HIF-1 alpha

Contains two independent C-terminal transactivation domains, NTAD and CTAD, which function synergistically. Their transcriptional activity is repressed by an intervening inhibitory domain (ID).

The protein expressed by the gene HIF1A functions as a master transcriptional regulator of the adaptive response to hypoxia, activating the transcription of over 40 genes under hypoxic conditions, including erythropoietin, glucose transporters, glycolytic enzymes, vascular endothelial growth factor, HILPDA, and others. These genes' protein products enhance oxygen delivery or facilitate metabolic adaptation to hypoxia. HIF1A is crucial for embryonic vascularization, tumor angiogenesis, and ischemic disease pathophysiology. Its activation requires transcriptional coactivators like CREBBP and EP300, with activity enhanced by interactions with NCOA1 and/or NCOA2. Interaction with redox regulatory protein APEX1 activates CTAD and enhances activation by NCOA1 and CREBBP. Additionally, HIF1A is involved in axonal distribution and mitochondrial transport in neurons during hypoxia. In the context of microbial infection, specifically human coronavirus SARS-CoV-2, HIF1A is necessary for glycolysis induction in monocytes, leading to a proinflammatory state, inducing expression of ACE2, cytokines, and promoting virus replication and monocyte inflammatory response. This supplementary information is collated from multiple sources and compiled automatically.

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 (PubMed:20699359, PubMed:20889502). Phosphorylation by GSK3-beta and PLK3 promote degradation by the proteasome (By similarity).

Sumoylated; with SUMO1 under hypoxia (PubMed:15465032, PubMed:15776016, PubMed:17610843). Sumoylation is enhanced through interaction with RWDD3 (PubMed:17956732). Both sumoylation and desumoylation seem to be involved in the regulation of its stability during hypoxia (PubMed:15465032, PubMed:15776016, PubMed:17610843). 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 (PubMed:15465032, PubMed:15776016, PubMed:17610843). Desumoylation by SENP1 increases its stability amd transcriptional activity (By similarity). There is a disaccord between various publications on the effect of sumoylation and desumoylation on its stability and transcriptional activity (Probable).

Acetylation of Lys-532 by ARD1 increases interaction with VHL and stimulates subsequent proteasomal degradation (PubMed:12464182). Deacetylation of Lys-709 by SIRT2 increases its interaction with and hydroxylation by EGLN1 thereby inactivating HIF1A activity by inducing its proteasomal degradation (PubMed:24681946).

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 E3 ligase VHL (PubMed:25615526). Deubiquitinated by UCHL1 (PubMed:25615526).

In normoxia, is hydroxylated on Pro-402 and Pro-564 in the oxygen-dependent degradation domain (ODD) by EGLN1/PHD2 and EGLN2/PHD1 (PubMed:11292861, PubMed:11566883, PubMed:12351678, PubMed:15776016, PubMed:25974097). EGLN3/PHD3 has also been shown to hydroxylate Pro-564 (PubMed:11292861, PubMed:11566883, PubMed:12351678, PubMed:15776016, PubMed:25974097). The hydroxylated prolines promote interaction with VHL, initiating rapid ubiquitination and subsequent proteasomal degradation (PubMed:11292861, PubMed:11566883, PubMed:12351678, PubMed:15776016, PubMed:25974097). Deubiquitinated by USP20 (PubMed:11292861, PubMed:11566883, PubMed:12351678, PubMed:15776016, PubMed:25974097). Under hypoxia, proline hydroxylation is impaired and ubiquitination is attenuated, resulting in stabilization (PubMed:11292861, PubMed:11566883, PubMed:12351678, PubMed:15776016, PubMed:25974097). In normoxia, is hydroxylated on Asn-803 by HIF1AN, thus abrogating interaction with CREBBP and EP300 and preventing transcriptional activation (PubMed:12080085). This hydroxylation is inhibited by the Cu/Zn-chelator, Clioquinol (PubMed:12080085). Repressed by iron ion, via Fe(2+) prolyl hydroxylase (PHD) enzymes-mediated hydroxylation and subsequent proteasomal degradation (PubMed:28296633).

The iron and 2-oxoglutarate dependent 3-hydroxylation of asparagine is (S) stereospecific within HIF CTAD domains.

(Microbial infection) Glycosylated at Arg-18 by enteropathogenic E.coli protein NleB1: arginine GlcNAcylation enhances transcription factor activity and impairs glucose metabolism.

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.

• Cytoplasm
• Nucleus
• Nucleus speckle
• Colocalizes with HIF3A in the nucleus and speckles (By similarity). Cytoplasmic in normoxia, nuclear translocation in response to hypoxia (PubMed:9822602).

BHLHE78, MOP1, PASD8, HIF1A, Hypoxia-inducible factor 1-alpha, HIF-1-alpha, HIF1-alpha, ARNT-interacting protein, Basic-helix-loop-helix-PAS protein MOP1, Class E basic helix-loop-helix protein 78, Member of PAS protein 1, PAS domain-containing protein 8, bHLHe78

• entrezGene:3091
• omim:603348
• swissprot:Q16665

Proteins

Epigenetics

• Immunology & Infectious Disease
• Oncology

92670Da