Analysis of GATA transcription factors functions on development and differentiation of hematopoietic cells.

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1) Functonal analyses of GATA transcription factoers in vivo. GATA-1 germline mutation in mice results in embryoniclethality due to defective erythroid cell maturation, and thus other hematopoietic GATA factors do not compensate for the loss of GATA-1. To determine whether GATA-1's obligate presence in erythroid cellsis due to its distinct biochemical properties or spatiotemporal patterning, we attempted to rescue GATA-1 mutant mice with hematopoietic GATA factor cDNAs placed under the transcriptional control of the GATA-1 gene. We found that transgenic expression of a GATA-1 cDNA fully abrogated the GATA-1-deficient phenotype. Surprisingly, GATA-2 and GATA-3 factors expressed from the same regulatory cassette also rescued the embryoniclethal phenotype of the GATA-1 mutation. These results demonstrate that the transcriptional control dictating proper GATA-1 accumulation is the most critical determinant of GATA-1 activity during erythropoiesis.2) Domain analysis of GATA-1 in vivo. Linea … More ge-specific transgenic rescue of the germ line GATA-1 mutant revealed novel properties od specific domains of GATA-1 that are not revealed by cell culture models. The N-terminal and N-finger domains confer complementing but clearly distingulsihable properties to GATA-1 function in vivo.3) Transcriptional regulation of GATA factors. To define the boundaries of the GATA-1 gene hematopoieticenhancer(G1HE), a series of deletion constructs was prepared and tested in transfection and transgenic mice analyses. The results clearly indicated that a strong GATA-1 gene regulatory activity in both primitive and definitive erythroid cell exists in a 149 bp core region with in G1HE, while that in megakaryocyte exists in more wide region of G1HE.This 149 bp core region contains one GATA, one GAT and one E-box. Mutational analyses revealed that only the GATA box is critical for gene regulatory activity. Thus these results demonstrate the presence of a network of GATA factors for GATA-1 gene expression and G1HE consist of two elements which determine erythroid or megakaryocyte lineage specificity. Less