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Yu T, Chen J, Wang Y, Xu J. The embryonic zebrafish brain is exclusively colonized by pu.1-dependent and lymphatic-independent population of microglia. SCIENCE ADVANCES 2024; 10:eado0519. [PMID: 39196933 PMCID: PMC11352844 DOI: 10.1126/sciadv.ado0519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 07/24/2024] [Indexed: 08/30/2024]
Abstract
Microglia, the crucial immune cells inhabiting the central nervous system (CNS), perform a range of vital functions, encompassing immune defense and neuronal regulation. Microglia subsets with diverse functions and distinct developmental regulations have been identified recently. It is generally accepted that all microglia originate from hematopoiesis and depend on the myeloid transcription factor PU.1. However, a recent study reported the existence of mrc1+ microglia in zebrafish embryos, which are seemingly independent of Pu.1 and reliant on lymphatic vessels, sparking great interest in the possibility of lymphatic-originated microglia. To address this, we took advantage of a pu.1 knock-in zebrafish allele for a detailed investigation. Our results conclusively showed that almost all zebrafish embryonic microglia (~95% on average) express pu.1. Further, lineage tracing and mutant analysis revealed that these microglia neither emerged from nor depended on lymphatic vessels. In essence, our study refutes the presence of pu.1-independent but lymphatic-dependent microglia.
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Affiliation(s)
- Tao Yu
- Shenzhen Key Laboratory for Neuronal Structural Biology, Biomedical Research Institute, Shenzhen Peking University–The Hong Kong University of Science and Technology Medical Center, Shenzhen 518036, China
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Jiahao Chen
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Yuexin Wang
- Greater Bay Biomedical Innocenter, Shenzhen Bay Laboratory, Shenzhen 518055, China
| | - Jin Xu
- Innovation Centre of Ministry of Education for Development and Diseases, School of Medicine, South China University of Technology, Guangzhou, China
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Iyer H, Talbot WS. The Cl- transporter ClC-7 is essential for phagocytic clearance by microglia. J Cell Sci 2024; 137:jcs261616. [PMID: 38294065 PMCID: PMC10911276 DOI: 10.1242/jcs.261616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/15/2024] [Indexed: 02/01/2024] Open
Abstract
Microglia, professional phagocytic cells of the brain, rely upon the appropriate activation of lysosomes to execute their immune and clearance functions. Lysosomal activity is, in turn, modulated by a complex network of over 200 membrane and accessory proteins that relay extracellular cues to these key degradation centers. The ClC-7 chloride (Cl-)-proton (H+) antiporter (also known as CLCN7) is localized to the endolysosomal compartments and mutations in CLCN7 lead to osteopetrosis and neurodegeneration. Although the functions of ClC-7 have been extensively investigated in osteoclasts and neurons, its role in microglia in vivo remains largely unexamined. Here, we show that microglia and embryonic macrophages in zebrafish clcn7 mutants cannot effectively process extracellular debris in the form of apoptotic cells and β-amyloid. Despite these functional defects, microglia develop normally in clcn7 mutants and display normal expression of endosomal and lysosomal markers. We also find that mutants for ostm1, which encodes the β-subunit of ClC-7, have a phenotype that is strikingly similar to that of clcn7 mutants. Together, our observations uncover a previously unappreciated role of ClC-7 in microglia and contribute to the understanding of the neurodegenerative phenotypes that accompany mutations in this channel.
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Affiliation(s)
- Harini Iyer
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - William S. Talbot
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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3
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Mylvaganam S, Freeman SA. The resolution of phagosomes. Immunol Rev 2023; 319:45-64. [PMID: 37551912 DOI: 10.1111/imr.13260] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 07/18/2023] [Indexed: 08/09/2023]
Abstract
Phagocytosis is a fundamental immunobiological process responsible for the removal of harmful particulates. While the number of phagocytic events achieved by a single phagocyte can be remarkable, exceeding hundreds per day, the same phagocytic cells are relatively long-lived. It should therefore be obvious that phagocytic meals must be resolved in order to maintain the responsiveness of the phagocyte and to avoid storage defects. In this article, we discuss the mechanisms involved in the resolution process, including solute transport pathways and membrane traffic. We describe how products liberated in phagolysosomes support phagocyte metabolism and the immune response. We also speculate on mechanisms involved in the redistribution of phagosomal metabolites back to circulation. Finally, we highlight the pathologies owed to impaired phagosome resolution, which range from storage disorders to neurodegenerative diseases.
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Affiliation(s)
- Sivakami Mylvaganam
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Spencer A Freeman
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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5
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Iyer H, Shen K, Meireles AM, Talbot WS. A lysosomal regulatory circuit essential for the development and function of microglia. SCIENCE ADVANCES 2022; 8:eabp8321. [PMID: 36044568 PMCID: PMC9432849 DOI: 10.1126/sciadv.abp8321] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/18/2022] [Indexed: 05/17/2023]
Abstract
As the primary phagocytic cells of the central nervous system, microglia exquisitely regulate their lysosomal activity to facilitate brain development and homeostasis. However, mechanisms that coordinate lysosomal activity with microglia development, chemotaxis, and function remain unclear. Here, we show that embryonic macrophages require the lysosomal guanosine triphosphatase (GTPase) RagA and the GTPase-activating protein Folliculin to colonize the brain in zebrafish. We demonstrate that embryonic macrophages in rraga mutants show increased expression of lysosomal genes but display significant down-regulation of immune- and chemotaxis-related genes. Furthermore, we find that RagA and Folliculin repress the key lysosomal transcription factor Tfeb and its homologs Tfe3a and Tfe3b in the macrophage lineage. Using RNA sequencing, we establish that Tfeb and Tfe3 are required for activation of lysosomal target genes under conditions of stress but not for basal expression of lysosomal pathways. Collectively, our data define a lysosomal regulatory circuit essential for macrophage development and function in vivo.
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Neely SA, Lyons DA. Insights Into Central Nervous System Glial Cell Formation and Function From Zebrafish. Front Cell Dev Biol 2021; 9:754606. [PMID: 34912801 PMCID: PMC8666443 DOI: 10.3389/fcell.2021.754606] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/05/2021] [Indexed: 12/23/2022] Open
Abstract
The term glia describes a heterogenous collection of distinct cell types that make up a large proportion of our nervous system. Although once considered the glue of the nervous system, the study of glial cells has evolved significantly in recent years, with a large body of literature now highlighting their complex and diverse roles in development and throughout life. This progress is due, in part, to advances in animal models in which the molecular and cellular mechanisms of glial cell development and function as well as neuron-glial cell interactions can be directly studied in vivo in real time, in intact neural circuits. In this review we highlight the instrumental role that zebrafish have played as a vertebrate model system for the study of glial cells, and discuss how the experimental advantages of the zebrafish lend themselves to investigate glial cell interactions and diversity. We focus in particular on recent studies that have provided insight into the formation and function of the major glial cell types in the central nervous system in zebrafish.
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Affiliation(s)
- Sarah A. Neely
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - David A. Lyons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Trzeciak A, Wang YT, Perry JSA. First we eat, then we do everything else: The dynamic metabolic regulation of efferocytosis. Cell Metab 2021; 33:2126-2141. [PMID: 34433074 PMCID: PMC8568659 DOI: 10.1016/j.cmet.2021.08.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/07/2021] [Accepted: 08/02/2021] [Indexed: 12/13/2022]
Abstract
Clearance of apoptotic cells, or "efferocytosis," is essential for diverse processes including embryonic development, tissue turnover, organ regeneration, and immune cell development. The human body is estimated to remove approximately 1% of its body mass via apoptotic cell clearance daily. This poses several intriguing cell metabolism problems. For instance, phagocytes such as macrophages must induce or suppress metabolic pathways to find, engulf, and digest apoptotic cells. Then, phagocytes must manage the potentially burdensome biomass of the engulfed apoptotic cell. Finally, phagocytes reside in complex tissue architectures that vary in nutrient availability, the types of dying cells or debris that require clearance, and the neighboring cells they interact with. Here, we review advances in our understanding of these three key areas of phagocyte metabolism. We end by proposing a model of efferocytosis that integrates recent findings and establishes a new paradigm for testing how efferocytosis prevents chronic inflammatory disease and autoimmunity.
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Affiliation(s)
- Alissa Trzeciak
- Immunology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Ya-Ting Wang
- Immunology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Justin Shaun Arnold Perry
- Immunology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, 417 E 68th Street, New York, NY 10065, USA; Department of Immunology and Microbial Pathogenesis, Weill Cornell Medical College, 417 E 68th Street, New York, NY 10065, USA.
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Contreras JL, Ladino MA, Aránguiz K, Mendez GP, Coban-Akdemir Z, Yuan B, Gibbs RA, Burrage LC, Lupski JR, Chinn IK, Vogel TP, Orange JS, Poli MC. Immune Dysregulation Mimicking Systemic Lupus Erythematosus in a Patient With Lysinuric Protein Intolerance: Case Report and Review of the Literature. Front Pediatr 2021; 9:673957. [PMID: 34095032 PMCID: PMC8172984 DOI: 10.3389/fped.2021.673957] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
Lysinuric protein intolerance (LPI) is an inborn error of metabolism caused by defective transport of cationic amino acids in epithelial cells of intestines, kidneys and other tissues as well as non-epithelial cells including macrophages. LPI is caused by biallelic, pathogenic variants in SLC7A7. The clinical phenotype of LPI includes failure to thrive and multi-system disease including hematologic, neurologic, pulmonary and renal manifestations. Individual presentations are extremely variable, often leading to misdiagnosis or delayed diagnosis. Here we describe a patient that clinically presented with immune dysregulation in the setting of early-onset systemic lupus erythematosus (SLE), including renal involvement, in whom an LPI diagnosis was suspected post-mortem based on exome sequencing analysis. A review of the literature was performed to provide an overview of the clinical spectrum and immune mechanisms involved in this disease. The precise mechanism by which ineffective amino acid transport triggers systemic inflammatory features is not yet understood. However, LPI should be considered in the differential diagnosis of early-onset SLE, particularly in the absence of response to immunosuppressive therapy.
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Affiliation(s)
| | - Mabel A. Ladino
- Universidad de Chile, Reumatóloga Pediátrica Hospital San Juan de Dios, Santiago, Chile
| | - Katherine Aránguiz
- Unidad de Inmunología y Reumatología Hospital Luis Calvo Mackenna, Providencia, Chile
| | - Gonzalo P. Mendez
- Patológo Renal, Departamento de Anatomía Patológica, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Zeynep Coban-Akdemir
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Bo Yuan
- Department of Laboratories, Seattle Children's Hospital, Seattle, WA, United States
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Richard A. Gibbs
- Sequencing Center, Baylor College of Medicine, Houston, TX, United States
| | - Lindsay C. Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Texas Children's Hospital, Houston, TX, United States
| | - James R. Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
- Sequencing Center, Baylor College of Medicine, Houston, TX, United States
- Texas Children's Hospital, Houston, TX, United States
| | - Ivan K. Chinn
- Texas Children's Hospital, Houston, TX, United States
- Department of Pediatrics, Division of Allergy, Immunology and Retrovirology, Baylor College of Medicine, Houston, TX, United States
| | - Tiphanie P. Vogel
- Texas Children's Hospital, Houston, TX, United States
- Department of Pediatrics, Division of Rheumatology, Baylor College of Medicine, Houston, TX, United States
| | - Jordan S. Orange
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, New York Presbyterian Morgan Stanley Children's Hospital, Columbia University, New York, NY, United States
| | - M. Cecilia Poli
- Facultad de Medicina Universidad del Desarrollo-Clínica Alemana, Santiago, Chile
- Department of Pediatrics, Division of Allergy, Immunology and Retrovirology, Baylor College of Medicine, Houston, TX, United States
- Unidad de Inmunología y Reumatología, Hospital Roberto del Río, Santiago, Chile
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