Figure 2.

YAP/TAZ response to matrix elasticity. (A) Focal adhesions on 3T3 fibroblasts cultured on matrices of different stiffnesses from 1–125 kPa. Scale bar, 30 μm. Increased cell adhesions were found in cells cultured on stiff matrices. (B) Predictions showed trends similar to those of experiments and followed a Hill-type function. Mean ± SE of n = 23 (1 kPa), 27 (15 kPa), 20 (25 kPa), 31 (45 kPa), 26 (65 kPa), and 34 (125kPa) cells from three independent experiments. (C) 3T3 fibroblasts cultured on matrices of different stiffness were immunostained for Y397-phosphorylated FAK (green). Scale bar, 30 μm. Cell lysate was analyzed by Western blot with antibodies for detecting specific FAK phosphorylation sites on Y397. Increased FAKpY397 levels were observed in cells on stiff matrices as can be identified from increased fluorescence intensity. (D) Adhesion reinforcement determines the change of traction force response to stiffness, i.e., biphasic or monotonic. (E) Cells cultured on a stiff matrix showed pronounced actin caps at the top the nucleus. Scale bar, 50 μm. (F) 3T3 fibroblasts cultured on matrices of different stiffness (1 and 65 kPa) were immunostained for YAP (green), F-actin (red), and DAPI (blue). Scale bar, 50 μm. Increased YAP N/C ratio was found in cells cultured on stiff matrices as can be identified from increased fluorescence intensity, with experiments and predictions following a Hill-type function. Mean ± SE of n = 18 (1 kPa), 21 (5 kPa), 18 (15 kPa), 24 (25 kPa), and 15 (65 kPa) cells from three independent experiments. To see this figure in color, go online.