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El-Dakroury WA, Zewail MB, Amin MM. Design, optimization, and in-vivo performance of glipizide-loaded O-carboxymethyl chitosan nanoparticles in insulin resistant/type 2 diabetic rat model. J Drug Deliv Sci Technol 2022. [DOI: 10.1016/j.jddst.2022.104040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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2
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Navel orange peel hydroethanolic extract, naringin and naringenin have anti-diabetic potentials in type 2 diabetic rats. Biomed Pharmacother 2017; 94:197-205. [PMID: 28759757 DOI: 10.1016/j.biopha.2017.07.094] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 07/11/2017] [Accepted: 07/19/2017] [Indexed: 01/12/2023] Open
Abstract
The therapy of Type 2 Diabetes Mellitus (T2DM) stays a challenging issue. During the last decade, there has been an interest in the expansion of anti-diabetic drugs especially those of natural sources. Thus, the aim of this study was to assess the anti-hyperglycemic and the anti-hyperlipidemic effects as well as the anti-oxidant activities of navel orange hydroethanolic extract and its constituting flavonoids naringin and naringenin on nicotineamide (NA)/streptozotocin (STZ)-induced type 2 diabetic rats. To induce T2DM, 16h-fasted rats were intraperitoneally injected with STZ at dose of 50mg/kg body weight (b. w.), 15min after the intraperitoneal administration of NA (120mg/kg b. w.). The NA/STZ-induced type 2 diabetic rats were orally treated with navel orange peel hydroethanolic extract, naringin and narengenin at dose level of 100mg/kg b. w./day for 4 weeks. The treatments with navel orange peel hydroethanolic extract, naringin and narengenin potentially alleviated the lowered serum insulin and C-peptide levels, the depleted liver glycogen content, the elevated liver glucose-6-phosphatase and glycogen phosphorylase activities, the deteriorated serum lipid profile, and the suppressed liver antioxidant defense system of NA/STZ-induced type 2 diabetic rats. The treatments also enhanced the mRNA expression of insulin receptor β-subunit, GLUT4 and adiponectin in adipose tissue of STZ/NA-induced type 2 diabetic rats. In conclusion, the navel orange peel hydroethanolic extract, naringin and naringenin have potent anti-diabetic effects in NA/STZ-induced type 2 diabetic rats via their insulinotropic effects and insulin improving action which in turn may be mediated through enhancing insulin receptor, GLUT4 and adiponectin expression in adipose tissue.
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Huang X, Yang Z. Resistin's, obesity and insulin resistance: the continuing disconnect between rodents and humans. J Endocrinol Invest 2016; 39:607-15. [PMID: 26662574 DOI: 10.1007/s40618-015-0408-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/24/2015] [Indexed: 02/07/2023]
Abstract
PURPOSE This review aimed to discuss the conflicting findings from resistin research in rodents and humans as well as recent advances in our understanding of resistin's role in obesity and insulin resistance. METHODS A comprehensive review and synthesis of resistin's role in obesity and insulin resistance as well as conflicting findings from resistin research in rodents and humans. RESULTS In rodents, resistin is increased in high-fat/high-carbohydrate-fed, obese states characterized by impaired glucose uptake and insulin sensitivity. Resistin plays a causative role in the development of insulin resistance in rodents via 5' AMP-activated protein kinase (AMPK)-dependent and AMPK-independent suppressor of cytokine signaling-3 (SOCS-3) signaling. In contrast to rodents, human resistin is primarily secreted by peripheral-blood mononuclear cells (PBMCs) as opposed to white adipocytes. Circulating resistin levels have been positively associated with central/visceral obesity (but not BMI) as well as insulin resistance, while other studies show no such association. Human resistin has a role in pro-inflammatory processes that have been conclusively associated with obesity and insulin resistance. PBMCs, as well as vascular cells, have been identified as the primary targets of resistin's pro-inflammatory activity via nuclear factor-κB (NF-κB, p50/p65) and other signaling pathways. CONCLUSION Mounting evidence reveals a continuing disconnect between resistin's role in rodents and humans due to significant differences between these two species with respect to resistin's gene and protein structure, differential gene regulation, tissue-specific distribution, and insulin resistance induction as well as a paucity of evidence regarding the resistin receptor and downstream signaling mechanisms of action.
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Affiliation(s)
- X Huang
- Department of Radiology, College of Basic Medicine, Chongqing Medical University, Chongqing, China
- Department of Internal Medicine, Hechuan Hospital of First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Z Yang
- Department of Internal Medicine, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
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Sitagliptin decreases ventricular arrhythmias by attenuated glucose-dependent insulinotropic polypeptide (GIP)-dependent resistin signalling in infarcted rats. Biosci Rep 2016; 36:BSR20150139. [PMID: 26811539 PMCID: PMC4793300 DOI: 10.1042/bsr20150139] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 01/19/2016] [Indexed: 11/17/2022] Open
Abstract
Myocardial infarction (MI) was associated with insulin resistance, in which resistin acts as a critical mediator. We aimed to determine whether sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, can attenuate arrhythmias by regulating resistin-dependent nerve growth factor (NGF) expression in postinfarcted rats. Normoglycaemic male Wistar rats after ligating coronary artery were randomized to either vehicle or sitagliptin for 4 weeks starting 24 h after operation. Post-infarction was associated with increased myocardial noradrenaline [norepinephrine (NE)] levels and sympathetic hyperinnervation. Compared with vehicle, sympathetic innervation was blunted after administering sitagliptin, as assessed by immunofluorescent analysis of tyrosine hydroxylase, growth-associated factor 43 and neurofilament and western blotting and real-time quantitative RT-PCR of NGF. Arrhythmic scores in the sitagliptin-treated infarcted rats were significantly lower than those in vehicle. Furthermore, sitagliptin was associated with reduced resistin expression and increased Akt activity. Ex vivo studies showed that glucose-dependent insulinotropic polypeptide (GIP) infusion, but not glucagon-like peptide-1 (GLP-1), produced similar reduction in resistin levels to sitagliptin in postinfarcted rats. Furthermore, the attenuated effects of sitagliptin on NGF levels can be reversed by wortmannin (a phosphatidylinositol 3-kinase antagonist) and exogenous resistin infusion. Sitagliptin protects ventricular arrhythmias by attenuating sympathetic innervation in the non-diabetic infarcted rats. Sitagliptin attenuated resistin expression via the GIP-dependent pathway, which inhibited sympathetic innervation through a signalling pathway involving phosphatidylinositol 3-kinase (PI3K) and Akt protein.
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Rak-Mardyła A, Drwal E. In vitro interaction between resistin and peroxisome proliferator-activated receptor γ in porcine ovarian follicles. Reprod Fertil Dev 2016; 28:357-68. [DOI: 10.1071/rd14053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 06/13/2014] [Indexed: 11/23/2022] Open
Abstract
In the present study, using real-time polymerase chain reaction and immunoblotting methods, we quantified the expression of peroxisome proliferator-activated receptor (PPAR) γ, PPARα and PPARβ in different sized ovarian follicles (small (SF), medium (MF) and large (LF) follicles) in prepubertal and adult pigs. In prepubertal pigs, PPARγ and PPARα expression was highest in LF; however, PPARβ expression did not differ among SF, MF and LF. In mature pigs, only protein expression of PPARγ and PPARα increased during ovarian follicle development. Following identification of very high levels of PPARγ expression in LF in prepubertal and adult pigs, using in vitro culture of ovarian follicles, we determined the effect of resistin at 0.1, 1 and 10 ng mL–1 on PPARγ mRNA and protein expression and the effect of rosiglitazone at 25 and 50 µM (a PPARγ agonist) on resistin mRNA and protein expression. Resistin increased PPARγ expression in ovarian follicles in both prepubertal and adult pigs, whereas rosiglitazone had an inhibitory effect on resistin expression. The role of PPARγ in regulating the effects of resistin on ovarian steroidogenesis was investigated using GW9662 (a PPARγ antagonist at dose of 1 μM). In these studies, GW9662 reversed the effect of resistin on steroid hormone secretion. The data suggest that there is local cooperation between resistin and PPARγ expression in the porcine ovary. Resistin significantly increased the expression of PPARγ, whereas PPARγ decreased resistin expression; thus, PPARγ is a new key regulator of resistin expression and function.
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Zhang H, Sturchler E, Zhu J, Nieto A, Cistrone PA, Xie J, He L, Yea K, Jones T, Turn R, Di Stefano PS, Griffin PR, Dawson PE, McDonald PH, Lerner RA. Autocrine selection of a GLP-1R G-protein biased agonist with potent antidiabetic effects. Nat Commun 2015; 6:8918. [PMID: 26621478 PMCID: PMC4686834 DOI: 10.1038/ncomms9918] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/16/2015] [Indexed: 02/08/2023] Open
Abstract
Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists have emerged as treatment options for type 2 diabetes mellitus (T2DM). GLP-1R signals through G-protein-dependent, and G-protein-independent pathways by engaging the scaffold protein β-arrestin; preferential signalling of ligands through one or the other of these branches is known as ‘ligand bias'. Here we report the discovery of the potent and selective GLP-1R G-protein-biased agonist, P5. We identified P5 in a high-throughput autocrine-based screening of large combinatorial peptide libraries, and show that P5 promotes G-protein signalling comparable to GLP-1 and Exendin-4, but exhibited a significantly reduced β-arrestin response. Preclinical studies using different mouse models of T2DM demonstrate that P5 is a weak insulin secretagogue. Nevertheless, chronic treatment of diabetic mice with P5 increased adipogenesis, reduced adipose tissue inflammation as well as hepatic steatosis and was more effective at correcting hyperglycaemia and lowering haemoglobin A1c levels than Exendin-4, suggesting that GLP-1R G-protein-biased agonists may provide a novel therapeutic approach to T2DM. GLP-1 is a gut hormone with glucose-lowering activity. Here the authors report the peptide, P5, a variant of the GLP-1 receptor agonist exendin-4, with 'biased' signalling activity, and show that P5 improves glucose homeostasis in diabetic mice by increasing adipose tissue hyperplasia.
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Affiliation(s)
- Hongkai Zhang
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Emmanuel Sturchler
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Jiang Zhu
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Ainhoa Nieto
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Philip A Cistrone
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Jia Xie
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - LinLing He
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Kyungmoo Yea
- Shanghai Institute for Advance Immunological Studies, Shanghai Tech University, Shanghai 200031, China
| | - Teresa Jones
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Rachel Turn
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | | | - Patrick R Griffin
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Philip E Dawson
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Patricia H McDonald
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, Florida 33458, USA
| | - Richard A Lerner
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Macaluso FS, Maida M, Petta S. Genetic background in nonalcoholic fatty liver disease: A comprehensive review. World J Gastroenterol 2015; 21:11088-11111. [PMID: 26494964 PMCID: PMC4607907 DOI: 10.3748/wjg.v21.i39.11088] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/11/2015] [Accepted: 09/02/2015] [Indexed: 02/06/2023] Open
Abstract
In the Western world, nonalcoholic fatty liver disease (NAFLD) is considered as one of the most significant liver diseases of the twenty-first century. Its development is certainly driven by environmental factors, but it is also regulated by genetic background. The role of heritability has been widely demonstrated by several epidemiological, familial, and twin studies and case series, and likely reflects the wide inter-individual and inter-ethnic genetic variability in systemic metabolism and wound healing response processes. Consistent with this idea, genome-wide association studies have clearly identified Patatin-like phosholipase domain-containing 3 gene variant I148M as a major player in the development and progression of NAFLD. More recently, the transmembrane 6 superfamily member 2 E167K variant emerged as a relevant contributor in both NAFLD pathogenesis and cardiovascular outcomes. Furthermore, numerous case-control studies have been performed to elucidate the potential role of candidate genes in the pathogenesis and progression of fatty liver, although findings are sometimes contradictory. Accordingly, we performed a comprehensive literature search and review on the role of genetics in NAFLD. We emphasize the strengths and weaknesses of the available literature and outline the putative role of each genetic variant in influencing susceptibility and/or progression of the disease.
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Brestoff JR, Artis D. Immune regulation of metabolic homeostasis in health and disease. Cell 2015; 161:146-160. [PMID: 25815992 DOI: 10.1016/j.cell.2015.02.022] [Citation(s) in RCA: 336] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 02/07/2023]
Abstract
Obesity is an increasingly prevalent disease worldwide. While genetic and environmental factors are known to regulate the development of obesity and associated metabolic diseases, emerging studies indicate that innate and adaptive immune cell responses in adipose tissue have critical roles in the regulation of metabolic homeostasis. In the lean state, type 2 cytokine-associated immune cell responses predominate in white adipose tissue and protect against weight gain and insulin resistance through direct effects on adipocytes and elicitation of beige adipose. In obesity, these metabolically beneficial immune pathways become dysregulated, and adipocytes and other factors initiate metabolically deleterious type 1 inflammation that impairs glucose metabolism. This review discusses our current understanding of the functions of different types of adipose tissue and how immune cells regulate adipocyte function and metabolic homeostasis in the context of health and disease and highlights. We also highlight the potential of targeting immuno-metabolic pathways as a therapeutic strategy to treat obesity and associated diseases.
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Affiliation(s)
- Jonathan R Brestoff
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Joan and Sanford I. Weill Department of Medicine, Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, 10021, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - David Artis
- Jill Roberts Institute for Research in Inflammatory Bowel Disease, Joan and Sanford I. Weill Department of Medicine, Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, 10021, USA.
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Mahmoud AM, Ahmed OM, Ashour MB, Abdel-Moneim A. In vivo and in vitro antidiabetic effects of citrus flavonoids; a study on the mechanism of action. Int J Diabetes Dev Ctries 2015. [DOI: 10.1007/s13410-014-0268-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Amin MM, Asaad GF, Abdel Salam RM, El-Abhar HS, Arbid MS. Novel CoQ10 antidiabetic mechanisms underlie its positive effect: modulation of insulin and adiponectine receptors, Tyrosine kinase, PI3K, glucose transporters, sRAGE and visfatin in insulin resistant/diabetic rats. PLoS One 2014; 9:e89169. [PMID: 24586567 PMCID: PMC3930675 DOI: 10.1371/journal.pone.0089169] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
As a nutritional supplement, coenzyme Q10 (CoQ10) was tested previously in several models of diabetes and/or insulin resistance (IR); however, its exact mechanisms have not been profoundly explicated. Hence, the objective of this work is to verify some of the possible mechanisms that underlie its therapeutic efficacy. Moreover, the study aimed to assess the potential modulatory effect of CoQ10 on the antidiabetic action of glimebiride. An insulin resistance/type 2 diabetic model was adopted, in which rats were fed high fat/high fructose diet (HFFD) for 6 weeks followed by a single sub-diabetogenic dose of streptozotocin (35 mg/kg, i.p.). At the end of the 7th week animals were treated with CoQ10 (20 mg/kg, p.o) and/or glimebiride (0.5 mg/kg, p.o) for 2 weeks. CoQ10 alone opposed the HFFD effect and increased the hepatic/muscular content/activity of tyrosine kinase (TK), phosphatidylinositol kinase (PI3K), and adiponectin receptors. Conversely, it decreased the content/activity of insulin receptor isoforms, myeloperoxidase and glucose transporters (GLUT4; 2). Besides, it lowered significantly the serum levels of glucose, insulin, fructosamine and HOMA index, improved the serum lipid panel and elevated the levels of glutathione, sRAGE and adiponectin. On the other hand, CoQ10 lowered the serum levels of malondialdehyde, visfatin, ALT and AST. Surprisingly, CoQ10 effect surpassed that of glimepiride in almost all the assessed parameters, except for glucose, fructosamine, TK, PI3K, and GLUT4. Combining CoQ10 with glimepiride enhanced the effect of the latter on the aforementioned parameters. Conclusion: These results provided a new insight into the possible mechanisms by which CoQ10 improves insulin sensitivity and adjusts type 2 diabetic disorder. These mechanisms involve modulation of insulin and adiponectin receptors, as well as TK, PI3K, glucose transporters, besides improving lipid profile, redox system, sRAGE, and adipocytokines. The study also points to the potential positive effect of CoQ10 as an adds- on to conventional antidiabetic therapies.
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MESH Headings
- Animals
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/enzymology
- Diabetes Mellitus, Experimental/metabolism
- Drug Interactions
- Glucose Transport Proteins, Facilitative/metabolism
- Hypoglycemic Agents/pharmacology
- Hypoglycemic Agents/therapeutic use
- Insulin Resistance
- Liver/drug effects
- Liver/metabolism
- Male
- Membrane Proteins/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Nicotinamide Phosphoribosyltransferase/metabolism
- Peroxidase/metabolism
- Phosphatidylinositol 3-Kinases/metabolism
- Protein-Tyrosine Kinases/metabolism
- Rats
- Receptor for Advanced Glycation End Products
- Receptor, Insulin/metabolism
- Receptors, Adiponectin/metabolism
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/metabolism
- Transferases/metabolism
- Ubiquinone/analogs & derivatives
- Ubiquinone/pharmacology
- Ubiquinone/therapeutic use
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Affiliation(s)
- Mohamed M. Amin
- Department of Pharmacology, Medical Division, National Research Center, Cairo, Egypt
| | - Gihan F. Asaad
- Department of Pharmacology, Medical Division, National Research Center, Cairo, Egypt
| | - Rania M. Abdel Salam
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Hanan S. El-Abhar
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
- * E-mail:
| | - Mahmoud S. Arbid
- Department of Pharmacology, Medical Division, National Research Center, Cairo, Egypt
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Liu CW, Yang SY, Lin CK, Liu HS, Ho LT, Wu LY, Lee MJ, Ku HC, Chang HH, Huang RN, Kao YH. The forkhead transcription factor FOXO1 stimulates the expression of the adipocyte resistin gene. Gen Comp Endocrinol 2014; 196:41-51. [PMID: 24291305 DOI: 10.1016/j.ygcen.2013.11.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 10/24/2013] [Accepted: 11/10/2013] [Indexed: 01/27/2023]
Abstract
Resistin is known as an adipocyte-specific hormone that can cause insulin resistance and decrease adipocyte differentiation. It can be regulated by transcriptional factors, but the possible role of forkhead transcription factor FOXO1 in regulating resistin gene expression is still unknown. Using 3T3 fibroblast and C3H10T1/2 and 3T3-L1 adipocytes, we found that transient overexpression of a non-phosphorylatable, constitutively active FOXO1, but not the wild type of FOXO1 or a DNA binding-deficient FOXO1, activated resistin promoter-directed luciferase expression. However, transient overexpression of a dominant-negative FOXO1 inactivated resistin promoter activity and reduced resistin mRNA expression. These observations indicate that the action of FOXO1 on resistin gene expression requires the activation of FOXO1 and that the effect of FOXO1 depends on the phosphorylation and dephosphorylation of FOXO1. The FOXO1 protein target sites on the resistin promoter were localized to the proximal -3545 to -787bp of 5'-flanking region of the resistin promoter. A chromatin immunoprecipitation assay also showed that FOXO1 bound the resistin promoter at nucleotide regions of -1539 to -1366bp and -1016 to -835bp, but not at the regions of -795 to -632bp. Results of this study suggest that FOXO1 transcription factor likely activates the expression of adipocyte resistin gene via direct association with the upstream resistin promoter.
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Affiliation(s)
- Chi-Wei Liu
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan
| | - Shu-Ya Yang
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan
| | - Cheng-Kuo Lin
- Department of Joint Laboratory, Armed Forces Taoyuan General Hospital, Taoyuan, Taiwan
| | - Hang-Seng Liu
- Department of Joint Laboratory, Armed Forces Taoyuan General Hospital, Taoyuan, Taiwan
| | - Low-Tone Ho
- Department of Internal Medicine, Veterans General Hospital, Taipei, Taiwan
| | - Liang-Yi Wu
- Department of Bioscience Technology, Chung-Yuan Christian University, Jhongli, Taoyuan, Taiwan
| | - Meng-Jung Lee
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan
| | - Hui-Chen Ku
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan
| | - Hsin-Huei Chang
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan
| | - Rong-Nan Huang
- Department of Entomology, National Taiwan University, Taipei, Taiwan
| | - Yung-Hsi Kao
- Department of Life Sciences, National Central University, Jhongli, Taoyuan, Taiwan.
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Association between resistin +299A/A genotype and nonalcoholic fatty liver disease in Chinese patients with type 2 diabetes mellitus. Gene 2013; 529:340-4. [PMID: 23954219 DOI: 10.1016/j.gene.2013.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/29/2013] [Accepted: 08/01/2013] [Indexed: 02/08/2023]
Abstract
OBJECTIVE To investigate the relationship between the resistin intronic +299G/A polymorphism and nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM). METHODS We selected 738 T2DM patients, including 395 with NAFLD and 343 without fatty liver disease, as well as 279 healthy control individuals, and analyzed their resistin +299G/A polymorphism genotype by polymerase chain reaction-restriction fragment length polymorphism. RESULTS Plasma resistin levels in T2DM patients with NAFLD were at the highest (P<0.05). The frequency of AA genotype at the +299 site of the resistin gene in patients with concurrent T2DM combined with NAFLD was significantly different from that in the control (P<0.05). The AA genotype was found to be associated with a 1.80-fold increased risk for T2DM combined with NAFLD, 2.05-fold increased risk for obesity and 2.37-fold increased risk for obesity of abdominal type compared to the GG (P<0.05, respectively). The multivariate non-conditional logistic regression model analysis further shows that the AA genotype is a risk factor for the development of NAFLD in T2DM patients (OR, 2.32; 95% CI, 1.05-4.68; P<0.05). CONCLUSION The resistin +299AA genotype may be associated with increases in the risk of the NAFLD development in T2DM patients.
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Qi MM, Guan XQ, Zhu LR, Yang YP. Role of resistin in the development of insulin resistance and hepatic fibrosis in nonalcoholic fatty liver disease. Shijie Huaren Xiaohua Zazhi 2012; 20:1383-1388. [DOI: 10.11569/wcjd.v20.i16.1383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the role of resistin in the development of insulin resistin (IR) and hepatic fibrosis in nonalcoholic fatty liver disease (NAFLD).
METHODS: Thirty male Wistar rats were randomly divided into control group (n = 15) and model group (n = 15). The control group was fed a normal diet, while the model group was given a high fat diet to induce NAFLD. Five rats in each group were killed at 15, 18 and 21 wk. Serum levels of FBG, FINS, type Ⅲ procollagen (PC Ⅲ), hyaluronic acid (HA), type Ⅳ collagen (C Ⅳ) and laminin (LN) were measured. Insulin resistance was calculated by homeostasis model assessment (HOMA-IR). Liver tissue samples were collected and the degree of hepatic fibrosis was graded by hematoxylin-eosin (HE) staining, VG staining and electron microscopy. RT-PCR was used to determine the expression level of resistin mRNA.
RESULTS: The degree of hepatic fibrosis increased with the time of feeding the high fat diet. Compared to the control group, the levels of HOMA-IR, PC Ⅲ, LN, C Ⅳ, HA and resistin significantly increased, which was particularly prominent at week 21 (33.74 μg/L ± 10.41 μg/L, 2.96 μg/L ± 0.76 μg/L, 4.14 μg/L ± 1.07 μg/L, 19.07 μg/L ± 2.78 μg/L, 848.87 μg/L ± 204.04 μg/L, 0.99 μg/L ± 0.10 μg/L, all P < 0.05 or 0.01). Resistin expression was positively correlated with the levels of HOMA-IR, PCIII, LN, C Ⅳ, and HA (r = 0.77, 0.80, 0.68, 0.67, 0.76, all P < 0.05 or 0.01).
CONCLUSION: Resistin may induce IR and promote the formation of hepatic fibrosis in NAFLD.
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Veyrat-Durebex C, Deblon N, Caillon A, Andrew R, Altirriba J, Odermatt A, Rohner-Jeanrenaud F. Central glucocorticoid administration promotes weight gain and increased 11β-hydroxysteroid dehydrogenase type 1 expression in white adipose tissue. PLoS One 2012; 7:e34002. [PMID: 22479501 PMCID: PMC3316512 DOI: 10.1371/journal.pone.0034002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 02/24/2012] [Indexed: 01/03/2023] Open
Abstract
Glucocorticoids (GCs) are involved in multiple metabolic processes, including the regulation of insulin sensitivity and adipogenesis. Their action partly depends on their intracellular activation by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). We previously demonstrated that central GC administration promotes hyperphagia, body weight gain, hyperinsulinemia and marked insulin resistance at the level of skeletal muscles. Similar dysfunctions have been reported to occur upon specific overexpression of 11β-HSD1 in adipose tissue. The aim of the present study was therefore to determine whether the effects of central GC infusion may enhance local GC activation in white adipose tissue. Male Wistar and Sprague Dawley (SD) rats were intracerebroventricularly infused with GCs for 2 to 3 days. Body weight, food intake and metabolic parameters were measured, and expression of enzymes regulating 11β-HSD1, as well as that of genes regulated by GCs, were quantified. Central GC administration induced a significant increase in body weight gain and in 11β-HSD1 and resistin expression in adipose tissue. A decrease 11β-HSD1 expression was noticed in the liver of SD rats, as a partial compensatory mechanism. Such effects of GCs are centrally elicited. This model of icv dexamethasone infusion thus appears to be a valuable acute model, that helps delineating the initial metabolic defects occurring in obesity. An impaired downregulation of intracellular GC activation in adipose tissue may be important for the development of insulin resistance.
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Affiliation(s)
- Christelle Veyrat-Durebex
- Laboratory of Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
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15
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Resistin expression in breast cancer tissue as a marker of prognosis and hormone therapy stratification. Gynecol Oncol 2012; 125:742-50. [PMID: 22370603 DOI: 10.1016/j.ygyno.2012.02.032] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 02/16/2012] [Accepted: 02/20/2012] [Indexed: 12/28/2022]
Abstract
OBJECTIVE Adipocytokines are adipocyte-derived hormones and well documented to be involved in carcinogenesis. The expression of resistin, a newly discovered adipocytokine, in breast cancer tissues was determined and correlated with patient clinicopathological variables. METHODS Resistin expression in breast cancer tissues and the normal adjacent breast tissues was analyzed by immunohistochemistry and was correlated with clinicopathological variables as well as recurrence rates by the chi-square test. The prognostic value of resistin for disease-free and overall survival was determined by Kaplan-Meier estimates, and the significance of differences between curves was evaluated by the log-rank test. RESULTS High resistin expression was predominantly observed in breast cancer tissues but not the adjacent normal breast tissues. High resistin expression in breast cancer tissues was correlated significantly with tumor stage, tumor size, lymph node metastasis and estrogen receptor status. Hormone therapy, but not radiotherapy or chemotherapy, decreased the recurrence rate in patients with high resistin expression. While high resistin expression was associated with poor disease-free and overall survival, Cox regression analysis also revealed that resistin was an independent predictor of disease-free and overall survival. CONCLUSIONS High resistin expression in breast cancer tissue is associated with a more malignant clinicopathological status as well as poor patient survival. Resistin may therefore hold promise as an independent prognosis predictor for breast cancer, as a marker for hormone therapy stratification and as a potential therapeutic target.
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Lipid metabolism in mammalian tissues and its control by retinoic acid. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:177-89. [PMID: 21669299 DOI: 10.1016/j.bbalip.2011.06.001] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 05/10/2011] [Accepted: 06/01/2011] [Indexed: 12/18/2022]
Abstract
Evidence has accumulated that specific retinoids impact on developmental and biochemical processes influencing mammalian adiposity including adipogenesis, lipogenesis, adaptive thermogenesis, lipolysis and fatty acid oxidation in tissues. Treatment with retinoic acid, in particular, has been shown to reduce body fat and improve insulin sensitivity in lean and obese rodents by enhancing fat mobilization and energy utilization systemically, in tissues including brown and white adipose tissues, skeletal muscle and the liver. Nevertheless, controversial data have been reported, particularly regarding retinoids' effects on hepatic lipid and lipoprotein metabolism and blood lipid profile. Moreover, the molecular mechanisms underlying retinoid effects on lipid metabolism are complex and remain incompletely understood. Here, we present a brief overview of mammalian lipid metabolism and its control, introduce mechanisms through which retinoids can impact on lipid metabolism, and review reported activities of retinoids on different aspects of lipid metabolism in key tissues, focusing on retinoic acid. Possible implications of this knowledge in the context of the management of obesity and the metabolic syndrome are also addressed. This article is part of a Special Issue entitled Retinoid and Lipid Metabolism.
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Song H, Guan Y, Zhang L, Li K, Dong C. SPARC interacts with AMPK and regulates GLUT4 expression. Biochem Biophys Res Commun 2010; 396:961-6. [PMID: 20460104 DOI: 10.1016/j.bbrc.2010.05.033] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 11/25/2022]
Abstract
AMP-activated protein kinase (AMPK) is a critical regulator of glucose metabolism. To elucidate the biochemical mechanisms by which AMPK regulates glucose and fat metabolism, we conducted a yeast two-hybrid screen to identify its interacting partners. A yeast two-hybrid system was used to screen a mouse embryo cDNA library for proteins able to bind mouse AMPK alpha 1. We also demonstrated an endogenous interaction between AMPK alpha 1 and its interacting partner by co-immunoprecipitation of the endogenous proteins using specific antibodies in HepG2 cells, and in rat kidney, liver, skeletal muscle, and fat tissue. We show that secreted protein acidic and rich in cysteine (SPARC) is an AMPK-interacting protein, and the two proteins enhance each other. AMPK activation increases SPARC expression, and knockdown of AMPK to inhibit endogenous AMPK expression reduces SPARC protein levels. On the other hand, SPARC siRNA reduces AICAR-stimulated AMPK phosphorylation. SPARC affects AMPK-mediated glucose metabolism through regulation of Glut4 expression in L6 myocytes. Our findings suggest that SPARC may be involved in regulating glucose metabolism via AMPK activation. These results provide a starting point for efforts to clarify the relationship between AMPK and SPARC, and deepen our understanding of their roles in fat and glucose metabolism.
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Affiliation(s)
- Haiyan Song
- Department of Endocrinology and Metabolism, The Second Affiliated Hospital of Harbin Medical University, Xuefu Road 246, Harbin 150080, China.
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Singh AK, Battu A, Mohareer K, Hasnain SE, Ehtesham NZ. Transcription of human resistin gene involves an interaction of Sp1 with peroxisome proliferator-activating receptor gamma (PPARgamma). PLoS One 2010; 5:e9912. [PMID: 20360975 PMCID: PMC2848011 DOI: 10.1371/journal.pone.0009912] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Accepted: 02/26/2010] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Resistin is a cysteine rich protein, mainly expressed and secreted by circulating human mononuclear cells. While several factors responsible for transcription of mouse resistin gene have been identified, not much is known about the factors responsible for the differential expression of human resistin. METHODOLOGY/PRINCIPAL FINDING We show that the minimal promoter of human resistin lies within approximately 80 bp sequence upstream of the transcriptional start site (-240) whereas binding sites for cRel, CCAAT enhancer binding protein alpha (C/EBP-alpha), activating transcription factor 2 (ATF-2) and activator protein 1 (AP-1) transcription factors, important for induced expression, are present within sequences up to -619. Specificity Protein 1(Sp1) binding site (-276 to -295) is also present and an interaction of Sp1 with peroxisome proliferator activating receptor gamma (PPARgamma) is necessary for constitutive expression in U937 cells. Indeed co-immunoprecipitation assay demonstrated a direct physical interaction of Sp1 with PPARgamma in whole cell extracts of U937 cells. Phorbol myristate acetate (PMA) upregulated the expression of resistin mRNA in U937 cells by increasing the recruitment of Sp1, ATF-2 and PPARgamma on the resistin gene promoter. Furthermore, PMA stimulation of U937 cells resulted in the disruption of Sp1 and PPARgamma interaction. Chromatin immunoprecipitation (ChIP) assay confirmed the recruitment of transcription factors phospho ATF-2, Sp1, Sp3, PPARgamma, chromatin modifier histone deacetylase 1 (HDAC1) and the acetylated form of histone H3 but not cRel, C/EBP-alpha and phospho c-Jun during resistin gene transcription. CONCLUSION Our findings suggest a complex interplay of Sp1 and PPARgamma along with other transcription factors that drives the expression of resistin in human monocytic U937 cells.
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Affiliation(s)
| | - Aruna Battu
- National Institute of Nutrition, Indian Council for Medical Research, Hyderabad, India
| | | | - Seyed E. Hasnain
- University of Hyderabad, Hyderabad, India
- Institute of Life Sciences, University of Hyderabad, Hyderabad, India
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Nasreen Z. Ehtesham
- National Institute of Nutrition, Indian Council for Medical Research, Hyderabad, India
- Institute of Life Sciences, University of Hyderabad, Hyderabad, India
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Filková M, Haluzík M, Gay S, Senolt L. The role of resistin as a regulator of inflammation: Implications for various human pathologies. Clin Immunol 2009; 133:157-70. [PMID: 19740705 DOI: 10.1016/j.clim.2009.07.013] [Citation(s) in RCA: 300] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/24/2009] [Accepted: 07/29/2009] [Indexed: 12/28/2022]
Abstract
Resistin was originally described as an adipocyte-secreted peptide that induced insulin resistance in rodents. Increasing evidence indicates its important regulatory roles in various biological processes, including several inflammatory diseases. Further studies have shown that resistin in humans, in contrast to its production by adipocytes in mice, is synthesized predominantly by mononuclear cells both within and outside adipose tissue. Possible roles for resistin in obesity-related subclinical inflammation, atherosclerosis and cardiovascular disease, non-alcoholic fatty liver disease, rheumatic diseases, malignant tumors, asthma, inflammatory bowel disease, and chronic kidney disease have already been demonstrated. In addition, resistin can modulate several molecular pathways involved in metabolic, inflammatory, and autoimmune diseases. In this review, current knowledge about the functions and pathophysiological implications of resistin in different human pathologies is summarized, although there is a significant lack of firm evidence regarding the specific role resistin plays in the "orchestra" of the numerous mediators of inflammation.
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Affiliation(s)
- Mária Filková
- Institute of Rheumatology and Connective Tissue Research Laboratory, Department of Rheumatology of First Faculty of Medicine, Charles University in Prague, Na Slupi 4, Prague 2, 128 50, Czech Republic
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Schaalan M, El-Abhar HS, Barakat M, El-Denshary ES. Westernized-like-diet-fed rats: effect on glucose homeostasis, lipid profile, and adipocyte hormones and their modulation by rosiglitazone and glimepiride. J Diabetes Complications 2009; 23:199-208. [PMID: 18407527 DOI: 10.1016/j.jdiacomp.2008.02.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 01/20/2008] [Accepted: 02/09/2008] [Indexed: 01/11/2023]
Abstract
Wersternized diet, containing high fat diet intake combined with high consumption of softdrinks, is accused with the emerge of modern epidemic obesity and diabesity. Therefore, we aimed to study the effect of this diet combination on the homeostasis of glucose, lipids, and some adipohormones in rats and to simulate the metabolic perturbations induced by the unhealthy Westernized diet intake, leading to the development of type 2 diabetes. To achieve this, we divided male Wistar rats (80-120 g) into two main groups: the first was fed commercial normal fat diet and the second received an in-house-prepared high-fat diet (HFD), combined with fructose in drinking water for a period of 6 weeks, followed by a subdiabetogenic dose of streptozotocin (STZ) (35 mg/kg) to produce frank hyperglycemia. The effect of this diet alone or after 2 weeks of treatment with rosiglitazone or glimepiride on glucose homeostasis, lipid profile, and levels of resistin and leptin was studied. The HFD/fructose/STZ diet elevated fasting plasma glucose, fructosamine, insulin, and homeostasis model assessment (HOMA) index, as well as serum triglycerides (TGs), total cholesterol (TC), and low-density lipoprotein cholesterol, with a decrease in high-density lipoprotein cholesterol. Hepatic TG and TC levels, as well as serum activities of aspartate transaminase (AST), alanine transaminase (ALT), and lactate dehydrogenase (LDH), were increased, suggesting a diet-induced hepatic steatosis, beside the increased levels of serum resistin and leptin. Rosiglitazone corrected the altered parameters measured, except for liver TGs; similarly, glimepiride reinstated the inverted parameters but raised insulin level and, consequently, the HOMA index. These results show that this diet could be used to induce an effect that mimics human type 2 diabetes with its metabolic disturbances and is suitable for screening the antidiabetic agents used for management of this disease.
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Affiliation(s)
- Mona Schaalan
- Biochemistry Department, Faculty of Pharmacy, Misr International University (MIU), Cairo, Egypt.
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Shen H, Zheng PY, Ji G, Xing LJ. Roles of adipocytokines in the pathogenesis of non-alcoholic fatty liver disease. Shijie Huaren Xiaohua Zazhi 2009; 17:1212-1217. [DOI: 10.11569/wcjd.v17.i12.1212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is closely associated with obesity, abnormal lipid metabolism and insulin resistance. Adipocytokines, which secrete leptin, adiponectin, tumor necrosis factor, peroxisome proliferator-activated receptor, resistin, interleukin-6 (IL-6), interleukin-8 (IL-8), visfatin, plasminogen activator inhibitor-1, play important roles in the pathogenesis and development of NAFLD. This paper tries to further discuss the roles of adipocytokines in the purpose of providing new ideas and methods for clinical research.
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Dongxia L, Qi H, Lisong L, Jincheng G. Association of peroxisome proliferator-activated receptorgamma gene Pro12Ala and C161T polymorphisms with metabolic syndrome. Circ J 2008; 72:551-7. [PMID: 18362424 DOI: 10.1253/circj.72.551] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
UNLABELLED BACKGROUND Peroxisome proliferator-activated receptor gamma (PPARgamma) is involved mainly in adipocyte differentiation and has been suggested to play an important role in the pathogenesis of insulin resistance (IR) and atherosclerosis. The frequencies of 2 common polymorphisms of the PPARgamma gene, Pro12Ala single nucleotide polymorphism (SNP) in exon B and C161T SNP in exon 6, were investigated in 792 subjects and the correlations between the different genotypes, IR and metabolic syndrome (MS) were analyzed. METHODS AND RESULTS Anthropometric measurements, fasting glucose, insulin and lipid profiles were measured in 792 people of the Han population in Beijing, China. Homeostatic model assessments and quantitative insulin sensitivity check indices were calculated. MS was diagnosed according to the IDF guidelines (2005) for a Chinese population. Polymerase chain reaction - restriction fragment length polymorphism were performed for DNA genotyping. For the C161T polymorphism, allele frequencies were 0.804 for the C allele and 0.196 for the T allele. For Pro12Ala, allele frequencies were 0.947 for proline and 0.053 for alanine. There was no Ala12Ala homozygote in the population. No differences were seen in the mean values of age, body mass index (BMI), blood pressure or fasting blood glucose level among different genotypes when analyzed as a whole. Subjects with an A or T allele had lower fasting insulin levels, HOMA-IR levels, and a lower level QUICKI trend. Further analysis by age was conducted, and A or T allele carriers in the <60 year group showed a trend of lower triglyceride and a higher high-density lipoprotein-cholesterol level, but this was not statistically significant. When subjects were divided into 4 groups according to the combination of genetic alleles of the 2 polymorphisms, the subjects with Pro12Ala and a T allele simultaneously showed a significantly higher BMI than those without the Ala allele. The presence of a T allele in the C161T polymorphism and Pro12Ala polymorphism seems to affect body weight, which is similar to the results found in previous studies. CONCLUSIONS Both polymorphisms showed a significant association with IR, but failed to show an association with MS components. Those with an A allele of Pro12Ala and a T allele of the C161T polymorphism showed a higher BMI, which requires further investigation.
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Affiliation(s)
- Liu Dongxia
- Department of Cardiology, Xuanwu Hospital, Capital Medical University, Beijing, China
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Yao XH, Nyomba BLG. Hepatic insulin resistance induced by prenatal alcohol exposure is associated with reduced PTEN and TRB3 acetylation in adult rat offspring. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1797-806. [DOI: 10.1152/ajpregu.00804.2007] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Prenatal alcohol exposure (EtOH) results in insulin resistance in rats of both sexes with increased expression of hepatic gluconeogenic genes and glucose production. To investigate whether hepatic insulin signaling is defective, we studied 3-mo-old female offspring of dams that were given EtOH during pregnancy compared with those from pair-fed and control dams. We performed an intraperitoneal pyruvate tolerance test, determined the phosphorylation status of hepatic phosphoinositide-dependent protein kinase-1 (PDK1), Akt, and PKCζ before and after intravenous insulin bolus, and measured mRNA and in vivo acetylation of TRB3 (tribbles 3) and PTEN (phosphatase and tensin homolog deleted on chromosome ten) as well as the expression of the histone acetylase (HAT) PCAF (p300/CREB-binding protein-associated factor), histone deacetylase-1 (HDAC1), and HAT and HDAC activities. In EtOH compared with pair-fed and control offspring, basal and pyruvate-induced blood glucose was increased, insulin-induced PDK1, Akt, and PKCζ phosphorylation was reduced, and expression of PTEN and TRB3 was increased while their acetylation status was decreased in association with increased HDAC and decreased HAT activities. Thus female adult rats prenatally exposed to EtOH have increased gluconeogenesis, reduced insulin signaling, and increased PTEN and TRB3 expression in the liver. In addition, PTEN and TRB3 are hypoacetylated, which can contribute to Akt-inhibiting activity. These results suggest that hepatic insulin resistance in rats prenatally exposed to EtOH is explained, at least in part, by increased PTEN and TRB3 activity due to both increased gene expression and reduced acetylation.
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Pistilli EE, Gordish-Dressman H, Seip RL, Devaney JM, Thompson PD, Price TB, Angelopoulos TJ, Clarkson PM, Moyna NM, Pescatello LS, Visich PS, Zoeller RF, Hoffman EP, Gordon PM. Resistin polymorphisms are associated with muscle, bone, and fat phenotypes in white men and women. Obesity (Silver Spring) 2007; 15:392-402. [PMID: 17299113 DOI: 10.1038/oby.2007.543] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVE The biological function of resistin (RST) is unknown, although it may have roles in obesity, diabetes, and insulin resistance. The objective of this study was to examine the effects of single nucleotide polymorphisms (SNPs) in the human RST gene on muscle, bone, and adipose tissue phenotypes and in response to resistance training (RT). RESEARCH METHODS AND PROCEDURES Subjects were white and consisted of strength (n = 482) and size (n = 409) cohorts who had not performed RT in the previous year. Subjects completed 12 weeks of structured, unilateral upper arm RT aimed at increasing the size and strength of the non-dominant arm, using their dominant arm as an untrained control. Strength measurements were taken pre- and post-12-week RT and consisted of elbow flexor isometric strength and one-repetition maximum during a biceps curl using free weights. Whole muscle, subcutaneous fat, and cortical bone volumes were measured by magnetic resonance imaging. Six RST SNPs were identified. Analysis of covariance was used to test for effects of the SNPs on pre- and post-muscle strength and whole muscle, fat, and bone volumes independent of gender, age, and body weight. RESULTS Five RST SNPs (-537 A>C, -420 C>G, 398 C>T, 540 G>A, 980 C>G) were associated with measured phenotypes among subjects when stratified by BMI (<25, >/ or = 25 kg/m(2)). Several gender-specific associations were observed between RST SNPs and phenotypes among individuals with a BMI > or = 25. Conversely, only two associations were observed among individuals with a BMI < 25. DISCUSSION These data support previous identified associations of RST with adipose tissue and demonstrate additional associations with bone and skeletal muscle that warrant further investigation.
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Affiliation(s)
- Emidio E Pistilli
- Division of Exercise Physiology, School of Medicine, West Virginia University, Morgantown, WV 26506-9227, USA
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Schäffler A, Weigert J, Neumeier M, Schölmerich J, Buechler C. Regulation and function of collagenous repeat containing sequence of 26-kDa protein gene product "cartonectin". Obesity (Silver Spring) 2007; 15:303-13. [PMID: 17299102 DOI: 10.1038/oby.2007.566] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Collagenous repeat containing sequence of 26-kDa protein (CORS-26) was identified as a new gene transcript expressed in cartilage with unknown function. It was the aim of this study to investigate expression, regulation, and function of CORS-26 in adipocytes. RESEARCH METHODS AND PROCEDURES CORS-26 mRNA and protein expression was studied by reverse transcriptase-polymerase chain reaction, Western blot analysis, and quantitative real-time polymerase chain reaction. Transcriptional regulation was studied by electrophoretic mobility shift assay and luciferase reporter gene assay. The adipocytic secretion of adiponectin and resistin was measured by enzyme-linked immunosorbent assay. RESULTS CORS-26 mRNA is absent in 3T3-L1 preadipocytes and adipocytes after 48 hours of differentiation. CORS-26 mRNA was induced from Day 4 to Day 9 of adipocyte differentiation. CORS-26 protein was induced in mature adipocytes. Peroxisome proliferator-activated receptor (PPAR) gamma (but not PPARalpha) in nuclear extracts prepared from adipocytes was shown to bind specifically to a putative peroxisome proliferator response element-one-half-site located at -641/-596 bp. Increasing doses of the ligands troglitazone (1, 10, 20 microM) and fenofibrate (50, 100, 200 microM) but not 15-deoxy-prostaglandin (J(2)) (0.5, 1.0, 2.5 microM) resulted in a significant reduction of both promoter activity and the amount of mRNA expression. Recombinant CORS-26 significantly stimulated the adipocytic secretion of adiponectin and resistin in a dose-dependent manner. DISCUSSION The mRNA and protein expression profile puts CORS-26 in the adipocytokine family. Cartonectin is negatively regulated by exogenous, but not endogenous, PPARgamma ligands. Because CORS-26 up-regulates adipokine secretion, it might be involved in metabolic and immunologic pathways.
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Affiliation(s)
- Andréas Schäffler
- Department of Internal Medicine I, University of Regensburg, D-93042 Regensburg, Germany.
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Yao XH, Grégoire Nyomba BL. Abnormal glucose homeostasis in adult female rat offspring after intrauterine ethanol exposure. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1926-33. [PMID: 17218436 DOI: 10.1152/ajpregu.00822.2006] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Adverse events during pregnancy, including prenatal ethanol (EtOH) exposure, are associated with insulin-resistant diabetes in male rat offspring, but it is unclear whether this is true for female offspring. We investigated whether prenatal EtOH exposure alters glucose metabolism in adult female rat offspring and whether this is associated with reduced in vivo insulin signaling in skeletal muscle. Female Sprague-Dawley rats were given EtOH, 4 g.kg(-1).day(-1) by gavage throughout pregnancy. Glucose tolerance test and hyperinsulinemic euglycemic clamp were performed, and insulin signaling was investigated in skeletal muscle, in adult female offspring. We gave insulin intravenously to these rats and determined the association of glucose transporter-4 with plasma membranes, as well as the phosphorylation of phosphoinositide-dependent protein kinase-1 (PDK1), Akt, and PKCzeta. Although EtOH offspring had normal birth weight, they were overweight as adults and had fasting hyperglycemia, hyperinsulinemia, and reduced insulin-stimulated glucose uptake. After insulin treatment, EtOH-exposed rats had decreased membrane glucose transporter-4, PDK1, Akt, and PKCzeta in the gastrocnemius muscle, compared with control rats. Insulin stimulation of PDK1, Akt, and PKCzeta phosphorylation was also reduced. In addition, the expression of the protein tribbles-3 and the phosphatase enzyme activity of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), which prevent Akt activation, were increased in muscle from EtOH-exposed rats. Female rat offspring exposed to EtOH in utero develop insulin-resistant diabetes in association with excessive PTEN and tribbles-3 signaling downstream of the phosphatidylinositol 3-kinase pathway in skeletal muscle, which may be a mechanism for the abnormal glucose tolerance.
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Affiliation(s)
- Xing-Hai Yao
- Department of Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
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Brown R, Imran SA, Belsham DD, Ur E, Wilkinson M. Adipokine gene expression in a novel hypothalamic neuronal cell line: resistin-dependent regulation of fasting-induced adipose factor and SOCS-3. Neuroendocrinology 2007; 85:232-41. [PMID: 17579277 DOI: 10.1159/000104248] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2005] [Accepted: 04/24/2007] [Indexed: 12/18/2022]
Abstract
Adipokines such as leptin, resistin, and fasting-induced adipose factor (FIAF) are secreted by adipocytes, but their expression is also detectable in the brain and pituitary. The role of central adipokines remains elusive, but we speculate that they may modulate those hypothalamic signaling pathways that control energy homeostasis. Here we describe experiments to test this in which we exploited a novel hypothalamic neuronal cell line (N-1) that expresses a variety of neuropeptides and receptors that are known to be implicated in appetite regulation. Using real-time RT-PCR, we confirmed that N-1 neurons express resistin (rstn) and fiaf, as well as suppressor of cytokine signaling-3 (socs-3), a feedback inhibitor of leptin signaling. Treating N-1 cells with recombinant resistin (200 ng/ml, 30 min) reduced both fiaf (25%, p < 0.005) and socs-3 (29%, p < 0.005) mRNA levels, and similar reductions in fiaf (40%, p < 0.001) and socs-3 (25%, p < 0.001) resulted following the overexpression of resistin. Conversely, when RNA interference (RNAi) was used to reduce endogenous rstn levels (-60%, p < 0.005), fiaf and socs-3 expression was increased (46 and 65% respectively, p < 0.005). A similar reduction in rstn mRNA was achieved using RNAi in differentiated 3T3-L1 adipocytes, and this manipulation also reduced fiaf and socs-3 expression (-53, -21 and -20% respectively, p < 0.005). In contrast, although RNAi successfully reduced fiaf mRNA by 50% (p < 0.001) in N-1 cells and 40% (p < 0.001) in 3T3-L1 cells, there was no effect on rstn or socs-3 mRNA. These data suggest that resistin exerts a novel autocrine/paracrine control over fiaf and socs-3 expression in both 3T3-L1 adipocytes and N-1 neurons. Such a mechanism could be part of the central feedback system that modulates the effects of adipokines, and other adiposity signals, implicated in hypothalamic energy homeostasis. However, it remains to be determined whether these in vitro results can be translated to the control of adipokine expression in brain and adipose tissue.
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Affiliation(s)
- Russell Brown
- Department of Obstetrics, Faculty of Medicine, Dalhousie University, Halifax, N.S., Canada
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Chen YH, Lee MJ, Chang HH, Hung PF, Kao YH. 17 beta-estradiol stimulates resistin gene expression in 3T3-L1 adipocytes via the estrogen receptor, extracellularly regulated kinase, and CCAAT/enhancer binding protein-alpha pathways. Endocrinology 2006; 147:4496-504. [PMID: 16740979 DOI: 10.1210/en.2005-1655] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Resistin is known as an adipocyte-specific secretory hormone that can cause insulin resistance and decrease adipocyte differentiation. It can be regulated by sexual hormones, but the mechanism of estrogen's actions is still not clear. Using 3T3-L1 adipocytes, we found that 17 beta-estradiol (E2) up-regulated resistin mRNA expression in a dose- and time-dependent manner. The concentration of E2 that increased resistin mRNA levels by 100-250% was approximately 1 nM for a range of 1-24 h of treatment. Treatment with either actinomycin D or cycloheximide prevented E2-stimulated resistin mRNA expression, suggesting that the effect of E2 requires new mRNA and protein synthesis. Although E2 was shown to increase activities of the estrogen receptor (ER) and MAPK kinase 1 and the association of nuclear ER alpha and CCAAT/enhancer binding protein-alpha with the resistin gene promoter, signaling was demonstrated to be blocked by pretreatment with either ICI182780 or PD98059. Neither SB203580 nor LY294002 changed the E2-increased levels of resistin mRNA, but they respectively inhibited E2-stimulated phosphorylation of p38 MAPK and Akt. These results imply the ER alpha, ERK, and CCAAT/enhancer binding protein- are necessary for the E2 stimulation of transcription from the resistin promoter. Moreover, PD98059, but not SB203580 or LY294002, antagonized E2-increased resistin protein release. These data suggest that E2 likely modifies the distribution of the resistin protein between the intracellular and extracellular compartments via an ERK-dependent pathway.
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Affiliation(s)
- Yen-Hang Chen
- Department of Life Science, College of Science, National Central University, Chung-Li City, Taoyuan, Taiwan 32054
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Vankoningsloo S, De Pauw A, Houbion A, Tejerina S, Demazy C, de Longueville F, Bertholet V, Renard P, Remacle J, Holvoet P, Raes M, Arnould T. CREB activation induced by mitochondrial dysfunction triggers triglyceride accumulation in 3T3-L1 preadipocytes. J Cell Sci 2006; 119:1266-82. [PMID: 16537646 DOI: 10.1242/jcs.02848] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Several mitochondrial pathologies are characterized by lipid redistribution and microvesicular cell phenotypes resulting from triglyceride accumulation in lipid-metabolizing tissues. However, the molecular mechanisms underlying abnormal fat distribution induced by mitochondrial dysfunction remain poorly understood. In this study, we show that inhibition of respiratory complex III by antimycin A as well as inhibition of mitochondrial protein synthesis trigger the accumulation of triglyceride vesicles in 3T3-L1 fibroblasts. We also show that treatment with antimycin A triggers CREB activation in these cells. To better delineate how mitochondrial dysfunction induces triglyceride accumulation in preadipocytes, we developed a low-density DNA microarray containing 89 probes, which allows gene expression analysis for major effectors and/or markers of adipogenesis. We thus determined gene expression profiles in 3T3-L1 cells incubated with antimycin A and compared the patterns obtained with differentially expressed genes during the course of in vitro adipogenesis induced by a standard pro-adipogenic cocktail. After an 8-day treatment, a set of 39 genes was found to be differentially expressed in cells treated with antimycin A, among them CCAAT/enhancer-binding protein alpha (C/EBPalpha), C/EBP homologous protein-10 (CHOP-10), mitochondrial glycerol-3-phosphate dehydrogenase (GPDmit), and stearoyl-CoA desaturase 1 (SCD1). We also demonstrate that overexpression of two dominant negative mutants of the cAMP-response element-binding protein CREB (K-CREB and M1-CREB) and siRNA transfection, which disrupt the factor activity and expression, respectively, inhibit antimycin-A-induced triglyceride accumulation. Furthermore, CREB knockdown with siRNA also downregulates the expression of several genes that contain cAMP-response element (CRE) sites in their promoter, among them one that is potentially involved in synthesis of triglycerides such as SCD1. These results highlight a new role for CREB in the control of triglyceride metabolism during the adaptative response of preadipocytes to mitochondrial dysfunction.
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Affiliation(s)
- Sébastien Vankoningsloo
- Laboratory of Biochemistry and Cellular Biology, University of Namur (F.U.N.D.P.), Rue de Bruxelles, 61, 5000 Namur, Belgium
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30
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Otto C, Otto B, Göke B, Pfeiffer AFH, Lehrke M, Vogeser M, Spranger J, Parhofer KG. Increase in adiponectin levels during pioglitazone therapy in relation to glucose control, insulin resistance as well as ghrelin and resistin levels. J Endocrinol Invest 2006; 29:231-6. [PMID: 16682836 DOI: 10.1007/bf03345545] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Glitazones increase the secretion of the adipocyte-derived hormone adiponectin. Furthermore, the gastric signal peptide ghrelin is known to suppress adiponectin expression in adipocyte cell culture models. It is not known whether the increase in adiponectin during glitazone therapy is due to a suppression of ghrelin levels, a decrease of resistin concentrations or an amelioration of glucose control. In 10 patients (age 71+/-9 yr, body mass index 29.9+/-3.6 kg/m(2), HbA1c 6.9+/-0.5%) with Type 2 diabetes, who had already been treated with sulfonylureas, we additionally initiated a pioglitazone therapy (30 mg/day) for 12 weeks. To investigate the pioglitazone effect independently of blood glucose, glycosylated hemoglobin (HbA1c) was kept unchanged by reducing the daily dose of sulfonylurea if necessary. Ghrelin concentration [radioimmunoassay (RIA), Phoenix Pharmaceuticals, Mountain View, CA, USA], adiponectin levels [enzyme-linked immunosorbent assay (ELISA), Biovendor, Heidelberg, Germany] as well as resistin concentrations (ELISA, Linco Research, St. Charles, MO, USA) were measured before and after pioglitazone. Glucose control remained unchanged within the 12-week pioglitazone therapy (HbA1c 6.9+/-0.5% before vs 6.8+/-0.6% after pioglitazone) while body weight increased from 86.6+/-9.2 to 88.0+/-9.4 kg (p<0.05), and insulin concentration decreased from 19.6+/-5.7 to 10.1+/-1.6 microU/ml (p<0.05). Adiponectin concentration increased in all patients from 7.70+/-2.47 to 23.33+/-8.28 microg/ml (p<0.01), while resistin concentrations tended to decrease (by 15%; p=0.059). However, ghrelin remained unchanged during therapy. No correlations were observed either between ghrelin, resistin, insulin and adiponectin, or between body weight and hormone plasma levels. The increase in adiponectin levels during pioglitazone therapy seems to be at least partly independent of blood glucose and insulin concentration as well as of ghrelin levels, and it was not associated with a decrease in resistin concentrations.
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Affiliation(s)
- C Otto
- Medical Department 2, Grosshadern, University Hospital of Munich, Marchioninistrasse 15, D-81377 Munich, Germany.
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31
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Zhou L, Xia T, Li Y, Chen X, Peng Y, Yang Z. Transcriptional regulation of the resistin gene. Domest Anim Endocrinol 2006; 30:98-107. [PMID: 16076545 DOI: 10.1016/j.domaniend.2005.06.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Revised: 06/20/2005] [Accepted: 06/24/2005] [Indexed: 11/26/2022]
Abstract
Resistin, which is a protein that is secreted exclusively by adipocytes, plays an important role in insulin resistance and adipocyte differentiation. Adipocytes express significant amounts of resistin mRNA, while preadipocytes express low levels of resistin mRNA. The mechanism that causes this difference is unclear. Therefore, we studied the mechanism regulating resistin expression and the roles of different transcriptional factors in this process. The results from fluorescent photography and semi-quantitative RT-PCR showed that sterol regulatory element-binding protein 1c (SREBP1c) and cyclic AMP response-element-binding protein (CREB) had no effect on resistin expression. By contrast, CCAAT/enhancer-binding protein-alpha (C/EBPalpha) increased resistin mRNA levels both in 3T3-L1 preadipocytes and in 293T cells. The relative increase in the amount of resistin mRNA in the 293T cells was much larger than that in the 3T3-L1 preadipocytes. Moreover, while C/EBPalpha was necessary for resistin expression, we found that up-regulating C/EBPalpha levels alone was not sufficient to induce a similar level of resistin in preadipocytes to that in adipocytes.
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Affiliation(s)
- Lei Zhou
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan city, Hubei Province 430070, China
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32
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Liu HS, Chen YH, Hung PF, Kao YH. Inhibitory effect of green tea (-)-epigallocatechin gallate on resistin gene expression in 3T3-L1 adipocytes depends on the ERK pathway. Am J Physiol Endocrinol Metab 2006; 290:E273-81. [PMID: 16159906 DOI: 10.1152/ajpendo.00325.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Resistin (Rstn) is known as an adipocyte-specific secretory hormone that can cause insulin resistance and decrease adipocyte differentiation. By contrast, green tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been reported as body weight and diabetes chemopreventatives. Whether EGCG regulates production of Rstn is unknown. Using 3T3-L1 adipocytes, we found that EGCG at 20 and 100 microM suppressed Rstn mRNA levels by approximately 35 and 50%, respectively, after 3 h. The basal half-life of Rstn mRNA induced by actinomycin D was >12 h but shifted to 3 h in the presence of EGCG. This suggests that EGCG regulates the stability of Rstn mRNA. Treatment with cycloheximide did not prevent EGCG-suppressed Rstn mRNA levels, which suggests that the effect of EGCG does not require new protein synthesis. Intracellular Rstn protein significantly decreased in the presence of 100 microM EGCG 3 h after treatment, whereas the release of the Rstn protein did not significantly change. This suggests that EGCG may modulate the distribution of Rstn protein between the intracellular and extracellular compartments. EGCG did not affect the amounts of extracellular signal-related kinase-1/2 (ERK1/2), phospho-JNK, phospho-p38, and phospho-Akt proteins but reduced the amounts of phospho-ERK1/2 proteins. Overexpression with MEK1 blocked EGCG-inhibited Rstn mRNA expression. These data suggest that EGCG downregulates Rstn expression via a pathway that is dependent on the ERK pathway.
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Affiliation(s)
- Hang-Seng Liu
- Department of General Medical Laboratory, Armed Forces Tao-Yuan General Hospital, Chung-Li City, Tao-Yuan, Taiwan
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Abstract
Type 2 diabetes is characterized by insulin resistance and impaired insulin secretion. Considerable evidence implicates altered fat topography and defects in adipocyte metabolism in the pathogenesis of type 2 diabetes. In individuals who develop type 2 diabetes, fat cells tend to be enlarged. Enlarged fat cells are resistant to the antilipolytic effects of insulin, leading to day-long elevated plasma free fatty acid (FFA) levels. Chronically increased plasma FFA stimulates gluconeogenesis, induces hepatic and muscle insulin resistance, and impairs insulin secretion in genetically predisposed individuals. These FFA-induced disturbances are referred to as lipotoxicity. Enlarged fat cells also have diminished capacity to store fat. When adipocyte storage capacity is exceeded, lipid 'overflows' into muscle and liver, and possibly the beta-cells of the pancreas, exacerbating insulin resistance and further impairing insulin secretion. In addition, dysfunctional fat cells produce excessive amounts of insulin resistance-inducing, inflammatory and atherosclerosis-provoking cytokines, and fail to secrete normal amounts of insulin-sensitizing cytokines. As more evidence emerges, there is a stronger case for targeting adipose tissue in the treatment of type 2 diabetes. Peroxisome-proliferator activated receptor gamma (PPARgamma) agonists, for example the thiazolidinediones, redistribute fat within the body (decrease visceral and hepatic fat; increase subcutaneous fat) and have been shown to enhance adipocyte insulin sensitivity, inhibit lipolysis, reduce plasma FFA and favourably influence the production of adipocytokines. This article examines in detail the role of adipose tissue in the pathogenesis of type 2 diabetes and highlights the potential of PPAR agonists to improve the management of patients with the condition.
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Affiliation(s)
- R A DeFronzo
- Diabetes Division, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, Texas 78229, USA.
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Silswal N, Singh AK, Aruna B, Mukhopadhyay S, Ghosh S, Ehtesham NZ. Human resistin stimulates the pro-inflammatory cytokines TNF-alpha and IL-12 in macrophages by NF-kappaB-dependent pathway. Biochem Biophys Res Commun 2005; 334:1092-101. [PMID: 16039994 DOI: 10.1016/j.bbrc.2005.06.202] [Citation(s) in RCA: 424] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 06/30/2005] [Indexed: 12/18/2022]
Abstract
Resistin, a recently discovered 92 amino acid protein involved in the development of insulin resistance, has been associated with obesity and type 2 diabetes. The elevated serum resistin in human diabetes is often associated with a pro-inflammatory milieu. However, the role of resistin in the development of inflammation is not well understood. Addition of recombinant human resistin protein (hResistin) to macrophages (both murine and human) resulted in enhanced secretion of pro-inflammatory cytokines, TNF-alpha and IL-12, similar to that obtained using 5 microg/ml lipopolysaccharide. Both oligomeric and dimeric forms of hResistin were able to activate these cytokines suggesting that the inflammatory action of resistin is independent of its conformation. Heat denatured hResistin abrogated cytokine induction while treatment of recombinant resistin with polymyxin B agarose beads had no effect thereby ruling out the role of endotoxin in the recombinant hResistin mediated cytokine induction. The pro-inflammatory nature of hResistin was further evident from the ability of this protein to induce the nuclear translocation of NF-kappaB transcription factor as seen from electrophoretic mobility shift assays. Induction of TNF-alpha in U937 cells by hResistin was markedly reduced in the presence of either dominant negative IkappaBalpha plasmid or PDTC, a pharmacological inhibitor of NF-kappaB. A protein involved in conferring insulin resistance is also a pro-inflammatory molecule that has important implications.
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Affiliation(s)
- Nirupama Silswal
- Molecular Biology Unit, National Institute of Nutrition (ICMR), Hyderabad 500007, India
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35
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Oh KW, Lee WY, Rhee EJ, Baek KH, Yoon KH, Kang MI, Yun EJ, Park CY, Ihm SH, Choi MG, Yoo HJ, Park SW. The relationship between serum resistin, leptin, adiponectin, ghrelin levels and bone mineral density in middle-aged men. Clin Endocrinol (Oxf) 2005; 63:131-8. [PMID: 16060905 DOI: 10.1111/j.1365-2265.2005.02312.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Body weight is a significant predictor of bone mass. Hormonal factors such as sex hormones, insulin, leptin and adiponectin are thought to play a role in the mechanisms controlling the association of body weight and fat mass with bone mass. However, contradictory results have been reported for the association between serum adipocytokines and bone mineral density (BMD). We therefore examined whether the serum adipocytokine and ghrelin levels, markers of fat metabolism, are associated with BMD in male adults. PATIENTS AND MEASUREMENTS For 80 male adults (average age 54.5 +/- 6.4 years; average body mass index (BMI) 24.4 +/- 2.5 kg/m2), the correlations between serum resistin, leptin, adiponectin and ghrelin levels with BMD were investigated. RESULTS Among the adipocytokines, serum resistin levels were negatively correlated with lumbar spine BMD (r = -0.237, P = 0.05). After adjustment was made for age and BMI, log-transformed serum leptin showed a significant negative correlation with lumbar spine BMD, which was not seen on bivariate analysis (r = -0.237, P = 0.039). Femoral neck BMD was marginally associated only with serum adiponectin levels (r = -0.226, P = 0.062). In multiple regression analyses, among the adipokines, only resistin was a significant determinant of lumbar spine BMD, although the variance was small (R2 = 0.256). Serum ghrelin levels were not correlated with the BMD of either body site. CONCLUSIONS Serum resistin level showed a significant negative correlation with lumbar spine BMD, although the variance was small. Further studies are needed to elucidate the role of adipocytokines in bone metabolism.
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Affiliation(s)
- Ki Won Oh
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Sacred Heart Hospital, Hallym University, Pyungchon-dong, Dongan-gu, Anyang-city, Kyungki-do, Chunchon, Korea.
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36
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Abstract
Resistin (Rstn) is known as an adipocyte-specific secretory factor that can cause insulin resistance and decrease adipocyte differentiation. Conversely, based on various studies, insulin-like growth factors (IGFs) can improve insulin resistance and stimulate adipocyte adipogenesis. Whether IGFs exert their effects through the control of Rstn's production or modulation of Rstn's action is unknown. This study was designed to examine the influence and the signaling of IGF-I on Rstn gene expression and protein secretion by 3T3-L1 adipocytes. We found that IGF-I suppressed Rstn mRNA expression and protein release in dose- and time-dependent manners. The IC50 of IGF-I was approximately 1 nM for a range of 6-10 h of treatment. Treatment with cycloheximide, but not with actinomycin D, prevented IGF-I-suppressed Rstn mRNA expression, suggesting that IGF-I destabilizes Rstn mRNA and that IGF-I's effect requires new protein, but not mRNA, synthesis. Pretreatment with IGF-I receptor (IGF-IR) antibody blocked IGF-I-altered IGF-IR activity and Rstn mRNA levels. Neither PD-98059, SB-203580, nor LY-294002 changed the IGF-I-decreased levels of Rstn mRNA, but they inhibited IGF-I-stimulated activities of MEK1, p38 MAPK, and phosphoinositide 3-kinase, respectively. However, SB-203580 antagonized the IGF-I-decreased Rstn protein release. These data demonstrate that IGF-I downregulates Rstn gene expression via IGF-IR-dependent and MEK1-, p38 MAPK-, and phosphoinositide 3-kinase-independent pathways and likely modifies the distribution of Rstn protein between the intracellular and extracellular compartments via a p38 MAPK-dependent pathway. Decreases in Rstn production and secretion induced by IGF-I may be related to the mechanism by which IGF-I modulates body weight and diabetes in animals.
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Affiliation(s)
- Yen-Hang Chen
- Department of Life Science, College of Science, National Central University, Chung-Li City, Taoyuan, Taiwan
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Kurlawalla-Martinez C, Stiles B, Wang Y, Devaskar SU, Kahn BB, Wu H. Insulin hypersensitivity and resistance to streptozotocin-induced diabetes in mice lacking PTEN in adipose tissue. Mol Cell Biol 2005; 25:2498-510. [PMID: 15743841 PMCID: PMC1061603 DOI: 10.1128/mcb.25.6.2498-2510.2005] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In adipose tissue, insulin controls glucose and lipid metabolism through the intracellular mediators phosphatidylinositol 3-kinase and serine-threonine kinase AKT. Phosphatase and a tensin homolog deleted from chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase/AKT pathway, is hypothesized to inhibit the metabolic effects of insulin. Here we report the generation of mice lacking PTEN in adipose tissue. Loss of Pten results in improved systemic glucose tolerance and insulin sensitivity, associated with decreased fasting insulin levels, increased recruitment of the glucose transporter isoform 4 to the cell surface in adipose tissue, and decreased serum resistin levels. Mutant animals also exhibit increased insulin signaling and AMP kinase activity in the liver. Pten mutant mice are resistant to developing streptozotocin-induced diabetes. Adipose-specific Pten deletion, however, does not alter adiposity or plasma fatty acids. Our results demonstrate that in vivo PTEN is a potent negative regulator of insulin signaling and insulin sensitivity in adipose tissue. Furthermore, PTEN may be a promising target for nutritional and/or pharmacological interventions aimed at reversing insulin resistance.
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Affiliation(s)
- Christine Kurlawalla-Martinez
- Department of Pediatrics, Division of Neonatology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA
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Yang Z, Zhang M, Xu L, Zhang J, Hongwei W. Effect of tumor necrosis factor-alpha on resistin expression in 3T3-L1 adipocytes and its mechanism. Curr Med Sci 2005; 25:121-3, 130. [PMID: 16116950 DOI: 10.1007/bf02873554] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Indexed: 10/19/2022]
Abstract
In order to investigate the effect of tumor necrosis factor-alpha (TNFalpha) on resistin expression in 3T3-L1 adipocytes, and further explore its mechanisms, the differentiated 3T3-L1 adipocytes were incubated with 0, 1, 10, 100 ng/mL TNFalpha respectively for 24 h, and then the expression of resistin was determined. The differentiated 3T3-L1 adipocytes were incubated with 100 ng/ mL TNFalpha for 3, 6, 24 h respectively, and then the expression of resistin mRNA was analyzed. 3T3-L1 adipocytes were induced to differentiate into mature adipocytes. The cells were randomly divided into 4 groups for culture. In the control group, no drugs were added. Cells of TNFalpha group were treated with 100 ng/mL TNFalpha. In Ro-31-8220 group, 5 micromol/L protein kinase C inhibitor Ro-31-8220 was added. With TNFalpha+Ro-31-8220 group, 100 ng/mL TNFalpha were added 1 h after the addition of 5 micromol/L Ro-31-8220. All adipocytes were cultured for 24 h. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were employed to detect the expression of resistin gene. Our results showed that resistin protein and mRNA in 3T3-L1 adipocytes were inhibited by TNFalpha at different concentrations (P<0.01), and the inhibitory effect increased with the concentration (P<0.01). At the same concentrations, the inhibitory effect increased with time (P <0.01). Ro-31-8220 could inhibit its expression and the inhibitive effect remained unchanged with addition of TNFalpha (P>0.05). It was concluded that TNFalpha could inhibit the expression of resistin in 3T3-L1 adipocytes. The mechanism may be that the expression of resistin is partly controlled by protein kinase C signal conduction pathway.
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Affiliation(s)
- Zaigang Yang
- Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 30030, China
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Temple KA, Cohen RN, Wondisford SR, Yu C, Deplewski D, Wondisford FE. An intact DNA-binding domain is not required for peroxisome proliferator-activated receptor gamma (PPARgamma) binding and activation on some PPAR response elements. J Biol Chem 2004; 280:3529-40. [PMID: 15572375 DOI: 10.1074/jbc.m411422200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARgamma) interacts with retinoid X receptor (RXR) on PPAR response elements (PPREs) to regulate transcription of PPAR-responsive genes. To investigate the binding of PPARgamma and RXR to PPREs, three mutations were constructed in the DNA-binding domains of PPARgamma; two of the mutants maintained the structure of zinc finger I (PPARgamma-GS and PPARgamma-AA), and a third mutation disrupted the protein structure of zinc finger I (PPARgamma-CS). Results indicated that the mutations of PPARgamma that maintained intact zinc fingers were capable of binding to a variety of PPREs in the presence of RXR and could activate transcription on several PPREs. In parallel, a mutation was created in the DNA-binding domain of RXRalpha that maintained the structure of the zinc fingers (RXR-GS) but did not bind DNA and was transcriptionally inactive. Examination of the 3' half-site of several PPREs revealed that variations from the consensus sequence reduced or abolished transcriptional activity, but conversion to consensus improved transcriptional activity with PPARgamma-GS and PPARgamma-AA. Examination of the 5' half-site indicated that the upstream three nucleotides were more important for transcriptional activity than the downstream three nucleotides. Our data demonstrated that stringent binding of RXR to the 3' half-site of a PPRE is more influential on the binding of the PPARgamma/RXR heterodimer than the ability of PPARgamma to bind DNA. Thus, unlike RXR, PPARgamma exhibits promiscuity in binding on a PPRE, suggesting that the definition of a PPRE for PPARgamma may need to be expanded.
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Affiliation(s)
- Karla A Temple
- Department of Medicine, and Committee on Molecular Metabolism and Nutrition, Pritzker School of Medicine, University of Chicago, Chicago, Illinois 60637, USA
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40
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Haugen F, Zahid N, Dalen KT, Hollung K, Nebb HI, Drevon CA. Resistin expression in 3T3-L1 adipocytes is reduced by arachidonic acid. J Lipid Res 2004; 46:143-53. [PMID: 15489540 DOI: 10.1194/jlr.m400348-jlr200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The resistin gene is expressed in adipocytes and encodes a protein proposed to link obesity and type 2 diabetes. Increased plasma FFA is associated with insulin resistance. We examined the effect of separate FFAs on the expression of resistin mRNA in cultured murine 3T3-L1 adipocytes. The FFAs tested did not increase resistin expression, whereas both arachidonic acid (AA) and eicosapentaenoic acid (EPA) reduced resistin mRNA levels. AA was by far the most potent FFA, reducing resistin mRNA levels to approximately 20% of control at 60-250 muM concentration. Selective inhibitors of cyclooxygenase-1 and of mitogen-activated protein kinase kinase counteracted AA-induced reduction in resistin mRNA levels. Transient overexpression of sterol-regulatory element binding protein-1a (SREBP-1a) activated the resistin promoter, but there was no reduction in the abundance of approximately 65 kDa mature SREBP-1 after AA exposure. Actinomycin D as well as cycloheximide abolished the AA-induced reduction of resistin mRNA levels, indicating dependence on de novo transcription and translation. Our data suggest that reductions in resistin mRNA levels involve a destabilization of the resistin mRNA molecule. An inhibitory effect of AA and EPA on resistin expression may explain the beneficial effect of ingesting PUFAs on insulin sensitivity.
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Affiliation(s)
- Fred Haugen
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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41
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Muse ED, Obici S, Bhanot S, Monia BP, McKay RA, Rajala MW, Scherer PE, Rossetti L. Role of resistin in diet-induced hepatic insulin resistance. J Clin Invest 2004. [PMID: 15254590 DOI: 10.1172/jci200421270] [Citation(s) in RCA: 243] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Resistin is an adipose-derived hormone postulated to link adiposity to insulin resistance. To determine whether resistin plays a causative role in the development of diet-induced insulin resistance, we lowered circulating resistin levels in mice by use of a specific antisense oligodeoxynucleotide (ASO) directed against resistin mRNA and assessed in vivo insulin action by the insulin-clamp technique. After 3 weeks on a high-fat (HF) diet, mice displayed severe insulin resistance associated with an approximately 80% increase in plasma resistin levels. In particular, the rate of endogenous glucose production (GP) increased more than twofold compared with that in mice fed a standard chow. Treatment with the resistin ASO for 1 week normalized the plasma resistin levels and completely reversed the hepatic insulin resistance. Importantly, in this group of mice, the acute infusion of purified recombinant mouse resistin, designed to acutely elevate the levels of circulating resistin up to those observed in the HF-fed mice, was sufficient to reconstitute hepatic insulin resistance. These results provide strong support for a physiological role of resistin in the development of hepatic insulin resistance in this model.
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Affiliation(s)
- Evan D Muse
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, New York 10461, USA
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42
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Nogueiras R, Barreiro ML, Caminos JE, Gaytán F, Suominen JS, Navarro VM, Casanueva FF, Aguilar E, Toppari J, Diéguez C, Tena-Sempere M. Novel expression of resistin in rat testis: functional role and regulation by nutritional status and hormonal factors. J Cell Sci 2004; 117:3247-57. [PMID: 15226398 DOI: 10.1242/jcs.01196] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Resistin, a recently cloned adipose-secreted factor, is primarily involved in the modulation of insulin sensitivity and adipocyte differentiation. However, additional metabolic or endocrine functions of this molecule remain largely unexplored. In this study, a series of experiments were undertaken to explore the potential expression, regulation and functional role of this novel adipocytokine in rat testis. Resistin gene expression was demonstrated in rat testis throughout postnatal development, with maximum mRNA levels in adult specimens. At this age, resistin peptide was immunodetected in interstitial Leydig cells and Sertoli cells within seminiferous tubules. Testicular expression of resistin was under hormonal regulation of pituitary gonadotropins and showed stage-specificity, with peak expression values at stages II-VI of the seminiferous epithelial cycle. In addition, testicular resistin mRNA was down-regulated by the selective agonist of PPARγ, rosiglitazone, in vivo and in vitro. Similarly, fasting and central administration of the adipocyte-derived factor, leptin, evoked a significant reduction in testicular resistin mRNA levels, whereas they remained unaltered in a model of diet-induced obesity. From a functional standpoint, resistin, in a dose-dependent manner, significantly increased both basal and choriogonadotropin-stimulated testosterone secretion in vitro. Overall, our present results provide the first evidence for the expression, regulation and functional role of resistin in rat testis. These data underscore a reproductive facet of this recently cloned molecule, which may operate as a novel endocrine integrator linking energy homeostasis and reproduction.
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Affiliation(s)
- Ruben Nogueiras
- Department of Physiology, University of Santiago de Compostela, c/San Francisco s/n, 15705, Spain
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Muse ED, Obici S, Bhanot S, Monia BP, McKay RA, Rajala MW, Scherer PE, Rossetti L. Role of resistin in diet-induced hepatic insulin resistance. J Clin Invest 2004; 114:232-9. [PMID: 15254590 PMCID: PMC449748 DOI: 10.1172/jci21270] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Accepted: 05/25/2004] [Indexed: 12/26/2022] Open
Abstract
Resistin is an adipose-derived hormone postulated to link adiposity to insulin resistance. To determine whether resistin plays a causative role in the development of diet-induced insulin resistance, we lowered circulating resistin levels in mice by use of a specific antisense oligodeoxynucleotide (ASO) directed against resistin mRNA and assessed in vivo insulin action by the insulin-clamp technique. After 3 weeks on a high-fat (HF) diet, mice displayed severe insulin resistance associated with an approximately 80% increase in plasma resistin levels. In particular, the rate of endogenous glucose production (GP) increased more than twofold compared with that in mice fed a standard chow. Treatment with the resistin ASO for 1 week normalized the plasma resistin levels and completely reversed the hepatic insulin resistance. Importantly, in this group of mice, the acute infusion of purified recombinant mouse resistin, designed to acutely elevate the levels of circulating resistin up to those observed in the HF-fed mice, was sufficient to reconstitute hepatic insulin resistance. These results provide strong support for a physiological role of resistin in the development of hepatic insulin resistance in this model.
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Affiliation(s)
- Evan D Muse
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, New York 10461, USA
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Affiliation(s)
- Rustam Rea
- School of Medical and Surgical Sciences, Centre for Integrated Systems Biology and Medicine, University of Nottingham, UK
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Abstract
This work identifies retinoic acid (RA), the acid form of vitamin A, as a signal that inhibits the expression of resistin, an adipocyte-secreted protein previously proposed to act as an inhibitor of adipocyte differentiation and as a systemic insulin resistance factor. Both 9-cis and all-trans RA reduced resistin mRNA levels in white and brown adipocyte cell model systems; the effect was time- and dose-dependent, was followed by a reduced secretion of resistin, and was reproduced by selective agonists of both RA receptors and rexinoid receptors. Association of CCAAT/enhancer-binding protein alpha (a positive regulator of the resistin gene) and its coactivators p300, cAMP response element-binding protein binding protein, and retinoblastoma protein with the resistin gene promoter was reduced in RA-treated adipocytes. RA administration to normal mice resulted in reduced resistin mRNA levels in brown and white adipose tissues, reduced circulating resistin levels, reduced body weight, and improved glucose tolerance. Resistin expression was also downregulated after dietary vitamin A supplementation in mice. The results raise the possibility that vitamin A status may contribute to modulate systemic functions through effects on the production of adipocyte-derived protein signals.
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Affiliation(s)
- Francisco Felipe
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Department of Fundamental Biology and Health Sciences, University of the Balearic Islands, Palma de Mallorca, Spain
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Pakala R, Kuchulakanti P, Rha SW, Cheneau E, Baffour R, Waksman R. Peroxisome proliferator-activated receptor γ: Its role in metabolic syndrome. ACTA ACUST UNITED AC 2004; 5:97-103. [PMID: 15464947 DOI: 10.1016/j.carrad.2004.03.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2004] [Revised: 03/25/2004] [Accepted: 03/25/2004] [Indexed: 10/26/2022]
Abstract
Here we review PPARgamma function in relation to human adipogenesis, insulin sensitization, lipid metabolism, blood pressure regulation and prothrombotic state to perhaps provide justification for this nuclear receptor remaining a key therapeutic target for the continuing development of agents to treat human metabolic syndrome.
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Affiliation(s)
- Rajbabu Pakala
- Cardiovascular Research Institute, Washington Hospital Center, 110 Irving Street NW, Suite 4B-1, Washington, DC 20010, USA
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Abstract
Obesity and noninsulin-dependent diabetes mellitus are globally epidemic. Insulin resistance is a major contributor to the pathogenesis of type II diabetes and plays a role in numerous other metabolic disorders including hypertension, dyslipidaemia and atherosclerosis. Obesity, in particular visceral adiposity, is positively correlated with insulin resistance. Although this correlation between adiposity and insulin resistance is well established in human beings as well as in rodent models, the mechanisms involved in obesity-related insulin resistance are not fully defined. One mechanism is that factors secreted from adipocytes can affect peripheral insulin resistance. One candidate for such a factor is resistin, an adipocyte-secreted hormone that impairs glucose homeostasis and insulin action in the mouse. This review will summarize our current understanding of resistin and will attempt to provide a framework for future study of its role in rodent and human physiology.
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Affiliation(s)
- Claire M Steppan
- Division of Endocrinology, Diabetes, and Metabolism, Departments of Medicine and Genetics, and The Penn Diabetes Center, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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Bays H, Mandarino L, DeFronzo RA. Role of the adipocyte, free fatty acids, and ectopic fat in pathogenesis of type 2 diabetes mellitus: peroxisomal proliferator-activated receptor agonists provide a rational therapeutic approach. J Clin Endocrinol Metab 2004; 89:463-78. [PMID: 14764748 DOI: 10.1210/jc.2003-030723] [Citation(s) in RCA: 435] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Harold Bays
- Diabetes Division, University of Texas Health Science Center, San Antonio, Texas 78229, USA
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Affiliation(s)
- K Motojima
- Department of Biochemistry, Meiji Pharmaceutical University, Kiyose, Tokyo, Japan.
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Minn AH, Patterson NB, Pack S, Hoffmann SC, Gavrilova O, Vinson C, Harlan DM, Shalev A. Resistin is expressed in pancreatic islets. Biochem Biophys Res Commun 2003; 310:641-5. [PMID: 14521959 DOI: 10.1016/j.bbrc.2003.09.061] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Resistin, a recently described adipocyte factor, is regulated by peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. While resistin has been proposed to mediate insulin resistance in rodents, little is known about human resistin and its expression in pancreatic islets has not been tested. The goal of the present study was therefore to analyze whether resistin, like PPARgamma, is expressed in islets. Human islets from seven donors were analyzed by quantitative RT-PCR revealing resistin expression in all samples. Immunohistochemistry using a resistin-specific antibody on human pancreatic sections localized resistin protein to the islets. Mouse resistin was also detected in the Min6 beta cell line. Interestingly, we found a 4-fold increase in islet resistin expression in insulin resistant A-ZIP transgenic compared to wild-type mice. Our results demonstrate that resistin is expressed in islets and up-regulated in insulin resistance and thereby shed new light on the role of resistin in mice and humans.
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Affiliation(s)
- Alexandra H Minn
- Endocrinology Section, Department of Medicine, University of Wisconsin, Madison, WI 53792, USA
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