Abstract

The binding of endothelin-1 (ET-1) to endothelin type A receptor (ETAR) performs a critical action in pulmonary arterial smooth muscle cell (PASMC) proliferation leading to pulmonary vascular structural remodeling. More evidence showed that cystathionine γ-lyase (CSE)-catalyzed endogenous hydrogen sulfide (H2S) was involved in the pathogenesis of cardiovascular diseases. In this study, we aimed to explore the effect of endogenous H2S/CSE pathway on the ET-1/ETAR binding and its underlying mechanisms in the cellular and animal models of PASMC proliferation. Both live cell imaging and ligand-receptor assays revealed that H2S donor, NaHS, inhibited the binding of ET-1/ETAR in human PASMCs (HPASMCs) and HEK-293A cells, along with an inhibition of ET-1-activated HPASMC proliferation. While, an upregulated Ki-67 expression by the pulmonary arteries, a marked pulmonary artery structural remodeling, and an increased pulmonary artery pressure were observed in CSE knockout (CSE-KO) mice with a deficient H2S/CSE pathway compared with those in the wild type (WT) mice. Meanwhile, NaHS rescued the enhanced binding of ET-1 with ETAR and cell proliferation in the CSE-knockdowned HPASMCs. Moreover, the ETAR antagonist BQ123 blocked the enhanced proliferation of CSE-knockdowned HPASMCs. Mechanistically, ETAR persulfidation was reduced in the lung tissues of CSE-KO mice compared to that in WT mice, which could be reversed by NaHS treatment. Similarly, NaHS persulfidated ETAR in HPASMCs and HEK-293A cells. Whereas a thiol reductant dithiothreitol (DTT) reversed the H2S-induced ETAR persulfidation and further blocked the H2S-inhibited binding of ET-1/ETAR and HPASMC proliferation. Furthermore, the mutation of ETAR at cysteine (Cys) 69 abolished the persulfidation of ETAR by H2S, and subsequently blocked the H2S-suppressed ET-1/ETAR binding and HPASMC proliferation. Endogenous H2S persulfidated ETAR at Cys69 to inhibit the binding of ET-1 to ETAR, subsequently suppressed PASMC proliferation, and antagonized pulmonary vascular structural remodeling.