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. 1998 Mar 17;95(6):2956–2960. doi: 10.1073/pnas.95.6.2956

Figure 5.

Figure 5

Suppression of radiation-induced DNA fragmentation in HeLa/Tet-Bcl-2 and LYar/LYas by Bcl-2 is reversed in the presence of CM− medium. DNA fragmentation in mouse lymphoma and HeLa cells with either high or low Bcl-2 expression following exposure to 5 Gy γ-irradiation (dark bars) or sham irradiation (light bars) is shown. Previously we have reported that incubation cells in CM− medium sensitized them to radiation in the presence of Bcl-2 by depleting GSH (5). Therefore, LYar and HeLa cells expressing high levels of Bcl-2 were incubated in the presence of CM− medium following exposure to 5 Gy (hatched bar). Fragmentation was normalized to compare differences between induced fragmentation with different levels of Bcl-2 protein. In LYas cells fragmentation peaked at 4 h with approximately 80% of the DNA fragmented. The time course for DNA fragmentation in HeLa cells is of a longer duration. Maximum fragmentation was 30% measured at 120 h. Bcl-2 influence on radiation-induced DNA fragmentation could be measured as early as 24 h, which is reported in the figure. Error bars are SD from three samples, and each experiment was repeated with similar results.