RESUMO
For a long time, self-renewing and multipotent hematopoietic stem cells (HSCs) have been thought to make a major contribution to both embryonic and adult hematopoiesis. The canonical hematopoietic hierarchy illustrating HSC self-renewal and multipotency has been established mainly based on invasive functional assays (e.g. transplantation or colony-forming units in the spleen and in culture), which evaluate the cellular potentials of HSCs. With the extensive applications of non-invasive cell fate-mapping strategies, recent lineage tracing-based studies have suggested that not all native hematopoiesis is established via the hierarchical differentiation of HSCs. By contrast, hematopoietic progenitor cells (HPCs) are a dominant contributor to both embryonic and young adult hematopoiesis. These new findings help redefine the cellular origins of embryonic and adult hematopoiesis under native conditions, and emphasize the differences in revealing HSC potential versus HSC fate using distinct approaches during stress and native hematopoiesis. Here, we review recent advances in HPC and HSC development, and provide an updated perspective to incorporate these new findings with our traditional understanding of developmental and adult hematopoiesis.
Assuntos
Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas , Diferenciação Celular , Hematopoese , Linhagem da CélulaRESUMO
Limited knowledge of cellular and molecular mechanisms underlying hematopoietic stem cell and multipotent progenitor (HSC/MPP) expansion within their native niche has impeded the application of stem cell-based therapies for hematological malignancies. Here, we constructed a spatiotemporal transcriptome map of mouse fetal liver (FL) as a platform for hypothesis generation and subsequent experimental validation of novel regulatory mechanisms. Single-cell transcriptomics revealed three transcriptionally heterogeneous HSC/MPP subsets, among which a CD93-enriched subset exhibited enhanced stem cell properties. Moreover, by employing integrative analysis of single-cell and spatial transcriptomics, we identified novel HSC/MPP 'pocket-like' units (HSC PLUS), composed of niche cells (hepatoblasts, stromal cells, endothelial cells, and macrophages) and enriched with growth factors. Unexpectedly, macrophages showed an 11-fold enrichment in the HSC PLUS. Functionally, macrophage-HSC/MPP co-culture assay and candidate molecule testing, respectively, validated the supportive role of macrophages and growth factors (MDK, PTN, and IGFBP5) in HSC/MPP expansion. Finally, cross-species analysis and functional validation showed conserved cell-cell interactions and expansion mechanisms but divergent transcriptome signatures between mouse and human FL HSCs/MPPs. Taken together, these results provide an essential resource for understanding HSC/MPP development in FL, and novel insight into functional HSC/MPP expansion ex vivo.
Assuntos
Células Endoteliais , Transcriptoma , Animais , Hematopoese/genética , Células-Tronco Hematopoéticas , Fígado , CamundongosRESUMO
Macrophages play pivotal roles in immunity, hematopoiesis, and tissue homeostasis. In mammals, macrophages have been shown to originate from yolk-sac-derived erythro-myeloid progenitors and aorta-gonad-mesonephros (AGM)-derived hematopoietic stem cells. However, whether macrophages can arise from other embryonic sites remains unclear. Here, using single-cell RNA sequencing, we profile the transcriptional landscape of mouse fetal placental hematopoiesis. We uncover and experimentally validate that a CD44+ subpopulation of placental endothelial cells (ECs) exhibits hemogenic potential. Importantly, lineage tracing using the newly generated Hoxa13 reporter line shows that Hoxa13-labeled ECs can produce placental macrophages, named Hofbauer cell (HBC)-like cells. Furthermore, we identify two subtypes of HBC-like cells, and cell-cell interaction analysis identifies their potential roles in angiogenesis and antigen presentation, separately. Our study provides a comprehensive understanding of placental hematopoiesis and highlights the placenta as a source of macrophages, which has important implications for both basic and translational research.
Assuntos
Linhagem da Célula , Hemangioblastos/citologia , Hematopoese , Células-Tronco Hematopoéticas/citologia , Macrófagos/citologia , Placenta/citologia , Animais , Feminino , Hemangioblastos/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Placenta/metabolismo , Gravidez , Análise de Célula Única , TranscriptomaRESUMO
During vertebrate embryogenesis, fetal hematopoietic stem and progenitor cells (HSPCs) exhibit expansion and differentiation properties in a supportive hematopoietic niche. To profile the developmental landscape of fetal HSPCs and their local niche, here, using single-cell RNA-sequencing, we deciphered a dynamic atlas covering 28,777 cells and 9 major cell types (23 clusters) of zebrafish caudal hematopoietic tissue (CHT). We characterized four heterogeneous HSPCs with distinct lineage priming and metabolic gene signatures. Furthermore, we investigated the regulatory mechanism of CHT niche components for HSPC development, with a focus on the transcription factors and ligand-receptor networks involved in HSPC expansion. Importantly, we identified an endothelial cell-specific G protein-coupled receptor 182, followed by in vivo and in vitro functional validation of its evolutionally conserved role in supporting HSPC expansion in zebrafish and mice. Finally, comparison between zebrafish CHT and human fetal liver highlighted the conservation and divergence across evolution. These findings enhance our understanding of the regulatory mechanism underlying hematopoietic niche for HSPC expansion in vivo and provide insights into improving protocols for HSPC expansion in vitro.
Assuntos
Hematopoese , Células-Tronco Hematopoéticas/fisiologia , Nicho de Células-Tronco , Animais , Linhagem da Célula , Feto/metabolismo , Perfilação da Expressão Gênica , Humanos , Fígado/metabolismo , Camundongos , Análise de Célula Única , Peixe-ZebraRESUMO
Cell transplantation into immunodeficient recipients is a widely used approach to study stem cell and cancer biology; however, studying cell states post transplantation in vivo is inconvenient in mammals. Here, we generated a foxn1/Casper mutant zebrafish that is transparent and exhibits T cell deficiency. By employing the line for hematopoietic stem cell (HSC) transplantation (HSCT), we could achieve nonconditioned transplantation. Meanwhile, we found that fetal HSCs from 3 days post fertilization zebrafish embryos produce a better transplant outcome in foxn1/Casper mutants, compared with adult HSCs. In addition to HSCT, the foxn1/Casper mutant is feasible for allografts of myelodysplastic syndrome-like and muscle cells, as well as xenografts of medaka muscle cells. In summary, foxn1/Casper mutants permit the nonconditioned engraftment of multiple cell types and visualized characterization of transplanted cells in vivo.
Assuntos
Aloenxertos/transplante , Fatores de Transcrição Forkhead/genética , Xenoenxertos/transplante , Mutação/genética , Neoplasias/patologia , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/genética , Animais , Sequência de Bases , Células-Tronco Fetais/citologia , Fatores de Transcrição Forkhead/metabolismo , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Resultado do Tratamento , Peixe-Zebra/embriologia , Proteínas de Peixe-Zebra/metabolismoRESUMO
In vertebrates, hematopoiesis occurring in different niches is orchestrated by intrinsic and extrinsic regulators. Previous studies have revealed numerous linear and planar regulatory mechanisms. However, a multi-dimensional transcriptomic atlas of any given hematopoietic organ has not yet been established. Here, we use multiple RNA sequencing (RNA-seq) approaches, including cell type-specific, temporal bulk RNA-seq, in vivo GEO-seq, and single-cell RNA-seq (scRNA-seq), to characterize the detailed spatiotemporal transcriptome during hematopoietic stem and progenitor cell (HSPC) expansion in the caudal hematopoietic tissue (CHT) of zebrafish. Combinatorial expression profiling reveals that, in the CHT niche, HSPCs and their neighboring supporting cells are co-regulated by shared signaling pathways and intrinsic factors, such as integrin signaling and Smchd1. Moreover, scRNA-seq analysis unveils the strong association between cell cycle status and HSPC differentiation. Taken together, we report a global transcriptome landscape that provides valuable insights and a rich resource to understand HSPC expansion in an intact vertebrate hematopoietic organ.
Assuntos
Hematopoese , Células-Tronco Hematopoéticas/citologia , Transcriptoma , Animais , Células-Tronco Hematopoéticas/classificação , Células-Tronco Hematopoéticas/metabolismo , RNA-Seq , Transdução de Sinais , Análise de Célula Única , Nicho de Células-Tronco , Peixe-ZebraRESUMO
The stem/progenitor cell has long been regarded as a central cell type in development, homeostasis, and regeneration, largely owing to its robust self-renewal and multilineage differentiation abilities. The balance between self-renewal and stem/progenitor cell differentiation requires the coordinated regulation of cell cycle progression and cell fate determination. Extensive studies have demonstrated that cell cycle states determine cell fates, because cells in different cell cycle states are characterized by distinct molecular features and functional outputs. Recent advances in high-resolution epigenome profiling, single-cell transcriptomics, and cell cycle reporter systems have provided novel insights into the cell cycle regulation of cell fate determination. Here, we review recent advances in cell cycle-dependent cell fate determination and functional heterogeneity, and the application of cell cycle manipulation for cell fate conversion. These findings will provide insight into our understanding of cell cycle regulation of cell fate determination in this field, and may facilitate its potential application in translational medicine.
Assuntos
Ciclo Celular , Fenômenos Fisiológicos Celulares , Animais , Epigenômica , Fase G1 , Fase G2 , Humanos , Pesquisa Translacional BiomédicaRESUMO
Fetal liver (FL) is an intricate and highly vascularized hematopoietic organ, which can support the extensive expansion of hematopoietic stem cells (HSCs) without loss of stemness, as well as of the downstream lineages of HSCs. This powerful function of FL largely benefits from the niche (or microenvironment), which provides a residence for HSC expansion. Numerous studies have demonstrated that the FL niche consists of heterogeneous cell populations that associate with HSCs spatially and regulate HSCs functionally. At the molecular level, a complex of cell extrinsic and intrinsic signaling network within the FL niche cells maintains HSC expansion. Here, we summarize recent studies on the analysis of the FL HSCs and their niche, and specifically on the molecular regulatory network for HSC expansion. Based on these studies, we hypothesize a strategy to obtain a large number of functional HSCs via 3D reconstruction of FL organoid ex vivo for clinical treatment in the future.
Assuntos
Proliferação de Células , Células-Tronco Fetais/citologia , Células-Tronco Hematopoéticas/citologia , Fígado/citologia , Animais , Células-Tronco Fetais/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Redes Reguladoras de Genes , Células-Tronco Hematopoéticas/metabolismo , Humanos , Fígado/irrigação sanguínea , Fígado/embriologia , Nicho de Células-Tronco/genéticaAssuntos
Adenosina/análogos & derivados , Aorta/embriologia , Células Endoteliais/fisiologia , Hematopoese/fisiologia , Receptores Notch/metabolismo , Células-Tronco/fisiologia , Adenosina/fisiologia , Animais , Feminino , Metiltransferases/metabolismo , Camundongos , Camundongos Knockout , Gravidez , Proteínas de Ligação a RNA/metabolismoRESUMO
During development, hematopoietic stem cells (HSCs) undergo a rapid expansion in the fetal liver (FL) after their emergence in the aorta-gonad-mesonephros (AGM) region. We recently reported that the endolysosomal trafficking factor BLOS2, encoded by the Bloc1s2 gene, regulates HSC/hematopoietic progenitor cell emergence in the AGM region; however, whether it plays a role in the FL remains unknown. Here, we show that BLOS2 plays an essential role in the regulation of HSC proliferation and differentiation in the FL. Bloc1s2 depletion leads to elevated Notch signaling, with an increased frequency but weakened self-renewal ability of FL HSCs. Functional assays show that Bloc1s2-/- FL HSCs harbor impaired lymphoid and myeloid differentiation abilities. These findings reveal that balanced control of Notch signaling by BLOS2 is required for HSC homeostasis during FL hematopoiesis.
Assuntos
Diferenciação Celular/fisiologia , Proliferação de Células/fisiologia , Feto/embriologia , Células-Tronco Hematopoéticas/metabolismo , Fígado/embriologia , Proteínas/metabolismo , Receptores Notch/metabolismo , Animais , Feto/citologia , Hematopoese Extramedular/fisiologia , Células-Tronco Hematopoéticas/citologia , Humanos , Fígado/citologia , Camundongos , Camundongos Knockout , Proteínas/genética , Receptores Notch/genéticaRESUMO
Epicuticular wax in plants limits non-stomatal water loss, inhibits postgenital organ fusion, protects plants against damage from UV radiation and imposes a physical barrier against pathogen infection. Here, we give a detailed description of the genetic, physiological and morphological consequences of a mutation in the rice gene WSL2, based on a comparison between the wild-type and an EMS mutant. The mutant's leaf cuticle membrane is thicker and less organized than that of the wild type, and its total wax content is diminished by ~80%. The mutant is also more sensitive to drought stress. WSL2 was isolated by positional cloning, and was shown to encode a homologue of the Arabidopsis thaliana genes CER3/WAX2/YRE/FLP1 and the maize gene GL1. It is expressed throughout the plant, except in the root. A transient assay carried out in both A. thaliana and rice protoplasts showed that the gene product is deposited in the endoplasmic reticulum. An analysis of the overall composition of the wax revealed that the mutant produces a substantially reduced quantity of C22-C32 fatty acids, which suggests that the function of WSL2 is associated with the elongation of very long-chain fatty acids.
Assuntos
Ácidos Graxos/biossíntese , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Ceras/metabolismo , Arabidopsis/genética , Genes de Plantas , Variação Genética , Genótipo , Mutação , Oryza/genética , Fenótipo , Epiderme Vegetal/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Zea mays/genéticaRESUMO
In rice, one detrimental factor influencing single panicle yield is the frequent occurrence of panicle apical abortion (PAA) under unfavorable climatic conditions. Until now, no detailed genetic information has been available to avoid PAA in rice breeding. Here, we show that the occurrence of PAA is associated with the accumulation of excess hydrogen peroxide. Quantitative trait loci (QTLs) mapping for PAA in an F(2) population derived from the cross of L-05261 (PAA line) × IRAT129 (non-PAA variety) identified seven QTLs over a logarithm of the odd (LOD) threshold of 2.5, explaining approximately 50.1% of phenotypic variance for PAA in total. Five of the QTLs with an increased effect from L-05261, were designated as qPAA3-1, qPAA3-2, qPAA4, qPAA5 and qPAA8, and accounted for 6.8%, 5.9%, 4.2%, 13.0% and 12.2% of phenotypic variance, respectively. We found that the PAA in the early heading plants was mainly controlled by qPAA8. Subsequently, using the sub-populations specific for qPAA8 based on marker-assisted selection, we further narrowed qPAA8 to a 37.6-kb interval delimited by markers RM22475 and 8-In112. These results are beneficial for PAA gene clone.