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Hatano Y, Sawayama N, Miyashita H, Kurashina T, Okada K, Takahashi M, Matsumoto M, Hoshide S, Sasaki T, Nagashima S, Ebihara K, Mori H, Kario K, Ishibashi S. Sex-specific association of primary aldosteronism with visceral adiposity. J Endocr Soc 2022; 6:bvac098. [PMID: 35822200 PMCID: PMC9268741 DOI: 10.1210/jendso/bvac098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Indexed: 11/19/2022] Open
Abstract
Context The association between primary aldosteronism and obesity, especially its sex difference, remains unknown. Objective To assess the association for each subtype of primary aldosteronism with obesity parameters including visceral adipose tissue and differences between sexes. Methods In this case-control study, 4 normotensive controls were selected for each case with primary aldosteronism. Multivariable conditional logistic regression models were used to estimate the association between each type of primary aldosteronism and obesity indicators. We used a random forest to identify which visceral or subcutaneous tissue areas had a closer association with disease status. Results The study subjects included 42 aldosterone-producing adenoma cases (22 women) and 68 idiopathic hyperaldosteronism cases (42 women). In multivariable conditional logistic regressions, aldosterone-producing adenoma was significantly associated with body mass index only in men (odds ratio [OR] [95% CI)], 4.62 [1.98-10.80] per 2.89 kg/m2) but not in women (OR [95% CI], 1.09 [0.69-1.72] per 3.93 kg/m2) compared with the matched controls, whereas idiopathic hyperaldosteronism was associated with body mass index in both men (OR [95% CI], 3.96 [2.03-7.73] per 3.75 kg/m2) and women (OR [95% CI], 2.65 [1.77-3.96] per 3.85 kg/m2) compared with the matched controls. In random forests, visceral adipose tissue areas were the better predictor of both aldosterone-producing adenoma and idiopathic hyperaldosteronism than subcutaneous adipose tissue. Conclusions Aldosterone-producing adenoma cases were obese among men, but not among women. Idiopathic hyperaldosteronism cases were obese among both men and women. Visceral adipose tissue may contribute to the pathophysiology of primary aldosteronism.
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Affiliation(s)
- Yu Hatano
- Department of Family Medicine and Community Health, Duke University, 2200 West Main Street , Durham, NC, 27705 USA
| | - Nagisa Sawayama
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Hiroshi Miyashita
- Jichi Medical University Health Care Center, 2-35 Gion, Shimotsuke-shi , Tochigi-ken 329-0493, Japan
| | - Tomoyuki Kurashina
- School of Nursing, Jichi Medical University, 3311-1 Yakushiji , Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Kenta Okada
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Manabu Takahashi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Masatoshi Matsumoto
- Department of Community-Based Medical System, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku , Hiroshima 734-8551, Japan
| | - Satoshi Hoshide
- Division of Cardiology, Department of Internal Medicine, Jichi Medial University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Takahiro Sasaki
- Department of Radiology, Jichi Medial University, 3311-1 Yakushiji , Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Shuichi Nagashima
- Department of Endocrinology and Metabolism, Jichi Medical University Saitama Medical center, 1-847 Amanumacho , Omiya-ku, Saitama-shi, Saitama-ken 330-8503, Japan
| | - Ken Ebihara
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Harushi Mori
- Department of Radiology, Jichi Medial University, 3311-1 Yakushiji , Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Kazuomi Kario
- Division of Cardiology, Department of Internal Medicine, Jichi Medial University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Jichi Medical University , 3311-1 Yakushiji, Shimotsuke-shi, Tochigi-ken 329-0498, Japan
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Dixit G, Prabhu A. The pleiotropic peroxisome proliferator activated receptors: Regulation and therapeutics. Exp Mol Pathol 2021; 124:104723. [PMID: 34822814 DOI: 10.1016/j.yexmp.2021.104723] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/02/2021] [Accepted: 11/15/2021] [Indexed: 02/07/2023]
Abstract
The Peroxisome proliferator-activated receptors (PPARs) are key regulators of metabolic events in our body. Owing to their implication in maintenance of homeostasis, both PPAR agonists and antagonists assume therapeutic significance. Understanding the molecular mechanisms of each of the PPAR isotypes in the healthy body and during disease is crucial to exploiting their full therapeutic potential. This article is an attempt to present a rational analysis of the multifaceted therapeutic effects and underlying mechanisms of isotype-specific PPAR agonists, dual PPAR agonists, pan PPAR agonists as well as PPAR antagonists. A holistic understanding of the mechanistic dimensions of these key metabolic regulators will guide future efforts to identify novel molecules in the realm of metabolic, inflammatory and immunotherapeutic diseases.
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Affiliation(s)
- Gargi Dixit
- Department of Pharmaceutical Chemistry & Quality Assurance, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mumbai, India
| | - Arati Prabhu
- Department of Pharmaceutical Chemistry & Quality Assurance, SVKM's Dr. Bhanuben Nanavati College of Pharmacy, Mumbai, India.
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Andrews FV, Kim SM, Edwards L, Schlezinger JJ. Identifying adipogenic chemicals: Disparate effects in 3T3-L1, OP9 and primary mesenchymal multipotent cell models. Toxicol In Vitro 2020; 67:104904. [PMID: 32473317 DOI: 10.1016/j.tiv.2020.104904] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/18/2020] [Accepted: 05/22/2020] [Indexed: 12/19/2022]
Abstract
3T3-L1 pre-adipocytes are used commonly to identify new adipogens, but this cell line has been shown to produce variable results. Here, potential adipogenic chemicals (identified in the ToxCast dataset using the Toxicological Priority Index) were tested for their ability to induce adipocyte differentiation in 3T3-L1 cells, OP9 cells and primary mouse bone marrow multipotent stromal cells (BM-MSC). Ten of the 36 potential adipogens stimulated lipid accumulation in at least one model (novel: fenthion, quinoxyfen, prallethrin, allethrin, pyrimethanil, tebuconzaole, 2,4,6-tris (tert-butyl)phenol; known: fentin, pioglitazone, 3,3',5,5'-tetrabromobisphenol A). Only prallethrin and pioglitazone enhanced lipid accumulation in all models. OP9 cells were significantly more sensitive to chemicals known to activate PPARγ through RXR than the other models. Coordinate effects on adipocyte and osteoblast differentiation were investigated further in BM-MSCs. Lipid accumulation was correlated with the ability to stimulate expression of the PPARγ target gene, Plin1. Induction of lipid accumulation also was associated with reduction in alkaline phosphatase activity. Allethrin, prallethrin, and quinoxyfen strongly suppressed osteogenic gene expression. BM-MSCs were useful in coordinately investigating pro-adipogenic and anti-osteogenic effects. Overall, the results show that additional models should be used in conjunction with 3T3-L1 cells to identify a broader spectrum of adipogens and their coordinate effects on osteogenesis.
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Affiliation(s)
- Faye V Andrews
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Stephanie M Kim
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Lariah Edwards
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA
| | - Jennifer J Schlezinger
- Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA.
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4
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Ferguson D, Hutson I, Tycksen E, Pietka TA, Bauerle K, Harris CA. Role of Mineralocorticoid Receptor in Adipogenesis and Obesity in Male Mice. Endocrinology 2020; 161:bqz010. [PMID: 32036385 PMCID: PMC7007880 DOI: 10.1210/endocr/bqz010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 10/30/2019] [Indexed: 02/07/2023]
Abstract
Increased visceral adiposity and hyperglycemia, 2 characteristics of metabolic syndrome, are also present in conditions of excess glucocorticoids (GCs). GCs are hormones thought to act primarily via the glucocorticoid receptor (GR). GCs are commonly prescribed for inflammatory disorders, yet their use is limited due to many adverse metabolic side effects. In addition to GR, GCs also bind the mineralocorticoid receptor (MR), but there are many conflicting studies about the exact role of MR in metabolic disease. Using MR knockout mice (MRKO), we find that both white and brown adipose depots form normally when compared with wild-type mice at P5. We created mice with adipocyte-specific deletion of MR (FMRKO) to better understand the role of MR in metabolic dysfunction. Treatment of mice with excess GCs for 4 weeks, via corticosterone in drinking water, induced increased fat mass and glucose intolerance to similar levels in FMRKO and floxed control mice. Separately, when fed a high-fat diet for 16 weeks, FMRKO mice had reduced body weight, fat mass, and hepatic steatosis, relative to floxed control mice. Decreased adiposity likely resulted from increased energy expenditure since food intake was not different. RNA sequencing analysis revealed decreased enrichment of genes associated with adipogenesis in inguinal white adipose of FMRKO mice. Differentiation of mouse embryonic fibroblasts (MEFs) showed modestly impaired adipogenesis in MRKO MEFs compared with wild type, but this was rescued upon the addition of peroxisome proliferator-activated receptor gamma (PPARγ) agonist or PPARγ overexpression. Collectively, these studies provide further evidence supporting the potential value of MR as a therapeutic target for conditions associated with metabolic syndrome.
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Affiliation(s)
- Daniel Ferguson
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Irina Hutson
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Eric Tycksen
- Genome Technology Access Center, McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri
| | - Terri A Pietka
- Nutrition and Geriatrics Division, Washington University School of Medicine, St. Louis, Missouri
| | - Kevin Bauerle
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Charles A Harris
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
- Department of Medicine, Veterans Affairs St Louis Healthcare System, John Cochran Division, St. Louis, Missouri
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Pinitol alleviates systemic inflammatory cytokines in human obesity by a mechanism involving unfolded protein response and sirtuin 1. Clin Nutr 2018; 37:2036-2044. [DOI: 10.1016/j.clnu.2017.09.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 07/28/2017] [Accepted: 09/11/2017] [Indexed: 01/08/2023]
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Wang X, Yu C, Feng J, Chen J, Jiang Q, Kuang S, Wang Y. Depot-specific differences in fat mass expansion in WT and ob/ob mice. Oncotarget 2018; 8:46326-46336. [PMID: 28564636 PMCID: PMC5542270 DOI: 10.18632/oncotarget.17938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 02/13/2017] [Indexed: 12/19/2022] Open
Abstract
The study was designed to investigate the cellular mechanisms underlying the differential fat expansion in different fat depots in wild type (WT) and ob/ob (OB) mice. At 6 weeks old, no differences in fat mass were found between SAT and VAT in WT mice, while O-SAT showed significantly higher weight than that of O-VAT. The average adipocyte size of SAT (~ 4133.47 μm2) was smaller than that of VAT (~ 7438.91 μm2) in OB mice. O-SAT preadipocytes gained higher triglyceride contents and higher levels of PPARγ and C/EBPα than did O-VAT preadipocytes upon in vitro differentiation. W-SAT and W-VAT displayed no significant differences in fatty acid uptake, while 1.36 fold significantly higher fatty acid uptake was found in O-SAT compared to O-VAT. Approximately 52% of the radioactivity recovered in cellular lipids was found in TAG in O-SAT, which was significantly higher than the other three adipocyte types. Significantly more radiolabelled oleic acid was β-oxidized to CO2 in adipocytes from O-VAT than that from O-SAT. ATP production was significantly lower in W-SAT compared with W-VAT, whereas no significantly ATP level was observed between O-SAT and O-VAT. Expression of UCP-1 in SAT from either WT or OB mice was significantly higher than the counterpart of VAT, which demonstrated higher uncoupled respiration and lower oxidative phosphorylation in SAT. Together, a combined increase in adipogenesis and FA uptake, and decreases in β-oxidation and ATP production, contributed to greater expansion of SAT compared to VAT in obese mice.
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Affiliation(s)
- Xinxia Wang
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
| | - Caihua Yu
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
| | - Jie Feng
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
| | - Jin Chen
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
| | - Qin Jiang
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
| | - Shihuan Kuang
- Department of Animal Sciences and Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Yizhen Wang
- College of Animal Sciences, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture, Zhejiang Provincial Laboratory of Feed and Animal Nutrition, Hangzhou, Zhejiang 310058, P. R. China
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7
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Liu LF, Craig CM, Tolentino LL, Choi O, Morton J, Rivas H, Cushman SW, Engleman EG, McLaughlin T. Adipose tissue macrophages impair preadipocyte differentiation in humans. PLoS One 2017; 12:e0170728. [PMID: 28151993 PMCID: PMC5289462 DOI: 10.1371/journal.pone.0170728] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 01/10/2017] [Indexed: 12/13/2022] Open
Abstract
AIM The physiologic mechanisms underlying the relationship between obesity and insulin resistance are not fully understood. Impaired adipocyte differentiation and localized inflammation characterize adipose tissue from obese, insulin-resistant humans. The directionality of this relationship is not known, however. The aim of the current study was to investigate whether adipose tissue inflammation is causally-related to impaired adipocyte differentiation. METHODS Abdominal subcutaneous(SAT) and visceral(VAT) adipose tissue was obtained from 20 human participants undergoing bariatric surgery. Preadipocytes were isolated, and cultured in the presence or absence of CD14+ macrophages obtained from the same adipose tissue sample. Adipocyte differentiation was quantified after 14 days via immunofluorescence, Oil-Red O, and adipogenic gene expression. Cytokine secretion by mature adipocytes cultured with or without CD14+macrophages was quantified. RESULTS Adipocyte differentiation was significantly lower in VAT than SAT by all measures (p<0.001). With macrophage removal, SAT preadipocyte differentiation increased significantly as measured by immunofluorescence and gene expression, whereas VAT preadipocyte differentiation was unchanged. Adipocyte-secreted proinflammatory cytokines were higher and adiponectin lower in media from VAT vs SAT: macrophage removal reduced inflammatory cytokine and increased adiponectin secretion from both SAT and VAT adipocytes. Differentiation of preadipocytes from SAT but not VAT correlated inversely with systemic insulin resistance. CONCLUSIONS The current results reveal that proinflammatory immune cells in human SAT are causally-related to impaired preadipocyte differentiation, which in turn is associated with systemic insulin resistance. In VAT, preadipocyte differentiation is poor even in the absence of tissue macrophages, pointing to inherent differences in fat storage potential between the two depots.
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Affiliation(s)
- Li Fen Liu
- Division of Endocrinology, Department of Medicine, Stanford University, Palo Alto, California, United States of America
| | - Colleen M. Craig
- Division of Endocrinology, Department of Medicine, Stanford University, Palo Alto, California, United States of America
| | | | - Okmi Choi
- Stanford Blood Center, Palo Alto, California, United States of America
| | - John Morton
- Department of Surgery, School of Medicine, Stanford University, Palo Alto, California, United States of America
| | - Homero Rivas
- Department of Surgery, School of Medicine, Stanford University, Palo Alto, California, United States of America
| | - Samuel W. Cushman
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Edgar G. Engleman
- Stanford Blood Center, Palo Alto, California, United States of America
- Department of Pathology, School of Medicine Stanford University, Palo Alto, California, United States of America
| | - Tracey McLaughlin
- Division of Endocrinology, Department of Medicine, Stanford University, Palo Alto, California, United States of America
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Khong JJ, McNab AA, Ebeling PR, Craig JE, Selva D. Pathogenesis of thyroid eye disease: review and update on molecular mechanisms. Br J Ophthalmol 2015; 100:142-50. [PMID: 26567024 DOI: 10.1136/bjophthalmol-2015-307399] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 10/25/2015] [Indexed: 01/07/2023]
Abstract
Orbital changes in thyroid orbitopathy (TO) result from de novo adipogenesis, hyaluronan synthesis, interstitial oedema and enlargement of extraocular muscles. Cellular immunity, with predominantly CD4+ T cells expressing Th1 cytokines, and overexpression of macrophage-derived cytokines, perpetuate orbital inflammation. Orbital fibroblasts appear to be the major effector cells. Orbital fibroblasts express both thyrotropin receptor (TSHR) and insulin-like growth factor-1 receptor (IGF-1R) at higher levels than normal fibroblasts. TSHR expression increases in adipogenesis; TSHR agonism enhances hyaluronan production. IGF-1R stimulation leads to adipogenesis, hyaluronan synthesis and production of the chemokines, interleukin (IL)-16 and Regulated on Activation, Normal T Cell Expression and Secreted, which facilitate lymphocyte trafficking into the orbit. Immune activation uses a specific CD40:CD154 molecular bridge to activate orbital fibroblasts, which secrete pro-inflammatory cytokines including IL-1β, IL-1α, IL-6, IL-8, macrophage chemoattractant protein-1 and transforming growth factor-β, to perpetuate orbital inflammation. Molecular pathways including adenylyl cyclase/cyclic adenosine monophosphate, phophoinositide 3 kinase/AKT/mammalian target of rapamycin, mitogen-activated protein kinase are involved in TO. The emergence of a TO animal model and a new generation of TSHR antibody assays increasingly point towards TSHR as the primary autoantigen for extrathyroidal orbital involvement. Oxidative stress in TO resulting from imbalances of the oxidation-reduction state provides a framework of understanding for smoking prevention, achieving euthyroidism and the use of antioxidants such as selenium. Progress has been made in the understanding of the pathogenesis of TO, which should advance development of novel therapies targeting cellular immunity, specifically the CD40:CD40 ligand interaction, antibody-producing B cells, cytokines, TSHR and IGF-1R and its signalling pathways. Further studies in signalling networks and molecular triggers leading to burnout of TO will further our understanding of TO.
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Affiliation(s)
- Jwu Jin Khong
- North West Academic Centre, The University of Melbourne, Western Hospital, St Albans, Victoria, Australia Orbital Plastics and Lacrimal Unit, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia Austin Health, Department of Surgery, University of Melbourne, Heidelberg, Victoria, Australia
| | - Alan A McNab
- Orbital Plastics and Lacrimal Unit, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia Centre of Eye Research Australia, University of Melbourne, East Melbourne, Victoria, Australia
| | - Peter R Ebeling
- North West Academic Centre, The University of Melbourne, Western Hospital, St Albans, Victoria, Australia Department of Medicine, School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Dinesh Selva
- South Australian Institute of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia
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Abstract
Obesity is associated with altered gut microbiota composition and impaired gut barrier function. These changes, together with interrelated mesenteric adipose tissue inflammation, result in increased release of pro-inflammatory cytokines, bacteria-derived factors, and lipids into the portal circulation, promoting the development of (hepatic) insulin resistance. Herein, the potential impact of obesity-related changes in gut and visceral adipose tissue biology on the development of insulin resistance and Type 2 diabetes is reviewed.
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Affiliation(s)
- Daniel Konrad
- Department of Pediatric Endocrinology and Diabetology, University Children's Hospital, Zurich, Switzerland; Children's Research Center, University Children's Hospital, Zurich, Switzerland; and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Stephan Wueest
- Department of Pediatric Endocrinology and Diabetology, University Children's Hospital, Zurich, Switzerland; Children's Research Center, University Children's Hospital, Zurich, Switzerland; and
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Lessard J, Laforest S, Pelletier M, Leboeuf M, Blackburn L, Tchernof A. Low abdominal subcutaneous preadipocyte adipogenesis is associated with visceral obesity, visceral adipocyte hypertrophy, and a dysmetabolic state. Adipocyte 2014; 3:197-205. [PMID: 25068086 PMCID: PMC4110096 DOI: 10.4161/adip.29385] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 11/28/2022] Open
Abstract
Subcutaneous adipose tissue expansion through adipogenesis is increasingly recognized as a major determinant of body fat distribution and obesity-related cardiometabolic alterations. Our objective was to assess whether adipogenic rates of cultured human primary preadipocytes from the visceral and subcutaneous compartments relate to visceral obesity and cardiometabolic alterations. We recruited 35 women undergoing gynecological surgery and assessed body fat distribution by CT as well as fasting plasma lipids and glycemia. Fat samples from the greater omentum and abdominal subcutaneous (SC) compartments were used to assess mature adipocyte cell size and establish primary preadipocyte cultures. Differentiation was induced using adipogenic media and adipogenic rates were assessed using Oil Red O (ORO) absorbance/DNA content ratio and glyceraldehyde 3-phosphate dehydrogenase (G3PDH) activity/DNA of differentiated cells. We found a lower adipogenic capacity of omental (OM) preadipocytes than SC preadipocytes originating from the same women (P < 0.05). Whereas only OM cell size was different among groups of low vs high OM adipogenic rate, SC adipogenic rates were clearly related to increased OM cell size and dyslipidemia when women were separated on median value of either ORO/DNA or G3PDH activity/DNA ratios. When matched for BMI, women with low SC preadipocyte adipogenic rates had a higher visceral adipose tissue area (P < 0.01), omental adipocyte hypertrophy (P < 0.05), higher VLDL-lipid content (P < 0.01) and higher fasting glycemia (P < 0.05) than those with low SC adipogenic rates. In conclusion, low abdominal subcutaneous preadipocyte differentiation capacity in vitro is associated with visceral obesity, visceral adipocyte hypertrophy, and a dysmetabolic state.
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11
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Yu J, Kong X, Liu J, Lv Y, Sheng Y, Lv S, Di W, Wang C, Zhang F, Ding G. Expression profiling of PPARγ-regulated microRNAs in human subcutaneous and visceral adipogenesis in both genders. Endocrinology 2014; 155:2155-65. [PMID: 24666251 DOI: 10.1210/en.2013-2105] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Clinical evidence shows that visceral fat accumulation decreases whereas sc fat increases in patients treated with thiazolidinediones (TZDs), a type of peroxisome proliferator-activated receptor (PPAR)γ agonist. To clarify the molecular mechanism of the differential effects of PPARγ agonists on sc and visceral adipose, we investigated expression profiling of PPARγ-regulated micro-RNAs (miRNAs) using miRNA microarray. The level of 182 miRNAs changed in human sc adipose treated with pioglitazone, whereas only 46 miRNAs changed in visceral adipose. Among these miRNAs, 27 miRNAs changed in both human sc and visceral adipocytes. Specifically, 7 miRNAs changed at the same direction in sc and visceral adipocytes, whereas 20 miRNAs changed at opposite directions in these two fat depots. Bioinformatics analysis showed that these miRNAs and the predicted target genes were involved in TGF-β-, Wnt/β-catenin-, and insulin-signaling pathways and related to metabolic regulation or cell cycle. Among the miRNAs changed at the same direction in sc and visceral adipocytes, miR-378, located in the first intron of PPARγ coactivator 1β (PGC1β), was coordinately expressed with PGC1β during adipogenesis. Moreover, miR-378 and PGC1β were both up-regulated by PPARγ agonist. We also provided evidence that miR-378 promoted adipogenesis in sc fat, but not in visceral fat. These results display miRNAs expression profiling altered in sc and visceral adipogenesis regulated by PPARγ and suggest a potential mechanism underlying the differential effects of TZDs on the 2 fat depot accumulations.
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Affiliation(s)
- Jing Yu
- Department of Geratology (J.Y., X.K., J.L., Y.L., Y.S., S.L., W.D., C.W., G.D.) and Department of General Surgery (F.Z.), the First Hospital Affiliated to Nanjing Medical University, Nanjing, People's Republic of China
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Fat depot-specific differences in pref-1 gene expression and adipocyte cellularity between Wagyu and Holstein cattle. Biochem Biophys Res Commun 2014; 445:310-3. [DOI: 10.1016/j.bbrc.2014.01.177] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 01/28/2014] [Indexed: 11/22/2022]
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Cignarelli A, Giorgino F, Vettor R. Pharmacologic agents for type 2 diabetes therapy and regulation of adipogenesis. Arch Physiol Biochem 2013; 119:139-50. [PMID: 23724947 DOI: 10.3109/13813455.2013.796996] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The close link between type 2 diabetes and excess body weight highlights the need to consider the effects on weight of different treatments used for correction of hyperglycaemia. Indeed, specific currently available diabetes therapies can cause weight gain, including insulin and its analogues, sulphonylureas, and thiazolidinediones, while others, such as metformin and the GLP-1 receptor agonists, can promote weight loss. Excess body weight in patients with diabetes is largely due to expansion of adipose tissue, and these drugs could interfere with the mechanisms underlying the expansion and differentiation of adipocyte precursors. Almost all anti-diabetes drugs could also potentially affect adipocyte metabolism directly, by modulating lipogenesis, lipolysis, and fat oxidation. This review will examine the available evidence for specific effects of various anti-diabetes drugs on adipose tissue development and function with the ultimate goal of increasing our understanding of how pharmacological agents can modulate energy balance and body fat.
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Affiliation(s)
- A Cignarelli
- Department of Emergency and Organ Transplantation, Section of Internal Medicine, Endocrinology, Andrology, and Metabolic Diseases, University of Bari "Aldo Moro" , Bari , Italy and
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Harada E, Mizuno Y, Katoh D, Kashiwagi Y, Morita S, Nakayama Y, Yoshimura M, Masuzaki H, Saito Y, Yasue H. Increased urinary aldosterone excretion is associated with subcutaneous not visceral, adipose tissue area in obese individuals: a possible manifestation of dysfunctional subcutaneous adipose tissue. Clin Endocrinol (Oxf) 2013; 79:510-6. [PMID: 23106315 DOI: 10.1111/cen.12083] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 10/19/2012] [Accepted: 10/20/2012] [Indexed: 12/31/2022]
Abstract
BACKGROUND Aldosterone is reported to be associated with obesity and is a risk factor for metabolic syndrome. Metabolic abnormalities are more strongly associated with visceral adipose tissue (VAT) than with subcutaneous adipose tissue (SAT). OBJECTIVE We examined whether aldosterone is more closely associated with VAT area than with SAT area in obese individuals. METHODS We enrolled 81 Japanese patients (46 men, mean age 43 ± 13 years and 35 women, mean age 53 ± 10 years) suspected of metabolic disorders and measured plasma and 24-h urinary aldosterone, as well as SAT and VAT areas. SAT and VAT areas were measured at the umbilical level by computed tomography. RESULTS Spearman's rank correlation analysis showed that urinary aldosterone was significantly and positively correlated with body mass index, waist circumference, SAT area, alanine aminotransferase, C-reactive protein, plasma immune-reactive insulin, plasma renin activity and estimated glomerular filtration rate, and negatively correlated with age and blood glucose. Urinary aldosterone was not correlated with VAT area (r = 0·013, P = 0·906). Multivariate regression analyses revealed that log SAT area, age and diastolic blood pressure were significant (P = 0·001, 0·001 and 0·032, respectively) predictors of log urinary aldosterone excretion rate. CONCLUSION Our results indicate that urinary aldosterone excretion is positively associated with SAT but not with VAT area in the middle-aged obese individuals.Urinary aldosterone is also negatively correlated with age.
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Affiliation(s)
- Eisaku Harada
- Division of Cardiovascular Medicine, Kumamoto Kinoh Hospital, Kumamoto Aging Research Institute, Kumamoto, Japan.
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15
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Ma Y, Gao H, Lin F, Chen N, Xu Y, Jiang J, Li F, Lu F, Zhao M, Shi K, Cheng N, Li J. Tissue expression, association analysis between three novel SNPs of the RXRα gene and growth traits in Chinese indigenous cattle. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s11434-013-5816-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Lessard J, Tchernof A. Depot- and obesity-related differences in adipogenesis. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/clp.12.49] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Long NM, Shasa DR, Ford SP, Nathanielsz PW. Growth and insulin dynamics in two generations of female offspring of mothers receiving a single course of synthetic glucocorticoids. Am J Obstet Gynecol 2012; 207:203.e1-8. [PMID: 22939726 DOI: 10.1016/j.ajog.2012.06.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 06/07/2012] [Accepted: 06/13/2012] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Synthetic glucocorticoid administration to women threatening preterm delivery increases neonatal survival. However, mounting evidence shows that fetal exposure to glucocorticoid levels higher than appropriate for current maturation adversely programs offspring development. We examined fetal synthetic glucocorticoid multigenerational metabolic effects on F1 and F2 female offspring. STUDY DESIGN At 0.7 gestation, pregnant F0 ewes received 4 injections of dexamethasone (2 mg, approximately 60 ug.kg(-1) day(-1) 12 hours apart) or saline (control). F1 female offspring were bred to produce F2 female offspring. Postpubertal pancreatic β-cell function was tested in F1 and F2 by intravenous glucose tolerance test. RESULTS F1 and F2 ewe lambs showed reduced birthweight and morphometrics, and similar increased fasting glucose and decreased intravenous glucose tolerance test β-cell response. CONCLUSION This is the first demonstration of multigenerational programming of later life β-cell response by clinically relevant doses of synthetic glucocorticoid indicating the need for study of long-term effects of fetal exposure to synthetic glucocorticoid.
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Affiliation(s)
- Nathan M Long
- The Center for the Study of Fetal Programming, Laramie, WY, USA
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The SGBS cell strain as a model for the in vitro study of obesity and cancer. Clin Transl Oncol 2012; 14:774-82. [PMID: 22855155 DOI: 10.1007/s12094-012-0863-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 12/26/2011] [Indexed: 12/15/2022]
Abstract
INTRODUCTION The murine adipocyte cell line 3T3-L1 is well characterised and used widely, while the human pre-adipocyte cell strain, Simpson-Golabi-Behmel Syndrome (SGBS), requires validation for use in human studies. Obesity is currently estimated to account for up to 41 % of the worldwide cancer burden. A human in vitro model system is required to elucidate the molecular mechanisms for this poorly understood association. This work investigates the relevance of the SGBS cell strain for obesity and cancer research in humans. MATERIALS AND METHODS Pre-adipocyte 3T3-L1 and SGBS were differentiated according to standard protocols. Morphology was assessed by Oil Red O staining. Adipocyte-specific gene expression was measured by qPCR and biochemical function was assessed by glycerol-3-phosphate dehydrogenase (GPDH) enzyme activity. Differential gene expression in oesophageal adenocarcinoma cell line OE33 following co-culture with SGBS or primary omental human adipocytes was investigated using Human Cancer Profiler qPCR arrays. RESULTS During the process of differentiation, SGBS expressed higher levels of adipocyte-specific transcripts and fully differentiated SGBS expressed more similar morphology, transcript levels and biochemical function to primary omental adipocytes, relative to 3T3-L1. Co-culture with SGBS or primary omental adipocytes induced differential expression of genes involved in adhesion (ITGB3), angiogenesis (IGF1, TEK, TNF, VEGFA), apoptosis (GZMA, TERT) and invasion and metastasis (MMP9, TIMP3) in OE33 tumour cells. CONCLUSIONS Comparable adipocyte-specific gene expression, biochemical function and a shared induced gene signature in co-cultured OE33 cells indicate that SGBS is a relevant in vitro model for obesity and cancer research in humans.
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Pruimboom-Brees IM, Francone O, Pettersen JC, Kerlin RL, Will Y, Amacher DE, Boucher GG, Morton D. The development of subcutaneous sarcomas in rodents exposed to peroxisome proliferators agonists: hypothetical mechanisms of action and de-risking attitude. Toxicol Pathol 2012; 40:810-8. [PMID: 22504321 DOI: 10.1177/0192623312441406] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) represent therapeutic targets for the management of type 2 diabetes mellitus and dyslipidemia. Rodent carcinogenicity studies have revealed a link between γ and dual γ/α PPAR agonist treatment and the increased incidence of subcutaneous (SC) liposarcomas/fibrosarcomas or hemangiosarcomas, but very little has been reported for potent and selective PPARα agonists. We present a mode of action framework for the development of SC mesenchymal tumors in rodents given PPAR agonists. (1) Tumor promotion results from pharmacologically mediated recruitment (proliferation and differentiation), thermogenesis and adipogenesis of stromovascular cells, and subsequent generation of oxidative free radicals. (2) Tumor initiation consists of chemotype-driven mitochondrial dysfunction causing uncontrolled oxidative stress and permanent DNA damage. Promotion is characterized by enhanced adipogenesis in the SC adipose tissue, where the baseline PPARγ expression and responsiveness to PPARγ ligands is the highest, and by thermogenesis through expression of the uncoupling protein 1 (UCP-1) and the PPARγ co-activator 1 α (PGC-1α), two factors more highly expressed in brown versus white adipose tissue. Initiation is supported by the demonstration of mitochondrial uncoupling and OXPHOS Complexes dysfunction (Complexes III, IV and V) by compounds associated with increased incidences of sarcomas (muraglitazar and troglitazone), but not others lacking malignant tumor effects (pioglitazone, rosiglitazone).
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Teng YW, Ellis JM, Coleman RA, Zeisel SH. Mouse betaine-homocysteine S-methyltransferase deficiency reduces body fat via increasing energy expenditure and impairing lipid synthesis and enhancing glucose oxidation in white adipose tissue. J Biol Chem 2012; 287:16187-98. [PMID: 22362777 DOI: 10.1074/jbc.m111.303255] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Betaine-homocysteine S-methyltransferase (BHMT) catalyzes the synthesis of methionine from homocysteine. In our initial report, we observed a reduced body weight in Bhmt(-/-) mice. We initiated this study to investigate the potential role of BHMT in energy metabolism. Compared with the controls (Bhmt(+/+)), Bhmt(-/-) mice had less fat mass, smaller adipocytes, and better glucose and insulin sensitivities. Compared with the controls, Bhmt(-/-) mice had increased energy expenditure, with no changes in food intake, fat uptake or absorption, or in locomotor activity. The reduced adiposity in Bhmt(-/-) mice was not due to hyperthermogenesis. Bhmt(-/-) mice failed to maintain a normal body temperature upon cold exposure because of limited fuel supplies. In vivo and ex vivo tests showed that Bhmt(-/-) mice had normal lipolytic function. The rate of (14)C-labeled fatty acid incorporated into [(14)C]triacylglycerol was the same in Bhmt(+/+) and Bhmt(-/-) gonadal fat depots (GWAT), but it was 62% lower in Bhmt(-/-) inguinal fat depots (IWAT) compared with that of Bhmt(+/+) mice. The rate of (14)C-labeled fatty acid oxidation was the same in both GWAT and IWAT from Bhmt(+/+) and Bhmt(-/-) mice. At basal level, Bhmt(-/-) GWAT had the same [(14)C]glucose oxidation as did the controls. When stimulated with insulin, Bhmt(-/-) GWAT oxidized 2.4-fold more glucose than did the controls. Compared with the controls, the rate of [(14)C]glucose oxidation was 2.4- and 1.8-fold higher, respectively, in Bhmt(-/-) IWAT without or with insulin stimulus. Our results show for the first time a role for BHMT in energy homeostasis.
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Affiliation(s)
- Ya-Wen Teng
- Department of Nutrition, School of Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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Hammes TO, Costa CDS, Rohden F, Margis R, de Almeida JC, Padoin AV, Mottin CC, Guaragna RM. Parallel down-regulation of FOXO1, PPARγ and adiponectin mRNA expression in visceral adipose tissue of class III obese individuals. Obes Facts 2012; 5:452-9. [PMID: 22797373 DOI: 10.1159/000339574] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 11/23/2011] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVE Adipose tissue is responsible for secretion of several cytokines that mediate systemic effects on obesity and insulin resistance. Subcutaneous abdominal adipose tissue (SAT) and visceral adipose tissue (VAT) are metabolically different and have differences in their gene expression profile. Our study evaluated the expression of adiponectin, FOXO1, PPARγ, and SIRT1 in VAT and SAT of non-obese and class III obese subjects. METHODS The adipose tissue samples were obtained by surgery. Reverse transcripts of studied genes were determined by quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS Comparing the different lipid depots, adiponectin expression was lower only in VAT of obese individuals (p = 0.043); FOXO1 and PPARγ levels were decreased in VAT of both groups. When non-obese and obese were compared, only adiponectin expression was lower in SAT and in VAT of obese subjects (p = 0.004 and p = 0.002, respectively). No difference was found with regard to SIRT1 levels in VAT or SAT in both groups. FOXO1 expression in SAT of obese subjects had a negative correlation with age (r = -0.683; p = 0.029) and triglyceride serum levels (r = -0.794; p = 0.006). CONCLUSION The decrease mRNA expression of this genes in VAT, responsible for central adiposity, may be associated with an increased risk of obesity and co-morbidities.
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Wagner IV, Perwitz N, Drenckhan M, Lehnert H, Klein J. Cannabinoid type 1 receptor mediates depot-specific effects on differentiation, inflammation and oxidative metabolism in inguinal and epididymal white adipocytes. Nutr Diabetes 2011; 1:e16. [PMID: 23455155 PMCID: PMC3303536 DOI: 10.1038/nutd.2011.12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Objective: The endocannabinoid system is a major component in the control of energy metabolism. Cannabinoid 1 (CB1)-receptor blockade induces weight loss and reduces the risk to develop the metabolic syndrome with its associated cardiovascular complications. These effects are mediated by central and peripheral pathways. Interestingly, weight loss is mainly achieved by a reduction of visceral fat mass. We analyzed fat depot-specific differences on adipocyte differentiation, inflammation and oxidative metabolism in CB1-receptor knockout cells. Materials and methods: We used newly generated epididymal/inguinal adipose cell lines from CB1-receptor knockout mice. Differences in differentiation were measured by fat-specific Oil Red O staining and quantitative analysis of key differentiation markers. Induction of apoptosis was evaluated by cell death detection and investigation of p53 phosphorylation. Inflammation markers were quantified by real-time PCR. For analyzing the process of transdifferentiation we measured oxygen consumption and mitochondrial biogenesis. Results: Differentiation was reduced in visceral adipocytes from CB1-receptor knockout mice as compared with wild-type controls. Moreover, we found an induction of apoptosis in these cells. In contrast, subcutaneous adipocytes from CB1-receptor knockout mice showed an accelerated differentiation and a reduced rate of apoptosis. Inflammation was increased in visceral fat cells, as analyzed by the expression pattern of interleukin-6, monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-α, whereas in subcutaneous adipocytes these markers were decreased. Furthermore, subcutaneous CB1-receptor knockout cells were more sensitive toward a conversion into a brown fat phenotype. Uncoupling protein-1 as well as PGC-1α expression was significantly elevated. This was accompanied by an increase in mitochondrial biogenesis and oxygen consumption. Conclusion: In conclusion, we found depot-specific effects on differentiation, apoptosis, inflammation and oxidative metabolism in CB1-receptor knockout cells. Thus, CB1-receptor-mediated pathways differentially target adipose tissue depots to a dual effect that minimizes cardiometabolic risk, on the one hand, by diminishing visceral fat, and that enhances thermogenesis in subcutaneous adipocytes, on the other.
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Affiliation(s)
- I V Wagner
- Department of Internal Medicine I, University of Luebeck, Luebeck, Germany
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Wada T, Ihunnah CA, Gao J, Chai X, Zeng S, Philips BJ, Rubin JP, Marra KG, Xie W. Estrogen sulfotransferase inhibits adipocyte differentiation. Mol Endocrinol 2011; 25:1612-23. [PMID: 21816900 DOI: 10.1210/me.2011-1089] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The estrogen sulfotransferase (EST) is a phase II drug-metabolizing enzyme known to catalyze the sulfoconjugation of estrogens. EST is highly expressed in the white adipose tissue of male mice, but the role of EST in the development and function of adipocytes remains largely unknown. In this report, we showed that EST played an important role in adipocyte differentiation. EST was highly expressed in 3T3-L1 preadipocytes and primary mouse preadipocytes. The expression of EST was dramatically reduced in differentiated 3T3-L1 cells and mature primary adipocytes. Overexpression of EST in 3T3-L1 cells prevented adipocyte differentiation. In contrast, preadipocytes isolated from EST knockout (EST-/-) mice exhibited enhanced differentiation. The inhibitory effect of EST on adipogenesis likely resulted from the sustained activation of ERK1/2 MAPK and inhibition of insulin signaling, leading to a failure of switch from clonal expansion to differentiation. The enzymatic activity of EST was required for the inhibitory effect of EST on adipogenesis, because an enzyme-dead EST mutant failed to inhibit adipocyte differentiation. In vivo, overexpression of EST in the adipose tissue of female transgenic mice resulted in smaller adipocyte size. Taken together, our results suggest that EST functions as a negative regulator of adipogenesis.
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Affiliation(s)
- Taira Wada
- Center for Pharmacogenetics, Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Sacks HS, Fain JN, Cheema P, Bahouth SW, Garrett E, Wolf RY, Wolford D, Samaha J. Inflammatory genes in epicardial fat contiguous with coronary atherosclerosis in the metabolic syndrome and type 2 diabetes: changes associated with pioglitazone. Diabetes Care 2011; 34:730-3. [PMID: 21289232 PMCID: PMC3041217 DOI: 10.2337/dc10-2083] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine changes in gene expression in epicardial adipose tissue (EAT) associated with coronary atherosclerosis (CAD) and effects of pioglitazone therapy. RESEARCH DESIGN AND METHODS Genes were quantified by RT-PCR in EAT and thoracic subcutaneous adipose tissue (SAT) obtained during surgery in CAD patients with metabolic syndrome (MS) or type 2 diabetes and control subjects with minimal or no CAD and no MS or type 2 diabetes. RESULTS Increased expression of interleukin-1 receptor antagonist (IL-1Ra) and IL-10, a trend for higher IL-1β, and no change in peroxisome proliferator-activated receptor-γ (PPARγ) was found in EAT from MS or type 2 diabetes. Only PPARγ mRNA was reduced in SAT. Pioglitazone therapy in type 2 diabetes was associated with decreased expression of IL-1β, IL-1Ra, and IL-10 in EAT; decreased IL-10 in SAT; and increased PPARγ in SAT. CONCLUSIONS In MS and type 2 diabetes with CAD, proinflammatory and anti-inflammatory genes were differentially increased in EAT and selectively reduced in association with pioglitazone treatment.
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Affiliation(s)
- Harold S Sacks
- Department of Medicine, College of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
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Regional differences in cellular mechanisms of adipose tissue gain with overfeeding. Proc Natl Acad Sci U S A 2010; 107:18226-31. [PMID: 20921416 DOI: 10.1073/pnas.1005259107] [Citation(s) in RCA: 269] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Body fat distribution is an important predictor of the metabolic consequences of obesity, but the cellular mechanisms regulating regional fat accumulation are unknown. We assessed the changes in adipocyte size (photomicrographs) and number in response to overfeeding in upper- and lower-body s.c. fat depots of 28 healthy, normal weight adults (15 men) age 29 ± 2 y. We analyzed how these changes relate to regional fat gain (dual energy X-ray absorptiometry and computed tomography) and baseline preadipocyte proliferation, differentiation [peroxisome proliferator-activated receptor-γ2 (PPARγ2) and CCAAT/enhancer binding protein-α (C/EBPα) mRNA]), and apoptotic response to TNF-α. Fat mass increased by 1.9 ± 0.2 kg in the upper body and 1.6 ± 0.1 kg in the lower body. Average abdominal s.c. adipocyte size increased by 0.16 ± 0.06 μg lipid per cell and correlated with relative upper-body fat gain (r = 0.74, P < 0.0001). However, lower-body fat responded to overfeeding by fat-cell hyperplasia, with adipocyte number increasing by 2.6 ± 0.9 × 10(9) cells (P < 0.01). We found no depot-differences in preadipocyte replication or apoptosis that would explain lower-body adipocyte hyperplasia and abdominal s.c. adipocyte hypertrophy. However, baseline PPARγ2 and C/EBPα mRNA were higher in abdominal than femoral s.c. preadipocytes (P < 0.005 and P < 0.03, respectively), consistent with the ability of abdominal s.c. adipocytes to achieve a larger size. Inherent differences in preadipocyte cell dynamics may contribute to the distinct responses of different fat depots to overfeeding, and fat-cell number increases in certain depots in adults after only 8 wk of increased food intake.
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Yamanouchi T. Concomitant therapy with pioglitazone and insulin for the treatment of type 2 diabetes. Vasc Health Risk Manag 2010; 6:189-97. [PMID: 20407626 PMCID: PMC2856574 DOI: 10.2147/vhrm.s5838] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Indexed: 01/21/2023] Open
Abstract
To prevent hyperinsulinemia, which may cause atherosclerosis, thiazolidinediones (TZDs), also known as insulin sensitizers, are often added to the therapeutic regimen of patients with type 2 diabetes who are receiving insulin. The combination of insulin with pioglitazone, a TZD, reduces glycoated hemoglobin (HbA(1c)) by 0.6%-2.1%. The higher the HbA(1c) baseline the larger the therapeutic reduction of HbA(1c). This combination therapy has been shown to be beneficial even in lean Japanese patients with diabetes. It should be noted that such combination therapy is much more useful when the main clinical aim is lowering not postprandial, but fasting and nocturnal glycemia. The glycemic-lowering effects of pioglitazone alone occur slowly, whereas the addition of insulin to pioglitazone often shows a dramatic glucose-lowering effect. Thus, such combination therapy increases the possibility of frequent hypoglycemia within 1 to 2 months of combining the drugs. Severe hypoglycemia in patients using this therapy is rare. Patients treated with combination therapy who show a predominant reduction of glycemia often have severe edema; in 10%-20% of patients, combination therapy leads to drug-related congestive heart failure (CHF). However, this phenomenon is usually weakened if low doses of pioglitazone which are added to insulin therapy (ie, 15 mg/day or even 7.5 mg/day for women). It is well known that pioglitazone has an anti-atherosclerotic effect, although it is unclear if hyperinsulinemia induces atherogenic changes, either directly or indirectly, by the promotion of obesity. Until now, we have not confirmed whether the anti-atherosclerotic effects of pioglitazone exceed the supposed disadvantageous action of insulin when used in combination therapy. The addition of pioglitazone tends to reduce daily insulin dosages, but study findings have not been consistent. Improvement of lipid profiles has also been weak with this combination therapy. Long-term trials are needed before any conclusions can be reached concerning atherogenic effects of treatment for type 2 diabetes. Combination therapy of even small doses of pioglitazone with insulin should be primarily used for patients who achieve insufficient reduction in glycemia with insulin monotherapy.
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Affiliation(s)
- Toshikazu Yamanouchi
- Kita-Tokyo-Jueien/Department of Internal Medicine, Teikyo University, Tokyo, Japan.
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Sutanto MM, Ferguson KK, Sakuma H, Ye H, Brady MJ, Cohen RN. The silencing mediator of retinoid and thyroid hormone receptors (SMRT) regulates adipose tissue accumulation and adipocyte insulin sensitivity in vivo. J Biol Chem 2010; 285:18485-95. [PMID: 20371609 DOI: 10.1074/jbc.m110.107680] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The silencing mediator of retinoid and thyroid hormone receptors (SMRT) serves as a corepressor for nuclear receptors and other factors. Recent evidence suggests that SMRT is an important regulator of metabolism, but its role in adipocyte function in vivo remains unclear. We generated heterozygous SMRT knock-out (SMRT(+/-)) mice to investigate the function of SMRT in the adipocyte and the regulation of adipocyte insulin sensitivity. We show that SMRT(+/-) mice are normal weight on a regular diet, but develop increased adiposity on a high-fat diet (HFD). The mechanisms underlying this phenotype are complex, but appear to be due to a combination of an increased number of smaller subcutaneous adipocytes as well as decreased leptin expression, resulting in greater caloric intake. In addition, adipogenesis of mouse embryonic fibroblasts (MEFs) derived from these mice was increased. However, adipocyte insulin sensitivity, measured by insulin-induced Akt phosphorylation and insulin-mediated suppression of lipolysis, was enhanced in SMRT(+/-) adipocytes. These finding suggest that SMRT regulates leptin expression and limits the ability of fat mass to expand with increased caloric intake, but that SMRT also negatively regulates adipocyte insulin sensitivity.
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Affiliation(s)
- Maria M Sutanto
- Committee on Molecular Metabolism and Nutrition, Division of the Biological Sciences, Department of Medicine, The University of Chicago, Chicago, Illinois 60637, USA
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Abstract
Humans and other mammals have three main adipose tissue depots: visceral white adipose tissue, subcutaneous white adipose tissue and brown adipose tissue, each of which possesses unique cell-autonomous properties. In contrast to visceral adipose tissue, which can induce detrimental metabolic effects, subcutaneous white adipose tissue and brown adipose tissue have the potential to benefit metabolism by improving glucose homeostasis and increasing energy consumption. In addition, adipose tissue contains adipose-derived stem cells, which possess the ability to differentiate into multiple lineages, a property that might be of value for the repair or replacement of various damaged cell types. Adipose tissue transplantation has primarily been used as a tool to study physiology and for human reconstructive surgery. Transplantation of adipose tissue is, however, now being explored as a possible tool to promote the beneficial metabolic effects of subcutaneous white adipose tissue and brown adipose tissue, as well as adipose-derived stem cells. Ultimately, the clinical applicability of adipose tissue transplantation for the treatment of obesity and metabolic disorders will reside in the achievable level of safety, reliability and efficacy compared with other treatments.
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Affiliation(s)
- Thien T Tran
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
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Morton NM. Obesity and corticosteroids: 11beta-hydroxysteroid type 1 as a cause and therapeutic target in metabolic disease. Mol Cell Endocrinol 2010; 316:154-64. [PMID: 19804814 DOI: 10.1016/j.mce.2009.09.024] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 09/16/2009] [Accepted: 09/28/2009] [Indexed: 12/11/2022]
Abstract
The metabolic abnormalities found associated with high blood glucocorticoid levels (e.g. rare Cushing's syndrome) include insulin-resistance, visceral obesity, hypertension, dyslipidaemia and an increased risk of cardiovascular diseases. The same constellation of abnormalities is found in the highly prevalent idiopathic obesity/insulin-resistance (metabolic)-syndrome. It is now apparent that tissue-specific changes in cortisol metabolism explain these parallels rather than altered blood cortisol levels. Primary among these changes is increased intracellular glucocorticoid reactivation, catalysed by the enzyme 11beta-hydroxysteroid dehydrogenase type (HSD)-1 in obese adipose tissue. Liver, skeletal muscle, endocrine pancreas, blood vessels and leukocytes express 11beta-HSD1 and their potential role in metabolic disease is discussed. The weight of evidence, much of it gained from animal models, suggests that therapeutic inhibition of 11beta-HSD1 will be beneficial in most cellular contexts, with clinical trials supportive of this concept.
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Affiliation(s)
- Nicholas Michael Morton
- Molecular Metabolism Group after University of Edinburgh, Centre for Cardiovascular Sciences, Edinburgh, United Kingdom.
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Leyvraz C, Suter M, Verdumo C, Calmes JM, Paroz A, Darimont C, Gaillard RC, Pralong FP, Giusti V. Selective effects of PPARgamma agonists and antagonists on human pre-adipocyte differentiation. Diabetes Obes Metab 2010; 12:195-203. [PMID: 19895635 DOI: 10.1111/j.1463-1326.2009.01149.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The insulin sensitizer rosiglitazone (RTZ) acts by activating peroxisome proliferator and activated receptor gamma (PPAR gamma), an effect accompanied in vivo in humans by an increase in fat storage. We hypothesized that this effect concerns PPARgamma(1) and PPARgamma(2) differently and is dependant on the origin of the adipose cells (subcutaneous or visceral). To this aim, the effect of RTZ, the PPARgamma antagonist GW9662 and lentiviral vectors expressing interfering RNA were evaluated on human pre-adipocyte models. METHODS Two models were investigated: the human pre-adipose cell line Chub-S7 and primary pre-adipocytes derived from subcutaneous and visceral biopsies of adipose tissue (AT) obtained from obese patients. Cells were used to perform oil-red O staining, gene expression measurements and lentiviral infections. RESULTS In both models, RTZ was found to stimulate the differentiation of pre-adipocytes into mature cells. This was accompanied by significant increases in both the PPARgamma(1) and PPARgamma(2) gene expression, with a relatively stronger stimulation of PPARgamma(2). In contrast, RTZ failed to stimulate differentiation processes when cells were incubated in the presence of GW9662. This effect was similar to the effect observed using interfering RNA against PPARgamma(2). It was accompanied by an abrogation of the RTZ-induced PPARgamma(2) gene expression, whereas the level of PPARgamma(1) was not affected. CONCLUSIONS Both the GW9662 treatment and interfering RNA against PPARgamma(2) are able to abrogate RTZ-induced differentiation without a significant change of PPARgamma(1) gene expression. These results are consistent with previous results obtained in animal models and suggest that in humans PPARgamma(2) may also be the key isoform involved in fat storage.
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Affiliation(s)
- C Leyvraz
- Service of Endocrinology, Diabetology and Metabolism, University Hospital CHUV, Lausanne, Switzerland
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Hu H, Li DL, Fan L, Ren J, Wang SP, Jia B, Liu BH, Sun L, Yu XJ, Zang WJ. Involvement of volume-sensitive Cl−channels in the proliferation of human subcutaneous pre-adipocytes. Clin Exp Pharmacol Physiol 2010; 37:29-34. [DOI: 10.1111/j.1440-1681.2009.05223.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Smith U, Hammarstedt A. Antagonistic effects of thiazolidinediones and cytokines in lipotoxicity. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:377-80. [PMID: 19941972 DOI: 10.1016/j.bbalip.2009.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 11/16/2009] [Accepted: 11/16/2009] [Indexed: 01/04/2023]
Abstract
Ectopic lipid accumulation is promoted by obesity and an impaired ability to accumulate triglycerides in the subcutaneous depots. The adipose tissue is dysregulated in hypertrophic obesity, i.e., when the adipose cells have become enlarged. In some individuals, however, obesity is a consequence of a recruitment of new adipocytes, i.e., a hyperplastic obesity. This form of obesity is usually not associated with the metabolic complications and is termed "obese but metabolically normal". We here review recent findings showing that hypertrophic obesity is associated with an impaired differentiation of committed preadipocytes. This may be a primary (genetic?) event, thus leading to hypertrophic fat cells and the associated inflammation. However, it is also possible that the inflammation is a primary event allowing, in particular, TNFalpha to inhibit preadipocyte differentiation. TNFalpha, instead, promotes a partial transdifferentiation of the preadipocytes to assume a macrophage-like phenotype. PPARgamma activation promotes adipogenesis but can apparently not overcome the impaired preadipocyte differentiation seen in hypertrophic obesity.
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Affiliation(s)
- Ulf Smith
- The Lundberg Laboratory for Diabetes Research, Center of Excellence for Metabolic and Cardiovascular Research, Department of Molecular and Clinical Medicine, The Sahlgrenska Academy at the University of Gothenburg, SE-413 45 Gothenburg, Sweden.
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Zhuang XF, Zhao MM, Weng CL, Sun NL. Adipocytokines: a bridge connecting obesity and insulin resistance. Med Hypotheses 2009; 73:981-5. [PMID: 19692185 DOI: 10.1016/j.mehy.2009.05.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2009] [Revised: 05/02/2009] [Accepted: 05/12/2009] [Indexed: 11/16/2022]
Abstract
Overweight or obesity has become a critical health problem in the world. The association of obesity with type 2 diabetes mellitus (T2D) has been recognized for decades, and the major basis for this link is the ability of obesity to engender insulin resistance (IR). Adipose tissue is not only an energy depot but also an active endocrine organ. Furthermore, fat distribution in the body is important for the progress of IR. Many studies show that visceral fat is more important in relation to IR than subcutaneous fat. Circulating free fatty acids (FFAs) derived from adipocytes are elevated in many IR states and have been suggested to be a main underlying mechanism of IR in obesity-associated T2D. However, compelling evidence demonstrates that adipocytokines including several adipocyte-derived cytokines or hormones are also involved in obesity-induced IR. Therefore, we hypothesise that adipocytokines may be a bridge connecting obesity and IR, and abnormal fat depot distribution or visceral fat/subcutaneous fat ratio (V/S ratio) in obesity also could be a primer for IR. When visceral fat accumulates and V/S ratio deteriorates , just like a primer,in visceral obesity it should begin to display unhealthy effect begin to take place in the body. In addition to it, as one of physiological regulation mechanisms of the body, most of the adipocytokines from the visceral fat reduce the visceral fat volume or normalize the V/S ratio. Actually, on the contrary, with serum a change in the serum adipocytokine level and an imbalance of them in the body for a long term, it will become a pathological condition and various kinds of effects may contribute to the development of IR. If confirmed, this hypothesis may lead to the formulation of new pathogenesis and new therapeutic approaches to IR. For example, an effective slimming pill will be assessed in future on the basis of the decrease of V/S and serum adipocytokines level rather than of body weight.
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Affiliation(s)
- Xiao-Feng Zhuang
- Department of Cardiology, Peking University People's Hospital, Beijing, China
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Phillips SA, Ciaraldi TP, Oh DK, Savu MK, Henry RR. Adiponectin secretion and response to pioglitazone is depot dependent in cultured human adipose tissue. Am J Physiol Endocrinol Metab 2008; 295:E842-50. [PMID: 18664597 PMCID: PMC2575897 DOI: 10.1152/ajpendo.90359.2008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The subcutaneous (S) and visceral (V) adipose tissue (AT) depots are increasingly recognized as distinct. To test the hypothesis that depot differences exist for adiponectin, fresh and cultured human VAT and SAT from obese type 2 diabetic (T2D) and obese nondiabetic (ND) subjects was examined to determine whether differences in adiponectin content and secretion occurred as a function of depot studied, diabetic status, and response to thiazolidinedione treatment. VAT and SAT were obtained by biopsy and AT explants cultured in defined media for 7 days. Protein expression was assessed by Western blot. Adiponectin content of conditioned medium was determined by radioimmunoassay. Diabetic status had no effect on adiponectin secretion over days 0-2 of culture. In ND SAT, secretion fell over days 2-4 but was sustained at greater levels vs. T2D SAT. In both ND and T2D VAT, adiponectin secretion was low, similar to T2D SAT. Over the 7-day culture period, cellular adiponectin increased in ND SAT and VAT; it remained unchanged in T2D SAT and VAT. Pioglitazone increased adiponectin secretion and content in all SAT. Pioglitazone failed to increase adiponectin secretion from either ND or T2D VAT and increased cellular content only in ND VAT. AT depot differences exist in the secretion of adiponectin and responsiveness to thiazolidinedione treatment. These data suggest that SAT, not VAT, appears to be the major contributor to increased circulating adiponectin levels in response to pioglitazone treatment.
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Affiliation(s)
- Susan A Phillips
- Veterans Affairs San Diego Healthcare System, La Jolla, California 92161, USA.
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Walker GE, Marzullo P, Verti B, Guzzaloni G, Maestrini S, Zurleni F, Liuzzi A, Di Blasio AM. Subcutaneous abdominal adipose tissue subcompartments: potential role in rosiglitazone effects. Obesity (Silver Spring) 2008; 16:1983-91. [PMID: 19186324 DOI: 10.1038/oby.2008.326] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Abdominal visceral tissue (VAT) and subcutaneous adipose tissue (SAT), comprised of superficial-SAT (sSAT) and deep-SAT (dSAT), are metabolically distinct. The antidiabetic agents thiazolidinediones (TZDs), in addition to their insulin-sensitizing effects, redistribute SAT suggesting that TZD action involves adipose tissue depot-specific regulation. We investigated the expression of proteins key to adipocyte metabolism on differentiated first passage (P1) preadipocytes treated with rosiglitazone, to establish a role for the diverse depots of abdominal adipose tissue in the insulin-sensitizing effects of TZDs. Adipocytes and preadipocytes were isolated from sSAT, dSAT, and VAT samples obtained from eight normal subjects. Preadipocytes (P1) left untreated (U) or treated with a classic differentiation cocktail (DI) including rosiglitazone (DIR) for 9 days were evaluated for strata-specific differences in differentiation including peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and lipoprotein lipase (LPL) expression, insulin sensitivity via adiponectin and glucose transport-4 (GLUT4), glucocorticoid metabolism with 11 beta-hydroxysteroid dehydrogenase type-1 (11 beta HSD1), and alterations in the adipokine leptin. While depot-specific differences were absent with the classic differentiation cocktail, with rosiglitazone sSAT had the most potent response followed by dSAT, whereas VAT was resistant to differentiation. With rosiglitazone, universal strata effects were observed for PPAR-gamma, LPL, and leptin, with VAT in all cases expressing significantly lower basal expression levels. Clear dSAT-specific changes were observed with decreased intracellular GLUT4. Specific sSAT alterations included decreased 11 beta HSD1 whereas secreted adiponectin was potently upregulated in sSAT with respect to dSAT and VAT. Overall, the subcompartments of SAT, sSAT, and dSAT, appear to participate in the metabolic changes that arise with rosiglitazone administration.
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Affiliation(s)
- Gillian E Walker
- Laboratory of Molecular Biology, I.R.C.C.S. Istituto Auxologico Italiano, Piancavallo (VB), Italy.
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Tavares V, Hirata MH, Hirata RDC. [Peroxisome proliferator-activated receptor gamma (PPARgamma): molecular study in glucose homeostasis, lipid metabolism and therapeutic approach]. ACTA ACUST UNITED AC 2008; 51:526-33. [PMID: 17684612 DOI: 10.1590/s0004-27302007000400005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Accepted: 02/23/2007] [Indexed: 11/22/2022]
Abstract
The peroxisome proliferators-activated receptors (PPARs) are transcription factors belonging to the family of nuclear receptors that regulate glucose homeostasis, lipid metabolism and inflammation. Three proteins, encoded by distinct genes, have been identified: PPARalpha, PPARbeta and PPARgamma, which control gene expression by binding to specific response elements (PPREs) in the promoters. Recent studies suggest that activation of PPARgamma might decrease atherosclerosis progression and increase the insulin sensitivity, might be a potential therapeutic target for the treatment of a diverse array of disorders, including type 2 diabetes and dyslipidaemia. This review highlights recent studies, which have advanced our understanding of the pivotal role that this receptor plays in metabolism, with particular reference to the molecular mechanisms and therapeutic efficacy.
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Affiliation(s)
- Vladimir Tavares
- Programa de Pós-Graduação em Farmácia, Area de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes 580, 05508-900 São Paulo, SP.
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Grant AC, Ortiz-Colón G, Doumit ME, Tempelman RJ, Buskirk DD. Differentiation of bovine intramuscular and subcutaneous stromal-vascular cells exposed to dexamethasone and troglitazone. J Anim Sci 2008; 86:2531-8. [PMID: 18539836 DOI: 10.2527/jas.2008-0860] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The objectives of these experiments were to compare differentiation of bovine stromal-vascular (S-V) cells isolated from i.m. and s.c. adipose tissues in response to a glucocorticoid and a peroxisome proliferator-activated receptor gamma agonist. Stromal-vascular cells were isolated from i.m. and s.c. fat depots of 3 Angus steers and propagated in culture. Cells were exposed to differentiation media containing 0.25 microM dexamethasone (DEX), a glucocorticoid analog, and 40 microM troglitazone (TRO), a peroxisome proliferator-activated receptor gamma agonist, or both. Cells treated with DEX and TRO had greater (P < 0.02) glycerol-3-phosphate dehydrogenase activity than control cells. No interactions between DEX, TRO, and depot (P > 0.59) or depot differences (P = 0.41) in glycerol-3-phosphate dehydrogenase activity were found. Morphological assessment of adipogenic colonies showed that DEX induced a 1.8-fold increase in the percentage of adipogenic colonies (P = 0.03), whereas TRO increased the proportion of adipogenic colonies by 1.9-fold (P = 0.02) compared with those not treated with DEX or TRO, respectively. Depots had a similar percentage of adipogenic colonies (P = 0.18); however, the percentage of differentiated cells within adipogenic colonies was found to be 6.4-fold greater in s.c. isolates compared with i.m. (P < 0.001). Addition of TRO increased the proportion of differentiated cells within colonies by 10-fold compared with those of nontreated colonies (P < 0.001), whereas the percentage of differentiated cells within adipogenic colonies only tended to be increased by DEX (P = 0.10). These data indicate that bovine i.m. and s.c. S-V cells are capable of enhanced differentiation in response to DEX and TRO, and these effects were additive. Most importantly, inherent differences in the capacity to differentiate exist between adipogenic bovine i.m. and s.c. S-V cells.
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Affiliation(s)
- A C Grant
- Department of Animal Science, Michigan State University, East Lansing 48824-1225, USA
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Fontaine C, Cousin W, Plaisant M, Dani C, Peraldi P. Hedgehog signaling alters adipocyte maturation of human mesenchymal stem cells. Stem Cells 2008; 26:1037-46. [PMID: 18258719 DOI: 10.1634/stemcells.2007-0974] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Human stem cells are powerful tools by which to investigate molecular mechanisms of cell growth and differentiation under normal and pathological conditions. Hedgehog signaling, the dysregulation of which causes several pathologies, such as congenital defects and cancer, is involved in several cell differentiation processes and interferes with adipocyte differentiation of rodent cells. The present study was aimed at investigating the effect of Hedgehog pathway modulation on adipocyte phenotype using different sources of human mesenchymal cells, such as bone marrow stromal cells and human multipotent adipose-derived stem cells. We bring evidence that Hedgehog signaling decreases during human adipocyte differentiation. Inhibition of this pathway is not sufficient to trigger adipogenesis, but activation of Hedgehog pathway alters adipocyte morphology as well as insulin sensitivity. Analysis of glycerol-3-phosphate dehydrogenase activity and expression of adipocyte marker genes indicate that activation of Hedgehog signaling by purmorphamine impairs adipogenesis. In sharp contrast to reports in rodent cells, the maturation process, but not the early steps of human mesenchymal stem cell differentiation, is affected by Hedgehog activation. Hedgehog interferes with adipocyte differentiation by targeting CCAAT enhancer-binding protein alpha and peroxisome proliferator-activated receptor (PPAR) gamma2 expression, whereas PPARgamma1 level remains unaffected. Although Hedgehog pathway stimulation does not modify the total number of adipocytes, adipogenesis appears dramatically impaired, with reduced lipid accumulation, a decrease in adipocyte-specific markers, and acquisition of an insulin-resistant phenotype. This study indicates that a decrease in Hedgehog signaling is necessary but not sufficient to trigger adipocyte differentiation and unveils a striking difference in the adipocyte differentiation process between rodent and human mesenchymal stem cells.
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Affiliation(s)
- Coralie Fontaine
- Institute of Signaling, Biology, Development and Cancer, Université de Nice Sophia-Antipolis, Centre National de la Recherche Scientifique UMR6543, Nice, France
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Yamazaki Y, Kawano Y, Uebayasi M. Induction of adiponectin by natural and synthetic phenolamides in mouse and human preadipocytes and its enhancement by docosahexaenoic acid. Life Sci 2007; 82:290-300. [PMID: 18166202 DOI: 10.1016/j.lfs.2007.11.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2007] [Revised: 10/26/2007] [Accepted: 11/28/2007] [Indexed: 11/26/2022]
Abstract
Adiponectin, the adipose-derived cytokine, plays an important role in preventing metabolic syndromes. To develop new adiponectin inducers, eight species of ferulic esters and amides, and five related compounds were synthesized and tested on the stimulation of adiponectin production in mouse 3T3-L1 and normal human preadipocytes. The ferulamides with an aromatic ring in the N-substituent are very active in inducing adiponectin as compared with the known active compounds, curcumin, [6]-gingerol, and capsaicin, and furthermore the activities of these ferulamides are remarkably stronger than those of the corresponding esters or the straight chain octylamide. The most active compound, N-(2-phenylethyl)ferulamide (7), was found to activate the PPAR (peroxisome proliferator-activated receptor) gamma-RXR (retinoid X receptor) alpha heterodimeric complex in the PPRE (PPAR-responsive element)-driven luciferase reporter assay. The adiponectin production by 7 is synergistically enhanced by coaddition of a PPARgamma-specific agonist, pioglitazone (PGZ), or another PPARgamma agonist, docosahexaenoic acid (DHA), in cultured preadipocytes. The compound 7 alone did not show a statistically significant effect on the plasma adiponectin level in KK-A(y)/Ta mice, while 1% 7 in the diets significantly lowered the blood glucose and triglyceride levels and 0.3% 7 mixed with DHA oil in the diets significantly increased the adiponectin level as compared with the control. These results suggest that the present ferulamides would be useful lead compounds in developing more potent agents for treatment of metabolic syndromes through promoting the endogenous adiponectin production, and that such an activity is possibly enhanced by the coadministration with DHA.
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Affiliation(s)
- Yoshimitsu Yamazaki
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan.
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Maiorana A, Del Bianco C, Cianfarani S. Adipose Tissue: A Metabolic Regulator. Potential Implications for the Metabolic Outcome of Subjects Born Small for Gestational Age (SGA). Rev Diabet Stud 2007; 4:134-46. [PMID: 18084671 DOI: 10.1900/rds.2007.4.134] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Adipose tissue is involved in the regulation of glucose and lipid metabolism, energy balance, inflammation and immune response. Abdominal obesity plays a key role in the development of insulin resistance because of the high lipolytic rate of visceral adipose tissue and its secretion of adipocytokines. Low birth weight subjects are prone to central redistribution of adipose tissue and are at high risk of developing metabolic syndrome, type 2 diabetes and cardiovascular disease. Intrauterine adipogenesis may play a key role in the fetal origin of the pathogenesis of metabolic syndrome, type 2 diabetes and cardiovascular disease. Therefore, knowledge of the behavior of visceral adipose tissue-derived stem cells could provide a greater understanding of the metabolic risk related to intrauterine growth retardation, with potential clinical implications for the prevention of long-term metabolic alterations.
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Affiliation(s)
- Arianna Maiorana
- Rina Balducci Center of Pediatric Endocrinology, Department of Public Health and Cell Biology, Tor Vergata University, 00133-Rome, Italy
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Grant AC, Ortiz-Colòn G, Doumit ME, Buskirk DD. Optimization of in vitro conditions for bovine subcutaneous and intramuscular preadipocyte differentiation. J Anim Sci 2007; 86:73-82. [PMID: 17911240 DOI: 10.2527/jas.2007-0379] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The objective of these experiments was to develop an in vitro cell culture system for differentiation of bovine preadipocytes, which will permit examination of differences in differentiation between intramuscular (i.m.) and subcutaneous (s.c.) bovine preadipocytes. Stromal-vascular cells from bovine i.m. and s.c. adipose depots were isolated and cultured. Clonally derived s.c. preadipocytes were used to determine the ability of insulin, bovine serum lipids, octanoate, acetic acid, dexamethasone (DEX), and troglitazone (TRO) to elicit differentiation of these cells when added to serum-free medium. Addition of 10 and 20 microL/mL of a commercially available serum lipids supplement to low-glucose Dulbecco's modified Eagle's medium containing 280 nM insulin increased glycerol-3-phosphate dehydrogenase (GPDH) activity (P < 0.01). Inclusion of 1.25 to 10 microM TRO to medium containing 280 nM insulin and 20 microL/ mL serum lipids supplement also increased GPDH activity (P < 0.001) compared with 0 microM TRO. The combination of 280 nM insulin, 1 mM octanoate, and 10 mM acetic acid, with 48 h exposure to 0.25 microM DEX caused morphological differentiation in a small number of cells but did not stimulate GPDH activity (P = 0.99). When used together, 280 nM insulin, 20 microL/mL of serum lipids supplement, 40 microM TRO, and 0.25 microM DEX stimulated differentiation compared with the aforementioned treatment (P < 0.001). Omission of TRO or insulin from this medium reduced GPDH activity by 68% (P < 0.001), whereas removal of DEX tended to reduce GPDH activity (P = 0.06). Preadipocytes from s.c. (n = 3) and i.m. (n = 2) adipose tissues of 3 steers were used to determine the effects of TRO on differentiation using the established conditions. Forty to sixty microM TRO enhanced differentiation compared with 0 microM TRO (P < 0.02) in both depots. No depot differences in response to TRO were detected (P = 0.32). These data demonstrate that bovine preadipocytes are capable of differentiation in response to combinations of insulin, serum lipids, DEX, and TRO. Although TRO enhanced differentiation of bovine preadipocytes, no differential effects of TRO on the differentiation of s.c. and i.m. cells were detected.
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Affiliation(s)
- A C Grant
- Departments of Animal Science, Michigan State University, East Lansing 48824-1225, USA
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Peroxisome proliferator-activated receptor gamma agonist action of 3-methyl-1,2-cyclopentanedione. Biochim Biophys Acta Gen Subj 2007; 1770:1612-9. [PMID: 17931788 DOI: 10.1016/j.bbagen.2007.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2007] [Revised: 08/01/2007] [Accepted: 08/03/2007] [Indexed: 11/24/2022]
Abstract
Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily that plays a pivotal role in regulating inflammatory gene expression. The purpose of this study was to investigate the effects of coffee extract, 3-methyl-1,2-cyclopentanedione (3-MCP) on PPARs in vitro. Western blotting and luciferase assays using the PPAR response element (PPRE) construct revealed that 3-MCP induced PPARgamma-selective activation in YPEN-1 cells and that treatment with the PPARgamma selective antagonist, GW9662, was associated with a decrease in 3-MCP-induced PPARgamma activity. The 3-MCP also was shown to suppress reactive species generation and pro-inflammatory transcription factor NF-kappaB activity through PPARgamma activation. Theses results indicate that 3-MCP is a novel PPARgamma agonist and suggests that this agent may have a potential to minimize inflammation.
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Yang X, Smith U. Adipose tissue distribution and risk of metabolic disease: does thiazolidinedione-induced adipose tissue redistribution provide a clue to the answer? Diabetologia 2007; 50:1127-39. [PMID: 17393135 DOI: 10.1007/s00125-007-0640-1] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Accepted: 01/26/2007] [Indexed: 12/23/2022]
Abstract
The relative effect of visceral and subcutaneous obesity on the risk of chronic metabolic disease has been a matter of long-term dispute. While ample data support either of the fat depots being causative or associative, valid argument for one depot often automatically belittles the other. Paradigms such as the visceral/portal hypothesis and the acquired lipodystrophy/ectopic fat storage and endocrine hypothesis have been proposed. Nevertheless, neither hypothesis alone explains the entire pathophysiological setting. Treatment of diabetes with thiazolidinediones selectively increases fat partitioning to the subcutaneous adipose depot but does not change visceral fat accumulation. This is in contrast to the preferential visceral fat mobilisation by diet and exercise. Surgical removal of visceral or subcutaneous adipose tissue yields relatively long-lasting metabolic improvement only when combined with procedures that ameliorate adipose tissue cell composition. These studies illustrate that human adipose tissue in different anatomic locations does not work in isolation, and that there is a best-fit relationship in terms of volume and function among different fat depots that needs to be met to maintain the systemic energy balance and to prevent the complications related to obesity.
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Affiliation(s)
- X Yang
- Centre of Excellence for Metabolic and Cardiovascular Research/The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
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Kim HJ, Jung TW, Kang ES, Kim DJ, Ahn CW, Lee KW, Lee HC, Cha BS. Depot-specific regulation of perilipin by rosiglitazone in a diabetic animal model. Metabolism 2007; 56:676-85. [PMID: 17445544 DOI: 10.1016/j.metabol.2006.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 12/05/2006] [Indexed: 11/17/2022]
Abstract
Treatment with rosiglitazone, a potent peroxisome proliferator-activated receptor (PPAR) gamma agonist, results in lipid storage coupled with reduced release of free fatty acids into the circulation. Many studies have reported that PPAR-gamma agonists increase subcutaneous adiposity but have no effect on visceral fat mass. Perilipin, a family of phosphoproteins that coat intracellular lipid droplets in adipocytes, is essential for enlargement of lipid droplets. Recently, a functional PPAR-responsive element was identified within the murine perilipin gene. We hypothesized that the depot-specific regulation of perilipin by rosiglitazone may be associated with the fat-redistribution and insulin-sensitizing effects of rosiglitazone. After 6 weeks of rosiglitazone treatment in Otusuka Long-Evans Tokushima Fatty rats, an animal model of type 2 diabetes mellitus, we measured changes in adiposity, triglyceride content in liver and muscle, morphology of the pancreas, and perilipin messenger RNA and protein expression in adipose tissue. Rosiglitazone increased subcutaneous adiposity, decreased triglyceride content of liver and muscle, decreased plasma free fatty acids (2107 +/- 507 micromol/L in the placebo group vs 824 +/- 148 micromol/L in the rosiglitazone group; P < .05), and improved insulin resistance. The islets of placebo-treated rats showed hypertrophy and destruction, whereas the islets of rosiglitazone-treated rats showed hypertrophy, but the islet architecture remained intact. Perilipin messenger RNA and protein expression increased in subcutaneous fat, but did not change in visceral fat, after rosiglitazone treatment. In 3T3-L1 cells, rosiglitazone pretreatment decreased lipolysis and increased perilipin protein. In conclusion, increased perilipin expression in subcutaneous fat after rosiglitazone treatment is likely to be a mediator of reduced lipolysis, resulting in lipid storage in subcutaneous fat, fat redistribution, and insulin sensitization.
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Affiliation(s)
- Hae Jin Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, South Korea
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Laplante M, Festuccia WT, Soucy G, Gélinas Y, Lalonde J, Berger JP, Deshaies Y. Mechanisms of the depot specificity of peroxisome proliferator-activated receptor gamma action on adipose tissue metabolism. Diabetes 2006; 55:2771-8. [PMID: 17003342 DOI: 10.2337/db06-0551] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this study, we aimed to establish the mechanisms whereby peroxisome proliferator-activated receptor gamma (PPARgamma) agonism brings about redistribution of fat toward subcutaneous depots and away from visceral fat. In rats treated with the full PPARgamma agonist COOH (30 mg x kg(-1) x day(-1)) for 3 weeks, subcutaneous fat mass was doubled and that of visceral fat was reduced by 30% relative to untreated rats. Uptake of triglyceride-derived nonesterified fatty acids was greatly increased in subcutaneous fat (14-fold) and less so in visceral fat (4-fold), with a concomitant increase, restricted to subcutaneous fat only, in mRNA levels of the uptake-, retention-, and esterification-promoting enzymes lipoprotein lipase, aP2, and diacylglycerol acyltransferase 1. Basal lipolysis and fatty acid recycling were stimulated by COOH in both subcutaneous fat and visceral fat, with no frank quantitative depot specificity. The agonist increased mRNA levels of enzymes of fatty acid oxidation and thermogenesis much more strongly in visceral fat than in subcutaneous fat, concomitantly with a stronger elevation in O2 consumption in the former than in the latter. Mitochondrial biogenesis was stimulated equally in both depots. These findings demonstrate that PPARgamma agonism redistributes fat by stimulating the lipid uptake and esterification potential in subcutaneous fat, which more than compensates for increased O2 consumption; conversely, lipid uptake is minimally altered and energy expenditure is greatly increased in visceral fat, with consequent reduction in fat accumulation.
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Affiliation(s)
- Mathieu Laplante
- Laval Hospital Research Centre, Laval University, Quebec, QC, Canada G1V 4G5
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Gray SL, Nora ED, Grosse J, Manieri M, Stoeger T, Medina-Gomez G, Burling K, Wattler S, Russ A, Yeo GSH, Chatterjee VK, O'Rahilly S, Voshol PJ, Cinti S, Vidal-Puig A. Leptin deficiency unmasks the deleterious effects of impaired peroxisome proliferator-activated receptor gamma function (P465L PPARgamma) in mice. Diabetes 2006; 55:2669-77. [PMID: 17003330 DOI: 10.2337/db06-0389] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Peroxisome proliferator-activated receptor (PPAR)gamma is a key transcription factor facilitating fat deposition in adipose tissue through its proadipogenic and lipogenic actions. Human patients with dominant-negative mutations in PPARgamma display lipodystrophy and extreme insulin resistance. For this reason it was completely unexpected that mice harboring an equivalent mutation (P465L) in PPARgamma developed normal amounts of adipose tissue and were insulin sensitive. This finding raised important doubts about the interspecies translatability of PPARgamma-related findings, bringing into question the relevance of other PPARgamma murine models. Here, we demonstrate that when expressed on a hyperphagic ob/ob background, the P465L PPARgamma mutant grossly exacerbates the insulin resistance and metabolic disturbances associated with leptin deficiency, yet reduces whole-body adiposity and adipocyte size. In mouse, coexistence of the P465L PPARgamma mutation and the leptin-deficient state creates a mismatch between insufficient adipose tissue expandability and excessive energy availability, unmasking the deleterious effects of PPARgamma mutations on carbohydrate metabolism and replicating the characteristic clinical symptoms observed in human patients with dominant-negative PPARgamma mutations. Thus, adipose tissue expandability is identified as an important factor for the development of insulin resistance in the context of positive energy balance.
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Affiliation(s)
- Sarah L Gray
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QR, UK
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47
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Christodoulides C, Laudes M, Cawthorn WP, Schinner S, Soos M, O’Rahilly S, Sethi JK, Vidal-Puig A. The Wnt antagonist Dickkopf-1 and its receptors are coordinately regulated during early human adipogenesis. J Cell Sci 2006; 119:2613-2620. [PMID: 16763196 PMCID: PMC4304001 DOI: 10.1242/jcs.02975] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Secretion of Wnts by adipose cells has an important role in the control of murine adipogenesis. We present the first evidence that a Wnt antagonist, Dickkopf 1 (Dkk1), is secreted by human preadipocytes and promotes adipogenesis. DKK1 mRNA increases six hours after onset of human adipogenesis and this is followed by an increase in Dkk1 protein. With further differentiation, the mRNA and protein levels progressively decline such that they are undetectable in mature adipocytes. The transient induction in DKK1 correlates with downregulation of cytoplasmic and nuclear beta-catenin levels, this being a surrogate marker of canonical Wnt signalling, and Wnt/beta-catenin transcriptional activity. In addition, constitutive expression of Dkk1 in 3T3-L1 preadipocytes promotes their differentiation, further supporting the functional significance of increased Dkk1 levels during human adipogenesis. Concomitant downregulation of the Dkk1 receptors LRP5 and LRP6 is likely to potentiate the ability of Dkk1 to inhibit Wnt signalling and promote differentiation. Notably, Dkk1 is not expressed in primary murine preadipocytes or cell lines. The involvement of Dkk1 in human but not murine adipogenesis indicates that inter-species differences exist in the molecular control of this process. Given the public health importance of disorders of adipose mass, further knowledge of the pathways involved specifically in human adipocyte differentiation might ultimately be of clinical relevance.
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Affiliation(s)
- Constantinos Christodoulides
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Matthias Laudes
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Will P. Cawthorn
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Sven Schinner
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Maria Soos
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Stephen O’Rahilly
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Jaswinder K. Sethi
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
| | - Antonio Vidal-Puig
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke’s Hospital, Hills Road, Cambridge, CB2 2QR, UK
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Abstract
The nuclear receptor family of PPARs was named for the ability of the original member to induce hepatic peroxisome proliferation in mice in response to xenobiotic stimuli. However, studies on the action and structure of the 3 human PPAR isotypes (PPARalpha, PPARdelta, and PPARgamma) suggest that these moieties are intimately involved in nutrient sensing and the regulation of carbohydrate and lipid metabolism. PPARalpha and PPARdelta appear primarily to stimulate oxidative lipid metabolism, while PPARgamma is principally involved in the cellular assimilation of lipids via anabolic pathways. Our understanding of the functions of PPARgamma in humans has been increased by the clinical use of potent agonists and by the discovery of both rare and severely deleterious dominant-negative mutations leading to a stereotyped syndrome of partial lipodystrophy and severe insulin resistance, as well as more common sequence variants with a much smaller impact on receptor function. These may nevertheless have much greater significance for the public health burden of metabolic disease. This Review will focus on the role of PPARgamma in human physiology, with specific reference to clinical pharmacological studies, and analysis of PPARG gene variants in the abnormal lipid and carbohydrate metabolism of the metabolic syndrome.
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Affiliation(s)
- Robert K Semple
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom
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49
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Christodoulides C, Scarda A, Granzotto M, Milan G, Dalla Nora E, Keogh J, De Pergola G, Stirling H, Pannacciulli N, Sethi JK, Federspil G, Vidal-Puig A, Farooqi IS, O'Rahilly S, Vettor R. WNT10B mutations in human obesity. Diabetologia 2006; 49:678-84. [PMID: 16477437 PMCID: PMC4304000 DOI: 10.1007/s00125-006-0144-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 11/09/2005] [Indexed: 11/24/2022]
Abstract
AIMS/HYPOTHESIS Recent studies suggest that wingless-type MMTV integration site family, member 10B (WNT10B) may play a role in the negative regulation of adipocyte differentiation in vitro and in vivo. In order to determine whether mutations in WNT10B contribute to human obesity, we screened two independent populations of obese subjects for mutations in this gene. SUBJECTS AND METHODS We studied 96 subjects with severe obesity of early onset (less than 10 years of age) from the UK Genetics of Obesity Study and 115 obese Italian subjects of European origin. RESULTS One proband with early-onset obesity was found to be heterozygous for a C256Y mutation, which abrogated the ability of WNT10B to activate canonical WNT signalling and block adipogenesis and was not found in 600 control alleles. All relatives of the proband who carried this allele were either overweight or obese. Three other rare missense variants were found in obese probands, but these did not clearly cosegregate with obesity in family studies and one (P301S), which was found in three unrelated subjects with early-onset obesity, had normal functional properties. CONCLUSIONS/INTERPRETATION These mutations represent the first naturally occurring missense variants of WNT10B. While the pedigree analysis in the case of C256Y WNT10B does not provide definitive proof of a causal link of this variant with obesity, the finding of a non-functioning WNT10B allele in a human family affected by obesity should encourage further study of this gene in other obese populations.
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Affiliation(s)
- C Christodoulides
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Box 232, Cambridge, CB2 2QQ, UK
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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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