RESUMO
Aged hematopoietic stem cells (HSCs) display diminished self-renewal and a myeloid differentiation bias. However, the drivers and mechanisms that underpin this fundamental switch are not understood. HSCs produce genotoxic formaldehyde that requires protection by the detoxification enzymes ALDH2 and ADH5 and the Fanconi anemia (FA) DNA repair pathway. We find that the HSCs in young Aldh2-/-Fancd2-/- mice harbor a transcriptomic signature equivalent to aged wild-type HSCs, along with increased epigenetic age, telomere attrition, and myeloid-biased differentiation quantified by single HSC transplantation. In addition, the p53 response is vigorously activated in Aldh2-/-Fancd2-/- HSCs, while p53 deletion rescued this aged HSC phenotype. To further define the origins of the myeloid differentiation bias, we use a GFP genetic reporter to find a striking enrichment of Vwf+ myeloid and megakaryocyte-lineage-biased HSCs. These results indicate that metabolism-derived formaldehyde-DNA damage stimulates the p53 response in HSCs to drive accelerated aging.
Assuntos
Envelhecimento , Aldeídos , Dano ao DNA , Hematopoese , Proteína Supressora de Tumor p53 , Animais , Camundongos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Aldeídos/metabolismo , Transcriptoma , Análise da Expressão Gênica de Célula Única , Células-Tronco Hematopoéticas/citologia , Células Mieloides/citologia , Humanos , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologiaRESUMO
Reactive aldehydes arise as by-products of metabolism and are normally cleared by multiple families of enzymes. We find that mice lacking two aldehyde detoxifying enzymes, mitochondrial ALDH2 and cytoplasmic ADH5, have greatly shortened lifespans and develop leukemia. Hematopoiesis is disrupted profoundly, with a reduction of hematopoietic stem cells and common lymphoid progenitors causing a severely depleted acquired immune system. We show that formaldehyde is a common substrate of ALDH2 and ADH5 and establish methods to quantify elevated blood formaldehyde and formaldehyde-DNA adducts in tissues. Bone-marrow-derived progenitors actively engage DNA repair but also imprint a formaldehyde-driven mutation signature similar to aging-associated human cancer mutation signatures. Furthermore, we identify analogous genetic defects in children causing a previously uncharacterized inherited bone marrow failure and pre-leukemic syndrome. Endogenous formaldehyde clearance alone is therefore critical for hematopoiesis and in limiting mutagenesis in somatic tissues.
Assuntos
Álcool Desidrogenase/genética , Aldeído-Desidrogenase Mitocondrial/genética , Formaldeído/sangue , Leucemia/genética , Adolescente , Aldeídos/sangue , Animais , Criança , Pré-Escolar , Adutos de DNA/genética , Dano ao DNA/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Feminino , Formaldeído/toxicidade , Hematopoese/genética , Células-Tronco Hematopoéticas/metabolismo , Humanos , Lactente , Leucemia/sangue , Leucemia/patologia , Masculino , Camundongos , Mutação/genética , Especificidade por SubstratoRESUMO
ABSTRACT: Loss of long-term hematopoietic stem cell (LT-HSC) function ex vivo hampers the success of clinical protocols that rely on culture. However, the kinetics and mechanisms through which this occurs remain incompletely characterized. In this study, through time-resolved single-cell RNA sequencing, matched in vivo functional analysis, and the use of a reversible in vitro system of early G1 arrest, we defined the sequence of transcriptional and functional events that occur during the first ex vivo division of human LT-HSCs. We demonstrated that the sharpest loss in LT-HSC repopulation capacity happens early on, between 6 and 24 hours of culture, before LT-HSCs commit to cell cycle progression. During this time window, LT-HSCs adapt to the culture environment, limit the global variability in gene expression, and transiently upregulate gene networks involved in signaling and stress responses. From 24 hours, LT-HSC progression past early G1 contributes to the establishment of differentiation programs in culture. However, contrary to the current assumptions, we demonstrated that the loss of HSC function ex vivo is independent of cell cycle progression. Finally, we showed that targeting LT-HSC adaptation to culture by inhibiting the early activation of JAK/STAT signaling improves HSC long-term repopulating function ex vivo. Collectively, our study demonstrated that controlling early LT-HSC adaptation to ex vivo culture, for example, via JAK inhibition, is critically important to improve HSC gene therapy and expansion protocols.
Assuntos
Ciclo Celular , Células-Tronco Hematopoéticas , Humanos , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Células Cultivadas , Transdução de Sinais , Diferenciação Celular , Técnicas de Cultura de Células/métodos , Adaptação FisiológicaRESUMO
In COVID-19, hyperinflammatory and dysregulated immune responses contribute to severity. Patients with pre-existing autoimmune conditions can therefore be at increased risk of severe COVID-19 and/or associated sequelae, yet SARS-CoV-2 infection in this group has been little studied. Here, we performed single-cell analysis of peripheral blood mononuclear cells from patients with three major autoimmune diseases (rheumatoid arthritis, psoriasis, or multiple sclerosis) during SARS-CoV-2 infection. We observed compositional differences between the autoimmune disease groups coupled with altered patterns of gene expression, transcription factor activity, and cell-cell communication that substantially shape the immune response under SARS-CoV-2 infection. While enrichment of HLA-DRlow CD14+ monocytes was observed in all three autoimmune disease groups, type-I interferon signaling as well as inflammatory T cell and monocyte responses varied widely between the three groups of patients. Our results reveal disturbed immune responses to SARS-CoV-2 in patients with pre-existing autoimmunity, highlighting important considerations for disease treatment and follow-up.
Assuntos
Doenças Autoimunes , COVID-19 , Humanos , SARS-CoV-2 , Leucócitos Mononucleares , Multiômica , Autoimunidade , Análise de Célula ÚnicaRESUMO
Despite the overwhelming evidence that multiple sclerosis is an autoimmune disease, relatively little is known about the precise nature of the immune dysregulation underlying the development of the disease. Reasoning that the CSF from patients might be enriched for cells relevant in pathogenesis, we have completed a high-resolution single-cell analysis of 96 732 CSF cells collected from 33 patients with multiple sclerosis (n = 48 675) and 48 patients with other neurological diseases (n = 48 057). Completing comprehensive cell type annotation, we identified a rare population of CD8+ T cells, characterized by the upregulation of inhibitory receptors, increased in patients with multiple sclerosis. Applying a Multi-Omics Factor Analysis to these single-cell data further revealed that activity in pathways responsible for controlling inflammatory and type 1 interferon responses are altered in multiple sclerosis in both T cells and myeloid cells. We also undertook a systematic search for expression quantitative trait loci in the CSF cells. Of particular interest were two expression quantitative trait loci in CD8+ T cells that were fine mapped to multiple sclerosis susceptibility variants in the viral control genes ZC3HAV1 (rs10271373) and IFITM2 (rs1059091). Further analysis suggests that these associations likely reflect genetic effects on RNA splicing and cell-type specific gene expression respectively. Collectively, our study suggests that alterations in viral control mechanisms might be important in the development of multiple sclerosis.
Assuntos
Esclerose Múltipla , Humanos , Linfócitos T CD8-Positivos , Regulação para Cima , Antivirais , Líquido Cefalorraquidiano/metabolismo , Proteínas de Membrana/genéticaRESUMO
Recent advances in molecular profiling provide descriptive datasets of complex differentiation landscapes including the haematopoietic system, but the molecular mechanisms defining progenitor states and lineage choice remain ill-defined. Here, we employed a cellular model of murine multipotent haematopoietic progenitors (Hoxb8-FL) to knock out 39 transcription factors (TFs) followed by RNA-Seq analysis, to functionally define a regulatory network of 16,992 regulator/target gene links. Focussed analysis of the subnetworks regulated by the B-lymphoid TF Ebf1 and T-lymphoid TF Gata3 revealed a surprising role in common activation of an early myeloid programme. Moreover, Gata3-mediated repression of Pax5 emerges as a mechanism to prevent precocious B-lymphoid differentiation, while Hox-mediated activation of Meis1 suppresses myeloid differentiation. To aid interpretation of large transcriptomics datasets, we also report a new method that visualises likely transitions that a progenitor will undergo following regulatory network perturbations. Taken together, this study reveals how molecular network wiring helps to establish a multipotent progenitor state, with experimental approaches and analysis tools applicable to dissecting a broad range of both normal and perturbed cellular differentiation landscapes.
Assuntos
Linhagem da Célula/fisiologia , Sistema Hematopoético/metabolismo , Fatores de Transcrição/metabolismo , Animais , Diferenciação Celular , Linhagem da Célula/genética , Epigenômica , Fator de Transcrição GATA3/genética , Fator de Transcrição GATA3/metabolismo , Hematopoese , Transplante de Células-Tronco Hematopoéticas , Camundongos , Proteína Meis1/metabolismo , Fator de Transcrição PAX5/genética , Fator de Transcrição PAX5/metabolismo , Células Precursoras de Linfócitos B , Fatores de Transcrição/genéticaRESUMO
Thymopoiesis depends on the recruitment and expansion of bone marrow-derived progenitor populations; tight regulation of these processes is required for maintenance of the homeostasis of the T lineage. Lyl-1, a transcription factor that regulates hematopoietic progenitors, is expressed in thymocyte progenitors until T cell commitment. Here we demonstrate a requirement for Lyl-1 in lymphoid specification and the maintenance of early T lineage progenitors (ETPs). Lyl-1 deficiency resulted in profound defects in the generation of lymphoid-primed multipotent progenitors (LMPPs), common lymphoid progenitors (CLPs) and ETPs. Lyl-1-deficient ETPs and thymocyte progenitors at the CD4(-)CD8(-) double-negative 2 (DN2) stage showed more apoptosis, blocked differentiation and impaired population expansion. We identified Gfi1 as a critical transcriptional target of Lyl-1-mediated lymphopoiesis of T cells. Thus, Lyl-1 is a pivotal component of a transcriptional program that controls the lymphoid specification and maintenance of ETPs.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Células Progenitoras Linfoides/fisiologia , Linfopoese , Proteínas de Neoplasias/metabolismo , Linfócitos T/imunologia , Animais , Apoptose/imunologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/deficiência , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Células da Medula Óssea/fisiologia , Antígenos CD4/biossíntese , Antígenos CD8/biossíntese , Linhagem da Célula , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Células Progenitoras Linfoides/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas de Neoplasias/deficiência , Proteínas de Neoplasias/genética , Linfócitos T/fisiologia , Timócitos/fisiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Hematopoietic stem cells (HSCs) are of major clinical importance, and finding methods for their in vitro generation is a prime research focus. We show here that the cell cycle inhibitor p57Kip2/Cdkn1c limits the number of emerging HSCs by restricting the size of the sympathetic nervous system (SNS) and the amount of HSC-supportive catecholamines secreted by these cells. This regulation occurs at the SNS progenitor level and is in contrast to the cell-intrinsic function of p57Kip2 in maintaining adult HSCs, highlighting profound differences in cell cycle requirements of adult HSCs compared with their embryonic counterparts. Furthermore, this effect is specific to the aorta-gonad-mesonephros (AGM) region and shows that the AGM is the main contributor to early fetal liver colonization, as early fetal liver HSC numbers are equally affected. Using a range of antagonists in vivo, we show a requirement for intact ß2-adrenergic signaling for SNS-dependent HSC expansion. To gain further molecular insights, we have generated a single-cell RNA-sequencing data set of all Ngfr+ sympathoadrenal cells around the dorsal aorta to dissect their differentiation pathway. Importantly, this not only defined the relevant p57Kip2-expressing SNS progenitor stage but also revealed that some neural crest cells, upon arrival at the aorta, are able to take an alternative differentiation pathway, giving rise to a subset of ventrally restricted mesenchymal cells that express important HSC-supportive factors. Neural crest cells thus appear to contribute to the AGM HSC niche via 2 different mechanisms: SNS-mediated catecholamine secretion and HSC-supportive mesenchymal cell production.
Assuntos
Células-Tronco Hematopoéticas , Mesonefro , Aorta , Diferenciação Celular , GônadasRESUMO
Adult hematopoietic stem cells (HSCs) are predominantly quiescent and can be activated in response to acute stress such as infection or cytotoxic insults. STAT1 is a pivotal downstream mediator of interferon (IFN) signaling and is required for IFN-induced HSC proliferation, but little is known about the role of STAT1 in regulating homeostatic hematopoietic stem/progenitor cells (HSPCs). Here, we show that loss of STAT1 altered the steady state HSPC landscape, impaired HSC function in transplantation assays, delayed blood cell regeneration following myeloablation, and disrupted molecular programs that protect HSCs, including control of quiescence. Our results also reveal STAT1-dependent functional HSC heterogeneity. A previously unrecognized subset of homeostatic HSCs with elevated major histocompatibility complex class II (MHCII) expression (MHCIIhi) displayed molecular features of reduced cycling and apoptosis and was refractory to 5-fluorouracil-induced myeloablation. Conversely, MHCIIlo HSCs displayed increased megakaryocytic potential and were preferentially expanded in CALR mutant mice with thrombocytosis. Similar to mice, high MHCII expression is a feature of human HSCs residing in a deeper quiescent state. Our results therefore position STAT1 at the interface of stem cell heterogeneity and the interplay between stem cells and the adaptive immune system, areas of broad interest in the wider stem cell field.
Assuntos
Células-Tronco Hematopoéticas , Megacariócitos , Fator de Transcrição STAT1 , Animais , Proliferação de Células , Fluoruracila/farmacologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Interferons , Megacariócitos/metabolismo , Camundongos , Fator de Transcrição STAT1/genética , Fator de Transcrição STAT1/metabolismoRESUMO
Rare hematopoietic stem and progenitor cell (HSPC) pools outside the bone marrow (BM) contribute to blood production in stress and disease but remain ill-defined. Although nonmobilized peripheral blood (PB) is routinely sampled for clinical management, the diagnosis and monitoring potential of PB HSPCs remain untapped, as no healthy PB HSPC baseline has been reported. Here we comprehensively delineate human extramedullary HSPC compartments comparing spleen, PB, and mobilized PB to BM using single-cell RNA-sequencing and/or functional assays. We uncovered HSPC features shared by extramedullary tissues and others unique to PB. First, in contrast to actively dividing BM HSPCs, we found no evidence of substantial ongoing hematopoiesis in extramedullary tissues at steady state but report increased splenic HSPC proliferative output during stress erythropoiesis. Second, extramedullary hematopoietic stem cells/multipotent progenitors (HSCs/MPPs) from spleen, PB, and mobilized PB share a common transcriptional signature and increased abundance of lineage-primed subsets compared with BM. Third, healthy PB HSPCs display a unique bias toward erythroid-megakaryocytic differentiation. At the HSC/MPP level, this is functionally imparted by a subset of phenotypic CD71+ HSCs/MPPs, exclusively producing erythrocytes and megakaryocytes, highly abundant in PB but rare in other adult tissues. Finally, the unique erythroid-megakaryocytic-skewing of PB is perturbed with age in essential thrombocythemia and ß-thalassemia. Collectively, we identify extramedullary lineage-primed HSPC reservoirs that are nonproliferative in situ and report involvement of splenic HSPCs during demand-adapted hematopoiesis. Our data also establish aberrant composition and function of circulating HSPCs as potential clinical indicators of BM dysfunction.
Assuntos
Hematopoese , Células-Tronco Hematopoéticas , Adulto , Medula Óssea , Células da Medula Óssea/fisiologia , Eritropoese , Humanos , MegacariócitosRESUMO
Hematopoietic stem and progenitor cell (HSPC) formation and lineage differentiation involve gene expression programs orchestrated by transcription factors and epigenetic regulators. Genetic disruption of the chromatin remodeler chromodomain-helicase-DNA-binding protein 7 (CHD7) expanded phenotypic HSPCs, erythroid, and myeloid lineages in zebrafish and mouse embryos. CHD7 acts to suppress hematopoietic differentiation. Binding motifs for RUNX and other hematopoietic transcription factors are enriched at sites occupied by CHD7, and decreased RUNX1 occupancy correlated with loss of CHD7 localization. CHD7 physically interacts with RUNX1 and suppresses RUNX1-induced expansion of HSPCs during development through modulation of RUNX1 activity. Consequently, the RUNX1:CHD7 axis provides proper timing and function of HSPCs as they emerge during hematopoietic development or mature in adults, representing a distinct and evolutionarily conserved control mechanism to ensure accurate hematopoietic lineage differentiation.
Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core , Proteínas de Ligação a DNA , Hematopoese , Animais , Diferenciação Celular , Linhagem Celular , Subunidade alfa 2 de Fator de Ligação ao Core/química , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Feminino , Células-Tronco Hematopoéticas , Humanos , Masculino , Camundongos , Baço/citologia , Peixe-ZebraRESUMO
In mammals, specification of the three major germ layers occurs during gastrulation, when cells ingressing through the primitive streak differentiate into the precursor cells of major organ systems. However, the molecular mechanisms underlying this process remain unclear, as numbers of gastrulating cells are very limited. In the mouse embryo at embryonic day 6.5, cells located at the junction between the extra-embryonic region and the epiblast on the posterior side of the embryo undergo an epithelial-to-mesenchymal transition and ingress through the primitive streak. Subsequently, cells migrate, either surrounding the prospective ectoderm contributing to the embryo proper, or into the extra-embryonic region to form the yolk sac, umbilical cord and placenta. Fate mapping has shown that mature tissues such as blood and heart originate from specific regions of the pre-gastrula epiblast, but the plasticity of cells within the embryo and the function of key cell-type-specific transcription factors remain unclear. Here we analyse 1,205 cells from the epiblast and nascent Flk1(+) mesoderm of gastrulating mouse embryos using single-cell RNA sequencing, representing the first transcriptome-wide in vivo view of early mesoderm formation during mammalian gastrulation. Additionally, using knockout mice, we study the function of Tal1, a key haematopoietic transcription factor, and demonstrate, contrary to previous studies performed using retrospective assays, that Tal1 knockout does not immediately bias precursor cells towards a cardiac fate.
Assuntos
Embrião de Mamíferos/citologia , Gastrulação/genética , Perfilação da Expressão Gênica , Mesoderma/citologia , Mesoderma/embriologia , Análise de Célula Única , Transcriptoma/genética , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/deficiência , Linhagem da Célula/genética , Embrião de Mamíferos/embriologia , Embrião de Mamíferos/metabolismo , Eritropoese/genética , Gástrula/citologia , Gástrula/metabolismo , Mesoderma/metabolismo , Camundongos , Proteínas Proto-Oncogênicas/deficiência , Análise de Sequência de DNA , Proteína 1 de Leucemia Linfocítica Aguda de Células TRESUMO
Cohesin complex disruption alters gene expression, and cohesin mutations are common in myeloid neoplasia, suggesting a critical role in hematopoiesis. Here, we explore cohesin dynamics and regulation of hematopoietic stem cell homeostasis and differentiation. Cohesin binding increases at active regulatory elements only during erythroid differentiation. Prior binding of the repressive Ets transcription factor Etv6 predicts cohesin binding at these elements and Etv6 interacts with cohesin at chromatin. Depletion of cohesin severely impairs erythroid differentiation, particularly at Etv6-prebound loci, but augments self-renewal programs. Together with corroborative findings in acute myeloid leukemia and myelodysplastic syndrome patient samples, these data suggest cohesin-mediated alleviation of Etv6 repression is required for dynamic expression at critical erythroid genes during differentiation and how this may be perturbed in myeloid malignancies.
Assuntos
Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Regulação Leucêmica da Expressão Gênica , Mutação , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/metabolismo , Biomarcadores Tumorais , Linhagem Celular Tumoral , Feminino , Dosagem de Genes , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Histonas/metabolismo , Humanos , Masculino , Transtornos Mieloproliferativos/diagnóstico , Gradação de Tumores , Ligação Proteica , Proteínas Proto-Oncogênicas c-ets/metabolismo , Sequências Reguladoras de Ácido Nucleico , Proteínas Repressoras/metabolismo , Coesinas , Variante 6 da Proteína do Fator de Translocação ETSRESUMO
BACKGROUND: Basophils and mast cells contribute to the development of allergic reactions. Whereas these mature effector cells are extensively studied, the differentiation trajectories from hematopoietic progenitors to basophils and mast cells are largely uncharted at the single-cell level. METHODS: We performed multicolor flow cytometry, high-coverage single-cell RNA sequencing analyses, and cell fate assays to chart basophil and mast cell differentiation at single-cell resolution in mouse. RESULTS: Analysis of flow cytometry data reconstructed a detailed map of basophil and mast cell differentiation, including a bifurcation of progenitors into two specific trajectories. Molecular profiling and pseudotime ordering of the single cells revealed gene expression changes during differentiation. Cell fate assays showed that multicolor flow cytometry and transcriptional profiling successfully predict the bipotent phenotype of a previously uncharacterized population of peritoneal basophil-mast cell progenitors. CONCLUSIONS: A combination of molecular and functional profiling of bone marrow and peritoneal cells provided a detailed road map of basophil and mast cell development. An interactive web resource was created to enable the wider research community to explore the expression dynamics for any gene of interest.
Assuntos
Basófilos , Mastócitos , Animais , Células da Medula Óssea , Diferenciação Celular , Camundongos , Células-TroncoRESUMO
Runx1 is an important haematopoietic transcription factor as stressed by its involvement in a number of haematological malignancies. Furthermore, it is a key regulator of the emergence of the first haematopoietic stem cells (HSCs) during development. The transcription factor Gata3 has also been linked to haematological disease and was shown to promote HSC production in the embryo by inducing the secretion of important niche factors. Both proteins are expressed in several different cell types within the aorta-gonads-mesonephros (AGM) region, in which the first HSCs are generated; however, a direct interaction between these two key transcription factors in the context of embryonic HSC production has not formally been demonstrated. In this current study, we have detected co-localisation of Runx1 and Gata3 in rare sub-aortic mesenchymal cells in the AGM. Furthermore, the expression of Runx1 is reduced in Gata3 -/- embryos, which also display a shift in HSC emergence. Using an AGM-derived cell line as a model for the stromal microenvironment in the AGM and performing ChIP-Seq and ChIP-on-chip experiments, we demonstrate that Runx1, together with other key niche factors, is a direct target gene of Gata3. In addition, we can pinpoint Gata3 binding to the Runx1 locus at specific enhancer elements which are active in the microenvironment. These results reveal a direct interaction between Gata3 and Runx1 in the niche that supports embryonic HSCs and highlight a dual role for Runx1 in driving the transdifferentiation of haemogenic endothelial cells into HSCs as well as in the stromal cells that support this process.
Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário , Endotélio Vascular/citologia , Fator de Transcrição GATA3/metabolismo , Células-Tronco Hematopoéticas/citologia , Animais , Aorta/citologia , Aorta/metabolismo , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Embrião de Mamíferos/metabolismo , Endotélio Vascular/metabolismo , Feminino , Fator de Transcrição GATA3/genética , Gônadas/citologia , Gônadas/metabolismo , Hematopoese , Células-Tronco Hematopoéticas/metabolismo , Mesonefro/citologia , Mesonefro/metabolismo , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Recent advances in single-cell technologies have permitted the investigation of heterogeneous cell populations at previously unattainable resolution. Here we apply such approaches to resolve the molecular mechanisms driving disease in mouse hematopoietic stem cells (HSCs), using JAK2V617F mutant myeloproliferative neoplasms (MPNs) as a model. Single-cell gene expression and functional assays identified a subset of JAK2V617F mutant HSCs that display defective self-renewal. This defect is rescued at the single HSC level by crossing JAK2V617F mice with mice lacking TET2, the most commonly comutated gene in patients with MPN. Single-cell gene expression profiling of JAK2V617F-mutant HSCs revealed a loss of specific regulator genes, some of which were restored to normal levels in single TET2/JAK2 mutant HSCs. Of these, Bmi1 and, to a lesser extent, Pbx1 and Meis1 overexpression in JAK2-mutant HSCs could drive a disease phenotype and retain durable stem cell self-renewal in functional assays. Together, these single-cell approaches refine the molecules involved in clonal expansion of MPNs and have broad implications for deconstructing the molecular network of normal and malignant stem cells.
Assuntos
Autorrenovação Celular , Regulação Neoplásica da Expressão Gênica , Neoplasias Hematológicas/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Janus Quinase 2/metabolismo , Mutação de Sentido Incorreto , Transtornos Mieloproliferativos/metabolismo , Proteínas de Neoplasias/metabolismo , Células-Tronco Neoplásicas/metabolismo , Substituição de Aminoácidos , Animais , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/patologia , Células-Tronco Hematopoéticas/patologia , Janus Quinase 2/genética , Camundongos , Camundongos Transgênicos , Transtornos Mieloproliferativos/genética , Transtornos Mieloproliferativos/patologia , Proteínas de Neoplasias/genética , Células-Tronco Neoplásicas/patologiaRESUMO
Hematopoietic stem and progenitor cells (HSPCs) maintain the adult blood system, and their dysregulation causes a multitude of diseases. However, the differentiation journeys toward specific hematopoietic lineages remain ill defined, and system-wide disease interpretation remains challenging. Here, we have profiled 44 802 mouse bone marrow HSPCs using single-cell RNA sequencing to provide a comprehensive transcriptional landscape with entry points to 8 different blood lineages (lymphoid, megakaryocyte, erythroid, neutrophil, monocyte, eosinophil, mast cell, and basophil progenitors). We identified a common basophil/mast cell bone marrow progenitor and characterized its molecular profile at the single-cell level. Transcriptional profiling of 13 815 HSPCs from the c-Kit mutant (W41/W41) mouse model revealed the absence of a distinct mast cell lineage entry point, together with global shifts in cell type abundance. Proliferative defects were accompanied by reduced Myc expression. Potential compensatory processes included upregulation of the integrated stress response pathway and downregulation of proapoptotic gene expression in erythroid progenitors, thus providing a template of how large-scale single-cell transcriptomic studies can bridge between molecular phenotypes and quantitative population changes.
Assuntos
Diferenciação Celular/genética , Linhagem da Célula/genética , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Mutação , Proteínas Proto-Oncogênicas c-kit/deficiência , Animais , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , Perfilação da Expressão Gênica , Camundongos , Camundongos Knockout , Proteínas Proto-Oncogênicas c-kit/metabolismo , Transdução de Sinais , Análise de Célula Única , TranscriptomaRESUMO
Adult blood contains a mixture of mature cell types, each with specialized functions. Single hematopoietic stem cells (HSCs) have been functionally shown to generate all mature cell types for the lifetime of the organism. Differentiation of HSCs toward alternative lineages must be balanced at the population level by the fate decisions made by individual cells. Transcription factors play a key role in regulating these decisions and operate within organized regulatory programs that can be modeled as transcriptional regulatory networks. As dysregulation of single HSC fate decisions is linked to fatal malignancies such as leukemia, it is important to understand how these decisions are controlled on a cell-by-cell basis. Here we developed and applied a network inference method, exploiting the ability to infer dynamic information from single-cell snapshot expression data based on expression profiles of 48 genes in 2,167 blood stem and progenitor cells. This approach allowed us to infer transcriptional regulatory network models that recapitulated differentiation of HSCs into progenitor cell types, focusing on trajectories toward megakaryocyte-erythrocyte progenitors and lymphoid-primed multipotent progenitors. By comparing these two models, we identified and subsequently experimentally validated a difference in the regulation of nuclear factor, erythroid 2 (Nfe2) and core-binding factor, runt domain, alpha subunit 2, translocated to, 3 homolog (Cbfa2t3h) by the transcription factor Gata2. Our approach confirms known aspects of hematopoiesis, provides hypotheses about regulation of HSC differentiation, and is widely applicable to other hierarchical biological systems to uncover regulatory relationships.
Assuntos
Redes Reguladoras de Genes , Hematopoese/genética , Células-Tronco Hematopoéticas/citologia , Algoritmos , Animais , Diferenciação Celular , Camundongos Endogâmicos C57BL , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/fisiologiaRESUMO
Despite major advances in the generation of genome-wide binding maps, the mechanisms by which transcription factors (TFs) regulate cell type identity have remained largely obscure. Through comparative analysis of 10 key haematopoietic TFs in both mast cells and blood progenitors, we demonstrate that the largely cell type-specific binding profiles are not opportunistic, but instead contribute to cell type-specific transcriptional control, because (i) mathematical modelling of differential binding of shared TFs can explain differential gene expression, (ii) consensus binding sites are important for cell type-specific binding and (iii) knock-down of blood stem cell regulators in mast cells reveals mast cell-specific genes as direct targets. Finally, we show that the known mast cell regulators Mitf and c-fos likely contribute to the global reorganisation of TF binding profiles. Taken together therefore, our study elucidates how key regulatory TFs contribute to transcriptional programmes in several distinct mammalian cell types.