Association of 14-3-3 proteins to beta1-adrenergic receptors modulates Kv11.1 K+ channel activity in recombinant systems.
We identify a new mechanism for the beta(1)-adrenergic receptor (beta(1)AR)-mediated regulation of human ether-a-go-go-related gene (HERG) potassium channel (Kv11.1). We find that the previously reported modulatory interaction between Kv11.1 channels and 14-3-3epsilon proteins is competed by wild type beta(1)AR by means of a novel interaction between this receptor and 14-3-3epsilon. The association between beta(1)AR and 14-3-3epsilon is increased by agonist stimulation in both transfected cells and heart tissue and requires cAMP-dependent protein kinase (PKA) activity. The beta(1)AR/14-3-3epsilon association is direct, since it can be recapitulated using purified 14-3-3epsilon and beta(1)AR fusion proteins and is abolished in cells expressing beta(1)AR phosphorylation-deficient mutants. Biochemical and electrophysiological studies of the effects of isoproterenol on Kv11.1 currents recorded using the whole-cell patch clamp demonstrated that beta(1)AR phosphorylation-deficient mutants do not recruit 14-3-3epsilon away from Kv11.1 and display a markedly altered agonist-mediated modulation of Kv11.1 currents compared with wild-type beta(1)AR, increasing instead of inhibiting current amplitudes. Interestingly, such differential modulation is not observed in the presence of 14-3-3 inhibitors. Our results suggest that the dynamic association of 14-3-3 proteins to both beta(1)AR and Kv11.1 channels is involved in the adrenergic modulation of this critical regulator of cardiac repolarization and refractoriness.
Tutor
Antonio S
AS
Departamento de Biología Molecular and Centro de Biología Molecular "Severo Ochoa," Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Delpón
Eva
E
Caballero
Ricardo
R
Gómez
Ricardo
R
Núñez
Lucía
L
Vaquero
Miguel
M
Tamargo
Juan
J
Mayor
Federico
F
Penela
Petronila
P
D048948:14-3-3 Proteins / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism*; D013997:Time Factors
D048948:14-3-3 Proteins; C489610:KCNV2 protein, human; D050505:Mutant Proteins; D024642:Potassium Channels, Voltage-Gated; D018342:Receptors, Adrenergic, beta-1; D011994:Recombinant Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol