FLI1 and GATA1 govern TLN1 transcription: new insights into FLI1-related platelet disorders
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE273210 | GEO | 2025/03/31
REPOSITORIES: GEO
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Project description:The Stem Cell Leukemia (Scl or Tal1) protein forms part of a multimeric transcription factor complex required for normal megakaryopoiesis. However, unlike other members of this complex such as Gata1, Fli1 and Runx1, mutations of Scl have not been observed as a cause of inherited thrombocytopenia. We postulated that functional redundancy with its closely related family member, Lymphoblastic Leukemia 1 (Lyl1) might explain this observation. To determine if Lyl1 can substitute for Scl in megakaryopoiesis, we examined the platelet phenotype of mice lacking one or both factors in megakaryocytes. Conditional Scl knockout mice crossed with transgenic mice expressing Cre recombinase under the control of the mouse platelet factor 4 (Pf4) promoter generated megakaryocytes with markedly reduced but not absent Scl. These Pf4SclcKO mice had mild thrombocytopenia and subtle defects in platelet aggregation. However, Pf4SclcKO mice generated on a Lyl1-null background (double knockout, DKO mice) had severe macrothrombocytopenia, abnormal megakaryocyte morphology, defective pro-platelet formation and markedly impaired platelet aggregation. DKO megakaryocytes, but not single knockouts, had reduced expression of Gata1, Fli1, Nfe2 and many other genes that cause inherited thrombocytopenia. These gene expression changes were significantly associated with shared Scl and Lyl1 E-box binding sites that were also enriched for Gata1, Ets and Runx1 motifs. Thus, Scl and Lyl1 share functional roles in platelet production and function by regulating expression of partner proteins including Gata1 and Fli1. We propose that this functional redundancy provides one explanation for the absence of Scl and Lyl1 mutations as a cause of inherited thrombocytopenia.
2020-12-21 | GSE125025 | GEO
Project description:Thioredoxin-interacting protein (TXNIP) is ubiquitously expressed in blood cells, including hematopoietic stem cells (HSCs), monocytes, and platelets. Here we report a novel finding that TXNIP plays a crucial role in megakaryopoiesis and platelet biogenesis via interacting with GATA1, a transcription factor for megakaryocyte-erythroid differentiation. Txnip-/- mice displayed immature megakaryocytes in the bone marrow with thrombocytopenia, which had gotten worse as the mice aged. Transcriptome analysis revealed that the transcriptional activity of GATA1 was significantly enhanced in the Txnip-/- megakaryocyte precursors (MkPs) than wild type (WT) cells. During megakaryopoiesis in ex vivo, Txnip-/- MkPs remained small in cell size with less mitochondrial mass, and more glycolysis for ATP production, as opposed to the normal megakaryocyte maturation. The effects of TXNIP in megakaryocytes were recapitulated in human cord blood CD34+ HSC-derived differentiation. Taken together, this study demonstrates the importance of spatiotemporal expression of TXNIP in platelet biogenesis. We propose for the first time that TXNIP might play a critical role in determining a lineage between megakaryocytes and erythroid cells from a common megakaryocyte-erythroid progenitor via regulation of transcriptional activity of GATA1.
2022-12-31 | GSE186400 | GEO
Project description:FLI1 and GATA1 govern TLN1 transcription: new insights into FLI1-related platelet disorders
| PRJNA1140608 | ENA
Project description:The hematopoietic system gives rise to a heterogeneous population of terminally differentiated cells that reside in the bone marrow (BM) to fulfill their roles in immunity, blood clotting and tissue oxygenation. Hematopoietic stem and progenitor cells are at the apex of a hierarchically organized maturation cascade constantly replenishing the pool of differentiated cells to maintain blood cell homeostasis. The bone marrow microenvironment is functionally compartmentalized by heterogeneous niche cells that provide physical and soluble signals to spatio-temporally organize hematopoiesis. Megakaryocytes (MKs) are niche cells of hematopoietic origin that support hematopoietic stem cell (HSCs) homeostasis and generate circulating platelets. Platelet production involves the release of MK fragments while their cell body is entirely consumed in a process termed thrombopoiesis. Consequently, replenishment of fragmented MKs from MK progenitors (termed megakaryopoiesis) is required to ensure sufficient platelet production, but also to maintain MK homeostasis within the HSC niche. Here, we used intravital imaging of the megakaryocytic lineage to identify the spatio-temporal patterns of megakaryopoiesis during steady state and thrombocytopenia. We show that MK consumption during thrombopoiesis is compensated by immediate and local proliferation of MK progenitors. MK homeostasis is controlled by plasmacytoid dendritic cells (pDCs) that scan the BM and secrete Interferon alpha (INFa) upon detection of exhausted megakaryocytes to trigger megakaryopoiesis. We identified local pDC-derived INFa release as a physiological inflammatory stimulus of the bone marrow niche that synchronizes megakaryopoiesis and thrombopoiesis to maintain homeostasis of MKs and platelets in steady state and under stress. Viral infection with SARS-CoV-2 can manipulate pDC-driven MK proliferation leading to inappropriate megakaryopoiesis, which has been associated with thrombotic complications during COVID-19.
2024-04-26 | GSE185488 | GEO
Project description:Megakaryocytes accumulate mRNA during their maturation, which is required for the correct spatio-temporal production of cytoskeletal proteins, membranes and platelet-specific granules, and for the subsequent shedding of thousands of platelets per cell. Gene expression profiling identified the RNA binding protein ATAXIN2 (ATXN2) as a putative novel regulator of megakaryopoiesis. ATXN2 expression is high in CD34+/CD41+ megakaryoblasts and sharply decreases upon maturation to megakaryocytes. ATXN2 associates with DDX6 suggesting that it may mediate repression of mRNA translation during early megakaryopoiesis. Comparative transcriptome and proteome analysis on megakaryoid cells (MEG-01) with differential ATXN2 expression identified ATXN2 dependent gene expression of mRNA and protein involved in processes linked to coagulation. Mice deficient for Atxn2 did not display differences in bleeding times, but expression of key surface receptors on platelets, such as ITGB3 (carries the CD61 antigen) and CD31 (PECAM1), were deregulated and platelet aggregation was reduced upon specific triggers.
2020-05-26 | PXD015823 | Pride
Project description:Megakaryocytes accumulate mRNA during their maturation, which is required for the correct spatio-temporal production of cytoskeletal proteins, membranes and platelet-specific granules, and for the subsequent shedding of thousands of platelets per cell. Gene expression profiling identified the RNA binding protein ATAXIN2 (ATXN2) as a putative novel regulator of megakaryopoiesis. ATXN2 expression is high in CD34+/CD41+ megakaryoblasts and sharply decreases upon maturation to megakaryocytes. ATXN2 associates with DDX6 suggesting that it may mediate repression of mRNA translation during early megakaryopoiesis. Comparative transcriptome and proteome analysis on megakaryoid cells (MEG-01) with differential ATXN2 expression identified ATXN2 dependent gene expression of mRNA and protein involved in processes linked to coagulation. Mice deficient for Atxn2 did not display differences in bleeding times, but expression of key surface receptors on platelets, such as ITGB3 (carries the CD61 antigen) and CD31 (PECAM1), were deregulated and platelet aggregation upon specific triggers was reduced.
2020-02-14 | GSE131308 | GEO
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:Dominant-negative mutations in transcription factor Growth Factor Independence-1B (GFI1B) cause a bleeding disorder characterized by a plethora of megakaryocyte and platelet abnormalities. The deregulated molecular mechanisms and pathways are unknown. Here we show that normal and mutant GFI1B interacted most strongly with the LSD1-RCOR-HDAC corepressor complex in megakaryoblasts. Sequestration of this complex by mutant GFI1B and chemical separation of GFI1B from LSD1 induced abnormalities in normal megakaryocytes comparable to those seen in patients. Megakaryocytes derived from GFI1B-mutant induced pluripotent stem cells (iPSC) also phenocopied abnormalities seen in patients. Proteome studies on normal and mutant iPSC-derived megakaryocytes identified a multitude of deregulated pathways downstream of mutant GFI1B. Proteome studies on primary normal and GFI1B-mutant platelets showed reduced expression of proteins implicated in platelet function, and sustained expression of proteins normally downregulated during megakaryocyte differentiation. Thus, GFI1B regulates a broad developmental program during megakaryopoiesis. Mutant GFI1B deregulates this program through LSD1-RCOR-HDAC sequestering.
2019-01-25 | PXD009020 | Pride
Project description:We have mapped the binding sites for the five key regulators GATA1, GATA2, RUNX1, FLI1 and TAL1/SCL in primary human megakaryocytes. Statistical analysis identified subsets of enriched as well as depleted combinatorial binding patterns. In particular simultaneous binding by all 5 factors was highly enriched and occurred in the vicinity of many genes known to be involved in blood and megakaryocyte development. Knock down in zebrafish of 8 of these genes with no previously known role in hematopoiesis, revealed all to be essential for thrombocyte and/or erythroid development. Combinatorial analysis of multi-factor ChIP-Seq datasets coupled with a high-throughput in vivo screen therefore offers a powerful strategy to identify novel essential regulators of complex mammalian differentiation processes. 5 transcription factors and rabbit-IgG in megakaryocytes.
2011-06-01 | E-GEOD-24674 | biostudies-arrayexpress
Project description:Embryonic stem (ES) and induced pluripotent stem (iPS) cells represent a potential source of megakaryocytes and platelets for transfusion therapies. However, most current ES/iPS cell differentiation protocols are limited by low yields of hematopoietic progeny. Mutations in the mouse and human genes encoding transcription factor GATA1 cause accumulation of proliferating, developmentally arrested megakaryocytes. To exploit this clinical observation, we engineered wildtype (WT) murine ES cells to express doxycycline (dox)-regulated Gata1 short hairpin (sh) RNAs. In vitro differentiation with dox and thrombopoietin (Tpo) resulted in approximately 1013-fold expansion of immature hematopoietic progenitors. Upon dox withdrawal with multilineage cytokines, GATA1 expression was restored and the cells differentiated into erythroblasts and megakaryocytes. With Tpo alone, dox-deprived progenitors formed mainly mature megakaryocytes that generated functional platelets in vivo. Our findings provide a novel, readily reproducible strategy to expand ES-cell derived megakaryocyte-erythroid progenitors and direct their differentiation into megakaryocytes producing functional platelets in clinically relevant numbers. 3 classes of samples were compared 1) fetal liver derived megkaryocytes 2) G1ME (Gata1â megakaryocyte-erythroid) 3) G1ME2 (engineered wildtype (WT) murine ES cells to express doxycycline (dox)-regulated Gata1 short hairpin (sh) RNAs)
2015-12-09 | E-GEOD-66479 | biostudies-arrayexpress