Muscularizing tissues in the endocardial cushions of the avian heart are characterized by the expression of h1-calponin

Authors

  • Iris Moralez,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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    • I. Moralez and A. Phelps have contributed equally to this manuscript.

  • Aimée Phelps,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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    • I. Moralez and A. Phelps have contributed equally to this manuscript.

  • Barbara Riley,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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  • Miranda Raines,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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  • Elaine Wirrig,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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  • Brian Snarr,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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  • Jiang-Ping Jin,

    1. Section of Molecular Cardiology, Evanston Northwestern Healthcare and Northwestern University, Evanston, Illinois
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  • Maurice Van Den Hoff,

    1. Department of Anatomy & Embryology, Experimental and Molecular Cardiology Group, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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  • Stanley Hoffman,

    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
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  • Andy Wessels

    Corresponding author
    1. Department of Cell Biology and Anatomy, Cardiovascular Developmental Biology Center, Medical University of South Carolina, Charleston, South Carolina
    • Department of Cell Biology and Anatomy & Cardiovascular Developmental Biology Center, Medical University of South Carolina, 173 Ashley Avenue, Basic Science Building, Room 648B, P.O. Box 250508, Charleston, SC 29425
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Abstract

Muscularization of mesenchymal tissues in the developing heart is an important event in the morphogenesis of the valvuloseptal complex in four-chambered hearts. Perturbation of muscularization has been implicated in the pathogenesis of cardiac malformations in several animal models for congenital heart disease, including the Trisomy 16 mouse and the TGFβ2 knockout mouse. Studies to unravel the mechanism of muscularization, as well as studies to determine the extent of the process in frequently used animal-model systems for cardiac development, have, thus far, been hampered by the lack of useful differentiation markers for muscularizing tissues, albeit that it had been demonstrated that, in the mouse, muscularizing cells are characterized by an elevated level of smooth muscle actin expression. In this study, we investigated whether muscularization of endocardial cushions in the avian heart is also accompanied by the expression of smooth muscle cell markers. The results presented in this study demonstrate that, in quail and chick, a specific population of muscularizing cells is recognized by the expression of smooth muscle h1-calponin. Interestingly, other genes typically found in smooth muscle cells (e.g., smooth muscle actin and caldesmon) are not expressed in muscularizing tissues. We conclude that muscularization of cushion-derived mesenchymal tissues is associated with a discrete genetic program reflected by the expression of h1-calponin and predict that h1-calponin will prove an invaluable tool in elucidating the regulation of muscularization and other aspects related to this event. Developmental Dynamics 235:1648–1658, 2006. © 2006 Wiley-Liss, Inc.

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