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- Title
Regulation of cardiac shal-related potassium channel Kv 4.3 by serum- and glucocorticoid-inducible kinase isoforms inXenopusoocytes.
- Authors
Baltaev, Ravshan; Strutz-Seebohm, Nathalie; Korniychuk, Ganna; Myssina, Svetlana; Lang, Florian; Seebohm, Guiscard
- Abstract
The human cardiac transient outward potassium currentIto is formed by co-assembly of voltage-dependent K+ channel (Kv 4.3) pore-forming a-subunits with differently spliced K channel interacting protein (KChIP) accessory proteins.Ito is of considerable importance for the normal course of the cardiac ventricular action potential. The present study was performed to determine whether isoforms of the serum- and glucocorticoid-inducible kinase (SGK) family influence Kv 4.3/KChIP2b channel activity in theXenopus laevisheterologous expression system. Co-expression of SGK1, but not of SGK2 or SGK3, increased Kv 4.3/KChIP2b channel currents. The up-regulation of the current was not due to changes in the activation curve or changes of channel inactivation. The currents in oocytes expressing Kv 4.3 alone were smaller than those in Kv 4.3/KChIP2b expressing oocytes, but were still stimulated by SGK1. The effect of wild-type SGK1 was mimicked by constitutively active SGK1 (SGK1S422D) but not by an inactive mutant (SGK1K127N). The current amplitude increase mediated by SGK1 was not dependent on NEDD4.2 or RAB5, nor did it reflect increased cell surface expression. In conclusion, SGK1 stimulates Kv 4.3 potassium channels expressed inXenopusoocytes by a novel mechanism distinct from the known NEDD4.2-dependent pathway.
- Subjects
POTASSIUM channels; ION channels; GLUCOCORTICOIDS; ANTI-inflammatory agents; ADRENOCORTICAL hormones; POTASSIUM
- Publication
Pflügers Archiv: European Journal of Physiology, 2005, Vol 450, Issue 1, p26
- ISSN
0031-6768
- Publication type
Article
- DOI
10.1007/s00424-004-1369-z