Focal adhesion formation by f9 embryonal carcinoma cells after vinculin gene disruption

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Abstract
The assembly of focal adhesions was investigated in F9 embryonal carcinoma cells in which the expression of vinculin was eliminated by a targeted disruption of the vinculin gene. Vinculin-deficient F9 cells were capable of adhering to fibronectin-coated surfaces, though they displayed a reduced spreading compared to the parental cells. Transmission electron microscopy as well as inter-ference reflection microscopy of live cells showed that vinculin-null F9 cells formed focal adhesions that were indistinguishable from those of the control cells. Fluores-cent labeling for actin, talin, α-actinin, paxillin and phos-photyrosinated components indicated that the organization of all these focal contact-associated components was essen-tially identical in the vinculin-containing and vinculin-null cells. However, quantitative, digitized microscopy indicated that the intensity of fluorescence labeling in focal adhesions for α-actinin, talin and paxillin was significantly higher in cells lacking vinculin. The results suggest that there are multiple molecular mechanisms for the formation of focal adhesions in the absence of vinculin.