Fig. 6: Mechanotransductive signals delivered by stiff substrates drive epigenetic repression of α-Klotho.

A Latrunculin A, an inhibitor of actin polymerization, rescued stiff matrix-induced increases in DNMT1 and reduction of α-Klotho, type II collagen (Col2), and aggrecan (Acan) in aged chondrocytes, as quantified by immunofluorescence (n = 3/group except for Col2 [n = 4/group]; 30–60 cells per individual sample). Scale bar: 20 μm. B Inhibition of actin polymerization blocked the stiff substrate-driven increased Klotho promoter and global DNA methylation in aged chondrocytes (n = 3/group). C Inhibition of actin polymerization blocked the stiff substrate-driven increased binding of RNA Polymerase II (Pol II), c-MYC, but not H3K4M2, at Dnmt1 promoter in aged chondrocytes as quantified by chromatin immunoprecipitation (ChIP) analyses (n = 4/group). D Inhibition of actin polymerization blocked the stiff substrate-driven increased binding of DNMT1 at Klotho promoter in aged chondrocytes as quantified by ChIP analyses (n = 4/group). Statistical analyses were performed using a linear mixed effect model (A) or two-tailed paired t test (B–D). Data are presented as means ± 95% confidence intervals. Source data are provided as a Source Data file.