Myosin-X induces filopodia by multiple elongation mechanism

Tomonobu M. Watanabe, Hiroshi Tokuo, Kohsuke Gonda, Hideo Higuchi, Mitsuo Ikebe

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59 Citations (Scopus)


Filopodia are actin-rich finger-like cytoplasmic projections extending from the leading edge of cells. Unconventional myosin-X is involved in the protrusion of filopodia. However, the underlying mechanism of myosin-X-induced filopodia formation is obscure. Here, we studied the movements of myosin-X during filopodia protrusion using a total internal reflection microscope to clarify the mechanism of myosin-X-induced filopodia formation. Myosin-X was recruited to the discrete site at the leading edge where it assembles with exponential kinetics before the filopodia extension. The myosin-X-induced filopodia showed repeated extension-retraction cycles with each extension of 2.4 μm, which was critical to produce long filopodia. Myosin-X, lacking the FERM domain, could move to the tip as does the wild type. However, it was transported toward the cell body during filopodia retraction, did not undergo multiple extension-retraction cycles, and failed to produce long filopodia. During the filopodia protrusion, the single molecules of full-length myosin-X moved within filopodia. The majority of the fluorescence spots showed two-step photobleaching, suggesting that the moving myosin-X is a dimer. Deletion of the FERM domain did not change the movement at the single molecule level with the same velocity of ∼600 nm/s as wild-type, suggesting that the myosin-X in filopodia moves without interaction with the attached membrane via the FERM domain. Based upon these results, we have proposed a model of myosin-X-induced filopodia protrusion.

Original languageEnglish
Pages (from-to)19605-19614
Number of pages10
JournalJournal of Biological Chemistry
Issue number25
Publication statusPublished - 2010 Jun 18

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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