The Integrin-Ligand Interaction Regulates Adhesion and Migration through a Molecular Clutch
Figure 5
The efficiency of the ECM-actin linkage differs between α5β1 and α6β1 or αLβ2. CHO.B2 cells were doubly transfected with paxillin-Cherry and the indicated integrin (with GFP), then either plated on different concentration of substrates or cross-linked or poly-lysine treated substrates or treated with Mn2+.
(A) Fluxing is not affected by covalent cross-linking (x-link) or poly-L-lysine attachment (pLys). CHO-B2 cells doubly transfected with paxillin-Cherry and the indicated integrin (with GFP), then either plated on control, cross-linked or poly-L-lysine attached substrates. Average velocity of protein fluxing was quantified by STICS. Data are expressed as the mean ± SEM (n = 28 cells). Two-way ANOVA reveals that neither poly-L lysine attachment nor crosslinking have a significant effect on the flux velocity (P = 0.48). (B) Covalent cross-linking (Upper) or poly-L-lysine attachment (Lower) of the indicated integrin ligands did not significantly affect protrusion. Data are expressed as the mean ± SD of at least 3 independent experiments (n = 7, 7, 12, 15, 10, 7 for cross-linking, respectively; n = 8, 9, 8, 9, 8, 7 protrusions for poly-lysine, respectively.) Protrusion rates were obtained from kymographs. (C) Protrusion rates of cells expressing α5 or α6 integrins and plated on FN or LN, respectively. On FN, the protrusion rate decreases with increasing concentration (P<0.006). No significant difference was detected with LN. (D) Protrusion of CHO.B2 cells was inhibited by activating integrins with Mn2+ (P<1×10−6). Data are expressed as the mean ± SD of at least 3 independent experiments. (n = 9, 9, 10, 12, 9, 10 protrusions respectively.).