HIF3A

The protein encoded by this gene is the alpha-3 subunit of one of several alpha/beta-subunit heterodimeric transcription factors that regulate many adaptive responses to low oxygen tension (hypoxia). The alpha-3 subunit lacks the transactivation domain found in factors containing either the alpha-1 or alpha-2 subunits. It is thought that factors containing the alpha-3 subunit are negative regulators of hypoxia-inducible gene expression. Multiple alternatively spliced transcript variants have been found for this gene.

Full Name

HIF3A

Function

Acts as a transcriptional regulator in adaptive response to low oxygen tension. Acts as a regulator of hypoxia-inducible gene expression (PubMed:11573933, PubMed:16126907, PubMed:19694616, PubMed:20416395, PubMed:21069422).

Functions as an inhibitor of angiogenesis in hypoxic cells of the cornea. Plays a role in the development of the cardiorespiratory system. May also be involved in apoptosis (By similarity).

Isoform 2:
Attenuates the ability of transcription factor HIF1A to bind to hypoxia-responsive elements (HRE) located within the enhancer/promoter of hypoxia-inducible target genes and hence inhibits HRE-driven transcriptional activation. Also inhibits hypoxia-inducible ARNT-mediated gene expression.

Isoform 3:
Attenuates the ability of transcription factor HIF1A to bind to hypoxia-responsive elements (HRE) located within the enhancer/promoter of hypoxia-inducible target genes and hence inhibits HRE-driven transcriptional activation.

Isoform 4:
Attenuates the ability of transcription factor HIF1A and EPAS1/HIF2A to bind to hypoxia-responsive elements (HRE) located within the enhancer/promoter of hypoxia-inducible target genes and hence inhibits HRE-driven transcriptional activation (PubMed:16126907, PubMed:17998805, PubMed:19694616, PubMed:20416395).

May act as a tumor suppressor and inhibits malignant cell transformation (PubMed:17998805).

Isoform 5:
Attenuates the ability of transcription factor HIF1A to bind to hypoxia-responsive elements (HRE) located within the enhancer/promoter of hypoxia-inducible target genes and hence inhibits HRE-driven transcriptional activation.

Biological Process

Angiogenesis Source: UniProtKB-KW
Apoptotic process Source: UniProtKB-KW
Regulation of transcription by RNA polymerase II Source: UniProtKB
Response to hypoxia Source: Ensembl
Transcription by RNA polymerase II Source: Ensembl

Cellular Location

Nucleus; Nucleus speckle; Cytoplasm; Mitochondrion. In the nuclei of all periportal and perivenous hepatocytes. In the distal perivenous zone, detected in the cytoplasm of the hepatocytes. Shuttles between the nucleus and the cytoplasm in a CRM1-dependent manner. Colocalizes with BAD in the cytoplasm. Colocalizes with EPAS1 and HIF1A in the nucleus and speckles (By similarity). Localized in the cytoplasm and nuclei under normoxia, but increased in the nucleus under hypoxic conditions (PubMed:19694616). Colocalized with HIF1A in kidney tumors (PubMed:19694616).

PTM

In normoxia, hydroxylated on Pro-492 in the oxygen-dependent degradation domain (ODD) by prolyl hydroxylase(s) (PHD). The hydroxylated proline promotes interaction with VHL, initiating rapid ubiquitination and subsequent proteasomal degradation.
Ubiquitinated; ubiquitination occurs in a VHL- and oxygen-dependent pathway and subsequently targeted for proteasomal degradation.