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• W1985280131 abstract "Epigenetic modification through DNA methylation is implicated in metabolic disease. Using whole-genome promoter methylation analysis of skeletal muscle from normal glucose-tolerant and type 2 diabetic subjects, we identified cytosine hypermethylation of peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1 α (PGC-1α) in diabetic subjects. Methylation levels were negatively correlated with PGC-1α mRNA and mitochondrial DNA (mtDNA). Bisulfite sequencing revealed that the highest proportion of cytosine methylation within PGC-1α was found within non-CpG nucleotides. Non-CpG methylation was acutely increased in human myotubes by exposure to tumor necrosis factor-α (TNF-α) or free fatty acids, but not insulin or glucose. Selective silencing of the DNA methyltransferase 3B (DNMT3B), but not DNMT1 or DNMT3A, prevented palmitate-induced non-CpG methylation of PGC-1α and decreased mtDNA and PGC-1α mRNA. We provide evidence for PGC-1α hypermethylation, concomitant with reduced mitochondrial content in type 2 diabetic patients, and link DNMT3B to the acute fatty-acid-induced non-CpG methylation of PGC-1α promoter. Epigenetic modification through DNA methylation is implicated in metabolic disease. Using whole-genome promoter methylation analysis of skeletal muscle from normal glucose-tolerant and type 2 diabetic subjects, we identified cytosine hypermethylation of peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1 α (PGC-1α) in diabetic subjects. Methylation levels were negatively correlated with PGC-1α mRNA and mitochondrial DNA (mtDNA). Bisulfite sequencing revealed that the highest proportion of cytosine methylation within PGC-1α was found within non-CpG nucleotides. Non-CpG methylation was acutely increased in human myotubes by exposure to tumor necrosis factor-α (TNF-α) or free fatty acids, but not insulin or glucose. Selective silencing of the DNA methyltransferase 3B (DNMT3B), but not DNMT1 or DNMT3A, prevented palmitate-induced non-CpG methylation of PGC-1α and decreased mtDNA and PGC-1α mRNA. We provide evidence for PGC-1α hypermethylation, concomitant with reduced mitochondrial content in type 2 diabetic patients, and link DNMT3B to the acute fatty-acid-induced non-CpG methylation of PGC-1α promoter. Type 2 diabetes mellitus (T2DM) and its associated metabolic consequences, such as kidney and heart failure, are leading causes of morbidity and mortality worldwide. T2DM is a chronic disorder characterized by insulin resistance in adipose tissue, liver, and skeletal muscle, which are metabolic organs affected by an impaired insulin secretion of the β-pancreatic cell. In particular, defects in skeletal muscle metabolism play a primary role in the development of whole-body insulin resistance (Eriksson et al., 1989Eriksson J. Franssila-Kallunki A. Ekstrand A. Saloranta C. Widén E. Schalin C. Groop L. Early metabolic defects in persons at increased risk for non-insulin-dependent diabetes mellitus.N. Engl. J. Med. 1989; 321: 337-343Crossref PubMed Scopus (787) Google Scholar), as this tissue is the major site of insulin-mediated glucose disposal (DeFronzo et al., 1985DeFronzo R.A. Gunnarsson R. Björkman O. Olsson M. Wahren J. Effects of insulin on peripheral and splanchnic glucose metabolism in noninsulin-dependent (type II) diabetes mellitus.J. Clin. Invest. 1985; 76: 149-155Crossref PubMed Scopus (839) Google Scholar). The mechanisms underlying insulin resistance and T2DM are incompletely understood, but genetic and environmental factors such as physical activity and diet/nutrition are involved. Epigenetic modifications of the genome, including DNA methylation, provide a potential molecular basis for the interaction between genetic and environmental factors on glucose homeostasis and may contribute to the manifestation of T2DM. Dietary factors that affect the activity of enzymes supplying methyl groups can influence the rate of disease manifestation (Van den Veyver, 2002Van den Veyver I.B. Genetic effects of methylation diets.Annu. Rev. Nutr. 2002; 22: 255-282Crossref PubMed Scopus (176) Google Scholar). Evidence for a nutritional effect on epigenetic regulation in T2DM is suggested by a generational study in humans showing that the nutritional status of the parent is closely linked with an increased risk of T2DM-associated mortality in the second generation, raising the possibility of a role for epigenetic modifications of genomic DNA in metabolic disease (Pembrey et al., 2006Pembrey M.E. Bygren L.O. Kaati G. Edvinsson S. Northstone K. Sjöström M. Golding J. Sex-specific, male-line transgenerational responses in humans.Eur. J. Hum. Genet. 2006; 14: 159-166Crossref PubMed Scopus (791) Google Scholar). The impact of nutrition on DNA methylation has been directly shown in the agouti mice, whereby methyl donor supplementation prevented DNA hypomethylation of the intracisternal A particle retroviral element into the agouti gene of the offspring (Cooney et al., 2002Cooney C.A. Dave A.A. Wolff G.L. Maternal methyl supplements in mice affect epigenetic variation and DNA methylation of offspring.J. Nutr. 2002; 132: 2393S-2400SPubMed Google Scholar, Michaud et al., 1994Michaud E.J. van Vugt M.J. Bultman S.J. Sweet H.O. Davisson M.T. Woychik R.P. Differential expression of a new dominant agouti allele (Aiapy) is correlated with methylation state and is influenced by parental lineage.Genes Dev. 1994; 8: 1463-1472Crossref PubMed Scopus (222) Google Scholar, Morgan et al., 1999Morgan H.D. Sutherland H.G. Martin D.I. Whitelaw E. Epigenetic inheritance at the agouti locus in the mouse.Nat. Genet. 1999; 23: 314-318Crossref PubMed Scopus (1026) Google Scholar). Whether epigenetic modifications acutely occur in somatic tissues of mammalian origin is unknown. Here, we performed a genome-wide promoter analysis of DNA methylation to screen for genes differentially methylated in T2DM. We identified hypermethylation of genes involved in mitochondrial function, such as the peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1 α (PGC-1α), and provide a mechanism by which elevations in cytokines or lipids induce non-CpG methylation of the PGC-1α promoter in skeletal muscle. Our results provide insight into the acute reprogramming of gene expression through methylation in metabolic disease. We used methylated DNA immunoprecipitation (MeDIP), combined with microarray technology (Keshet et al., 2006Keshet I. Schlesinger Y. Farkash S. Rand E. Hecht M. Segal E. Pikarski E. Young R.A. Niveleau A. Cedar H. et al.Evidence for an instructive mechanism of de novo methylation in cancer cells.Nat. Genet. 2006; 38: 149-153Crossref PubMed Scopus (379) Google Scholar, Weber et al., 2005Weber M. Davies J.J. Wittig D. Oakeley E.J. Haase M. Lam W.L. Schübeler D. Chromosome-wide and promoter-specific analyses identify sites of differential DNA methylation in normal and transformed human cells.Nat. Genet. 2005; 37: 853-862Crossref PubMed Scopus (1314) Google Scholar), to discover whether changes in DNA methylation are specific to T2DM. A cohort of normal glucose-tolerant (NGT) and T2DM male volunteers was studied. The metabolic characteristics are presented in the Supplemental Data (Table S1). Importantly, we studied closely age-matched groups to exclude any possible effect of aging, since aging has been associated with methylation events (Bjornsson et al., 2008Bjornsson H.T. Sigurdsson M.I. Fallin M.D. Irizarry R.A. Aspelund T. Cui H. Yu W. Rongione M.A. Ekström T.J. Harris T.B. et al.Intra-individual change over time in DNA methylation with familial clustering.JAMA. 2008; 299: 2877-2883Crossref PubMed Scopus (515) Google Scholar, Issa et al., 1994Issa J.P. Ottaviano Y.L. Celano P. Hamilton S.R. Davidson N.E. Baylin S.B. Methylation of the oestrogen receptor CpG island links ageing and neoplasia in human colon.Nat. Genet. 1994; 7: 536-540Crossref PubMed Scopus (1030) Google Scholar, Siegmund et al., 2007Siegmund K.D. Connor C.M. Campan M. Long T.I. Weisenberger D.J. Biniszkiewicz D. Jaenisch R. Laird P.W. Akbarian S. DNA methylation in the human cerebral cortex is dynamically regulated throughout the life span and involves differentiated neurons.PLoS ONE. 2007; 2: e895Crossref PubMed Scopus (332) Google Scholar). Oxidative capacity, as measured by VO2 max, and body mass index (BMI) were not significantly different between the groups studied. To identify candidate genes for methylation events, vastus lateralis muscle biopsies obtained from the volunteers were studied. Samples enriched for methylated DNA fragments were probed on an array covering approximately 7.5 kb upstream through 2.45 kb downstream of referenced 5′ transcription start sites. Of 25,500 promoter regions represented on the array, 838 were differentially methylated (p < 0.05) in skeletal muscle obtained from NGT versus T2DM subjects. To identify groups of genes with similar changes in methylation in skeletal muscle from T2DM patients, we defined the biological processes of the identified genes using a gene ontology classification (Dennis et al., 2003Dennis G. Sherman B.T. Hosack D.A. Yang J. Gao W. Lane H.C. Lempicki R.A. DAVID: Database for annotation, visualization, and integrated discovery.Genome Biol. 2003; 4: 3Crossref PubMed Google Scholar). We ranked genes by the level of statistical significance (p values) and number of genes in the gene ontology clusters (Table S2). We revealed 44 positive genes as classified in the mitochondrion ontology (Table S3). Of interest, the PGC-1α promoter was hypermethylated in skeletal muscle from T2DM patients compared to NGT subjects (p < 0.05) (Figure 1A). We validated the MeDIP result for PGC-1α using bisulfite sequencing. Genomic DNA was extracted from vastus lateralis muscle biopsies obtained from NGT, impaired glucose-tolerant (IGT), or T2DM subjects (Table S1). Bisulfite sequencing was performed on a portion of the promoter encompassing −337 to −37 relative to the +1 transcription start site of PGC-1α gene in each individual (Figures 1B and S1). The efficiency of the bisulfite conversion was compared to the unmethylated fragment of the region of interest of the PGC-1α promoter (Figure 1C). We found a 2.7- and 2.2-fold increase in unconverted cytosines on the PGC-1α promoter of IGT and T2DM patients, respectively, compared to NGT subjects (Figure 1C). An alternative promoter of human PGC-1α has recently been identified (Yoshioka et al., 2009Yoshioka T. Inagaki K. Noguchi T. Sakai M. Ogawa W. Hosooka T. Iguchi H. Watanabe E. Matsuki Y. Hiramatsu R. et al.Identification and characterization of an alternative promoter of the human PGC-1alpha gene.Biochem. Biophys. Res. Commun. 2009; 381: 537-543Crossref PubMed Scopus (40) Google Scholar). Methylation of a portion encompassing −243 to −47 relative to the +1 transcription start site of PGC-1α alternative promoter was similar in NGT as compared to T2DM subjects. Through further bisulfite sequencing of DHX15 and GBA3, two genes proximal to PGC-1α, we reveal that hypermethylation in T2DM is not broadly altered on a wide portion of the chromatin, but is specific to the canonical PGC-1α promoter (Figure 2). Most of the methylated cytosines were found within non-CpG dinucleotides (Figure S1). Of interest, the hypermethylation pattern observed in the T2DM patients was unrelated to family history of the disease. Our findings highlight the potential physiological importance of non-CpG methylation in human skeletal muscle, since non-CpG methylation has been almost exclusively reported in plants and embryonic stem cells (Grandjean et al., 2007Grandjean V. Yaman R. Cuzin F. Rassoulzadegan M. Inheritance of an epigenetic mark: the CpG DNA methyltransferase 1 is required for de novo establishment of a complex pattern of non-CpG methylation.PLoS ONE. 2007; 2: e1136Crossref PubMed Scopus (63) Google Scholar, Meyer et al., 1994Meyer P. Niedenhof I. ten Lohuis M. Evidence for cytosine methylation of non-symmetrical sequences in transgenic Petunia hybrida.EMBO J. 1994; 13: 2084-2088PubMed Google Scholar, Ramsahoye et al., 2000Ramsahoye B.H. Biniszkiewicz D. Lyko F. Clark V. Bird A.P. Jaenisch R. Non-CpG methylation is prevalent in embryonic stem cells and may be mediated by DNA methyltransferase 3a.Proc. Natl. Acad. Sci. USA. 2000; 97: 5237-5242Crossref PubMed Scopus (694) Google Scholar). Given that DNA methylation located within or close to the 5′ region of genes has been associated with regulation of gene expression (Costello and Plass, 2001Costello J.F. Plass C. Methylation matters.J. Med. Genet. 2001; 38: 285-303Crossref PubMed Scopus (453) Google Scholar), we next assessed whether PGC-1α mRNA expression was altered in skeletal muscle biopsies from NGT and T2DM subjects. PGC-1α mRNA content was decreased 38% in T2DM patients (Figure 1D) and negatively correlated with promoter methylation (ρ = −0.56, p = 0.036) (Figure 1E). Further investigation of the role of PGC-1α promoter methylation on gene activity using a gene reporter assay revealed that in vitro methylation of a single cytosine residue (located −260 relative to the +1 transcription start site) caused a marked reduction of gene activity (Figure 1F). Several lines of evidence suggest that insulin resistance and T2DM are associated with decreased skeletal muscle mitochondrial function, which can reduce cellular and whole-body oxidative capacity (Kelley et al., 2002Kelley D.E. He J. Menshikova E.V. Ritov V.B. Dysfunction of mitochondria in human skeletal muscle in type 2 diabetes.Diabetes. 2002; 51: 2944-2950Crossref PubMed Scopus (1625) Google Scholar, Simoneau and Kelley, 1997Simoneau J.A. Kelley D.E. Altered glycolytic and oxidative capacities of skeletal muscle contribute to insulin resistance in NIDDM.J. Appl. Physiol. 1997; 83: 166-171Crossref PubMed Scopus (331) Google Scholar). Reductions in mitochondrial density have also been proposed as a primary cause of mitochondrial dysfunction in insulin-resistant states (Boushel et al., 2007Boushel R. Gnaiger E. Schjerling P. Skovbro M. Kraunsoe R. Dela F. Patients with type 2 diabetes have normal mitochondrial function in skeletal muscle.Diabetologia. 2007; 50: 790-796Crossref PubMed Scopus (382) Google Scholar). Here, we show that PGC-1α promoter methylation was negatively correlated with mitochondrial DNA (mtDNA) content, as measured by ratio of mtDNA to nuclear DNA (nDNA) using real-time quantitative PCR (ρ = −0.55, p = 0.043) (Figure S2). PGC-1α is a key factor that coordinately regulates the expression of a subset of mitochondrial genes and participates in the overall mitochondrial function in the cell (Lin et al., 2005Lin J. Handschin C. Spiegelman B.M. Metabolic control through the PGC-1 family of transcription coactivators.Cell Metab. 2005; 1: 361-370Abstract Full Text Full Text PDF PubMed Scopus (1514) Google Scholar). To examine whether mitochondrial content is altered in skeletal muscle from T2DM patients, proteins from the mitochondrial respiratory chain were measured in crude lysates. The relative amounts of succinate-ubiquinol reductase (SUO or complex II), core I (complex III), and cytochrome C (CytC) were significantly decreased in T2DM patients compared with NGT subjects (Figures 3A and 3B). Additionally, the level of expression of the mitochondrial transcription factor A (TFAM), a key protein in the regulation of mtDNA quantity, was significantly decreased in T2DM compared with NGT subjects (Figures 3A and 3B). The ratio of mtDNA per nucleus was decreased 22% in T2DM patients (Figure 3C). Ultrastructural analysis of skeletal muscle obtained from each cohort further supports these findings, as both mitochondrial number and area were significantly reduced (p < 0.001) in T2DM patients compared with NGT subjects (Figures 4A–4C). Thus, mitochondrial markers were decreased in skeletal muscle from T2DM patients, indicative of altered mitochondrial content in this cohort.Figure 4Decreased Mitochondrial Content in Type 2 Diabetic PatientsShow full caption(A–C) Mitochondrial ultrastructure was examined in skeletal muscle from NGT (n = 3) and T2DM (n = 3) subjects by transmission electron microscopy. Representative images of samples from an NGT subject and a T2DM patient are shown (A). Note the mitochondria located between contractile units (arrows). Images are of type I fibers (note the thick Z-line); scale bar represents 500 nm. The number (B) and area (C) of mitochondria were determined from images captured at 2800× with an area of 7.2 μm2. Bars represent the mean of all images counted, and points represent means of individual subjects. Area data are expressed in mitochondria area per total image area (∗p < 0.001).View Large Image Figure ViewerDownload Hi-res image Download (PPT) (A–C) Mitochondrial ultrastructure was examined in skeletal muscle from NGT (n = 3) and T2DM (n = 3) subjects by transmission electron microscopy. Representative images of samples from an NGT subject and a T2DM patient are shown (A). Note the mitochondria located between contractile units (arrows). Images are of type I fibers (note the thick Z-line); scale bar represents 500 nm. The number (B) and area (C) of mitochondria were determined from images captured at 2800× with an area of 7.2 μm2. Bars represent the mean of all images counted, and points represent means of individual subjects. Area data are expressed in mitochondria area per total image area (∗p < 0.001). Alterations in the extracellular milieu, including hyperglycemia, hyperinsulinemia, elevated free fatty acids, and elevated cytokines, can cause peripheral insulin resistance in T2DM. To investigate whether these external factors directly and acutely alter the methylation status, we used primary human skeletal muscle cells derived from vastus lateralis biopsies obtained from NGT men and screened for putative factors involved in PGC-1α methylation. Primary human skeletal muscle cultures were incubated for 48 hr with various factors known to induce insulin resistance (Figure 5A). TNF-α, palmitate, and oleate induced hypermethylation of the PGC-1α promoter, whereas high glucose or insulin concentrations were without effect. Similar to our results in muscle tissue, bisulfite sequencing revealed that the majority of the methylated cytosines were located outside of CpG nucleotides (Figure 5B). We next evaluated whether these changes occurred as a consequence of whole-genome methylation using luminometric methylation assays (LUMA). Upon palmitate treatment, we found that both global CpA and CpT methylation within 5′-CCA/TGG-3′ was increased from 1.6% to 4.2% (Figure 6A), although CpG methylation within the 5′-CCGG-3′ sequence was unaltered (Figure 6B). In vastus lateralis, we observed similar CpG and non-CpG levels (Figures 6C and 6D). These results provide further evidence of high non-CpG methylation in human skeletal muscle. Moreover, global methylation levels were unchanged in T2DM patients (Figures 6C and 6D), suggesting that hypermethylation is gene specific. Collectively, these data provide evidence that free fatty acids acutely induce non-CpG methylation at the PGC-1α promoter and at the whole-genome level in primary human myocytes.Figure 6Luminometric Assay Analysis of Global DNA MethylationShow full caption(A–D) Global CpG and non-CpG methylation analysis in primary human myocytes exposed to palmitate is shown in (A) and (B). Global CpG and non-CpG methylation analyses in vastus lateralis biopsies from people with NGT or T2DM are shown in (C) and (D). Genomic DNA was digested using the restriction enzymes Psp6I and AjnI. The ratio (Psp6I)/(AjnI) was plotted to a standard curve to determine the percent CCWGG methylation levels. Results are mean ± SEM (A and C). Genomic DNA was also digested using the restriction enzymes MspI, HpaII, and EcoRI. The value [1 − (HpaII/EcoRI)/(MspI/EcoRI)] × 100 was used as percent CCGG methylation level. Results are mean ± SEM (B and D).View Large Image Figure ViewerDownload Hi-res image Download (PPT) (A–D) Global CpG and non-CpG methylation analysis in primary human myocytes exposed to palmitate is shown in (A) and (B). Global CpG and non-CpG methylation analyses in vastus lateralis biopsies from people with NGT or T2DM are shown in (C) and (D). Genomic DNA was digested using the restriction enzymes Psp6I and AjnI. The ratio (Psp6I)/(AjnI) was plotted to a standard curve to determine the percent CCWGG methylation levels. Results are mean ± SEM (A and C). Genomic DNA was also digested using the restriction enzymes MspI, HpaII, and EcoRI. The value [1 − (HpaII/EcoRI)/(MspI/EcoRI)] × 100 was used as percent CCGG methylation level. Results are mean ± SEM (B and D). In mammals, three functional DNA methyltransferase (DNMT) isoforms have been identified: DNMT1, DNMT3A, and DNMT3B. To identify whether DNMTs are involved in palmitate-induced PGC-1α promoter methylation, we selectively silenced DNMT1, DNMT3A, and DNMT3B in human primary muscle cells. Gene silencing of either DNMT1 or DNMT3A failed to rescue palmitate-induced downregulation of PGC-1α mRNA and mitochondrial gene expression (Figure S3). In contrast, silencing of DNMT3B 43% (Figure 7A) prevented palmitate-induced PGC-1α promoter methylation (Figure 7B). Furthermore, the palmitate-induced reduction of mtDNA content, as evaluated by the mtDNA to nDNA ratio, was partly prevented by DNMT3B silencing (Figure 7C). Quantitative PCR was also performed to detect any variation in the expression of genes related to mitochondrial function and biogenesis (Figure 7D). DNMT3B silencing prevented the palmitate-induced downregulated mRNA expression of PGC-1α, TFAM, citrate synthase (CS), and carnitine palmitoyltransferase (CPT)-2. Conversely, the effect of palmitate treatment to upregulate mRNA expression of CPT-1 and CytC was unaltered by DNMT3B silencing. Nuclear respiratory factor 1 (NRF-1) was unaltered by either palmitate treatment or DNMT3B silencing. Thus, the expression of a subset of genes important for mitochondrial regulation is downregulated following palmitate exposure in a DNMT3B-dependent manner. We cannot directly link PGC-1α to the regulation of these genes, because changes in gene expression could have been caused by a direct effect of palmitate. These genes may themselves be targets of dynamic regulation via methylation, or they may be regulated as a consequence of the reduction in PGC-1α expression. For example, our MeDIP analysis revealed TFAM and CPT-2 are hypermethylated in skeletal muscle from T2DM patients (data not shown). These results provide evidence that DNMT3B plays a role in palmitate-induced DNA methylation and the control of mitochondrial marker gene expression in human skeletal muscle cells. However, protein content of DNMT isoforms were unchanged following 48 hr exposure of human myocytes to high concentrations of glucose, insulin, palmitate, oleate, or TNF-α (Figure S4A). In skeletal muscle from NGT and T2DM subjects, quantitative analysis of DNMT isoforms using RT-PCR revealed mRNA expression of DNMT3B (normalized to actin) was increased in T2DM versus NGT subjects (378 ± 42 versus 215 ± 46 arbitrary units, respectively; p < 0.05). In contrast, mRNA expression of DNMT1 (1685 ± 201 versus 1580 ± 315 arbitrary units) and DNMT3A (6168 ± 633 versus 6161 ± 857 arbitrary units) was unchanged between T2DM and NGT subjects, which further supports a role of DNMT3B in increased methylation levels. However, protein content was unaltered between T2DM and NGT subjects (Figure S4B). Thus, collectively, our results suggest that enzymatic activation of DNMT3B, rather than changes in protein expression, is involved in hypermethylation of the PGC-1α promoter. Mitochondrial dysfunction has been proposed to contribute to impaired fat oxidation and excess lipid storage in skeletal muscle (Morino et al., 2006Morino K. Petersen K.F. Shulman G.I. Molecular mechanisms of insulin resistance in humans and their potential links with mitochondrial dysfunction.Diabetes. 2006; 55: S9-S15Crossref PubMed Scopus (608) Google Scholar). Here, we provide evidence for epigenetic modifications on the PGC-1α promoter in skeletal muscle from T2DM patients using genome-wide promoter screening of DNA methylation. PGC-1α is a master regulator of mitochondrial biogenesis and function (Wu et al., 1999Wu Z. Puigserver P. Andersson U. Zhang C. Adelmant G. Mootha V. Troy A. Cinti S. Lowell B. Scarpulla R.C. et al.Mechanisms controlling mitochondrial biogenesis and respiration through the thermogenic coactivator PGC-1.Cell. 1999; 98: 115-124Abstract Full Text Full Text PDF PubMed Scopus (2904) Google Scholar). Hypermethylation of the PGC-1α promoter was associated with reduced PGC-1α expression and implicates a mechanism for decreased mitochondrial content in T2DM. Downregulation of PGC-1α expression in T2DM subjects was previously reported (Mootha et al., 2003Mootha V.K. Lindgren C.M. Eriksson K.F. Subramanian A. Sihag S. Lehar J. Puigserver P. Carlsson E. Ridderstråle M. Laurila E. et al.PGC-1alpha-responsive genes involved in oxidative phosphorylation are coordinately downregulated in human diabetes.Nat. Genet. 2003; 34: 267-273Crossref PubMed Scopus (5043) Google Scholar). Consistent with the notion that mitochondrial oxidative capacity is impaired in T2DM, we report that PGC-1α and several mitochondrial markers, including TFAM, CytC, SUO, and core I, as well as mtDNA/nDNA and mitochondrial size and number, are reduced. In the present study, we couple PGC-1α promoter hypermethylation with reduced mitochondrial density and provide a potential mechanism for mitochondrial dysfunction in T2DM. Whether alterations in mitochondrial function or PGC-1α levels are directly linked to insulin resistance or diabetes remains unclear. However, we observed a negative association between PGC-1α promoter methylation and mRNA levels and also provide evidence that DNA methylation influences PGC-1α promoter activity. Furthermore, the PGC-1α promoter is hypermethylated in skeletal muscle from IGT subjects, indicating this may be an early event in the pathogenesis of insulin resistance in T2DM. Nevertheless, reduced skeletal muscle PGC-1α mRNA expression has been noted in some (Patti et al., 2003Patti M.E. Butte A.J. Crunkhorn S. Cusi K. Berria R. Kashyap S. Miyazaki Y. Kohane I. Costello M. Saccone R. et al.Coordinated reduction of genes of oxidative metabolism in humans with insulin resistance and diabetes: Potential role of PGC1 and NRF1.Proc. Natl. Acad. Sci. USA. 2003; 100: 8466-8471Crossref PubMed Scopus (1546) Google Scholar), but not all (Karlsson et al., 2006Karlsson H.K. Ahlsén M. Zierath J.R. Wallberg-Henriksson H. Koistinen H.A. Insulin signaling and glucose transport in skeletal muscle from first-degree relatives of type 2 diabetic patients.Diabetes. 2006; 55: 1283-1288Crossref PubMed Scopus (59) Google Scholar), nondiabetic family history-positive subjects, despite impairments in mitochondrial function (Morino et al., 2005Morino K. Petersen K.F. Dufour S. Befroy D. Frattini J. Shatzkes N. Neschen S. White M.F. Bilz S. Sono S. et al.Reduced mitochondrial density and increased IRS-1 serine phosphorylation in muscle of insulin-resistant offspring of type 2 diabetic parents.J. Clin. Invest. 2005; 115: 3587-3593Crossref PubMed Scopus (605) Google Scholar). Thus, additional factors may also contribute to the reduced mitochondrial content in history-positive nondiabetic subjects and T2DM patients. Indeed, changes in PGC-1α mRNA expression and mitochondrial function may be related to alterations in physical activity or nutritional status between the NGT and T2DM subjects, rather than diabetes per se. Whether methylation of the PGC-1α promoter is an early pathogenic event in the pathogenesis of insulin resistance in T2DM or a more generalized consequence causally related to features of IGT and T2DM requires further evaluation. Lipid overload can impair skeletal muscle oxidative capacity and increase intramuscular triglyceride content, thereby providing a role for nutritional factors in the development of peripheral insulin resistance in T2DM (Borkman et al., 1993Borkman M. Storlien L.H. Pan D.A. Jenkins A.B. Chisholm D.J. Campbell L.V. The relation between insulin sensitivity and the fatty-acid composition of skeletal-muscle phospholipids.N. Engl. J. Med. 1993; 328: 238-244Crossref PubMed Scopus (757) Google Scholar, Dobbins et al., 2001Dobbins R.L. Szczepaniak L.S. Bentley B. Esser V. Myhill J. McGarry J.D. Prolonged inhibition of muscle carnitine palmitoyltransferase-1 promotes intramyocellular lipid accumulation and insulin resistance in rats.Diabetes. 2001; 50: 123-130Crossref PubMed Scopus (241) Google Scholar, Valtueña et al., 1997Valtueña S. Salas-Salvadó J. Lorda P.G. The respiratory quotient as a prognostic factor in weight-loss rebound.Int. J. Obes. Relat. Metab. Disord. 1997; 21: 811-817Crossref PubMed Scopus (55) Google Scholar). The hypermethylation of the PGC-1α promoter upon free fatty acid exposure is compatible with previous evidence of a close relationship between PGC-1α mRNA levels in cultured myotubes and circulating fatty acid levels of the donor and strongly implicates fatty acids in the epigenetic modification of PGC-1α mRNA expression (Staiger et al., 2006Staiger H. Stefan N. Machicao F. Fritsche A. Häring H.U. PPARGC1A mRNA levels of in vitro differentiated human skeletal muscle cells are negatively associated with the plasma oleate concentrations of the donors.Diabetologia. 2006; 49: 212-214Crossref PubMed Scopus (20) Google Scholar). We also observed PGC-1α promoter hypermethylation upon TNF-α exposure. Excessive levels" @default.
• W1985280131 created "2016-06-24" @default.
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• W1985280131 date "2009-09-01" @default.
• W1985280131 modified "2023-10-13" @default.
• W1985280131 title "Non-CpG Methylation of the PGC-1α Promoter through DNMT3B Controls Mitochondrial Density" @default.
• W1985280131 cites W1534122645 @default.
• W1985280131 cites W1964876127 @default.
• W1985280131 cites W1965722916 @default.
• W1985280131 cites W1971082641 @default.
• W1985280131 cites W1989038174 @default.
• W1985280131 cites W2001986437 @default.
• W1985280131 cites W2003188067 @default.
• W1985280131 cites W2003363961 @default.
• W1985280131 cites W2023832867 @default.
• W1985280131 cites W2036227669 @default.
• W1985280131 cites W2044616072 @default.
• W1985280131 cites W2046069528 @default.
• W1985280131 cites W2047806321 @default.
• W1985280131 cites W2049481764 @default.
• W1985280131 cites W2053710327 @default.
• W1985280131 cites W2053901332 @default.
• W1985280131 cites W2064838548 @default.
• W1985280131 cites W2073157961 @default.
• W1985280131 cites W2077687426 @default.
• W1985280131 cites W2092603991 @default.
• W1985280131 cites W2096534598 @default.
• W1985280131 cites W2099744924 @default.
• W1985280131 cites W2101259235 @default.
• W1985280131 cites W2114416343 @default.
• W1985280131 cites W2119493125 @default.
• W1985280131 cites W2122683221 @default.
• W1985280131 cites W2123106337 @default.
• W1985280131 cites W2130189740 @default.
• W1985280131 cites W2134868253 @default.
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