RNA Binding Protein SRSF3 confers an essential role in megakaryocyte maturation and platelet production
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE155620 | GEO | 2021/12/21
REPOSITORIES: GEO
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Project description:RNA processing is increasingly recognized as a critical control point in the regulation of different hematopoietic lineages including megakaryocytes responsible for the production of platelets. Platelets are anucleate cytoplasts that contain a rich repertoire of RNAs encoding proteins with essential platelet functions derived from the parent megakaryocyte. It is largely unknown how RNA binding proteins contribute to the development and functions of megakaryocytes and platelets. We show that serine-arginine-rich splicing factor 3 (SRSF3) is essential for megakaryocyte maturation and generation of functional platelets. Megakaryocyte-specific deletion of Srsf3 in mice led to macrothrombocytopenia characterized by megakaryocyte maturation arrest, dramatically reduced platelet counts, and abnormally large functionally compromised platelets. SRSF3 deficient megakaryocytes failed to reprogram their transcriptome during maturation and to load platelets with RNAs required for normal platelet function. SRSF3 depletion led to nuclear accumulation of megakaryocyte mRNAs, demonstrating that SRSF3 deploys similar RNA regulatory mechanisms in megakaryocytes as in other cell types. Our study further suggests that SRSF3 plays a role in sorting cytoplasmic megakaryocyte RNAs into platelets and demonstrates how SRSF3-mediated RNA processing forms a central part of megakaryocyte gene regulation. Understanding SRSF3 functions in megakaryocytes and platelets provides key insights into normal thrombopoiesis and platelet pathologies as SRSF3 RNA targets in megakaryocytes are associated with platelet diseases.
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Project description:RNA Binding Protein SRSF3 confers an essential role in megakaryocyte maturation and platelet production
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Project description:RNA-seq expression analysis of transcripts encoding proteasome subunits in human CD34+ cord blood cell-derived megakaryocytes and mouse bone marrow-derived megakaryocytes. Analysis of transcript expression in human CD34+ cord blood cell-derived megakaryocytes and mouse bone marrow-derived megakaryocytes.
2015-01-31 | E-GEOD-58202 | biostudies-arrayexpress
Project description:Dnm2fl/fl Pf4-Cre (Dnm2Plt-/-) mice lacking the endocytic GTPase dynamin 2 (DNM2) in platelets and megakaryocytes (MKs) develop hallmarks of myelofibrosis. At the cellular level, the tyrosine kinase JAK2 is constitutively active but decreased in expression in Dnm2Plt-/- platelets. Additionally, Dnm2Plt-/- platelets cannot endocytose the thrombopoietin (TPO) receptor Mpl, leading to elevated circulating TPO levels. Here, we assessed whether the hyperproliferative phenotype of Dnm2Plt-/- mice was due to JAK2 constitutive activation or elevated circulating TPO levels. In unstimulated Dnm2Plt-/- platelets, STAT3 and to a lower extent STAT5 were phosphorylated, but their phosphorylation was slowed and diminished upon TPO stimulation. We further crossed Dnm2Plt-/- mice in the Mpl-/- background to generate Mpl-/- Dnm2Plt-/- mice lacking Mpl ubiquitously and DNM2 in platelets and MKs. Mpl-/- Dnm2Plt-/- platelets had severely reduced JAK2 and STAT3 but normal STAT5 expression. Mpl-/- Dnm2Plt-/- mice had severely reduced bone marrow MK and hematopoietic stem and progenitor cell numbers. Additionally, Mpl-/- Dnm2Plt-/- mice had severe erythroblast maturation defects, decreased expression of hemoglobin and heme homeostasis genes, increased expression of ribosome biogenesis and protein translation genes, and developed anemia with grossly elevated plasma erythropoietin levels, leading to early fatality by postnatal day 25. Mpl-/- Dnm2Plt+/+ mice had impaired EB development at three weeks of age, which normalized with adulthood. Together, the data shows that DNM2-dependent Mpl-mediated endocytosis in platelets and MKs is required for steady-state hematopoiesis and provides novel insights into a developmentally controlled role for Mpl in normal erythropoiesis, regulating hemoglobin and heme production.
2022-08-25 | GSE206343 | GEO
Project description:The aim of the project is to identify the genes in megakaryocytes whose expression is modified upon 3D methylcellulose hydrogel culture compared to liquid culture. Megakaryocytes are the precursor cells of platelets. We previously showed that growing megakaryocytes in 3D hydrogel strongly modifies their differentiation and their morphology, being closer to the one in situ. We were thus interested into identifying these mechanobiological pathways induced by the confinement. We found that 3D culture notably upregulated genes related to the Rho GTPase pathway.
2024-08-20 | GSE264159 | GEO
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:The final stages of of megakaryocyte (MK) maturation involve a series of steps, including polyploidization and proplatelet formation. Although these processes are highly dependent on dynamic changes in the microtubule (MT) cytoskeleton, the mechanisms responsible for regulation of MTs in MKs remain poorly defined. Stathmin is a highly conserved MT-regulatory protein that has been suggested to play a role in MK differentiation of human leukemic cell lines. However, previous studies defining this relationship have reached contradictory conclusions. In this study, we addressed this controversy and investigated the role of stathmin in primary human MKs. To explore the importance of stathmin down-regulation during megakaryocytopoiesis, we used a lentiviral-mediated gene delivery system to prevent physiologic down-regulation of stathmin in primary MKs. We demonstrated that sustained expression of constitutively active stathmin delayed cytoplasmic maturation (ie, glycoprotein GPIb and platelet factor 4 expression) and reduced the ability of MKs to achieve high levels of ploidy. Moreover, platelet production was impaired in MKs in which down-regulation of stathmin expression was prevented. These studies indicate that suppression of stathmin is biologically important for MK maturation and platelet production and support the importance of MT regulation during the final stages of thrombopoiesis.
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Project description:RNA-seq expression analysis of transcripts encoding proteasome subunits in human CD34+ cord blood cell-derived megakaryocytes and mouse bone marrow-derived megakaryocytes.
2015-01-31 | GSE58202 | GEO
Project description:During maturation, megakaryocytes (MKs) express ?1-tubulin (TUBB1) and rearrange their microtubule components to enlarge, form proplatelets, and eventually release platelets. The development of a platform to identify in vitro conditions that would efficiently promote MK development could potentially enable large-scale platelet production. Here, we show that an immortalized MK cell line (imMKCL) genetically modified to express the ?1-tubulin-Venus reporter provides a practical system to efficiently monitor the in vitro production of platelet-like particles (PLPs). The Venus transgene was inserted downstream of the TUBB1 locus in imMKCLs using CRISPR/Cas9, and the expression was visualized by Venus fluorescence intensity. This imMKCL reporter line was then used for high-throughput drug screening. We identified several compounds that significantly improved the efficiency of PLP production in vitro under feeder-free conditions and showed a significant tendency to recover platelets in vivo in a mouse thrombocytopenia model induced by anti-GPIb? antibody administration. Interestingly, most of these compounds, including a WNT signaling pathway inhibitor, Wnt-C59, antagonized the aryl hydrocarbon receptor (AhR) to increase PLP production, confirming the crucial role of AhR inhibition in MK maturation. Consistently, small interfering RNA treatment against AhR increased the Venus intensity and PLP production. TCS 359, an FLT3 inhibitor, significantly increased PLP production independently of FLT3 or AhR. This study highlights the usefulness of the ?1-tubulin reporter MK line as a useful tool to study the mechanisms underlying thrombopoiesis and to identify novel inducers of ex vivo platelet production.
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Project description:Circulating nucleic acids are present in plasma and are derived from a range of cell types, mainly cells of hematopoietic origin, enabling their use as biomarkers for diseases involving these cell types. Using cell type-specific methylation markers, we determined that megakaryocytes are major contributors to cfDNA (~26%), while erythroblasts contribute 1-4% of cfDNA in healthy individuals. Additionally, we identified megakaryocyte-derived DNA within platelets, providing non-invasive access to the megakaryocyte genome and epigenome. Analysis of cfDNA in women who have received male platelet transfusions indicates that megakaryocyte-derived cfDNA does not originate from platelets but is rather released directly from megakaryocytes. The concentration of megakaryocyte-derived cfDNA is elevated in individuals with pathologies involving increased platelet production (Essential Thrombocythemia, Idiopathic Thrombocytopenic Purpura) and decreased by bone marrow suppression (due to chemotherapy), while erythrocyte progenitor cfDNA is elevated in patients with Thalassemia. Megakaryocyte- and erythroblast-specific DNA methylation patterns may serve as novel biomarkers for pathologies involving increased or decreased thrombopoiesis and erythropoiesis.
2022-10-12 | GSE206818 | GEO