Ouabain affects cell migration via Na,K-ATPase-p130cas and via nucleus-centrosome association

Abstract

Na,K-ATPase is a membrane protein that catalyzes ATP to maintain transmembrane sodium and potassium gradients. In addition, Na,K-ATPase also acts as a signal-transducing receptor for cardiotonic steroids such as ouabain and activates a number of signalling pathways. Several studies report that ouabain affects cell migration. Here we used ouabain at concentrations far below those required to block Na,K-ATPase pump activity and show that it significantly reduced RPE cell migration through two mechanisms. It causes dephosphorylation of a 130 kD protein, which we identify as p130cas. Src is involved, because Src inhibitors, but not inhibitors of other kinases tested, caused a similar reduction in p130cas phosphorylation and ouabain increased the association of Na,K-ATPase and Src. Knockdown of p130cas by siRNA reduced cell migration. Unexpectedly, ouabain induced separation of nucleus and centrosome, also leading to a block in cell migration. Inhibitor and siRNA experiments show that this effect is mediated by ERK1,2. This is the first report showing that ouabain can regulate cell migration by affecting nucleus-centrosome association.

Influence of Endogenous Cardiac Glycosides, Digoxin, and Marinobufagenin in the Physiology of Epithelial Cells

“…Some CG, including ouabain, digoxin, and digitonin, have been used as cardiac inotropic agents for almost 200 years; however, due to their narrow therapeutic index, the CG have been gradually replaced by other medications and presently are almost discontinued for this purpose [8]. Nonetheless, a fact that has given a renewed interest, on the study of these compounds, is the finding that apart from their effect on heart and hypertension, they influence an interesting variety of physiological and pathological processes, such as cell adhesion [9], growth, apoptosis, motility, and differentiation [10][11][12]. Among these, the ability to induce impairment of cell proliferation or activation of cell death by apoptosis or autophagy has led to consider CG as promising new therapeutic tools against cancer [13][14][15][16].…”