Lamellipodial actin mechanically links myosin activity with adhesion-site formation
Cell. 2007-02-01; 128(3): 561-575
Lire sur PubMed
1. Cell. 2007 Feb 9;128(3):561-75.
Lamellipodial actin mechanically links myosin activity with adhesion-site
Giannone G(1), Dubin-Thaler BJ, Rossier O, Cai Y, Chaga O, Jiang G, Beaver W,
Döbereiner HG, Freund Y, Borisy G, Sheetz MP.
(1)Department of Biological Sciences, Columbia University, New York, NY 10027,
Cell motility proceeds by cycles of edge protrusion, adhesion, and retraction.
Whether these functions are coordinated by biochemical or biomechanical processes
is unknown. We find that myosin II pulls the rear of the lamellipodial actin
network, causing upward bending, edge retraction, and initiation of new adhesion
sites. The network then separates from the edge and condenses over the myosin.
Protrusion resumes as lamellipodial actin regenerates from the front and extends
rearward until it reaches newly assembled myosin, initiating the next cycle.
Upward bending, observed by evanescence and electron microscopy, results in
ruffle formation when adhesion strength is low. Correlative fluorescence and
electron microscopy shows that the regenerating lamellipodium forms a cohesive,
separable layer of actin above the lamellum. Thus, actin polymerization
periodically builds a mechanical link, the lamellipodium, connecting myosin
motors with the initiation of adhesion sites, suggesting that the major functions
driving motility are coordinated by a biomechanical process.
PMID: 17289574 [Indexed for MEDLINE]