Sarcomeric actin organization is synergistically promoted by tropomodulin, ADF/cofilin, AIP1 and profilin in C. elegans

Sawako Yamashiro, Elisabeth A. Cox, David L. Baillie, Jeff D. Hardin, Shoichiro Ono

    Research output: Contribution to journalArticlepeer-review

    29 Citations (Scopus)

    Abstract

    Sarcomeric organization of thin and thick filaments in striated muscle is important for the efficient generation of contractile forces. Sarcomeric actin filaments are uniform in their lengths and regularly arranged in a striated pattern. Tropomodulin caps the pointed end of actin filaments and is a crucial regulator of sarcomere assembly. Here, we report unexpected synergistic functions of tropomodulin with enhancers of actin filament dynamics in Caenorhabditis elegans striated muscle. Pointed-end capping by tropomodulin inhibited actin filament depolymerization by ADF/cofilin in vitro. However, in vivo, the depletion of tropomodulin strongly enhanced the disorganization of sarcomeric actin filaments in ADF/cofilin mutants, rather than antagonistically suppressing the phenotype. Similar phenotypic enhancements by tropomodulin depletion were also observed in mutant backgrounds for AIP1 and profilin. These in vivo effects cannot be simply explained by antagonistic effects of tropomodulin and ADF/cofilin in vitro. Thus, we propose a model in which tropomodulin and enhancers of actin dynamics synergistically regulate elongation and shortening of actin filaments at the pointed end.

    Original languageEnglish
    Pages (from-to)3867-3877
    Number of pages11
    JournalJournal of cell science
    Volume121
    Issue number23
    DOIs
    Publication statusPublished - 2008 Dec 1

    Keywords

    • Actin dynamics
    • Myofibrils
    • Pointed end
    • Striated muscle

    ASJC Scopus subject areas

    • Cell Biology

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