1 increased upon phytic acid and myo-inositol treatments. In fully differentiated adipocytes, phytic acid and myo-inositol reduced basal lipolysis dose dependently (P < .01). These results suggest that phytic acid and myo-inositol increase insulin sensitivity in adipocytes by increasing lipid storage capacity, improving glucose uptake, and inhibiting lipolysis.

  17. Artemisia scoparia Enhances Adipocyte Development and Endocrine Function In Vitro and Enhances Insulin Action In Vivo

    PubMed Central

    Richard, Allison J.; Fuller, Scott; Fedorcenco, Veaceslav; Beyl, Robbie; Burris, Thomas P.; Mynatt, Randall; Ribnicky, David M.; Stephens, Jacqueline M.

    2014-01-01

    Background Failure of adipocytes to expand during periods of energy excess can result in undesirable metabolic consequences such as ectopic fat accumulation and insulin resistance. Blinded screening studies have indicated that Artemisia scoparia (SCO) extracts can enhance adipocyte differentiation and lipid accumulation in cultured adipocytes. The present study tested the hypothesis that SCO treatment modulates fat cell development and function in vitro and insulin sensitivity in adipose tissue in vivo. Methods In vitro experiments utilized a Gal4-PPARγ ligand binding domain (LBD) fusion protein-luciferase reporter assay to examine PPARγ activation. To investigate the ability of SCO to modulate adipogenesis and mature fat cell function in 3T3-L1 cells, neutral lipid accumulation, gene expression, and protein secretion were measured by Oil Red O staining, qRT-PCR, and immunoblotting, respectively. For the in vivo experiments, diet-induced obese (DIO) C57BL/6J mice were fed a high-fat diet (HFD) or HFD containing 1% w/w SCO for four weeks. Body weight and composition, food intake, and fasting glucose and insulin levels were measured. Phospho-activation and expression of insulin-sensitizing proteins in epididymal adipose tissue (eWAT) were measured by immunoblotting. Results Ethanolic extracts of A. scoparia significantly activated the PPARγ LBD and enhanced lipid accumulation in differentiating 3T3-L1 cells. SCO increased the transcription of several PPARγ target genes in differentiating 3T3-L1 cells and rescued the negative effects of tumor necrosis factor α on production and secretion of adiponectin and monocyte chemoattractant protein-1 in fully differentiated fat cells. DIO mice treated with SCO had elevated adiponectin levels and increased phosphorylation of AMPKα in eWAT when compared to control mice. In SCO-treated mice, these changes were also associated with decreased fasting insulin and glucose levels. Conclusion SCO has metabolically beneficial

  18. Isoproterenol stimulates phosphorylation of the insulin-regulatable glucose transporter in rat adipocytes.

    PubMed Central

    James, D E; Hiken, J; Lawrence, J C

    1989-01-01

    We have examined the acute effects of insulin and isoproterenol on the phosphorylation state of the insulin-regulatable glucose transporter (IRGT) in rat adipocytes. The IRGT was immunoprecipitated from either detergent-solubilized whole-cell homogenates or subcellular fractions of 32P-labeled fat cells and subjected to sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The 32P-labeled IRGT was detected by autoradiography as a species of apparent Mr 46,000. Insulin stimulated translocation of the IRGT from low-density microsomes to the plasma membrane but did not affect phosphorylation of the transporter in either fraction. Isoproterenol inhibited insulin-stimulated glucose transport by 40% but was without effect on the subcellular distribution of the transporter in either the presence or absence of insulin. Isoproterenol stimulated phosphorylation of the IRGT 2-fold. Incubating cells with dibutyryl-cAMP and 8-bromo-cAMP also stimulated phosphorylation 2-fold, and the transporter was phosphorylated in vitro when IRGT-enriched vesicles were incubated with cAMP-dependent protein kinase and [gamma-32P]ATP. These results suggest that isoproterenol stimulates phosphorylation of the IRGT via a cAMP-dependent pathway and that phosphorylation of the transporter may modulate its ability to transport glucose. Images PMID:2554313

  19. A polyphenol rescues lipid induced insulin resistance in skeletal muscle cells and adipocytes.

    PubMed

    Gogoi, Bhaskarjyoti; Chatterjee, Priyajit; Mukherjee, Sandip; Buragohain, Alak Kumar; Bhattacharya, Samir; Dasgupta, Suman

    2014-09-26

    Skeletal muscle and adipose tissues are known to be two important insulin target sites. Therefore, lipid induced insulin resistance in these tissues greatly contributes in the development of type 2 diabetes (T2D). Ferulic acid (FRL) purified from the leaves of Hibiscus mutabilis, showed impressive effects in preventing saturated fatty acid (SFA) induced defects in skeletal muscle cells. Impairment of insulin signaling molecules by SFA was significantly waived by FRL. SFA markedly reduced insulin receptor β (IRβ) in skeletal muscle cells, this was affected due to the defects in high mobility group A1 (HMGA1) protein obtruded by phospho-PKCε and that adversely affects IRβ mRNA expression. FRL blocked PKCε activation and thereby permitted HMGA1 to activate IRβ promoter which improved IR expression deficiency. In high fat diet (HFD) fed diabetic rats, FRL reduced blood glucose level and enhanced lipid uptake activity of adipocytes isolated from adipose tissue. Importantly, FRL suppressed fetuin-A (FetA) gene expression, that reduced circulatory FetA level and since FetA is involved in adipose tissue inflammation, a significant attenuation of proinflammatory cytokines occurred. Collectively, FRL exhibited certain unique features for preventing lipid induced insulin resistance and therefore promises a better therapeutic choice for T2D.

  20. Isolation of insulin-sensitive phosphatidylinositol-glycan from rat adipocytes. Its impaired breakdown in the streptozotocin-diabetic rat.

    PubMed Central

    Macaulay, S L; Larkins, R G

    1990-01-01

    In this study an insulin-sensitive glycophospholipid from rat adipocytes was isolated and partially characterized. A material that activated pyruvate dehydrogenase was extracted from rat adipocyte membrane supernatants. Its release was stimulated by insulin and phosphatidylinositol-specific-phospholipase C and its activity was destroyed by nitrous acid deamination. These findings suggested that insulin might stimulate breakdown of a glycophospholipid containing inositol and glucosamine, as previously reported for some other cell types [Low & Saltiel (1988) Science 239, 268-275]. A lipid that incorporated [3H]glucosamine, [3H]galactose, [3H]inositol, and [3H]myristate and whose turnover was stimulated by insulin was subsequently isolated from intact adipocytes by sequential t.l.c. using an acidic solvent system followed by a basic solvent system. The effects of insulin on turnover of the lipid in these cells were transient, with maximal effects at 1 min, and there was a typical concentration-response curve to insulin (0.07 nM-7 nM), with effects being detected over the physiological range of insulin concentrations. In contrast with studies in other cells, there was appreciable turnover of the sugar labels. The majority of the [3H]glucosamine and [3H]galactose labels were cycled through to triacylglycerol in the adipocyte. However, of that recovered in the glycophospholipid band, a major proportion (less than 40%) was recovered as the native label. Digestion of the purified molecule with phosphatidylinositol-specific phospholipase C generated a material that activated both pyruvate dehydrogenase and low-Km cyclic AMP phosphodiesterase. Impairment in insulin-stimulated breakdown of the molecule in adipocytes of streptozotocin-diabetic rats was found, consistent with the impaired insulin activation of pyruvate dehydrogenase and glucose utilization seen in this model. These findings suggest that insulin stimulates breakdown of this glycophospholipid by stimulating an

  1. Piromelatine decreases triglyceride accumulation in insulin resistant 3T3-L1 adipocytes: role of ATGL and HSL.

    PubMed

    Wang, Ping-Ping; She, Mei-Hua; He, Ping-Ping; Chen, Wu-Jun; Laudon, Moshe; Xu, Xuan-Xuan; Yin, Wei-Dong

    2013-08-01

    Piromelatine, a novel investigational multimodal sleep medicine, is developed for the treatment of patients with primary and co-morbid insomnia. Piromelatine has been shown to inhibit weight gain and improve insulin sensitivity in high-fat/high-sucrose-fed (HFHS) rats. Considering that piromelatine has also been implicated in lowering of triglyceride levels in HFHS rats, this work elucidated whether this effect involves in the regulation of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) in triglyceride (TG) metabolism. In this study, we investigated the effects of piromelatine and MT2 receptors inhibition on TG content, insulin-stimulated glucose uptake, and the expressions of ATGL and HSL in 3T3-L1 adipocytes preincubated in high glucose and high insulin (HGI) conditions. Our results showed that culturing 3T3-L1 adipocytes under HGI conditions increased triglyceride accumulation with concomitant decrease of ATGL and HSL expression, inducing insulin resistance in 3T3-L1 adipocytes. We also found that triglyceride accumulation was significantly inhibited and the levels of ATGL/HSL increased after melatonin or piromelatine treatment. The effects of melatonin/piromelatine (10 nM) were counteracted by pretreatment with the relatively selective MT2 receptor antagonist luzindole (100 nM). In this study, our data demonstrate that piromelatine reverses high glucose and high insulin-induced triglyceride accumulation in 3T3-L1 adipocytes, possibly through up-regulating of ATGL and HSL expression via a melatonin-dependent manner.

  2. ApoA-IV improves insulin sensitivity and glucose uptake in mouse adipocytes via PI3K-Akt Signaling

    PubMed Central

    Li, Xiaoming; Wang, Fei; Xu, Min; Howles, Philip; Tso, Patrick

    2017-01-01

    Insulin resistance is a risk factor for type 2 diabetes mellitus. We investigated the effect of ApoA-IV on glucose uptake in the adipose and muscle tissues of mice and cultured 3T3-L1 adipocytes. We found that treatment with ApoA-IV lowered fasting blood glucose in both WT and diabetic KKAy mice by increasing glucose uptake in cardiac muscle, white adipose tissue, and brown adipose tissue through a mechanism that was partially insulin independent. Cell culture experiments showed that ApoA-IV improved glucose uptake in adipocytes in the absence of insulin by upregulating GLUT4 translocation by PI3K mediated activation of Akt signaling pathways. Considering our previous finding that ApoA-IV treatment enhanced pancreatic insulin secretion, these results suggests that ApoA-IV acts directly upon adipose tissue to improve glucose uptake and indirectly via insulin signaling. Our findings warrant future studies to identify the receptor for ApoA-IV and the downstream targets of PI3K-Akt signaling that regulate glucose uptake in adipocytes as potential therapeutic targets for treating insulin resistance. PMID:28117404

  3. Nandinine, a Derivative of Berberine, Inhibits Inflammation and Reduces Insulin Resistance in Adipocytes via Regulation of AMP-Kinase Activity.

    PubMed

    Zhao, Wenwen; Ge, Haixia; Liu, Kang; Chen, Xiuping; Zhang, Jian; Liu, Baolin

    2017-02-01

    Nandinine is a derivative of berberine that has high efficacy for treating cardiovascular diseases. This study investigated the effects of berberine and nandinine on the regulation of insulin sensitivity in adipocytes. Through treatment with macrophage-derived conditioned medium in 3T3-L1 adipocytes, dysregulation of adipokine production and activation of the IκB kinase β/nuclear factor-kappa B pathway was induced. However, these phenomena were effectively reversed by berberine, nandinine, and salicylate pretreatments. Furthermore, both berberine and nandinine inhibited serine phosphorylation of insulin receptor substrate-1 induced by IκB kinase β and increased tyrosine phosphorylation of insulin receptor substrate-1 to activate the PI3K/Akt pathway, which finally led to insulin-mediated glucose uptake. In addition, berberine and nandinine significantly increased AMP-activated protein kinase activity, thereby contributing to their anti-inflammatory effect by inhibiting IκB kinase β activation. Finally, in vivo studies demonstrated that both berberine (100 or 200 mg/kg) and nandinine (100 or 200 mg/kg) effectively ameliorated glucose intolerance and induced the insulin sensitivity index in mice. In conclusion, berberine and nandinine attenuated insulin resistance in adipocytes by inhibiting inflammation in an AMP-activated protein kinase-dependent manner. Berberine and nandinine may be used as dietary supplements and nandinine is a new candidate for obesity treatment.

  4. Bavachin from Psoralea corylifolia Improves Insulin-Dependent Glucose Uptake through Insulin Signaling and AMPK Activation in 3T3-L1 Adipocytes.

    PubMed

    Lee, Hyejin; Li, Hua; Noh, Minsoo; Ryu, Jae-Ha

    2016-04-08

    The fruit of Psoralea corylifolia L. (Fabaceae) (PC), known as "Bo-Gol-Zhee" in Korea has been used as traditional medicine. Ethanol and aqueous extracts of PC have an anti-hyperglycemic effect by increasing plasma insulin levels and decreasing blood glucose and total plasma cholesterol levels in type 2 diabetic rats. In this study, we purified six compounds from PC and investigated their anti-diabetic effect. Among the purified compounds, bavachin most potently accumulated lipids during adipocyte differentiation. Intracellular lipid accumulation was measured by Oil Red-O (ORO) cell staining to investigate the effect of compounds on adipogenesis. Consistently, bavachin activated gene expression of adipogenic transcriptional factors, proliferator-activated receptorγ (PPARγ) and CCAAT/enhancer binding protein-α (C/EBPα). Bavachin also increased adiponectin expression and secretion in adipocytes. Moreover, bavachin increased insulin-induced glucose uptake by differentiated adipocytes and myoblasts. In differentiated adipocytes, we found that bavachin enhanced glucose uptake via glucose transporter 4 (GLUT4) translocation by activating the Akt and 5'AMP-activated protein kinase (AMPK) pathway in the presence or absence of insulin. These results suggest that bavachin from Psoralea corylifolia might have therapeutic potential for type 2 diabetes by activating insulin signaling pathways.

  5. Bavachin from Psoralea corylifolia Improves Insulin-Dependent Glucose Uptake through Insulin Signaling and AMPK Activation in 3T3-L1 Adipocytes

    PubMed Central

    Lee, Hyejin; Li, Hua; Noh, Minsoo; Ryu, Jae-Ha

    2016-01-01

    The fruit of Psoralea corylifolia L. (Fabaceae) (PC), known as “Bo-Gol-Zhee” in Korea has been used as traditional medicine. Ethanol and aqueous extracts of PC have an anti-hyperglycemic effect by increasing plasma insulin levels and decreasing blood glucose and total plasma cholesterol levels in type 2 diabetic rats. In this study, we purified six compounds from PC and investigated their anti-diabetic effect. Among the purified compounds, bavachin most potently accumulated lipids during adipocyte differentiation. Intracellular lipid accumulation was measured by Oil Red-O (ORO) cell staining to investigate the effect of compounds on adipogenesis. Consistently, bavachin activated gene expression of adipogenic transcriptional factors, proliferator-activated receptorγ (PPARγ) and CCAAT/enhancer binding protein-α (C/EBPα). Bavachin also increased adiponectin expression and secretion in adipocytes. Moreover, bavachin increased insulin-induced glucose uptake by differentiated adipocytes and myoblasts. In differentiated adipocytes, we found that bavachin enhanced glucose uptake via glucose transporter 4 (GLUT4) translocation by activating the Akt and 5′AMP-activated protein kinase (AMPK) pathway in the presence or absence of insulin. These results suggest that bavachin from Psoralea corylifolia might have therapeutic potential for type 2 diabetes by activating insulin signaling pathways. PMID:27070585

  6. Synergistic induction of insulin resistance by endothelin-1 and cAMP in 3T3-L1 adipocytes.

    PubMed

    Chai, Shin-Pei; Fong, Jim C

    2015-10-01

    Both endothelin-1 (ET-1) and cAMP are implicated for inducing insulin resistance. Since we have shown previously that there is a crosstalk between ET-1 and cAMP signaling pathways in regulating glucose uptake in 3T3-L1 adipocytes, we extended our investigation in this study on whether they may have a synergistic effect on inducing insulin resistance. Our results showed that it was indeed the case. Insulin-stimulated glucose uptake, phosphorylation of PKB, IRS-1-associated PI3K, and IRS-1 tyrosine phosphorylation were all inhibited by ET-1 and 8-bromo cAMP in a synergistic manner. IRS-1 protein levels were similarly decreased by ET-1 and 8-bromo cAMP, attributable to suppressed mRNA expression. In addition, after correction for the loss in IRS-1 protein, the inhibition of insulin-stimulated IRS-1 tyrosine phosphorylation or IRS-1-associated PI3K was mainly caused by cAMP. Moreover, whereas IRS-2 protein levels were increased by cAMP or ET-1 plus cAMP, insulin-stimulated IRS-2-associated PI3K activities were abolished by both treatments. Furthermore, ET-1 and β-adrenergic agonists had similar synergistic inhibition on insulin-stimulated glucose uptake. In conclusion, we have shown that ET-1 and cAMP may synergistically induce insulin resistance in adipocytes via inhibiting IRS-1 expression as well as insulin-stimulated IRS-1/IRS-2 activities.

  7. Adipocyte-specific CD1d-deficiency mitigates diet-induced obesity and insulin resistance in mice

    PubMed Central

    Satoh, Masashi; Hoshino, Miyuki; Fujita, Koki; Iizuka, Misao; Fujii, Satoshi; Clingan, Christopher S.; Van Kaer, Luc; Iwabuchi, Kazuya

    2016-01-01

    It has been shown that CD1d expression and glycolipid-reactive, CD1d-restricted NKT cells exacerbate the development of obesity and insulin resistance in mice. However, the relevant CD1d-expressing cells that influence the effects of NKT cells on the progression of obesity remain incompletely defined. In this study, we have demonstrated that 3T3-L1 adipocytes can present endogenous ligands to NKT cells, leading to IFN-γ production, which in turn, stimulated 3T3-L1 adipocytes to enhance expression of CD1d and CCL2, and decrease expression of adiponectin. Furthermore, adipocyte-specific CD1d deletion decreased the size of the visceral adipose tissue mass and enhanced insulin sensitivity in mice fed a high-fat diet (HFD). Accordingly, NKT cells were less activated, IFN-γ production was significantly reduced, and levels of adiponectin were increased in these animals as compared with control mice on HFD. Importantly, macrophage recruitment into the adipose tissue of adipocyte-specific CD1d-deficient mice was significantly blunted. These findings indicate that interactions between NKT cells and CD1d-expressing adipocytes producing endogenous NKT cell ligands play a critical role in the induction of inflammation and functional modulation of adipose tissue that leads to obesity. PMID:27329323

  8. Regulation of insulin-like growth factor II receptors by growth hormone and insulin in rat adipocytes

    SciTech Connect

    Loennroth, P.; Assmundsson, K.; Eden, S.; Enberg, G.; Gause, I.; Hall, K.; Smith, U.

    1987-06-01

    The acute and long-term effects of growth hormone (GH) on the binding of insulin-like growth factor II (IGF-II) were evaluated in adipose cells from hypophysectomized rats given replacement therapy with thyroxine and hydrocortisone and in cells from their sham-operated littermates. After the cells were incubated with insulin and/or GH, the recycling of /sup 125/I-labeled IGF-II receptors was metabolically inhibited by treating the cells with KCN. IGF-II binding was 100 +/- 20% higher in cells from GH-deficient animals when compared with sham-operated controls. These GH-deficient cells also showed an increased sensitivity for insulin as compared with control cells (the EC/sub 50/ for insulin was 0.06 ng/ml in GH-deficient cells and 0.3 ng/ml in control cells.). However, the maximal incremental effect of insulin on IGH-II binding was reduced approx. = 27% by hypophysectomy. GH added to the incubation medium increased the number of IGF-II binding sites by 100 +/- 18% in cells from hypophysectomized animals. This increase was rapidly induced, but the time course was slower than that for the stimulatory effect of insulin. Half-maximal effect of GH on IGF-II binding was obtained at approx. = 30 ng/ml. Thus, GH added in vitro exerted a rapid insulin-like effect on the number of IGH-II receptors. GH also appears to play a regulating role for maintaining the cellular number of IGH-II receptors and, in addition, modulates the stimulatory effect of insulin on IGF-II binding.

  9. Knockdown of NYGGF4 (PID1) rescues insulin resistance and mitochondrial dysfunction induced by FCCP in 3T3-L1 adipocytes.

    PubMed

    Shi, Chun-Mei; Wang, Yu-Mei; Zhang, Chun-Mei; Qiu, Jie; Shen, Ya-Hui; Zhu, Jin-Gai; Chen, Lin; Xu, Guang-Feng; Zhao, Ya-Ping; Ji, Chen-Bo; Guo, Xi-Rong

    2012-11-01

    NYGGF4 is a recently identified gene that is involved in obesity-associated insulin resistance. Previous data from this laboratory have demonstrated that NYGGF4 overexpression might contribute to the development of insulin resistance (IR) and to mitochondrial dysfunction. Additionally, NYGGF4 knockdown enhanced insulin sensitivity and mitochondrial function in 3T3-L1 adipocytes. We designed this study to determine whether silencing of NYGGF4 in 3T3-L1 adipocytes could rescue the effect of insulin sensitivity and mitochondrial function induced by the cyanide p-trifluoromethoxyphenyl-hydrazone (FCCP), a mitochondrion uncoupler, to ascertain further the mechanism of NYGGF4 involvement in obesity-associated insulin resistance. We found that 3T3-L1 adipocytes, incubated with 5μM FCCP for 12h, had decreased levels of insulin-stimulated glucose uptake and had impaired insulin-stimulated GLUT4 translocation. Silencing also diminished insulin-stimulated tyrosinephosphorylation of IRS-1 and serine phosphorylation of Akt. This phenomenon contrasts with the effect of NYGGF4 knockdown on insulin sensitivity and describes the regulatory function of NYGGF4 in adipocytes insulin sensitivity. We next analyzed the mitochondrial function in NYGGF4-silenced adipocytes incubated with FCCP. NYGGF4 knockdown partly rescued the dissipation of mitochondrial mass, mitochondrial DNA, intracellular ATP synthesis, and intracellular reactive oxygen species (ROS) production occurred following the addition of FCCP, as well as inhibition of mitochondrial transmembrane potential (ΔΨm) in 3T3-L1 adipocytes incubated with FCCP. Collectively, our results suggested that addition of silencing NYGGF4 partly rescued the effect of insulin resistance and mitochondrial dysfunction in NYGGF4 silenced 3T3-L1 adipocytes incubated with FCCP, which might explain the involvement of NYGGF4-induced IR and the development of NYGGF4 in mitochondrial function.

  10. Inhibition of insulin-stimulated phosphorylation of the intracellular domain of phospholemman decreases insulin-dependent GLUT4 translocation in streptolysin-O-permeabilized adipocytes.

    PubMed Central

    Walaas, O; Horn, R S; Walaas, S I

    1999-01-01

    A variety of studies indicate that protein kinase C might be involved in the insulin signalling cascade leading to translocation of the insulin-regulated glucose transporter GLUT4 from intracellular pools to the plasma membrane. Phospholemman is a plasma-membrane protein kinase C substrate whose phosphorylation is increased by insulin in intact muscle [Walaas, Czernik, Olstad, Sletten and Walaas (1994) Biochem. J. 304, 635-640]. The present study examined whether the inhibition of phospholemman phosphorylation modulates the effects of insulin on GLUT4 translocation. For this purpose, a synthetic peptide derived from the intracellular domain of phospholemman with the phosphorylatable serine residues replaced with alanine residues was prepared. This peptide was found to decrease the protein kinase C-catalysed phosphorylation of a synthetic phospholemman peptide in vitro. When introduced into streptolysin-O-permeabilized adipocytes, the peptide decreased the effects of insulin on both the phosphorylation of phospholemman and the recruitment of GLUT4 to the plasma membrane. Similarly, the internalization of phospholemman antibodies, which also decreased the protein kinase C-mediated phosphorylation of the synthetic phospholemman peptide in vitro, decreased the effect of insulin on GLUT4 translocation in the adipocytes. The results suggest that phosphorylation of the intracellular domain of phospholemman might be involved in modulating the insulin-induced translocation of GLUT4 to the plasma membrane. PMID:10493924

  11. Insulin stimulates actin comet tails on intracellular GLUT4-containing compartments in differentiated 3T3L1 adipocytes.

    PubMed

    Kanzaki, M; Watson, R T; Khan, A H; Pessin, J E

    2001-12-28

    Incubation of isolated GLUT4-containing vesicles with Xenopus oocyte extracts resulted in a guanosine 5'-[gamma-thio]triphosphate (GTP gamma S) and sodium orthovanadate stimulation of actin comet tails. The in vitro actin-based GLUT4 vesicle motility was inhibited by both latrunculin B and a dominant-interfering N-WASP mutant, N-WASP/Delta VCA. Preparations of gently sheared (broken) 3T3L1 adipocytes also displayed GTP gamma S and sodium orthovanadate stimulation of actin comet tails on GLUT4 intracellular compartments. Furthermore, insulin pretreatment of intact adipocytes prior to gently shearing also resulted in a marked increase in actin polymerization and actin comet tailing on GLUT4 vesicles. In addition, the insulin stimulation of actin comet tails was completely inhibited by Clostridum difficile toxin B, demonstrating a specific role for a Rho family member small GTP-binding protein. Expression of N-WASP/Delta VCA in intact cells had little effect on adipocyte cortical actin but partially inhibited insulin-stimulated GLUT4 translocation. Taken together, these data demonstrate that insulin can induce GLUT4 vesicle actin comet tails that are necessary for the efficient translocation of GLUT4 from intracellular storage sites to the plasma membrane.

  12. Palmitate stimulates glucose transport in rat adipocytes by a mechanism involving translocation of the insulin sensitive glucose transporter (GLUT4)

    NASA Technical Reports Server (NTRS)

    Hardy, R. W.; Ladenson, J. H.; Henriksen, E. J.; Holloszy, J. O.; McDonald, J. M.

    1991-01-01

    In rat adipocytes, palmitate: a) increases basal 2-deoxyglucose transport 129 +/- 27% (p less than 0.02), b) decreases the insulin sensitive glucose transporter (GLUT4) in low density microsomes and increases GLUT4 in plasma membranes and c) increases the activity of the insulin receptor tyrosine kinase. Palmitate-stimulated glucose transport is not additive with the effect of insulin and is not inhibited by the protein kinase C inhibitors staurosporine and sphingosine. In rat muscle, palmitate: a) does not affect basal glucose transport in either the soleus or epitrochlearis and b) inhibits insulin-stimulated glucose transport by 28% (p less than 0.005) in soleus but not in epitrochlearis muscle. These studies demonstrate a potentially important differential role for fatty acids in the regulation of glucose transport in different insulin target tissues.

  13. Plac8 is required for white adipocyte differentiation in vitro and cell number control in vivo.

    PubMed

    Jimenez-Preitner, Maria; Berney, Xavier; Thorens, Bernard

    2012-01-01

    Plac8 belongs to an evolutionary conserved family of proteins, mostly abundant in plants where they control fruit weight through regulation of cell number. In mice, Plac8 is expressed both in white and brown adipose tissues and we previously showed that Plac8(-/-) mice develop late-onset obesity, with abnormal brown fat differentiation and reduced thermogenic capacity. We also showed that in brown adipocytes, Plac8 is an upstream regulator of C/EBPβ expression. Here, we first assessed the role of Plac8 in white adipogenesis in vitro. We show that Plac8 is induced early after induction of 3T3-L1 adipocytes differentiation, a process that is prevented by Plac8 knockdown; similarly, embryonic fibroblasts obtained from Plac8 knockout mice failed to form adipocytes upon stimulation of differentiation. Knockdown of Plac8 in 3T3-L1 was associated with reduced expression of C/EBPβ, Krox20, and Klf4, early regulators of the white adipogenic program, and we show that Plac8 could transactivate the C/EBPβ promoter. In vivo, we show that absence of Plac8 led to increased white fat mass with enlarged adipocytes but reduced total number of adipocytes. Finally, even though Plac8(-/-) mice showed impaired thermogenesis due to brown fat dysfunction, this was not associated with changes in glycemia or plasma free fatty acid and triglyceride levels. Collectively, these data indicate that Plac8 is an upstream regulator of C/EBPβ required for adipogenesis in vitro. However, in vivo, Plac8 is dispensable for the differentiation of white adipocytes with preserved fat storage capacity but is required for normal fat cell number regulation.

  14. Proteomic Analysis of GLUT4 Storage Vesicles Reveals Tumor Suppressor Candidate 5 (TUSC5) as a Novel Regulator of Insulin Action in Adipocytes*

    PubMed Central

    Fazakerley, Daniel J.; Naghiloo, Sheyda; Chaudhuri, Rima; Koumanov, Françoise; Burchfield, James G.; Thomas, Kristen C.; Krycer, James R.; Prior, Matthew J.; Parker, Ben L.; Murrow, Beverley A.; Stöckli, Jacqueline; Meoli, Christopher C.; Holman, Geoffrey D.; James, David E.

    2015-01-01

    Insulin signaling augments glucose transport by regulating glucose transporter 4 (GLUT4) trafficking from specialized intracellular compartments, termed GLUT4 storage vesicles (GSVs), to the plasma membrane. Proteomic analysis of GSVs by mass spectrometry revealed enrichment of 59 proteins in these vesicles. We measured reduced abundance of 23 of these proteins following insulin stimulation and assigned these as high confidence GSV proteins. These included established GSV proteins such as GLUT4 and insulin-responsive aminopeptidase, as well as six proteins not previously reported to be localized to GSVs. Tumor suppressor candidate 5 (TUSC5) was shown to be a novel GSV protein that underwent a 3.7-fold increase in abundance at the plasma membrane in response to insulin. siRNA-mediated knockdown of TUSC5 decreased insulin-stimulated glucose uptake, although overexpression of TUSC5 had the opposite effect, implicating TUSC5 as a positive regulator of insulin-stimulated glucose transport in adipocytes. Incubation of adipocytes with TNFα caused insulin resistance and a concomitant reduction in TUSC5. Consistent with previous studies, peroxisome proliferator-activated receptor (PPAR) γ agonism reversed TNFα-induced insulin resistance. TUSC5 expression was necessary but insufficient for PPARγ-mediated reversal of insulin resistance. These findings functionally link TUSC5 to GLUT4 trafficking, insulin action, insulin resistance, and PPARγ action in the adipocyte. Further studies are required to establish the exact role of TUSC5 in adipocytes. PMID:26240143

  15. Proteomic Analysis of GLUT4 Storage Vesicles Reveals Tumor Suppressor Candidate 5 (TUSC5) as a Novel Regulator of Insulin Action in Adipocytes.

    PubMed

    Fazakerley, Daniel J; Naghiloo, Sheyda; Chaudhuri, Rima; Koumanov, Françoise; Burchfield, James G; Thomas, Kristen C; Krycer, James R; Prior, Matthew J; Parker, Ben L; Murrow, Beverley A; Stöckli, Jacqueline; Meoli, Christopher C; Holman, Geoffrey D; James, David E

    2015-09-25

    Insulin signaling augments glucose transport by regulating glucose transporter 4 (GLUT4) trafficking from specialized intracellular compartments, termed GLUT4 storage vesicles (GSVs), to the plasma membrane. Proteomic analysis of GSVs by mass spectrometry revealed enrichment of 59 proteins in these vesicles. We measured reduced abundance of 23 of these proteins following insulin stimulation and assigned these as high confidence GSV proteins. These included established GSV proteins such as GLUT4 and insulin-responsive aminopeptidase, as well as six proteins not previously reported to be localized to GSVs. Tumor suppressor candidate 5 (TUSC5) was shown to be a novel GSV protein that underwent a 3.7-fold increase in abundance at the plasma membrane in response to insulin. siRNA-mediated knockdown of TUSC5 decreased insulin-stimulated glucose uptake, although overexpression of TUSC5 had the opposite effect, implicating TUSC5 as a positive regulator of insulin-stimulated glucose transport in adipocytes. Incubation of adipocytes with TNFα caused insulin resistance and a concomitant reduction in TUSC5. Consistent with previous studies, peroxisome proliferator-activated receptor (PPAR) γ agonism reversed TNFα-induced insulin resistance. TUSC5 expression was necessary but insufficient for PPARγ-mediated reversal of insulin resistance. These findings functionally link TUSC5 to GLUT4 trafficking, insulin action, insulin resistance, and PPARγ action in the adipocyte. Further studies are required to establish the exact role of TUSC5 in adipocytes.

  16. Angiopoietin-like 2, a circadian gene, improves type 2 diabetes through potentiation of insulin sensitivity in mice adipocytes.

    PubMed

    Kitazawa, Masashi; Nagano, Mamoru; Masumoto, Koh-Hei; Shigeyoshi, Yasufumi; Natsume, Tohru; Hashimoto, Seiichi

    2011-07-01

    Angiopoietin-like (Angptl)2, a member of the Angptl protein family, is predominantly secreted from adipose tissue and the heart. Here, we demonstrate that the expression of Angptl2 in epididymal adipose tissue of C57BL/6J mice shows pulsatility and circadian rhythmicity and that the rhythmicity was disrupted in high-fat-fed and leptin receptor-deficient diabetic db/db mice with insulin resistance. To investigate whether the reduction in Angptl2 expression was related to the progression of diabetes, we treated db/db mice with recombinant Angptl2 for 4 wk during the peak period of Angptl2 expression in C57BL/6J mice. Angptl2-treated mice showed decreases in plasma glucose, insulin, triglyceride, and fatty acid levels and an increase in plasma adiponectin, a therapeutic regulator of insulin resistance, leading to improvements in glucose tolerance. In cultured adipocytes, recombinant Angptl2 increased adiponectin expression and stimulated insulin sensitivity partially by reducing the levels of tribbles homolog 3, a specific Akt kinase inhibitory protein. Conversely, Angptl2 small interfering RNA reduced adiponectin expression, resulting in insulin resistance. In preadipocytes, treatment with Angptl2 small interfering RNA inhibited differentiation to adipocytes and reduced adiponectin expression. Taken together, our results suggest that replenishment of Angptl2 stimulates insulin sensitivity and improves the type 2 diabetic state.

  17. Optogenetic activation reveals distinct roles of PIP3 and Akt in adipocyte insulin action.

    PubMed

    Xu, Yingke; Nan, Di; Fan, Jiannan; Bogan, Jonathan S; Toomre, Derek

    2016-05-15

    Glucose transporter 4 (GLUT4; also known as SLC2A4) resides on intracellular vesicles in muscle and adipose cells, and translocates to the plasma membrane in response to insulin. The phosphoinositide 3-kinase (PI3K)-Akt signaling pathway plays a major role in GLUT4 translocation; however, a challenge has been to unravel the potentially distinct contributions of PI3K and Akt (of which there are three isoforms, Akt1-Akt3) to overall insulin action. Here, we describe new optogenetic tools based on CRY2 and the N-terminus of CIB1 (CIBN). We used these 'Opto' modules to activate PI3K and Akt selectively in time and space in 3T3-L1 adipocytes. We validated these tools using biochemical assays and performed live-cell kinetic analyses of IRAP-pHluorin translocation (IRAP is also known as LNPEP and acts as a surrogate marker for GLUT4 here). Strikingly, Opto-PIP3 largely mimicked the maximal effects of insulin stimulation, whereas Opto-Akt only partially triggered translocation. Conversely, drug-mediated inhibition of Akt only partially dampened the translocation response of Opto-PIP3 In spatial optogenetic studies, focal targeting of Akt to a region of the cell marked the sites where IRAP-pHluorin vesicles fused, supporting the idea that local Akt-mediated signaling regulates exocytosis. Taken together, these results indicate that PI3K and Akt play distinct roles, and that PI3K stimulates Akt-independent pathways that are important for GLUT4 translocation.

  18. Hyperglycemia Potentiates H2O2 Production in Adipocytes and Enhances Insulin Signal Transduction: Potential Role for Oxidative Inhibition of Thiol-Sensitive Protein-Tyrosine Phosphatases

    PubMed Central

    WU, XIANGDONG; ZHU, LI; ZILBERING, ASSAF; MAHADEV, KALYANKAR; MOTOSHIMA, HIROYUKI; YAO, JUNLI; GOLDSTEIN, BARRY J.

    2006-01-01

    Insulin signal transduction in adipocytes is accompanied by a burst of cellular hydrogen peroxide (H2O2 facilitates insulin signaling by inhibiting thiol-dependent protein-tyrosine phosphatases (PTPs)) that are negative regulators of insulin action. As hyperglycemia is associated with increased cellular reactive oxygen species, we postulated that high glucose conditions might potentiate the H2O2 generated by insulin and modulate insulin-stimulated protein phosphorylation. Basal H2O2 generation was increased threefold in differentiated 3T3-L1 adipocytes by growth in 25 mM glucose versus 5 mM glucose. High glucose increased the sensitivity of the insulin-stimulated H2O2 signal to lower concentrations of insulin. Basal endogenous total PTP activity and the activity of PTP1B, a PTP implicated in the negative regulation of insulin signaling, were reduced in high glucose conditions, and their further reduction by insulin stimulation was more enhanced in high versus low glucose medium. Phosphorylation of the insulin receptor, IRS-1, and Akt in response to insulin was also significantly enhanced in high glucose conditions, especially at submaximal insulin concentrations. In primary rat adipocytes, high glucose increased insulin-stimulated H2O2 the oxidative inhibition of total PTP production and potentiated and PTP1B activity; however, insulin signaling was not enhanced in the primary cells in high glucose apparently due to cross-regulation of insulin-stimulated protein phosphorylation by activation of protein kinase C (PKC). These studies indicate that high glucose can enhance insulin-stimulated H2O2 generation and augment oxidative PTP inhibition in cultured and primary adipocytes, but the overall balance of insulin signal transduction is determined by additional signal effects in high glucose, including the activation of PKC. PMID:15889998

  19. Cyanidin-3-glucoside derived from black soybeans ameliorate type 2 diabetes through the induction of differentiation of preadipocytes into smaller and insulin-sensitive adipocytes.

    PubMed

    Matsukawa, Toshiya; Inaguma, Tetsuya; Han, Junkyu; Villareal, Myra O; Isoda, Hiroko

    2015-08-01

    Black soybean is a health food has been reported to have antidiabetes effect. The onset of diabetes is closely associated with adipocyte differentiation, and at present, the effect of black soybean on adipocyte differentiation is unknown. Here, we investigated the antidiabetes effect of black soybean, and its anthocyanin cyanidin-3-glucoside (Cy3G), on adipocyte differentiation. Orally administered black soybean seed coat extract (BSSCE) reduced the body and white adipose tissue (WAT) weight of db/db mice accompanied by a decrease in the size of adipocytes in WAT. Furthermore, 3T3-Ll cells treated with BSSCE and Cy3G were observed to differentiate into smaller adipocytes which correlated with increased PPARγ and C/EBPα gene expressions, increased adiponectin secretion, decreased tumor necrosis factor-α secretion, activation of insulin signalling and increased glucose uptake. C2C12 myotubes cultured with conditioned medium, obtained from 3T3-L1 adipocyte cultures treated with Cy3G, also showed significantly increased expression of PGC-1α, SIRT1 and UCP-3 genes. Here we report that BSSCE, as well as its active compound Cy3G, has antidiabetes effects on db/db mice by promoting adipocyte differentiation. This notion is supported by BSSCE and Cy3G inducing the differentiation of 3T3-L1 preadipocytes into smaller, insulin-sensitive adipocytes, and it induced the activation of skeletal muscle metabolism. This is the first report on the modulation effect of Cy3G on adipocyte differentiation.

  20. Bixin regulates mRNA expression involved in adipogenesis and enhances insulin sensitivity in 3T3-L1 adipocytes through PPAR{gamma} activation

    SciTech Connect

    Takahashi, Nobuyuki; Goto, Tsuyoshi; Taimatsu, Aki; Egawa, Kahori; Katoh, Sota; Kusudo, Tatsuya; Sakamoto, Tomoya; Ohyane, Chie; Lee, Joo-Young; Kim, Young-il; Uemura, Taku; Hirai, Shizuka; Kawada, Teruo

    2009-12-25

    Insulin resistance is partly due to suppression of insulin-induced glucose uptake into adipocytes. The uptake is dependent on adipocyte differentiation, which is controlled at mRNA transcription level. The peroxisome proliferator-activated receptor (PPAR), a ligand-regulated nuclear receptor, is involved in the differentiation. Many food-derived compounds serve as ligands to activate or inactivate PPAR. In this study, we demonstrated that bixin and norbixin (annatto extracts) activate PPAR{gamma} by luciferase reporter assay using GAL4-PPAR chimera proteins. To examine the effects of bixin on adipocytes, 3T3-L1 adipocytes were treated with bixin or norbixin. The treatment induced mRNA expression of PPAR{gamma} target genes such as adipocyte-specific fatty acid-binding protein (aP2), lipoprotein lipase (LPL), and adiponectin in differentiated 3T3-L1 adipocytes and enhanced insulin-dependent glucose uptake. The observations indicate that bixin acts as an agonist of PPAR{gamma} and enhances insulin sensitivity in 3T3-L1 adipocytes, suggesting that bixin is a valuable food-derived compound as a PPAR ligand to regulate lipid metabolism and to ameliorate metabolic syndrome.

  1. Cholesterol depletion blocks redistribution of lipid raft components and insulin-mimetic signaling by glimepiride and phosphoinositolglycans in rat adipocytes.

    PubMed Central

    Müller, Gunter; Hanekop, Nils; Wied, Susanne; Frick, Wendelin

    2002-01-01

    Glycosylphosphatidylinositol-anchored plasma membrane (GPI) proteins, such as Gce1, the dually acylated nonreceptor tyrosine kinases (NRTKs), such as pp59(Lyn), and the membrane protein, caveolin, together with cholesterol are typical components of detergent/carbonate-insoluble glycolipid-enriched raft domains (DIGs) in the plasma membrane of most eucaryotes. Previous studies demonstrated the dissociation from caveolin and concomitant redistribution from DIGs of Gce1 and pp59(Lyn) in rat adipocytes in response to four different insulin-mimetic stimuli, glimepiride, phosphoinositolglycans, caveolin-binding domain peptide, and trypsin/NaCl-treatment. We now characterized the structural basis for this dynamic of DIG components. MATERIALS AND METHODS: Carbonate extracts from purified plasma membranes of basal and stimulated adipocytes were analyzed by high-resolution sucrose gradient centrifugation. RESULTS: This process revealed the existence of two distinct species of detergent/carbonate-insoluble complexes floating at higher buoyant density and harboring lower amounts of cholesterol, caveolin, GPI proteins, and NRTKs (lcDIGs) compared to typical DIGs of high cholesterol content (hcDIGs). The four insulin-mimetic stimuli decreased by 40-70% and increased by 2.5- to 5-fold the amounts of GPI proteins and NRTKs at hcDIGs and lcDIGs, respectively. Cholesterol depletion of adipocytes per se by incubation with methyl-beta-cyclodextrin or cholesterol oxidase also caused translocation of GPI proteins and NRTKs from hcDIGs to lcDIGs and their release from caveolin in reversible fashion without concomitant induction of insulin-mimetic signaling. Cholesterol depletion, however, reduced by 50-60% the stimulus-induced translocation as well as dissociation from hcDIGs-associated caveolin of GPI proteins and NRTKs, activation of NRTKs as well as insulin-mimetic signaling and metabolic action. In contrast, insulin-mimetic signaling induced by vanadium compounds was not

  2. Regulation of myosin IIA and filamentous actin during insulin-stimulated glucose uptake in 3T3-L1 adipocytes

    SciTech Connect

    Stall, Richard; Ramos, Joseph; Kent Fulcher, F.; Patel, Yashomati M.

    2014-03-10

    Insulin stimulated glucose uptake requires the colocalization of myosin IIA (MyoIIA) and the insulin-responsive glucose transporter 4 (GLUT4) at the plasma membrane for proper GLUT4 fusion. MyoIIA facilitates filamentous actin (F-actin) reorganization in various cell types. In adipocytes F-actin reorganization is required for insulin-stimulated glucose uptake. What is not known is whether MyoIIA interacts with F-actin to regulate insulin-induced GLUT4 fusion at the plasma membrane. To elucidate the relationship between MyoIIA and F-actin, we examined the colocalization of MyoIIA and F-actin at the plasma membrane upon insulin stimulation as well as the regulation of this interaction. Our findings demonstrated that MyoIIA and F-actin colocalized at the site of GLUT4 fusion with the plasma membrane upon insulin stimulation. Furthermore, inhibition of MyoII with blebbistatin impaired F-actin localization at the plasma membrane. Next we examined the regulatory role of calcium in MyoIIA-F-actin colocalization. Reduced calcium or calmodulin levels decreased colocalization of MyoIIA and F-actin at the plasma membrane. While calcium alone can translocate MyoIIA it did not stimulate F-actin accumulation at the plasma membrane. Taken together, we established that while MyoIIA activity is required for F-actin localization at the plasma membrane, it alone is insufficient to localize F-actin to the plasma membrane. - Highlights: • Insulin induces colocalization of MyoIIA and F-actin at the cortex in adipocytes. • MyoIIA is necessary but not sufficient to localize F-actin at the cell cortex. • MyoIIA-F-actin colocalization is regulated by calcium and calmodulin.

  3. Biological effects of THC and a lipophilic cannabis extract on normal and insulin resistant 3T3-L1 adipocytes.

    PubMed

    Gallant, M; Odei-Addo, F; Frost, C L; Levendal, R-A

    2009-10-01

    Type 2 diabetes, a chronic disease, affects about 150 million people world wide. It is characterized by insulin resistance of peripheral tissues such as liver, skeletal muscle, and fat. Insulin resistance is associated with elevated levels of tumor necrosis factor alpha (TNF-alpha), which in turn inhibits insulin receptor tyrosine kinase autophosphorylation. It has been reported that cannabis is used in the treatment of diabetes. A few reports indicate that smoking cannabis can lower blood glucose in diabetics. Delta(9)-tetrahydrocannabinol (THC) is the primary psychoactive component of cannabis. This study aimed to determine the effect of a lipophilic cannabis extract on adipogenesis, using 3T3-L1 cells, and to measure its effect on insulin sensitivity in insulin resistant adipocytes. Cells were cultured in Dulbecco's modified eagle medium (DMEM) with 10% fetal bovine serum (FBS) and differentiated over a 3 day period for all studies. In the adipogenesis studies, differentiated cells were exposed to the extract in the presence and absence of insulin. Lipid content and glucose uptake was subsequently measured. Insulin-induced glucose uptake increased, while the rate of adipogenesis decreased with increasing THC concentration. Insulin-resistance was induced using TNF-alpha, exposed to the extract and insulin-induced glucose uptake measured. Insulin-induced glucose was increased in these cells after exposure to the extract. Semiquantitative real time polymerase chain reaction (RT-PCR) was performed after ribonucleic acid (RNA) extraction to evaluate the effects of the extract on glucose transporter isotype 4 (GLUT-4), insulin receptor substrate-1 (IRS-1) and IRS-2 gene expression.

  4. SEC16A is a RAB10 effector required for insulin-stimulated GLUT4 trafficking in adipocytes

    PubMed Central

    Bruno, Joanne; Chaudhary, Natasha; Iaea, David

    2016-01-01

    RAB10 is a regulator of insulin-stimulated translocation of the GLUT4 glucose transporter to the plasma membrane (PM) of adipocytes, which is essential for whole-body glucose homeostasis. We establish SEC16A as a novel RAB10 effector in this process. Colocalization of SEC16A with RAB10 is augmented by insulin stimulation, and SEC16A knockdown attenuates insulin-induced GLUT4 translocation, phenocopying RAB10 knockdown. We show that SEC16A and RAB10 promote insulin-stimulated mobilization of GLUT4 from a perinuclear recycling endosome/TGN compartment. We propose RAB10–SEC16A functions to accelerate formation of the vesicles that ferry GLUT4 to the PM during insulin stimulation. Because GLUT4 continually cycles between the PM and intracellular compartments, the maintenance of elevated cell-surface GLUT4 in the presence of insulin requires accelerated biogenesis of the specialized GLUT4 transport vesicles. The function of SEC16A in GLUT4 trafficking is independent of its previously characterized activity in ER exit site formation and therefore independent of canonical COPII-coated vesicle function. However, our data support a role for SEC23A, but not the other COPII components SEC13, SEC23B, and SEC31, in the insulin stimulation of GLUT4 trafficking, suggesting that vesicles derived from subcomplexes of COPII coat proteins have a role in the specialized trafficking of GLUT4. PMID:27354378

  5. SEC16A is a RAB10 effector required for insulin-stimulated GLUT4 trafficking in adipocytes.

    PubMed

    Bruno, Joanne; Brumfield, Alexandria; Chaudhary, Natasha; Iaea, David; McGraw, Timothy E

    2016-07-04

    RAB10 is a regulator of insulin-stimulated translocation of the GLUT4 glucose transporter to the plasma membrane (PM) of adipocytes, which is essential for whole-body glucose homeostasis. We establish SEC16A as a novel RAB10 effector in this process. Colocalization of SEC16A with RAB10 is augmented by insulin stimulation, and SEC16A knockdown attenuates insulin-induced GLUT4 translocation, phenocopying RAB10 knockdown. We show that SEC16A and RAB10 promote insulin-stimulated mobilization of GLUT4 from a perinuclear recycling endosome/TGN compartment. We propose RAB10-SEC16A functions to accelerate formation of the vesicles that ferry GLUT4 to the PM during insulin stimulation. Because GLUT4 continually cycles between the PM and intracellular compartments, the maintenance of elevated cell-surface GLUT4 in the presence of insulin requires accelerated biogenesis of the specialized GLUT4 transport vesicles. The function of SEC16A in GLUT4 trafficking is independent of its previously characterized activity in ER exit site formation and therefore independent of canonical COPII-coated vesicle function. However, our data support a role for SEC23A, but not the other COPII components SEC13, SEC23B, and SEC31, in the insulin stimulation of GLUT4 trafficking, suggesting that vesicles derived from subcomplexes of COPII coat proteins have a role in the specialized trafficking of GLUT4.

  6. Systems-wide Experimental and Modeling Analysis of Insulin Signaling through Forkhead Box Protein O1 (FOXO1) in Human Adipocytes, Normally and in Type 2 Diabetes.

    PubMed

    Rajan, Meenu Rohini; Nyman, Elin; Kjølhede, Preben; Cedersund, Gunnar; Strålfors, Peter

    2016-07-22

    Insulin resistance is a major aspect of type 2 diabetes (T2D), which results from impaired insulin signaling in target cells. Signaling to regulate forkhead box protein O1 (FOXO1) may be the most important mechanism for insulin to control transcription. Despite this, little is known about how insulin regulates FOXO1 and how FOXO1 may contribute to insulin resistance in adipocytes, which are the most critical cell type in the development of insulin resistance. We report a detailed mechanistic analysis of insulin control of FOXO1 in human adipocytes obtained from non-diabetic subjects and from patients with T2D. We show that FOXO1 is mainly phosphorylated through mTORC2-mediated phosphorylation of protein kinase B at Ser(473) and that this mechanism is unperturbed in T2D. We also demonstrate a cross-talk from the MAPK branch of insulin signaling to stimulate phosphorylation of FOXO1. The cellular abundance and consequently activity of FOXO1 are halved in T2D. Interestingly, inhibition of mTORC1 with rapamycin reduces the abundance of FOXO1 to the levels in T2D. This suggests that the reduction of the concentration of FOXO1 is a consequence of attenuation of mTORC1, which defines much of the diabetic state in human adipocytes. We integrate insulin control of FOXO1 in a network-wide mathematical model of insulin signaling dynamics based on compatible data from human adipocytes. The diabetic state is network-wide explained by attenuation of an mTORC1-to-insulin receptor substrate-1 (IRS1) feedback and reduced abundances of insulin receptor, GLUT4, AS160, ribosomal protein S6, and FOXO1. The model demonstrates that attenuation of the mTORC1-to-IRS1 feedback is a major mechanism of insulin resistance in the diabetic state.

  7. Evodiamine Inhibits Insulin-Stimulated mTOR-S6K Activation and IRS1 Serine Phosphorylation in Adipocytes and Improves Glucose Tolerance in Obese/Diabetic Mice

    PubMed Central

    Wang, Ting; Kusudo, Tatsuya; Takeuchi, Tamaki; Yamashita, Yukari; Kontani, Yasuhide; Okamatsu, Yuko; Saito, Masayuki; Mori, Nozomu; Yamashita, Hitoshi

    2013-01-01

    Evodiamine, an alkaloid extracted from the dried unripe fruit of the tree Evodia rutaecarpa Bentham (Rutaceae), reduces obesity and insulin resistance in obese/diabetic mice; however, the mechanism underlying the effect of evodiamine on insulin resistance is unknown. This study investigated the effect of evodiamine on signal transduction relating to insulin resistance using obese/diabetic KK-Ay mice and an in vitro adipocyte culture. There is a significant decrease in the mammalian target of rapamycin (mTOR) and ribosomal S6 protein kinase (S6K) signaling in white adipose tissue (WAT) in KK-Ay mice treated with evodiamine, in which glucose tolerance is improved. In addition, reduction of insulin receptor substrate 1 (IRS1) serine phosphorylation, an indicator of insulin resistance, was detected in their WAT, suggesting suppression of the negative feedback loop from S6K to IRS1. As well as the stimulation of IRS1 and Akt serine phosphorylation, insulin-stimulated phosphorylation of mTOR and S6K is time-dependent in 3T3-L1 adipocytes, whereas evodiamine does not affect their phosphorylation except for an inhibitory effect on mTOR phosphorylation. Moreover, evodiamine inhibits the insulin-stimulated phosphorylation of mTOR and S6K, leading to down-regulation of IRS1 serine phosphorylation in the adipocytes. Evodiamine also stimulates phosphorylation of AMP-activated protein kinase (AMPK), an important regulator of energy metabolism, which may cause down-regulation of mTOR signaling in adipocytes. A similar effect on AMPK, mTOR and IRS1 phosphorylation was found in adipocytes treated with rosiglitazone. These results suggest evodiamine improves glucose tolerance and prevents the progress of insulin resistance associated with obese/diabetic states, at least in part, through inhibition of mTOR-S6K signaling and IRS1 serine phosphorylation in adipocytes. PMID:24391749

  8. [8-hydroxy-dihydroberberine ameliorated insulin resistance induced by high FFA and high glucose in 3T3-L1 adipocytes].

    PubMed

    Xu, Li-jun; Lu, Fu-er; Yi, Ping; Wang, Zeng-si; Wei, Shi-chao; Chen, Guang; Dong, Hui; Zou, Xin

    2009-11-01

    The purpose of the study is to investigate the effect of 8-hydroxy-dihydroberberine on insulin resistance induced by high free fatty acid (FFA) and high glucose in 3T3-L1 adipocytes and its possible molecular mechanism. Palmic acid or glucose in combination with insulin was used to induce insulin resistance in 3T3-L1 adipocytes. 8-Hydroxy-dihydroberberine and berberine were added to the cultured medium separately, which were considered as treated group and positive control group. The rate of glucose uptake was determined by 2-deoxy-[3H]-D-glucose method. The amount of glucose consumption in the medium was measured by glucose oxidase method. Cell growth and proliferation of 3T3-L1 adipocytes were detected with Cell Counting Kit-8 (CCK-8) assay. After incubated with palmic acid for 24 hours or glucose with insulin for 18 hours, the rate of glucose transport in 3T3-L1 adipocytes was inhibited by 67% and 58%, respectively. The amount of glucose consumption in 3T3-L1 adipose cells was decreased by 41% after cells were incubated with palmic acid for 24 h. However, the above changes were reversed by pretreatment with 8-hydroxy-dihydroberberine for 24 and 48 h. Significant difference existed between groups. Insulin resistance in 3T3-L1 adipocytes, which is induced by high FFA and high glucose, could be ameliorated by 8-hydroxy-dihydroberberine.

  9. Isoliquiritigenin impairs insulin signaling and adipocyte differentiation through the inhibition of protein-tyrosine phosphatase 1B oxidation in 3T3-L1 preadipocytes.

    PubMed

    Park, Sun-Ji; Choe, Young-Geun; Kim, Jung-Hak; Chang, Kyu-Tae; Lee, Hyun-Shik; Lee, Dong-Seok

    2016-07-01

    Isoliquritigenin (ISL) is an abundant dietary flavonoid with a chalcone structure, which is an important constituent in Glycyrrhizae Radix (GR). ISL exhibits anti-oxidant activity, and this activity has been shown to play a beneficial role in various health conditions. However, it is unclear whether the anti-oxidant activity of ISL affects insulin signaling pathway and lipid accumulation of adipocytes. We sought to investigate the effects and molecular mechanisms of ISL on insulin-stimulated adipogenesis in 3T3-L1 cells. We investigated whether ISL attenuates insulin-induced Reactive Oxygen Species (ROS) generation, and whether ISL inhibits the lipid accumulation and the expression of adipogenic-genes during the differentiation of 3T3-L1 cells. ISL blocked the ROS generation, suppressed the lipid accumulation and the expression of adipocyte-specific proteins, which are increased in response to insulin stimulation during adipocyte differentiation of 3T3-L1 cells. We also investigated whether the anti-oxidant capacity of ISL is involved in regulating the molecular events of insulin-signaling cascade in 3T3-L1 adipocytes. ISL restores PTP1B activity by inhibiting PTP1B oxidation and IR/PI3K/AKT phosphorylation during the early stages of insulin-induced adipogenesis. Our findings show that the anti-oxidant capacity of ISL attenuated insulin IR/PI3K/AKT signaling through inhibition of PTP1B oxidation, and ultimately attenuated insulin-induced adipocyte differentiation of 3T3-L1 cells.

  10. Melatonin rescues 3T3-L1 adipocytes from FFA-induced insulin resistance by inhibiting phosphorylation of IRS-1 on Ser307.

    PubMed

    She, Meihua; Hou, Hongjie; Wang, Zongbao; Zhang, Chi; Laudon, Moshe; Yin, Weidong

    2014-08-01

    Melatonin is biosynthesized in the pineal gland and secreted into the bloodstream. Evidences indicate a role of melatonin in the regulation of glucose metabolism. The objective of this study was to investigate the effect of melatonin on insulin sensitivity in insulin resistant adipocytes. Following a preincubation with melatonin or vehicle for 30 min, insulin resistant cells of 3T3-L1 adipocytes were induced by palmitic acids (300 μM, 6 h). Our results showed that palmitic acids inhibited both the basal and insulin-stimulated uptake of [(3)H]-2-Deoxyglucose, down-regulated the levels of IRS-1 and GLUT-4. However, compared to the vehicle group, melatonin pre-treatment increased significantly the uptake of [(3)H]-2-Deoxyglucose as well as the level of GLUT-4, and decreased phosphorylated IRS-1 (Ser307) although total IRS-1 did not change significantly. These data suggest that palmitic acids impair insulin signal via down-regulating the expressions of IRS-1 and GLUT-4; whereas melatonin can ameliorate insulin sensitivity by inhibiting Ser307 phosphorylation in IRS-1 and increasing GLUT-4 expressions in insulin resistant 3T3-L1 adipocytes. We conclude that melatonin regulates the insulin sensitivity and glucose homeostasis via inhibiting Ser-phosphorylation and improving function of IRS-1.

  11. Adipocyte and adipogenesis.

    PubMed

    Ali, Aus Tariq; Hochfeld, Warren E; Myburgh, Renier; Pepper, Michael S

    2013-01-01

    Adipocytes are the main constituent of adipose tissue and are considered to be a corner stone in the homeostatic control of whole body metabolism. Their primary function is to control energy balance by storing triacylglycerol in periods of energy excess and mobilizing it during energy deprivation. Besides the classical function of storing fat, adipocytes secrete numerous lipid and protein factors. Collectively they are considered to constitute a major endocrine organ which has a profound impact on the metabolism of other tissues, the regulation of appetite, insulin sensitivity, immunological responses and vascular disease. Adipogenesis is the process during which fibroblast like preadipocytes developed into mature adipocytes. Adipogenesis is a well-orchestrated multistep process that requires the sequential activation of numerous transcription factors, including the CCAAT/enhancer-binding protein (C/EBP) gene family and peroxisome proliferator activated receptor-γ (PPAR-γ). In order to reach maturity, these cells must go through two vital steps: adipocyte determination and adipocyte differentiation. Although many of the molecular details of adipogenesis are still unknown, several factors involved in this processes have been identified. Some stimulators include peroxisome proliferator-activated receptor γ (PPAR γ), insulin-like growth factor I (IGF-l), macrophage colony stimulating factor, fatty acids, prostaglandins and glucocorticoids. Inhibitors include glycoproteins, transforming growth factor-β (TGF-β), inflammatory cytokines and growth hormone. Beside these factors, there are others for example age, gender and life style that may affect this process in one way or another. An increase in the number and size of adipocytes causes white adipose tissue (WAT) to expand and this can lead to obesity. Adipogenesis can lead to central obesity if it occurs in the abdominal fat depot and peripheral obesity if it occurs in subcutaneous tissue.

  12. Cinnamon extract exhibits insulin-like and independent effects on gene expression in adipocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cinnamon is beneficial to people with insulin resistance due in part to the insulin-like activity of the cinnamon extract (CE). Molecular effects of CE are limited. This study tested the hypothesis that CE has insulin-like and insulin-independent effects at the molecular level. Quantitative real-tim...

  13. β-Catenin Directly Sequesters Adipocytic and Insulin Sensitizing Activities but Not Osteoblastic Activity of PPARγ2 in Marrow Mesenchymal Stem Cells

    PubMed Central

    Rahman, Sima; Czernik, Piotr J.; Lu, Yalin; Lecka-Czernik, Beata

    2012-01-01

    Lineage allocation of the marrow mesenchymal stem cells (MSCs) to osteoblasts and adipocytes is dependent on both Wnt signaling and PPARγ2 activity. Activation of PPARγ2, an essential regulator of energy metabolism and insulin sensitivity, stimulates adipocyte and suppresses osteoblast differentiation and bone formation, and correlates with decreased bone mass and increased fracture rate. In contrast, activation of Wnt signaling promotes osteoblast differentiation, augments bone accrual and reduces total body fat. This study examined the cross-talk between PPARγ2 and β-catenin, a key mediator of canonical Wnt signaling, on MSC lineage determination. Rosiglitazone-activated PPARγ2 induced rapid proteolytic degradation of β-catenin, which was prevented by either inhibiting glycogen synthase kinase 3 beta (GSK3β) activity, or blocking pro-adipocytic activity of PPARγ2 using selective antagonist GW9662 or mutation within PPARγ2 protein. Stabilization of β-catenin suppressed PPARγ2 pro-adipocytic but not anti-osteoblastic activity. Moreover, β-catenin stabilization decreased PPARγ2-mediated insulin signaling as measured by insulin receptor and FoxO1 gene expression, and protein levels of phosphorylated Akt (pAkt). Cellular knockdown of β-catenin with siRNA increased expression of adipocyte but did not affect osteoblast gene markers. Interestingly, the expression of Wnt10b was suppressed by anti-osteoblastic, but not by pro-adipocytic activity of PPARγ2. Moreover, β-catenin stabilization in the presence of activated PPARγ2 did not restore Wnt10b expression indicating a dominant role of PPARγ2 in negative regulation of pro-osteoblastic activity of Wnt signaling. In conclusion, β-catenin and PPARγ2 are in cross-talk which results in sequestration of pro-adipocytic and insulin sensitizing activity. The anti-osteoblastic activity of PPARγ2 is independent of this interaction. PMID:23272157

  14. Terminal Galactosylation and Sialylation Switching on Membrane Glycoproteins upon TNF-Alpha-Induced Insulin Resistance in Adipocytes*

    PubMed Central

    Parker, Benjamin L.; Thaysen-Andersen, Morten; Fazakerley, Daniel J.; Holliday, Mira; Packer, Nicolle H.; James, David E.

    2016-01-01

    Insulin resistance (IR) is a complex pathophysiological state that arises from both environmental and genetic perturbations and leads to a variety of diseases, including type-2 diabetes (T2D). Obesity is associated with enhanced adipose tissue inflammation, which may play a role in disease progression. Inflammation modulates protein glycosylation in a variety of cell types, and this has been associated with biological dysregulation. Here, we have examined the effects of an inflammatory insult on protein glycosylation in adipocytes. We performed quantitative N-glycome profiling of membrane proteins derived from mouse 3T3-L1 adipocytes that had been incubated with or without the proinflammatory cytokine TNF-alpha to induce IR. We identified the regulation of specific terminal N-glycan epitopes, including an increase in terminal di-galactose- and a decrease in biantennary alpha-2,3-sialoglycans. The altered N-glycosylation of TNF-alpha-treated adipocytes correlated with the regulation of specific glycosyltransferases, including the up-regulation of B4GalT5 and Ggta1 galactosyltransferases and down-regulation of ST3Gal6 sialyltransferase. Knockdown of B4GalT5 down-regulated the terminal di-galactose N-glycans, confirming the involvement of this enzyme in the TNF-alpha-regulated N-glycome. SILAC-based quantitative glycoproteomics of enriched N-glycopeptides with and without deglycosylation were used to identify the protein and glycosylation sites modified with these regulated N-glycans. The combined proteome and glycoproteome workflow provided a relative quantification of changes in protein abundance versus N-glycosylation occupancy versus site-specific N-glycans on a proteome-wide level. This revealed the modulation of N-glycosylation on specific proteins in IR, including those previously associated with insulin-stimulated GLUT4 trafficking to the plasma membrane. PMID:26537798

  15. Bisphenol-A impairs insulin action and up-regulates inflammatory pathways in human subcutaneous adipocytes and 3T3-L1 cells.

    PubMed

    Valentino, Rossella; D'Esposito, Vittoria; Passaretti, Federica; Liotti, Antonietta; Cabaro, Serena; Longo, Michele; Perruolo, Giuseppe; Oriente, Francesco; Beguinot, Francesco; Formisano, Pietro

    2013-01-01

    Current evidence indicates that chemical pollutants may interfere with the homeostatic control of nutrient metabolism, thereby contributing to the increased prevalence of metabolic disorders. Bisphenol-A (BPA) is a lipophilic compound contained in plastic which is considered a candidate for impairing energy and glucose metabolism. We have investigated the impact of low doses of BPA on adipocyte metabolic functions. Human adipocytes derived from subcutaneous adipose tissue and differentiated 3T3-L1 cells were incubated with BPA, in order to evaluate the effect on glucose utilization, insulin sensitivity and cytokine secretion. Treatment with 1 nM BPA significantly inhibited insulin-stimulated glucose utilization, without grossly interfering with adipocyte differentiation. Accordingly, mRNA levels of the adipogenic markers PPARγ and GLUT4 were unchanged upon BPA exposure. BPA treatment also impaired insulin-activated receptor phosphorylation and signaling. Moreover, adipocyte incubation with BPA was accompanied by increased release of IL-6 and IFN-γ, as assessed by multiplex ELISA assays, and by activation of JNK, STAT3 and NFkB pathways. Treatment of the cells with the JNK inhibitor SP600125 almost fully reverted BPA effect on insulin signaling and glucose utilization. In conclusion, low doses of BPA interfere with inflammatory/insulin signaling pathways, leading to impairment of adipose cell function.

  16. C(2)-ceramide influences the expression and insulin-mediated regulation of cyclic nucleotide phosphodiesterase 3B and lipolysis in 3T3-L1 adipocytes.

    PubMed

    Mei, Jie; Holst, Lena Stenson; Landström, Tova Rahn; Holm, Cecilia; Brindley, David; Manganiello, Vincent; Degerman, Eva

    2002-03-01

    Cyclic nucleotide phosphodiesterase (PDE) 3B plays an important role in the antilipolytic action of insulin and, thereby, the release of fatty acids from adipocytes. Increased concentrations of circulating fatty acids as a result of elevated or unrestrained lipolysis cause insulin resistance. The lipolytic action of tumor necrosis factor (TNF)-alpha is thought to be one of the mechanisms by which TNF-alpha induces insulin resistance. Ceramide is the suggested second messenger of TNF-alpha action, and in this study, we used 3T3-L1 adipocytes to investigate the effects of C(2)-ceramide (a short-chain ceramide analog) on the expression and regulation of PDE3B and lipolysis. Incubation of adipocytes with 100 micromol/l C(2)-ceramide (N-acetyl-sphingosine) resulted in a time-dependent decrease of PDE3B activity, accompanied by decreased PDE3B protein expression. C(2)-ceramide, in a time- and dose-dependent manner, stimulated lipolysis, an effect that was blocked by H-89, an inhibitor of protein kinase A. These ceramide effects were prevented by 20 micromol/l troglitazone, an antidiabetic drug. In addition to downregulation of PDE3B, the antilipolytic action of insulin was decreased by ceramide treatment. These results, together with data from other studies on PDE3B and lipolysis in diabetic humans and animals, suggest a novel pathway by which ceramide induces insulin resistance. Furthermore, PDE3B is demonstrated to be a target for troglitazone action in adipocytes.

  17. Inhibiting insulin resistance mechanisms by DTS phytocompound: an experimental study on metabolic syndrome-prone adipocytes.

    PubMed

    Catanzaro, Roberto; Lorenzetti, Aldo; Allegri, Flavio; Yadav, Hariom; Solimene, Umberto; Kumaraju, Ajit K; Minelli, Emilio; Tomella, Claudio; Polimeni, Ascanio; Marotta, Francesco

    2012-08-01

    The present study was designed to determine whether DTS a phytocompound endowed with antioxidant properties, could beneficially modulate nitric oxide (NO) production stimulated by lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) in adipocytes. Combined stimulation (CS-treatment) exerted by using 5 microg/ml of LPS together with 100 ng/ml of TNF-alpha significantly enhanced NO production in 3T3-L1 adipocytes. Preincubation of the adipocytes with DTS (10-30 mM) inhibited such phenomenon in a dose-dependent fashion. The production of NO was decreased by 52% at the concentration of 30mM of DTS. The decrease in NO production by DTS was associated also with a decrease in inducible nitric oxide synthase (iNOS) protein and iNOS mRNA expression. Nuclear factor-kappa B (NF-kappaB) was significantly enhanced by CS-treatment, while the pretreatment with 30 mM of DTS prevented the activity by 27%. IL-6 production in 3T3-L1 adipocytes was markedly increased by CS stimulus, and the enhanced secretion of IL-6 was suppressed in a dose-dependent manner by DTS. These results suggest that DTS regulates iNOS expression and NO production in adipocytes through the modulating activation of NF-kappaB and may have a potential clinical application within protocols designed for treating metabolic syndrome. (www.actabiomedica.it).

  18. Verification of the antidiabetic effects of cinnamon (Cinnamomum zeylanicum) using insulin-uncontrolled type 1 diabetic rats and cultured adipocytes.

    PubMed

    Shen, Yan; Fukushima, Misato; Ito, Yoshimasa; Muraki, Etsuko; Hosono, Takashi; Seki, Taiichiro; Ariga, Toyohiko

    2010-01-01

    It has long been believed that an intake of cinnamon (Cinnamomum zeylanicum) alleviates diabetic pathological conditions. However, it is still controversial whether the beneficial effect is insulin-dependent or insulin-mimetic. This study was aimed at determining the insulin-independent effect of cinnamon. Streptozotocin-induced diabetic rats were divided into four groups and orally administered with an aqueous cinnamon extract (CE) for 22 d. The diabetic rats that had taken CE at a dose of more than 30 mg/kg/d were rescued from their hyperglycemia and nephropathy, and these rats were found to have upregulation of uncoupling protein-1 (UCP-1) and glucose transporter 4 (GLUT4) in their brown adipose tissues as well as in their muscles. This was verified by using 3T3-L1 adipocytes in which CE upregulates GLUT4 translocation and increases the glucose uptake. CE exhibited its anti-diabetic effect independently from insulin by at least two mechanisms: i) upregulation of mitochondrial UCP-1, and ii) enhanced translocation of GLUT4 in the muscle and adipose tissues.

  19. ROCK1 reduces mitochondrial content and irisin production in muscle suppressing adipocyte browning and impairing insulin sensitivity.

    PubMed

    Zhou, Xiaoshuang; Li, Rongshan; Liu, Xinyan; Wang, Lihua; Hui, Peng; Chan, Lawrence; Saha, Pradip K; Hu, Zhaoyong

    2016-07-14

    Irisin reportedly promotes the conversion of preadipocytes into "brown-like" adipocytes within subcutaneous white adipose tissue (WAT) via a mechanism that stimulates UCP-1 expression. An increase in plasma irisin has been associated with improved obesity and insulin resistance in mice with type 2 diabetes. But whether a low level of irisin stimulates the development of obesity has not been determined. In studying mice with muscle-specific constitutive ROCK1 activation (mCaROCK1), we found that irisin production was down-regulated and the mice developed obesity and insulin resistance. Therefore, we studied the effects of irisin deficiency on energy metabolism in mCaROCK1 mice. Constitutively activation of ROCK1 in muscle suppressed irisin expression in muscle resulting in a low level of irisin in circulation. Irisin deficiency reduced heat production and decreased the expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and subcutaneous WAT. Moreover, mCaROCK1 mice also displayed impaired glucose tolerance. Notably, irisin replenishment in mCaROCK1 mice partially reversed insulin resistance and obesity and these changes were associated with increased expression of UCP1 and Pref-1 in subcutaneous WAT. These results demonstrate that irisin mediates muscle-adipose tissue communication and regulates energy and glucose homeostasis. Irisin administration can correct obesity and insulin resistance in mice.

  20. ROCK1 reduces mitochondrial content and irisin production in muscle suppressing adipocyte browning and impairing insulin sensitivity

    PubMed Central

    Zhou, Xiaoshuang; Li, Rongshan; Liu, Xinyan; Wang, Lihua; Hui, Peng; Chan, Lawrence; Saha, Pradip K.; Hu, Zhaoyong

    2016-01-01

    Irisin reportedly promotes the conversion of preadipocytes into “brown-like” adipocytes within subcutaneous white adipose tissue (WAT) via a mechanism that stimulates UCP-1 expression. An increase in plasma irisin has been associated with improved obesity and insulin resistance in mice with type 2 diabetes. But whether a low level of irisin stimulates the development of obesity has not been determined. In studying mice with muscle-specific constitutive ROCK1 activation (mCaROCK1), we found that irisin production was down-regulated and the mice developed obesity and insulin resistance. Therefore, we studied the effects of irisin deficiency on energy metabolism in mCaROCK1 mice. Constitutively activation of ROCK1 in muscle suppressed irisin expression in muscle resulting in a low level of irisin in circulation. Irisin deficiency reduced heat production and decreased the expression of uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) and subcutaneous WAT. Moreover, mCaROCK1 mice also displayed impaired glucose tolerance. Notably, irisin replenishment in mCaROCK1 mice partially reversed insulin resistance and obesity and these changes were associated with increased expression of UCP1 and Pref-1 in subcutaneous WAT. These results demonstrate that irisin mediates muscle-adipose tissue communication and regulates energy and glucose homeostasis. Irisin administration can correct obesity and insulin resistance in mice. PMID:27411515

  1. The v-SNARE Vti1a regulates insulin-stimulated glucose transport and Acrp30 secretion in 3T3-L1 adipocytes.

    PubMed

    Bose, Avirup; Guilherme, Adilson; Huang, Shaohui; Hubbard, Andrea C; Lane, Charles R; Soriano, Neil A; Czech, Michael P

    2005-11-04

    Regulated exocytosis in adipocytes mediates key functions, exemplified by insulin-stimulated secretion of peptides such as adiponectin and recycling of intracellular membranes containing GLUT4 glucose transporters to the cell surface. Using a proteomics approach, the v-SNARE Vti1a (vps10p tail interacting 1a) was identified by mass spectrometry in purified GLUT4-containing membranes. Insulin treatment of 3T3-L1 adipocytes decreased the amounts of both Vti1a and GLUT4 in these membranes, confirming that Vti1a is a component of insulin-sensitive GLUT4-containing vesicles. In the basal state, endogenous Vti1a colocalizes exclusively with perinuclear GLUT4. Although Vti1a has previously been reported to be a v-SNARE localized in the trans-Golgi network, treatment with brefeldin A failed to significantly modify Vti1a or GLUT4 localization while completely dispersing Golgi and trans-Golgi network marker proteins. Furthermore, depletion of Vti1a protein in cultured adipocytes through small interfering RNA-based gene silencing significantly inhibited both adiponectin secretion and insulin-stimulated deoxyglucose uptake. Taken together, these results suggest that the v-SNARE Vti1a may regulate a step common to both GLUT4 and Acrp30 trafficking in 3T3-L1 adipocytes.

  2. The phosphatidylinositol 3-kinase inhibitor, wortmannin, inhibits insulin-induced activation of phosphatidylcholine hydrolysis and associated protein kinase C translocation in rat adipocytes.

    PubMed Central

    Standaert, M L; Avignon, A; Yamada, K; Bandyopadhyay, G; Farese, R V

    1996-01-01

    We questioned whether phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase C (PKC) function as interrelated signalling mechanisms during insulin action in rat adipocytes. Insulin rapidly activated a phospholipase D that hydrolyses phosphatidylcholine (PC), and this activation was accompanied by increases in diacylglycerol and translocative activation of PKC-alpha and PKC-beta in the plasma membrane. Wortmannin, an apparently specific PI 3-kinase inhibitor, inhibited insulin-stimulated, phospholipase D-dependent PC hydrolysis and subsequent translocation of PKC-alpha and PKC-beta to the plasma membrane. Wortmannin did not inhibit PKC directly in vitro, or the PKC-dependent effects of phorbol esters on glucose transport in intact adipocytes. The PKC inhibitor RO 31-8220 did not inhibit PI 3-kinase directly or its activation in situ by insulin, but inhibited both insulin-stimulated and phorbol ester-stimulated glucose transport. Our findings suggest that insulin acts through PI 3-kinase to activate a PC-specific phospholipase D and causes the translocative activation of PKC-alpha and PKC-beta in plasma membranes of rat adipocytes. PMID:8611143

  3. Actin filaments play a critical role in insulin-induced exocytotic recruitment but not in endocytosis of GLUT4 in isolated rat adipocytes.

    PubMed Central

    Omata, W; Shibata, H; Li, L; Takata, K; Kojima, I

    2000-01-01

    Actin-based cytoskeletons have been implicated in insulin-stimulated glucose transport and translocation of the insulin-regulated glucose transporter, GLUT4, from the intracellular pool to the plasma membrane. However, most previous studies were done using adherent cell systems such as L6 myotubes and 3T3-L1 adipocytes, and very little information is available on the significance of the actin filaments to the insulin action in isolated adipocytes, a widely used experimental system. In the present study, we investigated the physiological role of actin filaments in the subcellular trafficking of GLUT4 in isolated rat adipocytes. We first compared the effects of two actin-disrupting reagents, latrunculin A and cytochalasin D, on the organization of the actin filaments as well as on the insulin action on glucose transport by laser confocal microscopy combined with biochemical analysis of the insulin action. Treatment of the cells with latrunculin A induced dose- and time-dependent disappearance of the filamentous actin, which correlated very well with inhibition of the insulin effect on glucose transport. Although cytochalasin D at 50 microM significantly inhibited insulin-stimulated glucose transport, it was not effective in disassembly of the actin filaments; rather, many intense punctate signals were observed in cytochalasin D-treated cells. In the actin-disrupted adipocytes treated with latrunculin A, insulin-induced GLUT4 translocation was inhibited completely. In addition, latrunculin A remarkably inhibited both insulin-induced glucose transport and GLUT4 translocation in the presense of D(k)-(62-85), a potent inhibitor of GLUT4 endocytosis, suggesting that intactness of the actin filaments was necessary for insulin-induced exocytosis of the GLUT4-containing vesicles. On the other hand, latrunculin A showed little inhibitory effect on either endocytosis of the trypsin-cleaved 35-kDa fragment of GLUT4 or decay of the glucose transport activity after addition of

  4. Prolonged inorganic arsenite exposure suppresses insulin-stimulated AKT S473 phosphorylation and glucose uptake in 3T3-L1 adipocytes: Involvement of the adaptive antioxidant response

    SciTech Connect

    Xue, Peng; Hou, Yongyong; Zhang, Qiang; Woods, Courtney G.; Yarborough, Kathy; Liu, Huiyu; Sun, Guifan; Andersen, Melvin E.; Pi, Jingbo

    2011-04-08

    Highlights: {yields} In 3T3-L1 adipocytes iAs{sup 3+} decreases insulin-stimulated glucose uptake. {yields} iAs{sup 3+} attenuates insulin-induced phosphorylation of AKT S473. {yields} iAs{sup 3+} activates the cellular adaptive oxidative stress response. {yields} iAs{sup 3+} impairs insulin-stimulated ROS signaling. {yields} iAs{sup 3+} decreases expression of adipogenic genes and GLUT4. -- Abstract: There is growing evidence that chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with the incidence of type 2 diabetes (T2D). One critical feature of T2D is insulin resistance in peripheral tissues, especially in mature adipocytes, the hallmark of which is decreased insulin-stimulated glucose uptake (ISGU). Despite the deleterious effects of reactive oxygen species (ROS), they have been recognized as a second messenger serving an intracellular signaling role for insulin action. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central transcription factor regulating cellular adaptive response to oxidative stress. This study proposes that in response to arsenic exposure, the NRF2-mediated adaptive induction of endogenous antioxidant enzymes blunts insulin-stimulated ROS signaling and thus impairs ISGU. Exposure of differentiated 3T3-L1 cells to low-level (up to 2 {mu}M) inorganic arsenite (iAs{sup 3+}) led to decreased ISGU in a dose- and time-dependent manner. Concomitant to the impairment of ISGU, iAs{sup 3+} exposure significantly attenuated insulin-stimulated intracellular ROS accumulation and AKT S473 phosphorylation, which could be attributed to the activation of NRF2 and induction of a battery of endogenous antioxidant enzymes. In addition, prolonged iAs{sup 3+} exposure of 3T3-L1 adipocytes resulted in significant induction of inflammatory response genes and decreased expression of adipogenic genes and glucose transporter type 4 (GLUT4), suggesting chronic inflammation and reduction in GLUT4

  5. Amelioration of Mitochondrial Dysfunction-Induced Insulin Resistance in Differentiated 3T3-L1 Adipocytes via Inhibition of NF-κB Pathways

    PubMed Central

    Hafizi Abu Bakar, Mohamad; Sarmidi, Mohamad Roji; Kai, Cheng Kian; Huri, Hasniza Zaman; Yaakob, Harisun

    2014-01-01

    A growing body of evidence suggests that activation of nuclear factor kappa B (NF-κB) signaling pathways is among the inflammatory mechanism involved in the development of insulin resistance and chronic low-grade inflammation in adipose tissues derived from obese animal and human subjects. Nevertheless, little is known about the roles of NF-κB pathways in regulating mitochondrial function of the adipose tissues. In the present study, we sought to investigate the direct effects of celastrol (potent NF-κB inhibitor) upon mitochondrial dysfunction-induced insulin resistance in 3T3-L1 adipocytes. Celastrol ameliorates mitochondrial dysfunction by altering mitochondrial fusion and fission in adipocytes. The levels of oxidative DNA damage, protein carbonylation and lipid peroxidation were down-regulated. Further, the morphology and quantification of intracellular lipid droplets revealed the decrease of intracellular lipid accumulation with reduced lipolysis. Moreover, massive production of the pro-inflammatory mediators tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were markedly depleted. Insulin-stimulated glucose uptake activity was restored with the enhancement of insulin signaling pathways. This study signified that the treatments modulated towards knockdown of NF-κB transcription factor may counteract these metabolic insults exacerbated in our model of synergy between mitochondrial dysfunction and inflammation. These results demonstrate for the first time that NF-κB inhibition modulates mitochondrial dysfunction induced insulin resistance in 3T3-L1 adipocytes. PMID:25474091

  6. FDP-E induces adipocyte inflammation and suppresses insulin-stimulated glucose disposal: effect of inflammation and obesity on fibrinogen Bβ mRNA.

    PubMed

    Kang, Minsung; Vaughan, Roger A; Paton, Chad M

    2015-12-01

    Obesity is associated with increased fibrinogen production and fibrin formation, which produces fibrin degradation products (FDP-E and FDP-D). Fibrin and FDPs both contribute to inflammation, which would be expected to suppress glucose uptake and insulin signaling in adipose tissue, yet the effect of FDP-E and FDP-D on adipocyte function and glucose disposal is completely unknown. We tested the effects of FDPs on inflammation in 3T3-L1 adipocytes and primary macrophages and adipocyte glucose uptake in vitro. High-fat-fed mice increased hepatic fibrinogen mRNA expression ninefold over chow-fed mice, with concomitant increases in plasma fibrinogen protein levels. Obese mice also displayed increased fibrinogen content of epididymal fat pads. We treated cultured 3T3-L1 adipocytes and primary macrophages with FDP-E, FDP-D, or fibrinogen degradation products (FgnDP-E). FDP-D and FgnDP-E had no effect on inflammation or glucose uptake. Cytokine mRNA expression in RAW264.7 macrophage-like cells and 3T3-L1 adipocytes treated with FDP-E induced inflammation with maximal effects at 100 nM and 6 h. Insulin-stimulated 2-deoxy-d-[(3)H]glucose uptake was reduced by 71% in adipocytes treated with FDP-E. FDP-E, but not FDP-D or FgnDP-E, induces inflammation in macrophages and adipocytes and decreases glucose uptake in vitro. FDP-E may contribute toward obesity-associated acute inflammation and glucose intolerance, although its chronic role in obesity remains to be elucidated.

  7. Transcriptional Regulation of an Insulin-Sensitizing Adipokine Adipolin/CTRP12 in Adipocytes by Krüppel-Like Factor 15

    PubMed Central

    Enomoto, Takashi; Ohashi, Koji; Shibata, Rei; Kambara, Takahiro; Uemura, Yusuke; Yuasa, Daisuke; Kataoka, Yoshiyuki; Miyabe, Megumi; Matsuo, Kazuhiro; Joki, Yusuke; Hayakawa, Satoko; Hiramatsu-Ito, Mizuho; Ito, Masanori; Murohara, Toyoaki; Ouchi, Noriyuki

    2013-01-01

    Obese states characterized by chronic inflammation are closely linked to the development of metabolic dysfunction. We identified adipolin/CTRP12 as an insulin-sensitizing and anti-inflammatory adipokine. Although obese conditions down-regulate adipolin expression, its molecular mechanism is largely unknown. Here we show that the transcriptional regulator Krüppel-like factor (KLF) 15 is involved in the regulation of adipolin expression in adipocytes. White adipose tissue from diet-induced obese (DIO) mice showed decreased expression of KLF9 and KLF15 among several KLFs, which was accompanied by reduced expression of adipolin. In cultured 3T3L1 adipocytes, treatment with TNFα significantly reduced the mRNA levels of KLF9, KLF15 and adipolin. Adenovirus-mediated overexpression of KLF15 but not KLF9 reversed TNFα-induced reduction of adipolin expression in adipocytes. Conversely, gene targeting ablation of KLF15 attenuated adipolin expression in adipocytes. Expression of KLF15 but not KLF9 enhanced the promoter activity of adipolin in HEK293 cells. Pretreatment of 3T3L1 adipocytes with the JNK inhibitor SP600125, but not p38 MAPK inhibitor SB203580 blocked the inhibitory effects of TNFα on adipolin and KLF15 expression. These data suggest that adipose inflammation under conditions of obesity suppresses adipolin expression via JNK-dependent down-regulation of KLF15 in adipocytes. PMID:24358263

  8. Differential effects of pertussis toxin on insulin-stimulated phosphatidylcholine hydrolysis and glycerolipid synthesis de novo. Studies in BC3H-1 myocytes and rat adipocytes

    SciTech Connect

    Hoffman, J.M.; Standaert, M.L.; Nair, G.P.; Farese, R.V. )

    1991-04-02

    Insulin-induced increases in diacylglycerol (DAG) have been suggested to result from stimulation of de novo phosphatidic acid (PA) synthesis and phosphatidylcholine (PC) hydrolysis. Presently, the authors found that insulin decreased PC levels of BC3H-1 myocytes and rat adipocytes by approximately 10-25% within 30 s. These decreases were rapidly reversed in both cell types, apparently because of increased PC synthesis de novo. In BC3H-1 myocytes, pertussis toxin inhibited PC resynthesis and insulin effects on the pathway of de novo PA-DAG-PC synthesis, as evidenced by changes in ({sup 3}H)glycerol incorporation, but did not inhibit insulin-stimulated PC hydrolysis. Pertussis toxin also blocked the later, but not the initial, increase in DAG production in the myocytes. Phorbol esters activated PC hydrolysis in both myocytes and adipocytes, but insulin-induced stimulation of PC hydrolysis was not dependent upon activation of PKC, since this hydrolysis was not inhibited by 500 {mu}M sangivamycin, an effective PKC inhibitor. The results indicate that insulin increases DAG by pertussis toxin sensitive and insensitive (PC hydrolysis) mechanisms, which are mechanistically separate, but functionally interdependent and integrated. PC hydrolysis may contribute importantly to initial increases in DAG, but later sustained increases are apparently largely dependent on insulin-induced stimulation of the pathway of de novo phospholipid synthesis.

  9. Tribbles 3 Inhibits Brown Adipocyte Differentiation and Function by Suppressing Insulin Signaling

    PubMed Central

    Jeong, Ha-Won; Choi, Ran Hee; McClellan, Jamie L.; Piroli, Gerardo G.; Frizzell, Norma; Tseng, Yu-Hua; Goodyear, Laurie J.; Koh, Ho-Jin

    2016-01-01

    Recent studies have demonstrated that adult humans have substantial amounts of functioning brown adipose tissue (BAT). Since BAT has been implicated as an anti-obese and anti-diabetic tissue, it is important to understand the signaling molecules that regulate BAT function. There has been a link between insulin signaling and BAT metabolism as deletion or pharmaceutical inhibition of insulin signaling impairs BAT differentiation and function. Tribbles 3 (TRB3) is a pseudo kinase that has been shown to regulate metabolism and insulin signaling in multiple tissues but the role of TRB3 in BAT has not been studied. In this study, we found that TRB3 expression was present in BAT and overexpression of TRB3 in brown preadipocytes impaired differentiation and decreased expression of BAT markers. Furthermore, TRB3 overexpression resulted in significantly lower oxygen consumption rates for basal and proton leakage, indicating decreased BAT activity. Based on previous studies showing that deletion or pharmaceutical inhibition of insulin signaling impairs BAT differentiation and function, we assessed insulin signaling in brown preadipocytes and BAT in vivo. Overexpression of TRB3 in cells impaired insulin-stimulated IRS1 and Akt phosphorylation, whereas TRB3KO mice displayed improved IRS1 and Akt phosphorylation. Finally, deletion of IRS1 abolished the function of TRB3 to regulate BAT differentiation and metabolism. These data demonstrate that TRB3 inhibits insulin signaling in BAT, resulting in impaired differentiation and function. PMID:26801556

  10. Design, synthesis and characterization of novel binary V(V)-Schiff base materials linked with insulin-mimetic vanadium-induced differentiation of 3T3-L1 fibroblasts to adipocytes. Structure-function correlations at the molecular level.

    PubMed

    Halevas, E; Tsave, O; Yavropoulou, M P; Hatzidimitriou, A; Yovos, J G; Psycharis, V; Gabriel, C; Salifoglou, A

    2015-06-01

    Among the various roles of vanadium in the regulation of intracellular signaling, energy metabolism and insulin mimesis, its exogenous activity stands as a contemporary challenge currently under investigation and a goal to pursue as a metallodrug against Diabetes mellitus II. In this regard, the lipogenic activity of vanadium linked to the development of well-defined anti-diabetic vanadodrugs has been investigated through: a) specifically designing and synthesizing Schiff base organic ligands L, bearing a variable number of terminal alcohols, b) a series of well-defined soluble binary V(V)-L compounds synthesized and physicochemically characterized, c) a study of their cytotoxic effect and establishment of adipogenic activity in 3T3-L1 fibroblasts toward mature adipocytes, and d) biomarker examination of a closely-linked molecular target involving or influenced by the specific V(V) forms, cumulatively delineating factors involved in potential pathways linked to V(V)-induced insulin-like activity. Collectively, the results a) project the importance of specific structural features in Schiff ligands bound to V(V), thereby influencing the emergence of its (a)toxicity and for the first time its insulin-like activity in pre-adipocyte differentiation, b) contribute to the discovery of molecular targets influenced by the specific vanadoforms seeking to induce glucose uptake, and c) indicate an interplay of V(V) structural speciation and cell-differentiation biological activity, thereby gaining insight into vanadium's potential as a future metallodrug in Diabetes mellitus.

  11. Targeting AMP-activated protein kinase in adipocytes to modulate obesity-related adipokine production associated with insulin resistance and breast cancer cell proliferation

    PubMed Central

    2011-01-01

    Background Adipokines, e.g. TNFα, IL-6 and leptin increase insulin resistance, and consequent hyperinsulinaemia influences breast cancer progression. Beside its mitogenic effects, insulin may influence adipokine production from adipocyte stromal cells and paracrine enhancement of breast cancer cell growth. In contrast, adiponectin, another adipokine is protective against breast cancer cell proliferation and insulin resistance. AMP-activated protein kinase (AMPK) activity has been found decreased in visceral adipose tissue of insulin-resistant patients. Lipopolysaccharides (LPS) link systemic inflammation to high fat diet-induced insulin resistance. Modulation of LPS-induced adipokine production by metformin and AMPK activation might represent an alternative way to treat both, insulin resistance and breast cancer. Methods Human preadipocytes obtained from surgical biopsies were expanded and differentiated in vitro into adipocytes, and incubated with siRNA targeting AMPKalpha1 (72 h), LPS (24 h, 100 μg/ml) and/or metformin (24 h, 1 mM) followed by mRNA extraction and analyses. Additionally, the supernatant of preadipocytes or derived-adipocytes in culture for 24 h was used as conditioned media to evaluate MCF-7 breast cancer cell proliferation. Results Conditioned media from preadipocyte-derived adipocytes, but not from undifferentiated preadipocytes, increased MCF-7 cell proliferation (p < 0.01). Induction of IL-6 mRNA by LPS was reduced by metformin (p < 0.01), while the LPS-induced mRNA expression of the naturally occurring anti-inflammatory cytokine interleukin 1 receptor antagonist was increased (p < 0.01). Silencing of AMPKalpha1 enhanced LPS-induced IL-6 and IL-8 mRNA expression (p < 0.05). Conclusions Adipocyte-secreted factors enhance breast cancer cell proliferation, while AMPK and metformin improve the LPS-induced adipokine imbalance. Possibly, AMPK activation may provide a new way not only to improve the obesity-related adipokine profile and insulin

  12. Isomeric C12-alkamides from the roots of Echinacea purpurea improve basal and insulin-dependent glucose uptake in 3T3-L1 adipocytes.

    PubMed

    Kotowska, Dorota; El-Houri, Rime B; Borkowski, Kamil; Petersen, Rasmus K; Fretté, Xavier C; Wolber, Gerhard; Grevsen, Kai; Christensen, Kathrine B; Christensen, Lars P; Kristiansen, Karsten

    2014-12-01

    Echinacea purpurea has been used in traditional medicine as a remedy for the treatment and prevention of upper respiratory tract infections and the common cold. Recent investigations have indicated that E. purpurea also has an effect on insulin resistance. A dichloromethane extract of E. purpurea roots was found to enhance glucose uptake in adipocytes and to activate peroxisome proliferator-activated receptor γ. The purpose of the present study was to identify the bioactive compounds responsible for the potential antidiabetic effect of the dichloromethane extract using a bioassay-guided fractionation approach. Basal and insulin-dependent glucose uptake in 3T3-L1 adipocytes were used to assess the bioactivity of extract, fractions and isolated metabolites. A peroxisome proliferator-activated receptor γ transactivation assay was used to determine the peroxisome proliferator-activated receptor γ activating properties of the extract, active fractions and isolated metabolites. Two novel isomeric dodeca-2E,4E,8Z,10E/Z-tetraenoic acid 2-methylbutylamides together with two known C12-alkamides and α-linolenic acid were isolated from the active fractions. The isomeric C12-alkamides were found to activate peroxisome proliferator-activated receptor γ, to increase basal and insulin-dependent glucose uptake in adipocytes in a dose-dependent manner, and to exhibit characteristics of a peroxisome proliferator-activated receptor γ partial agonist.

  13. 4-Hydroxyisoleucine ameliorates an insulin resistant-like state in 3T3-L1 adipocytes by regulating TACE/TIMP3 expression

    PubMed Central

    Gao, Feng; Du, Wen; Zafar, Mohammad Ishraq; Shafqat, Raja Adeel; Jian, Liumeng; Cai, Qin; Lu, Furong

    2015-01-01

    Background Obesity-associated insulin resistance (IR) is highly correlated with soluble tumor necrosis factor-α (sTNF-α), which is released from transmembranous TNF-α by TNF-α converting enzyme (TACE). In vivo, TACE activity is suppressed by tissue inhibitor of metalloproteinase 3 (TIMP3). Agents that can interact with TACE/TIMP3 to improve obesity-related IR would be highly valuable. In the current study, we assessed whether (2S,3R,4S)-4-hydroxyisoleucine (4-HIL) could modulate TACE/TIMP3 and ameliorate an obesity-induced IR-like state in 3T3-L1 adipocytes. Materials and methods 3T3-L1 adipocytes were incubated in the presence of 25 mM glucose and 0.6 nM insulin to induce an IR-like state, and were then treated with different concentrations of 4-HIL or 10 µM pioglitazone (positive control). The glucose uptake rate was determined using the 2-deoxy-[3H]-d-glucose method, and the levels of sTNF-α in the cell supernatant were determined using ELISA. The protein expression of TACE, TIMP3, and insulin signaling-related molecules was measured using western blotting. Results Exposure to high glucose and insulin for 18 hours increased the levels of sTNF-α in the cell supernatant. The phosphorylation of insulin receptor substrate-1 (IRS-1) Ser307 and Akt Ser473 was increased, whereas the protein expression of IRS-1, Akt, and glucose transporter-4 was decreased. The insulin-induced glucose uptake was reduced by 67% in 3T3-L1 adipocytes, which indicated the presence of an IR-like state. The above indexes, which demonstrated the successful induction of an IR-like state, were reversed by 4-HIL in a dose-dependent manner by downregulating and upregulating the protein expression of TACE and TIMP3 proteins, respectively. Conclusion 4-HIL improved an obesity-associated IR-like state in 3T3-L1 adipocytes by targeting TACE/TIMP3 and the insulin signaling pathway. PMID:26527864

  14. Specific collagen XVIII isoforms promote adipose tissue accrual via mechanisms determining adipocyte number and affect fat deposition.

    PubMed

    Aikio, Mari; Elamaa, Harri; Vicente, David; Izzi, Valerio; Kaur, Inderjeet; Seppinen, Lotta; Speedy, Helen E; Kaminska, Dorota; Kuusisto, Sanna; Sormunen, Raija; Heljasvaara, Ritva; Jones, Emma L; Muilu, Mikko; Jauhiainen, Matti; Pihlajamäki, Jussi; Savolainen, Markku J; Shoulders, Carol C; Pihlajaniemi, Taina

    2014-07-29

    Collagen XVIII is an evolutionary conserved ubiquitously expressed basement membrane proteoglycan produced in three isoforms via two promoters (P). Here, we assess the function of the N-terminal, domain of unknown function/frizzled-like sequences unique to medium/long collagen XVIII by creating P-specific null mice. P2-null mice, which only produce short collagen XVIII, developed reduced bulk-adiposity, hepatic steatosis, and hypertriglyceridemia. These abnormalities did not develop in P1-null mice, which produce medium/long collagen XVIII. White adipose tissue samples from P2-null mice contain larger reserves of a cell population enriched in early adipocyte progenitors; however, their embryonic fibroblasts had ∼ 50% lower adipocyte differentiation potential. Differentiating 3T3-L1 fibroblasts into mature adipocytes produced striking increases in P2 gene-products and dramatic falls in P1-transcribed mRNA, whereas Wnt3a-induced dedifferentiation of mature adipocytes produced reciprocal changes in P1 and P2 transcript levels. P2-derived gene-products containing frizzled-like sequences bound the potent adipogenic inhibitor, Wnt10b, in vitro. Previously, we have shown that these same sequences bind Wnt3a, inhibiting Wnt3a-mediated signaling. P2-transcript levels in visceral fat were positively correlated with serum free fatty acid levels, suggesting that collagen α1 (XVIII) expression contributes to regulation of adipose tissue metabolism in visceral obesity. Medium/long collagen XVIII is deposited in the Space of Disse, and interaction between hepatic apolipoprotein E and this proteoglycan is lost in P2-null mice. These results describe a previously unidentified extracellular matrix-directed mechanism contributing to the control of the multistep adipogenic program that determines the number of precursors committing to adipocyte differentiation, the maintenance of the differentiated state, and the physiological consequences of its impairment on ectopic fat

  15. Increased insulin binding to adipocytes and monocytes and increased insulin sensitivity of glucose transport and metabolism in adipocytes from non-insulin-dependent diabetics after a low-fat/high-starch/high-fiber diet.

    PubMed

    Hjøllund, E; Pedersen, O; Richelsen, B; Beck-Nielsen, H; Sørensen, N S

    1983-11-01

    Nine non-insulin-dependent diabetics were studied before and after 3 weeks on an isoenergetic high-fiber/high-starch/low-fat diet (alternative diet), and nine non-insulin-dependent diabetics were studied on their usual diet. In the group that ate the alternative diet, the intake of fiber and starch increased 120% and 53%, whereas fat intake decreased 31%. Diabetes control improved as demonstrated by decreased fasting plasma glucose (P less than 0.05) and 24-hour urinary glucose excretion (P less than 0.05). The in vivo insulin action increased (KIVITT increased, P less than 0.05) with no change in fasting serum insulin levels. In fat cells obtained from patients in the alternative-diet group, insulin receptor binding increased (P less than 0.05) after the change of diet. Insulin binding to purified monocytes (more than 95% monocytes) also increased (P less than 0.05), whereas no change was found in insulin binding to erythrocytes. When lipogenesis was studied at a tracer glucose concentration at which glucose transport seems to be rate limiting, insulin sensitivity increased (P less than 0.02). This is the predicted consequence of increased receptor binding. Moreover, when CO2 production and lipogenesis were studied at a higher glucose concentration, where steps beyond transport seem to be rate limiting for glucose metabolism, increased insulin sensitivity was also observed. In contrast, no change was found in maximal insulin responsiveness. Fat and blood cells from the patients who continued on their usual diet showed no changes of the mentioned quantities.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Activation of AMP-activated protein kinase signaling pathway by adiponectin and insulin in mouse adipocytes: requirement of acyl-CoA synthetases FATP1 and Acsl1 and association with an elevation in AMP/ATP ratio.

    PubMed

    Liu, Qingqing; Gauthier, Marie-Soleil; Sun, Lei; Ruderman, Neil; Lodish, Harvey

    2010-11-01

    Adiponectin activates AMP-activated protein kinase (AMPK) in adipocytes, but the underlying mechanism remains unclear. Here we tested the hypothesis that AMP, generated in activating fatty acids to their CoA derivatives, catalyzed by acyl-CoA synthetases, is involved in AMPK activation by adiponectin. Moreover, in adipocytes, insulin affects the subcellular localization of acyl-CoA synthetase FATP1. Thus, we also tested whether insulin activates AMPK in these cells and, if so, whether it activates through a similar mechanism. We examined these hypotheses by measuring the AMP/ATP ratio and AMPK activation on adiponectin and insulin stimulation and after knocking down acyl-CoA synthetases in adipocytes. We show that adiponectin activation of AMPK is accompanied by an ∼2-fold increase in the cellular AMP/ATP ratio. Moreover, FATP1 and Acsl1, the 2 major acyl-CoA synthetase isoforms in adipocytes, are essential for AMPK activation by adiponectin. We also show that after 40 min. insulin activated AMPK in adipocytes, which was coupled with a 5-fold increase in the cellular AMP/ATP ratio. Knockdown studies show that FATP1 and Acsl1 are required for these processes, as well as for stimulation of long-chain fatty acid uptake by adiponection and insulin. These studies demonstrate that a change in cellular energy state is associated with AMPK activation by both adiponectin and insulin, which requires the activity of FATP1 and Acsl1.

  17. miR-146a-5p inhibits TNF-α-induced adipogenesis via targeting insulin receptor in primary porcine adipocytes.

    PubMed

    Wu, Di; Xi, Qian-Yun; Cheng, Xiao; Dong, Tao; Zhu, Xiao-Tong; Shu, Gang; Wang, Li-Na; Jiang, Qing-Yan; Zhang, Yong-Liang

    2016-08-01

    TNF-α is a multifunctional cytokine participating in immune disorders, inflammation, and tumor development with regulatory effects on energy metabolism. Our work focused on the function of TNF-α in adipogenesis of primary porcine adipocytes. TNF-α could suppress the insulin receptor (IR) at the mRNA and protein levels. Microarray analysis of TNF-α-treated porcine adipocytes was used to screen out 29 differentially expressed microRNAs (miRNAs), 13 of which were remarkably upregulated and 16 were intensely downregulated. These 29 differentially expressed miRNAs were predicted to mainly participate in the insulin signaling pathway, adipocytokine signaling pathway, and type 2 diabetes mellitus pathway by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. miR-146a-5p, reportedly involved in immunity and cancer relevant processes, was one of the most highly differentially expressed miRNAs after TNF-α treatment. Red Oil O staining and TG assay revealed that miR-146a-5p suppressed adipogenesis. A dual-luciferase reporter and siRNA assay verified that miR-146a-5p targeted IR and could inhibit its protein expression. miR-146a-5p was also validated to be involved in the insulin signaling pathway by reducing tyrosine phosphorylation of insulin receptor substrate-1. Our study provides the first evidence of miR-146a-5p targeting IR, which facilitates future studies related to obesity and diabetes using pig models.

  18. Adipocyte amino acid sensing controls adult germline stem cell number via the amino acid response pathway and independently of Target of Rapamycin signaling in Drosophila.

    PubMed

    Armstrong, Alissa R; Laws, Kaitlin M; Drummond-Barbosa, Daniela

    2014-12-01

    How adipocytes contribute to the physiological control of stem cells is a critical question towards understanding the link between obesity and multiple diseases, including cancers. Previous studies have revealed that adult stem cells are influenced by whole-body physiology through multiple diet-dependent factors. For example, nutrient-dependent pathways acting within the Drosophila ovary control the number and proliferation of germline stem cells (GSCs). The potential role of nutrient sensing by adipocytes in modulating stem cells in other organs, however, remains largely unexplored. Here, we report that amino acid sensing by adult adipocytes specifically modulates the maintenance of GSCs through a Target of Rapamycin-independent mechanism. Instead, reduced amino acid levels and the consequent increase in uncoupled tRNAs trigger activation of the GCN2-dependent amino acid response pathway within adipocytes, causing increased rates of GSC loss. These studies reveal a new step in adipocyte-stem cell crosstalk.

  19. Uncoupling of Obesity from Insulin Resistance Through a Targeted Mutation in aP2, the Adipocyte Fatty Acid Binding Protein

    NASA Astrophysics Data System (ADS)

    Hotamisligil, Gokhan S.; Johnson, Randall S.; Distel, Robert J.; Ellis, Ramsey; Papaioannou, Virginia E.; Spiegelman, Bruce M.

    1996-11-01

    Fatty acid binding proteins (FABPs) are small cytoplasmic proteins that are expressed in a highly tissue-specific manner and bind to fatty acids such as oleic and retinoic acid. Mice with a null mutation in aP2, the gene encoding the adipocyte FABP, were developmentally and metabolically normal. The aP2-deficient mice developed dietary obesity but, unlike control mice, they did not develop insulin resistance or diabetes. Also unlike their obese wild-type counterparts, obese aP2-/- animals failed to express in adipose tissue tumor necrosis factor-α (TNF-α), a molecule implicated in obesity-related insulin resistance. These results indicate that aP2 is central to the pathway that links obesity to insulin resistance, possibly by linking fatty acid metabolism to expression of TNF-α.

  20. Arrest of endosome acidification by bafilomycin A1 mimics insulin action on GLUT4 translocation in 3T3-L1 adipocytes.

    PubMed Central

    Chinni, S R; Shisheva, A

    1999-01-01

    In insulin-sensitive fat and muscle cells, the major glucose transporter GLUT4 is constitutively sequestered in endosomal tubulovesicular membranes, and moves to the cell surface in response to insulin. While sequence information within GLUT4 appears to be responsible for its constitutive intracellular sequestration, the regulatory elements and mechanisms that enable this protein to achieve its unique sorting pattern under basal and insulin-stimulated conditions are poorly understood. We show here that arrest of endosome acidification in insulin-sensitive 3T3-L1 adipocytes by bafilomycin A1, a specific inhibitor of the vacuolar proton pump, results in the rapid and dose-dependent translocation of GLUT4 from the cell interior to the membrane surface; the effects of maximally stimulatory concentrations of bafilomycin A1 (400-800 nM) were equivalent to 50-65% of the effects of acute insulin treatment. Like insulin, bafilomycin A1 induced the redistribution of GLUT1 and Rab4, but not that of other proteins whose membrane localization has been shown to be insulin-insensitive. Studies to address the mechanism of this effect demonstrated that neither autophosphorylation nor internalization of the insulin receptor was altered by bafilomycin A1 treatment. Bafilomycin-induced GLUT4 translocation was not blocked by cell pretreatment with wortmannin. Taken together, these data indicate that arrest of endosome acidification mimics insulin action on GLUT4 and GLUT1 translocation by a mechanism distal to insulin receptor and phosphatidylinositol 3-kinase activation, and suggest an important role for endosomal pH in the membrane dynamics of the glucose transporters. PMID:10215598

  1. Optimized mixture of hops rho iso-alpha acids-rich extract and acacia proanthocyanidins-rich extract reduces insulin resistance in 3T3-L1 adipocytes and improves glucose and insulin control in db/db mice

    PubMed Central

    Darland, Gary; Konda, Veera Reddy; Pacioretty, Linda M.; Chang, Jyh-Lurn; Bland, Jeffrey S.; Babish, John G.

    2012-01-01

    Rho iso-alpha acids-rich extract (RIAA) from Humulus lupulus (hops) and proanthocyanidins-rich extracts (PAC) from Acacia nilotica exert anti-inflammatory and anti-diabetic activity in vitro and in vivo. We hypothesized that a combination of these two extracts would exert enhanced effects in vitro on inflammatory markers and insulin signaling, and on nonfasting glucose and insulin in db/db mice. Over 49 tested combinations, RIAA:PAC at 5:1 (6.25 µg/mL) exhibited the greatest reductions in TNFα-stimulated lipolysis and IL-6 release in 3T3-L1 adipocytes, comparable to 5 µg/mL troglitazone. Pretreatment of 3T3-L1 adipocytes with this combination (5 µg/mL) also led to a 3-fold increase in insulin-stimulated glucose uptake that was comparable to 5 µg/mL pioglitazone or 901 µg/mL aspirin. Finally, db/db mice fed with RIAA:PAC at 5:1 (100 mg/kg) for 7 days resulted in 22% decrease in nonfasting glucose and 19% decrease in insulin that was comparable to 0.5 mg/kg rosiglitazone and better than 100 mg/kg metformin. RIAA:PAC mixture may have the potential to be an alternative when conventional therapy is undesirable or ineffective, and future research exploring its long-term clinical application is warranted. PMID:23198019

  2. Chromium activates glucose transporter 4 trafficking and enhances insulin-stimulated glucose transport in 3T3-L1 adipocytes via a cholesterol-dependent mechanism.

    PubMed

    Chen, Guoli; Liu, Ping; Pattar, Guruprasad R; Tackett, Lixuan; Bhonagiri, Padma; Strawbridge, Andrew B; Elmendorf, Jeffrey S

    2006-04-01

    Evidence suggests that chromium supplementation may alleviate symptoms associated with diabetes, such as high blood glucose and lipid abnormalities, yet a molecular mechanism remains unclear. Here, we report that trivalent chromium in the chloride (CrCl3) or picolinate (CrPic) salt forms mobilize the glucose transporter, GLUT4, to the plasma membrane in 3T3-L1 adipocytes. Concomitant with an increase in GLUT4 at the plasma membrane, insulin-stimulated glucose transport was enhanced by chromium treatment. In contrast, the chromium-mobilized pool of transporters was not active in the absence of insulin. Microscopic analysis of an exofacially Myc-tagged enhanced green fluorescent protein-GLUT4 construct revealed that the chromium-induced accumulation of GLUT4-containing vesicles occurred adjacent to the inner cell surface membrane. With insulin these transporters physically incorporated into the plasma membrane. Regulation of GLUT4 translocation by chromium did not involve known insulin signaling proteins such as the insulin receptor, insulin receptor substrate-1, phosphatidylinositol 3-kinase, and Akt. Consistent with a reported effect of chromium on increasing membrane fluidity, we found that chromium treatment decreased plasma membrane cholesterol. Interestingly, cholesterol add-back to the plasma membrane prevented the beneficial effect of chromium on both GLUT4 mobilization and insulin-stimulated glucose transport. Furthermore, chromium action was absent in methyl-beta-cyclodextrin-pretreated cells already displaying reduced plasma membrane cholesterol and increased GLUT4 translocation. Together, these data reveal a novel mechanism by which chromium may enhance GLUT4 trafficking and insulin-stimulated glucose transport. Moreover, these findings at the level of the cell are consistent with in vivo observations of improved glucose tolerance and decreased circulating cholesterol levels after chromium supplementation.

  3. Corticosterone-induced insulin resistance is not associated with alterations of insulin receptor number and kinase activity in chicken kidney.

    PubMed

    Bisbis, S; Taouis, M; Derouet, M; Chevalier, B; Simon, J

    1994-12-01

    Chicken renal insulin receptors have been recently characterized; their number and kinase activities vary in response to altered nutritional status. In the present study, the effect of chronic corticosterone treatment was examined in 5-week-old chickens. The development of an insulin resistance following corticosterone was suggested after 1 and 2 weeks of treatment by a significant increases in plasma insulin levels (1.63 +/- 0.13 vs 0.56 +/- 0.14 ng insulin/ml in controls) and in renal cytosolic phosphoenolpyruvate carboxykinase activity (17.2 +/- 0.8 vs 13.7 +/- 0.7 nm/mn/mg tissue in controls). No significant changes were present at the level of insulin receptor number and kinase activity. Therefore, in kidney and, as previously observed, in muscles, corticosterone can induce insulin resistance at postreceptor steps in the cascade of events leading to insulin action.

  4. Prolonged insulin stimulation down-regulates GLUT4 through oxidative stress-mediated retromer inhibition by a protein kinase CK2-dependent mechanism in 3T3-L1 adipocytes.

    PubMed

    Ma, Jinhui; Nakagawa, Yuko; Kojima, Itaru; Shibata, Hiroshi

    2014-01-03

    Although insulin acutely stimulates glucose uptake by promotion of GLUT4 translocation from intracellular compartments to the plasma membrane in adipocytes and muscles, long term insulin stimulation causes GLUT4 depletion that is particularly prominent in the insulin-responsive GLUT4 storage compartment. This effect is caused mainly by accelerated lysosomal degradation of GLUT4, although the mechanism is not fully defined. Here we show that insulin acutely induced dissociation of retromer components from the low density microsomal membranes of 3T3-L1 adipocytes that was accompanied by disruption of the interaction of Vps35 with sortilin. This insulin effect was dependent on the activity of protein kinase CK2 but not phosphatidylinositol 3-kinase or extracellular signal-regulated kinase 1/2. Knockdown of Vps26 decreased GLUT4 to a level comparable with that with insulin stimulation for 4 h. Vps35 with a mutation in the CK2 phosphorylation motif (Vps35-S7A) was resistant to insulin-induced dissociation from the low density microsomal membrane, and its overexpression attenuated GLUT4 down-regulation with insulin. Furthermore, insulin-generated hydrogen peroxide was an upstream mediator of the insulin action on retromer and GLUT4. These results suggested that insulin-generated oxidative stress switches the GLUT4 sorting direction to lysosomes through inhibition of the retromer function in a CK2-dependent manner.

  5. miR-146a-5p inhibits TNF-α-induced adipogenesis via targeting insulin receptor in primary porcine adipocytes[S

    PubMed Central

    Wu, Di; Xi, Qian-Yun; Cheng, Xiao; Dong, Tao; Zhu, Xiao-Tong; Shu, Gang; Wang, Li-Na; Jiang, Qing-Yan; Zhang, Yong-Liang

    2016-01-01

    TNF-α is a multifunctional cytokine participating in immune disorders, inflammation, and tumor development with regulatory effects on energy metabolism. Our work focused on the function of TNF-α in adipogenesis of primary porcine adipocytes. TNF-α could suppress the insulin receptor (IR) at the mRNA and protein levels. Microarray analysis of TNF-α-treated porcine adipocytes was used to screen out 29 differentially expressed microRNAs (miRNAs), 13 of which were remarkably upregulated and 16 were intensely downregulated. These 29 differentially expressed miRNAs were predicted to mainly participate in the insulin signaling pathway, adipocytokine signaling pathway, and type 2 diabetes mellitus pathway by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. miR-146a-5p, reportedly involved in immunity and cancer relevant processes, was one of the most highly differentially expressed miRNAs after TNF-α treatment. Red Oil O staining and TG assay revealed that miR-146a-5p suppressed adipogenesis. A dual-luciferase reporter and siRNA assay verified that miR-146a-5p targeted IR and could inhibit its protein expression. miR-146a-5p was also validated to be involved in the insulin signaling pathway by reducing tyrosine phosphorylation of insulin receptor substrate-1. Our study provides the first evidence of miR-146a-5p targeting IR, which facilitates future studies related to obesity and diabetes using pig models. PMID:27324794

  6. Glut4 Is Sorted from a Rab10 GTPase-independent Constitutive Recycling Pathway into a Highly Insulin-responsive Rab10 GTPase-dependent Sequestration Pathway after Adipocyte Differentiation.

    PubMed

    Brewer, Paul Duffield; Habtemichael, Estifanos N; Romenskaia, Irina; Mastick, Cynthia Corley; Coster, Adelle C F

    2016-01-08

    The RabGAP AS160/TBC1D4 controls exocytosis of the insulin-sensitive glucose transporter Glut4 in adipocytes. Glut4 is internalized and recycled through a highly regulated secretory pathway in these cells. Glut4 also cycles through a slow constitutive endosomal pathway distinct from the fast transferrin (Tf) receptor recycling pathway. This slow constitutive pathway is the only Glut4 cycling pathway in undifferentiated fibroblasts. The α2-macroglobulin receptor LRP1 cycles with Glut4 and the Tf receptor through all three exocytic pathways. To further characterize these pathways, the effects of knockdown of AS160 substrates on the trafficking kinetics of Glut4, LRP1, and the Tf receptor were measured in adipocytes and fibroblasts. Rab10 knockdown decreased cell surface Glut4 in insulin-stimulated adipocytes by 65%, but not in basal adipocytes or in fibroblasts. This decrease was due primarily to a 62% decrease in the rate constant of Glut4 exocytosis (kex), although Rab10 knockdown also caused a 1.4-fold increase in the rate constant of Glut4 endocytosis (ken). Rab10 knockdown in adipocytes also decreased cell surface LRP1 by 30% by decreasing kex 30-40%. There was no effect on LRP1 trafficking in fibroblasts or on Tf receptor trafficking in either cell type. These data confirm that Rab10 is an AS160 substrate that limits exocytosis through the highly insulin-responsive specialized secretory pathway in adipocytes. They further show that the slow constitutive endosomal (fibroblast) recycling pathway is Rab10-independent. Thus, Rab10 is a marker for the specialized pathway in adipocytes. Interestingly, mathematical modeling shows that Glut4 traffics predominantly through the specialized Rab10-dependent pathway both before and after insulin stimulation.

  7. Effect of a high fat diet on rat adipocyte lipolysis: responses to epinephrine, forskolin, methylisobutylxanthine, dibutyryl cyclic AMP, insulin and nicotinic acid.

    PubMed

    Tepperman, H M; Dewitt, J; Tepperman, J

    1986-10-01

    An earlier report from this laboratory showed that feeding rats a high fat diet decreased epinephrine-stimulated lipolysis in their adipose tissue. Experiments were designed to explore further the effects of such diets on adipocyte response to epinephrine and to several other lipolytic and antilipolytic agents. Rats were fed diets with 67% of energy consisting of glucose or lard for 5 to 7 d. Adipocytes were prepared from epididymal fat pads and lipolysis measured by the release of glycerol into the medium during 1-h incubations. The cells from the rats fed the high fat diet showed lower lipolytic responses to stimulation by epinephrine, forskolin and dibutyryl cyclic AMP than those from rats fed the high glucose diet. The lard diet effect on the lipolytic response to isobutylmethylxanthine varied among experiments, but it also decreased it in some of them. However, the high fat diet did not induce decreased sensitivity or responsiveness to the antilipolytic effect of insulin, although previous reports have demonstrated resistance to other actions of insulin in rats fed a high fat diet. The antilipolytic effect of nicotinic acid was also similar in cells from rats fed a high fat diet to that found for cells from rats fed the high glucose diet.

  8. Glutamine, insulin and glucocorticoids regulate glutamine synthetase expression in C2C12 myotubes, Hep G2 hepatoma cells and 3T3 L1 adipocytes.

    PubMed

    Wang, Yanxin; Watford, Malcolm

    2007-04-01

    The cell-specific regulation of glutamine synthetase expression was studied in three cell lines. In C2C12 myotubes, glucocorticoids increased the abundance of both glutamine synthetase protein and mRNA. Culture in the absence of glutamine also resulted in very high glutamine synthetase protein abundance but mRNA levels were unchanged. Glucocorticoids also increased the abundance of glutamine synthetase mRNA in Hep G2 hepatoma cells but this was not reflected in changes in protein abundance. Culture of Hep G2 cells without glutamine resulted in very high levels of protein, again with no change in mRNA abundance. Insulin was without effect in both C2C12 and Hep G2 cells. In 3T3 L1 adipocytes glucocorticoids increased the abundance of both glutamine synthetase mRNA and protein, insulin added alone had no effect but in the presence of glucocorticoids resulted in lower mRNA levels than seen with glucocorticoids alone, although protein levels remained high under such conditions. In contrast to the other cell lines glutamine synthetase protein levels were relatively unchanged by culture in the absence of glutamine. The results support the hypothesis that in myocytes, and hepatomas, but not in adipocytes, glutamine acts to moderate glutamine synthetase induction by glucocorticoids.

  9. [The content of individual fatty acids and numbers of double bonds, insulin, C-peptide and unesterified fatty acids in blood plasma in testing tolerance to glucose].

    PubMed

    Titov, V N; Sazhina, N N; Aripovskiĭ, A V; Evteeva, N M; Tkhagalizhokova, É M; Parkhimovich, R M

    2014-10-01

    The glucose tolerance test demonstrates that content of unesterified fatty acids in blood plasma decreases up to three times and the content of oleic and linoleic acids is more decreased in the pool of fatty acids lipids. Out of resistance to insulin, hormone secretion increases up to three times. The decreasing of level of individual fatty acids occurs in a larger extent. Under resistance to insulin secretion of insulin is increasing up to eight times. The decreasing of level of each fatty acid is less expressed. The effect of insulin reflects decreasing of content of double bonds in blood plasma. The number of double bonds characterizes the degree of unsaturation of fatty acids in lipids of blood plasma. The higher number of double bonds is in the pool of unesterified fatty acids the more active is the effect of insulin. The hyper-secretion of insulin is directly proportional to content of palmitic fatty acid in lipids of blood plasma on fasting. According the phylogenetic theory of general pathology, the effect of insulin on metabolism of glucose is mediated by fatty acids. The insulin is blocking lipolysis in insulin-depended subcutaneous adipocytes and decreases content of unesterified fatty acids in blood plasma. The insulin is depriving all cells of possibility to absorb unesterified fatty acids and "forces" them to absorb glucose increasing hereby number of GLUT4 on cell membrane. The resistance to insulin is manifested in high concentration of unesterfied fatty acids, hyperinsulinemia, hyperalbuminemia and increasing of concentration of C-reactive protein-monomer. The resistance to insulin is groundlessly referred to as a symptom of diabetes mellitus type II. The resistance to insulin is only a functional disorder lasting for years. It can be successfully arrested. The diabetes mellitus is developed against the background of resistance to insulin only after long-term hyper-secretion of insulin and under emaciation and death of β-cells. The diabetes

  10. Chronic hyperprolactinemia evoked by disruption of lactotrope dopamine D2 receptors impacts on liver and adipocyte genes related to glucose and insulin balance.

    PubMed

    Luque, Guillermina María; Lopez-Vicchi, Felicitas; Ornstein, Ana María; Brie, Belén; De Winne, Catalina; Fiore, Esteban; Perez-Millan, Maria Inés; Mazzolini, Guillermo; Rubinstein, Marcelo; Becu-Villalobos, Damasia

    2016-12-01

    We studied the impact of high prolactin titers on liver and adipocyte gene expression related to glucose and insulin homeostasis in correlation with obesity onset. To that end we used mutant female mice that selectively lack dopamine type 2 receptors (D2Rs) from pituitary lactotropes (lacDrd2KO), which have chronic high prolactin levels associated with increased body weight, marked increments in fat depots, adipocyte size, and serum lipids, and a metabolic phenotype that intensifies with age. LacDrd2KO mice of two developmental ages, 5 and 10 mo, were used. In the first time point, obesity and increased body weight are marginal, although mice are hyperprolactinemic, whereas at 10 mo there is marked adiposity with a 136% increase in gonadal fat and a 36% increase in liver weight due to lipid accumulation. LacDrd2KO mice had glucose intolerance, hyperinsulinemia, and impaired insulin response to glucose already in the early stages of obesity, but changes in liver and adipose tissue transcription factors were time and tissue dependent. In chronic hyperprolactinemic mice liver Prlr were upregulated, there was liver steatosis, altered expression of the lipogenic transcription factor Chrebp, and blunted response of Srebp-1c to refeeding at 5 mo of age, whereas no effect was observed in the glycogenesis pathway. On the other hand, in adipose tissue a marked decrease in lipogenic transcription factor expression was observed when morbid obesity was already settled. These adaptive changes underscore the role of prolactin signaling in different tissues to promote energy storage.

  11. Overexpression of protein-tyrosine phosphatase-1B in adipocytes inhibits insulin-stimulated phosphoinositide 3-kinase activity without altering glucose transport or Akt/Protein kinase B activation.

    PubMed

    Venable, C L; Frevert, E U; Kim, Y B; Fischer, B M; Kamatkar, S; Neel, B G; Kahn, B B

    2000-06-16

    Previous studies suggested that protein-tyrosine phosphatase 1B (PTP1B) antagonizes insulin action by catalyzing dephosphorylation of the insulin receptor (IR) and/or other key proteins in the insulin signaling pathway. In adipose tissue and muscle of obese humans and rodents, PTP1B expression is increased, which led to the hypothesis that PTP1B plays a role in the pathogenesis of insulin resistance. Consistent with this, mice in which the PTP1B gene was disrupted exhibit increased insulin sensitivity. To test whether increased expression of PTP1B in an insulin-sensitive cell type could contribute to insulin resistance, we overexpressed wild-type PTP1B in 3T3L1 adipocytes using adenovirus-mediated gene delivery. PTP1B expression was increased approximately 3-5-fold above endogenous levels at 16 h, approximately 14-fold at 40 h, and approximately 20-fold at 72 h post-transduction. Total protein-tyrosine phosphatase activity was increased by 50% at 16 h, 3-4-fold at 40 h, and 5-6-fold at 72 h post-transduction. Compared with control cells, cells expressing high levels of PTP1B showed a 50-60% decrease in maximally insulin-stimulated tyrosyl phosphorylation of IR and insulin receptor substrate-1 (IRS-1) and phosphoinositide 3-kinase (PI3K) activity associated with IRS-1 or with phosphotyrosine. Akt phosphorylation and activity were unchanged. Phosphorylation of p42 and p44 MAP kinase (MAPK) was reduced approximately 32%. Overexpression of PTP1B had no effect on basal, submaximally or maximally (100 nm) insulin-stimulated glucose transport or on the EC(50) for transport. Our results suggest that: 1) insulin stimulation of glucose transport in adipocytes requires insulin-induced glucose transport in adipocytes, and 3) overexpression of PTP1B alone in adipocytes does not impair glucose transport.

  12. Novel roles for insulin receptor (IR) in adipocytes and skeletal muscle cells via new and unexpected substrates.

    PubMed

    Ramalingam, Latha; Oh, Eunjin; Thurmond, Debbie C

    2013-08-01

    The insulin signaling pathway regulates whole-body glucose homeostasis by transducing extracellular signals from the insulin receptor (IR) to downstream intracellular targets, thus coordinating a multitude of biological functions. Dysregulation of IR or its signal transduction is associated with insulin resistance, which may culminate in type 2 diabetes. Following initial stimulation of IR, insulin signaling diverges into different pathways, activating multiple substrates that have roles in various metabolic and cellular processes. The integration of multiple pathways arising from IR activation continues to expand as new IR substrates are identified and characterized. Accordingly, our review will focus on roles for IR substrates as they pertain to three primary areas: metabolism/glucose uptake, mitogenesis/growth, and aging/longevity. While IR functions in a seemingly pleiotropic manner in many cell types, through these three main roles in fat and skeletal muscle cells, IR multi-tasks to regulate whole-body glucose homeostasis to impact healthspan and lifespan.

  13. Molecular mechanisms for the regulation of insulin-stimulated glucose uptake by small guanosine triphosphatases in skeletal muscle and adipocytes.

    PubMed

    Satoh, Takaya

    2014-10-16

    Insulin is a hormone that regulates the blood glucose level by stimulating various physiological responses in its target tissues. In skeletal muscle and adipose tissue, insulin promotes membrane trafficking of the glucose transporter GLUT4 from GLUT4 storage vesicles to the plasma membrane, thereby facilitating the uptake of glucose from the circulation. Detailed mechanisms underlying insulin-dependent intracellular signal transduction for glucose uptake remain largely unknown. In this article, I give an overview on the recently identified signaling network involving Rab, Ras, and Rho family small guanosine triphosphatases (GTPases) that regulates glucose uptake in insulin-responsive tissues. In particular, the regulatory mechanisms for these small GTPases and the cross-talk between protein kinase and small GTPase cascades are highlighted.

  14. Adrenoceptors promote glucose uptake into adipocytes and muscle by an insulin-independent signaling pathway involving mechanistic target of rapamycin complex 2.

    PubMed

    Mukaida, Saori; Evans, Bronwyn A; Bengtsson, Tore; Hutchinson, Dana S; Sato, Masaaki

    2017-02-01

    Uptake of glucose into skeletal muscle and adipose tissue plays a vital role in metabolism and energy balance. Insulin released from β-islet cells of the pancreas promotes glucose uptake in these target tissues by stimulating translocation of GLUT4 transporters to the cell surface. This process is complex, involving signaling proteins including the mechanistic (or mammalian) target of rapamycin (mTOR) and Akt that intersect with multiple pathways controlling cell survival, growth and proliferation. mTOR exists in two forms, mTOR complex 1 (mTORC1), and mTOR complex 2 (mTORC2). mTORC1 has been intensively studied, acting as a key regulator of protein and lipid synthesis that integrates cellular nutrient availability and energy balance. Studies on mTORC2 have focused largely on its capacity to activate Akt by phosphorylation at Ser473, however recent findings demonstrate a novel role for mTORC2 in cellular glucose uptake. For example, agonists acting at β2-adrenoceptors (ARs) in skeletal muscle or β3-ARs in brown adipose tissue increase glucose uptake in vitro and in vivo via mechanisms dependent on mTORC2 but not Akt. In this review, we will focus on the signaling pathways downstream of β-ARs that promote glucose uptake in skeletal muscle and brown adipocytes, and will highlight how the insulin and adrenergic pathways converge and interact in these cells. The identification of insulin-independent mechanisms that promote glucose uptake should facilitate novel treatment strategies for metabolic disease.

  15. B Lymphocyte Stimulator (BLyS) is expressed in human adipocytes in vivo and is related to obesity but not to insulin resistance.

    PubMed

    Müller, Nike; Schulte, Dominik M; Hillebrand, Susann; Türk, Kathrin; Hampe, Jochen; Schafmayer, Clemens; Brosch, Mario; von Schönfels, Witigo; Ahrens, Markus; Zeuner, Rainald; Schröder, Johann O; Blüher, Matthias; Gutschow, Christian; Freitag-Wolf, Sandra; Stelmach-Mardas, Marta; Saggau, Carina; Schreiber, Stefan; Laudes, Matthias

    2014-01-01

    Inflammation and metabolism have been shown to be evolutionary linked and increasing evidence exists that pro-inflammatory factors are involved in the pathogenesis of obesity and type 2 diabetes. Until now, most data suggest that within adipose tissue these factors are secreted by cells of the innate immune system, e. g. macrophages. In the present study we demonstrate that B lymphocyte stimulator (BLyS) is increased in human obesity. In contrast to several pro-inflammatory factors, we found the source of BLyS in human adipose tissue to be the adipocytes rather than immune cells. In grade 3 obese human subjects, expression of BLyS in vivo in adipose tissue is significantly increased (p<0.001). Furthermore, BLyS serum levels are elevated in grade 3 human obesity (862.5+222.0 pg/ml vs. 543.7+60.7 pg/ml in lean controls, p<0.001) and are positively correlated to the BMI (r = 0.43, p<0.0002). In the present study, bariatric surgery significantly altered serum BLyS concentrations. In contrast, weight loss due to a very-low-calorie-formula-diet (800 kcal/d) had no such effect. To examine metabolic activity of BLyS, in a translational research approach, insulin sensitivity was measured in human subjects in vivo before and after treatment with the human recombinant anti-BLyS antibody belimumab. Since BLyS is known to promote B-cell proliferation and immunoglobulin secretion, the present data suggest that adipocytes of grade 3 obese human subjects are able to activate the adaptive immune system, suggesting that in metabolic inflammation in humans both, innate and adaptive immunity, are of pathophysiological relevance.

  16. B Lymphocyte Stimulator (BLyS) Is Expressed in Human Adipocytes In Vivo and Is Related to Obesity but Not to Insulin Resistance

    PubMed Central

    Müller, Nike; Schulte, Dominik M.; Hillebrand, Susann; Türk, Kathrin; Hampe, Jochen; Schafmayer, Clemens; Brosch, Mario; von Schönfels, Witigo; Ahrens, Markus; Zeuner, Rainald; Schröder, Johann O.; Blüher, Matthias; Gutschow, Christian; Freitag-Wolf, Sandra; Stelmach-Mardas, Marta; Saggau, Carina; Schreiber, Stefan; Laudes, Matthias

    2014-01-01

    Inflammation and metabolism have been shown to be evolutionary linked and increasing evidence exists that pro-inflammatory factors are involved in the pathogenesis of obesity and type 2 diabetes. Until now, most data suggest that within adipose tissue these factors are secreted by cells of the innate immune system, e. g. macrophages. In the present study we demonstrate that B lymphocyte stimulator (BLyS) is increased in human obesity. In contrast to several pro-inflammatory factors, we found the source of BLyS in human adipose tissue to be the adipocytes rather than immune cells. In grade 3 obese human subjects, expression of BLyS in vivo in adipose tissue is significantly increased (p<0.001). Furthermore, BLyS serum levels are elevated in grade 3 human obesity (862.5+222.0 pg/ml vs. 543.7+60.7 pg/ml in lean controls, p<0.001) and are positively correlated to the BMI (r = 0.43, p<0.0002). In the present study, bariatric surgery significantly altered serum BLyS concentrations. In contrast, weight loss due to a very-low-calorie-formula-diet (800 kcal/d) had no such effect. To examine metabolic activity of BLyS, in a translational research approach, insulin sensitivity was measured in human subjects in vivo before and after treatment with the human recombinant anti-BLyS antibody belimumab. Since BLyS is known to promote B-cell proliferation and immunoglobulin secretion, the present data suggest that adipocytes of grade 3 obese human subjects are able to activate the adaptive immune system, suggesting that in metabolic inflammation in humans both, innate and adaptive immunity, are of pathophysiological relevance. PMID:24728308

  17. Rab14 limits the sorting of Glut4 from endosomes into insulin-sensitive regulated secretory compartments in adipocytes.

    PubMed

    Brewer, Paul Duffield; Habtemichael, Estifanos N; Romenskaia, Irina; Coster, Adelle C F; Mastick, Cynthia Corley

    2016-05-15

    Insulin increases glucose uptake by increasing the rate of exocytosis of the facilitative glucose transporter isoform 4 (Glut4) relative to its endocytosis. Insulin also releases Glut4 from highly insulin-regulated secretory compartments (GSVs or Glut4 storage vesicles) into constitutively cycling endosomes. Previously it was shown that both overexpression and knockdown of the small GTP-binding protein Rab14 decreased Glut4 translocation to the plasma membrane (PM). To determine the mechanism of this perturbation, we measured the effects of Rab14 knockdown on the trafficking kinetics of Glut4 relative to two proteins that partially co-localize with Glut4, the transferrin (Tf) receptor and low-density-lipoprotein-receptor-related protein 1 (LRP1). Our data support the hypothesis that Rab14 limits sorting of proteins from sorting (or 'early') endosomes into the specialized GSV pathway, possibly through regulation of endosomal maturation. This hypothesis is consistent with known Rab14 effectors. Interestingly, the insulin-sensitive Rab GTPase-activating protein Akt substrate of 160 kDa (AS160) affects both sorting into and exocytosis from GSVs. It has previously been shown that exocytosis of GSVs is rate-limited by Rab10, and both Rab10 and Rab14 are in vitro substrates of AS160. Regulation of both entry into and exit from GSVs by AS160 through sequential Rab substrates would provide a mechanism for the finely tuned 'quantal' increases in cycling Glut4 observed in response to increasing concentrations of insulin.

  18. Zinc transporter 7 deficiency affects lipid synthesis in adipocytes by inhibiting insulin-dependent Akt activity and glucose uptake

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mice deficient for zinc transporter 7 (Znt7) are mildly zinc deficient, accompanied with low body weight gain and body fat accumulation. To investigate the underlying mechanism of Znt7 deficiency in body adiposity, we investigated fatty acid composition and insulin sensitivity in visceral (epididyma...

  19. NOD1 activation induces proinflammatory gene expression and insulin resistance in 3T3-L1 adipocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chronic inflammation is associated with obesity and insulin resistance. However, the underlying mechanisms are not fully understood. Pattern recognition receptors Toll-like receptors and Nucleotide-oligomerization domain containing proteins play critical roles in innate immune response. Here we repo...

  20. Nymphaea nouchali Burm. f. hydroalcoholic seed extract increases glucose consumption in 3T3-L1 adipocytes through activation of peroxisome proliferator-activated receptor gamma and insulin sensitization

    PubMed Central

    Parimala, Mabel; Debjani, M.; Vasanthi, Hannah Rachel; Shoba, Francis Gricilda

    2015-01-01

    Nymphaea nouchali Burm. f. (Family – Nymphaeaceae) is a well-known medicinal plant used in the Indian ayurvedic system of medicine for treating diabetes. The seeds especially have been prescribed for diabetes. The hydroalcoholic extract of N. nouchali seeds has been demonstrated to possess anti-hyperglycemic effects in diabetic rats, but the functional mechanism remains unknown. The nuclear receptor, peroxisome proliferator-activated receptor gamma (PPARγ) is noted to play an important role in glucose and lipid homeostasis. This study was hence focused in evaluating the effect of the extract on PPARγ activation, adipocyte differentiation, and glucose consumption in 3T3-L1 cells. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), followed by adipogenesis assay using Oil Red O technique. Glucose consumption of preadipocytes and adipocytes in the presence of the extract was also determined. Real-time polymerase chain reaction was performed to identify the expression of genes involved in glucose consumption in the adipocytes. MTT assay confirmed the extract to be nontoxic, and Oil Red O staining confirmed enhanced adipocyte differentiation of 3T3-L1 cells in a dose-dependent manner. The extract also increased the expression of PPARγ target gene, which in turn enhanced the expression of GLUT-4. The data, therefore, suggests that N. nouchali seed extract promotes adipocyte differentiation and glucose consumption by inducing PPARγ activation, which in turn increases mRNA GLUT-4 expression and subsequently enhances insulin-responsiveness in insulin target tissues. PMID:26605160

  1. Nymphaea nouchali Burm. f. hydroalcoholic seed extract increases glucose consumption in 3T3-L1 adipocytes through activation of peroxisome proliferator-activated receptor gamma and insulin sensitization.

    PubMed

    Parimala, Mabel; Debjani, M; Vasanthi, Hannah Rachel; Shoba, Francis Gricilda

    2015-01-01

    Nymphaea nouchali Burm. f. (Family - Nymphaeaceae) is a well-known medicinal plant used in the Indian ayurvedic system of medicine for treating diabetes. The seeds especially have been prescribed for diabetes. The hydroalcoholic extract of N. nouchali seeds has been demonstrated to possess anti-hyperglycemic effects in diabetic rats, but the functional mechanism remains unknown. The nuclear receptor, peroxisome proliferator-activated receptor gamma (PPARγ) is noted to play an important role in glucose and lipid homeostasis. This study was hence focused in evaluating the effect of the extract on PPARγ activation, adipocyte differentiation, and glucose consumption in 3T3-L1 cells. Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), followed by adipogenesis assay using Oil Red O technique. Glucose consumption of preadipocytes and adipocytes in the presence of the extract was also determined. Real-time polymerase chain reaction was performed to identify the expression of genes involved in glucose consumption in the adipocytes. MTT assay confirmed the extract to be nontoxic, and Oil Red O staining confirmed enhanced adipocyte differentiation of 3T3-L1 cells in a dose-dependent manner. The extract also increased the expression of PPARγ target gene, which in turn enhanced the expression of GLUT-4. The data, therefore, suggests that N. nouchali seed extract promotes adipocyte differentiation and glucose consumption by inducing PPARγ activation, which in turn increases mRNA GLUT-4 expression and subsequently enhances insulin-responsiveness in insulin target tissues.

  2. Impact of lipid phosphatases SHIP2 and PTEN on the time- and Akt-isoform-specific amelioration of TNF-alpha-induced insulin resistance in 3T3-L1 adipocytes.

    PubMed

    Ikubo, Mariko; Wada, Tsutomu; Fukui, Kazuhito; Ishiki, Manabu; Ishihara, Hajime; Asano, Tomoichiro; Tsuneki, Hiroshi; Sasaoka, Toshiyasu

    2009-01-01

    TNF-alpha is a major contributor to the pathogenesis of insulin resistance associated with obesity and inflammation by serine phosphorylating and degrading insulin receptor substrate-1. Presently, we further found that pretreatment with TNF-alpha inhibited insulin-induced phosphorylation of Akt2 greater than Akt1. Since lipid phosphatases SH2-containing inositol 5'-phoshatase 2 (SHIP2) and phosphatase and tensin homologs deleted on chromosome 10 (PTEN) are negative regulators of insulin's metabolic signaling at the step downstream of phosphatidylinositol 3-kinase, we investigated the Akt isoform-specific properties of these phosphatases in the negative regulation after short- and long-term insulin treatment and examined the influence of inhibition on the amelioration of insulin resistance caused by TNF-alpha in 3T3-L1 adipocytes. Adenovirus-mediated overexpression of WT-SHIP2 decreased the phosphorylation of Akt2 greater than Akt1 after insulin stimulation up to 15 min. Expression of a dominant-negative DeltaIP-SHIP2 enhanced the phosphorylation of Akt2 up to 120 min. On the other hand, overexpression of WT-PTEN inhibited the phosphorylation of both Akt1 and Akt2 after short- but not long-term insulin treatment. The expression of DeltaIP-PTEN enhanced the phosphorylation of Akt1 at 120 min and that of Akt2 at 2 min. Interestingly, the expression of DeltaIP-SHIP2, but not DeltaIP-PTEN, protected against the TNF-alpha inhibition of insulin-induced phosphorylation of Akt2, GSK3, and AS160, whereas both improved the TNF-alpha inhibition of insulin-induced 2-deoxyglucose uptake. The results indicate that these lipid phosphatases possess different characteristics according to the time and preference of Akt isoform-dependent signaling in the negative regulation of the metabolic actions of insulin, whereas both inhibitions are effective in the amelioration of insulin resistance caused by TNF-alpha.

  3. Natural killer T cells in adipose tissue prevent insulin resistance

    PubMed Central

    Schipper, Henk S.; Rakhshandehroo, Maryam; van de Graaf, Stan F.J.; Venken, Koen; Koppen, Arjen; Stienstra, Rinke; Prop, Serge; Meerding, Jenny; Hamers, Nicole; Besra, Gurdyal; Boon, Louis; Nieuwenhuis, Edward E.S.; Elewaut, Dirk; Prakken, Berent; Kersten, Sander; Boes, Marianne; Kalkhoven, Eric

    2012-01-01

    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell–deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue–resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue–resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance. PMID:22863618

  4. Natural killer T cells in adipose tissue prevent insulin resistance.

    PubMed

    Schipper, Henk S; Rakhshandehroo, Maryam; van de Graaf, Stan F J; Venken, Koen; Koppen, Arjen; Stienstra, Rinke; Prop, Serge; Meerding, Jenny; Hamers, Nicole; Besra, Gurdyal; Boon, Louis; Nieuwenhuis, Edward E S; Elewaut, Dirk; Prakken, Berent; Kersten, Sander; Boes, Marianne; Kalkhoven, Eric

    2012-09-01

    Lipid overload and adipocyte dysfunction are key to the development of insulin resistance and can be induced by a high-fat diet. CD1d-restricted invariant natural killer T (iNKT) cells have been proposed as mediators between lipid overload and insulin resistance, but recent studies found decreased iNKT cell numbers and marginal effects of iNKT cell depletion on insulin resistance under high-fat diet conditions. Here, we focused on the role of iNKT cells under normal conditions. We showed that iNKT cell-deficient mice on a low-fat diet, considered a normal diet for mice, displayed a distinctive insulin resistance phenotype without overt adipose tissue inflammation. Insulin resistance was characterized by adipocyte dysfunction, including adipocyte hypertrophy, increased leptin, and decreased adiponectin levels. The lack of liver abnormalities in CD1d-null mice together with the enrichment of CD1d-restricted iNKT cells in both mouse and human adipose tissue indicated a specific role for adipose tissue-resident iNKT cells in the development of insulin resistance. Strikingly, iNKT cell function was directly modulated by adipocytes, which acted as lipid antigen-presenting cells in a CD1d-mediated fashion. Based on these findings, we propose that, especially under low-fat diet conditions, adipose tissue-resident iNKT cells maintain healthy adipose tissue through direct interplay with adipocytes and prevent insulin resistance.

  5. Constitutive adipocyte mTORC1 activation enhances mitochondrial activity and reduces visceral adiposity in mice.

    PubMed

    Magdalon, Juliana; Chimin, Patricia; Belchior, Thiago; Neves, Rodrigo X; Vieira-Lara, Marcel A; Andrade, Maynara L; Farias, Talita S; Bolsoni-Lopes, Andressa; Paschoal, Vivian A; Yamashita, Alex S; Kowaltowski, Alicia J; Festuccia, William T

    2016-05-01

    Mechanistic target of rapamycin complex 1 (mTORC1) loss of function reduces adiposity whereas partial mTORC1 inhibition enhances fat deposition. Herein we evaluated how constitutive mTORC1 activation in adipocytes modulates adiposity in vivo. Mice with constitutive mTORC1 activation in adipocytes induced by tuberous sclerosis complex (Tsc)1 deletion and littermate controls were evaluated for body mass, energy expenditure, glucose and fatty acid metabolism, mitochondrial function, mRNA and protein contents. Adipocyte-specific Tsc1 deletion reduced visceral, but not subcutaneous, fat mass, as well as adipocyte number and diameter, phenotypes that were associated with increased lipolysis, UCP-1 content (browning) and mRNA levels of pro-browning transcriptional factors C/EBPβ and ERRα. Adipocyte Tsc1 deletion enhanced mitochondrial oxidative activity, fatty acid oxidation and the expression of PGC-1α and PPARα in both visceral and subcutaneous fat. In brown adipocytes, however, Tsc1 deletion did not affect UCP-1 content and basal respiration. Adipocyte Tsc1 deletion also reduced visceral adiposity and enhanced glucose tolerance, liver and muscle insulin signaling and adiponectin secretion in mice fed with purified low- or high-fat diet. In conclusion, adipocyte-specific Tsc1 deletion enhances mitochondrial activity, induces browning and reduces visceral adiposity in mice.

  6. Retinol-Binding Protein 4 Inhibits Insulin Signaling in Adipocytes by Inducing Proinflammatory Cytokines in Macrophages through a c-Jun N-Terminal Kinase- and Toll-Like Receptor 4-Dependent and Retinol-Independent Mechanism

    PubMed Central

    Norseen, Julie; Hosooka, Tetsuya; Hammarstedt, Ann; Yore, Mark M.; Kant, Shashi; Aryal, Pratik; Kiernan, Urban A.; Phillips, David A.; Maruyama, Hiroshi; Kraus, Bettina J.; Usheva, Anny; Davis, Roger J.; Smith, Ulf

    2012-01-01

    Retinol-binding protein 4 (RBP4), the sole retinol transporter in blood, is secreted from adipocytes and liver. Serum RBP4 levels correlate highly with insulin resistance, other metabolic syndrome factors, and cardiovascular disease. Elevated serum RBP4 causes insulin resistance, but the molecular mechanisms are unknown. Here we show that RBP4 induces expression of proinflammatory cytokines in mouse and human macrophages and thereby indirectly inhibits insulin signaling in cocultured adipocytes. This occurs through activation of c-Jun N-terminal protein kinase (JNK) and Toll-like receptor 4 (TLR4) pathways independent of the RBP4 receptor, STRA6. RBP4 effects are markedly attenuated in JNK1−/− JNK2−/− macrophages and TLR4−/− macrophages. Because RBP4 is a retinol-binding protein, we investigated whether these effects are retinol dependent. Unexpectedly, retinol-free RBP4 (apo-RBP4) is as potent as retinol-bound RBP4 (holo-RBP4) in inducing proinflammatory cytokines in macrophages. Apo-RBP4 is likely to be physiologically significant since RBP4/retinol ratios are increased in serum of lean and obese insulin-resistant humans compared to ratios in insulin-sensitive humans, indicating that higher apo-RBP4 is associated with insulin resistance independent of obesity. Thus, RBP4 may cause insulin resistance by contributing to the development of an inflammatory state in adipose tissue through activation of proinflammatory cytokines in macrophages. This process reveals a novel JNK- and TLR4-dependent and retinol- and STRA6-independent mechanism of action for RBP4. PMID:22431523

  7. Effects of cardiotrophin on adipocytes.

    PubMed

    Zvonic, Sanjin; Hogan, Jessica C; Arbour-Reily, Patricia; Mynatt, Randall L; Stephens, Jacqueline M

    2004-11-12

    Cardiotrophin (CT-1) is a naturally occurring protein member of the interleukin (IL)-6 cytokine family and signals through the gp130/leukemia inhibitory factor receptor (LIFR) heterodimer. The formation of gp130/LIFR complex triggers the auto/trans-phosphorylation of associated Janus kinases, leading to the activation of Janus kinase/STAT and MAPK (ERK1 and -2) signaling pathways. Since adipocytes express both gp130 and LIFR proteins and are responsive to other IL-6 family cytokines, we examined the effects of CT-1 on 3T3-L1 adipocytes. Our studies have shown that CT-1 administration results in a dose- and time-dependent activation and nuclear translocation of STAT1, -3, -5A, and -5B as well as ERK1 and -2. We also confirmed the ability of CT-1 to induce signaling in fat cells in vivo. Our studies revealed that neither CT-1 nor ciliary neurotrophic factor treatment affected adipocyte differentiation. However, acute CT-1 treatment caused an increase in SOCS-3 mRNA in adipocytes and a transient decrease in peroxisome proliferator-activated receptor gamma (PPARgamma) mRNA that was regulated by the binding of STAT1 to the PPARgamma2 promoter. The effects of CT-1 on SOCS-3 and PPARgamma mRNA were independent of MAPK activation. Chronic administration of CT-1 to 3T3-L1 adipocytes resulted in a decrease of both fatty acid synthase and insulin receptor substrate-1 protein expression yet did not effect the expression of a variety of other adipocyte proteins. Moreover, chronic CT-1 treatment resulted in the development of insulin resistance as judged by a decrease in insulin-stimulated glucose uptake. In summary, CT-1 is a potent regulator of signaling in adipocytes in vitro and in vivo, and our current efforts are focused on determining the role of this cardioprotective cytokine on adipocyte physiology.

  8. PPARgamma induces the insulin-dependent glucose transporter GLUT4 in the absence of C/EBPalpha during the conversion of 3T3 fibroblasts into adipocytes.

    PubMed Central

    Wu, Z; Xie, Y; Morrison, R F; Bucher, N L; Farmer, S R

    1998-01-01

    To define the molecular mechanisms that control GLUT4 expression during adipogenesis, NIH-3T3 fibroblasts ectopically expressing different adipogenic transcription factors (C/EBPbeta, C/EBPdelta, C/EBPalpha, and PPARgamma) under the control of a tetracycline-responsive inducible (C/EBPs) or a constitutive retroviral (PPARgamma) expression system were used. Enhanced production of C/EBPbeta (beta2 cell line), C/EBPbeta together with C/EBPdelta (beta/delta39 cell line), C/EBPalpha (alpha1 cell line), or PPARgamma (Pgamma2 cell line) in cells exposed to dexamethasone and the PPARgamma ligand ciglitazone (a thiazolidinedione) resulted in expression of GLUT4 mRNA as well as other members of the adipogenic gene program, including aP2 and adipsin. Focusing our studies on the beta/delta39 cells, we have demonstrated that C/EBPbeta along with C/EBPdelta in the presence of dexamethasone induces PPARgamma, adipsin, and aP2 mRNA production; however, GLUT4 mRNA is only expressed in cells exposed to ciglitazone. In addition, enhanced expression of a ligand-activated form of PPARgamma in the beta/delta39 fibroblasts stimulates synthesis of GLUT4 protein and gives rise to a population of adipocytic cells that take up glucose in direct response to insulin. C/EBPalpha is not expressed in the beta/delta39 cells under conditions that stimulate the adipogenic program. This observation suggests that PPARgamma alone or in combination with C/EBPbeta and C/EBPdelta is capable of activating GLUT4 gene expression. PMID:9421462

  9. Changes of insulin effect on lipogenesis and insulin binding receptors during hypokinesia

    NASA Astrophysics Data System (ADS)

    Macho, L.; Fickova, M.; Zorad, S.

    The effect of hypokinesia on insulin action and insulin binding to specific receptors in fat cells was studied. Male Wistar rats were exposed to hypokinesia in special adjustable plastic cages for 1, 7, 21 and 60 days, and the stimulatory effect of insulin (10 and 100 mU) on the incorporation of radiocarbon labelled glucose into lipids of fat tissue and the binding of insulin to receptors of isolated adipocytes was estimated. The stimulation of lipogenesis by insulin was slightly diminished after hypokinesia for 1 day, however, an important increase of insulin action was found in rats exposed to hypokinesia for 60 days. The decrease of insulin binding capacity of the number of binding sites per cell and of the insulin receptor density was found after 1 day of hypokinesia. In rats exposed to hypokinesia for 60 days, in agreement with the higher stimulatory affect of insulin, an increase of insulin receptor density was observed. These results showed that hypokinesia has an important influence on stimulatory action of insulin and on insulin receptors in adipocytes.

  10. Adipose progenitor cells reside among the mature adipocytes: morphological research using an organotypic culture system.

    PubMed

    Anayama, Hisashi; Fukuda, Ryo; Yamate, Jyoji

    2015-11-01

    The precise localization and biological characteristics of the adipose progenitor cells are still a focus of debate. In this study, the localization of the adipose progenitor cells was determined using an organotypic culture system of adipose tissue slices. The tissue slices of subcutaneous white adipose tissue from rats were placed on a porous membrane and cultured at the interface between air and the culture medium for up to 5 days with or without adipogenic stimulation. The structure of adipose tissue components was sufficiently preserved during the culture and, following adipogenic stimulation with insulin, dexamethasone, and 3-isobutyl-1-methylxanthine, numerous multilocular adipocytes appeared in the interstitium among the mature adipocytes. Histomorphological 3-D observation using confocal laser microscopy revealed the presence of small mesenchymal cells containing little or no fat residing in the perivascular region and on the mature adipocytes and differentiation from the pre-existing mesenchymal cells to multilocular adipocytes. Immunohistochemistry demonstrated that these cells were initially present within the fibronectin-positive extracellular matrix (ECM). The adipose differentiation of the mesenchymal cells was confirmed by the enhanced expression of C/EBP-β suggesting adipose differentiation and the concurrent advent of CD105-expressing mesenchymal cells within the interstitium of the mature adipocytes. Based on the above, the mesenchymal cells embedded in the ECM around the mature adipocytes were confirmed to be responsible for adipogenesis because the transition of the mesenchymal cells to the stem state contributed to the increase in the number of adipocytes in rat adipose tissue.

  11. Protein Carbonylation and Adipocyte Mitochondrial Function*

    PubMed Central

    Curtis, Jessica M.; Hahn, Wendy S.; Stone, Matthew D.; Inda, Jacob J.; Droullard, David J.; Kuzmicic, Jovan P.; Donoghue, Margaret A.; Long, Eric K.; Armien, Anibal G.; Lavandero, Sergio; Arriaga, Edgar; Griffin, Timothy J.; Bernlohr, David A.

    2012-01-01

    Carbonylation is the covalent, non-reversible modification of the side chains of cysteine, histidine, and lysine residues by lipid peroxidation end products such as 4-hydroxy- and 4-oxononenal. In adipose tissue the effects of such modifications are associated with increased oxidative stress and metabolic dysregulation centered on mitochondrial energy metabolism. To address the role of protein carbonylation in the pathogenesis of mitochondrial dysfunction, quantitative proteomics was employed to identify specific targets of carbonylation in GSTA4-silenced or overexpressing 3T3-L1 adipocytes. GSTA4-silenced adipocytes displayed elevated carbonylation of several key mitochondrial proteins including the phosphate carrier protein, NADH dehydrogenase 1α subcomplexes 2 and 3, translocase of inner mitochondrial membrane 50, and valyl-tRNA synthetase. Elevated protein carbonylation is accompanied by diminished complex I activity, impaired respiration, increased superoxide production, and a reduction in membrane potential without changes in mitochondrial number, area, or density. Silencing of the phosphate carrier or NADH dehydrogenase 1α subcomplexes 2 or 3 in 3T3-L1 cells results in decreased basal and maximal respiration. These results suggest that protein carbonylation plays a major instigating role in cytokine-dependent mitochondrial dysfunction and may be linked to the development of insulin resistance in the adipocyte. PMID:22822087

  12. Adipocyte biology in polycystic ovary syndrome.

    PubMed

    Barber, T M; Franks, S

    2013-07-05

    Polycystic Ovary Syndrome (PCOS) is a common endocrinopathy that is associated with an adverse metabolic profile including insulin resistance. There is a clear association between obesity, the development of PCOS and the severity of its phenotypic, biochemical and metabolic features. Evidence to support this link includes data from epidemiological, pathophysiological and genetic studies. Given the importance of obesity in the development and manifestation of PCOS, ongoing research into the many facets of adipocyte biology in women with the condition is important and should continue to be a priority. In this review article, we discuss the existing literature on fat distribution, adipokines, adipocyte hypertrophy and adipocyte steroid metabolism in women with PCOS.

  13. Postreceptor defects causing insulin resistance in normoinsulinemic non-insulin-dependent diabetes mellitus

    SciTech Connect

    Bolinder, J.; Ostman, J.; Arner, P.

    1982-10-01

    The mechanisms of the diminished hypoglycemic response to insulin in non-insulin-dependent diabetes mellitus (NIDDM) with normal levels of circulating plasma insulin were investigated. Specific binding of mono-/sup 125/I (Tyr A14)-insulin to isolated adipocytes and effects of insulin (5--10,000 microunits/ml) on glucose oxidation and lipolysis were determined simultaneously in subcutaneous adipose tissue of seven healthy subjects of normal weight and seven untreated NIDDM patients with normal plasma insulin levels. The two groups were matched for age, sex, and body weight. Insulin binding, measured in terms of receptor number and affinity, was normal in NIDDM, the total number of receptors averaging 350,000 per cell. Neither sensitivity nor the maximum antilipolytic effect of insulin was altered in NIDDM patients as compared with control subjects; the insulin concentration producing half the maximum effect (ED50) was 10 microunits/ml. As regards the effect of insulin on glucose oxidation, for the control subjects ED50 was 30 microunits/ml, whereas in NIDDM patients, insulin exerted no stimulatory effect. The results obtained suggest that the effect of insulin on glucose utilization in normoinsulinemic NIDDM may be diminished in spite of normal insulin binding to receptors. The resistance may be due solely to postreceptor defects, and does not involve antilipolysis.

  14. Insulin demand regulates β cell number via the unfolded protein response.

    PubMed

    Sharma, Rohit B; O'Donnell, Amy C; Stamateris, Rachel E; Ha, Binh; McCloskey, Karen M; Reynolds, Paul R; Arvan, Peter; Alonso, Laura C

    2015-10-01

    Although stem cell populations mediate regeneration of rapid turnover tissues, such as skin, blood, and gut, a stem cell reservoir has not been identified for some slower turnover tissues, such as the pancreatic islet. Despite lacking identifiable stem cells, murine pancreatic β cell number expands in response to an increase in insulin demand. Lineage tracing shows that new β cells are generated from proliferation of mature, differentiated β cells; however, the mechanism by which these mature cells sense systemic insulin demand and initiate a proliferative response remains unknown. Here, we identified the β cell unfolded protein response (UPR), which senses insulin production, as a regulator of β cell proliferation. Using genetic and physiologic models, we determined that among the population of β cells, those with an active UPR are more likely to proliferate. Moreover, subthreshold endoplasmic reticulum stress (ER stress) drove insulin demand-induced β cell proliferation, through activation of ATF6. We also confirmed that the UPR regulates proliferation of human β cells, suggesting that therapeutic UPR modulation has potential to expand β cell mass in people at risk for diabetes. Together, this work defines a stem cell-independent model of tissue homeostasis, in which differentiated secretory cells use the UPR sensor to adapt organ size to meet demand.

  15. Insulin

    MedlinePlus

    ... container that can be closed like a laundry detergent bottle. Check the expiration date on the insulin ... in a hard container like an empty laundry detergent bottle or a metal coffee can. Make sure ...

  16. Agouti regulates adipocyte transcription factors.

    PubMed

    Mynatt, R L; Stephens, J M

    2001-04-01

    Agouti is a secreted paracrine factor that regulates pigmentation in hair follicle melanocytes. Several dominant mutations cause ectopic expression of agouti, resulting in a phenotype characterized by yellow fur, adult-onset obesity and diabetes, increased linear growth and skeletal mass, and increased susceptibility to tumors. Humans also produce agouti protein, but the highest levels of agouti in humans are found in adipose tissue. To mimic the human agouti expression pattern in mice, transgenic mice (aP2-agouti) that express agouti in adipose tissue were generated. The transgenic mice develop a mild form of obesity, and they are sensitized to the action of insulin. We correlated the levels of specific regulators of insulin signaling and adipocyte differentiation with these phenotypic changes in adipose tissue. Signal transducers and activators of transcription (STAT)1, STAT3, and peroxisome proliferator-activated receptor (PPAR)-gamma protein levels were elevated in the transgenic mice. Treatment of mature 3T3-L1 adipocytes recapitulated these effects. These data demonstrate that agouti has potent effects on adipose tissue. We hypothesize that agouti increases adiposity and promotes insulin sensitivity by acting directly on adipocytes via PPAR-gamma.

  17. Insulin

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The manipulation of organic materials--cells, tissues, and even living organisms--offers many exciting possibilities for the future from organic computers to improved aquaculture. Commercial researchers are using the microgravity environment to produce large near perfect protein crystals Research on insulin has yielded crystals that far surpass the quality of insulin crystals grown on the ground. Using these crystals industry partners are working to develop new and improved treatments for diabetes. Other researchers are exploring the possibility of producing antibiotics using plant cell cultures which could lead to both orbital production and the improvement of ground-based antibiotic production.

  18. Engineering of pseudoislets: effect on insulin secretion activity by cell number, cell population, and microchannel networks.

    PubMed

    Kojima, N; Takeuchi, S; Sakai, Y

    2014-05-01

    Engineered pseudoislets reconstituted from a suspension of pancreatic α and β cells have the potential to relieve the shortage of donor islets for transplantation in the treatment of type 1 diabetes. However, the methods to fabricate pseudoislets are not well developed. In this study, we attempted to generate pseudoislets, which show a higher potential for glucose-induced insulin secretion, by altering total cell number, adjusting the cell ratio of pancreatic α and β cells, and fabricating microchannel networks with the use of alginate hydrogel beads. To effectively aggregate α and β cells and hydrogel beads, we used a previously established rapid aggregation method. When pseudoislets were reconstituted with 8,000 cells in a 1:8 α/β-cell ratio, we observed that the glucose-induced insulin secretion was enhanced by 3.1 times compared with the pseudoislets formed with β cells only. In addition, embedding of microchannel networks increased the insulin secretion rate by 4.4 times compared with the pseudoislets without the microstructures. These findings demonstrated that active modification was effective in reconstituting higher functional pseudoislets, which may be useful for islet transplantation.

  19. Adipocytes, myofibers, and cytokine biology: new horizons in the regulation of growth and body composition.

    PubMed

    Jacobi, S K; Gabler, N K; Ajuwon, K M; Davis, J E; Spurlock, M E

    2006-04-01

    Muscle growth in meat animals is a complex process governed by integrated signals emanating from multiple endocrine and immune cells. A generalized phenomenon among meat animal industries is that animals commonly fail to meet their genetic potential for growth in commercial production settings. Therefore, understanding the impact of stress and disease on muscle growth is essential to improving production efficiency. The adipocyte in particular seems to be well positioned as an interface between energy status and immune function, and may thus influence nutrient partitioning and growth through a combination of signals that influence fat metabolism, glucose uptake, and insulin sensitivity. Adipocytes and myofibers are active participants in the innate immune response, and as such, produce a number of metabolic regulators, including leptin, adiponectin, and proinflammatory cytokines. Specifically, adipocytes and muscle cells respond directly to bacterial lipopolysaccharide (LPS) by producing interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha). However, adipocytes are also the predominant source of the antiinflammatory hormone adiponectin, which regulates the nuclear factor kappa-B transcription factor. The ability to recognize antigens and produce regulatory molecules strategically positions adipocytes and myofibers to regulate growth locally, and to reciprocally regulate metabolism peripherally.

  20. RNA-binding protein PSPC1 promotes the differentiation-dependent nuclear export of adipocyte RNAs.

    PubMed

    Wang, Jiexin; Rajbhandari, Prashant; Damianov, Andrey; Han, Areum; Sallam, Tamer; Waki, Hironori; Villanueva, Claudio J; Lee, Stephen D; Nielsen, Ronni; Mandrup, Susanne; Reue, Karen; Young, Stephen G; Whitelegge, Julian; Saez, Enrique; Black, Douglas L; Tontonoz, Peter

    2017-03-01

    A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex, promotes adipogenesis in vitro and is important for mature adipocyte function in vivo. Cross-linking and immunoprecipitation followed by RNA sequencing revealed that PSPC1 binds to intronic and 3'-untranslated regions of a number of adipocyte RNAs, including the RNA encoding the transcriptional regulator EBF1. Purification of the paraspeckle complex from adipocytes further showed that PSPC1 associates with the RNA export factor DDX3X in a differentiation-dependent manner. Remarkably, PSPC1 relocates from the nucleus to the cytoplasm during differentiation, coinciding with enhanced export of adipogenic RNAs. Mice lacking PSPC1 in fat displayed reduced lipid storage and adipose tissue mass and were resistant to diet-induced obesity and insulin resistance due to a compensatory increase in energy expenditure. These findings highlight a role for PSPC1-dependent RNA maturation in the posttranscriptional control of adipose development and function.

  1. Convergence and divergence of the signaling pathways for insulin and phosphoinositolglycans.

    PubMed

    Müller, G; Wied, S; Piossek, C; Bauer, A; Bauer, J; Frick, W

    1998-05-01

    Phosphoinositolglycan molecules isolated from insulin-sensitive mammalian tissues have been demonstrated in numerous in vitro studies to exert partial insulin-mimetic activity on glucose and lipid metabolism in insulin-sensitive cells. However, their ill-defined structures, heterogeneous nature, and limited availability have prohibited the analysis of the underlying molecular mechanism. Phosphoinositolglycan-peptide (PIG-P) of defined and homogeneous structure prepared in large scale from the core glycan of a glycosyl-phosphatidylinositol-anchored membrane protein from Saccharomyces cerevisiae has recently been shown to stimulate glucose transport as well as a number of glucose-metabolizing enzymes and pathways to up to 90% (at 2 to 10 microns) of the maximal insulin effect in isolated rat adipocytes, cardiomyocytes, and diaphragms (G. Müller et al., 1997, Endocrinology 138: 3459-3476). Consequently, we used this PIG-P for the present study in which we compare its intracellular signaling with that of insulin. The activation of glucose transport by both PIG-P and insulin in isolated rat adipocytes and diaphragms was found to require stimulation of phosphatidylinositol (PI) 3-kinase but to be independent of functional p70S6kinase and mitogen-activated protein kinase. The increase in glycerol-3-phosphate acyltransferase activity in rat adipocytes in response to PIG-P and insulin was dependent on both PI 3-kinase and p70S6kinase. This suggest that the signaling pathways for PIG-P and insulin to glucose transport and metabolism converage at the level of PI 3-kinase. A component of the PIG-P signaling pathway located up-stream of PI 3-kinase was identified by desensitization of isolated rat adipocytes for PIG-P action by combined treatment with trypsin and NaCl under conditions that preserved cell viability and the insulin-mimetic activity of sodium vanadate but completely blunted the insulin response. Incubation of the cells with either trypsin or NaCl alone was

  2. Convergence and divergence of the signaling pathways for insulin and phosphoinositolglycans.

    PubMed Central

    Müller, G.; Wied, S.; Piossek, C.; Bauer, A.; Bauer, J.; Frick, W.

    1998-01-01

    Phosphoinositolglycan molecules isolated from insulin-sensitive mammalian tissues have been demonstrated in numerous in vitro studies to exert partial insulin-mimetic activity on glucose and lipid metabolism in insulin-sensitive cells. However, their ill-defined structures, heterogeneous nature, and limited availability have prohibited the analysis of the underlying molecular mechanism. Phosphoinositolglycan-peptide (PIG-P) of defined and homogeneous structure prepared in large scale from the core glycan of a glycosyl-phosphatidylinositol-anchored membrane protein from Saccharomyces cerevisiae has recently been shown to stimulate glucose transport as well as a number of glucose-metabolizing enzymes and pathways to up to 90% (at 2 to 10 microns) of the maximal insulin effect in isolated rat adipocytes, cardiomyocytes, and diaphragms (G. Müller et al., 1997, Endocrinology 138: 3459-3476). Consequently, we used this PIG-P for the present study in which we compare its intracellular signaling with that of insulin. The activation of glucose transport by both PIG-P and insulin in isolated rat adipocytes and diaphragms was found to require stimulation of phosphatidylinositol (PI) 3-kinase but to be independent of functional p70S6kinase and mitogen-activated protein kinase. The increase in glycerol-3-phosphate acyltransferase activity in rat adipocytes in response to PIG-P and insulin was dependent on both PI 3-kinase and p70S6kinase. This suggest that the signaling pathways for PIG-P and insulin to glucose transport and metabolism converage at the level of PI 3-kinase. A component of the PIG-P signaling pathway located up-stream of PI 3-kinase was identified by desensitization of isolated rat adipocytes for PIG-P action by combined treatment with trypsin and NaCl under conditions that preserved cell viability and the insulin-mimetic activity of sodium vanadate but completely blunted the insulin response. Incubation of the cells with either trypsin or NaCl alone was

  3. Functional Human Beige Adipocytes from Induced Pluripotent Stem Cells.

    PubMed

    Guénantin, Anne-Claire; Briand, Nolwenn; Capel, Emilie; Dumont, Florent; Morichon, Romain; Provost, Claire; Stillitano, Francesca; Jeziorowska, Dorota; Siffroi, Jean-Pierre; Hajjar, Roger J; Fève, Bruno; Hulot, Jean-Sébastien; Collas, Philippe; Capeau, Jacqueline; Vigouroux, Corinne

    2017-03-07

    Activation of thermogenic beige adipocytes has recently emerged as a promising therapeutic target in obesity and diabetes. Relevant human models for beige adipocyte differentiation are essential to implement such therapeutic strategies. We report a straightforward and efficient protocol to generate functional human beige adipocytes from induced pluripotent stem cells (hiPSCs). Without overexpression of exogenous adipogenic genes, our method recapitulates an adipogenic developmental pathway through successive mesodermal and adipogenic progenitor stages. hiPSC-derived adipocytes are insulin-sensitive and display beige-specific markers and functional properties including upregulation of thermogenic genes, increased mitochondrial content and increased oxygen consumption upon activation with cAMP analogues. Engraftment of hiPSC-derived adipocytes in mice produces well-organized and vascularized adipose tissue, capable of β-adrenergic-responsive glucose uptake. Our model of human beige adipocyte development provides a new and scalable tool for disease modeling and therapeutic screening.

  4. Syntaxin 4, VAMP2, and/or VAMP3/cellubrevin are functional target membrane and vesicle SNAP receptors for insulin-stimulated GLUT4 translocation in adipocytes.

    PubMed Central

    Olson, A L; Knight, J B; Pessin, J E

    1997-01-01

    Introduction of the cytoplasmic domain of syntaxin 4, using either recombinant vaccinia virus or single-cell microinjection, resulted in an inhibition of insulin-stimulated GLUT4 but not GLUT1 translocation to the plasma membrane. This was specific for syntaxin 4, since neither the expression of syntaxin 3 nor the expression of a syntaxin 4 mutant in which the vesicle-associated membrane protein (VAMP) binding site was deleted had any significant effect. Consistent with the requirement for a functional VAMP binding site, expression of the cytoplasmic domains of VAMP2 or VAMP3/cellubrevin also resulted in an inhibition of insulin-stimulated GLUT4 translocation. In addition, immunoprecipitation of the expressed syntaxin 4 cytoplasmic domain resulted in an insulin-stimulated increase in the coimmunoprecipitation of GLUT4-containing vesicles. Together, these data demonstrate that syntaxin 4, VAMP2, and/or VAMP3/cellubrevin can function as target membrane and vesicle SNAP receptors, respectively, for insulin-responsive GLUT4 translocation to the plasma membrane. PMID:9111311

  5. Effect of Sutherlandia frutescens on the lipid metabolism in an insulin resistant rat model and 3T3-L1 adipocytes.

    PubMed

    MacKenzie, Janine; Koekemoer, Trevor C; Roux, Saartjie; van de Venter, Maryna; Dealtry, Gill B

    2012-12-01

    High fat diet induced insulin resistance correlates with dyslipidaemia and ectopic fat deposits in skeletal muscle and liver. The effects of Sutherlandia frutescens, an antidiabetic medicinal plant, on lipid metabolism were evaluated in an insulin resistant (IR) rat model and in 3 T3-preadipocytes. Wistar rats received normal diet (ND) or high fat diet (HFD). After the onset of IR in the HFD group, the rats were subdivided into two subgroups, which either continued with HFD or were treated with 50 mg S. frutescens/kg BW/day and HFD (HFD + SF). After 4 weeks, the HFD + SF rats had a significantly lower body weight than the HFD rats (p < 0.05). Blood plasma analysis showed a decrease in insulin, free fatty acids and triglycerides. Related changes in lipid parameters were observed in the liver, skeletal muscle and adipose tissue. To investigate the effects of S. frutescens on adipose tissue, 3 T3-L1 cells were used as a model. Treatment with S. frutescens led to a decrease in triglyceride accumulation, whilst glucose consumption and lactate production were increased (p < 0.05). These results indicate that S. frutescens directly affects mitochondrial activity and lipid biosynthesis in adipose tissue and provide a mechanism by which S. frutescens can restore insulin sensitivity by modulating fatty acid biosynthesis.

  6. Lilly lecture 1995. Glucose transport: pivotal step in insulin action.

    PubMed

    Kahn, B B

    1996-11-01

    The effect of insulin to acutely stimulate glucose uptake into muscle and adipose tissue is essential for normal glucose homeostasis. The GLUT4 glucose transporter is a major mediator of this action, and insulin recruits GLUT4 from an intracellular pool to the plasma membrane. An important pathologic feature of obesity, NIDDM, and to a lesser extent IDDM is resistance to insulin-stimulated glucose uptake. Investigations of the mechanisms have revealed tissue-specific regulation of GLUT4 with decreased gene expression in adipose cells but not in skeletal muscle. This has led to the hypothesis that alterations in the trafficking of the GLUT4 vesicle or in the exposure or activation of the GLUT4 transporter may cause insulin resistance in skeletal muscle in obesity and diabetes. Exercise training increases GLUT4 expression in muscle in association with enhanced glucose tolerance in vivo. Transgenic mice have been created to investigate other approaches to improve insulin action on glucose transport. Overexpression of GLUT4 in adipocytes of transgenic mice increases the proportion of GLUT4 on the plasma membrane and enhances insulin sensitivity in vivo. Altering insulin signaling by overexpressing p21ras in adipocytes of transgenic mice results in increased GLUT4 on the plasma membrane in the absence of insulin and increases insulin sensitivity in vitro and in vivo. Thus, glucose transport is a pivotal step in whole-body insulin action. Strategies to increase the number of GLUT4 transporters that are functionally inserted in the plasma membrane in muscle and adipocytes may lead to new therapies to treat or prevent NIDDM.

  7. ADMET: ADipocyte METabolism mathematical model.

    PubMed

    Micheloni, Alessio; Orsi, Gianni; De Maria, Carmelo; Vozzi, Giovanni

    2015-01-01

    White fat cells have an important physiological role in maintaining triglyceride and free fatty acid levels due to their fundamental storage property, as well as determining insulin resistance. ADipocyte METabolism is a mathematical model that mimics the main metabolic pathways of human white fat cell, connecting inputs (composition of culture medium) to outputs (glycerol and free fatty acid release). It is based on a set of nonlinear differential equations, implemented in Simulink® and controlled by cellular energetic state. The validation of this model is based on a comparison between the simulation results and a set of experimental data collected from the literature.

  8. Metformin induces glucose uptake in human preadipocyte-derived adipocytes from various fat depots.

    PubMed

    Fischer, M; Timper, K; Radimerski, T; Dembinski, K; Frey, D M; Zulewski, H; Keller, U; Müller, B; Christ-Crain, M; Grisouard, J

    2010-04-01

    To evaluate the effect of metformin on basal and insulin-induced glucose uptake in subcutaneous and visceral preadipocyte-derived adipocytes from obese and non-obese patients, preadipocytes were obtained from subcutaneous and visceral fat depots during abdominal surgery. Differentiation efficiency was evaluated by measurement of intracellular triglyceride accumulation. Preadipocyte-derived adipocytes were treated with metformin (1 mM) for 24 h with or without the addition of insulin (100 nM) for 20 min and glucose uptake was measured. In cells from each donor, intracellular triglyceride accumulation was more abundant in subcutaneous preadipocyte-derived adipocytes than in visceral preadipocyte-derived adipocytes (p < 0.001). Insulin stimulated glucose uptake in subcutaneous preadipocyte-derived adipocytes from both non-obese and obese patients (p < 0.001 vs. basal). In visceral preadipocyte-derived adipocytes, insulin did not increase basal glucose uptake. In subcutaneous preadipocyte-derived adipocytes from non-obese and obese patients, metformin alone increased glucose uptake to 2.7 +/- 0.2 (p < 0.001) and 2.1 +/- 0.1 fold (p < 0.001) respectively. Metformin increased glucose uptake in visceral preadipocyte-derived adipocytes from non-obese (1.7 +/- 0.1 fold vs. basal, p < 0.001) and obese (2.0 +/- 0.2 fold vs. basal, p < 0.001) patients. Combined treatment with metformin and insulin increased glucose uptake in subcutaneous preadipocyte-derived adipocytes from both non-obese and obese patients (p < 0.001 vs. insulin alone). In preadipocyte-derived adipocytes glucose uptake is induced by metformin independent of the fat depot origin of the preadipocytes (subcutaneous or visceral) and the obesity state of the patients (non-obese or obese). In adipocytes, metformin seems to induce glucose uptake independent of insulin suggesting an alternative mechanism of action of this drug.

  9. Cadmium modulates adipocyte functions in metallothionein-null mice

    SciTech Connect

    Kawakami, Takashige; Nishiyama, Kaori; Kadota, Yoshito; Sato, Masao; Inoue, Masahisa; Suzuki, Shinya

    2013-11-01

    Our previous study has demonstrated that exposure to cadmium (Cd), a toxic heavy metal, causes a reduction of adipocyte size and the modulation of adipokine expression. To further investigate the significance of the Cd action, we studied the effect of Cd on the white adipose tissue (WAT) of metallothionein null (MT{sup −/−}) mice, which cannot form atoxic Cd–MT complexes and are used for evaluating Cd as free ions, and wild type (MT{sup +/+}) mice. Cd administration more significantly reduced the adipocyte size of MT{sup −/−} mice than that of MT{sup +/+} mice. Cd exposure also induced macrophage recruitment to WAT with an increase in the expression level of Ccl2 (MCP-1) in the MT{sup −/−} mice. The in vitro exposure of Cd to adipocytes induce triglyceride release into culture medium, decrease in the expression levels of genes involved in fatty acid synthesis and lipid hydrolysis at 24 h, and at 48 h increase in phosphorylation of the lipid-droplet-associated protein perilipin, which facilitates the degradation of stored lipids in adipocytes. Therefore, the reduction in adipocyte size by Cd may arise from an imbalance between lipid synthesis and lipolysis. In addition, the expression levels of leptin, adiponectin and resistin decreased in adipocytes. Taken together, exposure to Cd may induce unusually small adipocytes and modulate the expression of adipokines differently from the case of physiologically small adipocytes, and may accelerate the risk of developing insulin resistance and type 2 diabetes. - Highlights: • Cd causes a marked reduction in adipocyte size in MT-null mice. • Cd enhances macrophage migration into adipose tissue and disrupt adipokine secretion. • MT gene alleviates Cd-induced adipocyte dysfunctions. • Cd enhances the degradation of stored lipids in adipocytes, mediated by perilipin. • Cd induces unusually small adipocytes and the abnormal expression of adipokines.

  10. Dynamics of Adipocyte Turnover in Humans

    SciTech Connect

    Spalding, K; Arner, E; Westermark, P; Bernard, S; Buchholz, B; Bergmann, O; Blomqvist, L; Hoffstedt, J; Naslund, E; Britton, T; Concha, H; Hassan, M; Ryden, M; Frisen, J; Arner, P

    2007-07-16

    Obesity is increasing in an epidemic fashion in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells is thought to be most important. We show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese and even under extreme conditions, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analyzing the integration of {sup 14}C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in obesity, suggesting a tight regulation of fat cell number that is independent of metabolic profile in adulthood. The high turnover of adipocytes establishes a new therapeutic target for pharmacological intervention in obesity.

  11. Super-resolution microscopy reveals the insulin-resistance-regulated reorganization of GLUT4 on plasma membranes.

    PubMed

    Gao, Lan; Chen, Junling; Gao, Jing; Wang, Hongda; Xiong, Wenyong

    2017-01-15

    GLUT4 (also known as SLC2A4) is essential for glucose uptake in skeletal muscles and adipocytes, which play central roles in whole-body glucose metabolism. Here, using direct stochastic optical reconstruction microscopy (dSTORM) to investigate the characteristics of plasma-membrane-fused GLUT4 at the single-molecule level, we have demonstrated that insulin and insulin resistance regulate the spatial organization of GLUT4 in adipocytes. Stimulation with insulin shifted the balance of GLUT4 on the plasma membrane toward a more dispersed configuration. In contrast, insulin resistance induced a more clustered distribution of GLUT4 and increased the mean number of molecules per cluster. Furthermore, our data demonstrate that the F(5)QQI motif and lipid rafts mediate the maintenance of GLUT4 clusters on the plasma membrane. Mutation of F(5)QQI (F(5)QQA-GLUT4) induced a more clustered distribution of GLUT4; moreover, destruction of lipid rafts in adipocytes expressing F(5)QQA-GLUT4 dramatically decreased the percentage of large clusters and the mean number of molecules per cluster. In conclusion, our data clarify the effects of insulin stimulation or insulin resistance on GLUT4 reorganization on the plasma membrane and reveal new pathogenic mechanisms of insulin resistance.

  12. Differential adipogenic and inflammatory properties of small adipocytes in Zucker Obese and Lean rats.

    PubMed

    Liu, Alice; Sonmez, Alper; Yee, Gail; Bazuine, Merlijn; Arroyo, Matilde; Sherman, Arthur; McLaughlin, Tracey; Reaven, Gerald; Cushman, Samuel; Tsao, Philip

    2010-10-01

    We recently reported that a preponderance of small adipose cells, decreased expression of cell differentiation markers, and enhanced inflammatory activity in human subcutaneous whole adipose tissue were associated with insulin resistance. To test the hypothesis that small adipocytes exhibited these differential properties, we characterised small adipocytes from epididymal adipose tissue of Zucker Obese (ZO) and Lean (ZL) rats. Rat epididymal fat pads were removed and adipocytes isolated by collagenase digestion. Small adipocytes were separated by sequential filtration through nylon meshes. Adipocytes were fixed in osmium tetroxide for cell size distribution analysis via Beckman Coulter Multisizer. Quantitative real-time PCR for cell differentiation and inflammatory genes was performed. Small adipocytes represented a markedly greater percentage of the total adipocyte population in ZO than ZL rats (58±4% vs. 12±3%, p<0.001). In ZO rats, small as compared with total adipocytes had 4-fold decreased adiponectin, and 4-fold increased visfatin and IL-6 levels. Comparison of small adipocytes in ZO versus ZL rats revealed 3-fold decreased adiponectin and PPARγ levels, and 2.5-fold increased IL-6. In conclusion, ZO rat adipose tissue harbours a large proportion of small adipocytes that manifest impaired cell differentiation and pro-inflammatory activity, two mechanisms by which small adipocytes may contribute to insulin resistance.

  13. Ablation of TSC2 Enhances Insulin Secretion by Increasing the Number of Mitochondria through Activation of mTORC1

    PubMed Central

    Koyanagi, Maki; Asahara, Shun-ichiro; Matsuda, Tomokazu; Hashimoto, Naoko; Shigeyama, Yutaka; Shibutani, Yuki; Kanno, Ayumi; Fuchita, Megumi; Mikami, Tomoko; Hosooka, Tetsutya; Inoue, Hiroshi; Matsumoto, Michihiro; Koike, Masato; Uchiyama, Yasuo; Noda, Tetsuo; Seino, Susumu; Kasuga, Masato; Kido, Yoshiaki

    2011-01-01

    Aim We previously found that chronic tuberous sclerosis protein 2 (TSC2) deletion induces activation of mammalian target of rapamycin Complex 1 (mTORC1) and leads to hypertrophy of pancreatic beta cells from pancreatic beta cell-specific TSC2 knockout (βTSC2−/−) mice. The present study examines the effects of TSC2 ablation on insulin secretion from pancreatic beta cells. Methods Isolated islets from βTSC2−/− mice and TSC2 knockdown insulin 1 (INS-1) insulinoma cells treated with small interfering ribonucleic acid were used to investigate insulin secretion, ATP content and the expression of mitochondrial genes. Results Activation of mTORC1 increased mitochondrial DNA expression, mitochondrial density and ATP production in pancreatic beta cells of βTSC2−/− mice. In TSC2 knockdown INS-1 cells, mitochondrial DNA expression, mitochondrial density and ATP production were increased compared with those in control INS-1 cells, consistent with the phenotype of βTSC2−/− mice. TSC2 knockdown INS-1 cells also exhibited augmented insulin secretory response to glucose. Rapamycin inhibited mitochondrial DNA expression and ATP production as well as insulin secretion in response to glucose. Thus, βTSC2−/− mice exhibit hyperinsulinemia due to an increase in the number of mitochondria as well as enlargement of individual beta cells via activation of mTORC1. Conclusion Activation of mTORC1 by TSC2 ablation increases mitochondrial biogenesis and enhances insulin secretion from pancreatic beta cells. PMID:21886784

  14. Transdifferentiation properties of adipocytes in the adipose organ.

    PubMed

    Cinti, Saverio

    2009-11-01

    Mammals have two types of adipocytes, white and brown, but their anatomy and physiology is different. White adipocytes store lipids, and brown adipocytes burn them to produce heat. Previous descriptions implied their localization in distinct sites, but we demonstrated that they are mixed in many depots, raising the concept of adipose organ. We explain the reason for their cohabitation with the hypothesis of reversible physiological transdifferentiation; they are able to convert one into each other. If needed, the brown component of the organ could increase at the expense of the white component and vice versa. This plasticity is important because the brown phenotype of the organ associates with resistance to obesity and related disorders. Another example of physiological transdifferetiation of adipocytes is offered by the mammary gland; the pregnancy hormonal stimuli seems to trigger a reversible transdifferentiation of adipocytes into milk-secreting epithelial glands. The obese adipose organ is infiltrated by macrophages inducing chronic inflamation that is widely considered as a causative factor for insulin resistance. We showed that the vast majority of macrophages infiltrating the obese organ are arranged around dead adipocytes, forming characteristic crown-like structures. We recently found that visceral fat is more infiltrated than the subcutaneous fat despite a smaller size of visceral adipocytes. This suggests a different susceptibility of visceral and subcutaneous adipocytes to death, raising the concept of smaller critical death size that could be important to explain the key role of visceral fat for the metabolic disorders associated with obesity.

  15. Insulin-like growth factor 1 gene (CA)n repeats and a variable number of tandem repeats of the insulin gene in Brazilian children born small for gestational age

    PubMed Central

    Coletta, Rocio R D; Jorge, Alexander A L; D' Alva, Catarina Brasil; Pinto, Emília M; Billerbeck, Ana Elisa C; Pachi, Paulo R; Longui, Carlos A; Garcia, Ricardo M; Boguszewski, Margaret; Arnhold, Ivo J P; Mendonca, Berenice B; Costa, Elaine M F

    2013-01-01

    OBJECTIVE: To investigate the influence of (CA)n repeats in the insulin-like growth factor 1 gene and a variable number of tandem repeats of the insulin gene on birth size in children who are small or adequate-sized for gestational age and to correlate these polymorphisms with serum insulin-like growth factor 1 levels and insulin sensitivity in children who are small for gestational age, with and without catch-up growth. PATIENTS AND METHODS: We evaluated 439 infants: 297 that were adequate-sized for gestational age and 142 that were small for gestational age (66 with and 76 without catch-up). The number of (CA)n repeat in the insulin-like growth factor 1 gene and a variable number of tandem repeats in the insulin gene were analyzed using GENESCAN software and polymerase chain reaction followed by enzymatic digestion, respectively. Clinical and laboratory data were obtained from all patients. RESULTS: The height, body mass index, paternal height, target height and insulin-like growth factor 1 serum levels were higher in children who were small for gestational age with catch-up. There was no difference in the allelic and genotypic distributions of both polymorphisms between the adequate-sized and small infants or among small infants with and without catch-up. Similarly, the polymorphisms were not associated with clinical or laboratory variables. CONCLUSION: Polymorphisms of the (CA)n repeats of the insulin-like growth factor 1 gene and a variable number of tandem repeats of the insulin gene, separately or in combination, did not influence pre- or postnatal growth, insulin-like growth factor 1 serum levels or insulin resistance. PMID:23778474

  16. Adipose Estrogen and Increased Breast Cancer Risk in Obesity: Regulation by Leptin and Insulin

    DTIC Science & Technology

    2006-09-01

    associated with insulin resistance we had also proposed to determine the induction of Aromatase and βHSD5 mRNA expression in response to insulin and...Metabolic insulin resistance was determined by measuring insulin mediated glucose uptake. Glucose uptake was reduced by 50-70% in adipocytes...conditions in our cell culture system to mimic metabolic insulin resistance . These “insulin-resistant” adipocytes are currently being used to

  17. Inhibition of adipocyte inflammation and macrophage chemotaxis by butein.

    PubMed

    Wang, Zheng; Lee, Youngyi; Eun, Jae Soon; Bae, Eun Ju

    2014-09-05

    Adipose tissue inflammation has been proposed as a therapeutic target for the treatment of obesity and metabolic disorders such as insulin resistance and type 2 diabetes. Butein, a polyphenol of vegetal origin, exhibits anti-inflammatory effects in macrophages but it was not reported whether butein prevents adipocyte inflammation. Here, we investigated the effects of butein on adipocyte inflammation in 3T3-L1 cells and performed functional macrophage migration assays. Butein opposed the stimulation of inducible nitric oxide synthase (iNOS) protein expression and of nitric oxide production by simultaneous treatment of adipocytes with tumor necrosis factor alpha (TNFα), lipopolysaccharide (LPS), and interferon gamma (TLI). In addition, butein inhibited mRNA expression of pro-inflammatory genes and chemokines in adipocytes stimulated with TLI or conditioned medium from RAW 264.7 macrophages treated with LPS. These effects were associated with suppression of inhibitor of kappa B alpha degradation induced by TNFα and with nuclear factor-kappa B (NF-κB) p65 phosphorylation and acetylation. Moreover, butein prevented phosphorylation of extracellular signal-regulated kinases, c-Jun N-terminal kinase, and the mitogen-activated protein kinase (MAPK) p38. These results suggest that butein suppresses adipocyte inflammation by inhibiting NF-κB/MAPK-dependent transcriptional activity. Furthermore, conditioned media from adipocytes stimulated macrophage chemotaxis, whereas media from adipocytes treated with butein blocked macrophage migration, an effect that was consistent with suppression of MCP-1 secretion by adipocytes treated with butein. In addition, macrophages treated with butein exhibited a reduced ability to migrate toward adipocyte CM. In conclusion, butein may represent a therapeutic agent to prevent adipose tissue inflammation and the obesity-linked insulin resistance.

  18. Ubc9 Impairs Activation of the Brown Fat Energy Metabolism Program in Human White Adipocytes.

    PubMed

    Hartig, Sean M; Bader, David A; Abadie, Kathleen V; Motamed, Massoud; Hamilton, Mark P; Long, Weiwen; York, Brian; Mueller, Michaela; Wagner, Martin; Trauner, Michael; Chan, Lawrence; Bajaj, Mandeep; Moore, David D; Mancini, Michael A; McGuire, Sean E

    2015-09-01

    Insulin resistance and type 2 diabetes mellitus (T2DM) result from an inability to efficiently store and catabolize surplus energy in adipose tissue. Subcutaneous adipocytes protect against insulin resistance and T2DM by coupling differentiation with the induction of brown fat gene programs for efficient energy metabolism. Mechanisms that disrupt these programs in adipocytes are currently poorly defined, but represent therapeutic targets for the treatment of T2DM. To gain insight into these mechanisms, we performed a high-throughput microscopy screen that identified ubiquitin carrier protein 9 (Ubc9) as a negative regulator of energy storage in human sc adipocytes. Ubc9 depletion enhanced energy storage and induced the brown fat gene program in human sc adipocytes. Induction of adipocyte differentiation resulted in decreased Ubc9 expression commensurate with increased brown fat gene expression. Thiazolidinedione treatment reduced the interaction between Ubc9 and peroxisome proliferator-activated receptor (PPAR)γ, suggesting a mechanism by which Ubc9 represses PPARγ activity. In support of this hypothesis, Ubc9 overexpression remodeled energy metabolism in human sc adipocytes by selectively inhibiting brown adipocyte-specific function. Further, Ubc9 overexpression decreased uncoupling protein 1 expression by disrupting PPARγ binding at a critical uncoupling protein 1 enhancer region. Last, Ubc9 is significantly elevated in sc adipose tissue isolated from mouse models of insulin resistance as well as diabetic and insulin-resistant humans. Taken together, our findings demonstrate a critical role for Ubc9 in the regulation of sc adipocyte energy homeostasis.

  19. Comparison of the adipogenesis in intramuscular and subcutaneous adipocytes from Bamei and Landrace pigs.

    PubMed

    Zhang, Guo Hua; Lu, Jian Xiong; Chen, Yan; Zhao, Yong Qing; Guo, Peng Hui; Yang, Ju Tian; Zang, Rong Xin

    2014-08-01

    Fat deposition is a complex process involving proliferation, differentiation, and lipogenesis of adipocytes. Bamei and Landrace are considered to represent fat- and lean-type pig breeds. Subcutaneous (SC) and intramuscular (IM) pre-adipocytes were cultured to compare the proliferation and lipogenesis in these breeds. The differentiated adipocytes were exposed to glucose or insulin to evaluate their effects on lipogenesis and lipogenic gene expression. Pre-adipocytes proliferated dramatically faster in SC vs. IM cells, and in Bamei vs. Landrace breeds. Lipogenesis and lipogenic gene expression had a greater increase in Bamei than in Landrace, and in SC vs. IM in the process of differentiation. Glucose markedly promoted lipogenesis and lipogenic gene expression in differentiated adipocytes. The stimulation of high-glucose levels on lipogenesis and ChREBP and lipogenic gene expression was higher in SC than IM adipocytes, and in Bamei vs. Landrace. Insulin largely increased SREBP-1c expression, however it modestly stimulated lipogenesis and lipogenic gene expression, and there was no difference between cell populationsor between breeds. These data demonstrated that regional and varietal differences obviously existed in the development of porcine adipocytes. The proliferation and differentiation capacity of pre-adipocytes, and the adipocyte lipogenesis stimulated by glucose, are stronger in Bamei than Landrace, and in SC vs. IM adipocytes independent of breed.

  20. Effects of heparin on insulin binding and biological activity

    SciTech Connect

    Kriauciunas, K.M.; Grigorescu, F.; Kahn, C.R.

    1987-02-01

    The effect of heparin, a polyanionic glycosaminoglycan known to alter the function of many proteins, on insulin binding and bioactivity was studied. Cultured human lymphocytes (IM-9) were incubated with varying concentrations of heparin, then extensively washed, and /sup 125/I-labeled insulin binding was measured. Heparin at concentrations used clinically for anticoagulation (1-50 U/ml) inhibited binding in a dose-dependent manner; 50% inhibition of binding occurred with 5-10 U/ml. Scatchard analysis indicated that the decrease in binding was due to a decrease in both the affinity and the apparent number of available insulin receptors. The effect occurred within 10 min at 22 degrees C and persisted even after the cells were extensively washed. Inhibition of insulin binding also occurred when cells were preincubated with heparinized plasma or heparinized serum but not when cells were incubated with normal serum or plasma from blood anticoagulated with EDTA. By contrast, other polyanions and polycations, e.g., poly-L-glutamic acid, poly-L-lysine, succinylated poly-L-lysine, and histone, did not inhibit binding. Heparin also inhibited insulin binding in Epstein-Barr (EB) virus-transformed lymphocytes but had no effect on insulin binding to isolated adipocytes, human erythrocytes, or intact hepatoma cells. When isolated adipocytes were incubated with heparin, there was a dose-dependent inhibition of insulin-stimulated glucose oxidation and, to a lesser extent, of basal glucose oxidation. Although heparin has no effect on insulin binding to intact hepatoma cells, heparin inhibited both insulin binding and insulin-stimulated autophosphorylation in receptors solubilized from these cells.

  1. Decreased beige adipocyte number and mitochondrial respiration coincide with reduced FGF21 gene expression in Sprague Dawley rats fed prenatal low protein and postnatal high fat diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have shown that protein malnutrition during fetal growth followed by postnatal high-fat diets results in a rapid increase in subcutaneous adipose tissue mass in the offspring contributing to development of obesity and insulin resistance. Recent studies have shown that the absence of a key transcr...

  2. Skeletal muscle insulin resistance in zebrafish induces alterations in β-cell number and glucose tolerance in an age- and diet-dependent manner.

    PubMed

    Maddison, Lisette A; Joest, Kaitlin E; Kammeyer, Ryan M; Chen, Wenbiao

    2015-04-15

    Insulin resistance creates an environment that promotes β-cell failure and development of diabetes. Understanding the events that lead from insulin resistance to diabetes is necessary for development of effective preventional and interventional strategies, and model systems that reflect the pathophysiology of disease progression are an important component toward this end. We have confirmed that insulin enhances glucose uptake in zebrafish skeletal muscle and have developed a zebrafish model of skeletal muscle insulin resistance using a dominant-negative IGF-IR. These zebrafish exhibit blunted insulin signaling and glucose uptake in the skeletal muscle, confirming insulin resistance. In young animals, we observed an increase in the number of β-cells and normal glucose tolerance that was indicative of compensation for insulin resistance. In older animals, the β-cell mass was reduced to that of control with the appearance of impaired glucose clearance but no elevation in fasting blood glucose. Combined with overnutrition, the insulin-resistant animals have an increased fasting blood glucose compared with the control animals, demonstrating that the β-cells in the insulin-resistant fish are in a vulnerable state. The relatively slow progression from insulin resistance to glucose intolerance in this model system has the potential in the future to test cooperating genes or metabolic conditions that may accelerate the development of diabetes and provide new therapeutic targets.

  3. Communication between natural killer T cells and adipocytes in obesity

    PubMed Central

    Satoh, Masashi; Iwabuchi, Kazuya

    2016-01-01

    ABSTRACT Adipose tissue contains various types of immunocompetent cells, and these cells of innate and adaptive immunity control adipose tissue inflammation that blunts insulin sensitivity. Recent studies have shown that adipocytes express CD1d and present lipid antigen(s) to activate natural killer T (NKT) cells. The function of adipocytes is in turn modulated by cytokines that NKT cells produce to alter the expression of anti-inflammatory adipokine(s) and the production of inflammatory and chemoattractant cytokines. These in vitro studies imply that the interaction between adipocytes and NKT cells might affect the development of not only obesity but also obesity-related diseases. To test the importance of the interaction between NKT cells and adipocytes, we examined whether an adipocyte-specific CD1d deletion affected the development of obesity, which had been demonstrated with B6.CD1d−/− (CD1d KO). We found that the interaction is indeed important to induce adipose tissue inflammation and insulin resistance in response to lipid excess. In this commentary, the advances and controversies on NKT cells and obesity are discussed based on our recent report that NKT cells play a pivotal role in the regulation of adipose tissue by communicating with adipocytes via CD1d. PMID:27994954

  4. Insulin resistance and hypertension: new insights.

    PubMed

    Soleimani, Manoocher

    2015-03-01

    Insulin resistance is associated with hypertension. Nakamura et al. demonstrate in rodents and humans with insulin resistance that while the stimulatory effect of insulin on glucose uptake in adipocytes, mediated via insulin receptor substrate 1 (IRS1), was severely diminished, its effect on salt reabsorption in the kidney proximal tubule, mediated via IRS2, was preserved. Compensatory hyperinsulinemia in individuals with insulin resistance may enhance salt absorption in the proximal tubule, resulting in a state of salt overload and hypertension.

  5. Adipocyte secreted factors enhance aggressiveness of prostate carcinoma cells.

    PubMed

    Moreira, Ângela; Pereira, Sofia S; Costa, Madalena; Morais, Tiago; Pinto, Ana; Fernandes, Rúben; Monteiro, Mariana P

    2015-01-01

    Obesity has been associated with increased incidence and risk of mortality of prostate cancer. One of the proposed mechanisms underlying this risk association is the change in adipokines expression that could promote the development and progression of the prostate tumor cells. The main goal of this study was to evaluate the effect of preadipocyte and adipocyte secretome in the proliferation, migration and invasion of androgen independent prostate carcinoma cells (RM1) and to assess cell proliferation in the presence of the adiposity signals leptin and insulin. RM1 cells were co-cultured in with preadipocytes, adipocytes or cultured in their respective conditioned medium. Cell proliferation was assessed by flow cytometry and XTT viability test. Cell migration was evaluated using a wound healing injury assay of RM1 cells cultured with conditioned media. Cellular invasion of RM1 cells co-cultured with adipocytes and preadipocytes was assessed using matrigel membranes. Preadipocyte conditioned medium was associated with a small increase in RM1 proliferation, while adipocytes conditioned media significantly increased RM1 cell proliferation (p<0.01). Adipocytes also significantly increased the RM1 cells proliferation in co-culture (p <0.01). Cell migration was higher in RM1 cells cultured with preadipocyte and adipocyte conditioned medium. RM1 cell invasion was significantly increased after co-culture with preadipocytes and adipocytes (p <0.05). Insulin also increased significantly the cell proliferation in contrast to leptin, which showed no effect. In conclusion, prostate carcinoma cells seem to be influenced by factors secreted by adipocytes that are able to increase their ability to proliferate, migrate and invade.

  6. Adipocyte Secreted Factors Enhance Aggressiveness of Prostate Carcinoma Cells

    PubMed Central

    Moreira, Ângela; Pereira, Sofia S.; Costa, Madalena; Morais, Tiago; Pinto, Ana; Fernandes, Rúben; Monteiro, Mariana P.

    2015-01-01

    Obesity has been associated with increased incidence and risk of mortality of prostate cancer. One of the proposed mechanisms underlying this risk association is the change in adipokines expression that could promote the development and progression of the prostate tumor cells. The main goal of this study was to evaluate the effect of preadipocyte and adipocyte secretome in the proliferation, migration and invasion of androgen independent prostate carcinoma cells (RM1) and to assess cell proliferation in the presence of the adiposity signals leptin and insulin. RM1 cells were co-cultured in with preadipocytes, adipocytes or cultured in their respective conditioned medium. Cell proliferation was assessed by flow cytometry and XTT viability test. Cell migration was evaluated using a wound healing injury assay of RM1 cells cultured with conditioned media. Cellular invasion of RM1 cells co-cultured with adipocytes and preadipocytes was assessed using matrigel membranes. Preadipocyte conditioned medium was associated with a small increase in RM1 proliferation, while adipocytes conditioned media significantly increased RM1 cell proliferation (p<0.01). Adipocytes also significantly increased the RM1 cells proliferation in co-culture (p <0.01). Cell migration was higher in RM1 cells cultured with preadipocyte and adipocyte conditioned medium. RM1 cell invasion was significantly increased after co-culture with preadipocytes and adipocytes (p <0.05). Insulin also increased significantly the cell proliferation in contrast to leptin, which showed no effect. In conclusion, prostate carcinoma cells seem to be influenced by factors secreted by adipocytes that are able to increase their ability to proliferate, migrate and invade. PMID:25928422

  7. Cellular and molecular implications of mature adipocyte dedifferentiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When one looks at the voluminous amount of scientific literature dealing with the molecular regulation of carcass composition, obesity, metabolic syndrome, or diabetes a profound number of papers are printed each week regarding adipocyte involvement in each. To form adipocytes (process termed adipo...

  8. Characterization of adipocytes derived from fibro/adipogenic progenitors resident in human skeletal muscle

    PubMed Central

    Arrighi, N; Moratal, C; Clément, N; Giorgetti-Peraldi, S; Peraldi, P; Loubat, A; Kurzenne, J-Y; Dani, C; Chopard, A; Dechesne, C A

    2015-01-01

    A population of fibro/adipogenic but non-myogenic progenitors located between skeletal muscle fibers was recently discovered. The aim of this study was to determine the extent to which these progenitors differentiate into fully functional adipocytes. The characterization of muscle progenitor-derived adipocytes is a central issue in understanding muscle homeostasis. They are considered as being the cellular origin of intermuscular adipose tissue that develops in several pathophysiological situations. Here fibro/adipogenic progenitors were isolated from a panel of 15 human muscle biopsies on the basis of the specific cell-surface immunophenotype CD15+/PDGFRα+CD56−. This allowed investigations of their differentiation into adipocytes and the cellular functions of terminally differentiated adipocytes. Adipogenic differentiation was found to be regulated by the same effectors as those regulating differentiation of progenitors derived from white subcutaneous adipose tissue. Similarly, basic adipocyte functions, such as triglyceride synthesis and lipolysis occurred at levels similar to those observed with subcutaneous adipose tissue progenitor-derived adipocytes. However, muscle progenitor-derived adipocytes were found to be insensitive to insulin-induced glucose uptake, in association with the impairment of phosphorylation of key insulin-signaling effectors. Our findings indicate that muscle adipogenic progenitors give rise to bona fide white adipocytes that have the unexpected feature of being insulin-resistant. PMID:25906156

  9. Activating HSP72 in rodent skeletal muscle increases mitochondrial number and oxidative capacity and decreases insulin resistance.

    PubMed

    Henstridge, Darren C; Bruce, Clinton R; Drew, Brian G; Tory, Kálmán; Kolonics, Attila; Estevez, Emma; Chung, Jason; Watson, Nadine; Gardner, Timothy; Lee-Young, Robert S; Connor, Timothy; Watt, Matthew J; Carpenter, Kevin; Hargreaves, Mark; McGee, Sean L; Hevener, Andrea L; Febbraio, Mark A

    2014-06-01

    Induction of heat shock protein (HSP)72 protects against obesity-induced insulin resistance, but the underlying mechanisms are unknown. Here, we show that HSP72 plays a pivotal role in increasing skeletal muscle mitochondrial number and oxidative metabolism. Mice overexpressing HSP72 in skeletal muscle (HSP72Tg) and control wild-type (WT) mice were fed either a chow or high-fat diet (HFD). Despite a similar energy intake when HSP72Tg mice were compared with WT mice, the HFD increased body weight, intramuscular lipid accumulation (triacylglycerol and diacylglycerol but not ceramide), and severe glucose intolerance in WT mice alone. Whole-body VO2, fatty acid oxidation, and endurance running capacity were markedly increased in HSP72Tg mice. Moreover, HSP72Tg mice exhibited an increase in mitochondrial number. In addition, the HSP72 coinducer BGP-15, currently in human clinical trials for type 2 diabetes, also increased mitochondrial number and insulin sensitivity in a rat model of type 2 diabetes. Together, these data identify a novel role for activation of HSP72 in skeletal muscle. Thus, the increased oxidative metabolism associated with activation of HSP72 has potential clinical implications not only for type 2 diabetes but also for other disorders where mitochondrial function is compromised.

  10. Activating HSP72 in Rodent Skeletal Muscle Increases Mitochondrial Number and Oxidative Capacity and Decreases Insulin Resistance

    PubMed Central

    Henstridge, Darren C.; Bruce, Clinton R.; Drew, Brian G.; Tory, Kálmán; Kolonics, Attila; Estevez, Emma; Chung, Jason; Watson, Nadine; Gardner, Timothy; Lee-Young, Robert S.; Connor, Timothy; Watt, Matthew J.; Carpenter, Kevin; Hargreaves, Mark; McGee, Sean L.; Hevener, Andrea L.; Febbraio, Mark A.

    2014-01-01

    Induction of heat shock protein (HSP)72 protects against obesity-induced insulin resistance, but the underlying mechanisms are unknown. Here, we show that HSP72 plays a pivotal role in increasing skeletal muscle mitochondrial number and oxidative metabolism. Mice overexpressing HSP72 in skeletal muscle (HSP72Tg) and control wild-type (WT) mice were fed either a chow or high-fat diet (HFD). Despite a similar energy intake when HSP72Tg mice were compared with WT mice, the HFD increased body weight, intramuscular lipid accumulation (triacylglycerol and diacylglycerol but not ceramide), and severe glucose intolerance in WT mice alone. Whole-body VO2, fatty acid oxidation, and endurance running capacity were markedly increased in HSP72Tg mice. Moreover, HSP72Tg mice exhibited an increase in mitochondrial number. In addition, the HSP72 coinducer BGP-15, currently in human clinical trials for type 2 diabetes, also increased mitochondrial number and insulin sensitivity in a rat model of type 2 diabetes. Together, these data identify a novel role for activation of HSP72 in skeletal muscle. Thus, the increased oxidative metabolism associated with activation of HSP72 has potential clinical implications not only for type 2 diabetes but also for other disorders where mitochondrial function is compromised. PMID:24430435

  11. Endoplasmic Reticulum Stress Regulates Adipocyte Resistin Expression

    PubMed Central

    Lefterova, Martina I.; Mullican, Shannon E.; Tomaru, Takuya; Qatanani, Mohammed; Schupp, Michael; Lazar, Mitchell A.

    2009-01-01

    OBJECTIVE Resistin is a secreted polypeptide that impairs glucose metabolism and, in rodents, is derived exclusively from adipocytes. In murine obesity, resistin circulates at elevated levels but its gene expression in adipose tissue is paradoxically reduced. The mechanism behind the downregulation of resistin mRNA is poorly understood. We investigated whether endoplasmic reticulum (ER) stress, which is characteristic of obese adipose tissue, regulates resistin expression in cultured mouse adipocytes. RESEARCH DESIGN AND METHODS The effects of endoplasmic stress inducers on resistin mRNA and secreted protein levels were examined in differentiated 3T3-L1 adipocytes, focusing on the expression and genomic binding of transcriptional regulators of resistin. The association between downregulated resistin mRNA and induction of ER stress was also investigated in the adipose tissue of mice fed a high-fat diet. RESULTS ER stress reduced resistin mRNA in 3T3-L1 adipocytes in a time- and dose-dependent manner. The effects of ER stress were transcriptional because of downregulation of CAAT/enhancer binding protein-α and peroxisome proliferator–activated receptor-γ transcriptional activators and upregulation of the transcriptional repressor CAAT/enhancer binding protein homologous protein-10 (CHOP10). Resistin protein was also substantially downregulated, showing a close correspondence with mRNA levels in 3T3-L1 adipocytes as well as in the fat pads of obese mice. CONCLUSIONS ER stress is a potent regulator of resistin, suggesting that ER stress may underlie the local downregulation of resistin mRNA and protein in fat in murine obesity. The paradoxical increase in plasma may be because of various systemic abnormalities associated with obesity and insulin resistance. PMID:19491212

  12. Activation of peroxisome proliferator-activated receptor-{alpha} enhances fatty acid oxidation in human adipocytes

    SciTech Connect

    Lee, Joo-Young; Hashizaki, Hikari; Goto, Tsuyoshi; Sakamoto, Tomoya; Takahashi, Nobuyuki; Kawada, Teruo

    2011-04-22

    Highlights: {yields} PPAR{alpha} activation increased mRNA expression levels of adipocyte differentiation marker genes and GPDH activity in human adipocytes. {yields} PPAR{alpha} activation also increased insulin-dependent glucose uptake in human adipocytes. {yields} PPAR{alpha} activation did not affect lipid accumulation in human adipocytes. {yields} PPAR{alpha} activation increased fatty acid oxidation through induction of fatty acid oxidation-related genes in human adipocytes. -- Abstract: Peroxisome proliferator-activated receptor-{alpha} (PPAR{alpha}) is a key regulator for maintaining whole-body energy balance. However, the physiological functions of PPAR{alpha} in adipocytes have been unclarified. We examined the functions of PPAR{alpha} using human multipotent adipose tissue-derived stem cells as a human adipocyte model. Activation of PPAR{alpha} by GW7647, a potent PPAR{alpha} agonist, increased the mRNA expression levels of adipocyte differentiation marker genes such as PPAR{gamma}, adipocyte-specific fatty acid-binding protein, and lipoprotein lipase and increased both GPDH activity and insulin-dependent glucose uptake level. The findings indicate that PPAR{alpha} activation stimulates adipocyte differentiation. However, lipid accumulation was not changed, which is usually observed when PPAR{gamma} is activated. On the other hand, PPAR{alpha} activation by GW7647 treatment induced the mRNA expression of fatty acid oxidation-related genes such as CPT-1B and AOX in a PPAR{alpha}-dependent manner. Moreover, PPAR{alpha} activation increased the production of CO{sub 2} and acid soluble metabolites, which are products of fatty acid oxidation, and increased oxygen consumption rate in human adipocytes. The data indicate that activation of PPAR{alpha} stimulates both adipocyte differentiation and fatty acid oxidation in human adipocytes, suggesting that PPAR{alpha} agonists could improve insulin resistance without lipid accumulation in adipocytes. The expected

  13. Coordinate regulation of glucose transporter function, number, and gene expression by insulin and sulfonylureas in L6 rat skeletal muscle cells.

    PubMed Central

    Wang, P H; Moller, D; Flier, J S; Nayak, R C; Smith, R J

    1989-01-01

    The extrapancreatic actions of sulfonylureas on the glucose transport system were studied in the L6 line of cultured rat skeletal muscle cells. Insulin (10(-7) M) increased 2-deoxyglucose uptake in differentiated L6 myotubes by 30-40% after 8 h of incubation. The sulfonylurea tolazamide (0.6 mg/ml, 22 h) had no effect on glucose uptake in the absence of insulin, but increased insulin-stimulated 2-deoxyglucose uptake twofold. The total cellular content of glucose transporters was assessed with a monoclonal anti-transporter antibody by a solid-phase ELISA method. Insulin (8 h) increased the quantity of glucose transporters, with a maximal twofold increase at 10(-7) M and a dose-response curve similar to that for insulin stimulation of glucose uptake. In spite of its lack of effect on glucose uptake, tolazamide alone (0.6 mg/ml) increased the cellular content of transporters by 70%. The effects of insulin and tolazamide on transporter gene expression were studied with probes derived from Hep G2 glucose transporter cDNA. Insulin increased the transporter mRNA level 1.7-fold, tolazamide increased it 1.5-fold, and the combination of insulin and tolazamide increased transporter mRNA 3-fold. It is concluded that sulfonylureas, together with insulin, enhance glucose uptake in L6 skeletal muscle cells by increasing the number of functioning glucose transport molecules. The long-term regulation of the glucose transport system in skeletal muscle by insulin and sulfonylureas in vivo may involve similar changes in transporter function, number, and gene expression. Images PMID:2661591

  14. 3T3 cells in adipocytic conversion.

    PubMed

    O'Shea Alvarez, M S

    1991-01-01

    3T3 are murine cells of an established heteroploid cellular line. Some clones of this cellular line, when cultured under adequate conditions differentiate into adipocytes. During the process of differentiation, the cells undergo a change from the elongated fibroblastic shape to a round or oval form and accumulate small drops of lipids within their cytoplasma. These lipid drops fuse into one large drop which displaces the nucleus towards the periphery, giving the cell the aspect of a mature adipocyte of white adipose tissue. The cells not only change their morphology, but they also present important biochemical changes. They show a simultaneous increase in triglyceride synthesis and activity of lipogenic enzymes. There is also an increase in the response of the activity of various hormones and the de novo synthesis of the receptors to such hormones, as insulin and ACTH. During the process of differentiation important changes occur in the synthesis of various proteins, such as actin, tubulin, and other proteins which also make up the cellular cytoskeleton, forming part of the lipid transportation within the adipose cell. The adipocytic differentiation of 3T3 cells depends on adipogenic serum factors used in the supplementary culture medium. These adipogenic factors seem to play an important role in the development of adipose tissue. There are hormones, chemical agents and serum factors which modulate adipocytic differentiation. The clone must be susceptible to adipocytic differentiation, it must reach a quiescent state and find itself in adipogenic conditions for the 3T3 cells to differentiate into adipocytes. It must also carry out an DNA synthesis which is an expression of the new phenotype. The differentiation of 3T3 cells in terminal. The fact that these cells present an adipocytic conversion under physiologic conditions and with adipogenic hormones which exist in the whole animal has been demonstrated. All of these characteristics show that the 3T3 cells may be

  15. An siRNA-based method for efficient silencing of gene expression in mature brown adipocytes

    PubMed Central

    Isidor, Marie S.; Winther, Sally; Basse, Astrid L.; Petersen, M. Christine H.; Cannon, Barbara; Nedergaard, Jan; Hansen, Jacob B.

    2016-01-01

    ABSTRACT Brown adipose tissue is a promising therapeutic target for opposing obesity, glucose intolerance and insulin resistance. The ability to modulate gene expression in mature brown adipocytes is important to understand brown adipocyte function and delineate novel regulatory mechanisms of non-shivering thermogenesis. The aim of this study was to optimize a lipofection-based small interfering RNA (siRNA) transfection protocol for efficient silencing of gene expression in mature brown adipocytes. We determined that a critical parameter was to deliver the siRNA to mature adipocytes by reverse transfection, i.e. transfection of non-adherent cells. Using this protocol, we effectively knocked down both high- and low-abundance transcripts in a model of mature brown adipocytes (WT-1) as well as in primary mature mouse brown adipocytes. A functional consequence of the knockdown was confirmed by an attenuated increase in uncoupled respiration (thermogenesis) in response to β-adrenergic stimulation of mature WT-1 brown adipocytes transfected with uncoupling protein 1 siRNA. Efficient gene silencing was also obtained in various mouse and human white adipocyte models (3T3-L1, primary mouse white adipocytes, hMADS) with the ability to undergo “browning.” In summary, we report an easy and versatile reverse siRNA transfection protocol to achieve specific silencing of gene expression in various models of mature brown and browning-competent white adipocytes, including primary cells. PMID:27386153

  16. Nutritional and hormonal control of lipolysis in isolated gilthead seabream (Sparus aurata) adipocytes.

    PubMed

    Albalat, A; Gómez-Requeni, P; Rojas, P; Médale, F; Kaushik, S; Vianen, G J; Van den Thillart, G; Gutiérrez, J; Pérez-Sánchez, J; Navarro, I

    2005-07-01

    We examined the effects of diet composition and fasting on lipolysis of freshly isolated adipocytes from gilthead seabream (Sparus aurata). We also analyzed the effects of insulin, glucagon, and growth hormone (GH) in adipocytes isolated from fish fed with different diets. Basal lipolysis, measured as glycerol release, increased proportionally with cell concentration and time of incubation, which validates the suitability of these cell preparations for the study of hormonal regulation of this metabolic process. Gilthead seabream were fed two different diets, FM (100% of fish meal) and PP (100% of plant protein supplied by plant sources) for 6 wk. After this period, each diet group was divided into two groups: fed and fasted (for 11 days). Lipolysis was significantly higher in adipocytes from PP-fed fish than in adipocytes from FM-fed fish. Fasting provoked a significant increase in the lipolytic rate, about threefold in isolated adipocytes regardless of nutritional history. Hormone effects were similar in the different groups: glucagon increased the lipolytic rate, whereas insulin had almost no effect. GH was clearly lipolytic, although the relative increase in glycerol over control was lower in isolated adipocytes from fasted fish compared with fed fish. Together, we demonstrate for the first time that lipolysis, measured in isolated seabream adipocytes, is affected by the nutritional state of the fish. Furthermore, our data suggest that glucagon and especially GH play a major role in the control of adipocyte lipolysis.

  17. Isolation and Culture of Pig Spermatogonial Stem Cells and Their in Vitro Differentiation into Neuron-Like Cells and Adipocytes.

    PubMed

    Wang, Xiaoyan; Chen, Tingfeng; Zhang, Yani; Li, Bichun; Xu, Qi; Song, Chengyi

    2015-11-04

    Spermatogonial stem cells (SSCs) renew themselves throughout the life of an organism and also differentiate into sperm in the adult. They are multipopent and therefore, can be induced to differentiate into many cells types in vitro. SSCs from pigs, considered an ideal animal model, are used in studies of male infertility, regenerative medicine, and preparation of transgenic animals. Here, we report on a culture system for porcine SSCs and the differentiation of these cells into neuron-like cells and adipocytes. SSCs and Sertoli cells were isolated from neonatal piglet testis by differential adhesion and SSCs were cultured on a feeder layer of Sertoli cells. Third-generation SSCs were induced to differentiate into neuron-like cells by addition of retinoic acid, β-mercaptoethanol, and 3-isobutyl-1-methylxanthine (IBMX) to the induction media and into adipocytes by the addition of hexadecadrol, insulin, and IBMX to the induction media. The differentiated cells were characterized by biochemical staining, qRT-PCR, and immunocytochemistry. The cells were positive for SSC markers, including alkaline phosphatase and SSC-specific genes, consistent with the cells being undifferentiated. The isolated SSCs survived on the Sertoli cells for 15 generations. Karyotyping confirmed that the chromosomal number of the SSCs were normal for pig (2n = 38, n = 19). Pig SSCs were successfully induced into neuron-like cells eight days after induction and into adipocytes 22 days after induction as determined by biochemical and immunocytochemical staining. qPCR results also support this conclusion. The nervous tissue markers genes, Nestin and β-tubulin, were expressed in the neuron-like cells and the adipocyte marker genes, PPARγ and C/EBPα, were expressed in the adipocytes.

  18. Low-Dose Bisphenol-A Impairs Adipogenesis and Generates Dysfunctional 3T3-L1 Adipocytes.

    PubMed

    Ariemma, Fabiana; D'Esposito, Vittoria; Liguoro, Domenico; Oriente, Francesco; Cabaro, Serena; Liotti, Antonietta; Cimmino, Ilaria; Longo, Michele; Beguinot, Francesco; Formisano, Pietro; Valentino, Rossella

    2016-01-01

    Environmental endocrine disruptors (EDCs), including bisphenol-A (BPA), have been recently involved in obesity and diabetes by dysregulating adipose tissue function. Our aim was to examine whether prolonged exposure to low doses of BPA could affect adipogenesis and adipocyte metabolic functions. Therefore, 3T3-L1 pre-adipocytes were cultured for three weeks with BPA 1 nM to mimic human environmental exposure. We evaluated BPA effect on cell proliferation, differentiation, gene expression and adipocyte metabolic function. BPA significantly increased pre-adipocyte proliferation (p<0.01). In 3T3-L1 adipocytes differentiated in the presence of BPA, the expression of Peroxisome proliferator-activated receptor gamma (PPARγ), Fatty Acid Binding Protein 4/Adipocyte Protein 2 (FABP4/AP2) and CCAAT/enhancer binding protein (C/EBPα) was increased by 3.5, 1.5 and 3 folds, respectively. Mature adipocytes also showed a significant increase in lipid accumulation (p<0.05) and alterations of insulin action, with significant reduction in insulin-stimulated glucose utilization (p<0.001). Moreover, in mature adipocytes, mRNA levels of Leptin, interleukin-6 (IL6) and interferon-γ (IFNγ) were significantly increased (p<0.05). In conclusion, BPA prolonged exposure at low doses, consistent with those found in the environment, may affect adipocyte differentiation program, enhancing pre-adipocyte proliferation and anticipating the expression of the master genes involved in lipid/glucose metabolism. The resulting adipocytes are hypertrophic, with impaired insulin signaling, reduced glucose utilization and increased pro-inflammatory cytokine expression. Thus, these data supported the hypothesis that BPA exposure, during critical stages of adipose tissue development, may cause adipocyte metabolic dysfunction and inflammation, thereby increasing the risk of developing obesity-related diseases.

  19. Low-Dose Bisphenol-A Impairs Adipogenesis and Generates Dysfunctional 3T3-L1 Adipocytes

    PubMed Central

    Ariemma, Fabiana; D’Esposito, Vittoria; Liguoro, Domenico; Oriente, Francesco; Cabaro, Serena; Liotti, Antonietta; Cimmino, Ilaria; Longo, Michele; Beguinot, Francesco; Formisano, Pietro; Valentino, Rossella

    2016-01-01

    Environmental endocrine disruptors (EDCs), including bisphenol-A (BPA), have been recently involved in obesity and diabetes by dysregulating adipose tissue function. Our aim was to examine whether prolonged exposure to low doses of BPA could affect adipogenesis and adipocyte metabolic functions. Therefore, 3T3-L1 pre-adipocytes were cultured for three weeks with BPA 1nM to mimic human environmental exposure. We evaluated BPA effect on cell proliferation, differentiation, gene expression and adipocyte metabolic function. BPA significantly increased pre-adipocyte proliferation (p<0.01). In 3T3-L1 adipocytes differentiated in the presence of BPA, the expression of Peroxisome proliferator-activated receptor gamma (PPARγ), Fatty Acid Binding Protein 4/Adipocyte Protein 2 (FABP4/AP2) and CCAAT/enhancer binding protein (C/EBPα) was increased by 3.5, 1.5 and 3 folds, respectively. Mature adipocytes also showed a significant increase in lipid accumulation (p<0.05) and alterations of insulin action, with significant reduction in insulin-stimulated glucose utilization (p<0.001). Moreover, in mature adipocytes, mRNA levels of Leptin, interleukin-6 (IL6) and interferon-γ (IFNγ) were significantly increased (p<0.05). In conclusion, BPA prolonged exposure at low doses, consistent with those found in the environment, may affect adipocyte differentiation program, enhancing pre-adipocyte proliferation and anticipating the expression of the master genes involved in lipid/glucose metabolism. The resulting adipocytes are hypertrophic, with impaired insulin signaling, reduced glucose utilization and increased pro-inflammatory cytokine expression. Thus, these data supported the hypothesis that BPA exposure, during critical stages of adipose tissue development, may cause adipocyte metabolic dysfunction and inflammation, thereby increasing the risk of developing obesity-related diseases. PMID:26942597

  20. Alteration of local adipose tissue trace element homeostasis as a possible mechanism of obesity-related insulin resistance.

    PubMed

    Tinkov, Alexey A; Sinitskii, Anton I; Popova, Elizaveta V; Nemereshina, Olga N; Gatiatulina, Evgenia R; Skalnaya, Margarita G; Skalny, Anatoly V; Nikonorov, Alexandr A

    2015-09-01

    The mechanisms of association between obesity and the related metabolic disturbances in general and insulin resistance in particular are extensively studied. Taking into account a key role of adipose tissue insulin resistance in the development of systemic obesity-related insulin resistance, the estimation of mechanisms linking increased adiposity and impaired insulin signaling in adipocytes will allow to develop novel prophylactic and therapeutic approaches to treatment of these states. A number of trace elements like chromium, zinc, and vanadium have been shown to take part in insulin signaling via various mechanisms. Taking into account a key role of adipocyte in systemic carbohydrate homeostasis it can be asked if trace element homeostasis in adipose tissue may influence regulatory mechanisms of glucose metabolism. We hypothesize that caloric excess through currently unknown mechanisms results in decreased chromium, vanadium, and zinc content in adipocytes. Decreased content of trace elements in the adipose tissue causes impairment of intra-adipocyte insulin signaling subsequently leading to adipose tissue insulin resistance. The latter significantly contributes to systemic insulin resistance and further metabolic disruption in obesity. It is also possible that decreased adipose tissue trace element content is associated with dysregulation of insulin-sensitizing and proinflammatory adipokines also leading to insulin resistance. We hypothesize that insulin resistance and adipokine dysbalance increase the severity of obesity subsequently aggravating alteration of adipose tissue trace element balance. Single indications of high relative adipose tissue trace element content, decreased Cr, V, and Zn content in obese adipose tissue, and tight association between fat tissue chromium, vanadium, and zinc levels and metabolic parameters in obesity may be useful for hypothesis validation. If our hypothesis will be confirmed by later studies, adipose tissue chromium

  1. Adipocytes as immune regulatory cells

    PubMed Central

    Vielma, Silvana A.; Klein, Richard L.; Levingston, Corinne A.; Young, M. Rita I.

    2013-01-01

    Obesity is a chronic inflammatory state and adipocytes are capable of contributing to this inflammation by their production of inflammatory mediators. The present study used fibroblast-derived adipocytes and normal spleen cells as a model to determine if adipocytes can also serve as immune regulatory cells by modulating the functions of conventional immune cells. Media conditioned by the adipocytes stimulated release of the Th1-type cytokines IL-2, IFN-γ and GM-CSF from cultures of normal spleen cells. The adipocytes also stimulated spleen cell release of inhibitory cytokines, although to varying degrees. This included IL-10, IL-13 and, to a lesser extent, IL-4. Spleen cell production of the inflammatory cytokines IL-6, TNF-α and IL-9 was stimulated by adipocytes, although production of the Th17-derived cytokine, IL-17, was not stimulated. The adipocyte-conditioned medium did not stimulate production of predominantly monocytes-derived chemokines CXCL9, CCL2, CCL3, CCL4, but stimulated production of the predominantly T-cell-derived chemokine CCL5. In all cases where cytokine/chemokine production from spleen cells was stimulated by adipocytes, it was to a far greater level than was produced by the adipocytes themselves. Studies initiated to determine the identity of the adipocyte-derived mediators showed that the spleen cell modulation could not be attributed to solely adiponectin or leptin. Studies to determine the source of some of the cytokines whose production was stimulated by adipocytes showed that expression of the inflammatory cytokine IL-6 was not increased in either CD4+ or CD8+ T-cell. When the splenic T-cells were examined for IFN-γ, the adipocyte stimulation of IFN-γ was within CD8+ T-cells, not CD4+ T-cells. These studies show that adipocytes may be able to serve as immune regulatory cells to stimulate conventional immune cells to release a spectrum of immune mediators. PMID:23587489

  2. Programming human pluripotent stem cells into white and brown adipocytes

    PubMed Central

    Ahfeldt, Tim; Schinzel, Robert T.; Lee, Youn-Kyoung; Hendrickson, David; Kaplan, Adam; Lum, David H.; Camahort, Raymond; Xia, Fang; Shay, Jennifer; Rhee, Eugene P.; Clish, Clary B.; Deo, Rahul C.; Shen, Tony; Lau, Frank H.; Cowley, Alicia; Mowrer, Greg; Al-Siddiqi, Heba; Nahrendorf, Matthias; Musunuru, Kiran; Gerszten, Robert E.; Rinn, John L.; Cowan, Chad A.

    2012-01-01

    The utility of human pluripotent stem cells is dependent on efficient differentiation protocols that convert these cells into relevant adult cell types. Here we report the robust and efficient differentiation of human pluripotent stem cells into white or brown adipocytes. We found that inducible expression of PPARG2 alone or combined with CEBPB and/or PRDM16 in mesenchymal progenitor cells derived from pluripotent stem cells programmed their development towards a white or brown adipocyte cell fate with efficiencies of 85%–90%. These adipocytes retained their identity independent of transgene expression, could be maintained in culture for several weeks, expressed mature markers and had mature functional properties such as lipid catabolism and insulin-responsiveness. When transplanted into mice, the programmed cells gave rise to ectopic fat pads with the morphological and functional characteristics of white or brown adipose tissue. These results indicate that the cells could be used to faithfully model human disease. PMID:22246346

  3. Long-Term Fructose Intake Increases Adipogenic Potential: Evidence of Direct Effects of Fructose on Adipocyte Precursor Cells.

    PubMed

    Zubiría, María Guillermina; Alzamendi, Ana; Moreno, Griselda; Rey, María Amanda; Spinedi, Eduardo; Giovambattista, Andrés

    2016-04-02

    We have previously addressed that fructose rich diet (FRD) intake for three weeks increases the adipogenic potential of stromal vascular fraction cells from the retroperitoneal adipose tissue (RPAT). We have now evaluated the effect of prolonged FRD intake (eight weeks) on metabolic parameters, number of adipocyte precursor cells (APCs) and in vitro adipogenic potential from control (CTR) and FRD adult male rats. Additionally, we have examined the direct fructose effects on the adipogenic capacity of normal APCs. FRD fed rats had increased plasma levels of insulin, triglyceride and leptin, and RPAT mass and adipocyte size. FACS studies showed higher APCs number and adipogenic potential in FRD RPAT pads; data is supported by high mRNA levels of competency markers: PPARγ2 and Zfp423. Complementary in vitro experiments indicate that fructose-exposed normal APCs displayed an overall increased adipogenic capacity. We conclude that the RPAT mass expansion observed in eight week-FRD fed rats depends on combined accelerated adipogenesis and adipocyte hypertrophy, partially due to a direct effect of fructose on APCs.

  4. Long-Term Fructose Intake Increases Adipogenic Potential: Evidence of Direct Effects of Fructose on Adipocyte Precursor Cells

    PubMed Central

    Zubiría, María Guillermina; Alzamendi, Ana; Moreno, Griselda; Rey, María Amanda; Spinedi, Eduardo; Giovambattista, Andrés

    2016-01-01

    We have previously addressed that fructose rich diet (FRD) intake for three weeks increases the adipogenic potential of stromal vascular fraction cells from the retroperitoneal adipose tissue (RPAT). We have now evaluated the effect of prolonged FRD intake (eight weeks) on metabolic parameters, number of adipocyte precursor cells (APCs) and in vitro adipogenic potential from control (CTR) and FRD adult male rats. Additionally, we have examined the direct fructose effects on the adipogenic capacity of normal APCs. FRD fed rats had increased plasma levels of insulin, triglyceride and leptin, and RPAT mass and adipocyte size. FACS studies showed higher APCs number and adipogenic potential in FRD RPAT pads; data is supported by high mRNA levels of competency markers: PPARγ2 and Zfp423. Complementary in vitro experiments indicate that fructose-exposed normal APCs displayed an overall increased adipogenic capacity. We conclude that the RPAT mass expansion observed in eight week-FRD fed rats depends on combined accelerated adipogenesis and adipocyte hypertrophy, partially due to a direct effect of fructose on APCs. PMID:27049396

  5. Adipose tissue macrophages in insulin-resistant subjects are associated with collagen VI and fibrosis and demonstrate alternative activation.

    PubMed

    Spencer, Michael; Yao-Borengasser, Aiwei; Unal, Resat; Rasouli, Neda; Gurley, Catherine M; Zhu, Beibei; Peterson, Charlotte A; Kern, Philip A

    2010-12-01

    Adipose tissue macrophages are associated with insulin resistance and are linked to changes in the extracellular matrix. To better characterize adipose macrophages, the extracellular matrix, and adipocyte-macrophage interactions, gene expression from adipose tissue and the stromal vascular fraction was assessed for markers of inflammation and fibrosis, and macrophages from obese and lean subjects were counted and characterized immunohistochemically. Coculture experiments examined the effects of adipocyte-macrophage interaction. Collagen VI gene expression was associated with insulin sensitivity and CD68 (r = -0.56 and 0.60, P < 0.0001) and with other markers of inflammation and fibrosis. Compared with adipose tissue from lean subjects, adipose tissue from obese subjects contained increased areas of fibrosis, which correlated inversely with insulin sensitivity (r = -0.58, P < 0.02) and positively with macrophage number (r = 0.70, P < 0.01). Although macrophages in crownlike structures (CLS) were more abundant in obese adipose tissue, the majority of macrophages were associated with fibrosis and were not organized in CLS. Macrophages in CLS were predominantly M1, but most other macrophages, particularly those in fibrotic areas, were M2 and also expressed CD150, a marker of M2c macrophages. Coculture of THP-1 macrophages with adipocytes promoted the M2 phenotype, with a lower level of IL-1 expression and a higher ratio of IL-10 to IL-12. Transforming growth factor-β (TGF-β) was more abundant in M2 macrophages and was further increased by coculture with adipocytes. Downstream effectors of TGF-β, such as plasminogen activator inhibitor-1, collagen VI, and phosphorylated Smad, were increased in macrophages and adipocytes. Thus adipose tissue of insulin-resistant humans demonstrated increased fibrosis, M2 macrophage abundance, and TGF-β activity.

  6. Brown adipogenic potential of brown adipocytes and peri-renal adipocytes from human embryo

    PubMed Central

    Wu, Nan-Nan; Zhang, Chuan-Hai; Lee, Hyuek-Jong; Ma, Yan; Wang, Xin; Ma, Xiao-Juan; Ma, Wei; Zhao, Dong; Feng, Ying-Mei

    2016-01-01

    Both brown adipocytes (BAC) and beige cells hold therapeutic potential for the treatment of metabolic disorders. Unfortunately, the amount and activity of these cells are limited in adults. Although BAC marker expression has been shown in peri-renal adipose tissues in children and adults, functional assessment is lacking. Furthermore, it is entirely unknown whether adipose progenitors are present in human embryo and able to give rise to BAC in situ during evolution. Therefore, adipose tissues in the interscapular and peri-renal regions were dissected from human embryo and subcutaneous white adipose tissues (sWAT) were obtained from an adult. After subjected to differentiation in vitro, adipocyte progenitors were detected present in all these adipose tissues. When stimulated for adipogenesis, differentiated adipocytes in the intercapular and peri-renal regions showed similar features: (1) induced BAC and beige cell marker expression including UCP1 and PRDM16 and comparable mitochondrion copy number; (2) similar gene expression patterns by RNA-Seq analysis; and (3) similar maximal oxygen consumption rates examined by respirometry. Nevertheless, stimulation of adipocyte progenitors in sWAT induces neither BAC and beige cell marker expression nor any change of oxygen consumption. In conclusion, peri-renal adipocyte progenitors in human embryo hold browning potential for BAC production. PMID:27982067

  7. Adeno-Associated Viral Vectors Transduce Mature Human Adipocytes in Three-Dimensional Slice Cultures.

    PubMed

    Kallendrusch, Sonja; Schopow, Nikolas; Stadler, Sonja C; Büning, Hildegard; Hacker, Ulrich T

    2016-10-01

    Adipose tissue plays a pivotal role, both in the regulation of energy homeostasis and as an endocrine organ. Consequently, adipose tissue dysfunction is closely related to insulin resistance, morbid obesity, and metabolic syndrome. To study molecular mechanisms and to develop novel therapeutic strategies, techniques are required to genetically modify mature adipocytes. Here, we report on adeno-associated viral (AAV) vectors as a versatile tool to transduce human mature adipocytes in organotypic three-dimensional tissue cultures.

  8. Influence of amount and type of dietary fat on deposition, adipocyte count and iodine number of abdominal fat in broiler chickens.

    PubMed

    Wongsuthavas, S; Terapuntuwat, S; Wongsrikeaw, W; Katawatin, S; Yuangklang, C; Beynen, A C

    2008-02-01

    This study described the relation between the type and amount of dietary fat on the deposition of abdominal fat by broiler chickens. It was hypothesized that at higher fat intakes, the well-known lowering effect of polyunsaturated fatty acids on the deposition of abdominal fat would be diminished. Experimental diets were formulated to contain three levels of added fat (3%, 6% and 9%). Each level had different proportions of the saturated fatty acids (SFA) and unsaturated fatty acids (UFA) by installing the ratios of 1:1, 1:2, 1:3, 1:4 and 1:5 with the use of tallow and soybean oil. Arbor Acres chicks, aged 7 days, were fed one of the 15 experimental diets until they were aged 42 days. Feed and water were provided ad libitum. There was no systematic effect of the dietary fat type and the amount on the weight gain and the feed intake. The lowest SFA:UFA ratio of 1:5 produced the lowest feed conversion rates, irrespective of the amount of the fat in the diet. The abdominal fat deposition was similar in the birds fed on diets containing either 3% or 6% added fat, but deposition was lower than in those fed 9% fat. A decrease in the SFA:UFA ratio of the diet was associated with a dose-dependent decrease in abdominal fat, irrespective of the amount of fat in the diet. This observation leads to the rejection of the hypothesis stated above. A decrease in the dietary SFA:UFA from 1:1 to 1:4 caused a decrease in the number of the fat cells per surface unit of breast meat. It is concluded that an increased intake of soybean oil at the expense of tallow reduced the abdominal fat deposition and the number of fat cells in the breast meat of broiler chickens.

  9. Adipocyte-specific loss of PPARγ attenuates cardiac hypertrophy

    PubMed Central

    Fang, Xi; Stroud, Matthew J.; Ouyang, Kunfu; Fang, Li; Zhang, Jianlin; Dalton, Nancy D.; Gu, Yusu; Wu, Tongbin; Peterson, Kirk L.; Huang, Hsien-Da; Wang, Nanping

    2016-01-01

    Adipose tissue is a key endocrine organ that governs systemic homeostasis. PPARγ is a master regulator of adipose tissue signaling that plays an essential role in insulin sensitivity, making it an important therapeutic target. The selective PPARγ agonist rosiglitazone (RSG) has been used to treat diabetes. However, adverse cardiovascular effects have seriously hindered its clinical application. Experimental models have revealed that PPARγ activation increases cardiac hypertrophy. RSG stimulates cardiac hypertrophy and oxidative stress in cardiomyocyte-specific PPARγ knockout mice, implying that RSG might stimulate cardiac hypertrophy independently of cardiomyocyte PPARγ. However, candidate cell types responsible for RSG-induced cardiomyocyte hypertrophy remain unexplored. Utilizing cocultures of adipocytes and cardiomyocytes, we found that stimulation of PPARγ signaling in adipocytes increased miR-200a expression and secretion. Delivery of miR-200a in adipocyte-derived exosomes to cardiomyocytes resulted in decreased TSC1 and subsequent mTOR activation, leading to cardiomyocyte hypertrophy. Treatment with an antagomir to miR-200a blunted this hypertrophic response in cardiomyocytes. In vivo, specific ablation of PPARγ in adipocytes was sufficient to blunt hypertrophy induced by RSG treatment. By delineating mechanisms by which RSG elicits cardiac hypertrophy, we have identified pathways that mediate the crosstalk between adipocytes and cardiomyocytes to regulate cardiac remodeling. PMID:27734035

  10. Spontaneously beating cardiomyocytes derived from white mature adipocytes

    PubMed Central

    Jumabay, Medet; Zhang, Rui; Yao, Yucheng; Goldhaber, Joshua I.; Boström, Kristina I.

    2010-01-01

    Aims Adipose stromal cells and dissociated brown adipose tissue have been shown to generate cardiomyocyte-like cells. However, it is not clear whether white mature adipocytes have the same potential, even though a close relationship has been found between adipocytes and vascular endothelial cells, another cardiovascular cell type. The objective of this study was to examine if white adipocytes would be able to supply cardiomyocytes. Methods and results We prepared a highly purified population of lipid-filled adipocytes from mice, 6–7 weeks of age. When allowed to lose lipids, the adipocytes assumed a fibroblast-like morphology, so-called dedifferentiated fat (DFAT) cells. Subsequently, 10–15% of the DFAT cells spontaneously differentiated into cardiomyocyte-like cells, in which the cardiomyocyte phenotype was identified by morphological observations, expression of cardiomyocyte-specific markers, and immunocytochemical staining. In addition, electrophysiological studies revealed pacemaker activity in these cells, and functional studies showed that a β-adrenergic agonist stimulated the beating rate, whereas a β-antagonist reduced it. In vitro treatment of newly isolated adipocytes or DFAT cells with inhibitors of bone morphogenetic proteins (BMP) and Wnt signalling promoted the development of the cardiomyocyte phenotype as determined by the number or beating colonies of cardiomyocyte-like cells and expression of troponin I, a cardiomyocyte-specific marker. Inhibition of BMP was most effective in promoting the cardiomyocyte phenotype in adipocytes, whereas Wnt-inhibition was most effective in DFAT cells. Conclusion White mature adipocytes can differentiate into cardiomyocyte-like cells, suggesting a link between adipocyte and cardiomyocyte differentiation. PMID:19643806

  11. Developmental aspects of the rat brain insulin receptor: loss of sialic acid and fluctuation in number characterize fetal development

    SciTech Connect

    Brennan, W.A. Jr.

    1988-06-01

    In this study, I have investigated the structure of the rat brain insulin receptor during fetal development. There is a progressive decrease in the apparent molecular size of the brain alpha-subunit during development: 130K on day 16 of gestation, 126K at birth, and 120K in the adult. Glycosylation was investigated as a possible reason for the observed differences in the alpha-subunit molecular size. The results show that the developmental decrease in the brain alpha-subunit apparent molecular size is due to a parallel decrease in sialic acid content. This was further confirmed by measuring the retention of autophosphorylated insulin receptors on wheat germ agglutinin (WGA)-Sepharose. An inverse correlation between developmental age and retention of /sup 32/P-labeled insulin receptors on the lectin column was observed. Insulin binding increases 6-fold between 16 and 20 days of gestation (61 +/- 25 (+/- SE) fmol/mg protein and 364 +/- 42 fmol/mg, respectively). Thereafter, binding in brain membranes decreases to 150 +/- 20 fmol/mg by 2 days after birth, then reaches the adult level of 63 +/- 15 fmol/mg. In addition, the degree of insulin-stimulated autophosphorylation closely parallels the developmental changes in insulin binding. Between 16 and 20 days of fetal life, insulin-stimulated phosphorylation of the beta-subunit increases 6-fold. Thereafter, the extent of phosphorylation decreases rapidly, reaching adult values identical with those in 16-day-old fetal brain. These results suggest that the embryonic brain possesses competent insulin receptors whose expression changes markedly during fetal development. This information should be important in defining the role of insulin in the developing nervous system.

  12. Knockdown of PTRF ameliorates adipocyte differentiation and functionality of human mesenchymal stem cells.

    PubMed

    Perez-Diaz, Sergio; Garcia-Rodriguez, Beatriz; Gonzalez-Irazabal, Yolanda; Valero, Monica; Lagos-Lizan, Javier; Arbones-Mainar, Jose M

    2017-01-01

    Healthy expansion of human adipose tissue requires mesenchymal stem cells (hMSC) able to proliferate and differentiate into mature adipocytes. Hence, characterization of those factors that coordinate hMSC-to-adipocyte transition is of paramount importance to modulate the adipose tissue expansion. It has been previously reported that the adipogenic program of hMSC can be disrupted by upregulating caveolar proteins, and polymerase I and transcript release factor (PTRF) is an integral component of caveolae, highly expressed in adipose tissue. Here, we hypothesized that the role of PTRF in adipocyte functionality might stem from an effect on hMSC. To test this hypothesis, we isolated hMSC from the subcutaneous fat depot. We found an upregulated expression of the PTRF associated with decreased adipogenic potential of hMSC, likely due to the existence of senescent adipocyte precursors. Employing short hairpin RNA-based constructs to stably reduce PTRF, we were able to restore insulin sensitivity and reduced basal lipolysis and leptin levels in human adipocytes with high levels of PTRF. Additionally, we pinpointed the detrimental effect caused by PTRF on the adipose tissue to the existence of senescent adipocyte precursors unable to proliferate and differentiate into adipocytes. This study provides evidence that impaired adipocyte functionality can be corrected, at least partially, by PTRF downregulation and warrants further in vivo research in patients with dysfunctional adipose tissue to prevent metabolic complications.

  13. Phosphoproteomics Identifies CK2 as a Negative Regulator of Beige Adipocyte Thermogenesis and Energy Expenditure.

    PubMed

    Shinoda, Kosaku; Ohyama, Kana; Hasegawa, Yutaka; Chang, Hsin-Yi; Ogura, Mayu; Sato, Ayaka; Hong, Haemin; Hosono, Takashi; Sharp, Louis Z; Scheel, David W; Graham, Mark; Ishihama, Yasushi; Kajimura, Shingo

    2015-12-01

    Catecholamines promote lipolysis both in brown and white adipocytes, whereas the same stimuli preferentially activate thermogenesis in brown adipocytes. Molecular mechanisms for the adipose-selective activation of thermogenesis remain poorly understood. Here, we employed quantitative phosphoproteomics to map global and temporal phosphorylation profiles in brown, beige, and white adipocytes under β3-adrenenoceptor activation and identified kinases responsible for the adipose-selective phosphorylation profiles. We found that casein kinase2 (CK2) activity is preferentially higher in white adipocytes than brown/beige adipocytes. Genetic or pharmacological blockade of CK2 in white adipocytes activates the thermogenic program in response to cAMP stimuli. Such activation is largely through reduced CK2-mediated phosphorylation of class I HDACs. Notably, inhibition of CK2 promotes beige adipocyte biogenesis and leads to an increase in whole-body energy expenditure and ameliorates diet-induced obesity and insulin resistance. These results indicate that CK2 is a plausible target to rewire the β3-adrenenoceptor signaling cascade that promotes thermogenesis in adipocytes.

  14. Paprika Pigments Attenuate Obesity-Induced Inflammation in 3T3-L1 Adipocytes

    PubMed Central

    Maeda, Hayato; Saito, Shuuichi; Nakamura, Nozomi; Maoka, Takashi

    2013-01-01

    Obesity is related to various diseases, such as diabetes, hyperlipidemia, and hypertension. Adipocytokine, which is released from adipocyte cells, affects insulin resistance and blood lipid level disorders. Further, adipocytokine is related to chronic inflammation in obesity condition adipocyte cells. Paprika pigments (PPs) contain large amounts of capsanthin and capsorubin. These carotenoids affect the liver and improve lipid disorders of the blood. However, how these carotenoids affect adipocyte cells remains unknown. Present study examined the effects of PP on adipocytokine secretion, which is related to improvement of metabolic syndrome. In addition, suppressive effects of PP on chronic inflammation in adipocyte cells were analyzed using 3T3-L1 adipocyte cells and macrophage cell coculture experiments. PP promoted 3T3-L1 adipocyte cells differentiation upregulated adiponectin mRNA expression and secretion. Further, coculture of adipocyte and macrophage cells treated with PP showed suppressed interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemotactic protein-1 (MCP-1), and resistin mRNA expression, similarly to treatment with troglitazone, which is a PPARγ ligand medicine. Conclusion. These results suggest that PP ameliorates chronic inflammation in adipocytes caused by obesity. PP adjusts adipocytokine secretion and might, therefore, affect antimetabolic syndrome diseases. PMID:24049664

  15. Gender Differences in Adipocyte Metabolism and Liver Cancer Progression.

    PubMed

    Cheung, Otto K-W; Cheng, Alfred S-L

    2016-01-01

    Liver cancer is the third most common cancer type and the second leading cause of deaths in men. Large population studies have demonstrated remarkable gender disparities in the incidence and the cumulative risk of liver cancer. A number of emerging risk factors regarding metabolic alterations associated with obesity, diabetes and dyslipidemia have been ascribed to the progression of non-alcoholic fatty liver diseases (NAFLD) and ultimately liver cancer. The deregulation of fat metabolism derived from excessive insulin, glucose, and lipid promotes cancer-causing inflammatory signaling and oxidative stress, which eventually triggers the uncontrolled hepatocellular proliferation. This review presents the current standing on the gender differences in body fat compositions and their mechanistic linkage with the development of NAFLD-related liver cancer, with an emphasis on genetic, epigenetic and microRNA control. The potential roles of sex hormones in instructing adipocyte metabolic programs may help unravel the mechanisms underlying gender dimorphism in liver cancer and identify the metabolic targets for disease management.

  16. Gender Differences in Adipocyte Metabolism and Liver Cancer Progression

    PubMed Central

    Cheung, Otto K.-W.; Cheng, Alfred S.-L.

    2016-01-01

    Liver cancer is the third most common cancer type and the second leading cause of deaths in men. Large population studies have demonstrated remarkable gender disparities in the incidence and the cumulative risk of liver cancer. A number of emerging risk factors regarding metabolic alterations associated with obesity, diabetes and dyslipidemia have been ascribed to the progression of non-alcoholic fatty liver diseases (NAFLD) and ultimately liver cancer. The deregulation of fat metabolism derived from excessive insulin, glucose, and lipid promotes cancer-causing inflammatory signaling and oxidative stress, which eventually triggers the uncontrolled hepatocellular proliferation. This review presents the current standing on the gender differences in body fat compositions and their mechanistic linkage with the development of NAFLD-related liver cancer, with an emphasis on genetic, epigenetic and microRNA control. The potential roles of sex hormones in instructing adipocyte metabolic programs may help unravel the mechanisms underlying gender dimorphism in liver cancer and identify the metabolic targets for disease management. PMID:27703473

  17. Conjugated Linoleic Acid Induces Human Adipocyte Delipidation

    PubMed Central

    Brown, J. Mark; Boysen, Maria Sandberg; Chung, Soonkyu; Fabiyi, Olowatoyin; Morrison, Ron F.; Mandrup, Susanne; McIntosh, Michael K.

    2005-01-01

    Dietary conjugated linoleic acid (CLA) reduces body fat in animals and some humans. Here we show that trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, when added to cultures of stromal vascular cells containing newly differentiated human adipocytes, caused a time-dependent decrease in triglyceride content, insulin-stimulated glucose and fatty acid uptake, incorporation into lipid, and oxidation compared with controls. In parallel, gene expression of peroxisome proliferator-activated receptor-γ and many of its downstream targets were diminished by trans-10, cis-12 CLA, whereas leptin gene expression was increased. Prior to changes in gene expression and metabolism, trans-10, cis-12 CLA caused a robust and sustained activation of mitogen-activated protein kinase kinase/extracellular signal-related kinase (MEK/ERK) signaling. Furthermore, the trans-10, cis-12 CLA-mediated activation of MEK/ERK could be attenuated by pretreatment with U0126 and pertussis toxin. In parallel, pretreatment with U0126 blocked the ability of trans-10, cis-12 CLA to alter gene expression and attenuate glucose and fatty acid uptake of the cultures. Intriguingly, the induction by CLA of MEK/ERK signaling was linked to hypersecretion of adipocytokines interleukin-6 and interleukin-8. Collectively, these data demonstrate for the first time that trans-10, cis-12 CLA decreases the triglyceride content of newly differentiated human adipocytes by inducing MEK/ERK signaling through the autocrine/paracrine actions of interleukins-6 and 8. PMID:15067015

  18. DERMAL ADIPOCYTES: FROM IRRELEVANCE TO METABOLIC TARGETS?

    PubMed Central

    Kruglikov, Ilja L.; Scherer, Philipp E.

    2015-01-01

    Dermal white adipose tissue (dWAT) has found little appreciation in the past as a distinct entity from the better recognized subcutaneous white adipose tissue (sWAT). However, recent work has established dWAT as an important contributor to a multitude of processes, including immune response, wound healing and scarring, hair follicle growth and thermoregulation. Unique metabolic contributions are attributed to dWAT as well, at least in part due to thermic insulation properties and its response to cold exposure. Dermal adipocytes can also undergo adipocyte-myofibroblast transition (AMT), a process that is suspected to play an important role in a number of pathophysiological processes within the skin. Here, we discuss emerging concepts regarding dWAT physiology and its significance to a variety of cellular processes. PMID:26643658

  19. Modulation of adipocyte biology by δ(9)-tetrahydrocannabinol.

    PubMed

    Teixeira, Diana; Pestana, Diogo; Faria, Ana; Calhau, Conceição; Azevedo, Isabel; Monteiro, Rosário

    2010-11-01

    It is recognized that the endocannabinoid system (ECS) plays a crucial role in the modulation of food intake and other aspects of energy metabolism. In this study, we aimed to investigate the effects of Δ(9)-tetrahydrocannabinol (THC) on adipocyte biology. 3T3-L1 cells were used to evaluate proliferation by sulforhodamine B (SRB) staining and methyl-(3)H-thymidine incorporation after 48 or 72 h of treatment with THC (1-500 nmol/l). Cells were differentiated in the presence or absence of the cannabinoid, and adipogenesis was determined by measuring lipid accumulation and peroxisome proliferator-activated receptor γ (PPARγ) transcription through reverse transcriptase-PCR (RT-PCR). Lipolysis was quantified under basal conditions or after isoproterenol (IP, 100 nmol/l) or insulin (INS, 100 nmol/l) treatment. Transforming growth factor β (TGFβ), diacylglycerol lipase α, and N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD) transcriptions were determined by RT-PCR in preadipocytes and adipocytes and adiponectin only in adipocytes. THC treatment increased culture protein content and reduced methyl-(3)H-thymidine incorporation. Cells treated with THC underwent adipogenesis shown by the expression of PPARγ and had increased lipid accumulation. Basal and IP-stimulated lipolyses were inhibited by THC and there was no effect on lipolysis of INS-treated adipocytes. The effects on methyl-(3)H-thymidine incorporation and lipolysis seem to be mediated through CB1- and CB2-dependent pathways. THC decreased NAPE-PLD in preadipocytes and increased adiponectin and TGFβ transcription in adipocytes. These results show that the ECS interferes with adipocyte biology and may contribute to adipose tissue (AT) remodeling. Although these observations point toward increased AT deposition, the stimulation of adiponectin production and inhibition of lipolysis may be in favor of improved INS sensitivity under cannabinoid influence.

  20. St. John's Wort Has Metabolically Favorable Effects on Adipocytes In Vivo

    PubMed Central

    Richard, Allison J.; Ribnicky, David M.; Mynatt, Randall; Stephens, Jacqueline M.

    2014-01-01

    In addition to serving as a storage site for reserve energy, adipocytes play a critical role in whole-body insulin sensitivity and glucose metabolism. St. John's Wort (SJW) is a botanical supplement widely used as an over-the-counter treatment of depression and a variety of other conditions associated with anxiety and nerve pain. Previous studies in our laboratory demonstrated that SJW inhibits insulin-stimulated glucose uptake and adipocyte differentiation in cultured murine and mature human adipocytes. To investigate the effects of SJW on adipocyte function in vivo, we utilized C57BL/6J mice. In our studies, mice were administered SJW extract (200 mg/kg) once daily by gavage for two weeks. In contrast to our in vitro studies, mice treated with SJW extract showed increased levels of adiponectin in white adipose tissue in a depot specific manner (P < 0.01). SJW also exerted an insulin-sensitizing effect as indicated by a significant increase in insulin-stimulated Akt serine phosphorylation in epididymal white adipose tissue (P < 0.01). Food intake, body weight, fasting blood glucose, and fasting insulin did not differ between the two groups. These results are important as they indicate that SJW does not promote metabolic dysfunction in adipose tissue in vivo. PMID:25136373

  1. St. John's Wort Has Metabolically Favorable Effects on Adipocytes In Vivo.

    PubMed

    Fuller, Scott; Richard, Allison J; Ribnicky, David M; Beyl, Robbie; Mynatt, Randall; Stephens, Jacqueline M

    2014-01-01

    In addition to serving as a storage site for reserve energy, adipocytes play a critical role in whole-body insulin sensitivity and glucose metabolism. St. John's Wort (SJW) is a botanical supplement widely used as an over-the-counter treatment of depression and a variety of other conditions associated with anxiety and nerve pain. Previous studies in our laboratory demonstrated that SJW inhibits insulin-stimulated glucose uptake and adipocyte differentiation in cultured murine and mature human adipocytes. To investigate the effects of SJW on adipocyte function in vivo, we utilized C57BL/6J mice. In our studies, mice were administered SJW extract (200 mg/kg) once daily by gavage for two weeks. In contrast to our in vitro studies, mice treated with SJW extract showed increased levels of adiponectin in white adipose tissue in a depot specific manner (P < 0.01). SJW also exerted an insulin-sensitizing effect as indicated by a significant increase in insulin-stimulated Akt serine phosphorylation in epididymal white adipose tissue (P < 0.01). Food intake, body weight, fasting blood glucose, and fasting insulin did not differ between the two groups. These results are important as they indicate that SJW does not promote metabolic dysfunction in adipose tissue in vivo.

  2. Molecular mechanisms of insulin resistance in diabetes.

    PubMed

    Soumaya, Kouidhi

    2012-01-01

    Molecular components of impaired insulin signaling pathway have emerged with growing interest to understand how the environment and genetic susceptibility combine to cause defects in this fundamental pathway that lead to insulin resistance. When insulin resistance is combined with beta-cell defects in glucose-stimulated insulin secretion, impaired glucose tolerance, hyperglycemia, or Type 2 diabetes can result. The most common underlying cause is obesity, although primary insulin resistance in normal-weight individuals is also possible. The adipose tissue releases free fatty acids that contribute to insulin resistance and also acts as a relevant endocrine organ producing mediators (adipokines) that can modulate insulin signalling. This chapter deals with the core elements promoting, insulin resistance, associated with impaired insulin signalling pathway and adipocyte dysfunction. A detailed understanding of these basic pathophysiological mechanisms is critical for the development of novel therapeutic strategies to treat diabetes.

  3. Regulation of the pro-inflammatory cytokine osteopontin by GIP in adipocytes - A role for the transcription factor NFAT and phosphodiesterase 3B

    SciTech Connect

    Omar, Bilal; Banke, Elin; Guirguis, Emilia; Aakesson, Lina; Manganiello, Vincent; Lyssenko, Valeriya; Groop, Leif; Gomez, Maria F.; Degerman, Eva

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer GIP stimulates lipogenesis and osteopontin expression in primary adipocytes. Black-Right-Pointing-Pointer GIP-induced osteopontin expression is NFAT-dependent. Black-Right-Pointing-Pointer Osteopontin expression is PDE3-dependent. Black-Right-Pointing-Pointer Osteopontin expression is increased in PDE3B KO mice. -- Abstract: The incretin - glucose-dependent insulinotropic polypeptide (GIP) - and the pro-inflammatory cytokine osteopontin are known to have important roles in the regulation of adipose tissue functions. In this work we show that GIP stimulates lipogenesis and osteopontin expression in primary adipocytes. The GIP-induced increase in osteopontin expression was inhibited by the NFAT (the transcription factor nuclear factor of activated T-cells) inhibitor A-285222. Also, the NFAT kinase glycogen synthase kinase (GSK) 3 was upregulated by GIP. To test whether cAMP might be involved in GIP-mediated effects on osteopontin a number of strategies were used. Thus, the {beta}3-adrenergic receptor agonist CL316,243 stimulated osteopontin expression, an effects which was mimicked by OPC3911, a specific inhibitor of phosphodiesterase 3. Furthermore, treatment of phosphodiesterase 3B knock-out mice with CL316,243 resulted in a dramatic upregulation of osteopontin in adipose tissue which was not the case in wild-type mice. In summary, we delineate mechanisms by which GIP stimulates osteopontin in adipocytes. Given the established link between osteopontin and insulin resistance, our data suggest that GIP by stimulating osteopontin expression, also could promote insulin resistance in adipocytes.

  4. Bone marrow adipocytes as negative regulators of the hematopoietic microenvironment

    PubMed Central

    Naveiras, Olaia; Nardi, Valentina; Wenzel, Pamela L.; Fahey, Frederic; Daley, George Q.

    2009-01-01

    Osteoblasts and endothelium constitute functional niches that support hematopoietic stem cells (HSC) in mammalian bone marrow (BM) 1,2,3 . Adult BM also contains adipocytes, whose numbers correlate inversely with the hematopoietic activity of the marrow. Fatty infiltration of hematopoietic red marrow follows irradiation or chemotherapy and is a diagnostic feature in biopsies from patients with marrow aplasia 4. To explore whether adipocytes influence hematopoiesis or simply fill marrow space, we compared the hematopoietic activity of distinct regions of the mouse skeleton that differ in adiposity. By flow cytometry, colony forming activity, and competitive repopulation assay, HSCs and short-term progenitors are reduced in frequency in the adipocyte-rich vertebrae of the mouse tail relative to the adipocyte-free vertebrae of the thorax. In lipoatrophic A-ZIP/F1 “fatless” mice, which are genetically incapable of forming adipocytes8, and in mice treated with the PPARγ inhibitor Bisphenol-A-DiGlycidyl-Ether (BADGE), which inhibits adipogenesis9, post-irradiation marrow engraftment is accelerated relative to wild type or untreated mice. These data implicate adipocytes as predominantly negative regulators of the bone marrow microenvironment, and suggest that antagonizingmarrow adipogenesis may enhance hematopoietic recovery in clinical bone marrow transplantation. PMID:19516257

  5. Carboxylated and Uncarboxylated Forms of Osteocalcin Directly Modulate the Glucose Transport System and Inflammation in Adipocytes

    PubMed Central

    Hill, H. S.; Grams, J.; Walton, R. G.; Liu, J.; Moellering, D. R.; Garvey, W. T.

    2017-01-01

    Osteocalcin is secreted by osteoblasts and improves insulin sensitivity in vivo, although mechanisms remain unclear. We tested the hypothesis that osteocalcin directly modulates cell biology in insulin-targeted peripheral tissues. In L-6 myocytes, osteocalcin stimulated glucose transport both in the absence (basal) and presence of insulin. Similarly, in primary cultured adipocytes, both carboxylated and uncarboxylated osteocalcin increased basal and insulin-stimulated glucose transport as well as insulin sensitivity. Osteocalcin also increased basal and insulin-stimulated glucose oxidation, though there was no effect on fatty acid synthesis or lipolysis. In primary-cultured adipocytes, both forms of osteocalcin suppressed secretion of tumor necrosis factor alpha into the media; however, only carboxylated osteocalcin suppressed interleukin 6 release, and neither form of osteocalcin modulated monocyte chemoattractant protein-1 secretion. Both carboxylated and uncarboxylated osteocalcin increased secretion of adiponectin and the anti-inflammatory cytokine interleukin 10. In conclusion, both carboxylated and uncarboxylated osteocalcin directly increase glucose transport in adipocytes and muscle cells, while suppressing proinflammatory cytokine secretion and stimulating interleukin 10 and adiponectin release. Thus, these results provide a mechanism for the insulin-sensitizing effects of osteocalcin and help elucidate the role that bone plays in regulating systemic metabolism. PMID:24554534

  6. Effects of C-reactive protein on adipokines genes expression in 3T3-L1 adipocytes

    SciTech Connect

    Yuan, Guoyue; Jia, Jue; Di, Liangliang; Zhou, Libin; Dong, Sijing; Ye, Jingjing; Wang, Dong; Yang, Ling; Wang, Jifang; Li, Lianxi; Yang, Ying; Mao, Chaoming; Chen, Mingdao

    2012-08-03

    Highlights: Black-Right-Pointing-Pointer CRP increases TNF-{alpha} and IL-6 genes expression in matured 3T3-L1 adipocytes. Black-Right-Pointing-Pointer CRP suppresses adiponectin, leptin and PPAR-{gamma} mRNA levels in matured 3T3-L1 cells. Black-Right-Pointing-Pointer Wortmannin reverses effects of CRP on adiponectin, TNF-{alpha} and leptin mRNA levels. Black-Right-Pointing-Pointer CRP may regulate IR, obesity and metabolic syndrome by this mechanism. -- Abstract: Adipose tissue is now recognized to be an important endocrine organ, secreting a variety of adipokines that are involved in the regulation of energy metabolism, insulin resistance and metabolic syndrome. C-reactive protein (CRP) is considered as one of the most sensitive markers of inflammation. A number of studies have shown that elevation of CRP concentrations is an independent predictive parameter of type 2 diabetes mellitus, which is also strongly associated with various components of the metabolic syndrome. The aim of the present study is to investigate the effects of CRP on adipokines genes expression in 3T3-L1 adipocytes. Quantitative real-time PCR analysis revealed that CRP inhibited adiponectin, leptin and peroxisome proliferator-activated receptor-gamma (PPAR-{gamma}) genes expression and raised tumor necrosis factor-{alpha} (TNF-{alpha}) and interleukin-6 (IL-6) mRNA levels in matured 3T3-L1 adipocytes in a dose and time-dependent manner. Pharmacological inhibition of phosphatidylinositol (PI)-3 kinase by wortmannin partially reversed the effects of CRP on adiponectin, TNF-{alpha} and leptin genes expression. These results collectively suggest that CRP regulates adiponectin, TNF-{alpha}, leptin, IL-6 and PPAR-{gamma} genes expression, and that might represent a mechanism by which CRP regulates insulin resistance, obesity and metabolic syndrome.

  7. Human white adipocytes convert into "rainbow" adipocytes in vitro.

    PubMed

    Maurizi, Giulia; Poloni, Antonella; Mattiucci, Domenico; Santi, Spartaco; Maurizi, Angela; Izzi, Valerio; Giuliani, Angelica; Mancini, Stefania; Zingaretti, Maria Cristina; Perugini, Jessica; Severi, Ilenia; Falconi, Massimo; Vivarelli, Marco; Rippo, Maria Rita; Corvera, Silvia; Giordano, Antonio; Leoni, Pietro; Cinti, Saverio

    2016-12-17

    White adipocytes are plastic cells able to reversibly transdifferentiate into brown adipocytes and into epithelial glandular cells under physiologic stimuli in vivo. These plastic properties could be used in future for regenerative medicine, but are incompletely explored in their details. Here, we focused on plastic properties of human mature adipocytes (MA) combining gene expression profile through microarray analysis with morphologic data obtained by electron and time lapse microscopy. Primary MA showed the classic morphology and gene expression profile of functional mature adipocytes. Notably, despite their committed status, MA expressed high levels of reprogramming genes. MA from ceiling cultures underwent transdifferentiation towards fibroblast-like cells with a well-differentiated morphology and maintaining stem cell gene signatures. The main morphologic aspect of the transdifferentiation process was the secretion of large lipid droplets and the development of organelles necessary for exocrine secretion further supported the liposecretion process. Of note, electron microscope findings suggesting liposecretion phenomena were found also in explants of human fat and rarely in vivo in fat biopsies from obese patients. In conclusion, both MA and post-liposecretion adipocytes show a well-differentiated phenotype with stem cell properties in line with the extraordinary plasticity of adipocytes in vivo. This article is protected by copyright. All rights reserved.

  8. Carbamazepine directly inhibits adipocyte differentiation through activation of the ERK 1/2 pathway

    PubMed Central

    Turpin, E; Muscat, A; Vatier, C; Chetrite, G; Corruble, E; Moldes, M; Fève, B

    2013-01-01

    Background and Purpose Carbamazepine (CBZ), known for its anti-epileptic, analgesic and mood-stabilizing properties, is also known to induce weight gain but the pathophysiology of this adverse effect is still largely unknown. We tested the hypothesis that CBZ could have a direct effect on adipocyte development and metabolism. Experimental Research We studied the effects of CBZ on morphological biochemical and molecular markers of adipogenesis, using several pre-adipocyte murine cell lines (3T3-L1, 3T3-F442A and T37i cells) and primary cultures of human pre-adipocytes. To delineate the mechanisms underlying the effect of CBZ, clonal expansion of pre-adipocytes, pro-adipogenic transcription factors, glucose uptake and lipolysis were also examined. Key Results CBZ strongly inhibited pre-adipocyte differentiation and triglyceride accumulation in a time- and dose-dependent manner in all models. Pleiotropic mechanisms were at the basis of the inhibitory effects of CBZ on adipogenesis and cell lipid accumulation. They included suppression of both clonal expansion and major adipogenic transcription factors such as PPAR-γ and CCAAT/enhancer binding protein-α, activation of basal lipolysis and decrease in insulin-stimulated glucose transport. Conclusions and Implications The effect of CBZ on adipogenesis involves activation of the ERK1/2 pathway. Our results show that CBZ acts directly on pre-adipocytes and adipocytes to alter adipose tissue development and metabolism. PMID:22889231

  9. Divergent mechanisms for the insulin resistant and hyperresponsive glucose transport in adipose cells from fasted and refed rats. Alterations in both glucose transporter number and intrinsic activity.

    PubMed Central

    Kahn, B B; Simpson, I A; Cushman, S W

    1988-01-01

    The effects of fasting and refeeding on the glucose transport response to insulin in isolated rat adipose cells have been examined using 3-O-methylglucose transport in intact cells and cytochalasin B binding and Western blotting in subcellular membrane fractions. After a 72-h fast, basal glucose transport activity decreases slightly and insulin-stimulated activity decreases greater than 85%. Following 48 h of fasting, insulin-stimulated glucose transport activity is diminished from 3.9 +/- 0.5 to 1.3 +/- 0.3 fmol/cell per min (mean +/- SEM). Similarly, the concentrations of glucose transporters are reduced with fasting in both the plasma membranes from insulin-stimulated cells from 38 +/- 5 to 18 +/- 3 pmol/mg of membrane protein and the low density microsomes from basal cells from 68 +/- 8 to 34 +/- 9 pmol/mg of membrane protein. Ad lib. refeeding for 6 d after a 48-h fast results in up to twofold greater maximally insulin-stimulated glucose transport activity compared with the control level (7.1 +/- 0.4 vs. 4.5 +/- 0.2 fmol/cell per min), before returning to baseline at 10 d. However, the corresponding concentration of glucose transporters in the plasma membranes is restored only to the control level (45 +/- 5 vs. 50 +/- 5 pmol/mg of membrane protein). Although the concentration of glucose transporters in the low density microsomes of basal cells remains decreased, the total number is restored to the control level due to an increase in low density microsomal protein. Thus, the insulin-resistant glucose transport in adipose cells from fasted rats can be explained by a decreased translocation of glucose transporters to the plasma membrane due to a depleted intracellular pool. In contrast, the insulin hyperresponsive glucose transport observed with refeeding appears to result from (a) a restored translocation of glucose transporters to the plasma membrane from a repleted intracellular pool and (b) enhanced plasma membrane glucose transporter intrinsic activity

  10. The effect of diet fat on rat adipocyte glucose transport.

    PubMed

    Ip, C; Tepperman, H M; De Witt, J; Tepperman, J

    1977-05-01

    Rats were fed either a high fat diet (67% of calories as lard) or high glucose diet (67% of calories as glucose) for 7-8 days. Basal and insulin stimulated net uptake of D glucose (D-L) and 2 deoxy D glucose uptake by free fat cells of fat rats were depressed. Net transport of D glucose (D-L) by purified adipocyte plasma membranes of fat red rats was also diminished. Incubation of fat cells from glucose fed rats with insulin before homogenization for membrane preparation increased net D glucose transport by subsequently purified membranes in two experiments to a greater extent than in similar preparations from rat fed rats. These experiments suggest that fat feeding modifies the plasma membranes of fat cells so that both glucose transport and the stimulatory effect of insulin on the process are decreased.

  11. Phloretin promotes adipocyte differentiation in vitro and improves glucose homeostasis in vivo

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adipocyte dysfunction is associated with many metabolic diseases such as obesity, insulin resistance and diabetes. Previous studies found that phloretin promotes 3T3-L1 cells differentiation, but the underlying mechanisms for phloretin's effects on adipogenesis remain unclear. In this study, we demo...

  12. Adenovirusmediated interference of FABP4 regulates ADIPOQ, LEP and LEPR expression in bovine adipocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fatty acid binding protein 4 plays an important role in fatty acid transportation in adipocytes and its expression is related to obesity, insulin resistance, metabolic syndrome and intramuscular fat content. Yet little is understood about FABP4 functions at the cellular level in the bovine. Thus, we...

  13. Structural and functional changes in human insulin induced by methylglyoxal.

    PubMed

    Jia, Xuming; Olson, Douglas J H; Ross, Andrew R S; Wu, Lingyun

    2006-07-01

    Elevated methylglyoxal (MG) levels have been reported in insulin-resistance syndrome. The present study investigated whether MG, a highly reactive metabolite of glucose, induced structural and functional changes of insulin. Incubation of human insulin with MG in vitro yielded MG-insulin adducts, as evidenced by additional peaks observed on mass spectrometric (MS) analysis of the incubates. Tandem MS analysis of insulin B-chain adducts confirmed attachment of MG at an arginine residue. [3H]-2-deoxyglucose uptake by 3T3-L1 adipocytes was significantly and concentration-dependently decreased after the treatment with MG-insulin adducts, in comparison with the effect of native insulin at the same concentrations. A significant decrease of glucose uptake induced by MG-insulin adducts was also observed in L8 skeletal muscle cells. MG alone had no effect on glucose uptake or the transcriptional expression of insulin receptor. Unlike native insulin, MG-insulin adducts did not inhibit insulin release from pancreatic beta-cells. The degradation of MG-insulin through liver cells was also decreased. In conclusion, MG modifies insulin by attaching to internal arginine residue in beta-chain of insulin. The formation of this MG-insulin adduct decreases insulin-mediated glucose uptake, impairs autocrine control of insulin secretion, and decreases insulin clearance. These structural and functional abnormalities of insulin molecule may contribute to the pathogenesis of insulin resistance.

  14. Differentiation and characterization of human facial subcutaneous adipocytes

    PubMed Central

    Chon, Su-Hyoun; Pappas, Apostolos

    2014-01-01

    Aging is associated with the loss of facial subcutaneous fat and with increased abdominal subcutaneous fat. Site specific differences in adipocyte phenotype and/or gene expression may play a role in these age-related changes. In this study, we isolated and characterized human facial preadipocytes and investigated distinct metabolic properties such as a differentiation pattern in relation to abdominal preadipocytes. Subcutaneous preadipocytes were isolated from human facial and abdominal skin and cultured in the presence of differentiation factors including rosiglitazone, a known peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist, isobutyl-methyl xanthine (IBMX) and insulin. Differentiation was characterized microscopically and by quantitative real-time PCR. Unexpected superior adipogenic capacity of facial preadipocytes was observed; more facial preadipocytes differentiated in response to rosiglitazone than abdominal preadipocytes and facial preadipocytes retained their ability to differentiate through passage 11 compared with passage 5 for abdominal preadipocytes. Experiments confirmed a reduced lipolysis response in facial versus abdominal adipocytes after exposure to isoproterenol, which was consistent with the reduced β2-adrenergic receptor expression by 60% in the facial cells. The expression of other lipid metabolic gene markers was similar in both facial and abdominal adipocytes with the exception of β3-adrenergic receptor which was only found in abdominal adipose tissue. Gene profiling, by microarray analysis, identified that several HOX genes are robustly reduced in facial adipocytes compared to abdominal adipocytes, suggesting different characteristics between the 2 fat depots. These differences may have implications for development of treatments for facial fat loss during aging. PMID:26167398

  15. Branched short-chain fatty acids modulate glucose and lipid metabolism in primary adipocytes

    PubMed Central

    Heimann, Emilia; Nyman, Margareta; Pålbrink, Ann-Ki; Lindkvist-Petersson, Karin; Degerman, Eva

    2016-01-01

    ABSTRACT Short-chain fatty acids (SCFAs), e.g. acetic acid, propionic acid and butyric acid, generated through colonic fermentation of dietary fibers, have been shown to reach the systemic circulation at micromolar concentrations. Moreover, SCFAs have been conferred anti-obesity properties in both animal models and human subjects. Branched SCFAs (BSCFAs), e.g., isobutyric and isovaleric acid, are generated by fermentation of branched amino acids, generated from undigested protein reaching colon. However, BSCFAs have been sparsely investigated when referring to effects on energy metabolism. Here we primarily investigate the effects of isobutyric acid and isovaleric acid on glucose and lipid metabolism in primary rat and human adipocytes. BSCFAs inhibited both cAMP-mediated lipolysis and insulin-stimulated de novo lipogenesis at 10 mM, whereas isobutyric acid potentiated insulin-stimulated glucose uptake by all concentrations (1, 3 and 10 mM) in rat adipocytes. For human adipocytes, only SCFAs inhibited lipolysis at 10 mM. In both in vitro models, BSCFAs and SCFAs reduced phosphorylation of hormone sensitive lipase, a rate limiting enzyme in lipolysis. In addition, BSCFAs and SCFAs, in contrast to insulin, inhibited lipolysis in the presence of wortmannin, a phosphatidylinositide 3-kinase inhibitor and OPC3911, a phosphodiesterase 3 inhibitor in rat adipocytes. Furthermore, BSCFAs and SCFAs reduced insulin-mediated phosphorylation of protein kinase B. To conclude, BSCFAs have effects on adipocyte lipid and glucose metabolism that can contribute to improved insulin sensitivity in individuals with disturbed metabolism. PMID:27994949

  16. Caveolin expression and activation in retroperitoneal and subcutaneous adipocytes: influence of a high-fat diet.

    PubMed

    Gómez-Ruiz, Ana; Milagro, Fermín I; Campión, Javier; Martínez, J Alfredo; de Miguel, Carlos

    2010-10-01

    The effect of a high-fat diet on the expression of the three main isoforms of caveolins in adipocytes isolated from rat retroperitoneal and subcutaneous white adipose tissue was investigated. Two distinct phases can be distinguished on a time-dependent response in adipocytes from both locations. The early stage affects only to retroperitoneal adipocytes and implies caveolin-1 activation and caveolin-2 inactivation, together with increased expression of insulin signaling intermediaries. This initial response would be aimed to counterbalance the energy overload. Continued exposure to the high-fat diet produces an increase in circulating glucose and insulin levels, inducing a late stage in which adipocytes from both locations are affected. This late stage is characterized by general increased caveolin-1 and caveolin-2 expression; while on the other hand, the insulin signaling intermediaries are downregulated, with the noticeable exception of GLUT-4, whose expression remains high. Therefore, it seems that at this stage caveolins and GLUT-4 are regulated independently of the insulin pathway, through a mechanism that could be mediated by inflammation and oxidative stress associated with obesity. Although this GLUT-4 upregulation suggests a response against the raise in circulating glucose, this might not be the case, since the developing insulin resistance at this stage indicates a prediabetic state. We have also found that the high-fat diet is able to induce the expression of muscle-specific caveolin-3 in retroperitoneal adipocytes since the initial phase. This observation is similar to what we reported previously in skeletal muscle (Gómez-Ruiz et al., 2009, FEBS Lett 583:3259-3264), suggesting a similar regulatory mechanism for this isoform.

  17. Curcumin and resveratrol inhibit nuclear factor-kappaB-mediated cytokine expression in adipocytes

    PubMed Central

    Gonzales, Amanda M; Orlando, Robert A

    2008-01-01

    Background Adipocytes express inflammatory mediators that contribute to the low-level, chronic inflammation found in obese subjects and have been linked to the onset of cardiovascular disorders and insulin resistance associated with type 2 diabetes mellitus. A reduction in inflammatory gene expression in adipocytes would be expected to reverse this low-level, inflammatory state and improve cardiovascular function and insulin sensitivity. The natural products, curcumin and resveratrol, are established anti-inflammatory compounds that mediate their effects by inhibiting activation of NF-κB signaling. In the present study, we examined if these natural products can inhibit NF-κB activation in adipocytes and in doing so reduce cytokine expression. Methods Cytokine (TNF-α, IL-1β, IL-6) and COX-2 gene expression in 3T3-L1-derived adipocytes was measured by quantitative real-time PCR (qRT-PCR) with or without TNFα-stimulation. Cytokine protein and prostaglandin E2 (PGE2) expression were measured by ELISA. Effects of curcumin and resveratrol were evaluated by treating TNFα-stimulated adipocytes with each compound and 1) assessing the activation state of the NF-κB signaling pathway and 2) measuring inflammatory gene expression by qRT-PCR and ELISA. Results Both preadipocytes and differentiated adipocytes express the genes for TNF-α, IL-6, and COX-2, key mediators of the inflammatory response. Preadipocytes were also found to express IL-1β; however, IL-1β expression was absent in differentiated adipocytes. TNF-α treatment activated NF-κB signaling in differentiated adipocytes by inducing IκB degradation and NF-κB translocation to the nucleus, and as a result increased IL-6 (6-fold) and COX-2 (2.5-fold) mRNA levels. TNF-α also activated IL-1β gene expression in differentiated adipocytes, but had no effect on endogenous TNF-α mRNA levels. No detectable TNFα or IL-1β was secreted by adipocytes. Curcumin and resveratrol treatment inhibited NF-κB activation and

  18. Insulin and Insulin Resistance

    PubMed Central

    2005-01-01

    As obesity and diabetes reach epidemic proportions in the developed world, the role of insulin resistance and its consequences are gaining prominence. Understanding the role of insulin in wide-ranging physiological processes and the influences on its synthesis and secretion, alongside its actions from the molecular to the whole body level, has significant implications for much chronic disease seen in Westernised populations today. This review provides an overview of insulin, its history, structure, synthesis, secretion, actions and interactions followed by a discussion of insulin resistance and its associated clinical manifestations. Specific areas of focus include the actions of insulin and manifestations of insulin resistance in specific organs and tissues, physiological, environmental and pharmacological influences on insulin action and insulin resistance as well as clinical syndromes associated with insulin resistance. Clinical and functional measures of insulin resistance are also covered. Despite our incomplete understanding of the complex biological mechanisms of insulin action and insulin resistance, we need to consider the dramatic social changes of the past century with respect to physical activity, diet, work, socialisation and sleep patterns. Rapid globalisation, urbanisation and industrialisation have spawned epidemics of obesity, diabetes and their attendant co-morbidities, as physical inactivity and dietary imbalance unmask latent predisposing genetic traits. PMID:16278749

  19. Effects of Estrogen Therapy on Bone Marrow Adipocytes in Postmenopausal Osteoporotic Women

    PubMed Central

    Syed, Farhan A.; Oursler, Merry Jo; Hefferan, Theresa E.; Peterson, James. M.; Riggs, B. Lawrence; Khosla, Sundeep

    2009-01-01

    Introduction Aging is associated not only with bone loss but also with increases in bone marrow adipocytes. Since osteoblasts and adipocytes are derived from a common precursor, it is possible that with aging, there is a preferential “switch” in commitment of this precursor to the adipocyte over the osteoblast lineage. We tested the hypothesis that the apparent “age-related” increase in marrow adipocytes is due, at least in part, to estrogen (E) deficiency. Methods Reanalysis of bone biopsies from a randomized, placebo-controlled trial involving 56 postmenopausal osteoporotic women (mean age, 64 years) treated either with placebo (PL, n = 27) or transdermal estradiol (0.1 mg/d, n = 29) for 1 year. Results Adipocyte volume/tissue volume (AV/TV) and adipocyte number (Ad#) increased (by ∼ 20%, P < 0.05) in the PL group, but were unchanged (Ad#) or decreased (AV/TV, by −24%, P < 0.001) in the E group. E treatment also prevented increases in mean adipocyte size over 1 year. Conclusions These findings represent the first in vivo demonstration in humans that not only ongoing bone loss, but also the increase in bone marrow adipocyte number and size in postmenopausal osteoporotic women may be due, at least in part, to E deficiency. PMID:18274695

  20. Tocotrienol suppresses adipocyte differentiation and Akt phosphorylation in 3T3-L1 preadipocytes.

    PubMed

    Uto-Kondo, Harumi; Ohmori, Reiko; Kiyose, Chikako; Kishimoto, Yoshimi; Saito, Hisako; Igarashi, Osamu; Kondo, Kazuo

    2009-01-01

    In vivo studies show that alpha-tocotrienol and gamma-tocotrienol accumulate in adipose tissue. Furthermore, a recent study reports that the oral administration of gamma-tocotrienol from a tocotrienol-rich fraction from palm oil (TRF) decreases body fat levels in rats. The objective of this study was to evaluate the effect of TRF and its components on adipocyte differentiation in 3T3-L1 preadipocytes, which differentiated into adipocytes in the presence of 1.8 micromol/L insulin. TRF suppressed the insulin-induced mRNA expression of adipocyte-specific genes such as PPARgamma, adipocyte fatty acid-binding protein (aP2), and CCAAT/enhancer-binding protein-alpha (C/EBPalpha) compared with the differentiation of 3T3-L1 preadipocytes into adipocytes only in the presence of insulin. To confirm the suppressive effect of TRF, the major components of TRF, such as alpha-tocotrienol, gamma-tocotrienol, and alpha-tocopherol, were investigated. Alpha-tocotrienol and gamma-tocotrienol decreased the insulin-induced PPARgamma mRNA expression by 55 and 90%, respectively, compared with insulin, whereas alpha-tocopherol increased the mRNA expression. In addition, gamma-tocotrienol suppressed the insulin-induced aP2 and C/EBPalpha mRNA expression, triglyceride accumulation, and PPARgamma protein levels compared with insulin. The current results also revealed that gamma-tocotrienol inhibited the insulin-stimulated phosphorylation of Akt but not extracellular signal-regulated kinase (ERK)1/2 in the insulin signaling pathway of 3T3-L1 preadipocytes. Thus, the antiadipogenic effect of TRF depends on alpha-tocotrienol and gamma-tocotrienol, and gamma-tocotrienol may be a more potent inhibitor of adipogenesis than alpha-tocotrienol. Therefore, the results of this study suggest that tocotrienol suppresses insulin-induced differentiation and Akt phosphorylation in 3T3-L1 preadipocytes. Furthermore, tocotrienol could act as an antiadipogenic vitamin in the nutrient-mediated regulation of body

  1. Adipose Estrogen and Increased Breast Cancer Risk in Obesity: Regulation by Leptin and Insulin

    DTIC Science & Technology

    2007-09-07

    usually associated with insulin resistance we had also proposed to determine the induction of Aromatase and βHSD5 mRNA expression in response to...3 days. Metabolic insulin resistance was determined by measuring insulin mediated glucose uptake. Glucose uptake was reduced by 50-70% in...standardize conditions in our cell culture system to mimic metabolic insulin resistance . These “insulin-resistant” adipocytes are currently being used to

  2. Recent Advances in Proteomic Studies of Adipose Tissues and Adipocytes

    PubMed Central

    Kim, Eun Young; Kim, Won Kon; Oh, Kyoung-Jin; Han, Baek Soo; Lee, Sang Chul; Bae, Kwang-Hee

    2015-01-01

    Obesity is a chronic disease that is associated with significantly increased levels of risk of a number of metabolic disorders. Despite these enhanced health risks, the worldwide prevalence of obesity has increased dramatically over the past few decades. Obesity is caused by the accumulation of an abnormal amount of body fat in adipose tissue, which is composed mostly of adipocytes. Thus, a deeper understanding of the regulation mechanism of adipose tissue and/or adipocytes can provide a clue for overcoming obesity-related metabolic diseases. In this review, we describe recent advances in the study of adipose tissue and/or adipocytes, focusing on proteomic approaches. In addition, we suggest future research directions for proteomic studies which may lead to novel treatments of obesity and obesity-related diseases. PMID:25734986

  3. Rosiglitazone drives cavin-2/SDPR expression in adipocytes in a CEBPα-dependent manner

    PubMed Central

    Wasserstrom, Sebastian; Säll, Johanna; Göransson, Olga; Swärd, Karl; Stenkula, Karin G.

    2017-01-01

    Caveolae are abundant adipocyte surface domains involved in insulin signaling, membrane trafficking and lipid homeostasis. Transcriptional control mechanisms for caveolins and cavins, the building blocks of caveolae, are thus arguably important for adipocyte biology and studies in this area may give insight into insulin resistance and diabetes. Here we addressed the hypothesis that one of the less characterized caveolar components, cavin-2 (SDPR), is controlled by CCAAT/Enhancer Binding Protein (CEBPα) and Peroxisome Proliferator-Activated Receptor Gamma (PPARG). Using human mRNA expression data we found that SDPR correlated with PPARG in several tissues. This was also observed during differentiation of 3T3-L1 fibroblasts into adipocytes. Treatment of 3T3-L1-derived adipocytes with the PPARγ-activator Rosiglitazone increased SDPR and CEBPα expression at both the mRNA and protein levels. Silencing of CEBPα antagonized these effects. Further, adenoviral expression of PPARγ/CEBPα or Rosiglitazone-treatment increased SDPR expression in primary rat adipocytes. The myocardin family coactivator MKL1 was recently shown to regulate SDPR expression in human coronary artery smooth muscle cells. However, we found that actin depolymerization, known to inhibit MKL1 and MKL2, was without effect on SDPR mRNA levels in adipocytes, even though overexpression of MKL1 and MKL2 had the capacity to increase caveolins and cavins and to repress PPARγ/CEBPα. Altogether, this work demonstrates that CEBPα expression and PPARγ-activity promote SDPR transcription and further supports the emerging notion that PPARγ/CEBPα and MKL1/MKL2 are antagonistic in adipocytes. PMID:28278164

  4. Effect of Glycine on Adipocyte Hypertrophy in a Metabolic Syndrome Rat Model.

    PubMed

    López, Yazmín Reyes; Pérez-Torres, Israel; Zúñiga-Muñoz, Alejandra; Lans, Verónica Guarner; Díaz-Díaz, Eulises; Castro, Elizabeth Soria; Espejel, Rodrigo Velázquez

    2016-01-01

    Glycine (Gly) lowers hypercholesterolemia, hypertriglyceridemia and hypertension but its role in preventing adipocyte hypertrophy and modulating enzymatic activity of adipocytes has not been studied. Here we evaluate the effect of 1% Gly in the diet on adipocyte hypertrophy and the modulation of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) in a metabolic syndrome (MS) rat model with intra-abdominal obesity. 32 Wistar rats were divided into 3 groups: control (C), MS, MS plus Gly (MS+Gly), and MS+Gly plus strychnine (MS+Gly+S). MS was induced by administering 30% sucrose in the drinking water for 16 weeks. In the MS+Gly and MS+Gly+S groups, the sucrose solution plus 1% Gly and 1 % Gly plus strychnine 10 μM were given during the last 4 weeks of the sucrose treatment. After 16 weeks of treatment, rats were sacrificed and the adipose tissue dissected. Gly in MS rats decreased body weight, intra-abdominal adipose tissue, adipocyte hypertrophy, blood pressure, triglycerides, insulin, HOMA-IR index, leptin, total fatty acids, non-esterified fatty acids and LPL activity. It increased fatty acids of the phospholipids, perilipin A expression and it decreased HSL expression, without changing LPL expression. The Gly receptor subunit-β was identified in adipocytes. In conclusion, Gly treatment regulates the activity of enzymes involved in the lipid metabolism of the adipocytes through the Gly receptor and it decreases the effects of the high sucrose diet.

  5. Diabetic human adipose tissue-derived mesenchymal stem cells fail to differentiate in functional adipocytes.

    PubMed

    Barbagallo, Ignazio; Li Volti, Giovanni; Galvano, Fabio; Tettamanti, Guido; Pluchinotta, Francesca R; Bergante, Sonia; Vanella, Luca

    2016-11-30

    Adipose tissue dysfunction represents a hallmark of diabetic patients and is a consequence of the altered homeostasis of this tissue. Mesenchymal stem cells (MSCs) and their differentiation into adipocytes contribute significantly in maintaining the mass and function of adult adipose tissue. The aim of this study was to evaluate the differentiation of MSCs from patients suffering type 2 diabetes (dASC) and how such process results in hyperplasia or rather a stop of adipocyte turnover resulting in hypertrophy of mature adipocytes. Our results showed that gene profile of all adipogenic markers is not expressed in diabetic cells after differentiation indicating that diabetic cells fail to differentiate into adipocytes. Interestingly, delta like 1, peroxisome proliferator-activated receptor alpha, and interleukin 1β were upregulated whereas Sirtuin 1 and insulin receptor substrate 1 gene expression were found downregulated in dASC compared to cells obtained from healthy subjects. Taken together our data indicate that dASC lose their ability to differentiate into mature and functional adipocytes. In conclusion, our in vitro study is the first to suggest that diabetic patients might develop obesity through a hypertrophy of existing mature adipocytes due to failure turnover of adipose tissue.

  6. Insulin sensitizing and insulinotropic action of berberine from Cortidis rhizoma.

    PubMed

    Ko, Byoung-Seob; Choi, Soo Bong; Park, Seong Kyu; Jang, Jin Sun; Kim, Yeong Eun; Park, Sunmin

    2005-08-01

    Our preliminary study demonstrated that 70% ethanol Cortidis Rhizoma extracts (CR) had a hypoglycemic action in diabetic animal models. We determined whether CR fractions acted as anti-diabetic agent, and a subsequent investigation of the action mechanism of the major compound, berberine ([C(20)H(18)NO(4)](+)), was carried out in vitro. The 20, 40 and 60% methanol fractions from the XAD-4 column contained the most insulin sensitizing activities in 3T3-L1 adipocytes. The common major peak in these fractions was berberine. Treatment with 50 microM berberine plus differentiation inducers significantly reduced triglyceride accumulation by decreased differentiation of 3T3-L1 fibroblasts to adipocytes and triglyceride synthesis. Significant insulin sensitizing activity was observed in 3T3-L1 adipocytes which were given 50 microM berberine plus 0.2 nM insulin to reach a glucose uptake level increased by 10 nM of insulin alone. This was associated with increased glucose transporter-4 translocation into the plasma membrane via enhancing insulin signaling pathways and the insulin receptor substrate-1-phosphoinositide 3 Kinase-Akt. Berberine also increased glucose-stimulated insulin secretion and proliferation in Min6 cells via an enhanced insulin/insulin-like growth factor-1 signaling cascade. Data suggested that berberine can act as an effective insulin sensitizing and insulinotropic agent. Therefore, berberine can be used as anti-diabetic agent for obese diabetic patients.

  7. Early B cell factor 1 regulates adipocyte morphology and lipolysis in white adipose tissue.

    PubMed

    Gao, Hui; Mejhert, Niklas; Fretz, Jackie A; Arner, Erik; Lorente-Cebrián, Silvia; Ehrlund, Anna; Dahlman-Wright, Karin; Gong, Xiaowei; Strömblad, Staffan; Douagi, Iyadh; Laurencikiene, Jurga; Dahlman, Ingrid; Daub, Carsten O; Rydén, Mikael; Horowitz, Mark C; Arner, Peter

    2014-06-03

    White adipose tissue (WAT) morphology characterized by hypertrophy (i.e., fewer but larger adipocytes) associates with increased adipose inflammation, lipolysis, insulin resistance, and risk of diabetes. However, the causal relationships and the mechanisms controlling WAT morphology are unclear. Herein, we identified EBF1 as an adipocyte-expressed transcription factor with decreased expression/activity in WAT hypertrophy. In human adipocytes, the regulatory targets of EBF1 were enriched for genes controlling lipolysis and adipocyte morphology/differentiation, and in both humans and murine models, reduced EBF1 levels associated with increased lipolysis and adipose hypertrophy. Although EBF1 did not affect adipose inflammation, TNFα reduced EBF1 gene expression. High-fat diet intervention in Ebf1(+/-) mice resulted in more pronounced WAT hypertrophy and attenuated insulin sensitivity compared with wild-type littermate controls. We conclude that EBF1 is an important regulator of adipose morphology and fat cell lipolysis and may constitute a link between WAT inflammation, altered lipid metabolism, adipose hypertrophy, and insulin resistance.

  8. Early B-cell Factor 1 Regulates Adipocyte Morphology and Lipolysis in White Adipose Tissue

    PubMed Central

    Gao, Hui; Mejhert, Niklas; Fretz, Jackie A.; Arner, Erik; Lorente-Cebrián, Silvia; Ehrlund, Anna; Dahlman-Wright, Karin; Gong, Xiaowei; Strömblad, Staffan; Douagi, Iyadh; Laurencikiene, Jurga; Dahlman, Ingrid; Daub, Carsten O.; Rydén, Mikael; Horowitz, Mark C.; Arner, Peter

    2014-01-01

    Summary White adipose tissue (WAT) morphology characterized by hypertrophy (i.e. fewer but larger adipocytes) associates with increased adipose inflammation, lipolysis, insulin resistance and risk of diabetes. However, the causal relationships and the mechanisms controlling WAT morphology are unclear. Herein, we identified EBF1 as an adipocyte-expressed transcription factor with decreased expression/activity in WAT hypertrophy. In human adipocytes, the regulatory targets of EBF1 were enriched for genes controlling lipolysis and adipocyte morphology/differentiation and in both humans and murine models, reduced EBF1 levels associated with increased lipolysis and adipose hypertrophy. Although EBF1 did not affect adipose inflammation, TNFα reduced EBF1 gene expression. High fat diet-intervention in Ebf1+/− mice resulted in more pronounced WAT hypertrophy and attenuated insulin sensitivity compared with wild-type littermate controls. We conclude that EBF1 is an important regulator of adipose morphology and fat cell lipolysis and may constitute a link between WAT inflammation, altered lipid metabolism, adipose hypertrophy and insulin resistance. PMID:24856929

  9. Adipocytes WNT5a mediated dedifferentiation: a possible target in pancreatic cancer microenvironment

    PubMed Central

    Zoico, Elena; Darra, Elena; Rizzatti, Vanni; Budui, Simona; Franceschetti, Guido; Mazzali, Gloria; Rossi, Andrea P; Fantin, Francesco; Menegazzi, Marta; Cinti, Saverio; Zamboni, Mauro

    2016-01-01

    A significant epidemiological association between obesity and pancreatic ductal adenocarcinoma (PDAC) has previously been described, as well as a correlation between the degree of pancreatic steatosis, PDAC risk and prognosis. The underlying mechanisms are still not completely known. After co-culture of 3T3-L1 adipocytes and MiaPaCa2 with an in vitro transwell system we observed the appearance of fibroblast-like cells, along with a decrease in number and size of remaining adipocytes. RT-PCR analyses of 3T3-L1 adipocytes in co-culture showed a decrease in gene expression of typical markers of mature adipocytes, in parallel with an increased expression of fibroblast-specific and reprogramming genes. We found an increased WNT5a gene and protein expression early in MiaPaCa2 cells in co-culture. Additionally, EMSA of c-Jun and AP1 in 3T3-L1 demonstrated an increased activation in adipocytes after co-culture. Treatment with WNT5a neutralizing antibody completely reverted the activation of c-Jun and AP1 observed in co-cultured adipocytes. Increasing doses of recombinant SFRP-5, a competitive inhibitor for WNT5a receptor, added to the co-culture medium, were able to block the dedifferentiation of adipocytes in co-culture. These data support a WNT5a-mediated dedifferentiation process with adipocytes reprogramming toward fibroblast-like cells that might profoundly influence cancer microenvironment. PMID:26958939

  10. Effects of perfluorinated chemicals on adipocyte development ...

    EPA Pesticide Factsheets

    Obesity is a growing concern in the US population. Current interest is high in the role played by environmental factors called obesogens that may contribute to obesity through developmental exposure. One class of potential obesogens is the family of perfluorinated chemicals used as surfactants in a variety of industrial applications. Given the importance of understanding the role these compounds play in lipid homeostasis we used pre-adipocyte 3T3-L1 mouse fibroblast cells (Zen-Bio, RTP NC) to study their effects on adipogenesis and lipid accumulation. These cells differentiate into adipocytes accumulating large lipid droplets. Cultures were treated with perfluorooctanoic acid (PFOA) (1-200uM), perfluorononanoic acid (PFNA) (5-lOOuM), perfluorooctane sulfonate (PFOS) (5O-300uM), and perfluorohexane sulfonate (PFHxS) (40- 250uM). Cell size number, and lipid content were assessed using morphomeiric analysis. All four compounds decreased cell size compared to control, and PFNA was most potent, in terms of lowest observed effect concentration (LOEC), whereas PFOA was least potent. Cell number increased for all perfluorinated chemicals tested, most potently for PFNA and least for PFOS. Interestingly, average lipid area per cell for all four chemicals decreased compared to control, but PFOS and PFHxS had increased total lipid area. Additionally, significant increases in total triglyceride were noted for all compounds compared to controls. PFOA and PFNA increased trigly

  11. Insulin Therapy

    MedlinePlus

    ... 3 hours and lasts 12 to 16 hours.Long-acting insulin (such as insulin glargine and insulin detemir) ... hard to time their meals around regular insulin injections. Sometimes they end up eating too soon or ...

  12. Fluctuation of insulin resistance in a leprechaun with a primary defect in insulin binding.

    PubMed

    Kobayashi, M; Takata, Y; Sasaoka, T; Shigeta, Y; Goji, K

    1988-05-01

    A 3-month-old female leprechaun demonstrated extreme insulin resistance with hyperinsulinemia (330 mumol/L) and resistance to exogenous insulin. Insulin binding to erythrocytes, cultured lymphocytes, and fibroblasts from the patient were decreased to less than 20% of normal, whereas insulin-like growth factor I binding to fibroblasts was normal. Antiinsulin receptor antibody binding to cultured lymphocytes was also decreased to 20% of normal, indicating a decreased concentration of insulin receptors on the cell surface. The ability of insulin to stimulate D-[14C]glucose uptake was decreased to 35% of normal in the patient's fibroblasts, and the dose-response curve was shifted to the right. With time, the insulin resistance fluctuated from near normal (fasting insulin, 244.0 pmol/L) to severe resistance (fasting insulin, 5740-9328 pmol/L), and an insulin tolerance test revealed amelioration of insulin resistance during remission. However, insulin binding to erythrocytes and adipocytes was decreased persistently to 20% of normal. These results indicate that the patient had a primary defect in her insulin receptors, i.e. decreased insulin receptor concentration. The variable degree of insulin resistance was possibly due to variable receptor function in the signal transmission process.

  13. Insulin phosphorylates calmodulin in preparations of solubilized rat hepatocyte insulin receptors

    SciTech Connect

    Sacks, D.B.; McDonald, J.M.

    1987-05-01

    It has previously been shown that insulin stimulates the phosphorylation of calmodulin in adipocyte insulin receptor preparations. Here they demonstrate that insulin also stimulates the phosphorylation of calmodulin in wheat germ lectin-enriched insulin receptor preparations obtained from rat hepatocytes. Standard phosphorylation assays were performed at 30C in the presence of 50mM Tris-HCl (pH 7.5), 0.1% (v/v) Triton X-100, 1mM EGTA, 50 M (el-TSP)ATP, 5mM MgCl2, 0.25 M polylysine, 1.2 M calmodulin and various CaS and insulin concentrations. The phosphorylation of calmodulin was determined by SDS-PAGE and autoradiography. Phosphorylation of calmodulin had an absolute requirement for insulin receptors, insulin and certain basic proteins. Phosphorylation was maximal above 13 nM insulin and at submicromolar CaS concentrations, whereas supramicromolar CaS concentrations were inhibitory. As was observed in the adipocyte insulin receptor system, calmodulin phosphorylation was dependent upon the presence of co-factors, such as polylysine, histone H/sub f/2b and protamine sulfate. The role played by these co-factors has not yet been established. These data suggest that both CaS and calmodulin participate in post receptor insulin events in hepatocytes.

  14. Ebf1-Dependent Control of the Osteoblast and Adipocyte Lineages

    PubMed Central

    Hesslein, David G. T.; Fretz, Jackie A.; Xi, Yougen; Nelson, Tracy; Zhou, Shoaming; Lorenzo, Joseph A.; Schatz, David G.; Horowitz, Mark C.

    2008-01-01

    Ebf1 is a transcription factor essential for B cell fate specification and function and important for the development of olfactory sensory neurons. We show here that Ebf1 also plays an important role in regulating osteoblast and adipocyte development in vivo. Ebf1 mRNA and protein is expressed in MSCs, in OBs at most stages of differentiation, and in adipocytes. Tibiae and femora from Ebf1−/− mice had a striking increase in all bone formation parameters examined including the number of OBs, osteoid volume, and bone formation rate. Serum osteocalcin, a marker of bone formation, was significantly elevated in mutant mice. The numbers of osteoclasts in bone were normal in younger (4 week-old) Ebf1−/− mice but increased in older (12 week-old) Ebf1−/− mice. This correlated well with in vitro osteoclast development from bone marrow cells. In addition to the increased osteoblastogenesis, there was a dramatic increase in adipocyte numbers in the bone marrow of Ebf1−/− mice. Increased adiposity was also seen histologically in the liver but not in the spleen of these mice, and accompanied by decreased deposition of adipose to subcutaneous sites. Thus Ebf1-deficient mice appear to be a new model of lipodystrophy. Ebf1 is a rare example of a transcription factor that regulates both the osteoblast and adipocyte lineages similarly. PMID:19130908

  15. Failure to initiate early insulin therapy – A risk factor for diabetic retinopathy in insulin users with Type 2 diabetes mellitus: Sankara Nethralaya-Diabetic Retinopathy Epidemiology and Molecular Genetics Study (SN-DREAMS, Report number 35)

    PubMed Central

    Gupta, Aditi; Delhiwala, Kushal S; Raman, Rajiv P G; Sharma, Tarun; Srinivasan, Sangeetha; Kulothungan, Vaitheeswaran

    2016-01-01

    Context: Insulin users have been reported to have a higher incidence of diabetic retinopathy (DR). Aim: The aim was to elucidate the factors associated with DR among insulin users, especially association between duration, prior to initiating insulin for Type 2 diabetes mellitus (DM) and developing DR. Materials and Methods: Retrospective cross-sectional observational study included 1414 subjects having Type 2 DM. Insulin users were defined as subjects using insulin for glycemic control, and insulin nonusers as those either not using any antidiabetic treatment or using diet control or oral medications. The duration before initiating insulin after diagnosis was calculated by subtracting the duration of insulin usage from the duration of DM. DR was clinically graded using Klein's classification. SPSS (version 9.0) was used for statistical analysis. Results: Insulin users had more incidence of DR (52.9% vs. 16.3%, P < 0.0001) and sight threatening DR (19.1% vs. 2.4%, P < 0.0001) in comparison to insulin nonusers. Among insulin users, longer duration of DM (odds ratio [OR] 1.12, 95% confidence interval [CI] 1.00–1.25, P = 0.044) and abdominal obesity (OR 1.15, 95% CI 1.02–1.29, P = 0.021) was associated with DR. The presence of DR was significantly associated with longer duration (≥5 years) prior to initiating insulin therapy, overall (38.0% vs. 62.0%, P = 0.013), and in subjects with suboptimal glycemic control (32.5% vs. 67.5%, P = 0.022). Conclusions: The presence of DR is significantly associated with longer duration of diabetes (>5 years) and sub-optimal glycemic control (glycosylated hemoglobin <7.0%). Among insulin users, abdominal obesity was found to be a significant predictor of DR; DR is associated with longer duration prior to initiating insulin therapy in Type 2 DM subjects with suboptimal glycemic control. PMID:27488152

  16. Modulation of adipocyte lipoprotein lipase expression as a strategy for preventing or treating visceral obesity.

    PubMed

    McCarty, M F

    2001-08-01

    As compared to subcutaneous adipocytes, visceral adipocytes have high basal lipolysis, are highly sensitive to catecholamines, and are poorly sensitive to insulin; these traits are amplified when visceral adipocytes hypertrophy. As a result, enlarged visceral fat stores tend to flood the portal circulation with free fatty acids at metabolically inappropriate times when fatty acids are unlikely to be oxidized, thus exposing tissues to excessive free fatty acid levels and giving rise to the insulin resistance syndrome. A logical approach to preventing or correcting visceral obesity is to down-regulate the lipoprotein lipase (LPL) activity of visceral adipocytes relative to that expressed in subcutaneous adipocytes and skeletal muscle. IGF-I activity appears to be a primary determinant of visceral LPL activity in humans; systemic IGF-I activity is decreased when diurnal insulin secretion is low, when hepatocytes detect a relative paucity of certain essential amino acids, and when estrogens are administered orally. The ability of alpha-glucosidase inhibitor therapy to selectively reduce visceral adiposity suggests that down-regulation of diurnal insulin secretion and/or IGF-I activity may indeed have a greater impact on LPL activity in visceral fat than in subcutaneous fat. Thus, low-glycemic-index, vegan, high-protein, or hypocaloric diets can be expected to decrease visceral LPL activity, as can postmenopausal estrogen therapy. Furthermore, estrogen enhances the LPL activity of non-pathogenic gluteofemoral fat cells, whereas testosterone decreases visceral LPL activity in men; this may explain why sex hormone replacement in middle-aged people of both sexes has a favorable impact on visceral fat and insulin sensitivity. Beta-adrenergic activity suppresses transcription of LPL in adipocytes; this phenomenon may contribute to the favorable impact of exercise training on visceral obesity; conceivably, preadministration of safe drugs that boost catecholamine activity

  17. Decreased beige adipocyte number and mitochondrial respiration coincide with increased histone methyl transferase (G9a) and reduced FGF21 gene expression in Sprague Dawley rats fed prenatal low protein and postnatal high fat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have shown that protein malnutrition during fetal growth followed by postnatal high-fat diets results in a rapid increase in subcutaneous adipose tissue mass in the offspring contributing to development of obesity and insulin resistance. Recent studies have shown that the absence of a key transcr...

  18. Semisynthesis and biological activity of porcine [LeuB24]insulin and [LeuB25]insulin.

    PubMed Central

    Tager, H; Thomas, N; Assoian, R; Rubenstein, A; Saekow, M; Olefsky, J; Kaiser, E T

    1980-01-01

    Two analogs of porcine insulin with substitutions of leucine for phenylalanine in the COOH-terminal region of the insulin B chain have been prepared by a combination of solid-phase synthesis and semisynthesis. Solid-phase synthesis of the substituted octapeptides B23-B30 bearing the trifluoracetyl group on lysine-B29, enzymatic coupling of the octapeptides to bis(tertiary-butyloxycarbonyl)desoctapeptide insulin by trypsin, and deprotection of the corresponding adducts in formic acid and piperidine resulted in two insulin derivatives, one with leucine at position B24 and the other with leucine at position B25. These analogs had only about 10% and 1%, respectively, of the activity of porcine insulin in competing for the binding of [125I]iodoinsulin to both rat adipocytes and human IM-9 lymphocytes. The relative potencies of the analogs in stimulating glucose oxidation by rat adipocytes decreased in the order porcine insulin > [LeuB24]insulin > [LeuB25]insulin. However, at high concentrations both analogs had full agonists activity. Experiments in which the semisynthetic insulins were mixed with the native hormone showed that [LeuB24]insulin, but not [LeuB25]insulin, was an active antagonist of insulin action. These results suggest that the antagonistic activity of a human insulin variant having leucine at position B24 or B25 can be assigned to the molecule with the sequence Gly-Leu-Phe-Tyr (residues B23-B26) in its active site. Images PMID:6997872

  19. Lipodystrophy, Diabetes and Normal Serum Insulin in PPARγ-Deficient Neonatal Mice

    PubMed Central

    O’Donnell, Peter E.; Ye, Xiu Zhen; DeChellis, Melissa A.; Davis, Vannessa M.; Duan, Sheng Zhong; Mortensen, Richard M.; Milstone, David S.

    2016-01-01

    Peroxisome proliferator activated receptor gamma (PPARγ) is a pleiotropic ligand activated transcription factor that acts in several tissues to regulate adipocyte differentiation, lipid metabolism, insulin sensitivity and glucose homeostasis. PPARγ also regulates cardiomyocyte homeostasis and by virtue of its obligate role in placental development is required for embryonic survival. To determine the postnatal functions of PPARγ in vivo we studied globally deficient neonatal mice produced by epiblast-restricted elimination of PPARγ. PPARγ-rescued placentas support development of PPARγ-deficient embryos that are viable and born in near normal numbers. However, PPARγ-deficient neonatal mice show severe lipodystrophy, lipemia, hepatic steatosis with focal hepatitis, relative insulin deficiency and diabetes beginning soon after birth and culminating in failure to thrive and neonatal lethality between 4 and 10 days of age. These abnormalities are not observed with selective PPARγ2 deficiency or with deficiency restricted to hepatocytes, skeletal muscle, adipocytes, cardiomyocytes, endothelium or pancreatic beta cells. These observations suggest important but previously unappreciated functions for PPARγ1 in the neonatal period either alone or in combination with PPARγ2 in lipid metabolism, glucose homeostasis and insulin sensitivity. PMID:27505464

  20. Leptin Production by Encapsulated Adipocytes Increases Brown Fat, Decreases Resistin, and Improves Glucose Intolerance in Obese Mice

    PubMed Central

    DiSilvestro, David J.; Melgar-Bermudez, Emiliano; Yasmeen, Rumana; Fadda, Paolo; Lee, L. James; Kalyanasundaram, Anuradha; Gilor, Chen L.; Ziouzenkova, Ouliana

    2016-01-01

    The neuroendocrine effects of leptin on metabolism hold promise to be translated into a complementary therapy to traditional insulin therapy for diabetes and obesity. However, injections of leptin can provoke inflammation. We tested the effects of leptin, produced in the physiological adipocyte location, on metabolism in mouse models of genetic and dietary obesity. We generated 3T3-L1 adipocytes constitutively secreting leptin and encapsulated them in a poly-L-lysine membrane, which protects the cells from immune rejection. Ob/ob mice (OB) were injected with capsules containing no cells (empty, OB[Emp]), adipocytes (OB[3T3]), or adipocytes overexpressing leptin (OB[Lep]) into both visceral fat depots. Leptin was found in the plasma of OB[Lep], but not OB[Emp] and OB[3T3] mice at the end of treatment (72 days). The OB[Lep] and OB[3T3] mice have transiently suppressed appetite and weight loss compared to OB[Emp]. Only OB[Lep] mice have greater brown fat mass, metabolic rate, and reduced resistin plasma levels compared to OB[Emp]. Glucose tolerance was markedly better in OB[Lep] vs. OB[Emp] and OB[3T3] mice as well as in wild type mice with high-fat diet-induced obesity and insulin resistance treated with encapsulated leptin-producing adipocytes. Our proof-of-principle study provides evidence of long-term improvement of glucose tolerance with encapsulated adipocytes producing leptin. PMID:27055280

  1. p75 neurotrophin receptor regulates glucose homeostasis and insulin sensitivity

    PubMed Central

    Baeza-Raja, Bernat; Li, Pingping; Le Moan, Natacha; Sachs, Benjamin D.; Schachtrup, Christian; Davalos, Dimitrios; Vagena, Eirini; Bridges, Dave; Kim, Choel; Saltiel, Alan R.; Olefsky, Jerrold M.; Akassoglou, Katerina

    2012-01-01

    Insulin resistance is a key factor in the etiology of type 2 diabetes. Insulin-stimulated glucose uptake is mediated by the glucose transporter 4 (GLUT4), which is expressed mainly in skeletal muscle and adipose tissue. Insulin-stimulated translocation of GLUT4 from its intracellular compartment to the plasma membrane is regulated by small guanosine triphosphate hydrolases (GTPases) and is essential for the maintenance of normal glucose homeostasis. Here we show that the p75 neurotrophin receptor (p75NTR) is a regulator of glucose uptake and insulin resistance. p75NTR knockout mice show increased insulin sensitivity on normal chow diet, independent of changes in body weight. Euglycemic-hyperinsulinemic clamp studies demonstrate that deletion of the p75NTR gene increases the insulin-stimulated glucose disposal rate and suppression of hepatic glucose production. Genetic depletion or shRNA knockdown of p75NTR in adipocytes or myoblasts increases insulin-stimulated glucose uptake and GLUT4 translocation. Conversely, overexpression of p75NTR in adipocytes decreases insulin-stimulated glucose transport. In adipocytes, p75NTR forms a complex with the Rab5 family GTPases Rab5 and Rab31 that regulate GLUT4 trafficking. Rab5 and Rab31 directly interact with p75NTR primarily via helix 4 of the p75NTR death domain. Adipocytes from p75NTR knockout mice show increased Rab5 and decreased Rab31 activities, and dominant negative Rab5 rescues the increase in glucose uptake seen in p75NTR knockout adipocytes. Our results identify p75NTR as a unique player in glucose metabolism and suggest that signaling from p75NTR to Rab5 family GTPases may represent a unique therapeutic target for insulin resistance and diabetes. PMID:22460790

  2. Short-term HFD does not alter lipolytic function of adipocytes

    PubMed Central

    Wiedemann, Michael SF; Wueest, Stephan; Grob, Alexandra; Item, Flurin; Schoenle, Eugen J; Konrad, Daniel

    2014-01-01

    A short bout of high fat diet (HFD) impairs glucose tolerance and hepatic insulin sensitivity. We recently identified adipose tissue inflammation and resulting dysfunctional adipose tissue–liver cross-talk as an early event in the development of HFD-induced hepatic insulin resistance. In particular, reducing white adipose tissue (WAT) inflammation by adipocyte-specific depletion of Fas/CD95 protected mice from developing hepatic insulin resistance but not hepatic steatosis. Herein, we expanded our previous work and determined the impact of four days of HFD on lipolytic activity of isolated adipocytes. Compared with chow-fed mice, the degree of basal and isoproterenol-stimulated free fatty acid (FFA) and glycerol release was similar in HFD-fed animals. Moreover, insulin’s ability to suppress lipolysis remained intact, suggesting retained insulin sensitivity. Despite unaltered lipolysis, circulating FFA concentrations were greatly increased in non-fasted HFD-fed mice. In conclusion, a short-term HFD challenge does not affect lipolytic function of adipocytes. The observed increase of circulating FFA levels in randomly fed animals may rather be the result of increased dietary fat supply. PMID:24719784

  3. TSH effects on thermogenesis in rat brown adipocytes.

    PubMed

    Martinez-deMena, Raquel; Anedda, Andrea; Cadenas, Susana; Obregon, Maria-Jesus

    2015-03-15

    TSH receptor (TSHR) is present in the thyroid and other tissues, as adipose tissue. In brown adipose tissue (BAT) TSH increases UCP1 expression and lipolysis. We have studied the regulation of Tshr mRNA expression and the effect of TSH on Ucp1 and Dio2 mRNA, on D2 activity and O2 consumption in rat brown adipocytes and the TSH signaling pathways. Tshr increased during brown adipocyte differentiation, was up-regulated by insulin and low TSH concentrations and down-regulated by high TSH concentrations, T3 and/or NE. TSH increased basal Ucp1 mRNA in a dose-dependent way acting synergistically with T3, while had no effect when NE was present. High TSH concentrations increased basal Dio2 mRNA (12-fold) and were synergistic with T3 (100-fold), but decreased Dio2 mRNA in T3+NE-treated cells. TSH increased D2 activities in T3-treated cells and inhibition of ERK pathway decreased the TSH effect by 55%. In T3+NE treated-cells TSH decreased D2 activity by 50%, in a dose-dependent manner. TSH activated Akt and Erk phosphorylation, while inhibition of PKA promoted Akt phosphorylation. TSH inhibited leptin mRNA. TSH increased O2 consumption by 20% and T3 enhanced its effect. Tshr is expressed in brown adipocytes and is regulated by insulin, TSH, T3 and NE. TSH increases basal and T3-stimulated Ucp1 and Dio2 expression and D2 activity only when T3 is present, but decreases Dio2 mRNA and D2 activity stimulated by NE+T3. TSH increases O2 consumption, confirming the role of TSH in the maintenance of thermogenesis.

  4. Increased extracellular and intracellular Ca{sup 2+} lead to adipocyte accumulation in bone marrow stromal cells by different mechanisms

    SciTech Connect

    Hashimoto, Ryota; Katoh, Youichi; Miyamoto, Yuki; Itoh, Seigo; Daida, Hiroyuki; Nakazato, Yuji; Okada, Takao

    2015-02-20

    Mesenchymal stem cells found in bone marrow stromal cells (BMSCs) are the common progenitors for both adipocyte and osteoblast. An increase in marrow adipogenesis is associated with age-related osteopenia and anemia. Both extracellular and intracellular Ca{sup 2+} ([Ca{sup 2+}]{sub o} and [Ca{sup 2+}]{sub i}) are versatile signaling molecules that are involved in the regulation of cell functions, including proliferation and differentiation. We have recently reported that upon treatment of BMSCs with insulin and dexamethasone, both high [Ca{sup 2+}]{sub o} and high [Ca{sup 2+}]{sub i} enhanced adipocyte accumulation, which suggested that increases in [Ca{sup 2+}]{sub o} caused by bone resorption may accelerate adipocyte accumulation in aging and diabetic patients. In this study, we used primary mouse BMSCs to investigate the mechanisms by which high [Ca{sup 2+}]{sub o} and high [Ca{sup 2+}]{sub i} may enhance adipocyte accumulation. In the process of adipocyte accumulation, two important keys are adipocyte differentiation and the proliferation of BMSCs, which have the potential to differentiate into adipocytes. Use of MTT assay and real-time RT-PCR revealed that high [Ca{sup 2+}]{sub i} (ionomycin)-dependent adipocyte accumulation is caused by enhanced proliferation of BMSCs but not enhanced differentiation into adipocytes. Using fura-2 fluorescence-based approaches, we showed that high [Ca{sup 2+}]{sub o} (addition of CaCl{sub 2}) leads to increases in [Ca{sup 2+}]{sub i}. Flow cytometric methods revealed that high [Ca{sup 2+}]{sub o} suppressed the phosphorylation of ERK independently of intracellular Ca{sup 2+}. The inhibition of ERK by U0126 and PD0325901 enhanced the differentiation of BMSCs into adipocytes. These data suggest that increased extracellular Ca{sup 2+} provides the differentiation of BMSCs into adipocytes by the suppression of ERK activity independently of increased intracellular Ca{sup 2+}, which results in BMSC proliferation. - Highlights:

  5. Pmch-deficiency in rats is associated with normal adipocyte differentiation and lower sympathetic adipose drive.

    PubMed

    Mul, Joram D; O'Duibhir, Eoghan; Shrestha, Yogendra B; Koppen, Arjen; Vargoviç, Peter; Toonen, Pim W; Zarebidaki, Eleen; Kvetnansky, Richard; Kalkhoven, Eric; Cuppen, Edwin; Bartness, Timothy J

    2013-01-01

    The orexigenic neuropeptide melanin-concentrating hormone (MCH), a product of Pmch, is an important mediator of energy homeostasis. Pmch-deficient rodents are lean and smaller, characterized by lower food intake, body-, and fat mass. Pmch is expressed in hypothalamic neurons that ultimately are components in the sympathetic nervous system (SNS) drive to white and interscapular brown adipose tissue (WAT, iBAT, respectively). MCH binds to MCH receptor 1 (MCH1R), which is present on adipocytes. Currently it is unknown if Pmch-ablation changes adipocyte differentiation or sympathetic adipose drive. Using Pmch-deficient and wild-type rats on a standard low-fat diet, we analyzed dorsal subcutaneous and perirenal WAT mass and adipocyte morphology (size and number) throughout development, and indices of sympathetic activation in WAT and iBAT during adulthood. Moreover, using an in vitro approach we investigated the ability of MCH to modulate 3T3-L1 adipocyte differentiation. Pmch-deficiency decreased dorsal subcutaneous and perirenal WAT mass by reducing adipocyte size, but not number. In line with this, in vitro 3T3-L1 adipocyte differentiation was unaffected by MCH. Finally, adult Pmch-deficient rats had lower norepinephrine turnover (an index of sympathetic adipose drive) in WAT and iBAT than wild-type rats. Collectively, our data indicate that MCH/MCH1R-pathway does not modify adipocyte differentiation, whereas Pmch-deficiency in laboratory rats lowers adiposity throughout development and sympathetic adipose drive during adulthood.

  6. Berberine activates GLUT1-mediated glucose uptake in 3T3-L1 adipocytes.

    PubMed

    Kim, So Hui; Shin, Eun-Jung; Kim, Eun-Do; Bayaraa, Tsenguun; Frost, Susan Cooke; Hyun, Chang-Kee

    2007-11-01

    It has recently been known that berberine, an alkaloid of medicinal plants, has anti-hyperglycemic effects. To explore the mechanism underlying this effect, we used 3T3-L1 adipocytes for analyzing the signaling pathways that contribute to glucose transport. Treatment of berberine to 3T3-L1 adipocytes for 6 h enhanced basal glucose uptake both in normal and in insulin-resistant state, but the insulin-stimulated glucose uptake was not augmented significantly. Inhibition of phosphatidylinositol 3-kinase (PI 3-K) by wortmannin did not affect the berberine effect on basal glucose uptake. Berberine did not augment tyrosine phosphorylation of insulin receptor (IR) and insulin receptor substrate (IRS)-1. Further, berberine had no effect on the activity of the insulin-sensitive downstream kinase, atypical protein kinase C (PKCzeta/lambda). However, interestingly, extracellular signal-regulated kinases (ERKs), which have been known to be responsible for the expression of glucose transporter (GLUT)1, were significantly activated in berberine-treated 3T3-L1 cells. As expected, the level of GLUT1 protein was increased both in normal and insulin-resistant cells in response to berberine. But berberine affected the expression of GLUT4 neither in normal nor in insulin-resistant cells. In addition, berberine treatment increased AMP-activated protein kinase (AMPK) activity in 3T3-L1 cells, which has been reported to be associated with GLUT1-mediated glucose uptake. Together, we concluded that berberine increases glucose transport activity of 3T3-L1 adipocytes by enhancing GLUT1 expression and also stimulates the GLUT1-mediated glucose uptake by activating GLUT1, a result of AMPK stimulation.

  7. Di-(2-Ethylhexyl)-Phthalate (DEHP) Causes Impaired Adipocyte Function and Alters Serum Metabolites

    PubMed Central

    Klöting, Nora; Hesselbarth, Nico; Gericke, Martin; Kunath, Anne; Biemann, Ronald; Chakaroun, Rima; Kosacka, Joanna; Kovacs, Peter; Kern, Matthias; Stumvoll, Michael; Fischer, Bernd; Rolle-Kampczyk, Ulrike; Feltens, Ralph; Otto, Wolfgang; Wissenbach, Dirk K.; von Bergen, Martin; Blüher, Matthias

    2015-01-01

    Di-(2-ethylhexyl)-phthalate (DEHP), an ubiquitous environmental contaminant, has been shown to cause adverse effects on glucose homeostasis and insulin sensitivity in epidemiological studies, but the underlying mechanisms are still unknown. We therefore tested the hypothesis that chronic DEHP exposure causes impaired insulin sensitivity, affects body weight, adipose tissue (AT) function and circulating metabolic parameters of obesity resistant 129S6 mice in vivo. An obesity-resistant mouse model was chosen to reduce a potential obesity bias of DEHP effects on metabolic parameters and AT function. The metabolic effects of 10-weeks exposure to DEHP were tested by insulin tolerance tests and quantitative assessment of 183 metabolites in mice. Furthermore, 3T3-L1 cells were cultured with DEHP for two days, differentiated into mature adipocytes in which the effects on insulin stimulated glucose and palmitate uptake, lipid content as well as on mRNA/protein expression of key adipocyte genes were investigated. We observed in female mice that DEHP treatment causes enhanced weight gain, fat mass, impaired insulin tolerance, changes in circulating adiponectin and adipose tissue Pparg, adiponectin and estrogen expression. Serum metabolomics indicated a general increase in phospholipid and carnitine concentrations. In vitro, DEHP treatment increases the proliferation rate and alters glucose uptake in adipocytes. Taken together, DEHP has significant effects on adipose tissue (AT) function and alters specific serum metabolites. Although, DEHP treatment led to significantly impaired insulin tolerance, it did not affect glucose tolerance, HOMA-IR, fasting glucose, insulin or triglyceride serum concentrations. This may suggest that DEHP treatment does not cause impaired glucose metabolism at the whole body level. PMID:26630026

  8. Interferon inhibits the conversion of 3T3-L1 mouse fibroblasts into adipocytes.

    PubMed Central

    Keay, S; Grossberg, S E

    1980-01-01

    Confluent Swiss mouse 3T3-L1 fibroblasts slowly differentiate functionally and morphologically into adipocytes, a conversion hastened by insulin. The cells are sensitive (although less than L929 cells) to the antiviral action of mouse fibroblast interferons but not to interferons from heterologous species (human and chicken). Cultures stimulated with insulin in the presence of partially purified or electrophoretically pure mouse interferons have a much lower percentage of cells accumulating lipid than do insulin-treated control cultures. Interferon-treated cell cultures also contain much less triglyceride, cholesterol, and cholesterol esters than do replicate control cultures stimulated by insulin to differentiate. Increased de novo lipid biosynthesis that occurs during differentiation is inhibited, as determined by incorporation of [14C]acetate into lipids extractable by the Folch method. This incorporation is a sensitive bioassay of the antidifferentiation effect of interferon; less than 1 antiviral unit is inhibitory. Variously inactivated or mock interferon preparations as well as interferons from several heterologous species fail to inhibit 3T3-L1 adipocyte conversion. Interferon is inhibitory even when applied as long as 3 days after insulin stimulation. The effect of interferon does not appear to depend upon its competition with insulin for cell surface receptors. Because interferon can alter the program of events involved in conversion of 3T3-L1 fibroblasts into adipose cells, it may be able to affect the regulation of eukaryotic cell differentiation. Images PMID:6159626

  9. Dexamethasone and rosiglitazone are sufficient and necessary for producing functional adipocytes from mesenchymal stem cells.

    PubMed

    Contador, David; Ezquer, Fernando; Espinosa, Maximiliano; Arango-Rodriguez, Martha; Puebla, Carlos; Sobrevia, Luis; Conget, Paulette

    2015-09-01

    The final product of adipogenesis is a functional adipocyte. This mature cell acquires the necessary machinery for lipid metabolism, loses its proliferation potential, increases its insulin sensitivity, and secretes adipokines. Multipotent mesechymal stromal cells have been recognized as a source of adipocytes both in vivo and in vitro. The in vitro adipogenic differentiation of human MSC (hMSC) has been induced up to now by using a complex stimulus which includes dexamethasone, 3-isobutyl-1-methylxanthine, indomethacin, and insulin (a classical cocktail) and evaluated according to morphological changes. The present work was aimed at demonstrating that the simultaneous activation of dexamethasone's canonical signaling pathways, through the glucocorticoid receptor and CCAAT-enhancer-binding proteins (C/EBPs) and rosiglitazone through peroxisome proliferator-activated receptor gamma (PPAR-gamma) is sufficient yet necessary for inducing hMSC adipogenic differentiation. It was also ascertained that hMSC exposed just to dexamethasone and rosiglitazone (D&R) differentiated into cells which accumulated neutral lipid droplets, expressed C/EBP-alpha, PPAR-gamma, aP2, lipoprotein lipase, acyl-CoA synthetase, phosphoenolpyruvate carboxykinase, adiponectin, and leptin genes but did not proliferate. Glucose uptake was dose dependent on insulin stimulus and high levels of adipokines were secreted (i.e. displaying not only the morphology but also expressing mature adipocytes' specific genes and functional characteristics). This work has demonstrated that (i) the activating C/EBPs and PPAR-gamma signaling pathways were sufficient to induce adipogenic differentiation from hMSC, (ii) D&R producing functional adipocytes from hMSC, (iii) D&R induce adipogenic differentiation from mammalian MSC (including those which are refractory to classical adipogenic differentiation stimuli). D&R would thus seem to be a useful tool for MSC characterization, studying adipogenesis pathways and

  10. Oral Insulin Reloaded

    PubMed Central

    Heinemann, Lutz; Plum-Mörschel, Leona

    2014-01-01

    Optimal coverage of insulin needs is the paramount aim of insulin replacement therapy in patients with diabetes mellitus. To apply insulin without breaking the skin barrier by a needle and/or to allow a more physiological provision of insulin are the main reasons triggering the continuous search for alternative routes of insulin administration. Despite numerous attempts over the past 9 decades to develop an insulin pill, no insulin for oral dosing is commercially available. By way of a structured approach, we aim to provide a systematic update on the most recent developments toward an orally available insulin formulation with a clear focus on data from clinical-experimental and clinical studies. Thirteen companies that claim to be working on oral insulin formulations were identified. However, only 6 of these companies published new clinical trial results within the past 5 years. Interestingly, these clinical data reports make up a mere 4% of the considerably high total number of publications on the development of oral insulin formulations within this time period. While this picture clearly reflects the rising research interest in orally bioavailable insulin formulations, it also highlights the fact that the lion’s share of research efforts is still allocated to the preclinical stages. PMID:24876606

  11. Biosimilar Insulin and Costs

    PubMed Central

    Heinemann, Lutz

    2015-01-01

    The costs for insulin treatment are high, and the steady increase in the number of patients with diabetes on insulin presents a true challenge to health care systems. Therefore, all measures to lower these costs are welcomed by patients, physicians, and health care providers. The market introduction of biosimilar insulins presents an option to lower treatment costs as biosimilars are usually offered at a lower price than the originator product. However, the assumption that a drastic reduction in insulin prices will take place, as was observed with many generic drugs, is most probably not realistic. As the first biosimilar insulin has now been approved in the EU, this commentary discusses a number of aspects that are relevant when it comes to the potential cost reduction we will see with the use of biosimilar insulins. PMID:26350722

  12. Polyacetylenes from carrots (Daucus carota) improve glucose uptake in vitro in adipocytes and myotubes.

    PubMed

    El-Houri, Rime B; Kotowska, Dorota; Christensen, Kathrine B; Bhattacharya, Sumangala; Oksbjerg, Niels; Wolber, Gerhard; Kristiansen, Karsten; Christensen, Lars P

    2015-07-01

    A dichloromethane (DCM) extract of carrot roots was found to stimulate insulin-dependent glucose uptake (GU) in adipocytes in a dose dependent manner. Bioassay-guided fractionation of the DCM extract resulted in the isolation of the polyacetylenes falcarinol and falcarindiol. Both polyacetylenes were able to significantly stimulate basal and/or insulin-dependent GU in 3T3-L1 adipocytes and porcine myotube cell cultures in a dose-dependent manner. Falcarindiol increased peroxisome proliferator-activated receptor (PPAR)γ-mediated transactivation significantly at concentrations of 3, 10 and 30 μM, while PPARγ-mediated transactivation by falcarinol was only observed at 10 μM. Docking studies accordingly indicated that falcarindiol binds to the ligand binding domain of PPARγ with higher affinity than falcarinol and that both polyacetylenes exhibit characteristics of PPARγ partial agonists. Falcarinol was shown to inhibit adipocyte differentiation as evident by gene expression studies and Oil Red O staining, whereas falcarindiol did not inhibit adipocyte differentiation, which indicates that these polyacetylenes have distinct modes of action. The results of the present study suggest that falcarinol and falcarindiol may represent scaffolds for novel partial PPARγ agonists with possible antidiabetic properties.

  13. Cirsium japonicum flavones enhance adipocyte differentiation and glucose uptake in 3T3-L1 cells.

    PubMed

    Liao, Zhiyong; Wu, Zhihua; Wu, Mingjiang

    2012-01-01

    Cirsium japonicum flavones have been demonstrated to possess anti-diabetic effects in diabetic rats, but the functional mechanism remains unknown. The nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) plays an important role in glucose and lipid homeostasis. In this study, we report the effects of Cirsium japonicum flavones (pectolinarin and 5,7-dihydroxy-6,4-dimethoxy flavone) on PPARγ activation, adipocyte differentiation, and glucose uptake in 3T3-L1 cells. Reporter gene assays and Oil Red O staining showed that Cirsium japonicum flavones induced PPARγ activation and enhanced adipocyte differentiation of 3T3-L1 cells in a dose-dependent manner. In addition, Cirsium japonicum flavones increased the expression of PPARγ target genes, such as adiponectin and glucose transporter 4 (GLUT4), and enhanced the translocation of intracellular GLUT4 to the plasma membrane. In mature 3T3-L1 adipocytes, Cirsium japonicum flavones significantly enhanced the basal and insulin-stimulated glucose uptake. The flavones-induced effects in 3T3-L1 cells were abolished by the PPARγ antagonist, GW9662, and by the phosphatidylinositol 3-kinase (PI3K) inhibitor, wortmannin. This study suggests that Cirsium japonicum flavones promote adipocyte differentiation and glucose uptake by inducing PPARγ activation and then modulating the insulin signaling pathway in some way, which could benefit diabetes patients.

  14. ReishiMax, mushroom based dietary supplement, inhibits adipocyte differentiation, stimulates glucose uptake and activates AMPK

    PubMed Central

    2011-01-01

    Background Obesity is a health hazard which is closely associated with various complications including insulin resistance, hypertension, dyslipidemia, atherosclerosis, type 2 diabetes and cancer. In spite of numerous preclinical and clinical interventions, the prevalence of obesity and its related disorders are on the rise demanding an urgent need for exploring novel therapeutic agents that can regulate adipogenesis. In the present study, we evaluated whether a dietary supplement ReishiMax (RM), containing triterpenes and polysaccharides extracted from medicinal mushroom Ganoderma lucidum, affects adipocyte differentiation and glucose uptake in 3T3-L1 cells. Methods 3T3-L1 pre-adipocytes were differentiated into adipocytes and treated with RM (0-300 μg/ml). Adipocyte differentiation/lipid uptake was evaluated by oil red O staining and triglyceride and glycerol concentrations were determined. Gene expression was evaluated by semi-quantitative RT-PCR and Western blot analysis. Glucose uptake was determined with [3H]-glucose. Results RM inhibited adipocyte differentiation through the suppresion of expression of adipogenic transcription factors peroxisome proliferator-activated receptor-γ (PPAR-γ), sterol regulatory element binding element protein-1c (SREBP-1c) and CCAAT/enhancer binding protein-α (C/EBP-α). RM also suppressed expression of enzymes and proteins responsible for lipid synthesis, transport and storage: fatty acid synthase (FAS), acyl-CoA synthetase-1 (ACS1), fatty acid binding protein-4 (FABP4), fatty acid transport protein-1 (FATP1) and perilipin. RM induced AMP-activated protein kinase (AMPK) and increased glucose uptake by adipocytes. Conclusion Our study suggests that RM can control adipocyte differentiation and glucose uptake. The health benefits of ReishiMax warrant further clinical studies. PMID:21929808

  15. Omentum and bone marrow: how adipocyte-rich organs create tumour microenvironments conducive for metastatic progression

    PubMed Central

    Gusky, H. Chkourko; Diedrich, J.; MacDougald, O. A.; Podgorski, I.

    2016-01-01

    Summary A number of clinical studies have linked adiposity with increased cancer incidence, progression and metastasis, and adipose tissue is now being credited with both systemic and local effects on tumour development and survival. Adipocytes, a major component of benign adipose tissue, represent a significant source of lipids, cytokines and adipokines, and their presence in the tumour microenvironment substantially affects cellular trafficking, signalling and metabolism. Cancers that have a high predisposition to metastasize to the adipocyte-rich host organs are likely to be particularly affected by the presence of adipocytes. Although our understanding of how adipocytes influence tumour progression has grown significantly over the last several years, the mechanisms by which adipocytes regulate the meta-static niche are not well-understood. In this review, we focus on the omentum, a visceral white adipose tissue depot, and the bone, a depot for marrow adipose tissue, as two distinct adipocyte-rich organs that share common characteristic: they are both sites of significant metastatic growth. We highlight major differences in origin and function of each of these adipose depots and reveal potential common characteristics that make them environments that are attractive and conducive to secondary tumour growth. Special attention is given to how omental and marrow adipocytes modulate the tumour microenvironment by promoting angiogenesis, affecting immune cells and altering metabolism to support growth and survival of metastatic cancer cells. PMID:27432523

  16. Comprehensive proteomic data sets for studying adipocyte-macrophage cell-cell communication.

    PubMed

    Freiwald, Anja; Weidner, Christopher; Witzke, Annabell; Huang, Sheng-Yu; Meierhofer, David; Sauer, Sascha

    2013-12-01

    Cellular communication is a fundamental process in biology. The interaction of adipocytes with macrophages is a key event in the development of common diseases such as type 2 diabetes. We applied an established bilayer cell co-culture system and comprehensive mass spectrometry analysis to detect proteome-wide the paracrine interaction of murine adipocytes and macrophages. Altogether, we identified 4486 proteins with at least two unique peptides of which 2392 proteins were informative for 3T3-L1 adipocytes and 2957 proteins for RAW 264.7 macrophages. Further, we observed over 12,000 phosphorylation sites of which we could assign 3,200 informative phosphopeptides with a single phosphosite for adipocytes and 4,514 for macrophages. Using protein set enrichment and phosphosite analyses, we deciphered regulatory protein pathways involved in cellular stress and inflammation, which can contribute to metabolic impairment of cells including insulin resistance and other disorders. The generated data sets provide a holistic, molecular pathway-centric view on the interplay of adipocytes and macrophages in disease processes and a resource for further studies.

  17. miR-146a-mediated suppression of the inflammatory response in human adipocytes

    PubMed Central

    Roos, Julian; Enlund, Eveliina; Funcke, Jan-Bernd; Tews, Daniel; Holzmann, Karlheinz; Debatin, Klaus-Michael; Wabitsch, Martin; Fischer-Posovszky, Pamela

    2016-01-01

    The obesity-associated inflammation of white adipose tissue (WAT) is one of the factors leading to the development of related diseases such as insulin resistance and liver steatosis. Recently, microRNAs (miRNAs) were identified as important regulators of WAT functions. Herein, we cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes with macrophage-conditioned medium (MacCM) and performed an Affimetrix miRNA array to identify miRNAs differentially expressed under inflammatory conditions. We identified 24 miRNAs differentially expressed upon inflammation in human adipocytes and miR-146a was the most up-regulated miRNA species. In subcutaneous WAT, miR-146a was elevated in both human and murine obesity. Transfection of miR-146a mimics prevented the MacCM-induced inflammatory response in SGBS adipocytes as seen by reduced levels of IL-8 and MCP-1 mRNA and protein. We identified IRAK1 and TRAF6 as targets of miR-146a in human adipocytes and detected a reduced inflammation-induced activation of JNK and p38 upon miR-146a transfection. Taken together, we could show that miR-146a reduces the inflammatory response in human adipocytes. In a negative feedback loop miR-146a might contribute to the regulation of inflammatory processes in WAT and possibly prevent an overwhelming inflammatory response. PMID:27922090

  18. Pioglitazone increases secretion of high-molecular-weight adiponectin from adipocytes.

    PubMed

    Bodles, Angela M; Banga, Anannya; Rasouli, Neda; Ono, Fumiyo; Kern, Philip A; Owens, Randall J

    2006-11-01

    Adiponectin is an adipocyte-derived serum protein that plays important roles in energy homeostasis, obesity, and insulin sensitivity. Using sucrose gradients and Western blotting of nondenaturing gels, we examined the adiponectin isoforms secreted from human adipose tissue, human and mouse adipocytes, and cell lines in response to pioglitazone added in vitro. The predominant form secreted from adipose tissue in vitro was the high-molecular-weight (HMW) isoform, with small amounts of low-molecular-weight (LMW) forms present. The addition of pioglitazone (1-3 micromM) in vitro increased the secretion of the HMW isoform, with no significant effect on the other isoforms. Human adipose tissue was also examined for changes in adiponectin mRNA levels upon pioglitazone treatment. No difference was detected, suggesting that the effect of pioglitazone is not at the transcriptional level but, rather, at a posttranscriptional phase of the secretory pathway. Additional experiments were conducted to determine whether adiponectin expression was mechanistically similar in other adipose cells. Examination of primary human adipocytes revealed an increase in intracellular HMW isoform with a decline in LMW forms following pioglitazone treatment, with a corresponding increase in the secreted HMW form. Similar results were observed with primary mouse adipocytes, 3T3-F422A cells, and SGBS human adipocyte cells, although differences in the distribution of HMW and LMW isoforms were apparent between cell types. Although there are differences in isoforms between species, in all cases pioglitazone served to increase the secretion of the HMW form of adiponectin.

  19. Endoplasmic reticulum stress suppresses lipin-1 expression in 3T3-L1 adipocytes

    SciTech Connect

    Takahashi, Nobuhiko; Hiranaka, Natsumi; Suzuki, Takeshi; Yui, Tomoo; Akanuma, Masayoshi; Kanazawa, Kaoru; Yoshida, Mika; Naito, Sumiyoshi; Fujiya, Mikihiro; Kohgo, Yutaka

    2013-02-01

    Highlights: ► Lipin-1 involves lipid metabolism, adipocyte differentiation, and inflammation. ► Adipose lipin-1 expression is reduced in obesity. ► ER stress suppresses lipin-1 expression in 3T3-L1 adipocytes. ► Activation of PPAR-γ recovers ER stress-induced lipin-1 reduction. -- Abstract: Lipin-1 plays crucial roles in the regulation of lipid metabolism and cell differentiation in adipocytes. In obesity, adipose lipin-1 mRNA expression is decreased and positively correlated with systemic insulin sensitivity. Amelioration of the lipin-1 depletion might be improved dysmetabolism. Although some cytokines such as TNF-α and interleukin-1β reduces adipose lipin-1 expression, the mechanism of decreased adipose lipin-1 expression in obesity remains unclear. Recently, endoplasmic reticulum (ER) stress is implicated in the pathogenesis of obesity. Here we investigated the role of ER stress on the lipin-1 expression in 3T3-L1 adipocytes. We demonstrated that lipin-1 expression was suppressed by the treatment with ER stress inducers (tunicamycin and thapsigargin) at transcriptional level. We also showed that constitutive lipin-1 expression could be maintained by peroxisome proliferator-activated receptor-γ in 3T3-L1 adipocytes. Activation of peroxisome proliferator-activated receptor-γ recovered the ER stress-induced lipin-1 suppression. These results suggested that ER stress might be involved in the pathogenesis of obesity through lipin-1 depletion.

  20. Effects of androgens on insulin action in women: is androgen excess a component of female metabolic syndrome?

    PubMed

    Corbould, A

    2008-10-01

    Hyperinsulinemia as a consequence of insulin resistance causes hyperandrogenemia in women. The objective was to review evidence for the converse situation, i.e. whether androgens adversely influence insulin action. Androgen excess could potentially contribute to the pathogenesis of insulin resistance in women with polycystic ovary syndrome (PCOS), metabolic syndrome/type 2 diabetes, and in obese peripubertal girls. An Entrez-PubMed search was conducted to identify studies addressing the relationship of androgens with metabolic syndrome/type 2 diabetes in women. Studies reporting outcomes of androgen administration, interventions to reduce androgen effects in hyperandrogenemic women, and basic studies investigating androgen effects on insulin target tissues were reviewed. Multiple studies showed associations between serum testosterone and insulin resistance or metabolic syndrome/type 2 diabetes risk in women, but their cross-sectional nature did not allow conclusions about causality. Androgen administration to healthy women was associated with development of insulin resistance. Intervention studies in women with hyperandrogenism were limited by small subject numbers and use of indirect methods for assessing insulin sensitivity. However, in three of the seven studies using euglycemic hyperinsulinemic clamps, reduction of androgen levels or blockade of androgen action improved insulin sensitivity. Testosterone administration to female rats caused skeletal muscle insulin resistance. Testosterone induced insulin resistance in adipocytes of women in vitro. In conclusion, the metabolic consequences of androgen excess in women have been under-researched. Studies of long-term interventions that lower androgen levels or block androgen effects in young women with hyperandrogenism are needed to determine whether these might protect against metabolic syndrome/type 2 diabetes in later life.

  1. The Role of PDE3B Phosphorylation in the Inhibition of Lipolysis by Insulin

    PubMed Central

    DiPilato, Lisa M.; Ahmad, Faiyaz; Harms, Matthew; Seale, Patrick; Manganiello, Vincent

    2015-01-01

    Inhibition of adipocyte lipolysis by insulin is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance and type 2 diabetes mellitus. The main target of the antilipolytic action of insulin is believed to be phosphodiesterase 3B (PDE3B), whose phosphorylation by Akt leads to accelerated degradation of the prolipolytic second messenger cyclic AMP (cAMP). To test this hypothesis genetically, brown adipocytes lacking PDE3B were examined for their regulation of lipolysis. In Pde3b knockout (KO) adipocytes, insulin was unable to suppress β-adrenergic receptor-stimulated glycerol release. Reexpressing wild-type PDE3B in KO adipocytes fully rescued the action of insulin against lipolysis. Surprisingly, a mutant form of PDE3B that ablates the major Akt phosphorylation site, murine S273, also restored the ability of insulin to suppress lipolysis. Taken together, these data suggest that phosphorylation of PDE3B by Akt is not required for insulin to suppress adipocyte lipolysis. PMID:26031333

  2. Insulin Basics

    MedlinePlus

    ... long insulin continues to lower blood glucose. Insulin Strength All insulins come dissolved or suspended in liquids. The standard and most commonly used strength in the United States today is U-100, ...

  3. Diabetes: insulin resistance and derangements in lipid metabolism. Cure through intervention in fat transport and storage.

    PubMed

    Raz, Itamar; Eldor, Roi; Cernea, Simona; Shafrir, Eleazar

    2005-01-01

    We present multiple findings on derangements in lipid metabolism in type 2 diabetes. The increase in the intracellular deposition of triglycerides (TG) in muscles, liver and pancreas in subjects prone to diabetes is well documented and demonstrated to attenuate glucose metabolism by interfering with insulin signaling and insulin secretion. The obesity often associated with type 2 diabetes is mainly central, resulting in the overload of abdominal adipocytes with TG and reducing fat depot capacity to protect other tissues from utilizing a large proportion of dietary fat. In contrast to subcutaneous adipocytes, the central adipocytes exhibit a high rate of basal lipolysis and are highly sensitive to fat mobilizing hormones, but respond poorly to lipolysis restraining insulin. The enlarged visceral adipocytes are flooding the portal circulation with free fatty acids (FFA) at metabolically inappropriate time, when FFA should be oxidized, thus exposing nonadipose tissues to fat excess. This leads to ectopic TG accumulation in muscles, liver and pancreatic beta-cells, resulting in insulin resistance and beta-cell dysfunction. This situation, based on a large number of observations in humans and experimental animals, confirms that peripheral adipose tissue is closely regulated, performing a vital role of buffering fluxes of FFA in the circulation. The central adipose tissues tend to upset this balance by releasing large amounts of FFA. To reduce the excessive fat outflow from the abdominal depots and prevent the ectopic fat deposition it is important to decrease the volume of central fat stores or increase the peripheral fat stores. One possibility is to downregulate the activity of lipoprotein lipase, which is overexpressed in abdominal relatively to subcutaneous fat stores. This can be achieved by gastrointestinal bypass or gastroplasty, which decrease dietary fat absorption, or by direct means that include surgical removal of mesenteric fat. Indirect treatment consists

  4. Adipocyte is a non-trivial, dynamic partner of breast cancer cells.

    PubMed

    Tan, Jinxiang; Buache, Emilie; Chenard, Marie-Pierre; Dali-Youcef, Nassim; Rio, Marie-Christine

    2011-01-01

    While the participation of adipocytes is well known in tissue architecture, energy supply and endocrine processes, their implication during natural cancer history is just beginning to unfold. An extensive review of the literature concerning the impact of resident adipocytes on breast cancer development/progression was performed. This review provides in vitro and in vivo evidence that adipocytes located close to invasive cancer cells, referred to as cancer-associated adipocytes (CAAs), are essential for breast tumor development/progression. Their deleterious function is dependent, at least partly, on their crosstalk with invasive cancer cells. Indeed, this event leads to dramatic phenotypic and/or functional modifications of both cell types. Adipocytes exhibit delipidation and acquire a fibroblast-like shape. In parallel, cancer cell aggressiveness is exacerbated through increased migratory and invasive properties. Moreover, obesity is currently a sign of poor prognosis in human carcinomas. In this context, a high number of "obese" resident adipocytes might be predicted to be detrimental. Accordingly, there are some similarities between the molecular alterations observed in hypertrophied adipocytes and in CAAs. How adipocytes function to favor tumorigenesis at the molecular level remains largely unknown. Nevertheless, progress has been made recently and molecular clues are starting to emerge. Deciphering the cellular and molecular mechanisms behind the adipocyte-cancer cell heterotypic crosstalk is of great interest since it might provide new targets for improving diagnosis/prognosis and for the design of innovative therapeutic strategies. They might also improve our understanding of the relationship between obesity/metabolic disorders and cancer risk and/or poor patient outcome.

  5. Adipogenesis and insulin sensitivity in obesity are regulated by retinoid-related orphan receptor gamma

    PubMed Central

    Meissburger, Bettina; Ukropec, Jozef; Roeder, Eva; Beaton, Nigel; Geiger, Matthias; Teupser, Daniel; Civan, Burcak; Langhans, Wolfgang; Nawroth, Peter P; Gasperikova, Daniela; Rudofsky, Gottfried; Wolfrum, Christian

    2011-01-01

    Obesity is a well-known risk factor for the development of secondary complications such as type 2 diabetes. However, only a part of the obese population develops secondary metabolic disorders. Here, we identify the transcription factor retinoid-related orphan receptor gamma (RORγ) as a negative regulator of adipocyte differentiation through expression of its newly identified target gene matrix metalloproteinase 3. In vivo differentiation of adipocyte progenitor cells from Rorγ-deficient mice is enhanced and obese Rorγ−/− mice show decreased adipocyte sizes. These small adipocytes are highly insulin sensitive, leading to an improved control of circulating free fatty acids. Ultimately, Rorγ−/− mice are protected from hyperglycemia and insulin resistance in the state of obesity. In adipose stromal-vascular fraction from obese human subjects, Rorγ expression is correlated with adipocyte size and negatively correlated with adipogenesis and insulin sensitivity. Taken together, our findings identify RORγ as a factor, which controls adipogenesis as well as adipocyte size and modulates insulin sensitivity in obesity. RORγ might therefore serve as a novel pharmaceutical target to treat obesity-associated insulin resistance. PMID:21853531

  6. Role of sialic acid in insulin action and the insulin resistance of diabetes mellitus

    SciTech Connect

    Salhanick, A.I.; Amatruda, J.M. )

    1988-08-01

    Adipocytes treated with neuraminidase show markedly reduced responsiveness to insulin without any alteration in insulin binding. In addition, several studies have separately demonstrated both insulin resistance and decreases in membrane sialic acid content and associated biosynthetic enzymes in diabetes mellitus. In the present study, the authors investigated the role that sialic acid residues may play in insulin action and in the hepatic insulin resistance associated with nonketotic diabetes. Primary cultures of hepatocytes from normal rats treated with neuraminidase demonstrated a dose-dependent decrease in insulin-stimulated lipogenesis. At a concentration of neuraminidase that decreases insulin action by 50%, 23% of total cellular sialic acid content was released. Neuraminidase-releasable sialic acid was significantly decreased in hepatocytes from diabetic rats and this was associated with significant insulin resistance. Treatment of hepatocytes from diabetic rats with cytidine 5{prime}-monophospho-N-acetylneuraminic acid (CMP-NANA) enhanced insulin responsiveness 39%. The enhanced insulin responsiveness induced by CMP-NANA was blocked by cytidine 5{prime}-monophosphate (CMP) suggesting that the CMP-NANA effect was catalyzed by a cell surface sialyl-transferase. CMP reduced neuraminidase-releasable ({sup 14}C)sialic acid incorporation into hepatocytes by 43%. The data demonstrate a role for cell surface sialic acid residues in hepatic insulin action and support a role for decreased cell surface sialic acid residues in the insulin resistance of diabetes mellitus.

  7. Macadamia Oil Supplementation Attenuates Inflammation and Adipocyte Hypertrophy in Obese Mice

    PubMed Central

    Lima, Edson A.; Silveira, Loreana S.; Masi, Laureane N.; Crisma, Amanda R.; Davanso, Mariana R.; Souza, Gabriel I. G.; Santamarina, Aline B.; Moreira, Renata G.; Roque Martins, Amanda; de Sousa, Luis Gustavo O.; Hirabara, Sandro M.; Rosa Neto, Jose C.

    2014-01-01

    Excess of saturated fatty acids in the diet has been associated with obesity, leading to systemic disruption of insulin signaling, glucose intolerance, and inflammation. Macadamia oil administration has been shown to improve lipid profile in humans. We evaluated the effect of macadamia oil supplementation on insulin sensitivity, inflammation, lipid profile, and adipocyte size in high-fat diet (HF) induced obesity in mice. C57BL/6 male mice (8 weeks) were divided into four groups: (a) control diet (CD), (b) HF, (c) CD supplemented with macadamia oil by gavage at 2 g/Kg of body weight, three times per week, for 12 weeks (CD + MO), and (d) HF diet supplemented with macadamia oil (HF + MO). CD and HF mice were supplemented with water. HF mice showed hypercholesterolemia and decreased insulin sensitivity as also previously shown. HF induced inflammation in adipose tissue and peritoneal macrophages, as well as adipocyte hypertrophy. Macadamia oil supplementation attenuated hypertrophy of adipocytes and inflammation in the adipose tissue and macrophages. PMID:25332517

  8. Fat accumulation in differentiated brown adipocytes is linked with expression of Hox genes.

    PubMed

    Singh, Smita; Rajput, Yudhishthir S; Barui, Amit K; Sharma, Rajan; Datta, Tirtha K

    2016-03-01

    Homeobox (Hox) genes are involved in body plan of embryo along the anterior-posterior axis. Presence of several Hox genes in white adipose tissue (WAT) and brown adipose tissue (BAT) is indicative of involvement of Hox genes in adipogenesis. We propose that differentiation inducing agents viz. isobutyl-methyl-xanthine (IBMX), indomethacin, dexamethasone (DEX), triiodothyronine (T3) and insulin may regulate differentiation in brown adipose tissue through Hox genes. In vitro culture of brown fat stromalvascular fraction (SVF) in presence or absence of differentiation inducing agents was used for establishing relationship between fat accumulation in differentiated adipocytes and expression of Hox genes. Relative expression of Pref1, UCP1 and Hox genes was determined in different stages of adipogenesis. Presence or absence of IBMX, indomethacin and DEX during differentiation of proliferated pre-adipocytes resulted in marked differences in expression of Hox genes and lipid accumulation. In presence of these inducing agents, lipid accumulation as well as expression of HoxA1, HoxA5, HoxC4 &HoxC8 markedly enhanced. Irrespective of presence or absence of T3, insulin down regulates HoxA10. T3 results in over expression of HoxA5, HoxC4 and HoxC8 genes, whereas insulin up regulates expression of only HoxC8. Findings suggest that accumulation of fat in differentiated adipocytes is linked with expression of Hox genes.

  9. Kinin B1 Receptor in Adipocytes Regulates Glucose Tolerance and Predisposition to Obesity

    PubMed Central

    Motta, Fabiana Louise; Fonseca, Raphael Gomes; Alenina, Natalia; Guadagnini, Dioze; Schadock, Ines; Silva, Elton Dias; Torres, Hugo A. M.; dos Santos, Edson Lucas; Castro, Charlles Heldan; D’Almeida, Vânia; Andreotti, Sandra; Campaña, Amanda Baron; Sertié, Rogério A. L.; Saad, Mario J. A.; Lima, Fabio Bessa; Bader, Michael; Pesquero, João Bosco

    2012-01-01

    Background Kinins participate in the pathophysiology of obesity and type 2 diabetes by mechanisms which are not fully understood. Kinin B1 receptor knockout mice (B1−/−) are leaner and exhibit improved insulin sensitivity. Methodology/Principal Findings Here we show that kinin B1 receptors in adipocytes play a role in controlling whole body insulin action and glucose homeostasis. Adipocytes isolated from mouse white adipose tissue (WAT) constitutively express kinin B1 receptors. In these cells, treatment with the B1 receptor agonist des-Arg9-bradykinin improved insulin signaling, GLUT4 translocation, and glucose uptake. Adipocytes from B1−/− mice showed reduced GLUT4 expression and impaired glucose uptake at both basal and insulin-stimulated states. To investigate the consequences of these phenomena to whole body metabolism, we generated mice where the expression of the kinin B1 receptor was limited to cells of the adipose tissue (aP2-B1/B1−/−). Similarly to B1−/− mice, aP2-B1/B1−/− mice were leaner than wild type controls. However, exclusive expression of the kinin B1 receptor in adipose tissue completely rescued the improved systemic insulin sensitivity phenotype of B1−/− mice. Adipose tissue gene expression analysis also revealed that genes involved in insulin signaling were significantly affected by the presence of the kinin B1 receptor in adipose tissue. In agreement, GLUT4 expression and glucose uptake were increased in fat tissue of aP2-B1/B1−/− when compared to B1−/− mice. When subjected to high fat diet, aP2-B1/B1−/− mice gained more weight than B1−/− littermates, becoming as obese as the wild types. Conclusions/Significance Thus, kinin B1 receptor participates in the modulation of insulin action in adipocytes, contributing to systemic insulin sensitivity and predisposition to obesity. PMID:23024762

  10. Activation of AMPK by berberine promotes adiponectin multimerization in 3T3-L1 adipocytes.

    PubMed

    Li, Yun; Wang, Pengcheng; Zhuang, Yuan; Lin, Huan; Li, Yehua; Liu, Ling; Meng, Qinghang; Cui, Ting; Liu, Jing; Li, Zhen

    2011-06-23

    Adiponectin is assembled into trimer (LMW), hexamer (MMW) and high-molecular-weight (HMW) multimer in adipocytes. The HMW adiponectin is more metabolically active and closely associated with peripheral insulin sensitivity. In this study, we reported that berberine, an isoquinoline alkaloid with insulin-sensitizing effect, inhibits the expression of adiponectin, but promotes the assembly of HMW adiponectin and increases the ratio of HMW to total adiponectin. Berberine activates AMPK. Knockdown of AMPKα1 abolishes the effect of berberine. Activation of AMPK by AICAR also increases the level of HMW adiponectin. Our study suggested that activation of AMPK by berberine promotes adiponectin multimerization.

  11. Progeny from dedifferentiated adipocytes display protracted adipogenesis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Progeny of adipofibroblast cells, derived from mature bovine adipocytes, were used to determine their ability to redifferentiate into lipid-assimilating adipocytes. Traditional cell biology methods were used, including the expression of adipogenic markers such as PPAR'. When exposed to medium supple...

  12. Evidence of early alterations in adipose tissue biology and function and its association with obesity-related inflammation and insulin resistance in children.

    PubMed

    Landgraf, Kathrin; Rockstroh, Denise; Wagner, Isabel V; Weise, Sebastian; Tauscher, Roy; Schwartze, Julian T; Löffler, Dennis; Bühligen, Ulf; Wojan, Magdalena; Till, Holger; Kratzsch, Jürgen; Kiess, Wieland; Blüher, Matthias; Körner, Antje

    2015-04-01

    Accumulation of fat mass in obesity may result from hypertrophy and/or hyperplasia and is frequently associated with adipose tissue (AT) dysfunction in adults. Here we assessed early alterations in AT biology and function by comprehensive experimental and clinical characterization of 171 AT samples from lean and obese children aged 0 to 18 years. We show an increase in adipocyte size and number in obese compared with lean children beginning in early childhood. These alterations in AT composition in obese children were accompanied by decreased basal lipolytic activity and significantly enhanced stromal vascular cell proliferation in vitro, potentially underlying the hypertrophy and hyperplasia seen in obese children, respectively. Furthermore, macrophage infiltration, including the formation of crown-like structures, was increased in AT of obese children from 6 years on and was associated with higher hs-CRP serum levels. Clinically, adipocyte hypertrophy was not only associated with leptin serum levels but was highly and independently correlated with HOMA-IR as a marker of insulin resistance in children. In summary, we show that adipocyte hypertrophy is linked to increased inflammation in AT in obese children, thereby providing evidence that obesity-associated AT dysfunction develops in early childhood and is related to insulin resistance.

  13. Skin aging: are adipocytes the next target?

    PubMed Central

    Kruglikov, Ilja L.; Scherer, Philipp E.

    2016-01-01

    Dermal white adipose tissue (dWAT) is increasingly appreciated as a special fat depot. The adipocytes in this depot exert a variety of unique effects on their surrounding cells and can undergo massive phenotypic changes. Significant modulation of dWAT content can be observed both in intrinsically and extrinsically aged skin. Specifically, skin that has been chronically photo-damaged displays a reduction of the dWAT volume, caused by the replacement of adipocytes by fibrotic structures. This is likely to be caused by the recently uncovered process described as “adipocyte-myofibroblast transition” (AMT). In addition, contributions of dermal adipocytes to the skin aging processes are also indirectly supported by spatial correlations between the prevalence of hypertrophic scarring and the appearance of signs of skin aging in different ethnic groups. These observations could elevate dermal adipocytes to prime targets in strategies aimed at counteracting skin aging. PMID:27434510

  14. Mitochondria in White, Brown, and Beige Adipocytes

    PubMed Central

    Cedikova, Miroslava; Kripnerová, Michaela; Dvorakova, Jana; Pitule, Pavel; Grundmanova, Martina; Babuska, Vaclav; Mullerova, Dana; Kuncova, Jitka

    2016-01-01

    Mitochondria play a key role in energy metabolism in many tissues, including cardiac and skeletal muscle, brain, liver, and adipose tissue. Three types of adipose depots can be identified in mammals, commonly classified according to their colour appearance: the white (WAT), the brown (BAT), and the beige/brite/brown-like (bAT) adipose tissues. WAT is mainly involved in the storage and mobilization of energy and BAT is predominantly responsible for nonshivering thermogenesis. Recent data suggest that adipocyte mitochondria might play an important role in the development of obesity through defects in mitochondrial lipogenesis and lipolysis, regulation of adipocyte differentiation, apoptosis, production of oxygen radicals, efficiency of oxidative phosphorylation, and regulation of conversion of white adipocytes into brown-like adipocytes. This review summarizes the main characteristics of each adipose tissue subtype and describes morphological and functional modifications focusing on mitochondria and their activity in healthy and unhealthy adipocytes. PMID:27073398

  15. Basal insulin: beyond glycemia.

    PubMed

    Niswender, Kevin D

    2011-07-01

    Insulin is a pleiotropic hormone with numerous effects at the cellular, tissue, and organismal levels. Clinicians are familiar with physiological effects of insulin on carbohydrate metabolism, including stimulation of glucose uptake in skeletal muscle and the suppression of glucose production from the liver. Other metabolic effects of insulin include inhibiting the release of free fatty acids from adipose tissue and stimulating the incorporation of amino acids into proteins. Indeed, every organ in the body, including the brain, is a target for insulin action. Insulin resistance, typically defined with respect to glucose metabolism, is a condition in which normal levels of insulin do not trigger the signal for glucose disposition. The effects of insulin resistance and impaired insulin signaling have profound pathophysiologic effects, such as hyperglycemia-induced tissue damage, hypertension, dyslipidemia, metabolic syndrome, and cardiovascular and renal disease. An integrated view of insulin action in all of these tissues may yield improved therapeutic insight and possibly even illuminate new therapeutic opportunities. With the increase in the number of patients diagnosed with prediabetes and diabetes, an updated understanding of the disease and the pharmacologic armamentarium used to treat it is needed to improve outcomes. To help expand the clinical care provider's perspective, this article will provide a provocative discussion about the pathophysiology of diabetes, the role of insulin and insulin resistance, and the clinical efficacy potential of insulin. Understanding the cellular and molecular mechanisms underlying the effects of insulin and how these translate into clinical consequences beyond glycemia will assist primary care physicians in the care of their patients with diabetes and metabolic syndrome.

  16. Berberine inhibits PTP1B activity and mimics insulin action.

    PubMed

    Chen, Chunhua; Zhang, Yuebo; Huang, Cheng

    2010-07-02

    Type 2 diabetes patients show defects in insulin signal transduction that include lack of insulin receptor, decrease in insulin stimulated receptor tyrosine kinase activity and receptor-mediated phosphorylation of insulin receptor substrates (IRSs). A small molecule that could target insulin signaling would be of significant advantage in the treatment of diabetes. Berberine (BBR) has recently been shown to lower blood glucose levels and to improve insulin resistance in db/db mice partly through the activation of AMP-activated protein kinase (AMPK) signaling and induction of phosphorylation of insulin receptor (IR). However, the underlying mechanism remains largely unknown. Here we report that BBR mimics insulin action by increasing glucose uptake ability by 3T3-L1 adipocytes and L6 myocytes in an insulin-independent manner, inhibiting phosphatase activity of protein tyrosine phosphatase 1B (PTP1B), and increasing phosphorylation of IR, IRS1 and Akt in 3T3-L1 adipocytes. In diabetic mice, BBR lowers hyperglycemia and improves impaired glucose tolerance, but does not increase insulin release and synthesis. The results suggest that BBR represents a different class of anti-hyperglycemic agents.

  17. Adipocyte (Pro)Renin-Receptor Deficiency Induces Lipodystrophy, Liver Steatosis and Increases Blood Pressure in Male Mice.

    PubMed

    Wu, Chia-Hua; Mohammadmoradi, Shayan; Thompson, Joel; Su, Wen; Gong, Ming; Nguyen, Genevieve; Yiannikouris, Frédérique

    2016-07-01

    Adipose tissue dysfunction related to obesity is overwhelmingly associated with increased risk of developing cardiovascular diseases. In the setting of obesity, (pro)renin receptor (PRR) is increased in adipose tissue of mice. We sought to determine the physiological consequences of adipocyte-PRR deficiency using adiponectin-Cre mice. We report a unique model of adipocyte-PRR-deficient mice (PRR(Adi/Y)) with almost no detectable white adipose tissues. As a consequence, the livers of PRR(Adi/Y) mice were enlarged and demonstrated a marked accumulation of lipids. Adipocyte-specific deficiency of PRR increased systolic blood pressure and the concentration of soluble PRR in plasma. To determine whether adipocyte-PRR was involved in the development of obesity-induced hypertension, mice were fed a low-fat or a high-fat diet for 16 weeks. Adipocyte-PRR-deficient mice were resistant to diet-induced obesity. Both high-fat- and low-fat-fed PRR(Adi/Y) mice had elevated insulin levels. Interestingly, adipocyte-PRR deficiency improved glucose tolerance in high-fat-fed PRR(Adi/Y) mice. In response to feeding either low-fat or high-fat diets, systolic blood pressure was greater in PRR(Adi/Y) mice than in control mice. High-fat feeding elevated soluble PRR concentration in control and PRR(Adi/Y) mice. In vitro knockdown of PRR by siRNA significantly decreased mRNA abundance of PPARγ (peroxisome proliferator-activated receptor gamma), suggesting an important role for PRR in adipogenesis. Our data indicate that adipocyte-PRR is involved in lipid homeostasis and glucose and insulin homeostasis, and that soluble PRR may be a predictor of metabolic disturbances and play a role in systolic blood pressure regulation.

  18. Inhibition of mitotic clonal expansion mediates fisetin-exerted prevention of adipocyte differentiation in 3T3-L1 cells.

    PubMed

    Lee, Youngyi; Bae, Eun Ju

    2013-11-01

    Adipocytes are the key player in adipose tissue inflammation and subsequent systemic insulin resistance and its development involves complex process of proliferation and differentiation of preadipocytes. Fistein, a polyphenol flavonoid, is known to exert anti-inflammatory, anti-carcinogenic and anti-diabetic effects. In this study, we aimed to investigate the effect of fisetin on adipocyte proliferation and differentiation in 3T3-L1 preadipocyte cell line and its mechanism of action. We found that fisetin inhibits adipocyte differentiation in a concentration dependent manner, which were evidenced by Oil Red O staining and the protein expression of mature adipocyte marker genes fatty acid synthase and peroxisome proliferator-activated receptor γ. Moreover, the proliferation of preadipocytes was also markedly suppressed by treatment of fisetin for 24 and 48 h in the differentiation medium. We also found that fisetin inhibition of adipocyte differentiation was largely due to the effect on mitotic clonal expansion. Fisetin suppression of preadipocyte proliferation at early stage of differentiation was accompanied by the changes of expression of a series of cell cycle regulatory proteins. Altogether, our results suggest that the inhibition of adipocyte differentiation by fisetin may be at least in part mediated by cell cycle arrest during adipogenesis.

  19. Suppression of lipin-1 expression increases monocyte chemoattractant protein-1 expression in 3T3-L1 adipocytes

    SciTech Connect

    Takahashi, Nobuhiko; Hiranaka, Natsumi; Suzuki, Takeshi; Yui, Tomoo; Akanuma, Masayasu; Oka, Kazuya; Kanazawa, Kaoru; Yoshida, Mika; Naito, Sumiyoshi; Fujiya, Mikihiro; Kohgo, Yutaka

    2011-11-11

    Highlights: Black-Right-Pointing-Pointer Lipin-1 affects lipid metabolism, adipocyte differentiation, and transcription. Black-Right-Pointing-Pointer Adipose lipin-1 expression is reduced in obesity. Black-Right-Pointing-Pointer Lipin-1 depletion using siRNA in 3T3-L1 adipocytes increased MCP-1 expression. Black-Right-Pointing-Pointer Lipin-1 is involved in adipose inflammation. -- Abstract: Lipin-1 plays a crucial role in the regulation of lipid metabolism and cell differentiation in adipocytes. Expression of adipose lipin-1 is reduced in obesity, and metabolic syndrome. However, the significance of this reduction remains unclear. This study investigated if and how reduced lipin-1 expression affected metabolism. We assessed mRNA expression levels of various genes related to adipocyte metabolism in lipin-1-depleted 3T3-L1 adipocytes by introducing its specific small interfering RNA. In lipin-1-depleted adipocytes, mRNA and protein expression levels of monocyte chemoattractant protein-1 (MCP-1) were significantly increased, although the other genes tested were not altered. The conditioned media from the cells promoted monocyte chemotaxis. The increase in MCP-1 expression was prevented by treatment with quinazoline or salicylate, inhibitors of nuclear factor-{kappa}B activation. Because MCP-1 is related to adipose inflammation and systemic insulin resistance, these results suggest that a reduction in adipose lipin-1 in obesity may exacerbate adipose inflammation and metabolism.

  20. Coprinus comatus Cap Inhibits Adipocyte Differentiation via Regulation of PPARγ and Akt Signaling Pathway

    PubMed Central

    Jang, Sun-Hee; Kang, Suk Nam; Jeon, Beong-Sam; Ko, Yeoung-Gyu; Kim, Hong-Duck; Won, Chung-Kil; Kim, Gon-Sup; Cho, Jae-Hyeon

    2014-01-01

    This study assessed the effects of Coprinus comatus cap (CCC) on adipogenesis in 3T3-L1 adipocytes and the effects of CCC on the development of diet-induced obesity in rats. Here, we showed that the CCC has an inhibitory effect on the adipocyte differentiation of 3T3-L1 cells, resulting in a significant decrease in lipid accumulation through the downregulation of several adipocyte specific-transcription factors, including CCAAT/enhancer binding protein β, C/EBPδ, and peroxisome proliferator-activated receptor gamma (PPARγ). Moreover, treatment with CCC during adipocyte differentiation induced a significant down-regulation of PPARγ and adipogenic target genes, including adipocyte protein 2, lipoprotein lipase, and adiponectin. Interestingly, the CCC treatment of the 3T3-L1 adipocytes suppressed the insulin-stimulated Akt and GSK3β phosphorylation, and these effects were stronger in the presence of an inhibitor of Akt phosphorylation, LY294002, suggesting that CCC inhibited adipocyte differentiation through the down-regulation of Akt signaling. In the animal study, CCC administration significantly reduced the body weight and adipose tissue weight of rats fed a high fat diet (HFD) and attenuated lipid accumulation in the adipose tissues of the HFD-induced obese rats. The size of the adipocyte in the epididymal fat of the CCC fed rats was significantly smaller than in the HFD rats. CCC treatment significantly reduced the total cholesterol and triglyceride levels in the serum of HFD rats. These results strongly indicated that the CCC-mediated decrease in body weight was due to a reduction in adipose tissue mass. The expression level of PPARγ and phospho-Akt was significantly lower in the CCC-treated HFD rats than that in the HFD obesity rats. These results suggested that CCC inhibited adipocyte differentiation by the down-regulation of major transcription factor involved in the adipogenesis pathway including PPARγ through the regulation of the Akt pathway in 3T3

  1. Fetuin-A downregulates adiponectin through Wnt-PPARγ pathway in lipid induced inflamed adipocyte.

    PubMed

    Agarwal, Soumik; Chattopadhyay, Mrittika; Mukherjee, Sandip; Dasgupta, Suman; Mukhopadhyay, Satinath; Bhattacharya, Samir

    2017-01-01

    Adiponectin secreted from adipocytes is an anti-diabetic and anti-atherogenic adipokine. Adiponectin level is known to fall significantly in obesity induced type 2 diabetes which worsen insulin sensitivity because of aberrant lipid management. However, underlying mechanism of adiponectin decrease in obese diabetic condition is yet unclear. We report here that lowering of plasma adiponectin coincided with the higher Fetuin A (FetA) level in high fat diet (HFD) induced obese diabetic mice. Knock down of FetA gene (FetA(KD)) elevated adiponectin level markedly in HFD mice, while reinforcement of FetA into FetA(KD)HFD mice reduced its level again. These results indicate FetA's involvement in the lowering of adiponectin level in obesity induced diabetic mice. Our findings to understand how FetA could affect adiponectin decrease demonstrated that FetA could enhance Wnt3a expression in the adipocyte of HFD mice. FetA addition to 3T3L1 adipocyte incubation elevated Wnt3a expression in a dose dependent manner. Overexpression of Wnt3a by FetA inhibited PPARγ and adiponectin. FetA failed to reduce PPARγ and adiponectin in Wnt3a gene knocked down 3T3L1` adipocytes. All these suggest that FetA mediate its inhibitory effect on adiponectin through Wnt3a-PPARγ pathway. Inhibition of adiponectin expression through FetA and Wnt3a significantly compromised with the activation of AMPK and its downstream signalling molecules which adversely affected lipid management causing loss of insulin sensitivity. Downregulation of adiponectin in inflamed adipocyte by FetA through the mediation of Wnt3a and PPARγ is a new report.

  2. Differentiation of Pre-Adipocytes in Modelled Microgravity

    NASA Astrophysics Data System (ADS)

    Coinu, R.; Postiglione, I.; Meloni, M. A.; Galleri, G.; Pippia, P.; Palumbo, G.

    2008-06-01

    It has been demonstrated that microgravity affects biological and biochemical functions of cells including: morphology, cytoskeleton and embryogenesis [1]; proliferation, reduction of DNA, protein synthesis and glucose transport [2]; signalling, reduction of EGF-dependant c-fos and c-jun expression [3]; gene expression, reduction of IL2 expression and release by activated T-cells [4]. Moreover it has be found that peroxisome proliferators activated receptor γ (PPARγ2), which is known to be important for adipocyte differentiation, adipsin, leptin, and glucose transporter-4, are highly expressed in response to modelled microgravity [5]. These findings prompted us to investigate the effects of microgravity on cellular differentiation rate using a well characterized model. Such model consists in murine pre-adipocyte cells (3T3-L1) properly stimulated with insulin, dexamethazone and isobuthylmethyl-xantine (DMI protocol). The adipogenic program is completed within a short time. The entire process requires coordinated and temporarily beated molecular events. Early events. Growth arrest at confluence; Clonal expansion (this process involves synchronous entry of cells into S phase of the cell cycle, leading to one or two rounds of mitosis); Early expression of C/EBPβ and C/EBPδ. Late events. Expression of PPARγ and C/EBPα Assumption of rounded morphology and accumulation of lipid droplets.

  3. Insulin-independent role of adiponectin receptor signaling in Drosophila germline stem cell maintenance.

    PubMed

    Laws, Kaitlin M; Sampson, Leesa L; Drummond-Barbosa, Daniela

    2015-03-15

    Adipocytes have key endocrine roles, mediated in large part by secreted protein hormones termed adipokines. The adipokine adiponectin is well known for its role in sensitizing peripheral tissues to insulin, and several lines of evidence suggest that adiponectin might also modulate stem cells/precursors. It remains unclear, however, how adiponectin signaling controls stem cells and whether this role is secondary to its insulin-sensitizing effects or distinct. Drosophila adipocytes also function as an endocrine organ and, although no obvious adiponectin homolog has been identified, Drosophila AdipoR encodes a well-conserved homolog of mammalian adiponectin receptors. Here, we generate a null AdipoR allele and use clonal analysis to demonstrate an intrinsic requirement for AdipoR in germline stem cell (GSC) maintenance in the Drosophila ovary. AdipoR null GSCs are not fully responsive to bone morphogenetic protein ligands from the niche and have a slight reduction in E-cadherin levels at the GSC-niche junction. Conversely, germline-specific overexpression of AdipoR inhibits natural GSC loss, suggesting that reduction in adiponectin signaling might contribute to the normal decline in GSC numbers observed over time in wild-type females. Surprisingly, AdipoR is not required for insulin sensitization of the germline, leading us to speculate that insulin sensitization is a more recently acquired function than stem cell regulation in the evolutionary history of adiponectin signaling. Our findings establish Drosophila female GSCs as a new system for future studies addressing the molecular mechanisms whereby adiponectin receptor signaling modulates stem cell fate.

  4. Identification of a Novel Function of Adipocyte Plasma Membrane-Associated Protein (APMAP) in Gestational Diabetes Mellitus by Proteomic Analysis of Omental Adipose Tissue.

    PubMed

    Ma, Yuhang; Gao, Jing; Yin, Jiajing; Gu, Liping; Liu, Xing; Chen, Su; Huang, Qianfang; Lu, Huifang; Yang, Yuemin; Zhou, Hu; Wang, Yufan; Peng, Yongde

    2016-02-05

    Gestational diabetes mellitus (GDM) is considered as an early stage of type 2 diabetes mellitus. In this study, we compared demographic and clinical data between six GDM subjects and six normal glucose tolerance (NGT; healthy controls) subjects and found that homeostasis model of assessment for insulin resistance index (HOMA-IR) increased in GDM. Many previous studies demonstrated that omental adipose tissue dysfunction could induce insulin resistance. Thus, to investigate the cause of insulin resistance in GDM, we used label-free proteomics to identify differentially expressed proteins in omental adipose tissues from GDM and NGT subjects (data are available via ProteomeXchange with identifier PXD003095). A total of 3528 proteins were identified, including 66 significantly changed proteins. Adipocyte plasma membrane-associated protein (APMAP, a.k.a. C20orf3), one of the differentially expressed proteins, was down-regulated in GDM omental adipose tissues. Furthermore, mature 3T3-L1 adipocytes were used to simulate omental adipocytes. The inhibition of APMAP expression by RNAi impaired insulin signaling and activated NFκB signaling in these adipocytes. Our study revealed that the down-regulation of APMAP in omental adipose tissue may play an important role in insulin resistance in the pathophysiology of GDM.

  5. Insulin stimulates the tyrosine phosphorylation of caveolin

    PubMed Central

    1995-01-01

    The specialized plasma membrane structures termed caveolae and the caveolar-coat protein caveolin are highly expressed in insulin- sensitive cells such as adipocytes and muscle. Stimulation of 3T3-L1 adipocytes with insulin significantly increased the tyrosine phosphorylation of caveolin and a 29-kD caveolin-associated protein in caveolin-enriched Triton-insoluble complexes. Maximal phosphorylation occurred within 5 min, and the levels of phosphorylation remained elevated for at least 30 min. The insulin-dose responses for the tyrosine phosphorylation of caveolin and the 29-kD caveolin-associated protein paralleled those for the phosphorylation of the insulin receptor. The stimulation of caveolin tyrosine phosphorylation was specific for insulin and was not observed with PDGF or EGF, although PDGF stimulated the tyrosine phosphorylation of the 29-kD caveolin- associated protein. Increased tyrosine phosphorylation of caveolin, its associated 29-kD protein, and a 60-kD protein was observed in an in vitro kinase assay after incubation of the caveolin-enriched Triton- insoluble complexes with Mg-ATP, suggesting the presence of an intrinsic tyrosine kinase in these complexes. These fractions contain only trace amounts of the activated insulin receptor. In addition, these complexes contain a 60-kD kinase detected in an in situ gel kinase assay and an approximately 60 kD protein that cross-reacts with an antibody against the Src-family kinase p59Fyn. Thus, the insulin- dependent tyrosine phosphorylation of caveolin represents a novel, insulin-specific signal transduction pathway that may involve activation of a tyrosine kinase downstream of the insulin receptor. PMID:7540611

  6. Insulin signaling and insulin resistance.

    PubMed

    Beale, Elmus G

    2013-01-01

    Insulin resistance or its sequelae may be the common etiology of maladies associated with metabolic syndrome (eg, hypertension, type 2 diabetes, atherosclerosis, heart attack, stroke, and kidney failure). It is thus important to understand those factors that affect insulin sensitivity. This review stems from the surprising discovery that interference with angiotensin signaling improves insulin sensitivity, and it provides a general overview of insulin action and factors that control insulin sensitivity.

  7. Resveratrol Metabolites Modify Adipokine Expression and Secretion in 3T3-L1 Pre-Adipocytes and Mature Adipocytes

    PubMed Central

    Eseberri, Itziar; Lasa, Arrate; Churruca, Itziar; Portillo, María P.

    2013-01-01

    Objective Due to the low bioavailability of resveratrol, determining whether its metabolites exert any beneficial effect is an interesting issue. Methods 3T3-L1 maturing pre-adipocytes were treated during differentiation with 25 µM of resveratrol or with its metabolites and 3T3-L1 mature adipocytes were treated for 24 hours with 10 µM resveratrol or its metabolites. The gene expression of adiponectin, leptin, visfatin and apelin was assessed by Real Time RT-PCR and their concentration in the incubation medium was quantified by ELISA. Results Resveratrol reduced mRNA levels of leptin and increased those of adiponectin. It induced the same changes in leptin secretion. Trans-resveratrol-3-O-glucuronide and trans-resveratrol-4′-O-glucuronide increased apelin and visfatin mRNA levels. Trans-resveratrol-3-O-sulfate reduced leptin mRNA levels and increased those of apelin and visfatin. Conclusions The present study shows for the first time that resveratrol metabolites have a regulatory effect on adipokine expression and secretion. Since resveratrol has been reported to reduce body-fat accumulation and to improve insulin sensitivity, and considering that these effects are mediated in part by changes in the analyzed adipokines, it may be proposed that resveratrol metabolites play a part in these beneficial effects of resveratrol. PMID:23717508

  8. White-to-brown metabolic conversion of human adipocytes by JAK inhibition

    PubMed Central

    Moisan, Annie; Lee, Youn-Kyoung; Zhang, Jitao David; Hudak, Carolyn S.; Meyer, Claas A.; Prummer, Michael; Zoffmann, Sannah; Truong, Hoa Hue; Ebeling, Martin; Kiialainen, Anna; Gérard, Régine; Xia, Fang; Schinzel, Robert T.; Amrein, Kurt E.; Cowan, Chad A.

    2014-01-01

    The rising incidence of obesity and related disorders such as diabetes and heart disease has focused considerable attention on the discovery of novel therapeutics. One promising approach has been to increase the number or activity of brown-like adipocytes in white adipose depots, as this has been shown to prevent diet-induced obesity and reduce the incidence and severity of type 2 diabetes. Thus, the conversion of fat-storing cells into metabolically active thermogenic cells has become an appealing therapeutic strategy to combat obesity. Here, we report a screening platform for the identification of small molecules capable of promoting a white-to-brown metabolic conversion in human adipocytes. We identified two inhibitors of Janus Kinase (JAK) activity with no precedent in adipose tissue biology that stably confer brown-like metabolic activity to white adipocytes. Importantly, these metabolically converted adipocytes exhibit elevated UCP1 expression and increased mitochondrial activity. We further found that repression of interferon signalling and activation of hedgehog signalling in JAK-inactivated adipocytes contributes to the metabolic conversion observed in these cells. Our findings highlight a novel role for the JAK/STAT pathway in the control of adipocyte function and establish a platform to identify compounds for the treatment of obesity. PMID:25487280

  9. Tea catechins modulate the glucose transport system in 3T3-L1 adipocytes.

    PubMed

    Ueda, Manabu; Furuyashiki, Takashi; Yamada, Kayo; Aoki, Yukiko; Sakane, Iwao; Fukuda, Itsuko; Yoshida, Ken-Ichi; Ashida, Hitoshi

    2010-11-01

    In this study, we investigated the effects of tea catechins on the translocation of glucose transporter (GLUT) 4 in 3T3-L1 adipocytes. We found that the ethyl acetate fraction of green tea extract, containing abundant catechins, most decreased insulin-induced glucose uptake activity in 3T3-L1 cells. When the cells were treated with 50 μM catechins in the absence or presence of insulin for 30 min, nongallate-type catechins increased glucose uptake activity without insulin, whereas gallate-type catechins decreased insulin-induced glucose uptake activity. (-)-Epicatechin (EC) and (-)-epigallocatechin (EGC), nongallate-type catechins, increased glucose uptake activity in the dose- and time-dependent manner, whereas (-)-catechin 3-gallate (Cg) and (-)-epigallocatechin 3-gallate (EGCg), gallate-type catechins, decreased insulin-induced glucose uptake activity in the dose- and time-dependent manner. When the cells were treated with 50 μM catechins for 30 min, EC and EGC promoted GLUT4 translocation, whereas Cg and EGCg decreased the insulin-induced translocation in the cells. EC and EGC increased phosphorylation of PKCλ/ζ without phosphorylation of insulin receptor (IR) and Akt. Wortmannin and LY294002, inhibitors for phosphatidylinositol 3'-kinase (PI3K), decreased EC- and EGC-induced glucose uptake activity in the cells. Cg and EGCg decreased phosphorylation of PKCλ/ζ in the presence of insulin without affecting insulin-induced phosphorylation of IR, and Akt. Therefore, EC and EGC promote the translocation of GLUT4 through activation of PI3K, and Cg and EGCg inhibit insulin-induced translocation of GLUT4 by the insulin signaling pathway in 3T3-L1 cells.

  10. Expression of adipocyte biomarkers in a primary cell culture models reflects preweaning adipobiology.

    PubMed

    Chu, Dinh-Toi; Malinowska, Elzbieta; Gawronska-Kozak, Barbara; Kozak, Leslie P

    2014-06-27

    A cohort of genes was selected to characterize the adipogenic phenotype in primary cell cultures from three tissue sources. We compared the quantitative expression of biomarkers in culture relative to their expression in vivo because the mere presence or absence of expression is minimally informative. Although all biomarkers analyzed have biochemical functions in adipocytes, the expression of some of the biomarkers varied enormously in culture relative to their expression in the adult fat tissues in vivo, i.e. inguinal fat for white adipocytes and brite cells, interscapular brown adipose tissue for brown adipocytes, and ear mesenchymal stem cells for white adipocytes from adult mice. We propose that the pattern of expression in vitro does not reflect gene expression in the adult mouse; rather it is predominantly the expression pattern of adipose tissue of the developing mouse between birth and weaning. The variation in gene expression among fat depots in both human and rodent has been an extensively studied phenomenon, and as recently reviewed, it is related to subphenotypes associated with immune function, the inflammatory response, fat depot blood flow, and insulin sensitivity. We suggest that adipose tissue biology in the period from birth to weaning is not just a staging platform for the emergence of adult white fat but that it has properties to serve the unique needs of energy metabolism in the newborn. A case in point is the differentiation of brite cells that occurs during this period followed by their involution immediately following weaning.

  11. Adipocyte fetuin-A contributes to macrophage migration into adipose tissue and polarization of macrophages.

    PubMed

    Chatterjee, Priyajit; Seal, Soma; Mukherjee, Sandip; Kundu, Rakesh; Mukherjee, Sutapa; Ray, Sukanta; Mukhopadhyay, Satinath; Majumdar, Subeer S; Bhattacharya, Samir

    2013-09-27

    Macrophage infiltration into adipose tissue during obesity and their phenotypic conversion from anti-inflammatory M2 to proinflammatory M1 subtype significantly contributes to develop a link between inflammation and insulin resistance; signaling molecule(s) for these events, however, remains poorly understood. We demonstrate here that excess lipid in the adipose tissue environment may trigger one such signal. Adipose tissue from obese diabetic db/db mice, high fat diet-fed mice, and obese diabetic patients showed significantly elevated fetuin-A (FetA) levels in respect to their controls; partially hepatectomized high fat diet mice did not show noticeable alteration, indicating adipose tissue to be the source of this alteration. In adipocytes, fatty acid induces FetA gene and protein expressions, resulting in its copious release. We found that FetA could act as a chemoattractant for macrophages. To simulate lipid-induced inflammatory conditions when proinflammatory adipose tissue and macrophages create a niche of an altered microenvironment, we set up a transculture system of macrophages and adipocytes; the addition of fatty acid to adipocytes released FetA into the medium, which polarized M2 macrophages to M1. This was further confirmed by direct FetA addition to macrophages. Taken together, lipid-induced FetA from adipocytes is an efficient chemokine for macrophage migration and polarization. These findings open a new dimension for understanding obesity-induced inflammation.

  12. Adipocyte Fetuin-A Contributes to Macrophage Migration into Adipose Tissue and Polarization of Macrophages*

    PubMed Central

    Chatterjee, Priyajit; Seal, Soma; Mukherjee, Sandip; Kundu, Rakesh; Mukherjee, Sutapa; Ray, Sukanta; Mukhopadhyay, Satinath; Majumdar, Subeer S.; Bhattacharya, Samir

    2013-01-01

    Macrophage infiltration into adipose tissue during obesity and their phenotypic conversion from anti-inflammatory M2 to proinflammatory M1 subtype significantly contributes to develop a link between inflammation and insulin resistance; signaling molecule(s) for these events, however, remains poorly understood. We demonstrate here that excess lipid in the adipose tissue environment may trigger one such signal. Adipose tissue from obese diabetic db/db mice, high fat diet-fed mice, and obese diabetic patients showed significantly elevated fetuin-A (FetA) levels in respect to their controls; partially hepatectomized high fat diet mice did not show noticeable alteration, indicating adipose tissue to be the source of this alteration. In adipocytes, fatty acid induces FetA gene and protein expressions, resulting in its copious release. We found that FetA could act as a chemoattractant for macrophages. To simulate lipid-induced inflammatory conditions when proinflammatory adipose tissue and macrophages create a niche of an altered microenvironment, we set up a transculture system of macrophages and adipocytes; the addition of fatty acid to adipocytes released FetA into the medium, which polarized M2 macrophages to M1. This was further confirmed by direct FetA addition to macrophages. Taken together, lipid-induced FetA from adipocytes is an efficient chemokine for macrophage migration and polarization. These findings open a new dimension for understanding obesity-induced inflammation. PMID:23943623

  13. Inhibitory effect of naringenin chalcone on inflammatory changes in the interaction between adipocytes and macrophages.

    PubMed

    Hirai, Shizuka; Kim, Young-Il; Goto, Tsuyoshi; Kang, Min-Sook; Yoshimura, Mineka; Obata, Akio; Yu, Rina; Kawada, Teruo

    2007-09-29

    Obese adipose tissue is characterized by an enhanced infiltration of macrophages. It is considered that the paracrine loop involving monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-alpha between adipocytes and macrophages establishes a vicious cycle that augments the inflammatory changes and insulin resistance in obese adipose tissue. Polyphenols, which are widely distributed in fruit and vegetables, can act as antioxidants and some of them are also reported to have anti-inflammatory properties. Tomato is one of the most popular and extensively consumed vegetable crops worldwide, which also contains many flavonoids, mainly naringenin chalcone. We investigated the effect of flavonoids, including naringenin chalcone, on the production of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated macrophages and in the interaction between adipocytes and macrophages. Naringenin chalcone inhibited the production of TNF-alpha, MCP-1, and nitric oxide (NO) by LPS-stimulated RAW 264 macrophages in a dose-dependent manner. Coculture of 3T3-L1 adipocytes and RAW 264 macrophages markedly enhanced the production of TNF-alpha, MCP-1, and NO compared with the control cultures; however, treatment with naringenin chalcone dose-dependently inhibited the production of these proinflammatory mediators. These results indicate that naringenin chalcone exhibits anti-inflammatory properties by inhibiting the production of proinflammatory cytokines in the interaction between adipocytes and macrophages. Naringenin chalcone may be useful for ameliorating the inflammatory changes in obese adipose tissue.

  14. Suppressive Role of PPARγ-Regulated Endothelial Nitric Oxide Synthase in Adipocyte Lipolysis

    PubMed Central

    Yamada, Yoko; Eto, Masato; Ito, Yuki; Mochizuki, Satoru; Son, Bo-Kyung; Ogawa, Sumito; Iijima, Katsuya; Kaneki, Masao; Kozaki, Koichi; Toba, Kenji; Akishita, Masahiro; Ouchi, Yasuyoshi

    2015-01-01

    Introduction Metabolic syndrome causes insulin resistance and is associated with risk factor clustering, thereby increasing the risk of atherosclerosis. Recently, endothelial nitric oxide synthase deficient (eNOS-/-) mice have been reported to show metabolic disorders. Interestingly, eNOS has also been reported to be expressed in non-endothelial cells including adipocytes, but the functions of eNOS in adipocytes remain unclear. Methods and Results The eNOS expression was induced with adipocyte differentiation and inhibition of eNOS/NO enhanced lipolysis in vitro and in vivo. Furthermore, the administration of a high fat diet (HFD) was able to induce non-alcoholic steatohepatitis (NASH) in eNOS-/- mice but not in wild type mice. A PPARγ antagonist increased eNOS expression in adipocytes and suppressed HFD-induced fatty liver changes. Conclusions eNOS-/- mice induce NASH development, and these findings provide new insights into the therapeutic approach for fatty liver disease and related disorders. PMID:26317347

  15. The role of sex steroids in white adipose tissue adipocyte function.

    PubMed

    Newell-Fugate, A E

    2017-04-01

    With the increasing knowledge that gender influences normal physiology, much biomedical research has begun to focus on the differential effects of sex on tissue function. Sexual dimorphism in mammals is due to the combined effects of both genetic and hormonal factors. Hormonal factors are mutable particularly in females in whom the estrous cycle dominates the hormonal milieu. Given the severity of the obesity epidemic and the fact that there are differences in the obesity rates in men and women, the role of sex in white adipose tissue function is being recognized as increasingly important. Although sex differences in white adipose tissue distribution are well established, the mechanisms affecting differential function of adipocytes within white adipose tissue in males and females remain largely understudied and poorly understood. One of the largest differences in the endocrine environment in males and females is the concentration of circulating androgens and estrogens. This review examines the effects of androgens and estrogens on lipolysis/lipogenesis, adipocyte differentiation, insulin sensitivity and adipokine production in adipocytes from white adipose tissue with a specific emphasis on the sexual dimorphism of adipocyte function in white adipose tissue during both health and disease.

  16. Recombinant canine single chain insulin analogues: insulin receptor binding capacity and ability to stimulate glucose uptake.

    PubMed

    Adams, Jamie P; Holder, Angela L; Catchpole, Brian

    2014-12-01

    Virtually all diabetic dogs require exogenous insulin therapy to control their hyperglycaemia. In the UK, the only licensed insulin product currently available is a purified porcine insulin preparation. Recombinant insulin is somewhat problematic in terms of its manufacture, since the gene product (preproinsulin) undergoes substantial post-translational modification in pancreatic β cells before it becomes biologically active. The aim of the present study was to develop recombinant canine single chain insulin (SCI) analogues that could be produced in a prokaryotic expression system and which would require minimal processing. Three recombinant SCI constructs were developed in a prokaryotic expression vector, by replacing the insulin C-peptide sequence with one encoding a synthetic peptide (GGGPGKR), or with one of two insulin-like growth factor (IGF)-2 C-peptide coding sequences (human: SRVSRRSR; canine: SRVTRRSSR). Recombinant proteins were expressed in the periplasmic fraction of Escherichia coli and assessed for their ability to bind to the insulin and IGF-1 receptors, and to stimulate glucose uptake in 3T3-L1 adipocytes. All three recombinant SCI analogues demonstrated preferential binding to the insulin receptor compared to the IGF-1 receptor, with increased binding compared to recombinant canine proinsulin. The recombinant SCI analogues stimulated glucose uptake in 3T3-L1 adipocytes compared to negligible uptake using recombinant canine proinsulin, with the canine insulin/cIGF-2 chimaeric SCI analogue demonstrating the greatest effect. Thus, biologically-active recombinant canine SCI analogues can be produced relatively easily in bacteria, which could potentially be used for treatment of diabetic dogs.

  17. Insulin Test

    MedlinePlus

    ... ovarian syndrome (PCOS) , prediabetes or heart disease , or metabolic syndrome . A health practitioner also may order insulin and ... such as appears in type 2 diabetes and metabolic syndrome Decreased insulin levels are seen with: Diabetes Hypopituitarism ...

  18. Adipocyte induced arterial calcification is prevented with sodium thiosulfate

    SciTech Connect

    Chen, Neal X.; O’Neill, Kalisha; Akl, Nader Kassis; Moe, Sharon M.

    2014-06-20

    Highlights: • High phosphorus can induce calcification of adipocytes, even when fully differentiated. • Adipocytes can induce vascular calcification in an autocrine manner. • Sodium thiosulfate inhibits adipocyte calcification. - Abstract: Background: Calcification can occur in fat in multiple clinical conditions including in the dermis, breasts and in the abdomen in calciphylaxis. All of these are more common in patients with advanced kidney disease. Clinically, hyperphosphatemia and obesity are risk factors. Thus we tested the hypothesis that adipocytes can calcify in the presence of elevated phosphorus and/or that adipocytes exposed to phosphorus can induce vascular smooth muscle cell (VSMC) calcification. Methods: 3T3-L1 preadipocytes were induced into mature adipocytes and then treated with media containing high phosphorus. Calcification was assessed biochemically and PCR performed to determine the expression of genes for osteoblast and adipocyte differentiation. Adipocytes were also co-cultured with bovine VSMC to determine paracrine effects, and the efficacy of sodium thiosulfate was determined. Results: The results demonstrated that high phosphorus induced the calcification of differentiated adipocytes with increased expression of osteopontin, the osteoblast transcription factor Runx2 and decreased expression of adipocyte transcription factors peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding protein α (CEBPα), indicating that high phosphorus led to a phenotypic switch of adipocytes to an osteoblast like phenotype. Sodium thiosulfate, dose dependently decreased adipocyte calcification and inhibited adipocyte induced increase of VSMC calcification. Co-culture studies demonstrated that adipocytes facilitated VSMC calcification partially mediated by changes of secretion of leptin and vascular endothelial growth factor (VEGF) from adipocytes. Conclusion: High phosphorus induced calcification of mature adipocytes, and

  19. The Effects of High Fat Diet and Resveratrol on Mitochondrial Activity of Brown Adipocytes

    PubMed Central

    Cho, Yoon Hee; Hong, Zhen-Yu; Lee, Ha; Lee, Sue Ji; Hong, Seung-soo

    2016-01-01

    Background Resveratrol (RSV) is a polyphenolic phytoalexin that has many effects on metabolic diseases such as diabetes and obesity. Given the importance of brown adipose tissue (BAT) for energy expenditure, we investigated the effects of RSV on brown adipocytes. Methods For the in vitro study, interscapular BAT was isolated from 7-week-old male Sprague Dawley rats. For the in vivo study, 7-week-old male Otsuka Long Evans Tokushima Fatty (OLETF) rats were divided into four groups and treated for 27 weeks with: standard diet (SD); SD+RSV (10 mg/kg body weight, daily); high fat diet (HFD); HFD+RSV. RSV was provided via oral gavage once daily during the in vivo experiments. Results RSV treatment of primary cultured brown preadipocytes promoted mitochondrial activity, along with over-expression of estrogen receptor α (ER-α). In OLETF rats, both HFD and RSV treatment increased the weight of BAT and the differentiation of BAT. However, only RSV increased the mitochondrial activity and ER-α expression of BAT in the HFD-fed group. Finally, RSV improved the insulin sensitivity of OLETF rats by increasing the mitochondrial activity of BAT, despite having no effects on white adipocytes and muscles in either diet group. Conclusion RSV could improve insulin resistance, which might be associated with mitochondrial activity of brown adipocyte. Further studies evaluating the activity of RSV for both the differentiation and mitochondrial activity of BAT could be helpful in investigating the effects of RSV on metabolic parameters. PMID:27077216

  20. Sex-Dependent Effects of HO-1 Deletion from Adipocytes in Mice

    PubMed Central

    Hosick, Peter A.; Weeks, Mary Frances; Hankins, Michael W.; Moore, Kyle H.; Stec, David E.

    2017-01-01

    Induction of heme oxygenase-1 (HO-1) has been demonstrated to decrease body weight and improve insulin sensitivity in several models of obesity in rodents. To further study the role of HO-1 in adipose tissue, we created an adipose-specific HO-1 knockout mouse model. Male and female mice were fed either a control or a high-fat diet for 30 weeks. Body weights were measured weekly and body composition, fasting blood glucose and insulin levels were determined every six weeks. Adipocyte-specific knockout of HO-1 had no significant effect on body weight in mice fed a high-fat diet but increased body weight in female mice fed a normal-fat diet. Although body weights were not different in females fed a high fat diet, loss of HO-1 in adipocytes resulted in significant alterations in body composition. Adipose-specific HO-1 knockout resulted in increased fasting hyperglycemia and insulinemia in female but not male mice on both diets. Adipose-specific knockout of HO-1 resulted in a significant loss of HO activity and a decrease in the protein levels of adiponectin in adipose tissue. These results demonstrate that loss of HO-1 in adipocytes has greater effects on body fat and fasting hyperglycemia in a sex-dependent fashion and that expression of HO-1 in adipose tissue may have a greater protective role in females as compared to males. PMID:28287466

  1. Pmch-Deficiency in Rats Is Associated with Normal Adipocyte Differentiation and Lower Sympathetic Adipose Drive

    PubMed Central

    Mul, Joram D.; O’Duibhir, Eoghan; Shrestha, Yogendra B.; Koppen, Arjen; Vargoviç, Peter; Toonen, Pim W.; Zarebidaki, Eleen; Kvetnansky, Richard; Kalkhoven, Eric; Cuppen, Edwin; Bartness, Timothy J.

    2013-01-01

    The orexigenic neuropeptide melanin-concentrating hormone (MCH), a product of Pmch, is an important mediator of energy homeostasis. Pmch-deficient rodents are lean and smaller, characterized by lower food intake, body-, and fat mass. Pmch is expressed in hypothalamic neurons that ultimately are components in the sympathetic nervous system (SNS) drive to white and interscapular brown adipose tissue (WAT, iBAT, respectively). MCH binds to MCH receptor 1 (MCH1R), which is present on adipocytes. Currently it is unknown if Pmch-ablation changes adipocyte differentiation or sympathetic adipose drive. Using Pmch-deficient and wild-type rats on a standard low-fat diet, we analyzed dorsal subcutaneous and perirenal WAT mass and adipocyte morphology (size and number) throughout development, and indices of sympathetic activation in WAT and iBAT during adulthood. Moreover, using an in vitro approach we investigated the ability of MCH to modulate 3T3-L1 adipocyte differentiation. Pmch-deficiency decreased dorsal subcutaneous and perirenal WAT mass by reducing adipocyte size, but not number. In line with this, in vitro 3T3-L1 adipocyte differentiation was unaffected by MCH. Finally, adult Pmch-deficient rats had lower norepinephrine turnover (an index of sympathetic adipose drive) in WAT and iBAT than wild-type rats. Collectively, our data indicate that MCH/MCH1R-pathway does not modify adipocyte differentiation, whereas Pmch-deficiency in laboratory rats lowers adiposity throughout development and sympathetic adipose drive during adulthood. PMID:23555928

  2. A novel IRS-1-associated protein, DGKζ regulates GLUT4 translocation in 3T3-L1 adipocytes.

    PubMed

    Liu, TingYu; Yu, BuChin; Kakino, Mamoru; Fujimoto, Hitoshi; Ando, Yasutoshi; Hakuno, Fumihiko; Takahashi, Shin-Ichiro

    2016-10-14

    Insulin receptor substrates (IRSs) are major targets of insulin receptor tyrosine kinases. Here we identified diacylglycerol kinase zeta (DGKζ) as an IRS-1-associated protein, and examined roles of DGKζ in glucose transporter 4 (GLUT4) translocation to the plasma membrane. When DGKζ was knocked-down in 3T3-L1 adipocytes, insulin-induced GLUT4 translocation was inhibited without affecting other mediators of insulin-dependent signaling. Similarly, knockdown of phosphatidylinositol 4-phosphate 5-kinase 1α (PIP5K1α), which had been reported to interact with DGKζ, also inhibited insulin-induced GLUT4 translocation. Moreover, DGKζ interacted with IRS-1 without insulin stimulation, but insulin stimulation decreased this interaction. Over-expression of sDGKζ (short-form DGKζ), which competed out DGKζ from IRS-1, enhanced GLUT4 translocation without insulin stimulation. Taking these results together with the data showing that cellular PIP5K activity was correlated with GLUT4 translocation ability, we concluded that IRS-1-associated DGKζ prevents GLUT4 translocation in the absence of insulin and that the DGKζ dissociated from IRS-1 by insulin stimulation enhances GLUT4 translocation through PIP5K1α activity.

  3. A novel IRS-1-associated protein, DGKζ regulates GLUT4 translocation in 3T3-L1 adipocytes

    PubMed Central

    Liu, TingYu; Yu, BuChin; Kakino, Mamoru; Fujimoto, Hitoshi; Ando, Yasutoshi; Hakuno, Fumihiko; Takahashi, Shin-Ichiro

    2016-01-01

    Insulin receptor substrates (IRSs) are major targets of insulin receptor tyrosine kinases. Here we identified diacylglycerol kinase zeta (DGKζ) as an IRS-1-associated protein, and examined roles of DGKζ in glucose transporter 4 (GLUT4) translocation to the plasma membrane. When DGKζ was knocked-down in 3T3-L1 adipocytes, insulin-induced GLUT4 translocation was inhibited without affecting other mediators of insulin-dependent signaling. Similarly, knockdown of phosphatidylinositol 4-phosphate 5-kinase 1α (PIP5K1α), which had been reported to interact with DGKζ, also inhibited insulin-induced GLUT4 translocation. Moreover, DGKζ interacted with IRS-1 without insulin stimulation, but insulin stimulation decreased this interaction. Over-expression of sDGKζ (short-form DGKζ), which competed out DGKζ from IRS-1, enhanced GLUT4 translocation without insulin stimulation. Taking these results together with the data showing that cellular PIP5K activity was correlated with GLUT4 translocation ability, we concluded that IRS-1-associated DGKζ prevents GLUT4 translocation in the absence of insulin and that the DGKζ dissociated from IRS-1 by insulin stimulation enhances GLUT4 translocation through PIP5K1α activity. PMID:27739494

  4. Insulin action in adipose tissue in type 1 diabetes

    PubMed Central

    Arrieta-Blanco, Francisco; Botella-Carretero, Jose Ignacio; Iglesias, Pedro; Balsa, José Antonio; Zamarrón, Isabel; De la Puerta, Cristina; Arrieta, Juan José; Ramos, Francisco; Vázquez, Clotilde; Rovira, Adela

    2011-01-01

    Background: Insulin action has been reported to be normal in type 1 diabetic patients. However, some studies have reported an insulin resistance state in these patients. The aim of this study was to investigate insulin resistance in a group of type 1 diabetic patients. We studied the insulin action in adipose tissue and analyzed the effects of duration of disease, body mass index (BMI), and glycosylated hemoglobin on insulin action at the receptor and postreceptor levels in adipocytes. Methods: Nine female type 1 diabetic patients with different durations of disease and eight nondiabetic female patients of comparable age and BMI were studied. 125I-insulin binding and U-[14C]-D-glucose transport was measured in a sample of subcutaneous gluteus adipose tissue obtained by open surgical biopsy from each subject. Results: The duration of disease was negatively correlated with both 125I-insulin binding capacity (r = −0.70, P < 0.05) and basal and maximum insulin-stimulated glucose transport (r = −0.87, P < 0.01, and r = −0.88, P < 0.01, respectively). Maximum specific 125I-insulin binding to the receptors in adipocytes was higher in the group of patients with a shorter duration of disease (P < 0.01). Basal and maximum insulin-stimulated glucose transport was significantly higher in the group with less than 5 years of disease (P < 0.01). No correlation was found between BMI and insulin action. Conclusion: Female type 1 diabetic patients have normal insulin action. There is a high glucose uptake in the early phase of the disease, although a longer duration of disease appears to be a contributing factor to a decrease in insulin action in these patients, and involving both receptor and postreceptor mechanisms. PMID:21475629

  5. Alpha-tocopheryl-phosphate regulation of gene expression in pre-adipocytes and adipocytes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A correct function of adipocytes in connection with cellular fatty acid loading and release is a vital aspect of energy homeostasis; dysregulation of these reactions can result in obesity and type 2 diabetes mellitus. In addition, adipocytes have been proposed to play a major role in preventing lipo...

  6. Resveratrol protects against polychlorinated biphenyl-mediated impairment of glucose homeostasis in adipocytes

    PubMed Central

    Baker, Nicki A.; English, Victoria; Sunkara, Manjula; Morris, Andrew J.; Pearson, Kevin J.; Cassis, Lisa A.

    2014-01-01

    Resveratrol (RSV) is a plant polyphenol that exhibits several favorable effects on glucose homeostasis in adipocytes. Recent studies from our laboratory demonstrated that coplanar polychlorinated biphenyls (PCBs) that are ligands of the aryl hydrocarbon receptor (AhR) impair glucose homeostasis in mice. PCB-induced impairment of glucose homeostasis was associated with augmented expression of inflammatory cytokines in adipose tissue, a site for accumulation of lipophilic PCBs. This study determined if RSV protects against PCB-77 induced impairment of glucose disposal in vitro and in vivo, and if these beneficial effects are associated with enhanced nuclear factor erythoid 2-related factor 2 (Nrf2) signaling in adipose tissue. PCB-77 increased oxidative stress and abolished insulin stimulated 2-deoxy-D-glucose (2DG) uptake in 3T3-L1 adipocytes. These effects were restored by RSV, which resulted in a concentration-dependent increase in NAD(P)H:quinone oxidoreductase 1 (NQO1), the downstream target of Nrf2 signaling. We quantified glucose and insulin tolerance and components of Nrf2 and insulin signaling cascades in adipose tissue of male C57BL/6 mice administered vehicle or PCB-77 (50 mg/kg) and fed a diet with or without resVida® (0.1%, or 160 mg/kg/day). PCB-77 impaired glucose and insulin tolerance, and these effects were reversed by RSV. PCB-77 induced reductions in insulin signaling in adipose tissue were also abolished by RSV, which increased NQO1 expression. These results demonstrate that coplanar PCB-induced impairment of glucose homeostasis in mice can be prevented by RSV, potentially through stimulation of Nrf2 signaling and enhanced insulin stimulated glucose disposal in adipose tissue. PMID:24231106

  7. Harmine Induces Adipocyte Thermogenesis through RAC1-MEK-ERK-CHD4 Axis

    PubMed Central

    Nie, Tao; Hui, Xiaoyan; Mao, Liufeng; Nie, Baoming; Li, Kuai; Sun, Wei; Gao, Xuefei; Tang, Xiaofeng; Xu, Yong; Jiang, Baishan; Tu, Zhengcao; Li, Peng; Ding, Ke; Han, Weiping; Zhang, Shaoping; Xu, Aimin; Ding, Sheng; Liu, Pentao; Patterson, Adam; Cooper, Garth; Wu, Donghai

    2016-01-01

    Harmine is a natural compound possessing insulin-sensitizing effect in db/db diabetic mice. However its effect on adipose tissue browning is unknown. Here we reveal that harmine antagonizes high fat diet-induced adiposity. Harmine-treated mice gained less weight on a high fat diet and displayed increased energy expenditure and adipose tissue thermogenesis. In vitro, harmine potently induced the expression of thermogenic genes in both brown and white adipocytes, which was largely abolished by inhibition of RAC1/MEK/ERK pathway. Post-transcriptional modification analysis revealed that chromodomain helicase DNA binding protein 4 (CHD4) is a potential downstream target of harmine-mediated ERK activation. CHD4 directly binds the proximal promoter region of Ucp1, which is displaced upon treatment of harmine, thereby serving as a negative modulator of Ucp1. Thus, here we reveal a new application of harmine in combating obesity via this off-target effect in adipocytes. PMID:27805061

  8. Alliin, a garlic (Allium sativum) compound, prevents LPS-induced inflammation in 3T3-L1 adipocytes.

    PubMed

    Quintero-Fabián, Saray; Ortuño-Sahagún, Daniel; Vázquez-Carrera, Manuel; López-Roa, Rocío Ivette

    2013-01-01

    Garlic (Allium sativum L.) has been used to alleviate a variety of health problems due to its high content of organosulfur compounds and antioxidant activity. The main active component is alliin (S-allyl cysteine sulfoxide), a potent antioxidant with cardioprotective and neuroprotective actions. In addition, it helps to decrease serum levels of glucose, insulin, triglycerides, and uric acid, as well as insulin resistance, and reduces cytokine levels. However its potential anti-inflammatory effect is unknown. We examined the effects of alliin in lipopolysaccharide- (LPS-) stimulated 3T3-L1 adipocytes by RT-PCR, Western blot, and microarrays analysis of 22,000 genes. Incubation of cells for 24 h with 100 μmol/L alliin prevented the increase in the expression of proinflammatory genes, IL-6, MCP-1, and Egr-1 in 3T3-L1 adipocytes exposed to 100 ng/mL LPS for 1 h. Interestingly, the phosphorylation of ERK1/2, which is involved in LPS-induced inflammation in adipocytes, was decreased following alliin treatment. Furthermore, the gene expression profile by microarrays evidentiate an upregulation of genes involved in immune response and downregulation of genes related with cancer. The present results have shown that alliin is able to suppress the LPS inflammatory signals by generating an anti-inflammatory gene expression profile and by modifying adipocyte metabolic profile.

  9. Alliin, a Garlic (Allium sativum) Compound, Prevents LPS-Induced Inflammation in 3T3-L1 Adipocytes

    PubMed Central

    Quintero-Fabián, Saray; Ortuño-Sahagún, Daniel; Vázquez-Carrera, Manuel; López-Roa, Rocío Ivette

    2013-01-01

    Garlic (Allium sativum L.) has been used to alleviate a variety of health problems due to its high content of organosulfur compounds and antioxidant activity. The main active component is alliin (S-allyl cysteine sulfoxide), a potent antioxidant with cardioprotective and neuroprotective actions. In addition, it helps to decrease serum levels of glucose, insulin, triglycerides, and uric acid, as well as insulin resistance, and reduces cytokine levels. However its potential anti-inflammatory effect is unknown. We examined the effects of alliin in lipopolysaccharide- (LPS-) stimulated 3T3-L1 adipocytes by RT-PCR, Western blot, and microarrays analysis of 22,000 genes. Incubation of cells for 24 h with 100 μmol/L alliin prevented the increase in the expression of proinflammatory genes, IL-6, MCP-1, and Egr-1 in 3T3-L1 adipocytes exposed to 100 ng/mL LPS for 1 h. Interestingly, the phosphorylation of ERK1/2, which is involved in LPS-induced inflammation in adipocytes, was decreased following alliin treatment. Furthermore, the gene expression profile by microarrays evidentiate an upregulation of genes involved in immune response and downregulation of genes related with cancer. The present results have shown that alliin is able to suppress the LPS inflammatory signals by generating an anti-inflammatory gene expression profile and by modifying adipocyte metabolic profile. PMID:24453416

  10. G0/G1 switch gene-2 regulates human adipocyte lipolysis by affecting activity and localization of adipose triglyceride lipase.

    PubMed

    Schweiger, Martina; Paar, Margret; Eder, Christina; Brandis, Janina; Moser, Elena; Gorkiewicz, Gregor; Grond, Susanne; Radner, Franz P W; Cerk, Ines; Cornaciu, Irina; Oberer, Monika; Kersten, Sander; Zechner, Rudolf; Zimmermann, Robert; Lass, Achim

    2012-11-01

    The hydrolysis of triglycerides in adipocytes, termed lipolysis, provides free fatty acids as energy fuel. Murine lipolysis largely depends on the activity of adipose triglyceride lipase (ATGL), which is regulated by two proteins annotated as comparative gene identification-58 (CGI-58) and G0/G1 switch gene-2 (G0S2). CGI-58 activates and G0S2 inhibits ATGL activity. In contrast to mice, the functional role of G0S2 in human adipocyte lipolysis is poorly characterized. Here we show that overexpression or silencing of G0S2 in human SGBS adipocytes decreases and increases lipolysis, respectively. Human G0S2 is upregulated during adipocyte differentiation and inhibits ATGL activity in a dose-dependent manner. Interestingly, C-terminally truncated ATGL mutants, which fail to localize to lipid droplets, translocate to the lipid droplet upon coexpression with G0S2, suggesting that G0S2 anchors ATGL to lipid droplets independent of ATGL's C-terminal lipid binding domain. Taken together, our results indicate that G0S2 also regulates human lipolysis by affecting enzyme activity and intracellular localization of ATGL. Increased lipolysis is known to contribute to the pathogenesis of insulin resistance, and G0S2 expression has been shown to be reduced in poorly controlled type 2 diabetic patients. Our data indicate that downregulation of G0S2 in adipose tissue could represent one of the underlying causes leading to increased lipolysis in the insulin-resistant state.

  11. Decreased insulin sensitivity during dietary sodium restriction is not mediated by effects of angiotensin II on insulin action.

    PubMed

    Perry, Colin G; Palmer, Tim; Cleland, Steven J; Morton, Ian J; Salt, Ian P; Petrie, John R; Gould, Gwyn W; Connell, John M C

    2003-08-01

    We have previously reported that modest dietary sodium restriction, as advocated in management guidelines for diabetes, may reduce insulin sensitivity. It has since been suggested that this effect may be mediated via cross-talk between insulin and angiotensin II (AII)-stimulated intracellular second messengers. In order to assess the effect of 5 days of modest sodium restriction (to <80 mmol/day target sodium intake) on insulin sensitivity, 15 healthy males underwent a double-blind, placebo-controlled, randomized, cross-over euglycaemic hyperinsulinaemic clamp study. One phase was supplemented with sodium tablets and the other with matched placebo. Insulin sensitivity (M) was reduced during dietary sodium restriction [median M value, 10.2 mg/kg per min (interquartile range 9.50-13.85) versus 12.8 mg/kg per min (interquartile range 9.60-14.30), P <0.05]. To elucidate potential mechanisms that may explain this observation, we investigated the effect of AII on insulin action in isolated adipocytes obtained from healthy females. No effect of AII on insulin-mediated glucose transport or suppression of lipolysis was observed. In conclusion, despite the observation that dietary sodium restriction was associated with a median 15% reduction in insulin sensitivity, we found no evidence of a direct effect of AII on insulin action in human adipocytes.

  12. CD1d-mediated presentation of endogenous lipid antigens by adipocytes requires microsomal triglyceride transfer protein.

    PubMed

    Rakhshandehroo, Maryam; Gijzel, Sanne M W; Siersbæk, Rasmus; Broekema, Marjoleine F; de Haar, Colin; Schipper, Henk S; Boes, Marianne; Mandrup, Susanne; Kalkhoven, Eric

    2014-08-08

    Obesity-induced adipose tissue (AT) dysfunction results in a chronic low-grade inflammation that predisposes to the development of insulin resistance and type 2 diabetes. During the development of obesity, the AT-resident immune cell profile alters to create a pro-inflammatory state. Very recently, CD1d-restricted invariant (i) natural killer T (NKT) cells, a unique subset of lymphocytes that are reactive to so called lipid antigens, were implicated in AT homeostasis. Interestingly, recent data also suggest that human and mouse adipocytes can present such lipid antigens to iNKT cells in a CD1d-dependent fashion, but little is known about the lipid antigen presentation machinery in adipocytes. Here we show that CD1d, as well as the lipid antigen loading machinery genes pro-saposin (Psap), Niemann Pick type C2 (Npc2), α-galactosidase (Gla), are up-regulated in early adipogenesis, and are transcriptionally controlled by CCAAT/enhancer-binding protein (C/EBP)-β and -δ. Moreover, adipocyte-induced Th1 and Th2 cytokine release by iNKT cells also occurred in the absence of exogenous ligands, suggesting the display of endogenous lipid antigen-D1d complexes by 3T3-L1 adipocytes. Furthermore, we identified microsomal triglyceride transfer protein, which we show is also under the transcriptional regulation of C/EBPβ and -δ, as a novel player in the presentation of endogenous lipid antigens by adipocytes. Overall, our findings indicate that adipocytes can function as non-professional lipid antigen presenting cells, which may present an important aspect of adipocyte-immune cell communication in the regulation of whole body energy metabolism and immune homeostasis.

  13. CD1d-mediated Presentation of Endogenous Lipid Antigens by Adipocytes Requires Microsomal Triglyceride Transfer Protein*

    PubMed Central

    Rakhshandehroo, Maryam; Gijzel, Sanne M. W.; Siersbæk, Rasmus; Broekema, Marjoleine F.; de Haar, Colin; Schipper, Henk S.; Boes, Marianne; Mandrup, Susanne; Kalkhoven, Eric

    2014-01-01

    Obesity-induced adipose tissue (AT) dysfunction results in a chronic low-grade inflammation that predisposes to the development of insulin resistance and type 2 diabetes. During the development of obesity, the AT-resident immune cell profile alters to create a pro-inflammatory state. Very recently, CD1d-restricted invariant (i) natural killer T (NKT) cells, a unique subset of lymphocytes that are reactive to so called lipid antigens, were implicated in AT homeostasis. Interestingly, recent data also suggest that human and mouse adipocytes can present such lipid antigens to iNKT cells in a CD1d-dependent fashion, but little is known about the lipid antigen presentation machinery in adipocytes. Here we show that CD1d, as well as the lipid antigen loading machinery genes pro-saposin (Psap), Niemann Pick type C2 (Npc2), α-galactosidase (Gla), are up-regulated in early adipogenesis, and are transcriptionally controlled by CCAAT/enhancer-binding protein (C/EBP)-β and -δ. Moreover, adipocyte-induced Th1 and Th2 cytokine release by iNKT cells also occurred in the absence of exogenous ligands, suggesting the display of endogenous lipid antigen-D1d complexes by 3T3-L1 adipocytes. Furthermore, we identified microsomal triglyceride transfer protein, which we show is also under the transcriptional regulation of C/EBPβ and –δ, as a novel player in the presentation of endogenous lipid antigens by adipocytes. Overall, our findings indicate that adipocytes can function as non-professional lipid antigen presenting cells, which may present an important aspect of adipocyte-immune cell communication in the regulation of whole body energy metabolism and immune homeostasis. PMID:24966328

  14. [Molecular mechanisms of the alternative lipogenic function of insulin].

    PubMed

    Pankov, Iu A

    2013-01-01

    The proposed hypothesis suggests that major function of insulin is stimulation of triglyceride accumulation in adipose tissue and glycogen synthesis in liver and muscles. The impairment of insulin functioning diminishes triglyceride storage in adipose tissue, elevates the level of its metabolite in periphery and suppresses glucose intake by cells. Leptin disturbs direct insulin action on adipocytes, and prevents fat accumulation. Leptin deficiency or impairment of its functioning facilitate lipogenic effect of insulin, and induce obesity. Lipodystrophy decreases leptin secretion and enhances triglyceride production activated by insulin. Triglycerides are not accumulated in adipose tissue because of its deficiency, and overwhelm peripheral tissues. Lipid metabolites decrease glucose consumption and induce lipoatrophic diabetes. The hypothesis on the lipogenic insulin functioning is confirmed by specific knockout of Insr gene in only tissue: muscles, adipose tissue and other, and by the restoration of its expression in transgenic mice.

  15. Chromium and insulin resistance.

    PubMed

    Anderson, Richard A

    2003-12-01

    Insulin resistance leads to the inability of insulin to control the utilization and storage of glucose. It is associated initially with elevated levels of circulating insulin followed by glucose intolerance which may progress to type 2 diabetes, hyperlipidaemia, hypertension, obesity and cardiovascular diseases. While the causes of these diseases are multifactorial, one nutrient that is associated with all of these abnormalities is Cr. In the presence of Cr, in a biologically active form, much lower levels of insulin are required. Modern diets, which are often high in refined carbohydrates, are not only low in Cr, but lead to enhanced Cr losses. In response to the consumption of refined carbohydrates, there is a rapid rise in blood sugar leading to elevations in insulin that cause a mobilization of Cr. Once mobilized, Cr is not reabsorbed but lost via the urine leading to decreased Cr stores. Several studies involving both human subjects and experimental animals have reported improvements in insulin sensitivity, blood glucose, insulin, lipids, haemoglobin A1c, lean body mass and related variables in response to improved Cr nutrition. However, not all studies have reported beneficial effects associated with improved Cr nutrition. Well-controlled human studies are needed to document an unequivocal effect of Cr on insulin sensitivity in human subjects. Studies need to involve a significant number of subjects with insulin resistance, glucose intolerance or early stages of diabetes, who have not been taking supplements containing Cr for at least 4 months, and involve at least 400 to 600 microg supplemental Cr daily or more. Studies should be at least 4 months to document sustained effects of supplemental Cr on insulin resistance and related variables. Cr is a nutrient and not a therapeutic agent and therefore will only be of benefit to those whose problems are due to suboptimal intake of Cr.

  16. Development of a rapid culture method to induce adipocyte differentiation of human bone marrow-derived mesenchymal stem cells

    SciTech Connect

    Ninomiya, Yuichi; Sugahara-Yamashita, Yzumi; Nakachi, Yutaka; Tokuzawa, Yoshimi; Okazaki, Yasushi; Nishiyama, Masahiko

    2010-04-02

    Human mesenchymal stem cells (hMSCs) derived from bone marrow are multipotent stem cells that can regenerate mesenchymal tissues such as adipose, bone or muscle. It is thought that hMSCs can be utilized as a cell resource for tissue engineering and as human models to study cell differentiation mechanisms, such as adipogenesis, osteoblastogenesis and so on. Since it takes 2-3 weeks for hMSCs to differentiate into adipocytes using conventional culture methods, the development of methods to induce faster differentiation into adipocytes is required. In this study we optimized the culture conditions for adipocyte induction to achieve a shorter cultivation time for the induction of adipocyte differentiation in bone marrow-derived hMSCs. Briefly, we used a cocktail of dexamethasone, insulin, methylisobutylxanthine (DIM) plus a peroxisome proliferator-activated receptor {gamma} agonist, rosiglitazone (DIMRo) as a new adipogenic differentiation medium. We successfully shortened the period of cultivation to 7-8 days from 2-3 weeks. We also found that rosiglitazone alone was unable to induce adipocyte differentiation from hMSCs in vitro. However, rosiglitazone appears to enhance hMSC adipogenesis in the presence of other hormones and/or compounds, such as DIM. Furthermore, the inhibitory activity of TGF-{beta}1 on adipogenesis could be investigated using DIMRo-treated hMSCs. We conclude that our rapid new culture method is very useful in measuring the effect of molecules that affect adipogenesis in hMSCs.

  17. Aculeatin, a coumarin derived from Toddalia asiatica (L.) Lam., enhances differentiation and lipolysis of 3T3-L1 adipocytes

    SciTech Connect

    Watanabe, Akio; Kato, Tsuyoshi; Ito, Yusuke; Yoshida, Izumi; Harada, Teppei; Mishima, Takashi; Fujita, Kazuhiro; Watai, Masatoshi; Nakagawa, Kiyotaka; Miyazawa, Teruo

    2014-10-31

    Highlights: • Aculeatin promoted adipocyte differentiation. • Aculeatin improved glucose uptake. • Aculeatin enhanced adipocyte lipolysis. - Abstract: Toddalia asiatica (L.) Lam. (T. asiatica) has been utilized traditionally for medicinal purposes such as the treatment of diabetes. Currently, the extract is considered to be a good source of anti-diabetic agents, but the active compounds have yet to be identified. In this study, we investigated the effects of fractionated T. asiatica extracts on the differentiation of 3T3-L1 preadipocytes and identified aculeatin as a potential active agent. When 3T3-L1 preadipocytes were treated with aculeatin isolated from T. asiatica in the presence of insulin, aculeatin increased cellular triglyceride levels and glycerol-3-phosphate dehydrogenase activity. This indicated that aculeatin could enhance the differentiation of preadipocytes into adipocytes. Further analyses using a DNA microarray and real-time quantitative reverse-transcription PCR showed an increase in the expression of peroxisome proliferator-activated receptor-γ target genes (Pparg, Ap2, Cd36, Glut4 and Adipoq) by aculeatin, suggesting that aculeatin enhances the differentiation of 3T3-L1 cells by modulating the expression of genes critical for adipogenesis. Interestingly, after treatment of differentiated adipocytes with aculeatin, glucose uptake and lipolysis were enhanced. Overall, our results suggested that aculeatin is an active compound in T. asiatica for enhancing both differentiation and lipolysis of adipocytes, which are useful for the treatment of lipid abnormalities as well as diabetes.

  18. Effect of inhibition of glutathione synthesis on insulin action: in vivo and in vitro studies using buthionine sulfoximine.

    PubMed Central

    Khamaisi, M; Kavel, O; Rosenstock, M; Porat, M; Yuli, M; Kaiser, N; Rudich, A

    2000-01-01

    Decreased cellular GSH content is a common finding in experimental and human diabetes, in which increased oxidative stress appears to occur. Oxidative stress has been suggested to play a causative role in the development of impaired insulin action on adipose tissue and skeletal muscle. In this study we undertook to investigate the potential of GSH depletion to induce insulin resistance, by utilizing the GSH synthesis inhibitor, L-buthionine-[S,R]-sulfoximine (BSO). GSH depletion (20-80% in various tissues), was achieved in vivo by treating rats for 20 days with BSO, and in vitro (80%) by treating 3T3-L1 adipocytes with BSO for 18 h. No demonstrable change in the GSH/GSSG ratio was observed following BSO treatment. GSH depletion was progressively associated with abnormal glucose tolerance test, which could not be attributed to impaired insulin secretion. Skeletal muscle insulin responsiveness was unaffected by GSH depletion, based on normal glucose response to exogenous insulin, 2-deoxyglucose uptake measurements in isolated soleus muscle, and on normal skeletal muscle expression of GLUT4 protein. Adipocyte insulin responsiveness in vitro was assessed in 3T3-L1 adipocytes, which displayed decreased insulin-stimulated tyrosine phosphorylation of insulin-receptor-substrate proteins and of the insulin receptor, but exaggerated protein kinase B phosphorylation. However, insulin-stimulated glucose uptake was unaffected by GSH depletion. In accordance, normal adipose tissue insulin sensitivity was observed in BSO-treated rats in vivo, as demonstrated by normal inhibition of circulating non-esterified fatty acid levels by endogenous insulin secretion. In conclusion, GSH depletion by BSO results in impaired glucose tolerance, but preserved adipocyte and skeletal muscle insulin responsiveness. This suggests that alternative oxidation-borne factors mediate the induction of peripheral insulin resistance by oxidative stress. PMID:10880357

  19. Identification and validation of N-acetyltransferase 2 as an insulin sensitivity gene

    PubMed Central

    Knowles, Joshua W.; Xie, Weijia; Zhang, Zhongyang; Chennemsetty, Indumathi; Assimes, Themistocles L.; Paananen, Jussi; Hansson, Ola; Pankow, James; Goodarzi, Mark O.; Carcamo-Orive, Ivan; Morris, Andrew P.; Chen, Yii-Der I.; Mäkinen, Ville-Petteri; Ganna, Andrea; Mahajan, Anubha; Guo, Xiuqing; Abbasi, Fahim; Greenawalt, Danielle M.; Lum, Pek; Molony, Cliona; Lind, Lars; Lindgren, Cecilia; Raffel, Leslie J.; Tsao, Philip S.; Schadt, Eric E.; Rotter, Jerome I.; Sinaiko, Alan; Reaven, Gerald; Yang, Xia; Hsiung, Chao A.; Groop, Leif; Cordell, Heather J.; Laakso, Markku; Hao, Ke; Ingelsson, Erik; Frayling, Timothy M.; Weedon, Michael N.; Walker, Mark; Quertermous, Thomas

    2015-01-01

    Decreased insulin sensitivity, also referred to as insulin resistance (IR), is a fundamental abnormality in patients with type 2 diabetes and a risk factor for cardiovascular disease. While IR predisposition is heritable, the genetic basis remains largely unknown. The GENEticS of Insulin Sensitivity consortium conducted a genome-wide association study (GWAS) for direct measures of insulin sensitivity, such as euglycemic clamp or insulin suppression test, in 2,764 European individuals, with replication in an additional 2,860 individuals. The presence of a nonsynonymous variant of N-acetyltransferase 2 (NAT2) [rs1208 (803A>G, K268R)] was strongly associated with decreased insulin sensitivity that was independent of BMI. The rs1208 “A” allele was nominally associated with IR-related traits, including increased fasting glucose, hemoglobin A1C, total and LDL cholesterol, triglycerides, and coronary artery disease. NAT2 acetylates arylamine and hydrazine drugs and carcinogens, but predicted acetylator NAT2 phenotypes were not associated with insulin sensitivity. In a murine adipocyte cell line, silencing of NAT2 ortholog Nat1 decreased insulin-mediated glucose uptake, increased basal and isoproterenol-stimulated lipolysis, and decreased adipocyte differentiation, while Nat1 overexpression produced opposite effects. Nat1-deficient mice had elevations in fasting blood glucose, insulin, and triglycerides and decreased insulin sensitivity, as measured by glucose and insulin tolerance tests, with intermediate effects in Nat1 heterozygote mice. Our results support a role for NAT2 in insulin sensitivity. PMID:25798622

  20. Identification and validation of N-acetyltransferase 2 as an insulin sensitivity gene.

    PubMed

    Knowles, Joshua W; Xie, Weijia; Zhang, Zhongyang; Chennamsetty, Indumathi; Chennemsetty, Indumathi; Assimes, Themistocles L; Paananen, Jussi; Hansson, Ola; Pankow, James; Goodarzi, Mark O; Carcamo-Orive, Ivan; Morris, Andrew P; Chen, Yii-Der I; Mäkinen, Ville-Petteri; Ganna, Andrea; Mahajan, Anubha; Guo, Xiuqing; Abbasi, Fahim; Greenawalt, Danielle M; Lum, Pek; Molony, Cliona; Lind, Lars; Lindgren, Cecilia; Raffel, Leslie J; Tsao, Philip S; Schadt, Eric E; Rotter, Jerome I; Sinaiko, Alan; Reaven, Gerald; Yang, Xia; Hsiung, Chao A; Groop, Leif; Cordell, Heather J; Laakso, Markku; Hao, Ke; Ingelsson, Erik; Frayling, Timothy M; Weedon, Michael N; Walker, Mark; Quertermous, Thomas

    2015-04-01

    Decreased insulin sensitivity, also referred to as insulin resistance (IR), is a fundamental abnormality in patients with type 2 diabetes and a risk factor for cardiovascular disease. While IR predisposition is heritable, the genetic basis remains largely unknown. The GENEticS of Insulin Sensitivity consortium conducted a genome-wide association study (GWAS) for direct measures of insulin sensitivity, such as euglycemic clamp or insulin suppression test, in 2,764 European individuals, with replication in an additional 2,860 individuals. The presence of a nonsynonymous variant of N-acetyltransferase 2 (NAT2) [rs1208 (803A>G, K268R)] was strongly associated with decreased insulin sensitivity that was independent of BMI. The rs1208 "A" allele was nominally associated with IR-related traits, including increased fasting glucose, hemoglobin A1C, total and LDL cholesterol, triglycerides, and coronary artery disease. NAT2 acetylates arylamine and hydrazine drugs and carcinogens, but predicted acetylator NAT2 phenotypes were not associated with insulin sensitivity. In a murine adipocyte cell line, silencing of NAT2 ortholog Nat1 decreased insulin-mediated glucose uptake, increased basal and isoproterenol-stimulated lipolysis, and decreased adipocyte differentiation, while Nat1 overexpression produced opposite effects. Nat1-deficient mice had elevations in fasting blood glucose, insulin, and triglycerides and decreased insulin sensitivity, as measured by glucose and insulin tolerance tests, with intermediate effects in Nat1 heterozygote mice. Our results support a role for NAT2 in insulin sensitivity.

  1. Rab5 activity regulates GLUT4 sorting into insulin-responsive and non-insulin-responsive endosomal compartments: a potential mechanism for development of insulin resistance.

    PubMed

    Tessneer, Kandice L; Jackson, Robert M; Griesel, Beth A; Olson, Ann Louise

    2014-09-01

    Glucose transporter isoform 4 (GLUT4) is the insulin-responsive glucose transporter mediating glucose uptake in adipose and skeletal muscle. Reduced GLUT4 translocation from intracellular storage compartments to the plasma membrane is a cause of peripheral insulin resistance. Using a chronic hyperinsulinemia (CHI)-induced cell model of insulin resistance and Rab5 mutant overexpression, we determined these manipulations altered endosomal sorting of GLUT4, thus contributing to the development of insulin resistance. We found that CHI induced insulin resistance in 3T3-L1 adipocytes by retaining GLUT4 in a Rab5-activity-dependent compartment that is unable to equilibrate with the cell surface in response to insulin. Furthermore, CHI-mediated retention of GLUT4 in this non-insulin-responsive compartment impaired filling of the transferrin receptor (TfR)-positive and TfR-negative insulin-responsive storage compartments. Our data suggest that hyperinsulinemia may inhibit GLUT4 by chronically maintaining GLUT4 in the Rab5 activity-dependent endosomal pathway and impairing formation of the TfR-negative and TfR-positive insulin-responsive GLUT4 pools. This model suggests that an early event in the development of insulin-resistant glucose transport in adipose tissue is to alter the intracellular localization of GLUT4 to a compartment that does not efficiently equilibrate with the cell surface when insulin levels are elevated for prolonged periods of time.

  2. Berberine increases expression of GATA-2 and GATA-3 during inhibition of adipocyte differentiation.

    PubMed

    Hu, Y; Davies, G E

    2009-09-01

    It is known that a number of transcription factors are key regulators in the complex process of adipocyte differentiation including peroxisome proliferator activated receptor gamma (PPARgamma) and the CCAAT enhancer binding protein alpha (C/EBPalpha). Studies have demonstrated that in pre-adipocyte 3T3-L1 cells constitutive expression of the DNA binding proteins GATA-2 and GATA-3 results in protein/protein interactions with C/EBPalpha resulting in down regulation of PPARgamma and subsequent suppressed adipocyte differentiation with cells trapped at the pre-adipocyte stage. Thus it appears that GATA-2 and GATA-3 are of critical importance in regulating adipocyte differentiation through molecular interactions with PPARgamma and C/EBPalpha. Recent reports suggest that berberine, an isoquinoline derivative alkaloid isolated from many medicinal herbs prevents differentiation of 3T3-L1 cells via a down regulation of PPARgamma and C/EBPalpha expression. The aim of this study was to determine the effect of berberine on GATA-2 and 3 gene and protein expression levels during differentiation of 3T3-L1 cells. MTT (Methylthiazolyldiphenyl-tetrazolium bromide) was used to detect the cytotoxic effects of berberine on the viability of 3T3-L1 cells during proliferation and differentiation. Differentiation of 3T3-L1 cells was monitored by Oil Red O staining and RT-PCR of PPARgamma and C/EBPalpha and the expression of GATA-2 and 3 was determined by RT-PCR and Western Blot. Results show that following treatment with 8microM berberine the mRNA and protein expression levels of GATA-2 and 3 were elevated and accompanied by inhibited adipocyte differentiation. These results may lead to the use of berberine to target the induction of specific genes such as GATA-2 and GATA-3 which affect adipocyte differentiation.

  3. Proinflammatory cytokines differentially regulate adipocyte mitochondrial metabolism, oxidative stress, and dynamics

    PubMed Central

    Hahn, Wendy S.; Kuzmicic, Jovan; Burrill, Joel S.; Donoghue, Margaret A.; Foncea, Rocio; Jensen, Michael D.; Lavandero, Sergio; Arriaga, Edgar A.

    2014-01-01

    Proinflammatory cytokines differentially regulate adipocyte mitochondrial metabolism, oxidative stress, and dynamics. Macrophage infiltration of adipose tissue and the chronic low-grade production of inflammatory cytokines have been mechanistically linked to the development of insulin resistance, the forerunner of type 2 diabetes mellitus. In this study, we evaluated the chronic effects of TNFα, IL-6, and IL-1β on adipocyte mitochondrial metabolism and morphology using the 3T3-L1 model cell system. TNFα treatment of cultured adipocytes led to significant changes in mitochondrial bioenergetics, including increased proton leak, decreased ΔΨm, increased basal respiration, and decreased ATP turnover. In contrast, although IL-6 and IL-1β decreased maximal respiratory capacity, they had no effect on ΔΨm and varied effects on ATP turnover, proton leak, or basal respiration. Only TNFα treatment of 3T3-L1 cells led to an increase in oxidative stress (as measured by superoxide anion production and protein carbonylation) and C16 ceramide synthesis. Treatment of 3T3-L1 adipocytes with cytokines led to decreased mRNA expression of key transcription factors and control proteins implicated in mitochondrial biogenesis, including PGC-1α and eNOS as well as deceased expression of COX IV and Cyt C. Whereas each cytokine led to effects on expression of mitochondrial markers, TNFα exclusively led to mitochondrial fragmentation and decreased the total level of OPA1 while increasing OPA1 cleavage, without expression of levels of mitofusin 2, DRP-1, or mitofilin being affected. In summary, these results indicate that inflammatory cytokines have unique and specialized effects on adipocyte metabolism, but each leads to decreased mitochondrial function and a reprogramming of fat cell biology. PMID:24595304

  4. Deleted in breast cancer 1 plays a functional role in adipocyte differentiation.

    PubMed

    Moreno-Navarrete, José María; Moreno, María; Vidal, Marta; Ortega, Francisco; Serrano, Marta; Xifra, Gemma; Ricart, Wifredo; Fernández-Real, José Manuel

    2015-04-01

    Genetic deletion of Dbc1 in mice reduced adipose tissue senescence and inflammation while promoting an expansion of this tissue. Here, we aimed to investigate DBC1 mRNA and protein levels in human adipose tissue from subjects with a wide spectrum of fat mass (cohort 1; n = 105) and insulin resistance (cohort 2; n = 47); we also investigated the effects of DBC1 knockdown on 3T3-L1 adipocyte differentiation. DBC1 mRNA was relatively abundant in both visceral (VAT) and subcutaneous adipose tissue (SAT) (mainly in the adipocyte fraction), being decreased in adipose tissue from obese compared with lean subjects. In both VAT and SAT, DBC1 mRNA levels were negatively associated with BMI and positively associated with age and the expression of PPARγ, GLUT4, IRS1, lipogenic (FASN, ACACA), lipid droplet-associated genes (PLIN1, FSP27, ADRP, and TIP47), and lipolytic (ABDH5, AKAP, and PRKACA) genes but negatively associated with ADIPOQ in VAT. DBC1 mRNA and protein levels were increased in the early stages of adipocyte differentiation of human and 3T3-L1 adipocytes. Dbc1 knockdown (KD) with lentivirus led to enhanced adipocyte differentiation, increasing intracellular lipid accumulation and adipogenic gene expression. In conclusion, although DBC1 gene expression was reduced in adipose tissue from obese subjects, it was negatively associated with ADIPOQ gene expression in VAT, suggesting that DBC1 might promote visceral adipose tissue dysfunction. In vitro data supported the antiadipogenic effects of DBC1.

  5. The unsolved mystery of apoA-I recycling in adipocyte.

    PubMed

    Wang, Shuai; Peng, Dao-quan; Yi, Yuhong

    2016-02-24

    As the major storage site for triglycerides and free cholesterol, adipose tissue plays a central role in energy metabolism. ApoA-I is the main constituent of HDL and plays an important role in removal of excess cholesterol from peripheral tissues. Recently, multiple studies have shown beneficial effects of apoA-I on adipose metabolism and function. ApoA-I was reported to improve insulin sensitivity and exert anti-inflammatory, anti-obesity effect in animal studies. Interestingly, Uptake and resecretion of apoA-I by adipocytes has been detected. However, the significance of apoA-I recycling by adipocytes is still not clear. This article reviewed methods used to study cellular recycling of apoA-I and summarized the current knowledge on the mechanisms involved in apoA-I uptake by adipocytes. Since the main function of apoA-I is to mediate reverse cholesterol transport from peripheral tissues, the role of apoA-I internalization and re-secretion by adipocytes in intracellular cholesterol transport under physiological and pathological conditions were discussed. In addition, findings on the correlation between apoA-I recycling and obesity were discussed. Finally, it was proposed that during intracellular transport, apoA-I-protein complex may acquire cargoes other than lipids and deliver regulatory information when they were resecreted into the plasma. Although apoA-I recycling by adipocytes is still an unsolved mystery, it's likely that it is more than a redundant pathway especially under pathological conditions.

  6. Atrial natriuretic peptide regulates lipid mobilization and oxygen consumption in human adipocytes by activating AMPK

    SciTech Connect

    Souza, Sandra C.; Chau, Mary D.L.; Yang, Qing; Gauthier, Marie-Soleil; Clairmont, Kevin B.; Wu, Zhidan; Gromada, Jesper; Dole, William P.

    2011-07-08

    Highlights: {yields} Treatment of differentiated human adipocytes with atrial natriuretic peptide (ANP) increased lipolysis and oxygen consumption by activating AMP-activated protein kinase (AMPK). {yields} ANP stimulated lipid mobilization by selective activation of the alpha2 subunit of AMPK and increased energy utilization through activation of both the alpha1 and alpha2 subunits of AMPK. {yields} ANP enhanced adipocyte mitochondrial oxidative capacity as evidenced by induction of oxidative mitochondrial genes and increase in oxygen consumption. {yields} Exposure of human adipocytes to fatty acids and (TNF{alpha}) induced insulin resistance and decreased expression of mitochondrial genes which was restored to normal by ANP. -- Abstract: Atrial natriuretic peptide (ANP) has been shown to regulate lipid and carbohydrate metabolism providing a possible link between cardiovascular function and metabolism by mediating the switch from carbohydrate to lipid mobilization and oxidation. ANP exerts a potent lipolytic effect via cGMP-dependent protein kinase (cGK)-I mediated-stimulation of AMP-activated protein kinase (AMPK). Activation of the ANP/cGK signaling cascade also promotes muscle mitochondrial biogenesis and fat oxidation. Here we demonstrate that ANP regulates lipid metabolism and oxygen utilization in differentiated human adipocytes by activating the alpha2 subunit of AMPK. ANP treatment increased lipolysis by seven fold and oxygen consumption by two fold, both of which were attenuated by inhibition of AMPK activity. ANP-induced lipolysis was shown to be mediated by the alpha2 subunit of AMPK as introduction of dominant-negative alpha2 subunit of AMPK attenuated ANP effects on lipolysis. ANP-induced activation of AMPK enhanced mitochondrial oxidative capacity as evidenced by a two fold increase in oxygen consumption and induction of mitochondrial genes, including carnitine palmitoyltransferase 1A (CPT1a) by 1.4-fold, cytochrome C (CytC) by 1.3-fold, and

  7. Catabolism of Branched Chain Amino Acids Contributes Significantly to Synthesis of Odd-Chain and Even-Chain Fatty Acids in 3T3-L1 Adipocytes

    PubMed Central

    Crown, Scott B.; Marze, Nicholas; Antoniewicz, Maciek R.

    2015-01-01

    The branched chain amino acids (BCAA) valine, leucine and isoleucine have been implicated in a number of diseases including obesity, insulin resistance, and type 2 diabetes mellitus, although the mechanisms are still poorly understood. Adipose tissue plays an important role in BCAA homeostasis by actively metabolizing circulating BCAA. In this work, we have investigated the link between BCAA catabolism and fatty acid synthesis in 3T3-L1 adipocytes using parallel 13C-labeling experiments, mass spectrometry and model-based isotopomer data analysis. Specifically, we performed parallel labeling experiments with four fully 13C-labeled tracers, [U-13C]valine, [U-13C]leucine, [U-13C]isoleucine and [U-13C]glutamine. We measured mass isotopomer distributions of fatty acids and intracellular metabolites by GC-MS and analyzed the data using the isotopomer spectral analysis (ISA) framework. We demonstrate that 3T3-L1 adipocytes accumulate significant amounts of even chain length (C14:0, C16:0 and C18:0) and odd chain length (C15:0 and C17:0) fatty acids under standard cell culture conditions. Using a novel GC-MS method, we demonstrate that propionyl-CoA acts as the primer on fatty acid synthase for the production of odd chain fatty acids. BCAA contributed significantly to the production of all fatty acids. Leucine and isoleucine contributed at least 25% to lipogenic acetyl-CoA pool, and valine and isoleucine contributed 100% to lipogenic propionyl-CoA pool. Our results further suggest that low activity of methylmalonyl-CoA mutase and mass action kinetics of propionyl-CoA on fatty acid synthase result in high rates of odd chain fatty acid synthesis in 3T3-L1 cells. Overall, this work provides important new insights into the connection between BCAA catabolism and fatty acid synthesis in adipocytes and underscores the high capacity of adipocytes for metabolizing BCAA. PMID:26710334

  8. Insulin allergy.

    PubMed

    Ghazavi, Mohammad K; Johnston, Graham A

    2011-01-01

    Insulin reactions occur rarely but are of tremendous clinical importance. The first was reported in 1922 as a callus reaction at the injection site of insufficiently purified bovine insulin. Porcine insulin was subsequently found to be less allergenic than bovine insulin. Increasingly pure insulins have decreased the risk of adverse reactions, and the production of recombinant insulin with the same amino sequence as human insulin saw a large decrease in adverse reactions. Currently, the prevalence of allergic reactions to insulin products appears to be approximately 2%, and less than one-third of these events have been considered related to the insulin itself. Other reactions occur due to the preservatives added to insulin, including zinc, protamine, and meta-cresol. Allergic reactions can be type I or immunoglobulin E-mediated, type III or Arthus, and type IV or delayed-type hypersensitivity reactions. Type I reactions are the most common and can, rarely, cause anaphylaxis. In contrast, type IV reactions can occur after a delay of several days. Investigations include skin prick testing, patch testing, intradermal testing, and occasionally, skin biopsy.

  9. Dual pathways for the intracellular processing of insulin. Relationship between retroendocytosis of intact hormone and the recycling of insulin receptors.

    PubMed

    Marshall, S

    1985-11-05

    Adipocytes process insulin through either of two pathways: a retroendocytotic pathway that culminates in the release of intact insulin, and a degradative pathway that terminates in the intracellular catabolism and release of degraded ligand. Mechanistically, these pathways were found to differ in several ways. First, temporal differences were found in the rate at which intact and degraded products were extruded. After 125I-insulin was preloaded into the cell interior, intact ligand was completely released during the first 10 min (t 1/2 = 2 min), whereas degraded insulin was released at a much slower rate over 1 h (t 1/2 greater than 8 min). Secondly, it was found that chloroquine profoundly inhibited the insulin degradative pathway, resulting in the intracellular accumulation of intact ligand and a reduction in the release of degraded products. In contrast, however, chloroquine was without effect on the retroendocytotic processing of insulin. Based on the known actions of chloroquine, it appears that retroendocytosis of insulin does not involve vesicular acidification or dissociation of the insulin-receptor complex and that insulin is most likely carried to the cell exterior in the same vesicles (either receptor-bound or free) as those mediating recycling receptors. Interestingly, accumulation of undergraded insulin within chloroquine-treated cells did not result in the release of additional intact ligand, suggesting that once insulin enters the degradative compartment it is committed to catabolism and cannot exit the cell through the retroendocytotic pathway. A third difference was revealed by the finding that extracellular unlabeled insulin (100 ng/ml) markedly accelerated the rate at which preloaded 125I-insulin was released from adipocytes (t 1/2 of 3 min versus 7 min in controls cells). Analysis of the composition of the released products revealed that extracellular insulin rapidly augmented (over 10 min) in a dose-dependent manner (5-200 ng/ml) the amount of

  10. Fatty acid binding protein 4 expression marks a population of adipocyte progenitors in white and brown adipose tissues.

    PubMed

    Shan, Tizhong; Liu, Weiyi; Kuang, Shihuan

    2013-01-01

    Adipose tissues regulate metabolism, reproduction, and life span. The development and growth of adipose tissue are due to increases of both adipocyte cell size and cell number; the latter is mediated by adipocyte progenitors. Various markers have been used to identify either adipocyte progenitors or mature adipocytes. The fatty acid binding protein 4 (FABP4), commonly known as adipocyte protein 2 (aP2), has been extensively used as a marker for differentiated adipocytes. However, whether aP2 is expressed in adipogenic progenitors is controversial. Using Cre/LoxP-based cell lineage tracing in mice, we have identified a population of aP2-expressing progenitors in the stromal vascular fraction (SVF) of both white and brown adipose tissues. The aP2-lineage progenitors reside in the adipose stem cell niche and express adipocyte progenitor markers, including CD34, Sca1, Dlk1, and PDGFRα. When isolated and grown in culture, the aP2-expressing SVF cells proliferate and differentiate into adipocytes upon induction. Conversely, ablation of the aP2 lineage greatly reduces the adipogenic potential of SVF cells. When grafted into wild-type mice, the aP2-lineage progenitors give rise to adipose depots in recipient mice. Therefore, the expression of aP2 is not limited to mature adipocytes, but also marks a pool of undifferentiated progenitors associated with the vasculature of adipose tissues. Our finding adds to the repertoire of adipose progenitor markers and points to a new regulator of adipose plasticity.

  11. Hypoxia-inducible Factor 1α Regulates a SOCS3-STAT3-Adiponectin Signal Transduction Pathway in Adipocytes*

    PubMed Central

    Jiang, Changtao; Kim, Jung-Hwan; Li, Fei; Qu, Aijuan; Gavrilova, Oksana; Shah, Yatrik M.; Gonzalez, Frank J.

    2013-01-01

    Obesity has been identified as a major risk factor for type 2 diabetes, characterized by insulin resistance in insulin target tissues. Hypoxia-inducible factor 1α (HIF1α) regulates pathways in energy metabolism that become dysregulated in obesity. Earlier studies revealed that HIF1α in adipose tissue is markedly elevated in high-fat diet-fed mice that are obese and insulin-resistant. Genetic ablation of HIF1α in adipose tissue decreased insulin resistance and obesity, accompanied by increased serum adiponectin levels. However, the exact mechanism whereby HIF1α regulates adiponectin remains unclear. Here, acriflavine (ACF), an inhibitor of HIF1α, induced the expression of adiponectin and reduced the expression of SOCS3 in cultured 3T3-L1 adipocytes. Mechanistic studies revealed that HIF1α suppressed the expression of adiponectin through a SOCS3-STAT3 pathway. Socs3 was identified as a novel HIF1α target gene based on chromatin immunoprecipitation and luciferase assays. STAT3 directly regulated adiponectin in vitro in cultured 3T3-L1 adipocytes. ACF was found to prevent diet-induced obesity and insulin resistance. In vivo, ACF also regulated the SOCS3-STAT3-adiponectin pathway, and inhibition of HIF1α in adipose tissue was essential for ACF to improve the SOCS3-STAT3-adiponectin pathway to counteract insulin resistance. This study provides evidence for a novel target gene and signal transduction pathway in adipocytes and indicates that inhibitors of HIF1α have potential utility for the treatment of obesity and type 2 diabetes. PMID:23255598

  12. Deletion of Rab GAP AS160 modifies glucose uptake and GLUT4 translocation in primary skeletal muscles and adipocytes and impairs glucose homeostasis.

    PubMed

    Lansey, Melissa N; Walker, Natalie N; Hargett, Stefan R; Stevens, Joseph R; Keller, Susanna R

    2012-11-15

    Tight control of glucose uptake in skeletal muscles and adipocytes is crucial to glucose homeostasis and is mediated by regulating glucose transporter GLUT4 subcellular distribution. In cultured cells, Rab GAP AS160 controls GLUT4 intracellular retention and release to the cell surface and consequently regulates glucose uptake into cells. To determine AS160 function in GLUT4 trafficking in primary skeletal muscles and adipocytes and investigate its role in glucose homeostasis, we characterized AS160 knockout (AS160(-/-)) mice. We observed increased and normal basal glucose uptake in isolated AS160(-/-) adipocytes and soleus, respectively, while insulin-stimulated glucose uptake was impaired and GLUT4 expression decreased in both. No such abnormalities were found in isolated AS160(-/-) extensor digitorum longus muscles. In plasma membranes isolated from AS160(-/-) adipose tissue and gastrocnemius/quadriceps, relative GLUT4 levels were increased under basal conditions and remained the same after insulin treatment. Concomitantly, relative levels of cell surface-exposed GLUT4, determined with a glucose transporter photoaffinity label, were increased in AS160(-/-) adipocytes and normal in AS160(-/-) soleus under basal conditions. Insulin augmented cell surface-exposed GLUT4 in both. These observations suggest that AS160 is essential for GLUT4 intracellular retention and regulation of glucose uptake in adipocytes and skeletal muscles in which it is normally expressed. In vivo studies revealed impaired insulin tolerance in the presence of normal (male) and impaired (female) glucose tolerance. Concurrently, insulin-elicited increases in glucose disposal were abolished in all AS160(-/-) skeletal muscles and liver but not in AS160(-/-) adipose tissues. This suggests AS160 as a target for differential manipulation of glucose homeostasis.

  13. Luteolin is a bioflavonoid that attenuates adipocyte-derived inflammatory responses via suppression of nuclear factor-κB/mitogen-activated protein kinases pathway

    PubMed Central

    Nepali, Sarmila; Son, Ji-Seon; Poudel, Barun; Lee, Ji-Hyun; Lee, Young-Mi; Kim, Dae-Ki

    2015-01-01

    Background: Inflammation of adipocytes has been a therapeutic target for treatment of obesity and metabolic disorders which cause insulin resistance and hence lead to type II diabetes. Luteolin is a bioflavonoid with many beneficial properties such as antioxidant, antiproliferative, and anti-cancer. Objectives: To elucidate the potential anti-inflammatory response and the underlying mechanism of luteolin in 3T3-L1 adipocytes. Materials and Methods: We stimulated 3T3-L1 adipocytes with the mixture of tumor necrosis factor-α, lipopolysaccharide, and interferon-γ (TLI) in the presence or absence of luteolin. We performed Griess’ method for nitric oxide (NO) production and measure mRNA and protein expressions by real-time polymerase chain reaction and western blotting, respectively. Results: Luteolin opposed the stimulation of inducible nitric oxide synthase and NO production by simultaneous treatment of adipocytes with TLI. Furthermore, it reduced the pro-inflammatory genes such as cyclooxygenase-2, interleukin-6, resistin, and monocyte chemoattractant protein-1. Furthermore, luteolin improved the insulin sensitivity by enhancing the expression of insulin receptor substrates (IRS1/2) and glucose transporter-4 via phosphatidylinositol-3K signaling pathway. This inhibition was associated with suppression of Iκ-B-α degradation and subsequent inhibition of nuclear factor-κB (NF-κB) p65 translocation to the nucleus. In addition, luteolin blocked the phosphorylation of ERK1/2, c-Jun N-terminal Kinases and also p38 mitogen-activated protein kinases (MAPKs). Conclusions: These results illustrate that luteolin attenuates inflammatory responses in the adipocytes through suppression of NF-κB and MAPKs activation, and also improves insulin sensitivity in 3T3-L1 cells, suggesting that luteolin may represent a therapeutic agent to prevent obesity-associated inflammation and insulin resistance. PMID:26246742

  14. Subetta treatment increases adiponectin secretion by mature human adipocytes in vitro.

    PubMed

    Nicoll, Jim; Gorbunov, Evgeniy A; Tarasov, Sergey A; Epstein, Oleg I

    2013-01-01

    Purpose. To investigate the mechanism of action in peripheral tissues of novel complex drug containing release-active dilutions of antibodies to the beta subunit of the insulin receptor and antibodies to endothelial nitric oxide synthase (Subetta), which has shown efficacy in animal models of diabetes. Methods. Human mature adipocytes were incubated either with Subetta, with one of negative controls (placebo or vehicle), with one of nonspecific controls (release-active dilutions of antibodies to cannabinoid receptor type I or release-active dilutions of rabbit nonimmune serum), or with dimethyl sulfoxide (DMSO) at 37°C in a humidified incubator at 5% CO2 for three days. Rosiglitazone was used as reference drug. Secretion of adiponectin was measured by quantitative enzyme-linked immunosorbent assay (ELISA). Results. Only Subetta significantly stimulates adiponectin production by mature human adipocytes. Nonspecific controls did not significantly affect adiponectin secretion, resulting in adiponectin levels comparable to background values of the negative controls and DMSO. Conclusion. Increasing adiponectin production in absence of insulin by Subetta probably via modulating effect on the beta subunit of the insulin receptor might serve as one of the mechanisms of the antidiabetic effect of this drug. These in vitro results give first insight on possible mechanism of action of Subetta and serve as a background for further studies.

  15. Leucaena leucocephala fruit aqueous extract stimulates adipogenesis, lipolysis, and glucose uptake in primary rat adipocytes.

    PubMed

    Kuppusamy, Umah Rani; Arumugam, Bavani; Azaman, Nooriza; Jen Wai, Chai

    2014-01-01

    Leucaena leucocephala had been traditionally used to treat diabetes. The present study was designed to evaluate in vitro "insulin-like" activities of Leucaena leucocephala (Lam.) deWit. aqueous fruit extract on lipid and glucose metabolisms. The ability of the extract to stimulate adipogenesis, inhibit lipolysis, and activate radio-labeled glucose uptake was assessed using primary rat adipocytes. Quantitative Real-Time RT-PCR was performed to investigate effects of the extract on expression levels of genes (protein kinases B, AKT; glucose transporter 4, GLUT4; hormone sensitive lipase, HSL; phosphatidylinositol-3-kinases, PI3KA; sterol regulatory element binding factor 1, Srebp1) involved in insulin-induced signaling pathways. L. leucocephala aqueous fruit extract stimulated moderate adipogenesis and glucose uptake into adipocytes when compared to insulin. Generally, the extract exerted a considerable level of lipolytic effect at lower concentration but decreased gradually at higher concentration. The findings concurred with RT-PCR analysis. The expressions of GLUT4 and HSL genes were upregulated by twofold and onefold, respectively, whereas AKT, PI3KA, and Srebp1 genes were downregulated. The L. leucocephala aqueous fruit extract may be potentially used as an adjuvant in the treatment of Type 2 diabetes mellitus and weight management due to its enhanced glucose uptake and balanced adipogenesis and lipolysis properties.

  16. Evaluation of chylomicron effect on ASP production in 3T3-L1 adipocytes.

    PubMed

    Gao, Ying; Gauvreau, Danny; Cui, Wei; Lapointe, Marc; Paglialunga, Sabina; Cianflone, Katherine

    2011-02-01

    In the past few years, there has been increasing interest in the production and physiological role of acylation-stimulating protein (ASP), identical to C3adesArg, a product of the alternative complement pathway generated through C3 cleavage. Recent studies in C3 (-/-) mice that are ASP deficient have demonstrated a role for ASP in postprandial triglyceride clearance and fat storage. The aim of the present study was to establish a cell model and sensitive ELISA assay for the evaluation of ASP production using 3T3-L1 adipocytes. 3T3-L1 preadipocytes were differentiated into adipocytes, then cultured in different media such as serum-free (SF), Dulbecco's modified Eagle's medium (DMEM)/F12 + 10% fetal calf serum (FBS), and at varying concentrations of chylomicrons and insulin + chylomicrons up to 48 h. ASP production in SF and DMEM/F12 + 10% FBS was compared. Chylomicrons stimulated ASP production in a concentration- and time-dependent manner. By contrast, chylomicron treatment had no effect on the production of C3, the precursor protein of ASP, which was constant over 48 h. Addition of insulin (100 nM) to a low-dose of chylomicrons (100 µg TG/ml) significantly increased ASP production compared with chylomicrons alone at 48 h (P < 0.001). Furthermore, addition of insulin significantly increased C3 secretion at both 18 and 48 h of incubation (P < 0.05, P < 0.001, respectively). Overall, the proportion of ASP to C3 remained constant, indicating no change in the ratio of C3 cleaved to generate ASP. This study demonstrated that 3T3-L1 adipocyte is a useful model for the evaluation of C3 secretion and ASP production by using a sensitive mouse-specific ELISA assay. The stimulation of ASP production with chylomicrons demonstrates a physiologically relevant response, and provides a strategy for further studies on ASP production and function.

  17. Insights into an adipocyte whitening program

    PubMed Central

    Hill, Bradford G

    2015-01-01

    White adipose tissue plays a critical role in regulating systemic metabolism and can remodel rapidly in response to changes in nutrient availability. Nevertheless, little is known regarding the metabolic changes occurring in adipocytes during obesity. Our laboratory recently addressed this issue in a commonly used, high-fat-diet mouse model of obesity. We found remarkable changes in adipocyte metabolism that occur prior to infiltration of macrophages in expanding adipose tissue. Results of metabolomic analyses, adipose tissue respirometry, electron microscopy, and expression analyses of key genes and proteins revealed dysregulation of several metabolic pathways, loss of mitochondrial biogenetic capacity, and apparent activation of mitochondrial autophagy which were followed in time by downregulation of numerous mitochondrial proteins important for maintaining oxidative capacity. These findings demonstrate the presence of an adipocyte whitening program that may be critical for regulating adipose tissue remodeling under conditions of chronic nutrient excess. PMID:26167407

  18. Variability of NPH insulin preparations.

    PubMed

    Belmonte, M M; Colle, E; DeBelle, R; Murthy, D Y

    1971-01-23

    In 1968-69 certain juvenile diabetics receiving NPH insulin began having pre-breakfast glucosuria and mid-morning hypoglycemic reactions. A mail survey of our clinic population and a study done at the Quebec camp for diabetic children in 1969 revealed that certain lot numbers were associated with poor control and that a change to new lot numbers or alternate insulin preparations resulted in better control. "Suspect" insulin preparations and non-suspect insulins were given to newly diagnosed diabetics, and plasma insulin and glucose levels were measured over a 24-hour period. The data confirmed that the "suspect" insulins were causing early hypoglycemia and failing to control hyperglycemia during the latter hours of the 24-hour period. The lower glucose levels were associated with higher plasma insulin levels. The "suspect" insulins were further found to have elevated levels of free insulin in the supernatant fluid.The requirements for quality control of modified insulin preparations are reviewed and suggestions are offered for their improvement.

  19. A key role of nuclear factor Y in the refeeding response of fatty acid synthase in adipocytes.

    PubMed

    Nishi-Tatsumi, Makiko; Yahagi, Naoya; Takeuchi, Yoshinori; Toya, Naoki; Takarada, Ayako; Murayama, Yuki; Aita, Yuichi; Sawada, Yoshikazu; Piao, Xiaoying; Oya, Yukari; Shikama, Akito; Masuda, Yukari; Kubota, Midori; Izumida, Yoshihiko; Matsuzaka, Takashi; Nakagawa, Yoshimi; Sekiya, Motohiro; Iizuka, Yoko; Kawakami, Yasushi; Kadowaki, Takashi; Yamada, Nobuhiro; Shimano, Hitoshi

    2017-03-09

    Fatty acid synthase (Fasn) is a key component of energy metabolism that is dynamically induced by food intake. Although extensive studies have revealed a number of transcription factors involved in the fasting/refeeding transition of Fasn expression in hepatocytes, much less evidence is available for adipocytes. Using the in vivo Ad-luc analytical system, we identified the inverted CCAAT element (ICE) around -100 nucleotides in the Fasn promoter as a critical cis-element for the refeeding response in adipocytes. Electrophoretic mobility shift assays and chromatin immunoprecipitation show that nuclear factor Y (NF-Y) binds to ICE specifically in refeeding states. Notably, the NF-Y binding to ICE is differently regulated between adipocytes and hepatocytes. These findings provide insights into the specific mechanisms controlling energy metabolism in adipocytes. This article is protected by copyright. All rights reserved.

  20. Dissociation of in vitro sensitivities of glucose transport and antilipolysis to insulin in NIDDM

    SciTech Connect

    Yki-Jaervinen, H.; Kubo, K.; Zawadzki, J.; Lillioja, S.; Young, A.; Abbott, W.; Foley, J.E.

    1987-09-01

    It is unclear from previous studies whether qualitative or only quantitative differences exist in insulin action in adipocytes obtained from obese subjects with non-insulin-dependent diabetes mellitus (NIDDM) when compared with equally obese nondiabetic subjects. In addition, the role of changes in insulin binding as a cause of insulin resistance in NIDDM is still controversial. The authors compared the sensitivities of (/sup 14/C)-glucose transport and antilipolysis to insulin and measured (/sup 125/I)-insulin binding in abdominal adipocytes obtained from 45 obese nondiabetic, obese diabetic, and 15 nonobese female southwestern American Indians. Compared with the nonobese group, the sensitivities of glucose transport antilipolysis were reduced in both the obese nondiabetic and obese diabetic groups. Compared with the obese nondiabetic subjects, the ED/sub 50/ for stimulation of glucose transport was higher in the obese patients with NIDDM. In contrast, the ED/sub 50/S for antilipolysis were similar in obese diabetic patients and obese nondiabetic subjects. No differences was found in insulin binding in patients with NIDDM when compared with the equally obese nondiabetic subjects. These data indicate 1) the mechanism of insulin resistance differs in NIDDM and obesity, and 2) the selective loss of insulin sensitivity in NIDDM precludes changes in insulin binding as a cause of insulin resistance in this disorder.

  1. Myocardial Fat Accumulation Is Independent of Measures of Insulin Sensitivity

    PubMed Central

    Noureldin, Radwa; Ouwerkerk, Ronald; Liu, Elizabeth Y.; Madan, Ritu; Abel, Brent S.; Mullins, Katherine; Walter, Mary F.; Skarulis, Monica C.; Gharib, Ahmed M.

    2015-01-01

    Background: Myocardial steatosis, an independent predictor of diastolic dysfunction, is frequently present in type 2 diabetes mellitus. High free fatty acid flux, hyperglycemia, and hyperinsulinemia may play a role in myocardial steatosis. There are no prior studies examining the relationship between insulin sensitivity (antilipolytic and glucose disposal actions of insulin) and cardiac steatosis. Objective: Using a cross-sectional study design of individuals with and without metabolic syndrome (MetSyn), we examined the relationships between cardiac steatosis and the sensitivity of the antilipolytic and glucose disposal actions of insulin. Methods: Pericardial fat (PF) volume, intramyocardial and hepatic fat (MF and HF) content, visceral fat (VF) and sc fat content were assessed by magnetic resonance imaging in 77 subjects (49 without MetSyn and 28 with MetSyn). In a subset of the larger cohort (n = 52), peripheral insulin sensitivity index (SI) and adipocyte insulin sensitivity (Adipo-SI) were determined from an insulin-modified frequently sampled iv glucose tolerance test. The Quantitative Insulin Sensitivity Check Index was used as a surrogate for hepatic insulin sensitivity. Results: Individuals with the MetSyn had significantly higher body mass index, total body fat, and MF, PF, HF, and VF content. HF and VF, but not MF, were negatively correlated with the Quantitative Insulin Sensitivity Check Index, Adipo-SI, and SI. Stepwise regression revealed that waist circumference and serum triglyceride levels independently predicted MF and PF, respectively. Adipo-SI and serum triglyceride levels independently predict HF. Conclusion: Myocardial steatosis is unrelated to hepatic, adipocyte, or peripheral insulin sensitivity. Although it is frequently observed in insulin-resistant subjects, further studies are necessary to identify and delineate pathogenic mechanisms that differentially affect cardiac and hepatic steatosis. PMID:26020762

  2. Effects of nutritional status on plasma leptin levels and in vitro regulation of adipocyte leptin expression and secretion in rainbow trout.

    PubMed

    Salmerón, Cristina; Johansson, Marcus; Angotzi, Anna R; Rønnestad, Ivar; Jönsson, Elisabeth; Björnsson, Björn Thrandur; Gutiérrez, Joaquim; Navarro, Isabel; Capilla, Encarnación

    2015-01-01

    As leptin has a key role on appetite, knowledge about leptin regulation is important in order to understand the control of energy balance. We aimed to explore the modulatory effects of adiposity on plasma leptin levels in vivo and the role of potential regulators on leptin expression and secretion in rainbow trout adipocytes in vitro. Fish were fed a regular diet twice daily ad libitum or a high-energy diet once daily at two ration levels; satiation (SA group) or restricted (RE group) to 25% of satiation, for 8weeks. RE fish had significantly reduced growth (p<0.001) and adipose tissue weight (p<0.001), and higher plasma leptin levels (p=0.022) compared with SA fish. Moreover, plasma leptin levels negatively correlated with mesenteric fat index (p=0.009). Adipocytes isolated from the different fish were treated with insulin, ghrelin, leucine, eicosapentaenoic acid or left untreated (control). In adipocytes from fish fed regular diet, insulin and ghrelin increased leptin secretion dose-dependently (p=0.002; p=0.033, respectively). Leptin secretion in control adipocytes was significantly higher in RE than in SA fish (p=0.022) in agreement with the in vivo findings, indicating that adipose tissue may contribute to the circulating leptin levels. No treatment effects were observed in adipocytes from the high-energy diet groups, neither in leptin expression nor secretion, except that leptin secretion was significantly reduced by leucine in RE fish adipocytes (p=0.025). Overall, these data show that the regulation of leptin in rainbow trout adipocytes by hormones and nutrients seems to be on secretion, rather than at the transcriptional level.

  3. Fenretinide mediated retinoic acid receptor signalling and inhibition of ceramide biosynthesis regulates adipogenesis, lipid accumulation, mitochondrial function and nutrient stress signalling in adipocytes and adipose tissue

    PubMed Central

    Mcilroy, George D.; Tammireddy, Seshu R.; Maskrey, Benjamin H.; Grant, Louise; Doherty, Mary K.; Watson, David G.; Delibegović, Mirela; Whitfield, Phillip D.; Mody, Nimesh

    2016-01-01

    Fenretinide (FEN) is a synthetic retinoid that inhibits obesity and insulin resistance in high-fat diet (HFD)-fed mice and completely prevents 3T3-L1 pre-adipocyte differentiation. The aim of this study was to determine the mechanism(s) of FEN action in 3T3-L1 adipocytes and in mice. We used the 3T3-L1 model of adipogenesis, fully differentiated 3T3-L1 adipocytes and adipose tissue from HFD-induced obese mice to investigate the mechanisms of FEN action. We measured expression of adipogenic and retinoid genes by qPCR and activation of nutrient-signalling pathways by western blotting. Global lipid and metabolite analysis was performed and specific ceramide lipid species measured by liquid chromatography-mass spectrometry. We provide direct evidence that FEN inhibits 3T3-L1 adipogenesis via RA-receptor (RAR)-dependent signaling. However, RARα antagonism did not prevent FEN-induced decreases in lipid levels in mature 3T3-L1 adipocytes, suggesting an RAR-independent mechanism. Lipidomics analysis revealed that FEN increased dihydroceramide lipid species 5- to 16-fold in adipocytes, indicating an inhibition of the final step of ceramide biosynthesis. A similar blockade in adipose tissue from FEN-treated obese mice was associated with a complete normalisation of impaired mitochondrial β-oxidation and tricarboxylic acid cycle flux. The FEN catabolite, 4-oxo-N-(4-hydroxyphenyl)retinamide (4-OXO), also decreased lipid accumulation without affecting adipogenesis. FEN and 4-OXO (but not RA) treatment additionally led to the activation of p38-MAPK, peIF2α and autophagy markers in adipocytes. Overall our data reveals FEN utilises both RAR-dependent and -independent pathways to regulate adipocyte biology, both of which may be required for FEN to prevent obesity and insulin resistance in vivo. PMID:26592777

  4. Lipolysis, lipogenesis, and adiposity are reduced while fatty acid oxidation is increased in visceral and subcutaneous adipocytes of endurance-trained rats

    PubMed Central

    Pistor, Kathryn E; Sepa-Kishi, Diane M; Hung, Steven; Ceddia, Rolando B

    2014-01-01

    This study examined the alterations in triglyceride (TG) breakdown and storage in subcutaneous inguinal (SC Ing) and epididymal (Epid) fat depots following chronic endurance training. Male Wistar rats were either kept sedentary (Sed) or subjected to endurance training (Ex) at 70–85% peak VO2 for 6 weeks. At weeks 0, 3, and 6 blood was collected at rest and immediately after a bout of submaximal exercise of similar relative intensity to assess whole-body lipolysis. At week 6, adipocytes were isolated from Epid and SC Ing fat pads for the determination of lipolysis under basal or isoproterenol- and forskolin-stimulated conditions, basal and insulin-stimulated glucose incorporation into lipids, and fatty acid oxidation (FAO). Body weight, fat pad mass, and insulin were reduced by endurance training. Also, circulating non-esterified fatty acids (NEFAs) were 33% lower in Ex than Sed rats when exercising at the same relative intensity. This coincided with reduced isoproterenol-stimulated lipolysis in the Epid (27%) and SC Ing (25%) adipocytes in Ex rats. Similarly, forskolin-stimulated lipolysis was reduced in Epid (51%) and SC Ing (49%) adipocytes from Ex rats. Insulin-stimulated glucose incorporation into lipids in adipocytes from both fat depots from Ex rats was also lower (∼43%) than Sed controls. Conversely, FAO was increased in Epid (1.71-fold) and SC Ing (1.82-fold) adipocytes of Ex rats. In conclusion, chronic endurance exercise reduced lipolysis and lipogenesis while increasing FAO in Epid and SC Ing adipocytes. These are compatible with an energy-sparing adaptive response to reduced adiposity under chronic endurance training conditions. PMID:26167399

  5. Trans, trans-farnesol as a mevalonate-derived inducer of murine 3T3-F442A pre-adipocyte differentiation

    PubMed Central

    Torabi, Sheida

    2015-01-01

    Based on our finding that depletion of mevalonate-derived metabolites inhibits adipocyte differentiation, we hypothesize that trans, trans-farnesol (farnesol), a mevalonate-derived sesquiterpene, induces adipocyte differentiation. Farnesol dose-dependently (25–75 μmol/L) increased intracellular triglyceride content of murine 3T3-F442A pre-adipocytes measured by AdipoRed™ Assay and Oil Red-O staining. Concomitantly, farnesol dose-dependently increased glucose uptake and glucose transport protein 4 (GLUT4) expression without affecting cell viability. Furthermore, quantitative real-time polymerase chain reaction and Western blot showed that farnesol increased the mRNA and protein levels of peroxisome proliferator-activated receptor γ (PPARγ), a key regulator of adipocyte differentiation, and the mRNA levels of PPARγ-regulated fatty acid-binding protein 4 and adiponectin; in contrast, farnesol downregulated Pref-1 gene, a marker of pre-adipocytes. GW9662 (10 µmol/L), an antagonist of PPARγ, reversed the effects of farnesol on cellular lipid content, suggesting that PPARγ signaling pathway may mediate the farnesol effect. Farnesol (25–75 μmol/L) did not affect the mRNA level of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme in the mevalonate pathway. Farnesol may be the mevalonate-derived inducer of adipocyte differentiation and potentially an insulin sensitizer via activation of PPARγ and upregulation of glucose uptake. PMID:26660152

  6. Cold Exposure Induces Proliferation of Mature Brown Adipocyte in a ß3-Adrenergic Receptor-Mediated Pathway

    PubMed Central

    Fukano, Keigo; Okamatsu-Ogura, Yuko; Tsubota, Ayumi; Nio-Kobayashi, Junko; Kimura, Kazuhiro

    2016-01-01

    Hyperplasia of brown adipose tissue (BAT) is a fundamental mechanism for adaptation to survive in the cold environment in rodents. To determine which cell types comprising BAT contribute to tissue hyperplasia, immunohistochemical analysis using a proliferative marker Ki67 was performed on the BAT from 6-week-old C57BL/6J mice housed at 23°C (control) or 10°C (cold) for 5 days. Interestingly, in the control group, the cell proliferative marker Ki67 was detected in the nuclei of uncoupling protein 1-positive mature brown adipocytes (7.2% ± 0.4% of brown adipocyte), as well as in the non-adipocyte stromal-vascular (SV) cells (19.6% ± 2.3% of SV cells), which include preadiopocytes. The percentage of Ki67-positive brown adipocytes increased to 25.6% ± 1.8% at Day 1 after cold exposure and was significantly higher than the non-cold acclimated control until Day 5 (21.8% ± 1.7%). On the other hand, the percentage of Ki67-positive SV cells gradually increased by a cold exposure and peaked to 42.1% ± 8.3% at Day 5. Injection of a ß3-adrenergic receptor (ß3-AR) agonist for continuous 5 days increased the number of Ki67-positive brown adipocytes even at Day 1 but not that of SV cells. In addition, the ß3-AR antagonist, but not ß1-AR antagonist, attenuated the cold exposure-induced increase in the number of Ki67-positive brown adipocytes. These results suggest that mature brown adipocytes proliferate immediately after cold exposure in a ß3-AR-mediated pathway. Thus, proliferation of mature brown adipocytes as well as preadipocytes in SV cells may contribute to cold exposure-induced BAT hyperplasia. PMID:27846311

  7. Non-steroidal anti-inflammatory drugs activate NADPH oxidase in adipocytes and raise the H2O2 pool to prevent cAMP-stimulated protein kinase a activation and inhibit lipolysis

    PubMed Central

    2013-01-01

    Background Non-steroidal anti-inflammatory drugs (NSAIDs) —aspirin, naproxen, nimesulide, and piroxicam— lowered activation of type II cAMP-dependent protein kinase A (PKA-II) in isolated rat adipocytes, decreasing adrenaline- and dibutyryl cAMP (Bt2cAMP)-stimulated lipolysis. The molecular bases of insulin-like actions of NSAID were studied. Results Based on the reported inhibition of lipolysis by H2O2, catalase was successfully used to block NSAID inhibitory action on Bt2cAMP-stimulated lipolysis. NSAID, at (sub)micromolar range, induced an H2O2 burst in rat adipocyte plasma membranes and in whole adipocytes. NSAID-mediated rise of H2O2 was abrogated in adipocyte plasma membranes by: diphenyleneiodonium, an inhibitor of NADPH oxidase (NOX); the NOX4 antibody; and cytochrome c, trapping the NOX-formed superoxide. These three compounds prevented the inhibition of Bt2cAMP-stimulated lipolysis by NSAIDs. Inhibition of aquaporin-mediated H2O2 transport with AgNO3 in adipocytes allowed NOX activation but prevented the lipolysis inhibition promoted by NSAID: i.e., once synthesized, H2O2 must reach the lipolytic machinery. Since insulin inhibits adrenaline-stimulated lipolysis, the effect of aspirin on isoproterenol-stimulated lipolysis in rat adipocytes was studied. As expected, isoproterenol-mediated lipolysis was blunted by both insulin and aspirin. Conclusions NSAIDs activate NOX4 in adipocytes to produce H2O2, which impairs cAMP-dependent PKA-II activation, thus preventing isoproterenol-activated lipolysis. H2O2 signaling in adipocytes is a novel and important cyclooxygenase-independent effect of NSAID. PMID:23718778

  8. Cellular levels of feedback regulator of adenylate cyclase and the effect of epinephrine and insulin.

    PubMed Central

    Ho, R j; Russell, T R; Asakawa, T; Sutherland, E W

    1975-01-01

    We have obtained direct evidence that shows the cellular formation and subsequent release of a potent inhibitor (feedback regulator) of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] by adipocytes, upon stimulation with epinephrine. The appearance of such a feedback regulator in adipocytes preceded its release into the medium. During a 30 min incubation, intracellular regulator levels rose rapidly and reached 39-61 units/g of adipocyte at 10 min. Release of inhibitor into the medium increased slowly and was 11-16 units/g of adipocyte at 10 min. Upon continued incubation, the cells at 30 min contained 30-41 units/g of ingibitor, slightly less than the content at 30 min; meanwhile, the medium content rose more than 3-fold. The inhibitor from both locations appeared to have the same characteristics, judging from the purification procedures and the biological activities on hormone-stimulated adenylate cyclase. Adenylate cyclase was inhibited by the feedback regulator in vitro when either epinephrine, corticotropin (ACTH), or glucagon was used as activator. The site of action of this inhibitor is therefore most likely beyond the specific hormone receptors. A new in vitro action of insulin has been found. Insulin, 50-500 microunits/ml, inhibited the formation and release of this factor from isolated rat or hamster adipocytes by 29-81% after these cells were stimulated by hormones that raise intracellular adenosine 3':5'-cyclic monophosphate. This factor enhaced the effect of insulin in lowering the adenosine 3':5'-cyclic monophosphate levels in fresh rat adipocytes. A reduced formation of such a factor may modify the metabolic events in adipocytes, and some as yet unexplained effects of insulin could therefore be linked to the metabolic effects of this factor. PMID:174073

  9. Inhibitory Effect of Methyl 2-(4'-Methoxy-4'-oxobutanamide) Benzoate from Jerusalem Artichoke (Helianthus tuberosus) on the Inflammatory Paracrine Loop between Macrophages and Adipocytes.

    PubMed

    Jung, Yun Joo; Kim, Byung Oh; Kwak, Jong Hwan; Pyo, Suhkneung

    2016-12-14

    The interaction between macrophages and adipocytes is known to aggravate inflammation of the adipose tissue, leading to decreased insulin sensitivity. Hence, attenuation of the inflammatory paracrine loop between macrophages and adipocytes is deemed essential to ameliorate insulin resistance and diabetes mellitus type 2. Methyl 2-(4'-methoxy-4'-oxobutanamide) benzoate (compound 1), a newly isolated compound from Jerusalem srtichoke (JA), has not been biologically characterized yet. Here, we investigated whether JA-derived compound 1 attenuates the inflammatory cycle between RAW 264.7 macrophages and 3T3-L1 adipocytes. Compound 1 suppressed the inflammatory response of RAW 264.7 cells to lipopolysaccharide through decreased secretion of IL-1β, IL-6, and TNF-α. Moreover, the mRNA expression of TNF-α, IL-6, IL-1β, MCP-1, and Rantes and MAPK pathway activation in 3T3-L1 adipocytes, incubated in macrophage-conditioned media, were inhibited. These findings suggest an anti-inflammatory effect of a newly extracted compound against adipose tissue inflammation and insulin resistance.

  10. White-to-brite conversion in human adipocytes promotes metabolic reprogramming towards fatty acid anabolic and catabolic pathways

    PubMed Central

    Barquissau, V.; Beuzelin, D.; Pisani, D.F.; Beranger, G.E.; Mairal, A.; Montagner, A.; Roussel, B.; Tavernier, G.; Marques, M.-A.; Moro, C.; Guillou, H.; Amri, E.-Z.; Langin, D.

    2016-01-01

    Objective Fat depots with thermogenic activity have been identified in humans. In mice, the appearance of thermogenic adipocytes within white adipose depots (so-called brown-in-white i.e., brite or beige adipocytes) protects from obesity and insulin resistance. Brite adipocytes may originate from direct conversion of white adipocytes. The purpose of this work was to characterize the metabolism of human brite adipocytes. Methods Human multipotent adipose-derived stem cells were differentiated into white adipocytes and then treated with peroxisome proliferator-activated receptor (PPAR)γ or PPARα agonists between day 14 and day 18. Gene expression profiling was determined using DNA microarrays and RT-qPCR. Variations of mRNA levels were confirmed in differentiated human preadipocytes from primary cultures. Fatty acid and glucose metabolism was investigated using radiolabelled tracers, Western blot analyses and assessment of oxygen consumption. Pyruvate dehydrogenase kinase 4 (PDK4) knockdown was achieved using siRNA. In vivo, wild type and PPARα-null mice were treated with a β3-adrenergic receptor agonist (CL316,243) to induce appearance of brite adipocytes in white fat depot. Determination of mRNA and protein levels was performed on inguinal white adipose tissue. Results PPAR agonists promote a conversion of white adipocytes into cells displaying a brite molecular pattern. This conversion is associated with transcriptional changes leading to major metabolic adaptations. Fatty acid anabolism i.e., fatty acid esterification into triglycerides, and catabolism i.e., lipolysis and fatty acid oxidation, are increased. Glucose utilization is redirected from oxidation towards glycerol-3-phophate production for triglyceride synthesis. This metabolic shift is dependent on the activation of PDK4 through inactivation of the pyruvate dehydrogenase complex. In vivo, PDK4 expression is markedly induced in wild-type mice in response to CL316,243, while this increase is blunted

  11. Apolipoprotein E promotes lipid accumulation and differentiation in human adipocytes

    SciTech Connect

    Lasrich, Dorothee; Bartelt, Alexander; Grewal, Thomas; Heeren, Joerg

    2015-09-10

    Several studies in mice indicate a role for apolipoprotein E (APOE) in lipid accumulation and adipogenic differentiation in adipose tissue. However, little is yet known if APOE functions in a similar manner in human adipocytes. This prompted us to compare lipid loading and expression of adipocyte differentiation markers in APOE-deficient and control adipocytes using the differentiated human mesenchymal stem cell line hMSC-Tert as well as primary human and mouse adipocytes as model systems. Differentiated hMSC-Tert were stably transduced with or without siRNA targeting APOE while murine adipocytes were isolated from wild type and Apoe knockout mice. Human APOE knockdown hMSC-Tert adipocytes accumulated markedly less triglycerides compared to control cells. This correlated with strongly decreased gene expression levels of adipocyte markers such as adiponectin (ADIPOQ) and fatty acid binding protein 4 (FABP4) as well as the key transcription factor driving adipocyte differentiation, peroxisome proliferator activator receptor gamma (PPARG), in particular the PPARG2 isoform. Similarly, differentiation of murine Apoe-deficient adipocytes was characterized by reduced gene expression of Adipoq, Fabp4 and Pparg. Interestingly, incubation of APOE-deficient hMSC-Tert adipocytes with conditioned media from APOE3-overexpressing adipocytes or APOE-containing Very Low Density Lipoprotein (VLDL) partially restored triglyceride accumulation, but were unable to induce adipocyte differentiation, as judged by expression of adipocyte markers. Taken together, depletion of endogenous APOE in human adipocytes severely impairs lipid accumulation, which is associated with an inability to initiate differentiation. - Highlights: • Immortalized human mesenchymal stem cells were used to study adipocyte development. • Knockdown of endogenous APOE lead to impaired lipid accumulation and adipogenesis. • APOE supplementation partially restored lipid accumulation but not differentiation.

  12. Impact of embryo number and maternal undernutrition around the time of conception on insulin signaling and gluconeogenic factors and microRNAs in the liver of fetal sheep.

    PubMed

    Lie, Shervi; Morrison, Janna L; Williams-Wyss, Olivia; Suter, Catherine M; Humphreys, David T; Ozanne, Susan E; Zhang, Song; MacLaughlin, Severence M; Kleemann, David O; Walker, Simon K; Roberts, Claire T; McMillen, I Caroline

    2014-05-01

    This study aimed to determine whether exposure of the oocyte and/or embryo to maternal undernutrition results in the later programming of insulin action in the liver and factors regulating gluconeogenesis. To do this, we collect livers from singleton and twin fetal sheep that were exposed to periconceptional (PCUN; -60 to 7 days) or preimplantation (PIUN; 0-7 days) undernutrition at 136-138 days of gestation (term = 150 days). The mRNA and protein abundance of insulin signaling and gluconeogenic factors were then quantified using qRT-PCR and Western blotting, respectively, and global microRNA expression was quantified using deep sequencing methodology. We found that hepatic PEPCK-C mRNA (P < 0.01) and protein abundance and the protein abundance of IRS-1 (P < 0.01), p110β (P < 0.05), PTEN (P < 0.05), CREB (P < 0.01), and pCREB (Ser(133); P < 0.05) were decreased in the PCUN and PIUN singletons. In contrast, hepatic protein abundance of IRS-1 (P < 0.01), p85 (P < 0.01), p110β (P < 0.001), PTEN (P < 0.01), Akt2 (P < 0.01), p-Akt (Ser(473); P < 0.01), and p-FOXO-1 (Thr24) (P < 0.01) was increased in twins. There was a decrease in PEPCK-C mRNA (P < 0.01) but, paradoxically, an increase in PEPCK-C protein (P < 0.001) in twins. Both PCUN and PIUN altered the hepatic expression of 23 specific microRNAs. We propose that the differential impact of maternal undernutrition in the presence of one or two embryos on mRNAs and proteins involved in the insulin signaling and gluconeogenesis is explained by changes in the expression of a suite of specific candidate microRNAs.

  13. Impact of embryo number and maternal undernutrition around the time of conception on insulin signaling and gluconeogenic factors and microRNAs in the liver of fetal sheep

    PubMed Central

    Lie, Shervi; Morrison, Janna L.; Williams-Wyss, Olivia; Suter, Catherine M.; Humphreys, David T.; Ozanne, Susan E.; Zhang, Song; MacLaughlin, Severence M.; Kleemann, David O.; Walker, Simon K.; Roberts, Claire T.

    2014-01-01

    This study aimed to determine whether exposure of the oocyte and/or embryo to maternal undernutrition results in the later programming of insulin action in the liver and factors regulating gluconeogenesis. To do this, we collect livers from singleton and twin fetal sheep that were exposed to periconceptional (PCUN; −60 to 7 days) or preimplantation (PIUN; 0–7 days) undernutrition at 136–138 days of gestation (term = 150 days). The mRNA and protein abundance of insulin signaling and gluconeogenic factors were then quantified using qRT-PCR and Western blotting, respectively, and global microRNA expression was quantified using deep sequencing methodology. We found that hepatic PEPCK-C mRNA (P < 0.01) and protein abundance and the protein abundance of IRS-1 (P < 0.01), p110β (P < 0.05), PTEN (P < 0.05), CREB (P < 0.01), and pCREB (Ser133; P < 0.05) were decreased in the PCUN and PIUN singletons. In contrast, hepatic protein abundance of IRS-1 (P < 0.01), p85 (P < 0.01), p110β (P < 0.001), PTEN (P < 0.01), Akt2 (P < 0.01), p-Akt (Ser473; P < 0.01), and p-FOXO-1 (Thr24) (P < 0.01) was increased in twins. There was a decrease in PEPCK-C mRNA (P < 0.01) but, paradoxically, an increase in PEPCK-C protein (P < 0.001) in twins. Both PCUN and PIUN altered the hepatic expression of 23 specific microRNAs. We propose that the differential impact of maternal undernutrition in the presence of one or two embryos on mRNAs and proteins involved in the insulin signaling and gluconeogenesis is explained by changes in the expression of a suite of specific candidate microRNAs. PMID:24496309

  14. Effects of dopamine on leptin release and leptin gene (OB) expression in adipocytes from obese and hypertensive patients

    PubMed Central

    Alvarez-Aguilar, Cleto; Alvarez-Paredes, Alfonso Rafael; Lindholm, Bengt; Stenvinkel, Peter; García-López, Elvia; Mejía-Rodríguez, Oliva; López-Meza, Joel Edmundo; Amato, Dante; Paniagua, Ramon

    2013-01-01

    Background A reduction of dopaminergic (DAergic) activity with increased prolactin levels has been found in obese and hypertensive patients, suggesting its involvement as a pathophysiological mechanism promoting hypertension. Similarly, leptin action increasing sympathetic activity has been proposed to be involved in mechanisms of hypertension. The aim of this study was to analyze the effects of DA, norepinephrine (NE), and prolactin on leptin release and leptin gene (OB) expression in adipocytes from obese and hypertensive patients. Methods Leptin release and OB gene expression were analyzed in cultured adipocytes from 16 obese and hypertensive patients treated with DA (0.001, 0.01, 0.1, and 1.0 μmol/L), NE (1.0 μmol/L), insulin (0.1 μmol/L), and prolactin (1.0 μmol/L), and from five nonobese and normotensive controls treated with DA (1 μmol/L), NE (1 μmol/L), insulin (0.1 μmol/L), and prolactin (1.0 μmol/L). Results A dose-related reduction of leptin release and OB gene messenger ribonucleic acid expression under different doses of DA was observed in adipocytes from obese hypertensive patients. Whereas prolactin treatment elicited a significant increase of both leptin release and OB gene expression, NE reduced these parameters. Although similar effects of DA and NE were observed in adipocytes from controls, baseline values in controls were reduced to 20% of the value in adipocytes from obese hypertensive patients. Conclusion These results suggest that DAergic deficiency contributes to metabolic disorders linked to hyperleptinemia in obese and hypertensive patients. PMID:24348062

  15. Increasing adipocyte lipoprotein lipase improves glucose metabolism in high fat diet-induced obesity.

    PubMed

    Walton, R Grace; Zhu, Beibei; Unal, Resat; Spencer, Michael; Sunkara, Manjula; Morris, Andrew J; Charnigo, Richard; Katz, Wendy S; Daugherty, Alan; Howatt, Deborah A; Kern, Philip A; Finlin, Brian S

    2015-05-01

    Lipid accumulation in liver and skeletal muscle contributes to co-morbidities associated with diabetes and obesity. We made a transgenic mouse in which the adiponectin (Adipoq) promoter drives expression of lipoprotein lipase (LPL) in adipocytes to potentially increase adipose tissue lipid storage. These mice (Adipoq-LPL) have improved glucose and insulin tolerance as well as increased energy expenditure when challenged with a high fat diet (HFD). To identify the mechanism(s) involved, we determined whether the Adipoq-LPL mice diverted dietary lipid to adipose tissue to reduce peripheral lipotoxicity, but we found no evidence for this. Instead, characterization of the adipose tissue of the male mice after HFD challenge revealed that the mRNA levels of peroxisome proliferator-activated receptor-γ (PPARγ) and a number of PPARγ-regulated genes were higher in the epididymal fat pads of Adipoq-LPL mice than control mice. This included adiponectin, whose mRNA levels were increased, leading to increased adiponectin serum levels in the Adipoq-LPL mice. In many respects, the adipose phenotype of these animals resembles thiazolidinedione treatment except for one important difference, the Adipoq-LPL mice did not gain more fat mass on HFD than control mice and did not have increased expression of genes in adipose such as glycerol kinase, which are induced by high affinity PPAR agonists. Rather, there was selective induction of PPARγ-regulated genes such as adiponectin in the adipose of the Adipoq-LPL mice, suggesting that increasing adipose tissue LPL improves glucose metabolism in diet-induced obesity by improving the adipose tissue phenotype. Adipoq-LPL mice also have increased energy expenditure.

  16. The increasingly complex regulation of adipocyte differentiation

    PubMed Central

    Poulos, Sylvia P; Dodson, Michael V; Culver, Melinda F

    2015-01-01

    Adipose (AD) tissue development and function relies on the ability of adipocytes to proliferate and differentiate into lipid-containing cells that also have endocrine function. Research suggests that certain conditions can induce AD tissue stem cells to differentiate into various cell types and that the microenvironment of the cell, including the extracellular matrix (ECM), is essential in maintaining cell and tissue function. This review provides an overview of factors involved in the proliferation and differentiation of adipocytes. A brief review of the numerous factors that influence PPARγ, the transcription factor thought to be the master regulator of adipocyte differentiation, provides context of established pathways that regulate adipogenesis. Thought provoking findings from research with hypoxia that is supported by earlier research that vascular development is related to adipogenesis are reviewed. Finally, our understanding of the critical role of the ECM and environment in adipogenesis is discussed and compared with studies that suggest that adipocytes may dedifferentiate and can convert into other cell types. PMID:26645953

  17. Ivy gourd (Coccinia grandis L. Voigt) root suppresses adipocyte differentiation in 3T3-L1 cells

    PubMed Central

    2014-01-01

    Background Ivy gourd (Coccinia grandis L. Voigt) is a tropical plant widely distributed throughout Asia, Africa, and the Pacific Islands. The anti-obesity property of this plant has been claimed but still remains to be scientifically proven. We therefore investigated the effects of ivy gourd leaf, stem, and root on adipocyte differentiation by employing cell culture model. Methods Dried roots, stems, and leaves of ivy gourd were separately extracted with ethanol. Each extract was then applied to 3T3-L1 pre-adipocytes upon induction with a mixture of insulin, 3-isobutyl-1-methylxanthine, and dexamethasone, for anti-adipogenesis assay. The active extract was further fractionated by a sequential solvent partitioning method, and the resulting fractions were examined for their abilities to inhibit adipogenesis in 3T3-L1 cells. Differences in the expression of adipogenesis-related genes between the treated and untreated cells were determined from their mRNA and protein levels. Results Of the three ivy gourd extracts, the root extract exhibited an anti-adipogenic effect. It significantly reduced intracellular fat accumulation during the early stages of adipocyte differentiation. Together with the suppression of differentiation, expression of the genes encoding PPARγ, C/EBPα, adiponectin, and GLUT4 were down-regulated. Hexane-soluble fraction of the root extract also inhibited adipocyte differentiation and decreased the mRNA levels of various adipogenic genes in the differentiating cells. Conclusions This is the first study to demonstrate that ivy gourd root may prevent obesity based mainly on the ability of its active constituent(s) to suppress adipocyte differentiation in vitro. Such an inhibitory effect is mediated by at least down-regulating the expression of PPARγ-the key transcription factor of adipogenesis in pre-adipocytes during their early differentiation processes. PMID:24884680

  18. Fucoxanthin exerts differing effects on 3T3-L1 cells according to differentiation stage and inhibits glucose uptake in mature adipocytes

    SciTech Connect

    Kang, Seong-Il; Ko, Hee-Chul; Shin, Hye-Sun; Kim, Hyo-Min; Hong, Youn-Suk; Lee, Nam-Ho; Kim, Se-Jae

    2011-06-17

    Highlights: {yields} Fucoxanthin enhances 3T3-L1 adipocyte differentiation at an early stage. {yields} Fucoxanthin inhibits 3T3-L1 adipocyte differentiation at intermediate and late stages. {yields} Fucoxanthin attenuates glucose uptake by inhibiting the phosphorylation of IRS in mature 3T3-L1 adipocytes. {yields} Fucoxanthin exerts its anti-obesity effect by inhibiting the differentiation of adipocytes at both intermediate and late stages, as well as glucose uptake in mature adipocytes. -- Abstract: Progression of 3T3-L1 preadipocyte differentiation is divided into early (days 0-2, D0-D2), intermediate (days 2-4, D2-D4), and late stages (day 4 onwards, D4-). In this study, we investigated the effects of fucoxanthin, isolated from the edible brown seaweed Petalonia binghamiae, on adipogenesis during the three differentiation stages of 3T3-L1 preadipocytes. When fucoxanthin was applied during the early stage of differentiation (D0-D2), it promoted 3T3-L1 adipocyte differentiation, as evidenced by increased triglyceride accumulation. At the molecular level, fucoxanthin increased protein expression of peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}), CCAAT/enhancer-binding protein {alpha} (C/EBP{alpha}), sterol regulatory element-binding protein 1c (SREBP1c), and aP2, and adiponectin mRNA expression, in a dose-dependent manner. However, it reduced the expression of PPAR{gamma}, C/EBP{alpha}, and SREBP1c during the intermediate (D2-D4) and late stages (D4-D7) of differentiation. It also inhibited the uptake of glucose in mature 3T3-L1 adipocytes by reducing the phosphorylation of insulin receptor substrate 1 (IRS-1). These results suggest that fucoxanthin exerts differing effects on 3T3-L1 cells of different differentiation stages and inhibits glucose uptake in mature adipocytes.

  19. Protein phosphorylation in isolated human adipocytes - Adrenergic control of the phosphorylation of hormone-sensitive lipase

    SciTech Connect

    Smiley, R.M. Columbia Univ College of Physicians and Surgeons, New York, NY ); Paul, S.; Browning, M.D.; Leibel, R.L.; Hirsch, J. )

    1990-01-01

    The effect of adrenergic agents on protein phosphorylation in human adipocytes was examined. Freshly isolated human fat cells were incubated with {sup 32}PO{sub 4} in order to label intracellular ATP, then treated with a variety of adrenergic and other pharmacologic agents. Treatment with the {beta}-adrenergic agonist isoproterenol led to a significant increase in phosphate content of at least five protein bands (M{sub r} 52, 53, 63, 67, 84 kDa). The increase in phosphorylation was partially inhibited by the {alpha}-2 agonist clonidine. Epinephrine, a combined {alpha} and {beta} agonist, was less effective at increasing phosphate content of the proteins than was isoproterenol. Neither insulin nor the {alpha}-1 agonist phenylephrine had any discernible effect on the pattern of protein phosphorylation. The 84 kDa phosphorylated peptide band appears to contain hormone-sensitive lipase, a key enzyme in the lipolytic pathway which is activated by phosphorylation. These results are somewhat different than previously reported results for rat adipocytes, and represent the first report of overall pattern and adrenergic modulation of protein phosphorylation in human adipocytes.

  20. RBM4a-regulated splicing cascade modulates the differentiation and metabolic activities of brown adipocytes

    PubMed Central

    Lin, Jung-Chun; Lu, Yi-Han; Liu, Yun-Ru; Lin, Ying-Ju

    2016-01-01

    RNA-binding motif protein 4a (RBM4a) reportedly reprograms splicing profiles of the insulin receptor (IR) and myocyte enhancer factor 2C (MEF2C) genes, facilitating the differentiation of brown adipocytes. Using an RNA-sequencing analysis, we first compared the gene expressing profiles between wild-type and RBM4a−/− brown adipocytes. The ablation of RBM4a led to increases in the PTBP1, PTBP2 (nPTB), and Nova1 proteins, whereas elevated RBM4a reduced the expression of PTBP1 and PTBP2 proteins in brown adipocytes through an alternative splicing-coupled nonsense-mediated decay mechanism. Subsequently, RBM4a indirectly shortened the half-life of the Nova1 transcript which was comparatively stable in the presence of PTBP2. RBM4a diminished the influence of PTBP2 in adipogenic development by reprogramming the splicing profiles of the FGFR2 and PKM genes. These results constitute a mechanistic understanding of the RBM4a-modulated splicing cascade during the brown adipogenesis. PMID:26857472

  1. Fucoxanthinol, Metabolite of Fucoxanthin, Improves Obesity-Induced Inflammation in Adipocyte Cells

    PubMed Central

    Maeda, Hayato; Kanno, Shogo; Kodate, Mei; Hosokawa, Masashi; Miyashita, Kazuo

    2015-01-01

    Fucoxanthin (Fx) is a marine carotenoid found in edible brown seaweeds. We previously reported that dietary Fx metabolite into fucoxanthinol (FxOH), attenuates the weight gain of white adipose tissue of diabetic/obese KK-Ay mice. In this study, to evaluate anti-diabetic effects of Fx, we investigated improving the effect of insulin resistance on the diabetic model of KK-Ay mice. Furthermore, preventing the effect of FxOH on low-grade chronic inflammation related to oxidative stress was evaluated on 3T3-L1 adipocyte cells and a RAW264.7 macrophage cell co-culture system. A diet containing 0.1% Fx was fed to diabetic model KK-Ay mice for three weeks, then glucose tolerance was observed. Fx diet significantly improved glucose tolerance compared with the control diet group. In in vitro studies, FxOH showed suppressed tumor necrosis factor-α (TNF-α), and monocyte chemotactic protein-1 (MCP-1) mRNA expression and protein levels in a co-culture of adipocyte and macrophage cells. These findings suggest that Fx ameliorates glucose tolerance in the diabetic model mice. Furthermore, FxOH, a metabolite of Fx, suppresses low-grade chronic inflammation in adipocyte cells. PMID:26248075

  2. Extract of Chaga mushroom (Inonotus obliquus) stimulates 3T3-L1 adipocyte differentiation.

    PubMed

    Joo, Jeong In; Kim, Dong Hyun; Yun, Jong Won

    2010-11-01

    Chaga mushroom (Inonotus obliquus) has long been used as a folk medicine due to its numerous biological functions such as antibacterial, antiallergic, antiinflammatory and antioxidative activities. In the present study, it was found that the I. obliquus hot water extract (IOWE) activated adipogenesis of 3T3-L1 preadipocytes. Even in the absence of adipogenic stimuli by insulin, the IOWE strongly induced adipogenesis of 3T3-L1 preadipocytes. The major constituent of IOWE was glucose-rich polysaccharides with a molecular mass of 149  kDa. IOWE enhanced the differentiation of 3T3-L1 preadipocytes, increasing TG (triacylglycerol) accumulation that is critical for acquisition of the adipocyte phenotype, in a dose-dependent manner. IOWE stimulated gene expression of C/EBPα (CCAAT/enhancer-binding protein α) and PPARγ (peroxisome proliferator-activated receptors γ) during adipocyte differentiation, and induced the expression of PPARγ target genes such as aP2 (adipocyte protein 2), LPL (lipoprotein lipase) and CD36 (fatty acid translocase). Immunoblot analysis revealed that IOWE increased the expression of adipogenic makers such as PPARγ and GLUT4 (glucose transporter 4). The luciferase reporter assay demonstrated that IOWE did not exhibit PPARγ ligand activity. Although these results require further investigation, the ability of natural mushroom product to increase PPARγ transcriptional activities may be expected to be therapeutic targets for dyslipidemia and type 2 diabetes.

  3. Prednisolone induces the Wnt signalling pathway in 3T3-L1 adipocytes.

    PubMed

    Fleuren, Wilco W M; Linssen, Margot M L; Toonen, Erik J M; van der Zon, Gerard C M; Guigas, Bruno; de Vlieg, Jacob; Dokter, Wim H A; Ouwens, D Margriet; Alkema, Wynand

    2013-05-01

    Synthetic glucocorticoids are potent anti-inflammatory drugs but show dose-dependent metabolic side effects such as the development of insulin resistance and obesity. The precise mechanisms involved in these glucocorticoid-induced side effects, and especially the participation of adipose tissue in this are not completely understood. We used a combination of transcriptomics, antibody arrays and bioinformatics approaches to characterize prednisolone-induced alterations in gene expression and adipokine secretion, which could underlie metabolic dysfunction in 3T3-L1 adipocytes. Several pathways, including cytokine signalling, Akt signalling, and Wnt signalling were found to be regulated at multiple levels, showing that these processes are targeted by prednisolone. These results suggest that mechanisms by which prednisolone induce insulin resistance include dysregulation of wnt signalling and immune response processes. These pathways may provide interesting targets for the development of improved glucocorticoids.

  4. Prednisolone induces the Wnt signalling pathway in 3T3-L1 adipocytes

    PubMed Central

    Fleuren, Wilco W. M.; Linssen, Margot M. L.; Toonen, Erik J. M.; van der Zon, Gerard C. M.; Guigas, Bruno; de Vlieg, Jacob; Dokter, Wim H. A.; Ouwens, D. Margriet

    2013-01-01

    Synthetic glucocorticoids are potent anti-inflammatory drugs but show dose-dependent metabolic side effects such as the development of insulin resistance and obesity. The precise mechanisms involved in these glucocorticoid-induced side effects, and especially the participation of adipose tissue in this are not completely understood. We used a combination of transcriptomics, antibody arrays and bioinformatics approaches to characterize prednisolone-induced alterations in gene expression and adipokine secretion, which could underlie metabolic dysfunction in 3T3-L1 adipocytes. Several pathways, including cytokine signalling, Akt signalling, and Wnt signalling were found to be regulated at multiple levels, showing that these processes are targeted by prednisolone. These results suggest that mechanisms by which prednisolone induce insulin resistance include dysregulation of wnt signalling and immune response processes. These pathways may provide interesting targets for the development of improved glucocorticoids. PMID:23506355

  5. Characterization of GTP-binding proteins in Golgi-associated membrane vesicles from rat adipocytes.

    PubMed Central

    Schürmann, A; Rosenthal, W; Schultz, G; Joost, H G

    1992-01-01

    We have previously reported that guanine nucleotides inhibit glucose transport activity reconstituted from adipocyte membrane fractions. In order to further investigate the hypothetical involvement of guanine-nucleotide-binding proteins (GTP-binding proteins) in the regulation of insulin-sensitive glucose transport activity, we studied their subcellular distribution in adipocytes treated or not with insulin. Adipocytes were homogenized and fractionated to yield plasma membranes (PM) and a Golgi-enriched fraction of intracellular membranes (low-density microsomes, LDM). In these membrane fractions, total guanosine 5'-[gamma-[35S]thio]triphosphate ([35S]GTP[S]) binding, alpha- and beta-subunits of heterotrimeric G-proteins, proto-oncogenes Ha-ras and K-ras, and 23-28 kDa GTP-binding proteins were assayed. The levels of alpha s and alpha i (the alpha-subunits of Gs and Gi) were approx. 8-fold lower in LDM than in PM; beta-subunits, Ha-ras and K-ras were not detectable in LDM. Total GTP[S]-binding sites and 23-28 kDa GTP-binding proteins were present in LDM in approximately the same concentrations as in PM. Insulin gave rise to the characteristic translocation of glucose transporters, but failed to alter the subcellular distribution of any of the GTP-binding proteins. Fractionation of the LDM on a discontinuous sucrose gradient revealed that alpha s and alpha i, as detected with antiserum against a common peptide sequence (alpha common), and the bulk of the 23-28 kDa G-proteins sedimented at different sucrose densities. None of the GTP-binding proteins co-sedimented with glucose transporters. Furthermore, the inhibitory effect of GTP[S] on the reconstituted transport activity was lost in the peak fractions of glucose transporters partially purified on the sucrose gradient. These data indicate that LDM from adipocytes contain several GTP-binding proteins in discrete vesicle populations. However, the intracellular GTP-binding proteins are not tightly associated with the

  6. Chilean native fruit extracts inhibit inflammation linked to the pathogenic interaction between adipocytes and macrophages.

    PubMed

    Reyes-Farias, Marjorie; Vasquez, Karla; Ovalle-Marin, Angelica; Fuentes, Francisco; Parra, Claudia; Quitral, Vilma; Jimenez, Paula; Garcia-Diaz, Diego F

    2015-05-01

    Obesity is characterized by an increase in the infiltration of monocytes into the adipose tissue, causing an inflammatory condition associated with, for example, the development of insulin resistance. Thus, anti-inflammatory-based treatments could emerge as a novel and interesting approach. It has been reported that Chilean native fruits maqui (Aristotelia chilensis) and calafate (Berberis microphylla) present high contents of polyphenols, which are known for their antioxidant and anti-inflammatory properties. The aim of this study was to evaluate the ability of extracts of these fruits to block the pathogenic interaction between adipocytes and macrophages in vitro and to compare its effect with blueberry (Vaccinium corymbosum) extract treatment, which has been already described to possess several biomedical benefits. RAW264.7 macrophages were treated with 5 μg/mL lipopolysaccharides (LPS), with conditioned media (CM) from fully differentiated 3T3-L1 adipocytes, or in a coculture (CC) with 3T3-L1 adipocytes, in the presence or absence of 100 μM [total polyphenolic content] of each extract for 24 h. The gene expression and secretion profile of several inflammatory markers were evaluated. Nitric oxide secretion induced by LPS, CM, and CC was reduced by the presence of maqui (-12.2%, -45.6%, and -14.7%, respectively) and calafate (-27.6%, -43.9%, and -11.8%, respectively) extracts. Gene expression of inducible nitric oxide synthase and TNF-α was inhibited and of IL-10 was induced by maqui and calafate extract incubation. In conclusion, the extracts of these fruits present important inhibitory-like features over the inflammatory response of the interaction between adipocytes and macrophages, comprising a potential therapeutic tool against comorbidities associated with obesity development.

  7. Polymerase I and transcript release factor (PTRF) regulates adipocyte differentiation and determines adipose tissue expandability

    PubMed Central

    Perez-Diaz, Sergio; Johnson, Lance A.; DeKroon, Robert M.; Moreno-Navarrete, Jose M.; Alzate, Oscar; Fernandez-Real, Jose M.; Maeda, Nobuyo; Arbones-Mainar, Jose M.

    2014-01-01

    Impaired adipogenesis renders an adipose tissue unable to expand, leading to lipotoxicity and conditions such as diabetes and cardiovascular disease. While factors important for adipogenesis have been studied extensively, those that set the limits of adipose tissue expansion remain undetermined. Feeding a Western-type diet to apolipoprotein E2 knock-in mice, a model of metabolic syndrome, produced 3 groups of equally obese mice: mice with normal glucose tolerance, hyperinsulinemic yet glucose-tolerant mice, and prediabetic mice with impaired glucose tolerance and reduced circulating insulin. Using proteomics, we compared subcutaneous adipose tissues from mice in these groups and found that the expression of PTRF (polymerase I and transcript release factor) associated selectively with their glucose tolerance status. Lentiviral and pharmacologically overexpressed PTRF, whose function is critical for caveola formation, compromised adipocyte differentiation of cultured 3T3-L1cells. In human adipose tissue, PTRF mRNA levels positively correlated with markers of lipolysis and cellular senescence. Furthermore, a negative relationship between telomere length and PTRF mRNA levels was observed in human subcutaneous fat. PTRF is associated with limited adipose tissue expansion underpinning the key role of caveolae in adipocyte regulation. Furthermore, PTRF may be a suitable adipocyte marker for predicting pathological obesity and inform clinical management.—Perez-Diaz, S., Johnson, L. A., DeKroon, R. M., Moreno-Navarrete, J. M., Alzate, O., Fernandez-Real, J. M., Maeda, N., Arbones-Mainar, J. M. Polymerase I and transcript release factor (PTRF) regulates adipocyte differentiation and determines adipose tissue expandability. PMID:24812087

  8. Chilean Native Fruit Extracts Inhibit Inflammation Linked to the Pathogenic Interaction Between Adipocytes and Macrophages

    PubMed Central

    Reyes-Farias, Marjorie; Vasquez, Karla; Ovalle-Marin, Angelica; Fuentes, Francisco; Parra, Claudia; Quitral, Vilma; Jimenez, Paula

    2015-01-01

    Abstract Obesity is characterized by an increase in the infiltration of monocytes into the adipose tissue, causing an inflammatory condition associated with, for example, the development of insulin resistance. Thus, anti-inflammatory-based treatments could emerge as a novel and interesting approach. It has been reported that Chilean native fruits maqui (Aristotelia chilensis) and calafate (Berberis microphylla) present high contents of polyphenols, which are known for their antioxidant and anti-inflammatory properties. The aim of this study was to evaluate the ability of extracts of these fruits to block the pathogenic interaction between adipocytes and macrophages in vitro and to compare its effect with blueberry (Vaccinium corymbosum) extract treatment, which has been already described to possess several biomedical benefits. RAW264.7 macrophages were treated with 5 μg/mL lipopolysaccharides (LPS), with conditioned media (CM) from fully differentiated 3T3-L1 adipocytes, or in a coculture (CC) with 3T3-L1 adipocytes, in the presence or absence of 100 μM [total polyphenolic content] of each extract for 24 h. The gene expression and secretion profile of several inflammatory markers were evaluated. Nitric oxide secretion induced by LPS, CM, and CC was reduced by the presence of maqui (−12.2%, −45.6%, and −14.7%, respectively) and calafate (−27.6%, −43.9%, and −11.8%, respectively) extracts. Gene expression of inducible nitric oxide synthase and TNF-α was inhibited and of IL-10 was induced by maqui and calafate extract incubation. In conclusion, the extracts of these fruits present important inhibitory-like features over the inflammatory response of the interaction between adipocytes and macrophages, comprising a potential therapeutic tool against comorbidities associated with obesity development. PMID:25302660

  9. Enhanced accumulation of adipocytes in bone marrow stromal cells in the presence of increased extracellular and intracellular [Ca{sup 2+}

    SciTech Connect

    Hashimoto, Ryota; Katoh, Youichi; Nakamura, Kyoko; Itoh, Seigo; Iesaki, Takafumi; Daida, Hiroyuki; Nakazato, Yuji; Okada, Takao

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer High [Ca{sup 2+}]{sub o} enhances adipocyte accumulation in the presence of adipogenic inducers. Black-Right-Pointing-Pointer High [Ca{sup 2+}]{sub o} enhances both proliferation and adipocyte differentiation in BMSCs. Black-Right-Pointing-Pointer High [Ca{sup 2+}]{sub o} induces an increase in [Ca{sup 2+}]{sub o} in BMSCs. Black-Right-Pointing-Pointer An intracellular Ca{sup 2+} chelator suppresses the enhancement in adipocyte accumulation. Black-Right-Pointing-Pointer Controlling [Ca{sup 2+}]{sub o} may govern the balance of adipocyte and osteoblast development. -- Abstract: The bone marrow stroma contains osteoblasts and adipocytes that have a common precursor: the pluripotent mesenchymal stem cell found in bone marrow stromal cells (BMSCs). Local bone marrow Ca{sup 2+} levels can reach high concentrations due to bone resorption, which is one of the notable features of the bone marrow stroma. Here, we describe the effects of high [Ca{sup 2+}]{sub o} on the accumulation of adipocytes in the bone marrow stroma. Using primary mouse BMSCs, we evaluated the level of adipocyte accumulation by measuring Oil Red O staining and glycerol-3-phosphate dehydrogenase (GPDH) activity. High [Ca{sup 2+}]{sub o} enhanced the accumulation of adipocytes following treatment with both insulin and dexamethasone together but not in the absence of this treatment. This enhanced accumulation was the result of both the accelerated proliferation of BMSCs and their differentiation into adipocytes. Using the fura-2 method, we also showed that high [Ca{sup 2+}]{sub o} induces an increase in [Ca{sup 2+}]{sub i}. An intracellular Ca{sup 2+} chelator suppressed the enhancement in adipocyte accumulation due to increased [Ca{sup 2+}]{sub o} in BMSCs. These data suggest a new role for extracellular Ca{sup 2+} in the bone marrow stroma: increased [Ca{sup 2+}]{sub o} induces an increase in [Ca{sup 2+}]{sub i} levels, which in turn enhances the accumulation of

  10. Quercetin, a functional compound of onion peel, remodels white adipocytes to brown-like adipocytes.

    PubMed

    Lee, Sang Gil; Parks, John S; Kang, Hye Won

    2017-04-01

    Adipocyte browning is a promising strategy for obesity prevention. Using onion-peel-derived extracts and their bioactive compounds, we demonstrate that onion peel, a by-product of onion, can change the characteristics of white adipocytes to those of brown-like adipocytes in the white adipose tissue of mice and 3T3-L1 cells. The expression of the following brown adipose tissue-specific genes was increased in the retroperitoneal and subcutaneous adipose tissues of 0.5% onion-peel-extract-fed mice: PR domain-containing 16, peroxisome proliferator-activated receptor gamma coactivator 1α, uncoupling protein 1, fibroblast growth factor 21 and cell death-inducing DFFA-like effector. In 3T3-L1 adipocytes, onion peel extract induced the expression of brown adipose tissue-specific genes and increased the expression of carnitine palmitoyltransferase 1α. This effect was supported by decreased lipid levels and multiple small-sized lipid droplets. The ethyl acetate fraction of the onion peel extract that contained the highest proportion of hydrophobic molecules showed the same browning effect in 3T3-L1 adipocytes. A high-performance liquid chromatography analysis further identified quercetin as a functional compound in the browning effect of onion peel. The quercetin-associated browning effect was mediated in part by the activation of AMP-activated protein kinase. In summary, our study provides the first demonstration of the browning effects of onion peel and quercetin using both animal and cell models. This result indicates that onion peel has the potential to remodel the characteristics of white adipocytes to those of brown-like adipocytes.

  11. 10e12z CLA alters adipocyte differentiation and adipocyte cytokine expression and induces macrophage proliferation.

    PubMed

    Belda, Benjamin J; Thompson, Jerry T; Eser, Pinar O; Vanden Heuvel, John P

    2012-05-01

    The trans-10, cis-12 (10e12z) conjugated linoleic acid (CLA) isomer of CLA is responsible for loss of lipid storage or adipose tissue in vitro or in vivo. This isomer also induces inflammatory signaling in both mouse and human adipocytes in vitro. However, when these events occur and whether they are significant enough to affect other cell types are unclear. In these experiments, the 3T3-L1 cell line has been used to examine the interaction between inflammatory signaling and decreased differentiation or lipid storage induced by 10e12z CLA. In assays measuring both lipid accumulation and gene expression, differentiating 3T3-L1 cells exhibit concurrent induction of inflammatory signaling, as measured by cyclooxygenase-2 expression, and a decrease in adipocyte marker gene expression. Furthermore, in fully differentiated adipocytes, as identified in microarray assays and confirmed with real-time polymerase chain reaction, 10e12z CLA also significantly affected expression of both matrix metalloprotein-3 (MMP-3), collagen VI α 3 ColVI alpha 3 (VIα3) and the cytokine epiregulin, demonstrating that the effects of 10e12z broadly impact adipocyte function. In agreement with other experimental systems, 10e12z CLA inhibited RAW 264.7 cell proliferation; however, in response to adipocyte-conditioned media, 10e12z-CLA-treated adipocytes induced proliferation of this cell line, suggesting that the effect of 10e12z CLA is context dependent. These results are largely consistent with the known activation of the inflammatory mediator nuclear factor-κB in adipocytes in vitro and in vivo by 10e12z CLA treatment and demonstrate that adipose is an important target tissue of this isomer that impacts other cell types.

  12. Fructose consumption and moderate zinc deficiency influence growth and adipocyte metabolism in young rats prone to adult-onset obesity.

    PubMed

    Streiff, Erin L; Stanhope, Kimber L; Graham, James; Havel, Peter J; King, Janet C

    2007-07-01

    The effects of low zinc, high fructose diet on growth and adipocyte metabolism were examined in rats. At 28 days of age, animals were assigned to diets either adequate in zinc (30 ppm) with water (AZW) or fructose solution (AZF), or low in zinc (5 ppm) with water (LZW) or fructose solution (LZF). Body weight and food and fructose solution intake were measured three times a week. Blood samples were collected at baseline, 4 weeks, and 8 weeks, and energy expenditure was measured. The rats were killed at 12 weeks. Adipocytes were cultured in medium containing C14-glucose and physiological insulin concentrations. The animals in the LZF group consumed less energy and gained less weight than the other groups. Serum zinc concentrations were lower in the LZF than the AZF group. Energy expenditure over a 24-h period did not differ between groups; however, the respiratory quotient in the fed state was higher in the groups consuming fructose solution than in those consuming water. The mesenteric adipocytes from the animals in the LZF group utilized more glucose. Thus, the addition of fructose to a LZ diet reduced energy intake and growth and altered adipocyte fuel metabolism in young growing rats.

  13. Digitonin abolishes free 2-deoxy-D-glucose accumulation in isolated rat adipocytes

    SciTech Connect

    Thompson, K.; Kleinzeller, A.

    1986-03-05

    The hypothesis that accumulation against sizable chemical gradients of free (non-phosphorylated) 2-deoxy-D-glucose (2dGlc) in isolated rat adipocytes results from an intracellular compartmentation of free hexose was investigated. Cells exposed to 20 ..mu..g/ml digitonin for 10' demonstrated an increased plasma membrane permeability indexed by increased L-glucose entry rates and cellular (presumably cytosolic) protein and K/sup +/ loss. Functional integrity of intracellular organelles was indicated by the ability of the cells to support ATP-driven /sup 45/Ca/sup 2 +/-uptake. Equilibrium 3-O-methylglucose (3-O-MG, a non-accumulated hexose) levels were unaffected. These data suggest a specific permeabilizing action of digitonin at the plasma membrane having no effect on intracellular organelles or passively distributed solutes. Upon addition of digitonin, free 2dGlc fell from 66.5 +/- 8.9 to 7.4 +/- 2.3 pmol/10/sup 5/ cells, a value not significantly different from 3-O-MG levels. The gradient of 2dGlc-phosphate was also abolished, as was the increased steady-state free 2dGlc levels induced by insulin. The data argue against a compartmentation model as either the mechanism of adipocyte sugar accumulation or the basis of the steady-state free 2dGlc increase seen with insulin and suggest that an intact plasma membrane is essential to the process.

  14. G Protein–Coupled Receptor Kinase 2 Plays a Relevant Role in Insulin Resistance and Obesity

    PubMed Central

    Garcia-Guerra, Lucia; Nieto-Vazquez, Iria; Vila-Bedmar, Rocio; Jurado-Pueyo, María; Zalba, Guillermo; Díez, Javier; Murga, Cristina; Fernández-Veledo, Sonia; Mayor, Federico; Lorenzo, Margarita

    2010-01-01

    OBJECTIVE Insulin resistance is associated with the pathogenesis of metabolic disorders as type 2 diabetes and obesity. Given the emerging role of signal transduction in these syndromes, we set out to explore the possible role that G protein–coupled receptor kinase 2 (GRK2), first identified as a G protein–coupled receptor regulator, could have as a modulator of insulin responses. RESEARCH DESIGN AND METHODS We analyzed the influence of GRK2 levels in insulin signaling in myoblasts and adipocytes with experimentally increased or silenced levels of GRK2, as well as in GRK2 hemizygous animals expressing 50% lower levels of this kinase in three different models of insulin resistance: tumor necrosis factor-α (TNF-α) infusion, aging, and high-fat diet (HFD). Glucose transport, whole-body glucose and insulin tolerance, the activation status of insulin pathway components, and the circulating levels of important mediators were measured. The development of obesity and adipocyte size with age and HFD was analyzed. RESULTS Altering GRK2 levels markedly modifies insulin-mediated signaling in cultured adipocytes and myocytes. GRK2 levels are increased by ∼2-fold in muscle and adipose tissue in the animal models tested, as well as in lymphocytes from metabolic syndrome patients. In contrast, hemizygous GRK2 mice show enhanced insulin sensitivity and do not develop insulin resistance by TNF-α, aging, or HFD. Furthermore, reduced GRK2 levels induce a lean phenotype and decrease age-related adiposity. CONCLUSIONS Overall, our data identify GRK2 as an important negative regulator of insulin effects, key to the etiopathogenesis of insulin resistance and obesity, which uncovers this protein as a potential therapeutic target in the treatment of these disorders. PMID:20627936

  15. Computed tomography-measured adipose tissue attenuation and area both predict adipocyte size and cardiometabolic risk in women

    PubMed Central

    Côté, Julie Anne; Nazare, Julie-Anne; Nadeau, Mélanie; Leboeuf, Mathieu; Blackburn, Line; Després, Jean-Pierre; Tchernof, André

    2016-01-01

    abstract Objective: To assess the ability of CT-derived measurements including adipose tissue attenuation and area to predict fat cell hypertrophy and related cardiometabolic risk. Methods: Abdominal adipose tissue areas and radiologic attenuation were assessed using 4 CT images in 241 women (age: 47 years, BMI: 26.5 kg/m2). Fat cell weight was measured in paired VAT and SAT samples. Fasting plasma lipids, glucose and insulin levels were measured. Results: Adipose tissue attenuation was negatively correlated with SAT (r=-0.46) and VAT (r=-0.67) fat cell weight in the corresponding depot (p<0.0001 for both). Women with visceral adipocyte hypertrophy had higher total-, VLDL-, LDL- and HDL-triglyceride and apoB levels as well as a higher cholesterol/HDL-cholesterol ratio, fasting glucose and insulin levels compared to women with smaller visceral adipocytes. Adjustment for VAT area minimized these differences while subsequent adjustment for attenuation eliminated all differences, with the exception of fasting glycaemia. In SAT, adjustment for VAT area and attenuation eliminated all adipocyte hypertrophy-related alterations except for fasting hyperglycaemia. Conclusion: CT-derived adipose tissue attenuation and area both contribute to explain variation in the cardiometabolic risk profile associated with the same biological parameter: visceral fat cell hypertrophy. PMID:27144095

  16. Oxygen deprivation and the cellular response to hypoxia in adipocytes - perspectives on white and brown adipose tissues in obesity.

    PubMed

    Trayhurn, Paul; Alomar, Suliman Yousef

    2015-01-01

    Relative hypoxia has been shown to develop in white adipose tissue depots of different types of obese mouse (genetic, dietary), and this leads to substantial changes in white adipocyte function. These changes include increased production of inflammation-related adipokines (such as IL-6, leptin, Angptl4, and VEGF), an increase in glucose utilization and lactate production, and the induction of fibrosis and insulin resistance. Whether hypoxia also occurs in brown adipose tissue depots in obesity has been little considered. However, a recent study has reported low pO2 in brown fat of obese mice, this involving mitochondrial loss and dysfunction. We suggest that obesity-linked hypoxia may lead to similar alterations in brown adipocytes as in white fat cells - particularly changes in adipokine production, increased glucose uptake and lactate release, and insulin resistance. This would be expected to compromise thermogenic activity and the role of brown fat in glucose homeostasis and triglyceride clearance, underpinning the development of the metabolic syndrome. Hypoxia-induced augmentation of lactate production may also stimulate the "browning" of white fat depots through recruitment of UCP1 and the development of brite adipocytes.

  17. Insulin/IGF signaling in Drosophila and other insects: factors that regulate production, release and post-release action of the insulin-like peptides.

    PubMed

    Nässel, Dick R; Vanden Broeck, Jozef

    2016-01-01

    Insulin, insulin-like growth factors (IGFs) and insulin-like peptides (ILPs) are important regulators of metabolism, growth, reproduction and lifespan, and mechanisms of insulin/IGF signaling (IIS) have been well conserved over evolution. In insects, between one and 38 ILPs have been identified in each species. Relatively few insect species have been investigated in depth with respect to ILP functions, and therefore we focus mainly on the well-studied fruitfly Drosophila melanogaster. In Drosophila eight ILPs (DILP1-8), but only two receptors (dInR and Lgr3) are known. DILP2, 3 and 5 are produced by a set of neurosecretory cells (IPCs) in the brain and their biosynthesis and release are controlled by a number of mechanisms differing between larvae and adults. Adult IPCs display cell-autonomous sensing of circulating glucose, coupled to evolutionarily conserved mechanisms for DILP release. The glucose-mediated DILP secretion is modulated by neurotransmitters and neuropeptides, as well as by factors released from the intestine and adipocytes. Larval IPCs, however, are indirectly regulated by glucose-sensing endocrine cells producing adipokinetic hormone, or by circulating factors from the intestine and fat body. Furthermore, IIS is situated within a complex physiological regulatory network that also encompasses the lipophilic hormones, 20-hydroxyecdysone and juvenile hormone. After release from IPCs, the ILP action can be modulated by circulating proteins that act either as protective carriers (binding proteins), or competitive inhibitors. Some of these proteins appear to have additional functions that are independent of ILPs. Taken together, the signaling with multiple ILPs is under complex control, ensuring tightly regulated IIS in the organism.

  18. Insulin resistance and white adipose tissue inflammation are uncoupled in energetically challenged Fsp27-deficient mice.

    PubMed

    Zhou, Linkang; Park, Shi-Young; Xu, Li; Xia, Xiayu; Ye, Jing; Su, Lu; Jeong, Kyeong-Hoon; Hur, Jang Ho; Oh, Hyunhee; Tamori, Yoshikazu; Zingaretti, Cristina M; Cinti, Saverio; Argente, Jesús; Yu, Miao; Wu, Lizhen; Ju, Shenghong; Guan, Feifei; Yang, Hongyuan; Choi, Cheol Soo; Savage, David B; Li, Peng

    2015-01-07

    Fsp27 is a lipid droplet-associated protein almost exclusively expressed in adipocytes where it facilitates unilocular lipid droplet formation. In mice, Fsp27 deficiency is associated with increased basal lipolysis, 'browning' of white fat and a healthy metabolic profile, whereas a patient with congenital CIDEC deficiency manifested an adverse lipodystrophic phenotype. Here we reconcile these data by showing that exposing Fsp27-null mice to a substantial energetic stress by crossing them with ob/ob mice or BATless mice, or feeding them a high-fat diet, results in hepatic steatosis and insulin resistance. We also observe a striking reduction in adipose inflammation and increase in adiponectin levels in all three models. This appears to reflect reduced activation of the inflammasome and less adipocyte death. These findings highlight the importance of Fsp27 in facilitating optimal energy storage in adipocytes and represent a rare example where adipose inflammation and hepatic insulin resistance are disassociated.

  19. Insulin resistance and white adipose tissue inflammation are uncoupled in energetically challenged Fsp27-deficient mice

    PubMed Central

    Zhou, Linkang; Park, Shi-Young; Xu, Li; Xia, Xiayu; Ye, Jing; Su, Lu; Jeong, Kyeong-Hoon; Hur, Jang Ho; Oh, Hyunhee; Tamori, Yoshikazu; Zingaretti, Cristina M.; Cinti, Saverio; Argente, Jesús; Yu, Miao; Wu, Lizhen; Ju, Shenghong; Guan, Feifei; Yang, Hongyuan; Choi, Cheol Soo; Savage, David B.; Li, Peng

    2015-01-01

    Fsp27 is a lipid droplet-associated protein almost exclusively expressed in adipocytes where it facilitates unilocular lipid droplet formation. In mice, Fsp27 deficiency is associated with increased basal lipolysis, ‘browning’ of white fat and a healthy metabolic profile, whereas a patient with congenital CIDEC deficiency manifested an adverse lipodystrophic phenotype. Here we reconcile these data by showing that exposing Fsp27-null mice to a substantial energetic stress by crossing them with ob/ob mice or BATless mice, or feeding them a high-fat diet, results in hepatic steatosis and insulin resistance. We also observe a striking reduction in adipose inflammation and increase in adiponectin levels in all three models. This appears to reflect reduced activation of the inflammasome and less adipocyte death. These findings highlight the importance of Fsp27 in facilitating optimal energy storage in adipocytes and represent a rare example where adipose inflammation and hepatic insulin resistance are disassociated. PMID:25565658

  20. Chronic insulin effects on insulin signalling and GLUT4 endocytosis are reversed by metformin.

    PubMed Central

    Pryor, P R; Liu, S C; Clark, A E; Yang, J; Holman, G D; Tosh, D

    2000-01-01

    Decreases in insulin-responsive glucose transport and associated levels of cell surface GLUT4 occur in rat adipocytes maintained in culture for 20 h under hyperinsulinaemic and hyperglycaemic conditions. We have investigated whether this defect is due to reduced signalling from the insulin receptor, GLUT4 expression or impaired GLUT4 trafficking. The effects of chronic insulin treatment on glucose transport and GLUT4 trafficking were ameliorated by inclusion of metformin in the culture medium. In comparison with the ic insulin treatment attenuated changes in signalling processes leading to glucose transport. These included insulin receptor tyrosine phosphorylation, phosphoinositide 3-kinase activity and Akt activity, which were all reduced by 60-70%. Inclusion of metformin in the culture medium prevented the effects of the chronic insulin treatment on these signalling processes. In comparison with cells maintained in culture without insulin, the total expression of GLUT4 protein was not significantly altered by chronic insulin treatment, although the level of GLUT1 expression was increased. Trafficking rate constants for wortmannin-induced cell-surface loss of GLUT4 and GLUT1 were assessed by 2-N-4-(1-azi-2, 2,2-trifluoroethyl)benzoyl-1,3-bis(D-mannose-4-yloxy)-2-propyla min e (ATB-BMPA) photolabelling. In comparison with cells acutely treated with insulin, chronic insulin treatment resulted in a doubling of the rate constants for GLUT4 endocytosis. These results suggest that the GLUT4 endocytosis process is very sensitive to the perturbations in signalling that occur under hyperinsulinaemic and hyperglycaemic conditions, and that the resulting elevation of endocytosis accounts for the reduced levels of net GLUT4 translocation observed. PMID:10794717

  1. [Obesity, inflammation and insulin resistance: which role for adipokines].

    PubMed

    Antuna-Puente, Barbara; Feve, Bruno; Fellahi, Soraya; Bastard, Jean-Philippe

    2007-01-01

    Adipose tissue is now recognized as an endocrine organ involved in regulating physiologic and pathologic processes including inflammation. It synthesizes and secretes hormones such as leptin and adiponectin. It can secrete other products namely adipokines including cytokines and chemokines. The release of adipokines by either adipocytes or adipose tissue-infiltrated macrophages leads to a chronic sub-inflammatory state that likely plays a major role in cardiovascular complications linked to obesity and insulin resistance.

  2. Berberine stimulates glucose transport through a mechanism distinct from insulin.

    PubMed

    Zhou, Libin; Yang, Ying; Wang, Xiao; Liu, Shangquan; Shang, Wenbin; Yuan, Guoyue; Li, Fengying; Tang, Jinfeng; Chen, Mingdao; Chen, Jialun

    2007-03-01

    Berberine exerts a hypoglycemic effect, but the mechanism remains unknown. In the present study, the effect of berberine on glucose uptake was characterized in 3T3-L1 adipocytes. It was revealed that berberine stimulated glucose uptake in 3T3-L1 adipocytes in a dose- and time-dependent manner with the maximal effect at 12 hours. Glucose uptake was increased by berberine in 3T3-L1 preadipocytes as well. Berberine-stimulated glucose uptake was additive to that of insulin in 3T3-L1 adipocytes, even at the maximal effective concentrations of both components. Unlike insulin, the effect of berberine on glucose uptake was insensitive to wortmannin, an inhibitor of phosphatidylinositol 3-kinase, and SB203580, an inhibitor of p38 mitogen-activated protein kinase. Berberine activated extracellular signal-regulated kinase (ERK) 1/2, but PD98059, an ERK kinase inhibitor, only decreased berberine-stimulated glucose uptake by 32%. Berberine did not induce Ser473 phosphorylation of Akt nor enhance insulin-induced phosphorylation of Akt. Meanwhile, the expression and cellular localization of glucose transporter 4 (GLUT4) were not altered by berberine. Berberine did not increase GLUT1 gene expression. However, genistein, a tyrosine kinase inhibitor, completely blocked berberine-stimulated glucose uptake in 3T3-L1 adipocytes and preadipocytes, suggesting that berberine may induce glucose transport via increasing GLUT1 activity. In addition, berberine increased adenosine monophosphate-activated protein kinase and acetyl-coenzyme A carboxylase phosphorylation. These findings suggest that berberine increases glucose uptake through a mechanism distinct from insulin, and activated adenosine monophosphate-activated protein kinase seems to be involved in the metabolic effect of berberine.

  3. Cross-talks via mTORC2 can explain enhanced activation in response to insulin in diabetic patients

    PubMed Central

    Magnusson, Rasmus; Gustafsson, Mika; Cedersund, Gunnar; Strålfors, Peter

    2016-01-01

    The molecular mechanisms of insulin resistance in Type 2 diabetes have been extensively studied in primary human adipocytes, and mathematical modelling has clarified the central role of attenuation of mammalian target of rapamycin (mTOR) complex 1 (mTORC1) activity in the diabetic state. Attenuation of mTORC1 in diabetes quells insulin-signalling network-wide, except for the mTOR in complex 2 (mTORC2)-catalysed phosphorylation of protein kinase B (PKB) at Ser473 (PKB-S473P), which is increased. This unique increase could potentially be explained by feedback and interbranch cross-talk signals. To examine if such mechanisms operate in adipocytes, we herein analysed data from an unbiased phosphoproteomic screen in 3T3-L1 adipocytes. Using a mathematical modelling approach, we showed that a negative signal from mTORC1-p70 S6 kinase (S6K) to rictor–mTORC2 in combination with a positive signal from PKB to SIN1–mTORC2 are compatible with the experimental data. This combined cross-branch signalling predicted an increased PKB-S473P in response to attenuation of mTORC1 – a distinguishing feature of the insulin resistant state in human adipocytes. This aspect of insulin signalling was then verified for our comprehensive model of insulin signalling in human adipocytes. Introduction of the cross-branch signals was compatible with all data for insulin signalling in human adipocytes, and the resulting model can explain all data network-wide, including the increased PKB-S473P in the diabetic state. Our approach was to first identify potential mechanisms in data from a phosphoproteomic screen in a cell line, and then verify such mechanisms in primary human cells, which demonstrates how an unbiased approach can support a direct knowledge-based study. PMID:27986865

  4. Models of lipid droplets growth and fission in adipocyte cells

    SciTech Connect

    Boschi, Federico; Rizzatti, Vanni; Zamboni, Mauro; Sbarbati, Andrea

    2015-08-15

    Lipid droplets (LD) are spherical cellular inclusion devoted to lipids storage. It is well known that excessive accumulation of lipids leads to several human worldwide diseases like obesity, type 2 diabetes, hepatic steatosis and atherosclerosis. LDs' size range from fraction to one hundred of micrometers in adipocytes and is related to the lipid content, but their growth is still a puzzling question. It has been suggested that LDs can grow in size due to the fusion process by which a larger LD is obtained by the merging of two smaller LDs, but these events seems to be rare and difficult to be observed. Many other processes are thought to be involved in the number and growth of LDs, like the de novo formation and the growth through additional neutral lipid deposition in pre-existing droplets. Moreover the number and size of LDs are influenced by the catabolism and the absorption or interaction with other organelles. The comprehension of these processes could help in the confinement of the pathologies related to lipid accumulation. In this study the LDs' size distribution, number and the total volume of immature (n=12), mature (n=12, 10-days differentiated) and lipolytic (n=12) 3T3-L1 adipocytes were considered. More than 11,000 LDs were measured in the 36 cells after Oil Red O staining. In a previous work Monte Carlo simulations were used to mimic the fusion process alone between LDs. We found that, considering the fusion as the only process acting on the LDs, the size distribution in mature adipocytes can be obtained with numerical simulation starting from the size distribution in immature cells provided a very high rate of fusion events. In this paper Monte Carlo simulations were developed to mimic the interaction between LDs taking into account many other processes in addition to fusion (de novo formation and the growth through additional neutral lipid deposition in pre-existing droplets) in order to reproduce the LDs growth and we also simulated the catabolism

  5. Hyperglycemia and advanced glycosylation end products suppress adipocyte apoE expression: implications for adipocyte triglyceride metabolism.

    PubMed

    Espiritu, Doris Joy; Huang, Zhi Hua; Zhao, Yong; Mazzone, Theodore

    2010-10-01

    Endogenous adipocyte apolipoprotein E (apoE) plays an important role in adipocyte lipoprotein metabolism and lipid flux. A potential role for hyperglycemia in regulating adipocyte apoE expression and triglyceride metabolism was examined. Exposure of adipocytes to high glucose or advanced glycosylation end product-BSA significantly suppressed apoE mRNA and protein levels. This suppression was significantly attenuated by antioxidants or inhibitors of the NF-κB transcription pathway. Hyperglycemia in vivo led to adipose tissue oxidant stress and significant reduction in adipose tissue and adipocyte apoE mRNA level. Incubation with antioxidant in organ culture completely reversed this suppression. Hyperglycemia also reduced adipocyte triglyceride synthesis, and this could be completely reversed by adenoviral-mediated increases in apoE. To more specifically evaluate an in vivo role for adipocyte apoE expression on organismal triglyceride distribution in vivo, WT or apoE knockout (EKO) adipose tissue was transplanted in EKO recipient mice. After 12 wk, WT adipocytes transplanted in EKO mice accumulated more triglyceride compared with transplanted EKO adipocytes. In addition, EKO recipients of WT adipose tissue had reduced hepatic triglyceride content compared with EKO recipients transplanted with EKO adipose tissue. Our results demonstrate that hyperglycemia and advanced glycosylation end products suppress the expression of adipocyte apoE in vitro and in vivo and thereby reduce adipocyte triglyceride synthesis. In vivo results using adipose tissue transplantation suggest that reduction of adipocyte apoE, and subsequent reduction of adipocyte triglyceride accumulation, could influence lipid accumulation in nonadipose tissue.

  6. Effects of parabens on adipocyte differentiation.

    PubMed

    Hu, Pan; Chen, Xin; Whitener, Rick J; Boder, Eric T; Jones, Jeremy O; Porollo, Aleksey; Chen, Jiangang; Zhao, Ling

    2013-01-01

    Parabens are a group of alkyl esters of p-hydroxybenzoic acid that include methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. Paraben esters and their salts are widely used as preservatives in cosmetics, toiletries, food, and pharmaceuticals. Humans are exposed to parabens through the use of such products from dermal contact, ingestion, and inhalation. However, research on the effects of parabens on health is limited, and the effects of parabens on adipogenesis have not been systematically studied. Here, we report that (1) parabens promote adipogenesis (or adipocyte differentiation) in murine 3T3-L1 cells, as revealed by adipocyte morphology, lipid accumulation, and mRNA expression of adipocyte-specific markers; (2) the adipogenic potency of parabens is increased with increasing length of the linear alkyl chain in the following potency ranking order: methyl- < ethyl- < propyl- < butylparaben. The extension of the linear alkyl chain with an aromatic ring in benzylparaben further augments the adipogenic ability, whereas 4-hydroxybenzoic acid, the common metabolite of all parabens, and the structurally related benzoic acid (without the OH group) are inactive in promoting 3T3-L1 adipocyte differentiation; (3) parabens activate glucocorticoid receptor and/or peroxisome proliferator-activated receptor γ in 3T3-L1 preadipocytes; however, no direct binding to, or modulation of, the ligand binding domain of the glucocorticoid receptor by parabens was detected by glucocorticoid receptor competitor assays; and lastly, (4) parabens, butyl- and benzylparaben in particular, also promote adipose conversion of human adipose-derived multipotent stromal cells. Our results suggest that parabens may contribute to obesity epidemic, and the role of parabens in adipogenesis in vivo needs to be examined further.

  7. Myosin IIA participates in docking of Glut4 storage vesicles with the plasma membrane in 3T3-L1 adipocytes

    SciTech Connect

    Chung, Le Thi Kim; Hosaka, Toshio; Harada, Nagakatsu; Jambaldorj, Bayasgalan; Fukunaga, Keiko; Nishiwaki, Yuka; Teshigawara, Kiyoshi; Sakai, Tohru; Nakaya, Yutaka; Funaki, Makoto

    2010-01-01

    In adipocytes and myocytes, insulin stimulation translocates glucose transporter 4 (Glut4) storage vesicles (GSVs) from their intracellular storage sites to the plasma membrane (PM) where they dock with the PM. Then, Glut4 is inserted into the PM and initiates glucose uptake into these cells. Previous studies using chemical inhibitors demonstrated that myosin II participates in fusion of GSVs and the PM and increase in the intrinsic activity of Glut4. In this study, the effect of myosin IIA on GSV trafficking was examined by knocking down myosin IIA expression. Myosin IIA knockdown decreased both glucose uptake and exposures of myc-tagged Glut4 to the cell surface in insulin-stimulated cells, but did not affect insulin signal transduction. Interestingly, myosin IIA knockdown failed to decrease insulin-dependent trafficking of Glut4 to the PM. Moreover, in myosin IIA knockdown cells, insulin-stimulated binding of GSV SNARE protein, vesicle-associated membrane protein 2 (VAMP2) to PM SNARE protein, syntaxin 4 was inhibited. These data suggest that myosin IIA plays a role in insulin-stimulated docking of GSVs to the PM in 3T3-L1 adipocytes through SNARE complex formation.

  8. Notch pathway is dispensable for adipocyte specification.

    PubMed

    Nichols, Amy M; Pan, Yonghua; Herreman, An; Hadland, Brandon K; De Strooper, Bart; Kopan, Raphael; Huppert, Stacey S

    2004-09-01

    In the past decade we have witnessed an epidemic of obesity in developed countries. Therefore, understanding the mechanisms involved in regulation of body weight is becoming an increasingly important goal shared by the public and the scientific community. The key to fat deposition is the adipocyte, a specialized cell that plays a critical role in energy balance and appetite regulation. Much of our knowledge of adipogenesis comes from studies using preadipocytic cell lines that have provided important information regarding molecular control of adipocyte differentiation. However, they fall short of revealing how naive cells acquire competence for adipogenesis. Studies in preadipocytes indicate that the Notch pathway plays a role in regulating adipogenesis (Garces et al.: J Biol Chem 272:29729-29734, 1997). Given the known biological functions of Notch in mediating cell fate decisions (Artavanis-Tsakonas et al.: Science 284:770-776, 1999), we wished to test the hypothesis that the Notch pathway is required for this cellular program by examining adipogenesis in several genetic loss-of-function models that encompass the entire pathway. We conclude that the "canonical" Notch signaling pathway is dispensable for adipocyte specification and differentiation from either mesenchymal or epithelial progenitors.

  9. Modulation of age-related insulin sensitivity by VEGF-dependent vascular plasticity in adipose tissues

    PubMed Central

    Honek, Jennifer; Seki, Takahiro; Iwamoto, Hideki; Fischer, Carina; Li, Jingrong; Lim, Sharon; Samani, Nilesh J.; Zang, Jingwu; Cao, Yihai

    2014-01-01

    Mechanisms underlying age-related obesity and insulin resistance are generally unknown. Here, we report age-related adipose vascular changes markedly modulated fat mass, adipocyte functions, blood lipid composition, and insulin sensitivity. Notably, VEGF expression levels in various white adipose tissues (WATs) underwent changes uninterruptedly in different age populations. Anti-VEGF and anti- VEGF receptor 2 treatment in different age populations showed marked variations of vascular regression, with midaged mice exhibiting modest sensitivity. Interestingly, anti-VEGF treatment produced opposing effects on WAT adipocyte sizes in different age populations and affected vascular density and adipocyte sizes in brown adipose tissue. Consistent with changes of vasculatures and adipocyte sizes, anti-VEGF treatment increased insulin sensitivity in young and old mice but had no effects in the midaged group. Surprisingly, anti-VEGF treatment significantly improved insulin sensitivity in midaged obese mice fed a high-fat diet. Our findings demonstrate that adipose vasculatures show differential responses to anti-VEGF treatment in various age populations and have therapeutic implications for treatment of obesity and diabetes with anti-VEGF-based antiangiogenic drugs. PMID:25271320

  10. Insulin receptors in normal and disease states.

    PubMed

    Grunberger, G; Taylor, S I; Dons, R F; Gorden, P

    1983-03-01

    The binding of insulin to its receptor has been studied under various physiological and pathological conditions. Quantitative studies have involved human circulating cells such as monocytes and erythrocytes, adipocytes, placental cells, and cultured cells such as fibroblasts and transformed lymphocytes. In animals, other target tissues such as liver and muscle have been studied and correlated with the human studies. Various physiological conditions such as diurnal rhythm, diet, age, exercise and the menstrual cycle affect insulin binding; in addition, many drugs perturb the receptor interaction. Disease affecting the insulin receptor can be divided into five general categories: (1) Receptor regulation--this involves diseases characterized by hyper- or hypoinsulinaemia. Hyperinsulinaemia in the basal state usually leads to receptor 'down' regulation as seen in obesity, type II diabetes, acromegaly and islet cell tumours. Hypoinsulinaemia such as seen in anorexia nervosa or type I diabetes may lead to elevated binding. (2) Antireceptor antibodies--these immunoglobulins bind to the receptor and competitively inhibit insulin binding. They may act as agonists, antagonists or partial agonists. (3) Genetic diseases which produce fixed alterations in both freshly isolated and cultured cells. (4) Diseases of receptor specificity where insulin may bind with different affinity to its own receptor or related receptors such as receptors for insulin-like growth factors. (5) Disease of affinity modulation where physical factors such as pH, temperature, ions, etc. may modify binding. In this review, we have considered primarily abnormality in insulin receptor binding. There are numerous other functions of the receptor such as coupling and transmission of the biological signal. These mechanisms are frequently referred to as postreceptor events, but more properly should be referred to as postbinding events since the receptor subserves other functions in addition to recognition and