Fig. 3. SIRT1 regulated the aging process of PD-NSCs after IR.

a, b Cell senescence induced by IR was aggravated by downregulation of SIRT1 in WT-NSCs. WT-NSCs infected with SIRT1 shRNA were exposed to 10 Gy IR and incubated for 48 h. Scale bar: 100 μm. c Protein levels of aging-related genes in WT-NSCs with Sirt1 knockdown increased significantly, analyzed by western blotting and densitometry. d, e The expression of Ki67 decreased by knockdown of Sirt1 in WT-NSCs after IR treatment. Scale bar: 100 μm. f, g DNA damage accumulation represented by γH2AX foci enhanced dramatically in WT-NSCs with downregulated Sirt1 expression at 48 h post IR treatment. Scale bar: 10 μm. h, i Proliferative capacity as revealed by Ki67 staining was increased by overexpression of Sirt1 in PD-NSCs after IR treatment. SIRT1 expression in PD-NSCs was increased using a recombinant lentivirus encoding wild-type SIRT1, then cells were exposed to 10 Gy IR and incubated for 48 h. Scale bar: 100 μm. j Aging-related genes in PD-NSCs with Sirt1 overexpression further decreased, analyzed by western blotting and densitometry. All data were obtained from at least three independent experiments; mean ± SD, ***P < 0.001, **P < 0.01, *P < 0.05, ns not statistically significant, Student’s t-test