Mutation of Gdf15 alters the expression of metabolic enzymes during stress erythropoiesis. (A) Five × 10⁵ bone marrow cells of WT or Gdf15^−/− were transplanted to lethally irradiated WT recipients. Relative expression levels of Hif1α, Pdk1, Pdk3, Glut1, and Gls1 at indicated time points are plotted in a base-10 logarithmic scale. (B) WT and Gdf15^−/− bone marrow cells were cultured in expansion media for 7 days. Stress erythroid progenitors were collected and analyzed with qRT-PCR. Relative expression levels of Hif1α, Pdk1, Pdk3, Glut1, and Gls1 are shown. (C) qRT-PCR analysis of Hif1α, Pdk1, Pdk3, Glut1, and Gls1 relative expression levels in control and mutant progenitors cultured on control or mutant stroma as indicated (see Figure 5F-G for description). Paired Student t test was performed to evaluate differences in gene expression levels. (D-E) Gdf15^−/− bone marrow cells were cultured in vitro with or without 2 mM glutamate supplementation. (D) Flow cytometry analysis of (left) Kit⁺Sca1⁺ progenitor cells, (middle) percentage, and (right) absolute number of CD133^negKit⁺Sca1⁺ SEPs are shown. (E) Analysis of stress BFU-E colony formation assay in hypoxia (2% O₂). Data are shown as individual subject and the mean ± SEM. *P < .05, **P < .01, and ***P < .001.