RNA editing in the central cavity as a mechanism to regulate surface expression of the voltage-gated potassium channel Kv1.1.

Autor:	Streit AK; Institut für Physiologie und Pathophysiologie, Fachbereich Medizin, and Philipps-Universität Marburg, 35037 Marburg, Germany., Matschke LA; Institut für Physiologie und Pathophysiologie, Fachbereich Medizin, and Philipps-Universität Marburg, 35037 Marburg, Germany., Dolga AM; Institut für Pharmakologie und Klinische Pharmazie, Fachbereich Pharmazie, Philipps-Universität Marburg, 35037 Marburg, Germany., Rinné S; Institut für Physiologie und Pathophysiologie, Fachbereich Medizin, and Philipps-Universität Marburg, 35037 Marburg, Germany., Decher N; Institut für Physiologie und Pathophysiologie, Fachbereich Medizin, and Philipps-Universität Marburg, 35037 Marburg, Germany. Electronic address: decher@staff.uni-marburg.de.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2014 Sep 26; Vol. 289 (39), pp. 26762-26771. Date of Electronic Publication: 2014 Aug 06.
DOI:	10.1074/jbc.M113.545731
Abstrakt:	Voltage-gated potassium (Kv) 1.1 channels undergo a specific enzymatic RNA deamination, generating a channel with a single amino acid exchange located in the inner pore cavity (Kv1.1(I400V)). We studied I400V-edited Kv1.1 channels in more detail and found that Kv1.1(I400V) gave rise to much smaller whole-cell currents than Kv1.1. To elucidate the mechanism behind this current reduction, we conducted electrophysiological recordings on single-channel level and did not find any differences. Next we examined channel surface expression in Xenopus oocytes and HeLa cells using a chemiluminescence assay and found the edited channels to be less readily expressed at the surface membrane. This reduction in surface expression was verified by fluorescence imaging experiments. Western blot analysis for comparison of protein abundances and glycosylation patterns did not show any difference between Kv1.1 and Kv1.1(I400V), further indicating that changed trafficking of Kv1.1(I400V) is causing the current reduction. Block of endocytosis by dynasore or AP180C did not abolish the differences in current amplitudes between Kv1.1 and Kv1.1(I400V), suggesting that backward trafficking is not affected. Therefore, our data suggest that I400V RNA editing of Kv1.1 leads to a reduced current size by a decreased forward trafficking of the channel to the surface membrane. This effect is specific for Kv1.1 because coexpression of Kv1.4 channel subunits with Kv1.1(I400V) abolishes these trafficking effects. Taken together, we identified RNA editing as a novel mechanism to regulate homomeric Kv1.1 channel trafficking. Fine-tuning of Kv1.1 surface expression by RNA editing might contribute to the complexity of neuronal Kv channel regulation. (© 2014 by The American Society for Biochemistry and Molecular Biology, Inc.)
Databáze:	MEDLINE
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