Cystathione beta-synthase regulates HIF-1 alpha stability through persulfidation of PHD2

The stringent expression of the hypoxia inducible factor-1 alpha (HIF-1 alpha) is critical to a variety of pathophysiological conditions. We reveal that, in normoxia, enzymatic action of cystathionine beta-synthase (CBS) produces H2S, which persulfidates prolyl hydroxylase 2 (PHD2) at residues Cys(21) and Cys(33) (zinc finger motif), augmenting prolyl hydroxylase activity. Depleting endogenous H2S either by hypoxia or by inhibiting CBS via chemical or genetic means reduces persulfidation of PHD2 and inhibits activity, preventing hydroxylation of HIF-1 alpha, resulting in stabilization. Our in vitro findings are further supported by the depletion of CBS in the zebrafish model that exhibits axis defects and abnormal intersegmental vessels. Exogenous H2S supplementation rescues both in vitro and in vivo phenotypes. We have identified the persulfidated residues and defined their functional significance in regulating the activity of PHD2 via point mutations. Thus, the CBS/H2S/PHD2 axis may provide therapeutic opportunities for pathologies associated with HIF-1 alpha dysregulation in chronic diseases.