Molecular mechanisms underlying the megakaryocyte developmental defects caused by the ETV6 p.R369W variant
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE306384 | GEO | 2025/12/31
REPOSITORIES: GEO
Similar Datasets
Project description:The transcription factor Growth Factor Independence 1B (GFI1B) recruits Lysine Specific Demethylase 1A (LSD1/KDM1A) to stimulate gene programs relevant for megakaryocyte and platelet biology. Inherited pathogenic GFI1B variants result in thrombocytopenia and bleeding propensities with varying intensity. Whether these affect similar gene programs is unknow. Here we studied transcriptomic effects of four patient-derived GFI1B variants (GFI1BT174N,H181Y,R184P,Q287*) in MEG01 megakaryoblasts. Compared to normal GFI1B, each variant affected different gene programs with GFI1BQ287* uniquely failing to repress myeloid traits. In line with this, single cell RNA-sequencing of induced pluripotent stem cell (iPSC)-derived megakaryocytes revealed a 4.5-fold decrease in the megakaryocyte/myeloid cell ratio in GFI1BQ287* versus normal conditions. Inhibiting the GFI1B-LSD1 interaction with small molecule GSK-LSD1 resulted in activation of myeloid genes in normal iPSC-derived megakaryocytes similar as observed for GFI1BQ287* iPSC-derived megakaryocytes. Thus, GFI1B and LSD1 facilitate gene programs relevant for megakaryopoiesis while simultaneously repressing programs that induce myeloid differentiation.
2024-03-28 | PXD050401 | Pride
Project description:Molecular mechanisms underlying the megakaryocyte developmental defects caused by the ETV6 p.R369W variant
| PRJNA1310560 | ENA
Project description:Mutations in transcription factor Growth Factor Independence 1B (GFI1B) cause inherited bleedings with varying intensity possibly caused by different effects on the transcriptional function of GFI1B. We studied transcriptomic changes of normal and GFI1BT174N,H181Y,R184P,Q287* mutants in megakaryoblast MEG01 cells using RNA-sequencing. Compared to normal GFI1B each variant affected different gene modules with limited overlap between variants. Remarkably, GFI1BQ287* specifically activated a myeloid-associated gene module. Based on this finding we studied megakaryocyte differentiation using normal and GFI1BQ287* patient-derived induced pluripotent stem cells (IPSC) followed by single cell RNA-sequencing. This revealed a 45-fold decrease in the megakaryocyte/myeloid cell ratio in the GFI1BQ287* versus control condition. Moreover, myeloid specific genes were expressed within GFI1BQ287* but not normal megakaryocytes. Finally, we studied how megakaryocyte development was affected by inhibiting binding of GFI1B to Lysine Specific Demethylase 1 (LSD1), an interaction required for megakaryocyte development. Treatment of both MEG01 cells and normal IPSC-derived developing megakaryocytes with the small-molecule inhibitor GSK-LSD1 resulted in profound activation of myeloid gene programs within megakaryocytes, while the IPSC-derived megakaryocyte/myeloid ratio dropped two-fold. We conclude that GFI1B and LSD1 suppress myeloid differentiation allowing for proper megakaryocyte development. LSD1 inhibitor and GFI1BQ287*-mediated perturbation of this function causes myeloid skewing during megakaryocyte development.
2024-03-28 | GSE244609 | GEO
Project description:Megakaryocytes and platelets arise from hematopoietic stem and progenitor cells through a tightly regulated process involving various transcription factors, including ETS family member FLI1. Pathogenic variants in FLI1, particularly those affecting the ETS DNA-binding domain, have been implicated in inherited thrombocytopenia and are associated with abnormal giant alpha granules, as seen in Paris-Trousseau Syndrome. However, the precise pathophysiological mechanisms remain unclear. Here, we describe a patient with a de novo heterozygous nonsense mutation, FLI1Met100* (c.297del), and investigate its effects on megakaryopoiesis using the Meg01 megakaryoblast cell line as a model. We hypothesized that this variant generates a truncated protein that exerts a dominant-negative effect on megakaryocyte maturation. Western blot analysis confirmed the presence of the truncated protein following FLI1Met100* overexpression in Meg01 cells. To further examine its impact, we overexpressed both wild-type FLI1 (FLI1WT) and FLI1Met100* in Meg01 cells, followed by bulk RNA sequencing and proteomics analysis. Gene set enrichment analysis revealed that FLI1WT enhanced megakaryocytic phenotypes while suppressing erythroid phenotypes, whereas FLI1Met100* upregulated both. Flow cytometry further confirmed that erythroid markers CD235a, CD36, and KLF1 were downregulated by FLI1WT but elevated by FLI1Met100*. Additionally, FLI1WT promoted megakaryocyte maturation and adhesion, as evidenced by increased expression of the megakaryocyte marker CD61 and adhesion markers CD34 and CD44. Moreover, we demonstrated through immunoprecipitation that both FLI1WT and FLI1Met100* interact with shared cofactors. Collectively, our findings suggest that FLI1Met100* impairs megakaryocyte maturation through a dominant-negative manner, potentially contributing to thrombocytopenia by promoting erythroid features at the expense of proper megakaryocytic development.
2025-12-05 | PXD063984 | Pride
Project description:MicroRNAs are small non-coding RNAs that regulate cellular development by interfering with mRNA stability and translation. We defined the kinetics of global microRNA expression during the differentiation of murine hematopoietic progenitors into megakaryocytes. Of 435 miRNAs analyzed, 13 were upregulated and 81 were downregulated. Many of these changes are consistent with miRNA profiling studies of human megakaryocytes and platelets, although new patterns also emerged. Among 7 conserved miRNAs that were upregulated most strongly in megakaryocytes, 6 were also induced in the related erythroid lineage. MiR-146a was strongly upregulated during mouse and human megakaryopoiesis, but not erythropoiesis. However, overexpression of miR-146a in mouse bone marrow hematopoietic progenitor populations produced no detectable alterations in megakaryocyte development or platelet production in vivo or in colony assays. Our findings extend the repertoire of differentially regulated miRNAs during murine megakaryopoiesis and provide a useful new dataset for hematopoiesis research. In addition, we show that enforced hematopoietic expression of miR-146a has minimal effects on megakaryopoiesis. These results are compatible with prior studies indicating that miR-146a inhibits megakaryocyte production indirectly by suppressing cytokine production from innate immune cells, but cast doubt on a different study, which suggests that this miRNA inhibits megakaryopoiesis cell-autonomously.
2010-12-07 | GSE22480 | GEO
Project description:Sp1 and Sp3 belong to the Specificity proteins (Sp)/Krüppel-like transcription factor family. They are closely related, ubiquitously expressed and recognize G-rich DNA motifs. They are thought to regulate generic processes such as cell cycle and growth control, metabolic pathways and apoptosis. Ablation of Sp1 or Sp3 in mice is lethal, and combined haploinsufficiency results in hematopoietic defects during the fetal stages. Here, we show that in adult mice conditional ablation of either Sp1 or Sp3 has minimal impact on hematopoiesis, while the simultaneous loss of Sp1 and Sp3 results in severe macrothrombocytopenia and platelet dysfunction. We employed flow cytometry, cell culture and electron microscopy and show that although megakaryocyte numbers are normal in bone marrow and spleen, they display a less compact demarcation membrane system and a striking inability to form proplatelets. Through megakaryocyte transcriptomics and platelet proteomics we identified several cytoskeleton-related proteins and downstream effector kinases, including Mylk, that were downregulated upon Sp1/Sp3 depletion, providing an explanation for the observed defects in megakaryopoiesis. We show that Mylk is required for proplatelet formation and stabilization and for ITAM-receptor mediated platelet aggregation. Our data highlights the specific vs generic role of these ubiquitous transcription factors in the highly specialized megakaryocytic lineage. Megakaryocyte mRNA profiles of Sp1fl/fl::Sp3fl/fl (WTlox) and Pf4-Cre::Sp1fl/fl::Sp3fl/fl (dKO) mice were generated by deep sequencing, in triplicate.
2014-12-18 | E-GEOD-58707 | biostudies-arrayexpress
Project description:MicroRNAs are small non-coding RNAs that regulate cellular development by interfering with mRNA stability and translation. We defined the kinetics of global microRNA expression during the differentiation of murine hematopoietic progenitors into megakaryocytes. Of 435 miRNAs analyzed, 13 were upregulated and 81 were downregulated. Many of these changes are consistent with miRNA profiling studies of human megakaryocytes and platelets, although new patterns also emerged. Among 7 conserved miRNAs that were upregulated most strongly in megakaryocytes, 6 were also induced in the related erythroid lineage. MiR-146a was strongly upregulated during mouse and human megakaryopoiesis, but not erythropoiesis. However, overexpression of miR-146a in mouse bone marrow hematopoietic progenitor populations produced no detectable alterations in megakaryocyte development or platelet production in vivo or in colony assays. Our findings extend the repertoire of differentially regulated miRNAs during murine megakaryopoiesis and provide a useful new dataset for hematopoiesis research. In addition, we show that enforced hematopoietic expression of miR-146a has minimal effects on megakaryopoiesis. These results are compatible with prior studies indicating that miR-146a inhibits megakaryocyte production indirectly by suppressing cytokine production from innate immune cells, but cast doubt on a different study, which suggests that this miRNA inhibits megakaryopoiesis cell-autonomously. Exiqon locked nucleic acid (LNA) microarrays were used to compare microRNA expression in starting populations (ter 119- progenitors) and purified megakaryocytes. Day13.5-14.5 murine fetal livers (strain CD1) were depleted of erythroid cells and cultured with thrombopoietin to generate megakaryocytes. Each total RNA sample (0.5 μg per reaction) was labeled with Hy3 and Hy5 dyes using the Exiqon Power Labeling Kit and automated microarray hybridizations and washes were performed on a Tecan HS4800 station with 20 hr hybridization at 56ºC. Dye-swap pairs of three replicate experiments comparing Ter119- fetal liver cells vs. BSA-purified megakaryocytes were co-hybridized to six arrays. The geometric average of the 532 and 635 measurements after normalization was determined for each sample.
2010-12-07 | E-GEOD-22480 | biostudies-arrayexpress
Project description:Expression of the RNA-binding protein is increased upon megakaryocyte commitment, and may coordinate with mRNA stability and translation during megakaryopoiesis. Reduced expression of ATXN2 in human megakaryocytic cells decreased protein synthesis and total protein content despite equal mRNA expression. Genome-wide comparision of subpolysomal versus polysomal mRNA showed that both protein synthesis and protein degradation are derailed in absence of ATXN2. Furthermore, ATXN2 was associated with PABP and DDX6, proteins that control mRNA stability through the polyA-tail. These findings indicate that ATXN2 is involved in protein metabolism in megakaryocytes and platelet function.
2014-12-31 | GSE63297 | GEO
Project description:To determine the protein partners of ETV6, we expressed ETV6 and HA-tagged ETV6 in Reh pre-B leukemic cells. Anti-HA magnetic beads were used for affinity purification of ETV6-HA (and ETV6 control) from the nuclear and cytoplasmic fraction. Following purification on-beads digest and LC-MS/MS experiments were performed at the Proteomics platform of the CHU de Quebec Research Center, Quebec, Canada.
2022-01-26 | PXD031001 | Pride
Project description:Megakaryopoiesis is a complex process that involves major cellular changes and relies on controlled coordination of cellular proliferation and differentiation. These mechanisms are orchestrated in part by transcriptional regulators. The key hematopoietic transcription factor SCL/TAL1 is required for specification of the megakaryocytic lineage from hematopoietic progenitors. Here, we report that it also critically controls terminal megakaryocyte maturation. In vivo depletion of SCL specifically in the megakaryocytic lineage affects all key attributes of megakaryocyte progenitors (MkPs), namely proliferation, ploidisation, cytoplasmic maturation, as well as platelet production. Genome-wide expression analysis reveals increased expression of the cell cycle regulator p21 in Scl-deleted MkPs. Importantly, P21 knockdown-mediated rescue assays in Scl-deleted MkPs show full restoration of cell cycle progression and partial rescue of the nuclear and cytoplasmic maturation defects. Therefore, SCL-mediated transcriptional control of p21 is critical for maturation of MkPs. Our study provides a mechanistic link between one of the major hematopoietic transcriptional regulators, cell cycle progression and megakaryocytic differentiation. Total RNA extracted from control TGPF4-CRE;SCL wt/wt sorted MK progenitors was compared to total RNA extracted from TGPF4-CRE;SCL fl/fl MK progenitors cells where Scl was completely excised
2011-07-11 | E-GEOD-24969 | biostudies-arrayexpress