BMP4, SCF, and hypoxia cooperatively regulate the expansion of murine stress erythroid progenitors. Journal   Blood. Citation   Blood. 109(10):4494-502 Publication date   2007 May 15 Authors   Perry JM Harandi OF Paulson RF Investigators   Robert Paulson Grant agencies   National Heart, Lung, and Blood Institute Grants   NHLBI R01 HL70720 MeSH headings   Bone Morphogenetic Proteins Cell Hypoxia Cell Proliferation Erythroid Progenitor Cells Stem Cell Factor MeSH qualifiers   physiology cytology Abstract   The erythroid response to acute anemia relies on the rapid expansion in the spleen of a specialized population of erythroid progenitors termed stress BFU-E. This expansion requires BMP4/Madh5-dependent signaling in vivo; however, in vitro, BMP4 alone cannot recapitulate the expansion of stress BFU-E observed in vivo, which suggests that other signals are required. In this report we show that mutation of the Kit receptor results in a severe defect in the expansion of stress BFU-E, indicating a role for the Kit/SCF signaling pathway in stress erythropoiesis. In vitro analysis showed that BMP4 and SCF are necessary for the expansion of stress BFU-E, but only when spleen cells were cultured in BMP4 + SCF at low-oxygen concentrations did we recapitulate the expansion of stress BFU-E observed in vivo. Culturing spleen cells in BMP4, SCF under hypoxic conditions resulted in the preferential expansion of erythroid progenitors characterized by the expression of Kit, CD71, and TER119. This expression pattern is also seen in stress erythroid progenitors isolated from patients with sickle cell anemia and patients with beta-thalassemia. Taken together these data demonstrate that SCF and hypoxia synergize with BMP4 to promote the expansion and differentiation of stress BFU-E during the recovery from acute anemia.