Extracellular signal-regulated kinase plays a proapoptotic role in podocytes after reactive oxygen species treatment and inhibition of integrin–extracellular matrix interaction

Abstract

The effect of reactive oxygen species (ROS) and blocking integrin–extracellular matrix (ECM) interaction on apoptosis in podocytes, and the related signal transduction pathways remain unclear. Primary cultured rat podocytes were exposed to ROS. Integrin–ECM interaction was inhibited with anti-β1-integrin monoclonal antibody (mAb) or RGDS (Arg–Gly–Asp–Ser). Extracellular signal-regulated kinase (ERK) activation was evaluated with Western blotting. U0126 was used to inhibit ERK activation. Terminal deoxynucleotidyl transferase-mediated dUTP-peroxidase nick end-labeling of DNA (TUNEL) was used to evaluate apoptosis. We found that ROS-treated podocytes exhibited increased apoptosis, and both anti-β1-integrin mAb and RGDS induce apoptosis. Addition of ROS to either anti-β1-integrin mAb or RGDS enhanced apoptosis in both conditions. ERK activation was increased by either ROS or blocking integrin–ECM interaction. Preincubation with U0126 decreased apoptosis induced by ROS, anti-β1-integrin mAb or RGDS, respectively. Our study demonstrated that ROS and blocking integrin–ECM interaction induce podocyte apoptosis, which is mediated by ERK activation.