title: Activation of SIRT1 by resveratrol represses transcription of the gene for the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) by deacetylating hepatic nuclear factor 4alpha.
abstract: The SIRT1 activators isonicotinamide (IsoNAM), resveratrol, fisetin, and butein repressed transcription of the gene for the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) (PEPCK-C). An evolutionarily conserved binding site for hepatic nuclear factor (HNF) 4alpha (-272/-252) was identified, which was required for transcriptional repression of the PEPCK-C gene promoter caused by these compounds. This site contains an overlapping AP-1 binding site and is adjacent to the C/EBP binding element (-248/-234); the latter is necessary for hepatic transcription of PEPCK-C. AP-1 competed with HNF4alpha for binding to this site and also decreased HNF4alpha stimulation of transcription from the PEPCK-C gene promoter. Chromatin immunoprecipitation experiments demonstrated that HNF4alpha and AP-1, but not C/EBPbeta, reciprocally bound to this site prior to and after treating HepG2 cells with IsoNAM. IsoNAM treatment resulted in deacetylation of HNF4alpha, which decreased its binding affinity to the PEPCK-C gene promoter. In HNF4alpha-null Chinese hamster ovary cells, IsoNAM and resveratrol failed to repress transcription from the PEPCK-C gene promoter; overexpression of HNF4alpha in Chinese hamster ovary cells re-established transcriptional inhibition. Exogenous SIRT1 expression repressed transcription, whereas knockdown of SIRT1 by RNA interference reversed this effect. IsoNAM decreased the level of mRNA for PEPCK-C but had no effect on mRNA for glucose-6-phosphatase in AML12 mouse hepatocytes. We conclude that SIRT1 activation inhibited transcription of the gene for PEPCK-C in part by deacetylation of HNF4alpha. However, SIRT1 deacetylation of other key regulatory proteins that control PEPCK-C gene transcription also likely contributed to the inhibitory effect.
authors: Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4935, USA.
authors: Jianqi
authors: J
authors: Yang
authors: Xiaoying
authors: X
authors: Kong
authors: Maria Emilia S
authors: ME
authors: Martins-Santos
authors: Gabriela
authors: G
authors: Aleman
authors: Ernestine
authors: E
authors: Chaco
authors: George E
authors: GE
authors: Liu
authors: Shwu-Yuan
authors: SY
authors: Wu
authors: David
authors: D
authors: Samols
authors: Parvin
authors: P
authors: Hakimi
authors: Cheng-Ming
authors: CM
authors: Chiang
authors: Richard W
authors: RW
authors: Hanson
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology*; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009536:Niacinamide / Q000494:pharmacology; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D000077185:Resveratrol; D037761:Sirtuins / Q000378:metabolism*; D013267:Stilbenes / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
chemical_list: D051557:Hepatocyte Nuclear Factor 4; D013267:Stilbenes; D018808:Transcription Factor AP-1; D009536:Niacinamide; C027681:isonicotinamide; D004247:DNA; D037761:Sirtuins; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D000077185:Resveratrol