Hypoxia actively represses transcription by inducing negative cofactor 2 (Dr1/DrAP1) and blocking preinitiation complex assembly.
Hypoxia is a growth inhibitory stress associated with multiple disease states. We find that hypoxic stress actively regulates transcription not only by activation of specific genes but also by selective repression. We reconstituted this bimodal response to hypoxia in vitro and determined a mechanism for hypoxia-mediated repression of transcription. Hypoxic cell extracts are competent for transcript elongation, but cannot assemble a functional preinitiation complex (PIC) at a subset of promoters. PIC assembly and RNA polymerase II C-terminal domain (CTD) phosphorylation were blocked by hypoxic induction and core promoter binding of negative cofactor 2 protein (NC2 alpha/beta, Dr1/DrAP1). Immunodepletion of NC2 beta/Dr1 protein complexes rescued hypoxic-repressed transcription without alteration of normoxic transcription. Physiological regulation of NC2 activity may represent an active means of conserving energy in response to hypoxic stress.
Denko
Nicholas
N
Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University Medical School, Stanford, California 94305-5152, USA.
Wernke-Dollries
Kara
K
Johnson
Amber Buescher
AB
Hammond
Ester
E
Chiang
Cheng-Ming
CM
Barton
Michelle Craig
MC
D006528:Carcinoma, Hepatocellular; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000502:physiology; D006801:Humans; D010442:Peptide Chain Initiation, Translational / Q000502:physiology*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D014407:Tumor Cells, Cultured
C099112:DRAP1 protein, human; D012097:Repressor Proteins; D012319:RNA Polymerase II