Figure 4.

Apoptosis is altered in p37^Ing1-deficient thymocytes. A, spontaneous apoptosis is unchanged in p37^Ing1-deficient thymocytes. Thymocytes were isolated from two Wt, p37^Ing1-null, or p53-null mice, plated in triplicate, and cultured for 4 d ex vivo. Cells were harvested at 24-h intervals, fixed in 70% ethanol, and stained with propidium iodide and analyzed by FACS. B, thymocytes were isolated from Wt, p37^Ing1-null, p53-null, or p37^Ing1/p53-double null mice and either mock treated or irradiated with 2.5 Gy of ionizing radiation, fixed in 70% ethanol after 4 h, and stained with propidium iodide for FACS. Columns, average of three separate experiments. The difference in apoptosis between Wt and p37^Ing1-null or between p53-null and p37^Ing1/p53-double null thymocytes is statistically significant (P < 0.005). C and D, real-time PCR was done with primers to Puma or Bax on tissues harvested from mice that were either mock treated or whole-body treated with 10 Gy of ionizing radiation and harvested 4 h later. Columns, average values (relative fold induction) of three mice for each genotype. The difference in Bax expression is statistically significant between Wt and p37^Ing1-null tissues for thymus and spleen (P < 0.05), but not for brain and liver (P < 0.07). The difference in Bax expression between p53-null and p37^Ing1/p53-double null tissues is statistically significant for thymus, spleen, and brain (P < 0.05), but not for liver (P < 0.06).