Loss of quiescence of Gimap5-deficient HSCs and increased apoptosis of Gimap5-deficient LSK progenitors. (A) BrdU was injected into wild-type and Gimap5-deficient mice. 2 h later, BM cells were isolated from the mice and stained with anti-lineage cocktail (Mac-1, Gr-1, B220, CD4, CD8, and Ter-119), c-Kit, Sca-1, and CD135 antibodies, followed by BrdU and DAPI staining. The percentages indicate BrdU⁺ cells in gated LSK, LK, HSC, and MPP populations. (B) Statistical analysis of the percentages of BrdU⁺ cells from panel A. (C) BM cells from indicated mice were stained with anti-lineage cocktail, c-Kit, Sca-1, and CD135 or CD150 antibodies, followed by Pyronin Y and DAPI staining. The percentages of CD135⁻ LSK cells and CD150⁺ LSK cells in the G0, G1, and S + G2/M phases are shown. (D and E) BM cells from wild-type or Gimap5-deficient mice were stained with lineage cocktail, IL-7R, c-Kit, Sca-1, and CD135 antibodies, followed by Annexin V and DAPI staining. The percentages indicate apoptotic Annexin V⁺DAPI⁻ cells in LSK population (D) and in CD135⁻ LSK population (HSCs; E). (F) CD45.1⁺ B6 SJL recipients were transplanted with CD45.2⁺ wild-type (Gimap5^+/+) or CD45.2⁺ Gimap5-deficient (Gimap5^−/−) BM mixed 1:1 with wild-type competitor BM cells from B6 SJL mice as described in Fig. 3 C. 8 wk after BM transplantation, BrdU was injected into competitively reconstituted mice. 2 h later, the percentages of BrdU⁺ cells in CD45.2⁺CD135⁻ LSK population were determined by FACS. Data shown are representative of or obtained from three (A, B, and E), two (C and F), or five (D) mice of each genotype. Error bars show ±SD. *, P < 0.001; **, P < 0.05.