NYMC Faculty Publications
L-Ascorbic Acid: A True Substrate for HIF Prolyl Hydroxylase?
DOI
10.1016/j.biochi.2017.12.011
Journal Title
Biochimie
First Page
46
Last Page
54
Document Type
Article
Publication Date
April 2018
Department
Cell Biology and Anatomy
Abstract
L-Ascorbate (L-Asc), but not D-isoascorbate (D-Asc) and N-acetylcysteine (NAC) suppress HIF1 ODD-luc reporter activation induced by various inhibitors of HIF prolyl hydroxylase (PHD). The efficiency of suppression by L-Asc was sensitive to the nature of HIF PHD inhibitor chosen for reporter activation. In particular, the inhibitors developed to compete with alpha-ketoglutarate (alphaKG), were less sensitive to suppression by the physiological range of L-Asc (40-100muM) than those having a strong iron chelation motif. Challenging those HIF activators in the reporter system with D-Asc demonstrated that the D-isomer, despite exhibiting the same reducing potency with respect to ferric iron, had almost no effect compared to L-Asc. Similarly, no effect on reporter activation was observed with cell-permeable reducing agent NAC up to 1mM. Docking of L-Asc and D-Asc acid into the HIF PHD2 crystal structure showed interference of Tyr310 with respect to D-Asc. This suggests that L-Asc is not merely a reducing agent preventing enzyme inactivation. Rather, the overall results identify L-Asc as a co-substrate of HIF PHD that may compete for the binding site of alphaKG in the enzyme active center. This conclusion is in agreement with the results obtained recently in cell-based systems for TET enzymes and jumonji histone demethylases, where L-Asc has been proposed to act as a co-substrate and not as a reducing agent preventing enzyme inactivation.
Recommended Citation
Osipyants, A., Poloznikov, A., Smirnova, N., Hushpulian, D., Khristichenko, A., Chubar, T., Zakhariants, A., Ahuja, M., Gaisina, I., Thomas, B., Brown, A., Gazaryan, I., & Tishkov, V. (2018). L-Ascorbic Acid: A True Substrate for HIF Prolyl Hydroxylase?. Biochimie, 147, 46-54. https://doi.org/10.1016/j.biochi.2017.12.011