Beta-agonist stimulation ameliorates the phenotype of spinal and bulbar muscular atrophy mice and patient-derived myotubes

Sci Rep. 2017 Jan 24:7:41046. doi: 10.1038/srep41046.

Abstract

Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease characterized by the loss of lower motor neurons. SBMA is caused by expansions of a polyglutamine tract in the gene coding for androgen receptor (AR). Expression of polyglutamine-expanded AR causes damage to motor neurons and skeletal muscle cells. Here we investigated the effect of β-agonist stimulation in SBMA myotube cells derived from mice and patients, and in knock-in mice. We show that treatment of myotubes expressing polyglutamine-expanded AR with the β-agonist clenbuterol increases their size. Clenbuterol activated the phosphatidylinositol-3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway and decreased the accumulation of polyglutamine-expanded AR. Treatment of SBMA knock-in mice with clenbuterol, which was started at disease onset, ameliorated motor function and extended survival. Clenbuterol improved muscle pathology, attenuated the glycolytic-to-oxidative metabolic alterations occurring in SBMA muscles and induced hypertrophy of both glycolytic and oxidative fibers. These results indicate that β-agonist stimulation is a novel therapeutic strategy for SBMA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology*
  • Animals
  • Clenbuterol / pharmacology*
  • Disease Models, Animal
  • Humans
  • Male
  • Mice
  • Mice, Transgenic
  • Muscle Fibers, Skeletal / cytology
  • Muscle Fibers, Skeletal / drug effects*
  • Muscle Fibers, Skeletal / metabolism
  • Muscular Disorders, Atrophic / drug therapy*
  • Muscular Disorders, Atrophic / metabolism
  • Muscular Disorders, Atrophic / pathology
  • Peptides
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Androgen / genetics*
  • Signal Transduction*
  • TOR Serine-Threonine Kinases / metabolism
  • Trinucleotide Repeat Expansion

Substances

  • Adrenergic beta-Agonists
  • Peptides
  • Receptors, Androgen
  • polyglutamine
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Clenbuterol