We have studied the motility of wild-type F9 and vinculin-deficient (5
.51) mouse embryonal carcinoma cells. F9 cells extended filopodia at a
rate of 61 (+/- 18) nm/s over a distance of 3.18 (+/- 0.29) mu m. In
contrast, 5.51 cells exhibited filopodia which extended at a similar s
peed of 57 (+/- 17) nm/s but over a longer distance of 5.10 (+/- 2.14)
mu m. Cell-substratum contact areas of both cell types were examined
by reflection interference contrast microscopy. Wild-type F9 cells had
distinct close contacts (dark gray areas) at the cell periphery, wher
eas 5.51 cells had only a few light gray pinpoint contacts with the su
bstrate. Confocal microscopy showed alpha-actinin to be localized alon
g actin stress fibers in wild-type cells, and in 5.51 cells stress fib
ers were absent and alpha-actinin was associated with F-actin in the f
ilopodia. beta(1)-integrin, talin, and paxillin were concentrated in f
ocal contacts in wild-type cells, but in 5.51 cells beta(1)-integrin a
nd talin were in patches under the plasma membrane and paxillin was di
ffusely distributed in the cytoplasm. We conclude that changes in cell
shape and motility of 5.51 compared to wild-type F9 cells are due to
the absence of vinculin even though there may be functions of other fo
cal adhesion complex proteins, e.g., talin, linking the actin cytoskel
eton to the plasma membrane. (C) 1995 Academic Press, Inc.