Interaction between HIF-1α (ODD) and hARD1 does not induce acetylation and destabilization of HIF-1α

Hypoxia inducible factor-1α (HIF-1α) is a central component of the cellular responses to hypoxia. Hypoxic conditions result in stabilization of HIF-1α and formation of the transcriptionally active HIF-1 complex. It was suggested that mammalian ARD1 acetylates HIF-1α and thereby enhances HIF-1α ubiquitination and degradation. Furthermore, ARD1 was proposed to be downregulated in hypoxia thus facilitating the stabilization of HIF-1α. Here we demonstrate that the level of human ARD1 (hARD1) protein is not decreased in hypoxia. Moreover, hARD1 does not acetylate and destabilize HIF-1α. However, we find that hARD1 specifically binds HIF-1α, suggesting a putative, still unclear, connection between these proteins.