title: Adaptive gene regulation of pyruvate dehydrogenase kinase isoenzyme 4 in hepatotoxic chemical-induced liver injury and its stimulatory potential for DNA repair and cell proliferation.
abstract: The processes involved in the adaptation of animals to environmental factors remain unclear. We examined the mechanisms underlying the adaptive potential of the mouse against hepatotoxic chemical-induced injury. Microarray analysis revealed that ethylbenzene, a hepatotoxic chemical, upregulated PDK4 (encoding pyruvate dehydrogenase kinase isoenzyme 4) in mouse livers and that the upregulation was enhanced by previous exposure to the chemical. Although PDK4 is an energy resource regulator induced by starvation, expression of other fasting-inducible genes was unaffected. PDK4 induced by chemical stress developed hepatic accumulation of sirtuin 1 by regulating pyruvate concentration and activated the Nbn and ATM, which are critical for DNA repair and checkpoint activation. PDK4 overexpression on carbon tetrachloride (CCl(4))-induced liver injury resulted in delayed necrotic tissue recovery with cell cycle arrest and decreased γH2AX foci and micronucleus formation. PDK4 silencing on CCl(4)-induced liver injury accelerated necrotic tissue recovery and increased γH2AX foci and micronucleus formation, indicating the essential role of PDK4 in DNA repair and checkpoint activation. PDK4 overexpression induced pancreas-specific transcription factor 1a (Ptf1a) upregulation and transcriptional activation of several pancreatic genes in the liver. Ptf1a overexpression by adenoviral gene delivery resulted in accelerated tissue recovery on CCl(4)-induced liver injury. Our data identified PDK4 as a novel pivotal factor in adaptation to chemical stress.
authors.affiliation: Environmental Science Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba, Japan. dateki@criepi.denken.or.jp
authors.forename: Minori
authors.initials: M
authors.lastname: Dateki
authors.forename: Megumi
authors.initials: M
authors.lastname: Kunitomo
authors.forename: Kento
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Yanai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakasono
authors.forename: Tadashi
authors.initials: T
authors.lastname: Negishi
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle; D049109:Cell Proliferation; D004260:DNA Repair / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D005812:Genes, Switch; D056945:Hep G2 Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000473:pathology*; D008107:Liver Diseases / Q000201:enzymology* / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010179:Pancreas / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011773:Pyruvates / Q000378:metabolism; D056564:Sirtuin 1 / Q000378:metabolism; D013312:Stress, Physiological; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D007527:Isoenzymes; C000631432:PDK4 protein, human; C000631439:Pdk4 protein, mouse; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D011773:Pyruvates; D014157:Transcription Factors; C062602:transcription factor PTF1; D017346:Protein Serine-Threonine Kinases; C470545:Sirt1 protein, mouse; D056564:Sirtuin 1