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Jiao J, Bae EJ, Bandyopadhyay G, Oliver J, Marathe C, Chen M, Hsu JY, Chen Y, Tian H, Olefsky JM, Saberi M. Restoration of euglycemia after duodenal bypass surgery is reliant on central and peripheral inputs in Zucker fa/fa rats. Diabetes 2013; 62:1074-83. [PMID: 23248171 PMCID: PMC3609588 DOI: 10.2337/db12-0681] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Gastrointestinal bypass surgeries that result in rerouting and subsequent exclusion of nutrients from the duodenum appear to rapidly alleviate hyperglycemia and hyperinsulinemia independent of weight loss. While the mechanism(s) responsible for normalization of glucose homeostasis remains to be fully elucidated, this rapid normalization coupled with the well-known effects of vagal inputs into glucose homeostasis suggests a neurohormonally mediated mechanism. Our results show that duodenal bypass surgery on obese, insulin-resistant Zucker fa/fa rats restored insulin sensitivity in both liver and peripheral tissues independent of body weight. Restoration of normoglycemia was attributable to an enhancement in key insulin-signaling molecules, including insulin receptor substrate-2, and substrate metabolism through a multifaceted mechanism involving activation of AMP-activated protein kinase and downregulation of key regulatory genes involved in both lipid and glucose metabolism. Importantly, while central nervous system-derived vagal nerves were not essential for restoration of insulin sensitivity, rapid normalization in hepatic gluconeogenic capacity and basal hepatic glucose production required intact vagal innervation. Lastly, duodenal bypass surgery selectively altered the tissue concentration of intestinally derived glucoregulatory hormone peptides in a segment-specific manner. The present data highlight and support the significance of vagal inputs and intestinal hormone peptides toward normalization of glucose and lipid homeostasis after duodenal bypass surgery.
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Affiliation(s)
- Jian Jiao
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Eun Ju Bae
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Gautam Bandyopadhyay
- Department of Medicine, University of California, San Diego, La Jolla, California
| | - Jason Oliver
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Chaitra Marathe
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Michael Chen
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Jer-Yuan Hsu
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Yu Chen
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Hui Tian
- NGM Biopharmaceuticals, Inc., South San Francisco, California
| | - Jerrold M. Olefsky
- Department of Medicine, University of California, San Diego, La Jolla, California
- Corresponding authors: Jerrold M. Olefsky, , and Maziyar Saberi,
| | - Maziyar Saberi
- NGM Biopharmaceuticals, Inc., South San Francisco, California
- Corresponding authors: Jerrold M. Olefsky, , and Maziyar Saberi,
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52
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Lu M, Sarruf DA, Li P, Osborn O, Sanchez-Alavez M, Talukdar S, Chen A, Bandyopadhyay G, Xu J, Morinaga H, Dines K, Watkins S, Kaiyala K, Schwartz MW, Olefsky JM. Neuronal Sirt1 deficiency increases insulin sensitivity in both brain and peripheral tissues. J Biol Chem 2013; 288:10722-35. [PMID: 23457303 DOI: 10.1074/jbc.m112.443606] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Sirt1 is a NAD(+)-dependent class III deacetylase that functions as a cellular energy sensor. In addition to its well-characterized effects in peripheral tissues, emerging evidence suggests that neuronal Sirt1 activity plays a role in the central regulation of energy balance and glucose metabolism. To assess this idea, we generated Sirt1 neuron-specific knockout (SINKO) mice. On both standard chow and HFD, SINKO mice were more insulin sensitive than Sirt1(f/f) mice. Thus, SINKO mice had lower fasting insulin levels, improved glucose tolerance and insulin tolerance, and enhanced systemic insulin sensitivity during hyperinsulinemic euglycemic clamp studies. Hypothalamic insulin sensitivity of SINKO mice was also increased over controls, as assessed by hypothalamic activation of PI3K, phosphorylation of Akt and FoxO1 following systemic insulin injection. Intracerebroventricular injection of insulin led to a greater systemic effect to improve glucose tolerance and insulin sensitivity in SINKO mice compared with controls. In line with the in vivo results, insulin-induced AKT and FoxO1 phosphorylation were potentiated by inhibition of Sirt1 in a cultured hypothalamic cell line. Mechanistically, this effect was traced to a reduced effect of Sirt1 to directly deacetylate and repress IRS-1 function. The enhanced central insulin signaling in SINKO mice was accompanied by increased insulin receptor signal transduction in liver, muscle, and adipose tissue. In summary, we conclude that neuronal Sirt1 negatively regulates hypothalamic insulin signaling, leading to systemic insulin resistance. Interventions that reduce neuronal Sirt1 activity have the potential to improve systemic insulin action and limit weight gain on an obesigenic diet.
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Affiliation(s)
- Min Lu
- Department of Medicine, University of California, San Diego, California 92093, USA
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53
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Qatanani M, Tan Y, Dobrin R, Greenawalt DM, Hu G, Zhao W, Olefsky JM, Sears DD, Kaplan LM, Kemp DM. Inverse regulation of inflammation and mitochondrial function in adipose tissue defines extreme insulin sensitivity in morbidly obese patients. Diabetes 2013; 62:855-63. [PMID: 23223024 PMCID: PMC3581230 DOI: 10.2337/db12-0399] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Obesity is associated with insulin resistance, a major risk factor for type 2 diabetes and cardiovascular disease. However, not all obese individuals are insulin resistant, which confounds our understanding of the mechanistic link between these conditions. We conducted transcriptome analyses on 835 obese subjects with mean BMI of 48.8, on which we have previously reported genetic associations of gene expression. Here, we selected ~320 nondiabetic (HbA(1c) <7.0) subjects and further stratified the cohort into insulin-resistant versus insulin-sensitive subgroups based on homeostasis model assessment-insulin resistance. An unsupervised informatics analysis revealed that immune response and inflammation-related genes were significantly downregulated in the omental adipose tissue of obese individuals with extreme insulin sensitivity and, to a much lesser extent, in subcutaneous adipose tissue. In contrast, genes related to β-oxidation and the citric acid cycle were relatively overexpressed in adipose of insulin-sensitive patients. These observations were verified by querying an independent cohort of our published dataset of 37 subjects whose subcutaneous adipose tissue was sampled before and after treatment with thiazolidinediones. Whereas the immune response and inflammation pathway genes were downregulated by thiazolidinedione treatment, β-oxidation and citric acid cycle genes were upregulated. This work highlights the critical role that omental adipose inflammatory pathways might play in the pathophysiology of insulin resistance, independent of body weight.
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MESH Headings
- Adult
- Biopsy
- Body Mass Index
- Citric Acid Cycle/drug effects
- Cohort Studies
- Diabetes Mellitus, Type 2/complications
- Gene Expression Profiling
- Gene Expression Regulation, Enzymologic/drug effects
- Humans
- Hypoglycemic Agents/therapeutic use
- Insulin Resistance
- Intra-Abdominal Fat/drug effects
- Intra-Abdominal Fat/immunology
- Intra-Abdominal Fat/metabolism
- Intra-Abdominal Fat/pathology
- Mitochondria/drug effects
- Mitochondria/metabolism
- Mitochondria/pathology
- Mitochondrial Proteins/genetics
- Mitochondrial Proteins/metabolism
- Obesity, Morbid/complications
- Obesity, Morbid/immunology
- Obesity, Morbid/metabolism
- Obesity, Morbid/pathology
- Oligonucleotide Array Sequence Analysis
- Oxidative Phosphorylation/drug effects
- RNA, Messenger/metabolism
- Subcutaneous Fat, Abdominal/drug effects
- Subcutaneous Fat, Abdominal/immunology
- Subcutaneous Fat, Abdominal/metabolism
- Subcutaneous Fat, Abdominal/pathology
- Thiazolidinediones/therapeutic use
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Affiliation(s)
- Mohammed Qatanani
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Diabetes and Endocrinology, Merck Research Laboratories, Rahway, New Jersey
| | - Yejun Tan
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Informatics and Analysis, Merck Research Laboratories, Rahway, New Jersey
| | - Radu Dobrin
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Informatics and Analysis, Merck Research Laboratories, Rahway, New Jersey
| | - Danielle M. Greenawalt
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Informatics and Analysis, Merck Research Laboratories, Rahway, New Jersey
| | - Guanghui Hu
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Informatics and Analysis, Merck Research Laboratories, Rahway, New Jersey
| | - Wenqing Zhao
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Informatics and Analysis, Merck Research Laboratories, Rahway, New Jersey
| | - Jerrold M. Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Dorothy D. Sears
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Lee M. Kaplan
- Gastrointestinal Metabolism Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Daniel M. Kemp
- Discovery and Preclinical Sciences, Merck Research Laboratories, Rahway, New Jersey
- Diabetes and Endocrinology, Merck Research Laboratories, Rahway, New Jersey
- Corresponding author: Daniel M. Kemp,
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54
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55
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Xu J, Morinaga H, Oh D, Li P, Chen A, Talukdar S, Mamane Y, Mancini JA, Nawrocki AR, Lazarowski E, Olefsky JM, Kim JJ. GPR105 ablation prevents inflammation and improves insulin sensitivity in mice with diet-induced obesity. J Immunol 2012; 189:1992-9. [PMID: 22778393 DOI: 10.4049/jimmunol.1103207] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
GPR105, a G protein-coupled receptor for UDP-glucose, is highly expressed in several human tissues and participates in the innate immune response. Because inflammation has been implicated as a key initial trigger for type 2 diabetes, we hypothesized that GPR105 (official gene name: P2RY14) might play a role in the initiation of inflammation and insulin resistance in obesity. To this end, we investigated glucose metabolism in GPR105 knockout (KO) and wild-type (WT) mice fed a high-fat diet (HFD). We also examined whether GPR105 regulates macrophage recruitment to liver or adipose tissues by in vivo monocyte tracking and in vitro chemotaxis experiments, followed by transplantation of bone marrow from either KO or WT donors to WT recipients. Our data show that genetic deletion of GPR105 confers protection against HFD-induced insulin resistance, with reduced macrophage infiltration and inflammation in liver, and increased insulin-stimulated Akt phosphorylation in liver, muscle, and adipose tissue. By tracking monocytes from either KO or WT donors, we found that fewer KO monocytes were recruited to the liver of WT recipients. Furthermore, we observed that uridine 5-diphosphoglucose enhanced the in vitro migration of bone marrow-derived macrophages from WT but not KO mice, and that plasma uridine 5-diphosphoglucose levels were significantly higher in obese versus lean mice. Finally, we confirmed that insulin sensitivity improved in HFD mice with a myeloid cell-specific deletion of GPR105. These studies indicate that GPR105 ablation mitigates HFD-induced insulin resistance by inhibiting macrophage recruitment and tissue inflammation. Hence GPR105 provides a novel link between innate immunity and metabolism.
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Affiliation(s)
- Jianfeng Xu
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
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56
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Osborn O, Oh DY, McNelis J, Sanchez-Alavez M, Talukdar S, Lu M, Li P, Thiede L, Morinaga H, Kim JJ, Heinrichsdorff J, Nalbandian S, Ofrecio JM, Scadeng M, Schenk S, Hadcock J, Bartfai T, Olefsky JM. G protein-coupled receptor 21 deletion improves insulin sensitivity in diet-induced obese mice. J Clin Invest 2012; 122:2444-53. [PMID: 22653059 DOI: 10.1172/jci61953] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 04/24/2012] [Indexed: 02/06/2023] Open
Abstract
Obesity-induced inflammation is a key component of systemic insulin resistance, which is a hallmark of type 2 diabetes. A major driver of this inflammation/insulin resistance syndrome is the accumulation of proinflammatory macrophages in adipose tissue and liver. We found that the orphan GPCR Gpr21 was highly expressed in the hypothalamus and macrophages of mice and that whole-body KO of this receptor led to a robust improvement in glucose tolerance and systemic insulin sensitivity and a modest lean phenotype. The improvement in insulin sensitivity in the high-fat diet-fed (HFD-fed) Gpr21 KO mouse was traced to a marked reduction in tissue inflammation caused by decreased chemotaxis of Gpr21 KO macrophages into adipose tissue and liver. Furthermore, mice lacking macrophage expression of Gpr21 were protected from HFD-induced inflammation and displayed improved insulin sensitivity. Results of in vitro chemotaxis studies in human monocytes suggested that the defect in chemotaxis observed ex vivo and in vivo in mice is also translatable to humans. Cumulatively, our data indicate that GPR21 has a critical function in coordinating macrophage proinflammatory activity in the context of obesity-induced insulin resistance.
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Affiliation(s)
- Olivia Osborn
- Division of Endocrinology and Metabolism, Department of Medicine, UCSD, La Jolla, CA, USA
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57
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Abstract
Human loss-of-function gene variants in GPR120 have recently been identified that confer increased risk for obesity and metabolic syndrome. In addition, GPR120 KO mice develop obesity, increased inflammation, and insulin resistance, consistent with a role for GPR120 signaling in the metabolic syndrome and diabetes mellitus.
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Affiliation(s)
- Da Young Oh
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
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58
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Abstract
Inflammation and lipid signaling are intertwined modulators of homeostasis and immunity. In addition to the extensively studied eicosanoids and inositol phospholipids, emerging studies indicate that many other lipid species act to positively and negatively regulate inflammatory responses. Conversely, inflammatory signaling can significantly alter lipid metabolism in the liver, adipose tissue, skeletal muscle, and macrophage in the context of infection, diabetes, and atherosclerosis. Here, we review recent findings related to this interconnected network from the perspective of immunity and metabolic disease.
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Affiliation(s)
- Christopher K Glass
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0673, USA.
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59
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Bae EJ, Xu J, Oh DY, Bandyopadhyay G, Lagakos WS, Keshwani M, Olefsky JM. Liver-specific p70 S6 kinase depletion protects against hepatic steatosis and systemic insulin resistance. J Biol Chem 2012; 287:18769-80. [PMID: 22493495 DOI: 10.1074/jbc.m112.365544] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Obesity-associated hepatic steatosis is a manifestation of selective insulin resistance whereby lipogenesis remains sensitive to insulin but the ability of insulin to suppress glucose production is impaired. We created a mouse model of liver-specific knockdown of p70 S6 kinase (S6K) (L-S6K-KD) by systemic delivery of an adeno-associated virus carrying a shRNA for S6K and examined the effects on steatosis and insulin resistance. High fat diet (HFD) fed L-S6K-KD mice showed improved glucose tolerance and systemic insulin sensitivity compared with controls, with no changes in food intake or body weight. The induction of lipogenic gene expression was attenuated in the L-S6K-KD mice with decreased sterol regulatory element-binding protein (SREBP)-1c expression and mature SREBP-1c protein, as well as decreased steatosis on HFD. Our results demonstrate the importance of S6K: 1) as a modulator of the hepatic response to fasting/refeeding, 2) in the development of steatosis, and 3) as a key node in selective hepatic insulin resistance in obese mice.
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Affiliation(s)
- Eun Ju Bae
- Department of Medicine, University of California, San Diego, California 92093, USA
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60
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Fernandez MO, Sharma S, Hwang V, Olefsky JM, Webster NJ. Effect of brain specific deletion of PPARγ on puberty onset, hypothalamic gene expression and diet induced obesity (DIO) in C57BL/6 mice. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1094.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Shweta Sharma
- MedicineUniversity of California San DiegoLa JollaCA
| | - Vicky Hwang
- MedicineUniversity of California San DiegoLa JollaCA
| | | | - Nicholas J. Webster
- MedicineUniversity of California San DiegoLa JollaCA
- VA San Diego Healthcare SystemSan DiegoCA
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61
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Affiliation(s)
- Jerrold M Olefsky
- Medicine/Endocrinology & MetabolismUniversity of CaliforniaSan Diego, La JollaCA
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62
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Nguyen KV, Rickert EL, Olefsky JM, Webster NJ. Effect of caloric restriction on the expression of the Sirtuin Proteins. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.649.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Nicholas J Webster
- MedicineUniversity of CaliforniaSan Diego, La JollaCA
- MedicineVA San Diego Healthcare SystemLa JollaCA
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63
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Rickert EL, Olefsky JM, Webster NJ. Examination of the reproductive effects of SirT1 expression in neurons. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.762.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Nicholas J. Webster
- MedicineUniversity of CaliforniaSan Diego, La JollaCA
- VA San Diego Healthcare SystemSan DiegoCA
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64
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Abstract
It is now recognized that obesity is driving the type 2 diabetes epidemic in Western countries. Obesity-associated chronic tissue inflammation is a key contributing factor to type 2 diabetes and cardiovascular disease, and a number of studies have clearly demonstrated that the immune system and metabolism are highly integrated. Recent advances in deciphering the various cellular and signaling networks that participate in linking the immune and metabolic systems together have contributed to understanding of the pathogenesis of metabolic diseases and may also inform new therapeutic strategies based on immunomodulation. Here we discuss how these various networks underlie the etiology of the inflammatory component of insulin resistance, with a particular focus on the central roles of macrophages in adipose tissue and liver.
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Affiliation(s)
- Olivia Osborn
- Department of Medicine, Division of Endocrinology and Metabolism, University of California-San Diego, La Jolla, California, USA
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65
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Abstract
Macrophage-mediated inflammation is a key component of insulin resistance; however, the initial events of monocyte migration to become tissue macrophages remain poorly understood. We report a new method to quantitate in vivo macrophage tracking (i.e., blood monocytes from donor mice) labeled ex vivo with fluorescent PKH26 dye and injected into recipient mice. Labeled monocytes appear as adipose, liver, and splenic macrophages, peaking in 1-2 days. When CCR2 KO monocytes are injected into wild-type (WT) recipients, or WT monocytes given to MCP-1 KO recipients, adipose tissue macrophage (ATM) accumulation is reduced by ~40%, whereas hepatic macrophage content is decreased by ~80%. Using WT donor cells, ATM accumulation is several-fold greater in obese recipient mice compared with lean mice, regardless of the source of donor monocytes. After their appearance in adipose tissue, ATMs progressively polarize from the M2- to the M1-like state in obesity. In summary, the CCR2/MCP-1 system is a contributory factor to monocyte migration into adipose tissue and is the dominant signal controlling the appearance of recruited macrophages in the liver. Monocytes from obese mice are not programmed to become inflammatory ATMs but rather the increased proinflammatory ATM accumulation in obesity is in response to tissue signals.
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Affiliation(s)
- Da Young Oh
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Hidetaka Morinaga
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Saswata Talukdar
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
| | - Eun Ju Bae
- College of Pharmacy, Woosuk University, Wanju-gun, Jeollabuk-do, Korea
| | - Jerrold M. Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California
- Corresponding author: Jerrold M. Olefsky,
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66
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Li P, Fan W, Xu J, Lu M, Yamamoto H, Auwerx J, Sears DD, Talukdar S, Oh D, Chen A, Bandyopadhyay G, Scadeng M, Ofrecio JM, Nalbandian S, Olefsky JM. Adipocyte NCoR knockout decreases PPARγ phosphorylation and enhances PPARγ activity and insulin sensitivity. Cell 2012; 147:815-26. [PMID: 22078880 DOI: 10.1016/j.cell.2011.09.050] [Citation(s) in RCA: 228] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/22/2011] [Accepted: 09/23/2011] [Indexed: 01/06/2023]
Abstract
Insulin resistance, tissue inflammation, and adipose tissue dysfunction are features of obesity and Type 2 diabetes. We generated adipocyte-specific Nuclear Receptor Corepressor (NCoR) knockout (AKO) mice to investigate the function of NCoR in adipocyte biology, glucose and insulin homeostasis. Despite increased obesity, glucose tolerance was improved in AKO mice, and clamp studies demonstrated enhanced insulin sensitivity in liver, muscle, and fat. Adipose tissue macrophage infiltration and inflammation were also decreased. PPARγ response genes were upregulated in adipose tissue from AKO mice and CDK5-mediated PPARγ ser-273 phosphorylation was reduced, creating a constitutively active PPARγ state. This identifies NCoR as an adaptor protein that enhances the ability of CDK5 to associate with and phosphorylate PPARγ. The dominant function of adipocyte NCoR is to transrepress PPARγ and promote PPARγ ser-273 phosphorylation, such that NCoR deletion leads to adipogenesis, reduced inflammation, and enhanced systemic insulin sensitivity, phenocopying the TZD-treated state.
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Affiliation(s)
- Pingping Li
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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67
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Gillum MP, Kotas ME, Erion DM, Kursawe R, Chatterjee P, Nead KT, Muise ES, Hsiao JJ, Frederick DW, Yonemitsu S, Banks AS, Qiang L, Bhanot S, Olefsky JM, Sears DD, Caprio S, Shulman GI. SirT1 regulates adipose tissue inflammation. Diabetes 2011; 60:3235-45. [PMID: 22110092 PMCID: PMC3219953 DOI: 10.2337/db11-0616] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Macrophage recruitment to adipose tissue is a reproducible feature of obesity. However, the events that result in chemokine production and macrophage recruitment to adipose tissue during states of energetic excess are not clear. Sirtuin 1 (SirT1) is an essential nutrient-sensing histone deacetylase, which is increased by caloric restriction and reduced by overfeeding. We discovered that SirT1 depletion causes anorexia by stimulating production of inflammatory factors in white adipose tissue and thus posit that decreases in SirT1 link overnutrition and adipose tissue inflammation. RESEARCH DESIGN AND METHODS We used antisense oligonucleotides to reduce SirT1 to levels similar to those seen during overnutrition and studied SirT1-overexpressing transgenic mice and fat-specific SirT1 knockout animals. Finally, we analyzed subcutaneous adipose tissue biopsies from two independent cohorts of human subjects. RESULTS We found that inducible or genetic reduction of SirT1 in vivo causes macrophage recruitment to adipose tissue, whereas overexpression of SirT1 prevents adipose tissue macrophage accumulation caused by chronic high-fat feeding. We also found that SirT1 expression in human subcutaneous fat is inversely related to adipose tissue macrophage infiltration. CONCLUSIONS Reduction of adipose tissue SirT1 expression, which leads to histone hyperacetylation and ectopic inflammatory gene expression, is identified as a key regulatory component of macrophage influx into adipose tissue during overnutrition in rodents and humans. Our results suggest that SirT1 regulates adipose tissue inflammation by controlling the gain of proinflammatory transcription in response to inducers such as fatty acids, hypoxia, and endoplasmic reticulum stress.
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Affiliation(s)
- Matthew P. Gillum
- Howard Hughes Medical Institute, Chevy Chase, Maryland
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Maya E. Kotas
- Howard Hughes Medical Institute, Chevy Chase, Maryland
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut
| | - Derek M. Erion
- Howard Hughes Medical Institute, Chevy Chase, Maryland
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | - Romy Kursawe
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
| | - Paula Chatterjee
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Kevin T. Nead
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
| | | | - Jennifer J. Hsiao
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - David W. Frederick
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Shin Yonemitsu
- Howard Hughes Medical Institute, Chevy Chase, Maryland
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Alexander S. Banks
- Department of Cell Biology, Harvard School of Medicine, Boston, Massachusetts
| | - Li Qiang
- Columbia University, New York, New York
| | | | | | | | - Sonia Caprio
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
| | - Gerald I. Shulman
- Howard Hughes Medical Institute, Chevy Chase, Maryland
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut
- Corresponding author: Gerald I. Shulman,
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68
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Schenk S, McCurdy CE, Philp A, Chen MZ, Holliday MJ, Bandyopadhyay GK, Osborn O, Baar K, Olefsky JM. Sirt1 enhances skeletal muscle insulin sensitivity in mice during caloric restriction. J Clin Invest 2011; 121:4281-8. [PMID: 21985785 DOI: 10.1172/jci58554] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 09/07/2011] [Indexed: 01/08/2023] Open
Abstract
Skeletal muscle insulin resistance is a key component of the etiology of type 2 diabetes. Caloric restriction (CR) enhances the sensitivity of skeletal muscle to insulin. However, the molecular signals within skeletal muscle linking CR to improved insulin action remain largely unknown. Recently, the mammalian ortholog of Sir2, sirtuin 1 (Sirt1), has been identified as a potential transducer of perturbations in cellular energy flux into subsequent metabolic adaptations, including modulation of skeletal muscle insulin action. Here, we have demonstrated that CR increases Sirt1 deacetylase activity in skeletal muscle in mice, in parallel with enhanced insulin-stimulated phosphoinositide 3-kinase (PI3K) signaling and glucose uptake. These adaptations in skeletal muscle insulin action were completely abrogated in mice lacking Sirt1 deacetylase activity. Mechanistically, Sirt1 was found to be required for the deacetylation and inactivation of the transcription factor Stat3 during CR, which resulted in decreased gene and protein expression of the p55α/p50α subunits of PI3K, thereby promoting more efficient PI3K signaling during insulin stimulation. Thus, these data demonstrate that Sirt1 is an integral signaling node in skeletal muscle linking CR to improved insulin action, primarily via modulation of PI3K signaling.
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Affiliation(s)
- Simon Schenk
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0673, USA
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69
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Ohtsubo K, Chen MZ, Olefsky JM, Marth JD. Pathway to diabetes through attenuation of pancreatic beta cell glycosylation and glucose transport. Nat Med 2011; 17:1067-75. [PMID: 21841783 DOI: 10.1038/nm.2414] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 06/07/2011] [Indexed: 12/24/2022]
Abstract
A connection between diet, obesity and diabetes exists in multiple species and is the basis of an escalating human health problem. The factors responsible provoke both insulin resistance and pancreatic beta cell dysfunction but remain to be fully identified. We report a combination of molecular events in human and mouse pancreatic beta cells, induced by elevated levels of free fatty acids or by administration of a high-fat diet with associated obesity, that comprise a pathogenic pathway to diabetes. Elevated concentrations of free fatty acids caused nuclear exclusion and reduced expression of the transcription factors FOXA2 and HNF1A in beta cells. This resulted in a deficit of GnT-4a glycosyltransferase expression in beta cells that produced signs of metabolic disease, including hyperglycemia, impaired glucose tolerance, hyperinsulinemia, hepatic steatosis and diminished insulin action in muscle and adipose tissues. Protection from disease was conferred by enforced beta cell-specific GnT-4a protein glycosylation and involved the maintenance of glucose transporter expression and the preservation of glucose transport. We observed that this pathogenic process was active in human islet cells obtained from donors with type 2 diabetes; thus, illuminating a pathway to disease implicated in the diet- and obesity-associated component of type 2 diabetes mellitus.
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Affiliation(s)
- Kazuaki Ohtsubo
- Center for Nanomedicine, Sanford-Burnham Medical Research Institute, University of California-Santa Barbara, Santa Barbara, California, USA
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70
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Talukdar S, Olefsky JM, Osborn O. Targeting GPR120 and other fatty acid-sensing GPCRs ameliorates insulin resistance and inflammatory diseases. Trends Pharmacol Sci 2011; 32:543-50. [PMID: 21663979 DOI: 10.1016/j.tips.2011.04.004] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Revised: 04/25/2011] [Accepted: 04/29/2011] [Indexed: 01/08/2023]
Abstract
The past decade has seen great progress in the understanding of the molecular pharmacology, physiological function and therapeutic potential of G-protein-coupled receptors (GPCRs). Free fatty acids (FFAs) have been demonstrated to act as ligands of several GPCRs including GPR40, GPR43, GPR84, GPR119 and GPR120. We have recently shown that GPR120 acts as a physiological receptor of ω3 fatty acids in macrophages and adipocytes, which mediate potent anti-inflammatory and insulin sensitizing effects. The important role GPR120 plays in the control of inflammation raises the possibility that targeting this receptor could have therapeutic potential in many inflammatory diseases including obesity and type 2 diabetes. In this review paper, we discuss lipid-sensing GPCRs and highlight potential outcomes of targeting such receptors in ameliorating disease.
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Affiliation(s)
- Saswata Talukdar
- Department of Medicine, Division of Endocrinology and Metabolism, University of California San Diego, La Jolla, CA 92093, USA.
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71
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Lan D, Lu M, Sharma S, Mellon PL, Olefsky JM, Webster NJG. Trans-resveratrol inhibits phosphorylation of Smad2/3 and represses FSHβ gene expression by a SirT1-independent pathway in LβT2 gonadotrope cells. Reprod Toxicol 2011; 32:85-92. [PMID: 21679764 DOI: 10.1016/j.reprotox.2011.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 04/22/2011] [Accepted: 05/12/2011] [Indexed: 12/20/2022]
Abstract
Resveratrol (trans-3,5,4'-trihydroxystilbene), a polyphenol found in red wine, has multiple beneficial activities that are similar to caloric restriction. In this study, we analyzed the effect of resveratrol on the gonadotropin genes, follicle-stimulating hormone (FSHβ) and luteinizing hormone (LHβ) in LβT2 immortalized mouse gonadotrope cells. Resveratrol specifically inhibited activin-induced FSHβ mRNA and protein expression, and reduced activin-stimulated Smad2/3 phosphorylation. Knockdown of SirT1 gene expression or SirT1 inhibition did not block repression of FSHβ expression or suppression of Smad2/3 phosphorylation, but did increase p53 acetylation. Taken together, our results suggest that resveratrol down-regulates Smad2/3 phosphorylation and suppresses FSHβ expression via a SirT1-independent pathway.
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Affiliation(s)
- Debin Lan
- Department of Medicine, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA
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72
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Lu M, Sarruf DA, Talukdar S, Sharma S, Li P, Bandyopadhyay G, Nalbandian S, Fan W, Gayen JR, Mahata SK, Webster NJ, Schwartz MW, Olefsky JM. Brain PPAR-γ promotes obesity and is required for the insulin-sensitizing effect of thiazolidinediones. Nat Med 2011; 17:618-22. [PMID: 21532596 PMCID: PMC3380629 DOI: 10.1038/nm.2332] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 02/15/2011] [Indexed: 01/28/2023]
Abstract
In adipose tissue, muscle, liver and macrophages, signaling by the nuclear receptor peroxisome proliferator-activated receptor-γ (PPAR-γ) is a determinant of insulin sensitivity and this receptor mediates the insulin-sensitizing effects of thiazolidinediones (TZDs). As PPAR-γ is also expressed in neurons, we generated mice with neuron-specific Pparg knockout (Pparg brain knockout (BKO)) to determine whether neuronal PPAR-γ signaling contributes to either weight gain or insulin sensitivity. During high-fat diet (HFD) feeding, food intake was reduced and energy expenditure increased in Pparg-BKO mice compared to Pparg(f/f) mice, resulting in reduced weight gain. Pparg-BKO mice also responded better to leptin administration than Pparg(f/f) mice. When treated with the TZD rosiglitazone, Pparg-BKO mice were resistant to rosiglitazone-induced hyperphagia and weight gain and, relative to rosiglitazone-treated Pparg(f/f) mice, experienced only a marginal improvement in glucose metabolism. Hyperinsulinemic euglycemic clamp studies showed that the increase in hepatic insulin sensitivity induced by rosiglitazone treatment during HFD feeding was completely abolished in Pparg-BKO mice, an effect associated with the failure of rosiglitazone to improve liver insulin receptor signal transduction. We conclude that excess weight gain induced by HFD feeding depends in part on the effect of neuronal PPAR-γ signaling to limit thermogenesis and increase food intake. Neuronal PPAR-γ signaling is also required for the hepatic insulin sensitizing effects of TZDs.
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Affiliation(s)
- Min Lu
- Department of Medicine, University of California-San Diego (UCSD), San Diego, California, USA
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73
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Osawa Y, Seki E, Kodama Y, Suetsugu A, Miura K, Adachi M, Ito H, Shiratori Y, Banno Y, Olefsky JM, Nagaki M, Moriwaki H, Brenner DA, Seishima M. Acid sphingomyelinase regulates glucose and lipid metabolism in hepatocytes through AKT activation and AMP-activated protein kinase suppression. FASEB J 2010; 25:1133-44. [PMID: 21163859 PMCID: PMC3058702 DOI: 10.1096/fj.10-168351] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Acid sphingomyelinase (ASM) regulates the homeostasis of sphingolipids, including ceramides and sphingosine-1-phosphate (S1P). Because sphingolipids regulate AKT activation, we investigated the role of ASM in hepatic glucose and lipid metabolism. Initially, we overexpressed ASM in the livers of wild-type and diabetic db/db mice by adenovirus vector (Ad5ASM). In these mice, glucose tolerance was improved, and glycogen and lipid accumulation in the liver were increased. Using primary cultured hepatocytes, we confirmed that ASM increased glucose uptake, glycogen deposition, and lipid accumulation through activation of AKT and glycogen synthase kinase-3β. In addition, ASM induced up-regulation of glucose transporter 2 accompanied by suppression of AMP-activated protein kinase (AMPK) phosphorylation. Loss of sphingosine kinase-1 (SphK1) diminished ASM-mediated AKT phosphorylation, but exogenous S1P induced AKT activation in hepatocytes. In contrast, SphK1 deficiency did not affect AMPK activation. These results suggest that the SphK/S1P pathway is required for ASM-mediated AKT activation but not for AMPK inactivation. Finally, we found that treatment with high-dose glucose increased glycogen deposition and lipid accumulation in wild-type hepatocytes but not in ASM(-/-) cells. This result is consistent with glucose intolerance in ASM(-/-) mice. In conclusion, ASM modulates AKT activation and AMPK inactivation, thus regulating glucose and lipid metabolism in the liver.
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Affiliation(s)
- Yosuke Osawa
- Department of Informative Clinical Medicine, Gifu University Graduate School of Medicine, Gifu, Japan.
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74
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Abstract
Increased dietary saturated fat intake can lead to detrimental effects on human health. In this issue of Cell Metabolism, Lichtenstein et al. (2010) show that by inhibiting lipoprotein lipase (LPL) activity in mesenteric lymph nodes, Angiopoietin-like protein 4 (Angptl4) protects resident macrophages from dietary saturated fatty acid (SFA)-induced inflammation.
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Affiliation(s)
- Olivia Osborn
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
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75
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Sharma S, Sharma PM, Mistry DS, Chang RJ, Olefsky JM, Mellon PL, Webster NJG. PPARG regulates gonadotropin-releasing hormone signaling in LbetaT2 cells in vitro and pituitary gonadotroph function in vivo in mice. Biol Reprod 2010; 84:466-75. [PMID: 21076077 DOI: 10.1095/biolreprod.110.088005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Peroxisome proliferators-activated receptor gamma (PPARG) ligands improve insulin sensitivity in type 2 diabetes and polycystic ovarian syndrome (PCOS). Despite clinical studies showing normalization of pituitary responsiveness to gonadotropin-releasing hormone (GnRH) in patients with PCOS, the precise role of PPARG in regulating the hypothalamic-pituitary-gonadal axis remains unclear. In the present study, we tested the hypothesis that the PPARG agonist rosiglitazone has a direct effect on the pituitary. In mouse LbetaT2 immortalized gonadotrophs, rosiglitazone treatment inhibited GnRH stimulation of the stress kinases p38MAPK and MAPKs/JNKs, but did not alter activation of ERKs, both in the presence and absence of activin. Furthermore, p38MAPK signaling was critical for both Lhb and Fshb promoter activity, and rosiglitazone suppressed the GnRH-mediated induction of Lhb and Fshb mRNA. Depletion of PPARG using a lentivirally encoded short hairpin RNA abolishes the effect of rosiglitazone to suppress activation of JNKs and induction of the transcription factors EGR1 and FOS as well as the gonadotropin genes Lhb and Fshb. Lastly, we show conditional knockout of Pparg in pituitary gonadotrophs caused an increase in luteinizing hormone levels in female mice, a decrease in follicle-stimulating hormone in male mice, and a fertility defect characterized by reduced litter size. Taken together, our data support a direct role for PPARG in modulating pituitary function in vitro and in vivo.
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Affiliation(s)
- Shweta Sharma
- Medical Research Service, VA San Diego Healthcare System, San Diego, California, USA
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76
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Fan W, Morinaga H, Kim JJ, Bae E, Spann NJ, Heinz S, Glass CK, Olefsky JM. FoxO1 regulates Tlr4 inflammatory pathway signalling in macrophages. EMBO J 2010; 29:4223-36. [PMID: 21045807 DOI: 10.1038/emboj.2010.268] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 10/04/2010] [Indexed: 12/18/2022] Open
Abstract
The macrophage-mediated inflammatory response is a key etiologic component of obesity-related tissue inflammation and insulin resistance. The transcriptional factor FoxO1 is a key regulator of cell metabolism, cell cycle and cell death. Its activity is tightly regulated by the phosphoinositide-3-kinase-AKT (PI3K-Akt) pathway, which leads to phosphorylation, cytoplasmic retention and inactivation of FoxO1. Here, we show that FoxO1 promotes inflammation by enhancing Tlr4-mediated signalling in mature macrophages. By means of chromatin immunoprecipitation (ChIP) combined with massively parallel sequencing (ChIP-Seq), we show that FoxO1 binds to multiple enhancer-like elements within the Tlr4 gene itself, as well as to sites in a number of Tlr4 signalling pathway genes. While FoxO1 potentiates Tlr4 signalling, activation of the latter induces AKT and subsequently inactivates FoxO1, establishing a self-limiting mechanism of inflammation. Given the central role of macrophage Tlr4 in transducing extrinsic proinflammatory signals, the novel functions for FoxO1 in macrophages as a transcriptional regulator of the Tlr4 gene and its inflammatory pathway, highlights FoxO1 as a key molecular adaptor integrating inflammatory responses in the context of obesity and insulin resistance.
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Affiliation(s)
- Wuqiang Fan
- Division of Endocrinology-Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0673, USA
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77
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Oh DY, Talukdar S, Bae EJ, Imamura T, Morinaga H, Fan W, Li P, Lu WJ, Watkins SM, Olefsky JM. GPR120 is an omega-3 fatty acid receptor mediating potent anti-inflammatory and insulin-sensitizing effects. Cell 2010; 142:687-98. [PMID: 20813258 DOI: 10.1016/j.cell.2010.07.041] [Citation(s) in RCA: 1746] [Impact Index Per Article: 124.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 05/24/2010] [Accepted: 07/19/2010] [Indexed: 12/18/2022]
Abstract
Omega-3 fatty acids (omega-3 FAs), DHA and EPA, exert anti-inflammatory effects, but the mechanisms are poorly understood. Here, we show that the G protein-coupled receptor 120 (GPR120) functions as an omega-3 FA receptor/sensor. Stimulation of GPR120 with omega-3 FAs or a chemical agonist causes broad anti-inflammatory effects in monocytic RAW 264.7 cells and in primary intraperitoneal macrophages. All of these effects are abrogated by GPR120 knockdown. Since chronic macrophage-mediated tissue inflammation is a key mechanism for insulin resistance in obesity, we fed obese WT and GPR120 knockout mice a high-fat diet with or without omega-3 FA supplementation. The omega-3 FA treatment inhibited inflammation and enhanced systemic insulin sensitivity in WT mice, but was without effect in GPR120 knockout mice. In conclusion, GPR120 is a functional omega-3 FA receptor/sensor and mediates potent insulin sensitizing and antidiabetic effects in vivo by repressing macrophage-induced tissue inflammation.
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Affiliation(s)
- Da Young Oh
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
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78
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Lu M, Li P, Pferdekamper J, Fan W, Saberi M, Schenk S, Olefsky JM. Inducible nitric oxide synthase deficiency in myeloid cells does not prevent diet-induced insulin resistance. Mol Endocrinol 2010; 24:1413-22. [PMID: 20444886 DOI: 10.1210/me.2009-0462] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Recent findings denote an important contribution of macrophage inflammatory pathways in causing obesity-related insulin resistance. Inducible nitric oxide synthase (iNOS) is activated in proinflammatory macrophages and modestly elevated in insulin-responsive tissues. Although the benefits of systemic iNOS inhibition in insulin-resistant models have been demonstrated, the role of macrophage iNOS in metabolic disorders is not clear. In the current work, we used bone marrow transplantation (BMT) to generate mice with myeloid iNOS deficiency [iNOS BMT knockout (KO)]. Interestingly, disruption of iNOS in myeloid cells did not protect mice from high-fat diet-induced obesity and insulin resistance. When mice were treated with the iNOS inhibitor, N6-(1-Iminoethyl)-L-lysine hydrochloride (L-NIL), we observed a significant and comparable improvement of glucose homeostasis and insulin sensitivity in both wild-type and iNOS BMT KO mice. We further demonstrated that absence of iNOS in primary macrophages did not affect acute TLR4 signaling pathways and had only a modest and mixed effect on inflammatory gene expression. With respect to TNFalpha treatment, iNOS KO macrophages showed, if anything, a greater inflammatory response. In summary, we conclude that iNOS inhibition in tissues other than myeloid cells is responsible for the beneficial effects in obesity/insulin resistance.
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Affiliation(s)
- Min Lu
- Department of Medicine, University of California, San Diego, California 92093, USA
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79
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Abstract
Obesity induces an insulin-resistant state in adipose tissue, liver, and muscle and is a strong risk factor for the development of type 2 diabetes mellitus. Insulin resistance in the setting of obesity results from a combination of altered functions of insulin target cells and the accumulation of macrophages that secrete proinflammatory mediators. At the molecular level, insulin resistance is promoted by a transition in macrophage polarization from an alternative M2 activation state maintained by STAT6 and PPARs to a classical M1 activation state driven by NF-kappaB, AP1, and other signal-dependent transcription factors that play crucial roles in innate immunity. Strategies focused on inhibiting the inflammation/insulin resistance axis that otherwise preserve essential innate immune functions may hold promise for therapeutic intervention.
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Affiliation(s)
- Jerrold M Olefsky
- Department of Medicine, University of California-San Diego, La Jolla, CA 92093-0651, USA.
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80
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Lu M, Patsouris D, Li P, Flores-Riveros J, Frincke JM, Watkins S, Schenk S, Olefsky JM. A new antidiabetic compound attenuates inflammation and insulin resistance in Zucker diabetic fatty rats. Am J Physiol Endocrinol Metab 2010; 298:E1036-48. [PMID: 20159859 PMCID: PMC2867370 DOI: 10.1152/ajpendo.00668.2009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Tissue macrophage inflammatory pathways contribute to obesity-associated insulin resistance. Here, we have examined the efficacy and mechanisms of action of a novel anti-inflammatory compound (HE3286) in vitro and in vivo. In primary murine macrophages, HE3286 attenuates LPS- and TNFalpha-stimulated inflammation. In Zucker diabetic fatty rats, inflammatory cytokine/chemokine expression was downregulated in liver and adipose tissue by HE3286 treatment, as was macrophage infiltration into adipose tissue. In line with reduced inflammation, HE3286 treatment normalized fasting and fed glucose levels, improved glucose tolerance, and enhanced skeletal muscle and liver insulin sensitivity, as assessed by hyperinsulinemic euglycemic clamp studies. In phase 2 clinical trials, HE3286 treatment led to an enhancement in insulin sensitivity in humans. Gluconeogenic capacity was also reduced by HE3286 treatment, as evidenced by a reduced glycemic response during pyruvate tolerance tests and decreased basal hepatic glucose production (HGP) rates. Since serum levels of gluconeogenic substrates were decreased by HE3286, it indicates that the reduction of both intrinsic gluconeogenic capacity and substrate availability contributes to the decrease in HGP. Lipidomic analysis revealed that HE3286 treatment reduced liver cholesterol and triglyceride content, leading to a feedback elevation of LDL receptor and HMG-CoA reductase expression. Accordingly, HE3286 treatment markedly decreased total serum cholesterol. In conclusion, HE3286 is a novel anti-inflammatory compound, which displays both glucose-lowering and cholesterol-lowering effects.
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Affiliation(s)
- Min Lu
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0673, USA
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81
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Li P, Lu M, Nguyen MTA, Bae EJ, Chapman J, Feng D, Hawkins M, Pessin JE, Sears DD, Nguyen AK, Amidi A, Watkins SM, Nguyen U, Olefsky JM. Functional heterogeneity of CD11c-positive adipose tissue macrophages in diet-induced obese mice. J Biol Chem 2010; 285:15333-15345. [PMID: 20308074 DOI: 10.1074/jbc.m110.100263] [Citation(s) in RCA: 186] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Obesity represents a state of chronic, low grade inflammation and is associated with infiltration of increased numbers of adipose tissue macrophages (ATMs). Diet-induced obesity leads to an increase in non-inflammatory M1-like ATMs displaying the CD11c surface marker. We assessed the function of CD11c-positive ATMs when insulin resistant high fat diet (HFD) mice become insulin-sensitive after switching from HFD to normal chow (NC). HFD mice rapidly become insulin-sensitive in all major insulin-target tissues, including muscle, liver, and adipose tissue, after the diet switch. In adipose tissue the CD11c-positive macrophages remain constant in number despite the presence of insulin sensitivity, but these macrophages now assume a new phenotype in which they no longer exhibit increased inflammatory pathway markers. Adipose tissue markers of apoptosis and necrosis were elevated on HFD and remain high after the HFD --> NC diet switch. Furthermore, ATM accumulation preceded detectable adipocyte necrosis at the early phase of HFD. Together, these results indicate that 1) CD11c-positive M1-like ATMs can exhibit phenotypic plasticity and that the polarization of these cells between inflammatory and non-inflammatory states is well correlated to the presence of absence of insulin resistance, and 2) adipocyte necrosis and apoptosis can be dissociated from ATM accumulation.
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Affiliation(s)
- Pingping Li
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | - Min Lu
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | - M T Audrey Nguyen
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | - Eun Ju Bae
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | | | - Daorong Feng
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Meredith Hawkins
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jeffrey E Pessin
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Dorothy D Sears
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | - Anh-Khoi Nguyen
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | - Arezou Amidi
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673
| | | | - UyenThao Nguyen
- Lipomics Technologies, Inc., West Sacramento, California 95691
| | - Jerrold M Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0673.
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82
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Yoshizaki T, Schenk S, Imamura T, Babendure JL, Sonoda N, Bae EJ, Oh DY, Lu M, Milne JC, Westphal C, Bandyopadhyay G, Olefsky JM. SIRT1 inhibits inflammatory pathways in macrophages and modulates insulin sensitivity. Am J Physiol Endocrinol Metab 2010; 298:E419-28. [PMID: 19996381 PMCID: PMC2838524 DOI: 10.1152/ajpendo.00417.2009] [Citation(s) in RCA: 303] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Chronic inflammation is an important etiology underlying obesity-related disorders such as insulin resistance and type 2 diabetes, and recent findings indicate that the macrophage can be the initiating cell type responsible for this chronic inflammatory state. The mammalian silent information regulator 2 homolog SIRT1 modulates several physiological processes important for life span, and a potential role of SIRT1 in the regulation of insulin sensitivity has been shown. However, with respect to inflammation, the role of SIRT1 in regulating the proinflammatory pathway within macrophages is poorly understood. Here, we show that knockdown of SIRT1 in the mouse macrophage RAW264.7 cell line and in intraperitoneal macrophages broadly activates the JNK and IKK inflammatory pathways and increases LPS-stimulated TNFalpha secretion. Moreover, gene expression profiles reveal that SIRT1 knockdown leads to an increase in inflammatory gene expression. We also demonstrate that SIRT1 activators inhibit LPS-stimulated inflammatory pathways, as well as secretion of TNFalpha, in a SIRT1-dependent manner in RAW264.7 cells and in primary intraperitoneal macrophages. Treatment of Zucker fatty rats with a SIRT1 activator leads to greatly improved glucose tolerance, reduced hyperinsulinemia, and enhanced systemic insulin sensitivity during glucose clamp studies. These in vivo insulin-sensitizing effects were accompanied by a reduction in tissue inflammation markers and a decrease in the adipose tissue macrophage proinflammatory state, fully consistent with the in vitro effects of SIRT1 in macrophages. In conclusion, these results define a novel role for SIRT1 as an important regulator of macrophage inflammatory responses in the context of insulin resistance and raise the possibility that targeting of SIRT1 might be a useful strategy for treating the inflammatory component of metabolic diseases.
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Affiliation(s)
- Takeshi Yoshizaki
- Department of Medicine, Univ. of California, San Diego, La Jolla, 92037-0673, USA
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83
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Wang T, Villegas S, Huang Y, White SK, Ahlem C, Lu M, Olefsky JM, Reading C, Frincke JM, Alleva D, Flores-Riveros J. Amelioration of glucose intolerance by the synthetic androstene HE3286: link to inflammatory pathways. J Pharmacol Exp Ther 2010; 333:70-80. [PMID: 20068030 DOI: 10.1124/jpet.109.161182] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Insulin resistance, the major metabolic abnormality underlying type 2 diabetes, is associated with chronic inflammation and heavy macrophage infiltration in white adipose tissue (WAT). The therapeutic properties of the synthetic adrenal steroid Delta(5)-androstene-17alpha-ethynyl-3beta,7beta,17beta-triol (HE3286) were characterized in metabolic disease models. Treatment of diabetic db/db mice with HE3286 suppressed progression to hyperglycemia and markedly improved glucose clearance. Similar effects were also observed in insulin-resistant, diet-induced obese C57BL/6J mice and genetically obese ob/ob mice. This effect appeared to be a consequence of reduced insulin resistance because HE3286 lowered blood insulin levels in db/db and ob/ob mice. Treatment with HE3286 was accompanied by suppressed expression of the prototype macrophage-attracting chemokine monocyte chemoattractant protein-1 in WAT, along with its cognate receptor C-C motif chemokine receptor-2. Exposure of mouse macrophages to HE3286 in vitro caused partial suppression of endotoxin (lipopolysaccharide)-induced nuclear factor kappa-B (NF-kappaB)-sensitive reporter gene expression, NF-kappaB nuclear translocation, and NF-kappaB/p65 serine phosphorylation. Proinflammatory kinases, including IkappaB kinase, c-Jun NH2-terminal kinase, and p38, were also inhibited by HE3286. In ligand competition experiments HE3286 did not bind to classical sex steroid or corticosteroid receptors, including androgen receptor (AR), progesterone receptor, estrogen receptor (ER) alpha or ERbeta, and glucocorticoid receptor (GR). Likewise, in cells expressing nuclear receptor-sensitive reporter genes HE3286 did not substantially stimulate transactivation of AR, ER, GR, or peroxisome proliferator-activated receptor (PPAR) alpha, PPARdelta, and PPARgamma. These findings indicate that HE3286 improves glucose homeostasis in diabetic and insulin-resistant mice and suggest that the observed therapeutic effects result from attenuation of proinflammatory pathways, independent of classic sex steroid receptors, corticosteroid receptors, or PPARs.
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Affiliation(s)
- Tianlun Wang
- Hollis-Eden Pharmaceuticals, Inc., San Diego, CA 92121, USA
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84
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Saberi M, Bjelica D, Schenk S, Imamura T, Bandyopadhyay G, Li P, Jadhar V, Vargeese C, Wang W, Bowman K, Zhang Y, Polisky B, Olefsky JM. Novel liver-specific TORC2 siRNA corrects hyperglycemia in rodent models of type 2 diabetes. Am J Physiol Endocrinol Metab 2009; 297:E1137-46. [PMID: 19706791 PMCID: PMC2781351 DOI: 10.1152/ajpendo.00158.2009] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The transcription factor TORC2 [transducer of regulated cAMP-responsive element-binding protein (CREB) activity 2] is a major regulator of hepatic gluconeogenesis and is increased in hyperglycemic rodent models. Because chronic hyperglycemia and increased hepatic glucose production, via increased gluconeogenesis, is a key feature of type 2 diabetes, an effective in vivo method to efficiently knock down TORC2 could provide a potential therapy for treating hyperglycemia and type 2 diabetes. To assess this, primary mouse hepatocytes, high-fat diet (HFD)-fed mice, and Zucker diabetic fatty (ZDF) rats were treated with a siRNA against TORC2 (siTORC2), which was delivered via a novel lipid nanoparticle system, or control siRNA (siCON). Compared with siCON, administration of siTORC2 resulted in highly efficient, sustained (1-3 wk) knockdown of TORC2 and its gluconeogenic target genes phosphoenolpyruvate carboxykinase and glucose-6-phophatase in primary mouse hepatocytes and in the livers of HFD-fed mice. In mice, this knockdown was specific to the liver and did not occur in kidney, skeletal muscle, or adipose tissue. In HFD-fed mice, siTORC2 reduced in vivo gluconeogenic capacity, fasting hepatic glucose production, and hyperglycemia, and led to improved hepatic and skeletal muscle insulin sensitivity. siTORC2 treatment also improved systemic hyperglycemia in ZDF rats. In conclusion, these results demonstrate the importance of TORC2 in modulating HGP in vivo and highlight a novel, liver-specific siRNA approach for the potential treatment of hyperglycemia and type 2 diabetes.
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MESH Headings
- Animals
- Blood Glucose/metabolism
- Blotting, Western
- Cells, Cultured
- Chemistry, Pharmaceutical
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Gluconeogenesis/drug effects
- Glucose Clamp Technique
- Hepatocytes/metabolism
- Homeostasis/drug effects
- Hyperglycemia/drug therapy
- Insulin/blood
- Insulin Resistance/physiology
- Liver/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Polymerase Chain Reaction
- Pyruvic Acid/metabolism
- RNA, Small Interfering/adverse effects
- RNA, Small Interfering/pharmacology
- RNA, Small Interfering/therapeutic use
- Rats
- Rats, Zucker
- Trans-Activators/antagonists & inhibitors
- Trans-Activators/biosynthesis
- Trans-Activators/physiology
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/biosynthesis
- Transcription Factors/physiology
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Affiliation(s)
- Maziyar Saberi
- Univ. of California-San Diego, Dept. of Medicine, 9500 Gilman Dr., SCR225, La Jolla CA 92093, USA.
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85
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Saberi M, Woods NB, de Luca C, Schenk S, Lu JC, Bandyopadhyay G, Verma IM, Olefsky JM. Hematopoietic cell-specific deletion of toll-like receptor 4 ameliorates hepatic and adipose tissue insulin resistance in high-fat-fed mice. Cell Metab 2009; 10:419-29. [PMID: 19883619 PMCID: PMC2790319 DOI: 10.1016/j.cmet.2009.09.006] [Citation(s) in RCA: 341] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2008] [Revised: 05/29/2009] [Accepted: 09/25/2009] [Indexed: 02/09/2023]
Abstract
Chronic low-grade inflammation, particularly in adipose tissue, is an important modulator of obesity-induced insulin resistance. The Toll-like receptor 4 (Tlr4) is a key initiator of inflammatory responses in macrophages. We performed bone marrow transplantation (BMT) of Tlr4lps-del or control C57Bl/10J donor cells into irradiated wild-type C57Bl6 recipient mice to generate hematopoietic cell-specific Tlr4 deletion mutant (BMT-Tlr4(-/-)) and control (BMT-WT) mice. After 16 weeks of a high-fat diet (HFD), BMT-WT mice developed obesity, hyperinsulinemia, glucose intolerance, and insulin resistance. In contrast, BMT-Tlr4(-/-) mice became obese but did not develop fasting hyperinsulinemia and had improved hepatic and adipose insulin sensitivity during euglycemic clamp studies, compared to HFD BMT-WT controls. HFD BMT-Tlr4(-/-) mice also showed markedly reduced adipose tissue inflammatory markers and macrophage content. In summary, our results indicate that Tlr4 signaling in hematopoietic-derived cells is important for the development of hepatic and adipose tissue insulin resistance in obese mice.
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Affiliation(s)
- Maziyar Saberi
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, CA 92093, USA
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86
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Abstract
Obesity leads to tissue inflammation and insulin resistance, which are features of metabolic diseases such as type 2 diabetes. Chiang et al. (2009) now show that the IkappaB kinase IKKepsilon is an important link between obesity and inflammation and may be a new therapeutic target for treating obesity-related metabolic diseases.
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Affiliation(s)
- Jerrold M Olefsky
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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87
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Patsouris D, Neels JG, Fan W, Li PP, Nguyen MTA, Olefsky JM. Glucocorticoids and thiazolidinediones interfere with adipocyte-mediated macrophage chemotaxis and recruitment. J Biol Chem 2009; 284:31223-35. [PMID: 19740750 DOI: 10.1074/jbc.m109.041665] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The link between intra-abdominal adiposity and type II diabetes has been known for decades, and adipose tissue macrophage (ATM)-associated inflammation has recently been linked to insulin resistance. However, the mechanisms associated with ATM recruitment remain ill defined. Herein, we describe in vitro chemotaxis studies, in which adipocyte conditioned medium was used to stimulate macrophage migration. We demonstrate that tumor necrosis factor alpha and free fatty acids, key inflammatory stimuli involved in obesity-associated autocrine/paracrine inflammatory signaling, stimulate adipocyte expression and secretion of macrophage chemoattractants. Pharmacological studies showed that peroxisome proliferator-activated receptor gamma agonists and glucocorticoids potently inhibit adipocyte- induced recruitment of macrophages. This latter effect was mediated by the glucocorticoid receptor, which led to decreased chemokine secretion and expression. In vivo results were quite comparable; treatment of high fat diet-fed mice with dexamethasone prevented ATM accumulation in epididymal fat. This decrease in ATM was most pronounced for the proinflammatory F4/80(+), CD11b(+), CD11c(+) M-1-like ATM subset. Overall, our results elucidate a beneficial function of peroxisome proliferator-activated receptor gamma activation and glucocorticoid receptor/glucocorticoids in adipose tissue and indicate that pharmacologic prevention of ATM accumulation could be beneficial.
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Affiliation(s)
- David Patsouris
- Division of Endocrinology-Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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88
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Morris AJ, Martin SS, Haruta T, Nelson JG, Gustafson TA, Mueckler M, Rose DW, Olefsky JM. O-20: Disruption of the interaction between the insulin receptor and IRS-1 does not impair insulin stimulated GLUT4 translocation. Exp Clin Endocrinol Diabetes 2009. [DOI: 10.1055/s-0029-1211511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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89
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Kim JJ, Li P, Huntley J, Chang JP, Arden KC, Olefsky JM. FoxO1 haploinsufficiency protects against high-fat diet-induced insulin resistance with enhanced peroxisome proliferator-activated receptor gamma activation in adipose tissue. Diabetes 2009; 58:1275-82. [PMID: 19289458 PMCID: PMC2682681 DOI: 10.2337/db08-1001] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE Forkhead box O (FoxO) transcription factors represent evolutionarily conserved targets of insulin signaling, regulating metabolism and cellular differentiation in response to changes in nutrient availability. Although the FoxO1 isoform is known to play a key role in adipogenesis, its physiological role in differentiated adipose tissue remains unclear. RESEARCH DESIGN AND METHODS In this study, we analyzed the phenotype of FoxO1 haploinsufficient mice to investigate the role of FoxO1 in high-fat diet-induced obesity and adipose tissue metabolism. RESULTS We showed that reduced FoxO1 expression protects mice against obesity-related insulin resistance with marked improvement not only in hepatic insulin sensitivity but also in skeletal muscle insulin action. FoxO1 haploinsufficiency also resulted in increased peroxisome proliferator-activated receptor (PPAR)gamma gene expression in adipose tissue, with enhanced expression of PPARgamma target genes known to influence metabolism. Moreover, treatment of mice with the PPARgamma agonist rosiglitazone caused a greater improvement in in vivo insulin sensitivity in FoxO1 haploinsufficient animals, including reductions in circulating proinflammatory cytokines. CONCLUSIONS These findings indicate that FoxO1 proteins negatively regulate insulin action and that their effect may be explained, at least in part, by inhibition of PPARgamma function.
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Affiliation(s)
- Jane J Kim
- Department of Pediatrics, University of California at San Diego, La Jolla, California, USA.
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90
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Fan W, Imamura T, Sonoda N, Sears DD, Patsouris D, Kim JJ, Olefsky JM. FOXO1 transrepresses peroxisome proliferator-activated receptor gamma transactivation, coordinating an insulin-induced feed-forward response in adipocytes. J Biol Chem 2009; 284:12188-97. [PMID: 19246449 DOI: 10.1074/jbc.m808915200] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The transcriptional factor FoxO1 plays an important role in metabolic homeostasis. Herein we identify a novel transrepressional function that converts FoxO1 from an activator of transcription to a promoter-specific repressor of peroxisome proliferator-activated receptor gamma (PPARgamma) target genes that regulate adipocyte biology. FoxO1 transrepresses PPARgamma via direct protein-protein interactions; it is recruited to PPAR response elements (PPRE) on PPARgamma target genes by PPARgamma bound to PPRE and interferes with promoter DNA occupancy of the receptor. The FoxO1 transrepressional function, which is independent and dissectible from the transactivational effects, does not require a functional FoxO1 DNA binding domain, but dose require an evolutionally conserved 31 amino acids LXXLL-containing domain. Insulin induces FoxO1 phosphorylation and nuclear exportation, which prevents FoxO1-PPARgamma interactions and rescues transrepression. Adipocytes from insulin resistant mice show reduced phosphorylation and increased nuclear accumulation of FoxO1, which is coupled to lowered expression of endogenous PPARgamma target genes. Thus the innate FoxO1 transrepression function enables insulin to augment PPARgamma activity, which in turn leads to insulin sensitization, and this feed-forward cycle represents positive reinforcing connections between insulin and PPARgamma signaling.
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Affiliation(s)
- Wuqiang Fan
- Division of Endocrinology-Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA
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91
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Vu CB, Bemis JE, Disch JS, Ng PY, Nunes JJ, Milne JC, Carney DP, Lynch AV, Smith JJ, Lavu S, Lambert PD, Gagne DJ, Jirousek MR, Schenk S, Olefsky JM, Perni RB. Discovery of Imidazo[1,2-b]thiazole Derivatives as Novel SIRT1 Activators. J Med Chem 2009; 52:1275-83. [DOI: 10.1021/jm8012954] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Chi B. Vu
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Jean E. Bemis
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Jeremy S. Disch
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Pui Yee Ng
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Joseph J. Nunes
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Jill C. Milne
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - David P. Carney
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Amy V. Lynch
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Jesse J. Smith
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Siva Lavu
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Philip D. Lambert
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - David J. Gagne
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Michael R. Jirousek
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Simon Schenk
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Jerrold M. Olefsky
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
| | - Robert B. Perni
- Sirtris Pharmaceuticals, 200 Technology Square, Cambridge, Massachusetts 02139
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92
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Abstract
Fat metabolism and glucose homeostasis are processes that are highly interconnected. Cao et al. (2008) now take this concept a step further by identifying a fatty acid metabolite generated in adipose tissue that regulates insulin sensitivity in liver and muscle.
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93
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Abstract
Insulin resistance is a major metabolic feature of obesity and is a key factor in the etiology of a number of diseases, including type 2 diabetes. In this review, we discuss potential mechanisms by which brief nutrient excess and obesity lead to insulin resistance and propose that these mechanisms of action are different but interrelated. We discuss how pathways that "sense" nutrients within skeletal muscle are readily able to regulate insulin action. We then discuss how obesity leads to insulin resistance via a complex interplay among systemic fatty acid excess, microhypoxia in adipose tissue, ER stress, and inflammation. In particular, we focus on the hypothesis that the macrophage is an important cell type in the propagation of inflammation and induction of insulin resistance in obesity. Overall, we provide our integrative perspective regarding how nutrients and obesity interact to regulate insulin sensitivity.
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Affiliation(s)
- Simon Schenk
- Department of Medicine, Division of Endocrinology and Metabolism, UCSD, La Jolla, California 92093, USA
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94
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Patsouris D, Li PP, Thapar D, Chapman J, Olefsky JM, Neels JG. Ablation of CD11c-positive cells normalizes insulin sensitivity in obese insulin resistant animals. Cell Metab 2008; 8:301-9. [PMID: 18840360 PMCID: PMC2630775 DOI: 10.1016/j.cmet.2008.08.015] [Citation(s) in RCA: 630] [Impact Index Per Article: 39.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 05/13/2008] [Accepted: 08/21/2008] [Indexed: 12/16/2022]
Abstract
Obese adipose tissue is characterized by infiltration of macrophages. We and others recently showed that a specific subset of macrophages is recruited to obese adipose and muscle tissue. This subset expresses CD11c and produces high levels of proinflammatory cytokines that are linked to the development of obesity-associated insulin resistance. Here, we used a conditional cell ablation system, based on transgenic expression of the diphtheria toxin receptor under the control of the CD11c promoter, to study the effects of depletion of CD11c+ cells in obese mouse models. Our results show that CD11c+ cell depletion results in rapid normalization of insulin sensitivity. Furthermore, CD11c+ cell ablation leads to a marked decrease in inflammatory markers, both locally and systemically, as reflected by gene expression and protein levels. Together, these results indicate that these CD11c+ cells are a potential therapeutic target for treatment of obesity-related insulin resistance and type II diabetes.
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Affiliation(s)
- David Patsouris
- Division of Endocrinology & Metabolism, Department of Medicine, University of California, San Diego, La Jolla, California, USA
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95
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Féral CC, Neels JG, Kummer C, Slepak M, Olefsky JM, Ginsberg MH. Blockade of alpha4 integrin signaling ameliorates the metabolic consequences of high-fat diet-induced obesity. Diabetes 2008; 57:1842-51. [PMID: 18426864 PMCID: PMC2453617 DOI: 10.2337/db07-1751] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 04/14/2008] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Many prevalent diseases of advanced societies, such as obesity-induced type 2 diabetes, are linked to indolent mononuclear cell-dependent inflammation. We previously proposed that blockade of alpha4 integrin signaling can inhibit inflammation while limiting mechanism-based toxicities of loss of alpha4 function. Thus, we hypothesized that mice bearing an alpha4(Y991A) mutation, which blocks signaling, would be protected from development of high-fat diet-induced insulin resistance. RESEARCH DESIGN AND METHODS Six- to eight-week-old wild-type and alpha4(Y991A) C57Bl/6 male mice were placed on either a high-fat diet that derived 60% calories from lipids or a chow diet. Metabolic testing was performed after 16-22 weeks of diet. RESULTS Alpha4(Y991A) mice were protected from development of high-fat diet-induced insulin resistance. This protection was conferred on wild-type mice by alpha4(Y991A) bone marrow transplantation. In the reverse experiment, wild-type bone marrow renders high-fat diet-fed alpha4(Y991A) acceptor animals insulin resistant. Furthermore, fat-fed alpha4(Y991A) mice showed a dramatic reduction of monocyte/macrophages in adipose tissue. This reduction was due to reduced monocyte/macrophage migration rather than reduced monocyte chemoattractant protein-1 production. CONCLUSIONS Alpha4 integrins contribute to the development of HFD-induced insulin resistance by mediating the trafficking of monocytes into adipose tissue; hence, blockade of alpha4 integrin signaling can prevent the development of obesity-induced insulin resistance.
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Affiliation(s)
- Chloé C Féral
- Department of Medicine, University of California, San Diego, La Jolla, California, USA.
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96
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Yang X, Ongusaha PP, Miles PD, Havstad JC, Zhang F, So WV, Kudlow JE, Michell RH, Olefsky JM, Field SJ, Evans RM. Phosphoinositide signalling links O-GlcNAc transferase to insulin resistance. Nature 2008; 451:964-9. [PMID: 18288188 DOI: 10.1038/nature06668] [Citation(s) in RCA: 451] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Accepted: 01/07/2008] [Indexed: 12/14/2022]
Abstract
Glucose flux through the hexosamine biosynthetic pathway leads to the post-translational modification of cytoplasmic and nuclear proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc). This tandem system serves as a nutrient sensor to couple systemic metabolic status to cellular regulation of signal transduction, transcription, and protein degradation. Here we show that O-GlcNAc transferase (OGT) harbours a previously unrecognized type of phosphoinositide-binding domain. After induction with insulin, phosphatidylinositol 3,4,5-trisphosphate recruits OGT from the nucleus to the plasma membrane, where the enzyme catalyses dynamic modification of the insulin signalling pathway by O-GlcNAc. This results in the alteration in phosphorylation of key signalling molecules and the attenuation of insulin signal transduction. Hepatic overexpression of OGT impairs the expression of insulin-responsive genes and causes insulin resistance and dyslipidaemia. These findings identify a molecular mechanism by which nutritional cues regulate insulin signalling through O-GlcNAc, and underscore the contribution of this modification to the aetiology of insulin resistance and type 2 diabetes.
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Affiliation(s)
- Xiaoyong Yang
- Howard Hughes Medical Institute and Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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97
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Abstract
Obesity-induced chronic inflammation is a key component in the pathogenesis of insulin resistance and the Metabolic syndrome. In this review, we focus on the interconnection between obesity, inflammation and insulin resistance. Pro-inflammatory cytokines can cause insulin resistance in adipose tissue, skeletal muscle and liver by inhibiting insulin signal transduction. The sources of cytokines in insulin resistant states are the insulin target tissue themselves, primarily fat and liver, but to a larger extent the activated tissue resident macrophages. While the initiating factors of this inflammatory response remain to be fully determined, chronic inflammation in these tissues could cause localized insulin resistance via autocrine/paracrine cytokine signaling and systemic insulin resistance via endocrine cytokine signaling all of which contribute to the abnormal metabolic state.
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Affiliation(s)
- Carl de Luca
- University of California at San Diego, Department of Medicine (0673), 225 Stein Clinical Research Building, 9500 Gilman Drive, La Jolla, CA 92093, USA
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98
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Lu M, Tang Q, Olefsky JM, Mellon PL, Webster NJG. Adiponectin activates adenosine monophosphate-activated protein kinase and decreases luteinizing hormone secretion in LbetaT2 gonadotropes. Mol Endocrinol 2007; 22:760-71. [PMID: 18006641 DOI: 10.1210/me.2007-0330] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Metabolic dysregulation is associated with reproductive disorders, but the underlying mechanisms are not clearly understood. Adiponectin is an adipocyte-derived secretory factor that improves insulin sensitivity. Results from animal models indicate that overexpression of adiponectin impairs female fertility. We hypothesized that adiponectin regulates reproduction by altering the hypothalamic-pituitary axis. Mouse LbetaT2 immortalized gonadotrope cells express both adiponectin receptors 1 and 2. Adiponectin increases phosphorylation of AMP-activated protein kinase (AMPK), a downstream target of adiponectin receptors, and reduces basal and GnRH-stimulated LH secretion, acutely. The repression of LH secretion can be mimicked by 5-aminoimidazole-4-carboxamide-1-beta-riboside, an AMP analog, suggesting the involvement of AMPK. A dominant-negative AMPK mutant or compound C, a selective AMPK inhibitor, potentiates basal LH secretion and abolishes the inhibitory effect of adiponectin. Chronic activation of AMPK by 5-aminoimidazole-4-carboxamide-1-beta-riboside decreases cellular LH levels, and expression of dominant-negative AMPK increases cellular LH levels, suggesting a second effect of AMPK to regulate LH synthesis. Lastly, intravenous injection of an adenovirus expressing adiponectin into male mice reduces serum LH levels without changing FSH levels. In conclusion, our results suggest that adiponectin decreases LH secretion in pituitary gonadotropes in an AMPK-dependent manner.
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Affiliation(s)
- Min Lu
- Department of Medicine, University of California, San Diego, California 92093, USA
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99
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Solinas G, Vilcu C, Neels JG, Bandyopadhyay GK, Luo JL, Naugler W, Grivennikov S, Wynshaw-Boris A, Scadeng M, Olefsky JM, Karin M. JNK1 in hematopoietically derived cells contributes to diet-induced inflammation and insulin resistance without affecting obesity. Cell Metab 2007; 6:386-97. [PMID: 17983584 DOI: 10.1016/j.cmet.2007.09.011] [Citation(s) in RCA: 420] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 08/21/2007] [Accepted: 09/26/2007] [Indexed: 12/13/2022]
Abstract
Obesity-induced insulin resistance is a major factor in the etiology of type 2 diabetes, and Jun kinases (JNKs) are key negative regulators of insulin sensitivity in the obese state. Activation of JNKs (mainly JNK1) in insulin target cells results in phosphorylation of insulin receptor substrates (IRSs) at serine and threonine residues that inhibit insulin signaling. JNK1 activation is also required for accumulation of visceral fat. Here we used reciprocal adoptive transfer experiments to determine whether JNK1 in myeloid cells, such as macrophages, also contributes to insulin resistance and central adiposity. Our results show that deletion of Jnk1 in the nonhematopoietic compartment protects mice from high-fat diet (HFD)-induced insulin resistance, in part through decreased adiposity. By contrast, Jnk1 removal from hematopoietic cells has no effect on adiposity but confers protection against HFD-induced insulin resistance by decreasing obesity-induced inflammation.
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Affiliation(s)
- Giovanni Solinas
- Department of Medicine, University of Fribourg, Chemin du Musée 5, CH-1700 Fribourg, Switzerland
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100
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Sears DD, Hsiao A, Ofrecio JM, Chapman J, He W, Olefsky JM. Selective modulation of promoter recruitment and transcriptional activity of PPARgamma. Biochem Biophys Res Commun 2007; 364:515-21. [PMID: 17963725 DOI: 10.1016/j.bbrc.2007.10.057] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Accepted: 10/07/2007] [Indexed: 10/22/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor regulated by the insulin-sensitizing thiazolidinediones (TZDs). We studied selective modulation of endogenous genes by PPARgamma ligands using microarray, RNA expression kinetics, and chromatin immunoprecipitation (ChIP) in 3T3-L1 adipocytes. We found over 300 genes that were significantly regulated the TZDs pioglitazone, rosiglitazone, and troglitazone. TZD-mediated expression profiles were unique but overlapping. Ninety-one genes were commonly regulated by all three ligands. TZD time course and dose-response studies revealed gene- and TZD-specific expression kinetics. PEPCK expression was induced rapidly but PDK4 expression was induced gradually. Troglitazone EC50 values for PEPCK, PDK4, and RGS2 regulation were greater than those for pioglitazone and rosiglitazone. TZDs differentially induced histone acetylation of and PPARgamma recruitment to target gene promoters. Selective modulation of PPARgamma by TZDs resulted in distinct expression profiles and transcription kinetics which may be due to differential promoter activation and chromatin remodeling of target genes.
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Affiliation(s)
- Dorothy D Sears
- Department of Medicine, University of California, San Diego, 9500 Gilman Drive, MC0673, La Jolla, CA 92093, USA.
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