HIF3A

HIF3A, also known as Hypoxia-inducible factor 3, alpha subunit, is a gene that encodes a protein involved in the body's response to low oxygen conditions. It is a member of the PAS (Per-Arnt-Sim) domain protein family. HIF proteins are transcription factors that play a crucial role in cellular adaptation to hypoxia.

The protein encoded by HIF3A is typically degraded under normal oxygen levels. However, when oxygen levels decrease, the HIF3A protein becomes stabilized and can translocate to the nucleus. There, it can interact with other proteins to regulate the expression of genes involved in various physiological processes. These processes include angiogenesis (the formation of new blood vessels), erythropoiesis (the production of red blood cells), and cellular metabolism.

While HIF1A and HIF2A are well-studied and known to activate a broad range of hypoxia-inducible genes, HIF3A has been observed to have a more complex and sometimes inhibitory role. It can form heterodimers with ARNT (aryl hydrocarbon receptor nuclear translocator) and bind to hypoxia-response elements (HREs) in the promoter regions of target genes. However, the transcriptional activity of the HIF3A-ARNT complex can vary depending on the cellular context and the specific gene being regulated. Research suggests that HIF3A may act as a repressor of certain HIF-target genes or have distinct downstream effects compared to other HIF subunits. Its precise physiological functions are still an active area of investigation.