HSCs and CD41+ MK-HSCs are dysregulated in Runx1–/– mice and accompanied by thrombocytopenia. (A) Schematics of the mouse model of Runx1F/F;Mx1-Cre and Runx1 inducible deletion. (B) Western blotting of the knockout of RUNX1 protein in duplicate mice. (C) Genotyping of exon 4 deletion of Runx1 in Runx1F/F:Mx1-Cre mice. Triplet samples of Runx1F/F:Mx1-Cre (–/–) and Runx1F/F (F/F) are shown. (D) Peripheral blood counts of Runx1F/F;Mx1-Cre mice after pI:pC inductions. Statistics was performed using t test at 4 weeks post deletion between Runx1−/− and Runx1F/F mice. The x-axis indicates the weeks after the final pI:pC injection. (E) Quantification of flow cytometry analysis of MK-HSCs (LSKCD34−Flt3−CD150+CD41+) in the BM at 4 weeks after pI:pC injection. The y-axis is the percentage out of their parental population. (F) hematoxylin and eosin and anti-CD61 (a MK marker) staining of BM from Runx1−/− and Runx1F/F mice 4 weeks post pI:pC injections. The red arrows indicate MK cells. ∗∗∗P < .001 and ∗∗P < .01. ns, not significant.
