Figure 3.

Contractility and nuclear prestrain regulate strain transmission to the nucleus. (A) Microtensile device used for stretch with simultaneous epi-fluorescent imaging of cell and nuclear deformation on scaffolds. (B) Schematic of deformation analysis indicating the nuclear aspect ratio (NAR) and the locations of nuclear triads in the deformed (x) and undeformed (X) states that were used for Lagrangian strain calculation. (C) Lagrangian strains including shear strain (E₁₂), strain in the stretch direction (E₁₁), and strain perpendicular to the stretch direction (E₂₂). (D) Nuclear aspect ratio (NAR) for control cells normalized to the unstrained (0% strain) case. (E) Nuclear deformation index (NDI, which is NAR normalized to untreated control cells at the same strain, nNAR) for cells treated with ML7 (25 μM), Y27632 (10 μM), CytoD (2.5 μM), or LPA (50 μM). Nuclei that deform more than control have a positive NDI, and nuclei that deform less than control have a negative NDI. (Mean ± SE, n > 50 cells/group; two-way repeated measures ANOVA with Tukey’s post hoc testing.) To see this figure in color, go online.