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Modeling Myotonic Dystrophy 1 in C2C12 Myoblast Cells
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Truncated ClC-1 mRNA in myotonic dystrophy exerts a dominant-negative effect on the Cl current

Jim Berg1, Hong Jiang, Charles A Thornton

  • 1Department of Neurobiology, Harvard Medical School, Boston, MA, USA.

Neurology
|December 30, 2004
PubMed
Abstract

Insights

Myotonic dystrophy (DM) myotonia stems from aberrant chloride channel (ClC-1) splicing. Aberrant splice variants of ClC-1 mRNA interfere with normal channel function, potentially causing myotonia.

Area of Science:

  • Molecular biology
  • Neuroscience
  • Genetics

Background:

  • Myotonic dystrophy (DM) is characterized by muscle fiber degeneration and myotonic discharges.
  • Myotonia in DM is linked to abnormal splicing of chloride channel (ClC-1) pre-messenger RNA (mRNA).
  • This aberrant splicing often leads to premature termination codons, reducing functional ClC-1 protein and chloride conductance.

Purpose of the Study:

  • To investigate the functional properties of commonly occurring DM-associated ClC-1 mRNA splice variants.
  • To determine the impact of these variants on chloride channel function.

Main Methods:

  • Expression of two common DM mRNA splice variants in oocytes.
  • Assessment of functional properties of expressed chloride channels.

Main Results:

  • Neither of the assessed DM splice variants produced a functional Cl- channel.
  • Co-expression of aberrant splice variants with wild-type ClC-1 cRNA diminished current density.
  • Aberrant variants accelerated channel closure upon membrane repolarization.

Conclusions:

  • Aberrantly spliced ClC-1 mRNA variants exhibit a dominant negative effect.
  • This dominant negative effect likely contributes to the development of myotonia in DM patients.

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