Enhancement of K2P2.1 (TREK1) background currents expressed in Xenopus oocytes by voltage-gated K+ channel β subunits.
OBJECTIVE
K(2P)2.1 (TREK1) two-pore-domain potassium channels control electrical activity in the central nervous system (CNS) and in the heart. Auxiliary β subunits (Kvβ) increase functional K+ channel diversity in the CNS. Based on similar tissue distribution and common functional significance of Kvβ2 protein and K(2P)2.1 channels in neuronal excitability, we hypothesized that Kvβ2 subunits modulate K2P2.1 currents.


METHODS
Rat K2P2.1 channels and rKvβ subunits were expressed in Xenopus laevis oocytes, and two-electrode voltage clamp electrophysiology was used to assess K2P2.1 function.


RESULTS
Kvβ2 subunits increased K(2P)2.1 currents by 2.9-fold in concentration-dependent fashion (I(0mV,K2P2.1), 0.53±0.07μA; I(0mV,K2P2.1+Kvβ2), 1.56±0.13μA; n=15). K2P2.1 channel stimulation resulted in resting membrane potential hyperpolarization by -10.7mV (n=15). Open rectification and current-voltage relationships of K(2P)2.1 channels were not markedly altered upon co-expression with Kvβ2, and K2P2.1 membrane expression was not affected by Kvβ2 subunits. Related subunits Kvβ1 (1.7-fold; n=16), Kvβ3 (2.2-fold; n=16), and Kvβ4 (2.8-fold; n=16) similarly activated K2P2.1 currents, indicating a broader role for Kvβ proteins in K2P2.1 regulation.


CONCLUSIONS
Kvβ subunits stabilize the resting membrane potential through enhancement of K2P2.1K+ currents. The significance of this previously unappreciated biophysical mechanism in neuronal physiology remains to be investigated.
Department of Cardiology, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
Jana
J
Kisselbach
Department of Cardiology, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
Patrick A
PA
Schweizer
Institute for Veterinary Physiology and Biochemistry, Justus-Liebig-University, Frankfurter Str. 100, D-35392 Giessen, Germany.
Rüdiger
R
Gerstberger
Department of Cardiology, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
Rüdiger
R
Becker
Department of Cardiology, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany.
Hugo A
HA
Katus
Department of Cardiology, University of Heidelberg, Im Neuenheimer Feld 410, D-69120 Heidelberg, Germany. Electronic address: dierk.thomas@med.uni-heidelberg.de.
Dierk
D
Thomas
D000818:Animals; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D004566:Electrodes; D004594:Electrophysiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009865:Oocytes / Q000502:physiology*; D024683:Potassium Channels, Tandem Pore Domain / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated / Q000494:pharmacology / Q000502:physiology*; D029867:Xenopus Proteins / Q000494:pharmacology / Q000502:physiology*; D014982:Xenopus laevis
C498949:Kvbeta2 protein, Xenopus; D024683:Potassium Channels, Tandem Pore Domain; D024642:Potassium Channels, Voltage-Gated; D029867:Xenopus Proteins; C103742:potassium channel protein TREK-1