From Erythropoietin to Oxygen: Hypoxia-Inducible Factor Hydroxylases and the Hypoxia Signal Pathway

The regulation of blood red cell production by the hormone erythropoietin (Epo) provides a paradigm for control of gene expression by oxygen. Analysis of this pathway has revealed a widespread system of gene regulation based on a transcriptional complex termed hypoxia-inducible factor (HIF). Hydroxylation of specific prolyl and asparinyl residues in the alpha subunit of HIF by a series of non-haem iron-dependent dioxygenases has been defined as a novel mechanism of protein modification that transduces the oxygen-sensitive signal.