Fig. 5.

Cbp-deficient LSK and progenitor cells demonstrated alterations of quiescence and apoptosis. (A) Representative FACS plots of annexin V/7-AAD staining on LSK and progenitor cells from Cbp wt and Cbp Mx mice. Percentages of apoptotic LSK and progenitor cells (annexin V⁺ 7-AAD⁻) from Cbp wt and Cbp Mx animals show increased apoptosis in LSK but not progenitors from Cbp Mx mice. Results shown are means ± standard errors of the means (SEM; n = 8 for Cbp wt; n = 9 for Cbp Mx). *, P < 0.05. (B) Both Cbp wt and Mx mice were injected with 1 mg of BrdU 24 h before analysis. Representative FACS plots show cell cycle distributions of LSK and progenitors in Cbp wt and Mx mice. DNA content was stained with 7-AAD. Graphs show the percentages of cells in the different cell cycle phases. The proportions of LSK and progenitor cells in S or G₂/M were similar between Cbp wt and Mx mice, suggesting that deletion of Cbp does not affect the cycling stem and progenitor cells. Data are mean ± SEM (n = 4 for Cbp wt; n = 5 for Cbp Mx). (C) The cell cycle status of LSK and progenitor cells was determined by the combined expression of the proliferation marker ki67 and the DNA-staining dye 7-AAD. Representative FACS plots from both Cbp wt and Cbp Mx mice are shown. Graphs show the proportions of LSK and progenitor cells at different stages of the cell cycle. Both Cbp Mx LSK and progenitors demonstrated an increase in quiescent (G₀) fractions. Results are shown as means ± SEM (n = 11 for Cbp wt; n = 14 for Cbp Mx). *, P < 0.05; **, P < 0.01. (D) Analysis of the LSK compartment under stress conditions. Cbp wt or Mx mice were treated with one dose of 5-FU, 4 weeks after poly(I)·poly(C) treatment. Graphs show the frequencies of LSK and its subpopulations 10 days after 5-FU treatment (left and middle panels). The cell cycle status of the LSK compartment was determined based on the expression of Ki-67 and staining with the DNA dye 7-AAD (right panel). Results are means ± SEM (N > 6). *, P < 0.05; ***, P < 0.001.