Figure 6.

Age-dependent accumulation of unrepaired DNA DSBs in MNs of PRMT8-null mice. A, Immunoblot analysis of ADMA, CHOP (ER stress), BIP (ER stress marker), GFAP (astrocyte activation), and γH2AX (DNA repair) in spinal cord samples of 3-month-old and 20- to 24-month-old mice. B, Immunoblot analysis of ADMA, BIP, and γH2AX. Differentiated NSC34 MN cells were treated with thapsigargin or sodium arsenite for the indicated times. GAPDH served as a loading control. Note the unexpected accumulation of γH2AX upon ER stress. C, Immunoblot analysis of spinal cord samples taken from 12-month-old mice for γH2AX (n = 3 in each group). D, Immunostaining of spinal cord samples from 12-month-old mice for γH2AX. Representative images are shown. Immunoblot presented in C serves as a quantitative comparison. E, Left, Micro-irradiation-induced FUS recruitment to DNA DSBs. HeLa cells expressing GFP-FUS constitutively were micro-irradiated at 405 nm in a 150 × 1 pixel ROI (step size: 70 nm). Right, Comparative analysis of FUS kinetics in control versus ADOX-pretreated cells. Data are presented as mean ± SEM. ns, Nonsignificant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001 (Student's t test).