RT Journal Article
SR Electronic
T1 Early molecular events in the assembly of matrix adhesions at the leading edge of migrating cells
JF Journal of Cell Science
JO J. Cell Sci.
FD The Company of Biologists Ltd
SP 4605
OP 4613
DO 10.1242/jcs.00792
VO 116
IS 22
A1 Zaidel-Bar, Ronen
A1 Ballestrem, Christoph
A1 Kam, Zvi
A1 Geiger, Benjamin
YR 2003
UL http://jcs.biologists.org/content/116/22/4605.abstract
AB Cellular locomotion is driven by repeated cycles of protrusion of the leading edge, formation of new matrix adhesions and retraction of the trailing edge. In this study we addressed the molecular composition and dynamics of focal complexes, formed under the leading lamellae of motile cells, and their maturation into focal adhesions. We combined phase-contrast and fluorescence microscopy approaches to monitor the incorporation of phosphotyrosine and nine different focal adhesion proteins into focal complexes in endothelial cells, migrating into an in vitro `wound'. We show that newly formed complexes are located posterior to an actin-, VASP- and α-actinin-rich region in the lammelipodium. They are highly tyrosine phosphorylated, contain β3-integrin, talin, paxillin and low levels of vinculin and FAK, but are apparently devoid of zyxin and tensin. The recruitment of these proteins into focal complexes occurs sequentially, so that their specific protein composition depends on their age. Interestingly, double color, time-lapse movies visualizing both paxillin and zyxin, indicated that the transition from paxillin-rich focal complexes to definitive, zyxin-containing focal adhesions, takes place only after the leading edge stops advancing or retracts. These observations illuminate, for the first time, early stages in focal complex assembly and the dynamic process associated with its transformation into focal adhesion.