The regulation of hypoxic genes by calcium involves c-Jun/AP-1, which cooperates with hypoxia-inducible factor 1 in response to hypoxia.
Hypoxia causes the accumulation of the transcription factor hypoxia-inducible factor 1 (HIF-1), culminating in the expression of hypoxia-inducible genes such as those for vascular endothelial growth factor (VEGF) and NDRG-1/Cap43. Previously, we have demonstrated that intracellular calcium (Ca(2+)) is required for the expression of hypoxia-inducible genes. Here we found that, unlike with hypoxia or hypoxia-mimicking conditions, the elevation of intracellular Ca(2+) neither induced the HIF-1alpha protein nor stimulated HIF-1-dependent transcription. Furthermore, the elevation of intracellular Ca(2+) induced NDRG-1/Cap43 mRNA in HIF-1alpha-deficient cells. It also increased levels of c-Jun protein, causing its phosphorylation. The protein kinase inhibitor K252a abolished c-Jun induction and activator protein 1 (AP-1)-dependent reporter expression caused by Ca(2+) ionophore or hypoxia. K252a also significantly decreased hypoxia-induced VEGF and NDRG-1/Cap43 gene expression in both human and mouse cells. Using a set of deletion VEGF-Luc promoter constructs, we found that both HIF-1 and two AP-1 sites contribute to hypoxia-mediated induction of transcription. In contrast, only AP-1 sites contributed to Ca(2+)-mediated VEGF-Luc induction. A dominant-negative AP-1 prevented Ca(2+)-dependent transcription and partially impaired hypoxia-mediated transcription. In addition, dominant-negative AP-1 diminished the expression of the NDRG-1/Cap43 gene following hypoxia. We conclude that during hypoxia, an increase in intracellular Ca(2+) activates a HIF-1-independent signaling pathway that involves AP-1-dependent transcription. Cooperation between the HIF-1 and AP-1 pathways allows fine regulation of gene expression during hypoxia.
Salnikow
Konstantin
K
Department of Environmental Medicine, NIEHS and Kaplan Comprehensive Cancer Center, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA. salnikow@env.med.nyu.edu
Kluz
Thomas
T
Costa
Max
M
Piquemal
David
D
Demidenko
Zoya N
ZN
Xie
Keping
K
Blagosklonny
Mikhail V
MV
D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism; D015687:Cell Hypoxia / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005799:Genes, Dominant; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007424:Intracellular Fluid / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007476:Ionophores / Q000494:pharmacology; D008222:Lymphokines / Q000235:genetics; D051379:Mice; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099259:N-myc Downstream-Regulated Gene 1 Protein
D002118:Calcium; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D047908:Intracellular Signaling Peptides and Proteins; D007476:Ionophores; D008222:Lymphokines; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000099259:N-myc Downstream-Regulated Gene 1 Protein; C497442:HIF1A protein, human; C497443:Hif1a protein, mouse