Global transcriptome and chromatin occupancy analysis reveal the short isoform of GATA1 is deficient for erythroid specification and gene expression

Abstract

GATA1 is a master transcriptional regulator of the differentiation of several related myeloid blood cell types, including erythrocytes and megakaryocytes. Germ-line mutations that cause loss of full length GATA1, but allow for expression of the short isoform (GATA1s), are associated with defective erythropoiesis in a subset of patients with Diamond Blackfan Anemia. Despite extensive studies of GATA1s in megakaryopoiesis, the mechanism by which GATA1s fails to support normal erythropoiesis is not understood. In this study, we used global gene expression and chromatin occupancy analysis to compare the transcriptional activity of GATA1s to GATA1. We discovered that compared to GATA1, GATA1s is less able to activate the erythroid gene expression program and terminal differentiation in cells with dual erythroid-megakaryocytic differentiation potential. Moreover, we found that GATA1s bound to many of its erythroid-specific target genes less efficiently than full length GATA1. These results suggest that the impaired ability of GATA1s to promote erythropoiesis in DBA may be caused by failure to occupy erythroid-specific gene regulatory elements. Global transcriptome and chromatin occupancy analysis reveal the short isoform of GATA1 is deficient for erythroid specification and gene expression ABSTRACT MethodsCell culture G1ME cells were maintained in 1% THPO-conditioned media or in media containing THPO, SCF and EPO, as described. 3 Retroviral transduction and constructsRetroviral supernatant was prepared and applied to cells, as previously described.32 MigR1 constructs containing HA-tagged GATA1 and GATA1s have been described previously.

The DEK Oncoprotein Is a Critical Component of the EKLF/KLF1 Enhancer in Erythroid Cells

“…We have previously proposed that Gata2 is required for EKLF's initial activation, which is then activated to higher levels once Gata1 is fully induced by Gata2 (15). An intact Gata1 protein is required for full activation of EKLF, as Gata1s is deficient (95). The requirement of the BMP4 pathway for Gata1 expression suggests a coherent type 1 feed-forward mechanism on EKLF induction between BMP4/Smad5 and Gata1 once Gata1 is induced by Gata2 (96,97).…”

GATA factor transcriptional activity: Insights from genome‐wide binding profiles

“…Mutations that lead to the expression of the GATA1s isoform are also observed in some patients with Diamond‐Blackfan anemia—a bone marrow failure syndrome characterized by macrocytic anemia . Genome‐wide studies have shown that GATA1s binding is impaired at erythroid target genes but not at megakaryocytic target genes …”

GATA1 insufficiencies in primary myelofibrosis and other hematopoietic disorders: consequences for therapy

“…Comparison of chromatin binding signatures of GATA1 and GATA1s revealed that while GATA1s bound megakaryocytic genes normally, it bound many of its erythroid targets less efficiently than full-length GATA1 [21,22]. …”

“…This class of mutations results in exclusive production of a NH-terminally deleted isoform of GATA1 known as GATA1s [20]. With respect to the DBA phenotype, studies have shown that Gata1s fails to occupy chromatin of erythroid target genes to the same extent as the full-length protein, likely explaining the erythroid defect [21,22]. By contrast, the mechanism by which GATA1s causing mutations contribute to DS-AMKL is unknown.…”