Brg is dispensable for LT-HSC maintenance but is required for the full proliferative activity of LT-HSCs and downstream progenitors. (A) Schematic of transplant strategy used to achieve bone-marrow-specific deletion of Brg using a Mx1-Cre transgene. Donor and recipient bone marrow is distinguished by the expression of different alleles of the cell-surface marker Ly5. (B) Frequency of donor-derived (Ly5.2⁺) LT-HSCs in polyI:polyC (pIpC)-treated Mx1-Cre⁺;Brg^fl/fl and control hematopoietic chimeras as analyzed 16 weeks (primary) and 12 weeks (secondary) after transplantation. Representative fluorescence-activated cell sorter (FACS) profiles are shown (left). LT-HSCs were CD34^- Flk2^- Sca1⁺ Lin^- c-kit⁺. (C) Donor bone marrow containing the H2k-Bcl2 transgene show a similar impairment in LT-HSC to short-term hematopoietic stem cell (ST-HSC) transition after Brg deletion 16 weeks (primary) and 12 weeks (secondary) post-pIpC treatment. Representative FACS profiles are shown. (D) Donor (Ly5.2) versus host (Ly5.1) chimerism of bone marrow HSC and progenitor populations 18 weeks after pIpC-induced deletion of Brg (upper panel) or mock treatment (lower panel) (n = 5 to 6 mice per group). CLP, common lymphoid progenitor; CMP, common myeloid progenitor; DN, double negative; DP, double positive; Fr, fraction; GMP, granulocyte-macrophage progenitor; LT-HSC, long-term hemopoietic stem cells; MEP, megakaryocyte-erythrocyte progenitor; MPP, multipotent progenitor; NS, nonsignificant. See also supplemental Figures 8-10.