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Cell Physiol Biochem. 2016;39(3):1031-9. doi: 10.1159/000447810. Epub 2016 Aug 19.

Up-Regulation of the Large-Conductance Ca2+-Activated K+ Channel by Glycogen Synthase Kinase GSK3β.

Author information

1
Department of Cardiology, Vascular Medicine and Physiology, University of Tuebingen, Tuebingen, Germany.

Abstract

BACKGROUND/AIMS:

The pleotropic functions of the large conductance Ca2+-activated K+ channels (maxi K+ channel or BK channels) include regulation of neuronal excitation and cell volume. Kinases participating in those functions include the glycogen synthase kinase GSK3 ß which is under negative control of protein kinase B (PKB/Akt). GSK3ß is inhibited by the antidepressant Lithium. The present study thus explored whether GSK3ß modifies the activity of BK channels.

METHODS:

cRNA encoding the Ca2+ insensitive BK channel mutant BKM513I+Δ899-903 was injected into Xenopus laevis oocytes without or with additional injection of cRNA encoding wild-type GSK3ß, inactive K85RGSK3ß, or wild-type GSK3ß with wild-type PKB. K+ channel activity was measured utilizing dual electrode voltage clamp.

RESULTS:

BK channel activity in BKM513I+Δ899-903 expressing oocytes was significantly increased by co-expression of GSK3ß, but not by co-expression of K85RGSK3ß. The effect of wild type GSK3ß was abrogated by additional co-expression of wild-type PKB and by 24 hours incubation with Lithium (1 mM). Disruption of channel insertion into the cell membrane by brefeldin A (5 µM) was followed by a decline of the current to a similar extent in oocytes expressing BK and GSK3ß and in oocytes expressing BK alone.

CONCLUSION:

GSK3ß may up-regulate BK channels, an effect disrupted by Lithium or additional expression of PKB and possibly participating in the regulation of cell volume and excitability.

PMID:
27537208
DOI:
10.1159/000447810
[Indexed for MEDLINE]
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