Hepatitis C virus NS5A and core proteins induce oxidative stress-mediated calcium signalling alterations in hepatocytes

Background/Aims The hepatitis C virus (HCV) structural core and non-structural NS5A proteins induce in liver cells a series of intracellular events, including elevation of reactive oxygen and nitrogen species (ROS/RNS). Since oxidative stress is associated to altered intracellular Ca2+ homeostasis, we aimed to investigate the effect of these proteins on Ca2+ mobilization in human hepatocyte-derived transfected cells, and the protective effect of quercetin treatment. Methods Ca2+ mobilization and actin reorganization were determined by spectrofluorimetry. Production of ROS/RNS was determined by flow cytometry. Results Cells transfected with NS5A and core proteins showed enhanced ROS/RNS production and resting cytosolic Ca2+ concentration, and reduced Ca2+ concentration into the stores. Phenylephrine-evoked Ca2+ release, Ca2+ entry and extrusion by the plasma membrane Ca2+ -ATPase were significantly reduced in transfected cells. Similar effects were observed in cytokine-activated cells. Phenylephrine-evoked actin reorganization was reduced in the presence of core and NS5A proteins. These effects were significantly prevented by quercetin. Altered Ca2+ mobilization and increased calpain activation were observed in replicon-containing cells. Conclusions NS5A and core proteins induce oxidative stress-mediated Ca2+ homeostasis alterations in human hepatocyte-derived cells, which might underlie the effects of both proteins in the pathogenesis of liver disorders associated to HCV infection.