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Stimulation of Na^+/K^+ ATPase activity and Na^+ coupled glucose transport by @b-catenin

Mentor Sopjani, Ioana Alesutan, Jan Wilmes, Miribane Dërmaku-Sopjani, Rebecca S Lam, Evgenia Koutsouki, Muharrem Jakupi, Michael Föller, and Florian Lang

Biochem Biophys Res Commun 402(3):4 (2010) PMID 20951116

@b-Catenin is a multifunctional protein stimulating as oncogenic transcription factor several genes important for cell proliferation. @b-Catenin-regulated genes include the serum- and glucocorticoid-inducible kinase SGK1, which is known to stimulate a variety of transport systems. The present study explored the possibility that @b-catenin influences membrane transport. To this end, @b-catenin was expressed in Xenopus oocytes with or without SGLT1 and electrogenic transport determined by dual electrode voltage clamp. As a result, expression of @b-catenin significantly enhanced the ouabain-sensitive current of the endogeneous Na^+/K^+-ATPase. Inhibition of vesicle trafficking by brefeldin A revealed that the stimulatory effect of @b-catenin on the endogenous Na^+/K^+-ATPase was not due to enhanced stability of the pump protein in the cell membrane. Expression of @b-catenin further enhanced glucose-induced current (Ig) in SGLT1-expressing oocytes. In the absence of SGLT1 Ig was negligible irrespective of @b-catenin expression. The stimulating effect of @b-catenin on both Na^+/K^+ ATPase and SGLT1 activity was observed even in the presence of actinomycin D, an inhibitor of transcription. The experiments disclose a completely novel function of @b-catenin, i.e. the regulation of transport.

Copyright © 2010 Elsevier Ltd. All rights reserved.

DOI: 10.1016/j.bbrc.2010.10.049
Version: za2963e q8za1 q8zbb q8zc4 q8zd0 q8zec q8zf6 q8zgd

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