Cytoplasmic γ-actin contributes to a compensatory remodeling response in dystrophin-deficient muscle

Laurin M. Hanft, Inna N. Rybakova, Jitandrakumar R. Patel, Jill A. Rafael-Fortney, James M. Ervasti

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

Dystrophin mechanically links the costameric cytoskeleton and sarcolemma, yet dystrophin-deficient muscle exhibits abnormalities in cell signaling, gene expression, and contractile function that are not clearly understood. We generated new antibodies specific for cytoplasmic γ-actin and confirmed that γ-actin most predominantly localized to the sarcolemma and in a faint reticular lattice within normal muscle cells. However, we observed that γ-actin levels were increased 10-fold at the sarcolemma and within the cytoplasm of striated muscle cells from dystrophin-deficient mdx mice. Transgenic overexpression of the dystrophin homologue utrophin, or functional dystrophin constructs in mdx muscle, restored γ-actin to normal levels, whereas γ-actin remained elevated in mdx muscle expressing nonfunctional dystrophin constructs. We conclude that increased cytoplasmic γ-actin in dystrophin-deficient muscle may be a compensatory response to fortify the weakened costameric lattice through recruitment of parallel mechanical linkages. However, the presence of excessive myoplasmic γ-actin may also contribute to altered cell signaling or gene expression in dystrophin-deficient muscle.

Original languageEnglish (US)
Pages (from-to)5385-5390
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume103
Issue number14
DOIs
StatePublished - Apr 4 2006

Keywords

  • Costamere
  • Muscular dystrophy
  • Sarcolemma

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