Belele, C.L., English, M.A., Chahal, J., Burnetti, A., Finckbeiner, S.M., Gibney, G., Kirby, M., Sood, R., and Liu, P. (2009) Differential requirement for Gata1 DNA binding and transactivation between primitive and definitive stages of hematopoiesis in zebrafish. Blood. 114(25):5162-5172.
The transcription factor Gata1 is required for the development of erythrocytes and megakaryocytes. Previous studies with a complementation rescue approach showed that the zinc finger domains are required for both primitive and definitive hematopoiesis. Here we report a novel zebrafish gata1 mutant with an ENU-induced point mutation in the C-finger (gata1(T301K)). The Gata1 protein with this mutation bound to its DNA target sequence with reduced affinity and transactivated inefficiently in a reporter assay. gata1(T301K/T301K) fish had decreased number of erythrocytes during primitive hematopoiesis but normal adult hematopoiesis. We crossed the gata1(T301K/T301K) fish with those carrying the R339X mutation, also known as vlad tepes (vlt), which abolishes DNA binding and transactivation activities. As we reported before, gata1(vlt/vlt) embryos were "bloodless" and died around 11-15 days post fertilization (dpf). Interestingly, the gata1(T301K/vlt) fish had nearly complete block of primitive hematopoiesis, but they resumed hematopoiesis between 7-14 dpf and grew to phenotypically normal fish with normal adult hematopoiesis. Our findings suggest that the impact of Gata1 on hematopoiesis correlates with its DNA-binding ability and that primitive hematopoiesis is more sensitive to reduction in Gata1 function than definitive hematopoiesis.