In:
Pacing and Clinical Electrophysiology, Wiley, Vol. 37, No. 7 ( 2014-07), p. 853-863
Kurzfassung:
A KCNE1 polymorphism, D85N, causes long QT syndrome (LQTS) with a decrease in the slowly activating delayed‐rectifier K + channel current (I Ks ). We examined impacts of D85N polymorphism on KCNE1 protein stability and functions, and tested the ability of various drugs to modify them. Methods KCNE1‐D85N or the wild‐type protein was coexpressed in COS7 cells with KCNQ1 to form K + channels. Expression, degradation, and intracellular localization of KCNE1 proteins, as well as the currents conferred by KCNQ1/KCNE1 complexes, were determined using immunoblots, immunofluorescence, and patch‐clamp techniques. Results The protein level of KCNE1‐D85N was lower than that of the wild‐type, in spite of the comparable levels of their mRNA. KCNE1‐D85N was highly ubiquitinated and rapidly degraded as compared to the wild‐type; a proteasome inhibitor, MG132, inhibited its degradation and increased its steady‐state level. Both KCNE1‐D85N and the wild‐type proteins were co‐immunoprecipitated with KCNQ1. Immunofluorescent signals of KCNE1‐D85N accumulated in the endoplasmic reticulum and Golgi apparatus, with reduced levels on the cell membrane. Patch‐clamp experiments demonstrated that the membrane current corresponding to I Ks was much smaller in cells expressing KCNE1‐D85N than in those expressing the wild‐type. Verapamil (0.5–10 μM) increased the protein level of KCNE1‐D85N, decreased its ubiquitination, slowed its degradation, and enhanced KCNQ1/KCNE1‐D85N channel currents. Pretreatment with amiodarone abolished these effects of verapamil. Conclusion KCNE1‐D85N is less stable than the wild‐type protein, and is rapidly degraded through the ubiquitin‐proteasome system. Verapamil may be of a therapeutic value in LQTS patients via preventing degradation of KCNE1‐D85N.
Materialart:
Online-Ressource
ISSN:
0147-8389
,
1540-8159
DOI:
10.1111/pace.2014.37.issue-7
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2014
ZDB Id:
2037547-5
