-
Haematologica May 2023Thrombocytopenia is a thrombopoietin (TPO)-related disorder with very limited treatment options, and can be lifethreatening. There are major problems with typical...
Thrombocytopenia is a thrombopoietin (TPO)-related disorder with very limited treatment options, and can be lifethreatening. There are major problems with typical thrombopoietic agents targeting TPO signaling, so it is urgent to discover a novel TPO-independent mechanism involving thrombopoiesis and potential druggable targets. We developed a drug screening model by the multi-grained cascade forest (gcForest) algorithm and found that 3,8-di-O-methylellagic acid 2- O-glucoside (DMAG) (10, 20 and 40 μM) promoted megakaryocyte differentiation in vitro. Subsequent investigations revealed that DMAG (40 mM) activated ERK1/2, HIF-1b and NF-E2. Inhibition of ERK1/2 blocked megakaryocyte differentiation and attenuated the upregulation of HIF-1b and NF-E2 induced by DMAG. Megakaryocyte differentiation induced by DMAG was inhibited via knockdown of NF-E2. In vivo studies showed that DMAG (5 mg/kg) accelerated platelet recovery and megakaryocyte differentiation in mice with thrombocytopenia. The platelet count of the DMAG-treated group recovered to almost 72% and 96% of the count in the control group at day 10 and 14, respectively. The platelet counts in the DMAG-treated group were almost 1.5- and 1.3-fold higher compared with those of the irradiated group at day 10 and 14, respectively. Moreover, DMAG (10, 25 and 50 mM) stimulated thrombopoiesis in zebrafish. DMAG (5 mg/kg) could also increase platelet levels in c-MPL knockout (c-MPL-/-) mice. In summary, we established a drug screening model through gcForest and demonstrated that DMAG promotes megakaryocyte differentiation via the ERK/HIF1/NF-E2 pathway which, importantly, is independent of the classical TPO/c-MPL pathway. The present study may provide new insights into drug discovery for thrombopoiesis and TPO-independent regulation of thrombopoiesis, as well as a promising avenue for thrombocytopenia treatment.
Topics: Animals; Mice; Anemia; Blood Platelets; Megakaryocytes; Thrombocytopenia; Thrombopoiesis; Thrombopoietin; Zebrafish; Glucosides
PubMed: 36546424
DOI: 10.3324/haematol.2022.282209 -
Frontiers in Immunology 2022Megakaryocytes (MKs) are large cells giving rise to platelets. It is well established that in adults, MKs develop from hematopoietic stem cells and reside in the bone... (Review)
Review
Megakaryocytes (MKs) are large cells giving rise to platelets. It is well established that in adults, MKs develop from hematopoietic stem cells and reside in the bone marrow. MKs are also rare but normal constituents of the venous blood returning to the lungs, and MKs are found in the lung vasculature (MK), suggesting that these cells are migrants from the bone marrow and get trapped in lung capillaries where the final steps of platelet production can occur. An unprecedented increase in the number of lung and circulating MKs was described in coronavirus disease 2019 (COVID-19) patients, suggesting that lung thrombopoiesis may be increased during lung infection and/or thromboinflammation. In addition to the population of platelet-producing intravascular MKs in the lung, a population of lung-resident megakaryocytes (MK) has been identified and presents a specific immune signature compared to its bone marrow counterparts. Recent single-cell analysis and intravital imaging have helped us gain a better understanding of these populations in mouse and human. This review aims at summarizing the recent data on increased occurrence of lung MKs and discusses their origin, specificities, and potential role in homeostasis and inflammatory and infectious lung diseases. Here, we address remaining questions, controversies, and methodologic challenges for further studies of both MK and MK.
Topics: Humans; Mice; Animals; Megakaryocytes; Inflammation; COVID-19; Thrombosis; Lung
PubMed: 36524131
DOI: 10.3389/fimmu.2022.1029223 -
Immunity Dec 2022Inflammatory insults affect platelet production, but it is yet unknown what mechanisms can drive rapid adaptations in thrombopoiesis. In this issue of Immunity, Petzold...
Inflammatory insults affect platelet production, but it is yet unknown what mechanisms can drive rapid adaptations in thrombopoiesis. In this issue of Immunity, Petzold et al. (2022) propose that neutrophils "pluck" on megakaryocytes in the bone marrow to tune platelet release.
Topics: Blood Platelets; Neutrophils; Thrombopoiesis; Megakaryocytes; Bone Marrow
PubMed: 36516813
DOI: 10.1016/j.immuni.2022.11.012 -
International Journal of Molecular... Nov 2022Platelets (PLTs) are anucleate and considered incapable of nuclear functions. Contrastingly, nuclear proteins were detected in human PLTs. For most of these proteins, it...
Platelets (PLTs) are anucleate and considered incapable of nuclear functions. Contrastingly, nuclear proteins were detected in human PLTs. For most of these proteins, it is unclear if nuclear or alternatively assigned functions are performed, a question we wanted to address for nuclear assembly protein 1like 1 (NAP1L1). Using a wide array of molecular methods, including RNAseq, co-IP, overexpression and functional assays, we explored expression pattern and functionality of NAP1L1 in PLTs, and CD34-derived megakaryocytes (MKs). NAP1L1 is expressed in PLTs and MKs. Co-IP experiments revealed that dihydrolipolylysine-residue acetyltransferase (DLAT encoded protein PDC-E2, ODP2) dynamically interacts with NAP1L1. PDC-E2 is part of the mitochondrial pyruvate-dehydrogenase (PDH) multi-enzyme complex, playing a crucial role in maintaining cellular respiration, and promoting ATP-synthesis via the respiratory chain. Since altered mitochondrial function is a hallmark of infectious syndromes, we analyzed PDH activity in PLTs from septic patients demonstrating increased activity, paralleling NAP1L1 expression levels. MKs PDH activity decreased following an LPS-challenge. Furthermore, overexpression of NAP1L1 significantly altered the ability of MKs to form proplatelet extensions, diminishing thrombopoiesis. These results indicate that NAP1L1 performs in other than nucleosome-assembly functions in PTLs and MKs, binding a key mitochondrial protein as a potential chaperone, and gatekeeper, influencing PDH activity and thrombopoiesis.
Topics: Humans; Nuclear Proteins; Megakaryocytes; Blood Platelets; Thrombopoiesis; Antigens, CD34; Nucleosome Assembly Protein 1
PubMed: 36499021
DOI: 10.3390/ijms232314694 -
Blood Dec 2022
Topics: Humans; Thrombopoiesis; Megakaryocytes; Blood Platelets; Thrombosis
PubMed: 36480224
DOI: 10.1182/blood.2022017936 -
International Journal of Molecular... Nov 2022is a famous traditional Chinese medicine (TCM) used to treat bleeding, rheumatism, lumbago, etc. However, its therapeutic effects and mechanism against thrombocytopenia...
BACKGROUND
is a famous traditional Chinese medicine (TCM) used to treat bleeding, rheumatism, lumbago, etc. However, its therapeutic effects and mechanism against thrombocytopenia are still unknown so far. In the study, we investigated the effects of aqueous extracts of (AECRs) against thrombocytopenia and its molecular mechanism.
METHODS
Giemsa staining, phalloidin staining, and flow cytometry were performed to measure the effect of AECRs on the megakaryocyte differentiation in K562 and Meg-01 cells. A radiation-induced thrombocytopenia mouse model was constructed to assess the therapeutic actions of AECRs on thrombocytopenia. Network pharmacology and experimental verification were carried out to clarify its mechanism against thrombocytopenia.
RESULTS
AECRs promoted megakaryocyte differentiation in K562 and Meg-01 cells and accelerated platelet recovery and megakaryopoiesis with no systemic toxicity in radiation-induced thrombocytopenia mice. The PI3K/AKT, MEK/ERK, and JAK2/STAT3 signaling pathways contributed to AECR-induced megakaryocyte differentiation. The suppression of the above signaling pathways by their inhibitors blocked AERC-induced megakaryocyte differentiation.
CONCLUSIONS
AECRs can promote megakaryopoiesis and thrombopoiesis through activating PI3K/AKT, MEK/ERK, and JAK2/STAT3 signaling pathways, which has the potential to treat radiation-induced thrombocytopenia in the clinic.
Topics: Mice; Animals; Thrombopoiesis; Proto-Oncogene Proteins c-akt; Phosphatidylinositol 3-Kinases; Signal Transduction; Mitogen-Activated Protein Kinase Kinases; Thrombocytopenia
PubMed: 36430539
DOI: 10.3390/ijms232214060 -
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 -
Blood Jan 2023Glycosylation is recognized as a key process for proper megakaryopoiesis and platelet formation. The enzyme uridine diphosphate (UDP)-galactose-4-epimerase, encoded by...
Glycosylation is recognized as a key process for proper megakaryopoiesis and platelet formation. The enzyme uridine diphosphate (UDP)-galactose-4-epimerase, encoded by GALE, is involved in galactose metabolism and protein glycosylation. Here, we studied 3 patients from 2 unrelated families who showed lifelong severe thrombocytopenia, bleeding diathesis, mental retardation, mitral valve prolapse, and jaundice. Whole-exome sequencing revealed 4 variants that affect GALE, 3 of those previously unreported (Pedigree A, p.Lys78ValfsX32 and p.Thr150Met; Pedigree B, p.Val128Met; and p.Leu223Pro). Platelet phenotype analysis showed giant and/or grey platelets, impaired platelet aggregation, and severely reduced alpha and dense granule secretion. Enzymatic activity of the UDP-galactose-4-epimerase enzyme was severely decreased in all patients. Immunoblotting of platelet lysates revealed reduced GALE protein levels, a significant decrease in N-acetyl-lactosamine (LacNAc), showing a hypoglycosylation pattern, reduced surface expression of gylcoprotein Ibα-IX-V (GPIbα-IX-V) complex and mature β1 integrin, and increased apoptosis. In vitro studies performed with patients-derived megakaryocytes showed normal ploidy and maturation but decreased proplatelet formation because of the impaired glycosylation of the GPIbα and β1 integrin, and reduced externalization to megakaryocyte and platelet membranes. Altered distribution of filamin A and actin and delocalization of the von Willebrand factor were also shown. Overall, this study expands our knowledge of GALE-related thrombocytopenia and emphasizes the critical role of GALE in the physiological glycosylation of key proteins involved in platelet production and function.
Topics: Humans; Blood Platelets; Galactose; Glycosylation; Integrin beta1; Megakaryocytes; Thrombocytopenia; Thrombopoiesis; UDPglucose 4-Epimerase; Uridine Diphosphate
PubMed: 36395340
DOI: 10.1182/blood.2022016995 -
Blood Advances Jul 2023GATA1 mutations that result in loss of the N-terminal 83 amino acids are a feature of myeloid leukemia in children with Down syndrome, rare familial cases of...
GATA1 mutations that result in loss of the N-terminal 83 amino acids are a feature of myeloid leukemia in children with Down syndrome, rare familial cases of dyserythropoietic anemia, and a subset of cases of Diamond-Blackfan anemia. The Gata1s mouse model, which expresses only the short GATA1 isoform that begins at methionine 84, has been shown to have a defect in hematopoiesis, especially impaired erythropoiesis with expanded megakaryopoiesis, during gestation. However, these mice reportedly did not show any postnatal phenotype. Here, we demonstrate that Gata1s mutant mice display macrocytic anemia and features of aberrant megakaryopoiesis throughout life, culminating in profound splenomegaly and bone marrow fibrosis. These data support the use of this animal model for studies of GATA1 deficiencies.
Topics: Animals; Mice; Cell Lineage; Down Syndrome; Erythropoiesis; Protein Isoforms; Thrombopoiesis
PubMed: 36350717
DOI: 10.1182/bloodadvances.2022008124 -
Hospital Pharmacy Dec 2022Thrombocytopenia is a commonly encountered complication of hospitalized patients, and can be caused by many factors including infections, surgery, and medications....
Thrombocytopenia is a commonly encountered complication of hospitalized patients, and can be caused by many factors including infections, surgery, and medications. Drug-induced thrombocytopenia (DITP) should be considered when a patient presents with an unexpected occurrence of thrombocytopenia. Many drugs can induce thrombocytopenia either as a direct effect on thrombopoiesis within the bone marrow or by drug-dependent antibody-mediated destruction of platelets within the circulation. We present the case of a 44-year-old female who presented with 2 weeks of nausea, vomiting, and headaches occurring with her hemodialysis sessions. On admission she was found to be thrombocytopenic with a platelet count of 35 K/µL. Her last known normal platelet count was 299 K/µL from 2 months prior. A thorough work up of her thrombocytopenia was found to be unremarkable. Her newly started carvedilol was thought to be the most likely cause based on the rapid platelet recovery upon drug discontinuation and negative workup of other potential causes.
PubMed: 36340635
DOI: 10.1177/00185787221108719