Figure 2. Conditional Kmt2c deletion expands the HSC pool at the expense of HPCs.

(A) Overview of the conditional Kmt2c-flox allele.

(B) Western blot and genotyping PCR showing loss of MLL3 protein expression in Kmt2c^Δ/Δsplenocytes.

(C) Complementation testing of the Kmt2c null (exon 14) and Kmt2c^flox (exon 3) alleles, as measured by viable offspring after germline Kmt2c^flox deletion. Observed and expected allele frequencies were compared by the chi-square test. n = 35.

(D–H) HSC, HPC-1, pGM, and GMP numbers in 8-week-old mice of the indicated Kmt2c genotypes (two hindlimbs). n = 7–20.

(I) Peripheral blood CD45.2⁺ leukocyte chimerism after competitive whole bone marrow transplants. n = 10–13 per genotype from three independent donors.

(J) CD45.2⁺ HSC numbers in primary recipient bone marrow 16 weeks after transplantation.

(K) Twenty-four-hour BrdU incorporation in wild-type and Kmt2c^Δ/Δ HSCs. n = 5.

(L) Overview of H2B-GFP pulse-chase experiment.

(M) Representative histograms showing H2B-GFP signal in HSCs and HPCs after 14 weeks of doxycycline exposure.

(N) Percentages of H2B-GFP^High, H2B-GFP^Mid, and H2B-GFP^Low HSCs after a 14-week doxycycline chase. n = 6–11.

In all panels, error bars reflect standard deviation. *p < 0.05, **p < 0.01, ***p < 0.001; comparisons were made by two-tailed Student’s t test or one-way ANOVA with Holm-Sidak post hoc test (multiple comparisons). See also Figures S1 and S3.