Histone Arginine Methylation-Mediated Epigenetic Regulation of Discoidin Domain Receptor 2 Controls the Senescence of Human Bone Marrow Mesenchymal Stem Cells

Figure 3

Inhibition of DDR2 induced in vitro cellular senescence and DNA damage in hBM-MSCs. (a) hBM-MSCs treated for four days with siRNA-targeted DDR2 (si-DDR2) exhibited reduced clone number and morphological changes characteristic of late-passage senescent cells. (b) qPCR and Western blot analyses confirmed that the mRNA, total protein, and phosphorylated protein levels of DDR2 were significantly reduced following DDR2 knockdown. (c) Both CCK8 and EdU assays indicated decreased cellular proliferation capacity after DDR2 knockdown. (d) The senescence marker β-Gal and DNA damage marker H2A.X Ser139 were increased in si-DDR2-transfected cells. (e) Comet assay showed that a much higher percentage of si-DDR2-transfected hBM-MSCs exhibited comet tails compared to the control. (f) DDR2 knockdown significantly increased p15, p21, and p16 expression and reduced TERT expression both at the mRNA and protein levels. For WB assays, the relative expression of phosphorylated DDR2 and total DDR2 refers to β-actin that was determined using density analysis, and the ratios were shown above the bands. Bars represent the standard error of the from three repeats. Statistical significance was determined by ANOVA and Student’s -test. , .

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