Nuclear respiratory factor-1 (NRF-1) regulated hypoxia-inducible factor-1α (HIF-1α) under hypoxia in HEK293T.

Hypoxia-inducible factor 1α (HIF-1α) is a master regulator of oxygen homeostasis. Under hypoxia, the active HIF1-α subunits are mainly regulated through increased protein stabilization. Little is known concerning HIF-1α transcriptional regulation. Nuclear respiratory factor 1 (NRF-1) is a DNA-binding transcription factor that regulates mitochondrial biogenesis. In this study, we showed that NRF-1was a repressor of HIF-1α. The cellular depletion of NRF-1 by siRNA targeting leads to increased HIF-1αtranscriptional activity. EMSA, ChIP and luciferase activity allowed the identification of two functional NRF-1 binding sites within HIF-1α promoter. This study therefore identifies NRF-1 as a novel regulator of HIF-1α.