Research Paper Volume 4, Issue 4 pp 270—278

Attenuation of constitutive DNA damage signaling by 1,25-dihydroxyvitamin D3


Figure 4. Effect of treatment of mitogenically stimulated proliferating human lymphocytes untreated or treated with H2O2 and 1,25-VD on the level of expression of γH2AX. Human peripheral blood lymphocytes mitogenically stimulated with PHA for 48 h were untreated (Ctrl) or treated with 10 nM 1,25-VD for 24 h (A). Cells in another set of cultures (B) were either untreated with 1,25-VD but exposed to 200 μM of H2O2 for 1 h (H2O2) or were pretreated with 1,25-VD for 24 h and then treated with 200 μM H2O2 for 1 h (+H2O2). Expression of γH2AX was detected immunocytochemically and cell fluorescence was measured by flow cytometry. Through gating analysis (as shown in Figs. 1-3) the mean values (+SD) of fluorescence intensity for cells in G1, S and G2M phases of the cell cycle were obtained and plotted as bar graphs. Numbers above the arrows show the percent decline of the mean values of the 1,25-VD-treated cells compared to the cells not treated with 1,25-VD in the respective phases of the cycle.