Fig. 5. A working model of force propagation to the Cajal body.
Cajal body interactome under normal physiologic conditions (a) and under an external mechanical stress at the cell surface (b). Two major multi protein-RNA complexes in the Cajal body are characterized by coilin-mediated associations and SMN-mediated associations. Based on experimental results from Figs 1–4 and available literature, we propose a working model that an incoming force transmits into the nucleus via tensed F-actin to LINC, across the nuclear envelope to nuclear lamina, then to a putative nuclear force transmitting element (likely chromatin and/or an actin-dependent nuclear filamentous network32), from there to the CB to dissociate the protein complexes. LINC=linker of nucleoskeleton to cytoskeleton. snRNA=small nuclear RNA.