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Kim YK, Jo D, Arjunan A, Ryu Y, Lim YH, Choi SY, Kim HK, Song J. Identification of IGF-1 Effects on White Adipose Tissue and Hippocampus in Alzheimer's Disease Mice via Transcriptomic and Cellular Analysis. Int J Mol Sci 2024; 25:2567. [PMID: 38473814 DOI: 10.3390/ijms25052567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/17/2024] [Accepted: 02/19/2024] [Indexed: 03/14/2024] Open
Abstract
Alzheimer's disease (AD) stands as the most prevalent neurodegenerative disorder, characterized by a multitude of pathological manifestations, prominently marked by the aggregation of amyloid beta. Recent investigations have revealed a compelling association between excessive adiposity and glial activation, further correlating with cognitive impairments. Additionally, alterations in levels of insulin-like growth factor 1 (IGF-1) have been reported in individuals with metabolic conditions accompanied by memory dysfunction. Hence, our research endeavors to comprehensively explore the impact of IGF-1 on the hippocampus and adipose tissue in the context of Alzheimer's disease. To address this, we have conducted an in-depth analysis utilizing APP/PS2 transgenic mice, recognized as a well-established mouse model for Alzheimer's disease. Upon administering IGF-1 injections to the APP/PS2 mice, we observed notable alterations in their behavioral patterns, prompting us to undertake a comprehensive transcriptomic analysis of both the hippocampal and adipose tissues. Our data unveiled significant modifications in the functional profiles of these tissues. Specifically, in the hippocampus, we identified changes associated with synaptic activity and neuroinflammation. Concurrently, the adipose tissue displayed shifts in processes related to fat browning and cell death signaling. In addition to these findings, our analysis enabled the identification of a collection of long non-coding RNAs and circular RNAs that exhibited significant changes in expression subsequent to the administration of IGF-1 injections. Furthermore, we endeavored to predict the potential roles of these identified RNA molecules within the context of our study. In summary, our study offers valuable transcriptome data for hippocampal and adipose tissues within an Alzheimer's disease model and posits a significant role for IGF-1 within both the hippocampus and adipose tissue.
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Affiliation(s)
- Young-Kook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
- Biomedical Science Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Danbi Jo
- Biomedical Science Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Jeollanamdo, Republic of Korea
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Archana Arjunan
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Yeongseo Ryu
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
- Biomedical Science Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Yeong-Hwan Lim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Seo Yoon Choi
- Biomedical Science Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Jeollanamdo, Republic of Korea
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Hee Kyung Kim
- Department of Endocrinology and Metabolism, Department of Internal Medicine, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
| | - Juhyun Song
- Biomedical Science Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Jeollanamdo, Republic of Korea
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanamdo, Republic of Korea
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Dong SS, Zhu DL, Zhou XR, Rong Y, Zeng M, Chen JB, Jiang F, Tuo XM, Feng Z, Yang TL, Guo Y. An Intronic Risk SNP rs12454712 for Central Obesity Acts As an Allele-Specific Enhancer To Regulate BCL2 Expression. Diabetes 2021; 70:1679-1688. [PMID: 34035043 DOI: 10.2337/db20-1151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 05/10/2021] [Indexed: 11/13/2022]
Abstract
Genome-wide association studies (GWAS) have reproducibly associated the single nucleotide polymorphism (SNP) rs12454712 with waist-to-hip ratio adjusted for BMI (WHRadjBMI), but the functional role underlying this intronic variant is unknown. Integrative genomic and epigenomic analyses supported rs12454712 as a functional independent variant. We further demonstrated that rs12454712 acted as an allele-specific enhancer regulating expression of its located gene BCL2 by using dual-luciferase reporter assays and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9. Specifically, the rs12454712-C allele can bind transcription factor ZNF329, which efficiently elevates the enhancer activity and increases BCL2 expression. Knocking down Bcl2 in 3T3-L1 cells led to the downregulation of adipogenic differentiation marker genes and increased cell apoptosis. A significant negative correlation between BCL2 expression in subcutaneous adipose tissues and obesity was observed. Our findings illustrate the molecular mechanisms behind the intronic SNP rs12454712 for central obesity, which would be a potential and promising target for developing appropriate therapies.
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Affiliation(s)
- Shan-Shan Dong
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
- Research Institute of Xi'an Jiaotong University, Hangzhou, Zhejiang, China
| | - Dong-Li Zhu
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Xiao-Rong Zhou
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Yu Rong
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Mengqi Zeng
- Center for Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Jia-Bin Chen
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Feng Jiang
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Xiao-Mei Tuo
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Zhihui Feng
- Center for Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Tie-Lin Yang
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
| | - Yan Guo
- Biomedical Informatics & Genomics Center, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi, China
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Chemically Defined Xeno- and Serum-Free Cell Culture Medium to Grow Human Adipose Stem Cells. Cells 2021; 10:cells10020466. [PMID: 33671568 PMCID: PMC7926673 DOI: 10.3390/cells10020466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 02/07/2023] Open
Abstract
Adipose tissue is an abundant source of stem cells. However, liposuction cannot yield cell quantities sufficient for direct applications in regenerative medicine. Therefore, the development of GMP-compliant ex vivo expansion protocols is required to ensure the production of a "cell drug" that is safe, reproducible, and cost-effective. Thus, we developed our own basal defined xeno- and serum-free cell culture medium (UrSuppe), specifically formulated to grow human adipose stem cells (hASCs). With this medium, we can directly culture the stromal vascular fraction (SVF) cells in defined cell culture conditions to obtain hASCs. Cells proliferate while remaining undifferentiated, as shown by Flow Cytometry (FACS), Quantitative Reverse Transcription PCR (RT-qPCR) assays, and their secretion products. Using the UrSuppe cell culture medium, maximum cell densities between 0.51 and 0.80 × 105 cells/cm2 (=2.55-4.00 × 105 cells/mL) were obtained. As the expansion of hASCs represents only the first step in a cell therapeutic protocol or further basic research studies, we formulated two chemically defined media to differentiate the expanded hASCs in white or beige/brown adipocytes. These new media could help translate research projects into the clinical application of hASCs and study ex vivo the biology in healthy and dysfunctional states of adipocytes and their precursors. Following the cell culture system developers' practice and obvious reasons related to the formulas' patentability, the defined media's composition will not be disclosed in this study.
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Park J, Huh JY, Oh J, Kim JI, Han SM, Shin KC, Jeon YG, Choe SS, Park J, Kim JB. Activation of invariant natural killer T cells stimulates adipose tissue remodeling via adipocyte death and birth in obesity. Genes Dev 2019; 33:1657-1672. [PMID: 31727774 PMCID: PMC6942052 DOI: 10.1101/gad.329557.119] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 10/18/2019] [Indexed: 12/12/2022]
Abstract
In this study, Park et al. set out to elucidate the mechanism by which adipose-resident invariant natural killer T cells (iNKT) cells impact adipose tissue remodeling in obesity. Using in vitro and ex vivo approaches, the authors found that, in obesity, adipose iNKT cells can kill hypertrophic and pro-inflammatory adipocytes via FasL-Fas-dependent apoptosis, thus providing new insight into the role adipose iNKT cells play in promoting healthy adipose tissue remodeling. In obesity, adipose tissue undergoes dynamic remodeling processes such as adipocyte hypertrophy, hypoxia, immune responses, and adipocyte death. However, whether and how invariant natural killer T (iNKT) cells contribute to adipose tissue remodeling are elusive. In this study, we demonstrate that iNKT cells remove unhealthy adipocytes and stimulate the differentiation of healthy adipocytes. In obese adipose tissue, iNKT cells were abundantly found nearby dead adipocytes. FasL-positive adipose iNKT cells exerted cytotoxic effects to eliminate hypertrophic and pro-inflammatory Fas-positive adipocytes. Furthermore, in vivo adipocyte-lineage tracing mice model showed that activation of iNKT cells by alpha-galactosylceramide promoted adipocyte turnover, eventually leading to potentiation of the insulin-dependent glucose uptake ability in adipose tissue. Collectively, our data propose a novel role of adipose iNKT cells in the regulation of adipocyte turnover in obesity.
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Affiliation(s)
- Jeu Park
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Jin Young Huh
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Jiyoung Oh
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Jong In Kim
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Sang Mun Han
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Kyung Cheul Shin
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Yong Geun Jeon
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Sung Sik Choe
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - Jiyoung Park
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Jae Bum Kim
- National Creative Research Initiatives Center for Adipose Tissue Remodeling, Institute of Molecular Biology and Genetics, Department of Biological Sciences, Seoul National University, Seoul 08826, South Korea
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Engin A. Fat Cell and Fatty Acid Turnover in Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 960:135-160. [PMID: 28585198 DOI: 10.1007/978-3-319-48382-5_6] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid droplet-associated protein and fatty acid turn-over is also debated.
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Affiliation(s)
- Atilla Engin
- Faculty of Medicine, Department of General Surgery, Gazi University, Besevler, Ankara, Turkey. .,, Mustafa Kemal Mah. 2137. Sok. 8/14, 06520, Cankaya, Ankara, Turkey.
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Zoller V, Funcke JB, Roos J, Dahlhaus M, Abd El Hay M, Holzmann K, Marienfeld R, Kietzmann T, Debatin KM, Wabitsch M, Fischer-Posovszky P. Trail (TNF-related apoptosis-inducing ligand) induces an inflammatory response in human adipocytes. Sci Rep 2017; 7:5691. [PMID: 28720906 PMCID: PMC5515939 DOI: 10.1038/s41598-017-05932-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/06/2017] [Indexed: 01/28/2023] Open
Abstract
High serum concentrations of TNF-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor protein family, are found in patients with increased BMI and serum lipid levels. In a model of murine obesity, both the expression of TRAIL and its receptor (TRAIL-R) is elevated in adipose tissue. Accordingly, TRAIL has been proposed as an important mediator of adipose tissue inflammation and obesity-associated diseases. The aim of this study was to investigate if TRAIL regulates inflammatory processes at the level of the adipocyte. Using human Simpson-Golabi-Behmel syndrome (SGBS) cells as a model system, we found that TRAIL induces an inflammatory response in both preadipocytes and adipocytes. It stimulates the expression of interleukin 6 (IL-6), interleukin 8 (IL-8) as well as the chemokines monocyte chemoattractant protein-1 (MCP-1) and chemokine C-C motif ligand 20 (CCL-20) in a time- and dose-dependent manner. By using small molecule inhibitors, we found that both the NFκB and the ERK1/2 pathway are crucial for mediating the effect of TRAIL. Taken together, we identified a novel pro-inflammatory function of TRAIL in human adipocytes. Our findings suggest that targeting the TRAIL/TRAIL-R system might be a useful strategy to tackle obesity-associated adipose tissue inflammation.
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Affiliation(s)
- Verena Zoller
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Jan-Bernd Funcke
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Julian Roos
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Meike Dahlhaus
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Muad Abd El Hay
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | | | - Ralf Marienfeld
- Institute of Pathology, Ulm University, Ulm, Germany; Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Thomas Kietzmann
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Klaus-Michael Debatin
- Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany.
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Hypoxia in Obesity and Diabetes: Potential Therapeutic Effects of Hyperoxia and Nitrate. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:5350267. [PMID: 28607631 PMCID: PMC5457776 DOI: 10.1155/2017/5350267] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 04/04/2017] [Accepted: 04/11/2017] [Indexed: 02/06/2023]
Abstract
The prevalence of obesity and diabetes is increasing worldwide. Obesity and diabetes are associated with oxidative stress, inflammation, endothelial dysfunction, insulin resistance, and glucose intolerance. Obesity, a chronic hypoxic state that is associated with decreased nitric oxide (NO) bioavailability, is one of the main causes of type 2 diabetes. The hypoxia-inducible factor-1α (HIF-1α) is involved in the regulation of several genes of the metabolic pathways including proinflammatory adipokines, endothelial NO synthase (eNOS), and insulin signaling components. It seems that adipose tissue hypoxia and NO-dependent vascular and cellular dysfunctions are responsible for other consequences linked to obesity-related disorders. Although hyperoxia could reverse hypoxic-related disorders, it increases the production of reactive oxygen species (ROS) and decreases the production of NO. Nitrate can restore NO depletion and has antioxidant properties, and recent data support the beneficial effects of nitrate therapy in obesity and diabetes. Although it seems reasonable to combine hyperoxia and nitrate treatments for managing obesity/diabetes, the combined effects have not been investigated yet. This review discusses some aspects of tissue oxygenation and the potential effects of hyperoxia and nitrate interventions on obesity/diabetes management. It can be proposed that concomitant use of hyperoxia and nitrate is justified for managing obesity and diabetes.
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Gude MF, Hjortebjerg R, Oxvig C, Thyø AA, Magnusson NE, Bjerre M, Pedersen SB, Frystyk J. PAPP-A, IGFBP-4 and IGF-II are secreted by human adipose tissue cultures in a depot-specific manner. Eur J Endocrinol 2016; 175:509-519. [PMID: 27585595 DOI: 10.1530/eje-16-0569] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/16/2016] [Accepted: 09/01/2016] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Adipose tissue secretes pregnancy-associated plasma protein-A (PAPP-A), which may increase local IGF action through cleavage of IGF-binding protein-4 (IGFBP-4). We tested whether this mechanism was operational in human visceral and subcutaneous adipose tissue (i.e. VAT and SAT). DESIGN Explants of VAT and SAT from 26 obese subjects (hereof 17 women, BMI 39.5 (37.2; 42.8) kg/m2 (median (25%; 75% confidence interval) and SAT from eight lean, age-matched women (BMI 23.6 (22.4; 24.9) kg/m2) were incubated with or without GH (100 µg/L) and the media were harvested. METHODS Media were assessed for concentrations of PAPP-A, intact and PAPP-A-cleaved IGFBP-4, IGF-I and IGF-II, and IGF-I receptor (IGF-IR) activation by bioassay. RESULTS In obese subjects, VAT media contained higher concentrations than SAT of PAPP-A (4.4-fold) and both PAPP-A-generated IGFBP-4 fragments (C-terminal: 3.3-fold, N-terminal: 1.5-fold) (all P < 0.0005). Intact IGFBP-4 levels were similar in SAT and VAT. VAT media contained elevated IGF-II (1.4-fold; P < 0.005), but similar IGF-I concentrations compared with SAT. Still, VAT media contained a 1.8-fold increased ability to stimulate the IGF-IR (P < 0.005). IGF-I protein concentration and IGF-IR activation increased more in VAT media than SAT media following GH stimulation (both P < 0.05). At baseline, SAT media protein levels from lean and obese women were similar, with the exception of PAPP-A being 1.8-fold elevated in VAT media (P < 0.05). GH induced a similar increase in IGF-I media levels in SAT from obese and lean women. CONCLUSION Human adipose tissue cultures secrete enzymatically active PAPP-A, IGFBP-4 and IGF-II in a depot-specific manner, suggesting differential regulation of IGF activity. Further, IGF-II appears to be more prominent than IGF-I. Finally, VAT appears more GH responsive than SAT.
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Affiliation(s)
- Mette Faurholdt Gude
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
| | - Rikke Hjortebjerg
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
- Danish Diabetes AcademyOdense, Denmark
| | - Claus Oxvig
- Department of Molecular Biology and GeneticsFaculty of Science and Technology, Aarhus University, Aarhus C, Denmark
| | | | - Nils Erik Magnusson
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
| | - Mette Bjerre
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
| | - Steen Bønløkke Pedersen
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
- Endocrinology and Internal MedicineAarhus University Hospital, Aarhus C, Denmark
| | - Jan Frystyk
- Medical Research LaboratoryDepartment of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus C, Denmark
- Endocrinology and Internal MedicineAarhus University Hospital, Aarhus C, Denmark
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9
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Zoller V, Funcke JB, Keuper M, Abd El Hay M, Debatin KM, Wabitsch M, Fischer-Posovszky P. TRAIL (TNF-related apoptosis-inducing ligand) inhibits human adipocyte differentiation via caspase-mediated downregulation of adipogenic transcription factors. Cell Death Dis 2016; 7:e2412. [PMID: 27735943 PMCID: PMC5133965 DOI: 10.1038/cddis.2016.286] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 07/13/2016] [Accepted: 08/10/2016] [Indexed: 01/20/2023]
Abstract
Tumor necrosis factor-α (TNFα) and other ligands of the TNF superfamily are potent regulators of adipose tissue metabolism and play a crucial role in the obesity-induced inflammation of adipose tissue. Adipose tissue expression levels of TRAIL (TNF-related apoptosis-inducing ligand) and its receptor were shown to be upregulated by overfeeding and decreased by fasting in mice. In the present study we aimed to elucidate the impact of TRAIL on adipogenesis. To this end, human Simpson-Golabi-Behmel syndrome (SGBS) preadipocytes as well as stromal-vascular cells isolated from human white adipose tissue were used as model systems. Human recombinant TRAIL inhibited adipogenic differentiation in a dose-dependent manner. It activated the cleavage of caspase-8 and -3, which in turn resulted in a downregulation of the key adipogenic transcription factors C/EBPα, C/EBPδ, and PPARγ. The effect was completely blocked by pharmacological or genetic inhibition of caspases. Taken together we discovered a so far unrecognized function of TRAIL in the regulation of adipogenesis. Targeting the TRAIL/TRAIL receptor system might provide a novel strategy to interfere with adipose tissue homeostasis.
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Affiliation(s)
- Verena Zoller
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Jan-Bernd Funcke
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Michaela Keuper
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Muad Abd El Hay
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Klaus-Michael Debatin
- Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
| | - Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatric and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany
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10
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Funcke JB, Zoller V, El Hay MA, Debatin KM, Wabitsch M, Fischer-Posovszky P. TNF-related apoptosis-inducing ligand promotes human preadipocyte proliferation via ERK1/2 activation. FASEB J 2015; 29:3065-75. [PMID: 25857555 DOI: 10.1096/fj.14-267278] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/16/2015] [Indexed: 12/31/2022]
Abstract
Upon obesity, adipose tissue is excessively expanded and characterized by pathologic processes like hypoxia, fibrosis, and inflammation. Death ligands belonging to the TNF superfamily such as TNF-α are important contributors to these derangements and exert a pronounced influence on the metabolic and cellular homeostasis of adipose tissue. Here, we sought to identify the effect of the death ligand TNF-related apoptosis-inducing ligand (TRAIL) on the adipose tissue precursor cell pool and therefore investigated its influence on preadipocyte proliferation. Treatment of human preadipocytes with TRAIL resulted in a time- and dose-dependent increase in proliferation (EC50 3.4 ng/ml) comparable to IGF-1. Although no apoptosis was observed, TRAIL triggered a rapid cleavage of caspase-8 and -3. Neither inhibition of caspase activity by zVAD.fmk (20 µM) nor ablation of caspase-8 expression by lentivirus-delivered small hairpin RNA (shRNA) abolished the proliferative response. TRAIL triggered a delayed and sustained activation of ERK1/2, leaving Akt, p38, JNK, and NF-κB unaffected. Importantly, inhibition of ERK1/2 activation by PD0325901 (300 nM) or AZD6244 (5 or 10 µM) completely abolished the proliferative response. We thus reveal a hitherto unknown function of TRAIL in regulating adipose tissue homeostasis by promoting the proliferation of tissue-resident precursor cells.
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Affiliation(s)
- Jan-Bernd Funcke
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
| | - Verena Zoller
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
| | - Muad Abd El Hay
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
| | - Klaus-Michael Debatin
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
| | - Martin Wabitsch
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
| | - Pamela Fischer-Posovszky
- *Division of Pediatric Endocrinology and Diabetes and Department of Pediatrics and Adolescent Medicine, Ulm Medical Center, Ulm, Germany
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11
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Tabernero J, Chawla SP, Kindler H, Reckamp K, Chiorean EG, Azad NS, Lockhart AC, Hsu CP, Baker NF, Galimi F, Beltran P, Baselga J. Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab. Target Oncol 2014; 10:65-76. [PMID: 24816908 DOI: 10.1007/s11523-014-0315-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 04/03/2014] [Indexed: 01/20/2023]
Abstract
Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or non-squamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p < 0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0-261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers.
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Affiliation(s)
- Josep Tabernero
- Vall d'Hebron University Hospital and Institute of Oncology (VHIO), Universitat Autònoma de Barcelona, Passeig Vall d'Hebron 119-129, Barcelona, 08035, Spain,
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12
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Cardoso DF, Martinelli CE, Campos VC, Gomes ES, Rocha IES, Oliveira CRP, Vicente TAR, Pereira RMC, Pereira FA, Cartaxo CKA, Milani SLS, Oliveira MCP, Melo EV, Oliveira ALP, Aguiar-Oliveira MH. Comparison between the growth response to growth hormone (GH) therapy in children with partial GH insensitivity or mild GH deficiency. ARQUIVOS BRASILEIROS DE ENDOCRINOLOGIA E METABOLOGIA 2014; 58:23-9. [PMID: 24728160 DOI: 10.1590/0004-2730000002793] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 10/16/2013] [Indexed: 11/21/2022]
Abstract
OBJECTIVES GH therapy is still controversial, except in severe GH deficiency (SGHD). The objective of this study was to compare the response to growth hormone (GH) therapy in children with partial GH insensitivity (PGHIS) and mild GH deficiency (MGHD) with those with SGHD. SUBJECTS AND METHODS Fifteen PGHIS, 11 MGHD, and 19 SGHD subjects, followed up for more than one year in the Brazilian public care service, were evaluated regarding anthropometric and laboratory data at the beginning of treatment, after one year (1st year) on treatment, and at the last assessment (up to ten years in SGHD, up to four years in MGHD, and up to eight years in PGHIS). RESULTS Initial height standard deviation score (SDS) in SGHD was lower than in MGHD and PGHIS. Although the increase in 1 st year height SDS in comparison to initial height SDS was not different among the groups, height-SDS after the first year of treatment remained lower in SGHD than in MGHD. There was no difference in height-SDS at the last assessment of the children among the three groups. GH therapy, in the entire period of observation, caused a trend towards lower increase in height SDS in PGHIS than SGHD but similar increases were observed in MGHD and SGHD. CONCLUSION GH therapy increases height in PGHIS and produces similar height effects in MGHD and SGHD.
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Affiliation(s)
- Daniela F Cardoso
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Carlos Eduardo Martinelli
- Department of Pediatrics, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Viviane C Campos
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Elenilde S Gomes
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Ivina E S Rocha
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Carla R P Oliveira
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Taisa A R Vicente
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Rossana M C Pereira
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Francisco A Pereira
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Carla K A Cartaxo
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Soraya L S Milani
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Mario C P Oliveira
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Enaldo V Melo
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
| | - Andre L P Oliveira
- Department of Medicine, Universidade Federal de Sergipe, Aracaju, SE, Brazil
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13
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Kim WS, Han J, Hwang SJ, Sung JH. An update on niche composition, signaling and functional regulation of the adipose-derived stem cells. Expert Opin Biol Ther 2014; 14:1091-102. [DOI: 10.1517/14712598.2014.907785] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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14
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Nagel SA, Keuper M, Zagotta I, Enlund E, Ruperez AI, Debatin KM, Wabitsch M, Fischer-Posovszky P. Up-regulation of Bcl-2 during adipogenesis mediates apoptosis resistance in human adipocytes. Mol Cell Endocrinol 2014; 382:368-376. [PMID: 24397922 DOI: 10.1016/j.mce.2013.10.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/16/2013] [Accepted: 10/21/2013] [Indexed: 01/05/2023]
Abstract
Targeting apoptotic pathways in adipocytes has been suggested as a pharmacological approach to treat obesity. However, adipocyte apoptosis was identified as a cause for macrophage infiltration into adipose tissue. Previous studies suggest that mature adipocytes are less sensitive to apoptotic stimuli as compared to preadipocytes. Here, we aimed to identify proteins mediating apoptosis resistance in adipocytes. Our data revealed that the anti-apoptotic protein Bcl-2 (B-cell lymphoma 2) is up-regulated during adipogenic differentiation. Bcl-2 overexpression in preadipocytes lowers their apoptosis sensitivity to the level of mature adipocytes. Vice versa Bcl-2 knockdown in adipocytes sensitizes these cells to CD95-induced apoptosis. Taken together, our findings suggest a shift in the balance of pro-apoptotic and anti-apoptotic molecules during adipogenesis resulting in a higher apoptosis resistance. This study sheds new light on the apoptotic process in human fat cells and may constitute a new possible target for the specific regulation of adipose tissue mass.
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Affiliation(s)
- Stella A Nagel
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Michaela Keuper
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Ivana Zagotta
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Eveliina Enlund
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Azahara Iris Ruperez
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Klaus-Michael Debatin
- Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany.
| | - Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, 89075 Ulm, Germany.
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15
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Abstract
Obesity has reached epidemic proportions in the U.S.A. and many other parts of the world. Obesity increases the risk of a number of adverse health conditions including type 2 diabetes, insulin resistance, dyslipidemia, hypertension, and hepatic steatosis. Adipocyte hypertrophy occurs during weight gain and is associated with recruitment of immune cells, mainly macrophages, into the adipose tissue (AT). These cells typically surround a dying or dead adipocyte with the formation of crown-like structures that are present in experimental models of obesity as well as obese humans. The immune infiltration of AT results in increased production of various adipokines, cytokines, and chemokines that play a crucial role in the development of insulin resistance and hepatic steatosis. The pathogenic mechanisms resulting in AT macrophage recruitment are under intense investigation and remain incompletely understood. Recent evidence suggests that various programmed cell death pathways are activated in stressed hypertrophied adipocytes and may result in cell death. These events appear to occur at early stages and be important in triggering the metabolic dysregulation associated with obesity.
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Affiliation(s)
- Akiko Eguchi
- Department of Pediatrics, University of California San Diego (UCSD), CA, USA
| | - Ariel E. Feldstein
- Department of Pediatrics, University of California San Diego (UCSD), CA, USA
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16
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17
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Dysregulated Alternative Splicing Pattern of PKCδ during Differentiation of Human Preadipocytes Represents Distinct Differences between Lean and Obese Adipocytes. ISRN OBESITY 2013; 2013:161345. [PMID: 24533217 PMCID: PMC3901959 DOI: 10.1155/2013/161345] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/05/2013] [Indexed: 11/17/2022]
Abstract
Obesity and its comorbidities affect millions of people. Here, we demonstrate that human preadipocytes are susceptible to programmed cell death (apoptosis) while mature adipocytes are resistant to apoptosis. The molecular mechanisms underlying the phenotype of apoptosis-resistant adipocytes are lesser known. To study the role of apoptosis and define molecular differences in the developmental process of adipogenesis, human preadipocytes were differentiated in vitro to mature adipocytes. Many genes in the apoptosis pathway are alternatively spliced. Our data demonstrates that during differentiation PKC δ , Bclx, and Caspase9 switch to their prosurvival splice variants along with an increase in Bcl2 expression when the cells terminally differentiate into mature adipocytes. Next we determined the expression pattern of these genes in obesity. Our data indicated high expression of PKC δ VIII in adipose tissue of obese patient in different depots. We demonstrate a shift in the in vitro expression of these splice variants in differentiating preadipocytes derived from obese patients along with a decrease in adipogenesis markers. Hence, the programmed splicing of antiapoptotic proteins is a pivotal switch in differentiation that commits adipocytes to a prosurvival pathway. The expression pattern of these genes is dysregulated in obesity and may contribute to adipose tissue dysfunction.
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18
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TRAIL (TNF-related apoptosis-inducing ligand) regulates adipocyte metabolism by caspase-mediated cleavage of PPARgamma. Cell Death Dis 2013; 4:e474. [PMID: 23348588 PMCID: PMC3563999 DOI: 10.1038/cddis.2012.212] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tumor necrosis factor α (TNFα) and other members of the TNF family affect adipose tissue metabolism and contribute to the obesity-related inflammation of adipose tissue. Here, we sought to identify the effects of TRAIL (TNF-related apoptosis-inducing ligand) on fat cell biology. TRAIL-receptor 2 (TRAIL-R2) and its mouse homolog DR5 were regulated upon acute and chronic energy imbalance in murine and human adipose tissue. TRAIL inhibited insulin-stimulated glucose uptake and de novo lipogenesis in human adipocytes. Interestingly, TRAIL did not interfere with the phosphorylation of insulin-stimulated kinases such as Akt or Erk and did not activate the NF-κB pathway. Instead, TRAIL activated cleavage of caspase-8 and caspase-3. The subsequent cleavage of PPARγ led to its inactivation and resulted in reduced expression of lipogenic genes, such as Glut-4, FASN, and ACC. Taken together, we discovered a so far unknown function of the death ligand TRAIL in regulating adipocyte metabolism. Our results imply that TRAIL/TRAIL-R system might provide a new target for the prevention and treatment of obesity and its co-morbidities.
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19
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Sorisky A, Molgat ASD, Gagnon A. Macrophage-induced adipose tissue dysfunction and the preadipocyte: should I stay (and differentiate) or should I go? Adv Nutr 2013; 4:67-75. [PMID: 23319125 PMCID: PMC3648741 DOI: 10.3945/an.112.003020] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Adipose tissue can be regarded as a multidepot organ responsible for metabolic homeostasis by managing sophisticated energy transactions as well as by producing bioactive molecules that regulate insulin sensitivity and immune and vascular responses. Chronic nutrient excess expands adipose tissue, and concomitant variations in its cellular and matrix remodeling can affect the extent of the metabolic dysfunction that is associated with obesity. Preadipocytes, also termed adipose progenitor cells, play a pivotal role in determining whether a dysfunctional hypertrophic state arises as opposed to a hyperplastic process in which mature adipocytes remain relatively responsive. Obesity is associated with infiltration of macrophages, and these immune cells have been shown to communicate with preadipocytes to influence how they differentiate, survive, and proliferate. Understanding macrophage-preadipocyte interactions and their effect on adipose remodeling mechanisms may identify potential therapeutic molecular targets to improve adipose tissue function, even in the face of obesity.
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Affiliation(s)
- Alexander Sorisky
- Chronic Disease Program, Ottawa Hospital Research Institute, Ontario, Canada.
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20
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Affiliation(s)
- Jeff Holly
- Academic Units of Surgery and Child Health, University of Bristol, Bristol, United Kingdom
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21
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Vidal N, Cavaillé JP, Poggi M, Peiretti F, Stocker P. A nonradioisotope chemiluminescent assay for evaluation of 2-deoxyglucose uptake in 3T3-L1 adipocytes. Effect of various carbonyls species on insulin action. Biochimie 2012; 94:2569-76. [PMID: 22835478 DOI: 10.1016/j.biochi.2012.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/06/2012] [Indexed: 01/15/2023]
Abstract
We have developed a rapid nonradioisotope chemiluminescent assay adapted to high-throughput screening experiments, to evaluate glucose uptake activity in cultured cells. For chemiluminescence quantification of 2-deoxyglucose, we used a luminol oxidation reaction after an enzymatic dephosphorylation of 2-deoxyglucose-6-phosphate. All reactions were performed at 37 °C by consecutive addition of reagents, and the assay is able to quantify 2DG in picomole per well. To confirm the reliability of this method, we have evaluated the dose-effect of insulin, GLUT4 inhibitors and insulin-sensitizing agent on 2DG uptake into 3T3-L1 cells. The results obtained with the assay for 2DG uptake in vitro in the absence or presence of insulin stimulation, were similar to those obtained by the previous radioisotopic and enzymatic methods. We have also used this assay to evaluate the effect of various reactive carbonyl and oxygen species on insulin-stimulated 2DG-uptake into adipocytes. All reactive carbonyl species tested decreased insulin-stimulated glucose uptake in a time- and dose-dependent manner without affecting basal glucose uptake in 3T3-L1 cells. 4-hydroxynonenal was found to be the most potent in the impairment of glucose uptake. This new enzymatic chemiluminescent assay is rapid and useful for measurement of 2DG uptake in insulin-responsive in cultured cells.
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Affiliation(s)
- Nicolas Vidal
- Aix Marseille Université, Faculté des Sciences de St Jérôme, Institut de chimie radicalaire, UMR-7273 CNRS, 13397 Marseille Cedex 20, France
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22
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Fischer-Posovszky P, Tews D, Horenburg S, Debatin KM, Wabitsch M. Differential function of Akt1 and Akt2 in human adipocytes. Mol Cell Endocrinol 2012; 358:135-43. [PMID: 22480544 DOI: 10.1016/j.mce.2012.03.018] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 03/22/2012] [Accepted: 03/22/2012] [Indexed: 01/01/2023]
Abstract
Adipose tissue mass is determined by both cell size and cell number. Mouse models suggest that Akt isoforms are involved in the determination of fat mass by interfering with preadipocyte-to-adipocyte transition and regulating lipid storage. Here, we took advantage of a lentiviral mediated shRNA approach to study the role of Akt1 and Akt2 in differentiation and metabolism of human SGBS adipocytes. Adipogenic differentiation as measured by lipid accumulation was robustly inhibited in Akt2 deficient cells, whereas it was not affected by knockdown of Akt1. The knockdown of Akt2 caused an almost complete inhibition of preadipocyte proliferation. Furthermore, Akt2 deficient preadipocytes were significantly more sensitive to apoptosis induction by death receptor stimulation compared to Akt1 deficient cells. Both the knockdown of Akt1 or Akt2 equally affected insulin-stimulated lipogenesis as well as the anti-lipolytic effect of insulin. We conclude that Akt2 is indispensable for the regulation of preadipocyte and adipocyte number, whereas Akt1 and Akt2 are equally important for the regulation of insulin-stimulated metabolic pathways in human adipocytes. Recently proposed as an attractive target for the treatment of cancer, modulating Akt2 activity might also be a new molecular strategy to control adipose tissue mass.
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Affiliation(s)
- Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University Medical Center, Eythstr. 24, 89075 Ulm, Germany
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23
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Molgat ASD, Gagnon A, Foster C, Sorisky A. The activation state of macrophages alters their ability to suppress preadipocyte apoptosis. J Endocrinol 2012; 214:21-9. [PMID: 22556272 DOI: 10.1530/joe-12-0114] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Adipose tissue contains macrophages whose state of activation is regulated as obesity develops. Macrophage-secreted factors influence critical processes involved in adipose tissue homeostasis, including preadipocyte proliferation and differentiation into adipocytes. Macrophage-conditioned medium (MacCM) from J774A.1 macrophages protects 3T3-L1 preadipocytes from apoptosis through platelet-derived growth factor (PDGF) signaling. Here, we investigated the effect of macrophage activation on MacCM-dependent preadipocyte survival. MacCM was prepared following activation of either J774A.1 macrophages with lipopolysaccharide (LPS) or human primary monocyte-derived macrophages (MD-macrophages) with LPS or interleukin 4 (IL4). 3T3-L1 and human primary preadipocytes were induced to undergo apoptosis in MacCM, and apoptosis was quantified by cell enumeration or Hoechst nuclear staining. Preadipocyte PDGF signaling was assessed by immunoblot analysis of phosphorylated PDGF receptor, Akt, and ERK1/2. Pro-inflammatory activation of J774A.1 macrophages with LPS inhibited the pro-survival activity of MacCM on 3T3-L1 preadipocytes, despite intact PDGF signaling. Upregulation of macrophage tumor necrosis factor a (TNFα) expression occurred in response to LPS, and TNFα was demonstrated to be responsible for the inability of LPS-J774A.1-MacCM to inhibit preadipocyte apoptosis. Furthermore, MacCM from human MD-macrophages (MD-MacCM) inhibited apoptosis of primary human preadipocytes. MD-MacCM from LPS-treated macrophages, but not IL4-treated anti-inflammatory macrophages, was unable to protect human preadipocytes from cell death. In both murine cell lines and human primary cells, pro-inflammatory activation of macrophages inhibits their pro-survival activity, favoring preadipocyte death. These findings may be relevant to preadipocyte fate and adipose tissue remodeling in obesity.
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Affiliation(s)
- André S D Molgat
- Chronic Disease Program, Ottawa Hospital Research Institute, Canada K1H 8L6
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24
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Garten A, Schuster S, Kiess W. The insulin-like growth factors in adipogenesis and obesity. Endocrinol Metab Clin North Am 2012; 41:283-95, v-vi. [PMID: 22682631 DOI: 10.1016/j.ecl.2012.04.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Adipose tissue has been recognized as a major target of growth hormone (GH) action. GH was shown to inhibit adipocyte differentiation but stimulated preadipocyte proliferation in vitro. GH acts directly via its receptor or via upregulating insulin-like growth factor (IGF)-I, which is a critical mediator of preadipocyte proliferation, differentiation, and survival. Results from clinical studies on GH treatment in patients with GH deficiency or GH insensitivity syndrome can be used to dissect GH and IGF as well as IGF-binding protein (IGFBP) actions in vivo. In this article, changes of the GH/IGF system during adipocyte differentiation in vitro as well as related signaling pathways and their impact on adipose tissue growth and function are discussed. Clinical considerations include the effects of GH and IGF-I on adipose tissue during treatment of GH deficiency, differences in the IGF system between visceral and subcutaneous adipose tissue depots as well as the recently emerging role for adipose tissue in the regulation of glucose homeostasis.
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Affiliation(s)
- A Garten
- Department of Women and Child Health, Hospital for Children and Adolescents, Center for Pediatric Research Leipzig, University Hospitals, Liebigstraße 20a, 04103 Leipzig, Germany
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25
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Fischer-Posovszky P, Keuper M, Nagel S, Hesse D, Schürmann A, Debatin KM, Strauss G, Wabitsch M. Downregulation of FLIP by cycloheximide sensitizes human fat cells to CD95-induced apoptosis. Exp Cell Res 2011; 317:2200-9. [DOI: 10.1016/j.yexcr.2011.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 06/23/2011] [Accepted: 06/25/2011] [Indexed: 10/18/2022]
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26
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Bogazzi F, Russo D, Raggi F, Bohlooly-Y M, Tornell J, Sardella C, Lombardi M, Urbani C, Manetti L, Brogioni S, Martino E. Cardiac extrinsic apoptotic pathway is silent in young but activated in elder mice overexpressing bovine GH: interplay with the intrinsic pathway. J Endocrinol 2011; 210:231-8. [PMID: 21565853 DOI: 10.1530/joe-10-0402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Apoptosis may occur through the mitochondrial (intrinsic) pathway and activation of death receptors (extrinsic pathway). Young acromegalic mice have reduced cardiac apoptosis whereas elder animals have increased cardiac apoptosis. Multiple intrinsic apoptotic pathways have been shown to be modulated by GH and other stimuli in the heart of acromegalic mice. However, the role of the extrinsic apoptotic pathways in acromegalic hearts is currently unknown. In young (3-month-old) acromegalic mice, expression of proteins of the extrinsic apoptotic pathway did not differ from that of wild-type animals, suggesting that this mechanism did not participate in the lower cardiac apoptosis levels observed at this age. On the contrary, the extrinsic pathway was active in elder (9-month-old) animals (as shown by increased expression of TRAIL, FADD, TRADD and increased activation of death inducing signaling complex) leading to increased levels of active caspase 8. It is worth noting that changes of some pro-apoptotic proteins were induced by GH, which seemed to have, in this context, pro-apoptotic effects. The extrinsic pathway influenced the intrinsic pathway by modulating t-Bid, the cellular levels of which were reduced in young and increased in elder animals. However, in young animals this effect was due to reduced levels of Bid regulated by the extrinsic pathway, whereas in elder animals the increased levels of t-Bid were due to the increased levels of active caspase 8. In conclusion, the extrinsic pathway participates in the cardiac pro-apoptotic phenotype of elder acromegalic animals either directly, enhancing caspase 8 levels or indirectly, increasing t-Bid levels and conveying death signals to the intrinsic pathway.
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Affiliation(s)
- Fausto Bogazzi
- Department of Endocrinology and Metabolism, University of Pisa, Ospedale Cisanello, Via Paradisa, 2, 56124 Pisa, Italy.
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27
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Keuper M, Blüher M, Schön MR, Möller P, Dzyakanchuk A, Amrein K, Debatin KM, Wabitsch M, Fischer-Posovszky P. An inflammatory micro-environment promotes human adipocyte apoptosis. Mol Cell Endocrinol 2011; 339:105-13. [PMID: 21501656 DOI: 10.1016/j.mce.2011.04.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/30/2011] [Accepted: 04/01/2011] [Indexed: 02/08/2023]
Abstract
Obesity-associated macrophage infiltration into adipose tissue is responsible for both local and systemic inflammation. Recent findings suggest fat cell apoptosis as an initiator of macrophage recruitment. Here, we investigated the effects of an inflammatory micro-environment on fat cells using human THP-1 macrophages and SGBS adipocytes. Macrophage-secreted factors induced insulin resistance, inhibited insulin-stimulated Akt phosphorylation, and induced apoptosis of adipocytes. The apoptosis-inducing effect was even more pronounced in direct co-cultures of adipocytes and macrophages. Our data suggest a link between insulin resistance and apoptosis sensitivity. Accordingly, pharmacological and genetic inhibition of insulin signaling at the level of Akt2 sensitized adipocytes to apoptosis induction by macrophage-secreted factors. In conclusion, we describe here a novel interaction of macrophages and fat cells, i.e. induction of apoptosis. Our data suggest a feed-forward cycle in which macrophages further drive the inflammatory process by inducing insulin resistance and concomitant apoptosis of adipocytes.
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Affiliation(s)
- Michaela Keuper
- Division of Pediatric Endocrinology, Diabetes and Obesity Unit, Department of Pediatrics and Adolescent Medicine, Ulm University, Eythstr. 24, 89075 Ulm, Germany
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28
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Limited fatty infiltration due to apoptosis in human degenerated temporomandibular joint disks: an immunohistochemical study. J Craniofac Surg 2011; 21:1508-11. [PMID: 20856040 DOI: 10.1097/scs.0b013e3181ef2dc9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In this study, we hypothesized that caspase 3, which plays a central role in the execution phase of cell apoptosis, could be involved in limiting fatty degeneration of the temporomandibular joint (TMJ) disks and therefore inhibit the TMJ disk tissue from completely degenerating into fatty tissue. Therefore, caspase 3 immunohistochemical expression in human TMJ degenerated disks was studied. Fifty-nine degenerated TMJ disks were stained with Harry's hematoxylin, and they were then examined with light microscopy to detect any pathologic changes typical of fatty degeneration. Sections from the same TMJ disk were immunostained also by a polyclonal anti-caspase 3 antibody. On morphologic observations, 11 disks of 59 degenerated ones also presented a fatty infiltration. Immunostaining with caspase 3 antibody was detected on adipocytes in the cytoplasm as well as the nuclei. Our results sustain the hypothesis that fatty degeneration is limited by apoptosis, being adipocytes immunolabeled by caspase 3 antibody. Hence, apart from the several factors that can trigger degeneration changes in TMJ disk, their appearance, spread, and permanence, at least for fatty degeneration, seem to be influenced by apoptosis.
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Keuper M, Dzyakanchuk A, Amrein KE, Wabitsch M, Fischer-Posovszky P. THP-1 Macrophages and SGBS Adipocytes - A New Human in vitro Model System of Inflamed Adipose Tissue. Front Endocrinol (Lausanne) 2011; 2:89. [PMID: 22645513 PMCID: PMC3355855 DOI: 10.3389/fendo.2011.00089] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/15/2011] [Indexed: 11/13/2022] Open
Abstract
Obesity is associated with an accumulation of macrophages in adipose tissue. This inflammation of adipose tissue is a key event in the pathogenesis of several obesity-related disorders, particularly insulin resistance. Here, we summarized existing model systems that mimic the situation of inflamed adipose tissue in vitro, most of them being murine. Importantly, we introduce our newly established human model system which combines the THP-1 monocytic cell line and the preadipocyte cell strain Simpson-Golabi-Behmel syndrome (SGBS). THP-1 cells, which originate from an acute monocytic leukemia, differentiate easily into macrophages in vitro. The human preadipocyte cell strain SGBS was recently introduced as a unique tool to study human fat cell functions. SGBS cells are characterized by a high capacity for adipogenic differentiation. SGBS adipocytes are capable of fat cell-specific metabolic functions such as insulin-stimulated glucose uptake, insulin-stimulated de novo lipogenesis and β-adrenergic-stimulated lipolysis and they secrete typical adipokines including leptin, adiponectin, and RBP4. Applying either macrophage-conditioned medium or a direct co-culture of macrophages and fat cells, our model system can be used to distinguish between paracrine and cell-contact dependent effects. In conclusion, we propose this model as a useful tool to study adipose inflammation in vitro. It represents an inexpensive, highly reproducible human system. The methods described here can be easily extended for usage of primary human macrophages and fat cells.
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Affiliation(s)
- Michaela Keuper
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm UniversityUlm, Germany
| | - Anna Dzyakanchuk
- Pharmaceutical Research and Early Development, F. Hoffmann-La Roche Ltd.Basel, Switzerland
| | - Kurt E. Amrein
- Pharmaceutical Research and Early Development, F. Hoffmann-La Roche Ltd.Basel, Switzerland
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm UniversityUlm, Germany
- *Correspondence: Martin Wabitsch, Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm University, Eythstr 24, 89075 Ulm, Germany. e-mail:
| | - Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, Ulm UniversityUlm, Germany
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Wang T, Si Y, Shirihai OS, Si H, Schultz V, Corkey RF, Hu L, Deeney JT, Guo W, Corkey BE. Respiration in adipocytes is inhibited by reactive oxygen species. Obesity (Silver Spring) 2010; 18:1493-502. [PMID: 20035277 PMCID: PMC6154476 DOI: 10.1038/oby.2009.456] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It is a desirable goal to stimulate fuel oxidation in adipocytes and shift the balance toward less fuel storage and more burning. To understand this regulatory process, respiration was measured in primary rat adipocytes, mitochondria, and fat-fed mice. Maximum O(2) consumption, in vitro, was determined with a chemical uncoupler of oxidative phosphorylation (carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP)). The adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio was measured by luminescence. Mitochondria were localized by confocal microscopy with MitoTracker Green and their membrane potential (Delta psi(M)) measured using tetramethylrhodamine ethyl ester perchlorate (TMRE). The effect of N-acetylcysteine (NAC) on respiration and body composition in vivo was assessed in mice. Addition of FCCP collapsed Delta psi(M) and decreased the ATP/ADP ratio. However, we demonstrated the same rate of adipocyte O(2) consumption in the absence or presence of fuels and FCCP. Respiration was only stimulated when reactive oxygen species (ROS) were scavenged by pyruvate or NAC: other fuels or fuel combinations had little effect. Importantly, the ROS scavenging role of pyruvate was not affected by rotenone, an inhibitor of mitochondrial complex I. In addition, mice that consumed NAC exhibited increased O(2) consumption and decreased body fat in vivo. These studies suggest for the first time that adipocyte O(2) consumption may be inhibited by ROS, because pyruvate and NAC stimulated respiration. ROS inhibition of O(2) consumption may explain the difficulty to identify effective strategies to increase fat burning in adipocytes. Stimulating fuel oxidation in adipocytes by decreasing ROS may provide a novel means to shift the balance from fuel storage to fuel burning.
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Affiliation(s)
- Tong Wang
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Yaguang Si
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Orian S. Shirihai
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Huiqing Si
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Vera Schultz
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Richard F. Corkey
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Liping Hu
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jude T. Deeney
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Wen Guo
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Barbara E. Corkey
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, USA
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Genetic variation in APOJ, LPL, and TNFRSF10B affects plasma fatty acid distribution in Alaskan Eskimos. Am J Clin Nutr 2010; 91:1574-83. [PMID: 20410100 PMCID: PMC2869509 DOI: 10.3945/ajcn.2009.28927] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Alterations in plasma fatty acid distribution are linked to metabolic abnormalities related to type 2 diabetes and cardiovascular disease. OBJECTIVE The aim of this study was to investigate genetic factors influencing plasma fatty acid distribution in Alaskan Eskimos from the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) study. DESIGN Fatty acids in plasma were measured by gas chromatography in 761 related individuals (>35 y of age). RESULTS Quantitative genetic analyses showed that fatty acid distribution is significantly heritable (P < 0.001), with heritabilities ranging from 0.33 to 0.55. A genome-wide scan for plasma fatty acids identified a 20-cM region on chromosome 8 (p12-p21) with a quantitative trait locus for monounsaturated fatty acids (logarithm of odds score = 3.8). The same region had a quantitative trait locus for polyunsaturated fatty acids (logarithm of odds score = 2.6). We genotyped single nucleotide polymorphisms (SNPs) in candidate genes in 8p12-p21 and found a significant association between fatty acids and SNPs in apolipoprotein J (APOJ), lipoprotein lipase (LPL), macrophage scavenger receptor 1 (MSR1), and tumor necrosis factor receptor superfamily member 10b (TNFRSF10B). A Bayesian quantitative trait nucleotide analysis based on a measured genotype model showed that SNPs in LPL, TNFRSF10B, and APOJ had strong statistical evidence of a functional effect (posterior probability > or =75%) on plasma fatty acid distribution. CONCLUSIONS The results indicate that there is strong genetic influence on plasma fatty acid distribution and that genetic variation in APOJ, LPL, and TNFRSF10B may play a role. The GOCADAN study was registered at www.clinicaltrials.gov as NCT00006192.
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Affiliation(s)
- Lionel Hebbard
- Storr Liver Unit, Westmead Millennium InstituteThe University of Sydney and Westmead Hospital Westmead, NSW, Australia
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Ito M, Nagasawa M, Hara T, Ide T, Murakami K. Differential roles of CIDEA and CIDEC in insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. J Lipid Res 2010; 51:1676-84. [PMID: 20154362 DOI: 10.1194/jlr.m002147] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Both insulin and the cell death-inducing DNA fragmentation factor-alpha-like effector (CIDE) family play important roles in apoptosis and lipid droplet formation. However, regulation of the CIDE family by insulin and the contribution of the CIDE family to insulin actions remain unclear. Here, we investigated whether insulin regulates expression of the CIDE family and which subtypes contribute to insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. Insulin decreased CIDEA and increased CIDEC but not CIDEB mRNA expression. Starvation-induced apoptosis in adipocytes was significantly inhibited when insulin decreased the CIDEA mRNA level. Small interfering RNA-mediated depletion of CIDEA inhibited starvation-induced apoptosis similarly to insulin and restored insulin deprivation-reduced adipocyte number, whereas CIDEC depletion did not. Lipid droplet size of adipocytes was increased when insulin increased the CIDEC mRNA level. In contrast, insulin-induced enlargement of lipid droplets was markedly abrogated by depletion of CIDEC but not CIDEA. Furthermore, depletion of CIDEC, but not CIDEA, significantly increased glycerol release from adipocytes. These results suggest that CIDEA and CIDEC are novel genes regulated by insulin in human adipocytes and may play key roles in the effects of insulin, such as anti-apoptosis and lipid droplet formation.
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Affiliation(s)
- Minoru Ito
- Discovery Research Laboratories, Kyorin Pharmaceutical Co. Ltd., 2399-1, Nogi, Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan
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Mader I, Wabitsch M, Debatin KM, Fischer-Posovszky P, Fulda S. Identification of a novel proapoptotic function of resveratrol in fat cells: SIRT1-independent sensitization to TRAIL-induced apoptosis. FASEB J 2010; 24:1997-2009. [PMID: 20097879 DOI: 10.1096/fj.09-142943] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The phytochemical resveratrol has recently gained attention for its protection against metabolic disease and for extension of life span, which have been linked to its metabolic effects and SIRT1 activation in fat cells. However, little is known about the effect of resveratrol on fat cell apoptosis. Here, we identify a novel, SIRT1-independent mechanism by which resveratrol regulates fat cell numbers. We demonstrate for the first time that resveratrol enhances TNF-related apoptosis-inducing ligand (TRAIL)- or CD95-induced apoptosis of human preadipocytes in a highly synergistic manner (EC(50) at 72 h: resveratrol, >300 microM; TRAIL, >100 ng/ml; combination: 30 microM resveratrol and 10 ng/ml TRAIL, combination index 0.4). Similar results in primary human preadipocytes prepared from subcutaneous white adipose tissue and mature human adipocytes underline the relevance to human physiology. Mechanistic studies reveal that resveratrol inhibits PI3K-driven phosphorylation of Akt, leading to increased Bax activation, loss of mitochondrial membrane potential, cytochrome c release, and caspase-dependent apoptosis. The synergistic interaction of resveratrol and TRAIL depends on the intrinsic apoptosis pathway and caspases, since Bcl-2 overexpression and the caspase inhibitor zVAD.fmk inhibit apoptosis, whereas knockdown of SIRT1 by RNA interference has no effect. The discovery of this novel activity of resveratrol significantly advances the knowledge of fat tissue regulation by resveratrol and has important implications for its use in metabolic and age-related diseases.
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Baxter RC, Twigg SM. Actions of IGF binding proteins and related proteins in adipose tissue. Trends Endocrinol Metab 2009; 20:499-505. [PMID: 19801194 DOI: 10.1016/j.tem.2009.07.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 12/14/2022]
Abstract
The insulin-like growth factors (IGFs), their binding proteins (IGFBPs) and structurally related proteins have been identified in adipose tissue but their roles in adipose tissue are poorly understood. IGF-I and IGFBP-3 expression increase during human preadipocyte differentiation. However, whereas IGF-I stimulates this process, IGFBP-3 is inhibitory both to preadipocyte differentiation and to differentiated adipocyte function. The direct interaction of IGFBP-3 with peroxisome proliferator-activated receptor-gamma is believed to contribute to its inhibitory effect on differentiation. Connective tissue growth factor (CTGF/CCN2) shares weak structural homology and functional similarities with IGFBP-3, including inhibition of preadipocyte differentiation. This review examines the current knowledge of IGFBP regulation and actions in adipocytes and proposes a common regulatory pathway involving IGFBP-3 and CTGF/CCN2.
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Affiliation(s)
- Robert C Baxter
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards NSW 2065, Australia.
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Wueest S, Rapold RA, Schumann DM, Rytka JM, Schildknecht A, Nov O, Chervonsky AV, Rudich A, Schoenle EJ, Donath MY, Konrad D. Deletion of Fas in adipocytes relieves adipose tissue inflammation and hepatic manifestations of obesity in mice. J Clin Invest 2009; 120:191-202. [PMID: 19955656 DOI: 10.1172/jci38388] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Accepted: 09/30/2009] [Indexed: 02/06/2023] Open
Abstract
Adipose tissue inflammation is linked to the pathogenesis of insulin resistance. In addition to exerting death-promoting effects, the death receptor Fas (also known as CD95) can activate inflammatory pathways in several cell lines and tissues, although little is known about the metabolic consequence of Fas activation in adipose tissue. We therefore sought to investigate the contribution of Fas in adipocytes to obesity-associated metabolic dysregulation. Fas expression was markedly increased in the adipocytes of common genetic and diet-induced mouse models of obesity and insulin resistance, as well as in the adipose tissue of obese and type 2 diabetic patients. Mice with Fas deficiency either in all cells or specifically in adipocytes (the latter are referred to herein as AFasKO mice) were protected from deterioration of glucose homeostasis induced by high-fat diet (HFD). Adipocytes in AFasKO mice were more insulin sensitive than those in wild-type mice, and mRNA levels of proinflammatory factors were reduced in white adipose tissue. Moreover, AFasKO mice were protected against hepatic steatosis and were more insulin sensitive, both at the whole-body level and in the liver. Thus, Fas in adipocytes contributes to adipose tissue inflammation, hepatic steatosis, and insulin resistance induced by obesity and may constitute a potential therapeutic target for the treatment of insulin resistance and type 2 diabetes.
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Affiliation(s)
- Stephan Wueest
- Division of Pediatric Endocrinology and Diabetology, University Children's Hospital, Steinwiesstrasse 75, Zurich, Switzerland
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Zhang L, Reidy SP, Nicholson TE, Lee HJ, Majdalawieh A, Webber C, Stewart BR, Dolphin P, Ro HS. The role of AEBP1 in sex-specific diet-induced obesity. Mol Med 2009; 11:39-47. [PMID: 16307171 PMCID: PMC1449517 DOI: 10.2119/2005-00021.ro] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2005] [Accepted: 10/24/2005] [Indexed: 12/22/2022] Open
Abstract
Obesity is an important risk factor for heart disease, diabetes, and certain cancers, but the molecular basis for obesity is poorly understood. The transcriptional repressor AEBP1, which functions as a negative regulator of PTEN through a protein-protein interaction, is highly expressed in the stromal compartment of adipose tissues, including proliferative preadipocytes, and its expression is abolished in terminally differentiated, nonproliferative adipocytes. Here we show that transgenic overexpression of AEBP1 during adipogenesis coupled with a high-fat diet (HFD) resulted in massive obesity in female transgenic (AEBP1(TG)) mice via adipocyte hyperplasia. AEBP1 levels dynamically changed with aging, and HFD induced AEBP1 expression in females. Thus, HFD-fed AEBP1(TG) females display hyperinduction of AEBP1 and a marked reduction of PTEN level with concomitant hyperactivation of the survival signal in white adipose tissue. Our results suggest that AEBP1 plays a key functional role in in vivo modulation of adiposity via fat-cell proliferation and is involved in a sex-specific susceptibility to diet-induced obesity by the estrogen signaling pathway.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Hyo-Sung Ro
- Address correspondence and reprint requests to Hyo-Sung Ro, Department of Biochemistry & Molecular Biology, Faculty of Medicine, Dalhousie University, Tupper Medical Building, 1850 College Street, Halifax, NS, B3H 1X5 Canada. Phone: 902-494-2367; fax 902-494-1355; e-mail:
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Bäck K, Arnqvist HJ. Changes in insulin and IGF-I receptor expression during differentiation of human preadipocytes. Growth Horm IGF Res 2009; 19:101-111. [PMID: 18693051 DOI: 10.1016/j.ghir.2008.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 06/18/2008] [Accepted: 06/27/2008] [Indexed: 01/02/2023]
Abstract
Mature adipocytes originate from fibroblast-like precursor cells, preadipocytes, which differentiate to obtain the characteristics of adipocytes. Our aim was to investigate how differentiation of human preadipocytes affects the distribution of insulin receptors (IR) and IGF-I receptors (IGF-IR) and other cell characteristics. Preadipocytes were differentiated using indomethacine, dexamethasone, isobutyl-methylxantine (IBMX) and high concentration of insulin. Gene expression was quantified by real-time RT-PCR in preadipocytes (PA), differentiated preadipocytes (dPA) and mature adipocytes (mAD). The amount of expressed receptor protein was analyzed using receptor specific ELISAs and Western blot. We also studied DNA synthesis with radiolabeled thymidine incorporation and glucose accumulation with radiolabeled glucose. Differentiation of PA increased gene expression of IR but not IGF-IR. GLUT4, growth hormone receptor (GHR) and adiponectin appeared or increased. In PA and dPA only IR-A was expressed whereas also IR-B was detected in mAD. By Western blot and ELISA, IR and IGF-IR were detected in PA, dPA and mAD. During differentiation the ratio of IR to IGF-IR increased severalfold. In PA both the IR and the IGF-IR was phosphorylated by their own ligand at 1 nM and in dPA the activation of both receptors was stimulated by IGF-I, but not insulin, at 1 nM. Accumulation of glucose in PA was increased by insulin at 10nM and by IGF-I at 1 nM and 10nM. DNA synthesis was increased by insulin and IGF-I at 10nM. In conclusion, both IR and IGF-IR are present in human preadipocytes and adipocytes. Differentiation is characterized by an increased IR/IGF-IR ratio.
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Affiliation(s)
- Karolina Bäck
- Linköping University, Faculty of Health Sciences, Department of Clinical and Experimental Medicine, Division of Cell Biology, S-581 85 Linköping, Sweden.
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Cyclooxygenase-2 inhibition reverts the decrease in adiponectin levels and attenuates the loss of white adipose tissue during chronic inflammation. Eur J Pharmacol 2009; 608:97-103. [DOI: 10.1016/j.ejphar.2009.02.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 02/13/2009] [Indexed: 12/21/2022]
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Wang HJ, Tashiro SI, Onodera S, Ikejima T. Inhibition of insulin-like growth factor 1 receptor signaling enhanced silibinin-induced activation of death receptor and mitochondrial apoptotic pathways in human breast cancer MCF-7 cells. J Pharmacol Sci 2008; 107:260-9. [PMID: 18635919 DOI: 10.1254/jphs.08054fp] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Silibinin, which had been used as a hepatoprotectant, was shown to have anticancer activity. In this study we investigated the mechanisms of silibinin-induced apoptosis in human breast cancer MCF-7 cells. Expressions of Fas ligand (FasL), Fas-associated death domain protein (FADD), and Bax were significantly up-regulated in silibinin-treated cells, whilst silibinin induced a conspicuous translocation of Bax to mitochondria and release of cytochrome c to the cytosol. Therefore, both the extrinsic Fas death receptor and intrinsic mitochondrial death pathways played essential roles in silibinin-induced apoptosis. It was also found that silibinin markedly decreased protein expression of SIRT1, a mammalian homologue of yeast Sir2, which was proved to have a role in sequestering Bax away from mitochondria. Insulin-like growth factor 1 receptor (IGF-1R), a receptor tyrosine kinase with a crucial role in malignancy development, is expressed in most human primary breast carcinomas. Our results showed that silibinin-induced apoptosis was significantly reinforced by blocking IGF-1R signaling with tyrphostin AG1024, a specific inhibitor of IGF-1R autophosphorylation. Up-regulation of FADD, down-regulation of SIRT1 expression, and activation of the mitochondrial death pathway were apparently enhanced by AG1024 in the silibinin-treated MCF-7 cells.
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Affiliation(s)
- Hong-Jun Wang
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang, China
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Genetic polymorphisms differently influencing the emergence of atrophy and fat accumulation in HIV-related lipodystrophy. AIDS 2008; 22:1769-78. [PMID: 18753860 DOI: 10.1097/qad.0b013e32830b3a96] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE AND DESIGN The present study aims at evaluating the influence of genetic polymorphisms on antiretroviral therapy (ART)-associated lipodystrophy. We included in the study 255 ICoNA. patients and we assessed the distribution of Fas -670 AG polymorphism, ApoC3 -455 CT and -482 CT polymorphisms, C161T silent substitution in the PPAR gamma gene, the Adrenergic beta3 Receptor (ARbeta3) codon 64 TC variant, and two polymorphisms in the Adrenergic beta2 Receptor (ARbeta2) codon 16 AG and codon 27 CG. Crude rates of lipoatrophy and fat accumulation and adjusted relative rates were calculated using Poisson regression. RESULTS In a multivariate model after adjusting for gender, HIV exposure, age, current viral load, hepatitis C virus (HCV) serology, nucleoside reverse-transcriptase inhibitor (NRTI) pair/'third drugs' currently used, months of pre-highly active antiretroviral therapy (HAART) exposures to NRTI, the following genotypes resulted protective against lipoatrophy: ApoC3 -455 CC genotype [adjusted relative risks (ARR) 0.2, 95% confidence interval (CI) 0.046-0.91 vs CT/TT, P = 0.037], ARbeta3 codon 64 TT genotype (ARR 0.39, 95% CI 0.14-1.06 vs TC/CC, P = 0.066), and Fas -670 GG genotype (ARR 0.51, 95% CI 0.26-1.01 vs AG/AA, P = 0.053). With regard to fat accumulation, in the multivariate model, the ARbeta2 codon 27 CC genotype resulted protective (ARR 0.21, 95% CI 0.08-0.51 vs CG/GG, P = 0.0006), whereas the ARbeta2 codon 16 AA genotype resulted associated with higher risk (ARR 3.72, 95% CI 1.58-8.76 vs AG/GG, P = 0.0026). CONCLUSION Our study suggests that genetic polymorphisms of genes involved in apoptosis and adipocyte metabolism are significantly related to ART associated lipodystrophy. Particularly, we evidenced a role for ApoC3 -455 in lipoatrophy and for the two variants of ARbeta2 in fat accumulation.
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Freda PU, Shen W, Heymsfield SB, Reyes-Vidal CM, Geer EB, Bruce JN, Gallagher D. Lower visceral and subcutaneous but higher intermuscular adipose tissue depots in patients with growth hormone and insulin-like growth factor I excess due to acromegaly. J Clin Endocrinol Metab 2008; 93:2334-43. [PMID: 18349062 PMCID: PMC2435633 DOI: 10.1210/jc.2007-2780] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
CONTEXT GH and IGF-I are important regulators of metabolism and body composition. In acromegaly, a state of GH and IGF-I excess, the lipolytic and insulin antagonistic effects of GH may alter adipose tissue (AT) distribution. OBJECTIVES Our objective was to test the hypothesis that in acromegaly whole-body AT mass is less and to examine for the first time the relationship between GH/IGF-I excess and intermuscular AT (IMAT), an AT depot associated with insulin resistance in other populations. DESIGN, SETTING, AND PATIENTS We conducted a cross-sectional study in 24 adults with active acromegaly compared with predicted models developed in 315 healthy non-acromegaly subjects. OUTCOME MEASURES Mass of AT in the visceral AT (VAT), sc AT (SAT), and IMAT compartments from whole-body magnetic resonance imaging and serum levels of GH, IGF-I, insulin, and glucose were measured. RESULTS VAT and SAT were less in active acromegaly (P < 0.0001); these were 68.2 +/- 27% and 79.5 +/- 15% of predicted values, respectively. By contrast, IMAT was greater (P = 0.0052) by 185.6 +/- 84% of predicted. VAT/trunk AT ratios were inversely related to IGF-I levels (r = 0.544; P = 0.0054). Acromegaly subjects were insulin resistant. CONCLUSIONS VAT and SAT, most markedly VAT, are less in acromegaly. The proportion of trunk AT that is VAT is less with greater disease activity. IMAT is greater in acromegaly, a novel finding, which suggests that increased AT in muscle could be associated with GH-induced insulin resistance. These findings have implications for understanding the role of GH in body composition and metabolic risk in acromegaly and other clinical settings of GH use.
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Affiliation(s)
- Pamela U Freda
- Department of Medicine, Columbia University, College of Physicians and Surgeons, 650 West 168th Street, New York, NY 10032, USA.
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Kubota Y, Unoki H, Bujo H, Rikihisa N, Udagawa A, Yoshimoto S, Ichinose M, Saito Y. Low-dose GH supplementation reduces the TLR2 and TNF-α expressions in visceral fat. Biochem Biophys Res Commun 2008; 368:81-7. [DOI: 10.1016/j.bbrc.2008.01.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2008] [Accepted: 01/09/2008] [Indexed: 01/08/2023]
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Wabitsch M, Fischer-Posovszky P. Grundlagen der Fettgewebsforschung und Adipozytokine. GYNAKOLOGISCHE ENDOKRINOLOGIE 2008. [DOI: 10.1007/s10304-007-0226-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Fischer-Posovszky P, Newell FS, Wabitsch M, Tornqvist HE. Human SGBS cells - a unique tool for studies of human fat cell biology. Obes Facts 2008; 1:184-9. [PMID: 20054179 PMCID: PMC6452113 DOI: 10.1159/000145784] [Citation(s) in RCA: 201] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The human Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte cell strain provides a unique and useful tool for studies of human adipocyte biology. The cells originate from an adipose tissue specimen of a patient with SGBS. They are neither transformed nor immortalized, and provide an almost unlimited source due to their ability to proliferate for up to 50 generations with retained capacity for adipogenic differentiation. So far, the cells have been used for a number of studies on adipose differentiation, adipocyte glucose uptake, lipolysis, apoptosis, regulation of expression of adipokines, and protein translocation. The cells are efficiently differentiated in the presence of PPARgammaagonists and in the absence of serum and albumin. SGBS adipocytes respond to insulin stimulation by increasing glucose uptake several-fold (EC50 approximately 100 pmol/l), and by very effectively inhibiting (IC50 approximately 10 pmol/l) catecholamine-stimulated lipolysis.
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Affiliation(s)
- Pamela Fischer-Posovszky
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, University of Ulm, Germany
| | - Felicity S. Newell
- Diamantina Institute for Cancer, Immunology and Metabolic Medicine, University of Queensland, Brisbane, Queensland, Australia
| | - Martin Wabitsch
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics and Adolescent Medicine, University of Ulm, Germany
- *Prof. Dr. Martin Wabitsch, Department of Pediatrics and Adolescent Medicine, Division of Pediatric Endocrinology and Diabetes, University of Ulm, Eythstr. 24, 89075 Ulm, Germany, Tel./Fax +49 731 500 57402,
| | - Hans E. Tornqvist
- Department of Clinical Sciences, Diabetes and Endocrinology, Malmö University Hospital, Lund University, Sweden*
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Hilmi C, Larribere L, Giuliano S, Bille K, Ortonne JP, Ballotti R, Bertolotto C. IGF1 promotes resistance to apoptosis in melanoma cells through an increased expression of BCL2, BCL-X(L), and survivin. J Invest Dermatol 2007; 128:1499-505. [PMID: 18079751 DOI: 10.1038/sj.jid.5701185] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
IGF1 plays a key role in the development and growth of multiple tumors and in the prevention of apoptosis. In melanoma cells, IGF1 has been shown to mediate resistance to anoikis-induced apoptosis. However, the effect of IGF1 on other proapoptotic stimuli has never been reported. Further, the molecular mechanisms by which IGF1 mediates its prosurvival properties in melanoma cells remain unknown. Here, we demonstrate that IGF1 impairs the onset of tumor necrosis factor-related apoptosis-inducing ligand and staurosporine-induced apoptosis in melanoma cells expressing either wild-type or oncogenic B-Raf. Further, we show that IGF1 inhibits mitochondrial damage that occurs during apoptosis, thereby indicating that IGF1 acts at the level of mitochondria to mediate its antiapoptotic stimuli. Accordingly, IGF1 increases the mRNA levels and protein expression of antiapoptotic members of the BCL2 family--BCL2 and BCL-X(L)--and that of the inhibitor of apoptosis protein, survivin. Further, their specific silencing by small interfering RNA prevents the protective effect of IGF1. These findings therefore delineate the molecular mechanisms by which IGF1 mediates its prosurvival properties and provide a basis for clinical strategies designed to neutralize IGF1 or its target genes.
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Affiliation(s)
- Caroline Hilmi
- Institut National de la Santé et de la Recherche Médicale U597, Biologie et Pathologie des cellules mélanocytaires: de la pigmentation cutanée au mélanome, Nice, France
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Harrington M, Pond-Tor S, Boney CM. Role of epidermal growth factor and ErbB2 receptors in 3T3-L1 adipogenesis. Obesity (Silver Spring) 2007; 15:563-71. [PMID: 17372305 DOI: 10.1038/oby.2007.562] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE Epidermal growth factor (EGF) stimulates proliferation in 3T3-L1 preadipocytes, but EGF action in differentiation is less clear. EGF promotes differentiation at concentrations <1 nM but inhibits differentiation at higher concentrations, suggesting a dual role in adipogenesis. We hypothesized that differences in EGF receptor activation and downstream signaling mediate distinct biological effects of EGF at low vs. high abundance. RESEARCH METHODS AND PROCEDURES We compared the effects of low (0.1 nM) vs. high (10 nM) EGF on the activation of EGF receptors, proximal signaling molecules Src and Shc, and the downstream mitogen-activated protein kinase (MAPK) pathways extracellular regulated kinase (ERK) and p38 in proliferating and differentiated 3T3-L1 cells. RESULTS Both low and high EGF activated ERK and p38 in preadipocytes. Src inhibitors PP1 and PP2 blocked ERK and p38 activation by low but not high EGF, and only high EGF increased Shc phosphorylation. Selective inhibition of the EGF receptor (EGFR) with AG1478 blocked ERK and p38 activation at both concentrations; however, selective inhibition of the ErbB2 receptor (EB2R) with AG825 or small interfering RNA (siRNA) blocked low but not high EGF activation of ERK and p38. Coimmunoprecipitation of EGFR with EB2R and Src was observed with low EGF in preadipocytes but at both concentrations in adipocytes. EB2R inhibition during differentiation decreased p38 activity and peroxisome proliferator-activated receptor gamma (PPARgamma) abundance. DISCUSSION Our results show that EGFR homodimers mediate action of EGF at high abundance, but at low abundance, EGF promotes differentiation through EGFR/EB2R heterodimer activation of Src and p38. These results may partially explain the observations that high EGF concentrations inhibit, whereas low concentrations support, preadipocyte differentiation.
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Affiliation(s)
- Molly Harrington
- Department of Pediatrics, Rhode Island Hospital and Brown Medical School, Providence, Rhode Island 02903, USA
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Floyd ZE, Segura BM, He F, Stephens JM. Degradation of STAT5 proteins in 3T3-L1 adipocytes is induced by TNF-{alpha} and cycloheximide in a manner independent of STAT5A activation. Am J Physiol Endocrinol Metab 2007; 292:E461-8. [PMID: 16985255 DOI: 10.1152/ajpendo.00334.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine that has been implicated as a causative factor in obesity-linked insulin resistance. It is commonly accepted that macrophage-derived TNF-alpha acts in a paracrine manner on adjacent adipocytes to inhibit the expression of various adipocyte genes and to attenuate insulin signaling. Several studies have revealed that signal transducer and activator of transcription (STAT)5 proteins are modulated during adipogenesis and can modulate the transcription of some adipocyte genes. In this study, we demonstrate that TNF-alpha treatment, in the presence of cycloheximide, also results in the rapid turnover of STAT5A and STAT5B in a process that is independent of STAT5 activation by tyrosine phosphorylation. In addition, STAT5B is more labile than STAT5A under these conditions, suggesting that the COOH terminus of STAT5 may be involved in the turnover of each protein. Initial characterization of the TNF-alpha and cycloheximide-mediated degradation of STAT5 indicates that inhibition of the proteasome stabilizes both forms of STAT5 in the presence of TNF-alpha. In addition, the use of an NF-kappaB inhibitor results in the stabilization of STAT5A in the presence of TNF-alpha and cycloheximide, indicating that the degradation of STAT5 proteins under these conditions may involve the NF-kappaB pathway. STAT5 proteins are abundantly expressed in mature adipocytes and are normally extremely stable proteins under a wide range of conditions. However, our results demonstrate that the potentiation of TNF-alpha-mediated signaling in the presence of cyclohexmide is associated with a significant increase in the degradation of STAT5 proteins in 3T3-L1 adipocytes.
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Affiliation(s)
- Z Elizabeth Floyd
- Department of Biological Sciences, Louisiana State University, 202 Life Sciences Bldg., Baton Rouge, LA 70803, USA
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Ro HS, Zhang L, Majdalawieh A, Kim SW, Wu X, Lyons PJ, Webber C, Ma H, Reidy SP, Boudreau A, Miller JR, Mitchell P, McLeod RS. Adipocyte enhancer-binding protein 1 modulates adiposity and energy homeostasis. Obesity (Silver Spring) 2007; 15:288-302. [PMID: 17299101 DOI: 10.1038/oby.2007.569] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To determine whether adipocyte enhancer binding protein (AEBP) 1, a transcriptional repressor that is down-regulated during adipogenesis, functions as a critical regulator of adipose tissue homeostasis through modulation of phosphatase and tensin homolog deleted on chromosome ten (PTEN) tumor suppressor activity and mitogen-activated protein kinase (MAPK) activation. RESEARCH METHODS AND PROCEDURES We examined whether AEBP1 physically interacts with PTEN in 3T3-L1 cells by coimmunoprecipitation analysis. We generated AEBP1-null mice and examined the physiological role of AEBP1 as a key modulator of in vivo adiposity. Using adipose tissue from wild-type and AEBP1-null animals, we examined whether AEBP1 affects PTEN protein level. RESULTS AEBP1 interacts with PTEN, and deficiency of AEBP1 increases adipose tissue PTEN mass. AEBP1-null mice have reduced adipose tissue mass and enhanced apoptosis with suppressed survival signal. Primary pre-adipocytes from AEBP1-null adipose tissues exhibit lower basal MAPK activity with defective proliferative potential. AEBP1-null mice are also resistant to diet-induced obesity, suggesting a regulatory role for AEBP1 in energy homeostasis. DISCUSSION Our results suggest that AEBP1 negatively regulates adipose tissue PTEN levels, in conjunction with its role in proliferation and differentiation of pre-adipocytes, as a key functional role in modulation of in vivo adiposity.
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Affiliation(s)
- Hyo-Sung Ro
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
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Tchoukalova Y, Koutsari C, Jensen M. Committed subcutaneous preadipocytes are reduced in human obesity. Diabetologia 2007; 50:151-7. [PMID: 17096115 DOI: 10.1007/s00125-006-0496-9] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 09/07/2006] [Indexed: 01/03/2023]
Abstract
AIMS/HYPOTHESIS The aim of this study was to test whether the availability of committed preadipocytes in abdominal and femoral subcutaneous adipose tissue varies with obesity and body fat distribution. METHODS Body composition, fat cell size, committed preadipocytes and macrophages were measured in subcutaneous abdominal and femoral adipose depots of 17 lean, 16 upper-body-obese (UBO) and 13 lower-body-obese (LBO) women. Preadipocytes and macrophages were identified by simultaneous staining with the respective markers aP2 and CD68. In a subset of samples we measured preadipocyte proliferation, differentiation and susceptibility to apoptosis. RESULTS Abdominal adipocytes were smaller in lean than in obese women. Committed preadipocytes represented a greater fraction of stromovascular cells in lean than in obese women but were similar between UBO and LBO women (abdomen: approximately 30 +/- 3 vs approximately 17 +/- 2%; thigh: approximately 30 +/- 3 vs approximately 17 +/- 2%). Preliminary data suggested that preadipocyte kinetics were similar in LBO and lean women, whereas preadipocytes of UBO women differentiated less and were more susceptible to apoptotic stimuli. The fraction of stromovascular cells that were macrophages was greater in both depots in obese women (UBO and LBO) than in normal-weight women, but the difference was not statistically significant. CONCLUSIONS/INTERPRETATION The proportion of subcutaneous adipose tissue stromovascular cells that are committed preadipocytes is reduced with obesity. This could be due to greater recruitment of preadipocytes to adipogenesis or greater preadipocyte apoptosis, depending upon the obesity phenotype. These data are consistent with the concept that body fat distribution may be regulated partly through differences in adipogenesis.
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Affiliation(s)
- Y Tchoukalova
- Endocrine Research Unit, 5-194 Joseph, Mayo Clinic, Rochester, MN, 55905, USA
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