title: Down-regulation of histone H2B by DNA-dependent protein kinase in response to DNA damage through modulation of octamer transcription factor 1.
abstract: Cells respond to double-stranded DNA breaks (DSBs) by pausing cell cycle progression to allow the repair machinery to restore genomic integrity. DNA-dependent protein kinase (DNA-PK), comprising a large catalytic subunit (DNA-PK(cs)) and the Ku antigen regulatory subunit (Ku70/Ku80), is activated in response to DSBs and is required for DNA repair through the nonhomologous end-joining pathway. Here we provide evidence that DNA-PK participates in altering specific gene expression in response to DNA damage by modulating the stability and transcriptional regulatory potential of the essential transcription factor octamer transcription factor 1 (Oct-1). Histone H2B and U2 RNA, whose expression are highly dependent on Oct-1, were strongly decreased in response to ionizing radiation in a DNA-PK-dependent manner, and Oct-1-dependent reporter gene transcription was repressed. Furthermore, Oct-1 phosphorylation in response to ionizing radiation increased in a DNA-PK-dependent manner. Paradoxically, down-regulation of transactivation correlated with the rapid DNA-PK-dependent stabilization of Oct-1. Stabilization of Oct-1 was dependent on the NH(2)-terminal region of Oct-1, which contains a transcriptional activation domain and which was phosphorylated by DNA-PK in vitro. These results suggest a mechanism for the regulation of Oct-1 in response to DNA damage through specific phosphorylation within the NH(2)-terminal transcriptional regulatory domain.
authors: Department of Medicine, University of Ottawa, The Ottawa Health Research Institute, 725 Parkdale Avenue, Ottawa, Ontario K1Y 4E9, Canada. cschild-poulter@ohri.ca
authors: Caroline
authors: C
authors: Schild-Poulter
authors: Amy
authors: A
authors: Shih
authors: Nicholas C
authors: NC
authors: Yarymowich
authors: Robert J G
authors: RJ
authors: Haché
mesh_terms: D000818:Animals; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage / Q000502:physiology*; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D015536:Down-Regulation; D006367:HeLa Cells; D006657:Histones / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D051863:Host Cell Factor C1; D006801:Humans; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012342:RNA, Small Nuclear / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation
chemical_list: D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D006657:Histones; D051863:Host Cell Factor C1; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D012333:RNA, Messenger; D012342:RNA, Small Nuclear; D014157:Transcription Factors; C405484:U2 small nuclear RNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases