The role of the N-terminus of GATA1 in erythropoiesis

PROJECT SUMMARY The zinc finger transcription factor GATA1 is essential for development of a subset of hematopoietic lineages, including erythroid cells and megakaryocytes. Inherited mutations in GATA1 are associated with a spectrum of hematopoietic disorders including dyserythropoietic anemia and thrombocytopenia, caused by mutations in the N-terminal zinc finger, Diamond Blackfan Anemia (DBA), caused by mutations that lead to loss of the N-terminal transactivation domain, and hemolytic anemia caused by mutations in an intrinsically disordered region. The focus of this proposal is on understanding the consequences of loss of the N-terminal transactivation domain on red cell development. The isoform that lacks the N-terminus is named GATA1 short, or GATA1s. Mice that mimic these human mutations, Gata1s mice, display prominent defects in erythropoiesis in utero and a lifelong macrocytic anemia that has some similarities to DBA. In our published and preliminary studies, we have found that GATA1s binds chromatin to a similar extent as full length GATA1 but fails to lead to proper chromatin accessibility or histone modifications. We hypothesize that the absence of key protein-protein interactions between GATA1s and chromatin regulators such as SWI/SNF and NuRD complexes, leads to impaired gene regulation. We performed single cell RNA-sequencing of E13.5 Gata1s fetal livers and identified prominent changes in the erythroid lineage including relative increases in proerythroblasts and basophilic erythroblasts with concomitant decreases in the polychromatic and orthochromatic stages. Within the basophilic and polychromatic stages, we observed enrichment of pathways that control metabolism, including oxidative phosphorylation, in the Gata1s mutant cells. We hypothesize that metabolic defects resulting from aberrant gene regulation by GATA1s contributes to the defect in red cell maturation in mouse models and patients. In this grant, we propose to: 1) Identify the cofactors that are recruited by the N-terminus to regulate erythropoiesis; and 2) Investigate the role of the N-terminus in controlling erythroid gene expression and metabolism. These innovative studies will increase our understand of how the N-terminus regulates transcription, metabolism, and erythroid maturation and may shed light on strategies to improve erythropoiesis in DBA and other congenital anemias.