Fig. 1: The rate of cell stretch drives mechanosensing in a biphasic manner.

a Cells transfected with LifeAct-GFP and plated on polyacrylamide gels of 0.6 kPa or on glass. Insets are kymographs showing the movement of actin features along the lines marked in yellow. b Actin retrograde flow of cells cultured on 0.6 kPa gels or glass. n numbers are traces. c Nuclear, YAP, and paxillin stainings of cells stretched by 10% using the setup using triangular (Tr) and square (Sq) signals at different frequencies. Ns non-stretched cells. In YAP images, magenta outlines indicate the nucleus. In paxillin images, areas circled in red are shown magnified below. d Illustration of the stretch setup. e–h Quantifications of YAP nuclear to cytoplasmic ratios and paxillin focal adhesion lengths for cells stretched at 2.5 % (e), 5% (f) 10% (g), and 20% (h). Results are shown for non-stretched cells (Ns), cells stretched with triangular signals at different frequencies, and cells stretched with a square signal at 1 Hz (Sq). The effects of frequency were significant for both YAP and paxillin in all panels (p < 0.0001). The effect of square versus triangular 1 Hz signals was significant for paxillin at 5% stretch (p = 0.0025) and for both YAP and paxillin for 10 and 20% stretch (p < 0.0001). Statistical significance was assessed with Kruskal–Wallis tests. n numbers are cells. Scale bars are 50 μm in cells, 2 μm/40 s in kymographs (x/y axes), and 10 µm in magnifications. Data are shown as mean ± s.e.m.