Figure 4.

DOT1L inactivation in the adult bone marrow leads to rapid depletion of myeloid progenitors, followed by decrease in the numbers of hematopoietic stem cells (A) (left) Bone marrow cellularity in Dot1l^f/f Mx-Cre- and Dot1l^f/f Mx-Cre+ mice 7 days post poly(I:C) induction (n = 21 mice/group, pooled from 5 independent experiments; mean +/- SEM). (right) Bone marrow cellularity decreases in Dot1l^f/f Mx-Cre+ mice 10 days post poly(I:C) induction. (n = 14–16 mice/group, pooled from 3 independent experiments; mean +/- SEM). (B) Western blot shows decreased H3K79me2 in total BM at day 7 (left) and day 10 (right); (C) Flow cytometric analysis quantification shows that Pre MegE progenitors (CD150⁺CD105^-CD16/32^-CD41^-LK) are significantly decreased as early as day 7 (left) and continue to be depleted by day 10 (right). (D) Quantification of flow cytometric analysis showing that granulocyte-macrophage progenitors (GMP) (CD16/32⁺CD150^-CD41^-LK) are significantly decreased as early as day 7 (left) and continue to decrease through day 10 (right). (E) Myeloid colony formation by wild-type vs Dot1l-null BM in CFU-GM assays (n = 8 mice/group with technical triplicates; mean +/- SEM; pooled from 2 experiments) showing a lack of colony formation potential in Dot1l ^Δ/Δ mice in comparison to Dot1l WT. (F–H) Profound decrease in LT-HSC, CD11b⁺Gr1⁺ BM myeloid cells, and B220⁺ CD19⁺B cells at day 10 post poly (I:C). (ns p > 0.05, * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001, **** p ≤ 0.0001).