Fig. 1: Lamin-A L:N responds to changes in actomyosin contractility prior to lineage segregation. | Nature Communications

Fig. 1: Lamin-A L:N responds to changes in actomyosin contractility prior to lineage segregation.

From: The nuclear lamina couples mechanical forces to cell fate in the preimplantation embryo via actin organization

Fig. 1

a, b 3D immunofluorescence and quantification of Lamin-A/C lamina:nucleoplasm levels (Lamin-A/C L:N) in intact mouse embryos shows that Lamin-A/C L:N increases during development prior to lineage segregation. This is accompanied by changes in nuclear shape, with nuclei becoming more spherical over time. Treatment with H-1152 (50 µM, 4 h) causes a reduction in Lamin-A/C L:N and nuclear sphericity. Insets show 1 µm sections of the nucleus and 3D segmentation of the lamina (transparent) and nucleoplasm (opaque). Dots represent the mean and error bars represent SD (n = 10 for 2-cell, n = 34 for 4-cell, n = 59 for pre-compaction 8-cell, n = 54 for post-compaction 8-cell; P = 0.0002, Kruskal-Wallis test). c, d Immunofluorescence and quantification (fluorescence intensity standardized to DAPI) shows rising phosphorylated-myosin II between the 2-, 8-, and 16-cell stages. Dots represent the mean and error bars represent SD. n = 4 for 2-cell, n = 14 for 8 cell, and n = 16 for 16-cell. P = 0.0007 Kruskal-Wallis test. e Lamin-A/C L:N decreases after treatment with H-1152 at the 8-cell stage. n = 17 for control and H-1152. ****P < 0.0001, Mann-Whitney U test. f, Live-imaging of 4-cell and 8-cell cleavage divisions reveals greater deformation of cell shape at early stages. Utrophin-GFP allows 3D segmentation and analysis of local curvature. n = 11 for 4-8 cell, n = 8 for 8-16 cell. **P = 0.006, Mann-Whitney U test. Staining with phalloidin reveals an F-actin meshwork throughout the cytoplasm in early-stage mouse (g) and human (h) embryos. The meshwork extends from the cell cortex to the nucleus and the cytoplasmic density remains similar between the 2- and 8-cell stages. Representative examples selected from phalloidin stainings of >100 mouse embryos (g) and 9 human embryos (h). i, j Disrupting the contractility of the F-actin meshwork causes a reduction in mRuby-Lamin-A L:N. Spatiotemporally controlled stimulation of azido-blebbistatin was performed using a 860 nm laser targeting the F-actin meshwork between the nucleus and cortex (i). Graph shows mRuby-Lamin-A L:N following photostimulation. n = 4 for apical and basolateral, p = 0.0286, Mann-Whitney U test. All statistical tests are two-tailed. Bars in dot plots represent median and interquartile range. Scale bars, 10 µm. Source data are provided as a Source Data file.

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