Expression of hypoxia-inducible factor 1: Mechanisms and consequences

Hypoxia-inducible factor 1 (HIF-1) is a basic-helix-loop-helix transcription factor that plays essential roles in mammalian development and physiology. HIF-1 is a heterodimer composed of HIF-1 alpha and HIF-1 beta subunits. The expression and activity of the HIF-1 alpha subunit are tightly regulated by cellular O-2 concentration. Under hypoxic conditions, HIF-1 activates the transcription of genes encoding erythropoietin, glucose transporters, glycolytic enzymes, vascular endothelial growth factor, and other genes whose protein products increase O-2 delivery or facilitate metabolic adaptation to hypoxia. HIF-1 is essential for embryonic vascularization and survival, neovascularization in ischemic myocardium, hypoxia-induced pulmonary vascular remodeling, and tumor vascularization. HIF-1 alpha is 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. Pharmacologic manipulation of HIF-1 levels may provide a novel therapeutic approach to diseases that represent the most common causes of mortality in Western society, including cancer, chronic lung disease, and myocardial ischemia. BIOCHEM PHARMACOL 59;1:47-53, 2000. (C) 1999 Elsevier Science Inc.