Extracellular matrix stiffness regulates fibroblast differentiation by influencing DNA methyltransferase 1 expression through microtubule polymerization

Cells sense physical cues, such as changes in extracellular matrix (ECM) stiffness, and translate these stimuli into biochemical signals that control various aspects of cellular behavior, thereby facilitating physiological and pathological processes in various organs. Evidence from multiple studies suggests that the anterior vaginal wall stiffness is higher in POP patients than in non-POP patients. Our experiments found that the expression of -smooth muscle actin (-SMA) in the anterior vaginal wall of patients with POP was increased, and the expression of DNMT1 was decreased. We used polyacrylamide gel to simulate matrix stiffening in vitro, and substrate stiffening induced the high expression of myofibroblast markers -SMA and CTGF in L929 cells. Inhibition of DNMT1 promotes fibroblast differentiation into myofibroblasts in vitro. The results of bioinformatics analysis showed that the expression of DNMT1 was significantly correlated with microtubule polymerization-related proteins. The experiment showed that the microtubule polymerization inhibitor nocodazole could eliminate the decrease of DNMT1 expression in fibroblasts induced by high stiffness. We conclude that fibroblasts sense an increase in the stiffness of the surrounding matrix and regulate fibroblast differentiation by regulating the expression of DNA methyltransferase 1 (DNMT1) through the regulation of microtubule polymerization. This study may help to elucidate the complex crosstalk between vaginal fibroblasts and their surrounding matrix in both healthy and pathological conditions, and provide new insights into the implications of potentially targeted phenotypic regulation mechanisms in material-related therapeutic applications.