Figure 6.

The Actin-Binding Site Present in Vinculin Tail Is Important for Stretch-Induced Reorganization of Cell Polarity

(A) Still images from time-lapse recordings of MEFvin^−/− cells undergoing cyclic stretching, expressing indicated vinculin constructs (see Movie S7 for higher resolution). The FAs are color coded according to the angle between their main axis and the stretching axis: red for FAs in an angle between 0° and 30° to the stretching axis, green between 30° and 60°, and blue between 60° and 90°. Note the reorientation of FAs in cells expressing vinFL and vinT12 and the static behavior of FAs expressing vin258. FAs of cells expressing vinT12 reorganized faster than in vinFL-expressing cells, having reached their final position within 30 min of stretching (Movie S7). Scale bar represents 5 μm.

(B) Heat maps display the change in reorientation of the FAs (Δangle) relative to their initial angle (y axis) and during the time course of the stretching (x axis). The amplitude of the reorganization is color coded (see rainbow color bar). Most of the FAs with an initial angle between 0° and 60° to the stretching axis readily reoriented during the time of cyclic stretching. In contrast, FAs of cells without vinculin (MEFvin^−/− cells expressing paxillin-GFP as adhesion marker) or cells expressing vinculin constructs lacking the actin-binding site (vin258, vin880) were impaired in FA reorientation. The faster reorganization of FAs in cells expressing vinT12 highlights the importance of the vinculin-actin link in the transmission of stretch-induced forces.