Muscle weakness in myotonic dystrophy associated with misregulated splicing and altered gating of Ca(V)1.1 calcium channel

Hum Mol Genet. 2012 Mar 15;21(6):1312-24. doi: 10.1093/hmg/ddr568. Epub 2011 Dec 2.


Myotonic dystrophy type 1 and type 2 (DM1 and DM2) are genetic diseases in which mutant transcripts containing expanded CUG or CCUG repeats cause cellular dysfunction by altering the processing or metabolism of specific mRNAs and miRNAs. The toxic effects of mutant RNA are mediated partly through effects on proteins that regulate alternative splicing. Here we show that alternative splicing of exon 29 (E29) of Ca(V)1.1, a calcium channel that controls skeletal muscle excitation-contraction coupling, is markedly repressed in DM1 and DM2. The extent of E29 skipping correlated with severity of weakness in tibialis anterior muscle of DM1 patients. Two splicing factors previously implicated in DM1, MBNL1 and CUGBP1, participated in the regulation of E29 splicing. In muscle fibers of wild-type mice, the Ca(V)1.1 channel conductance and voltage sensitivity were increased by splice-shifting oligonucleotides that induce E29 skipping. In contrast to human DM1, expression of CUG-expanded RNA caused only a modest increase in E29 skipping in mice. However, forced skipping of E29 in these mice, to levels approaching those observed in human DM1, aggravated the muscle pathology as evidenced by increased central nucleation. Together, these results indicate that DM-associated splicing defects alter Ca(V)1.1 function, with potential for exacerbation of myopathy.

Publication types

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

MeSH terms

  • Alternative Splicing*
  • Animals
  • CELF1 Protein
  • Calcium / metabolism*
  • Calcium Channels, L-Type / physiology*
  • Cells, Cultured
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Exons / genetics
  • Gene Expression Regulation
  • Humans
  • Immunoblotting
  • Ion Channel Gating / physiology*
  • Mice
  • Mice, Transgenic
  • Morpholinos / pharmacology
  • Muscle Weakness / etiology*
  • Muscle Weakness / metabolism
  • Muscle Weakness / pathology
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / metabolism
  • Myoblasts / cytology
  • Myoblasts / metabolism
  • Myotonic Disorders / physiopathology*
  • Myotonic Dystrophy / physiopathology*
  • Patch-Clamp Techniques
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction


  • CACNA1S protein, mouse
  • CELF1 Protein
  • CELF1 protein, mouse
  • Calcium Channels, L-Type
  • DNA-Binding Proteins
  • Mbnl1 protein, mouse
  • Morpholinos
  • RNA, Messenger
  • RNA-Binding Proteins
  • Calcium