Fig. 6: Accelerated mitotic exit coupled with genome instability in CHK2 KO and CHK2 Y156F HeLa cells.

A–C An accelerated mitotic exit was observed in CHK2 KO and CHK2 Y156F (#Y2) cells compared to parental HeLa and CHK2 WT (#58) cells. Cells were released from overnight nocodazole treatment, stained with Hoechst 33342, and subjected to high-content live-cell imaging. A comparison of progression toward G0/G1 between parental and CHK2 KO, analyzed using MetaXpress, is shown in (A) as mean ± SD from three independent experiments. Representative division with the time spanning between metaphase and cytokinesis is shown (B). Results of the analysis of 20–22 cells are shown in (C). Arrows indicate those cells that have been traced. Scale bar, 20 μM. D–F Enhanced genome instability was demonstrated by increased micronuclei in CHK2 KO and CHK2 Y156F HeLa cells. Cells were assessed for the presence of micronuclei two days after release from nocodazole-mediated arrest. DAPI-stained representative images are shown in (D) with arrows indicating micronuclei. Scale bar, 10 μM. Cells with more than one micronucleus were counted, and results from three independent experiments are shown in (E). Expression of CHK2, as assessed by western blot, is demonstrated in (F).