RESUMEN

GATA1 is a highly conserved hematopoietic transcription factor (TF), essential for normal erythropoiesis and megakaryopoiesis, that encodes a full-length, predominant isoform and an amino (N) terminus-truncated isoform GATA1s. It is consistently expressed throughout megakaryocyte development and interacts with its target genes either independently or in association with binding partners such as FOG1 (friend of GATA1). While the N-terminus and zinc finger have classically been demonstrated to be necessary for the normal regulation of platelet-specific genes, murine models, cell-line studies, and human case reports indicate that the carboxy-terminal activation domain and zinc finger also play key roles in precisely controlling megakaryocyte growth, proliferation, and maturation. Murine models have shown that disruptions to GATA1 increase the proliferation of immature megakaryocytes with abnormal architecture and impaired terminal differentiation into platelets. In humans, germline GATA1 mutations result in variable cytopenias, including macrothrombocytopenia with abnormal platelet aggregation and excessive bleeding tendencies, while acquired GATA1s mutations in individuals with trisomy 21 (T21) result in transient abnormal myelopoiesis (TAM) and myeloid leukemia of Down syndrome (ML-DS) arising from a megakaryocyte-erythroid progenitor (MEP). Taken together, GATA1 plays a key role in regulating megakaryocyte differentiation, maturation, and proliferative capacity. As sequencing and proteomic technologies expand, additional GATA1 mutations and regulatory mechanisms contributing to human diseases of megakaryocytes and platelets are likely to be revealed.

Asunto(s)

Plaquetas , Factor de Transcripción GATA1 , Megacariocitos , Trombopoyesis , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Humanos , Animales , Plaquetas/metabolismo , Trombopoyesis/genética , Megacariocitos/metabolismo , Megacariocitos/citología , Mutación , Trombocitopenia/genética , Trombocitopenia/patología , Trombocitopenia/metabolismo , Diferenciación Celular/genética , Ratones

RESUMEN

Studies conducted on animal models have identified several therapeutic targets for myelofibrosis, the most severe of the myeloproliferative neoplasms. Unfortunately, many of the drugs which were effective in pre-clinical settings had modest efficacy when tested in the clinic. This discrepancy suggests that treatment for this disease requires combination therapies. To rationalize possible combinations, the efficacy in the Gata1low model of drugs currently used for these patients (the JAK1/2 inhibitor Ruxolitinib) was compared with that of drugs targeting other abnormalities, such as p27kip1 (Aplidin), TGF-ß (SB431542, inhibiting ALK5 downstream to transforming growth factor beta (TGF-ß) signaling and TGF-ß trap AVID200), P-selectin (RB40.34), and CXCL1 (Reparixin, inhibiting the CXCL1 receptors CXCR1/2). The comparison was carried out by expressing the endpoints, which had either already been published or had been retrospectively obtained for this study, as the fold change of the values in the corresponding vehicles. In this model, only Ruxolitinib was found to decrease spleen size, only Aplidin and SB431542/AVID200 increased platelet counts, and with the exception of AVID200, all the inhibitors reduced fibrosis and microvessel density. The greatest effects were exerted by Reparixin, which also reduced TGF-ß content. None of the drugs reduced osteopetrosis. These results suggest that future therapies for myelofibrosis should consider combining JAK1/2 inhibitors with drugs targeting hematopoietic stem cells (p27Kip1) or the pro-inflammatory milieu (TGF-ß or CXCL1).

Asunto(s)

Janus Quinasa 1 , Selectina-P , Mielofibrosis Primaria , Pirimidinas , Receptores de Interleucina-8B , Factor de Crecimiento Transformador beta , Mielofibrosis Primaria/tratamiento farmacológico , Mielofibrosis Primaria/metabolismo , Mielofibrosis Primaria/patología , Factor de Crecimiento Transformador beta/metabolismo , Animales , Janus Quinasa 1/antagonistas & inhibidores , Janus Quinasa 1/metabolismo , Selectina-P/metabolismo , Receptores de Interleucina-8B/antagonistas & inhibidores , Receptores de Interleucina-8B/metabolismo , Pirimidinas/farmacología , Pirimidinas/uso terapéutico , Receptores de Interleucina-8A/antagonistas & inhibidores , Receptores de Interleucina-8A/metabolismo , Ratones , Janus Quinasa 2/metabolismo , Janus Quinasa 2/antagonistas & inhibidores , Nitrilos/uso terapéutico , Nitrilos/farmacología , Modelos Animales de Enfermedad , Quimioterapia Combinada , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA1/genética , Pirazoles/farmacología , Pirazoles/uso terapéutico , Humanos

RESUMEN

BACKGROUND: GATA1-related cytopenia (GRC) is characterized by thrombocytopaenia and/or anaemia ranging from mild to severe. Haematopoietic stem cell transplantation (HSCT) is a healing therapeutic choice for GRC patients. We identified a novel pathogenic variant (GATA1: c.1019delG) in a boy with GATA1-related cytopenia. Then we performed preimplantation genetic testing (PGT) in this GRC family. After a mosaic embryo transfered, a healthy and HLA-compatible with the proband baby was delivered. CASE PRESENTATION: The proband is a 6-year-old boy who was diagnosed to have transfusion-dependent anaemia since 3 year old. Whole-exome sequencing (WES) showed that the proband has a hemizygous variant c.1019delG in GATA1, which is inherited from his mother. His parents decided to undergo PGT to have a health and HLA-compatible offspring. After whole genome amplification (WGA) of biopsied trophectoderm (TE) cells, next generation sequencing (NGS)-based PGT was preformed to analyse embryos on chromosomal aneuploidy, target mutation and HLA typing. There were 3 embryos HLA-matched to the proband. The genotypes of the 3 embryos were heterozygous variant, hemizygous variant, normal respectively. After a heterozygous, mosaic partial trisomy (chr)16, and HLA-matched embryo transfer, a healthy baby was delivered and whose HSCT is compatible with the proband. CONCLUSIONS: NGS-based PGT-HLA is a valuable procedure for the treatment of GATA1-related cytopenia caused by GATA1 variants, or other haematological disorders, oncological and immunological diseases. Furthermore, our study reconfirms that mosaic embryos transfer would bring healthy offspring.

Asunto(s)

Transferencia de Embrión , Factor de Transcripción GATA1 , Nacimiento Vivo , Mosaicismo , Diagnóstico Preimplantación , Niño , Femenino , Humanos , Masculino , Embarazo , Factor de Transcripción GATA1/genética , Pruebas Genéticas , Prueba de Histocompatibilidad , Nacimiento Vivo/genética , Preescolar

RESUMEN

Transcriptional mechanisms establish and maintain complex genetic and protein networks to control cell state transitions. The hematopoietic transcription factor GATA1 is a master regulator of erythropoiesis and megakaryopoiesis, and human GATA1 genetic variants cause anemia and megakaryoblastic leukemia. Multiomic analyses revealed that GATA1 controls expression of transporters and metabolic enzymes that dictate intracellular levels of endogenous small molecules, including heme, metal ions, and sphingolipids. Besides its canonical function as a hemoglobin component, heme facilitates or antagonizes GATA1 function to regulate erythropoiesis via mechanisms dependent or independent of the heme-binding transcription factor BTB domain and CNC homology 1 (BACH1). GATA1 regulates the expression of genes encoding heme biosynthetic enzymes and BACH1. GATA1 maintains homeostasis of bioactive ceramides during erythroid differentiation by regulating genes encoding sphingolipid metabolic enzymes. Disrupting ceramide homeostasis impairs critical cytokine signaling and is detrimental to erythroid cells. During erythroid maturation, GATA1 induces a zinc transporter switch that favors export versus import, thus dictating the intracellular zinc level, erythroblast survival, and differentiation. In aggregate, these studies support an emerging paradigm in which GATA factor-dependent transcriptional mechanisms control the intracellular levels of endogenous small molecules and small molecule-dependent feedback loops that serve as vital effectors of transcription factor activity, genome function, and cell state transitions.

Asunto(s)

Eritropoyesis , Humanos , Eritropoyesis/genética , Animales , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA1/genética , Factores de Transcripción GATA/metabolismo , Factores de Transcripción GATA/genética , Regulación de la Expresión Génica , Hemo/metabolismo , Hemo/biosíntesis , Diferenciación Celular

RESUMEN

In previous work, we found that PC was differentially expressed in cows at different lactation stages. Thus, we deemed that PC may be a candidate gene affecting milk production traits in dairy cattle. In this study, we found the polymorphisms of PC by resequencing and verified their genetic associations with milk production traits by using an animal model in a cattle population. In total, we detected six single-nucleotide polymorphisms (SNPs) in PC. The single marker association analysis showed that all SNPs were significantly associated with the five milk production traits (p < 0.05). Additionally, we predicted that allele G of 29:g.44965658 in the 5' regulatory region created binding sites for TF GATA1 and verified that this allele inhibited the transcriptional activity of PC by the dual-luciferase reporter assay. In conclusion, we proved that PC had a prominent genetic effect on milk production traits, and six SNPs with prominent genetic effects could be used as markers for genomic selection (GS) in dairy cattle, which is beneficial for accelerating the improvement in milk yield and quality in Chinese Holstein cows.

Asunto(s)

Lactancia , Leche , Polimorfismo de Nucleótido Simple , Animales , Bovinos/genética , Femenino , Leche/metabolismo , Lactancia/genética , Factor de Transcripción GATA1/genética , Alelos

RESUMEN

KLF transcription factor 1 (KLF1) and GATA binding protein 1 (GATA1) are transcription factors (TFs) that initiate and regulate transcription of the genes involved in erythropoiesis. These TFs possess DNA-binding domains that recognize specific nucleotide sequences in genes, to which they bind and regulate transcription. Variants in the genes that encode either KLF1 or GATA1 can result in a range of hematologic phenotypes-from benign to severe forms of thrombocytopenia and anemia; they can also weaken the expression of blood group antigens. The Lutheran (LU) blood group system is susceptible to TF gene variations, particularly KLF1 variants. Individuals heterozygous for KLF1 gene variants show reduced Lutheran antigens on red blood cells that are not usually detected by routine hemagglutination methods. This reduced antigen expression is referred to as the In(Lu) phenotype. For accurate blood typing, it is important to distinguish between the In(Lu) phenotype, which has very weak antigen expression, and the true Lunull phenotype, which has no antigen expression. The International Society of Blood Transfusion blood group allele database registers KLF1 and GATA1 variants associated with modified Lutheran expression. Here, we review KLF1 and recent novel gene variants defined through investigating blood group phenotype and genotype discrepancies or, for one report, investigating cases with unexplained chronic anemia. In addition, we include a review of the GATA1 TF, including a case report describing the second GATA1 variant associated with a serologic Lu(a-b-) phenotype. Finally, we review both past and recent reports on variations in the DNA sequence motifs on the blood group genes that disrupt the binding of the GATA1 TF and either remove or reduce erythroid antigen expression. This review highlights the diversity and complexity of the transcription process itself and the need to consider these factors as an added component for accurate blood group phenotyping.

Asunto(s)

Antígenos de Grupos Sanguíneos , Eritrocitos , Factor de Transcripción GATA1 , Factores de Transcripción de Tipo Kruppel , Humanos , Factores de Transcripción de Tipo Kruppel/genética , Factor de Transcripción GATA1/genética , Eritrocitos/metabolismo , Eritrocitos/inmunología , Antígenos de Grupos Sanguíneos/genética , Antígenos de Grupos Sanguíneos/inmunología , Sistema del Grupo Sanguíneo Lutheran/genética , Regulación de la Expresión Génica , Eritropoyesis/genética

RESUMEN

Transient abnormal myelopoiesis (TAM) in neonates with Down syndrome is a distinct form of leukemia or preleukemia that mirrors the hematological features of acute megakaryoblastic leukemia. However, it typically resolves spontaneously in the early stages. TAM originates from fetal liver (FL) hematopoietic precursor cells and emerges due to somatic mutations in GATA1 in utero. In TAM, progenitor cells proliferate and differentiate into mature megakaryocytes and granulocytes. This process occurs both in vitro, aided by hematopoietic growth factors (HGFs) produced in the FL, and in vivo, particularly in specific anatomical sites like the FL and blood vessels. The FL's hematopoietic microenvironment plays a crucial role in TAM's pathogenesis and may contribute to its spontaneous regression. This review presents an overview of current knowledge regarding the unique features of TAM in relation to the FL hematopoietic microenvironment, focusing on the functions of HGFs and the pathological features of TAM.

Asunto(s)

Síndrome de Down , Reacción Leucemoide , Hígado , Humanos , Síndrome de Down/complicaciones , Síndrome de Down/patología , Hígado/patología , Reacción Leucemoide/genética , Reacción Leucemoide/patología , Reacción Leucemoide/diagnóstico , Reacción Leucemoide/complicaciones , Células Madre Hematopoyéticas/patología , Células Madre Hematopoyéticas/metabolismo , Feto , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Mielopoyesis

RESUMEN

Bleeding and thrombosis are known as common complications of polycythemia for a long time. However, the role of coagulation system in erythropoiesis is unclear. Here, we discover that an anticoagulant protein tissue factor pathway inhibitor (TFPI) plays an essential role in erythropoiesis via the control of heme biosynthesis in central macrophages. TFPI levels are elevated in erythroblasts of human erythroblastic islands with JAK2V617F mutation and hypoxia condition. Erythroid lineage-specific knockout TFPI results in impaired erythropoiesis through decreasing ferrochelatase expression and heme biosynthesis in central macrophages. Mechanistically, the TFPI interacts with thrombomodulin to promote the downstream ERK1/2-GATA1 signaling pathway to induce heme biosynthesis in central macrophages. Furthermore, TFPI blockade impairs human erythropoiesis in vitro, and normalizes the erythroid compartment in mice with polycythemia. These results show that erythroblast-derived TFPI plays an important role in the regulation of erythropoiesis and reveal an interplay between erythroblasts and central macrophages.

Asunto(s)

Eritroblastos , Eritropoyesis , Factor de Transcripción GATA1 , Hemo , Lipoproteínas , Macrófagos , Policitemia , Policitemia/metabolismo , Policitemia/genética , Policitemia/patología , Eritroblastos/metabolismo , Hemo/metabolismo , Humanos , Animales , Lipoproteínas/metabolismo , Macrófagos/metabolismo , Ratones , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA1/genética , Janus Quinasa 2/metabolismo , Janus Quinasa 2/genética , Trombomodulina/metabolismo , Trombomodulina/genética , Ratones Noqueados , Ferroquelatasa/metabolismo , Ferroquelatasa/genética , Masculino , Sistema de Señalización de MAP Quinasas , Ratones Endogámicos C57BL , Femenino

RESUMEN

Bromodomain containing protein 9 (BRD9), a member of the non-canonical BRG1/BRM-associated factor (ncBAF) chromatin remodeling complex, has been implicated as a synthetic lethal target in AML but its function in normal human hematopoiesis is unknown. In hematopoietic stem and progenitor cells (HSPC) genomic or chemical inhibition of BRD9 led to a proliferative disadvantage and loss of stem cells in vitro. Human HSPCs with reduced BRD9 protein levels produced lower numbers of immature mixed multipotent GEMM colonies in semi-solid media. In lineage-promoting culture conditions, cells with reduced BRD9 levels failed to differentiate into the megakaryocytic lineage and showed delayed differentiation into erythroid cells but enhanced terminal myeloid differentiation. HSPCs with BRD9 knock down (KD) had reduced long-term multilineage engraftment in a xenotransplantation assay. An increased number of downregulated genes in RNAseq analysis after BRD9 KD coupled with a gain in chromatin accessibility at the promoters of several repressive transcription factors (TF) suggest that BRD9 functions in the maintenance of active transcription during HSC differentiation. In particular, the hematopoietic master regulator GATA1 was identified as one of the core TFs regulating the gene networks modulated by BRD9 loss in HSPCs. BRD9 inhibition reduced a GATA1-luciferase reporter signal, further suggesting a role for BRD9 in regulating GATA1 activity. BRD9 is therefore an additional example of epigenetic regulation of human hematopoiesis.

Asunto(s)

Diferenciación Celular , Linaje de la Célula , Células Madre Hematopoyéticas , Factores de Transcripción , Humanos , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/citología , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Animales , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA1/genética , Ratones , Hematopoyesis , Proteínas que Contienen Bromodominio

RESUMEN

During hematopoiesis, megakaryocytic erythroid progenitors (MEPs) differentiate into megakaryocytic or erythroid lineages in response to specific transcriptional factors, yet the regulatory mechanism remains to be elucidated. Using the MEP­like cell line HEL western blotting, RT­qPCR, lentivirus­mediated downregulation, flow cytometry as well as chromatin immunoprecipitation (ChIp) assay demonstrated that the E26 transformation­specific (ETS) transcription factor friend leukemia integration factor 1 (Fli­1) inhibits erythroid differentiation. The present study using these methods showed that while FLI1­mediated downregulation of GATA binding protein 1 (GATA1) suppresses erythropoiesis, its direct transcriptional induction of GATA2 promotes megakaryocytic differentiation. GATA1 is also involved in megakaryocytic differentiation through regulation of GATA2. By contrast to FLI1, the ETS member erythroblast transformation­specific­related gene (ERG) negatively controls GATA2 and its overexpression through exogenous transfection blocks megakaryocytic differentiation. In addition, FLI1 regulates expression of LIM Domain Binding 1 (LDB1) during erythroid and megakaryocytic commitment, whereas shRNA­mediated depletion of LDB1 downregulates FLI1 and GATA2 but increases GATA1 expression. In agreement, LDB1 ablation using shRNA lentivirus expression blocks megakaryocytic differentiation and modestly suppresses erythroid maturation. These results suggested that a certain threshold level of LDB1 expression enables FLI1 to block erythroid differentiation. Overall, FLI1 controlled the commitment of MEP to either erythroid or megakaryocytic lineage through an intricate regulation of GATA1/GATA2, LDB1 and ERG, exposing multiple targets for cell fate commitment and therapeutic intervention.

Asunto(s)

Diferenciación Celular , Células Eritroides , Megacariocitos , Humanos , Diferenciación Celular/genética , Línea Celular , Células Eritroides/metabolismo , Células Eritroides/citología , Factor de Transcripción GATA1/metabolismo , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA2/metabolismo , Factor de Transcripción GATA2/genética , Regulación de la Expresión Génica , Proteínas con Dominio LIM/metabolismo , Proteínas con Dominio LIM/genética , Megacariocitos/metabolismo , Megacariocitos/citología , Proteína Proto-Oncogénica c-fli-1/metabolismo , Proteína Proto-Oncogénica c-fli-1/genética , Regulador Transcripcional ERG/metabolismo , Regulador Transcripcional ERG/genética

Asunto(s)

Factor de Transcripción GATA1 , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Humanos , Animales , Trastornos de Fallo de la Médula Ósea/metabolismo , Trastornos de Fallo de la Médula Ósea/patología , Enfermedades de la Médula Ósea/metabolismo , Enfermedades de la Médula Ósea/patología , Enfermedades de la Médula Ósea/genética

RESUMEN

Toll-interacting protein (Tollip) serves as a crucial inhibitory factor in the modulation of Toll-like receptor (TLR)-mediated innate immunological responses. The structure and function of Tollip have been well documented in mammals, yet the information in teleost remained limited. This work employed in vitro overexpression and RNA interference in vivo and in vitro to comprehensively examine the regulatory effects of AjTollip on NF-κB and MAPK signaling pathways. The levels of p65, c-Fos, c-Jun, IL-1, IL-6, and TNF-α were dramatically reduced following overexpression of AjTollip, whereas knocking down AjTollip in vivo and in vitro enhanced those genes' expression. Protein molecular docking simulations showed AjTollip interacts with AjTLR2, AjIRAK4a, and AjIRAK4b. A better understanding of the transcriptional regulation of AjTollip is crucial to elucidating the role of Tollip in fish antibacterial response. Herein, we cloned and characterized a 2.2 kb AjTollip gene promoter sequence. The transcription factors GATA1 and Sp1 were determined to be associated with the activation of AjTollip expression by using promoter truncation and targeted mutagenesis techniques. Collectively, our results indicate that AjTollip suppresses the NF-κB and MAPK signaling pathways, leading to the decreased expression of the downstream inflammatory factors, and GATA1 and Sp1 play a vital role in regulating AjTollip expression.

Asunto(s)

Anguilla , Proteínas de Peces , Factor de Transcripción GATA1 , FN-kappa B , Animales , Proteínas de Peces/genética , Proteínas de Peces/inmunología , Proteínas de Peces/química , Proteínas de Peces/metabolismo , FN-kappa B/metabolismo , FN-kappa B/genética , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Anguilla/genética , Anguilla/inmunología , Factor de Transcripción Sp1/genética , Factor de Transcripción Sp1/metabolismo , Regulación de la Expresión Génica/inmunología , Inmunidad Innata/genética , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/inmunología , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Péptidos y Proteínas de Señalización Intracelular/inmunología , Péptidos y Proteínas de Señalización Intracelular/química , Transducción de Señal

RESUMEN

BACKGROUND: Blood typing is essential for safe transfusions and is performed serologically or genetically. Genotyping predominantly focuses on coding regions, but non-coding variants may affect gene regulation, as demonstrated in the ABO, FY and XG systems. To uncover regulatory loci, we expanded a recently developed bioinformatics pipeline for discovery of non-coding variants by including additional epigenetic datasets. METHODS: Multiple datasets including ChIP-seq with erythroid transcription factors (TFs), histone modifications (H3K27ac, H3K4me1), and chromatin accessibility (ATAC-seq) were analyzed. Candidate regulatory regions were investigated for activity (luciferase assays) and TF binding (electrophoretic mobility shift assay, EMSA, and mass spectrometry, MS). RESULTS: In total, 814 potential regulatory sites in 47 blood-group-related genes were identified where one or more erythroid TFs bound. Enhancer candidates in CR1, EMP3, ABCB6, and ABCC4 indicated by ATAC-seq, histone markers, and co-occupancy of 4 TFs (GATA1/KLF1/RUNX1/NFE2) were investigated but only CR1 and ABCC4 showed increased transcription. Co-occupancy of GATA1 and KLF1 was observed in the KEL promoter, previously reported to contain GATA1 and Sp1 sites. TF binding energy scores decreased when three naturally occurring variants were introduced into GATA1 and KLF1 motifs. Two of three GATA1 sites and the KLF1 site were confirmed functionally. EMSA and MS demonstrated increased GATA1 and KLF1 binding to the wild-type compared to variant motifs. DISCUSSION: This combined bioinformatics and experimental approach revealed multiple candidate regulatory regions and predicted TF co-occupancy sites. The KEL promoter was characterized in detail, indicating that two adjacent GATA1 and KLF1 motifs are most crucial for transcription.

Asunto(s)

Antígenos de Grupos Sanguíneos , Epigénesis Genética , Humanos , Antígenos de Grupos Sanguíneos/genética , Factor de Transcripción GATA1/genética , Factores de Transcripción de Tipo Kruppel/genética , Secuencias Reguladoras de Ácidos Nucleicos/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo

RESUMEN

Mutations in the master hematopoietic transcription factor GATA1 are often associated with functional defects in erythropoiesis and megakaryopoiesis. In this study, we identified a novel GATA1 germline mutation (c.1162delGG, p.Leu387Leufs*62) in a patient with congenital anemia and occasional thrombocytopenia. The C-terminal GATA1, a rarely studied mutational region, undergoes frameshifting translation as a consequence of this double-base deletion mutation. To investigate the specific function and pathogenic mechanism of this mutant, in vitro mutant models of stable re-expression cells were generated. The mutation was subsequently validated to cause diminished transcriptional activity of GATA1 and defective differentiation of erythroid and megakaryocytes. Using proximity labeling and mass spectrometry, we identified selective alterations in the proximal protein networks of the mutant, revealing decreased binding to a set of normal GATA1-interaction proteins, including the essential co-factor FOG1. Notably, our findings further demonstrated enhanced recruitment of the protein arginine methyltransferase PRMT6, which mediates histone modification at H3R2me2a and represses transcription activity. We also found an enhanced binding of this mutant GATA1/PRMT6 complex to the transcriptional regulatory elements of GATA1's target genes. Moreover, treatment of the PRMT6 inhibitor MS023 could partially rescue the inhibited transcriptional and impaired erythroid differentiation caused by the GATA1 mutation. Taken together, our results provide molecular insights into erythropoiesis in which mutation leads to partial loss of GATA1 function, and the role of PRMT6 and its inhibitor MS023 in congenital anemia, highlighting PRMT6 binding as a negative factor of GATA1 transcriptional activity in aberrant hematopoiesis.

Asunto(s)

Factor de Transcripción GATA1 , Mutación de Línea Germinal , Unión Proteica , Proteína-Arginina N-Metiltransferasas , Humanos , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Proteína-Arginina N-Metiltransferasas/genética , Proteína-Arginina N-Metiltransferasas/metabolismo , Diferenciación Celular/genética , Eritropoyesis/genética , Masculino , Femenino , Anemia/genética

RESUMEN

Constitutional trisomy 21 (T21) is a state of aneuploidy associated with high incidence of childhood acute myeloid leukemia (AML). T21-associated AML is preceded by transient abnormal myelopoiesis (TAM), which is triggered by truncating mutations in GATA1 generating a short GATA1 isoform (GATA1s). T21-associated AML emerges due to secondary mutations in hematopoietic clones bearing GATA1s. Since aneuploidy generally impairs cellular fitness, the paradoxically elevated risk of myeloid malignancy in T21 is not fully understood. We hypothesized that individuals with T21 bear inherent genome instability in hematopoietic lineages that promotes leukemogenic mutations driving the genesis of TAM and AML. We found that individuals with T21 show increased chromosomal copy number variations (CNVs) compared to euploid individuals, suggesting that genome instability could be underlying predisposition to TAM and AML. Acquisition of GATA1s enforces myeloid skewing and maintenance of the hematopoietic progenitor state independently of T21; however, GATA1s in T21 hematopoietic progenitor cells (HPCs) further augments genome instability. Increased dosage of the chromosome 21 (chr21) gene DYRK1A impairs homology-directed DNA repair as a mechanism of elevated mutagenesis. These results posit a model wherein inherent genome instability in T21 drives myeloid malignancy in concert with GATA1s mutations.

Asunto(s)

Síndrome de Down , Leucemia Mieloide Aguda , Reacción Leucemoide , Trastornos Mieloproliferativos , Humanos , Niño , Síndrome de Down/complicaciones , Variaciones en el Número de Copia de ADN , Trastornos Mieloproliferativos/genética , Inestabilidad Genómica , Leucemia Mieloide Aguda/patología , Aneuploidia , Trisomía , Factor de Transcripción GATA1/genética

RESUMEN

Children with Down syndrome (DS) have a 10- to 20-fold greater predisposition to develop acute leukemia compared to the general population, with a skew towards myeloid leukemia (ML-DS). While ML-DS is known to be a subtype with good outcome, patients who relapse face a dismal prognosis. Acute lymphocytic leukemia in DS (DS-ALL) is considered to have poor prognosis. The relapse rate is high in DS-ALL compared to their non-DS counterparts. We have a better understanding about the mutational spectrum of DS leukemia. Studies using animal, embryonic stem cell- and induced pluripotent stem cell-based models have shed light on the mechanism by which these mutations contribute to disease initiation and progression. In this review, we list the currently available treatment strategies for DS-leukemias along with their outcome with emphasis on challenges with chemotherapy-related toxicities in children with DS. We focus on the mechanisms of initiation and progression of leukemia in children with DS and highlight the novel molecular targets with greater success in preclinical trials that have the potential to progress to the clinic.

Asunto(s)

Síndrome de Down , Leucemia Megacarioblástica Aguda , Niño , Animales , Humanos , Síndrome de Down/complicaciones , Síndrome de Down/genética , Síndrome de Down/terapia , Leucemia Megacarioblástica Aguda/tratamiento farmacológico , Leucemia Megacarioblástica Aguda/genética , Factor de Transcripción GATA1/genética , Mutación , Recurrencia , Biología

RESUMEN

Rho GTPase activating protein 18 (ARHGAP18), a member of the RhoGAP gene family that increases GTP hydrolysis and inhibits RhoGTPase, was recently discovered to play a role in the development of breast cancer. However, its exact biological role in hepatocellular carcinoma (HCC) remains unclear. In our present study, we comprehensively assessed ARHGAP18 expression and its correlation with the prognostic value of cancer patients in databases. Cell proliferation and colony formation assays were employed to monitor cell growth. Luciferase reporter assay, Chromatin immunoprecipitation qPCR (ChIP-qPCR), immunofluorescence were performed for mechanism research. The expression of genes and proteins was detected by real-time PCR and western blotting. According to the findings of this research, ARHGAP18 protein levels are increased in HCC tissues compared to adjacent nontumor tissues, and ARHGAP18 overexpression is associated with poor survival. The results of a gain- and loss-of-function experiment with HCC cells in vitro demonstrated that ARHGAP18 stimulated cell proliferation, migration, and invasion. Mechanistically, we found that the transcription factor GATA binding protein 1 (GATA1) could bind to the ARHGAP18 promoter and facilitate ARHGAP18 expression. Further studies revealed that the effects of ARHGAP18 silencing on HCCLM3 and Bel-7402 cells were blocked by GATA1 overexpression. In conclusion, GATA1-mediated ARHGAP18 up-regulation plays an important role in HCC tumorigenesis and might be a potential therapeutic target for HCC.

Asunto(s)

Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patología , Neoplasias Hepáticas/patología , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Regulación de la Expresión Génica , Proliferación Celular/genética , Regulación Neoplásica de la Expresión Génica , Línea Celular Tumoral , Movimiento Celular/genética , Proteínas Activadoras de GTPasa/genética , Proteínas Activadoras de GTPasa/metabolismo

RESUMEN

Diamond-Blackfan anemia (DBA) is a congenital anemia with erythroid cell aplasia. Most of the causative genes are ribosomal proteins. GATA1, a hematopoietic master transcription factor required for erythropoiesis, also causes DBA. GATA1 is located on Xp11.23; therefore, DBA develops only in males in an X-linked inheritance pattern. Here, we report a case of transient erythroblastopenia and moderate anemia in a female newborn infant with a de novo GATA1 variant. In this patient, increased methylation of the GATA1 wild-type allele was observed in erythroid cells. Skewed lyonization of GATA1 may cause mild transient erythroblastopenia in a female patient.

Asunto(s)

Anemia Aplásica , Anemia de Diamond-Blackfan , Anemia Hemolítica Congénita , Masculino , Lactante , Recién Nacido , Humanos , Femenino , Proteínas Ribosómicas/genética , Anemia de Diamond-Blackfan/genética , Eritropoyesis , Factor de Transcripción GATA1/genética

RESUMEN

BACKGROUND: The transcription factor GATA1 is an essential regulator of erythroid cell gene expression and maturation and is also relevant for platelet biogenesis. GATA1-related thrombocytopenia (GATA1-RT) is a rare X-linked inherited platelet disorder (IPD) characterized by macrothrombocytopenia and dyserythropoiesis. Enlarged platelet size, reduced platelet granularity, and noticeable red blood cell anisopoikilocytosis are characteristic but unspecific morphological findings in GATA1-RT. OBJECTIVES: To expand the investigation of platelet phenotype of patients with GATA1-RT by light- and immunofluorescence microscopy on a blood smear. METHODS: We assessed blood smears by light- and immunofluorescence microscopy after May-Grünwald Giemsa staining using a set of 13 primary antibodies against markers belonging to different platelet structures. Antibody binding was visualized by fluorescently labeled secondary antibodies. RESULTS: We investigated 12 individuals with genetically confirmed GATA1-RT from 8 unrelated families. While confirming the already known characteristic of platelet morphology (platelet macrocytosis and reduced expression of markers for α-granules), we also found aggregates of nonmuscular myosin heavy chain II A (NMMIIA) in the erythrocytes in all individuals (1-3 aggregates/cell, 1-3 µm diameter). By systematically reanalyzing blood smears from a cohort of patients with 19 different forms of IPD, we found similar NMMIIA aggregates in the red blood cells only in subjects with GFI1B-related thrombocytopenia (GFI1B-RT), the other major IPD featured by dyserythropoiesis. CONCLUSION: Aggregates of NMMIIA in the erythrocytes associate with GATA1-RT and GFI1B-RT and can facilitate their diagnosis on blood smears. This previously unreported finding might represent a novel marker of dyserythropoiesis assessable in peripheral blood.

Asunto(s)

Anemia , Factor de Transcripción GATA1 , Miosina Tipo IIA no Muscular , Proteínas Proto-Oncogénicas , Proteínas Represoras , Trombocitopenia , Humanos , Plaquetas/metabolismo , Eritrocitos , Factor de Transcripción GATA1/genética , Factor de Transcripción GATA1/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Represoras/genética

RESUMEN

Patients with Down syndrome (DS), or trisomy 21 (T21), are at increased risk of transient abnormal myelopoiesis (TAM) and acute megakaryoblastic leukemia (ML-DS). Both TAM and ML-DS require prenatal somatic mutations in GATA1, resulting in the truncated isoform GATA1s. The mechanism by which individual chromosome 21 (HSA21) genes synergize with GATA1s for leukemic transformation is challenging to study, in part due to limited human cell models with wild-type GATA1 (wtGATA1) or GATA1s. HSA21-encoded DYRK1A is overexpressed in ML-DS and may be a therapeutic target. To determine how DYRK1A influences hematopoiesis in concert with GATA1s, we used gene editing to disrupt all 3 alleles of DYRK1A in isogenic T21 induced pluripotent stem cells (iPSCs) with and without the GATA1s mutation. Unexpectedly, hematopoietic differentiation revealed that DYRK1A loss combined with GATA1s leads to increased megakaryocyte proliferation and decreased maturation. This proliferative phenotype was associated with upregulation of D-type cyclins and hyperphosphorylation of Rb to allow E2F release and derepression of its downstream targets. Notably, DYRK1A loss had no effect in T21 iPSCs or megakaryocytes with wtGATA1. These surprising results suggest that DYRK1A and GATA1 may synergistically restrain megakaryocyte proliferation in T21 and that DYRK1A inhibition may not be a therapeutic option for GATA1s-associated leukemias.

Asunto(s)

Síndrome de Down , Leucemia Megacarioblástica Aguda , Humanos , Síndrome de Down/genética , Síndrome de Down/complicaciones , Factor de Transcripción GATA1/genética , Leucemia Megacarioblástica Aguda/complicaciones , Leucemia Megacarioblástica Aguda/genética , Trombopoyesis/genética