title: Hypoxia-inducible factor (HIF-1)alpha: its protein stability and biological functions.
abstract: Hypoxia-inducible factor (HIF-1) is an oxygen-dependent transcriptional activator, which plays crucial roles in the angiogenesis of tumors and mammalian development. HIF-1 consists of a constitutively expressed HIF-1beta subunit and one of three subunits (HIF-1alpha, HIF-2alpha or HIF-3alpha). The stability and activity of HIF-1alpha are regulated by various post-translational modifications, hydroxylation, acetylation, and phosphorylation. Therefore, HIF-1alpha interacts with several protein factors including PHD, pVHL, ARD-1, and p300/CBP. Under normoxia, the HIF-1alpha subunit is rapidly degraded via the von Hippel-Lindau tumor suppressor gene product (pVHL)- mediated ubiquitin-proteasome pathway. The association of pVHL and HIF-1alpha under normoxic conditions is triggered by the hydroxylation of prolines and the acetylation of lysine within a polypeptide segment known as the oxygen-dependent degradation (ODD) domain. On the contrary, in the hypoxia condition, HIF-1alpha subunit becomes stable and interacts with coactivators such as p300/CBP to modulate its transcriptional activity. Eventually, HIF-1 acts as a master regulator of numerous hypoxia-inducible genes under hypoxic conditions. The target genes of HIF-1 are especially related to angiogenesis, cell proliferation/survival, and glucose/iron metabolism. Moreover, it was reported that the activation of HIF-1alpha is closely associated with a variety of tumors and oncogenic pathways. Hence, the blocking of HIF-1a itself or HIF-1alpha interacting proteins inhibit tumor growth. Based on these findings, HIF-1 can be a prime target for anticancer therapies. This review summarizes the molecular mechanism of HIF-1a stability, the biological functions of HIF-1 and its potential applications of cancer therapies.
authors.affiliation: Research Institute of Pharmaceutical Sciences and College of Pharmacy, Seoul National University Seoul 151-742, Korea.
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Lee
authors.forename: Seong-Hui
authors.initials: SH
authors.lastname: Bae
authors.forename: Joo-Won
authors.initials: JW
authors.lastname: Jeong
authors.forename: Se-Hee
authors.initials: SH
authors.lastname: Kim
authors.forename: Kyu-Won
authors.initials: KW
authors.lastname: Kim
mesh_terms: D017398:Alternative Splicing; D005786:Gene Expression Regulation; D015316:Genetic Therapy; D006133:Growth Substances / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D006133:Growth Substances; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020033:Protein Isoforms; D021122:Protein Subunits; D014157:Transcription Factors