OBJECTIVE: To investigate the effect of 5-hydroxytryptamine (5-HT) on the proliferation, apoptosis and colony-forming unit-megakaryocyte (CFU-MK) of Meg-01 cells and its possible mechanisms. METHODS: The uptake and metabolism of 5-HT in Meg-01 cells were analysed by reverse-phase high-performance liquid chromatography (RP-HPLC) with electrochemical detection. The expression of 5-HT2B receptor (5-HT2BR) in megakaryocytes was detected by immunofluorescence staining. The cell proliferation and viability were measured by MTT and Trypan blue staining after Meg-01 cells were single-cultured or co-cultured with different concentrations of 5-HT/5-HT2BR inhibitor Ketanserin for 48 h. Meg-01 cells were incubated with 5-HT/ Ketanserin for 72 h, then the flow cytometry was used to detect early apoptosis of the cells and the activity of caspase-3. Using CFU-MK assay to investigate the effect of 5-HT on the differentiation of megakaryocytes. RESULTS: 5-HT could be uptaken by Meg-01 cells, and metabolized into 5-hydroxyindoleacetic acid (5-HIAA). The expression of 5-HT2BR on megakaryocytes could be detected after immunofluorescence staining. 5-HT could promote the proliferation of Meg-01 cells at a dose-dependent manner (r =0.82), with the most significant effect observed at a concentration of 200 nmol/L (P < 0.001). Trypan blue staining also indicated that 200 nmol/L 5-HT had the most significant effect on the viability of Meg-01 cells (P < 0.05). The proliferation of Meg-01 cells treated with 5-HT was increased compared with the untreated control (P < 0.001), while the combination of 5-HT with ketanserin downregulated this effect. 5-HT significantly reduced the early apoptosis rate (P < 0.001) and caspase-3 activity (P < 0.05) of Meg-01 cells, while addition of ketanserin significantly increased the early apoptosis rate of Meg-01 cells (P < 0.001) and caspase-3 activity also increased to some extent. 5-HT promoted the formation of CFU-MK in bone marrow cells in a dose-dependent manner (r =0.89). The addition of ketanserin reduced the promoting effect of 5-HT on CFU-MK formation (P < 0.01). CONCLUSION There may be monoamine oxidase present in megakaryocytes, which can metabolize and decompose 5-HT into 5-HIAA. 5-HT may promote the proliferation and differentiation of megakaryocytes through 5-HT2BR. Besides, 5-HT can also reduce the apoptosis of megakaryocytes, and its anti-apoptotic effect may be mediated by 5-HT2BR and caspase-3 pathways.
Apoptosis/drug effects* ; Cell Proliferation/drug effects* ; Megakaryocytes/metabolism* ; Serotonin/pharmacology* ; Humans ; Receptor, Serotonin, 5-HT2B/metabolism* ; Caspase 3/metabolism* ; Cell Differentiation

Megakaryocytes and hepatocytes are unique cells in mammals that undergo polyploidization through endomitosis in terminal differentiation. Many polyploidization regulators and underlying mechanisms have been reported, most of which are tightly coupled with development, organogenesis, and cell differentiation. However, the nature of endomitosis, which involves successful entry into and exit from mitosis without complete cytokinesis, has not yet been fully elucidated. We highlight that endomitosis is a new cell fate in the cell cycle, and tetraploidy is a critical stage at the bifurcation of cell fate decision. This review summarizes the recent research progress in this area and provides novel insights into how cells manipulate mitosis toward endomitosis. Endomitotic cells can evade the tetraploidy restrictions and proceed to multiple rounds of the cell cycle. This knowledge not only deepens our understanding of endomitosis as a fundamental biological process but also offers new perspectives on the physiological and pathophysiological implications of polyploidization.
Hepatocytes/physiology* ; Megakaryocytes/physiology* ; Humans ; Polyploidy ; Animals ; Cell Cycle/physiology* ; Cell Differentiation ; Mitosis/physiology*

Megakaryocytes (MKs), which are traditionally known for their role in platelet production, are now emerging as unique immune cells with diverse capabilities. They express immune receptors, participate in pathogen recognition and response, phagocytose pathogens, contribute to antigen presentation, and interact with various immune cell types. When encountering inflammatory challenges, MKs exhibit intricate immune functions that can either promote or inhibit inflammation. These responses are mediated through mechanisms, such as the secretion of either anti-inflammatory or pro-inflammatory cytokines and release of immunomodulatory platelets according to specific conditions. This intricate array of responses necessitates a detailed exploration to determine whether the immune functions of MKs are carried out by the entire MK population or by a specific subpopulation. Breakthroughs in single-cell RNA sequencing have uncovered a unique "immune MK" subpopulation, revealing its distinct characteristics and immunoregulatory functions. This review provides latest insights into MKs' immune attributes and their roles in physiological and pathological contexts and emphasizes the discovery and functions of "immune MKs".
Animals ; Humans ; Blood Platelets/immunology* ; Cytokines/metabolism* ; Inflammation/immunology* ; Megakaryocytes/metabolism*

OBJECTIVE: To investigate the effect of Rheb1 in the development of mouse megakaryocyte-erythroid progenitor cells and its related mechanism. METHODS: Rheb1 was specifically knocked-out in the hematopoietic system of Vav1-Cre;Rheb1^fl/fl mice(Rheb1^Δ/Δ mice). Flow cytometry was used to detect the percentage of red blood cells in peripheral blood and erythroid cells in bone marrow in Vav1-Cre;Rheb1^fl/fl mice and control mice. The CFC assay was used to detect the differentiation ability of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Real-time fluorescence quantification PCR was used to detect the relative expression of PU.1,GATA-1,GATA-2,CEBPα and CEBPβ of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Rapamycin was added to the culture medium, and it was used to detect the changes in cloning ability of megakaryocyte-erythroid progenitor cells from wild-type mice in vitro. RESULTS: After Rheb1 was knocked out, the development and stress response ability of megakaryocyte-erythroid progenitor cells in mice were weaken and the differentiation ability of megakaryocyte-erythroid progenitor cells in vitro was weaken. Moreover, the expression of GATA-1 of megakaryocyte-erythroid progenitor cells was decreased. Further, rapamycin could inhibit the differentiative capacity of megakaryocyte-erythroid progenitor cells in vitro. CONCLUSION Rheb1 can regulate the development of megakaryocyte-erythroid progenitor cells probably through the mTOR signaling pathway in mice.
Animals ; Cell Differentiation ; Erythrocytes ; Flow Cytometry ; Megakaryocyte-Erythroid Progenitor Cells ; Megakaryocytes ; Mice ; Signal Transduction

Tubulin affects platelets count through the control of mitosis and the formation of pro-platelets during the maturation of megakaryoblast to platelets. Tubulin is involved in maintaining the integrity of platelet skeleton, and also participates in the change of platelet morphology during platelet activation. Some new anti-tumor drugs targeting cell mitosis are trying to reduce the effect on tubulin in order to reduce the side effect of drugs on platelet formation. In some patients with thrombocytopenia, the variation and polymorphism of the tubulin gene affect the structure of microtubule multimers, which leads to the decrease of platelet formation. This review summarized the latest progresses of tubulin in the regulation of megakaryopoiesis and thrombopoiesis.
Blood Platelets ; Humans ; Megakaryocytes ; Platelet Count ; Thrombopoiesis ; Tubulin

Actinin/genetics* ; Anemia ; Blood Platelets/pathology* ; Female ; Humans ; Male ; Megakaryocytes ; Mutation, Missense ; Pedigree ; Thrombocytopenia/genetics*

Objective: To establish an intramedullary transplantation model of primary megakaryocytes to evaluate the platelet-producing capacity of megakaryocytes and explore the underlying regulatory mechanisms. Methods: Donor megakaryocytes from GFP-transgenic mice bone marrow were enriched by magnetic beads. The platelet-producing model was established by intramedullary injection to recipient mice that underwent half-lethal dose irradiation 1 week in advance. Donor-derived megakaryocytes and platelets were detected by immunofluorescence staining and flow cytometry. Results: The proportion of megakaryocytes in the enriched sample for transplantation was 40 to 50 times higher than that in conventional bone marrow. After intramedullary transplantation, donor-derived megakaryocytes successfully implanted in the medullary cavity of the recipient and produce platelets, which showed similar expression of surface markers and morphology to recipient-derived platelets. Conclusion: We successfully established an in vivo platelet-producing model of primary megakaryocytes using magnetic-bead enrichment and intramedullary injection, which objectively reflects the platelet-producing capacity of megakaryocytes in the bone marrow.
Animals ; Blood Platelets ; Bone Marrow ; Bone Marrow Cells ; Bone Marrow Transplantation ; Humans ; Megakaryocytes/metabolism* ; Mice

Objective: To reveal the crucial toxic components of ambient fine particles (PM_2.5) that affect the maturation and differentiation of megakaryocytes. Methods: Human megakaryocytes were exposed to the organic fractions, metallic fractions and water-soluble fractions of PM_2.5 at two exposure doses (i.e. actual air proportion concentration or the same concentration), respectively. The cell viability was performed to screen the non-cytotoxic levels of toxic components of PM_2.5 using the CCK-8 assay. CellTiter-Blue assay, morphological observation, flow cytometry analysis and WGA staining assay were used to evaluate the cell morphological changes, occurrence of DNA ploidy, alteration in the expressions of biomarkers and platelet formation, which were key indicators of the maturation and differentiation of megakaryocytes. Results: Compared to the control group, both metallic and organic components of PM_2.5 resulted in a lag in megakaryocytes with an increase in cell volume and the onset of DNA ploidy. Flow cytometry analysis showed that CD33 (the marker of myeloid-specific) decreased and CD41a (a megakaryocyte maturation-associated antigen) increased in metallic and organic components of PM_2.5 treatment groups. Moreover, compared to the control group, budding protrusions increased in metallic and organic components of PM_2.5 treatment groups. The water-soluble components had no effect on the maturation and differentiation of macrophages. Conclusion: Metallic and organic components of PM_2.5 are the crucial toxic components that promote the maturation and differentiation of megakaryocytes.
Biomarkers ; DNA/pharmacology* ; Humans ; Megakaryocytes/chemistry* ; Particulate Matter/toxicity* ; Sincalide/pharmacology* ; Water/pharmacology*

Abivertinib, a third-generation tyrosine kinase inhibitor, is originally designed to target epidermal growth factor receptor (EGFR)-activating mutations. Previous studies have shown that abivertinib has promising antitumor activity and a well-tolerated safety profile in patients with non-small-cell lung cancer. However, abivertinib also exhibited high inhibitory activity against Bruton's tyrosine kinase and Janus kinase 3. Given that these kinases play some roles in the progression of megakaryopoiesis, we speculate that abivertinib can affect megakaryocyte (MK) differentiation and platelet biogenesis. We treated cord blood CD34⁺ hematopoietic stem cells, Meg-01 cells, and C57BL/6 mice with abivertinib and observed megakaryopoiesis to determine the biological effect of abivertinib on MK differentiation and platelet biogenesis. Our in vitro results showed that abivertinib impaired the CFU-MK formation, proliferation of CD34⁺ HSC-derived MK progenitor cells, and differentiation and functions of MKs and inhibited Meg-01-derived MK differentiation. These results suggested that megakaryopoiesis was inhibited by abivertinib. We also demonstrated in vivo that abivertinib decreased the number of MKs in bone marrow and platelet counts in mice, which suggested that thrombopoiesis was also inhibited. Thus, these preclinical data collectively suggested that abivertinib could inhibit MK differentiation and platelet biogenesis and might be an agent for thrombocythemia.
Acrylamides/pharmacology* ; Animals ; Blood Platelets/drug effects* ; Cell Differentiation ; Megakaryocytes/drug effects* ; Mice ; Mice, Inbred C57BL ; Piperazines/pharmacology* ; Pyrimidines/pharmacology*

OBJECTIVE: To explore the phenotypic and genetic characteristics of acute megakaryoblastic leukemia (AMKL) in young children accompany by WT1, MLL-PTD and EVI1, in order to improve the diagnosis level of AMKL. METHODS: EDTA-K RESULTS: White blood cell count was 12.3× 10 CONCLUSION Acute megakaryocytic leukemia has unique and complex phenotypic and genetics characteristics.
Bone Marrow ; Child ; Child, Preschool ; Chromosome Aberrations ; Humans ; Karyotyping ; Leukemia, Megakaryoblastic, Acute/genetics* ; MDS1 and EVI1 Complex Locus Protein ; Megakaryocytes ; Oncogene Proteins, Fusion ; WT1 Proteins