The RNA-binding protein ATXN2 controls cellular processes during megakaryopoiesis.
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE131308 | GEO | 2020/02/14
REPOSITORIES: GEO
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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: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: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:Platelets have a wide range of functions including critical roles in hemostasis, thrombosis, and immunity. We hypothesized that during acute inflammation, such as in life-threatening sepsis, there are fundamental changes in the sites of platelet production and phenotypes of resultant platelets. Here, we showed during sepsis that the spleen is a major site of megakaryopoiesis and platelet production. Sepsis provoked an adrenergic-dependent mobilization of megakaryocyte-erythrocyte progenitors (MEPs) from the bone marrow to the spleen where interleukin-3 (IL-3) induced their differentiation into megakaryocytes. In the spleen, immune-skewed megakaryocytes produced a CD40L-high platelet population with potent immunomodulatory functions. Transfusions of post-sepsis platelets enriched from splenic production enhanced immune responses and reduced overall mortality in sepsis-challenged animals. These findings identify a spleen-derived protective platelet population that may be broadly immunomodulatory in acute inflammatory states such as sepsis.
2022-02-14 | GSE196607 | 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: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:Srf is a MADS-box transcription factor that is critical for muscle differentiation. Its function in hematopoiesis has not yet been revealed. Mkl1, a cofactor of Srf, is part of the t(1;22) translocation in acute megakaryoblastic leukemia, and plays a critical role in megakaryopoiesis. In order to test the role of Srf in megakaryocyte development, we crossed Pf4-Cre mice, which express Cre recombinase in cells committed to the megakaryocytic lineage, to SrfF/F mice in which functional Srf is no longer expressed after Cre-mediated excision. Pf4-Cre/SrfF/F (KO) mice are born with normal mendelian frequency, but have significant macrothrombocytopenia with approximately 50% reduction in platelet count. In contrast, the BM has increased numbers and percentages of CD41+ megakaryocytes (WT: 0.41+/-0.06%; KO: 1.92+/-0.12%) with significantly reduced ploidy. KO mice show significantly increased megakaryocyte progenitors in the BM by both FACS analysis and CFU-Mk. Megakaryocytes lacking Srf have abnormal stress fiber and demarcation membrane formation and platelets lacking Srf have abnormal actin distribution. In vitro and in vivo assays reveal platelet function defects in KO mice. Critical actin cytoskeletal genes are downregulated in KO megakaryocytes. Thus, Srf is required for normal megakaryocyte maturation and platelet production, due at least in part, to regulation of cytoskeletal genes. C-kit+CD41+ megakaryocyte progenitors from PF4-Cre/SRF C57BL/6 SRF WT (3) and C57BL/6 SRF KO (3) mice were sorted by flow cytometry and cultured for three days in thrombopoietin.
2010-07-13 | E-GEOD-21859 | 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: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: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