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Mowers J, Uhm M, Reilly SM, Simon J, Leto D, Chiang SH, Chang L, Saltiel AR. Inflammation produces catecholamine resistance in obesity via activation of PDE3B by the protein kinases IKKε and TBK1. eLife 2013; 2:e01119. [PMID: 24368730 PMCID: PMC3869376 DOI: 10.7554/elife.01119] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Obesity produces a chronic inflammatory state involving the NFκB pathway, resulting in persistent elevation of the noncanonical IκB kinases IKKε and TBK1. In this study, we report that these kinases attenuate β-adrenergic signaling in white adipose tissue. Treatment of 3T3-L1 adipocytes with specific inhibitors of these kinases restored β-adrenergic signaling and lipolysis attenuated by TNFα and Poly (I:C). Conversely, overexpression of the kinases reduced induction of Ucp1, lipolysis, cAMP levels, and phosphorylation of hormone sensitive lipase in response to isoproterenol or forskolin. Noncanonical IKKs reduce catecholamine sensitivity by phosphorylating and activating the major adipocyte phosphodiesterase PDE3B. In vivo inhibition of these kinases by treatment of obese mice with the drug amlexanox reversed obesity-induced catecholamine resistance, and restored PKA signaling in response to injection of a β-3 adrenergic agonist. These studies suggest that by reducing production of cAMP in adipocytes, IKKε and TBK1 may contribute to the repression of energy expenditure during obesity. DOI:http://dx.doi.org/10.7554/eLife.01119.001 Obesity is a complex metabolic disorder that is caused by increased food intake and decreased expenditure of energy. Obesity also increases the risk of developing type 2 diabetes, heart disease, stroke, arthritis, and certain cancers. There is considerable evidence to suggest that adipose tissue becomes less sensitive to catecholamines such as adrenaline in states of obesity, and that this reduced sensitivity in turn reduces energy expenditure. However, the details of this process are not fully understood. It is well established that obesity generates a state of chronic, low-grade inflammation in liver and adipose tissue, accompanied by the secretion of signaling proteins that prevent fat cells from responding to insulin, which leads to type 2 diabetes. Activation of the NFκB pathway is thought to have a central role in causing this inflammation. Now Mowers et al. have investigated whether inflammation caused by activation of the NFκB pathway also has a role in producing catecholamine resistance in fat cells. Obesity-dependent activation of the NFκB pathway increases the levels of a pair of enzymes, IKKε and TBK1. Mowers et al. found that elevated levels of these two enzymes reduced the ability of certain receptors (called β-adrenergic receptors) in the fat cells of obese mice to respond to catecholamines. High levels of the two enzymes also resulted in lower levels of a second messenger molecule called cAMP, which increases energy expenditure by elevating fat burning. However, treating the fat cells with drugs that interfere with the two enzymes restored sensitivity to catecholamine, allowing the fat cells to burn energy. Mowers et al. also treated obese mice with amlexanox, a drug that inhibits these enzymes, and found that this treatment made the mice sensitive to a synthetic catecholamine that triggered the release of energy from fat. Mowers et al. suggest, therefore, that IKKε and TBK1 respond to inflammation in the body by reducing catecholamine signaling, thus preventing energy expenditure. Drugs targeting these enzymes may be useful for treating conditions like obesity or type 2 diabetes. DOI:http://dx.doi.org/10.7554/eLife.01119.002
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Affiliation(s)
- Jonathan Mowers
- Life Sciences Institute, University of Michigan, Ann Arbor, United States
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202
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Prada PO, Saad MJ. Tyrosine kinase inhibitors as novel drugs for the treatment of diabetes. Expert Opin Investig Drugs 2013; 22:751-63. [PMID: 23705634 DOI: 10.1517/13543784.2013.802768] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
INTRODUCTION Some inhibitors of tyrosine kinase, as imatinib, erlotinib and sunitinib have antihyperglycemic effects but the mechanisms are not totally clear. AREAS COVERED It is well established that insulin resistance and beta-cell failure are hallmarks of type 2 diabetes mellitus (DM2). The present review will discuss the molecular mechanisms that account for insulin resistance and beta-cell failure in DM2, and also the effect of tyrosine kinase inhibitors in these processes. EXPERT OPINION A better understanding of how these drugs improve the two most important mechanisms of DM2 associated with suggestions of clinical studies will lead to improve the treatment of this disease.
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Affiliation(s)
- Patricia O Prada
- University of Campinas - UNICAMP, School of Applied Sciences, Limeira, SP, 13484-350, Brazil.
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203
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CEACAM1 loss links inflammation to insulin resistance in obesity and non-alcoholic steatohepatitis (NASH). Semin Immunopathol 2013; 36:55-71. [PMID: 24258517 DOI: 10.1007/s00281-013-0407-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/13/2013] [Indexed: 02/06/2023]
Abstract
Mounting epidemiological evidence points to an association between metabolic syndrome and non-alcoholic steatohepatitis (NASH), an increasingly recognized new epidemic. NASH pathologies include hepatocellular ballooning, lobular inflammation, hepatocellular injury, apoptosis, and hepatic fibrosis. We will review the relationship between insulin resistance and inflammation in visceral obesity and NASH in an attempt to shed more light on the pathogenesis of these major metabolic diseases. Moreover, we will identify loss of the carcinoembryonic antigen-related cell adhesion molecule 1 as a unifying mechanism linking the immunological and metabolic abnormalities in NASH.
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204
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Immune cells and metabolic dysfunction. Semin Immunopathol 2013; 36:13-25. [PMID: 24212254 DOI: 10.1007/s00281-013-0403-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 10/15/2013] [Indexed: 02/06/2023]
Abstract
Throughout evolution, effective nutrient sensing and control of systemic energy homeostasis have relied on a close physical and functional interaction between immune and metabolically active cells. However, in today's obesogenic environment, this fine-tuned immunometabolic interface is perturbed. As a consequence, chronic inflammatory conditions and aberrant activation of immune cells have emerged as key features of obesity-related metabolic disorders, including insulin resistance, cardiovascular complications, and type 2 diabetes, whereas a major research focus has been placed on the adipocyte-macrophage interaction in the context of metabolic dysfunction; recent studies have not only expanded the scope of relevant immune cells in this setting but also highlight the impact of distinct metabolic organs, including the liver, on immunometabolic control, metabolic disease development, and potential anti-inflammatory therapeutic options in obesity-driven pathologies. This review will thus summarize recent progress in this emerging area of metabolic research.
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205
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Brown and beige fat: development, function and therapeutic potential. Nat Med 2013; 19:1252-63. [PMID: 24100998 DOI: 10.1038/nm.3361] [Citation(s) in RCA: 1672] [Impact Index Per Article: 152.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 08/27/2013] [Indexed: 12/13/2022]
Abstract
Adipose tissue, best known for its role in fat storage, can also suppress weight gain and metabolic disease through the action of specialized, heat-producing adipocytes. Brown adipocytes are located in dedicated depots and express constitutively high levels of thermogenic genes, whereas inducible 'brown-like' adipocytes, also known as beige cells, develop in white fat in response to various activators. The activities of brown and beige fat cells reduce metabolic disease, including obesity, in mice and correlate with leanness in humans. Many genes and pathways that regulate brown and beige adipocyte biology have now been identified, providing a variety of promising therapeutic targets for metabolic disease.
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206
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Cheng X, Guo S, Liu Y, Chu H, Hakimi P, Berger NA, Hanson RW, Kao HY. Ablation of promyelocytic leukemia protein (PML) re-patterns energy balance and protects mice from obesity induced by a Western diet. J Biol Chem 2013; 288:29746-59. [PMID: 23986437 DOI: 10.1074/jbc.m113.487595] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The promyelocytic leukemia protein is a well known tumor suppressor, but its role in metabolism is largely unknown. Mice with a deletion in the gene for PML (KO mice) exhibit altered gene expression in liver, adipose tissue, and skeletal muscle, an accelerated rate of fatty acid metabolism, abnormal glucose metabolism, constitutive AMP-activating kinase (AMPK) activation, and insulin resistance in skeletal muscle. Last, an increased rate of energy expenditure protects PML KO mice from the effects of obesity induced by a Western diet. Collectively, our study uncovers a previously unappreciated role of PML in the regulation of metabolism and energy balance in mice.
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207
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Wang XA, Zhang R, Zhang S, Deng S, Jiang D, Zhong J, Yang L, Wang T, Hong S, Guo S, She ZG, Zhang XD, Li H. Interferon regulatory factor 7 deficiency prevents diet-induced obesity and insulin resistance. Am J Physiol Endocrinol Metab 2013; 305:E485-95. [PMID: 23695216 DOI: 10.1152/ajpendo.00505.2012] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Obesity-related inflammation has been implicated in the pathogenesis of insulin resistance and type 2 diabetes. In this study, we addressed the potential role of interferon regulatory factor 7 (IRF7), a master regulator of type I interferon-dependent immune responses, in the regulation of energy metabolism. The expression levels of IRF7 were increased in white adipose tissue, liver tissue, and gastrocnemius muscle of both diet-induced obese mice and ob/ob mice compared with their lean counterparts. After feeding a high-fat diet (HFD) for 24 wk, IRF7 knockout (KO) mice showed less weight gain and adiposity than wild-type controls. KO of IRF7 improved glucose and lipid homeostasis and insulin sensitivity. Additionally, KO of IRF7 ameliorated diet-induced hepatic steatosis. Next, we assessed the inflammatory state of the IRF7 KO mice on the HFD. These mice showed less macrophage infiltration into multiple organs and were protected from local and systemic inflammation. This study demonstrates a role for IRF7 in diet-induced alterations in energy metabolism and insulin sensitivity. Our results also suggest that IRF7 is involved in the etiology of metabolic abnormalities, which suggests a new strategy for treating obesity and type 2 diabetes.
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MESH Headings
- Adiposity
- Animals
- Diabetes Mellitus, Type 2/etiology
- Diabetes Mellitus, Type 2/immunology
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Diet, High-Fat/adverse effects
- Endoplasmic Reticulum Stress
- Energy Metabolism
- Fatty Liver/etiology
- Fatty Liver/immunology
- Fatty Liver/metabolism
- Fatty Liver/pathology
- Insulin Resistance
- Interferon Regulatory Factor-7/biosynthesis
- Interferon Regulatory Factor-7/genetics
- Interferon Regulatory Factor-7/metabolism
- Intra-Abdominal Fat/immunology
- Intra-Abdominal Fat/metabolism
- Intra-Abdominal Fat/pathology
- Liver/immunology
- Liver/metabolism
- Liver/pathology
- Macrophages/immunology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Obese
- Muscle, Skeletal/immunology
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Non-alcoholic Fatty Liver Disease
- Obesity/etiology
- Obesity/immunology
- Obesity/metabolism
- Obesity/pathology
- Random Allocation
- Up-Regulation
- Weight Gain
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Affiliation(s)
- Xin-An Wang
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
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208
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Kim YJ, Choi MS, Cha BY, Woo JT, Park YB, Kim SR, Jung UJ. Long-term supplementation of honokiol and magnolol ameliorates body fat accumulation, insulin resistance, and adipose inflammation in high-fat fed mice. Mol Nutr Food Res 2013; 57:1988-98. [PMID: 23901038 DOI: 10.1002/mnfr.201300113] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 12/12/2022]
Abstract
SCOPE This study investigated the effect of honokiol (HON) and magnolol (MAG), phenolic compounds in Magnolia plants, on adiposity and adiposity-related metabolic disturbances in mice fed high-fat diet (HFD), and the potential underlying mechanisms focusing on the lipid metabolism and inflammatory response. METHOD AND RESULTS C57BL/6J mice were fed HFD (45 kcal% fat) with or without HON (0.02%, w/w) or MAG (0.02%, w/w) for 16 wk. Despite no changes in body weight, food intake, and hepatic fat accumulation, HON and MAG significantly lowered the weight of white adipose tissue (WAT) as well as adipocyte size and protected against insulin resistance induced by HFD. These effects were associated with increases in energy expenditure and adipose fatty acid oxidation and decreases in fatty acid synthase activity and expression of genes related to fatty acid synthesis, desaturation, and uptake, as well as adipocyte differentiation in WAT. Moreover, HON and MAG significantly lowered the expression of proinflammatory genes in WAT and elevated the plasma IL-10 level. Particularly, HON significantly decreased the plasma resistin level and increased the plasma adiponectin level compared to the control group. CONCLUSION HON and MAG have potential as novel agents for amelioration of adiposity and associated insulin resistance and inflammation.
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Affiliation(s)
- Young-Je Kim
- Department of Food Science and Nutrition, Kyungpook National University, Daegu, Republic of Korea
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209
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Beaven SW, Matveyenko A, Wroblewski K, Chao L, Wilpitz D, Hsu TW, Lentz J, Drew B, Hevener AL, Tontonoz P. Reciprocal regulation of hepatic and adipose lipogenesis by liver X receptors in obesity and insulin resistance. Cell Metab 2013; 18:106-17. [PMID: 23823481 PMCID: PMC4089509 DOI: 10.1016/j.cmet.2013.04.021] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 03/28/2013] [Accepted: 04/26/2013] [Indexed: 12/25/2022]
Abstract
Liver X receptors (LXRs) regulate lipogenesis and inflammation, but their contribution to the metabolic syndrome is unclear. We show that LXRs modulate key aspects of the metabolic syndrome in mice. LXRαβ-deficient-ob/ob (LOKO) mice remain obese but show reduced hepatic steatosis and improved insulin sensitivity compared to ob/ob mice. Impaired hepatic lipogenesis in LOKO mice is accompanied by reciprocal increases in adipose lipid storage, reflecting tissue-selective effects on the SREBP, PPARγ, and ChREBP lipogenic pathways. LXRs are essential for obesity-driven SREBP-1c and ChREBP activity in liver, but not fat. Furthermore, loss of LXRs in obesity promotes adipose PPARγ and ChREBP-β activity, leading to improved insulin sensitivity. LOKO mice also exhibit defects in β cell mass and proliferation despite improved insulin sensitivity. Our data suggest that sterol sensing by LXRs in obesity is critically linked with lipid and glucose homeostasis and provide insight into the complex relationships between LXR and insulin signaling.
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Affiliation(s)
- Simon W Beaven
- Howard Hughes Medical Institute and Department of Pathology and Laboratory Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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210
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Cildir G, Akıncılar SC, Tergaonkar V. Chronic adipose tissue inflammation: all immune cells on the stage. Trends Mol Med 2013; 19:487-500. [PMID: 23746697 DOI: 10.1016/j.molmed.2013.05.001] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/03/2013] [Accepted: 05/06/2013] [Indexed: 12/12/2022]
Abstract
Inflammation is indispensable for host homeostasis against invading pathogens and efficient wound healing upon tissue malfunction and has to be tightly controlled by various mechanisms to limit excess responses harmful to host tissues. A myriad of disease conditions ranging from type 2 diabetes (T2D) to neurodegenerative and cardiovascular disorders are now shown to progress due to persistent, unresolved inflammation in metabolic tissues such as adipose, liver, pancreas, muscle, and brain. However, their underlying mechanisms are incompletely understood. The actions of innate and adaptive immune cells in these ailments are increasingly appreciated so much so that a new research area called 'immunometabolism' has emerged. In this review, we will highlight the fundamental roles of various immune cells in adipose tissue during the initiation and progression of obesity-induced inflammation and discuss potential anti-inflammatory therapies from different mechanistic points of view.
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Affiliation(s)
- Gökhan Cildir
- Laboratory of NF-κB Signaling, Institute of Molecular and Cell Biology (IMCB), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore
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211
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Cao C, Zhu Y, Chen W, Li L, Qi Y, Wang X, Zhao Y, Wan X, Chen X. IKKε knockout prevents high fat diet induced arterial atherosclerosis and NF-κB signaling in mice. PLoS One 2013; 8:e64930. [PMID: 23741427 PMCID: PMC3669140 DOI: 10.1371/journal.pone.0064930] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 04/19/2013] [Indexed: 01/16/2023] Open
Abstract
AIMS Atherosclerosis is a public health concern affecting many worldwide, but its pathogenesis remains unclear. In this study we investigated the role of IKKε during the formation of atherosclerosis and its molecular mechanism in the mouse aortic vessel wall. METHODS AND RESULTS C57BL/6 wild-type or IKKε knockout mice bred into the ApoE knockout genetic background were divided into 4 groups: (1) wild-type (WT), (2) ApoE knockout (AK), (3) IKKε knockout (IK), (4) or both ApoE and IKKε knockout (DK). Each group of mice were fed with a high fat diet (HFD) for 12 weeks from 8 weeks of age. Immunohistochemistry and Western blotting analysis demonstrated obvious increases in the expression of IKKε in the AK group compared with the WT group, especially in the intima. Serum lipid levels were significantly higher in the AK and DK groups than in the other two groups. Staining with hematoxylin-eosin and Oil Red, as well as scanning electron microscopy revealed less severe atherosclerotic lesions in the DK group than in the AK group. Immunofluorescence and Western blot analysis demonstrated obvious increases in the expression of NF-κB pathway components and downstream factors in the AK group, especially in the intima, while these increases were blocked in the DK group. CONCLUSION The knockout of IKKε prevented significant atherosclerosis lesions in the mouse aorta from in both wild-type and ApoE knockout mice fed a HFD, suggesting that IKKε may play a vital role in HFD-induced atherosclerosis and would be an important target for the treatment of atherosclerosis.
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Affiliation(s)
- Changchun Cao
- Division of Nephrology, Department of medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yifan Zhu
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wen Chen
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Liangpeng Li
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yongchao Qi
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xiaodi Wang
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ye Zhao
- Division of Nephrology, Department of medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xin Wan
- Division of Nephrology, Department of medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xin Chen
- Division of Thoracic and Cardiovascular Surgery, Department of surgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, China
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212
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213
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Bonet ML, Oliver P, Palou A. Pharmacological and nutritional agents promoting browning of white adipose tissue. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1831:969-85. [DOI: 10.1016/j.bbalip.2012.12.002] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 12/03/2012] [Accepted: 12/04/2012] [Indexed: 11/29/2022]
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214
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Effects of IKKɛ on Oxidised Low-density Lipoprotein-induced Injury in Vascular Endothelial Cells. Heart Lung Circ 2013; 22:366-72. [DOI: 10.1016/j.hlc.2012.11.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/11/2012] [Accepted: 11/19/2012] [Indexed: 12/11/2022]
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215
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Rajakumari S, Wu J, Ishibashi J, Lim HW, Giang AH, Won KJ, Reed RR, Seale P. EBF2 determines and maintains brown adipocyte identity. Cell Metab 2013; 17:562-74. [PMID: 23499423 PMCID: PMC3622114 DOI: 10.1016/j.cmet.2013.01.015] [Citation(s) in RCA: 267] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/03/2013] [Accepted: 01/23/2013] [Indexed: 11/24/2022]
Abstract
The master transcription factor Pparγ regulates the general differentiation program of both brown and white adipocytes. However, it has been unclear whether Pparγ also controls fat lineage-specific characteristics. Here, we show that early B cell factor-2 (Ebf2) regulates Pparγ binding activity to determine brown versus white adipocyte identity. The Ebf DNA-binding motif was highly enriched within brown adipose-specific Pparγ binding sites that we identified by genome-wide ChIP-Seq. Of the Ebf isoforms, Ebf2 was selectively expressed in brown relative to white adipocytes and was bound at brown adipose-specific Pparγ target genes. When expressed in myoblasts or white preadipose cells, Ebf2 recruited Pparγ to its brown-selective binding sites and reprogrammed cells to a brown fat fate. Brown adipose cells and tissue from Ebf2-deficient mice displayed a loss of brown-specific characteristics and thermogenic capacity. Together, these results identify Ebf2 as a key transcriptional regulator of brown fat cell fate and function.
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Affiliation(s)
- Sona Rajakumari
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
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216
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Nagai Y, Watanabe Y, Takatsu K. The TLR family protein RP105/MD-1 complex: A new player in obesity and adipose tissue inflammation. Adipocyte 2013; 2:61-6. [PMID: 23805400 PMCID: PMC3661108 DOI: 10.4161/adip.22929] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 11/14/2012] [Accepted: 11/16/2012] [Indexed: 12/20/2022] Open
Abstract
The radioprotective 105 (RP105)/MD-1 complex is a member of the Toll-like receptor (TLR) family of proteins. We have previously reported that this complex cooperates with the essential lipopolysaccharide (LPS) receptor TLR4/MD-2 complex and plays a crucial role in LPS responses by B cells. Recent evidences suggest that TLRs can also recognize endogenous ligands and promote non-infectious chronic inflammation. For instance, TLR4/MD-2 can be ligated by adipose tissue-derived saturated free fatty acids (FAs) and induce adipose tissue inflammation and insulin resistance. Recently, we reported that RP105 knockout (KO) or MD-1 KO mice have less high-fat diet (HFD)-induced obesity, adipose tissue inflammation and insulin resistance than wild-type (WT) or TLR4 KO mice. As RP105/MD-1 is not involved in recognition of palmitic and stearic acids, which are endogenous ligands for TLR4/MD-2, we conclude that RP105/MD-1 is itself a key regulator of diet-induced chronic inflammation in adipose tissue, obesity and insulin resistance that appears to be independent of the TLR4-dependent pathway. In this mini-review, we will highlight the significance of the RP105/MD-1 complex in adipose tissue inflammation and discuss implications for human diseases.
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217
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Abstract
One of the most promising areas in the therapeutics for metabolic diseases centers around activation of the pathways of energy expenditure. Brown adipose tissue is a particularly appealing target for increasing energy expenditure, given its amazing capacity to transform chemical energy into heat. In addition to classical brown adipose tissue, the last few years have seen great advances in our understanding of inducible thermogenic adipose tissue, also referred to as beige fat. A deeper understanding of the molecular processes involved in the development and function of these cell types may lead to new therapeutics for obesity, diabetes, and other metabolic diseases.
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218
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Qiu W, Wee K, Takeda K, Lim X, Sugii S, Radda GK, Han W. Suppression of adipogenesis by pathogenic seipin mutant is associated with inflammatory response. PLoS One 2013; 8:e57874. [PMID: 23520483 PMCID: PMC3592919 DOI: 10.1371/journal.pone.0057874] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 01/29/2013] [Indexed: 02/07/2023] Open
Abstract
Background While pathogenic mutations in BSCL2/Seipin cause congenital generalized lipodystrophy, the underlying mechanism is largely unknown. In this study, we investigated whether and how the pathogenic missense A212P mutation of Seipin (Seipin-A212P) inhibits adipogenesis. Methodology/Results We analyzed gene expression and lipid accumulation in stable 3T3-L1 cell lines expressing wild type (3T3-WT), non-lipodystrophic mutants N88S (3T3-N88S) and S90L (3T3-S90L), or lipodystrophic mutant A212P Seipin (3T3-A212P). When treated with adipogenic cocktail, 3T3-WT, 3T3-N88S and 3T3-S90L cells exhibited proper differentiation into mature adipocytes, indistinguishable from control 3T3-L1 cells. In contrast, adipogenesis was significantly impaired in 3T3-A212P cells. The defective adipogenesis in 3T3-A212P cells could be partially rescued by either PPARγ agonist or PPARγ overexpression. Gene expression profiling by microarray revealed that inhibition of adipogenesis was associated with activation of inflammatory genes including IL-6 and iNOS. We further demonstrated that Seipin-A212P expression at pre-differentiation stages significantly activated inflammatory responses by using an inducible expression system. The inflammation-associated inhibition of adipogenesis could be rescued by treatment with anti-inflammatory agents. Conclusions These results suggest that pathogenic Seipin-A212P inhibits adipogenesis and the inhibition is associated with activation of inflammatory pathways at pre-differentiation stages. Use of anti-inflammatory drugs may be a potential strategy for the treatment of lipodystrophy.
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Affiliation(s)
- Wenjie Qiu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
| | - Kenneth Wee
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
| | - Kosuke Takeda
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
| | - Xuemei Lim
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
| | - Shigeki Sugii
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
- Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore, Republic of Singapore
- * E-mail: (WH) (SS); (SS) (WH)
| | - George K. Radda
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, Republic of Singapore
- Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore, Republic of Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
- Metabolism in Human Diseases, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, Republic of Singapore
- * E-mail: (WH) (SS); (SS) (WH)
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Tu D, Zhu Z, Zhou AY, Yun CH, Lee KE, Toms AV, Li Y, Dunn GP, Chan E, Thai T, Yang S, Ficarro SB, Marto JA, Jeon H, Hahn WC, Barbie DA, Eck MJ. Structure and ubiquitination-dependent activation of TANK-binding kinase 1. Cell Rep 2013; 3:747-58. [PMID: 23453972 DOI: 10.1016/j.celrep.2013.01.033] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 11/05/2012] [Accepted: 01/28/2013] [Indexed: 12/28/2022] Open
Abstract
Upon stimulation by pathogen-associated inflammatory signals, TANK-binding kinase 1 (TBK1) induces type I interferon expression and modulates nuclear factor κB (NF-κB) signaling. Here, we describe the 2.4 Å-resolution crystal structure of nearly full-length TBK1 in complex with specific inhibitors. The structure reveals a dimeric assembly created by an extensive network of interactions among the kinase, ubiquitin-like, and scaffold/dimerization domains. An intact TBK1 dimer undergoes K63-linked polyubiquitination on lysines 30 and 401, and these modifications are required for TBK1 activity. The ubiquitination sites and dimer contacts are conserved in the close homolog inhibitor of κB kinase ε (IKKε) but not in IKKβ, a canonical IKK that assembles in an unrelated manner. The multidomain architecture of TBK1 provides a structural platform for integrating ubiquitination with kinase activation and IRF3 phosphorylation. The structure of TBK1 will facilitate studies of the atypical IKKs in normal and disease physiology and further the development of more specific inhibitors that may be useful as anticancer or anti-inflammatory agents.
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Affiliation(s)
- Daqi Tu
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
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220
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An inhibitor of the protein kinases TBK1 and IKK-ɛ improves obesity-related metabolic dysfunctions in mice. Nat Med 2013; 19:313-21. [PMID: 23396211 PMCID: PMC3594079 DOI: 10.1038/nm.3082] [Citation(s) in RCA: 336] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 12/26/2012] [Indexed: 12/13/2022]
Abstract
Emerging evidence suggests that inflammation provides a link between obesity and insulin resistance. The noncanonical IκB kinases IKK-ɛ and TANK-binding kinase 1 (TBK1) are induced in liver and fat by NF-κB activation upon high-fat diet feeding and in turn initiate a program of counterinflammation that preserves energy storage. Here we report that amlexanox, an approved small-molecule therapeutic presently used in the clinic to treat aphthous ulcers and asthma, is an inhibitor of these kinases. Treatment of obese mice with amlexanox elevates energy expenditure through increased thermogenesis, producing weight loss, improved insulin sensitivity and decreased steatosis. Because of its record of safety in patients, amlexanox may be an interesting candidate for clinical evaluation in the treatment of obesity and related disorders.
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221
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Liew CW, Boucher J, Cheong JK, Vernochet C, Koh HJ, Mallol C, Townsend K, Langin D, Kawamori D, Hu J, Tseng YH, Hellerstein MK, Farmer SR, Goodyear L, Doria A, Blüher M, Hsu SIH, Kulkarni RN. Ablation of TRIP-Br2, a regulator of fat lipolysis, thermogenesis and oxidative metabolism, prevents diet-induced obesity and insulin resistance. Nat Med 2013; 19:217-26. [PMID: 23291629 PMCID: PMC3567215 DOI: 10.1038/nm.3056] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 11/19/2012] [Indexed: 12/14/2022]
Abstract
Obesity develops as a result of altered energy homeostasis favoring fat storage. Here we describe a new transcription co-regulator for adiposity and energy metabolism, SERTA domain containing 2 (TRIP-Br2, also called SERTAD2). TRIP-Br2-null mice are resistant to obesity and obesity-related insulin resistance. Adipocytes of these knockout mice showed greater stimulated lipolysis secondary to enhanced expression of hormone sensitive lipase (HSL) and β3-adrenergic (Adrb3) receptors. The knockout mice also have higher energy expenditure because of increased adipocyte thermogenesis and oxidative metabolism caused by upregulating key enzymes in their respective processes. Our data show that a cell-cycle transcriptional co-regulator, TRIP-Br2, modulates fat storage through simultaneous regulation of lipolysis, thermogenesis and oxidative metabolism. These data, together with the observation that TRIP-Br2 expression is selectively elevated in visceral fat in obese humans, suggests that this transcriptional co-regulator is a new therapeutic target for counteracting the development of obesity, insulin resistance and hyperlipidemia.
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Affiliation(s)
- Chong Wee Liew
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Jeremie Boucher
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Jit Kong Cheong
- Cancer & Stem Cell Biology Program, Duke-NUS Graduate Medical School, 8 College Road, 169857, Singapore
| | - Cecile Vernochet
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Ho-Jin Koh
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Cristina Mallol
- Center of Animal Biotechnology and Gene Therapy, Edifici H, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
| | - Kristy Townsend
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Dominique Langin
- INSERM U1048, Obesity Research Laboratory, Institute of Metabolic and Cardiovascular Diseases, Toulouse, France
| | - Dan Kawamori
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Jiang Hu
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Yu-Hua Tseng
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Marc K Hellerstein
- Department of Nutritional Science and Toxicology, 220 Morgan Hall, University of California, Berkeley, California 94720, USA
| | - Stephen R Farmer
- Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
| | - Laurie Goodyear
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | - Alessandro Doria
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
| | | | - Stephen I-Hong Hsu
- Departments of Medicine and Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, Florida, 32610, USA
| | - Rohit N Kulkarni
- Research Division, Joslin Diabetes Center, Harvard Medical School, One Joslin Place Boston, MA 02215, USA
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222
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Verhelst K, Verstrepen L, Carpentier I, Beyaert R. IκB kinase ε (IKKε): a therapeutic target in inflammation and cancer. Biochem Pharmacol 2013; 85:873-80. [PMID: 23333767 PMCID: PMC7111187 DOI: 10.1016/j.bcp.2013.01.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 01/04/2013] [Accepted: 01/11/2013] [Indexed: 01/10/2023]
Abstract
The innate immune system forms our first line of defense against invading pathogens and relies for a major part on the activation of two transcription factors, NF-κB and IRF3. Signaling pathways that activate these transcription factors are intertwined at the level of the canonical IκB kinases (IKKα, IKKβ) and non-canonical IKK-related kinases (IKKε, TBK1). Recently, significant progress has been made in understanding the function and mechanism of action of IKKε in immune signaling. In addition, IKKε impacts on cell proliferation and transformation, and is thereby also classified as an oncogene. Studies with IKKε knockout mice have illustrated a key role for IKKε in inflammatory and metabolic diseases. In this review we will highlight the mechanisms by which IKKε impacts on signaling pathways involved in disease development and discuss its potential as a novel therapeutic target.
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Affiliation(s)
- Kelly Verhelst
- Department for Molecular Biomedical Research, Unit of Molecular Signal Transduction in Inflammation, VIB, Zwijnaarde (Ghent), Belgium
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223
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Abstract
Metabolism and immunity are inextricably linked both to each other and to organism-wide function, allowing mammals to adapt to changes in their internal and external environments. In the modern context of obesogenic diets and lifestyles, however, these adaptive responses can have deleterious consequences. In this Review, we discuss the pleiotropic actions of inflammation and insulin resistance in metabolic homeostasis and disease. An appreciation of the adaptive context in which these responses arose is useful for understanding their pathogenic actions in disease.
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Affiliation(s)
- Justin I. Odegaard
- Cardiovascular Research Institute, University of California, San Francisco, 94158-9001, USA
| | - Ajay Chawla
- Cardiovascular Research Institute, University of California, San Francisco, 94158-9001, USA
- Departments of Physiology and Medicine, University of California, San Francisco, 94158-9001, USA
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224
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Abstract
Obesity is caused by chronic positive energy balance because of higher energy intake relative to energy expenditure. Thermogenesis, the capacity of an organism to produce heat, is an important component of energy expenditure. Thus targeting the molecular mechanisms controlling thermogenesis could be an effective strategy for the prevention or treatment of obesity. Thermogenesis is modulated by three major factors: environmental temperature, nutrient quantity and quality, and by systemic inflammation. Obesity is now recognized to be a state of chronic low-grade systemic inflammation, which has been proposed to play a major role in the pathogenesis of obesity and obesity-associated diseases. This review discussed the molecular pathways that are recruited during metabolic inflammation and that are also implicated in the control of thermogenesis and energy balance. It emerges that the complex signalling network recruited during metabolic inflammation exerts a balanced action on the modulation of thermogenesis and energy balance, with some pathways promoting weight gain whereas other pathways have opposite actions. It is thus concluded that immunomodulation of metabolic inflammation, rather than an anti-inflammatory intervention aiming at its suppression, may be a more promising strategy to increase thermogenesis for the treatment or prevention of obesity and its associated diseases.
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Affiliation(s)
- G Solinas
- Laboratory of Metabolic Stress Biology, Division of Physiology, Department of Medicine, University of Fribourg, Chemin du Musée 5, Fribourg, Switzerland.
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225
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Kim YJ, Sano T, Nabetani T, Asano Y, Hirabayashi Y. GPRC5B Activates Obesity-Associated Inflammatory Signaling in Adipocytes. Sci Signal 2012; 5:ra85. [DOI: 10.1126/scisignal.2003149] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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226
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Bhargava P, Li C, Stanya KJ, Jacobi D, Dai L, Liu S, Gangl MR, Harn DA, Lee CH. Immunomodulatory glycan LNFPIII alleviates hepatosteatosis and insulin resistance through direct and indirect control of metabolic pathways. Nat Med 2012; 18:1665-72. [PMID: 23104131 PMCID: PMC3493877 DOI: 10.1038/nm.2962] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 08/30/2012] [Indexed: 02/06/2023]
Abstract
Parasitic worms express host-like glycans to attenuate the immune response of human hosts. The therapeutic potential of this immunomodulatory mechanism in controlling metabolic dysfunction associated with chronic inflammation remains unexplored. We demonstrate here that administration of Lacto-N-fucopentaose III (LNFPIII), a LewisX containing immunomodulatory glycan found in human milk and on parasitic helminths, improves glucose tolerance and insulin sensitivity in diet-induced obese mice. This effect is mediated partly through increased Il-10 production by LNFPIII activated macrophages and dendritic cells, which reduces white adipose tissue inflammation and sensitizes the insulin response of adipocytes. Concurrently, LNFPIII treatment up-regulates nuclear receptor Fxr-α (or Nr1h4) to suppress lipogenesis in the liver, conferring protection against hepatosteatosis. At the signaling level, the extracellular signal-regulated kinase (Erk)-Ap1 pathway appears to mediate the effects of LNFPIII on both inflammatory and metabolic pathways. Our results suggest that LNFPIII may provide novel therapeutic approaches to treat metabolic diseases.
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Affiliation(s)
- Prerna Bhargava
- Department of Genetics and Complex Diseases, Division of Biological Sciences, Harvard School of Public Health, Boston, MA, USA
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227
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Jowett JBM, Okada Y, Leedman PJ, Curran JE, Johnson MP, Moses EK, Goring HHH, Mochizuki S, Blangero J, Stone L, Allen H, Mitchell C, Matthews VB. ADAM28 is elevated in humans with the metabolic syndrome and is a novel sheddase of human tumour necrosis factor-α. Immunol Cell Biol 2012; 90:966-73. [PMID: 23010875 DOI: 10.1038/icb.2012.44] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Metalloproteinases are implicated in cleaving numerous proinflammatory mediators from the cell surface. Interestingly, the elevated levels of tumour necrosis factor-α (TNF-α) have been associated with the metabolic syndrome. We aimed to ascertain whether the human metalloproteinase ADAM28 correlates with parameters of the metabolic syndrome and whether ADAM28 is a novel sheddase of human TNF-α. To identify novel metalloproteinases associated with the metabolic syndrome, we conducted microarray studies on peripheral blood mononuclear cells from a well characterised human cohort. Human ADAM28 and TNF-α were overexpressed and ADAM28 expression or activity was reduced with small-interfering RNA (siRNA) or pharmacological inhibition. TNF-α levels were measured in cell supernatant by enzyme-linked immunosorbent assay. We also conducted ADAM28 inhibition studies in human THP-1 macrophages. Human ADAM28 expression levels were positively correlated with parameters of the metabolic syndrome. When human ADAM28 and TNF-α were overexpressed in HEK293 cells, both proteins co-localised, co-immunoprecipitated and promoted TNF-α shedding. The shedding was significantly reduced when ADAM28 activity was inhibited or ADAM28 expression was downregulated. In human THP-1 macrophages, endogenous ADAM28 and TNF-α were co-expressed and TNF-α shedding was significantly reduced when ADAM28 was inhibited by pharmacological inhibition or siRNA knockdown. Our data suggest a novel mechanistic role for the metalloproteinase ADAM28 in inflammation, obesity and type 2 diabetes.
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Affiliation(s)
- Jeremy B M Jowett
- Genomics and Systems Biology, Baker IDI Heart & Diabetes Institute, Melbourne, Victoria, Australia
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228
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Tornatore L, Thotakura AK, Bennett J, Moretti M, Franzoso G. The nuclear factor kappa B signaling pathway: integrating metabolism with inflammation. Trends Cell Biol 2012; 22:557-66. [PMID: 22995730 DOI: 10.1016/j.tcb.2012.08.001] [Citation(s) in RCA: 328] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/01/2012] [Accepted: 08/09/2012] [Indexed: 12/15/2022]
Abstract
Nuclear factor kappa B (NF-κB) transcription factors are evolutionarily conserved, coordinating regulators of immune and inflammatory responses. They also play a pivotal role in oncogenesis and metabolic disorders. Several studies during the past two decades have highlighted the key role of the IKK/NF-κB pathway in the induction and maintenance of the state of inflammation that underlies metabolic diseases such as obesity and type 2 diabetes. Recent reports, however, reveal an even more intimate connection between NF-κB and metabolism. These studies demonstrate that NF-κB regulates energy homeostasis via direct engagement of the cellular networks governing glycolysis and respiration, with profound implications beyond metabolic diseases, including cancer, ageing and anticancer therapy. In this review, we discuss these emerging bioenergetic functions of NF-κB and their significance to oncogenesis.
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Affiliation(s)
- Laura Tornatore
- Section of Inflammation and Signal Transduction, Department of Medicine, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
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229
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Barham W, Sherrill T, Connelly L, Blackwell TS, Yull FE. Intraductal injection of LPS as a mouse model of mastitis: signaling visualized via an NF-κB reporter transgenic. J Vis Exp 2012:e4030. [PMID: 22971993 DOI: 10.3791/4030] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Animal models of human disease are necessary in order to rigorously study stages of disease progression and associated mechanisms, and ultimately, as pre-clinical models to test interventions. In these methods, we describe a technique in which lipopolysaccharide (LPS) is injected into the lactating mouse mammary gland via the nipple, effectively modeling mastitis, or inflammation, of the gland. This simulated infection results in increased nuclear factor kappa B (NF-κB) signaling, as visualized through bioluminescent imaging of an NF-κB luciferase reporter mouse. Our ultimate goal in developing these methods was to study the inflammation associated with mastitis in the lactating gland, which often includes redness, swelling, and immune cell infiltration. Therefore, we were keenly aware that incision or any type of wounding of the skin, the nipple, or the gland in order to introduce the LPS could not be utilized in our methods since the approach would likely confound the read-out of inflammation. We also desired a straight-forward method that did not require specially made hand-drawn pipettes or the use of micromanipulators to hold these specialized tools in place. Thus, we determined to use a commercially available insulin syringe and to inject the agent into the mammary duct of an intact nipple. This method was successful and allowed us to study the inflammation associated with LPS injection without any additional effects overlaid by the process of injection. In addition, this method also utilized an NF-κB luciferase reporter transgenic mouse and bioluminescent imaging technology to visually and quantitatively show increased NF-κB signaling within the LPS-injected gland. These methods are of interest to researchers of many disciplines who wish to model disease within the lactating mammary gland, as ultimately, the technique described here could be utilized for injection of a number of substances, and is not limited to only LPS.
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Affiliation(s)
- Whitney Barham
- Cancer Biology Department, Vanderbilt University Medical Center, USA
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230
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Rahman SM, Janssen RC, Choudhury M, Baquero KC, Aikens RM, de la Houssaye BA, Friedman JE. CCAAT/enhancer-binding protein β (C/EBPβ) expression regulates dietary-induced inflammation in macrophages and adipose tissue in mice. J Biol Chem 2012; 287:34349-60. [PMID: 22902781 DOI: 10.1074/jbc.m112.410613] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Strong evidence exists for a link between chronic low level inflammation and dietary-induced insulin resistance; however, little is known about the transcriptional networks involved. Here we show that high fat diet (HFD) or saturated fatty acid exposure directly activates CCAAT/enhancer-binding protein β (C/EBPβ) protein expression in liver, adipocytes, and macrophages. Global C/EBPβ deletion prevented HFD-induced inflammation and surprisingly increased mitochondrial gene expression in white adipose tissue along with brown adipose tissue markers PRDM16, CIDEa, and UCP1, consistent with a resistance to HFD-induced obesity. In isolated peritoneal macrophages from C/EBPβ(-/-) mice, the anti-inflammatory gene LXRα and its targets SCD1 and DGAT2 were strikingly up-regulated along with IL-10, while NLRP3, a gene important for activating the inflammasome, was suppressed in response to palmitate. Using RAW 264.7 macrophage cells or 3T3-L1 adipocytes, C/EBPβ knockdown prevented palmitate-induced inflammation and p65-NFκB DNA binding activity, while C/EBPβ overexpression induced NFκB binding, JNK activation, and pro-inflammatory cytokine gene expression directly. Finally, chimeric bone marrow mice transplanted with bone marrow lacking C/EBPβ(-/-) demonstrated reduced systemic and adipose tissue inflammatory markers, macrophage content, and maintained insulin sensitivity on HFD. Taken together, these results demonstrate that HFD or palmitate exposure triggers C/EBPβ expression that controls expression of distinct aspects of alternative macrophage activation. Reducing C/EBPβ in macrophages confers protection from HFD-induced systemic inflammation and insulin resistance, suggesting it may be an attractive therapeutic target for ameliorating obesity-induced inflammatory responses.
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Affiliation(s)
- Shaikh M Rahman
- Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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231
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Pythoud C, Rodrigo WWSI, Pasqual G, Rothenberger S, Martínez-Sobrido L, de la Torre JC, Kunz S. Arenavirus nucleoprotein targets interferon regulatory factor-activating kinase IKKε. J Virol 2012; 86:7728-38. [PMID: 22532683 PMCID: PMC3421673 DOI: 10.1128/jvi.00187-12] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 04/06/2012] [Indexed: 12/24/2022] Open
Abstract
Arenaviruses perturb innate antiviral defense by blocking induction of type I interferon (IFN) production. Accordingly, the arenavirus nucleoprotein (NP) was shown to block activation and nuclear translocation of interferon regulatory factor 3 (IRF3) in response to virus infection. Here, we sought to identify cellular factors involved in innate antiviral signaling targeted by arenavirus NP. Consistent with previous studies, infection with the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) prevented phosphorylation of IRF3 in response to infection with Sendai virus, a strong inducer of the retinoic acid-inducible gene I (RIG-I)/mitochondrial antiviral signaling (MAVS) pathway of innate antiviral signaling. Using a combination of coimmunoprecipitation and confocal microscopy, we found that LCMV NP associates with the IκB kinase (IKK)-related kinase IKKε but that, rather unexpectedly, LCMV NP did not bind to the closely related TANK-binding kinase 1 (TBK-1). The NP-IKKε interaction was highly conserved among arenaviruses from different clades. In LCMV-infected cells, IKKε colocalized with NP but not with MAVS located on the outer membrane of mitochondria. LCMV NP bound the kinase domain (KD) of IKKε (IKBKE) and blocked its autocatalytic activity and its ability to phosphorylate IRF3, without undergoing phosphorylation. Together, our data identify IKKε as a novel target of arenavirus NP. Engagement of NP seems to sequester IKKε in an inactive complex. Considering the important functions of IKKε in innate antiviral immunity and other cellular processes, the NP-IKKε interaction likely plays a crucial role in arenavirus-host interaction.
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Affiliation(s)
- Christelle Pythoud
- Institute of Microbiology University Hospital Center and University of Lausanne, Lausanne, Switzerland
| | | | - Giulia Pasqual
- Institute of Microbiology University Hospital Center and University of Lausanne, Lausanne, Switzerland
| | - Sylvia Rothenberger
- Institute of Microbiology University Hospital Center and University of Lausanne, Lausanne, Switzerland
| | - Luis Martínez-Sobrido
- Department of Microbiology and Immunology, University of Rochester, Rochester, New York, USA
| | - Juan Carlos de la Torre
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California, USA
| | - Stefan Kunz
- Institute of Microbiology University Hospital Center and University of Lausanne, Lausanne, Switzerland
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232
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Song D, Fang G, Mao SZ, Ye X, Liu G, Gong Y, Liu SF. Chronic intermittent hypoxia induces atherosclerosis by NF-κB-dependent mechanisms. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1650-9. [PMID: 22846605 DOI: 10.1016/j.bbadis.2012.07.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 07/16/2012] [Accepted: 07/23/2012] [Indexed: 02/06/2023]
Abstract
Chronic intermittent hypoxia (CIH) causes atherosclerosis in mice fed a high cholesterol diet (HCD). The mechanisms by which CIH promotes atherosclerosis are incompletely understood. This study defined the mechanistic role of NF-κB pathway in CIH+HCD induced atherosclerosis. Wild type (WT) and mice deficient in the p50 subunit of NF-κB (p50-KO) were fed normal chow diet (ND) or HCD, and exposed to sham or CIH. Atherosclerotic lesions on the en face aortic preparation and cross-sections of aortic root were examined. In WT mice, neither CIH nor HCD exposure alone caused, but CIH+HCD caused evident atherosclerotic lesions on both preparations after 20weeks of exposure. WT mice on ND and exposed to CIH for 35.6weeks did not develop atherosclerotic lesions. P50 gene deletion diminished CIH+HCD induced NF-κB activation and abolished CIH+HCD induced atherosclerosis. P50 gene deletion inhibited vascular wall inflammation, reduced hepatic TNF-α level, attenuated the elevation in serum cholesterol level and diminished macrophage foam cell formation induced by CIH+HCD exposure. These results demonstrate that inhibition of NF-κB activation abrogates the activation of three major atherogenic mechanisms associated with an abolition of CIH+HCD induced atherosclerosis. NF-κB may be a central common pathway through which CIH+HCD exposure activates multiple atherogenic mechanisms, leading to atherosclerosis.
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Affiliation(s)
- D Song
- Centers for Heart and Lung Research and Pulmonary, Critical Care and Sleep Medicine, the Feinstein Institute for Medical Research, Manhasset, NY, USA
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233
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Harvey AE, Lashinger LM, Otto G, Nunez NP, Hursting SD. Decreased systemic IGF-1 in response to calorie restriction modulates murine tumor cell growth, nuclear factor-κB activation, and inflammation-related gene expression. Mol Carcinog 2012; 52:997-1006. [PMID: 22778026 DOI: 10.1002/mc.21940] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/01/2012] [Accepted: 06/04/2012] [Indexed: 12/15/2022]
Abstract
Calorie restriction (CR) prevents obesity and has potent anticancer effects associated with altered hormones and cytokines. We tested the hypothesis that CR inhibits MC38 mouse colon tumor cell growth through modulation of hormone-stimulated nuclear factor (NF)-κB activation and protumorigenic gene expression. Female C57BL/6 mice were randomized (n = 30/group) to receive control diet or 30% CR diet. At 20 wk, 15 mice/group were killed for body composition analysis. At 21 wk, serum was obtained for hormone analysis. At 22 wk, mice were injected with MC38 cells; tumor growth was monitored for 24 d. Gene expression in excised tumors and MC38 cells was analyzed using real-time RT-PCR. In vitro MC38 NF-κB activation (by p65 ELISA and immunofluorescence) were measured in response to varying IGF-1 concentrations (1-400 ng/mL). Relative to controls, CR mice had decreased tumor volume, body weight, body fat, serum IGF-1, serum leptin, and serum insulin, and increased serum adiponectin (P < 0.05, each). Tumors from CR mice, versus controls, had downregulated inflammation- and/or cancer-related gene expression, including interleukin (IL)-6, IL-1β, tumor necrosis factor-α, cyclooxygenase-2, chemokine (C-C motif) ligand-2, S100A9, and F4/80, and upregulated 15-hydroxyprostaglandin dehydrogenase expression. In MC38 cells in vitro, IGF-1 increased NF-κB activation and NF-κB downstream gene expression (P < 0.05, each). We conclude that CR, in association with reduced systemic IGF-1, modulates MC38 tumor growth, NF-κB activation, and inflammation-related gene expression. Thus, IGF-1 and/or NF-κB inhibition may pharmacologically mimic the anticancer effects of CR to break the obesity-colon cancer link.
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Affiliation(s)
- Alison E Harvey
- Department of Nutritional Sciences, University of Texas at Austin, Austin, Texas
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234
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Interferon-beta-1b-induced short- and long-term signatures of treatment activity in multiple sclerosis. THE PHARMACOGENOMICS JOURNAL 2012; 13:443-51. [PMID: 22711062 PMCID: PMC3793239 DOI: 10.1038/tpj.2012.27] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 04/20/2012] [Accepted: 04/23/2012] [Indexed: 12/30/2022]
Abstract
Interferon beta (IFNβ) reduces disease burden in relapsing-remitting multiple sclerosis (MS) patients. In this study, IFNβ-1b-treated MS patient gene expression profiles and biological knowledgebases were integrated to study IFNβ's pleiotropic mechanisms of action. Genes involved in immune regulation, mitochondrial fatty acid metabolism and antioxidant activity were discovered. Plausible mediators of neuronal preservation included NRF2, downregulation of OLA1, an antioxidant suppressor, and the antioxidant gene ND6, implicated in optic neuropathy and MS-like lesions. Network analysis highlighted IKBKE, which likely has a role in both viral response and energy metabolism. A comparative analysis of therapy-naive MS- and IFNβ-associated gene expression suggests an IFNβ insufficiency in MS. We observed more gene expression changes in long-term treatment than during acute dosing. These distinct short- and long-term effects were driven by different transcription factors. Multi-gene biomarker signatures of IFNβ treatment effects were developed and subsequently confirmed in independent IFNβ-1b-treated MS studies, but not in glatiramer acetate-treated patients.
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235
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Anhê GF, Okamoto MM, Kinote A, Sollon C, Lellis-Santos C, Anhê FF, Lima GA, Hirabara SM, Velloso LA, Bordin S, Machado UF. Quercetin decreases inflammatory response and increases insulin action in skeletal muscle of ob/ob mice and in L6 myotubes. Eur J Pharmacol 2012; 689:285-93. [PMID: 22713545 DOI: 10.1016/j.ejphar.2012.06.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 06/03/2012] [Accepted: 06/09/2012] [Indexed: 12/13/2022]
Abstract
Quercetin is a potent anti-inflammatory flavonoid, but its capacity to modulate insulin sensitivity in obese insulin resistant conditions is unknown. This study investigated the effect of quercetin treatment upon insulin sensitivity of ob/ob mice and its potential molecular mechanisms. Obese ob/ob mice were treated with quercetin for 10 weeks, and L6 myotubes were treated with either palmitate or tumor necrosis factor-α (TNFα) plus quercetin. Cells and muscles were processed for analysis of glucose transporter 4 (GLUT4), TNFα and inducible nitric oxide synthase (iNOS) expression, and c-Jun N-terminal kinase (JNK) and inhibitor of nuclear factor-κB (NF-κB) kinase (IκK) phosphorylation. Myotubes were assayed for glucose uptake and NF-κB translocation. Chromatin immunoprecipitation assessed NF-κB binding to GLUT4 promoter. Quercetin treatment improved whole body insulin sensitivity by increasing GLUT4 expression and decreasing JNK phosphorylation, and TNFα and iNOS expression in skeletal muscle. Quercetin suppressed palmitate-induced upregulation of TNFα and iNOS and restored normal levels of GLUT4 in myotubes. In parallel, quercetin suppressed TNFα-induced reduction of glucose uptake in myotubes. Nuclear accumulation of NF-κB in myotubes and binding of NF-κB to GLUT4 promoter in muscles of ob/ob mice were also reduced by quercetin. We demonstrated that quercetin decreased the inflammatory status in skeletal muscle of obese mice and in L6 myotubes. This effect was followed by increased muscle GLUT4, with parallel improvement of insulin sensitivity. These results point out quercetin as a putative strategy to manage inflammatory-related insulin resistance.
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Affiliation(s)
- Gabriel F Anhê
- Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas, Alexander Fleming Street, #101, FCM10 13084-971 Campinas, SP, Brazil.
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236
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Insulin resistance in the defense against obesity. Cell Metab 2012; 15:798-804. [PMID: 22682220 DOI: 10.1016/j.cmet.2012.03.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Revised: 01/14/2012] [Accepted: 03/01/2012] [Indexed: 12/18/2022]
Abstract
In the face of the current obesity epidemic, the nature of the relationship between overnutrition and type 2 diabetes is of great importance. Obesity can be considered a state of excessive insulin action that elicits a series of cellular homeostatic responses, producing systemic insulin resistance. These responses occur in four steps: homologous desensitization to insulin action, leptin secretion, inflammation, and, finally, a counter-inflammatory phase that serves to conserve energy storage. The molecular mechanisms underlying these steps are discussed in the context of potential new therapeutic approaches.
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237
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Muoio DM, Neufer PD. Lipid-induced mitochondrial stress and insulin action in muscle. Cell Metab 2012; 15:595-605. [PMID: 22560212 PMCID: PMC3348508 DOI: 10.1016/j.cmet.2012.04.010] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Revised: 01/16/2012] [Accepted: 04/13/2012] [Indexed: 12/14/2022]
Abstract
The interplay between mitochondrial energetics, lipid balance, and muscle insulin sensitivity has remained a topic of intense interest and debate for decades. One popular view suggests that increased oxidative capacity benefits metabolic wellness, based on the premise that it is healthier to burn fat than glucose. Attempts to test this hypothesis using genetically modified mouse models have produced contradictory results and instead link muscle insulin resistance to excessive fat oxidation, acylcarnitine production, and increased mitochondrial H(2)O(2)-emitting potential. Here, we consider emerging evidence that insulin action in muscle is driven principally by mitochondrial load and redox signaling rather than oxidative capacity.
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Affiliation(s)
- Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center, Duke University, Durham, NC 27710, USA.
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238
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Watanabe Y, Nakamura T, Ishikawa S, Fujisaka S, Usui I, Tsuneyama K, Ichihara Y, Wada T, Hirata Y, Suganami T, Izaki H, Akira S, Miyake K, Kanayama HO, Shimabukuro M, Sata M, Sasaoka T, Ogawa Y, Tobe K, Takatsu K, Nagai Y. The radioprotective 105/MD-1 complex contributes to diet-induced obesity and adipose tissue inflammation. Diabetes 2012; 61:1199-209. [PMID: 22396206 PMCID: PMC3331758 DOI: 10.2337/db11-1182] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent accumulating evidence suggests that innate immunity is associated with obesity-induced chronic inflammation and metabolic disorders. Here, we show that a Toll-like receptor (TLR) protein, radioprotective 105 (RP105)/myeloid differentiation protein (MD)-1 complex, contributes to high-fat diet (HFD)-induced obesity, adipose tissue inflammation, and insulin resistance. An HFD dramatically increased RP105 mRNA and protein expression in stromal vascular fraction of epididymal white adipose tissue (eWAT) in wild-type (WT) mice. RP105 mRNA expression also was significantly increased in the visceral adipose tissue of obese human subjects relative to nonobese subjects. The RP105/MD-1 complex was expressed by most adipose tissue macrophages (ATMs). An HFD increased RP105/MD-1 expression on the M1 subset of ATMs that accumulate in eWAT. Macrophages also acquired this characteristic in coculture with 3T3-L1 adipocytes. RP105 knockout (KO) and MD-1 KO mice had less HFD-induced adipose tissue inflammation, hepatic steatosis, and insulin resistance compared with wild-type (WT) and TLR4 KO mice. Finally, the saturated fatty acids, palmitic and stearic acids, are endogenous ligands for TLR4, but they did not activate RP105/MD-1. Thus, the RP105/MD-1 complex is a major mediator of adipose tissue inflammation independent of TLR4 signaling and may represent a novel therapeutic target for obesity-associated metabolic disorders.
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Affiliation(s)
- Yasuharu Watanabe
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Tomoya Nakamura
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Sho Ishikawa
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Shiho Fujisaka
- Department of First Internal Medicine, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Isao Usui
- Department of First Internal Medicine, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Koichi Tsuneyama
- Department of Diagnostic Pathology, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Yoshinori Ichihara
- Department of Clinical Pharmacology, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Tsutomu Wada
- Department of Clinical Pharmacology, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Yoichiro Hirata
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Takayoshi Suganami
- Department of Molecular Medicine and Metabolism, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hirofumi Izaki
- Department of Urology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Shizuo Akira
- Laboratory of Host Defense, WPI Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Kensuke Miyake
- Division of Infectious Genetics, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Hiro-omi Kanayama
- Department of Urology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Michio Shimabukuro
- Department of Cardio-Diabetes Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Masataka Sata
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Toshiyasu Sasaoka
- Department of Clinical Pharmacology, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Medicine and Metabolism, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kazuyuki Tobe
- Department of First Internal Medicine, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
| | - Kiyoshi Takatsu
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
- Toyama Prefectural Institute for Pharmaceutical Research, Toyama, Japan
| | - Yoshinori Nagai
- Department of Immunobiology and Pharmacological Genetics, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan
- Corresponding authors: Yoshinori Nagai, , and Kiyoshi Takatsu,
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239
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Schiffmann S, Ferreiros N, Birod K, Eberle M, Schreiber Y, Pfeilschifter W, Ziemann U, Pierre S, Scholich K, Grösch S, Geisslinger G. Ceramide Synthase 6 Plays a Critical Role in the Development of Experimental Autoimmune Encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2012; 188:5723-33. [DOI: 10.4049/jimmunol.1103109] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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240
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Samuel VT, Shulman GI. Mechanisms for insulin resistance: common threads and missing links. Cell 2012; 148:852-71. [PMID: 22385956 DOI: 10.1016/j.cell.2012.02.017] [Citation(s) in RCA: 1469] [Impact Index Per Article: 122.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Indexed: 02/07/2023]
Abstract
Insulin resistance is a complex metabolic disorder that defies explanation by a single etiological pathway. Accumulation of ectopic lipid metabolites, activation of the unfolded protein response (UPR) pathway, and innate immune pathways have all been implicated in the pathogenesis of insulin resistance. However, these pathways are also closely linked to changes in fatty acid uptake, lipogenesis, and energy expenditure that can impact ectopic lipid deposition. Ultimately, these cellular changes may converge to promote the accumulation of specific lipid metabolites (diacylglycerols and/or ceramides) in liver and skeletal muscle, a common final pathway leading to impaired insulin signaling and insulin resistance.
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Affiliation(s)
- Varman T Samuel
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510, USA.
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241
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Targeted deletion of thioesterase superfamily member 1 promotes energy expenditure and protects against obesity and insulin resistance. Proc Natl Acad Sci U S A 2012; 109:5417-22. [PMID: 22427358 DOI: 10.1073/pnas.1116011109] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mammalian acyl-CoA thioesterases (Acots) catalyze the hydrolysis of fatty acyl-CoAs to form free fatty acids plus CoA, but their metabolic functions remain undefined. Thioesterase superfamily member 1 (Them1; synonyms Acot11, StarD14, and brown fat inducible thioesterase) is a long-chain fatty acyl-CoA thioesterase that is highly expressed in brown adipose tissue and is regulated by both ambient temperature and food consumption. Here we show that Them1(-/-) mice were resistant to diet-induced obesity despite greater food consumption. Them1(-/-) mice exhibited increased O(2) consumption and heat production, which were accompanied by increased rates of fatty acid oxidation in brown adipose tissue and up-regulation of genes that promote energy expenditure. Them1(-/-) mice were also protected against diet-induced inflammation in white adipose tissue, as well as hepatic steatosis, and demonstrated improved glucose homeostasis. The absence of Them1 expression in vivo and in cell culture led to markedly attenuated diet- or chemically induced endoplasmic reticulum stress responses, providing a mechanism by which Them1 deficiency protects against insulin resistance and lipid deposition. Taken together, these data suggest that Them1 functions to decrease energy consumption and conserve calories. In the setting of nutritional excess, the overproduction of free fatty acids by Them1 provokes insulin resistance that is associated with inflammation and endoplasmic reticulum stress.
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242
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Sun B, Karin M. Obesity, inflammation, and liver cancer. J Hepatol 2012; 56:704-13. [PMID: 22120206 PMCID: PMC3889660 DOI: 10.1016/j.jhep.2011.09.020] [Citation(s) in RCA: 370] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 08/22/2011] [Accepted: 09/17/2011] [Indexed: 02/07/2023]
Abstract
Obesity has become a universal and major public health problem with increasing prevalence in both adults and children in the 21st century, even in developing countries. Extensive epidemiological studies reveal a strong link between obesity and development and progression of various types of cancers. The connection between obesity and liver cancer is particularly strong and obesity often results in liver diseases such as non-alcoholic fatty liver disease (NAFLD) and the more severe non-alcoholic steatohepatitis (NASH). NASH is characterized by fatty liver inflammation and is believed to cause fibrosis and cirrhosis. The latter is a known liver cancer risk factor. In fact due to its much higher prevalence obesity may be a more substantial contributor to overall hepatocellular carcinoma burden than infection with hepatitis viruses. Here we review and discuss recent advances in elucidation of cellular and molecular alterations and signaling pathways associated with obesity and liver inflammation and their contribution to hepatocarcinogenesis.
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Affiliation(s)
- Beicheng Sun
- Liver Transplantation Center, First Affiliated Hospital and Cancer Center, Nanjing Medical University, Nanjing, Jiangsu Province, PR China.
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology and Pathology, Cancer Center, UCSD School of Medicine, La Jolla, California 92093-0723, USA
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243
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Boesch-Saadatmandi C, Wagner AE, Wolffram S, Rimbach G. Effect of quercetin on inflammatory gene expression in mice liver in vivo - role of redox factor 1, miRNA-122 and miRNA-125b. Pharmacol Res 2012; 65:523-30. [PMID: 22402395 DOI: 10.1016/j.phrs.2012.02.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/09/2012] [Accepted: 02/21/2012] [Indexed: 12/13/2022]
Abstract
The anti-inflammatory properties of the flavonol quercetin have been intensively investigated using in vitro cell systems and are to a great extent reflected by changes in the expression of inflammatory markers. However, information relating to the degree at which quercetin affects inflammatory gene expression in vivo is limited. Recently, micro RNAs (miRNAs) have been identified as powerful post-transcriptional gene regulators. The effect of quercetin on miRNA regulation in vivo is largely unknown. Laboratory mice were fed for six weeks with control or quercetin enriched high fat diets and biomarkers of inflammation as well as hepatic levels of miRNAs previously involved in inflammation (miR-125b) and lipid metabolism (miR-122) were determined. We found lower mRNA steady state levels of the inflammatory genes interleukin 6, C-reactive protein, monocyte chemoattractant protein 1, and acyloxyacyl hydrolase in quercetin fed mice. In addition we found evidence for an involvement of redox factor 1, a modulator of nuclear factor κB signalling, on the attenuation of inflammatory gene expression mediated by dietary quercetin. Furthermore, the results demonstrate that hepatic miR-122 and miR-125b concentrations were increased by dietary quercetin supplementation and may therefore contribute to the gene-regulatory activity of quercetin in vivo.
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Affiliation(s)
- Christine Boesch-Saadatmandi
- Institute of Human Nutrition and Food Science, Christian-Albrechts-University Kiel, Hermann-Rodewald-Strasse 6, 24118 Kiel, Germany
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244
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Comb WC, Hutti JE, Cogswell P, Cantley LC, Baldwin AS. p85α SH2 domain phosphorylation by IKK promotes feedback inhibition of PI3K and Akt in response to cellular starvation. Mol Cell 2012; 45:719-30. [PMID: 22342344 DOI: 10.1016/j.molcel.2012.01.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 11/03/2011] [Accepted: 01/05/2012] [Indexed: 12/31/2022]
Abstract
The IκB kinase (IKK) pathway is an essential mediator of inflammatory, oncogenic, and cell stress pathways. Recently IKK was shown to be essential for autophagy induction in mammalian cells independent of its ability to regulate NF-κB, but the mechanism by which this occurs is unclear. Here we demonstrate that the p85 regulatory subunit of PI3K is an IKK substrate, phosphorylated at S690 in vitro and in vivo in response to cellular starvation. Cells expressing p85 S690A or inhibited for IKK activity exhibit increased Akt activity following cell starvation, demonstrating that p85 phosphorylation is required for starvation-induced PI3K feedback inhibition. S690 is in a conserved region of the p85 cSH2 domain, and IKK-mediated phosphorylation of this site results in decreased affinity for tyrosine-phosphorylated proteins and decreased PI3K membrane localization. Finally, leucine deprivation is shown to be necessary and sufficient for starvation-induced, IKK-mediated p85 phosphorylation and PI3K feedback inhibition.
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Affiliation(s)
- William C Comb
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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245
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Abstract
Macrophages are key innate immune effector cells best known for their role as professional phagocytes, which also include neutrophils and dendritic cells. Recent evidence indicates that macrophages are also key players in metabolic homoeostasis. Macrophages can be found in many tissues, where they respond to metabolic cues and produce pro- and/or anti-inflammatory mediators to modulate metabolite programmes. Certain metabolites, such as fatty acids, ceramides and cholesterol crystals, elicit inflammatory responses through pathogen-sensing signalling pathways, implicating a maladaptation of macrophages and the innate immune system to elevated metabolic stress associated with overnutrition in modern societies. The outcome of this maladaptation is a feedforward inflammatory response leading to a state of unresolved inflammation and a collection of metabolic pathologies, including insulin resistance, fatty liver, atherosclerosis and dyslipidaemia. The present review summarizes what is known about the contributions of macrophages to metabolic diseases and the signalling pathways that are involved in metabolic stress-induced macrophage activation. Understanding the role of macrophages in these processes will help us to develop therapies against detrimental effects of the metabolic syndrome.
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246
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Miyokawa-Gorin K, Takahashi K, Handa K, Kitahara A, Sumitani Y, Katsuta H, Tanaka T, Nishida S, Yoshimoto K, Ohno H, Ishida H. Induction of mitochondrial uncoupling enhances VEGF₁₂₀ but reduces MCP-1 release in mature 3T3-L1 adipocytes: possible regulatory mechanism through endogenous ER stress and AMPK-related pathways. Biochem Biophys Res Commun 2012; 419:200-5. [PMID: 22330806 DOI: 10.1016/j.bbrc.2012.01.145] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 01/30/2012] [Indexed: 12/30/2022]
Abstract
Although white adipocytes contain a larger number of mitochondria per cytoplasmic volume, adipocyte mitochondrial uncoupling to reduce the efficiency of ATP production on cellular function including secretory regulation of bioactive molecules such as VEGF and MCP-1 remains to be elucidated. Here we induce mitochondrial uncoupling under hypoxia-independent conditions in mature 3T3-L1 adipocytes using a metabolic uncoupler, dinitrophenol (DNP). MCP-1 release was significantly decreased by 26% (p<0.01) in 24h DNP (30 μmol/L)-treated adipocytes compared to control cells. In contrast, secreted VEGF(120) lacking a heparin-binding domain was markedly increased 2.0-fold (p<0.01). CHOP content in these cells also were augmented (p<0.01), but no significant increase of endogenous oxidative stress was observed. Treatment with thapsigargin, which can induce exogenous endoplasmic reticulum (ER) stress, clearly attenuated MCP-1 release (p<0.01), but exhibited no effects on VEGF(120) secretion. On the other hand, exogenous H(2)O(2) amplified both MCP-1 and VEGF(120) secretion (p<0.05). In addition, under chronic activation of AMPK by AICAR, MCP-1 release was significantly diminished (p<0.05) but VEGF(120) secretion was increased (p<0.01). JNK phosphorylation in mature adipocytes was decreased by treatment with either DNP or AICAR (p<0.01). Enhanced VEGF(120) secretion with either DNP or AICAR was markedly suppressed by PI3K inhibitor LY294002 (p<0.01). Thus, induced mitochondrial uncoupling in adipocytes can reduce MCP-1 release through induction of endogenous ER stress and by reduced JNK activities via chronic activation of AMPK. Under this condition, VEGF(120) secretion was increased through PI3K-dependent pathways, which were chronically activated by AMPK, and not through ER stress. Because the decrease of MCP-1 secretion under mitochondrial uncoupling might attenuate chronic low-grade inflammation by suppressing macrophages recruitment to adipose tissue, clarification of the mechanism might reveal novel therapeutic targets for ameliorating obesity-associated insulin resistance in metabolic syndrome and type 2 diabetes.
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Affiliation(s)
- Kaoru Miyokawa-Gorin
- Third Department of Internal Medicine, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan
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247
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Yokoyama S, Hosoi T, Ozawa K. Stearoyl-CoA Desaturase 1 (SCD1) is a key factor mediating diabetes in MyD88-deficient mice. Gene 2012; 497:340-3. [PMID: 22326531 DOI: 10.1016/j.gene.2012.01.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/18/2012] [Indexed: 11/18/2022]
Abstract
Saturated fatty acids, acting as ligands for toll-like receptor 4 (TLR4), induce inflammation and mediate the development of insulin resistance. Myeloid differentiation factor 88 (MyD88) is an adaptor protein for TLR4. Previously, we found MyD88-deficient mice fed a high-fat diet (HFD) exhibited a severe diabetic phenotype. Stearoyl-CoA Desaturase 1 (SCD1) is the rate-limiting enzyme in the biosynthesis of monounsaturated fatty acids and known as a risk factor of diabetes. In the present study, we found SCD1 was dramatically increased in HFD-fed MyD88-deficient mice liver. This finding showed the novel linkage between MyD88 and SCD1 in the development of diabetes mellitus.
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Affiliation(s)
- Shota Yokoyama
- Department of Pharmacotherapy, Hiroshima University, Hiroshima, Japan.
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248
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Hildebrandt MAT, Tan W, Tamboli P, Huang M, Ye Y, Lin J, Lee JS, Wood CG, Wu X. Kinome expression profiling identifies IKBKE as a predictor of overall survival in clear cell renal cell carcinoma patients. Carcinogenesis 2012; 33:799-803. [PMID: 22266464 DOI: 10.1093/carcin/bgs018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
There are 516 known kinases in the human genome. Because of their important role maintaining proper cellular function, they are often misregulated during tumorigenesis and associated with clinical outcomes in cancer patients, including clear cell renal cell carcinoma (ccRCC). However, less is known about the global expression status of these genes in renal cell carcinoma and their association with clinical outcomes. We performed a systematic analysis of gene expression for 503 kinases in 93 tumor samples and adjacent normal tissues. Expression patterns for 41 kinases were able to clearly differentiate tumor and normal samples. Expression of I-kappa-B kinase epsilon (IKBKE) was associated with a 5.3-fold increased risk of dying [95% confidence interval (CI): 1.93-14.59, P-value: 0.0012]. Individuals with high IKBKE expression were at a significantly increased risk of death (hazard ratio: 3.34, 95% CI: 1.07-10.40, P-value: 0.038) resulting in a significantly reduced overall survival time compared with those with low IKBKE tumor expression (P-value: 0.049). These results for IKBKE were validated in a replication population consisting of 237 ccRCC patients (P-value: 0.0021). Furthermore, IKBKE was observed to be higher expressed in tumors compared with adjacent normal tissues (P-value < 10(-7)). IKBKE is a member of the nuclear factor-kappaB (NF-κB) signaling pathway and interestingly, gene expression patterns for other members of the NF-κB pathway were not associated with survival, suggesting that IKBKE gene expression may be an independent marker of variation in overall survival. Overall, these results support a novel role for IKBKE expression in modulating overall survival in ccRCC patients.
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Affiliation(s)
- Michelle A T Hildebrandt
- Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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249
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Wang X, Li L, Huang Y, Wei Q. Calcineurin subunit B upregulates β-interferon production by phosphorylation of interferon regulatory factor 3 via Toll-like receptor 4. Cancer Sci 2012; 103:515-21. [PMID: 22118374 DOI: 10.1111/j.1349-7006.2011.02160.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Toll-like receptors (TLRs) function as pattern-reorganization receptors in mammals and play an essential role in innate immunity. After recognizing certain ligands, TLRs activate a cascade of signal pathways to establish a guard environment. For the first time, we report that in vitro treatment with recombinant calcineurin subunit B (CNB) upregulated several TLR-related genes. Calcineurin subunit B interacted with the ectodomain of TLR4 in vitro. On further investigation, phosphorylation of interferon regulatory factor 3 and degradation of IκB-α were observed by CNB stimulation. In addition to pro-inflammatory cytokines, transcription and production of β-interferon were also enhanced after CNB stimulation. Thus, CNB could be further explored as a cancer and virus immunotherapy drug.
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Affiliation(s)
- Xinyu Wang
- Department of Biochemistry and Molecular Biology, Beijing Normal University, Beijing Key Laboratory, Beijing, China
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250
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Wang Z, Xue L, Guo C, Han B, Pan C, Zhao S, Song H, Ma Q. Stevioside ameliorates high-fat diet-induced insulin resistance and adipose tissue inflammation by downregulating the NF-κB pathway. Biochem Biophys Res Commun 2012; 417:1280-5. [PMID: 22240021 DOI: 10.1016/j.bbrc.2011.12.130] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 12/26/2011] [Indexed: 01/04/2023]
Abstract
Accumulating evidence suggests that adipose tissue is the main source of pro-inflammatory molecules that predispose individuals to insulin resistance. Stevioside (SVS) is a widely used sweetener with multiple beneficial effects for diabetic patients. In this study, we investigated the effect of SVS on insulin resistance and the pro-inflammatory state of adipose tissue in mice fed with a high-fat diet (HFD). Oral administration of SVS for 1month had no effect on body weight, but it significantly improved fasting glucose, basal insulin levels, glucose tolerance and whole body insulin sensitivity. Interestingly, these changes were accompanied with decreased expression levels of several inflammatory cytokines in adipose tissue, including TNF-α, IL6, IL10, IL1β, KC, MIP-1α, CD11b and CD14. Moreover, macrophage infiltration in adipose tissue was remarkably reduced by SVS. Finally, SVS significantly suppressed the nuclear factor-kappa b (NF-κB) signaling pathway in adipose tissue. Collectively, these results suggested that SVS may ameliorate insulin resistance in HFD-fed mice by attenuating adipose tissue inflammation and inhibiting the NF-κB pathway.
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Affiliation(s)
- Zhiquan Wang
- State Key Laboratory of Medical Genomics, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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