Meis1 deletion leads to loss of quiescence in LT-HSCs. (A) Meis1-flox/CreER and control mice were treated with tamoxifen and, 1 week later, BM was analyzed by flow cytometry for cell-cycle analysis. Flow cytometry plots depict results of pyronin Y (vertical axis, RNA stain) and Hoechst (horizontal axis, DNA stain) staining gated on the LSK and LT-HSC fractions. Left lower quadrant represents cells in G0, left upper quadrant G1, and upper right S phase. Data are summarized in the bar graph to the right (n = 2 control and 3 Meis1 deleted). (B) Mice were treated as in panel A and then injected with BrdU before being killed. Shown are representative histograms of anti-BrdU staining gated on the LT-HSCs, as defined previously. (C) Flow cytometry plots of annexin V and 7-amino-actinomycin D gated on the LSK fraction of control and Meis1-deleted mice. (D) Meis1-deleted and control mice were treated with weekly doses of 5-FU. Graph shows the percentage survival (vertical axis) over time (horizontal axis) with the horizontal-axis labels representing the dates of 5-FU injection.
