Splicing misregulation of SCN5A contributes to cardiac-conduction delay and heart arrhythmia in myotonic dystrophy

Nat Commun. 2016 Apr 11;7:11067. doi: 10.1038/ncomms11067.

Abstract

Myotonic dystrophy (DM) is caused by the expression of mutant RNAs containing expanded CUG repeats that sequester muscleblind-like (MBNL) proteins, leading to alternative splicing changes. Cardiac alterations, characterized by conduction delays and arrhythmia, are the second most common cause of death in DM. Using RNA sequencing, here we identify novel splicing alterations in DM heart samples, including a switch from adult exon 6B towards fetal exon 6A in the cardiac sodium channel, SCN5A. We find that MBNL1 regulates alternative splicing of SCN5A mRNA and that the splicing variant of SCN5A produced in DM presents a reduced excitability compared with the control adult isoform. Importantly, reproducing splicing alteration of Scn5a in mice is sufficient to promote heart arrhythmia and cardiac-conduction delay, two predominant features of myotonic dystrophy. In conclusion, misregulation of the alternative splicing of SCN5A may contribute to a subset of the cardiac dysfunctions observed in myotonic dystrophy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Alternative Splicing / genetics*
  • Animals
  • Arrhythmias, Cardiac / complications*
  • Arrhythmias, Cardiac / genetics*
  • Base Sequence
  • Binding Sites
  • Computer Simulation
  • Electrophysiological Phenomena
  • Exons / genetics
  • Female
  • HEK293 Cells
  • Heart Conduction System / pathology
  • Heart Conduction System / physiopathology*
  • Humans
  • Male
  • Middle Aged
  • Molecular Sequence Data
  • Myotonic Dystrophy / complications*
  • Myotonic Dystrophy / genetics*
  • NAV1.5 Voltage-Gated Sodium Channel / genetics*
  • NAV1.5 Voltage-Gated Sodium Channel / metabolism
  • Nucleotide Motifs / genetics
  • RNA-Binding Proteins / metabolism
  • Sodium Channels / metabolism
  • Xenopus

Substances

  • NAV1.5 Voltage-Gated Sodium Channel
  • RNA-Binding Proteins
  • SCN5A protein, human
  • Sodium Channels