A common variant alters SCN5A–miR-24 interaction and associates with heart failure mortality
Xiaoming Zhang, … , Barry London, Ryan L. Boudreau
Xiaoming Zhang, … , Barry London, Ryan L. Boudreau
Published February 19, 2018
Citation Information: J Clin Invest. 2018;128(3):1154-1163. https://doi.org/10.1172/JCI95710.
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Research Article Cardiology Genetics

A common variant alters SCN5A–miR-24 interaction and associates with heart failure mortality

Abstract

SCN5A encodes the voltage-gated Na+ channel NaV1.5 that is responsible for depolarization of the cardiac action potential and rapid intercellular conduction. Mutations disrupting the SCN5A coding sequence cause inherited arrhythmias and cardiomyopathy, and single-nucleotide polymorphisms (SNPs) linked to SCN5A splicing, localization, and function associate with heart failure–related sudden cardiac death. However, the clinical relevance of SNPs that modulate SCN5A expression levels remains understudied. We recently generated a transcriptome-wide map of microRNA (miR) binding sites in human heart, evaluated their overlap with common SNPs, and identified a synonymous SNP (rs1805126) adjacent to a miR-24 site within the SCN5A coding sequence. This SNP was previously shown to reproducibly associate with cardiac electrophysiological parameters, but was not considered to be causal. Here, we show that miR-24 potently suppresses SCN5A expression and that rs1805126 modulates this regulation. We found that the rs1805126 minor allele associates with decreased cardiac SCN5A expression and that heart failure subjects homozygous for the minor allele have decreased ejection fraction and increased mortality, but not increased ventricular tachyarrhythmias. In mice, we identified a potential basis for this in discovering that decreased Scn5a expression leads to accumulation of myocardial reactive oxygen species. Together, these data reiterate the importance of considering the mechanistic significance of synonymous SNPs as they relate to miRs and disease, and highlight a surprising link between SCN5A expression and nonarrhythmic death in heart failure.

Authors

Xiaoming Zhang, Jin-Young Yoon, Michael Morley, Jared M. McLendon, Kranti A. Mapuskar, Rebecca Gutmann, Haider Mehdi, Heather L. Bloom, Samuel C. Dudley, Patrick T. Ellinor, Alaa A. Shalaby, Raul Weiss, W.H. Wilson Tang, Christine S. Moravec, Madhurmeet Singh, Anne L. Taylor, Clyde W. Yancy, Arthur M. Feldman, Dennis M. McNamara, Kaikobad Irani, Douglas R. Spitz, Patrick Breheny, Kenneth B. Margulies, Barry London, Ryan L. Boudreau

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Figure 5

Evaluation of oxidative stress in Scn5a heterozygous knockout mouse hearts.

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Evaluation of oxidative stress in Scn5a heterozygous knockout mouse hear...
Oxidation of dihydroethidium (DHE, a surrogate marker of steady-state levels of superoxide) was measured in fresh-frozen cardiac tissue sections collected from 7- to 8-month-old male Scn5a+/– mice and wild-type littermates (n = 3 each). Positive controls included sections treated with antimycin A (AntA, a mitochondrial electron transport chain blocker that is known increase ROS generation). Images were captured at ×40 magnification. Scale bars: 100 μm. (A) Representative photomicrographs of DHE-stained cardiac sections are shown. (B) Signal intensity quantified in 90 cells per group (i.e., 30 per mouse) is plotted (mean ± SEM). ****P < 0.0001 by 2-tailed t test.