Mechanism of Ca overload caused by STIM1/ORAI1 activation of store-operated Ca entry (SOCE) in hydrogen peroxide-induced mitochondrial damage and apoptosis in human primary melanocytes.

BACKGROUND

Vitiligo is a common depigmentation disorder. Oxidative stress in melanocytes is thought to be the primary cause of vitiligo. Imbalances in cellular calcium ion (Ca) levels may be associated with the onset and progression of various diseases through a process that has been linked to oxidative stress. The purpose of this study was to investigate the regulatory mechanism by which Ca levels change in normal human melanocytes (NHMs) under oxidative stress, thereby providing new insights and potential clinical therapeutic targets for the pathogenesis and treatment of vitiligo.

METHODS AND RESULTS

Single-cell RNA sequencing data from vitiligo patients were analyzed using bioinformatics techniques. NHMs were treated with hydrogen peroxide (HO), store-operated Ca entry (SOCE) blocker BTP2, and SOCE agonist cyclopiazonic acid. Flow cytometry was used to detect Ca levels, apoptosis rates, intra-mitochondrial reactive oxygen species (ROS) levels, and mitochondrial membrane potential (MMP) damage. The expression levels of target proteins were detected using immunofluorescence, quantitative real-time PCR, and western blotting. We found that HO-induced oxidative stress resulted in significantly increased intracellular Ca levels, upregulation of stromal interaction molecule 1 (STIM1) and calcium release-activated calcium channel protein (ORAI1), and mitochondrial dysfunction. Inhibition of SOCE and small interfering RNA-mediated silencing of STIM1/ORAI1 expression lowered mitochondrial levels of ROS and oxidative stress-induced intracellular Ca overload and restored MMP, ultimately terminating oxidative stress-induced apoptosis.

CONCLUSIONS

Oxidative stress upregulates STIM1/ORAI1 expression, leading to melanocyte apoptosis via increased Ca influx, whereas inhibition of SOCE protects melanocytes against oxidative stress-induced damage.