Mitogen-activated protein kinase kinase inhibitor PD98059 blocks the trans-activation but not the stabilization or DNA binding ability of hypoxia-inducible factor-1alpha.
Under low oxygen tension, cells increase the transcription of specific genes that are involved in angiogenesis, erythropoiesis, and glycolysis. Hypoxia-induced gene expression primarily depends on the stabilization of the alpha-subunit of hypoxia-inducible factor-1 (HIF-1alpha), which acts as a heterodimeric trans-activator. Our results indicate that stabilization of HIF-1alpha protein by treatment of proteasome inhibitors, is not sufficient for hypoxia-induced gene activation, and an additional hypoxia-dependent modification is necessary for gene expression by HIF-1alpha. Here, we demonstrate that mitogen-activated protein kinase kinase-1 (MEK-1) inhibitor PD98059 does not change either the stabilization or DNA binding ability of HIF-1alpha but it inhibits the trans-activation ability of HIF-1alpha, thereby it reduces the hypoxia-induced transcription of both an endogenous target gene and a hypoxia-responsive reporter gene. We found that hypoxia induced p42/p44 mitogen-activated protein kinases (MAPKs) that are target protein kinases of MEK-1, and that expression of dominant-negative p42 and p44 MAPK mutants reduced HIF-1-dependent transcription of the hypoxia-responsive reporter gene. Our results are the first to identify that hypoxia-induced trans-activation ability of HIF-1alpha is regulated by different mechanisms than its stabilization and DNA binding, and that these processes can be experimentally dissociated. MEK-1/p42/p44 MAPK regulates the trans-activation, but not the stabilization or DNA binding ability, of HIF-1alpha.
Hur
E
E
Department of Life Science, University of Seoul, Seoul, Korea.
Chang
K Y
KY
Lee
E
E
Lee
S K
SK
Park
H
H
D015687:Cell Hypoxia / Q000502:physiology; D003546:Cysteine Endopeptidases; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D048369:MAP Kinase Kinase 1; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014157:Transcription Factors; D015533:Transcriptional Activation / Q000187:drug effects*; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; C497442:HIF1A protein, human; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009097:Multienzyme Complexes; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one