ABSTRACT The study aimed to elucidate the mechanistic basis of impaired mechanosensitive pathways—YAP/TAZ and β‐catenin signaling—in filamin C‐deficient cells through investigation of transcriptomic profiles, actin cytoskeleton organization and focal adhesion structure. By using FlncKO‐C2C12 cells and testing a number of inhibitors, we identified that mechanosensitive processes depend on filamin C function. We detected that filamin C deficiency leads to increased F/G‐actin ratio and expansion of focal adhesion structures along with diminished nuclear accumulation of TAZ and β‐catenin and decreased YAP/TAZ activity. Verteporfin‐mediated YAP/TAZ inhibition caused adhesion enlargement and slight elevation of F/G‐actin ratio in WT‐C2C12 but had lower efficiency in FlncKO‐C2C12. Of note, actin cytoskeletal stabilization through Jasplakinolide treatment rescued YAP/TAZ signaling specifically in filamin C‐deficient cells, whereas inhibition of non‐muscle myosin II with (−)Blebbistatin failed to recapitulate the signaling suppression observed in control cells. In addition, ROCK inhibition with Y‐27632 demonstrated greater focal adhesion disassembly in FlncKO‐C2C12 cells than in WT‐C2C12 and produced a genotype‐specific response, restoring β‐catenin nuclear localization exclusively in FlncKO‐C2C12 without affecting WT‐C2C12 cells. In summary, we propose that in C2C12 muscle cells filamin C deficiency causes aberrant focal adhesion turnover and impairs actomyosin complex stabilization, which together compromise mechanosensitive pathways—YAP/TAZ and β‐catenin—and affect differentiation potential of muscle cells already at the myoblast stage.
Klimenko et al. (Sun,) studied this question.