Positive regulation of STIM1/Orai1‐mediated store operated calcium entry by reactive oxygen species in human mesangial cells (LB731)

Abstract

Store operated calcium entry (SOCE) plays a pivotal role in physiological responses of glomerular mesangial cells (MCs). STIM1 and Orai1 proteins are the essential components of SOCE pathway. We have previously demonstrated that STIM1and Orai1 were required for SOCE in cultured human MCs. Reactive oxygen species (ROS) can function as intracellular second messengers and as pathogenic factors in a variety of cell types. Whether and how ROS regulate the STIM1/Orai1‐dependent SOCE in MCs is unknown. The aim of the present study was to explore the effect of ROS on SOCE and the mechanism involved in cultured human MCs. Using fura‐2 fluorescence ratiometry approach, we found that the cyclopiazonic acid (CPA, 25 μM)‐stimulated SOCE was significantly enhanced in MCs with H2O2 treatment (100 μM for 5 days). Consistent with the functional data, western blot analysis of whole cell lysates showed significant increases in expressions of STIM1 and Orai1 proteins by H2O2 treatment in the range of 10‐100 μM for the same time period. However, H2O2 treatment did not affect mRNA expression levels of both STIM1 and Orai1. Furthermore, NAC (4 mM), an antioxidant, had tendency to attenuation of high glucose‐stimulated STIM1 protein expression. Taken together, our results indicate that ROS promote SOCE by increasing STIM1/Orai1 protein expression via a post‐transcriptional mechanism.Grant Funding Source: NIH