Epigenetic dysregulation of GATA1 is involved in myelodysplastic syndromes dyserythropoiesis

Abstract

Myelodysplastic syndromes (MDS) are characterized by dyserythropoiesis resulting in anemia. This pathological hallmark is incompletely understood. Notch signaling has been linked to impaired erythropoietic and megakaryopoietic development of CD34+ progenitor cells, but its role in MDS is unclear. We have analyzed the transcriptional activity of Notch pathway elements and its association with the key erythroid factor globin transcription factor 1 (GATA1) and the apoptosis regulatory gene B-cell lymphoma-xl (BCLxl) in MDS. The methylation of GATA1 erythroid promoter CpG dinucleotides flanking cis-regulatory elements, including an N-box suppressor binding site for HES1 and a GATA-box binding site, was examined in normal and MDS erythropoiesis. We have generated a kinetic in vitro model of MDS erythropoiesis using CD34+ bone marrow cells from healthy donors (n = 7) and patients with MDS (low risk: RA/n = 6, RARS/n = 3; high risk: RAEB/n = 4, RAEB-T/n = 2). RNA expression of GATA1, BCLxl, DLK1, Notch1, HES1, and HERP2 was measured by real-time RT-PCR (qPCR). DNA methylation at seven CpG dinucleotides of the GATA1 gene promoter was quantitatively analyzed by pyrosequencing of bisulfite-treated genomic DNA at any specific time point. For the Notch pathway elements, no conclusive expression differences were found between MDS and normal erythropoiesis. But we found steadily up-regulated RNA expression of GATA1 and of BCLxl during late normal erythropoietic differentiation. In contrast, during MDS, erythropoiesis a loss of typical up-regulation of GATA1 and BCLxl was observed. Hypermethylation of CpG dinucleotides flanking the repressor HES1 binding site within the 5' region of GATA1 was detected particularly during late MDS erythropoiesis. Interestingly, decremental GATA1 promotor methylation values were seen during normal erythropoiesis matching GATA1 RNA up-regulation. Our data show that the critical erythropoietic transcription factor GATA1 as well as the antiapoptotic molecule BCLxl fails to be normally up-regulated during MDS erythropoiesis. The higher residual 5'-GATA1 methylation values in MDS erythropoiesis but decremental loss thereof in normal erythropoiesis suggest a gene dose effect for GATA1 during erythropoiesis being finely tuned by CpG methylation. Its dysregulation may contribute to the ineffective erythropoiesis observed in MDS.

TET2 Plays an Essential Role in Erythropoiesis by Regulating Lineage-Specific Genes via DNA Oxidative Demethylation in a Zebrafish Model

“…These results preliminarily suggest that zTET2-mediated oxidative demethylation in gata-1 regulates the differentiation of erythroid precursors, and dysregulation of this oxidative demethylation may result in the occurrence of dyserythropoiesis and anemia seen in MDS. This suggestion shows overall consistency with recent observations that dysregulation of CpG methylation at the gata-1 promoter contributes to ineffective erythropoiesis in MDS (65). This study provides new insights showing that the deletion of TET2 induced the dysregulation of CpG methylation at the gata-1 promoter and that it should be one of the potential ϩ progenitors were strongly enriched in the ICM at 22 hpf (1) and decreased at 36 hpf (3) in control morphants as the progenitors entered circulation.…”

Acute Myeloid Leukemia (AML) with Erythroid Predominance Exhibits Clinical and Molecular Characteristics that Differ from Other Types of AML

“…In MDS, although not entirely clear, the possible mechanisms involved in ineffective erythropoiesis may be related to mutations or epigenetic dysregulation of a number of important genes, such as GAT1, RSP14, EVI1 and TEL [23], [24], [25]. These molecular genetic alterations affect mitochondrial ferritin expression and iron distribution, leading to insensitivity to erythropoietin, increased apoptosis and proliferation, and defective erythroid differentiation.…”

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

“…Other GATA1 mutants are associated with poor recruitment of the TAL1/LMO2 complex . Mutations leading to the exclusive production of a short GATA1 protein isoform lacking the N‐terminus (GATA1s) are associated with myeloproliferative disorders and acute megakaryocytic leukemia in children with Down syndrome or with impaired erythropoiesis . 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 .…”