title: Sirtuin 3, a new target of PGC-1alpha, plays an important role in the suppression of ROS and mitochondrial biogenesis.
abstract: BACKGROUND
  Sirtuin 3 (SIRT3) is one of the seven mammalian sirtuins, which are homologs of the yeast Sir2 gene. SIRT3 is the only sirtuin with a reported association with the human life span. Peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) plays important roles in adaptive thermogenesis, gluconeogenesis, mitochondrial biogenesis and respiration. PGC-1alpha induces several key reactive oxygen species (ROS)-detoxifying enzymes, but the molecular mechanism underlying this is not well understood.
  
  
  RESULTS
  Here we show that PGC-1alpha strongly stimulated mouse Sirt3 gene expression in muscle cells and hepatocytes. Knockdown of PGC-1alpha led to decreased Sirt3 gene expression. PGC-1alpha activated the mouse SIRT3 promoter, which was mediated by an estrogen-related receptor (ERR) binding element (ERRE) (-407/-399) mapped to the promoter region. Chromatin immunoprecipitation and electrophoretic mobility shift assays confirmed that ERRalpha bound to the identified ERRE and PGC-1alpha co-localized with ERRalpha in the mSirt3 promoter. Knockdown of ERRalpha reduced the induction of Sirt3 by PGC-1alpha in C(2)C(12) myotubes. Furthermore, Sirt3 was essential for PGC-1alpha-dependent induction of ROS-detoxifying enzymes and several components of the respiratory chain, including glutathione peroxidase-1, superoxide dismutase 2, ATP synthase 5c, and cytochrome c. Overexpression of SIRT3 or PGC-1alpha in C(2)C(12) myotubes decreased basal ROS level. In contrast, knockdown of mSIRT3 increased basal ROS level and blocked the inhibitory effect of PGC-1alpha on cellular ROS production. Finally, SIRT3 stimulated mitochondrial biogenesis, and SIRT3 knockdown decreased the stimulatory effect of PGC-1alpha on mitochondrial biogenesis in C(2)C(12) myotubes.
  
  
  CONCLUSIONS
  Our results indicate that Sirt3 functions as a downstream target gene of PGC-1alpha and mediates the PGC-1alpha effects on cellular ROS production and mitochondrial biogenesis. Thus, SIRT3 integrates cellular energy metabolism and ROS generation. The elucidation of the molecular mechanisms of SIRT3 regulation and its physiological functions may provide a novel target for treating ROS-related disease.
authors.affiliation: The National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Kong
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xue
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Liu
authors.forename: Huabing
authors.initials: H
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Fude
authors.initials: F
authors.lastname: Fang
authors.forename: Yongsheng
authors.initials: Y
authors.lastname: Chang
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D004272:DNA, Mitochondrial / Q000235:genetics; D024202:Electrophoretic Mobility Shift Assay; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D056945:Hep G2 Cells; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D056566:Sirtuin 3 / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial; D006360:Heat-Shock Proteins; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D017382:Reactive Oxygen Species; D015534:Trans-Activators; D014157:Transcription Factors; D056566:Sirtuin 3