1
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Karas BF, Terez KR, Mowla S, Battula N, Flannery KP, Gural BM, Aboussleman G, Mubin N, Manzini MC. Removal of pomt1 in zebrafish leads to loss of α-dystroglycan glycosylation and dystroglycanopathy phenotypes. Hum Mol Genet 2024; 33:709-723. [PMID: 38272461 PMCID: PMC11000664 DOI: 10.1093/hmg/ddae006] [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: 07/11/2023] [Revised: 11/28/2023] [Accepted: 12/22/2023] [Indexed: 01/27/2024] Open
Abstract
Biallelic mutations in Protein O-mannosyltransferase 1 (POMT1) are among the most common causes of a severe group of congenital muscular dystrophies (CMDs) known as dystroglycanopathies. POMT1 is a glycosyltransferase responsible for the attachment of a functional glycan mediating interactions between the transmembrane glycoprotein dystroglycan and its binding partners in the extracellular matrix (ECM). Disruptions in these cell-ECM interactions lead to multiple developmental defects causing brain and eye malformations in addition to CMD. Removing Pomt1 in the mouse leads to early embryonic death due to the essential role of dystroglycan during placental formation in rodents. Here, we characterized and validated a model of pomt1 loss of function in the zebrafish showing that developmental defects found in individuals affected by dystroglycanopathies can be recapitulated in the fish. We also discovered that pomt1 mRNA provided by the mother in the oocyte supports dystroglycan glycosylation during the first few weeks of development. Muscle disease, retinal synapse formation deficits, and axon guidance defects can only be uncovered during the first week post fertilization by generating knock-out embryos from knock-out mothers. Conversely, maternal pomt1 from heterozygous mothers was sufficient to sustain muscle, eye, and brain development only leading to loss of photoreceptor synapses at 30 days post fertilization. Our findings show that it is important to define the contribution of maternal mRNA while developing zebrafish models of dystroglycanopathies and that offspring generated from heterozygous and knock-out mothers can be used to differentiate the role of dystroglycan glycosylation in tissue formation and maintenance.
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Affiliation(s)
- Brittany F Karas
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Kristin R Terez
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Shorbon Mowla
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Namarata Battula
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Kyle P Flannery
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Brian M Gural
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Grace Aboussleman
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - Numa Mubin
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
| | - M Chiara Manzini
- Department of Neuroscience and Cell Biology, Child Health Institute of New Jersey, Rutgers University-Robert Wood Johnson Medical School, 89 French Street, New Brunswick, NJ 08901, United States
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2
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Melrose J. Hippo cell signaling and HS-proteoglycans regulate tissue form and function, age-dependent maturation, extracellular matrix remodeling, and repair. Am J Physiol Cell Physiol 2024; 326:C810-C828. [PMID: 38223931 DOI: 10.1152/ajpcell.00683.2023] [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: 12/11/2023] [Revised: 01/09/2024] [Accepted: 01/09/2024] [Indexed: 01/16/2024]
Abstract
This review examined how Hippo cell signaling and heparan sulfate (HS)-proteoglycans (HSPGs) regulate tissue form and function. Despite being a nonweight-bearing tissue, the brain is regulated by Hippo mechanoresponsive cell signaling pathways during embryonic development. HS-proteoglycans interact with growth factors, morphogens, and extracellular matrix components to regulate development and pathology. Pikachurin and Eyes shut (Eys) interact with dystroglycan to stabilize the photoreceptor axoneme primary cilium and ribbon synapse facilitating phototransduction and neurotransduction with bipolar retinal neuronal networks in ocular vision, the primary human sense. Another HSPG, Neurexin interacts with structural and adaptor proteins to stabilize synapses and ensure specificity of neural interactions, and aids in synaptic potentiation and plasticity in neurotransduction. HSPGs also stabilize the blood-brain barrier and motor neuron basal structures in the neuromuscular junction. Agrin and perlecan localize acetylcholinesterase and its receptors in the neuromuscular junction essential for neuromuscular control. The primary cilium is a mechanosensory hub on neurons, utilized by YES associated protein (YAP)-transcriptional coactivator with PDZ-binding motif (TAZ) Hippo, Hh, Wnt, transforming growth factor (TGF)-β/bone matrix protein (BMP) receptor tyrosine kinase cell signaling. Members of the glypican HSPG proteoglycan family interact with Smoothened and Patched G-protein coupled receptors on the cilium to regulate Hh and Wnt signaling during neuronal development. Control of glycosyl sulfotransferases and endogenous protease expression by Hippo TAZ YAP represents a mechanism whereby the fine structure of HS-proteoglycans can be potentially modulated spatiotemporally to regulate tissue morphogenesis in a similar manner to how Hippo signaling controls sialyltransferase expression and mediation of cell-cell recognition, dysfunctional sialic acid expression is a feature of many tumors.
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Affiliation(s)
- James Melrose
- Raymond Purves Laboratory, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney, Northern Sydney Local Health District, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
- Sydney Medical School-Northern, University of Sydney at Royal North Shore Hospital, St. Leonards, New South Wales, Australia
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, New South Wales, Australia
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3
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Reinhard J, Mueller-Buehl C, Wiemann S, Roll L, Luft V, Shabani H, Rathbun DL, Gan L, Kuo CC, Franzen J, Joachim SC, Faissner A. Neural extracellular matrix regulates visual sensory motor integration. iScience 2024; 27:108846. [PMID: 38318351 PMCID: PMC10839651 DOI: 10.1016/j.isci.2024.108846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/12/2023] [Accepted: 01/03/2024] [Indexed: 02/07/2024] Open
Abstract
Visual processing depends on sensitive and balanced synaptic neurotransmission. Extracellular matrix proteins in the environment of cells are key modulators in synaptogenesis and synaptic plasticity. In the present study, we provide evidence that the combined loss of the four extracellular matrix components, brevican, neurocan, tenascin-C, and tenascin-R, in quadruple knockout mice leads to severe retinal dysfunction and diminished visual motion processing in vivo. Remarkably, impaired visual motion processing was accompanied by a developmental loss of cholinergic direction-selective starburst amacrine cells. Additionally, we noted imbalance of inhibitory and excitatory synaptic signaling in the quadruple knockout retina. Collectively, the study offers insights into the functional importance of four key extracellular matrix proteins for retinal function, visual motion processing, and synaptic signaling.
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Affiliation(s)
- Jacqueline Reinhard
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Cornelius Mueller-Buehl
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Susanne Wiemann
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Lars Roll
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Veronika Luft
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Hamed Shabani
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard-Karls-University Tuebingen, 72076 Tuebingen, Germany
| | - Daniel L. Rathbun
- Institute for Ophthalmic Research, Centre for Ophthalmology, Eberhard-Karls-University Tuebingen, 72076 Tuebingen, Germany
| | - Lin Gan
- Interdisciplinary Centre for Clinical Research Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Chao-Chung Kuo
- Interdisciplinary Centre for Clinical Research Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Julia Franzen
- Interdisciplinary Centre for Clinical Research Aachen, RWTH Aachen University, 52074 Aachen, Germany
| | - Stephanie C. Joachim
- Experimental Eye Research Institute, University Eye Hospital, Ruhr University Bochum, 44892 Bochum, Germany
| | - Andreas Faissner
- Department of Cell Morphology and Molecular Neurobiology, Faculty of Biology and Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
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4
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Zhang L, Liu W, Wang HY, Qiang W, Wang R, Cui ZL, Zhang ZM. The temporal progression of retinal degeneration and early-stage idebenone treatment in the Pde6b rd1/rd1 mouse model of retinal dystrophy. Sci Rep 2024; 14:2019. [PMID: 38263197 PMCID: PMC10805728 DOI: 10.1038/s41598-024-52391-y] [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: 10/24/2023] [Accepted: 01/18/2024] [Indexed: 01/25/2024] Open
Abstract
Photoreceptor cell death, primarily through apoptosis, related to retinal disorders like retinitis pigmentosa (RP), would result in vision loss. The pathological processes and crucial mutant conditions preceding photoreceptor cell demise are not well understood. This study aims to conduct an in-depth examination of early-stage changes in the widely utilized Pde6brd1/rd1 (rd1) mouse model, which has Pde6b gene mutations representing autosomal recessive RP disorder. We investigated the morphology and ultrastructure of retinal cells, including second-order neurons, during the initial phase of disease progression. Our findings revealed that mitochondrial alterations in rod photoreceptors were present as a predeath mutant state as early as postnatal day 3 (P3). The bipolar and horizontal cells from the rd1 mouse retina exhibited significant morphological changes in response to loss of photoreceptor cells, indicating that second-order neurons rely on these cells for their structures. Subsequent oral administration of idebenone, a mitochondria-protective agent, enhanced retinal function and promoted both photoreceptor cell survival and inner retinal second-order synaptogenesis in rd1 mice at P14. Our findings offer a mechanistic framework, suggesting that mitochondrial damage acts as an early driver for photoreceptor cell death in retinal degeneration.
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Affiliation(s)
- Lei Zhang
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
- Xi'an Key Laboratory of Digital Medical Technology of Ophthalmologic Imaging, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
| | - Wei Liu
- Medical Experiment Center, Shaanxi University of Chinese Medicine, Xianyang, Shaanxi Province, China
| | - Hai-Yan Wang
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China.
- Xi'an Key Laboratory of Digital Medical Technology of Ophthalmologic Imaging, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China.
| | - Wei Qiang
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
- Xi'an Key Laboratory of Digital Medical Technology of Ophthalmologic Imaging, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
| | - Ru Wang
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
- Xi'an Key Laboratory of Digital Medical Technology of Ophthalmologic Imaging, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
| | - Zhi-Li Cui
- Shaanxi Eye Hospital, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
- Xi'an Key Laboratory of Digital Medical Technology of Ophthalmologic Imaging, Xi'an People's Hospital (Xi'an Fourth Hospital), Xi'an, 710004, China
| | - Zuo-Ming Zhang
- Department of Clinical Medicine, Faculty of Aerospace Medicine, Air Force Medical University, Xi'an, 710032, Shaanxi Province, China.
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5
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Jahncke JN, Miller DS, Krush M, Schnell E, Wright KM. Inhibitory CCK+ basket synapse defects in mouse models of dystroglycanopathy. eLife 2024; 12:RP87965. [PMID: 38179984 PMCID: PMC10942650 DOI: 10.7554/elife.87965] [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] [Indexed: 01/06/2024] Open
Abstract
Dystroglycan (Dag1) is a transmembrane glycoprotein that links the extracellular matrix to the actin cytoskeleton. Mutations in Dag1 or the genes required for its glycosylation result in dystroglycanopathy, a type of congenital muscular dystrophy characterized by a wide range of phenotypes including muscle weakness, brain defects, and cognitive impairment. We investigated interneuron (IN) development, synaptic function, and associated seizure susceptibility in multiple mouse models that reflect the wide phenotypic range of dystroglycanopathy neuropathology. Mice that model severe dystroglycanopathy due to forebrain deletion of Dag1 or Pomt2, which is required for Dystroglycan glycosylation, show significant impairment of CCK+/CB1R+ IN development. CCK+/CB1R+ IN axons failed to properly target the somatodendritic compartment of pyramidal neurons in the hippocampus, resulting in synaptic defects and increased seizure susceptibility. Mice lacking the intracellular domain of Dystroglycan have milder defects in CCK+/CB1R+ IN axon targeting, but exhibit dramatic changes in inhibitory synaptic function, indicating a critical postsynaptic role of this domain. In contrast, CCK+/CB1R+ IN synaptic function and seizure susceptibility was normal in mice that model mild dystroglycanopathy due to partially reduced Dystroglycan glycosylation. Collectively, these data show that inhibitory synaptic defects and elevated seizure susceptibility are hallmarks of severe dystroglycanopathy, and show that Dystroglycan plays an important role in organizing functional inhibitory synapse assembly.
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Affiliation(s)
- Jennifer N Jahncke
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Daniel S Miller
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Milana Krush
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Eric Schnell
- Operative Care Division, Portland VA Health Care SystemPortlandUnited States
- Anesthesiology and Perioperative Medicine, Oregon Health & Science UniversityPortlandUnited States
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
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6
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Sciandra F, Bozzi M, Bigotti MG. From adhesion complex to signaling hub: the dual role of dystroglycan. Front Mol Biosci 2023; 10:1325284. [PMID: 38155958 PMCID: PMC10752950 DOI: 10.3389/fmolb.2023.1325284] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 11/27/2023] [Indexed: 12/30/2023] Open
Abstract
Dystroglycan (DG) is a transmembrane protein widely expressed in multiple cells and tissues. It is formed by two subunits, α- and β-DG, and represents a molecular bridge between the outside and the inside of the cell, which is essential for the mechanical and structural stability of the plasma membrane. The α-subunit is a cell-surface protein that binds to the extracellular matrix (ECM) and is tightly associated with the plasma membrane via a non-covalent interaction with the β-subunit, which, in turn, is a transmembrane protein that binds to the cytoskeletal actin. DG is a versatile molecule acting not only as a mechanical building block but also as a modulator of outside-inside signaling events. The cytoplasmic domain of β-DG interacts with different adaptor and cytoskeletal proteins that function as molecular switches for the transmission of ECM signals inside the cells. These interactions can modulate the involvement of DG in different biological processes, ranging from cell growth and survival to differentiation and proliferation/regeneration. Although the molecular events that characterize signaling through the ECM-DG-cytoskeleton axis are still largely unknown, in recent years, a growing list of evidence has started to fill the gaps in our understanding of the role of DG in signal transduction. This mini-review represents an update of recent developments, uncovering the dual role of DG as an adhesion and signaling molecule that might inspire new ideas for the design of novel therapeutic strategies for pathologies such as muscular dystrophy, cardiomyopathy, and cancer, where the DG signaling hub plays important roles.
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Affiliation(s)
- Francesca Sciandra
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”-SCITEC (CNR), Roma, Italy
| | - Manuela Bozzi
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”-SCITEC (CNR), Roma, Italy
- Dipartimento di Scienze Biotecnologiche di Base, Cliniche Intensivologiche e Perioperatorie, Sezione di Biochimica, Università Cattolica del Sacro Cuore di Roma, Roma, Italy
| | - Maria Giulia Bigotti
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
- Bristol Heart Institute, Research Floor Level 7, Bristol Royal Infirmary, Bristol, United Kingdom
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7
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Farrugia BL, Melrose J. The Glycosaminoglycan Side Chains and Modular Core Proteins of Heparan Sulphate Proteoglycans and the Varied Ways They Provide Tissue Protection by Regulating Physiological Processes and Cellular Behaviour. Int J Mol Sci 2023; 24:14101. [PMID: 37762403 PMCID: PMC10531531 DOI: 10.3390/ijms241814101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/03/2023] [Accepted: 09/05/2023] [Indexed: 09/29/2023] Open
Abstract
This review examines the roles of HS-proteoglycans (HS-PGs) in general, and, in particular, perlecan and syndecan as representative examples and their interactive ligands, which regulate physiological processes and cellular behavior in health and disease. HS-PGs are essential for the functional properties of tissues both in development and in the extracellular matrix (ECM) remodeling that occurs in response to trauma or disease. HS-PGs interact with a biodiverse range of chemokines, chemokine receptors, protease inhibitors, and growth factors in immune regulation, inflammation, ECM stabilization, and tissue protection. Some cell regulatory proteoglycan receptors are dually modified hybrid HS/CS proteoglycans (betaglycan, CD47). Neurexins provide synaptic stabilization, plasticity, and specificity of interaction, promoting neurotransduction, neurogenesis, and differentiation. Ternary complexes of glypican-1 and Robbo-Slit neuroregulatory proteins direct axonogenesis and neural network formation. Specific neurexin-neuroligin complexes stabilize synaptic interactions and neural activity. Disruption in these interactions leads to neurological deficits in disorders of functional cognitive decline. Interactions with HS-PGs also promote or inhibit tumor development. Thus, HS-PGs have complex and diverse regulatory roles in the physiological processes that regulate cellular behavior and the functional properties of normal and pathological tissues. Specialized HS-PGs, such as the neurexins, pikachurin, and Eyes-shut, provide synaptic stabilization and specificity of neural transduction and also stabilize the axenome primary cilium of phototoreceptors and ribbon synapse interactions with bipolar neurons of retinal neural networks, which are essential in ocular vision. Pikachurin and Eyes-Shut interactions with an α-dystroglycan stabilize the photoreceptor synapse. Novel regulatory roles for HS-PGs controlling cell behavior and tissue function are expected to continue to be uncovered in this fascinating class of proteoglycan.
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Affiliation(s)
- Brooke L. Farrugia
- Department of Biomedical Engineering, Faculty of Engineering and Information Technology, University of Melbourne, Melbourne, VIC 3010, Australia;
| | - James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia
- Raymond Purves Laboratory of Bone and Joint Research, Kolling Institute of Medical Research, Northern Sydney Local Health District, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
- Sydney Medical School (Northern), University of Sydney at Royal North Shore Hospital, St. Leonards, NSW 2065, Australia
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8
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Patil DN, Pantalone S, Cao Y, Laboute T, Novick SJ, Singh S, Savino S, Faravelli S, Magnani F, Griffin PR, Singh AK, Forneris F, Martemyanov KA. Structure of the photoreceptor synaptic assembly of the extracellular matrix protein pikachurin with the orphan receptor GPR179. Sci Signal 2023; 16:eadd9539. [PMID: 37490546 PMCID: PMC10561654 DOI: 10.1126/scisignal.add9539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 07/06/2023] [Indexed: 07/27/2023]
Abstract
Precise synapse formation is essential for normal functioning of the nervous system. Retinal photoreceptors establish selective contacts with bipolar cells, aligning the neurotransmitter release apparatus with postsynaptic signaling cascades. This involves transsynaptic assembly between the dystroglycan-dystrophin complex on the photoreceptor and the orphan receptor GPR179 on the bipolar cell, which is mediated by the extracellular matrix protein pikachurin (also known as EGFLAM). This complex plays a critical role in the synaptic organization of photoreceptors and signal transmission, and mutations affecting its components cause blinding disorders in humans. Here, we investigated the structural organization and molecular mechanisms by which pikachurin orchestrates transsynaptic assembly and solved structures of the human pikachurin domains by x-ray crystallography and of the GPR179-pikachurin complex by single-particle, cryo-electron microscopy. The structures reveal molecular recognition principles of pikachurin by the Cache domains of GPR179 and show how the interaction is involved in the transsynaptic alignment of the signaling machinery. Together, these data provide a structural basis for understanding the synaptic organization of photoreceptors and ocular pathology.
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Affiliation(s)
- Dipak N. Patil
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Serena Pantalone
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Yan Cao
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Thibaut Laboute
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Scott J. Novick
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Shikha Singh
- Department of Biological Sciences, Columbia University New York, NY 10027, USA
| | - Simone Savino
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Silvia Faravelli
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Francesca Magnani
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
| | - Patrick R. Griffin
- Department of Molecular Medicine, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
| | - Appu K. Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
- Mehta Family Centre for Engineering in Medicine, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Federico Forneris
- The Armenise-Harvard Laboratory of Structural Biology, Department of Biology and Biotechnology, University of Pavia, Via Ferrata, 9A, I-27100 Pavia, Italy
- Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Kirill A. Martemyanov
- Department of Neuroscience, The Herbert Wertheim UF Scripps Institute for Biomedical Innovation & Technology, University of Florida, Jupiter, FL 33458, USA
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9
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Cehajic-Kapetanovic J, Singh MS, Zrenner E, MacLaren RE. Bioengineering strategies for restoring vision. Nat Biomed Eng 2023; 7:387-404. [PMID: 35102278 DOI: 10.1038/s41551-021-00836-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
Late-stage retinal degenerative disease involving photoreceptor loss can be treated by optogenetic therapy, cell transplantation and retinal prostheses. These approaches aim to restore light sensitivity to the retina as well as visual perception by integrating neuronal responses for transmission to the cortex. In age-related macular degeneration, some cell-based therapies also aim to restore photoreceptor-supporting tissue to prevent complete photoreceptor loss. In the earlier stages of degeneration, gene-replacement therapy could attenuate retinal-disease progression and reverse loss of function. And gene-editing strategies aim to correct the underlying genetic defects. In this Review, we highlight the most promising gene therapies, cell therapies and retinal prostheses for the treatment of retinal disease, discuss the benefits and drawbacks of each treatment strategy and the factors influencing whether functional tissue is reconstructed and repaired or replaced with an electronic device, and summarize upcoming technologies for enhancing the restoration of vision.
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Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK.
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
| | | | - Eberhart Zrenner
- Institute for Ophthalmic Research, Center for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
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10
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Frederick CE, Zenisek D. Ribbon Synapses and Retinal Disease: Review. Int J Mol Sci 2023; 24:5090. [PMID: 36982165 PMCID: PMC10049380 DOI: 10.3390/ijms24065090] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 02/27/2023] [Accepted: 03/01/2023] [Indexed: 03/30/2023] Open
Abstract
Synaptic ribbons are presynaptic protein complexes that are believed to be important for the transmission of sensory information in the visual system. Ribbons are selectively associated with those synapses where graded changes in membrane potential drive continuous neurotransmitter release. Defective synaptic transmission can arise as a result of the mutagenesis of a single ribbon component. Visual diseases that stem from malfunctions in the presynaptic molecular machinery of ribbon synapses in the retina are rare. In this review, we provide an overview of synaptopathies that give rise to retinal malfunction and our present understanding of the mechanisms that underlie their pathogenesis and discuss muscular dystrophies that exhibit ribbon synapse involvement in the pathology.
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Affiliation(s)
| | - David Zenisek
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, 333 Cedar Street, P.O. Box 208026, New Haven, CT 06510, USA
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11
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Navarro-Calvo J, Esquiva G, Gómez-Vicente V, Valor LM. MicroRNAs in the Mouse Developing Retina. Int J Mol Sci 2023; 24:ijms24032992. [PMID: 36769311 PMCID: PMC9918188 DOI: 10.3390/ijms24032992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/23/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The retina is among the highest organized tissues of the central nervous system. To achieve such organization, a finely tuned regulation of developmental processes is required to form the retinal layers that contain the specialized neurons and supporting glial cells to allow precise phototransduction. MicroRNAs are a class of small RNAs with undoubtful roles in fundamental biological processes, including neurodevelopment of the brain and the retina. This review provides a short overview of the most important findings regarding microRNAs in the regulation of retinal development, from the developmental-dependent rearrangement of the microRNA expression program to the key roles of particular microRNAs in the differentiation and maintenance of retinal cell subtypes.
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Affiliation(s)
- Jorge Navarro-Calvo
- Unidad de Investigación, Hospital General Universitario Dr. Balmis, ISABIAL, 03010 Alicante, Spain
| | - Gema Esquiva
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain
| | - Violeta Gómez-Vicente
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain
| | - Luis M. Valor
- Unidad de Investigación, Hospital General Universitario Dr. Balmis, ISABIAL, 03010 Alicante, Spain
- Correspondence: ; Tel.: +34-965-913-988
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12
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HS, an Ancient Molecular Recognition and Information Storage Glycosaminoglycan, Equips HS-Proteoglycans with Diverse Matrix and Cell-Interactive Properties Operative in Tissue Development and Tissue Function in Health and Disease. Int J Mol Sci 2023; 24:ijms24021148. [PMID: 36674659 PMCID: PMC9867265 DOI: 10.3390/ijms24021148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/23/2022] [Accepted: 12/27/2022] [Indexed: 01/11/2023] Open
Abstract
Heparan sulfate is a ubiquitous, variably sulfated interactive glycosaminoglycan that consists of repeating disaccharides of glucuronic acid and glucosamine that are subject to a number of modifications (acetylation, de-acetylation, epimerization, sulfation). Variable heparan sulfate chain lengths and sequences within the heparan sulfate chains provide structural diversity generating interactive oligosaccharide binding motifs with a diverse range of extracellular ligands and cellular receptors providing instructional cues over cellular behaviour and tissue homeostasis through the regulation of essential physiological processes in development, health, and disease. heparan sulfate and heparan sulfate-PGs are integral components of the specialized glycocalyx surrounding cells. Heparan sulfate is the most heterogeneous glycosaminoglycan, in terms of its sequence and biosynthetic modifications making it a difficult molecule to fully characterize, multiple ligands also make an elucidation of heparan sulfate functional properties complicated. Spatio-temporal presentation of heparan sulfate sulfate groups is an important functional determinant in tissue development and in cellular control of wound healing and extracellular remodelling in pathological tissues. The regulatory properties of heparan sulfate are mediated via interactions with chemokines, chemokine receptors, growth factors and morphogens in cell proliferation, differentiation, development, tissue remodelling, wound healing, immune regulation, inflammation, and tumour development. A greater understanding of these HS interactive processes will improve therapeutic procedures and prognoses. Advances in glycosaminoglycan synthesis and sequencing, computational analytical carbohydrate algorithms and advanced software for the evaluation of molecular docking of heparan sulfate with its molecular partners are now available. These advanced analytic techniques and artificial intelligence offer predictive capability in the elucidation of heparan sulfate conformational effects on heparan sulfate-ligand interactions significantly aiding heparan sulfate therapeutics development.
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13
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Barboni MTS, Joachimsthaler A, Roux MJ, Nagy ZZ, Ventura DF, Rendon A, Kremers J, Vaillend C. Retinal dystrophins and the retinopathy of Duchenne muscular dystrophy. Prog Retin Eye Res 2022:101137. [DOI: 10.1016/j.preteyeres.2022.101137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 10/25/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022]
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14
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Tsukamoto Y, Omi N. Multiple Invagination Patterns and Synaptic Efficacy in Primate and Mouse Rod Synaptic Terminals. Invest Ophthalmol Vis Sci 2022; 63:11. [PMID: 35819284 PMCID: PMC9287620 DOI: 10.1167/iovs.63.8.11] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Optical retina images are scaled based on eye size, which results in a linear scale ratio of 10:1 for human versus mouse and 7:1 for macaque monkey versus mouse. We examined how this scale difference correlates with the structural configuration of synaptic wiring in the rod spherule (RS) between macaque and mouse retinas compared with human data. Methods Rod bipolar cell (BC) dendrites and horizontal cell (HC) axonal processes, which invaginate the RS to form synaptic ribbon-associated triads, were examined by serial section transmission electron microscopy. Results The number of rod BC invaginating dendrites ranged 1∼4 in the macaque RS but only 1∼2 in the mouse. Approximately 40% of those dendrites bifurcated into two central elements in the macaque, but 2% of those dendrites did in the mouse. Both factors gave rise to 10 invagination patterns of BC and HC neurites in the macaque RS but only two in the mouse. Five morphological parameters: the lengths of arciform densities and ribbons, the area of the BC-RS contact, and the surface areas of BC and HC invaginating neurites, were all independent of the invagination patterns in the macaque RS. However, those parameters were significantly greater in the macaque than in the mouse by ratios of 1.5∼1.8. Conclusions The primate RS provides a more expansive BC-RS interface associated with the longer arciform density and more branched invaginating neurites of BCs and HCs than the mouse RS. The resulting greater synaptic contact area may contribute to more efficient signal transfer.
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Affiliation(s)
- Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo, Japan.,Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan.,Center for Systems Vision Science, Organization of Science and Technology, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Naoko Omi
- Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
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15
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Stefano MED, Ferretti V, Mozzetta C. Synaptic alterations as a neurodevelopmental trait of Duchenne muscular dystrophy. Neurobiol Dis 2022; 168:105718. [PMID: 35390481 DOI: 10.1016/j.nbd.2022.105718] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 01/14/2023] Open
Abstract
Dystrophinopaties, e.g., Duchenne muscular dystrophy (DMD), Becker muscular dystrophy and X-linked dilated cardiomyopathy are inherited neuromuscular diseases, characterized by progressive muscular degeneration, which however associate with a significant impact on general system physiology. The more severe is the pathology and its diversified manifestations, the heavier are its effects on organs, systems, and tissues other than muscles (skeletal, cardiac and smooth muscles). All dystrophinopaties are characterized by mutations in a single gene located on the X chromosome encoding dystrophin (Dp427) and its shorter isoforms, but DMD is the most devasting: muscular degenerations manifests within the first 4 years of life, progressively affecting motility and other muscular functions, and leads to a fatal outcome between the 20s and 40s. To date, after years of studies on both DMD patients and animal models of the disease, it has been clearly demonstrated that a significant percentage of DMD patients are also afflicted by cognitive, neurological, and autonomic disorders, of varying degree of severity. The anatomical correlates underlying neural functional damages are established during embryonic development and the early stages of postnatal life, when brain circuits, sensory and motor connections are still maturing. The impact of the absence of Dp427 on the development, differentiation, and consolidation of specific cerebral circuits (hippocampus, cerebellum, prefrontal cortex, amygdala) is significant, and amplified by the frequent lack of one or more of its lower molecular mass isoforms. The most relevant aspect, which characterizes DMD-associated neurological disorders, is based on morpho-functional alterations of selective synaptic connections within the affected brain areas. This pathological feature correlates neurological conditions of DMD to other severe neurological disorders, such as schizophrenia, epilepsy and autistic spectrum disorders, among others. This review discusses the organization and the role of the dystrophin-dystroglycan complex in muscles and neurons, focusing on the neurological aspect of DMD and on the most relevant morphological and functional synaptic alterations, in both central and autonomic nervous systems, described in the pathology and its animal models.
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Affiliation(s)
- Maria Egle De Stefano
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy.
| | - Valentina Ferretti
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy
| | - Chiara Mozzetta
- Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR) of Italy c/o Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy
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16
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Tsukui R, Yamamoto T, Okamura Y, Kato Y, Shibata N. Fukutin regulates tau phosphorylation and synaptic function: Novel properties of fukutin in neurons. Neuropathology 2022; 42:28-39. [PMID: 35026860 PMCID: PMC9305503 DOI: 10.1111/neup.12797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/20/2021] [Accepted: 11/20/2021] [Indexed: 12/13/2022]
Abstract
Fukutin, a product of the causative gene of Fukuyama congenital muscular dystrophy (FCMD), is known to be responsible for basement membrane formation. Patients with FCMD exhibit not only muscular dystrophy but also central nervous system abnormalities, including polymicrogyria and neurofibrillary tangles (NFTs) in the cerebral cortex. The formation of NFTs cannot be explained by basement membrane disorganization. To determine the involvement of fukutin in the NFT formation, we performed molecular pathological investigations using autopsied human brains and cultured neurons of a cell line (SH-SY5Y). In human brains, NFTs, identified with an antibody against phosphorylated tau (p-tau), were observed in FCMD patients but not age-matched control subjects and were localized in cortical neurons lacking somatic immunoreactivity for glutamic acid decarboxylase (GAD), a marker of inhibitory neurons. In FCMD brains, NFTs were mainly distributed in lesions of polymicrogyria. Immunofluorescence staining revealed the colocalization of immunoreactivities for p-tau and phosphorylated glycogen synthase kinase-3β (GSK-3β), a potential tau kinase, in the somatic cytoplasm of SH-SY5Y cells; both the immunoreactivities were increased by fukutin knockdown and reduced by fukutin overexpression. Western blot analysis using SH-SY5Y cells revealed consistent results. Enzyme-linked immunosorbent assay (ELISA) confirmed the binding affinity of fukutin to tau and GSK-3β in SH-SY5Y cells. In the human brains, the density of GAD-immunoreactive neurons in the frontal cortex was significantly higher in the FCMD group than in the control group. GAD immunoreactivity on Western blots of SH-SY5Y cells was significantly increased by fukutin knockdown. On immunofluorescence staining, immunoreactivities for fukutin and GAD were colocalized in the somatic cytoplasm of the human brains and SH-SY5Y cells, whereas those for fukutin and synaptophysin were colocalized in the neuropil of the human brains and the cytoplasm of SH-SY5Y cells. ELISA confirmed the binding affinity of fukutin to GAD and synaptophysin in SH-SY5Y cells. The present results provide in vivo and in vitro evidence for novel properties of fukutin as follows: (i) there is an inverse relationship between fukutin expression and GSK-3β/tau phosphorylation in neurons; (ii) fukutin binds to GSK-3β and tau; (iii) tau phosphorylation occurs in non-GAD-immunoreactive neurons in FCMD brains; (iv) neuronal GAD expression is upregulated in the absence of fukutin; and (v) fukutin binds to GAD and synaptophysin in presynaptic vesicles of neurons.
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Affiliation(s)
- Ryota Tsukui
- Graduate School of Medicine, Tokyo Women's Medical University, Tokyo, Japan.,Division of Human Pathology & Pathological Neuroscience, Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Tomoko Yamamoto
- Division of Human Pathology & Pathological Neuroscience, Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan.,Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Yukinori Okamura
- Graduate School of Medicine, Tokyo Women's Medical University, Tokyo, Japan.,Division of Human Pathology & Pathological Neuroscience, Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Yoichiro Kato
- Division of Human Pathology & Pathological Neuroscience, Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Noriyuki Shibata
- Division of Human Pathology & Pathological Neuroscience, Department of Pathology, Tokyo Women's Medical University, Tokyo, Japan.,Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan
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17
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Tsukamoto Y, Iseki K, Omi N. Helical Fasciculation of Bipolar and Horizontal Cell Neurites for Wiring With Photoreceptors in Macaque and Mouse Retinas. Invest Ophthalmol Vis Sci 2021; 62:31. [PMID: 33507230 PMCID: PMC7846946 DOI: 10.1167/iovs.62.1.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The three-dimensional configurations of rod and cone bipolar cell (BC) dendrites and horizontal cell (HC) processes outside rod and cone synaptic terminals have not been fully elucidated. We reveal how these neurites are mutually arranged to coordinate formation and maintenance of the postsynaptic complex of ribbon synapses in mouse and monkey retinas. Methods Serial section transmission electron microscopy was utilized to reconstruct BC and HC neurites in macaque monkey and mouse, including metabotropic glutamate receptor 6 (mGluR6)-knockout mice. Results Starting from sporadically distributed branching points, rod BC and HC neurites (B and H, respectively) took specific paths to rod spherules by gradually adjusting their mutual positions, which resulted in a closed alternating pattern of H‒B‒H‒B neurites at the rod spherule aperture. This order corresponded to the array of elements constituting the postsynaptic complex of ribbon synapses. We identified novel helical coils of HC processes surrounding the rod BC dendrite in both mouse and macaque retinas, and these structures occurred more frequently in mGluR6-knockout than wild-type mouse retinas. Horizontal cell processes also formed hook-like protrusions that encircled cone BC and HC neurites below the cone pedicles in the macaque retina. Conclusions Bipolar and horizontal cell neurites take specific paths to adjust their mutual positions at the rod spherule aperture. Some HC processes are helically coiled around rod BC dendrites or form hook-like protrusions around cone BC dendrites and HC processes. Loss of mGluR6 signaling may be one factor promoting unbalanced neurite growth and compensatory neurite coiling.
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Affiliation(s)
- Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo, Japan.,Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
| | - Kyoko Iseki
- Laboratory for Retinal Regeneration, RIKEN Center for Developmental Biology, Minatojima Minamimachi, Chuo-ku, Kobe, Hyogo, Japan
| | - Naoko Omi
- Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
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18
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Nemitz L, Dedek K, Janssen-Bienhold U. Synaptic Remodeling in the Cone Pathway After Early Postnatal Horizontal Cell Ablation. Front Cell Neurosci 2021; 15:657594. [PMID: 34122012 PMCID: PMC8187617 DOI: 10.3389/fncel.2021.657594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 05/03/2021] [Indexed: 11/30/2022] Open
Abstract
The first synapse of the visual pathway is formed by photoreceptors, horizontal cells and bipolar cells. While ON bipolar cells invaginate into the photoreceptor terminal and form synaptic triads together with invaginating horizontal cell processes, OFF bipolar cells make flat contacts at the base of the terminal. When horizontal cells are ablated during retina development, no invaginating synapses are formed in rod photoreceptors. However, how cone photoreceptors and their synaptic connections with bipolar cells react to this insult, is unclear so far. To answer this question, we specifically ablated horizontal cells from the developing mouse retina. Following ablation around postnatal day 4 (P4)/P5, cones initially exhibited a normal morphology and formed flat contacts with OFF bipolar cells, but only few invaginating contacts with ON bipolar cells. From P15 on, synaptic remodeling became obvious with clustering of cone terminals and mislocalized cone somata in the OPL. Adult cones (P56) finally displayed highly branched axons with numerous terminals which contained ribbons and vesicular glutamate transporters. Furthermore, type 3a, 3b, and 4 OFF bipolar cell dendrites sprouted into the outer nuclear layer and even expressed glutamate receptors at the base of newly formed cone terminals. These results indicate that cones may be able to form new synapses with OFF bipolar cells in adult mice. In contrast, cone terminals lost their invaginating contacts with ON bipolar cells, highlighting the importance of horizontal cells for synapse maintenance. Taken together, our data demonstrate that early postnatal horizontal cell ablation leads to differential remodeling in the cone pathway: whereas synapses between cones and ON bipolar cells were lost, new putative synapses were established between cones and OFF bipolar cells. These results suggest that synapse formation and maintenance are regulated very differently between flat and invaginating contacts at cone terminals.
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Affiliation(s)
- Lena Nemitz
- Visual Neuroscience, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
| | - Karin Dedek
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Ulrike Janssen-Bienhold
- Visual Neuroscience, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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19
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Uribe ML, Martín-Nieto J, Quereda C, Rubio-Fernández M, Cruces J, Janssen GMC, de Ru AH, van Veelen PA, Hensbergen PJ. Retinal Proteomics of a Mouse Model of Dystroglycanopathies Reveals Molecular Alterations in Photoreceptors. J Proteome Res 2021; 20:3268-3277. [PMID: 34027671 PMCID: PMC8280732 DOI: 10.1021/acs.jproteome.1c00126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Mutations in the POMT1 gene, encoding a protein O-mannosyltransferase
essential for α-dystroglycan
(α-DG) glycosylation, are frequently observed in a group of
rare congenital muscular dystrophies, collectively known as dystroglycanopathies.
However, it is hitherto unclear whether the effects seen in affected
patients can be fully ascribed to α-DG hypoglycosylation. To
study this, here we used comparative mass spectrometry-based proteomics
and immunofluorescence microscopy and investigated the changes in
the retina of mice in which Pomt1 is specifically
knocked out in photoreceptor cells. Our results demonstrate significant
proteomic changes and associated structural alteration in photoreceptor
cells of Pomt1 cKO mice. In addition to the effects
related to impaired α-DG O-mannosylation, we
observed morphological alterations in the outer segment that are associated
with dysregulation of a relatively understudied POMT1 substrate (KIAA1549),
BBSome proteins, and retinal stress markers. In conclusion, our study
provides new hypotheses to explain the phenotypic changes that are
observed in the retina of patients with dystroglycanopathies.
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Affiliation(s)
- Mary Luz Uribe
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands.,Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - José Martín-Nieto
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain.,Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Cristina Quereda
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, 03080 Alicante, Spain
| | - Marcos Rubio-Fernández
- Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080 Alicante, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Universidad Autónoma de Madrid, 28029 Madrid, Spain
| | - George M C Janssen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Arnoud H de Ru
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Peter A van Veelen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands
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20
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Garcia-Delgado AB, Valdes-Sanchez L, Morillo-Sanchez MJ, Ponte-Zuñiga B, Diaz-Corrales FJ, de la Cerda B. Dissecting the role of EYS in retinal degeneration: clinical and molecular aspects and its implications for future therapy. Orphanet J Rare Dis 2021; 16:222. [PMID: 34001227 PMCID: PMC8127272 DOI: 10.1186/s13023-021-01843-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 04/23/2021] [Indexed: 01/22/2023] Open
Abstract
Mutations in the EYS gene are one of the major causes of autosomal recessive retinitis pigmentosa. EYS-retinopathy presents a severe clinical phenotype, and patients currently have no therapeutic options. The progress in personalised medicine and gene and cell therapies hold promise for treating this degenerative disease. However, lack of understanding and incomplete comprehension of disease's mechanism and the role of EYS in the healthy retina are critical limitations for the translation of current technical advances into real therapeutic possibilities. This review recapitulates the present knowledge about EYS-retinopathies, their clinical presentations and proposed genotype–phenotype correlations. Molecular details of the gene and the protein, mainly based on animal model data, are analysed. The proposed cellular localisation and roles of this large multi-domain protein are detailed. Future therapeutic approaches for EYS-retinopathies are discussed.
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Affiliation(s)
- Ana B Garcia-Delgado
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
| | - Lourdes Valdes-Sanchez
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
| | | | - Beatriz Ponte-Zuñiga
- Department of Ophthalmology, University Hospital Virgen Macarena, Seville, Spain.,Retics Oftared, Institute of Health Carlos III, Madrid, Spain
| | - Francisco J Diaz-Corrales
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain.
| | - Berta de la Cerda
- Andalusian Center for Molecular Biology and Regenerative Medicine (CABIMER), Avda. Americo Vespucio 24, 41092, Seville, Spain
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21
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Bayram N, Bayram AK, Per H, Gümüş H, Ozsaygili C, Doğan MS, Çağlayan AO. Analysis of genotype-phenotype correlation in Walker-Warburg syndrome with a novel CRPPA mutation in different clinical manifestations. Eur J Ophthalmol 2021; 32:NP71-NP76. [PMID: 33977792 DOI: 10.1177/11206721211016306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
PURPOSE Walker-Warburg syndrome (WWS) is a rare autosomal recessive disorder characterized by congenital muscular dystrophy and severe brain and eye malformations. This study aims to analyze genotype-phenotype correlations in WWS with a novel cytidine diphosphate-l-ribitol pyrophosphorylase A (CRPPA) mutation in different clinical manifestations. CASE DESCRIPTION We report a girl with a presentation of multiple brain and ocular anomalies. Her ophthalmological evaluation showed a shallow anterior chamber, cortical cataract, iris hypoplasia, persistent hyperplastic primary vitreous in the right eye, punctate cataract, iris hypoplasia, primary congenital glaucoma, and a widespread loss of fundus pigmentation in the left eye. She was hypotonic, and her deep tendon reflexes were absent. Laboratory investigations showed high serum levels of serum creatine kinase. Brain magnetic resonance imaging demonstrated hydrocephalus, agenesis of the corpus callosum, retrocerebellar cyst, cerebellar dysplasia and hypoplasia, cobblestone lissencephaly, and hypoplastic brainstem. Whole exome sequencing revealed a novel homozygous nonsense mutation in the first exon of the CRPPA gene (NM_001101426.4, c.217G>T, p.Glu73Ter). CONCLUSIONS The study findings expand the phenotypic variability of the ocular manifestations in the CRPPA gene-related WWS. Iris hypoplasia can be a part of clinical manifestations of the CRPPA gene-related WWS. The uncovering of the genes associated with ocular features can provide preventative methods, early diagnosis, and improved therapeutic strategies.
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Affiliation(s)
- Nurettin Bayram
- Department of Ophthalmology, University of Health Sciences, Kayseri City Training and Research Hospital, Kayseri, Turkey
| | - Ayşe Kaçar Bayram
- Department of Pediatrics, Division of Pediatric Neurology, University of Health Sciences, Kayseri City Training and Research Hospital, Kayseri, Turkey
| | - Hüseyin Per
- Department of Pediatrics, Division of Pediatric Neurology, School of Medicine, Erciyes University, Kayseri, Turkey
| | - Hakan Gümüş
- Department of Pediatrics, Division of Pediatric Neurology, School of Medicine, Erciyes University, Kayseri, Turkey
| | - Cemal Ozsaygili
- Department of Ophthalmology, University of Health Sciences, Kayseri City Training and Research Hospital, Kayseri, Turkey
| | - Mehmet Said Doğan
- Department of Pediatric Radiology, School of Medicine, Erciyes University, Kayseri, Turkey
| | - Ahmet Okay Çağlayan
- Department of Medical Genetics, School of Medicine, Dokuz Eylul University, Izmir, Turkey.,Departments of Neurosurgery, Neurobiology and Genetics, Yale School of Medicine, New Haven, CT, USA
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22
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Burger CA, Jiang D, Mackin RD, Samuel MA. Development and maintenance of vision's first synapse. Dev Biol 2021; 476:218-239. [PMID: 33848537 DOI: 10.1016/j.ydbio.2021.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/02/2021] [Accepted: 04/03/2021] [Indexed: 12/21/2022]
Abstract
Synapses in the outer retina are the first information relay points in vision. Here, photoreceptors form synapses onto two types of interneurons, bipolar cells and horizontal cells. Because outer retina synapses are particularly large and highly ordered, they have been a useful system for the discovery of mechanisms underlying synapse specificity and maintenance. Understanding these processes is critical to efforts aimed at restoring visual function through repairing or replacing neurons and promoting their connectivity. We review outer retina neuron synapse architecture, neural migration modes, and the cellular and molecular pathways that play key roles in the development and maintenance of these connections. We further discuss how these mechanisms may impact connectivity in the retina.
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Affiliation(s)
- Courtney A Burger
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danye Jiang
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Robert D Mackin
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Melanie A Samuel
- Huffington Center on Aging, Department of Neuroscience, Baylor College of Medicine, Houston, TX, 77030, USA.
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23
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Functional analysis of Samd11, a retinal photoreceptor PRC1 component, in establishing rod photoreceptor identity. Sci Rep 2021; 11:4180. [PMID: 33603070 PMCID: PMC7892874 DOI: 10.1038/s41598-021-83781-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 02/04/2021] [Indexed: 11/08/2022] Open
Abstract
Establishing correct neuronal cell identity is essential to build intricate neural tissue architecture and acquire precise neural function during vertebrate development. While it is known that transcription factors play important roles in retinal cell differentiation, the contribution of epigenetic factors to establishing cell identity during retinal development remains unclear. We previously reported that Samd7, a rod photoreceptor cell-specific sterile alpha motif (SAM) domain protein, functions as a Polycomb repressive complex 1 component (PRC1) that is essential for establishing rod identity. In the current study, we analyzed a functional role of Samd11, another photoreceptor-enriched SAM-domain protein, in photoreceptor differentiation and maturation. We observed that Samd11 interacts with Phc2 and Samd7, suggesting that Samd11 is a component of PRC1 in photoreceptor cells. We generated Samd11-null allele and established Samd7/11 double knock-out (DKO) mouse. The Samd7/11 DKO retina exhibits shortened photoreceptor outer segments by electron microscopy analysis. Microarray analysis revealed that Samd7/11 DKO up-regulated more retinal genes than Samd7-/- alone, partial functional redundancy of Samd7 and Samd11. Taken together, the current results suggest that Samd7 and Samd11 are PRC1 components and that Samd7 is the major regulator while Samd11 is an accessory factor used for the establishment of precise rod photoreceptor identity.
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Pourhoseini S, Goswami-Sewell D, Zuniga-Sanchez E. Neurofascin Is a Novel Component of Rod Photoreceptor Synapses in the Outer Retina. Front Neural Circuits 2021; 15:635849. [PMID: 33643000 PMCID: PMC7902911 DOI: 10.3389/fncir.2021.635849] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/20/2021] [Indexed: 11/13/2022] Open
Abstract
Neural circuit formation is an intricate and complex process where multiple neuron types must come together to form synaptic connections at a precise location and time. How this process is orchestrated during development remains poorly understood. Cell adhesion molecules are known to play a pivotal role in assembling neural circuits. They serve as recognition molecules between corresponding synaptic partners. In this study, we identified a new player in assembling neural circuits in the outer retina, the L1-family cell adhesion molecule Neurofascin (Nfasc). Our data reveals Nfasc is expressed in the synaptic layer where photoreceptors make synaptic connections to their respective partners. A closer examination of Nfasc expression shows high levels of expression in rod bipolars but not in cone bipolars. Disruption of Nfasc using a conditional knockout allele results in selective loss of pre- and post-synaptic proteins in the rod synaptic layer but not in the cone synaptic layer. Electron microscopic analysis confirms that indeed there are abnormal synaptic structures with less dendrites of rod bipolars innervating rod terminals in loss of Nfasc animals. Consistent with these findings, we also observe a decrease in rod-driven retinal responses with disruption of Nfasc function but not in cone-driven responses. Taken together, our data suggest a new role of Nfasc in rod synapses within the mouse outer retina.
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Affiliation(s)
- Sahar Pourhoseini
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | | | - Elizabeth Zuniga-Sanchez
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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25
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Persiconi I, Cosmi F, Guadagno NA, Lupo G, De Stefano ME. Dystrophin Is Required for the Proper Timing in Retinal Histogenesis: A Thorough Investigation on the mdx Mouse Model of Duchenne Muscular Dystrophy. Front Neurosci 2020; 14:760. [PMID: 32982660 PMCID: PMC7487415 DOI: 10.3389/fnins.2020.00760] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/29/2020] [Indexed: 12/15/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a lethal X-linked muscular disease caused by defective expression of the cytoskeletal protein dystrophin (Dp427). Selected autonomic and central neurons, including retinal neurons, express Dp427 and/or dystrophin shorter isoforms. Because of this, DMD patients may also experience different forms of cognitive impairment, neurological and autonomic disorders, and specific visual defects. DMD-related damages to the nervous system are established during development, suggesting a role for all dystrophin isoforms in neural circuit development and differentiation; however, to date, their function in retinogenesis has never been investigated. In this large-scale study, we analyzed whether the lack of Dp427 affects late retinogenesis in the mdx mouse, the most well studied animal model of DMD. Retinal gene expression and layer maturation, as well as neural cell proliferation, apoptosis, and differentiation, were evaluated in E18 and/or P0, P5, P10, and adult mice. In mdx mice, expression of Capn3, Id3 (E18-P5), and Dtnb (P5) genes, encoding proteins involved in different aspects of retina development and synaptogenesis (e.g., Calpain 3, DNA-binding protein inhibitor-3, and β-dystrobrevin, respectively), was transiently reduced compared to age-matched wild type mice. Concomitantly, a difference in the time required for the retinal ganglion cell layer to reach appropriate thickness was observed (P0–P5). Immunolabeling for specific cell markers also evidenced a significant dysregulation in the number of GABAergic amacrine cells (P5–P10), a transient decrease in the area immunopositive for the Vesicular Glutamate Transporter 1 (VGluT1) during ribbon synapse maturation (P10) and a reduction in the number of calretinin+ retinal ganglion cells (RGCs) (adults). Finally, the number of proliferating retinal progenitor cells (P5–P10) and apoptotic cells (P10) was reduced. These results support the hypothesis of a role for Dp427 during late retinogenesis different from those proposed in consolidated neural circuits. In particular, Dp427 may be involved in shaping specific steps of retina differentiation. Notably, although most of the above described quantitative alterations recover over time, the number of calretinin+ RGCs is reduced only in the mature retina. This suggests that alterations subtler than the timing of retinal maturation may occur, a hypothesis that demands further in-depth functional studies.
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Affiliation(s)
- Irene Persiconi
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy.,Department of Biosciences, University of Oslo, Oslo, Norway
| | - Francesca Cosmi
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | | | - Giuseppe Lupo
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy
| | - Maria Egle De Stefano
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy.,Laboratory Affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy.,Center for Research in Neurobiology "Daniel Bovet", Sapienza University of Rome, Rome, Italy
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26
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Catalani E, Bongiorni S, Taddei AR, Mezzetti M, Silvestri F, Coazzoli M, Zecchini S, Giovarelli M, Perrotta C, De Palma C, Clementi E, Ceci M, Prantera G, Cervia D. Defects of full-length dystrophin trigger retinal neuron damage and synapse alterations by disrupting functional autophagy. Cell Mol Life Sci 2020; 78:1615-1636. [PMID: 32749504 PMCID: PMC7904721 DOI: 10.1007/s00018-020-03598-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 06/10/2020] [Accepted: 07/09/2020] [Indexed: 02/06/2023]
Abstract
Dystrophin (dys) mutations predispose Duchenne muscular disease (DMD) patients to brain and retinal complications. Although different dys variants, including long dys products, are expressed in the retina, their function is largely unknown. We investigated the putative role of full-length dystrophin in the homeostasis of neuro-retina and its impact on synapsis stabilization and cell fate. Retinas of mdx mice, the most used DMD model which does not express the 427-KDa dys protein (Dp427), showed overlapped cell death and impaired autophagy. Apoptotic neurons in the outer plexiform/inner nuclear layer and the ganglion cell layer had an impaired autophagy with accumulated autophagosomes. The autophagy dysfunction localized at photoreceptor axonal terminals and bipolar, amacrine, and ganglion cells. The absence of Dp427 does not cause a severe phenotype but alters the neuronal architecture, compromising mainly the pre-synaptic photoreceptor terminals and their post-synaptic sites. The analysis of two dystrophic mutants of the fruit fly Drosophila melanogaster, the homozygous DysE17 and DysEP3397, lacking functional large-isoforms of dystrophin-like protein, revealed rhabdomere degeneration. Structural damages were evident in the internal network of retina/lamina where photoreceptors make the first synapse. Both accumulated autophagosomes and apoptotic features were detected and the visual system was functionally impaired. The reactivation of the autophagosome turnover by rapamycin prevented neuronal cell death and structural changes of mutant flies and, of interest, sustained autophagy ameliorated their response to light. Overall, these findings indicate that functional full-length dystrophin is required for synapsis stabilization and neuronal survival of the retina, allowing also proper autophagy as a prerequisite for physiological cell fate and visual properties.
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Affiliation(s)
- Elisabetta Catalani
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Silvia Bongiorni
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Anna Rita Taddei
- Section of Electron Microscopy, Great Equipment Center, Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Marta Mezzetti
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Federica Silvestri
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Marco Coazzoli
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Silvia Zecchini
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Matteo Giovarelli
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Cristiana Perrotta
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
| | - Clara De Palma
- Department of Medical Biotechnology and Translational Medicine (BioMeTra), Università degli Studi di Milano, via Luigi Vanvitelli 32, 20129 , Milano, Italy
| | - Emilio Clementi
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy
- Unit of Clinical Pharmacology, University Hospital "Luigi Sacco"-ASST Fatebenefratelli Sacco, via G.B. Grassi 74, 20157, Milano, Italy
- Scientific Institute IRCCS "Eugenio Medea", via Don Luigi Monza 20, 23842, Bosisio Parini (LC), Italy
| | - Marcello Ceci
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Giorgio Prantera
- Department of Ecological and Biological Sciences (DEB), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy
| | - Davide Cervia
- Department for Innovation in Biological, Agro-Food and Forest Systems (DIBAF), Università degli Studi della Tuscia, largo dell'Università snc, 01100, Viterbo, Italy.
- Department of Biomedical and Clinical Sciences "Luigi Sacco" (DIBIC), Università degli Studi di Milano, via G.B. Grassi 74, 20157, Milano, Italy.
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27
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Liang C, Chen Y, Jiang X, Zou M, Yang Z, Li H, Peng L. Pikachurin Is Partially Involved in the Synaptic Connection Between Donor and Host Cells in Late-Stage rd1 Mice Following Conspecific Photoreceptor Transplantation. Stem Cells Dev 2020; 29:786-794. [PMID: 32178579 DOI: 10.1089/scd.2019.0268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Photoreceptor transplantation can rescue the retinal function of late-stage rd1 mice. Many studies have used synaptic markers to suggest that there are synaptic connections after transplantation, but how donor and host cells are connected remains unknown. Many molecules are needed for triad ribbon synapse formation in wild-type mice. Among them, pikachurin is an important extracellular matrix protein that bridges the pre- and postsynaptic components. To investigate the mechanism of the synaptic connection between donor photoreceptor and host retina, we studied the expression of pikachurin in late-stage rd1 mice before and after transplantation. The results showed that the full-length form of pikachurin could still be detected in the degenerated retina. After photoreceptors were transplanted to the subretinal space of rd1 or wild-type mice, pikachurin was detected in the cytoplasm of most donor photoreceptor cells. Pikachurin puncta may represent the cleaved form of the protein and may indicate synapse generation, but it was barely observed in the donor mass of wild-type mice (3.83 ± 3.17 puncta per 100 donor cells). In contrast, pikachurin puncta could be found in the graft of the rd1 mouse retina, but the number was low (21.35 ± 9.48 puncta per 100 donor cells). In addition, 54.12 ± 8.45% of bassoon puncta were paired with pikachurin puncta and 45.5 ± 6.33% were not, indicating that there were fewer pikachurin puncta than bassoon. These results suggest that pikachurin is involved in only a portion of the synaptic connection between the donor photoreceptor and host retina.
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Affiliation(s)
- Chen Liang
- Department of Ophthalmology and National Clinical Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, China.,Research Laboratory of Ophthalmology and Vision Sciences, West China Hospital, Sichuan University, Chengdu, China
| | - YingYing Chen
- Department of Ophthalmology and National Clinical Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, China
| | - XiaoShuang Jiang
- Department of Ophthalmology and National Clinical Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, China
| | - Ming Zou
- Department of Ophthalmology and National Clinical Research Center for Geriatrics, West China Hospital of Sichuan University, Chengdu, China
| | - Zhen Yang
- Research Core Facility, West China Hospital of Sichuan University, Chengdu, China
| | - HuiFang Li
- Research Core Facility, West China Hospital of Sichuan University, Chengdu, China
| | - LanYa Peng
- Department of Medical, West China Hospital of Sichuan University, Chengdu, China
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28
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Liu Y, Yu M, Shang X, Nguyen MHH, Balakrishnan S, Sager R, Hu H. Eyes shut homolog (EYS) interacts with matriglycan of O-mannosyl glycans whose deficiency results in EYS mislocalization and degeneration of photoreceptors. Sci Rep 2020; 10:7795. [PMID: 32385361 PMCID: PMC7210881 DOI: 10.1038/s41598-020-64752-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/21/2020] [Indexed: 12/12/2022] Open
Abstract
Mutations in eyes shut homolog (EYS), a secreted extracellular matrix protein containing multiple laminin globular (LG) domains, and in protein O-mannose β1, 2-N-acetylglucosaminyl transferase 1 (POMGnT1), an enzyme involved in O-mannosyl glycosylation, cause retinitis pigmentosa (RP), RP25 and RP76, respectively. How EYS and POMGnT1 regulate photoreceptor survival is poorly understood. Since some LG domain-containing proteins function by binding to the matriglycan moiety of O-mannosyl glycans, we hypothesized that EYS interacted with matriglycans as well. To test this hypothesis, we performed EYS Far-Western blotting assay and generated pomgnt1 mutant zebrafish. The results showed that EYS bound to matriglycans. Pomgnt1 mutation in zebrafish resulted in a loss of matriglycan, retention of synaptotagmin-1-positive EYS secretory vesicles within the outer nuclear layer, and diminished EYS protein near the connecting cilia. Photoreceptor density in 2-month old pomgnt1 mutant retina was similar to the wild-type animals but was significantly reduced at 6-months. These results indicate that EYS protein localization to the connecting cilia requires interaction with the matriglycan and that O-mannosyl glycosylation is required for photoreceptor survival in zebrafish. This study identified a novel interaction between EYS and matriglycan demonstrating that RP25 and RP76 are mechanistically linked in that O-mannosyl glycosylation controls targeting of EYS protein.
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Affiliation(s)
- Yu Liu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Miao Yu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Xuanze Shang
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - My Hong Hoai Nguyen
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
- Department of Biological Sciences, State University of New York at Plattsburgh, 101 Broad St., Plattsburgh, New York, 12901, USA
| | - Shanmuganathan Balakrishnan
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Rachel Sager
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA
| | - Huaiyu Hu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY, 13210, USA.
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29
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Furukawa T, Ueno A, Omori Y. Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells. Cell Mol Life Sci 2020; 77:1251-1266. [PMID: 31586239 PMCID: PMC11105113 DOI: 10.1007/s00018-019-03324-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/21/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022]
Abstract
In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.
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Affiliation(s)
- Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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30
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Shiraya T, Araki F, Ueta T, Fukunaga H, Totsuka K, Arai T, Uemura A, Moriya K, Kato S. Ursodeoxycholic Acid Attenuates the Retinal Vascular Abnormalities in Anti-PDGFR-β Antibody-Induced Pericyte Depletion Mouse Models. Sci Rep 2020; 10:977. [PMID: 31969665 PMCID: PMC6976624 DOI: 10.1038/s41598-020-58039-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 01/07/2020] [Indexed: 01/12/2023] Open
Abstract
As a clinical manifestations of diabetic retinopathy (DR), pericytes (PCs) loss from the capillary walls is thought to be an initial pathological change responsible for the breakdown of the blood-retinal barrier (BRB). This study was performed to investigate the effects of ursodeoxycholic acid (UDCA) in PC depletion mice by injection of an antibody against platelet-derived growth factor reception-β (PDGFR-β clone APB5). To assess the integrity of the retinal vessels, their density, diameters, vessel branching points, and number of acellular capillaries were evaluated. While all types of retinal vessels became enlarged in APB5-induced mice, treatment with UDCA rescued the vasculature; the vessel density, diameter of the veins and capillaries, and vessel branching points were significantly lower in mice treated with UDCA. Although APB5-induced mice displayed progressive exacerbation of retinal edema, whole retinal thickness upon treatment with UDCA was significantly decreased. Additionally, UDCA reduced the expression of F4/80+ macrophages in the APB5-induced retina according to immunofluorescent labeling. UDCA also reduced the increased expression of angiogenic factors and inflammatory mediators (vascular endothelial growth factor, intercellular adhesion molecule-1, and monocyte chemotactic protein-1). These findings suggest that UDCA can be used to prevent the progression of and treat DR.
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Affiliation(s)
- Tomoyasu Shiraya
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
| | - Fumiyuki Araki
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takashi Ueta
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hisako Fukunaga
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kiyohito Totsuka
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahiro Arai
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Akiyoshi Uemura
- Department of Retinal Vascular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Kyoji Moriya
- Department of Infectious Diseases, The University of Tokyo Hospital, Tokyo, Japan
| | - Satoshi Kato
- Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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31
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Orlandi C, Omori Y, Wang Y, Cao Y, Ueno A, Roux MJ, Condomitti G, de Wit J, Kanagawa M, Furukawa T, Martemyanov KA. Transsynaptic Binding of Orphan Receptor GPR179 to Dystroglycan-Pikachurin Complex Is Essential for the Synaptic Organization of Photoreceptors. Cell Rep 2020; 25:130-145.e5. [PMID: 30282023 PMCID: PMC6203450 DOI: 10.1016/j.celrep.2018.08.068] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 08/16/2018] [Accepted: 08/23/2018] [Indexed: 01/05/2023] Open
Abstract
Establishing synaptic contacts between neurons is paramount for nervous system function. This process involves transsynaptic interactions between a host of cell adhesion molecules that act in cooperation with the proteins of the extracellular matrix to specify uniquephysiological propertiesofindividual synaptic connections. However, understanding of the molecular mechanisms that generate functional diversity in an input-specific fashion is limited. In this study, we identify that major components of the extracellular matrix proteins present in the synaptic cleft—members oftheheparansulfateproteoglycan (HSPG) family—associate with the GPR158/179 group of orphan receptors. Using the mammalian retina as a model system, we demonstrate that the HSPG member Pikachurin, released by photoreceptors, recruits a key post-synaptic signaling complex of downstream ON-bipolar neurons in coordination with the presynaptic dystroglycan glycoprotein complex. We further demonstrate that this transsynaptic assembly plays an essential role in synaptic transmission of photoreceptor signals. Orlandi et al. identify transsynaptic assembly at photoreceptor synapses involving pre-synaptic dystrophindystroglycan complex and the postsynaptic orphan receptor GPR179 bridged by HSPG protein Pikachurin in the cleft and demonstrate its role in shaping transmission of photoreceptor signals.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Michel J Roux
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Centre National de la Recherche Scientifique, UMR7104, INSERM, U1258, Illkirch, France
| | - Giuseppe Condomitti
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium; KU Leuven, Department of Neurosciences, Herestraat 49, 3000 Leuven, Belgium
| | - Motoi Kanagawa
- Division of Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, Osaka, Japan
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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32
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Nemitz L, Dedek K, Janssen-Bienhold U. Rod Bipolar Cells Require Horizontal Cells for Invagination Into the Terminals of Rod Photoreceptors. Front Cell Neurosci 2019; 13:423. [PMID: 31619966 PMCID: PMC6760018 DOI: 10.3389/fncel.2019.00423] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/03/2019] [Indexed: 01/22/2023] Open
Abstract
In the central nervous system, neuronal processing relies on the precisely orchestrated formation of synapses during development. The first synapse of the visual system is a triad synapse, comprising photoreceptors, horizontal cells and bipolar cells. During the second postnatal week, the axon terminal processes of horizontal cells invaginate rod spherules, followed by rod bipolar cell dendrites. Both elements finally oppose the synaptic ribbon (the release site of glutamate). However, it has not been fully elucidated whether horizontal cells are essential for rod bipolar cell dendrites to find their way into the rod terminal. In the present study, we investigated this question by specifically ablating horizontal cells from the early postnatal mouse retina. We monitored the formation of the rod-to-rod bipolar cell synapse during retinal maturation until postnatal day 21. Based on quantitative electron microscopy, we found that without horizontal cells, the dendrites of rod bipolar cells never entered rod terminals. Furthermore, rods displayed significantly fewer and shorter presynaptic ribbons, suggesting that glutamate release is decreased, which coincided with significantly reduced expression of postsynaptic proteins (mGluR6, GPR179) in rod bipolar cells. Collectively, our findings uncover that horizontal cells are indeed necessary guideposts for rod bipolar cells. Whether horizontal cells release diffusible guidance cues or provide structural guidance by expressing specific cell adhesion molecules remains to be seen.
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Affiliation(s)
- Lena Nemitz
- Visual Neuroscience, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany
| | - Karin Dedek
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Ulrike Janssen-Bienhold
- Visual Neuroscience, Department of Neuroscience, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
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He J, Zhao C, Dai J, Weng CH, Bian BSJ, Gong Y, Ge L, Fang Y, Liu H, Xu H, Yin ZQ. Microglia Mediate Synaptic Material Clearance at the Early Stage of Rats With Retinitis Pigmentosa. Front Immunol 2019; 10:912. [PMID: 31105708 PMCID: PMC6499027 DOI: 10.3389/fimmu.2019.00912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 04/09/2019] [Indexed: 12/11/2022] Open
Abstract
Resident microglia are the main immune cells in the retina and play a key role in the pathogenesis of retinitis pigmentosa (RP). Many previous studies on the roles of microglia mainly focused on the neurotoxicity or neuroprotection of photoreceptors, while their contributions to synaptic remodeling of neuronal circuits in the retina of early RP remained unclarified. In the present study, we used Royal College of Surgeons (RCS) rats, a classic RP model characterized by progressive microglia activation and synapse loss, to investigate the constitutive effects of microglia on the synaptic lesions and ectopic neuritogenesis. Rod degeneration resulted in synapse disruption and loss in the outer plexiform layer (OPL) at the early stage of RP. Coincidentally, the resident microglia in the OPL increased phagocytosis and mainly engaged in phagocytic engulfment of postsynaptic mGluR6 of rod bipolar cells (RBCs). Complement pathway might be involved in clearance of postsynaptic elements of RBCs by microglia. We pharmacologically deleted microglia using a CSF1 receptor (CSF1R) inhibitor to confirm this finding, and found that it caused the accumulation of postsynaptic mGluR6 levels and increased the number and length of ectopic dendrites in the RBCs. Interestingly, the numbers of presynaptic sites expressing CtBP2 and colocalized puncta in the OPL of RCS rats were not affected by microglia elimination. However, sustained microglial depletion led to progressive functional deterioration in the retinal responses to light in RCS rats. Based on our results, microglia mediated the remodeling of RBCs by phagocytosing postsynaptic materials and inhibiting ectopic neuritogenesis, contributing to delay the deterioration of vision at the early stage of RP.
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Affiliation(s)
- Juncai He
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Congjian Zhao
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Jiaman Dai
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Chuan Huang Weng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Bai Shi Jiao Bian
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yu Gong
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Lingling Ge
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yajie Fang
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Hui Liu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Haiwei Xu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Zheng Qin Yin
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
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Dempsey CE, Bigotti MG, Adams JC, Brancaccio A. Analysis of α-Dystroglycan/LG Domain Binding Modes: Investigating Protein Motifs That Regulate the Affinity of Isolated LG Domains. Front Mol Biosci 2019; 6:18. [PMID: 30984766 PMCID: PMC6450144 DOI: 10.3389/fmolb.2019.00018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 03/07/2019] [Indexed: 12/25/2022] Open
Abstract
Dystroglycan (DG) is an adhesion complex that links the cytoskeleton to the surrounding extracellular matrix in skeletal muscle and a wide variety of other tissues. It is composed of a highly glycosylated extracellular α-DG associated noncovalently with a transmembrane β-DG whose cytodomain interacts with dystrophin and its isoforms. Alpha-dystroglycan (α-DG) binds tightly and in a calcium-dependent fashion to multiple extracellular proteins and proteoglycans, each of which harbors at least one, or, more frequently, tandem arrays of laminin-globular (LG) domains. Considerable biochemical and structural work has accumulated on the α-DG-binding LG domains, highlighting a significant heterogeneity in ligand-binding properties of domains from different proteins as well as between single and multiple LG domains within the same protein. Here we review biochemical, structural, and functional information on the LG domains reported to bind α-dystroglycan. In addition, we have incorporated bioinformatics and modeling to explore whether specific motifs responsible for α-dystroglycan recognition can be identified within isolated LG domains. In particular, we analyzed the LG domains of slits and agrin as well as those of paradigmatic α-DG non-binders such as laminin-α3. While some stretches of basic residues may be important, no universally conserved motifs could be identified. However, the data confirm that the coordinated calcium atom within the LG domain is needed to establish an interaction with the sugars of α-DG, although it appears that this alone is insufficient to mediate significant α-DG binding. We develop a scenario involving different binding modes of a single LG domain unit, or tandemly repeated units, with α-DG. A variability of binding modes might be important to generate a range of affinities to allow physiological regulation of this interaction, reflecting its crucial biological importance.
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Affiliation(s)
| | | | - Josephine C Adams
- School of Biochemistry, University of Bristol, Bristol, United Kingdom
| | - Andrea Brancaccio
- School of Biochemistry, University of Bristol, Bristol, United Kingdom.,Istituto di Chimica del Riconoscimento Molecolare - CNR, Università Cattolica del Sacro Cuore, Rome, Italy
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Pangrsic T, Singer JH, Koschak A. Voltage-Gated Calcium Channels: Key Players in Sensory Coding in the Retina and the Inner Ear. Physiol Rev 2019; 98:2063-2096. [PMID: 30067155 DOI: 10.1152/physrev.00030.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Calcium influx through voltage-gated Ca (CaV) channels is the first step in synaptic transmission. This review concerns CaV channels at ribbon synapses in primary sense organs and their specialization for efficient coding of stimuli in the physical environment. Specifically, we describe molecular, biochemical, and biophysical properties of the CaV channels in sensory receptor cells of the retina, cochlea, and vestibular apparatus, and we consider how such properties might change over the course of development and contribute to synaptic plasticity. We pay particular attention to factors affecting the spatial arrangement of CaV channels at presynaptic, ribbon-type active zones, because the spatial relationship between CaV channels and release sites has been shown to affect synapse function critically in a number of systems. Finally, we review identified synaptopathies affecting sensory systems and arising from dysfunction of L-type, CaV1.3, and CaV1.4 channels or their protein modulatory elements.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Joshua H Singer
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Alexandra Koschak
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
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Nickolls AR, Bönnemann CG. The roles of dystroglycan in the nervous system: insights from animal models of muscular dystrophy. Dis Model Mech 2018; 11:11/12/dmm035931. [PMID: 30578246 PMCID: PMC6307911 DOI: 10.1242/dmm.035931] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Dystroglycan is a cell membrane protein that binds to the extracellular matrix in a variety of mammalian tissues. The α-subunit of dystroglycan (αDG) is heavily glycosylated, including a special O-mannosyl glycoepitope, relying upon this unique glycosylation to bind its matrix ligands. A distinct group of muscular dystrophies results from specific hypoglycosylation of αDG, and they are frequently associated with central nervous system involvement, ranging from profound brain malformation to intellectual disability without evident morphological defects. There is an expanding literature addressing the function of αDG in the nervous system, with recent reports demonstrating important roles in brain development and in the maintenance of neuronal synapses. Much of these data are derived from an increasingly rich array of experimental animal models. This Review aims to synthesize the information from such diverse models, formulating an up-to-date understanding about the various functions of αDG in neurons and glia of the central and peripheral nervous systems. Where possible, we integrate these data with our knowledge of the human disorders to promote translation from basic mechanistic findings to clinical therapies that take the neural phenotypes into account. Summary: Dystroglycan is a ubiquitous matrix receptor linked to brain and muscle disease. Unraveling the functions of this protein will inform basic and translational research on neural development and muscular dystrophies.
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Affiliation(s)
- Alec R Nickolls
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.,Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Carsten G Bönnemann
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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37
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Kerov V, Laird JG, Joiner ML, Knecht S, Soh D, Hagen J, Gardner SH, Gutierrez W, Yoshimatsu T, Bhattarai S, Puthussery T, Artemyev NO, Drack AV, Wong RO, Baker SA, Lee A. α 2δ-4 Is Required for the Molecular and Structural Organization of Rod and Cone Photoreceptor Synapses. J Neurosci 2018; 38:6145-6160. [PMID: 29875267 PMCID: PMC6031576 DOI: 10.1523/jneurosci.3818-16.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 05/10/2018] [Accepted: 05/31/2018] [Indexed: 11/21/2022] Open
Abstract
α2δ-4 is an auxiliary subunit of voltage-gated Cav1.4 L-type channels that regulate the development and mature exocytotic function of the photoreceptor ribbon synapse. In humans, mutations in the CACNA2D4 gene encoding α2δ-4 cause heterogeneous forms of vision impairment in humans, the underlying pathogenic mechanisms of which remain unclear. To investigate the retinal function of α2δ-4, we used genome editing to generate an α2δ-4 knock-out (α2δ-4 KO) mouse. In male and female α2δ-4 KO mice, rod spherules lack ribbons and other synaptic hallmarks early in development. Although the molecular organization of cone synapses is less affected than rod synapses, horizontal and cone bipolar processes extend abnormally in the outer nuclear layer in α2δ-4 KO retina. In reconstructions of α2δ-4 KO cone pedicles by serial block face scanning electron microscopy, ribbons appear normal, except that less than one-third show the expected triadic organization of processes at ribbon sites. The severity of the synaptic defects in α2δ-4 KO mice correlates with a progressive loss of Cav1.4 channels, first in terminals of rods and later cones. Despite the absence of b-waves in electroretinograms, visually guided behavior is evident in α2δ-4 KO mice and better under photopic than scotopic conditions. We conclude that α2δ-4 plays an essential role in maintaining the structural and functional integrity of rod and cone synapses, the disruption of which may contribute to visual impairment in humans with CACNA2D4 mutations.SIGNIFICANCE STATEMENT In the retina, visual information is first communicated by the synapse formed between photoreceptors and second-order neurons. The mechanisms that regulate the structural integrity of this synapse are poorly understood. Here we demonstrate a role for α2δ-4, a subunit of voltage-gated Ca2+ channels, in organizing the structure and function of photoreceptor synapses. We find that presynaptic Ca2+ channels are progressively lost and that rod and cone synapses are disrupted in mice that lack α2δ-4. Our results suggest that alterations in presynaptic Ca2+ signaling and photoreceptor synapse structure may contribute to vision impairment in humans with mutations in the CACNA2D4 gene encoding α2δ-4.
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Affiliation(s)
- Vasily Kerov
- Department of Molecular Physiology and Biophysics
| | | | | | - Sharmon Knecht
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, and
| | - Daniel Soh
- Department of Molecular Physiology and Biophysics
| | | | | | | | - Takeshi Yoshimatsu
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, and
| | - Sajag Bhattarai
- Department of Ophthalmology and Institute for Vision Research
| | - Teresa Puthussery
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon 97239
| | | | - Arlene V Drack
- Department of Ophthalmology and Institute for Vision Research
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, and
| | - Sheila A Baker
- Department of Biochemistry,
- Department of Ophthalmology and Institute for Vision Research
| | - Amy Lee
- Department of Molecular Physiology and Biophysics,
- Department of Otolaryngology-Head and Neck Surgery
- Department of Neurology, University of Iowa, Iowa City, Iowa 52242
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Rubio-Fernández M, Uribe ML, Vicente-Tejedor J, Germain F, Susín-Lara C, Quereda C, Montoliu L, de la Villa P, Martín-Nieto J, Cruces J. Impairment of photoreceptor ribbon synapses in a novel Pomt1 conditional knockout mouse model of dystroglycanopathy. Sci Rep 2018; 8:8543. [PMID: 29867208 PMCID: PMC5986861 DOI: 10.1038/s41598-018-26855-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 05/16/2018] [Indexed: 11/09/2022] Open
Abstract
Hypoglycosylation of α-dystroglycan (α-DG) resulting from deficiency of protein O-mannosyltransferase 1 (POMT1) may cause severe neuromuscular dystrophies with brain and eye anomalies, named dystroglycanopathies. The retinal involvement of these disorders motivated us to generate a conditional knockout (cKO) mouse experiencing a Pomt1 intragenic deletion (exons 3-4) during the development of photoreceptors, mediated by the Cre recombinase expressed from the cone-rod homeobox (Crx) gene promoter. In this mouse, retinal α-DG was unglycosylated and incapable of binding laminin. Retinal POMT1 deficiency caused significant impairments in both electroretinographic recordings and optokinetic reflex in Pomt1 cKO mice, and immunohistochemical analyses revealed the absence of β-DG and of the α-DG-interacting protein, pikachurin, in the outer plexiform layer (OPL). At the ultrastructural level, noticeable alterations were observed in the ribbon synapses established between photoreceptors and bipolar cells. Therefore, O-mannosylation of α-DG in the retina carried out by POMT1 is crucial for the establishment of proper synapses at the OPL and transmission of visual information from cones and rods to their postsynaptic neurons.
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Affiliation(s)
- Marcos Rubio-Fernández
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Mary Luz Uribe
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain
| | - Javier Vicente-Tejedor
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - Francisco Germain
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - Cristina Susín-Lara
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Cristina Quereda
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain
| | - Lluis Montoliu
- Departamento de Biología Molecular y Celular, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), 28049, Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029, Madrid, Spain
| | - Pedro de la Villa
- Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, 28805, Madrid, Spain
| | - José Martín-Nieto
- Departamento de Fisiología, Genética y Microbiología, Facultad de Ciencias, Universidad de Alicante, 03080, Alicante, Spain.,Instituto Multidisciplinar para el Estudio del Medio "Ramón Margalef", Universidad de Alicante, 03080, Alicante, Spain
| | - Jesús Cruces
- Departamento de Bioquímica, Instituto de Investigaciones Biomédicas "Alberto Sols" UAM-CSIC, Facultad de Medicina, Universidad Autónoma de Madrid, 28029, Madrid, Spain.
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Suzuki-Kerr H, Iwagawa T, Sagara H, Mizota A, Suzuki Y, Watanabe S. Pivotal roles of Fezf2 in differentiation of cone OFF bipolar cells and functional maturation of cone ON bipolar cells in retina. Exp Eye Res 2018; 171:142-154. [DOI: 10.1016/j.exer.2018.03.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2018] [Revised: 03/05/2018] [Accepted: 03/16/2018] [Indexed: 10/17/2022]
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40
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Lrit1, a Retinal Transmembrane Protein, Regulates Selective Synapse Formation in Cone Photoreceptor Cells and Visual Acuity. Cell Rep 2018; 22:3548-3561. [DOI: 10.1016/j.celrep.2018.03.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/09/2018] [Accepted: 02/28/2018] [Indexed: 12/31/2022] Open
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41
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Hunter DD, Manglapus MK, Bachay G, Claudepierre T, Dolan MW, Gesuelli KA, Brunken WJ. CNS synapses are stabilized trans-synaptically by laminins and laminin-interacting proteins. J Comp Neurol 2017; 527:67-86. [PMID: 29023785 DOI: 10.1002/cne.24338] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/21/2017] [Accepted: 09/29/2017] [Indexed: 01/05/2023]
Abstract
The retina expresses several laminins in the outer plexiform layer (OPL), where they may provide an extracellular scaffold for synapse stabilization. Mice with a targeted deletion of the laminin β2 gene (Lamb2) exhibit retinal disruptions: photoreceptor synapses in the OPL are disorganized and the retinal physiological response is attenuated. We hypothesize that laminins are required for proper trans-synaptic alignment. To test this, we compared the distribution, expression, association and modification of several pre- and post-synaptic elements in wild-type and Lamb2-null retinae. A potential laminin receptor, integrin α3, is at the presynaptic side of the wild-type OPL. Another potential laminin receptor, dystroglycan, is at the post-synaptic side of the wild-type OPL. Integrin α3 and dystroglycan can be co-immunoprecipitated with the laminin β2 chain, demonstrating that they may bind laminins. In the absence of the laminin β2 chain, the expression of many pre-synaptic components (bassoon, kinesin, among others) is relatively undisturbed although their spatial organization and anchoring to the membrane is disrupted. In contrast, in the Lamb2-null, β-dystroglycan (β-DG) expression is altered, co-localization of β-DG with dystrophin and the glutamate receptor mGluR6 is disrupted, and the post-synaptic bipolar cell components mGluR6 and GPR179 become dissociated, suggesting that laminins mediate scaffolding of post-synaptic components. In addition, although pikachurin remains associated with β-DG, pikachurin is no longer closely associated with mGluR6 or α-DG in the Lamb2-null. These data suggest that laminins act as links among pre- and post-synaptic laminin receptors and α-DG and pikachurin in the synaptic space to maintain proper trans-synaptic alignment.
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Affiliation(s)
- Dale D Hunter
- Department of Anatomy and Cellular Biology, Tufts University and Tufts Center for Vision Research, Boston, Massachusetts.,Department of Ophthalmology and the SUNY Eye Institute, Upstate Medical University, Syracuse, New York
| | - Mary K Manglapus
- Department of Anatomy and Cellular Biology, Tufts University and Tufts Center for Vision Research, Boston, Massachusetts
| | - Galina Bachay
- Department of Ophthalmology and the SUNY Eye Institute, Upstate Medical University, Syracuse, New York
| | - Thomas Claudepierre
- Department of Anatomy and Cellular Biology, Tufts University and Tufts Center for Vision Research, Boston, Massachusetts
| | - Michael W Dolan
- Department of Ophthalmology and the SUNY Eye Institute, Upstate Medical University, Syracuse, New York
| | - Kelly-Ann Gesuelli
- Department of Ophthalmology and the SUNY Eye Institute, Upstate Medical University, Syracuse, New York
| | - William J Brunken
- Department of Anatomy and Cellular Biology, Tufts University and Tufts Center for Vision Research, Boston, Massachusetts.,Department of Ophthalmology and the SUNY Eye Institute, Upstate Medical University, Syracuse, New York
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42
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Krebs MP, Collin GB, Hicks WL, Yu M, Charette JR, Shi LY, Wang J, Naggert JK, Peachey NS, Nishina PM. Mouse models of human ocular disease for translational research. PLoS One 2017; 12:e0183837. [PMID: 28859131 PMCID: PMC5578669 DOI: 10.1371/journal.pone.0183837] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/12/2017] [Indexed: 01/24/2023] Open
Abstract
Mouse models provide a valuable tool for exploring pathogenic mechanisms underlying inherited human disease. Here, we describe seven mouse models identified through the Translational Vision Research Models (TVRM) program, each carrying a new allele of a gene previously linked to retinal developmental and/or degenerative disease. The mutations include four alleles of three genes linked to human nonsyndromic ocular diseases (Aipl1tvrm119, Aipl1tvrm127, Rpgrip1tvrm111, RhoTvrm334) and three alleles of genes associated with human syndromic diseases that exhibit ocular phentoypes (Alms1tvrm102, Clcn2nmf289, Fkrptvrm53). Phenotypic characterization of each model is provided in the context of existing literature, in some cases refining our current understanding of specific disease attributes. These murine models, on fixed genetic backgrounds, are available for distribution upon request and may be useful for understanding the function of the gene in the retina, the pathological mechanisms induced by its disruption, and for testing experimental approaches to treat the corresponding human ocular diseases.
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Affiliation(s)
- Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wanda L. Hicks
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Lan Ying Shi
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
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Dystroglycan Maintains Inner Limiting Membrane Integrity to Coordinate Retinal Development. J Neurosci 2017; 37:8559-8574. [PMID: 28760865 DOI: 10.1523/jneurosci.0946-17.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/19/2017] [Accepted: 07/21/2017] [Indexed: 02/02/2023] Open
Abstract
Proper neural circuit formation requires the precise regulation of neuronal migration, axon guidance, and dendritic arborization. Mutations affecting the function of the transmembrane glycoprotein dystroglycan cause a form of congenital muscular dystrophy that is frequently associated with neurodevelopmental abnormalities. Despite its importance in brain development, the role of dystroglycan in regulating retinal development remains poorly understood. Using a mouse model of dystroglycanopathy (ISPDL79* ) and conditional dystroglycan mutants of both sexes, we show that dystroglycan is critical for the proper migration, axon guidance, and dendritic stratification of neurons in the inner retina. Using genetic approaches, we show that dystroglycan functions in neuroepithelial cells as an extracellular scaffold to maintain the integrity of the retinal inner limiting membrane. Surprisingly, despite the profound disruptions in inner retinal circuit formation, spontaneous retinal activity is preserved. These results highlight the importance of dystroglycan in coordinating multiple aspects of retinal development.SIGNIFICANCE STATEMENT The extracellular environment plays a critical role in coordinating neuronal migration and neurite outgrowth during neural circuit development. The transmembrane glycoprotein dystroglycan functions as a receptor for multiple extracellular matrix proteins and its dysfunction leads to a form of muscular dystrophy frequently associated with neurodevelopmental defects. Our results demonstrate that dystroglycan is required for maintaining the structural integrity of the inner limiting membrane (ILM) in the developing retina. In the absence of functional dystroglycan, ILM degeneration leads to defective migration, axon guidance, and mosaic spacing of neurons and a loss of multiple neuron types during retinal development. These results demonstrate that disorganization of retinal circuit development is a likely contributor to visual dysfunction in patients with dystroglycanopathy.
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Martemyanov KA, Sampath AP. The Transduction Cascade in Retinal ON-Bipolar Cells: Signal Processing and Disease. Annu Rev Vis Sci 2017; 3:25-51. [PMID: 28715957 DOI: 10.1146/annurev-vision-102016-061338] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Our robust visual experience is based on the reliable transfer of information from our photoreceptor cells, the rods and cones, to higher brain centers. At the very first synapse of the visual system, information is split into two separate pathways, ON and OFF, which encode increments and decrements in light intensity, respectively. The importance of this segregation is borne out in the fact that receptive fields in higher visual centers maintain a separation between ON and OFF regions. In the past decade, the molecular mechanisms underlying the generation of ON signals have been identified, which are unique in their use of a G-protein signaling cascade. In this review, we consider advances in our understanding of G-protein signaling in ON-bipolar cell (BC) dendrites and how insights about signaling have emerged from visual deficits, mostly night blindness. Studies of G-protein signaling in ON-BCs reveal an intricate mechanism that permits the regulation of visual sensitivity over a wide dynamic range.
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Affiliation(s)
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, University of California, Los Angeles, California 90095;
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Neuillé M, Cao Y, Caplette R, Guerrero-Given D, Thomas C, Kamasawa N, Sahel JA, Hamel CP, Audo I, Picaud S, Martemyanov KA, Zeitz C. LRIT3 Differentially Affects Connectivity and Synaptic Transmission of Cones to ON- and OFF-Bipolar Cells. Invest Ophthalmol Vis Sci 2017; 58:1768-1778. [PMID: 28334377 PMCID: PMC5374884 DOI: 10.1167/iovs.16-20745] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). Using a cCSNB mouse model lacking Lrit3 (nob6), we recently have shown that LRIT3 has a role in the correct localization of TRPM1 (transient receptor potential melastatin 1) to the dendritic tips of ON-bipolar cells (BCs), contacting both rod and cone photoreceptors. Furthermore, postsynaptic clustering of other mGluR6 cascade components is selectively eliminated at the dendritic tips of cone ON-BCs. The purpose of this study was to further define the role of LRIT3 in structural and functional organization of cone synapses. Methods Exhaustive electroretinogram analysis was performed in a patient with LRIT3 mutations. Multielectrode array recordings were performed at the level of retinal ganglion cells in nob6 mice. Targeting of GluR1 and GluR5 at the dendritic tips of OFF-BCs in nob6 retinas was assessed by immunostaining and confocal microscopy. The ultrastructure of photoreceptor synapses was evaluated by electron microscopy in nob6 mice. Results The patient with LRIT3 mutations had a selective ON-BC dysfunction with relatively preserved OFF-BC responses. In nob6 mice, complete lack of ON-pathway function with robust, yet altered signaling processing in OFF-pathways was detected. Consistent with these observations, molecules essential for the OFF-BC signaling were normally targeted to the synapse. Finally, synaptic contacts made by ON-BC but not OFF-BC neurons with the cone pedicles were disorganized without ultrastructural alterations in cone terminals, horizontal cell processes, or synaptic ribbons. Conclusions These results suggest that LRIT3 is likely involved in coordination of the transsynaptic communication between cones and ON-BCs during synapse formation and function.
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Affiliation(s)
- Marion Neuillé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Romain Caplette
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | | | - Connon Thomas
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - Naomi Kamasawa
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom 6Fondation Ophtalmologique Adolphe de Rothschild, Paris, France 8Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Christian P Hamel
- INSERM U583, Physiopathologie et thérapie des déficits sensoriels et moteurs, Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, Montpellier, France
| | - Isabelle Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Serge Picaud
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Christina Zeitz
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
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Zhang C, Kolodkin AL, Wong RO, James RE. Establishing Wiring Specificity in Visual System Circuits: From the Retina to the Brain. Annu Rev Neurosci 2017; 40:395-424. [PMID: 28460185 DOI: 10.1146/annurev-neuro-072116-031607] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The retina is a tremendously complex image processor, containing numerous cell types that form microcircuits encoding different aspects of the visual scene. Each microcircuit exhibits a distinct pattern of synaptic connectivity. The developmental mechanisms responsible for this patterning are just beginning to be revealed. Furthermore, signals processed by different retinal circuits are relayed to specific, often distinct, brain regions. Thus, much work has focused on understanding the mechanisms that wire retinal axonal projections to their appropriate central targets. Here, we highlight recently discovered cellular and molecular mechanisms that together shape stereotypic wiring patterns along the visual pathway, from within the retina to the brain. Although some mechanisms are common across circuits, others play unconventional and circuit-specific roles. Indeed, the highly organized connectivity of the visual system has greatly facilitated the discovery of novel mechanisms that establish precise synaptic connections within the nervous system.
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Affiliation(s)
- Chi Zhang
- Department of Biological Structure, University of Washington, Seattle, Washington 98195; ,
| | - Alex L Kolodkin
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; ,
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, Seattle, Washington 98195; ,
| | - Rebecca E James
- Solomon H. Snyder Department of Neuroscience, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; ,
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Structural divergence of essential triad ribbon synapse proteins among placental mammals - Implications for preclinical trials in photoreceptor transplantation therapy. Exp Eye Res 2017; 159:156-167. [PMID: 28322827 DOI: 10.1016/j.exer.2017.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/24/2017] [Accepted: 03/17/2017] [Indexed: 11/22/2022]
Abstract
As photoreceptor transplantation rapidly moves closer to the clinic, verifying graft efficacy in animal models may have unforeseen xenogeneic barriers. Although photoreceptor transplants have most convincingly exhibited functional synaptogenesis in conspecific studies, such evidence (while ruling out false-positives due to: viral graft labeling, fusion/cytosolic transfer, or neuroprotection) has not yet been shown for discordant xenografts. From this, a fundamental question should be raised: is useful xenosynaptogenesis likely between human photoreceptors and mouse retina? The triad ribbon synapse (TRS) that would normally form is unique and contains trans-synaptic proteins essential to its formation and function. Thus, could interspecific structural divergence be present that may inhibit this trans-synaptic bridge in discordant xenografts? In an effort to address this question computationally, we compared eight recently confirmed (including subcellular location) TRS specific (or predominantly expressed at the TRS) proteins among placental mammals (1-to-1 orthologs) using HyPhy selection analysis (a predictive measure of structural divergence) and by using Phyre2 tertiary structural modeling. Here, selection analysis revealed strong positive (diversifying) selection acting on a particularly important TRS protein: pikachurin. This positive selection was localized to its second Laminin-G (LG)-like domain and on its N-terminal domain - a putative region of trans-synaptic interaction. Localization of structural divergence to the N-terminus of each putative post-translational cleavage (PTC) product may suggest neofunctionalization from ancestral uncleaved pikachurin - this would be consistent with a recent counter-paradigm report of pikachurin cleavage predominating at the TRS. From this, we suggest a dual role after cleavage where the N-terminal fragment can still mediate the trans-synaptic bridge, while the C-terminal fragment may act as a diffusible trophic or "homing" factor for bipolar cell dendrite migration. Tertiary structural models mirrored the conformational divergence predicted by selection analysis. With human and mouse pikachurin (as well as other TRS proteins) likely to diverge considerably in structure among placental mammals - alongside known inter-mammalian variation in TRS phenotype and protein repertoire, high levels of diversifying selection acting on genes involving sensation, considerable timespans allowing for genetic drift that can create xenogeneic epistasis, and uncertainty surrounding the extent of xenosynaptogenesis in PPC transplant studies to date - use of distantly related hosts to test human photoreceptor graft therapeutic efficacy should be considered with caution.
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Gentile G, Ceccarelli M, Micheli L, Tirone F, Cavallaro S. Functional Genomics Identifies Tis21-Dependent Mechanisms and Putative Cancer Drug Targets Underlying Medulloblastoma Shh-Type Development. Front Pharmacol 2016; 7:449. [PMID: 27965576 PMCID: PMC5127835 DOI: 10.3389/fphar.2016.00449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 11/09/2016] [Indexed: 12/11/2022] Open
Abstract
We have recently generated a novel medulloblastoma (MB) mouse model with activation of the Shh pathway and lacking the MB suppressor Tis21 (Patched1+/-/Tis21KO ). Its main phenotype is a defect of migration of the cerebellar granule precursor cells (GCPs). By genomic analysis of GCPs in vivo, we identified as drug target and major responsible of this defect the down-regulation of the promigratory chemokine Cxcl3. Consequently, the GCPs remain longer in the cerebellum proliferative area, and the MB frequency is enhanced. Here, we further analyzed the genes deregulated in a Tis21-dependent manner (Patched1+/-/Tis21 wild-type vs. Ptch1+/-/Tis21 knockout), among which are a number of down-regulated tumor inhibitors and up-regulated tumor facilitators, focusing on pathways potentially involved in the tumorigenesis and on putative new drug targets. The data analysis using bioinformatic tools revealed: (i) a link between the Shh signaling and the Tis21-dependent impairment of the GCPs migration, through a Shh-dependent deregulation of the clathrin-mediated chemotaxis operating in the primary cilium through the Cxcl3-Cxcr2 axis; (ii) a possible lineage shift of Shh-type GCPs toward retinal precursor phenotype, i.e., the neural cell type involved in group 3 MB; (iii) the identification of a subset of putative drug targets for MB, involved, among the others, in the regulation of Hippo signaling and centrosome assembly. Finally, our findings define also the role of Tis21 in the regulation of gene expression, through epigenetic and RNA processing mechanisms, influencing the fate of the GCPs.
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Affiliation(s)
- Giulia Gentile
- Institute of Neurological Sciences, National Research Council Catania, Italy
| | - Manuela Ceccarelli
- Institute of Cell Biology and Neurobiology, National Research Council, Fondazione Santa Lucia Rome, Italy
| | - Laura Micheli
- Institute of Cell Biology and Neurobiology, National Research Council, Fondazione Santa Lucia Rome, Italy
| | - Felice Tirone
- Institute of Cell Biology and Neurobiology, National Research Council, Fondazione Santa Lucia Rome, Italy
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Transgenic Rescue of the LARGEmyd Mouse: A LARGE Therapeutic Window? PLoS One 2016; 11:e0159853. [PMID: 27467128 PMCID: PMC4965172 DOI: 10.1371/journal.pone.0159853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/08/2016] [Indexed: 12/02/2022] Open
Abstract
LARGE is a glycosyltransferase involved in glycosylation of α-dystroglycan (α-DG). Absence of this protein in the LARGEmyd mouse results in α-DG hypoglycosylation, and is associated with central nervous system abnormalities and progressive muscular dystrophy. Up-regulation of LARGE has previously been proposed as a therapy for the secondary dystroglycanopathies: overexpression in cells compensates for defects in multiple dystroglycanopathy genes. Counterintuitively, LARGE overexpression in an FKRP-deficient mouse exacerbates pathology, suggesting that modulation of α-DG glycosylation requires further investigation. Here we demonstrate that transgenic expression of human LARGE (LARGE-LV5) in the LARGEmyd mouse restores α-DG glycosylation (with marked hyperglycosylation in muscle) and that this corrects both the muscle pathology and brain architecture. By quantitative analyses of LARGE transcripts we also here show that levels of transgenic and endogenous LARGE in the brains of transgenic animals are comparable, but that the transgene is markedly overexpressed in heart and particularly skeletal muscle (20–100 fold over endogenous). Our data suggest LARGE overexpression may only be deleterious under a forced regenerative context, such as that resulting from a reduction in FKRP: in the absence of such a defect we show that systemic expression of LARGE can indeed act therapeutically, and that even dramatic LARGE overexpression is well-tolerated in heart and skeletal muscle. Moreover, correction of LARGEmyd brain pathology with only moderate, near-physiological LARGE expression suggests a generous therapeutic window.
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Expression pattern in retinal photoreceptors of POMGnT1, a protein involved in muscle-eye-brain disease. Mol Vis 2016; 22:658-73. [PMID: 27375352 PMCID: PMC4911909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 06/14/2016] [Indexed: 11/01/2022] Open
Abstract
PURPOSE The POMGNT1 gene, encoding protein O-linked-mannose β-1,2-N-acetylglucosaminyltransferase 1, is associated with muscle-eye-brain disease (MEB) and other dystroglycanopathies. This gene's lack of function or expression causes hypoglycosylation of α-dystroglycan (α-DG) in the muscle and the central nervous system, including the brain and the retina. The ocular symptoms of patients with MEB include retinal degeneration and detachment, glaucoma, and abnormal electroretinogram. Nevertheless, the POMGnT1 expression pattern in the healthy mammalian retina has not yet been investigated. In this work, we address the expression of the POMGNT1 gene in the healthy retina of a variety of mammals and characterize the distribution pattern of this gene in the adult mouse retina and the 661W photoreceptor cell line. METHODS Using reverse transcription (RT)-PCR and immunoblotting, we studied POMGNT1 expression at the mRNA and protein levels in various mammalian species, from rodents to humans. Immunofluorescence confocal microscopy analyses were performed to characterize the distribution profile of its protein product in mouse retinal sections and in 661W cultured cells. The intranuclear distribution of POMT1 and POMT2, the two enzymes preceding POMGnT1 in the α-DG O-mannosyl glycosylation pathway, was also analyzed. RESULTS POMGNT1 mRNA and its encoded protein were expressed in the neural retina of all mammals studied. POMGnT1 was located in the cytoplasmic fraction in the mouse retina and concentrated in the myoid portion of the photoreceptor inner segments, where the protein colocalized with GM130, a Golgi complex marker. The presence of POMGnT1 in the Golgi complex was also evident in 661W cells. However, and in contrast to retinal tissue, POMGnT1 additionally accumulated in the nucleus of the 661W photoreceptors. Colocalization was found within this organelle between POMGnT1 and POMT1/2, the latter associated with euchromatic regions of the nucleus. CONCLUSIONS Our results indicate that POMGnT1 participates not only in the synthesis of O-mannosyl glycans added to α-DG in the Golgi complex but also in the glycosylation of other yet-to-be-identified proteins in the nucleus of mouse photoreceptors.
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