Figure 3. SUN1 depletion increases APB formation in TOP3α-knockdown cells. (A) U2OS and VA13 cells were infected with control (shLuc), shSUN1, shTOP3α, or shSUN1 combined with shTOP3α lentiviruses and selected for 3 days. Cell lysates were analyzed by immunoblotting with anti-SUN1, anti-TOP3α, and anti-GAPDH antibodies. The arrowhead indicates the location of the TOP3α protein. GAPDH was used as the loading control. (B) Representative images show the colocalization of TRF2 and PML in U2OS cells (upper panel) and VA13 cells (bottom panel), as shown in Figure 1. Scale bar, 20 μm. (C) Quantification of APBs (%) in the U2OS and VA13 cells shown in (B). Approximately 200-300 cells were analyzed for each independent experiment. Error bars denote SD; n=3 (independent experiments); *P<0.05 (two-tailed Student’s t-test). N.S., no significance.