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Nature Communications Nov 2023Circulating cell-free DNA (cfDNA) fragments are a biological analyte with extensive utility in diagnostic medicine. Understanding the source of cfDNA and mechanisms of...
Circulating cell-free DNA (cfDNA) fragments are a biological analyte with extensive utility in diagnostic medicine. Understanding the source of cfDNA and mechanisms of release is crucial for designing and interpreting cfDNA-based liquid biopsy assays. Using cell type-specific methylation markers as well as genome-wide methylation analysis, we determine that megakaryocytes, the precursors of anuclear platelets, are major contributors to cfDNA (~26%), while erythroblasts contribute 1-4% of cfDNA in healthy individuals. Surprisingly, we discover that platelets contain genomic DNA fragments originating in megakaryocytes, contrary to the general understanding that platelets lack genomic DNA. Megakaryocyte-derived cfDNA is increased in pathologies involving increased platelet production (Essential Thrombocythemia, Idiopathic Thrombocytopenic Purpura) and decreased upon reduced platelet production due to chemotherapy-induced bone marrow suppression. Similarly, erythroblast cfDNA is reflective of erythrocyte production and is elevated in patients with thalassemia. Megakaryocyte- and erythroblast-specific DNA methylation patterns can thus serve as biomarkers for pathologies involving increased or decreased thrombopoiesis and erythropoiesis, which can aid in determining the etiology of aberrant levels of erythrocytes and platelets.
Topics: Humans; Megakaryocytes; Thrombopoiesis; Erythropoiesis; Cell-Free Nucleic Acids; Blood Platelets; Erythroblasts; DNA
PubMed: 37985773
DOI: 10.1038/s41467-023-43310-2 -
Expert Reviews in Molecular Medicine Oct 2011Megakaryopoiesis is the process by which bone marrow progenitor cells develop into mature megakaryocytes (MKs), which in turn produce platelets required for normal... (Review)
Review
Megakaryopoiesis is the process by which bone marrow progenitor cells develop into mature megakaryocytes (MKs), which in turn produce platelets required for normal haemostasis. Over the past decade, molecular mechanisms that contribute to MK development and differentiation have begun to be elucidated. In this review, we provide an overview of megakaryopoiesis and summarise the latest developments in this field. Specially, we focus on polyploidisation, a unique form of the cell cycle that allows MKs to increase their DNA content, and the genes that regulate this process. In addition, because MKs have an important role in the pathogenesis of acute megakaryocytic leukaemia and a subset of myeloproliferative neoplasms, including essential thrombocythemia and primary myelofibrosis, we discuss the biology and genetics of these disorders. We anticipate that an increased understanding of normal MK differentiation will provide new insights into novel therapeutic approaches that will directly benefit patients.
Topics: Animals; Cell Differentiation; Humans; Leukemia, Megakaryoblastic, Acute; Megakaryocytes; Myeloproliferative Disorders; Primary Myelofibrosis; Thrombocytosis; Thrombopoiesis
PubMed: 22018018
DOI: 10.1017/S1462399411002043 -
Proceedings of the National Academy of... Nov 2022Platelets play a role not only in hemostasis and thrombosis, but also in inflammation and innate immunity. We previously reported that an activated form of tyrosyl-tRNA...
Platelets play a role not only in hemostasis and thrombosis, but also in inflammation and innate immunity. We previously reported that an activated form of tyrosyl-tRNA synthetase (YRS) has an extratranslational activity that enhances megakaryopoiesis and platelet production in mice. Here, we report that YRS mimics inflammatory stress inducing a unique megakaryocyte (MK) population with stem cell (Sca1) and myeloid (F4/80) markers through a mechanism dependent on Toll-like receptor (TLR) activation and type I interferon (IFN-I) signaling. This mimicry of inflammatory stress by YRS was studied in mice infected by lymphocytic choriomeningitis virus (LCMV). Using Sca1/EGFP transgenic mice, we demonstrated that IFN-I induced by YRS or LCMV infection suppressed normal hematopoiesis while activating an alternative pathway of thrombopoiesis. Platelets of inflammatory origin (Sca1/EGFP) were a relevant proportion of those circulating during recovery from thrombocytopenia. Analysis of these "inflammatory" MKs and platelets suggested their origin in myeloid/MK-biased hematopoietic stem cells (HSCs) that bypassed the classical MK-erythroid progenitor (MEP) pathway to replenish platelets and promote recovery from thrombocytopenia. Notably, inflammatory platelets displayed enhanced agonist-induced activation and procoagulant activities. Moreover, myeloid/MK-biased progenitors and MKs were mobilized from the bone marrow, as evidenced by their presence in the lung microvasculature within fibrin-containing microthrombi. Our results define the function of YRS in platelet generation and contribute to elucidate platelet alterations in number and function during viral infection.
Topics: Mice; Animals; Thrombopoiesis; Tyrosine-tRNA Ligase; Thrombocytopenia; Virus Diseases; Thrombosis; Mice, Transgenic; Spinocerebellar Ataxias
PubMed: 36409883
DOI: 10.1073/pnas.2212659119 -
International Journal of Molecular... Mar 2023Protein glycosylation, including sialylation, involves complex and frequent post-translational modifications, which play a critical role in different biological... (Review)
Review
Protein glycosylation, including sialylation, involves complex and frequent post-translational modifications, which play a critical role in different biological processes. The conjugation of carbohydrate residues to specific molecules and receptors is critical for normal hematopoiesis, as it favors the proliferation and clearance of hematopoietic precursors. Through this mechanism, the circulating platelet count is controlled by the appropriate platelet production by megakaryocytes, and the kinetics of platelet clearance. Platelets have a half-life in blood ranging from 8 to 11 days, after which they lose the final sialic acid and are recognized by receptors in the liver and eliminated from the bloodstream. This favors the transduction of thrombopoietin, which induces megakaryopoiesis to produce new platelets. More than two hundred enzymes are responsible for proper glycosylation and sialylation. In recent years, novel disorders of glycosylation caused by molecular variants in multiple genes have been described. The phenotype of the patients with genetic alterations in and is consistent with syndromic manifestations, severe inherited thrombocytopenia, and hemorrhagic complications.
Topics: Humans; Glycosylation; Thrombocytopenia; Blood Platelets; Megakaryocytes; Thrombopoiesis; Thrombopoietin; Nucleotide Transport Proteins
PubMed: 36982178
DOI: 10.3390/ijms24065109 -
Blood May 2011MicroRNAs are small RNA molecules that modulate protein expression by degrading mRNA or repressing translation. They have been shown to play important roles in... (Review)
Review
MicroRNAs are small RNA molecules that modulate protein expression by degrading mRNA or repressing translation. They have been shown to play important roles in hematopoiesis, including embryonic stem cell differentiation, erythropoiesis, granulocytopoiesis/monocytopoiesis, lymphopoiesis, and megakaryocytopoiesis. miR-150 and miR-155 play divergent roles in megakaryocytopoiesis, with the former promoting development of megakaryocytes at the expense of erythrocytes and the latter causing a reduction in megakaryocyte colony formation. Platelets also contain fully functional miRNA machinery, and certain miRNA levels in platelets have been found to coordinate with reactivity to specific agonists and to pathologic states. This review will cover the current state of knowledge of miRNAs in megakaryocytes and platelets and the exciting possibilities for future research.
Topics: Animals; Blood Platelets; Humans; Megakaryocytes; MicroRNAs; Models, Biological; Platelet Activation; Thrombopoiesis
PubMed: 21364189
DOI: 10.1182/blood-2011-01-292011 -
Platelets Dec 2023Noncoding RNAs (ncRNAs) are a group of RNA molecules that cannot encode proteins, and a better understanding of the complex interaction networks coordinated by ncRNAs... (Review)
Review
Noncoding RNAs (ncRNAs) are a group of RNA molecules that cannot encode proteins, and a better understanding of the complex interaction networks coordinated by ncRNAs will provide a theoretical basis for the development of therapeutics targeting the regulatory effects of ncRNAs. Platelets are produced upon the differentiation of hematopoietic stem cells into megakaryocytes, 10 per day, and are renewed every 8-9 days. The process of thrombopoiesis is affected by multiple factors, in which ncRNAs also exert a significant regulatory role. This article reviewed the regulatory roles of ncRNAs, mainly microRNAs (miRNAs), circRNAs (circular RNAs), and long non-coding RNAs (lncRNAs), in thrombopoiesis in recent years as well as their roles in primary immune thrombocytopenia (ITP).
Topics: Humans; Thrombopoiesis; Blood Platelets; Megakaryocytes; MicroRNAs; RNA, Untranslated
PubMed: 36550091
DOI: 10.1080/09537104.2022.2157382 -
Blood Mar 2016Thrombocytopenia is defined as a status in which platelet numbers are reduced. Imbalance between the homeostatic regulation of platelet generation and destruction is 1... (Review)
Review
Thrombocytopenia is defined as a status in which platelet numbers are reduced. Imbalance between the homeostatic regulation of platelet generation and destruction is 1 potential cause of thrombocytopenia. In adults, platelet generation is a 2-stage process entailing the differentiation of hematopoietic stem cells into mature megakaryocytes (MKs; known as megakaryopoiesis) and release of platelets from MKs (known as thrombopoiesis or platelet biogenesis). Until recently, information about the genetic defects responsible for congenital thrombocytopenia was only available for a few forms of the disease. However, investigations over the past 15 years have identified mutations in genes encoding >20 different proteins that are responsible for these disorders, which has advanced our understanding of megakaryopoiesis and thrombopoiesis. The underlying pathogenic mechanisms can be categorized as (1) defects in MK lineage commitment and differentiation, (2) defects in MK maturation, and (3) defect in platelet release. Using these developmental stage categories, we here update recently described mechanisms underlying megakaryopoiesis and thrombopoiesis and discuss the association between platelet generation systems and thrombocytopenia.
Topics: Adult; Animals; Genetic Diseases, Inborn; Hematopoietic Stem Cells; Humans; Megakaryocytes; Mutation; Thrombocytopenia; Thrombopoiesis
PubMed: 26787737
DOI: 10.1182/blood-2015-07-607903 -
Platelets Dec 2023Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal... (Review)
Review
Inherited thrombocytopenia (IT) is a group of hereditary disorders characterized by a reduced platelet count as the main clinical manifestation, and often with abnormal platelet function, which can subsequently lead to impaired hemostasis. In the past decades, humanized mouse models (HMMs), that are mice engrafted with human cells or genes, have been widely used in different research areas including immunology, oncology, and virology. With advances of the development of immunodeficient mice, the engraftment, and reconstitution of functional human platelets in HMM permit studies of occurrence and development of platelet disorders including IT and treatment strategies. This article mainly reviews the development of humanized mice models, the construction methods, research status, and problems of using humanized mice for the study of human thrombopoiesis.
Topics: Animals; Mice; Humans; Disease Models, Animal; Blood Platelets; Thrombopoiesis; Thrombocytopenia; Blood Platelet Disorders; Hematopoietic Stem Cell Transplantation
PubMed: 37849076
DOI: 10.1080/09537104.2023.2267676 -
International Journal of Molecular... May 2023Megakaryocytes are the main members of the hematopoietic system responsible for regulating vascular homeostasis through their progeny platelets, which are generally... (Review)
Review
Megakaryocytes are the main members of the hematopoietic system responsible for regulating vascular homeostasis through their progeny platelets, which are generally known for maintaining hemostasis. Megakaryocytes are characterized as large polyploid cells that reside in the bone marrow but may also circulate in the vasculature. They are generated directly or through a multi-lineage commitment step from the most primitive progenitor or Hematopoietic Stem Cells (HSCs) in a process called "megakaryopoiesis". Immature megakaryocytes enter a complicated development process defined as "thrombopoiesis" that ultimately results in the release of extended protrusions called proplatelets into bone marrow sinusoidal or lung microvessels. One of the main mediators that play an important modulatory role in hematopoiesis and hemostasis is nitric oxide (NO), a free radical gas produced by three isoforms of nitric oxide synthase within the mammalian cells. In this review, we summarize the effect of NO and its signaling on megakaryopoiesis and thrombopoiesis under both physiological and pathophysiological conditions.
Topics: Animals; Megakaryocytes; Nitric Oxide; Blood Platelets; Thrombopoiesis; Hematopoietic Stem Cells; Mammals
PubMed: 37175857
DOI: 10.3390/ijms24098145 -
Journal of Thrombosis and Haemostasis :... Aug 2005Megakaryocytes (MKs) expand and differentiate over several days in response to thrombopoietin (Tpo) before releasing innumerable blood platelets. The final steps in... (Review)
Review
Megakaryocytes (MKs) expand and differentiate over several days in response to thrombopoietin (Tpo) before releasing innumerable blood platelets. The final steps in platelet assembly and release represent a unique cellular transformation that is orchestrated by a range of transcription factors, signaling molecules, and cytoskeletal elements. Here we review recent advances in the physiology and molecular basis of MK differentiation. Genome-wide approaches, including transcriptional profiling and proteomics, have been used to identify novel platelet products and differentiation markers. The extracellular factors, stromal-derived factor (SDF)-1 chemokine and fibroblast growth factor (FGF)-4 direct MK interactions with the bone marrow stroma and regulate cytokine-independent cell maturation. An abundance of bone marrow MKs induce pathologic states, including excessive bone formation and myelofibrosis, and the basis for these effects is now better appreciated. We review the status of transcription factors that control MK differentiation, with special emphasis on nuclear factor-erythroid 2 (NF-E2) and its two putative target genes, beta1-tubulin and 3-beta-hydroxysteroid reductase. MKs express steroid receptors and some estrogen ligands, which may constitute an autocrine loop in formation of proplatelets, the cytoplasmic protrusions within which nascent blood platelets are assembled. Finally, we summarize our own studies on cellular and molecular facets of proplatelet formation and place the findings within the context of outstanding questions about mechanisms of thrombopoiesis.
Topics: Animals; Blood Platelets; Cell Differentiation; Chemokine CXCL12; Chemokines, CXC; Cytoplasm; Genome; Humans; Megakaryocytes; Microtubules; Protein Binding; Proteomics; Signal Transduction; Thrombopoiesis; Transcription Factors; Transcription, Genetic
PubMed: 16102038
DOI: 10.1111/j.1538-7836.2005.01426.x