Figure 4
Palladin modulates cellular traction forces and mechanosensitivity.
(A) Snapshot of a Palld4 cell on elastic gel embedded with beads. Scale bar: 10 μm. (B) Snapshot of traction stress map with color values corresponding to different stress values. Cell contour is superimposed in black. (C) Total traction force per unit area of Palld4 cells shown in the same plot with EGFP-palladin cells for comparison. (p < 0.01 for 4–10 kPa, p < 0.001 for 10–30 kPa, Wilcoxon ranksum test). Each bar represents an average of data obtained from N = 30–40 cells from ~6 independent experiments per condition. (D) Bar graph for comparison between traction stresses exerted by different cell types on intermediate stiffness (10–30 kPa) gels, showing that shRNA control cells (PGIPZ) exert similar stresses as WT and EGFP palladin cells. (p < 0.001, Wilcoxon ranksum test for comparison between EGFP-palladin and Palld4 cells). Each bar represents an average of data obtained from N > 20 cells from ~5 independent experiments. Rhodamine-phalloidin staining of a Palld4 cell on (E) a soft (2 kPa) gel and (F) a stiff (25 kPa) gel. Scale bar: 10 μm (G) Bar graphs comparing the spread areas of EGFP-palladin (black) and Palld4 (gray) cells as a function of gel stiffness. (p < 0.001, Wilcoxon ranksum test, N > 20 cells in each bar for comparison between 1–4 kPa and 4–10 kPa, 10–30 kPa, 30–60 kPa gels; only first comparison shown in graph; p < 0.05, Wilcoxon ranksum test, N>20 cells for comparison between 10–30 kPa and 30–60 kPa for Palld4 cells).
