Single-cell analysis of megakaryopoiesis in peripheral CD34+ cells: insights into ETV6-related thrombocytopenia
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE206089 | GEO | 2023/06/15
REPOSITORIES: GEO
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Project description:Megakaryocytic-Erythroid Progenitors (MEP) produce circulating red blood cells and platelets. Although much is known regarding megakaryocytic (Mk) and erythroid (E) maturation, detailed molecular mechanisms underlying the MEP fate decision have not been determined. Single cell RNA sequencing of highly enriched populations of primary human common myeloid progenitors (CMP), MEP, megakaryocyte progenitors (MKP) and erythroid progenitors (ERP), revealed that MEP have a distinct molecular signature with co-expression of genes otherwise expressed exclusively in CMP, MKP or ERP. Cell cycle genes are significantly differentially expressed between MEP, MKP, and ERP. We therefore tested the effects on MEP fate of genetic and pharmacologic modulation of cell cycle progression, and found that cell cycle activity mechanistically controls MEP fate decisions; cell cycle activation promotes E whereas cell cycle inhibition promotes Mk specification. The data obtained from healthy cells can now be applied to the mechanisms underlying benign and malignant disease states of Mk and E production.
2018-11-02 | GSE112692 | GEO
Project description:Hematopoietic stem cells (HSCs) reside in the bone marrow (BM), can self-renew, and generate all blood cells. Most hematopoietic lineages arise through successive, increasingly lineage-committed progenitors. In contrast, megakaryocytes (MKs), hyperploid cells that generate platelets essential to hemostasis, can derive rapidly and directly from HSCs, subpopulations of which are primed for MK differentiation. The underlying mechanism is unknown however. Here we show that DNA damage and subsequent arrest in the G2 phase of the cell cycle rapidly induce MK commitment in HSCs, but not in progenitors, through an initially predominantly post-transcriptional mechanism. Cycling HSCs show extensive replication-induced DNA damage associated with uracil misincorporation in vivo and in vitro. Consistent with this notion, thymidine attenuated DNA damage, rescued HSC maintenance and reduced the generation of CD41+ MK-committed HSCs in vitro. Similarly, overexpression of the dUTP-scavenging enzyme, dUTPase, enhanced in vitro maintenance of HSCs. Replication stress-induced MK priming, at least in part caused by uracil misincorporation, is therefore a barrier to HSC maintenance and expansion. DNA damage-induced MK priming may allow rapid generation of a lineage essential to immediate organismal survival, while simultaneously removing damaged HSCs and potentially avoiding malignant transformation of self-renewing stem cells
2024-06-24 | GSE240695 | GEO
Project description:ETV6-RUNX1 is associated with childhood B-cell acute lymphoblastic leukemia (B-ALL), but the consequence of ETV6-RUNX1 expression on cell lineage decision during B-cell leukemogenesis remains largely evasive. Clinically silent ETV6-RUNX1 preleukemic clones are frequently found in neonatal cord blood, but only a few carriers develop B-ALL as a result of the acquisition of secondary postnatal genetic hits, like KDM5C or PAX5 loss. However, understanding the mechanism involved in this transformation would advance the development of non-toxic prophylactic interventions to preleukemic carriers. Using genetic lineage tracing, we have examined the capacity of ETV6-RUNX1 in instructing a B-cell malignant phenotype. Restricted Cre-mediated activation of ETV6-RUNX1 from the endogenous Etv6 locus into B-cell precursors does not trigger B-ALL development. Similarly, concomitant transient ETV6-RUNX1 expression in hematopoietic progenitors close to restricted Cre-mediated introduction of second hit (Kdm5c loss) in B-cells fail to induce B-ALL. In contrast, targeting ETV6-RUNX1 in hematopoietic progenitors was required to induce leukemia. These mice develop either T-ALL or B-ALL, suggesting that the nature of the second hit may define tumor cell identity during ETV6-RUNX1 leukemogenesis. In order to uncover a potential exclusive effect of the second hit in establishing the leukemic phenotype, we next showed that the introduction of the second hit, either Kdm5c or Pax5 loss, to the ETV6-RUNX1 preleukemic clone confers the tumor B-cell identity without need of environmental infection exposure. The resulting B-ALLs clustered according to the second-hit by RNA sequencing (RNA-Seq) analysis. Together these results provide a novel paradigm for the generation of tumor B cells through ETV6-RUNX1 in vivo where the second hit confers the tumor cell-identity to the ETV6-RUNX1 preleukemic clone. These findings could be relevant to develop new therapeutic approaches to prevent disease development.
2021-05-06 | GSE141112 | GEO
Project description:Constitutional epimutations of tumor suppressor genes manifest as promoter methylation and transcriptional silencing of a single allele in normal somatic tissues, thereby predisposing to cancer. Constitutional MLH1 epimutations occur in individuals with young-onset cancer and demonstrate non-Mendelian inheritance through their reversal in the germline. We report a cancer-affected family showing dominant transmission of soma-wide highly mosaic MLH1 methylation and transcriptional repression linked to a particular genetic haplotype. The epimutation was erased in spermatozoa but reinstated in the somatic cells of the next generation. The affected haplotype harbored two single nucleotide substitutions in tandem: c.-27C>A located near the transcription initiation site and c.85G>T. The c.-27C>A variant significantly reduced transcriptional activity in reporter assays and is the probable cause of this epimutation. Five members of a three-generation Caucasian Lynch syndrome family with an autosomal dominant MLH1 epimutation linked to a single nucleotide variant (c.-27C>A) within the MLH1 5'UTR were examined for copy number variations and retention of heterozygosity on chromosome 3. These five carriers of constitutional MLH1 methylation and the c.-27C>A variant were compared with 300 healthy Caucasian controls from the Wellcome Trust Case Control Consortium using three algorithms (QuantiSNP, PennCNV, COKGEN) to detect any copy number variants. The five family members studied were female (the proband II5, her affected mother I1, and three asymptomatic relatives II2, II4 and III2) are labeled according to the pedigree in Figure 3 of the associated publication (Hitchins et al., Cancer Cell, 2011). The supplementary file 'GSE30348_gw6.lrr_baf.txt' contains log R ratio and B-allele frequency values in a tab-delimited format with one marker per row.
2011-07-01 | E-GEOD-30348 | biostudies-arrayexpress
Project description:Background: Constitutional MLH1 epimutations are characterized by monoallelic methylation of the MLH1 promoter throughout normal tissues, accompanied by allele-specific silencing. The mechanism underlying primary MLH1 epimutations is currently unknown. The aim of this study was to perform an in-depth characterization of constitutional MLH1 epimutations targeting the aberrantly methylated region around MLH1 and other genomic loci. Methods: Twelve MLH1 epimutation carriers, 61 Lynch syndrome patients and 41 healthy controls, were analyzed by Infinium Human Methylation 450K beadchip, and targeted molecular techniques were used to characterize the MLH1 epimutation in carriers and their inheritance pattern. Results: No nucleotide or structural variants were identified in-cis on the epimutated allele in ten carriers, in which intergenerational methylation erasure was demonstrated in two, suggesting primary type of epimutation. CNVs outside the MLH1 locus were found in two cases. EPM2AIP1-MLH1 CpG island was identified as the sole differentially methylated region in MLH1 epimutation carriers compared to controls. Conclusion: Primary constitutional MLH1 epimutations arise as a focal epigenetic event at the EPM2AIP1-MLH1 CpG island in the absence of cis-acting genetic variants. Further molecular characterization is needed to elucidate the mechanistic basis of MLH1 epimutations and their heritability/reversibility.
2017-11-28 | GSE107352 | GEO
Project description:Background: Constitutional MLH1 epimutations are characterized by monoallelic methylation of the MLH1 promoter throughout normal tissues, accompanied by allele-specific silencing. The mechanism underlying primary MLH1 epimutations is currently unknown. The aim of this study was to perform an in-depth characterization of constitutional MLH1 epimutations targeting the aberrantly methylated region around MLH1 and other genomic loci. Methods: Twelve MLH1 epimutation carriers, 61 Lynch syndrome patients and 41 healthy controls, were analyzed by Infinium Human Methylation 450K beadchip, and targeted molecular techniques were used to characterize the MLH1 epimutation in carriers and their inheritance pattern. Results: No nucleotide or structural variants were identified in-cis on the epimutated allele in ten carriers, in which intergenerational methylation erasure was demonstrated in two, suggesting primary type of epimutation. CNVs outside the MLH1 locus were found in two cases. EPM2AIP1-MLH1 CpG island was identified as the sole differentially methylated region in MLH1 epimutation carriers compared to controls. Conclusion: Primary constitutional MLH1 epimutations arise as a focal epigenetic event at the EPM2AIP1-MLH1 CpG island in the absence of cis-acting genetic variants. Further molecular characterization is needed to elucidate the mechanistic basis of MLH1 epimutations and their heritability/reversibility.
2017-11-28 | GSE107351 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below. ETS Variant 6 (ETV6) encodes an essential transcriptional repressor abundantly expressed in hematopoietic stem and progenitor cells (HSPCs), where it is required for adult hematopoiesis. Heterozygous pathogenic germline ETV6 variants are associated with Thrombocytopenia 5 (T5), a poorly understood genetic condition predisposing to thrombocytopenia and hematologic malignancies. To elucidate how germline ETV6 variants impact the HSPC compartment and contribute to disease, we generated a knock-in mouse model harboring an Etv6R355X loss-of-function variant, which is equivalent to the T5-associated variant ETV6R359X. Under homeostatic conditions, all HSPC subpopulations are present in the bone marrow (BM) of Etv6R355X/+ mice; however, these animals display subtle shifts in the proportions and/or numbers of specific progenitor subtypes. To examine whether the Etv6R355X/+ mutation impacts HSPC function, we carried out serial competitive transplantation and observed that Etv6R355X/+ lineage-sca1+cKit+ (LSK) cells exhibit significantly impaired reconstitution compared to Etv6+/+ LSK cells with near complete failure to repopulate irradiated-recipients by the tertiary transplant. Mechanistic studies incorporating CUT&RUN, ATAC-Seq and Hi-C identify ETV6 binding at inflammatory gene loci, including those within the TNF signaling pathway, in Etv6+/+ HSPCs, mouse BM-progenitor-derived HPC5 cells, and human CD34+ cells. Further, single-cell RNA-Seq of BM cells isolated post-competitive transplantation reveals upregulation of inflammatory genes in Etv6R355X/+ compared to Etv6+/+ progenitors. Corroborating these findings, Etv6R355X/+ HSPCs produce significantly more TNF than Etv6+/+ cells post-transplantation. From these studies, we conclude that ETV6 is required to repress inflammatory gene expression in HSPCs under conditions of hematopoietic stress and this mechanism may be critical to sustain HSPC function.
2023-08-24 | GSE213597 | GEO
Project description:ObjectiveWe previously determined that protein kinase C δ (PKCδ) regulates platelet function. However, the function of PKCδ in megakaryopoiesis is unknown.Approach and resultsUsing PKCδ(-/-) and wild-type littermate mice, we found that deficiency of PKCδ caused an increase in white blood cells and platelet counts, as well as in bone marrow and splenic megakaryocytes (P<0.05). Additionally, the megakaryocyte number and DNA content were enhanced in PKCδ(-/-) mouse bone marrow after culturing with exogenous thrombopoietin compared with wild-type (P<0.05). Importantly, thrombopoietin-induced signaling was also altered with PKCδ deletion because both extracellular signal-regulated kinase and Akt308 phosphorylation were heightened in PKCδ(-/-) megakaryocytes compared with wild-type. Finally, PKCδ(-/-) mice recovered faster and had a heightened rebound thrombocytosis after thrombocytopenic challenge.ConclusionsThese data suggest that PKCδ is an important megakaryopoietic protein, which regulates signaling induced by thrombopoietin and represents a potential therapeutic target.
| S-EPMC4239172 | biostudies-literature
Project description:Single-cell analysis of megakaryopoiesis in peripheral CD34+ cells: insights into ETV6-related thrombocytopenia
| PRJNA849164 | ENA
Project description:Thrombocytopenia is frequently encountered in infants with necrotizing enterocolitis (NEC). To develop a preclinical model of NEC-related thrombocytopenia, we measured serial platelet counts in 10-d-old (P10) mouse pups with trinitrobenzene sulfonic acid (TNBS)-induced NEC-like injury. We also measured platelet volume indices, immature platelet fraction (IPF), and megakaryocyte number/ploidy in these animals.Platelet counts, platelet volume indices, and IPF were measured in control (N = 65) and TNBS-treated pups (N = 104) using an automated hematology analyzer. Bone marrow megakaryocyte number, ploidy and CD41 expression were measured by flow cytometry. These findings were confirmed in a small cohort of P3 mice with NEC-like injury.Murine pups with TNBS-mediated NEC-like injury developed thrombocytopenia at 15-24 h after exposure to TNBS. Intestinal injury was associated with increased platelet volume indices (mean platelet volume, platelet-to-large cell ratio, and platelet distribution width), and IPF, indicating increased thrombopoiesis. These mice also showed increased megakaryocyte number, ploidy, and CD41 expression, indicating increased megakaryocyte differentiation.Similar to human NEC, murine NEC-like injury was also associated with decreased platelet counts. There was evidence of increased megakaryocyte differentiation and thrombopoiesis, which favors peripheral consumption of platelets as the likely mechanism of thrombocytopenia in these animals, over decreased platelet production.
| S-EPMC5425334 | biostudies-other