Fig 2: Long-term disruption of the SDF-1/CXCR4 axis diminishes numbers of erythroblasts, and this is correlated with GATA-1 expression. B6 mice were injected with PBS or 5 mg/kg of AMD3100 for 21 consecutive days. Levels of (A) circulating platelets, (B) WBC, and (C) RBC, as well as (D) number of BM MP cells and (E) their GATA-1 expression (fold change of MFI) were determined (n = 8). B6 mice were also administered with the indicated concentrations of AMD3100 for 21 consecutive days. (F) Numbers of BM-conserved erythroblasts at 4 stages and (G) GATA-1 expression (MFI) in these cells were analyzed (n = 8). Data represent mean ± S.D. *P < 0.05; **P < 0.01 vs. the PBS controls by unpaired Student’s t-test.

Fig 3: Transgenic overexpression of COMP-Ang1 inhibits the expression of GATA-1, but not GATA-2, in MP cells, and is not directly associated with HSC senescence. Flow cytometric results showing GATA-1-positive MP cells (MFI) in (A) BM and (B) spleen of transgenic mice and their littermate controls (n = 8). GATA-2-positive MP cells (MFI) in (C) BM and (D) spleen of transgenic mice and littermate controls (n = 5). BM-derived MP cells (%) positive for (E) Annexin V/PI or (F) CXCR4 in transgenic mice and littermate controls (n = 5). G BM-conserved lineage-negative cells (1 × 106 cells) isolated from transgenic mice or their littermate controls (CD45.2) were transplanted into irradiated recipient mice (CD45.1). GATA-1 expression (MFI) in BM-conserved MP cells and level of circulating platelets in recipients transplanted with cells derived from (H) K14-Cre;c-Ang1 or (I) Col2.3-Cre;c-Ang1 mice were compared with those from their littermate controls at 5 months post-transplantation (n = 7). Data represent mean ± S.D. **P < 0.01 vs. the controls by unpaired Student’s t-test.