Fig. 4.

CTS causes loss from the nuclear envelope (NE) and turnover of SUN2 protein. a Changes to linker of nucleoskeleton and cytoskeleton (LINC) complex and NE proteins in primary hMSCs, detected and quantified by MS immediately following CTS (1 h at 5 Hz, 2.6–6.2% strain; n = 3 donors), relative to unstrained controls. SUN2 was found to be significantly down-regulated, but was recovered 24 h after CTS (Supplemental Fig. 3d). Numbers in blue indicate the number of peptides detected per protein identity. p-values were calculated using empirical Bayes-modified t-tests with Benjamini–Hochberg correction. See Supplementary Data 4. b Immunofluorescence (IF) quantification of proteins localized at the NE immediately following CTS (1 h at 5 Hz, 2.6–6.2% strain; n = 3 donors for SUN1, SUN2, LMNA, and LMNB1; n = 4 donors for EMD; see Supplementary Figs. 6a–e for data distributions and donor-to-donor variation). c IF quantification of SUN2 at the NE following 1 and 10 min of CTS at 5 Hz (2.6–6.2% strain; n = 3 donors). Red line indicates SUN2 levels following 1 h of CTS (p = 0.03). Significant loss of SUN2 at the NE occurred within 1 min (1 min, p = 0.002; 10 min, p < 0.0001). d Nuclear to cytoplasmic area ratios quantified following 1 and 10 min of 5 Hz CTS. Red line indicates area ratio following 1 h of CTS (p = 0.003; Fig. 1f). These results indicate that loss of SUN2 from the NE precedes changes to cellular morphology. p-values in b–d determined from linear models (ANOVA tests). All plots show mean ± s.e.m.; see Supplementary Table 1 for sample sizes