Mouse transgenic lines that selectively label type I, type IIa, and types IIX+B skeletal muscle fibers

Authors

  • Joe V. Chakkalakal,

    1. Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, 52 Oxford Street, Cambridge, Massachusetts
    Current affiliation:
    1. Center of Regenerative Medicine, Massachusetts General Hospital, 185 Cambridge St., Charles River Plaza North, Boston, MA 02114S
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  • Shihuan Kuang,

    1. Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri
    Current affiliation:
    1. Department of Animal Sciences, Purdue University, 174B Smith Hall, 901 W State, St., West Lafayette, IN 47907
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  • Mario Buffelli,

    1. Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri
    Current affiliation:
    1. National Institute of Neuroscience and Department of Neurological and Visual Sciences, Section of Physiology, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy
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  • Jeff W. Lichtman,

    1. Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, 52 Oxford Street, Cambridge, Massachusetts
    2. Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri
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  • Joshua R. Sanes

    Corresponding author
    1. Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, 52 Oxford Street, Cambridge, Massachusetts
    2. Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri
    • Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, 52 Oxford Street, Cambridge, MA 02138
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Abstract

Skeletal muscle fibers vary in contractile and metabolic properties. Four main fiber types are present in mammalian trunk and limb muscles; they are called I, IIA, IIX, and IIB, ranging from slowest- to fastest-contracting. Individual muscles contain stereotyped proportions of two or more fiber types. Fiber type is determined by a combination of nerve-dependent and -independent influences, leading to formation of “homogeneous motor units” in which all branches of a single motor neuron form synapses on fibers of a single type. Fiber type composition of muscles can be altered in adulthood by multiple factors including exercise, denervation, hormones, and aging. To facilitate analysis of muscle development, plasticity, and innervation, we generated transgenic mouse lines in which Type I, Type IIA, and Type IIX+B fibers can be selectively labeled with distinguishable fluorophores. We demonstrate their use for motor unit reconstruction and live imaging of nerve-dependent alterations in fiber type. genesis 50:50–58, 2012. © 2011 Wiley Periodicals, Inc.

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