Myosin IIIa boosts elongation of stereocilia by transporting espin 1 to the plus ends of actin filaments

Felipe T. Salles, Raymond C. Merritt, Uri Manor, Gerard W. Dougherty, Aurea D. Sousa, Judy E. Moore, Christopher M. Yengo, Andréa C. Dosé, Bechara Kachar

Research output: Contribution to journalArticlepeer-review

122 Scopus citations


Two proteins implicated in inherited deafness, myosin IIIa, a plus-end-directed motor, and espin, an actin-bundling protein containing the actin-monomer-binding motif WH2, have been shown to influence the length of mechanosensory stereocilia. Here we report that espin 1, an ankyrin repeat-containing isoform of espin, colocalizes with myosin IIIa at stereocilia tips and interacts with a unique conserved domain of myosin IIIa. We show that combined overexpression of these proteins causes greater elongation of stereocilia, compared with overexpression of either myosin IIIa alone or espin 1 alone. When these two proteins were co-expressed in the fibroblast-like COS-7 cell line they induced a tenfold elongation of filopodia. This extraordinary filopodia elongation results from the transport of espin 1 to the plus ends of F-actin by myosin IIIa and depends on espin 1 WH2 activity. This study provides the basis for understanding the role of myosin IIIa and espin 1 in regulating stereocilia length, and presents a physiological example where myosins can boost elongation of actin protrusions by transporting actin regulatory factors to the plus ends of actin filaments.

Original languageEnglish (US)
Pages (from-to)443-450
Number of pages8
JournalNature Cell Biology
Issue number4
StatePublished - 2009

All Science Journal Classification (ASJC) codes

  • Cell Biology


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