title: Identification of functional hypoxia response elements in the promoter region of the DEC1 and DEC2 genes.
abstract: Adaptation to hypoxia is a crucial process both physiologically (i.e. in chondrocytes) and pathologically (i.e. in tumor cells). Previous studies have shown that DEC1, a basic helix-loop-helix transcription factor, is induced by hypoxia in glioma cells (Ivanova, A. V., Ivanov, S. V., Danilkovitch-Miagkova, A., and Lerman, M. I. (2001) J. Biol. Chem. 276, 15306-15315). In the present study, we found that hypoxia or CoCl(2) enhanced the mRNA expression of DEC2, as well as DEC1, within 24 h in chondrogenic ATDC5, 293T, and HeLa cells. In luciferase assays, the regions between -524 and -401 in the DEC1 promoter, and between -863 and -258 in the DEC2 promoter, were responsible for the hypoxia- or hypoxia-inducible factor-1alpha (HIF-1alpha)-induced transcription. In these regions, we identified functional hypoxia response elements (HREs) that bound to HIF-1alpha and HIF-1beta. In addition to an HIF-1 binding site consensus sequence, the DEC1 HRE had cAMP response element-like and CACAG sequences, which were also involved in the transcription activation in response to HIF-1alpha. Although the DEC2 HRE did not have a cAMP response element-like or CACAG sequence, it showed a higher affinity for HIF-1 than did the DEC1 HRE. Because DEC1 and DEC2 are directly inducible by HIF-1, these transcription factors may be crucial for the adaptation to hypoxia.
mesh_terms: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019902:Chondrocytes / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051792:Basic Helix-Loop-Helix Proteins; D003035:Cobalt; D003094:Collagen; D000242:Cyclic AMP; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008156:Luciferases; D012333:RNA, Messenger; D018336:Receptors, Aryl Hydrocarbon; D014157:Transcription Factors; C497396:ARNT protein, human; C107989:BHLHE40 protein, human; C422085:BHLHE41 protein, human; C497442:HIF1A protein, human; C018021:cobaltous chloride