Molecular Mechanisms of the Redox Regulation of the Na,K-ATPase

Abstract

This review considers the molecular mechanisms involved in the redox regulation of the Na,K-ATPase. The enzyme creates a transmembrane gradient of sodium and potassium ions, which is necessary for the vital activity of all animal cells, and acts as a receptor of cardiotonic steroids (CTSs), which regulate cell proliferation and apoptosis. The function of the Na,K-ATPase depends on the cell’s redox status. Although oxidative stress was initially found to inhibit the enzyme, it is clear now that the redox regulation of the Na,K-ATPase activity is a complex process that cannot be explained only by oxidative damage to the protein. Na,K-ATPase activity is maximal at physiological oxygen concentrations and decreases by both hypoxia and hyperoxia, as well as due to decrease or increase of intracellular glutathione concentrations. Thus, a specific range of redox conditions provides maximal activity of the Na,K-ATPase. Now it is obvious that a disturbance of the Na,K-ATPase activity in a number of pathologies such as hypoxia, ischemia, diabetes, Alzheimer’s disease is associated with a change in redox status in the cells. The receptor function of the Na,K-ATPase also depends on the cell redox status and it isshould be taken into account when studying the effects of cardiotonic steroids on cells and tissues. The very special point of this review is the redox modifications of thiol groups in Na,K-ATPase subunits and the regulatory processes in which they are involved in normal and pathological conditions. Insight into the molecular mechanisms of redox regulation provides a better understanding of what is necessary for preventing Na,K-ATPase dysfunction in pathological conditions and thus reducing cell damage.