title: Nuclear corepressor is required for inhibition of phosphoenolpyruvate carboxykinase expression by tumor necrosis factor-alpha.
abstract: Inhibition of phosphoenolpyruvate carboxykinase (PEPCK) by TNF-alpha contributes to the pathogenesis of hypoglycemia in endotoxin shock. In this study, the molecular mechanism underlying the inhibition was investigated in hepatoma cells (rat H4IIE and human HepG2). PEPCK expression was induced by cAMP, and the induction was reduced by TNF-alpha at protein and mRNA levels in H4IIE cells. The inhibition was observed in the PEPCK gene promoter in a PEPCK-luciferase reporter. Activation of nuclear factor kappaB (NF-kappaB) pathway was required for the transcriptional inhibition of PEPCK gene. Degradation of NF-kappaB inhibitor (IkappaB) and p65 nuclear translocation were involved in the inhibition. An interaction of histone deacetylase 3 (HDAC3) and silencing mediator for retinoic acid receptor and thyroid hormone receptor (SMRT) with the PEPCK gene promoter was induced by TNF-alpha and observed in a chromatin immunoprecipitation assay. The TNF-induced inhibition was blocked by HDAC inhibitor or HDAC3 knockdown. The blocking effect was also observed in knockdown of corepressor SMRT. Point mutation suggests that cAMP response element (CRE) is required for TNF-induced inhibition of the PEPCK gene promoter. Phosphorylation of cAMP response element-binding protein at Ser133 and expression of peroxisome proliferator-activated receptor-gamma coactivator 1alpha were not changed by TNF-alpha in H4IIE cells. The transcriptional activity of CRE-binding protein was inhibited by TNF-alpha in a CRE-luciferase reporter. The data suggests that the nuclear corepressor proteins of HDAC3 and SMRT mediate TNF inhibition of PEPCK transcription. The inhibition mechanism is related to activation of NF-kappaB and inhibition of CRE-binding protein activity by the corepressor. These data suggest a novel activity of nuclear corepressor in the regulation of PEPCK expression by TNF-alpha.
authors: Department of Endocrinology, The First-Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China.
authors: Jinhua
authors: J
authors: Yan
authors: Zhanguo
authors: Z
authors: Gao
authors: Gang
authors: G
authors: Yu
authors: Qing
authors: Q
authors: He
authors: Jianping
authors: J
authors: Weng
authors: Jianping
authors: J
authors: Ye
mesh_terms: D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006655:Histone Deacetylases / Q000378:metabolism; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D056971:Nuclear Receptor Co-Repressor 1; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000099186:Histone Deacetylase 3
chemical_list: D000242:Cyclic AMP; D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D006655:Histone Deacetylases; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D009687:Nuclear Proteins; D056971:Nuclear Receptor Co-Repressor 1; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D012333:RNA, Messenger; D012097:Repressor Proteins; D014409:Tumor Necrosis Factor-alpha; D000099186:Histone Deacetylase 3; C539127:NCOR1 protein, human; C000606204:NFKBIA protein, human; C539129:Ncor1 protein, rat; C000606206:Nfkbia protein, rat