Abstract

Mitophagy is a physiologic process of autophagic delivery of damaged or dysfunctional mitochondria to lysosomes. While this process maintains healthy mitochondrial population, excessive mitophagy leads to cellular dysfunction and death. Here, we tested the hypothesis that homocysteine generates mitochondrial reactive oxygen species and induces mitochondrial damage. Hydrogen sulfide (H2S) mitigates homocysteine‐toxicity against mitophagy. Human glomerular microvascular endothelial cells (hGMEnds) were exposed to different doses of Hcy (0–100 μM) for 48 h. H2S generating capability of these cells were measured in cell homogenate. Mitophagy was detected by LC3B immunostaining, Western blot and flow cytometry analyses. To enhance the endogenous production of H2S and clearance of Hcy, cystathionine μ‐synthase (CBS), cystathionine γ‐lyase (CSE) and 3‐mercaptopyruvate sulfurtransferase (3‐MST) cDNAs were delivered to the hGMEnds. Results demonstrate that Hcy attenuate H2S generation in the culture medium as well as endogenous production of H2S. Hcy also induced mitophagy in hGMEnds and either H2S supplementation or CBS, CSE and 3‐MST gene delivery ameliorated Hcy‐induced mitophagy. We conclude that gene delivery of Hcy metabolic enzymes CBS, CSE and 3‐MST protects cells from Hcy toxicity by converting Hcy to an anti‐ oxidant, anti‐hypertensive and anti‐apoptotic agent, H2S.