Detecting Hypoxia-Inducible Factor Levels and Activity

The hypoxia-inducible transcription factors HIF-1 and HIF-2 regulate the response to hypoxia. Both proteins are dimers of an alpha subunit and a shared beta subunit. Under hypoxic conditions, the alpha subunits are stabilized, and the transactivation ability of the HIF-1 transcription factor is induced. Accordingly, assessment of HIF-1α protein levels and HIF transcriptional activity serve as an indirect indicator of hypoxia. In this series of protocols, I describe three methods to probe the HIF pathway.