Motility of vinculin-deficient F9 embryonic carcinoma cells analyzed by video, laser confocal, and reflection interference contrast microscopy.

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) microns. In contrast, 5.51 cells exhibited filopodia which extended at a similar speed of 57 (+/- 17) nm/s but over a longer distance of 5.10 (+/- 2.14) microns. 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, whereas 5.51 cells had only a few light gray pinpoint contacts with the substrate. Confocal microscopy showed alpha-actinin to be localized along actin stress fibers in wild-type cells, and in 5.51 cells stress fibers were absent and alpha-actinin was associated with F-actin in the filopodia. beta 1-integrin, talin, and paxillin were concentrated in focal contacts in wild-type cells, but in 5.51 cells beta 1-integrin and talin were in patches under the plasma membrane and paxillin was diffusely 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 focal adhesion complex proteins, e.g., talin, linking the actin cytoskeleton to the plasma membrane.