L-leucine administration improves the anemia in Rps19-deficient mice. (A) Experimental strategy to test the effect of L-leucine in vivo: Rps19 deficiency was induced by feeding transgenic mice with doxycycline-containing food pellets (200 mg/kg), whereas L-leucine was simultaneously supplied in the drinking water (1.5% weight/volume). (B) Quantitative real-time PCR analysis of Rps19 in erythroid (preCFU-E/CFU-E) and myeloid (preGM/GMP) hematopoietic progenitors 14 days after doxycycline and L-leucine administration (n = 5, 11, and 10 for control, [D/D], and [D/D] + L-leucine, respectively). (C) Erythrocyte number, hemoglobin concentration, mean corpuscular volume (MCV), and reticulocyte number on day 14 (n = 12, 10, 38, and 34 for control, control + L-leucine, [D/D], and [D/D] + L-leucine, respectively). (D) Bone marrow cellularity (n = 17, 25, and 28 for control, [D/D], and [D/D] + L-leucine, respectively) and (E-F) hematopoietic stem and progenitor cell, and erythroblast frequencies on day 14 (n = 17, 16, and 18 for control, [D/D], and [D/D] + L-leucine, respectively). Error bars represent SD. HSC indicates hematopoietic stem cells; MkP, megakaryocyte progenitor; GMP, granulocyte-macrophage progenitor; CFU-E, colony-forming unit-erythroid; and EB, erythroblast.