1
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Clayton BLL, Barbar L, Sapar M, Kalpana K, Rao C, Migliori B, Rusielewicz T, Paull D, Brenner K, Moroziewicz D, Sand IK, Casaccia P, Tesar PJ, Fossati V. Patient iPSC models reveal glia-intrinsic phenotypes in multiple sclerosis. Cell Stem Cell 2024:S1934-5909(24)00288-1. [PMID: 39191254 DOI: 10.1016/j.stem.2024.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 06/17/2024] [Accepted: 08/05/2024] [Indexed: 08/29/2024]
Abstract
Multiple sclerosis (MS) is an inflammatory and neurodegenerative disease of the central nervous system (CNS), resulting in neurological disability that worsens over time. While progress has been made in defining the immune system's role in MS pathophysiology, the contribution of intrinsic CNS cell dysfunction remains unclear. Here, we generated a collection of induced pluripotent stem cell (iPSC) lines from people with MS spanning diverse clinical subtypes and differentiated them into glia-enriched cultures. Using single-cell transcriptomic profiling and orthogonal analyses, we observed several distinguishing characteristics of MS cultures pointing to glia-intrinsic disease mechanisms. We found that primary progressive MS-derived cultures contained fewer oligodendrocytes. Moreover, MS-derived oligodendrocyte lineage cells and astrocytes showed increased expression of immune and inflammatory genes, matching those of glia from MS postmortem brains. Thus, iPSC-derived MS models provide a unique platform for dissecting glial contributions to disease phenotypes independent of the peripheral immune system and identify potential glia-specific targets for therapeutic intervention.
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Affiliation(s)
- Benjamin L L Clayton
- Institute for Glial Sciences, Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Lilianne Barbar
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Maria Sapar
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Kriti Kalpana
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Chandrika Rao
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Bianca Migliori
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Tomasz Rusielewicz
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Daniel Paull
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Katie Brenner
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Dorota Moroziewicz
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Ilana Katz Sand
- Corinne Goldsmith Dickinson Center for Multiple Sclerosis, Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10129, USA
| | - Patrizia Casaccia
- Neuroscience Initiative, Advanced Science Research Center at CUNY, New York, NY 10031, USA
| | - Paul J Tesar
- Institute for Glial Sciences, Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
| | - Valentina Fossati
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA.
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2
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Clayton BL, Barbar L, Sapar M, Rusielewicz T, Kalpana K, Migliori B, Paull D, Brenner K, Moroziewicz D, Sand IK, Casaccia P, Tesar PJ, Fossati V. Patient iPSC models reveal glia-intrinsic phenotypes in multiple sclerosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.01.551553. [PMID: 37577713 PMCID: PMC10418164 DOI: 10.1101/2023.08.01.551553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Multiple sclerosis (MS) is considered an inflammatory and neurodegenerative disease of the central nervous system, typically resulting in significant neurological disability that worsens over time. While considerable progress has been made in defining the immune system's role in MS pathophysiology, the contribution of intrinsic CNS-cell dysfunction remains unclear. Here, we generated the largest reported collection of iPSC lines from people with MS spanning diverse clinical subtypes and differentiated them into glia-enriched cultures. Using single-cell transcriptomic profiling, we observed several distinguishing characteristics of MS cultures pointing to glia-intrinsic disease mechanisms. We found that iPSC-derived cultures from people with primary progressive MS contained fewer oligodendrocytes. Moreover, iPSC-oligodendrocyte lineage cells and astrocytes from people with MS showed increased expression of immune and inflammatory genes that match those of glial cells from MS postmortem brains. Thus, iPSC-derived MS models provide a unique platform for dissecting glial contributions to disease phenotypes independent of the peripheral immune system and identify potential glia-specific targets for therapeutic intervention.
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Affiliation(s)
- Benjamin L.L. Clayton
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
- These authors contributed equally
| | - Lilianne Barbar
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
- Current affiliation: Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63105, USA
- These authors contributed equally
| | - Maria Sapar
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Tomasz Rusielewicz
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Kriti Kalpana
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Bianca Migliori
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | | | - Daniel Paull
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Katie Brenner
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Dorota Moroziewicz
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
| | - Ilana Katz Sand
- Corinne Goldsmith Dickinson Center for Multiple Sclerosis, Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10129, USA
| | | | - Paul J. Tesar
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Valentina Fossati
- The New York Stem Cell Foundation Research Institute, New York, NY 10019, USA
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3
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Santos-Ledo A, Pérez-Montes C, DeOliveira-Mello L, Arévalo R, Velasco A. Oligodendrocyte origin and development in the zebrafish visual system. J Comp Neurol 2023; 531:515-527. [PMID: 36477827 PMCID: PMC10107312 DOI: 10.1002/cne.25440] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Revised: 09/19/2022] [Accepted: 11/23/2022] [Indexed: 12/12/2022]
Abstract
Oligodendrocytes are the myelinating cells in the central nervous system. In birds and mammals, the oligodendrocyte progenitor cells (OPCs) originate in the preoptic area (POA) of the hypothalamus. However, it remains unclear in other vertebrates such as fish. Thus, we have studied the early progression of OPCs during zebrafish visual morphogenesis from 2 days post fertilization (dpf) until 11 dpf using the olig2:EGFP transgenic line; and we have analyzed the differential expression of transcription factors involved in oligodendrocyte differentiation: Sox2 (using immunohistochemistry) and Sox10 (using the transgenic line sox10:tagRFP). The first OPCs (olig2:EGFP/Sox2) were found at 2 dpf in the POA. From 3 dpf onwards, these olig2:EGFP/Sox2 cells migrate to the optic chiasm, where they invade the optic nerve (ON), extending toward the retina. At 5 dpf, olig2:EGFP/Sox2 cells in the ON also colocalize with sox10:tagRFP. When olig2:EGFP cells differentiate and present more projections, they become positive only for sox10:tagRFP. olig2:EGFP/sox10: tagRFP cells ensheath the ON by 5 dpf when they also become positive for a myelin marker, based on the mbpa:tagRFPt transgenic line. We also found olig2:EGFP cells in other regions of the visual system. In the central retina at 2 dpf, they are positive for Sox2 but later become restricted to the proliferative germinal zone without this marker. In the ventricular areas of the optic tectum, olig2:EGFP cells present Sox2 but arborized ones sox10:tagRFP instead. Our data matches with other models, where OPCs are specified in the POA and migrate to the ON through the optic chiasm.
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Affiliation(s)
- Adrián Santos-Ledo
- Department of Cell Biology and Pathology, Instituto de NeurocienciasdeCastilla y León (INCyL), Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
| | - Cristina Pérez-Montes
- Department of Cell Biology and Pathology, Instituto de NeurocienciasdeCastilla y León (INCyL), Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
| | - Laura DeOliveira-Mello
- Department of Cell Biology and Pathology, Instituto de NeurocienciasdeCastilla y León (INCyL), Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
| | - Rosario Arévalo
- Department of Cell Biology and Pathology, Instituto de NeurocienciasdeCastilla y León (INCyL), Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
| | - Almudena Velasco
- Department of Cell Biology and Pathology, Instituto de NeurocienciasdeCastilla y León (INCyL), Universidad de Salamanca, Salamanca, Spain.,Instituto de Investigación Biomédica de Salamanca (IBSAL), Salamanca, Spain
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4
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Spencer SA, Suárez-Pozos E, Verdugo JS, Wang H, Afshari FS, Li G, Manam S, Yasuda D, Ortega A, Lister JA, Ishii S, Zhang Y, Fuss B. Lysophosphatidic acid signaling via LPA 6 : A negative modulator of developmental oligodendrocyte maturation. J Neurochem 2022; 163:478-499. [PMID: 36153691 PMCID: PMC9772207 DOI: 10.1111/jnc.15696] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 01/14/2023]
Abstract
The developmental process of central nervous system (CNS) myelin sheath formation is characterized by well-coordinated cellular activities ultimately ensuring rapid and synchronized neural communication. During this process, myelinating CNS cells, namely oligodendrocytes (OLGs), undergo distinct steps of differentiation, whereby the progression of earlier maturation stages of OLGs represents a critical step toward the timely establishment of myelinated axonal circuits. Given the complexity of functional integration, it is not surprising that OLG maturation is controlled by a yet fully to be defined set of both negative and positive modulators. In this context, we provide here first evidence for a role of lysophosphatidic acid (LPA) signaling via the G protein-coupled receptor LPA6 as a negative modulatory regulator of myelination-associated gene expression in OLGs. More specifically, the cell surface accessibility of LPA6 was found to be restricted to the earlier maturation stages of differentiating OLGs, and OLG maturation was found to occur precociously in Lpar6 knockout mice. To further substantiate these findings, a novel small molecule ligand with selectivity for preferentially LPA6 and LPA6 agonist characteristics was functionally characterized in vitro in primary cultures of rat OLGs and in vivo in the developing zebrafish. Utilizing this approach, a negative modulatory role of LPA6 signaling in OLG maturation could be corroborated. During development, such a functional role of LPA6 signaling likely serves to ensure timely coordination of circuit formation and myelination. Under pathological conditions as seen in the major human demyelinating disease multiple sclerosis (MS), however, persistent LPA6 expression and signaling in OLGs can be seen as an inhibitor of myelin repair. Thus, it is of interest that LPA6 protein levels appear elevated in MS brain samples, thereby suggesting that LPA6 signaling may represent a potential new druggable pathway suitable to promote myelin repair in MS.
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Affiliation(s)
- Samantha A Spencer
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Edna Suárez-Pozos
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Jazmín Soto Verdugo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - Huiqun Wang
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Fatemah S Afshari
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Guo Li
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Susmita Manam
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Daisuke Yasuda
- Department of Immunology, Akita University Graduate School of Medicine, Akita, Japan
| | - Arturo Ortega
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del IPN, Ciudad de México, México
| | - James A Lister
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
| | - Satoshi Ishii
- Department of Immunology, Akita University Graduate School of Medicine, Akita, Japan
| | - Yan Zhang
- Department of Medicinal Chemistry, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, USA
| | - Babette Fuss
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia, USA
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5
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Mani A, Salinas I. The knowns and many unknowns of CNS immunity in teleost fish. FISH & SHELLFISH IMMUNOLOGY 2022; 131:431-440. [PMID: 36241002 DOI: 10.1016/j.fsi.2022.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Many disease agents infect the central nervous system (CNS) of teleost fish causing severe losses for the fish farming sector. Yet, neurotropic fish pathogens remain poorly documented and immune responses in the teleost CNS essentially unknown. Previously thought to be devoid of an immune system, the mammalian CNS is now recognized to be protected from infection by diverse immune cells that mostly reside in the meningeal lymphatic system. Here we review the current body of work pertaining immune responses in the teleost CNS to infection. We identify important knowledge gaps with regards to CNS immunity in fish and make recommendations for rigorous experimentation and reporting in manuscripts so that fish immunologists can advance this burgeoning field.
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Affiliation(s)
- Amir Mani
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Irene Salinas
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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6
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Humanized zebrafish as a tractable tool for in vivo evaluation of pro-myelinating drugs. Cell Chem Biol 2022; 29:1541-1555.e7. [PMID: 36126653 DOI: 10.1016/j.chembiol.2022.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 05/25/2022] [Accepted: 08/24/2022] [Indexed: 12/14/2022]
Abstract
Therapies that promote neuroprotection and axonal survival by enhancing myelin regeneration are an unmet need to prevent disability progression in multiple sclerosis. Numerous potentially beneficial compounds have originated from phenotypic screenings but failed in clinical trials. It is apparent that current cell- and animal-based disease models are poor predictors of positive treatment options, arguing for novel experimental approaches. Here we explore the experimental power of humanized zebrafish to foster the identification of pro-remyelination compounds via specific inhibition of GPR17. Using biochemical and imaging techniques, we visualize the expression of zebrafish (zf)-gpr17 during the distinct stages of oligodendrocyte development, thereby demonstrating species-conserved expression between zebrafish and mammals. We also demonstrate species-conserved function of zf-Gpr17 using genetic loss-of-function and rescue techniques. Finally, using GPR17-humanized zebrafish, we provide proof of principle for in vivo analysis of compounds acting via targeted inhibition of human GPR17. We anticipate that GPR17-humanized zebrafish will markedly improve the search for effective pro-myelinating pharmacotherapies.
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7
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Xing L, Chai R, Wang J, Lin J, Li H, Wang Y, Lai B, Sun J, Chen G. Expression of myelin transcription factor 1 and lamin B receptor mediate neural progenitor fate transition in the zebrafish spinal cord pMN domain. J Biol Chem 2022; 298:102452. [PMID: 36063998 PMCID: PMC9530849 DOI: 10.1016/j.jbc.2022.102452] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/17/2022] [Accepted: 08/20/2022] [Indexed: 02/05/2023] Open
Abstract
The pMN domain is a restricted domain in the ventral spinal cord, defined by the expression of the olig2 gene. Though it is known that the pMN progenitor cells can sequentially generate motor neurons and oligodendrocytes, the lineages of these progenitors are controversial and how their progeny are generated is not well understood. Using single-cell RNA sequencing, here, we identified a previously unknown heterogeneity among pMN progenitors with distinct fates and molecular signatures in zebrafish. Notably, we characterized two distinct motor neuron lineages using bioinformatic analysis. We then went on to investigate specific molecular programs that regulate neural progenitor fate transition. We validated experimentally that expression of the transcription factor myt1 (myelin transcription factor 1) and inner nuclear membrane integral proteins lbr (lamin B receptor) were critical for the development of motor neurons and neural progenitor maintenance, respectively. We anticipate that the transcriptome features and molecular programs identified in zebrafish pMN progenitors will not only provide an in-depth understanding of previous findings regarding the lineage analysis of oligodendrocyte progenitor cells and motor neurons but will also help in further understanding of the molecular programming involved in neural progenitor fate transition.
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Affiliation(s)
- Lingyan Xing
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China,For correspondence: Lingyan Xing; Gang Chen
| | - Rui Chai
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Jiaqi Wang
- Department of Physiology, School of Medicine, Nantong University, Nantong, China
| | - Jiaqi Lin
- Department of Physiology, School of Medicine, Nantong University, Nantong, China
| | - Hanyang Li
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Yueqi Wang
- School of Medicine, University of Utah, Salt Lake City, Utah, USA
| | - Biqin Lai
- Key Laboratory for Stem Cells and Tissue Engineering (Sun Yat-sen University), Ministry of Education, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, China
| | - Junjie Sun
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China
| | - Gang Chen
- Key Laboratory of Neuroregeneration of Jiangsu and the Ministry of Education, Co-Innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, China,Basic Medical Research Center, School of Medicine, Nantong University, Nantong, China,For correspondence: Lingyan Xing; Gang Chen
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8
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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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9
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Lang I, Virk G, Zheng DC, Young J, Nguyen MJ, Amiri R, Fong M, Arata A, Chadaideh KS, Walsh S, Weiser DC. The Evolution of Duplicated Genes of the Cpi-17/Phi-1 ( ppp1r14) Family of Protein Phosphatase 1 Inhibitors in Teleosts. Int J Mol Sci 2020; 21:ijms21165709. [PMID: 32784920 PMCID: PMC7460850 DOI: 10.3390/ijms21165709] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 08/07/2020] [Indexed: 11/29/2022] Open
Abstract
The Cpi-17 (ppp1r14) gene family is an evolutionarily conserved, vertebrate specific group of protein phosphatase 1 (PP1) inhibitors. When phosphorylated, Cpi-17 is a potent inhibitor of myosin phosphatase (MP), a holoenzyme complex of the regulatory subunit Mypt1 and the catalytic subunit PP1. Myosin phosphatase dephosphorylates the regulatory myosin light chain (Mlc2) and promotes actomyosin relaxation, which in turn, regulates numerous cellular processes including smooth muscle contraction, cytokinesis, cell motility, and tumor cell invasion. We analyzed zebrafish homologs of the Cpi-17 family, to better understand the mechanisms of myosin phosphatase regulation. We found single homologs of both Kepi (ppp1r14c) and Gbpi (ppp1r14d) in silico, but we detected no expression of these genes during early embryonic development. Cpi-17 (ppp1r14a) and Phi-1 (ppp1r14b) each had two duplicate paralogs, (ppp1r14aa and ppp1r14ab) and (ppp1r14ba and ppp1r14bb), which were each expressed during early development. The spatial expression pattern of these genes has diverged, with ppp1r14aa and ppp1r14bb expressed primarily in smooth muscle and skeletal muscle, respectively, while ppp1r14ab and ppp1r14ba are primarily expressed in neural tissue. We observed that, in in vitro and heterologous cellular systems, the Cpi-17 paralogs both acted as potent myosin phosphatase inhibitors, and were indistinguishable from one another. In contrast, the two Phi-1 paralogs displayed weak myosin phosphatase inhibitory activity in vitro, and did not alter myosin phosphorylation in cells. Through deletion and chimeric analysis, we identified that the difference in specificity for myosin phosphatase between Cpi-17 and Phi-1 was encoded by the highly conserved PHIN (phosphatase holoenzyme inhibitory) domain, and not the more divergent N- and C- termini. We also showed that either Cpi-17 paralog can rescue the knockdown phenotype, but neither Phi-1 paralog could do so. Thus, we provide new evidence about the biochemical and developmental distinctions of the zebrafish Cpi-17 protein family.
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Affiliation(s)
- Irene Lang
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Guneet Virk
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Dale C. Zheng
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Jason Young
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Michael J. Nguyen
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Rojin Amiri
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Michelle Fong
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Alisa Arata
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
| | - Katia S. Chadaideh
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Susan Walsh
- Life Sciences, Soka University of America, Aliso Viejo, CA 92656, USA;
| | - Douglas C. Weiser
- Department of Biological Sciences, University of the Pacific, Stockton, CA 98211, USA; (I.L.); (G.V.); (D.C.Z.); (J.Y.); (M.J.N.); (R.A.); (M.F.); (A.A.); (K.S.C.)
- Correspondence: ; Tel.: +1-209-946-2955
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10
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Nagarajan B, Harder A, Japp A, Häberlein F, Mingardo E, Kleinert H, Yilmaz Ö, Zoons A, Rau B, Christ A, Kubitscheck U, Eiberger B, Sandhoff R, Eckhardt M, Hartmann D, Odermatt B. CNS myelin protein 36K regulates oligodendrocyte differentiation through Notch. Glia 2019; 68:509-527. [PMID: 31702067 DOI: 10.1002/glia.23732] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/23/2019] [Accepted: 09/24/2019] [Indexed: 12/12/2022]
Abstract
In contrast to humans and other mammals, zebrafish can successfully regenerate and remyelinate central nervous system (CNS) axons following injury. In addition to common myelin proteins found in mammalian myelin, 36K protein is a major component of teleost fish CNS myelin. Although 36K is one of the most abundant proteins in zebrafish brain, its function remains unknown. Here we investigate the function of 36K using translation-blocking Morpholinos. Morphant larvae showed fewer dorsally migrated oligodendrocyte precursor cells as well as upregulation of Notch ligand. A gamma secretase inhibitor, which prevents activation of Notch, could rescue oligodendrocyte precursor cell numbers in 36K morphants, suggesting that 36K regulates initial myelination through inhibition of Notch signaling. Since 36K like other short chain dehydrogenases might act on lipids, we performed thin layer chromatography and mass spectrometry of lipids and found changes in lipid composition in 36K morphant larvae. Altogether, we suggest that during early development 36K regulates membrane lipid composition, thereby altering the amount of transmembrane Notch ligands and the efficiency of intramembrane gamma secretase processing of Notch and thereby influencing oligodendrocyte precursor cell differentiation and further myelination. Further studies on the role of 36K short chain dehydrogenase in oligodendrocyte precursor cell differentiation during remyelination might open up new strategies for remyelination therapies in human patients.
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Affiliation(s)
- Bhuvaneswari Nagarajan
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Alexander Harder
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Anna Japp
- Institute of Neuropathology, University Clinics, University of Bonn, Bonn, Germany
| | - Felix Häberlein
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany.,Molecular, Cellular and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, Bonn, Germany
| | - Enrico Mingardo
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Henning Kleinert
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Öznur Yilmaz
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Angelika Zoons
- Institute of Anatomy, Division of Neuroanatomy, University Clinics, University of Bonn, Bonn, Germany
| | - Birgit Rau
- Institute of Anatomy, Division of Neuroanatomy, University Clinics, University of Bonn, Bonn, Germany
| | - Andrea Christ
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn, Germany
| | - Britta Eiberger
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Roger Sandhoff
- Lipid Pathobiochemistry Group, German Cancer Research Centre, Heidelberg, Germany
| | - Matthias Eckhardt
- Institute of Biochemistry and Molecular Biology, University Clinics, University of Bonn, Bonn, Germany
| | - Dieter Hartmann
- Institute of Anatomy, Division of Neuroanatomy, University Clinics, University of Bonn, Bonn, Germany
| | - Benjamin Odermatt
- Institute of Anatomy, Division of Anatomy and Cell Biology, University Clinics, University of Bonn, Bonn, Germany.,Institute of Anatomy, Division of Neuroanatomy, University Clinics, University of Bonn, Bonn, Germany
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11
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Abstract
In situ hybridization enables visualization of mRNA localization, and immunohistochemistry enables visualization of protein localization within a tissue or organism. Both techniques have been extensively utilized in zebrafish (Thisse et al., Development 119:1203-1215, 1993; Dutton et al., Development 128:4113-4125, 2001; Gilmour et al., Neuron 34:577-588, 2002; Lyons et al., Curr Biol 15:513-524, 2005) including for visualization of mRNA localization in Schwann cells (Lyons et al., Curr Biol 15:513-524, 2005; Monk et al., Science 325:1402-1405, 2009). For in situ hybridization, here, we outline how to generate RNA probes, conduct whole mount in situ hybridization for larvae, and list RNA probes that label different stages of Schwann cell development in zebrafish. For immunohistochemistry, the protocol we outline can be used to mark Schwann cells of sensory and motor nerves to examine properties such as developmental stage, morphology, proliferation, and apoptosis.
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12
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Abstract
Myelin is a lipid-rich sheath formed by the spiral wrapping of specialized glial cells around axon segments. Myelinating glia allow for rapid transmission of nerve impulses and metabolic support of axons, and the absence of or disruption to myelin results in debilitating motor, cognitive, and emotional deficits in humans. Because myelin is a jawed vertebrate innovation, zebrafish are one of the simplest vertebrate model systems to study the genetics and development of myelinating glia. The morphogenetic cellular movements and genetic program that drive myelination are conserved between zebrafish and mammals, and myelin develops rapidly in zebrafish larvae, within 3-5days postfertilization. Myelin ultrastructure can be visualized in the zebrafish from larval to adult stages via transmission electron microscopy, and the dynamic development of myelinating glial cells may be observed in vivo via transgenic reporter lines in zebrafish larvae. Zebrafish are amenable to genetic and pharmacological screens, and screens for myelinating glial phenotypes have revealed both genes and drugs that promote myelin development, many of which are conserved in mammalian glia. Recently, zebrafish have been employed as a model to understand the complex dynamics of myelinating glia during development and regeneration. In this chapter, we describe these key methodologies and recent insights into mechanisms that regulate myelination using the zebrafish model.
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Affiliation(s)
- M D'Rozario
- Washington University School of Medicine, St. Louis, MO, United States
| | - K R Monk
- Washington University School of Medicine, St. Louis, MO, United States; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, United States
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13
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Rouhiainen A, Zhao X, Vanttola P, Qian K, Kulesskiy E, Kuja-Panula J, Gransalke K, Grönholm M, Unni E, Meistrich M, Tian L, Auvinen P, Rauvala H. HMGB4 is expressed by neuronal cells and affects the expression of genes involved in neural differentiation. Sci Rep 2016; 6:32960. [PMID: 27608812 PMCID: PMC5036535 DOI: 10.1038/srep32960] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Accepted: 08/18/2016] [Indexed: 12/21/2022] Open
Abstract
HMGB4 is a new member in the family of HMGB proteins that has been characterized in sperm cells, but little is known about its functions in somatic cells. Here we show that HMGB4 and the highly similar rat Transition Protein 4 (HMGB4L1) are expressed in neuronal cells. Both proteins had slow mobility in nucleus of living NIH-3T3 cells. They interacted with histones and their differential expression in transformed cells of the nervous system altered the post-translational modification statuses of histones in vitro. Overexpression of HMGB4 in HEK 293T cells made cells more susceptible to cell death induced by topoisomerase inhibitors in an oncology drug screening array and altered variant composition of histone H3. HMGB4 regulated over 800 genes in HEK 293T cells with a p-value ≤0.013 (n = 3) in a microarray analysis and displayed strongest association with adhesion and histone H2A –processes. In neuronal and transformed cells HMGB4 regulated the expression of an oligodendrocyte marker gene PPP1R14a and other neuronal differentiation marker genes. In conclusion, our data suggests that HMGB4 is a factor that regulates chromatin and expression of neuronal differentiation markers.
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Affiliation(s)
- Ari Rouhiainen
- Neuroscience center, University of Helsinki, Finland.,Department of Biosciences, University of Helsinki, Finland
| | - Xiang Zhao
- Neuroscience center, University of Helsinki, Finland.,Schools of Pharmacy and Medicine, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | | | - Kui Qian
- Institute of Biotechnology, University of Helsinki, Finland
| | - Evgeny Kulesskiy
- Neuroscience center, University of Helsinki, Finland.,Institute for Molecular Medicine Finland, FIMM, University of Helsinki, Finland
| | | | | | | | - Emmanual Unni
- Department of Biochemistry, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Marvin Meistrich
- Department of Experimental Radiation Oncology, Division of Radiation Oncology, MD Anderson Cancer Center, Houston, Texas, USA
| | - Li Tian
- Neuroscience center, University of Helsinki, Finland.,Psychiatry Research Center, Beijing Hui Long Guan Hospital, Peking University, Beijing, China
| | - Petri Auvinen
- Institute of Biotechnology, University of Helsinki, Finland
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14
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Kozol RA, Abrams AJ, James DM, Buglo E, Yan Q, Dallman JE. Function Over Form: Modeling Groups of Inherited Neurological Conditions in Zebrafish. Front Mol Neurosci 2016; 9:55. [PMID: 27458342 PMCID: PMC4935692 DOI: 10.3389/fnmol.2016.00055] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022] Open
Abstract
Zebrafish are a unique cell to behavior model for studying the basic biology of human inherited neurological conditions. Conserved vertebrate genetics and optical transparency provide in vivo access to the developing nervous system as well as high-throughput approaches for drug screens. Here we review zebrafish modeling for two broad groups of inherited conditions that each share genetic and molecular pathways and overlap phenotypically: neurodevelopmental disorders such as Autism Spectrum Disorders (ASD), Intellectual Disability (ID) and Schizophrenia (SCZ), and neurodegenerative diseases, such as Cerebellar Ataxia (CATX), Hereditary Spastic Paraplegia (HSP) and Charcot-Marie Tooth Disease (CMT). We also conduct a small meta-analysis of zebrafish orthologs of high confidence neurodevelopmental disorder and neurodegenerative disease genes by looking at duplication rates and relative protein sizes. In the past zebrafish genetic models of these neurodevelopmental disorders and neurodegenerative diseases have provided insight into cellular, circuit and behavioral level mechanisms contributing to these conditions. Moving forward, advances in genetic manipulation, live imaging of neuronal activity and automated high-throughput molecular screening promise to help delineate the mechanistic relationships between different types of neurological conditions and accelerate discovery of therapeutic strategies.
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Affiliation(s)
- Robert A. Kozol
- Department of Biology, University of MiamiCoral Gables, FL, USA
| | - Alexander J. Abrams
- Department of Human Genetics, John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation, University of MiamiMiami, FL, USA
| | - David M. James
- Department of Biology, University of MiamiCoral Gables, FL, USA
| | - Elena Buglo
- Department of Human Genetics, John P. Hussman Institute for Human Genomics, Dr. John T. Macdonald Foundation, University of MiamiMiami, FL, USA
| | - Qing Yan
- Department of Biology, University of MiamiCoral Gables, FL, USA
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15
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Smith CJ, Johnson K, Welsh TG, Barresi MJF, Kucenas S. Radial glia inhibit peripheral glial infiltration into the spinal cord at motor exit point transition zones. Glia 2016; 64:1138-53. [PMID: 27029762 DOI: 10.1002/glia.22987] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 03/12/2016] [Accepted: 03/14/2016] [Indexed: 11/09/2022]
Abstract
In the mature vertebrate nervous system, central and peripheral nervous system (CNS and PNS, respectively) GLIA myelinate distinct motor axon domains at the motor exit point transition zone (MEP TZ). How these cells preferentially associate with and myelinate discrete, non-overlapping CNS versus PNS axonal segments, is unknown. Using in vivo imaging and genetic cell ablation in zebrafish, we demonstrate that radial glia restrict migration of PNS glia into the spinal cord during development. Prior to development of radial glial endfeet, peripheral cells freely migrate back and forth across the MEP TZ. However, upon maturation, peripherally located cells never enter the CNS. When we ablate radial glia, peripheral glia ectopically migrate into the spinal cord during developmental stages when they would normally be restricted. These findings demonstrate that radial glia contribute to both CNS and PNS development and control the unidirectional movement of glial cell types across the MEP TZ early in development. GLIA 2016. GLIA 2016;64:1138-1153.
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Affiliation(s)
- Cody J Smith
- Department of Biology, University of Virginia, Charlottesville, Virginia, 22904
| | - Kimberly Johnson
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01003
| | - Taylor G Welsh
- Department of Biology, University of Virginia, Charlottesville, Virginia, 22904.,Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia, 22904
| | - Michael J F Barresi
- Department of Biological Sciences, Smith College, Northampton, Massachusetts, 01003.,Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts, 01003
| | - Sarah Kucenas
- Department of Biology, University of Virginia, Charlottesville, Virginia, 22904.,Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia, 22904
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16
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Abstract
UNLABELLED An important characteristic of vertebrate CNS development is the formation of specific amounts of insulating myelin membrane on axons. CNS myelin is produced by oligodendrocytes, glial cells that extend multiple membrane processes to wrap multiple axons. Recent data have shown that signaling mediated by the mechanistic target of rapamycin (mTOR) serine/threonine kinase promotes myelination, but factors that regulate mTOR activity for myelination remain poorly defined. Through a forward genetic screen in zebrafish, we discovered that mutation of fbxw7, which encodes the substrate recognition subunit of a SCF ubiquitin ligase that targets proteins for degradation, causes hypermyelination. Among known Fbxw7 targets is mTOR. Here, we provide evidence that mTOR signaling activity is elevated in oligodendrocyte lineage cells of fbxw7 mutant zebrafish larvae. Both genetic and pharmacological inhibition of mTOR function suppressed the excess myelin gene expression resulting from loss of Fbxw7 function, indicating that mTOR is a functionally relevant target of Fbxw7 in oligodendrocytes. fbxw7 mutant larvae wrapped axons with more myelin membrane than wild-type larvae and oligodendrocyte-specific expression of dominant-negative Fbxw7 produced longer myelin sheaths. Our data indicate that Fbxw7 limits the myelin-promoting activity of mTOR, thereby serving as an important brake on developmental myelination. SIGNIFICANCE STATEMENT Myelin, a specialized, proteolipid-rich membrane that ensheaths and insulates nerve fibers, facilitates the rapid conduction of electrical impulses over long distances. Abnormalities in myelin formation or maintenance result in intellectual and motor disabilities, raising a need for therapeutic strategies designed to promote myelination. The mTOR kinase is a powerful driver of myelination, but the mechanisms that regulate mTOR function in myelination are not well understood. Our studies reveal that Fbxw7, a subunit of a ubiquitin ligase that targets other proteins for degradation, acts as a brake on myelination by limiting mTOR function. These findings suggest that Fbxw7 helps tune the amount of myelin produced during development and raise the possibility that Fbxw7 could be a target of myelin-promoting therapies.
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17
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The Autotaxin-Lysophosphatidic Acid Axis Modulates Histone Acetylation and Gene Expression during Oligodendrocyte Differentiation. J Neurosci 2015; 35:11399-414. [PMID: 26269646 DOI: 10.1523/jneurosci.0345-15.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED During development, oligodendrocytes (OLGs), the myelinating cells of the CNS, undergo a stepwise progression during which OLG progenitors, specified from neural stem/progenitor cells, differentiate into fully mature myelinating OLGs. This progression along the OLG lineage is characterized by well synchronized changes in morphology and gene expression patterns. The latter have been found to be particularly critical during the early stages of the lineage, and they have been well described to be regulated by epigenetic mechanisms, especially by the activity of the histone deacetylases HDAC1 and HDAC2. The data presented here identify the extracellular factor autotaxin (ATX) as a novel upstream signal modulating HDAC1/2 activity and gene expression in cells of the OLG lineage. Using the zebrafish as an in vivo model system as well as rodent primary OLG cultures, this functional property of ATX was found to be mediated by its lysophospholipase D (lysoPLD) activity, which has been well characterized to generate the lipid signaling molecule lysophosphatidic acid (LPA). More specifically, the lysoPLD activity of ATX was found to modulate HDAC1/2 regulated gene expression during a time window coinciding with the transition from OLG progenitor to early differentiating OLG. In contrast, HDAC1/2 regulated gene expression during the transition from neural stem/progenitor to OLG progenitor appeared unaffected by ATX and its lysoPLD activity. Thus, together, our data suggest that an ATX-LPA-HDAC1/2 axis regulates OLG differentiation specifically during the transition from OLG progenitor to early differentiating OLG and via a molecular mechanism that is evolutionarily conserved from at least zebrafish to rodent. SIGNIFICANCE STATEMENT The formation of the axon insulating and supporting myelin sheath by differentiating oligodendrocytes (OLGs) in the CNS is considered an essential step during vertebrate development. In addition, loss and/or dysfunction of the myelin sheath has been associated with a variety of neurologic diseases in which repair is limited, despite the presence of progenitor cells with the potential to differentiate into myelinating OLGs. This study characterizes the autotaxin-lysophosphatidic acid signaling axis as a modulator of OLG differentiation in vivo in the developing zebrafish and in vitro in rodent OLGs in culture. These findings provide novel insight into the regulation of developmental myelination, and they are likely to lead to advancing studies related to the stimulation of myelin repair under pathologic conditions.
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18
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Abstract
Vertebrate myelination is an evolutionary advancement essential for motor, sensory, and higher-order cognitive function. CNS myelin, a multilamellar differentiation of the oligodendrocyte plasma membrane, ensheaths axons to facilitate electrical conduction. Myelination is one of the most pivotal cell-cell interactions for normal brain development, involving extensive information exchange between differentiating oligodendrocytes and axons. The molecular mechanisms of myelination are discussed, along with new perspectives on oligodendrocyte plasticity and myelin remodeling of the developing and adult CNS.
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19
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Ristori E, Lopez-Ramirez MA, Narayanan A, Hill-Teran G, Moro A, Calvo CF, Thomas JL, Nicoli S. A Dicer-miR-107 Interaction Regulates Biogenesis of Specific miRNAs Crucial for Neurogenesis. Dev Cell 2015; 32:546-60. [PMID: 25662174 DOI: 10.1016/j.devcel.2014.12.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 10/16/2014] [Accepted: 12/17/2014] [Indexed: 01/07/2023]
Abstract
Dicer controls the biogenesis of microRNAs (miRNAs) and is essential for neurogenesis. Recent reports show that the levels and substrate selectivity of DICER result in the preferential biogenesis of specific miRNAs in vitro. However, how dicer expression levels and miRNA biogenesis are regulated in vivo and how this affects neurogenesis is incompletely understood. Here we show that during zebrafish hindbrain development dicer expression levels are controlled by miR-107 to tune the biogenesis of specific miRNAs, such as miR-9, whose levels regulate neurogenesis. Loss of miR-107 function stabilizes dicer levels and miR-9 biogenesis across the ventricular hindbrain zone, resulting in an increase of both proliferating progenitors and postmitotic neurons. miR-9 ectopic accumulation in differentiating neuronal cells recapitulated the excessive neurogenesis phenotype. We propose that miR-107 modulation of dicer levels in differentiating neuronal cells is required to maintain the homeostatic levels of specific miRNAs, whose precise accumulation is essential for neurogenesis.
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Affiliation(s)
- Emma Ristori
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA
| | | | - Anand Narayanan
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA
| | - Guillermina Hill-Teran
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA
| | - Albertomaria Moro
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA
| | - Charles-Félix Calvo
- University Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epiniere, UMR S975, Paris 75651, France; INSERM/CNRS U-1127/UMR-7225, Paris 75651, France; AP-HP, Groupe Hospitalier Pitié-Salpètrière, Paris 75651, France
| | - Jean-Léon Thomas
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA; University Pierre et Marie Curie-Paris 6, Centre de Recherche de l'Institut du Cerveau et de la Moelle Epiniere, UMR S975, Paris 75651, France; INSERM/CNRS U-1127/UMR-7225, Paris 75651, France; AP-HP, Groupe Hospitalier Pitié-Salpètrière, Paris 75651, France
| | - Stefania Nicoli
- Yale Cardiovascular Research Center, Internal Medicine, Yale University, New Haven, CT 06511, USA.
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20
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Dumas L, Heitz-Marchaland C, Fouquet S, Suter U, Livet J, Moreau-Fauvarque C, Chédotal A. Multicolor analysis of oligodendrocyte morphology, interactions, and development with Brainbow. Glia 2014; 63:699-717. [PMID: 25530205 DOI: 10.1002/glia.22779] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 12/08/2014] [Indexed: 11/12/2022]
Abstract
Oligodendrocytes are the myelinating cells of the central nervous system. Multiple markers are available to analyze the populations of oligodendroglial cells and their precursors during development and in pathological conditions. However, the behavior of oligodendrocytes remains poorly characterized in vivo, especially at the level of individual cells. Studying this aspect has been impaired so far by the lack of suitable methods for visualizing single oligodendrocytes, their processes, and their interactions during myelination. Here, we have used multicolor labeling technology to single-out simultaneously many individual oligodendrocytes in the postnatal mouse optic nerve. This method is based on Brainbow, a transgenic system for stochastic expression of multiple fluorescent protein genes through Cre-lox recombination, previously used for visualizing axons and neurons. We used tamoxifen-inducible recombination in myelinating cells of Brainbow transgenic mice to obtain multicolor labeling of oligodendrocytes. We show that the palette of colors expressed by labeled oligodendrocytes is tamoxifen dependent, with the highest doses producing the densest and most colorful labeling. At low doses of tamoxifen, the morphology of single or small clusters of fluorescent oligodendrocytes can be studied during postnatal development and in adult. Internodes are labeled to their extremities, revealing nodes of Ranvier. The new mouse model presented here opens new possibilities to explore the organization and development of the oligodendrocyte network with single-cell resolution.
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Affiliation(s)
- Laura Dumas
- INSERM, UMRS_U968, Institut de la Vision, Paris, F-75012, France; Sorbonne Universités, UPMC Univ Paris 06, Institut de la Vision, Paris, F-75012, France; CNRS, UMR_7210, Paris, F-75012, France
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21
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Abstract
The zebrafish is a premier vertebrate model system that offers many experimental advantages for in vivo imaging and genetic studies. This review provides an overview of glial cell types in the central and peripheral nervous system of zebrafish. We highlight some recent work that exploited the strengths of the zebrafish system to increase the understanding of the role of Gpr126 in Schwann cell myelination and illuminate the mechanisms controlling oligodendrocyte development and myelination. We also summarize similarities and differences between zebrafish radial glia and mammalian astrocytes and consider the possibility that their distinct characteristics may represent extremes in a continuum of cell identity. Finally, we focus on the emergence of zebrafish as a model for elucidating the development and function of microglia. These recent studies have highlighted the power of the zebrafish system for analyzing important aspects of glial development and function.
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Affiliation(s)
- David A Lyons
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, United Kingdom
| | - William S Talbot
- Department of Developmental Biology, Stanford University, Stanford, California 94305
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22
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Preston MA, Macklin WB. Zebrafish as a model to investigate CNS myelination. Glia 2014; 63:177-93. [PMID: 25263121 DOI: 10.1002/glia.22755] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/12/2014] [Indexed: 12/18/2022]
Abstract
Myelin plays a critical role in proper neuronal function by providing trophic and metabolic support to axons and facilitating energy-efficient saltatory conduction. Myelination is influenced by numerous molecules including growth factors, hormones, transmembrane receptors and extracellular molecules, which activate signaling cascades that drive cellular maturation. Key signaling molecules and downstream signaling cascades controlling myelination have been identified in cell culture systems. However, in vitro systems are not able to faithfully replicate the complex in vivo signaling environment that occurs during development or following injury. Currently, it remains time-consuming and expensive to investigate myelination in vivo in rodents, the most widely used model for studying mammalian myelination. As such, there is a need for alternative in vivo myelination models, particularly ones that can test molecular mechanisms without removing oligodendrocyte lineage cells from their native signaling environment or disrupting intercellular interactions with other cell types present during myelination. Here, we review the ever-increasing role of zebrafish in studies uncovering novel mechanisms controlling vertebrate myelination. These innovative studies range from observations of the behavior of single cells during in vivo myelination as well as mutagenesis- and pharmacology-based screens in whole animals. Additionally, we discuss recent efforts to develop novel models of demyelination and oligodendrocyte cell death in adult zebrafish for the study of cellular behavior in real time during repair and regeneration of damaged nervous systems.
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Affiliation(s)
- Marnie A Preston
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, Colorado
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23
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Kolosov D, Bui P, Chasiotis H, Kelly SP. Claudins in teleost fishes. Tissue Barriers 2013; 1:e25391. [PMID: 24665402 PMCID: PMC3875606 DOI: 10.4161/tisb.25391] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/09/2013] [Indexed: 12/26/2022] Open
Abstract
Teleost fishes are a large and diverse animal group that represent close to 50% of all described vertebrate species. This review consolidates what is known about the claudin (Cldn) family of tight junction (TJ) proteins in teleosts. Cldns are transmembrane proteins of the vertebrate epithelial/endothelial TJ complex that largely determine TJ permeability. Cldns achieve this by expressing barrier or pore forming properties and by exhibiting distinct tissue distribution patterns. So far, ~63 genes encoding for Cldn TJ proteins have been reported in 16 teleost species. Collectively, cldns (or Cldns) are found in a broad array of teleost fish tissues, but select genes exhibit restricted expression patterns. Evidence to date strongly supports the view that Cldns play a vital role in the embryonic development of teleost fishes and in the physiology of tissues and organ systems studied thus far.
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Affiliation(s)
- Dennis Kolosov
- Department of Biology; York University; Toronto, ON, Canada
| | - Phuong Bui
- Department of Biology; York University; Toronto, ON, Canada
| | | | - Scott P Kelly
- Department of Biology; York University; Toronto, ON, Canada
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24
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Moore AC, Mark TE, Hogan AK, Topczewski J, LeClair EE. Peripheral axons of the adult zebrafish maxillary barbel extensively remyelinate during sensory appendage regeneration. J Comp Neurol 2013; 520:4184-203. [PMID: 22592645 DOI: 10.1002/cne.23147] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Myelination is a cellular adaptation allowing rapid conduction along axons. We have investigated peripheral axons of the zebrafish maxillary barbel (ZMB), an optically clear sensory appendage. Each barbel carries taste buds, solitary chemosensory cells, and epithelial nerve endings, all of which regenerate after amputation (LeClair and Topczewski [2010] PLoS One 5:e8737). The ZMB contains axons from the facial nerve; however, myelination within the barbel itself has not been established. Transcripts of myelin basic protein (mbp) are expressed in normal and regenerating adult barbels, indicating activity in both maintenance and repair. Myelin was confirmed in situ by using toluidine blue, an anti-MBP antibody, and transmission electron microscopy (TEM). The adult ZMB contains ∼180 small-diameter axons (<2 μm), approximately 60% of which are myelinated. Developmental myelination was observed via whole-mount immunohistochemistry 4-6 weeks postfertilization, showing myelin sheaths lagging behind growing axons. Early-regenerating axons (10 days postsurgery), having no or few myelin layers, were disorganized within a fibroblast-rich collagenous scar. Twenty-eight days postsurgery, barbel axons had grown out several millimeters and were organized with compact myelin sheaths. Fiber types and axon areas were similar between normal and regenerated tissue; within 4 weeks, regenerating axons restored ∼85% of normal myelin thickness. Regenerating barbels express multiple promyelinating transcription factors (sox10, oct6 = pou3f1; krox20a/b = egr2a/b) typical of Schwann cells. These observations extend our understanding of the zebrafish peripheral nervous system within a little-studied sensory appendage. The accessible ZMB provides a novel context for studying axon regeneration, Schwann cell migration, and remyelination in a model vertebrate.
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Affiliation(s)
- Alex C Moore
- Department of Biological Sciences, DePaul University, Chicago, Illinois 60614, USA
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25
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Vatine GD, Zada D, Lerer-Goldshtein T, Tovin A, Malkinson G, Yaniv K, Appelbaum L. Zebrafish as a model for monocarboxyl transporter 8-deficiency. J Biol Chem 2012; 288:169-80. [PMID: 23161551 DOI: 10.1074/jbc.m112.413831] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Allan-Herndon-Dudley syndrome (AHDS) is a severe psychomotor retardation characterized by neurological impairment and abnormal thyroid hormone (TH) levels. Mutations in the TH transporter, monocarboxylate transporter 8 (MCT8), are associated with AHDS. MCT8 knock-out mice exhibit impaired TH levels; however, they lack neurological defects. Here, the zebrafish mct8 gene and promoter were isolated, and mct8 promoter-driven transgenic lines were used to show that, similar to humans, mct8 is primarily expressed in the nervous and vascular systems. Morpholino-based knockdown and rescue experiments revealed that MCT8 is strictly required for neural development in the brain and spinal cord. This study shows that MCT8 is a crucial regulator during embryonic development and establishes the first vertebrate model for MCT8 deficiency that exhibits a neurological phenotype.
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Affiliation(s)
- Gad David Vatine
- Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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Antagonistic regulation of PAF1C and p-TEFb is required for oligodendrocyte differentiation. J Neurosci 2012; 32:8201-7. [PMID: 22699901 DOI: 10.1523/jneurosci.5344-11.2012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Oligodendrocytes are myelinating glial cells in the CNS and are essential for proper neuronal function. During development, oligodendrocyte progenitor cells (OPCs) are specified from the motor neuron precursor domain of the ventral spinal cord and differentiate into myelinating oligodendrocytes after migration to the white matter of the neural tube. Cell cycle control of OPCs influences the balance between immature OPCs and myelinating oligodendrocytes, but the precise mechanism regulating the differentiation of OPCs into myelinating oligodendrocytes is unclear. To understand the mechanisms underlying oligodendrocyte differentiation, an N-ethyl-N-nitrosourea-based mutagenesis screen was performed and a zebrafish leo1 mutant, dalmuri (dal(knu6)) was identified in the current study. Leo1 is a component of the evolutionarily conserved RNA polymerase II-associated factor 1 complex (PAF1C), which is a positive regulator of transcription elongation. The dal(knu6) mutant embryos specified motor neurons and OPCs normally, and at the appropriate time, but OPCs subsequently failed to differentiate into myelinating oligodendrocytes and were eliminated by apoptosis. A loss-of-function study of cdc73, another member of PAF1C, showed the same phenotype in the CNS, indicating that PAF1C function is required for oligodendrocyte differentiation. Interestingly, inhibition of positive transcription elongation factor b (p-TEFb), rescued downregulated gene expression and impaired oligodendrocyte differentiation in the dal(knu6) mutant and Cdc73-deficient embryos. Together, these results indicate that antagonistic regulation of gene expression by PAF1C and p-TEFb plays a crucial role in oligodendrocyte development in the CNS.
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27
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Avraham-Davidi I, Ely Y, Pham VN, Castranova D, Grunspan M, Malkinson G, Gibbs-Bar L, Mayseless O, Allmog G, Lo B, Warren CM, Chen TT, Ungos J, Kidd K, Shaw K, Rogachev I, Wan W, Murphy PM, Farber SA, Carmel L, Shelness GS, Iruela-Arispe ML, Weinstein BM, Yaniv K. ApoB-containing lipoproteins regulate angiogenesis by modulating expression of VEGF receptor 1. Nat Med 2012; 18:967-73. [PMID: 22581286 DOI: 10.1038/nm.2759] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 04/02/2012] [Indexed: 12/15/2022]
Abstract
Despite the clear major contribution of hyperlipidemia to the prevalence of cardiovascular disease in the developed world, the direct effects of lipoproteins on endothelial cells have remained obscure and are under debate. Here we report a previously uncharacterized mechanism of vessel growth modulation by lipoprotein availability. Using a genetic screen for vascular defects in zebrafish, we initially identified a mutation, stalactite (stl), in the gene encoding microsomal triglyceride transfer protein (mtp), which is involved in the biosynthesis of apolipoprotein B (ApoB)-containing lipoproteins. By manipulating lipoprotein concentrations in zebrafish, we found that ApoB negatively regulates angiogenesis and that it is the ApoB protein particle, rather than lipid moieties within ApoB-containing lipoproteins, that is primarily responsible for this effect. Mechanistically, we identified downregulation of vascular endothelial growth factor receptor 1 (VEGFR1), which acts as a decoy receptor for VEGF, as a key mediator of the endothelial response to lipoproteins, and we observed VEGFR1 downregulation in hyperlipidemic mice. These findings may open new avenues for the treatment of lipoprotein-related vascular disorders.
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Affiliation(s)
- Inbal Avraham-Davidi
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
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28
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Yuelling LW, Waggener CT, Afshari FS, Lister JA, Fuss B. Autotaxin/ENPP2 regulates oligodendrocyte differentiation in vivo in the developing zebrafish hindbrain. Glia 2012; 60:1605-18. [PMID: 22821873 DOI: 10.1002/glia.22381] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 06/05/2012] [Indexed: 01/12/2023]
Abstract
During development, progenitors that are committed to differentiate into oligodendrocytes, the myelinating cells of the central nervous system (CNS), are generated within discrete regions of the neuroepithelium. More specifically, within the developing spinal cord and hindbrain ventrally located progenitor cells that are characterized by the expression of the transcription factor olig2 give temporally rise to first motor neurons and then oligodendrocyte progenitors. The regulation of this temporal neuron-glial switch has been found complex and little is known about the extrinsic factors regulating it. Our studies described here identified a zebrafish ortholog to mammalian atx, which displays evolutionarily conserved expression pattern characteristics. Most interestingly, atx was found to be expressed by cells of the cephalic floor plate during a time period when ventrally-derived oligodendrocyte progenitors arise in the developing hindbrain of the zebrafish. Knock-down of atx expression resulted in a delay and/or inhibition of the timely appearance of oligodendrocyte progenitors and subsequent developmental stages of the oligodendrocyte lineage. This effect of atx knock-down was not accompanied by changes in the number of olig2-positive progenitor cells, the overall morphology of the axonal network or the number of somatic abducens motor neurons. Thus, our studies identified Atx as an extrinsic factor that is likely secreted by cells from the floor plate and that is involved in regulating specifically the progression of olig2-positive progenitor cells into lineage committed oligodendrocyte progenitors.
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Affiliation(s)
- Larra W Yuelling
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, USA
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29
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Münzel EJ, Schaefer K, Obirei B, Kremmer E, Burton EA, Kuscha V, Becker CG, Brösamle C, Williams A, Becker T. Claudin k is specifically expressed in cells that form myelin during development of the nervous system and regeneration of the optic nerve in adult zebrafish. Glia 2011; 60:253-70. [PMID: 22020875 DOI: 10.1002/glia.21260] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Accepted: 10/05/2011] [Indexed: 01/07/2023]
Abstract
The zebrafish has become an important model organism to study myelination during development and after a lesion of the adult central nervous system (CNS). Here, we identify Claudin k as a myelin-associated protein in zebrafish and determine its localization during development and adult optic nerve regeneration. We find Claudin k in subcellular compartments consistent with location in autotypic tight junctions of oligodendrocytes and myelinating Schwann cells. Expression starts in the hindbrain at 2 days (mRNA) and 3 days (protein) postfertilization and is maintained in adults. A newly generated claudin k:green fluorescent protein (GFP) reporter line allowed us to characterize oligodendrocytes in the adult retina that express Claudin k and olig2, but not P0 and uniquely only form loose wraps of membrane around axons. After a crush of the adult optic nerve, Claudin k protein levels were first reduced and then recovered within 4 weeks postlesion, concomitant with optic nerve myelin de- and regeneration. During optic nerve regeneration, oligodendrocytes, many of which were newly generated, repopulated the lesion site and exhibited increasing morphological complexity over time. Thus, Claudin k is a novel myelin-associated protein expressed by oligodendrocytes and Schwann cells from early stages of wrapping and myelin formation in zebrafish development and adult regeneration, suggesting important functions of the gene for myelin formation and maintenance. Our Claudin k antibodies and claudin k:GFP reporter line represent excellent ways to visualize oligodendrocyte and Schwann cell differentiation in vivo.
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Affiliation(s)
- Eva Jolanda Münzel
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Almeida RG, Czopka T, Ffrench-Constant C, Lyons DA. Individual axons regulate the myelinating potential of single oligodendrocytes in vivo. Development 2011; 138:4443-50. [PMID: 21880787 DOI: 10.1242/dev.071001] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The majority of axons in the central nervous system (CNS) are eventually myelinated by oligodendrocytes, but whether the timing and extent of myelination in vivo reflect intrinsic properties of oligodendrocytes, or are regulated by axons, remains undetermined. Here, we use zebrafish to study CNS myelination at single-cell resolution in vivo. We show that the large caliber Mauthner axon is the first to be myelinated (shortly before axons of smaller caliber) and that the presence of supernumerary large caliber Mauthner axons can profoundly affect myelination by single oligodendrocytes. Oligodendrocytes that typically myelinate just one Mauthner axon in wild type can myelinate multiple supernumerary Mauthner axons. Furthermore, oligodendrocytes that exclusively myelinate numerous smaller caliber axons in wild type can readily myelinate small caliber axons in addition to the much larger caliber supernumerary Mauthner axons. These data indicate that single oligodendrocytes can myelinate diverse axons and that their myelinating potential is actively regulated by individual axons.
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Affiliation(s)
- Rafael G Almeida
- Centre for Neuroregeneration, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, UK
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Takada N, Appel B. swap70 promotes neural precursor cell cycle exit and oligodendrocyte formation. Mol Cell Neurosci 2011; 48:225-35. [PMID: 21875669 DOI: 10.1016/j.mcn.2011.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 07/06/2011] [Accepted: 08/05/2011] [Indexed: 10/17/2022] Open
Abstract
Multipotent neural precursors produce oligodendrocyte lineage cells, which then migrate throughout the central nervous system and extend multiple, long membrane processes to wrap and myelinate axons. These dynamic cellular behaviors imply dynamic regulation of the cytoskeleton. In a previous microarray screen for new oligodendrocyte genes we identified swap70, which encodes a protein with domains that predict numerous signaling activities. Because mouse Swap70 can promote cell motility by functioning as a guanine nucleotide exchange factor for Rac1, we hypothesized that zebrafish Swap70 promotes oligodendrocyte progenitor cell (OPC) motility and axon wrapping. To test this we investigated Swap70 localization in OPCs and differentiating oligodendrocytes and we performed a series of gain and loss of function experiments. Our tests of gene function did not provide evidence that Swap70 regulates oligodendrocyte lineage cell behavior. Instead, we found that swap70 deficient larvae had excess neural precursors and a deficit of OPCs. Cells associated with neural proliferative zones express swap70. Therefore, our data reveal a potential new role for Swap70 in regulating transition of dividing neural precursors to specified OPCs.
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Affiliation(s)
- Norio Takada
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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32
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Abstract
The myelin sheath is an essential component of the vertebrate nervous system, and its disruption causes numerous diseases, including multiple sclerosis (MS), and neurodegeneration. Although we understand a great deal about the early development of the glial cells that make myelin (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system), we know much less about the cellular and molecular mechanisms that regulate the later stages of differentiation that orchestrate myelin formation. Over the past decade, the zebrafish has been employed as a model with which to dissect the development of myelinated axons. Forward genetic screens have revealed new genes essential for myelination, as well as new roles for genes previously implicated in myelinated axon formation in other systems. High-resolution in vivo imaging in zebrafish has also begun to illuminate novel cell behaviors during myelinating glial cell development. Here we review the contribution of zebrafish research to our understanding of myelinated axon formation to date. We also describe and discuss many of the methodologies used in these studies and preview future endeavors that will ensure that the zebrafish remains at the cutting edge of this important area of research.
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Affiliation(s)
- Tim Czopka
- Centre for Neuroregeneration, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, UK
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