Identification and characterization of two types of erythroid progenitors that express GATA-1 at distinct levels Running heads: GATA-1 expression in erythroid progenitors Category: Hematopoiesis

Transcription factor GATA-1 is essential for the development of the erythroid lineage. To ascertain whether strict control of GATA-1 expression level is necessary for achieving proper erythropoiesis, we established transgenic mouse lines expressing green fluorescent protein (GFP) under the control of the GATA-1 gene hematopoietic regulatory domain. We examined the GATA-1 expression level by exploiting the transgenic mice and found two GFP-positive hematopoietic progenitor fractions in the bone marrow. One is the GFP fraction containing mainly CFU-E and proerythroblasts, which coexpress transferrin receptor, while the other is the GFP/transferrin receptor-negative fraction containing BFU-E. Since the intensity of green fluorescence correlates well with the expression level of GATA-1, these results indicate that GATA-1 is highly expressed in CFU-E, but low in BFU-E, suggesting that the incremental expression of GATA-1 is required for the formation of erythroid progenitors. We also examined GFP-positive fractions in the transgenic mouse spleen and fetal liver, and identified fractions containing BFU-E and CFU-E, respectively. This study also presents an efficient method for enriching the CFU-E and BFU-E from mouse hematopoietic tissues. (E-mail, [email protected]) 2 For personal use only. on April 13, 2017. by guest www.bloodjournal.org From