title: Transcriptional regulation of ferritin and antioxidant genes by HIPK2 under genotoxic stress.
abstract: ATF1 (activating transcription factor 1), a stimulus-induced CREB family transcription factor, plays important roles in cell survival and proliferation. Phosphorylation of ATF1 at Ser63 by PKA (cAMP-dependent protein kinase) and related kinases was the only known post-translational regulatory mechanism of ATF1. Here, we found that HIPK2 (homeodomain-interacting protein kinase 2), a DNA-damage-responsive nuclear kinase, is a new ATF1 kinase that phosphorylates Ser198 but not Ser63. ATF1 phosphorylation by HIPK2 activated ATF1 transcription function in the GAL4-reporter system. ATF1 is a transcriptional repressor of ferritin H, the major intracellular iron storage gene, through an ARE (antioxidant-responsive element). HIPK2 overrode the ATF1-mediated ARE repression in a kinase-activity-dependent manner in HepG2 cells. Furthermore, DNA-damage-inducing agents doxorubicin, etoposide and sodium arsenite induced ferritin H mRNA expression in HIPK2(+/+) MEF cells, whereas it was significantly impaired in HIPK2(-/-) MEF cells. Induction of other ARE-regulated detoxification genes such as NQO1 (NADPH quinone oxidoreductase 1), GST (glutathione S-transferase) and HO1 (heme oxygenase 1) by genotoxic stress was also decreased in HIPK2-deficient cells. Taken together, these results suggest that HIPK2 is a new ATF1 kinase involved in the regulation of ferritin H and other antioxidant detoxification genes in genotoxic stress conditions.
authors.affiliation: Department of Environmental and Molecular Toxicology, North Carolina State University, Campus Box 7633, Raleigh, NC 27695, USA.
authors.forename: Kiros
authors.initials: K
authors.lastname: Hailemariam
authors.forename: Kenta
authors.initials: K
authors.lastname: Iwasaki
authors.forename: Bo-Wen
authors.initials: BW
authors.lastname: Huang
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tsuji
mesh_terms: D051697:Activating Transcription Factor 1 / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D048708:Cell Growth Processes / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D004249:DNA Damage; D005293:Ferritins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D051697:Activating Transcription Factor 1; D002352:Carrier Proteins; D014157:Transcription Factors; D005293:Ferritins; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases