Activation of apocynin-sensitive NADPH oxidase (Nox2) activity in INS-1 832/13 cells under glucotoxic conditions

Abstract

Several lines of recent evidence provided compelling evidence to suggest increased generation of reactive oxygen species (ROS) as causal for mitochondrial dysregulation and apoptosis in islet β-cells exposed to noxious stimuli including high glucose, lipids and proinflammatory cytokines. Studies along these lines are also suggestive of a significant contributory role for NADPH oxidase in the generation of ROS under the above conditions. We have recently reported a marked increase in the expression and activation of cytosolic components of NADPH oxidase (p47phox, Rac1) in cell culture models of glucotoxicity and in islets from T2DM animals (Zucker Diabetic Fatty rat) and humans. In this communication, we provide further evidence indicating significant activation of NADPH activity (~2-fold) in INS-1 832/13 cells exposed to chronic hyperglycemic conditions (20 mM; 48 h). We also report marked attenuation of this activity, by apocynin, a selective inhibitor of phagocyte-like NADPH oxidase (Nox2) activity. Together, our findings implicate Nox2 as a source for ROS generation in β-cells exposed to glucotoxic conditions.