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ELife Jun 2023Polycomb repressive complex (PRC) 1 regulates stem cell fate by mediating mono-ubiquitination of histone H2A at lysine 119. While canonical PRC1 is critical for...
Polycomb repressive complex (PRC) 1 regulates stem cell fate by mediating mono-ubiquitination of histone H2A at lysine 119. While canonical PRC1 is critical for hematopoietic stem and progenitor cell (HSPC) maintenance, the role of non-canonical PRC1 in hematopoiesis remains elusive. PRC1.1, a non-canonical PRC1, consists of PCGF1, RING1B, KDM2B, and BCOR. We recently showed that PRC1.1 insufficiency induced by the loss of PCGF1 or BCOR causes myeloid-biased hematopoiesis and promotes transformation of hematopoietic cells in mice. Here we show that PRC1.1 serves as an epigenetic switch that coordinates homeostatic and emergency hematopoiesis. PRC1.1 maintains balanced output of steady-state hematopoiesis by restricting C/EBPα-dependent precocious myeloid differentiation of HSPCs and the HOXA9- and β-catenin-driven self-renewing network in myeloid progenitors. Upon regeneration, PRC1.1 is transiently inhibited to facilitate formation of granulocyte-macrophage progenitor (GMP) clusters, thereby promoting emergency myelopoiesis. Moreover, constitutive inactivation of PRC1.1 results in unchecked expansion of GMPs and eventual transformation. Collectively, our results define PRC1.1 as a novel critical regulator of emergency myelopoiesis, dysregulation of which leads to myeloid transformation.
Topics: Animals; Mice; Polycomb Repressive Complex 1; Myelopoiesis; Histones; Cell Differentiation; Hematopoietic Stem Cells
PubMed: 37266576
DOI: 10.7554/eLife.83004 -
Journal of Leukocyte Biology Aug 2020Discussion on how CXXC5 alters hematopoiesis by regulating the differentiation of hematopoietic stem and progenitor cells toward monocyte development.
Discussion on how CXXC5 alters hematopoiesis by regulating the differentiation of hematopoietic stem and progenitor cells toward monocyte development.
Topics: Animals; Cell Cycle; Cell Differentiation; DNA-Binding Proteins; Hematopoiesis; Hematopoietic Stem Cell Transplantation; Intracellular Signaling Peptides and Proteins; Mice; Myelopoiesis; Transcription Factors
PubMed: 32745327
DOI: 10.1002/JLB.1CE0420-106R -
International Immunology May 2023The microbiota engages in the development and maintenance of the host immune system. The microbiota affects not only mucosal tissues where it localizes but also the... (Review)
Review
The microbiota engages in the development and maintenance of the host immune system. The microbiota affects not only mucosal tissues where it localizes but also the distal organs. Myeloid cells are essential for host defense as first responders of the host immune system. Their generation, called myelopoiesis, is regulated by environmental signals, including commensal microbiota. Hematopoietic stem and progenitor cells in bone marrow can directly or indirectly sense microbiota-derived signals, thereby giving rise to myeloid cell lineages at steady-state and during inflammation. In this review, we discuss the role of commensal microorganisms in the homeostatic regulation of myelopoiesis in the bone marrow. We also outline the effects of microbial signals on myelopoiesis during inflammation and infection, with a particular focus on the development of innate immune memory. Studying the relationship between the microbiota and myelopoiesis will help us understand how the microbiota regulates immune responses at a systemic level beyond the local mucosa.
Topics: Humans; Myelopoiesis; Inflammation; Bone Marrow; Microbiota; Homeostasis
PubMed: 36694400
DOI: 10.1093/intimm/dxad002 -
Nature Sep 2017Stem-cell fate can be influenced by metabolite levels in culture, but it is not known whether physiological variations in metabolite levels in normal tissues regulate...
Stem-cell fate can be influenced by metabolite levels in culture, but it is not known whether physiological variations in metabolite levels in normal tissues regulate stem-cell function in vivo. Here we describe a metabolomics method for the analysis of rare cell populations isolated directly from tissues and use it to compare mouse haematopoietic stem cells (HSCs) to restricted haematopoietic progenitors. Each haematopoietic cell type had a distinct metabolic signature. Human and mouse HSCs had unusually high levels of ascorbate, which decreased with differentiation. Systemic ascorbate depletion in mice increased HSC frequency and function, in part by reducing the function of Tet2, a dioxygenase tumour suppressor. Ascorbate depletion cooperated with Flt3 internal tandem duplication (Flt3) leukaemic mutations to accelerate leukaemogenesis, through cell-autonomous and possibly non-cell-autonomous mechanisms, in a manner that was reversed by dietary ascorbate. Ascorbate acted cell-autonomously to negatively regulate HSC function and myelopoiesis through Tet2-dependent and Tet2-independent mechanisms. Ascorbate therefore accumulates within HSCs to promote Tet activity in vivo, limiting HSC frequency and suppressing leukaemogenesis.
Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Carcinogenesis; DNA-Binding Proteins; Dioxygenases; Female; Hematopoietic Stem Cells; Humans; Leukemia; Male; Metabolomics; Mice; Myelopoiesis; Proto-Oncogene Proteins; fms-Like Tyrosine Kinase 3
PubMed: 28825709
DOI: 10.1038/nature23876 -
Nature Feb 2018Varieties of RNA modification form the epitranscriptome for post-transcriptional regulation. 5-Methylcytosine (5-mC) is a sparse RNA modification in messenger RNA (mRNA)...
Varieties of RNA modification form the epitranscriptome for post-transcriptional regulation. 5-Methylcytosine (5-mC) is a sparse RNA modification in messenger RNA (mRNA) under physiological conditions. The function of RNA 5-hydroxymethylcytosine (5-hmC) oxidized by ten-eleven translocation (Tet) proteins in Drosophila has been revealed more recently. However, the turnover and function of 5-mC in mammalian mRNA have been largely unknown. Tet2 suppresses myeloid malignancies mostly in an enzymatic activity-dependent manner, and is important in resolving inflammatory response in an enzymatic activity-independent way. Myelopoiesis is a common host immune response in acute and chronic infections; however, its epigenetic mechanism needs to be identified. Here we demonstrate that Tet2 promotes infection-induced myelopoiesis in an mRNA oxidation-dependent manner through Adar1-mediated repression of Socs3 expression at the post-transcription level. Tet2 promotes both abdominal sepsis-induced emergency myelopoiesis and parasite-induced mast cell expansion through decreasing mRNA levels of Socs3, a key negative regulator of the JAK-STAT pathway that is critical for cytokine-induced myelopoiesis. Tet2 represses Socs3 expression through Adar1, which binds and destabilizes Socs3 mRNA in a RNA editing-independent manner. For the underlying mechanism of Tet2 regulation at the mRNA level, Tet2 mediates oxidation of 5-mC in mRNA. Tet2 deficiency leads to the transcriptome-wide appearance of methylated cytosines, including ones in the 3' untranslated region of Socs3, which influences double-stranded RNA formation for Adar1 binding, probably through cytosine methylation-specific readers, such as RNA helicases. Our study reveals a previously unknown regulatory role of Tet2 at the epitranscriptomic level, promoting myelopoiesis during infection in the mammalian system by decreasing 5-mCs in mRNAs. Moreover, the inhibitory function of cytosine methylation on double-stranded RNA formation and Adar1 binding in mRNA reveals its new physiological role in the mammalian system.
Topics: 3' Untranslated Regions; 5-Methylcytosine; Adenosine Deaminase; Animals; Bone Marrow Cells; DNA-Binding Proteins; Dioxygenases; Epigenesis, Genetic; Female; Gene Expression Regulation; Immunity, Innate; Mice; Myelopoiesis; Nucleic Acid Conformation; Oxidation-Reduction; Proto-Oncogene Proteins; RNA, Double-Stranded; RNA, Messenger; Sepsis; Suppressor of Cytokine Signaling 3 Protein; Transcriptome
PubMed: 29364877
DOI: 10.1038/nature25434 -
Nature Communications Sep 2023Telomerase RNA (TERC) has a noncanonical function in myelopoiesis binding to a consensus DNA binding sequence and attracting RNA polymerase II (RNA Pol II), thus...
Telomerase RNA (TERC) has a noncanonical function in myelopoiesis binding to a consensus DNA binding sequence and attracting RNA polymerase II (RNA Pol II), thus facilitating myeloid gene expression. The CR4/CR5 domain of TERC is known to play this role, since a mutation of this domain found in dyskeratosis congenita (DC) patients decreases its affinity for RNA Pol II, impairing its myelopoietic activity as a result. In this study, we report that two aptamers, short single-stranded oligonucleotides, based on the CR4/CR5 domain were able to increase myelopoiesis without affecting erythropoiesis in zebrafish. Mechanistically, the aptamers functioned as full terc; that is, they increased the expression of master myeloid genes, independently of endogenous terc, by interacting with RNA Pol II and with the terc-binding sequences of the regulatory regions of such genes, enforcing their transcription. Importantly, aptamers harboring the CR4/CR5 mutation that was found in DC patients failed to perform all these functions. The therapeutic potential of the aptamers for treating neutropenia was demonstrated in several preclinical models. The findings of this study have identified two potential therapeutic agents for DC and other neutropenic patients.
Topics: Humans; Animals; Aptamers, Nucleotide; Myelopoiesis; RNA Polymerase II; Syndrome; Zebrafish; Dyskeratosis Congenita
PubMed: 37737237
DOI: 10.1038/s41467-023-41472-7 -
Oncotarget Jan 2017Myeloid-derived suppressor cells (MDSCs) have a strong immunosuppressive character that allows them to regulate immune responses and hinder overt inflammatory responses.... (Review)
Review
Myeloid-derived suppressor cells (MDSCs) have a strong immunosuppressive character that allows them to regulate immune responses and hinder overt inflammatory responses. In cancer, this leads to tumor immune evasion and disease progression. MDSCs come in at least two forms: monocytic (Mo-MDSCs) and granulocytic (G-MDSCs). The classical definition of MDSCs as immature myeloid cells blocked from differentiating has been challenged by recent studies suggesting that Mo-MDSCs and G-MDSCs may represent monocytes and granulocytes that have acquired immunosuppressive properties. The molecular mechanism behind their generation and their true origins are now widely debated. In this review we discuss the different proposed mechanisms of the generation of both types of MDSCs, with a special focus on human MDSCs in cancer.
Topics: Animals; Cell Differentiation; Cellular Reprogramming; Colony-Stimulating Factors; Gene Expression Regulation; Granulocytes; Hematopoiesis, Extramedullary; Humans; Immunomodulation; Monocytes; Myeloid Cells; Myeloid-Derived Suppressor Cells; Myelopoiesis; Neutrophil Activation; Neutrophils; Phenotype; Signal Transduction
PubMed: 27690299
DOI: 10.18632/oncotarget.12278 -
Proceedings of the National Academy of... Oct 2021Trained immunity defines long-lasting adaptations of innate immunity based on transcriptional and epigenetic modifications of myeloid cells and their bone marrow...
Trained immunity defines long-lasting adaptations of innate immunity based on transcriptional and epigenetic modifications of myeloid cells and their bone marrow progenitors [M. Divangahi et al., 22, 2-6 (2021)]. Innate immune cells, however, do not exclusively differentiate between foreign and self but also react to host-derived molecules referred to as alarmins. Extracellular "labile" heme, released during infections, is a bona fide alarmin promoting myeloid cell activation [M. P. Soares, M. T. Bozza, 38, 94-100 (2016)]. Here, we report that labile heme is a previously unrecognized inducer of trained immunity that confers long-term regulation of lineage specification of hematopoietic stem cells and progenitor cells. In contrast to previous reports on trained immunity, essentially mediated by pathogen-associated molecular patterns, heme training depends on spleen tyrosine kinase signal transduction pathway acting upstream of c-Jun N-terminal kinases. Heme training promotes resistance to sepsis, is associated with the expansion of self-renewing hematopoetic stem cells primed toward myelopoiesis and to the occurrence of a specific myeloid cell population. This is potentially evoked by sustained activity of Nfix, Runx1, and Nfe2l2 and dissociation of the transcriptional repressor Bach2. Previously reported trained immunity inducers are, however, infrequently present in the host, whereas heme abundantly occurs during noninfectious and infectious disease. This difference might explain the vanishing protection exerted by heme training in sepsis over time with sustained long-term myeloid adaptations. Hence, we propose that trained immunity is an integral component of innate immunity with distinct functional differences on infectious disease outcome depending on its induction by pathogenic or endogenous molecules.
Topics: Animals; Epigenesis, Genetic; Heme; Humans; Immunity, Innate; Mice; Myelopoiesis
PubMed: 34663697
DOI: 10.1073/pnas.2102698118 -
Current Opinion in Hematology Jan 2018The purpose of this review is to describe recent findings in the context of previous work regarding dysregulated myelopoiesis and hematopoietic function following an... (Review)
Review
PURPOSE OF REVIEW
The purpose of this review is to describe recent findings in the context of previous work regarding dysregulated myelopoiesis and hematopoietic function following an acute physiologic insult, focusing on the expansion and persistence of myeloid-deriver suppressor cells, the deterioration of lymphocyte number and function, and the inadequacy of stress erythropoiesis.
RECENT FINDINGS
Persistent myeloid-derived suppressor cell (MDSC) expansion among critically ill septic patients is associated with T-cell suppression, vulnerability to nosocomial infection, chronic critical illness, and poor long-term functional status. Multiple approaches targeting MDSC expansion and suppressor cell activity may serve as a primary or adjunctive therapeutic intervention. Traumatic injury and the neuroendocrine stress response suppress bone marrow erythropoietin receptor expression in a process that may be reversed by nonselective beta-adrenergic receptor blockade. Hepcidin-mediated iron-restricted anemia of critical illness requires further investigation of novel approaches involving erythropoiesis-stimulating agents, iron administration, and hepcidin modulation.
SUMMARY
Emergency myelopoiesis is a dynamic process with unique phenotypes for different physiologic insults and host factors. Following an acute physiologic insult, critically ill patients are subject to persistent MDSC expansion, deterioration of lymphocyte number and function, and inadequate stress erythropoiesis. Better strategies are required to identify patients who are most likely to benefit from targeted therapies.
Topics: Animals; Hematopoiesis; Humans; Lymphocytes; Myelopoiesis
PubMed: 29035909
DOI: 10.1097/MOH.0000000000000395 -
Circulation Research Sep 2020Treatment efficacy for diabetes mellitus is largely determined by assessment of HbA1c (glycated hemoglobin A1c) levels, which poorly reflects direct glucose variation....
RATIONALE
Treatment efficacy for diabetes mellitus is largely determined by assessment of HbA1c (glycated hemoglobin A1c) levels, which poorly reflects direct glucose variation. People with prediabetes and diabetes mellitus spend >50% of their time outside the optimal glucose range. These glucose variations, termed transient intermittent hyperglycemia (TIH), appear to be an independent risk factor for cardiovascular disease, but the pathological basis for this association is unclear.
OBJECTIVE
To determine whether TIH per se promotes myelopoiesis to produce more monocytes and consequently adversely affects atherosclerosis.
METHODS AND RESULTS
To create a mouse model of TIH, we administered 4 bolus doses of glucose at 2-hour intervals intraperitoneally once to WT (wild type) or once weekly to atherosclerotic prone mice. TIH accelerated atherogenesis without an increase in plasma cholesterol, seen in traditional models of diabetes mellitus. TIH promoted myelopoiesis in the bone marrow, resulting in increased circulating monocytes, particularly the inflammatory Ly6-C subset, and neutrophils. Hematopoietic-restricted deletion of , , or its cognate receptor prevented monocytosis. Mechanistically, glucose uptake via GLUT (glucose transporter)-1 and enhanced glycolysis in neutrophils promoted the production of S100A8/A9. Myeloid-restricted deletion of (GLUT-1) or pharmacological inhibition of S100A8/A9 reduced TIH-induced myelopoiesis and atherosclerosis.
CONCLUSIONS
Together, these data provide a mechanism as to how TIH, prevalent in people with impaired glucose metabolism, contributes to cardiovascular disease. These findings provide a rationale for continual glucose control in these patients and may also suggest that strategies aimed at targeting the S100A8/A9-RAGE (receptor for advanced glycation end products) axis could represent a viable approach to protect the vulnerable blood vessels in diabetes mellitus. Graphic Abstract: A graphic abstract is available for this article.
Topics: Animals; Atherosclerosis; Biomarkers; Blood Glucose; Calgranulin A; Calgranulin B; Diet, High-Fat; Disease Models, Animal; Glucose Transporter Type 1; Glycolysis; Hyperglycemia; Macrophages; Male; Mice, Inbred C57BL; Mice, Knockout, ApoE; Monocytes; Myelopoiesis; Neutrophils; Plaque, Atherosclerotic; Receptor for Advanced Glycation End Products; Signal Transduction
PubMed: 32564710
DOI: 10.1161/CIRCRESAHA.120.316653