Faculty Collaboration Database

Regulation of caveolar cardiac sodium current by a single Gsalpha histidine residue. Am J Physiol Heart Circ Physiol 2008 Apr;294(4):H1693-9

Date

02/19/2008

Pubmed ID

18281377

DOI

10.1152/ajpheart.01337.2007

Scopus ID

2-s2.0-41749098073 (requires institutional sign-in at Scopus site)   40 Citations

Abstract

Cardiac sodium channels (voltage-gated Na(+) channel subunit 1.5) reside in both the plasmalemma and membrane invaginations called caveolae. Opening of the caveolar neck permits resident channels to become functional. In cardiac myocytes, caveolar opening can be stimulated by applying beta-receptor agonists, which initiates an interaction between the stimulatory G protein subunit-alpha (G(s)alpha) and caveolin-3. This study shows that, in adult rat ventricular myocytes, a functional G(s)alpha-caveolin-3 interaction occurs, even in the absence of the caveolin-binding sequence motif of G(s)alpha. Consistent with previous data, whole cell experiments conducted in the presence of intracellular PKA inhibitor stimulation with beta-receptor agonists increased the sodium current (I(Na)) by 35.9 +/- 8.6% (P < 0.05), and this increase was mimicked by application of G(s)alpha protein. Inclusion of anti-caveolin-3 antibody abolished this effect. These findings suggest that G(s)alpha and caveolin-3 are components of a PKA-independent pathway that leads to the enhancement of I(Na). In this study, alanine scanning mutagenesis of G(s)alpha (40THR42), in conjunction with voltage-clamp studies, demonstrated that the histidine residue at position 41 of G(s)alpha (H41) is a critical residue for the functional increase of I(Na). Protein interaction assays suggest that G(s)alphaFL (full length) binds to caveolin-3, but the enhancement of I(Na) is observed only in the presence of G(s)alpha H41. We conclude that G(s)alpha H41 is a critical residue in the regulation of the increase in I(Na) in ventricular myocytes.

Author List

Palygin OA, Pettus JM, Shibata EF

MESH terms used to index this publication - Major topics in bold

Adrenergic beta-Agonists
Animals
Caveolae
Caveolin 3
Cyclic AMP-Dependent Protein Kinases
GTP-Binding Protein alpha Subunits, Gs
Histidine
Ion Channel Gating
Isoproterenol
Male
Membrane Potentials
Models, Molecular
Mutagenesis, Site-Directed
Mutation
Myocytes, Cardiac
NAV1.5 Voltage-Gated Sodium Channel
Patch-Clamp Techniques
Protein Binding
Protein Conformation
Protein Kinase Inhibitors
Rats
Rats, Sprague-Dawley
Receptors, Adrenergic, beta
Sodium
Sodium Channels