title: Hypoxia-inducible factor-1alpha obstructs a Wnt signaling pathway by inhibiting the hARD1-mediated activation of beta-catenin.
abstract: Although a splice variant of mouse mARD1s was found to acetylate and destabilize hypoxia-inducible factor-1alpha (HIF-1alpha), human hARD1 has no such activities. Nonetheless, hARD1 has been reported to bind directly with HIF-1alpha. Here, we addressed the functional significance of the hARD1-HIF-1alpha interaction. Because hARD1 acetylates and activates beta-catenin, we examined whether HIF-1alpha regulates the hARD1-mediated activation of Wnt signaling. It was found that HIF-1alpha binds hARD1 through the oxygen-dependent degradation domain and, in so doing, dissociates hARD1 from beta-catenin, which prevents beta-catenin acetylation. In LiCl-stimulated HEK293 or cancer cell lines with active Wnt signaling, beta-catenin acetylation and activity were suppressed in hypoxia, and these suppressions were mediated by HIF-1alpha. Moreover, HIF-1alpha disruption of hARD1/beta-catenin repressed TCF4 activity, resulting in c-Myc suppression and p21(cip1) induction. In addition, we confirmed that the HIF-1alpha NH(2) terminal inactivates TCF4 by directly binding beta-catenin. In conclusion, HIF-1alpha was found to inactivate the Wnt signaling by binding to hARD1 or beta-catenin, which may contribute to the hypoxia-induced growth arrest of tumor cells.
authors.affiliation: Department of Pharmacology, Seoul National University College of Medicine, Chongno-gu, Seoul, Korea.
authors.forename: Ji-Hong
authors.initials: JH
authors.lastname: Lim
authors.forename: Yang-Sook
authors.initials: YS
authors.lastname: Chun
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Park
mesh_terms: D000107:Acetylation; D000123:Acetyltransferases / Q000378:metabolism / Q000502:physiology*; D015687:Cell Hypoxia / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism / Q000502:physiology*; D008954:Models, Biological; D063209:N-Terminal Acetyltransferase A; D063213:N-Terminal Acetyltransferase E; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051820:TCF Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D058118:Transcription Factor 7-Like 2 Protein; D051153:Wnt Proteins / Q000037:antagonists & inhibitors*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; D051820:TCF Transcription Factors; C544894:TCF7L2 protein, human; C544895:Tcf7l2 protein, mouse; D058118:Transcription Factor 7-Like 2 Protein; D051153:Wnt Proteins; D051176:beta Catenin; D000123:Acetyltransferases; D063209:N-Terminal Acetyltransferase A; C504824:NAA10 protein, human; D063213:N-Terminal Acetyltransferase E; D016283:Proto-Oncogene Proteins p21(ras)