NADPH oxidase and hydrogen peroxide mediate insulin-induced calcium increase in skeletal muscle cells

Abstract

Skeletal muscle is one of the main physiological targets of insulin, a hormone that triggers a complex signaling cascade and that enhances the production of reactive oxygen species (ROS) in different cell types. ROS, currently considered second messengers, produce redox modifications in proteins such as ion channels that induce changes in their functional properties. In myotubes, insulin also enhances calcium release from intracellular stores. In this work, we studied in myotubes whether insulin stimulated ROS production and investigated the mechanisms underlying the insulin-dependent calcium increase: in particular, whether the late phase of the Ca2+ increase induced by insulin required ROS. We found that insulin stimulated ROS production, as detected with the probe 2′, 7′-dichlorofluorescein diacetate (CM-H2DCFDA). We used the translocation of p47phox from the cytoplasm to the plasma membrane as a marker of the activation of NADPH oxidase. Insulin-stimulated ROS generation was suppre