Cdk9-55: A new player in muscle regeneration

Authors

  • Cristina Giacinti,

    1. Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia
    2. Department of Histology and Medical Embryology, University of Rome “Sapienza”, Rome, Italy
    Search for more papers by this author
  • Antonio Musarò,

    1. Department of Histology and Medical Embryology, University of Rome “Sapienza”, Rome, Italy
    Search for more papers by this author
  • Giulia De Falco,

    1. Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia
    2. Department of Human Pathology and Oncology, University of Siena, Siena, Italy
    Search for more papers by this author
  • Isabelle Jourdan,

    1. Department of Histology and Medical Embryology, University of Rome “Sapienza”, Rome, Italy
    Search for more papers by this author
  • Mario Molinaro,

    1. Department of Histology and Medical Embryology, University of Rome “Sapienza”, Rome, Italy
    Search for more papers by this author
  • Luigi Bagella,

    1. Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia
    2. Division of Biochemistry and Biophysics, Department of Biomedical Sciences, National Institute of Biostructures and Biosystems, University of Sassari, Sassari, Italy
    Search for more papers by this author
  • Cristiano Simone,

    1. Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia
    2. Division of Medical Genetics, Department of Biomedicine in Childhood, University of Bari, Bari, Italy
    Current affiliation:
    1. Laboratory of Signal-dependent Transcription, DTP, Consorzio Mario Negri Sud, Santa Maria Imbaro (Ch), Italy.
    Search for more papers by this author
  • Antonio Giordano

    Corresponding author
    1. Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia
    2. Department of Human Pathology and Oncology, University of Siena, Siena, Italy
    • Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, PA.
    Search for more papers by this author

Abstract

Adult skeletal muscle contains a specialized population of myogenic quiescent stem cells, termed satellite cells, which contribute to repair myofibers after injury. During muscle regeneration, satellite cells exit their normal quiescent state, proliferate, activating MyoD and Myf-5 expression, and finally differentiate and fuse to reconstitute the injured muscle architecture. We have previously reported that cdk9 is required for myogenesis in vitro by activating MyoD-dependent transcription. In myoblasts induced to differentiate, MyoD recruits cdk9 on the chromatin of muscle-specific regulatory regions. This event correlates with chromatin-modifying enzyme recruitment and phosphorylation of cdk9-specific target residues at the carboxyl-terminal domain of RNA polymerase II. Here we report that a second cdk9 isoform, termed cdk9-55, plays a fundamental role in muscle regeneration and differentiation in vivo. This alternative form is specifically induced in injured myofibers and its activity is strictly required for the completion of muscle regeneration process. J. Cell. Physiol. 216: 576–582, 2008, © 2008 Wiley-Liss, Inc.

Ancillary