Actin turnover-dependent fast dissociation of capping protein in the dendritic nucleation actin network: Evidence of frequent filament severing

Takushi Miyoshi, Takahiro Tsuji, Chiharu Higashida, Maud Hertzog, Akiko Fujita, Shuh Narumiya, Giorgio Scita, Naoki Watanabe

    Research output: Contribution to journalArticlepeer-review

    86 Citations (Scopus)

    Abstract

    Actin forms the dendritic nucleation network and undergoes rapid polymerization-depolymerization cycles in lamellipodia. To elucidate the mechanism of actin disassembly, we characterized molecular kinetics of the major filament end-binding proteins Arp2/3 complex and capping protein (CP) using single-molecule speckle microscopy. We have determined the dissociation rates of Arp2/3 and CP as 0.048 and 0.58 s-1, respectively, in lamellipodia of live XTC fibroblasts. This CP dissociation rate is three orders of magnitude faster than in vitro. CP dissociates slower from actin stress fibers than from the lamellipodial actin network, suggesting that CP dissociation correlates with actin filament dynamics. We found that jasplakinolide, an actin depolymerization inhibitor, rapidly blocked the fast CP dissociation in cells. Consistently, the coexpression of LIM kinase prolonged CP speckle lifetime in lamellipodia. These results suggest that cofilin-mediated actin disassembly triggers CP dissociation from actin filaments. We predict that filament severing and end-to-end annealing might take place fairly frequently in the dendritic nucleation actin arrays.

    Original languageEnglish
    Pages (from-to)947-955
    Number of pages9
    JournalJournal of Cell Biology
    Volume175
    Issue number6
    DOIs
    Publication statusPublished - 2006 Dec 18

    ASJC Scopus subject areas

    • Cell Biology

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