Cytoskeletal coherence requires myosin-IIA contractility
Journal of Cell Science. 2010-01-12; 123(3): 413-423
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1. J Cell Sci. 2010 Feb 1;123(Pt 3):413-23. doi: 10.1242/jcs.058297. Epub 2010 Jan
Cytoskeletal coherence requires myosin-IIA contractility.
Cai Y(1), Rossier O, Gauthier NC, Biais N, Fardin MA, Zhang X, Miller LW, Ladoux
B, Cornish VW, Sheetz MP.
(1)Department of Biological Sciences, Columbia University, New York, NY 10027,
Maintaining a physical connection across cytoplasm is crucial for many biological
processes such as matrix force generation, cell motility, cell shape and tissue
development. However, in the absence of stress fibers, the coherent structure
that transmits force across the cytoplasm is not understood. We find that
nonmuscle myosin-II (NMII) contraction of cytoplasmic actin filaments establishes
a coherent cytoskeletal network irrespective of the nature of adhesive contacts.
When NMII activity is inhibited during cell spreading by Rho kinase inhibition,
blebbistatin, caldesmon overexpression or NMIIA RNAi, the symmetric traction
forces are lost and cell spreading persists, causing cytoplasm fragmentation by
membrane tension that results in ‘C’ or dendritic shapes. Moreover, local
inactivation of NMII by chromophore-assisted laser inactivation causes local loss
of coherence. Actin filament polymerization is also required for cytoplasmic
coherence, but microtubules and intermediate filaments are dispensable. Loss of
cytoplasmic coherence is accompanied by loss of circumferential actin bundles. We
suggest that NMIIA creates a coherent actin network through the formation of
circumferential actin bundles that mechanically link elements of the peripheral
actin cytoskeleton where much of the force is generated during spreading.
PMID: 20067993 [Indexed for MEDLINE]