Normal myoblast fusion requires myoferlin

Katherine R. Doherty, Andrew Cave, Dawn Belt Davis, Anthony J. Delmonte, Avery Posey, Judy U. Early, Michele Hadhazy, Elizabeth M. McNally*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

141 Scopus citations

Abstract

Muscle growth occurs during embryonic development and continues in adult life as regeneration. During embryonic muscle growth and regeneration in mature muscle, singly nucleated myoblasts fuse to each other to form myotubes. In muscle growth, singly nucleated myoblasts can also fuse to existing large, syncytial myofibers as a mechanism of increasing muscle mass without increasing myofiber number. Myoblast fusion requires the alignment and fusion of two apposed lipid bilayers. The repair of muscle plasma membrane disruptions also relies on the fusion of two apposed lipid bilayers. The protein dysferlin, the product of the Limb Girdle Muscular Dystrophy type 2 locus, has been shown to be necessary for efficient, calcium-sensitive, membrane resealing. We now show that the related protein myoferlin is highly expressed in myoblasts undergoing fusion, and is expressed at the site of myoblasts fusing to myotubes. Like dysferlin, we found that myoferlin binds phospholipids in a calcium-sensitive manner that requires the first C2A domain. We generated mice with a null allele of myoferlin. Myoferlin null myoblasts undergo initial fusion events, but they form large myotubes less efficiently in vitro, consistent with a defect in a later stage of myogenesis. In vivo, myoferlin null mice have smaller muscles than controls do, and myoferlin null muscle lacks large diameter myofibers. Additionally, myoferlin null muscle does not regenerate as well as wild-type muscle does, and instead displays a dystrophic phenotype. These data support a role for myoferlin in the maturation of myotubes and the formation of large myotubes that arise from the fusion of myoblasts to multinucleate myotubes.

Original languageEnglish (US)
Pages (from-to)5565-5575
Number of pages11
JournalDevelopment
Volume132
Issue number24
DOIs
StatePublished - Dec 2005

Keywords

  • Ferlin
  • Fusion
  • Myoblast

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology

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