GATA-1-dependent transcriptional repression of GATA-2 via disruption of positive autoregulation and domain-wide chromatin remodeling

Abstract

Interplay among GATA transcription factors is an important determinant of cell fate during hematopoiesis. Although GATA-2 regulates hematopoietic stem cell function, mechanisms controlling GATA-2 expression are undefined. Of particular interest is the repression of GATA-2, because sustained GATA-2 expression in hematopoietic stem and progenitor cells alters hematopoiesis. GATA-2 transcription is derepressed in erythroid precursors lacking GATA-1, but the underlying mechanisms are unknown. Using chromatin immunoprecipitation analysis, we show that GATA-1 binds a highly restricted upstream region of the Ϸ70-kb GATA-2 domain, despite >80 GATA sites throughout the domain. GATA-2 also binds this region in the absence of GATA-1. Genetic complementation studies in GATA-1-null cells showed that GATA-1 rapidly displaces GATA-2, which is coupled to transcriptional repression. GATA-1 also displaces CREB-binding protein (CBP), despite the fact that GATA-1 binds CBP in other contexts. Repression correlates with reduced histone acetylation domain-wide, but not altered methylation of histone H3 at lysine 4. The GATA factor-binding region exhibited cell-type-specific enhancer activity in transient transfection assays. We propose that GATA-1 instigates GATA-2 repression by means of disruption of positive autoregulation, followed by establishment of a domain-wide repressive chromatin structure. Such a mechanism is predicted to be critical for the control of hematopoiesis.

Differential sensitivities of transcription factor target genes underlie cell type-specific gene expression profiles

“…To establish whether differential chromatin access underlies the distinct sensitivities, the ER-GATA-1 level͞activity was titrated with 5, 10, or 40 nM ␤-estradiol for 16 h, and chromatin occupancy was measured at sites defined previously (13,14,20,22,28,(43)(44)(45). ER-GATA-1 occupied ␤-globin HSs1-4 maximally and the ␤major promoter nearly maximally in 10 nM ␤-estradiol-treated cells ( Fig.…”

“…ER-GATA-1(⌬N) activated ␣-globin, Ahsp, and Alas2 Ͻ4-fold lower than with ER-GATA-1. ER-GATA-1(⌬N) repressed Gata2 (20) and c-Kit (47) 3.5-fold and 2.6-fold lower, respectively, vs. ER-GATA-1. ER-GATA-1(⌬N) was almost completely defective in activating Tac-2.…”

“…At the Gata2 and ␣-globin loci, GATA-1 and GATA-2 have common and unique target sites. GATA-2 occupies sites 3.9, 2.8, and 1.8 kb upstream of the active Gata2 1S promoter (20,21). GATA-1-induced Gata2 repression involves ''GATA switches'' in which GATA-1 replaces GATA-2 at Ϫ3.9-and Ϫ2.8-kb regions.…”

Tumor necrosis factor alpha-mediated inhibition of erythropoiesis involves GATA-1/GATA-2 balance impairment and PU.1 over-expression

“…In erythropoiesis, the GATA-1 and GATA-2 transcription factors have essential roles, and a quantitative balance in their protein levels is required to achieve erythroid lineage development [51]. GATA-2 plays a role in early progenitor cell proliferation, and activates GATA-1 gene expression, which, conversely, silences GATA-2 expression in erythroid progenitors [52]. GATA-1 deficiency leads to death due to severe anemia [38], while GATA-2 deficiency leads to embryonic death [41].…”

Linking anemia to inflammation and cancer: The crucial role of TNFα

“…GATA-2 is overexpressed during early hematopoiesis resulting in maintenance of the renewal capacity of erythroid progenitor cells. Its expression is then progressively repressed by the increasing expression of GATA-1 [23]. NF-E2, is described to act as a major regulator of hemoglobin synthesis during erythropoiesis [24], and EKLF, as a crucial factor in erythroid and megakaryocytic differentiation and maturation [25,26] (Table 1).…”