LRRC8A contributes to angiotensin II-induced cardiac hypertrophy by interacting with NADPH oxidases via the C-terminal leucine-rich repeat domain

Cardiac hypertrophy, an important cause of heart failure, is characterized by an increase in heart weight, the ventricular wall, and cardiomyocyte volume. The volume regulatory anion channel (VRAC) is an important regulator of cell volume. However, its role in cardiac hypertrophy remains unclear. The purpose of this study was to investigate the effect of leucine-rich repeat-containing 8A (LRRC8A), an essential component of the VRAC, on angiotensin II (AngII)-induced cardiac hypertrophy. Our results showed that LRRC8A expression, NADPH oxidase activity, and reactive oxygen species (ROS) production were increased in AngII-induced hypertrophic neonatal mouse cardiomyocytes and the myocardium of C57/BL/6 mice. In addition, AngII activated VRAC currents in cardiomyocytes. The delivery of adeno-associated viral (AAV9) bearing siRNA against mouse LRRC8A into the left ventricular wall inhibited AngII-induced cardiac hypertrophy and fibrosis. Accordingly, the knockdown of LRRC8A attenuated AngII-induced cardiomyocyte hypertrophy and VRAC currents in vitro. Furthermore, knockdown of LRRC8A suppressed AngII-induced ROS production, NADPH oxidase activity, the expression of NADPH oxidase membrane-bound subunits Nox2, Nox4, and p22phox, and the translocation of NADPH oxidase cytosolic subunits p47phox and p67phox. Immunofluorescent staining showed that LRRC8A co-localized with NADPH oxidase membrane subunits Nox2, Nox4, and p22phox. Co-immunoprecipitation and analysis of a C-terminal leucine-rich repeat domain (LRRD) mutant showed that LRRC8A physically interacts with Nox2, Nox4, and p22phox via the LRRD. Taken together, the results of this study suggested that LRRC8A might play an important role in promoting AngII-induced cardiac hypertrophy by interacting with NADPH oxidases via the LRRD.