151
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Walsh CA, Qin L, Tien JCY, Young LS, Xu J. The function of steroid receptor coactivator-1 in normal tissues and cancer. Int J Biol Sci 2012; 8:470-85. [PMID: 22419892 PMCID: PMC3303173 DOI: 10.7150/ijbs.4125] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 02/20/2012] [Indexed: 11/05/2022] Open
Abstract
In 1995, the steroid receptor coactivator-1 (SRC-1) was identified as the first authentic steroid receptor coactivator. Since then, the SRC proteins have remained at the epicenter of coregulator biology, molecular endocrinology and endocrine-related cancer. Cumulative works on SRC-1 have shown that it is primarily a nuclear receptor coregulator and functions to construct highly specific enzymatic protein complexes which can execute efficient and successful transcriptional activation of designated target genes. The versatile nature of SRC-1 enables it to respond to steroid dependent and steroid independent stimulation, allowing it to bind across many families of transcription factors to orchestrate and regulate complex physiological reactions. This review highlights the multiple functions of SRC-1 in the development and maintenance of normal tissue functions as well as its major role in mediating hormone receptor responsiveness. Insights from genetically manipulated mouse models and clinical data suggest SRC-1 is significantly overexpressed in many cancers, in particular, cancers of the reproductive tissues. SRC-1 has been associated with cellular proliferation and tumor growth but its major tumorigenic contributions are promotion and execution of breast cancer metastasis and mediation of resistance to endocrine therapies. The ability of SRC-1 to coordinate multiple signaling pathways makes it an important player in tumor cells' escape of targeted therapy.
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Affiliation(s)
- Claire A Walsh
- Endocrine Oncology Research Group, Royal College of Surgeons in Ireland, Dublin, Ireland
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152
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Shetty S, Ramos-Roman MA, Cho YR, Brown J, Plutzky J, Muise ES, Horton JD, Scherer PE, Parks EJ. Enhanced fatty acid flux triggered by adiponectin overexpression. Endocrinology 2012; 153:113-22. [PMID: 22045665 PMCID: PMC3249680 DOI: 10.1210/en.2011-1339] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 09/30/2011] [Indexed: 12/30/2022]
Abstract
Adiponectin overexpression in mice increases insulin sensitivity independent of adiposity. Here, we combined stable isotope infusion and in vivo measurements of lipid flux with transcriptomic analysis to characterize fatty acid metabolism in transgenic mice that overexpress adiponectin via the aP2-promoter (ADNTg). Compared with controls, fasted ADNTg mice demonstrated a 31% reduction in plasma free fatty acid concentrations (P = 0.008), a doubling of ketones (P = 0.028), and a 68% increase in free fatty acid turnover in plasma (15.1 ± 1.5 vs. 25.3 ± 6.8 mg/kg · min, P = 0.011). ADNTg mice had 2-fold more brown adipose tissue mass, and triglyceride synthesis and turnover were 5-fold greater in this organ (P = 0.046). Epididymal white adipose tissue was slightly reduced, possibly due to the approximately 1.5-fold increase in the expression of genes involved in oxidation (peroxisome proliferator-activated receptor α, peroxisome proliferator-activated receptor-γ coactivator 1α, and uncoupling protein 3). In ADNTg liver, lipogenic gene expression was reduced, but there was an unexpected increase in the expression of retinoid pathway genes (hepatic retinol binding protein 1 and retinoic acid receptor beta and adipose Cyp26A1) and liver retinyl ester content (64% higher, P < 0.02). Combined, these data support a physiological link between adiponectin signaling and increased efficiency of triglyceride synthesis and hydrolysis, a process that can be controlled by retinoids. Interactions between adiponectin and retinoids may underlie adiponectin's effects on intermediary metabolism.
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Affiliation(s)
- Shoba Shetty
- Touchstone Diabetes Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9052, USA
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153
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Abstract
We here discuss the role of brown adipose tissue on energy homeostasis and assess its potential as a target for body weight management. Because of their high number of mitochondria and the presence of uncoupling protein 1, brown fat adipocytes can be termed as energy inefficient for adenosine-5'-triphosphate (ATP) production but energy efficient for heat production. Thus, the energy inefficiency of ATP production, despite high energy substrate oxidation, allows brown adipose tissue to generate heat for body temperature regulation. Whether such thermogenic property also plays a role in body weight regulation is still debated. The recent (re)discovery of brown adipose tissue in human adults and a better understanding of brown adipose tissue development have encouraged the quest for new alternatives to treat obesity since obese individuals seem to have less brown adipose tissue mass/activity than do their lean counterparts. In this review, we discuss the physiological relevance of brown adipose tissue on thermogenesis and its potential usefulness on body weight control in humans.
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Affiliation(s)
- Eric Ravussin
- Human Physiology, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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154
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Satyanarayana A, Klarmann KD, Gavrilova O, Keller JR. Ablation of the transcriptional regulator Id1 enhances energy expenditure, increases insulin sensitivity, and protects against age and diet induced insulin resistance, and hepatosteatosis. FASEB J 2011; 26:309-23. [PMID: 21990377 DOI: 10.1096/fj.11-190892] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Obesity is a major health concern that contributes to the development of diabetes, hyperlipidemia, coronary artery disease, and cancer. Id proteins are helix-loop-helix transcription factors that regulate the proliferation and differentiation of cells from multiple tissues, including adipocytes. We screened mouse tissues for the expression of Id1 and found that Id1 protein is highly expressed in brown adipose tissue (BAT) and white adipose tissue (WAT), suggesting a role for Id1 in adipogenesis and cell metabolism. Id1(-/-) mice are viable but show a significant reduction in fat mass (P<0.005) over the life of the animal that was not due to decreased number of adipocytes. Analysis of Id1(-/-) mice revealed higher energy expenditure, increased lipolysis, and fatty acid oxidation, resulting in reduced triglyceride accumulation in WAT compared to Id1(+/+) mice. Serum levels of triglycerides (193.9±32.2 vs. 86.5±33.8, P<0.0005), cholesterol (189.4±33.8 vs. 110.6±8.23, P<0.0005) and leptin (1263±835 vs. 222±260, P<0.005) were significantly lower in aged Id1(-/-) mice compared to Id1(+/+) mice. Id1-deficient mice have higher resting (P<0.005) and total (P<0.05) O(2) consumption and lower respiratory exchange ratio (P<0.005), confirming that Id1(-/-) mice use a higher proportion of lipid as an energy source for the increased energy expenditure. The expression of PGC1α and UCP1 were 2- to 3-fold up-regulated in Id1(-/-) BAT, suggesting that loss of Id1 increases thermogenesis. As a consequence of higher energy expenditure and reduced fat mass, Id1(-/-) mice displayed enhanced insulin sensitivity. Id1 deficiency protected mice against age- and high-fat-diet-induced adiposity, insulin resistance, and hepatosteatosis. Our findings suggest that Id1 plays a critical role in the regulation of energy homeostasis and could be a potential target in the treatment of insulin resistance and fatty liver disease.
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Affiliation(s)
- Ande Satyanarayana
- Center for Cancer Research, National Cancer, Institute-Frederick, Frederick, MD 21702-1201, USA
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155
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Cao L, Choi EY, Liu X, Martin A, Wang C, Xu X, During MJ. White to brown fat phenotypic switch induced by genetic and environmental activation of a hypothalamic-adipocyte axis. Cell Metab 2011; 14:324-38. [PMID: 21907139 PMCID: PMC3172615 DOI: 10.1016/j.cmet.2011.06.020] [Citation(s) in RCA: 291] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 05/07/2011] [Accepted: 06/21/2011] [Indexed: 12/12/2022]
Abstract
Living in an enriched environment with complex physical and social stimulation leads to improved cognitive and metabolic health. In white fat, enrichment induced the upregulation of the brown fat cell fate determining gene Prdm16, brown fat-specific markers, and genes involved in thermogenesis and β-adrenergic signaling. Moreover, pockets of cells with prototypical brown fat morphology and high UCP1 levels were observed in the white fat of enriched mice associated with resistance to diet-induced obesity. Hypothalamic overexpression of BDNF reproduced the enrichment-associated activation of the brown fat gene program and lean phenotype. Inhibition of BDNF signaling by genetic knockout or dominant-negative trkB reversed this phenotype. Our genetic and pharmacologic data suggest a mechanism whereby induction of hypothalamic BDNF expression in response to environmental stimuli leads to selective sympathoneural modulation of white fat to induce "browning" and increased energy dissipation.
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Affiliation(s)
- Lei Cao
- Department of Molecular Virology, Immunology, and Medical Genetics, The Ohio State University, Columbus, OH 43210, USA.
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156
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Weitzel JM, Iwen KA. Coordination of mitochondrial biogenesis by thyroid hormone. Mol Cell Endocrinol 2011; 342:1-7. [PMID: 21664416 DOI: 10.1016/j.mce.2011.05.009] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 04/28/2011] [Accepted: 05/15/2011] [Indexed: 01/15/2023]
Abstract
Thyroid hormone (TH) has profound influence on metabolism that is closely linked to its effect on mitochondrial biogenesis and function. After a single injection of TH into mammals, physiological alterations (e.g. changes in oxygen consumption rates) are detectable after a lag period of ∼48h. This characteristic lag period is somewhat surprising since non-genomic responses are already detectable within minutes, and first genomic responses within some hours after administration of TH. This review provides a model to explain the characteristic lag period: TH regulates a first series of TH target genes via classical activation of gene expression by binding to thyroid hormone response elements. Some directly regulated target genes serve as intermediate factors and subsequently regulate a second series of indirect TH target genes. Intermediate factors are transcription factors (such as NRF-1, NRF-2 and PPARγ) and transcriptional coactivators (such as PGC-1α and PGC-1β). In concert with several post-translational modifications, these intermediate factors orchestrate the physiological response to thyroid hormone in vivo.
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Affiliation(s)
- Joachim M Weitzel
- Forschungsbereich Fortpflanzungsbiologie, Leibniz-Institut für Nutztierbiologie, FBN Dummerstorf, Germany.
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157
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Deletion of steroid receptor coactivator-3 gene ameliorates hepatic steatosis. J Hepatol 2011; 55:445-52. [PMID: 21184786 DOI: 10.1016/j.jhep.2010.11.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/11/2010] [Accepted: 11/12/2010] [Indexed: 02/06/2023]
Abstract
BACKGROUND & AIMS Excess dietary fat can cause hepatic steatosis, which can progress into severe liver disorders including steatohepatitis and cirrhosis. Steroid receptor coactivator-3 (SRC-3), a member of the p160 coactivator family, is reported as a key regulator of adipogenesis and energy homeostasis. We sought to determine the influence of SRC-3 on hepatic steatosis and the mechanism beneath. METHODS The influence of siRNA-mediated SRC-3 silencing on hepatic lipid accumulation was assessed in HepG2 cells. The molecular mechanism of SRC-3 regulation of hepatic lipid metabolism was also studied. Moreover, the effect of SRC-3 ablation on hepatic steatosis was examined in SRC-3 deficient mice. RESULTS In this study, we report that SRC-3 ablation reduces palmitic acid-induced lipid accumulation in HepG2 cells. Moreover, deletion of SRC-3 ameliorates hepatic steatosis and inflammation response in mice fed a high fat diet (HFD). These metabolic improvements can presumably be explained by the reduction in chicken ovalbumin upstream promoter transcription factor II (COUP-TFII) expression and the subsequent elevation in peroxisome proliferator-activated receptor α (PPARα) level. At the molecular level, SRC-3 interacts with retinoic receptor α (RARα) to activate COUP-TFII expression under all-trans retinoic acid (ARTA) treatment. CONCLUSIONS These findings indicate a crucial role for SRC-3 in regulating hepatic lipid metabolism and provide the possible novel inner mechanisms.
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158
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Zaragosi LE, Wdziekonski B, Brigand KL, Villageois P, Mari B, Waldmann R, Dani C, Barbry P. Small RNA sequencing reveals miR-642a-3p as a novel adipocyte-specific microRNA and miR-30 as a key regulator of human adipogenesis. Genome Biol 2011; 12:R64. [PMID: 21767385 PMCID: PMC3218826 DOI: 10.1186/gb-2011-12-7-r64] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 05/05/2011] [Accepted: 07/18/2011] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND In severe obesity, as well as in normal development, the growth of adipose tissue is the result of an increase in adipocyte size and numbers, which is underlain by the stimulation of adipogenic differentiation of precursor cells. A better knowledge of the pathways that regulate adipogenesis is therefore essential for an improved understanding of adipose tissue expansion. As microRNAs (miRNAs) have a critical role in many differentiation processes, our study aimed to identify the role of miRNA-mediated gene silencing in the regulation of adipogenic differentiation. RESULTS We used deep sequencing to identify small RNAs that are differentially expressed during adipogenesis of adipose tissue-derived stem cells. This approach revealed the un-annotated miR-642a-3p as a highly adipocyte-specific miRNA. We then focused our study on the miR-30 family, which was also up-regulated during adipogenic differentiation and for which the role in adipogenesis had not yet been elucidated. Inhibition of the miR-30 family blocked adipogenesis, whilst over-expression of miR-30a and miR-30d stimulated this process. We additionally showed that both miR-30a and miR-30d target the transcription factor RUNX2, and stimulate adipogenesis via the modulation of this major regulator of osteogenesis. CONCLUSIONS Overall, our data suggest that the miR-30 family plays a central role in adipocyte development. Moreover, as adipose tissue-derived stem cells can differentiate into either adipocytes or osteoblasts, the down-regulation of the osteogenesis regulator RUNX2 represents a plausible mechanism by which miR-30 miRNAs may contribute to adipogenic differentiation of adipose tissue-derived stem cells.
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Affiliation(s)
- Laure-Emmanuelle Zaragosi
- Centre National de la Recherche Scientifique, Institut de Pharmacologie Moléculaire et Cellulaire, UMR-6097, 660 Route des Lucioles, Valbonne Sophia-Antipolis 06560, France
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159
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Zhang F, Lavan BE, Gregoire FM. Selective Modulators of PPAR-gamma Activity: Molecular Aspects Related to Obesity and Side-Effects. PPAR Res 2011; 2007:32696. [PMID: 17389769 PMCID: PMC1783742 DOI: 10.1155/2007/32696] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/21/2006] [Accepted: 11/22/2006] [Indexed: 01/23/2023] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a key regulator of lipid metabolism and energy balance implicated in the development of insulin resistance and obesity. The identification of putative natural and synthetic ligands and activators of PPAR-gamma has helped to unravel the molecular basis of its function, including molecular details regarding ligand binding, conformational changes of the receptor, and cofactor binding, leading to the emergence of the concept of selective PPAR-gamma modulators (SPPARgammaMs). SPPARgammaMs bind in distinct manners to the ligand-binding pocket of PPAR-gamma, leading to alternative receptor conformations, differential cofactor recruitment/displacement, differential gene expression, and ultimately differential biological responses. Based on this concept, new and improved antidiabetic agents for the treatment of diabetes are in development. This review summarizes the current knowledge on the mechanism of action and biological effects of recently characterized SPPARgammaMs, including metaglidasen/halofenate, PA-082, and the angiotensin receptor antagonists, recently characterized as a new class of SPPARgammaMs.
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Affiliation(s)
- Fang Zhang
- Department of Biology, Metabolex Inc., 3876 Bay Center Place, Hayward, CA 94545, USA
| | - Brian E. Lavan
- Department of Biology, Metabolex Inc., 3876 Bay Center Place, Hayward, CA 94545, USA
| | - Francine M. Gregoire
- Department of Biology, Metabolex Inc., 3876 Bay Center Place, Hayward, CA 94545, USA
- *Francine M. Gregoire:
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160
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Powell E, Kuhn P, Xu W. Nuclear Receptor Cofactors in PPARgamma-Mediated Adipogenesis and Adipocyte Energy Metabolism. PPAR Res 2011; 2007:53843. [PMID: 17389765 PMCID: PMC1783724 DOI: 10.1155/2007/53843] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/17/2006] [Accepted: 10/17/2006] [Indexed: 01/18/2023] Open
Abstract
Transcriptional cofactors are integral to the proper function and regulation of nuclear receptors. Members of the peroxisome proliferator-activated receptor (PPAR) family of nuclear receptors are involved in the regulation of lipid and carbohydrate metabolism. They modulate gene transcription in response to a wide variety of ligands, a process that is mediated by transcriptional coactivators and corepressors. The mechanisms by which these cofactors mediate transcriptional regulation of nuclear receptor function are still being elucidated. The rapidly increasing array of cofactors has brought into focus the need for a clear understanding of how these cofactors interact in ligand- and cell-specific manners. This review highlights the differential effects of the assorted cofactors regulating the transcriptional action of PPARγ and summarizes the recent advances in understanding the physiological functions of corepressors and coactivators.
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Affiliation(s)
- Emily Powell
- McArdle Laboratory for Cancer Research, University of Wisconsin, 1400 University Avenue, Madison, WI 53706, USA
| | - Peter Kuhn
- McArdle Laboratory for Cancer Research, University of Wisconsin, 1400 University Avenue, Madison, WI 53706, USA
| | - Wei Xu
- McArdle Laboratory for Cancer Research, University of Wisconsin, 1400 University Avenue, Madison, WI 53706, USA
- *Wei Xu:
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161
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Symonds ME, Budge H, Perkins AC, Lomax MA. Adipose tissue development – Impact of the early life environment. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 106:300-6. [DOI: 10.1016/j.pbiomolbio.2010.11.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 11/18/2010] [Accepted: 11/26/2010] [Indexed: 12/21/2022]
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162
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Vila-Bedmar R, Fernández-Veledo S. A new era for brown adipose tissue: New insights into brown adipocyte function and differentiation. Arch Physiol Biochem 2011; 117:195-208. [PMID: 21428723 DOI: 10.3109/13813455.2011.560951] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Until quite recently, brown adipose tissue was considered of metabolic significance only in small mammals and human newborns, since it was thought to disappear rapidly after birth in humans. However, nowadays this tissue is known to play a role in the regulation of energy balance not only in rodents, but also in humans. In this review we highlight new features regarding brown adipose tissue origin and function and revise old paradigms about brown adipocyte differentiation.
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Affiliation(s)
- Rocio Vila-Bedmar
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, Complutense University, 28040 Madrid, Spain
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163
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Watanabe M, Horai Y, Houten SM, Morimoto K, Sugizaki T, Arita E, Mataki C, Sato H, Tanigawara Y, Schoonjans K, Itoh H, Auwerx J. Lowering bile acid pool size with a synthetic farnesoid X receptor (FXR) agonist induces obesity and diabetes through reduced energy expenditure. J Biol Chem 2011; 286:26913-20. [PMID: 21632533 DOI: 10.1074/jbc.m111.248203] [Citation(s) in RCA: 206] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
We evaluated the metabolic impact of farnesoid X receptor (FXR) activation by administering a synthetic FXR agonist (GW4064) to mice in which obesity was induced by a high fat diet. Administration of GW4064 accentuated body weight gain and glucose intolerance induced by the high fat diet and led to a pronounced worsening of the changes in liver and adipose tissue. Mechanistically, treatment with GW4064 decreased bile acid (BA) biosynthesis, BA pool size, and energy expenditure, whereas reconstitution of the BA pool in these GW4064-treated animals by BA administration dose-dependently reverted the metabolic abnormalities. Our data therefore suggest that activation of FXR with synthetic agonists is not useful for long term management of the metabolic syndrome, as it reduces the BA pool size and subsequently decreases energy expenditure, translating as weight gain and insulin resistance. In contrast, expansion of the BA pool size, which can be achieved by BA administration, could be an interesting strategy to manage the metabolic syndrome.
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Affiliation(s)
- Mitsuhiro Watanabe
- Department of Internal Medicine, School of Medicine, Keio University, Tokyo 160-8582, Japan.
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164
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Sugii S, Evans RM. Epigenetic codes of PPARγ in metabolic disease. FEBS Lett 2011; 585:2121-8. [PMID: 21605560 PMCID: PMC3129683 DOI: 10.1016/j.febslet.2011.05.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 04/29/2011] [Accepted: 05/02/2011] [Indexed: 01/03/2023]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARγ), a ligand-regulated nuclear hormone receptor, plays critical roles in metabolism and adipogenesis. PPARγ ligands such as thiazolidinediones (TZDs) exert insulin sensitizing and anti-inflammatory effects primarily through action on adipocytes, and are thus widely used to treat metabolic syndrome, especially type II diabetes. A number of PPARγ interacting partners have been identified, many of which are known epigenetic regulators, including enzymes for histone acetylation/deacetylation and histone methylation/demethylation. However, their functional roles in the PPARγ transcriptional pathway are not well defined. Recent advances in ChIP-based and deep sequencing technology are revealing previously underappreciated epigenomic mechanisms and therapeutic potentials of this nuclear receptor pathway.
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Affiliation(s)
- Shigeki Sugii
- Howard Hughes Medical Institute and Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd, La Jolla, CA 92037, USA
- Singapore Bioimaging Consortium and Duke-NUS Graduate Medical School, 11 Biopolis Way #02-02, Singapore 138667
| | - Ronald M. Evans
- Howard Hughes Medical Institute and Gene Expression Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd, La Jolla, CA 92037, USA
- Corresponding author. Fax #: +1-858-455-1349.
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165
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Fujisaka S, Usui I, Kanatani Y, Ikutani M, Takasaki I, Tsuneyama K, Tabuchi Y, Bukhari A, Yamazaki Y, Suzuki H, Senda S, Aminuddin A, Nagai Y, Takatsu K, Kobayashi M, Tobe K. Telmisartan improves insulin resistance and modulates adipose tissue macrophage polarization in high-fat-fed mice. Endocrinology 2011; 152:1789-99. [PMID: 21427223 DOI: 10.1210/en.2010-1312] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Diet-induced obesity is reported to induce a phenotypic switch in adipose tissue macrophages from an antiinflammatory M2 state to a proinflammatory M1 state. Telmisartan, an angiotensin II type 1 receptor blocker and a peroxisome proliferator-activated receptor-γ agonist, reportedly has more beneficial effects on insulin sensitivity than other angiotensin II type 1 receptor blockers. In this study, we studied the effects of telmisartan on the adipose tissue macrophage phenotype in high-fat-fed mice. Telmisartan was administered for 5 wk to high-fat-fed C57BL/6 mice. Insulin sensitivity, macrophage infiltration, and the gene expressions of M1 and M2 markers in visceral adipose tissues were then examined. An insulin- or a glucose-tolerance test showed that telmisartan treatment improved insulin resistance, decreasing the body weight gain, visceral fat weight, and adipocyte size without affecting the amount of energy intake. Telmisartan reduced the mRNA expression of CD11c and TNF-α, M1 macrophage markers, and significantly increased the expressions of M2 markers, such as CD163, CD209, and macrophage galactose N-acetyl-galactosamine specific lectin (Mgl2), in a quantitative RT-PCR analysis. A flow cytometry analysis showed that telmisartan decreased the number of M1 macrophages in visceral adipose tissues. In conclusion, telmisartan improves insulin sensitivity and modulates adipose tissue macrophage polarization to an antiinflammatory M2 state in high-fat-fed mice.
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MESH Headings
- Adipocytes/drug effects
- Adipocytes/metabolism
- Adipose Tissue/drug effects
- Adipose Tissue/metabolism
- Adipose Tissue/pathology
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Antigens, Differentiation, Myelomonocytic/genetics
- Antigens, Differentiation, Myelomonocytic/metabolism
- Benzimidazoles/pharmacology
- Benzoates/pharmacology
- Body Weight/drug effects
- CD11c Antigen/genetics
- CD11c Antigen/metabolism
- Cell Adhesion Molecules/genetics
- Cell Adhesion Molecules/metabolism
- Cell Size/drug effects
- Dietary Fats/administration & dosage
- Dietary Fats/adverse effects
- Epididymis/drug effects
- Epididymis/metabolism
- Flow Cytometry
- Gene Expression Profiling
- Gene Expression Regulation/drug effects
- Glucose/metabolism
- Insulin Resistance
- Lectins, C-Type/genetics
- Lectins, C-Type/metabolism
- Macrophages/drug effects
- Macrophages/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Obesity/etiology
- Obesity/pathology
- Obesity/physiopathology
- Oligonucleotide Array Sequence Analysis
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Telmisartan
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/metabolism
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Affiliation(s)
- Shiho Fujisaka
- The First Department of Internal Medicine, University of Toyama, Toyama, Japan
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166
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Flammer JR, Rogatsky I. Minireview: Glucocorticoids in autoimmunity: unexpected targets and mechanisms. Mol Endocrinol 2011; 25:1075-86. [PMID: 21511881 DOI: 10.1210/me.2011-0068] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
For decades, natural and synthetic glucocorticoids (GC) have been among the most commonly prescribed classes of immunomodulatory drugs. Their unsurpassed immunosuppressive and antiinflammatory activity along with cost-effectiveness makes these compounds a treatment of choice for the majority of autoimmune and inflammatory diseases, despite serious side effects that frequently accompany GC therapy. The activated GC receptor (GR) that conveys the signaling information of these steroid ligands to the transcriptional machinery engages a number of pathways to ultimately suppress autoimmune responses. Of those, GR-mediated apoptosis of numerous cell types of hematopoietic origin and suppression of proinflammatory cytokine gene expression have been described as the primary mechanisms responsible for the antiinflammatory actions of GC. However, along with the ever-increasing appreciation of the complex functions of the immune system in health and disease, we are beginning to recognize new facets of GR actions in immune cells. Here, we give a brief overview of the extensive literature on the antiinflammatory activities of GC and discuss in greater detail the unexpected pathways, factors, and mechanisms that have recently begun to emerge as novel targets for GC-mediated immunosuppression.
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Affiliation(s)
- Jamie R Flammer
- Hospital for Special Surgery Research Division, Weill Cornell Graduate School of Medical Sciences, New York, New York 10021, USA
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167
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Eichner LJ, Giguère V. Estrogen related receptors (ERRs): a new dawn in transcriptional control of mitochondrial gene networks. Mitochondrion 2011; 11:544-52. [PMID: 21497207 DOI: 10.1016/j.mito.2011.03.121] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 02/07/2011] [Accepted: 03/23/2011] [Indexed: 01/12/2023]
Abstract
Mitochondrial dysfunction contributes to the etiology of numerous diseases. Consequently, improving our knowledge of how to modulate mitochondrial activity is of considerable interest. One means to achieve this goal would be to control in a global and comprehensive manner the expression of most if not all nuclear encoded mitochondrial genes. The advent of genome-wide location analysis of transcription factor occupancy coupled with functional studies in cell and animal models has recently shown that three transcription factors possess this unique attribute. Unexpectedly, these factors are orphan members of the superfamily of nuclear receptors known as estrogen-related receptors (ERRs) α, β and γ. In this review, we will integrate current knowledge gathered through several functional and physiological genomic studies to provide persuasive evidence that the ERRs are indeed master regulators of mitochondrial biogenesis and function.
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Affiliation(s)
- Lillian J Eichner
- Goodman Cancer Research Centre, McGill University, Montréal, QC, Canada H3A 1A3
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168
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Bai P, Canto C, Brunyánszki A, Huber A, Szántó M, Cen Y, Yamamoto H, Houten SM, Kiss B, Oudart H, Gergely P, Menissier-de Murcia J, Schreiber V, Sauve AA, Auwerx J. PARP-2 regulates SIRT1 expression and whole-body energy expenditure. Cell Metab 2011; 13:450-460. [PMID: 21459329 PMCID: PMC3108571 DOI: 10.1016/j.cmet.2011.03.013] [Citation(s) in RCA: 208] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 12/03/2010] [Accepted: 03/21/2011] [Indexed: 01/23/2023]
Abstract
SIRT1 is a NAD(+)-dependent enzyme that affects metabolism by deacetylating key transcriptional regulators of energy expenditure. Here, we tested whether deletion of PARP-2, an alternative NAD(+)-consuming enzyme, impacts on NAD(+) bioavailability and SIRT1 activity. Our results indicate that PARP-2 deficiency increases SIRT1 activity in cultured myotubes. However, this increase was not due to changes in NAD(+) levels, but to an increase in SIRT1 expression, as PARP-2 acts as a direct negative regulator of the SIRT1 promoter. PARP-2 deletion in mice increases SIRT1 levels, promotes energy expenditure, and increases mitochondrial content. Furthermore, PARP-2(-/-) mice were protected against diet-induced obesity. Despite being insulin sensitized, PARP-2(-/-) mice were glucose intolerant due to a defective pancreatic function. Hence, while inhibition of PARP activity promotes oxidative metabolism through SIRT1 activation, the use of PARP inhibitors for metabolic purposes will require further understanding of the specific functions of different PARP family members.
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Affiliation(s)
- Péter Bai
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, ESBS, 67412 Illkirch, France; Department of Medical Chemistry, MHSC, University of Debrecen, 4032 Debrecen, Hungary
| | - Carles Canto
- Laboratory of Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Attila Brunyánszki
- Department of Medical Chemistry, MHSC, University of Debrecen, 4032 Debrecen, Hungary
| | - Aline Huber
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, ESBS, 67412 Illkirch, France
| | - Magdolna Szántó
- Department of Medical Chemistry, MHSC, University of Debrecen, 4032 Debrecen, Hungary
| | - Yana Cen
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Hiroyasu Yamamoto
- Laboratory of Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Sander M Houten
- Laboratory Genetic Metabolic Diseases, AMC, 1115 AZ, Amsterdam, The Netherlands
| | - Borbala Kiss
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, ESBS, 67412 Illkirch, France; Department of Dermatology, University of Debrecen, 4032 Debrecen, Hungary
| | - Hugues Oudart
- Centre d'Ecologie et Physiologie Energétiques CNRS UPR9010, 67087 Strasbourg, France
| | - Pál Gergely
- Department of Medical Chemistry, MHSC, University of Debrecen, 4032 Debrecen, Hungary
| | - Josiane Menissier-de Murcia
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, ESBS, 67412 Illkirch, France
| | - Valérie Schreiber
- Biotechnologie et Signalisation Cellulaire, UMR7242 CNRS, Université de Strasbourg, ESBS, 67412 Illkirch, France
| | - Anthony A Sauve
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Johan Auwerx
- Laboratory of Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
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169
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Hartig SM, He B, Long W, Buehrer BM, Mancini MA. Homeostatic levels of SRC-2 and SRC-3 promote early human adipogenesis. ACTA ACUST UNITED AC 2011; 192:55-67. [PMID: 21220509 PMCID: PMC3019557 DOI: 10.1083/jcb.201004026] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The related coactivators SRC-2 and SRC-3 interact with peroxisome proliferator activated receptor γ (PPARγ) to coordinate transcriptional circuits to promote adipogenesis. To identify potential coactivator redundancy during human adipogenesis at single cell resolution, we used high content analysis to quantify links between PPARγ, SRC-2, SRC-3, and lipogenesis. Because we detected robust increases and significant cell-cell heterogeneity in PPARγ and lipogenesis, without changes in SRC-2 or SRC-3, we hypothesized that permissive coregulator levels comprise a necessary adipogenic equilibrium. We probed this equilibrium by down-regulating SRC-2 and SRC-3 while simultaneously quantifying PPARγ. Individual or joint knockdown equally inhibits lipid accumulation by preventing lipogenic gene engagement, without affecting PPARγ protein levels. Supporting dominant, pro-adipogenic roles for SRC-2 and SRC-3, SRC-1 knockdown does not affect adipogenesis. SRC-2 and SRC-3 knockdown increases the proportion of cells in a PPARγ(hi)/lipid(lo) state while increasing phospho-PPARγ-S114, an inhibitor of PPARγ transcriptional activity and adipogenesis. Together, we demonstrate that SRC-2 and SRC-3 concomitantly promote human adipocyte differentiation by attenuating phospho-PPARγ-S114 and modulating PPARγ cellular heterogeneity.
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Affiliation(s)
- Sean M Hartig
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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170
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Abstract
Nuclear receptors (NRs) represent a vital class of ligand-activated transcription factors responsible for coordinately regulating the expression of genes involved in numerous biological processes. Transcriptional regulation by NRs is conducted through interactions with multiple coactivator or corepressor complexes that modify the chromatin environment to facilitate or inhibit RNA polymerase II binding and transcription initiation. In recent years, studies have identified specific biological roles for cofactors mediating NR signaling through epigenetic modifications such as acetylation and methylation of histones. Intriguingly, genome-wide analysis of NR and cofactor localization has both confirmed findings from single-gene studies and revealed new insights into the relationships between NRs, cofactors and target genes in determining gene expression. Here, we review recent developments in the understanding of epigenetic regulation by NRs across the genome within the context of the well-established background of cofactor complexes and their roles in histone modification.
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Affiliation(s)
- Christopher D Green
- Chinese Academy of Sciences Key Laboratory of Molecular Developmental Biology, Center for Molecular Systems Biology, Institute of Genetics & Developmental Biology, Chinese Academy of Sciences, Datun Road, Beijing, 100101, China
- Chinese Academy of Sciences Key Laboratory of Computational Biology, Chinese Academy of Sciences–MaxPlanck Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai, 200031, China
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171
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Sommerfeld A, Krones-Herzig A, Herzig S. Transcriptional co-factors and hepatic energy metabolism. Mol Cell Endocrinol 2011; 332:21-31. [PMID: 21112373 DOI: 10.1016/j.mce.2010.11.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 11/17/2010] [Accepted: 11/18/2010] [Indexed: 01/24/2023]
Abstract
After binding to their cognate DNA-binding partner, transcriptional co-factors exert their function through the recruitment of enzymatic, chromatin-modifying activities. In turn, the assembly of co-factor-associated multi-protein complexes efficiently impacts target gene expression. Recent advances have established transcriptional co-factor complexes as a critical regulatory level in energy homeostasis and aberrant co-factor activity has been linked to the pathogenesis of severe metabolic disorders including obesity, type 2 diabetes and other components of the Metabolic Syndrome. The liver represents the key peripheral organ for the maintenance of systemic energy homeostasis, and aberrations in hepatic glucose and lipid metabolism have been causally linked to the manifestation of disorders associated with the Metabolic Syndrome. Therefore, this review focuses on the role of distinct classes of transcriptional co-factors in hepatic glucose and lipid homeostasis, emphasizing pathway-specific functions of these co-factors under physiological and pathophysiological conditions.
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Affiliation(s)
- Anke Sommerfeld
- Department Molecular Metabolic Control, DKFZ-ZMBH Alliance, German Cancer Research Center Heidelberg, Germany
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172
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Cellular energy depletion resets whole-body energy by promoting coactivator-mediated dietary fuel absorption. Cell Metab 2011; 13:35-43. [PMID: 21195347 PMCID: PMC3072049 DOI: 10.1016/j.cmet.2010.12.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2010] [Revised: 09/08/2010] [Accepted: 11/30/2010] [Indexed: 01/08/2023]
Abstract
All organisms have devised strategies to counteract energy depletion and promote fitness for survival. We show here that cellular energy depletion puts into play a surprising strategy that leads to absorption of exogenous fuel for energy repletion. The energy-depletion-sensing kinase AMPK binds, phosphorylates, and activates the transcriptional coactivator SRC-2, which in a liver-specific manner promotes absorption of dietary fat from the gut. Hepatocyte-specific deletion of SRC-2 results in intestinal fat malabsorption and attenuated entry of fat into the blood stream. This defect can be attributed to AMPK- and SRC-2-mediated transcriptional regulation of hepatic bile acid (BA) secretion into the gut, as it can be completely rescued by replenishing intestinal BA or by genetically restoring the levels of hepatic bile salt export pump (BSEP). Our results position the hepatic AMPK-SRC-2 axis as an energy rheostat, which upon cellular energy depletion resets whole-body energy by promoting absorption of dietary fuel.
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173
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Abstract
The three members of the p160 family of steroid receptor coactivators (SRC-1, SRC-2, and SRC-3) steer the functional output of numerous genetic programs and serve as pleiotropic rheostats for diverse physiological processes. Since their discovery ∼15 years ago, the extraordinary sum of examination of SRC function has shaped the foundation of our knowledge for the now 350+ coregulators that have been identified to date. In this perspective, we retrace our steps into the field of coregulators and provide a summary of selected seminal work that helped define the SRCs as masters of systems biology.
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Affiliation(s)
- Brian York
- From the Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Bert W. O'Malley
- From the Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
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174
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Xu B, Gerin I, Miao H, Vu-Phan D, Johnson CN, Xu R, Chen XW, Cawthorn WP, MacDougald OA, Koenig RJ. Multiple roles for the non-coding RNA SRA in regulation of adipogenesis and insulin sensitivity. PLoS One 2010; 5:e14199. [PMID: 21152033 PMCID: PMC2996286 DOI: 10.1371/journal.pone.0014199] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 11/05/2010] [Indexed: 01/22/2023] Open
Abstract
Peroxisome proliferator-activated receptor-γ (PPARγ) is a master transcriptional regulator of adipogenesis. Hence, the identification of PPARγ coactivators should help reveal mechanisms controlling gene expression in adipose tissue development and physiology. We show that the non-coding RNA, Steroid receptor RNA Activator (SRA), associates with PPARγ and coactivates PPARγ-dependent reporter gene expression. Overexpression of SRA in ST2 mesenchymal precursor cells promotes their differentiation into adipocytes. Conversely, knockdown of endogenous SRA inhibits 3T3-L1 preadipocyte differentiation. Microarray analysis reveals hundreds of SRA-responsive genes in adipocytes, including genes involved in the cell cycle, and insulin and TNFα signaling pathways. Some functions of SRA may involve mechanisms other than coactivation of PPARγ. SRA in adipocytes increases both glucose uptake and phosphorylation of Akt and FOXO1 in response to insulin. SRA promotes S-phase entry during mitotic clonal expansion, decreases expression of the cyclin-dependent kinase inhibitors p21Cip1 and p27Kip1, and increases phosphorylation of Cdk1/Cdc2. SRA also inhibits the expression of adipocyte-related inflammatory genes and TNFα-induced phosphorylation of c-Jun NH2-terminal kinase. In conclusion, SRA enhances adipogenesis and adipocyte function through multiple pathways.
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Affiliation(s)
- Bin Xu
- Division of Metabolism, Endocrinology and Diabetes, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan, United States of America.
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175
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The coactivator SRC-1 is an essential coordinator of hepatic glucose production. Cell Metab 2010; 12:606-18. [PMID: 21109193 PMCID: PMC3024581 DOI: 10.1016/j.cmet.2010.11.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 06/17/2010] [Accepted: 09/23/2010] [Indexed: 01/26/2023]
Abstract
Gluconeogenesis makes a major contribution to hepatic glucose production, a process critical for survival in mammals. In this study, we identify the p160 family member, SRC-1, as a key coordinator of the hepatic gluconeogenic program in vivo. SRC-1-null mice displayed hypoglycemia secondary to a deficit in hepatic glucose production. Selective re-expression of SRC-1 in the liver restored blood glucose levels to a normal range. SRC-1 was found induced upon fasting to coordinate in a cell-autonomous manner, the gene expression of rate-limiting enzymes of the gluconeogenic pathway. At the molecular level, the main role of SRC-1 was to modulate the expression and the activity of C/EBPα through a feed-forward loop in which SRC-1 used C/EBPα to transactivate pyruvate carboxylase, a crucial gene for initiation of the gluconeogenic program. We propose that SRC-1 acts as a critical mediator of glucose homeostasis in the liver by adjusting the transcriptional activity of key genes involved in the hepatic glucose production machinery.
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176
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Duteil D, Chambon C, Ali F, Malivindi R, Zoll J, Kato S, Geny B, Chambon P, Metzger D. The transcriptional coregulators TIF2 and SRC-1 regulate energy homeostasis by modulating mitochondrial respiration in skeletal muscles. Cell Metab 2010; 12:496-508. [PMID: 21035760 PMCID: PMC3032428 DOI: 10.1016/j.cmet.2010.09.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2009] [Revised: 06/17/2010] [Accepted: 08/23/2010] [Indexed: 01/21/2023]
Abstract
The two p160 transcriptional coregulator family members SRC-1 and TIF2 have important metabolic functions in white and brown adipose tissues as well as in the liver. To analyze TIF2 cell-autonomous functions in skeletal muscles, we generated TIF2((i)skm)⁻(/)⁻ mice in which TIF2 was selectively ablated in skeletal muscle myofibers at adulthood. We found that increased mitochondrial uncoupling in skeletal muscle myocytes protected these mice from decreased muscle oxidative capacities induced by sedentariness, delayed the development of type 2 diabetes, and attenuated high-caloric-diet-induced obesity. Moreover, our results demonstrate that SRC-1 and TIF2 can modulate the expression of the uncoupling protein 3 (UCP3) in an antagonistic manner and that enhanced SRC-1 levels in TIF2-deficient myofibers are critically involved in the metabolic changes of TIF2((i)skm)⁻(/)⁻ mice. Thus, modulation of the expression and/or activity of these coregulators represents an attractive way to prevent or treat metabolic disorders.
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Affiliation(s)
- Delphine Duteil
- Department of Physiological Genetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France
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177
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Doshi LS, Brahma MK, Bahirat UA, Dixit AV, Nemmani KVS. Discovery and development of selective PPAR gamma modulators as safe and effective antidiabetic agents. Expert Opin Investig Drugs 2010; 19:489-512. [PMID: 20367191 DOI: 10.1517/13543781003640169] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
IMPORTANCE OF THE FIELD PPARgamma full agonists (pioglitazone and rosiglitazone) are the mainstay drugs for the treatment of type 2 diabetes; however, mechanism-based side effects have limited their full therapeutic potential. In recent years, much progress has been achieved in the discovery and development of selective PPARgamma modulators (SPPARgammaMs) as safer alternatives to PPARgamma full agonists. AREAS COVERED IN THIS REVIEW This review focuses on the preclinical and clinical data of all the SPPARgammaMs discovered so far, retrieved by searching PubMed, Prous Integrity database and company news updates from 1999 to date. WHAT THE READER WILL GAIN Here we thoroughly discuss SPPARgammaMs' mode of action, briefly examine new ways to identify superior SPPARgammaMs, and finally, compare and contrast the pharmacological and safety profile of various agents. TAKE HOME MESSAGE The preclinical and clinical findings clearly suggest that selective PPARgamma modulators have the potential to become the next generation of PPARgamma agonists: effective insulin sensitizers with a superior safety profile to that of PPARgamma full agonists.
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Affiliation(s)
- Lalit S Doshi
- Department of Pharmacology, Piramal Life Sciences Limited, 1 Nirlon Complex, Goregaon (E), Mumbai - 400 063, India
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178
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Genet C, Schmidt C, Strehle A, Schoonjans K, Auwerx J, Saladin R, Wagner A. Redefining the TGR5 Triterpenoid Binding Pocket at the C-3 Position. ChemMedChem 2010; 5:1983-8. [DOI: 10.1002/cmdc.201000329] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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179
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180
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Abstract
Peroxisome proliferator-activated receptor (PPAR)alpha, beta (also known as delta), and gamma function as sensors for fatty acids and fatty acid derivatives and control important metabolic pathways involved in the maintenance of energy balance. PPARs also regulate other diverse biological processes such as development, differentiation, inflammation, and neoplasia. In the nucleus, PPARs exist as heterodimers with retinoid X receptor-alpha bound to DNA with corepressor molecules. Upon ligand activation, PPARs undergo conformational changes that facilitate the dissociation of corepressor molecules and invoke a spatiotemporally orchestrated recruitment of transcription cofactors including coactivators and coactivator-associated proteins. While a given nuclear receptor regulates the expression of a prescribed set of target genes, coactivators are likely to influence the functioning of many regulators and thus affect the transcription of many genes. Evidence suggests that some of the coactivators such as PPAR-binding protein (PBP/PPARBP), thyroid hormone receptor-associated protein 220 (TRAP220), and mediator complex subunit 1 (MED1) may exert a broader influence on the functions of several nuclear receptors and their target genes. Investigations into the role of coactivators in the function of PPARs should strengthen our understanding of the complexities of metabolic diseases associated with energy metabolism.
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181
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Chen X, Liu Z, Xu J. The cooperative function of nuclear receptor coactivator 1 (NCOA1) and NCOA3 in placental development and embryo survival. Mol Endocrinol 2010; 24:1917-34. [PMID: 20685850 DOI: 10.1210/me.2010-0201] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nuclear receptor coactivator 1 [NCOA1/steroid receptor coactivator (SRC)-1] and NCOA3 (SRC-3/AIB1/ACTR) constitute two thirds of the SRC (steroid receptor coactivator) family. Although in vitro experiments have suggested overlapping functions between NCOA1 and NCOA3, their in vivo functional relationship is poorly understood. In this study, NCOA1 and NCOA3 double knockout mice were generated to determine the compensatory roles of NCOA1 and NCOA3 in development. NCOA1(-/-) mice survived normally, whereas most NCOA3(-/-) embryos were viable at embryonic d 13.5 (E13.5). In contrast, the majority of double-knockout (DKO) embryos died by E13.5. NCOA1 and NCOA3 are expressed in the labyrinth, and labyrinths of NCOA1(+/-);NCOA3(-/-) and DKO placentas were small compared with wild-type and single-knockout labyrinths. DKO labyrinths exhibited low densities of maternal blood sinuses and fetal capillaries and displayed fetomaternal blood transfusion. At the interface between maternal and fetal circulations, layer I sinusoidal trophoblast giant cells showed a reduced density of microvilli. Layer III syncytiotrophoblasts appeared to accumulate large lipid droplets and have reduced density and deepened invaginations of the intrasyncytial bays. The endothelial layer in DKO labyrinth showed abnormal morphologies and had large lipid droplets. Furthermore, disruption of NCOA1 and NCOA3 increased labyrinth trophoblast proliferation and their progenitor gene expression but decreased their differentiation gene expression. NCOA1 and NCOA3 deficiencies also affected the expression of several genes for placental morphogenesis including TGFβ-, peroxisome proliferator-activated receptor-β-, and peroxisome proliferator-activated receptor-γ-regulated genes and for glucose transportation including GLUT1 and Cx26. These findings demonstrate that NCOA1 and NCOA3 cooperatively regulate placental morphogenesis and embryo survival.
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Affiliation(s)
- Xian Chen
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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182
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Carnevalli LS, Masuda K, Frigerio F, Le Bacquer O, Um SH, Gandin V, Topisirovic I, Sonenberg N, Thomas G, Kozma SC. S6K1 plays a critical role in early adipocyte differentiation. Dev Cell 2010; 18:763-74. [PMID: 20493810 DOI: 10.1016/j.devcel.2010.02.018] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/04/2010] [Accepted: 02/26/2010] [Indexed: 01/08/2023]
Abstract
Earlier, we reported that S6K1(-/-) mice have reduced body fat mass, have elevated rates of lipolysis, have severely decreased adipocyte size, and are resistant to high fat diet (HFD)-induced obesity. Here we report that adipocytes of S6K1(-/-) mice on a HFD have the capacity to increase in size to a degree comparable to that of wild-type (WT) mice, but not in number, indicating an unexpected lesion in adipogenesis. Tracing this lesion revealed that S6K1 is dispensable for terminal adipocyte differentiation, but is involved in the commitment of embryonic stem cells to early adipocyte progenitors. We further show that absence of S6K1 attenuates the upregulation of transcription factors critical for commitment to adipogenesis. These results led to the conclusion that a lack of S6K1 impairs the generation of de novo adipocytes when mice are challenged with a HFD, consistent with a reduction in early adipocyte progenitors.
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Affiliation(s)
- Larissa S Carnevalli
- Department of Cancer and Cell Biology, Metabolic Diseases Institute, College of Medicine, University of Cincinnati, Cincinnati, OH 45237, USA
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183
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Koppen A, Kalkhoven E. Brown vs white adipocytes: The PPARγ coregulator story. FEBS Lett 2010; 584:3250-9. [DOI: 10.1016/j.febslet.2010.06.035] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/30/2022]
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184
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Madsen L, Pedersen LM, Lillefosse HH, Fjære E, Bronstad I, Hao Q, Petersen RK, Hallenborg P, Ma T, De Matteis R, Araujo P, Mercader J, Bonet ML, Hansen JB, Cannon B, Nedergaard J, Wang J, Cinti S, Voshol P, Døskeland SO, Kristiansen K. UCP1 induction during recruitment of brown adipocytes in white adipose tissue is dependent on cyclooxygenase activity. PLoS One 2010; 5:e11391. [PMID: 20613988 PMCID: PMC2894971 DOI: 10.1371/journal.pone.0011391] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/30/2010] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The uncoupling protein 1 (UCP1) is a hallmark of brown adipocytes and pivotal for cold- and diet-induced thermogenesis. METHODOLOGY/PRINCIPAL FINDINGS Here we report that cyclooxygenase (COX) activity and prostaglandin E(2) (PGE(2)) are crucially involved in induction of UCP1 expression in inguinal white adipocytes, but not in classic interscapular brown adipocytes. Cold-induced expression of UCP1 in inguinal white adipocytes was repressed in COX2 knockout (KO) mice and by administration of the COX inhibitor indomethacin in wild-type mice. Indomethacin repressed beta-adrenergic induction of UCP1 expression in primary inguinal adipocytes. The use of PGE(2) receptor antagonists implicated EP(4) as a main PGE(2) receptor, and injection of the stable PGE(2) analog (EP(3/4) agonist) 16,16 dm PGE(2) induced UCP1 expression in inguinal white adipose tissue. Inhibition of COX activity attenuated diet-induced UCP1 expression and increased energy efficiency and adipose tissue mass in obesity-resistant mice kept at thermoneutrality. CONCLUSIONS/SIGNIFICANCE Our findings provide evidence that induction of UCP1 expression in white adipose tissue, but not in classic interscapular brown adipose tissue is dependent on cyclooxygenase activity. Our results indicate that cyclooxygenase-dependent induction of UCP1 expression in white adipose tissues is important for diet-induced thermogenesis providing support for a surprising role of COX activity in the control of energy balance and obesity development.
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Affiliation(s)
- Lise Madsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Lone M. Pedersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Haldis Haukaas Lillefosse
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Even Fjære
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | | | - Qin Hao
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Philip Hallenborg
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Tao Ma
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rita De Matteis
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Pedro Araujo
- National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - Josep Mercader
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, and CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
| | - M. Luisa Bonet
- Laboratory of Molecular Biology, Nutrition and Biotechnology, Universitat de les Illes Balears, and CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Palma de Mallorca, Spain
| | - Jacob B. Hansen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Barbara Cannon
- The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jan Nedergaard
- The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Jun Wang
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- BGI-Shenzhen, Shenzhen, China
| | - Saverio Cinti
- Department of Molecular Pathology and Innovative Therapies, University of Ancona, Ancona, Italy
| | - Peter Voshol
- Metabolic Research Laboratories, University of Cambridge, Cambridge, United Kingdom
| | | | - Karsten Kristiansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- BGI-Shenzhen, Shenzhen, China
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185
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Siersbaek R, Nielsen R, Mandrup S. PPARgamma in adipocyte differentiation and metabolism--novel insights from genome-wide studies. FEBS Lett 2010; 584:3242-9. [PMID: 20542036 DOI: 10.1016/j.febslet.2010.06.010] [Citation(s) in RCA: 283] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 06/03/2010] [Accepted: 06/07/2010] [Indexed: 12/14/2022]
Abstract
Adipocyte differentiation is controlled by a tightly regulated transcriptional cascade in which PPARgamma and members of the C/EBP family are key players. Here we review the roles of PPARgamma and C/EBPs in adipocyte differentiation with emphasis on the recently published genome-wide binding profiles for PPARgamma and C/EBPalpha. Interestingly, these analyses show that PPARgamma and C/EBPalpha binding sites are associated with most genes that are induced during adipogenesis suggesting direct activation of many more adipocyte genes than previously anticipated. Furthermore, an extensive overlap between the C/EBPalpha and PPARgamma cistromes indicate a hitherto unrecognized direct crosstalk between these transcription factors. As more genome-wide data emerge in the future, this crosstalk will likely be found to include several other adipogenic transcription factors.
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Affiliation(s)
- Rasmus Siersbaek
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, 5230 Odense, Denmark
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186
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Jeninga EH, Schoonjans K, Auwerx J. Reversible acetylation of PGC-1: connecting energy sensors and effectors to guarantee metabolic flexibility. Oncogene 2010; 29:4617-24. [PMID: 20531298 DOI: 10.1038/onc.2010.206] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Organisms adapt their metabolism to meet ever changing environmental conditions. This metabolic adaptation involves at a cellular level the fine tuning of mitochondrial function, which is mainly under the control of the transcriptional co-activator proliferator-activated receptor gamma co-activator (PGC)-1alpha. Changes in PGC-1alpha activity coordinate a transcriptional response, which boosts mitochondrial activity in times of energy needs and attenuates it when energy demands are low. Reversible acetylation has emerged as a key way to alter PGC-1alpha activity. Although it is well established that PGC-1alpha is deacetylated and activated by Sirt1 and acetylated and inhibited by GCN5, less is known regarding how these enzymes themselves are regulated. Recently, it became clear that the energy sensor, AMP-activated kinase (AMPK) translates the effects of energy stress into altered Sirt1 activity by regulating the intracellular level of its co-substrate nicotinamide adenine dinucleotide (NAD)(+). Conversely, the enzyme ATP citrate lyase (ACL), relates energy balance to GCN5, through the control of the nuclear production of acetyl-CoA, the substrate for GCN5's acetyltransferase activity. We review here how these metabolic signaling pathways, affecting GCN5 and Sirt1 activity, allow the reversible acetylation-deacetylation of PGC-1alpha and the adaptation of mitochondrial energy homeostasis to energy levels.
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Affiliation(s)
- E H Jeninga
- Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Integrative and Systems Physiology, Lausanne, Switzerland
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187
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Reprogramming the posttranslational code of SRC-3 confers a switch in mammalian systems biology. Proc Natl Acad Sci U S A 2010; 107:11122-7. [PMID: 20534466 DOI: 10.1073/pnas.1005262107] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Here we demonstrate that reprogramming steroid receptor coactivator-3 (SRC-3) function by changing its posttranslational modification (PTM) code drastically influences systems biology. These findings support the physiological importance of PTMs in directing in vivo functions of a master coregulator. We previously reported that the transactivation potential of SRC-3 is controlled in part by PTMs, although this data emanated from in vitro studies. To test the physiological implications of PTMs on SRC-3, we developed a knock-in mouse model containing mutations at four conserved phosphorylation sites. These mice displayed a systems biology phenotype with increased body weight and adiposity, coupled with reduced peripheral insulin sensitivity. Collectively, these phenotypes result from increased IGF1 signaling, due to elevated IGFBP3 levels. We provide convincing evidence that these mutations in SRC-3 promoted enhanced transcription of the IGFBP3 gene and globally influenced growth and metabolism. Consequently, these mice displayed increased liver tumorigenesis, which likely results from elevated IGF1 signaling.
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188
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Kajimura S, Seale P, Spiegelman BM. Transcriptional control of brown fat development. Cell Metab 2010; 11:257-62. [PMID: 20374957 PMCID: PMC2857670 DOI: 10.1016/j.cmet.2010.03.005] [Citation(s) in RCA: 310] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 03/14/2010] [Accepted: 03/16/2010] [Indexed: 12/18/2022]
Abstract
Deconvoluting the natural pathway of BAT development has defined key molecular events, which enables researchers to manipulate the amount or activity of brown fat. We review recent advances on the transcriptional regulation of BAT development and discuss the emerging questions.
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Affiliation(s)
- Shingo Kajimura
- Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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189
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Genet C, Strehle A, Schmidt C, Boudjelal G, Lobstein A, Schoonjans K, Souchet M, Auwerx J, Saladin R, Wagner A. Structure-activity relationship study of betulinic acid, a novel and selective TGR5 agonist, and its synthetic derivatives: potential impact in diabetes. J Med Chem 2010; 53:178-90. [PMID: 19911773 DOI: 10.1021/jm900872z] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We describe here the biological screening of a collection of natural occurring triterpenoids against the G protein-coupled receptor TGR5, known to be activated by bile acids and which mediates some important cell functions. This work revealed that betulinic (1), oleanolic (2), and ursolic acid (3) exhibited TGR5 agonist activity in a selective manner compared to bile acids, which also activated FXR, the nuclear bile acid receptor. The most potent natural triterpenoid betulinic acid was chosen as a reference compound for an SAR study. Hemisyntheses were performed on the betulinic acid scaffold, and we focused on structural modifications of the C-3 alcohol, the C-17 carboxylic acid, and the C-20 alkene. In particular, structural variations around the C-3 position gave rise to major improvements of potency exemplified with derivatives 18 dia 2 (RG-239) and 19 dia 2. The best derivative was tested in vitro and in vivo, and its biological profile is discussed.
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Affiliation(s)
- Cédric Genet
- UMR/CNRS 7199, Faculte de pharmacie, Universite Louis Pasteur, 67404 Illkirch, France
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190
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Kozak LP, Koza RA. The genetics of brown adipose tissue. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 94:75-123. [PMID: 21036323 DOI: 10.1016/b978-0-12-375003-7.00004-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Brown adipose tissue is highly differentiated and has evolved as a mechanism for heat production based upon uncoupling of mitochondrial oxidative phosphorylation. Additionally, large amounts of lipid can be stored in the cells to provide fuel necessary for heat production upon adrenergic stimulation from the central nervous system, and a highly developed vascular system evolved to rapidly deliver heat to vital organs. For unknown reasons, the development of brown adipocytes has two independent pathways: one originates from muscle progenitor cells in the fetus and leads to a fully functional cell at birth (interscapular-type brown fat), while the other transiently emerges in traditional white fat depots at weaning, regresses, and then can be induced in adult mice upon adrenergic stimulation. No genetic variants have been found for interscapular fat, but naturally occurring alleles at eight genetic loci in mice lead to over 100-fold variation for brown adipocytes in white fat upon adrenergic stimulation. The ability to activate this potential for energy expenditure is of great interest in obesity research.
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Affiliation(s)
- Leslie P Kozak
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
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191
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Bitra K, Tan A, Dowling A, Palli SR. Functional characterization of PAS and HES family bHLH transcription factors during the metamorphosis of the red flour beetle, Tribolium castaneum. Gene 2009; 448:74-87. [PMID: 19683038 PMCID: PMC2760604 DOI: 10.1016/j.gene.2009.08.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2009] [Revised: 08/06/2009] [Accepted: 08/06/2009] [Indexed: 11/22/2022]
Abstract
The basic helix-loop-helix transcription factors are present in animals, plants and fungi and play important roles in the control of cellular proliferation, tissue differentiation, development and detoxification. Although insect genomes contain more than 50 helix-loop-helix transcription factors, the functions of only a few are known. RNAi has become a widely used tool to knock-down the expression to analyze the function of genes. As RNAi works well in Tribolium castaneum, we utilized this insect and RNAi to determine functions of 19 bHLH transcription factors belonging to PAS and HES families during the larval stages of the red flour beetle, T. castaneum. We searched the genome sequence of T. castaneum and identified 53 bHLH genes. Phylogenetic analyses classified these 53 genes into ten families; PAS, HES, Myc/USF, Hand, Mesp, Shout, p48, NeuroD/Neurogenin, Atonal and AS-C. In RNAi studies, knocking-down the expression of seven members of the PAS and HES families affected the growth and development of T. castaneum. An inability to grow to reach critical weight to undergo metamorphosis, failure to complete larval-pupal or pupal-adult ecdysis and abnormal wing development are among the most common phenotypes observed in RNAi insects. Among the bHLH transcription factors studied, the steroid receptor coactivator (SRC) showed the most severe phenotypes. Knock-down in the expression of the gene coding for SRC caused growth arrest by affecting the regulation of lipid metabolism. These studies demonstrate the power of RNAi for functional characterization of members of the multigene families in this model insect.
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Affiliation(s)
- Kavita Bitra
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, KY 40546
| | - Anjiang Tan
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, KY 40546
| | - Ashley Dowling
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, KY 40546
| | - Subba R. Palli
- Department of Entomology, College of Agriculture, University of Kentucky, Lexington, KY 40546
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192
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Schulz TJ, Tseng YH. Emerging role of bone morphogenetic proteins in adipogenesis and energy metabolism. Cytokine Growth Factor Rev 2009; 20:523-31. [PMID: 19896888 DOI: 10.1016/j.cytogfr.2009.10.019] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bone morphogenetic proteins (BMPs) regulate many processes in embryonic development as well as in the maintenance of normal tissue function later in adult life. However, the role of this family of proteins in formation of adipose tissue has been underappreciated in the field of developmental biology. With the growing epidemic of obesity, improved knowledge of adipocyte development and function is urgently needed. Recently, there have been significant advances in understanding the role of different members of the BMP superfamily in control of adipocyte differentiation and systemic energy homeostasis. This review summarizes recent progress in understanding how BMPs specify adipose cell fate in stem/progenitor cells and their potential role in energy metabolism. We propose that BMPs provide instructive signals for adipose cell fate determination and regulate adipocyte function. These findings have opened up exciting opportunities for developing new therapeutic approaches for the treatment of obesity and its many associated metabolic disorders.
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Affiliation(s)
- Tim J Schulz
- Joslin Diabetes Center, One Joslin Place, and Harvard Medical School, Boston, MA 02215, USA
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193
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Røst TH, Haugan Moi LL, Berge K, Staels B, Mellgren G, Berge RK. A pan-PPAR ligand induces hepatic fatty acid oxidation in PPARα−/− mice possibly through PGC-1 mediated PPARδ coactivation. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:1076-83. [DOI: 10.1016/j.bbalip.2009.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 06/19/2009] [Accepted: 06/23/2009] [Indexed: 10/20/2022]
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194
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Lonard DM, Kumar R, O'Malley BW. Minireview: the SRC family of coactivators: an entrée to understanding a subset of polygenic diseases? Mol Endocrinol 2009; 24:279-85. [PMID: 19846539 DOI: 10.1210/me.2009-0276] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In this perspective, we present the idea that SRC family coactivators are likely agents in human polygenic disease states based upon a number of interlocking aspects of their biology. We argue that their role as key integrators of environmental signals and their ability to regulate the expression of myriad downstream genes makes them likely candidates for strong positive evolutionary selection pressures. Based on the fact that they work as part of multiprotein coactivator complexes, we predict that individual coactivator alleles exist as weakly penetrant disease alleles, each contributing only a fraction of transcriptional activity to the whole coactivator complex. In this way, individual coactivator alleles are free to evolve in the absence of strong negative selection. Emerging genomic and proteomic approaches promise to advance the characterization of coactivator proteins and their physiological functions, allowing us to have a greater appreciation of their roles as master regulators at the nexus between genetics, reproduction, metabolism, cancer, other human diseases, and our environment.
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Affiliation(s)
- David M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030.
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195
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Festuccia WT, Deshaies Y. Depot specificities of PPARγ ligand actions on lipid and glucose metabolism and their implication in PPARγ-mediated body fat redistribution. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/clp.09.45] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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196
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Vernochet C, Peres SB, Farmer SR. Mechanisms of obesity and related pathologies: transcriptional control of adipose tissue development. FEBS J 2009; 276:5729-37. [PMID: 19754874 DOI: 10.1111/j.1742-4658.2009.07302.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Obesity and its associated disorders, including diabetes and cardiovascular disease, have now reached epidemic proportions in the Western world, resulting in dramatic increases in healthcare costs. Understanding the processes and metabolic perturbations that contribute to the expansion of adipose depots accompanying obesity is central to the development of appropriate therapeutic strategies. This minireview focuses on a discussion of the recent identification of molecular mechanisms controlling the development and function of adipose tissues, as well as how these mechanisms contribute to the regulation of energy balance in mammals.
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Affiliation(s)
- Cecile Vernochet
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118, USA
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197
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Vernochet C, Peres SB, Davis KE, McDonald ME, Qiang L, Wang H, Scherer PE, Farmer SR. C/EBPalpha and the corepressors CtBP1 and CtBP2 regulate repression of select visceral white adipose genes during induction of the brown phenotype in white adipocytes by peroxisome proliferator-activated receptor gamma agonists. Mol Cell Biol 2009; 29:4714-28. [PMID: 19564408 PMCID: PMC2725706 DOI: 10.1128/mcb.01899-08] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 02/23/2009] [Accepted: 06/18/2009] [Indexed: 01/02/2023] Open
Abstract
White adipose tissue (WAT) stores energy in the form of triglycerides, whereas brown tissue (BAT) expends energy, primarily by oxidizing lipids. WAT also secretes many cytokines and acute-phase proteins that contribute to insulin resistance in obese subjects. In this study, we have investigated the mechanisms by which activation of peroxisome proliferator-activated receptor gamma (PPARgamma) with synthetic agonists induces a brown phenotype in white adipocytes in vivo and in vitro. We demonstrate that this phenotypic conversion is characterized by repression of a set of white fat genes ("visceral white"), including the resistin, angiotensinogen, and chemerin genes, in addition to induction of brown-specific genes, such as Ucp-1. Importantly, the level of expression of the "visceral white" genes is high in mesenteric and gonadal WAT depots but low in the subcutaneous WAT depot and in BAT. Mutation of critical amino acids within helix 7 of the ligand-binding domain of PPARgamma prevents inhibition of visceral white gene expression by the synthetic agonists and therefore shows a direct role for PPARgamma in the repression process. Inhibition of the white adipocyte genes also depends on the expression of C/EBPalpha and the corepressors, carboxy-terminal binding proteins 1 and 2 (CtBP1/2). The data further show that repression of resistin and angiotensinogen expression involves recruitment of CtBP1/2, directed by C/EBPalpha, to the minimal promoter of the corresponding genes in response to the PPARgamma ligand. Developing strategies to enhance the brown phenotype in white adipocytes while reducing secretion of stress-related cytokines from visceral WAT is a means to combat obesity-associated disorders.
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Affiliation(s)
- Cecile Vernochet
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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198
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Xu J, Wu RC, O’Malley BW. Normal and cancer-related functions of the p160 steroid receptor co-activator (SRC) family. Nat Rev Cancer 2009; 9:615-30. [PMID: 19701241 PMCID: PMC2908510 DOI: 10.1038/nrc2695] [Citation(s) in RCA: 381] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The three homologous members of the p160 SRC family (SRC1, SRC2 and SRC3) mediate the transcriptional functions of nuclear receptors and other transcription factors, and are the most studied of all the transcriptional co-activators. Recent work has indicated that the SRCgenes are subject to amplification and overexpression in various human cancers. Some of the molecular mechanisms responsible for SRC overexpression, along with the mechanisms by which SRCs promote breast and prostate cancer cell proliferation and survival, have been identified, as have the specific contributions of individual SRC family members to spontaneous breast and prostate carcinogenesis in genetically manipulated mouse models. These studies have identified new challenges for cancer research and therapy.
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Affiliation(s)
- Jianming Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA
- Luzhou Medical College, Luzhou, Sichuan 646000, China
| | - Ray-Chang Wu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA
| | - Bert W. O’Malley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA
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199
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Miard S, Dombrowski L, Carter S, Boivin L, Picard F. Aging alters PPARgamma in rodent and human adipose tissue by modulating the balance in steroid receptor coactivator-1. Aging Cell 2009; 8:449-59. [PMID: 19485965 DOI: 10.1111/j.1474-9726.2009.00490.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Age is an important risk factor for the development of metabolic diseases (e.g. obesity, diabetes and atherosclerosis). Yet, little is known about the molecular mechanisms occurring upon aging that affect energy metabolism. Although visceral white adipose tissue (vWAT) is known for its key impact on metabolism, recent studies have indicated it could also be a key regulator of lifespan, suggesting that it can serve as a node for age-associated fat accretion. Here we show that aging triggers changes in the transcriptional milieu of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma) in vWAT, which leads to a modified potential for transactivation of target genes upon ligand treatment. We found that in vWAT of mice, rats and men, aging induced a specific decrease in the expression of steroid receptor coactivator-1 (SRC-1), whose recruitment to PPARgamma is associated with improved insulin sensitivity and low adipogenic activity. In contrast, aging and oxidative stress did not impact on PPARgamma expression and PPARgamma ligand production. Age-induced loss of PPARgamma/SRC-1 interactions increased the binding of PPARgamma to the promoter of the adipogenic gene aP2. These findings suggest that strategies aimed at increasing SRC-1 expression and recruitment to PPARgamma upon aging might help improve age-associated metabolic disorders.
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Affiliation(s)
- Stéphanie Miard
- Laval Hospital Research Center, Laval University, Québec, QC, Canada
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200
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Lit L, Sharp FR, Apperson M, Liu DZ, Walker WL, Liao I, Xu H, Ander BP, Wong B. Corticosteroid effects on blood gene expression in Duchenne muscular dystrophy. THE PHARMACOGENOMICS JOURNAL 2009; 9:411-8. [PMID: 19488064 DOI: 10.1038/tpj.2009.22] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Though Deflazacort and prednisone improve clinical endpoints in Duchenne muscular dystrophy (DMD) patients, Deflazacort produces fewer side effects. As mechanisms of improvement and side effect differences remain unknown, we evaluated effects of corticosteroid administration on gene expression in blood of DMD patients. Whole blood was obtained from 14 children and adolescents with DMD treated with corticosteroids (DMD-STEROID) and 20 DMD children and adolescents naïve to corticosteroids (DMD). The DMD-STEROID group was further subdivided into Deflazacort and prednisone groups. Affymetrix U133 Plus 2.0 expression microarrays were used to evaluate mRNA expression. Expression of 524 probes changed with corticosteroids, including genes in iron trafficking and the chondroitin sulfate biosynthesis pathway. Deflazacort compared with prednisone yielded 508 regulated probes, including many involved in adipose metabolism. These genes and pathways help explain mechanisms of efficacy and side effects of corticosteroids, and could provide new treatment targets for DMD and other neuromuscular disorders.
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Affiliation(s)
- L Lit
- Department of Neurology, MIND Institute, University of California at Davis, Sacramento, CA 95817, USA.
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