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Elbein SC, Kern PA, Rasouli N, Yao-Borengasser A, Sharma NK, Das SK. Global gene expression profiles of subcutaneous adipose and muscle from glucose-tolerant, insulin-sensitive, and insulin-resistant individuals matched for BMI. Diabetes 2011; 60:1019-29. [PMID: 21266331 PMCID: PMC3046820 DOI: 10.2337/db10-1270] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE To determine altered gene expression profiles in subcutaneous adipose and skeletal muscle from nondiabetic, insulin-resistant individuals compared with insulin-sensitive individuals matched for BMI. RESEARCH DESIGN AND METHODS A total of 62 nondiabetic individuals were chosen for extremes of insulin sensitivity (31 insulin-resistant and 31 insulin-sensitive subjects; 40 were European American and 22 were African American) and matched for age and obesity measures. Global gene expression profiles were determined and compared between ethnic groups and between insulin-resistant and insulin-sensitive participants individually and using gene-set enrichment analysis. RESULTS African American and European American subjects differed in 58 muscle and 140 adipose genes, including many inflammatory and metabolically important genes. Peroxisome proliferator-activated receptor γ cofactor 1A (PPARGC1A) was 1.75-fold reduced with insulin resistance in muscle, and fatty acid and lipid metabolism and oxidoreductase activity also were downregulated. Unexpected categories included ubiquitination, citrullination, and protein degradation. In adipose, highly represented categories included lipid and fatty acid metabolism, insulin action, and cell-cycle regulation. Inflammatory genes were increased in European American subjects and were among the top Kyoto Encyclopedia of Genes and Genomes pathways on gene-set enrichment analysis. FADS1, VEGFA, PTPN3, KLF15, PER3, STEAP4, and AGTR1 were among genes expressed differentially in both adipose and muscle. CONCLUSIONS Adipose tissue gene expression showed more differences between insulin-resistant versus insulin-sensitive groups than the expression of genes in muscle. We confirm the role of PPARGC1A in muscle and show some support for inflammation in adipose from European American subjects but find prominent roles for lipid metabolism in insulin sensitivity independent of obesity in both tissues.
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Affiliation(s)
- Steven C. Elbein
- Section on Endocrinology and Metabolism, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Philip A. Kern
- Division of Endocrinology, Department of Internal Medicine, University of Kentucky School of Medicine, and the Barnstable Brown Diabetes and Obesity Center, Lexington, Kentucky
- Corresponding author: Swapan K. Das, , or Philip A. Kern,
| | - Neda Rasouli
- Division of Endocrinology, Department of Internal Medicine, University of Colorado Denver, Aurora, Colorado
- Veterans Administration, Eastern Colorado Health Care System, Denver, Colorado
| | - Aiwei Yao-Borengasser
- College of Medicine, Endocrinology Division, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Neeraj K. Sharma
- Section on Endocrinology and Metabolism, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina
| | - Swapan K. Das
- Section on Endocrinology and Metabolism, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina
- Corresponding author: Swapan K. Das, , or Philip A. Kern,
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Fidaleo M, Arnauld S, Clémencet MC, Chevillard G, Royer MC, De Bruycker M, Wanders RJA, Athias A, Gresti J, Clouet P, Degrace P, Kersten S, Espeel M, Latruffe N, Nicolas-Francès V, Mandard S. A role for the peroxisomal 3-ketoacyl-CoA thiolase B enzyme in the control of PPARα-mediated upregulation of SREBP-2 target genes in the liver. Biochimie 2011; 93:876-91. [PMID: 21352884 DOI: 10.1016/j.biochi.2011.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 02/11/2011] [Indexed: 11/16/2022]
Abstract
Peroxisomal 3-ketoacyl-CoA thiolase B (Thb) catalyzes the final step in the peroxisomal β-oxidation of straight-chain acyl-CoAs and is under the transcription control of the nuclear hormone receptor PPARα. PPARα binds to and is activated by the synthetic compound Wy14,643 (Wy). Here, we show that the magnitude of Wy-mediated induction of peroxisomal β-oxidation of radiolabeled (1-(14)C) palmitate was significantly reduced in mice deficient for Thb. In contrast, mitochondrial β-oxidation was unaltered in Thb(-/-) mice. Given that Wy-treatment induced Acox1 and MFP-1/-2 activity at a similar level in both genotypes, we concluded that the thiolase step alone was responsible for the reduced peroxisomal β-oxidation of fatty acids. Electron microscopic analysis and cytochemical localization of catalase indicated that peroxisome proliferation in the liver after Wy-treatment was normal in Thb(-/-) mice. Intriguingly, micro-array analysis revealed that mRNA levels of genes encoding cholesterol biosynthesis enzymes were upregulated by Wy in Wild-Type (WT) mice but not in Thb(-/-) mice, which was confirmed at the protein level for the selected genes. The non-induction of genes encoding cholesterol biosynthesis enzymes by Wy in Thb(-/-) mice appeared to be unrelated to defective SREBP-2 or PPARα signaling. No difference was observed in the plasma lathosterol/cholesterol ratio (a marker for de novo cholesterol biosynthesis) between Wy-treated WT and Thb(-/-) mice, suggesting functional compensation. Overall, we conclude that ThA and SCPx/SCP2 thiolases cannot fully compensate for the absence of ThB. In addition, our data indicate that ThB is involved in the regulation of genes encoding cholesterol biosynthesis enzymes in the liver, suggesting that the peroxisome could be a promising candidate for the correction of cholesterol imbalance in dyslipidemia.
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Affiliation(s)
- Marco Fidaleo
- Centre de recherche INSERM U866, Dijon F-21000, France; Université de Bourgogne, Faculté des Sciences Gabriel, Equipe Biochimie Métabolique et Nutritionnelle, Dijon F-21000, France
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53
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König B, Fischer S, Schlotte S, Wen G, Eder K, Stangl GI. Monocarboxylate transporter 1 and CD147 are up-regulated by natural and synthetic peroxisome proliferator-activated receptor alpha agonists in livers of rodents and pigs. Mol Nutr Food Res 2011; 54:1248-56. [PMID: 20306479 DOI: 10.1002/mnfr.200900432] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Monocarboxylate transporter (MCT)-1 mediates the transport of ketone bodies and other monocarboxylic acids across the plasma membrane. MCT1 is up-regulated by peroxisome proliferator-activated receptor (PPAR)-alpha, a transcription factor that mediates the adaptive response to fasting by up-regulation of genes involved in fatty acid oxidation and ketogenesis. Here, we show for the first time that MCT1 is up-regulated by dietary natural PPAR-alpha agonists. Both, an oxidized fat and conjugated linoleic acids increased MCT1 mRNA concentration in the liver of rats. Also, in the liver of pigs as non-proliferating species MCT1 was up-regulated upon PPAR-alpha activation by clofibrate, oxidized fat and fasting. Concomitant with up-regulation of MCT1, mRNA level of CD147 was increased in livers of rats and pigs. CD147 is a plasma membrane glycoprotein that is required for translocation and transport activity of MCT1. CD147 mRNA increase upon PPAR-alpha activation could not be observed in mice lacking PPAR-alpha, which also fail in up-regulation of MCT1 indicating a co-regulation of MCT1 and CD147. Analysis of the 5'-flanking region of mouse MCT1 gene by reporter gene assay revealed that promoter activity of mouse MCT1 was not induced by PPAR-alpha, indicating that the 5'-flanking region is not involved in MCT1 regulation by PPAR-alpha.
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Affiliation(s)
- Bettina König
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany.
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54
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Guelzim N, Mariotti F, Martin PGP, Lasserre F, Pineau T, Hermier D. A role for PPARα in the regulation of arginine metabolism and nitric oxide synthesis. Amino Acids 2010; 41:969-79. [PMID: 21063737 DOI: 10.1007/s00726-010-0797-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 10/22/2010] [Indexed: 01/08/2023]
Abstract
The pleiotropic effects of PPARα may include the regulation of amino acid metabolism. Nitric oxide (NO) is a key player in vascular homeostasis. NO synthesis may be jeopardized by a differential channeling of arginine toward urea (via arginase) versus NO (via NO synthase, NOS). This was studied in wild-type (WT) and PPARα-null (KO) mice fed diets containing either saturated fatty acids (COCO diet) or 18:3 n-3 (LIN diet). Metabolic markers of arginine metabolism were assayed in urine and plasma. mRNA levels of arginases and NOS were determined in liver. Whole-body NO synthesis and the conversion of systemic arginine into urea were assessed by using (15)N(2)-guanido-arginine and measuring urinary (15)NO(3) and [(15)N]-urea. PPARα deficiency resulted in a markedly lower whole-body NO synthesis, whereas the conversion of systemic arginine into urea remained unaffected. PPARα deficiency also increased plasma arginine and decreased citrulline concentration in plasma. These changes could not be ascribed to a direct effect on hepatic target genes, since NOS mRNA levels were unaffected, and arginase mRNA levels decreased in KO mice. Despite the low level in the diet, the nature of the fatty acids modulated some effects of PPARα deficiency, including plasma arginine and urea, which increased more in KO mice fed the LIN diet than in those fed the COCO diet. In conclusion, PPARα is largely involved in normal whole-body NO synthesis. This warrants further study on the potential of PPARα activation to maintain NO synthesis in the initiation of the metabolic syndrome.
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Affiliation(s)
- Najoua Guelzim
- UMR914 Nutrition Physiology and Ingestive Behavior, INRA, 16 rue Claude Bernard, 75005, Paris, France
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55
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Abstract
Tight control of storage and synthesis of glucose during nutritional transitions is essential to maintain blood glucose levels, a process in which the liver has a central role. PPARα is the master regulator of lipid metabolism during fasting, but evidence is emerging for a role of PPARα in balancing glucose homeostasis as well. By using PPARα ligands and PPARα(-/-) mice, several crucial genes were shown to be regulated by PPARα in a direct or indirect way. We here review recent evidence that PPARα contributes to the adaptation of hepatic carbohydrate metabolism during the fed-to-fasted or fasted-to-fed transition in rodents.
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56
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Rakhshandehroo M, Knoch B, Müller M, Kersten S. Peroxisome proliferator-activated receptor alpha target genes. PPAR Res 2010; 2010:612089. [PMID: 20936127 PMCID: PMC2948931 DOI: 10.1155/2010/612089] [Citation(s) in RCA: 560] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 08/09/2010] [Indexed: 12/11/2022] Open
Abstract
The peroxisome proliferator-activated receptor alpha (PPARα) is a ligand-activated transcription factor involved in the regulation of a variety of processes, ranging from inflammation and immunity to nutrient metabolism and energy homeostasis. PPARα serves as a molecular target for hypolipidemic fibrates drugs which bind the receptor with high affinity. Furthermore, PPARα binds and is activated by numerous fatty acids and fatty acid-derived compounds. PPARα governs biological processes by altering the expression of a large number of target genes. Accordingly, the specific role of PPARα is directly related to the biological function of its target genes. Here, we present an overview of the involvement of PPARα in lipid metabolism and other pathways through a detailed analysis of the different known or putative PPARα target genes. The emphasis is on gene regulation by PPARα in liver although many of the results likely apply to other organs and tissues as well.
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Affiliation(s)
- Maryam Rakhshandehroo
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Bianca Knoch
- Food, Metabolism & Microbiology, Food & Textiles Group, AgResearch, Palmerston North 4442, New Zealand
- Institute of Food, Nutrition & Human Health, Massey University, Tennent Drive, Palmerston North 4442, New Zealand
| | - Michael Müller
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands
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57
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D'Argenio G, Petillo O, Margarucci S, Torpedine A, Calarco A, Koverech A, Boccia A, Paolella G, Peluso G. Colon OCTN2 gene expression is up-regulated by peroxisome proliferator-activated receptor gamma in humans and mice and contributes to local and systemic carnitine homeostasis. J Biol Chem 2010; 285:27078-27087. [PMID: 20558736 PMCID: PMC2930707 DOI: 10.1074/jbc.m110.109678] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 05/07/2010] [Indexed: 12/25/2022] Open
Abstract
In the large intestine organic cation transporter type-2 (OCTN2) is recognized as a transporter of compounds such as carnitine and colony sporulation factor, promoting health of the colon intestinal epithelium. Recent reports suggest that OCTN2 expression in small intestine is under control of peroxisome proliferator-activated receptor-alpha (PPARalpha). However, PPARalpha contribution to colonic OCTN2 expression remains controversial. Here we examined the transcriptional regulation of colon OCTN2 gene by PPARgamma. To exclude any additional modulation of other PPAR to OCTN2 expression, we used both in vivo and in vitro PPAR-null models and specific PPAR inhibitors. The PPARgamma agonists thiazolidinediones increased both OCTN2 mRNA and protein expression in colonic epithelial cell lines independently by PPARalpha expression. The induction was blocked only by PPARgamma antagonists or by gammaORF4, a PPARgamma isoform with dominant negative activity, suggesting a PPARgamma-dependent mechanism. A conserved noncanonical PPAR-responsive element was found by computational analysis in the first intron of human OCTN2 gene and validated by EMSA assay. Promoter-reporter assays further confirmed transcriptional functionality of the putative PPAR response element, whereas selective mutation caused complete loss of responsiveness to PPARgamma activation. Finally, adenovirus-mediated overexpression of constitutively active PPARgamma mutant increased colon OCTN2 expression in PPARalpha(-/-) mice. Interestingly, animals overexpressing colon PPARgamma showed a significant increase in plasma carnitine, thus demonstrating the functional contribution of large intestine to systemic carnitine homeostasis. This study reveals a PPARgamma-dependent absorption machinery in colon that is likely involved in the health of colon epithelium, in the microbiota-host interactions and in the absorption of nutraceuticals and drugs.
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Affiliation(s)
- Giuseppe D'Argenio
- Gastroenterologia, Dipartimento di Medicina Clinica e Sperimentale, Federico II University, 80131 Naples, Italy
| | - Orsolina Petillo
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy
| | - Sabrina Margarucci
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy
| | - Angela Torpedine
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy
| | - Anna Calarco
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy
| | | | - Angelo Boccia
- Dipartimento di Biochimica e Biotecnologie Mediche, Federico II University, CEINGE-Biotecnologie Avanzate, 80131 Naples, Italy
| | - Giovanni Paolella
- Dipartimento di Biochimica e Biotecnologie Mediche, Federico II University, CEINGE-Biotecnologie Avanzate, 80131 Naples, Italy
| | - Gianfranco Peluso
- Istituto di Biochimica delle Proteine, Consiglio Nazionale delle Ricerche, 80131 Naples, Italy.
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58
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Doi R, Oishi K, Ishida N. CLOCK regulates circadian rhythms of hepatic glycogen synthesis through transcriptional activation of Gys2. J Biol Chem 2010; 285:22114-21. [PMID: 20430893 DOI: 10.1074/jbc.m110.110361] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Hepatic glycogen content is important for glucose homeostasis and exhibits robust circadian rhythms that peak at the end of the active phase in mammals. The activities of the rate-limiting enzymes for glycogenesis and glycogenolysis also show circadian rhythms, and the balance between them forms the circadian rhythm of the hepatic glycogen content. However, no direct evidence has yet implicated the circadian clock in the regulation of glycogen metabolism at the molecular level. We show here that a Clock gene mutation damps the circadian rhythm of the hepatic glycogen content, as well as the circadian mRNA and protein expression of Gys2 (glycogen synthase 2), which is the rate-limiting enzyme of glycogenesis in the liver. Transient reporter assays revealed that CLOCK drives the transcriptional activation of Gys2 via two tandemly located E-boxes. Chromatin immunoprecipitation assays of liver tissues revealed that CLOCK binds to these E-box elements in vivo, and real time reporter assays showed that these elements are sufficient for circadian Gys2 expression in vitro. Thus, CLOCK regulates the circadian rhythms of hepatic glycogen synthesis through transcriptional activation of Gys2.
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Affiliation(s)
- Ryosuke Doi
- Ishida Group of Clock Gene, National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
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59
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van der Meer DLM, Degenhardt T, Väisänen S, de Groot PJ, Heinäniemi M, de Vries SC, Müller M, Carlberg C, Kersten S. Profiling of promoter occupancy by PPARalpha in human hepatoma cells via ChIP-chip analysis. Nucleic Acids Res 2010; 38:2839-50. [PMID: 20110263 PMCID: PMC2875002 DOI: 10.1093/nar/gkq012] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The transcription factor peroxisome proliferator-activated receptor alpha (PPARalpha) is an important regulator of hepatic lipid metabolism. While PPARalpha is known to activate transcription of numerous genes, no comprehensive picture of PPARalpha binding to endogenous genes has yet been reported. To fill this gap, we performed Chromatin immunoprecipitation (ChIP)-chip in combination with transcriptional profiling on HepG2 human hepatoma cells treated with the PPARalpha agonist GW7647. We found that GW7647 increased PPARalpha binding to 4220 binding regions. GW7647-induced binding regions showed a bias around the transcription start site and most contained a predicted PPAR binding motif. Several genes known to be regulated by PPARalpha, such as ACOX1, SULT2A1, ACADL, CD36, IGFBP1 and G0S2, showed GW7647-induced PPARalpha binding to their promoter. A GW7647-induced PPARalpha-binding region was also assigned to SREBP-targets HMGCS1, HMGCR, FDFT1, SC4MOL, and LPIN1, expression of which was induced by GW7647, suggesting cross-talk between PPARalpha and SREBP signaling. Our data furthermore demonstrate interaction between PPARalpha and STAT transcription factors in PPARalpha-mediated transcriptional repression, and suggest interaction between PPARalpha and TBP, and PPARalpha and C/EBPalpha in PPARalpha-mediated transcriptional activation. Overall, our analysis leads to important new insights into the mechanisms and impact of transcriptional regulation by PPARalpha in human liver and highlight the importance of cross-talk with other transcription factors.
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Affiliation(s)
- David L M van der Meer
- Nutrition, Metabolism and Genomics group, Division of Human Nutrition, Wageningen University, Bomenweg 2, NL-6703 HD Wageningen, The Netherlands
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60
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Wen G, Ringseis R, Eder K. Mouse OCTN2 is directly regulated by peroxisome proliferator-activated receptor alpha (PPARalpha) via a PPRE located in the first intron. Biochem Pharmacol 2009; 79:768-76. [PMID: 19819229 DOI: 10.1016/j.bcp.2009.10.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 09/30/2009] [Accepted: 10/01/2009] [Indexed: 10/20/2022]
Abstract
Recent studies provided strong evidence to suggest that organic cation transporter 2 (OCTN2) is a direct target gene of peroxisome proliferator-activated receptor alpha (PPARalpha). However, subsequent studies failed to demonstrate a functional peroxisome proliferator response element (PPRE) in the promoter region of the OCTN2 gene. In the present study we hypothesized that the OCTN2 gene is transcriptionally induced by PPARalpha via a functional PPRE located in the first intron. In silico-analysis of the first intron of mouse OCTN2 revealed 11 putative PPRE with high similarity to the consensus PPRE. In addition, reporter gene assays using a mouse OCTN2 intron reporter construct containing a cluster of three partially overlapping PPRE (PPREint-1-8-10) revealed a marked response to exogenous mouse PPARalpha/RXRalpha and subsequent stimulation with PPARalpha agonist WY-14,643. Introduction of a selective mutation in either PPRE8 or PPRE10 in the PPREint-1-8-10 reporter constructs caused a substantial loss of the responsiveness to PPARalpha activation, but a selective mutation in PPRE1 resulted in a complete loss of responsiveness to PPARalpha activation. Moreover, gel shift assays revealed binding of PPARalpha/RXRalpha heterodimer to the PPRE1 of mouse OCTN2 first intron. In conclusion, the present study shows that mouse OCTN2 is a direct target gene of PPARalpha and that transcriptional upregulation of OCTN2 by PPARalpha is likely mediated via PPRE1 in its first intron.
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Affiliation(s)
- Gaiping Wen
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 2, 06120 Halle (Saale), Germany
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61
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Stienstra R, Duval C, Keshtkar S, van der Laak J, Kersten S, Müller M. Peroxisome proliferator-activated receptor gamma activation promotes infiltration of alternatively activated macrophages into adipose tissue. J Biol Chem 2008; 283:22620-7. [PMID: 18541527 DOI: 10.1074/jbc.m710314200] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Obesity is associated with infiltration of macrophages into adipose tissue. Adipose macrophages may contribute to an elevated inflammatory status by secreting a variety of proinflammatory mediators, including tumor necrosis factor alpha and interleukin-6 (IL-6). Recent data suggest that during diet-induced obesity the phenotype of adipose-resident macrophages changes from alternatively activated macrophages toward a more classical and pro-inflammatory phenotype. Here, we explore the effect of peroxisome proliferator-activated receptor gamma activation on obesity-induced inflammation in 129SV mice fed a high fat diet for 20 weeks. High fat feeding increased bodyweight gain, adipose tissue mass, and liver triglycerides. Rosiglitazone treatment further increased adipose mass, reduced liver triglycerides, and changed adipose tissue morphology toward smaller adipocytes. Surprisingly, rosiglitazone markedly increased the number of macrophages in adipose tissue, as shown by immunohistochemical analysis and quantification of macrophage marker genes CD68 and F4/80+. In adipose tissue, markers for classically activated macrophages including IL-18 were down-regulated, whereas markers characteristic for alternatively activated macrophages (arginase 1, IL-10) were up-regulated by rosiglitazone. Importantly, conditioned media from rosiglitazone-treated alternatively activated macrophages neutralized the inhibitory effect of macrophages on 3T3-L1 adipocyte differentiation, suggesting that alternatively activated macrophages may be involved in mediating the effects of rosiglitazone on adipose tissue morphology and mass. Our results suggest that short term rosiglitazone treatment increases infiltration of alternatively activated macrophages in adipose tissue. The alternatively activated macrophages might play a role in peroxisome proliferator-activated receptor gamma-dependent expansion and remodeling of adipose tissue.
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Affiliation(s)
- Rinke Stienstra
- Nutrition, Metabolism, and Genomics Group, Division of Human Nutrition, Wageningen University, 6700 EV Wageningen, The Netherlands
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62
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Bibliography. Current world literature. Lipid metabolism. Curr Opin Lipidol 2008; 19:314-21. [PMID: 18460925 DOI: 10.1097/mol.0b013e328303e27e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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63
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Hoeks J, Briedé JJ, de Vogel J, Schaart G, Nabben M, Moonen-Kornips E, Hesselink MKC, Schrauwen P. Mitochondrial function, content and ROS production in rat skeletal muscle: effect of high-fat feeding. FEBS Lett 2008; 582:510-6. [PMID: 18230360 DOI: 10.1016/j.febslet.2008.01.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 01/03/2008] [Accepted: 01/15/2008] [Indexed: 12/25/2022]
Abstract
A high intake of dietary fat has been suggested to diminish mitochondrial functioning in skeletal muscle, possibly attributing to muscular fat accumulation. Here we show however, that an 8-week high-fat dietary intervention did not affect intrinsic functioning of rat skeletal muscle mitochondria assessed by respirometry, neither on a carbohydrate- nor on a lipid-substrate. Interestingly, PPARGC1A protein increased by approximately 2-fold upon high-fat feeding and we observed inconsistent results on different markers of mitochondrial density. Mitochondrial ROS production, assessed by electron spin resonance spectroscopy remained unaffected. Intramyocellular lipid levels increased significantly illustrating that a reduced innate mitochondrial function is not a prerequisite for intra-muscular fat accumulation.
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Affiliation(s)
- Joris Hoeks
- Department of Human Biology, Nutrition and Toxicology Research Institute Maastricht, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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Sun Y, Ng L, Lam W, Lo CKC, Chan PT, Yuen YL, Wong PF, Tsang DSC, Cheung WT, Lee SST. Identification and characterization of a novel mouse peroxisome proliferator-activated receptor alpha-regulated and starvation-induced gene, Ppsig. Int J Biochem Cell Biol 2008; 40:1775-91. [PMID: 18289917 DOI: 10.1016/j.biocel.2008.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 01/09/2008] [Accepted: 01/09/2008] [Indexed: 10/22/2022]
Abstract
The peroxisome proliferator-activated receptor alpha (PPARalpha) has been known to play a pivotal role in maintaining the energy balance during fasting; however, the battery of PPARalpha target genes involved in this metabolic response is still not fully characterized. Here, we report the identification and characterization of Ppsig (for PPARalpha-regulated and starvation-induced gene) with unknown biological function from mouse liver. Multiple Ppsig cDNAs which differed in the 3'-untranslated regions were identified. The open reading frame of Ppsig cDNA is 1830 bp which encodes a protein of 67.33 kDa. Ppsig contains 11 exons spanning at least 10 kb. Although the exact biological function of Ppsig is still not known, we found that Ppsig mRNA transcript was dramatically up-regulated during 72 h fasting and following treatment with a potent PPARalpha agonist, in a tissue-specific and PPARalpha-dependent manner. A functional peroxisome proliferator-response element was found in the intron 1 of Ppsig, thus confirming that Ppsig is a novel direct mouse PPARalpha target gene. This finding might help in elucidating the transcriptional regulatory mechanism of Ppsig in the cellular response to fasting.
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Affiliation(s)
- Yan Sun
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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