Figure 1.

MiTMABs induce apoptosis following cytokinesis failure in Hela cells. A-B, HeLa cells were released from the G₂/M boundary in the presence of MiTMAB, OcTMAB or controls (untreated, 0.1% DMSO and 2-(DiMA)EM) at the indicated concentrations. Cells were immediately monitored by time-lapse microscopy for 20 hours. A, Representative time-lapse images of a HeLa cell treated with 10 µM MiTMAB undergoing mitosis are shown. This cell undergoes apoptotic cell death, characterised by membrane blebbing, 420 min after failing cytokinesis. Cytokinesis failure was due to an inability to abscise the intracellular bridge, thus the cleavage furrow regressed resulting in formation of a binucleated cell. The percentage of binucleated HeLa cells that underwent apoptosis following cytokinesis failure are shown (B). Graph represents mean ± S.D. where n > 160 for each experimental condition. C, Asynchronously growing HeLa cells were monitored by time-lapse microscope for 20 h following addition of 30 µM MiTMAB, 4.5 µg/ml cytochalsin B (cytB) or controls (untreated, 0.1% DMSO and 2-(DiMA)EM). The graph represents mean ± S.D. of the percentage of cytokinesis failed HeLa cells that underwent apoptosis. D, G₂/M synchronized HeLa cells were analysed after 48 h following exposure to OcTMAB and controls (untreated, 0.1% DMSO and 2-(DiMA)EM) for the entire duration or for only the first 6 h (removal by washout). The graph (mean ± S.D. from two independent experiments) shows the percentage of apoptotic cells as indicated by <2N DNA content using flow cytometry.