201
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Gritz E, Hirschi KK. Specification and function of hemogenic endothelium during embryogenesis. Cell Mol Life Sci 2016; 73:1547-67. [PMID: 26849156 PMCID: PMC4805691 DOI: 10.1007/s00018-016-2134-0] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 12/16/2015] [Accepted: 01/07/2016] [Indexed: 01/15/2023]
Abstract
Hemogenic endothelium is a specialized subset of developing vascular endothelium that acquires hematopoietic potential and can give rise to multilineage hematopoietic stem and progenitor cells during a narrow developmental window in tissues such as the extraembryonic yolk sac and embryonic aorta-gonad-mesonephros. Herein, we review current knowledge about the historical and developmental origins of hemogenic endothelium, the molecular events that govern hemogenic specification of vascular endothelial cells, the generation of multilineage hematopoietic stem and progenitor cells from hemogenic endothelium, and the potential for translational applications of knowledge gained from further study of these processes.
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Affiliation(s)
- Emily Gritz
- Departments of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Yale Stem Cell Center, Yale University School of Medicine, 300 George St., New Haven, CT, 06511, USA
- Department of Pediatrics, Section of Neonatal-Perinatal Medicine, Yale University School of Medicine, 333 Cedar St., New Haven, CT, 06511, USA
| | - Karen K Hirschi
- Departments of Medicine, Genetics and Biomedical Engineering, Yale Cardiovascular Research Center, Vascular Biology and Therapeutics Program, and Yale Stem Cell Center, Yale University School of Medicine, 300 George St., New Haven, CT, 06511, USA.
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202
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Chin CJ, Cooper AR, Lill GR, Evseenko D, Zhu Y, He CB, Casero D, Pellegrini M, Kohn DB, Crooks GM. Genetic Tagging During Human Mesoderm Differentiation Reveals Tripotent Lateral Plate Mesodermal Progenitors. Stem Cells 2016; 34:1239-50. [PMID: 26934332 DOI: 10.1002/stem.2351] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/08/2016] [Indexed: 02/02/2023]
Abstract
Although clonal studies of lineage potential have been extensively applied to organ specific stem and progenitor cells, much less is known about the clonal origins of lineages formed from the germ layers in early embryogenesis. We applied lentiviral tagging followed by vector integration site analysis (VISA) with high-throughput sequencing to investigate the ontogeny of the hematopoietic, endothelial and mesenchymal lineages as they emerge from human embryonic mesoderm. In contrast to studies that have used VISA to track differentiation of self-renewing stem cell clones that amplify significantly over time, we focused on a population of progenitor clones with limited self-renewal capability. Our analyses uncovered the critical influence of sampling on the interpretation of lentiviral tag sharing, particularly among complex populations with minimal clonal duplication. By applying a quantitative framework to estimate the degree of undersampling we revealed the existence of tripotent mesodermal progenitors derived from pluripotent stem cells, and the subsequent bifurcation of their differentiation into bipotent endothelial/hematopoietic or endothelial/mesenchymal progenitors. Stem Cells 2016;34:1239-1250.
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Affiliation(s)
- Chee Jia Chin
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine (DGSOM)
| | - Aaron R Cooper
- Molecular Biology Interdepartmental PhD Program, DGSOM University of California Los Angeles.,Department of Microbiology, Immunology and Molecular Genetics, DGSOM, DGSOM University of California Los Angeles
| | - Georgia R Lill
- Department of Microbiology, Immunology and Molecular Genetics, DGSOM, DGSOM University of California Los Angeles
| | - Denis Evseenko
- Department of Orthopedic Surgery, Keck School of Medicine of University of Southern California (USC). All in, Los Angeles, CA, United States
| | - Yuhua Zhu
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine (DGSOM)
| | - Chong Bin He
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine (DGSOM)
| | - David Casero
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine (DGSOM)
| | - Matteo Pellegrini
- Department of Molecular, Cell and Development Biology, DGSOM University of California Los Angeles.,Molecular Biology Institute (MBI)
| | - Donald B Kohn
- Department of Microbiology, Immunology and Molecular Genetics, DGSOM, DGSOM University of California Los Angeles.,Molecular Biology Institute (MBI).,Department of Pediatrics, DGSOM University of California Los Angeles.,Broad Stem Cell Research Center (BSCRC), DGSOM University of California Los Angeles.,Jonsson Comprehensive Cancer Center (JCCC), DGSOM University of California Los Angeles
| | - Gay M Crooks
- Department of Pathology & Laboratory Medicine, David Geffen School of Medicine (DGSOM).,Department of Pediatrics, DGSOM University of California Los Angeles.,Broad Stem Cell Research Center (BSCRC), DGSOM University of California Los Angeles.,Department of Pathology & Laboratory Medicine, DGSOM University of California Los Angeles
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203
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Yvernogeau L, Gautier R, Khoury H, Menegatti S, Schmidt M, Gilles JF, Jaffredo T. An in vitro model of hemogenic endothelium commitment and hematopoietic production. Development 2016; 143:1302-12. [PMID: 26952980 DOI: 10.1242/dev.126714] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 02/21/2016] [Indexed: 01/03/2023]
Abstract
Adult-type hematopoietic stem and progenitor cells are formed during ontogeny from a specialized subset of endothelium, termed the hemogenic endothelium, via an endothelial-to-hematopoietic transition (EHT) that occurs in the embryonic aorta and the associated arteries. Despite efforts to generate models, little is known about the mechanisms that drive endothelial cells to the hemogenic fate and about the subsequent molecular control of the EHT. Here, we have designed a stromal line-free controlled culture system utilizing the embryonic pre-somitic mesoderm to obtain large numbers of endothelial cells that subsequently commit into hemogenic endothelium before undergoing EHT. Monitoring the culture for up to 12 days using key molecular markers reveals stepwise commitment into the blood-forming system that is reminiscent of the cellular and molecular changes occurring during hematopoietic development at the level of the aorta. Long-term single-cell imaging allows tracking of the EHT of newly formed blood cells from the layer of hemogenic endothelial cells. By modifying the culture conditions, it is also possible to modulate the endothelial cell commitment or the EHT or to produce smooth muscle cells at the expense of endothelial cells, demonstrating the versatility of the cell culture system. This method will improve our understanding of the precise cellular changes associated with hemogenic endothelium commitment and EHT and, by unfolding these earliest steps of the hematopoietic program, will pave the way for future ex vivo production of blood cells.
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Affiliation(s)
- Laurent Yvernogeau
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
| | - Rodolphe Gautier
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
| | - Hanane Khoury
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
| | - Sara Menegatti
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
| | - Melanie Schmidt
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
| | - Jean-Francois Gilles
- Institute of Biology Paris-Seine, Sorbonne Universités, UPMC Univ Paris 06, Cellular Imaging Facility, Paris 75005, France
| | - Thierry Jaffredo
- Sorbonne Universités, UPMC Univ Paris 06, IBPS, UMR 7622, Laboratoire de Biologie du Développement, Paris 75005, France CNRS, UMR 7622, Inserm U 1156, IBPS, Laboratoire de Biologie du Développement, Paris 75005, France
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204
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Orlova VV, Chuva de Sousa Lopes S, Valdimarsdottir G. BMP-SMAD signaling: From pluripotent stem cells to cardiovascular commitment. Cytokine Growth Factor Rev 2016; 27:55-63. [DOI: 10.1016/j.cytogfr.2015.11.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 11/13/2015] [Indexed: 02/07/2023]
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205
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Functional and molecular characterization of mouse Gata2-independent hematopoietic progenitors. Blood 2016; 127:1426-37. [PMID: 26834239 DOI: 10.1182/blood-2015-10-673749] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 01/20/2016] [Indexed: 01/15/2023] Open
Abstract
The Gata2 transcription factor is a pivotal regulator of hematopoietic cell development and maintenance, highlighted by the fact that Gata2 haploinsufficiency has been identified as the cause of some familial cases of acute myelogenous leukemia/myelodysplastic syndrome and in MonoMac syndrome. Genetic deletion in mice has shown that Gata2 is pivotal to the embryonic generation of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). It functions in the embryo during endothelial cell to hematopoietic cell transition to affect hematopoietic cluster, HPC, and HSC formation. Gata2 conditional deletion and overexpression studies show the importance of Gata2 levels in hematopoiesis, during all developmental stages. Although previous studies of cell populations phenotypically enriched in HPCs and HSCs show expression of Gata2, there has been no direct study of Gata2 expressing cells during normal hematopoiesis. In this study, we generate a Gata2Venus reporter mouse model with unperturbed Gata2 expression to examine the hematopoietic function and transcriptome of Gata2 expressing and nonexpressing cells. We show that all the HSCs are Gata2 expressing. However, not all HPCs in the aorta, vitelline and umbilical arteries, and fetal liver require or express Gata2. These Gata2-independent HPCs exhibit a different functional output and genetic program, including Ras and cyclic AMP response element-binding protein pathways and other Gata factors, compared with Gata2-dependent HPCs. Our results, indicating that Gata2 is of major importance in programming toward HSC fate but not in all cells with HPC fate, have implications for current reprogramming strategies.
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206
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Nakano A, Nakano H, Smith KA, Palpant NJ. The developmental origins and lineage contributions of endocardial endothelium. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1937-47. [PMID: 26828773 DOI: 10.1016/j.bbamcr.2016.01.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 12/21/2015] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
Abstract
Endocardial development involves a complex orchestration of cell fate decisions that coordinate with endoderm formation and other mesodermal cell lineages. Historically, investigations into the contribution of endocardium in the developing embryo was constrained to the heart where these cells give rise to the inner lining of the myocardium and are a major contributor to valve formation. In recent years, studies have continued to elucidate the complexities of endocardial fate commitment revealing a much broader scope of lineage potential from developing endocardium. These studies cover a wide range of species and model systems and show direct contribution or fate potential of endocardium giving rise to cardiac vasculature, blood, fibroblast, and cardiomyocyte lineages. This review focuses on the marked expansion of knowledge in the area of endocardial fate potential. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.
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Affiliation(s)
- Atsushi Nakano
- Department of Molecular Cell and Developmental Biology, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA, USA
| | - Haruko Nakano
- Department of Molecular Cell and Developmental Biology, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA, USA
| | - Kelly A Smith
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, Australia
| | - Nathan J Palpant
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD, Australia.
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207
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Understanding platelet generation from megakaryocytes: implications for in vitro-derived platelets. Blood 2016; 127:1227-33. [PMID: 26787738 DOI: 10.1182/blood-2015-08-607929] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 09/30/2015] [Indexed: 12/12/2022] Open
Abstract
Platelets are anucleate cytoplasmic discs derived from megakaryocytes that circulate in the blood and have major roles in hemostasis, thrombosis, inflammation, and vascular biology. Platelet transfusions are required to prevent the potentially life-threatening complications of severe thrombocytopenia seen in a variety of medical settings including cancer therapy, trauma, and sepsis. Platelets used in the clinic are currently donor-derived which is associated with concerns over sufficient availability, quality, and complications due to immunologic and/or infectious issues. To overcome our dependence on donor-derived platelets for transfusion, efforts have been made to generate in vitro-based platelets. Work in this area has advanced our understanding of the complex processes that megakaryocytes must undergo to generate platelets both in vivo and in vitro. This knowledge has also defined the challenges that must be overcome to bring in vitro-based platelet manufacturing to a clinical reality. This review will focus on our understanding of committed megakaryocytes and platelet release in vivo and in vitro, and how this knowledge can guide the development of in vitro-derived platelets for clinical application.
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208
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Daniel MG, Lemischka IR, Moore K. Converting cell fates: generating hematopoietic stem cells de novo via transcription factor reprogramming. Ann N Y Acad Sci 2016; 1370:24-35. [PMID: 26748878 DOI: 10.1111/nyas.12989] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Even though all paradigms of stem cell therapy and regenerative medicine emerged from the study of hematopoietic stem cells (HSCs), the inability to generate these cells de novo or expand them in vitro persists. Initial efforts to obtain these cells began with the use of embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) technologies, but these strategies have yet to yield fully functional cells. Subsequently, more recent approaches involve transcription factor (TF) overexpression to reprogram PSCs and various somatic cells. The induction of pluripotency with just four TFs by Yamanaka informs our ability to convert cell fates and demonstrates the feasibility of utilizing terminally differentiated cells to generate cells with multilineage potential. In this review, we discuss the recent efforts undertaken using TF-based reprogramming strategies to convert several cell types into HSCs.
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Affiliation(s)
- Michael G Daniel
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, New York.,Black Family Stem Cell Institute, Icahn School of Medicine, New York, New York.,The Graduate School of Biomedical Science, Icahn School of Medicine, New York, New York
| | - Ihor R Lemischka
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, New York.,Black Family Stem Cell Institute, Icahn School of Medicine, New York, New York.,Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine, New York, New York
| | - Kateri Moore
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, New York.,Black Family Stem Cell Institute, Icahn School of Medicine, New York, New York
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209
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Long Y, Huang H. On signaling pathways: hematopoietic stem cell specification from hemogenic endothelium. SCIENCE CHINA-LIFE SCIENCES 2015; 58:1256-61. [DOI: 10.1007/s11427-015-4976-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/16/2015] [Indexed: 10/22/2022]
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210
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Daniel MG, Pereira CF, Lemischka IR, Moore KA. Making a Hematopoietic Stem Cell. Trends Cell Biol 2015; 26:202-214. [PMID: 26526106 DOI: 10.1016/j.tcb.2015.10.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 12/22/2022]
Abstract
Previous attempts to either generate or expand hematopoietic stem cells (HSCs) in vitro have involved either ex vivo expansion of pre-existing patient or donor HSCs or de novo generation from pluripotent stem cells (PSCs), comprising both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). iPSCs alleviated ESC ethical issues but attempts to generate functional mature hematopoietic stem and progenitor cells (HSPCs) have been largely unsuccessful. New efforts focus on directly reprogramming somatic cells into definitive HSCs and HSPCs. To meet clinical needs and to advance drug discovery and stem cell therapy, alternative approaches are necessary. In this review, we synthesize the strategies used and the key findings made in recent years by those trying to make an HSC.
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Affiliation(s)
- Michael G Daniel
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA; The Graduate School of Biomedical Science, Icahn School of Medicine, New York, NY, USA
| | - Carlos-Filipe Pereira
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, UC Biotech Building, Biocant Park, 3060-197 Cantanhede, Portugal
| | - Ihor R Lemischka
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA; Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine, New York, NY, USA
| | - Kateri A Moore
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA.
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211
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Bai H, Liu Y, Xie Y, Hoyle DL, Brodsky RA, Cheng L, Cheng T, Wang ZZ. Definitive Hematopoietic Multipotent Progenitor Cells Are Transiently Generated From Hemogenic Endothelial Cells in Human Pluripotent Stem Cells. J Cell Physiol 2015; 231:1065-76. [PMID: 26395760 DOI: 10.1002/jcp.25199] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/21/2015] [Indexed: 12/21/2022]
Abstract
Generation of fully functional hematopoietic multipotent progenitor (MPP) cells from human pluripotent stem cells (hPSCs) has a great therapeutic potential to provide an unlimited cell source for treatment of hematological disorders. We previously demonstrated that CD34(+) CD31(+) CD144(+) population derived from hPSCs contain hemato-endothelial progenitors (HEPs) that give rise to hematopoietic and endothelial cells. Here, we report a differentiation system to generate definitive hematopoietic MPP cells from HEPs via endothelial monolayer. In the presence of angiogenic factors, HEPs formed an endothelial monolayer, from which hematopoietic clusters emerged through the process of endothelial-to-hematopoietic transition (EHT). EHT was significantly enhanced by hematopoietic growth factors. The definitive MPP cells generated from endothelial monolayer were capable of forming multilineage hematopoietic colonies, giving rise to T lymphoid cells, and differentiating into enucleated erythrocytes. Emergence of hematopoietic cells from endothelial monolayer occurred transiently. Hematopoietic potential was lost during prolonged culture of HEPs in endothelial growth conditions. Our study demonstrated that CD34(+) CD31(+) CD144(+) HEPs gave rise to hematopoietic MPP cells via hemogenic endothelial cells that exist transiently. The established differentiation system provides a platform for future investigation of regulatory factors involved in de novo generation of hematopoietic MPP cells and their applications in transplantation.
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Affiliation(s)
- Hao Bai
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Yanfeng Liu
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Yinliang Xie
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Disease Hospital, Chinese Academy of Medical Sciences, Tianjin, China
| | - Dixie L Hoyle
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Robert A Brodsky
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Linzhao Cheng
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Tao Cheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Disease Hospital, Chinese Academy of Medical Sciences, Tianjin, China
| | - Zack Z Wang
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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212
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G protein-coupled receptor 183 facilitates endothelial-to-hematopoietic transition via Notch1 inhibition. Cell Res 2015; 25:1093-107. [PMID: 26358189 PMCID: PMC4650626 DOI: 10.1038/cr.2015.109] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 07/28/2015] [Accepted: 07/31/2015] [Indexed: 12/15/2022] Open
Abstract
In vertebrates, embryonic hematopoietic stem and progenitor cells (HSPCs) are derived from a subset of endothelial cells, the hemogenic endothelium (HE), through the endothelial-to-hematopoietic transition (EHT). Notch signaling is essential for HSPC development during embryogenesis across vertebrates. However, whether and how it regulates EHT remains unclear. Here, we show that G protein-coupled receptor 183 (Gpr183) signaling serves as an indispensable switch for HSPC emergence by repressing Notch signaling before the onset of EHT. Inhibition of Gpr183 significantly upregulates Notch signaling and abolishes HSPC emergence. Upon activation by its ligand 7α-25-OHC, Gpr183 recruits β-arrestin1 and the E3 ligase Nedd4 to degrade Notch1 in specified HE cells and then facilitates the subsequent EHT. Importantly, 7α-25-OHC stimulation promotes HSPC emergence in vivo and in vitro, providing an attractive strategy for enhancing the in vitro generation of functional HSPCs.
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213
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Repression of arterial genes in hemogenic endothelium is sufficient for haematopoietic fate acquisition. Nat Commun 2015. [PMID: 26204127 PMCID: PMC4519987 DOI: 10.1038/ncomms8739] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Changes in cell fate and identity are essential for endothelial-to-haematopoietic transition (EHT), an embryonic process that generates the first adult populations of haematopoietic stem cells (HSCs) from hemogenic endothelial cells. Dissecting EHT regulation is a critical step towards the production of in vitro derived HSCs. Yet, we do not know how distinct endothelial and haematopoietic fates are parsed during the transition. Here we show that genes required for arterial identity function later to repress haematopoietic fate. Tissue-specific, temporally controlled, genetic loss of arterial genes (Sox17 and Notch1) during EHT results in increased production of haematopoietic cells due to loss of Sox17-mediated repression of haematopoietic transcription factors (Runx1 and Gata2). However, the increase in EHT can be abrogated by increased Notch signalling. These findings demonstrate that the endothelial haematopoietic fate switch is actively repressed in a population of endothelial cells, and that derepression of these programs augments haematopoietic output. The first haematopoietic stem and progenitor cells arise from the hemogenic endothelium of arterial vascular beds. Here the authors describe the mechanism that regulates the endothelial-to-haematopoietic transition and show that Sox17 and Notch1, genes critical to arterial endothelium identity, are also crucial repressors of haematopoietic fate.
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