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 March 1, 2018; First 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 1

The synonymous coding SCN5A SNP, rs1805126, modulates the miR-24–SCN5A interaction.

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The synonymous coding SCN5A SNP, rs1805126, modulates the miR-24–SCN5A i...
(A) Schematic of the conserved miR-24–SCN5A interaction identified by Ago2 HITS-CLIP (read coverage shown above). The site resides within the coding region of the SCN5A terminal exon and is adjacent to the synonymous SNP rs1805126 (*) that has previously been linked to heart rhythm abnormalities by GWAS. (B–D) The effect of miR-24 on SCN5A expression, and the potential impact of rs1805126 on this interaction, was tested in cell culture experiments. Mouse N2a cells were cotransfected in triplicate with synthetic pre-miRs (4 nM) and human full-length SCN5A expression plasmids harboring either the C or T allele for rs1805126, or synonymous mutations that disrupt the miR-24 seed site (mut*, base mutations are indicated in bold in panel A). At 48 hours after transfection, Western blot and QPCR analyses were used to measure protein and mRNA expression. (B) Representative Western blots show that miR-24 strongly suppresses NaV1.5 expression, having a more robust effect on the C allele, relative to T. Densitometry analysis of Western blot data (n = 9 biological replicates from 3 separate studies for C versus T, n = 4 for mutated) supports a significant allele-specific difference in miR-24 suppression of NaV1.5 levels (C), as does QPCR analyses measuring SCN5A mRNA levels (D; n = 6 biological replicates from 2 studies). Data are represented as the mean ± SEM, and P values were obtained using 2-tailed unpaired t test comparing the indicated groups.