Project description:The GATA2 transcription factor is a pivotal regulator of hematopoiesis. Disruptions in the GATA2 gene drive severe hematologic abnormalities and are associated with an increased risk of myelodysplastic syndromes and acute myeloid leukemia; however, the mechanisms underlying the pathophysiology of GATA2 deficiency remain still unclear. We developed two different mouse models that are based on serial and limiting donor cell transplantation of (aged) GATA2 haploinsufficient cells and mirror the symptoms of GATA2 deficiency. Similar to what has been observed in patients, our models show that GATA2 haploinsufficiency leads to B lymphopenia, monocytopenia, lethal bone marrow failure (BMF), myelodysplasia and lymphoblastic leukemia. Leukemia arises exclusively as a result of BMF, driven by somatic aberrations and accompanied by increased Myc target expression and genomic instability. These findings were confirmed in human GATA2+/- K562 cell lines showing defects in cytokinesis and are in line with the fact that monosomy 7 and trisomy 8 are frequent events in patients with MDS.
Project description:GATA2 deficiency is an autosomal dominant germline disorder of immune dysfunction and bone marrow failure with a high propensity for leukemic transformation in adolescents, present in up to 7% of pediatric myelodysplastic syndrome (MDS) and 15% of advanced MDS cases. While sequencing studies have identified several secondary mutations thought to contribute to malignancy, the mechanisms of disease progression have been difficult to identify due to a lack of disease-specific experimental models. Here, we generated a murine model of one of the most common GATA2 mutations associated with leukemic progression in GATA2 deficiency, Gata2R396Q/+. While mutant mice exhibit mild defects in peripheral blood output throughout life, they display significant hematopoietic abnormalities in the bone marrow (BM), including a reduction in hematopoietic stem cell (HSC) function and intrinsic biases toward specific stem cell subsets that differ from previous models of GATA2 loss. Supporting this observation, single-cell RNA sequencing of BM hematopoietic progenitors revealed a loss of HSC stemness, myeloid-bias, and accelerated ageing phenotype. Importantly, we show that Gata2R396Q/+ exerts effects early in hematopoietic development, as mutant mice generate fewer HSCs in the aorta gonad mesonephros, and fetal liver HSCs have reduced function. This reduced pool of HSCs and aged phenotype could be potential contributors to leukemic transformation in patients, and our model provides a useful tool to study the mechanisms of malignant transformation in GATA2 deficiency.
Project description:The Gata2 transcription factor is a pivotal regulator of hematopoietic stem cell (HSC) development and maintenance. Gata2 functions in the embryo during endothelial cell to hematopoietic cell transition (EHT) to affect hematopoietic cluster, HPC and HSC formation. Although previous studies of cell populations phenotypically enriched in HPCs and HSCs show expression of Gata2, there has been no direct study of Gata2 expressing cells during normal hematopoiesis. In this study we generate a Gata2 Venus reporter mouse model with unperturbed Gata2 expression to examine the hematopoietic function and transcriptome of Gata2 expressing and nonexpressing cells. Gata2Venus- HPCs 1 replicate, Gata2Venus+ HPCs 1 replicate
Project description:We generated homozygous GATA2 knockout human embryonic stem cells (GATA2-/- hESCs) and analyzed their blood differentiation potential. Paritcularly at the hemogenic endothelium (HE) stage and hematopoietic progenitor cell (HPC) stage. Our result revealed that GATA2-/- hESCs displayed attenuated generation of CD34+CD43+ HPCs, due to the impairment of endothelial to hematopoietic transition (EHT). However, GATA2-/- hESCs retained the potential to generate erythroblasts, macrophages, but never granulocytes. Through RNA-Seq and further rescue experiment, we further identified that SPI1 was responsible for the defect of GATA2-/- hESCs in generation of CD34+CD43+ HPCs and granulocytes.
Project description:The Gata2 transcription factor is a pivotal regulator of hematopoietic stem cell (HSC) development and maintenance. Gata2 functions in the embryo during endothelial cell to hematopoietic cell transition (EHT) to affect hematopoietic cluster, HPC and HSC formation. Although previous studies of cell populations phenotypically enriched in HPCs and HSCs show expression of Gata2, there has been no direct study of Gata2 expressing cells during normal hematopoiesis. In this study we generate a Gata2 Venus reporter mouse model with unperturbed Gata2 expression to examine the hematopoietic function and transcriptome of Gata2 expressing and nonexpressing cells.
Project description:Cell fate is established through coordinated gene expression programs in individual cells. Regulatory networks that include the Gata2 transcription factor play central roles in hematopoietic fate establishment. Whereas Gata2 is essential to the embryonic development and function of hematopoietic stem cells that form the adult hierarchy, little is known of the in vivo expression dynamics of Gata2 in single cells. Here we examine Gata2 expression in single aortic cells as they establish hematopoietic fate in Gata2Venus mouse embryos. Time-lapse imaging reveals rapid pulsatile level changes in Gata2 reporter expression in cells undergoing endothelial-to-hematopoietic-transition. Moreover, Gata2 reporter pulsatile expression is dramatically altered in Gata2+/- aortic cells, which undergo fewer transitions and are reduced in hematopoietic potential. Our novel finding of dynamic pulsatile expression of Gata2 suggests a highly unstable genetic state in single cells concomitant with their transition to hematopoietic fate. This reinforces the notion that threshold levels of Gata2 influence fate establishment and has implications for transcription factor-related hematologic dysfunctions.
Project description:The majority (72%) of adolescents with myelodysplastic syndrome and monosomy 7 carry an underlying GATA2 deficiency. Nowadays, chemotherapy and allogenic hematopoietic stem cell transplantation (HSCT) are the only cure, pointing out the urgent need to develop reliable predictive tools. Familial cases carrying the same mutation in the GATA2 gene develop the disease at different age. The trigger of the disease is still unknown. Therefore, it is needed to understand the genetic mechanisms (mutations) and epigenetic mechanism, such as, DNA methylation, a cellular mechanism to control gene expression. Abnormal DNA methylation has been linked to several adverse outcomes, including human diseases. In this study, we deeply characterized 20 Spanish GATA2 deficient patients; study the presence of secondary mutations, clinical phenotype and DNA methylation. We have found that the most frequent secondary mutations are in STAG2 and ASXL1 genes, detected in 30% and 20% of the patients, respectively, a similar ratio has been described in a bigger cohort, showing that our 20-patient cohort is representative of the GATA2 deficiency scenario. For the first time, we found a specific hypermethylated signature in GATA2 patients, opening a novel point of view in the GATA2-patient diagnostic and facilitating the risk estimation of themselves. Furthermore, whether the methylation profiling is accurate enough, it will be useful to predict the onset of the disease progression.