Embryonic focal adhesions

Fak (focal adhesion kinase) is expressed in most tissues and is evolutionary conserved across species. It is activated by integrin clustering and by stimulation of several G protein-coupled recqrtors and RTKs. Fak is associated with focal adhesions and regulates cell spreading and migration. The kinase is essential for embryonic development since the homozygote Fak knockout is embryonic lethal. Pyk2 (proline-rich tyrosine kinase 2), the second member of the Fak kinase family has a more restricted expression pattern (primarily neuronal and hematopoietic cells) and does not localize to focal adhesions. 

Figure 9.3 Distribution of focal adhesion proteins on RGD nanopattemed surfaces. Embryonic rat fibroblasts were seeded onto nanopattemed surfaces with either a 58- or 108-nm separation distance between RGD ligands. The localization of focal adhesion proteins vincuhn and paxillin were visualized using immunofluorescence at 3 and 24 h post-seeding. Cells seeded on the 58-nm nanopattemed surfaces showed significantly higher degrees of cell spreading compared with those on the 108-nm surfaces. Actin filaments in the fibroblasts were stained using an immunofluorescent phalloidin stain [64],...

Figure 3. Focal adhesions in (A,B) embryonic fibroblasts and (C,D) tumor cells removed from MMTY-PyMT mice. Cells were plated on fibronectin in serum-free medium. Fibroblasts were stained with rhodamine-phalloidin, FITC conjugated anti-paxillin antibodies, and Hoechst 33258 stain. Tumor cells were stained with rhodamine-phalloidin and FITC conjugated anti-vinculin antibodies. Fluorescence images of the cells were obtained using a decovolution microscope. Paxillin and vinculin (green) are localized to ends of microfilaments (red) in focal adhesions. Mgat5 (A) fibroblasts and (C) tumor cell show focal adhesions but these structures are absent in MgatS (B) fibroblasts and (D) tumor cells. (E), T cell receptor dependent stimulation measured by H-thymi-dine incorporation in response to anti-CD3 antibodies at 48h (F) Model of responses to variable substratum adhesions for Mgat5 and Mgat5 cells.

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