Characterization of a novel Nav1.5 channel mutation, A551T, associated with Brugada syndrome
Journal
Journal of Biomedical Science
Journal Volume
16
Journal Issue
1
Date Issued
2009
Author(s)
Abstract
Brugada syndrome is a life-threatening, inherited arrhythmia disorder associated with autosomal dominant mutations in SCN5A, the gene encoding the human cardiac Na+ channel subunit (Nav1.5). Here, we characterized the biophysical properties of a novel Brugada syndrome-associated Nav1.5 mutation, A551T, identified in a proband who was successfully resuscitated from an episode of ventricular fibrillation with sudden collapse. Whole-cell currents through wild-type (WT) Nav1.5 and mutant (A551T) channels were recorded and compared in the human embryonic kidney cell line HEK293T transfected with SCN5A cDNA and SCN1B cDNA, using the patch-clamp technique. Current density was decreased in the A551T mutant compared to the WT. In addition, the A551T mutation reduced Nav1.5 activity by promoting entry of the channel into fast inactivation from the closed state, thereby shifting the steady-state inactivation curve by -5 mV. Furthermore, when evaluated at -90 mV, the resting membrane potential, but not at the conventionally used -120 mV, both the percentage, and rate, of channel recovery from inactivation were reduced in the mutant. These results suggest that the DI-DII linker may be involved in the stability of inactivation gating process. This study supports the notion that a reduction in Nav1.5 channel function is involved in the pathogenesis of Brugada syndrome. The structural-functional study of the Nav1.5 channel advances our understanding of its pathophysiolgocial function.
SDGs
Other Subjects
complementary DNA; sodium channel; muscle protein; SCN5A protein, human; sodium; a55it gene; alpha chain; article; Brugada syndrome; cell strain HEK293; channel gating; controlled study; disease association; gene; gene identification; gene mutation; genetic analysis; genetic transfection; heart electrophysiology; heart ventricle fibrillation; human; human cell; human cell culture; kidney cell; membrane steady potential; patch clamp; pathogenesis; priority journal; protein analysis; protein phosphorylation; site directed mutagenesis; steady state; whole cell; amino acid substitution; case report; cell line; cell membrane potential; chemistry; genetics; male; metabolism; middle aged; missense mutation; phosphorylation; physiology; point mutation; protein processing; structure activity relation; Amino Acid Substitution; Brugada Syndrome; Cell Line, Transformed; Humans; Ion Channel Gating; Male; Membrane Potentials; Middle Aged; Muscle Proteins; Mutagenesis, Site-Directed; Mutation, Missense; Patch-Clamp Techniques; Phosphorylation; Point Mutation; Protein Processing, Post-Translational; Sodium; Sodium Channels; Structure-Activity Relationship
Type
journal article