UNIPROT #

Q16665

PROTEIN NAME

HIF1 alpha

SYNONYMS

ARNT interacting protein antibody; ARNT-interacting protein antibody; Basic helix loop helix PAS protein MOP1 antibody; Basic-helix-loop-helix-PAS protein MOP1 antibody; bHLHe78 antibody; Class E basic helix-loop-helix protein 78 antibody; HIF 1A antibody; HIF 1alpha antibody; HIF-1-alpha antibody; HIF1 A antibody; HIF1 Alpha antibody; HIF1 antibody; HIF1-alpha antibody; HIF1A antibody; HIF1A_HUMAN antibody; Hypoxia inducible factor 1 alpha antibody; Hypoxia inducible factor 1 alpha isoform I.3 antibody; Hypoxia inducible factor 1 alpha subunit antibody; Hypoxia inducible factor 1 alpha subunit basic helix loop helix transcription factor antibody; Hypoxia inducible factor 1, alpha subunit (basic helix loop helix transcription factor) antibody; Hypoxia inducible factor1alpha antibody; Hypoxia-inducible factor 1-alpha antibody; Member of PAS protein 1 antibody; Member of PAS superfamily 1 antibody; Member of the PAS Superfamily 1 antibody; MOP 1 antibody; MOP1 antibody; PAS domain-containing protein 8 antibody; PASD 8 antibody; PASD8 antibody

TISSUE SPECIFICITY

Expressed in most tissues with highest levels in kidney and heart. Overexpressed in the majority of common human cancers and their metastases, due to the presence of intratumoral hypoxia and as a result of mutations in genes encoding oncoproteins and tumor suppressors. A higher level expression seen in pituitary tumors as compared to the pituitary gland.

POST-TRANSLATIONAL MODIFICATION

S-nitrosylation of Cys-800 may be responsible for increased recruitment of p300 coactivator necessary for transcriptional activity of HIF-1 complex.; Requires phosphorylation for DNA-binding. Phosphorylation at Ser-247 by CSNK1D/CK1 represses kinase activity and impairs ARNT binding. Phosphorylation by GSK3-beta and PLK3 promote degradation by the proteasome.; Sumoylated; with SUMO1 under hypoxia. Sumoylation is enhanced through interaction with RWDD3. Both sumoylation and desumoylation seem to be involved in the regulation of its stability during hypoxia. Sumoylation can promote either its stabilization or its VHL-dependent degradation by promoting hydroxyproline-independent HIF1A-VHL complex binding, thus leading to HIF1A ubiquitination and proteasomal degradation. Desumoylation by SENP1 increases its stability amd transcriptional activity. There is a disaccord between various publications on the effect of sumoylation and desumoylation on its stability and transcriptional activity.; Acetylation of Lys-532 by ARD1 increases interaction with VHL and stimulates subsequent proteasomal degradation. Deacetylation of Lys-709 by SIRT2 increases its interaction with and hydroxylation by EGLN1 thereby inactivating HIF1A activity by inducing its proteasomal degradation.; Polyubiquitinated; in normoxia, following hydroxylation and interaction with VHL. Lys-532 appears to be the principal site of ubiquitination. Clioquinol, the Cu/Zn-chelator, inhibits ubiquitination through preventing hydroxylation at Asn-803. Ubiquitinated by a CUL2-based E3 ligase.; In normoxia, is hydroxylated on Pro-402 and Pro-564 in the oxygen-dependent degradation domain (ODD) by EGLN1/PHD2 and EGLN2/PHD1. EGLN3/PHD3 has also been shown to hydroxylate Pro-564. The hydroxylated prolines promote interaction with VHL, initiating rapid ubiquitination and subsequent proteasomal degradation. Deubiquitinated by USP20. Under hypoxia, proline hydroxylation is impaired and ubiquitination is attenuated, resulting in stabilization. In normoxia, is hydroxylated on Asn-803 by HIF1AN, thus abrogating interaction with CREBBP and EP300 and preventing transcriptional activation. This hydroxylation is inhibited by the Cu/Zn-chelator, Clioquinol. Repressed by iron ion, via Fe(2+) prolyl hydroxylase (PHD) enzymes-mediated hydroxylation and subsequent proteasomal degradation.; The iron and 2-oxoglutarate dependent 3-hydroxylation of asparagine is (S) stereospecific within HIF CTAD domains.

SUBCELLULAR LOCATION

Cytoplasm. Nucleus.

FUNCTION

Cell growth and viability is compromised by oxygen deprivation (hypoxia). Hypoxia-inducible factors, including HIF-1α, HIF-1β (also designated Arnt 1), EPAS-1 (also designated HIF-2α) and HIF-3α, induce glycolysis, erythropoiesis and angiogenesis in order to restore oxygen homeostasis. Hypoxia-inducible factors are members of the Per-Arnt-Sim (PAS) domain transcription factor family. In response to hypoxia, HIF-1α is upregulated and forms a heterodimer with Arnt 1 to form the HIF-1 complex. The HIF-1 complex recognizes and binds to the hypoxia responsive element (HRE) of hypoxia-inducible genes, thereby activating transcription. Hypoxia-inducible expression of some genes such as Glut-1, p53, p21 or Bcl-2, is HIF-1α dependent, whereas expression of others, such as p27, GADD 153 or HO-1, is HIF-1α independent. EPAS-1 and HIF-3α have also been shown to form heterodimeric complexes with Arnt 1 in response to hypoxia.