Na/K-ATPase amplification of oxidant stress; a universal but unrecognized clinical target?

Abstract

The Na/K-ATPase has a signaling function which appears to be separate from its ion pumping function. This signaling function refers to the transduction of conformational changes in the Na/K-ATPase alpha1 subunit into activating Src’s tyrosine kinase activity, triggering a cascade which generates reactive oxygen species (ROS), modulates other signaling pathways, and causes many physiological and pathophysiological effects. We have recently observed that ROS themselves as well as cardiotonic steroids can actually initiate the signal by directly inducing conformational changes in alpha1. It therefore appears that the Na/K-ATPase signal cascade can serve as a feed forward amplification for ROS with circulating cardiotonic steroids setting the gain. Work in both cellular and animal models of disease suggest that this amplification process is activated in conditions characterized by oxidant stress ranging from cancer to obesity/metabolic syndrome and may serve as a potential clinical target for interventions.