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Cardiac voltage-gated sodium channel Nav1.5 is regulated by Nedd4-2 mediated ubiquitination.

Abstract：

:Na(v)1.5, the cardiac isoform of the voltage-gated Na+ channel, is critical to heart excitability and conduction. However, the mechanisms regulating its expression at the cell membrane are poorly understood. The Na(v)1.5 C-terminus contains a PY-motif (xPPxY) that is known to act as binding site for Nedd4/Nedd4-like ubiquitin-protein ligases. Because Nedd4-2 is well expressed in the heart, we investigated its role in the ubiquitination and regulation of Na(v)1.5. Yeast two-hybrid and GST-pulldown experiments revealed an interaction between Na(v)1.5 C-terminus and Nedd4-2, which was abrogated by mutating the essential tyrosine of the PY-motif. Ubiquitination of Na(v)1.5 was detected in both transfected HEK cells and heart extracts. Furthermore, Nedd4-2-dependent ubiquitination of Na(v)1.5 was observed. To test for a functional role of Nedd4-2, patch-clamp experiments were performed on HEK cells expressing wild-type and mutant forms of both Na(v)1.5 and Nedd4-2. Na(v)1.5 current density was decreased by 65% upon Nedd4-2 cotransfection, whereas the PY-motif mutant channels were not affected. In contrast, a catalytically inactive Nedd4-2 had no effect, indicating that ubiquitination mediates this downregulation. However, Nedd4-2 did not alter the whole-cell or the single channel biophysical properties of Na(v)1.5. Consistent with the functional findings, localization at the cell periphery of Na(v)1.5-YFP fusion proteins was reduced upon Nedd4-2 coexpression. The Nedd4-1 isoform did not regulate Na(v)1.5, suggesting that Nedd4-2 is a specific regulator of Na(v)1.5. These results demonstrate that Na(v)1.5 can be ubiquitinated in heart tissues and that the ubiquitin-protein ligase Nedd4-2 acts on Na(v)1.5 by decreasing the channel density at the cell surface.

journal_name

Circ Res

journal_title

Circulation research

authors

van Bemmelen MX,Rougier JS,Gavillet B,Apothéloz F,Daidié D,Tateyama M,Rivolta I,Thomas MA,Kass RS,Staub O,Abriel H

doi

10.1161/01.RES.0000136816.05109.89

subject

Has Abstract

pub_date

2004-08-06 00:00:00

pages

284-91

issue

eissn

0009-7330

issn

1524-4571

pii

01.RES.0000136816.05109.89

journal_volume

pub_type

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Cardiac voltage-gated sodium channel Nav1.5 is regulated by Nedd4-2 mediated ubiquitination.