Fig. 1: Abnormal ETD in the absence of EpoR signaling.
From: EpoR stimulates rapid cycling and larger red cells during mouse and human erythropoiesis
a Experimental design. E12.5 Epor−/− fetal livers were transduced with bicistronic retroviral vectors encoding either Bcl-xL or EpoR, linked by an internal ribosomal entry site (IRES) to human CD4 (hCD4) or GFP reporters. Transduced cells differentiated in vitro into red cells over the ensuing 72 h. b Epor−/− CFU-e colonies, scored 48 h following transduction with either EpoR or Bcl-xL. Epo was added to the medium where indicated. Epor−/− fetal liver cells were also transduced with retroviral vectors encoding the following: ‘empty’ vector (‘V’), constitutively active Stat5 (Stat5 1*6), or doubly transduced with both Bcl-xL and Stat5 1*6. Data pooled from 3 independent experiments. Data are means ± SD. Only CFU-e colonies of a size comparable to those of wild-type colonies were scored. c Representative colonies from an experiment as in (b). d Colony area occupied by each of 75 colonies for each genotype (EpoR-Epor−/− or Bcl-xL-Epor−/−). Data pooled from 3 independent experiments as in (b). Two-sided t test, unequal variance. e Cytospin preparations of transduced Epor−/− fetal liver cells cultured in liquid medium for 36 h, in the presence or absence of Epo as indicated. Cells were stained for hemoglobin with diaminobenzidine (brown stain, arrowheads) and counter-stained with Giemsa. Representative of 4 independent experiments. Double-headed arrows point at enucleated red cells; arrows point at pyrenocytes (extruded nuclei). The micrograph in the bottom panel is representative of cultures both in the presence or absence of Epo. f, g Flow-cytometric CD71/Ter119 profiles of freshly harvested Epor−/− and wild-type littermate fetal livers (f), and of Epor−/− fetal liver cells 18 and 36 h post transduction and culture in Epo-containing medium (g).
