Ankyrin-G coordinates intercalated disc signaling platform to regulate cardiac excitability in vivo.

Journal Article (Journal Article)

RATIONALE: Nav1.5 (SCN5A) is the primary cardiac voltage-gated Nav channel. Nav1.5 is critical for cardiac excitability and conduction, and human SCN5A mutations cause sinus node dysfunction, atrial fibrillation, conductional abnormalities, and ventricular arrhythmias. Further, defects in Nav1.5 regulation are linked with malignant arrhythmias associated with human heart failure. Consequently, therapies to target select Nav1.5 properties have remained at the forefront of cardiovascular medicine. However, despite years of investigation, the fundamental pathways governing Nav1.5 membrane targeting, assembly, and regulation are still largely undefined. OBJECTIVE: Define the in vivo mechanisms underlying Nav1.5 membrane regulation. METHODS AND RESULTS: Here, we define the molecular basis of an Nav channel regulatory platform in heart. Using new cardiac-selective ankyrin-G(-/-) mice (conditional knock-out mouse), we report that ankyrin-G targets Nav1.5 and its regulatory protein calcium/calmodulin-dependent kinase II to the intercalated disc. Mechanistically, βIV-spectrin is requisite for ankyrin-dependent targeting of calcium/calmodulin-dependent kinase II-δ; however, βIV-spectrin is not essential for ankyrin-G expression. Ankyrin-G conditional knock-out mouse myocytes display decreased Nav1.5 expression/membrane localization and reduced INa associated with pronounced bradycardia, conduction abnormalities, and ventricular arrhythmia in response to Nav channel antagonists. Moreover, we report that ankyrin-G links Nav channels with broader intercalated disc signaling/structural nodes, as ankyrin-G loss results in reorganization of plakophilin-2 and lethal arrhythmias in response to β-adrenergic stimulation. CONCLUSIONS: Our findings provide the first in vivo data for the molecular pathway required for intercalated disc Nav1.5 targeting/regulation in heart. Further, these new data identify the basis of an in vivo cellular platform critical for membrane recruitment and regulation of Nav1.5.

Full Text

Duke Authors

Cited Authors

  • Makara, MA; Curran, J; Little, SC; Musa, H; Polina, I; Smith, SA; Wright, PJ; Unudurthi, SD; Snyder, J; Bennett, V; Hund, TJ; Mohler, PJ

Published Date

  • November 7, 2014

Published In

Volume / Issue

  • 115 / 11

Start / End Page

  • 929 - 938

PubMed ID

  • 25239140

Pubmed Central ID

  • PMC4224970

Electronic International Standard Serial Number (EISSN)

  • 1524-4571

Digital Object Identifier (DOI)

  • 10.1161/CIRCRESAHA.115.305154


  • eng

Conference Location

  • United States