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Investigating the Pathogenesis of MYH7 Mutation Gly823Glu in Familial Hypertrophic Cardiomyopathy using a Mouse Model
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The molecular phenotype of human cardiac myosin associated with hypertrophic obstructive cardiomyopathy

Adam M Jacques1, Natalia Briceno, Andrew E Messer

  • 1Cardiac Medicine, National Heart and Lung Institute, Imperial College London, Guy Scadding Building, Dovehouse Street, London, UK.

Cardiovascular Research
|April 16, 2008
PubMed

Insights

Myosin from hypertrophic cardiomyopathy patients exhibits reduced motility and impaired contractility, similar to end-stage heart failure. A myosin heavy chain mutation can be predicted using a functional assay.

Area of Science:

  • Cardiovascular Biology
  • Muscle Physiology
  • Molecular Cardiology

Background:

  • Hypertrophic cardiomyopathy (HCM) is a genetic heart muscle disease.
  • Understanding the functional and structural properties of cardiac myosin is crucial for elucidating disease mechanisms.

Purpose of the Study:

  • To compare myosin's functional and structural properties and myocyte contractility in HCM patients versus controls.
  • To investigate the impact of HCM-associated mutations on myosin function.

Main Methods:

  • Myosin isolation and in vitro motility assays.
  • Analysis of myosin light chain-1 isoforms and myosin light chain-2 phosphorylation.
  • Measurement of isolated cardiomyocyte contractility.

Main Results:

  • Myosin from myectomy samples showed significantly reduced motility (21% less) compared to donor myosin.
  • HCM myosin displayed altered light chain composition and reduced phosphorylation.
  • Isolated cardiomyocytes from HCM patients exhibited impaired contraction and relaxation.

Conclusions:

  • HCM myectomy samples display a hypocontractile phenotype similar to end-stage heart failure.
  • This phenotype is not a direct result of the hypertrophy-inducing mutation.
  • A functional assay can predict the presence of myosin heavy chain mutations causing HCM.
Abstract

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