Fig. 5: Stress fibers and cortex bear distinct mechanical loads.
From: Intracellular tension sensor reveals mechanical anisotropy of the actin cytoskeleton
a from left to right: orthogonal U2OS cell aligned (⊥) (left), cortical actin at 0% strain, cortical actin at 15% strain, SFs at 0% strain, SFs at 15% strain. b \(\Delta {{{{{\rm{FRET\; E}}}}}}\) of SFs and cortical actin in parallel TS cells (∥) under strain. Data are presented as mean values ±SD. n = 8 for 5%, n = 8 for 10%, n = 5 for 15%, and n = 6 for 20% strain. Šidák’s significance test for 5% p(SFs and cortical actin) = 0.9983, for 10% p(SFs and cortical actin) = 0.6172, for 15% p(SFs and cortical actin) = 0.9869, for 20% p(SFs and cortical actin) = 0.9937. c\(\Delta {{{{{\rm{FRET\; E}}}}}}\) of SFs and cortical actin in orthogonal TS cells (⊥) under strain. n = 9 for 5%, n = 8 for 10%, n = 5 for 15%, and n = 6 for 20% strain. Data are presented as mean values ±SD. Šidák’s significance test for 5% p(SFs and cortical actin) = 0.9943, for 10% p(SFs and cortical actin) = 0.7562, for 15% p(SFs and cortical actin) = 0.0013, for 20% p(SFs and cortical actin)<0.0001. d \({{{{{\rm{SF}}}}}}\,\Delta {{{{{\rm{FRET\; E}}}}}}\) against cortical \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for TS cells. Two-sided t-test significance for the slope of the lines, p(ortho) = 0.0213, p(parallel)<0.0001. The slopes difference p-value < 0.0001, F = 28.37. e \({{{{{\rm{SF}}}}}}\,\Delta {{{{{\rm{FRET\; E}}}}}}\) as a function of cortical \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for 67 μM ML7 treated cells. Two-tailed t-test significance for the slopes, p(ortho) = 0.0024, p(parallel) = 0.0009. The slopes difference p-value = 0.9355, F = 0.0066. f \({{{{{\rm{SF}}}}}}\,\Delta {{{{{\rm{FRET\; E}}}}}}\) against \(\Delta {{{{{\rm{FRET\; E}}}}}}\) for TS+10 μM Y27632 cells. Two-sided t-test significance for the slopes, p(ortho) < 0.0001, p(parallel) < 0.0001. The slopes difference p-value = 0.9266, F = 0.008561. g SF-cortex load bearing in parallel and orthogonal directions, compared to ML7 and Blebbistatin-treated cells. Data are presented as the slope of the linear regression, ± regression SD. Šidák’s significance test for parallel cells, p(TS and TS + 67 μM ML7) < 0.0001, (TS and TS + 10 μM Y27632) < 0.0001, (10 μM Y27632 and TS + 67 μM ML7) = 0.9852. Šidák’s significance test for orthogonal cells, p(TS and TS + 67 μM ML7) < 0.0001, (TS and TS + 10 μM Y27632) < 0.0001, (10 μM Y27632 and TS + 67 μM ML7) = 0.8807. Error bars are SD of regression lines. n = 15 for ⊥(TS), n = 13 for ∥ (TS), n = 14 for ⊥ (TS+ML7), n = 19 for ∥ (TS+ML7), n = 11 for ⊥(TS+Blebb.), n = 9 for ∥(TS+Blebb). Scale bar is 5 μm. Source data are provided as a Source Data file.
