Isoform switching from SM-B to SM-A myosin results in decreased contractility and altered expression of thin filament regulatory proteins

Gopal J. Babu, Gail J. Pyne, Yingbi Zhou, Chris Okwuchukuasanya, Joseph E. Brayden, George Osol, Richard J. Paul, Robert B. Low, Muthu Periasamy

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We previously generated an isoform-specific gene knockout mouse in which SM-B myosin is permanently replaced by SM-A myosin. In this study, we examined the effects of SM-B myosin loss on the contractile properties of vascular smooth muscle, specifically peripheral mesenteric vessels and aorta. The absence of SM-B myosin leads to decreased velocity of shortening and increased isometric force generation in mesenteric vessels. Surprisingly, the same changes occur in aorta, which contains little or no SM-B myosin in wild-type animals. Calponin and activated mitogen-activated protein kinase expression is increased and caldesmon expression is decreased in aorta, as well as in bladder. Light chain-17b isoform (LC17b) expression is increased in aorta. These results suggest that the presence or absence of SM-B myosin is a critical determinant of smooth muscle contraction and that its loss leads to additional changes in thin filament regulatory proteins.

Original languageEnglish (US)
Pages (from-to)C723-C729
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3 56-3
Publication statusPublished - Sep 1 2004
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Physiology
  • Cell Biology


  • Aorta
  • Caldesmon
  • Calponin
  • Mesenteric vessels

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