A chemical chaperone improves muscle function in mice with a RyR1 mutation

Nat Commun. 2017 Mar 24;8:14659. doi: 10.1038/ncomms14659.

Abstract

Mutations in the RYR1 gene cause severe myopathies. Mice with an I4895T mutation in the type 1 ryanodine receptor/Ca2+ release channel (RyR1) display muscle weakness and atrophy, but the underlying mechanisms are unclear. Here we show that the I4895T mutation in RyR1 decreases the amplitude of the sarcoplasmic reticulum (SR) Ca2+ transient, resting cytosolic Ca2+ levels, muscle triadin content and calsequestrin (CSQ) localization to the junctional SR, and increases endoplasmic reticulum (ER) stress/unfolded protein response (UPR) and mitochondrial ROS production. Treatment of mice carrying the I4895T mutation with a chemical chaperone, sodium 4-phenylbutyrate (4PBA), reduces ER stress/UPR and improves muscle function, but does not restore SR Ca2+ transients in I4895T fibres to wild type levels, suggesting that decreased SR Ca2+ release is not the major driver of the myopathy. These findings suggest that 4PBA, an FDA-approved drug, has potential as a therapeutic intervention for RyR1 myopathies that are associated with ER stress.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Calcium / metabolism
  • Calcium Signaling / drug effects
  • Calsequestrin / metabolism
  • Carrier Proteins / metabolism
  • Endoplasmic Reticulum Stress / drug effects
  • Male
  • Mice, Inbred C57BL
  • Mice, Mutant Strains
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Muscle Proteins / metabolism
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / physiopathology*
  • Mutation / genetics*
  • Oxidative Stress / drug effects
  • Phenotype
  • Phenylbutyrates / pharmacology*
  • Reactive Oxygen Species / metabolism
  • Ryanodine Receptor Calcium Release Channel / genetics*
  • Signal Transduction / drug effects

Substances

  • Calsequestrin
  • Carrier Proteins
  • Muscle Proteins
  • Phenylbutyrates
  • Reactive Oxygen Species
  • Ryanodine Receptor Calcium Release Channel
  • triadin
  • 4-phenylbutyric acid
  • Calcium