RESUMEN

A major next step in hematopoietic stem cell (HSC) biology is to enhance our quantitative understanding of cellular and evolutionary dynamics involved in undisturbed hematopoiesis. Mathematical models have been and continue to be key in this respect, and are most powerful when parameterized experimentally and containing sufficient biological complexity. In this paper, we use data from label propagation experiments in mice to parameterize a mathematical model of hematopoiesis that includes homeostatic control mechanisms as well as clonal evolution. We find that nonlinear feedback control can drastically change the interpretation of kinetic estimates at homeostasis. This suggests that short-term HSC and multipotent progenitors can dynamically adjust to sustain themselves temporarily in the absence of long-term HSCs, even if they differentiate more often than they self-renew in undisturbed homeostasis. Additionally, the presence of feedback control in the model renders the system resilient against mutant invasion. Invasion barriers, however, can be overcome by a combination of age-related changes in stem cell differentiation and evolutionary niche construction dynamics based on a mutant-associated inflammatory environment. This helps us understand the evolution of e.g., TET2 or DNMT3A mutants, and how to potentially reduce mutant burden.

Asunto(s)

Diferenciación Celular , Hematopoyesis , Células Madre Hematopoyéticas , Mutación , Animales , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Ratones , Hematopoyesis/genética , Hematopoyesis/fisiología , ADN Metiltransferasa 3A/metabolismo , Homeostasis , ADN (Citosina-5-)-Metiltransferasas/metabolismo , ADN (Citosina-5-)-Metiltransferasas/genética , Modelos Biológicos , Linaje de la Célula , Dioxigenasas , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Evolución Clonal , Modelos Teóricos

RESUMEN

Age is a risk factor for hematologic malignancies. Attributes of the aging hematopoietic system include increased myelopoiesis, impaired adaptive immunity, and a functional decline of the hematopoietic stem cells (HSCs) that maintain hematopoiesis. Changes in the composition of diverse HSC subsets have been suggested to be responsible for age-related alterations, however, the underlying regulatory mechanisms are incompletely understood in the context of HSC heterogeneity. In this study, we investigated how distinct HSC subsets, separated by CD49b, functionally and molecularly change their behavior with age. We demonstrate that the lineage differentiation of both lymphoid-biased and myeloid-biased HSC subsets progressively shifts to a higher myeloid cellular output during aging. In parallel, we show that HSCs selectively undergo age-dependent gene expression and gene regulatory changes in a progressive manner, which is initiated already in the juvenile stage. Overall, our studies suggest that aging intrinsically alters both cellular and molecular properties of HSCs.

Asunto(s)

Envejecimiento , Células Madre Hematopoyéticas , Ratones Endogámicos C57BL , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/citología , Animales , Envejecimiento/genética , Envejecimiento/fisiología , Ratones , Diferenciación Celular , Linaje de la Célula/genética , Hematopoyesis/genética , Células Mieloides/metabolismo , Células Mieloides/citología , Masculino , Regulación de la Expresión Génica , Femenino

RESUMEN

Arterial endothelial cells (AECs) are the founder cells for intraembryonic haematopoiesis. Here, we report a method for the efficient generation of human haemogenic DLL4+ AECs from pluripotent stem cells (PSC). Time-series single-cell RNA-sequencing reveals the dynamic evolution of haematopoiesis and lymphopoiesis, generating cell types with counterparts present in early human embryos, including stages marked by the pre-haematopoietic stem cell genes MECOM/EVI1, MLLT3 and SPINK2. DLL4+ AECs robustly support lymphoid differentiation, without the requirement for exogenous NOTCH ligands. Using this system, we find IL7 acts as a morphogenic factor determining the fate choice between the T and innate lymphoid lineages and also plays a role in regulating the relative expression level of RAG1. Moreover, we document a developmental pathway by which human RAG1+ lymphoid precursors give rise to the natural killer cell lineage. Our study describes an efficient method for producing lymphoid progenitors, providing insights into their endothelial and haematopoietic ontogeny, and establishing a platform to investigate the development of the human blood system.

Asunto(s)

Hematopoyesis , Linfopoyesis , Humanos , Hematopoyesis/genética , Linfopoyesis/genética , Células Endoteliales/metabolismo , Células Endoteliales/citología , Diferenciación Celular , Linaje de la Célula/genética , Interleucina-7/metabolismo , Interleucina-7/genética , Células Madre Pluripotentes/metabolismo , Células Madre Pluripotentes/citología , Proteínas de Unión al Calcio/metabolismo , Proteínas de Unión al Calcio/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Células Asesinas Naturales/metabolismo , Células Asesinas Naturales/citología , Hemangioblastos/metabolismo , Hemangioblastos/citología , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Proteínas de Homeodominio/metabolismo , Proteínas de Homeodominio/genética , Análisis de la Célula Individual/métodos , Receptores Notch/metabolismo , Receptores Notch/genética

RESUMEN

Tropomyosins coat actin filaments to impact actin-related signaling and cell morphogenesis. Genome-wide association studies have linked Tropomyosin 1 (TPM1) with human blood trait variation. TPM1 has been shown to regulate blood cell formation in vitro, but it remains unclear how or when TPM1 affects hematopoiesis. Using gene-edited induced pluripotent stem cell (iPSC) model systems, we found that TPM1 knockout augmented developmental cell state transitions and key signaling pathways, including tumor necrosis factor alpha (TNF-α) signaling, to promote hemogenic endothelial (HE) cell specification and hematopoietic progenitor cell (HPC) production. Single-cell analyses revealed decreased TPM1 expression during human HE specification, suggesting that TPM1 regulated in vivo hematopoiesis via similar mechanisms. Analyses of a TPM1 gene trap mouse model showed that TPM1 deficiency enhanced HE formation during embryogenesis, without increasing the number of hematopoietic stem cells. These findings illuminate novel effects of TPM1 on developmental hematopoiesis.

Asunto(s)

Diferenciación Celular , Hematopoyesis , Células Madre Hematopoyéticas , Tropomiosina , Tropomiosina/metabolismo , Tropomiosina/genética , Hematopoyesis/genética , Animales , Humanos , Ratones , Diferenciación Celular/genética , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/citología , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes Inducidas/citología , Hemangioblastos/metabolismo , Hemangioblastos/citología , Transducción de Señal , Células Endoteliales/metabolismo , Células Endoteliales/citología , Factor de Necrosis Tumoral alfa/metabolismo

RESUMEN

Recently, we have reported that extracellular vesicles (EVs) from the bone marrow mesenchymal stromal cells (BM-MSC) of aplastic anemia (AA) patients inhibit hematopoietic stem and progenitor cell (HSPC) proliferative and colony-forming ability and promote apoptosis. One mechanism by which AA BM-MSC EVs might contribute to these altered HSPC functions is through microRNAs (miRNAs) encapsulated in EVs. However, little is known about the role of BM-MSC EVs derived miRNAs in regulating HSPC functions in AA. Therefore, we performed miRNA profiling of EVs from BM-MSC of AA (n = 6) and normal controls (NC) (n = 6) to identify differentially expressed miRNAs. The Integrated DEseq2 analysis revealed 34 significantly altered mature miRNAs, targeting 235 differentially expressed HSPC genes in AA. Hub gene analysis revealed 10 HSPC genes such as IGF-1R, IGF2R, PAK1, PTPN1, etc., which are targeted by EV miRNAs and had an enrichment of chemokine, MAPK, NK cell-mediated cytotoxicity, Rap1, PI3k-Akt, mTOR signalling pathways which are associated with hematopoietic homeostasis. We further showed that miR-139-5p and its target, IGF-1R (hub-gene), might regulate HSPC proliferation and apoptosis, which may serve as potential therapeutic targets in AA. Overall, the study highlights that AA BM-MSC EV miRNAs could contribute to impaired HSPC functions in AA.

Asunto(s)

Anemia Aplásica , Vesículas Extracelulares , Perfilación de la Expresión Génica , Células Madre Mesenquimatosas , MicroARNs , Anemia Aplásica/genética , Anemia Aplásica/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/genética , Humanos , Células Madre Mesenquimatosas/metabolismo , Células Madre Hematopoyéticas/metabolismo , Femenino , Masculino , Adulto , Persona de Mediana Edad , Hematopoyesis/genética , Apoptosis/genética , Células de la Médula Ósea/metabolismo , Transducción de Señal

RESUMEN

The number of somatic mutations among all tissues increases along with age. This process was well-studied in hematopoietic stem cells (HSCs). Some mutations lead to a proliferative advantage and expansion of HSCs to form a dominant clone. Clonal hematopoiesis is general in the elderly population. Clonal hematopoiesis of indeterminate potential (CHIP) is a more common phenomenon in the elderly and is defined as somatic mutations in clonal blood cells without any other hematological malignancies. The development of CHIP is an independent risk factor for hematological malignancies, cardiovascular diseases, and reduced overall survival. CHIP is frequently associated with mutations in DNMT3A and TET2 genes involved in DNA methylation. The epigenetic human body clocks have been developed based on the age-related changes in methylation, making it possible to detect epigenetic aging. The combination of epigenetic aging and CHUP is associated with adverse health outcomes. Further research will reveal the significance of clonal hematopoiesis and CHIP in aging, acquiring various diseases, and determining the feasibility of influencing the mutagenic potential of clones.

Asunto(s)

Envejecimiento , Hematopoyesis Clonal , Epigénesis Genética , Humanos , Envejecimiento/fisiología , Envejecimiento/genética , Hematopoyesis Clonal/genética , Mutación , Metilación de ADN , Células Madre Hematopoyéticas/metabolismo , ADN Metiltransferasa 3A , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/diagnóstico , Dioxigenasas , Hematopoyesis/genética , Hematopoyesis/fisiología , ADN (Citosina-5-)-Metiltransferasas/genética

RESUMEN

MYB is a master regulator and pioneer factor highly expressed in hematopoietic progenitor cells (HPCs) where it contributes to the reprogramming processes operating during hematopoietic development. MYB plays a complex role being involved in several lineages of the hematopoietic system. At the molecular level, the MYB gene is subject to intricate regulation at many levels through several enhancer and promoter elements, through transcriptional elongation control, as well as post-transcriptional regulation. The protein is modulated by post-translational modifications (PTMs) such as SUMOylation restricting the expression of its downstream targets. Together with a range of interaction partners, cooperating transcription factors (TFs) and epigenetic regulators, MYB orchestrates a fine-tuned symphony of genes expressed during various stages of haematopoiesis. At the same time, the complex MYB system is vulnerable, being a target for unbalanced control and cancer development.

Asunto(s)

Hematopoyesis , Células Madre Hematopoyéticas , Proteínas Proto-Oncogénicas c-myb , Humanos , Hematopoyesis/genética , Células Madre Hematopoyéticas/metabolismo , Proteínas Proto-Oncogénicas c-myb/metabolismo , Proteínas Proto-Oncogénicas c-myb/genética , Animales , Procesamiento Proteico-Postraduccional , Epigénesis Genética , Regulación de la Expresión Génica

RESUMEN

Hematopoiesis is a continuous process of blood cell production driven by hematopoietic stem and progenitor cells (HSPCs) in the bone marrow. Proliferation and differentiation of HSPCs are regulated by complex transcriptional networks. In order to identify transcription factors with key roles in HSPC-mediated hematopoietic reconstitution, we developed an efficient and robust CRISPR/Cas9-based in vivo genetic screen. Using this experimental system, we identified the TFDP1 transcription factor to be essential for HSPC proliferation and post-transplant hematopoiesis. We further discovered that E2F4, an E2F transcription factor, serves as a binding partner of TFDP1 and is required for HSPC proliferation. Deletion of TFDP1 caused downregulation of genes associated with the cell cycle, with around 50% of these genes being identified as direct targets of TFDP1 and E2F4. Thus, our study expands the transcriptional network governing hematopoietic development through an in vivo CRISPR/Cas9-based genetic screen and identifies TFDP1/E2F4 as positive regulators of cell cycle genes in HSPCs.

Asunto(s)

Sistemas CRISPR-Cas , Factor de Transcripción E2F4 , Hematopoyesis , Células Madre Hematopoyéticas , Factor de Transcripción DP1 , Animales , Humanos , Ratones , Ciclo Celular/genética , Diferenciación Celular/genética , Proliferación Celular , Factor de Transcripción E2F4/genética , Factor de Transcripción E2F4/metabolismo , Hematopoyesis/genética , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/citología , Ratones Endogámicos C57BL , Factor de Transcripción DP1/genética , Factor de Transcripción DP1/metabolismo

RESUMEN

ABSTRACT: Recent advancements in single-cell genomics have enriched our understanding of hematopoiesis, providing intricate details about hematopoietic stem cell biology, differentiation, and lineage commitment. Technological advancements have highlighted extensive heterogeneity of cell populations and continuity of differentiation routes. Nevertheless, intermediate "attractor" states signify structure in stem and progenitor populations that link state transition dynamics to fate potential. We discuss how innovative model systems quantify lineage bias and how stress accelerates differentiation, thereby reducing fate plasticity compared with native hematopoiesis. We conclude by offering our perspective on the current model of hematopoiesis and discuss how a more precise understanding can translate to strategies that extend healthy hematopoiesis and prevent disease.

Asunto(s)

Genómica , Hematopoyesis , Células Madre Hematopoyéticas , Análisis de la Célula Individual , Hematopoyesis/genética , Humanos , Análisis de la Célula Individual/métodos , Genómica/métodos , Animales , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/metabolismo , Diferenciación Celular/genética , Linaje de la Célula/genética

RESUMEN

BACKGROUND: Myelodysplastic syndrome (MDS) is a complicated hematopoietic malignancy characterized by bone marrow (BM) dysplasia with symptoms like anemia, neutropenia, or thrombocytopenia. MDS exhibits considerable heterogeneity in prognosis, with approximately 30% of patients progressing to acute myeloid leukemia (AML). Single cell RNA-sequencing (scRNA-seq) is a new and powerful technique to profile disease landscapes. However, the current available scRNA-seq datasets for MDS are only focused on CD34+ hematopoietic progenitor cells. We argue that using entire BM cell for MDS studies probably will be more informative for understanding the pathophysiology of MDS. METHODS: Five MDS patients and four healthy donors were enrolled in the study. Unsorted cells from BM aspiration were collected for scRNA-seq analysis to profile overall alteration in hematopoiesis. RESULTS: Standard scRNA-seq analysis of unsorted BM cells successfully profiles deficient hematopoiesis in all five MDS patients, with three classified as high-risk and two as low-risk. While no significant increase in mutation burden was observed, high-risk MDS patients exhibited T-cell activation and abnormal myelogenesis at the stages between hematopoietic stem and progenitor cells (HSPC) and granulocyte-macrophage progenitors (GMP). Transcriptional factor analysis on the aberrant myelogenesis suggests that the epigenetic regulator chromatin structural protein-encoding gene HMGA1 is highly activated in the high-risk MDS group and moderately activated in the low-risk MDS group. Perturbation of HMGA1 by CellOracle simulated deficient hematopoiesis in mouse Lineage-negative (Lin-) BM cells. Projecting MDS and AML cells on a BM cell reference by our newly developed MarcoPolo pipeline intuitively visualizes a connection for myeloid leukemia development and abnormalities of hematopoietic hierarchy, indicating that it is technically feasible to integrate all diseased bone marrow cells on a common reference map even when the size of the cohort reaches to 1,000 patients or more. CONCLUSION: Through scRNA-seq analysis on unsorted cells from BM aspiration samples of MDS patients, this study systematically profiled the development abnormalities in hematopoiesis, heterogeneity of risk, and T-cell microenvironment at the single cell level.

Asunto(s)

Genómica , Hematopoyesis , Síndromes Mielodisplásicos , Análisis de la Célula Individual , Humanos , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/patología , Hematopoyesis/genética , Femenino , Masculino , Persona de Mediana Edad , Anciano , Células Madre Hematopoyéticas/metabolismo , Microambiente Celular , Mutación/genética

RESUMEN

Leukemias with ambiguous lineage comprise several loosely defined entities, often without a clear mechanistic basis. Here, we extensively profile the epigenome and transcriptome of a subgroup of such leukemias with CpG Island Methylator Phenotype. These leukemias exhibit comparable hybrid myeloid/lymphoid epigenetic landscapes, yet heterogeneous genetic alterations, suggesting they are defined by their shared epigenetic profile rather than common genetic lesions. Gene expression enrichment reveals similarity with early T-cell precursor acute lymphoblastic leukemia and a lymphoid progenitor cell of origin. In line with this, integration of differential DNA methylation and gene expression shows widespread silencing of myeloid transcription factors. Moreover, binding sites for hematopoietic transcription factors, including CEBPA, SPI1 and LEF1, are uniquely inaccessible in these leukemias. Hypermethylation also results in loss of CTCF binding, accompanied by changes in chromatin interactions involving key transcription factors. In conclusion, epigenetic dysregulation, and not genetic lesions, explains the mixed phenotype of this group of leukemias with ambiguous lineage. The data collected here constitute a useful and comprehensive epigenomic reference for subsequent studies of acute myeloid leukemias, T-cell acute lymphoblastic leukemias and mixed-phenotype leukemias.

Asunto(s)

Islas de CpG , Metilación de ADN , Epigénesis Genética , Redes Reguladoras de Genes , Humanos , Metilación de ADN/genética , Islas de CpG/genética , Proteínas Potenciadoras de Unión a CCAAT/genética , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Factor de Unión 1 al Potenciador Linfoide/genética , Factor de Unión 1 al Potenciador Linfoide/metabolismo , Factor de Unión a CCCTC/metabolismo , Factor de Unión a CCCTC/genética , Regulación Leucémica de la Expresión Génica , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Cromatina/metabolismo , Cromatina/genética , Masculino , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patología , Femenino , Hematopoyesis/genética , Niño , Transcriptoma , Proteínas Proto-Oncogénicas , Transactivadores

RESUMEN

Germline heterozygous mutations in DDX41 predispose individuals to hematologic malignancies in adulthood. Most of these DDX41 mutations result in a truncated protein, leading to loss of protein function. To investigate the impact of these mutations on hematopoiesis, we generated mice with hematopoietic-specific knockout of one Ddx41 allele. Under normal steady-state conditions, there was minimal effect on lifelong hematopoiesis, resulting in a mild yet persistent reduction in red blood cell counts. However, stress induced by transplantation of the Ddx41+/- BM resulted in hematopoietic stem/progenitor cell (HSPC) defects and onset of hematopoietic failure upon aging. Transcriptomic analysis of HSPC subsets from the transplanted BM revealed activation of cellular stress responses, including upregulation of p53 target genes in erythroid progenitors. To understand how the loss of p53 affects the phenotype of Ddx41+/- HSPCs, we generated mice with combined Ddx41 and Trp53 heterozygous deletions. The reduction in p53 expression rescued the fitness defects in HSPC caused by Ddx41 heterozygosity. However, the combined Ddx41 and Trp53 mutant mice were prone to developing hematologic malignancies that resemble human myelodysplastic syndrome and acute myeloid leukemia. In conclusion, DDX41 heterozygosity causes dysregulation of the response to hematopoietic stress, which increases the risk of transformation with a p53 mutation.

Asunto(s)

ARN Helicasas DEAD-box , Haploinsuficiencia , Neoplasias Hematológicas , Hematopoyesis , Mutación , Proteína p53 Supresora de Tumor , Animales , Humanos , Ratones , ARN Helicasas DEAD-box/genética , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/patología , Neoplasias Hematológicas/etiología , Hematopoyesis/genética , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/patología , Ratones Endogámicos C57BL , Ratones Noqueados , Estrés Fisiológico/genética , Proteína p53 Supresora de Tumor/genética

RESUMEN

The ETS transcription factor PU.1 plays an essential role in blood cell development. Its precise expression pattern is governed by cis-regulatory elements (CRE) acting at the chromatin level. CREs mediate the fine-tuning of graded levels of PU.1, deviations of which can cause acute myeloid leukemia. In this review, we perform an in-depth analysis of the regulation of PU.1 expression in normal and malignant hematopoiesis. We elaborate on the role of trans-acting factors and the biomolecular interplays in mediating local chromatin dynamics. Moreover, we discuss the current understanding of CRE bifunctionality exhibiting enhancer or silencer activities in different blood cell lineages and future directions toward gene-specific chromatin-targeted therapeutic development.

Asunto(s)

Hematopoyesis , Proteínas Proto-Oncogénicas , Transactivadores , Humanos , Hematopoyesis/genética , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Transactivadores/genética , Transactivadores/metabolismo , Linaje de la Célula , Animales , Transcripción Genética , Regulación de la Expresión Génica , Leucemia Mieloide Aguda/genética , Cromatina/metabolismo , Cromatina/genética

RESUMEN

BACKGROUND: The endothelial-to-hematopoietic transition (EHT) process during definitive hematopoiesis is highly conserved in vertebrates. Stage-specific expression of transposable elements (TEs) has been detected during zebrafish EHT and may promote hematopoietic stem cell (HSC) formation by activating inflammatory signaling. However, little is known about how TEs contribute to the EHT process in human and mouse. RESULTS: We reconstructed the single-cell EHT trajectories of human and mouse and resolved the dynamic expression patterns of TEs during EHT. Most TEs presented a transient co-upregulation pattern along the conserved EHT trajectories, coinciding with the temporal relaxation of epigenetic silencing systems. TE products can be sensed by multiple pattern recognition receptors, triggering inflammatory signaling to facilitate HSC emergence. Interestingly, we observed that hypoxia-related signals were enriched in cells with higher TE expression. Furthermore, we constructed the hematopoietic cis-regulatory network of accessible TEs and identified potential TE-derived enhancers that may boost the expression of specific EHT marker genes. CONCLUSIONS: Our study provides a systematic vision of how TEs are dynamically controlled to promote the hematopoietic fate decisions through transcriptional and cis-regulatory networks, and pre-train the immunity of nascent HSCs.

Asunto(s)

Elementos Transponibles de ADN , Hematopoyesis , Células Madre Hematopoyéticas , Análisis de la Célula Individual , Animales , Elementos Transponibles de ADN/genética , Análisis de la Célula Individual/métodos , Ratones , Hematopoyesis/genética , Humanos , Células Madre Hematopoyéticas/metabolismo , Células Endoteliales/metabolismo

RESUMEN

MicroRNAs (miRNAs) are small non-coding RNAs which contribute to the regulation of many physiological and pathological processes. Conventionally, miRNAs perform their activity in the cytoplasm where they regulate gene expression by interacting in a sequence-specific manner with mature messenger RNAs. Recent studies point to the presence of mature miRNAs in the nucleus. This review summarizes current findings regarding the molecular activities of nuclear miRNAs. These molecules can regulate gene expression at the transcriptional level by directly binding DNA on the promoter or the enhancer of regulated genes. miRNAs recruit different protein complexes to these regions, resulting in activation or repression of transcription, through a number of molecular mechanisms. Hematopoiesis is presented as a paradigmatic biological process whereby nuclear miRNAs possess a relevant regulatory role. Nuclear miRNAs can influence gene expression by affecting nuclear mRNA processing and by regulating pri-miRNA maturation, thus impacting the biogenesis of miRNAs themselves. Overall, nuclear miRNAs are biologically active molecules that can be critical for the fine tuning of gene expression and deserve further studies in a number of physiological and pathological conditions.

Asunto(s)

Núcleo Celular , Regulación de la Expresión Génica , MicroARNs , MicroARNs/genética , MicroARNs/metabolismo , Humanos , Núcleo Celular/metabolismo , Núcleo Celular/genética , Animales , Hematopoyesis/genética

RESUMEN

While myelodysplastic syndromes with del(5q) (del(5q) MDS) comprises a well-defined hematological subgroup, the molecular basis underlying its origin remains unknown. Using single cell RNA-seq (scRNA-seq) on CD34+ progenitors from del(5q) MDS patients, we have identified cells harboring the deletion, characterizing the transcriptional impact of this genetic insult on disease pathogenesis and treatment response. Interestingly, both del(5q) and non-del(5q) cells present similar transcriptional lesions, indicating that all cells, and not only those harboring the deletion, may contribute to aberrant hematopoietic differentiation. However, gene regulatory network (GRN) analyses reveal a group of regulons showing aberrant activity that could trigger altered hematopoiesis exclusively in del(5q) cells, pointing to a more prominent role of these cells in disease phenotype. In del(5q) MDS patients achieving hematological response upon lenalidomide treatment, the drug reverts several transcriptional alterations in both del(5q) and non-del(5q) cells, but other lesions remain, which may be responsible for potential future relapses. Moreover, lack of hematological response is associated with the inability of lenalidomide to reverse transcriptional alterations. Collectively, this study reveals transcriptional alterations that could contribute to the pathogenesis and treatment response of del(5q) MDS.

Asunto(s)

Antígenos CD34 , Deleción Cromosómica , Cromosomas Humanos Par 5 , Células Madre Hematopoyéticas , Lenalidomida , Síndromes Mielodisplásicos , Análisis de la Célula Individual , Humanos , Lenalidomida/farmacología , Lenalidomida/uso terapéutico , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/tratamiento farmacológico , Síndromes Mielodisplásicos/patología , Síndromes Mielodisplásicos/metabolismo , Células Madre Hematopoyéticas/efectos de los fármacos , Células Madre Hematopoyéticas/metabolismo , Antígenos CD34/metabolismo , Cromosomas Humanos Par 5/genética , Masculino , Femenino , Anciano , Redes Reguladoras de Genes/efectos de los fármacos , Persona de Mediana Edad , Hematopoyesis/efectos de los fármacos , Hematopoyesis/genética , Transcriptoma , Anciano de 80 o más Años , RNA-Seq , Perfilación de la Expresión Génica

RESUMEN

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

Asunto(s)

Hematopoyesis Clonal , ADN (Citosina-5-)-Metiltransferasas , ADN Metiltransferasa 3A , Periodontitis , Animales , ADN (Citosina-5-)-Metiltransferasas/metabolismo , ADN (Citosina-5-)-Metiltransferasas/genética , Ratones , Hematopoyesis Clonal/genética , Humanos , Periodontitis/genética , Periodontitis/patología , Mutación , Masculino , Femenino , Inflamación/genética , Inflamación/patología , Osteoclastos/metabolismo , Ratones Endogámicos C57BL , Adulto , Interleucina-17/metabolismo , Interleucina-17/genética , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Hematopoyesis/genética , Osteogénesis/genética , Células Madre Hematopoyéticas/metabolismo , Resorción Ósea/genética , Resorción Ósea/patología , Persona de Mediana Edad

RESUMEN

Clonal hematopoiesis (CH) arises when hematopoietic stem cells (HSCs) acquire mutations, most frequently in the DNMT3A and TET2 genes, conferring a competitive advantage through mechanisms that remain unclear. To gain insight into how CH mutations enable gradual clonal expansion, we used single-cell multi-omics with high-fidelity genotyping on human CH bone marrow (BM) samples. Most of the selective advantage of mutant cells occurs within HSCs. DNMT3A- and TET2-mutant clones expand further in early progenitors, while TET2 mutations accelerate myeloid maturation in a dose-dependent manner. Unexpectedly, both mutant and non-mutant HSCs from CH samples are enriched for inflammatory and aging transcriptomic signatures, compared with HSCs from non-CH samples, revealing a non-cell-autonomous effect. However, DNMT3A- and TET2-mutant HSCs have an attenuated inflammatory response relative to wild-type HSCs within the same sample. Our data support a model whereby CH clones are gradually selected because they are resistant to the deleterious impact of inflammation and aging.

Asunto(s)

Envejecimiento , Hematopoyesis Clonal , ADN (Citosina-5-)-Metiltransferasas , ADN Metiltransferasa 3A , Dioxigenasas , Células Madre Hematopoyéticas , Inflamación , Mutación , Humanos , Inflamación/genética , Inflamación/patología , Envejecimiento/genética , Hematopoyesis Clonal/genética , Mutación/genética , Células Madre Hematopoyéticas/metabolismo , ADN (Citosina-5-)-Metiltransferasas/genética , ADN (Citosina-5-)-Metiltransferasas/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Hematopoyesis/genética

RESUMEN

Single-cell transcriptome sequencing (scRNA-seq) has revolutionized our understanding of cellular processes by enabling the analysis of expression profiles at an individual cell level. This technology has shown promise in uncovering new cell types, gene functions, cell differentiation, and trajectory inference through the study of various biological processes, such as hematopoiesis. Recent scRNA-seq analysis of mouse bone marrow cells has provided a network model of hematopoietic lineage. However, all data analyses have predicted undirected network maps for the associated cell trajectories. Moreover, the debate regarding the origin of basophil cells still persists. In this work, we apply the Volatility Constrained (VC) correlation method to predict not only the network structure but also the causality or directionality between the cell types present in the hematopoietic process. Our findings suggest a dual origin of basophils, from both granulocyte/macrophage and erythrocyte progenitors, the latter being a trajectory less explored in previous research. The proposed approach and predictions may assist in developing a complete hematopoietic process map, impacting our understanding of hematopoiesis and providing a robust directional network framework for further biomedical research.

Asunto(s)

Linaje de la Célula , Hematopoyesis , Análisis de la Célula Individual , Transcriptoma , Hematopoyesis/genética , Animales , Análisis de la Célula Individual/métodos , Ratones , Linaje de la Célula/genética , Transcriptoma/genética , Basófilos/citología , Basófilos/metabolismo , Diferenciación Celular/genética , Redes Reguladoras de Genes , Perfilación de la Expresión Génica/métodos

RESUMEN

The development of haematopoiesis involves the coordinated action of numerous genes, some of which are implicated in haematological malignancies. However, the biological function of many genes remains elusive and unknown functional genes are likely to remain to be uncovered. Here, we report a previously uncharacterised gene in haematopoiesis, identified by screening mutant embryonic stem cells. The gene, 'attenuated haematopoietic development (Ahed)', encodes a nuclear protein. Conditional knockout (cKO) of Ahed results in anaemia from embryonic day 14.5 onward, leading to prenatal demise. Transplantation experiments demonstrate the incapacity of Ahed-deficient haematopoietic cells to reconstitute haematopoiesis in vivo. Employing a tamoxifen-inducible cKO model, we further reveal that Ahed deletion impairs the intrinsic capacity of haematopoietic cells in adult mice. Ahed deletion affects various pathways, and published databases present cancer patients with somatic mutations in Ahed. Collectively, our findings underscore the fundamental roles of Ahed in lifelong haematopoiesis, implicating its association with malignancies.

Asunto(s)

Hematopoyesis , Ratones Noqueados , Animales , Hematopoyesis/genética , Ratones , Humanos , Femenino , Células Madre Hematopoyéticas/metabolismo , Células Madre Hematopoyéticas/citología , Ratones Endogámicos C57BL , Mutación , Anemia/genética , Masculino , Células Madre Embrionarias/metabolismo