Co-expression of KCNE2 and KChlP2c modulates the electrophysiologi- cal properties of Kv4.2 current in COS-7 cells
Aim: Several β-subunits have been suggested to modulate the electrophysiological properties of the transient outward current (Ito) in cardiac myocytes, including the obligatory β-subunit K^+-channel interacting protein (KChIP2) and KCNE2. However, neither KChIP2 nor KCNE2 modulation of Kv4.x (x=2 an...
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Published in | Acta pharmacologica Sinica Vol. 29; no. 6; pp. 653 - 660 |
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Main Author | |
Format | Journal Article |
Language | English |
Published |
2008
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Subjects | |
Online Access | Get full text |
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Summary: | Aim: Several β-subunits have been suggested to modulate the electrophysiological properties of the transient outward current (Ito) in cardiac myocytes, including the obligatory β-subunit K^+-channel interacting protein (KChIP2) and KCNE2. However, neither KChIP2 nor KCNE2 modulation of Kv4.x (x=2 and/or 3) can fully recapitulate the electrophysiological properties of nativeIto. The present study is to investigate howIto current is modulated when both KChIP2 and KCNE2 are coexpressed. Methods: Kv4.2, KChIP2c, and KCNE2 cDNA were simultaneously transfected into COS-7 cells at a molar ratio of 3:1:1. Whole-cell currents were recorded by the patch-clamp method. Results: In comparison with the current regulated by KChIP2c alone, the co-expression of KCNE2 further slowed Kv4.2 current inactivation kinetics, but diminished KChIP2c-induced positive shift of the voltage-dependent activation of Kv4.2 current. Importantly, co-expression of KCNE2 accelerated the current recovery from inactivation, and caused an "overshoot" of peak current amplitude during Kv4.2 current recovery, a phenomenon which has been uniquely described for humanIto. However, co-expression of KCNE2 exerted no further effect on Kv4.2 current amplitude, the rate of Kv4.2 current activation and voltage-dependent inactivation. Conclusion: Co-expression of Kv4.2 with KChIP2c and KCNE2, but not with KChIP2c or KCNE2 alone, yields a current profile similar to nativeIto. Both KChIP2c and KCNE2 simultaneously participate in recapitulation of the electrophysiological properties of Ito in cardiac myocytes. |
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Bibliography: | KCNE2 electrophysiology transient outward current; Kv4.2; K^+-channel interacting protein; KCNE2; electrophysiology transient outward current Kv4.2 R96 K^+-channel interacting protein 31-1347/R |
ISSN: | 1671-4083 1745-7254 |