Nitric oxide impairs normoxic degradation of HIF-1alpha by inhibition of prolyl hydroxylases.
Hypoxia inducible factor-1 (HIF-1) is the master regulator of metabolic adaptation to hypoxia. It is appreciated that HIF-1alpha accumulation is achieved under normoxic conditions by e.g., nitric oxide. We determined molecular mechanisms of HIF-1alpha accumulation under the impact of S-nitrosoglutathione (GSNO). In human embryonic kidney cells GSNO provoked nuclear accumulation of HIF-1alpha. This appeared unrelated to gene transcription and protein translation, thus pointing to inhibition of HIF-1alpha degradation. Indeed, GSNO as well as the hypoxia mimic CoCl2 decreased ubiquitination of HIF-1alpha and GSNO-induced HIF-1alpha failed to coimmunoprecipitate with pVHL (von Hippel Lindau protein). Considering that HIF-1alpha-pVHL interactions require prolyl hydroxylation of HIF-1alpha, we went on to demonstrate inhibition of HIF-1alpha prolyl hydroxylases (PHDs) by GSNO. In vitro HIF-1alpha-pVHL interactions revealed that GSNO dose-dependently inhibits PHD activity but not the interaction of a synthetic peptide resembling the hydroxylated oxygen-dependent degradation domain of HIF-1alpha with pVHL. We conclude that GSNO-attenuated prolyl hydroxylase activity accounts for HIF-1alpha accumulation under conditions of NO formation during normoxia and that PHD activity is subject to regulation by NO.
Metzen
Eric
E
Institute of Physiology, University of Luebeck, Germany.
Zhou
Jie
J
Jelkmann
Wolfgang
W
Fandrey
Joachim
J
Brüne
Bernhard
B
D015687:Cell Hypoxia; D002478:Cells, Cultured; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009569:Nitric Oxide / Q000502:physiology*; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D026422:S-Nitrosoglutathione / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D051794:Von Hippel-Lindau Tumor Suppressor Protein
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D011393:Procollagen-Proline Dioxygenase; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; C497446:VHL protein, human