Marina Cherniavsky Lev

Position: PhD Student

Contact Details:

E-mail: marina.cherniavsky-lev@weizmann.ac.il

Telephone: 972-8-934-2718

Research Description

Characterization of effects of cardiac glycosides on different isoforms of Na⁺/K⁺ ATPase in cellular systems

Na⁺/K⁺ ATPase is a ubiquitously expressed membrane protein, vital for maintenance of multiple cellular processes. It is composed of an α and β subunits that are often complexed with an FXYD protein. There are four isoforms of the α subunit, that despite their minor differences in sequence (~10%), differ significantly in biochemical qualities, cellular and tissue distribution and probably other functions. Cardiac glycosides (CGs) are a large family of compounds that act as specific inhibitors of Na⁺/K⁺ ATPase. Many studies have established that mammalian tissues and body fluids contain CGs-like compounds that were termed endogenous CGs. Different CGs vary in their effect on blood pressure as well as have very different effects on cell proliferation and anti-cancer properties. Accumulating data suggest that in addition to its classical role of Na and K pumping the Na⁺/K⁺ ATPase mediates a CG-triggered cascade of signal transduction which may underlay their anti- cancer and proliferative effects. Another well established phenomenon is cellular internalization of the Na⁺/K⁺ ATPase upon the binding of the CG ouabain. The underlying mechanism is poorly understood. The general objective of this research is to elucidate the relationship and the interactions between different Na⁺/K⁺ ATPase isoforms and various endogenous and exogenous CGs, at the cellular level, and to investigate the roles of the isoforms in various cellular processes, namely Na⁺/K⁺ ATPase internalization and signal transduction. By now we have demonstrated that low concentrations of ouabain can induce cell proliferation and internalization of Na⁺/K⁺ ATPase as opposed to the other endogenous CG digoxin and oleandrin that didn’t exhibit this activity. In addition we began to generate human cell line clones that express only the α2 or α3 but not α1. This cell clones will be used to characterize isoform specific effects of CG.

A                                                         B                                                      C

Confocal microscopy images at ×40 magnification of H1299-YFP cells. A. Cells before addition of ouabain. B. After 16 hrs incubation with 100 nM ouabain. C. Untreated cells after 16 hrs.

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