Prmt1 KO phenocopies the hematopoietic defects associated with dKO. (A) Negative enrichment in arginine methyltransferase activity in isolated dKO LSKs. (B) Independent qPCR validation of Prmt1 expression in indicated LSKs. Data represent 2 independent experiments. (C) Co-occupancy of HOXA9 and β-CATENIN at the Prmt1 transcription start site detected by CUT&RUN-sequencing in HSPCs. (D) Chromatin accessibility at the Prmt1 locus visualized by ATAC-sequencing of LSKs. (E) Percentage of donor cells in bone marrow of transplanted mice at indicated time points. Absolute number of HSPCs at 4-week (F), 8-week (G), and 12-week (H) harvests (n = 3 mice per group per time point). (I) LTC-IC frequency of HSPCs isolated from mice that received transplant. Prmt1^fl/fl mice treated with corn oil (vehicle) are indicated as WT control. ∗P ≤ .05; ∗∗P ≤ .01; ∗∗∗P ≤ .001; NS, P > .05. qPCR, quantitative polymerase chain reaction.