O tráfego não convencional da miosina nas células

sexta-feira, maio 29, 2009

Unconventional myosin traffic in cells reveals a selective actin cytoskeleton

Crista M. Brawley and Ronald S. Rock,1

+Author Affiliations

Department of Biochemistry and Molecular Biology, The University of Chicago, 929 East 57th Street 60637, Chicago, IL 60637

Edited by Ronald D. Vale, University of California, San Francisco, CA, and approved April 17, 2009 (received for review October 16, 2008)


Eukaryotic cells have a self-organizing cytoskeleton where motors transport cargoes along cytoskeletal tracks. To understand the sorting process, we developed a system to observe single-molecule motility in a cellular context. We followed myosin classes V, VI, and X on triton-extracted actin cytoskeletons from Drosophila S2, mammalian COS-7, and mammalian U2OS cells. We find that these cells vary considerably in their global traffic patterns. The S2 and U2OS cells have regions of actin that either enhance or inhibit specific myosin classes. U2OS cells allow for 1 motor class, myosin VI, to move along stress fiber bundles, while motility of myosin V and X are suppressed. Myosin X motors are recruited to filopodia and the lamellar edge in S2 cells, whereas myosin VI motility is excluded from the same regions. Furthermore, we also see different velocities of myosin V motors in central regions of S2 cells, suggesting regional control of motor motility by the actin cytoskeleton. We also find unexpected features of the actin cytoskeletal network, including a population of reversed filaments with the barbed-end toward the cell center. This myosin motor regulation demonstrates that native actin cytoskeletons are more than just a collection of filaments.

actin cytoskeleton myosin motors single-molecule


1To whom correspondence should be addressed. E-mail: rrock@uchicago.edu
Author contributions: C.M.B. and R.S.R. designed research; C.M.B. performed research; C.M.B. and R.S.R. contributed new reagents/analytic tools; C.M.B. and R.S.R. analyzed data; and C.M.B. and R.S.R. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.


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