This Article Full Text Full Text (PDF) All Versions of this Article: 90/1/e11    most recent hh0102.102977v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Baroudi, G. Articles by Chahine, M. Search for Related Content PubMed PubMed Citation Articles by Baroudi, G. Articles by Chahine, M. Pubmed/NCBI databases Gene GEO Profiles HomoloGene UniGene Genetics Home Reference Related Collections Arrythmias-basic studies Ion channels/membrane transport Arrhythmias, clinical electrophysiology, drugs

(Circulation Research. 2002;90:e11.)
© 2002 American Heart Association, Inc.

UltraRapid Communications

Expression and Intracellular Localization of an SCN5A Double Mutant R1232W/T1620M Implicated in Brugada Syndrome

Ghayath Baroudi, Said Acharfi, Chantal Larouche, Mohamed Chahine

From the Department of Medicine, Laval University and Québec Heart Institute, Laval Hospital Research Center, Sainte-Foy, Québec, Canada.

Correspondence to Dr M. Chahine, PhD, Laval Hospital Research Center, 2725 Chemin Sainte-Foy, Sainte-Foy, Québec, Canada G1V 4G5. E-mail Mohamed.Chahine{at}phc.ulaval.ca

Abstract

Brugada syndrome is an inherited cardiac disorder caused by mutations in the cardiac sodium channel gene, SCN5A, that leads to ventricular fibrillation and sudden death. This study reports the changes in functional expression and cellular localization of an SCN5A double mutant (R1232W/T1620M) recently discovered in patients with Brugada syndrome. Mutant and wild-type (WT) human heart sodium channels (hNa_v1.5) were expressed in tsA201 cells in the presence of the ß₁-auxiliary subunit. Patch-clamp experiments in whole-cell configuration were conducted to assess functional expression. Immunohistochemistry and confocal microscopy were used to determine the spatial distribution of either WT or mutant cardiac sodium channels. The results show an abolition of functional sodium channel expression of the hNa_v1.5/R1232W/T1620M mutant in the tsA201 cells. A conservative positively charged mutant, hNa_v1.5/R1232K/T1620M, produced functional channels. Immunofluorescent staining showed that the FLAG-tagged hNa_v1.5/WT transfected into tsA201 cells was localized on the cell surface, whereas the FLAG-tagged hNa_v1.5/R1232W/T1620M mutant was colocalized with calnexin within the endoplasmic reticulum (ER). These results indicate that a positively charged arginine or lysine residue at position 1232 in the double mutant is required for the proper transport and functional expression of the hNa_v1.5 protein. These results support the concept that loss of function of the cardiac Na⁺ channel is responsible for the Brugada syndrome. The full text of this article is available at http://www.circresaha.org.

Key Words: sodium channels • cardiac arrhythmias • protein trafficking • Brugada syndrome • ion channels

This article has been cited by other articles:

				T. Chen, M. Inoue, and M. F. Sheets Reduced voltage dependence of inactivation in the SCN5A sodium channel mutation delF1617 Am J Physiol Heart Circ Physiol, June 1, 2005; 288(6): H2666 - H2676. [Abstract] [Full Text] [PDF]

				Y. Qu, G. Baroudi, Y. Yue, N. El-Sherif, and M. Boutjdir Localization and modulation of {alpha}1D (Cav1.3) L-type Ca channel by protein kinase A Am J Physiol Heart Circ Physiol, May 1, 2005; 288(5): H2123 - H2130. [Abstract] [Full Text] [PDF]

				L. L. Shang and S. C. Dudley Jr. Tandem Promoters and Developmentally Regulated 5'- and 3'-mRNA Untranslated Regions of the Mouse Scn5a Cardiac Sodium Channel J. Biol. Chem., January 14, 2005; 280(2): 933 - 940. [Abstract] [Full Text] [PDF]

				P. J. Mohler, I. Rivolta, C. Napolitano, G. LeMaillet, S. Lambert, S. G. Priori, and V. Bennett Nav1.5 E1053K mutation causing Brugada syndrome blocks binding to ankyrin-G and expression of Nav1.5 on the surface of cardiomyocytes PNAS, December 14, 2004; 101(50): 17533 - 17538. [Abstract] [Full Text] [PDF]

				H. L Tan, C. R Bezzina, J. P.P Smits, A. O Verkerk, and A. A.M Wilde Genetic control of sodium channel function Cardiovasc Res, March 15, 2003; 57(4): 961 - 973. [Abstract] [Full Text] [PDF]

				C. Fan, M. Liu, and Q. Wang Functional Analysis of TBX5 Missense Mutations Associated with Holt-Oram Syndrome J. Biol. Chem., February 28, 2003; 278(10): 8780 - 8785. [Abstract] [Full Text] [PDF]

				B. Ye, C. R. Valdivia, M. J. Ackerman, and J. C. Makielski A common human SCN5A polymorphism modifies expression of an arrhythmia causing mutation Physiol Genomics, February 6, 2003; 12(3): 187 - 193. [Abstract] [Full Text] [PDF]

				C. R Bezzina and H. L Tan Pharmacological rescue of mutant ion channels Cardiovasc Res, August 1, 2002; 55(2): 229 - 232. [Full Text] [PDF]