Fig. 1
Anisotropic texture of the mechanical environment increases EMT. a Schematic depiction of the edge areas of the expanding epithelial sheets, including formation of the finger-like protrusions (FLPs) led by “leading” cells and occasional separation of the tip cells (“dissemination”). It also defines the distance metric for the cell migration analysis in this and subsequent figures. The inset shows the electron micrograph of the NRA. b Cell trajectories colored to reflect the cell speed values in an expanding sheet on flat surfaces (top) and NRA (bottom). The colors of each dot indicate the mean speed values of the corresponding cells (left). The trajectories were tracked for 6 h with the speed measured every 20 min (right). c Migration speed of individual cells on flat and NRA substrata at different initial distances from the edge of the sheet (corresponding to values of d in panel a). Each dot represents the average speed of an individual cell. Dashed lines indicate the averaged speed of isolated individual cells on a flat surface (red) and NRA (blue) (each number of independently analyzed cells, n, is indicated, # = statistical significance of speed on the marginal region vs. the most submarginal region of cells on a flat surface (red) and NRA (blue), ##P < 5 × 10−4 and ###P < 5 × 10−6, * = statistical significance of the speed of cells on a flat surface vs. NRA, and *P < 0.05, **P < 5 × 10−4, and ***P < 5 × 10−6). d Disseminations from epithelial sheets per unit length of epithelial sheets on flat substrata and NRA for 18 h (n = 4 biologically independent experiments, * = statistical significance of numbers of dissemination on flat surfaces vs. NRA. ***P < 5 × 10−6). e The expression of Snail in the cells on flat surfaces and NRA analyzed by immunoblotting (n = 3 biologically independent samples, * = statistical significance of Snail expression in cells on flat vs. NRA substrata, *P < 0.05). f Dissemination from epithelial sheets on flat substrata and NRA in the presence of TGFβ (n = 4 biologically independent samples, * = statistical significance of the number of disseminations with control vs. TGFβ on the flat substratum (red) and on NRA (blue), flat substrata vs. NRA with TGFβ (black), *P < 0.05 and **P < 1 × 10−2). All error bars are S.E.M and statistical significance was determined by two-sided Student’s t-test
