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Tapia M, Levay K, Tsoulfas P, Park KK. Retrograde AAV-mediated gene modulation reveals chloride intracellular channel proteins as potent regulators of retinal ganglion cell death. Exp Neurol 2024; 377:114810. [PMID: 38714284 DOI: 10.1016/j.expneurol.2024.114810] [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: 03/01/2024] [Revised: 04/20/2024] [Accepted: 05/03/2024] [Indexed: 05/09/2024]
Abstract
Most projection neurons, including retinal ganglion cells (RGCs), undergo cell death after axotomy proximal to the cell body. Specific RGC subtypes, such as ON-OFF direction selective RGCs (ooDSGCs) are particularly vulnerable, whereas intrinsically photosensitive RGCs (ipRGCs) exhibit resilience to axonal injury. Through the application of RNA sequencing and fluorescent in situ hybridization, we show that the expression of chloride intracellular channel protein 1 and 4 (Clic1 and Clic4) are highly increased in the ooDSGCs after axonal injury. Toward determining a gene's role in RGCs, we optimized the utility and efficacy of adenovirus associated virus (AAV)-retro expressing short hairpin RNA (shRNA). Injection of AAV2-retro into the superior colliculus results in efficient shRNA expression in RGCs. Incorporating histone H2B gene fused with mGreenLantern results in bright nuclear reporter expression, thereby enhancing single RGC identification and cell quantitation in live retinas. Lastly, we demonstrate that AAV2-retro mediated knockdown of both Clic1 and Clic4 promotes RGC survival after injury. Our findings establish an integrated use of AAV2-retro-shRNA and real-time fundus imaging and reveal CLICs' contribution to RGC death.
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Affiliation(s)
- Mary Tapia
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, The University of Miami Miller School of Medicine, 1501 NW 10th Avenue, Miami, FL 33136, United States of America
| | - Konstantin Levay
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, The University of Miami Miller School of Medicine, 1501 NW 10th Avenue, Miami, FL 33136, United States of America
| | - Pantelis Tsoulfas
- Department of Neurological Surgery, The Miami Project to Cure Paralysis, The University of Miami Miller School of Medicine, 1501 NW 10th Avenue, Miami, FL 33136, United States of America
| | - Kevin K Park
- Department of Ophthalmology, Department of Neuroscience, Peter O'Donnell Jr. Brain Institute, The University of Texas Southwestern Medical Center, 5901 Forest Park Rd, Dallas, TX 75235, United States of America.
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2
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Pitha I, Du L, Nguyen TD, Quigley H. IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors. Prog Retin Eye Res 2024; 99:101232. [PMID: 38110030 PMCID: PMC10960268 DOI: 10.1016/j.preteyeres.2023.101232] [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: 08/17/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.
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Affiliation(s)
- Ian Pitha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center for Nanomedicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liya Du
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Harry Quigley
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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3
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Loo Y, Chan ASY, Khor CC, Aung T, Wang Z. Rodent genetically modified models of glaucoma. Mol Aspects Med 2024; 95:101229. [PMID: 38039744 DOI: 10.1016/j.mam.2023.101229] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 11/11/2023] [Accepted: 11/15/2023] [Indexed: 12/03/2023]
Abstract
Glaucoma, one of the leading causes of irreversible blindness worldwide, is a complex and heterogenous disease. While environmental factors are important, it is well-recognized that the disease has a strong heritable component. With the advent of large-cohort genome wide association studies, a myriad of genetic risk loci has been linked to different forms of glaucoma. Animal models have been an indispensable tool in characterizing these loci, especially if they lie within coding regions in the genome. Not only do these models connect genotype to phenotype, advancing our understanding of glaucoma pathogenesis in the process, they also have valuable utility as a platform for the pre-clinical testing of potential therapies. In this review, we will outline genetic models used for studying the major forms of glaucoma, including primary open angle glaucoma, normal tension glaucoma, primary angle closure glaucoma, pigmentary glaucoma, pseudoexfoliation glaucoma, and early onset glaucoma, including congenital and developmental glaucoma, and how studying these models have helped shed light on human glaucoma.
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Affiliation(s)
- Yunhua Loo
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Anita Sook Yee Chan
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Chiea Chuen Khor
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Tin Aung
- Duke-NUS Medical School, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Zhenxun Wang
- Duke-NUS Medical School, Singapore; Genome Institute of Singapore, Agency for Science, Technology and Research, Singapore; Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
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4
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Zuo Z, Zhang Z, Zhang S, Fan B, Li G. The Molecular Mechanisms Involved in Axonal Degeneration and Retrograde Retinal Ganglion Cell Death. DNA Cell Biol 2023; 42:653-667. [PMID: 37819746 DOI: 10.1089/dna.2023.0180] [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] [Indexed: 10/13/2023] Open
Abstract
Axonal degeneration is a pathologic change common to multiple retinopathies and optic neuropathies. Various pathologic factors, such as mechanical injury, inflammation, and ischemia, can damage retinal ganglion cell (RGC) somas and axons, eventually triggering axonal degeneration and RGC death. The molecular mechanisms of somal and axonal degeneration are distinct but also overlap, and axonal degeneration can result in retrograde somal degeneration. While the mitogen-activated protein kinase pathway acts as a central node in RGC axon degeneration, several newly discovered molecules, such as sterile alpha and Toll/interleukin-1 receptor motif-containing protein 1 and nicotinamide mononucleotide adenylyltransferase 2, also play a critical role in this pathological process following different types of injury. Therefore, we summarize the types of injury that cause RGC axon degeneration and retrograde RGC death and important underlying molecular mechanisms, providing a reference for the identification of targets for protecting axons and RGCs.
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Affiliation(s)
- Zhaoyang Zuo
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
| | - Ziyuan Zhang
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
| | - Siming Zhang
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
| | - Bin Fan
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
| | - Guangyu Li
- Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
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5
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Soucy JR, Aguzzi EA, Cho J, Gilhooley MJ, Keuthan C, Luo Z, Monavarfeshani A, Saleem MA, Wang XW, Wohlschlegel J, Baranov P, Di Polo A, Fortune B, Gokoffski KK, Goldberg JL, Guido W, Kolodkin AL, Mason CA, Ou Y, Reh TA, Ross AG, Samuels BC, Welsbie D, Zack DJ, Johnson TV. Retinal ganglion cell repopulation for vision restoration in optic neuropathy: a roadmap from the RReSTORe Consortium. Mol Neurodegener 2023; 18:64. [PMID: 37735444 PMCID: PMC10514988 DOI: 10.1186/s13024-023-00655-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/07/2023] [Indexed: 09/23/2023] Open
Abstract
Retinal ganglion cell (RGC) death in glaucoma and other optic neuropathies results in irreversible vision loss due to the mammalian central nervous system's limited regenerative capacity. RGC repopulation is a promising therapeutic approach to reverse vision loss from optic neuropathies if the newly introduced neurons can reestablish functional retinal and thalamic circuits. In theory, RGCs might be repopulated through the transplantation of stem cell-derived neurons or via the induction of endogenous transdifferentiation. The RGC Repopulation, Stem Cell Transplantation, and Optic Nerve Regeneration (RReSTORe) Consortium was established to address the challenges associated with the therapeutic repair of the visual pathway in optic neuropathy. In 2022, the RReSTORe Consortium initiated ongoing international collaborative discussions to advance the RGC repopulation field and has identified five critical areas of focus: (1) RGC development and differentiation, (2) Transplantation methods and models, (3) RGC survival, maturation, and host interactions, (4) Inner retinal wiring, and (5) Eye-to-brain connectivity. Here, we discuss the most pertinent questions and challenges that exist on the path to clinical translation and suggest experimental directions to propel this work going forward. Using these five subtopic discussion groups (SDGs) as a framework, we suggest multidisciplinary approaches to restore the diseased visual pathway by leveraging groundbreaking insights from developmental neuroscience, stem cell biology, molecular biology, optical imaging, animal models of optic neuropathy, immunology & immunotolerance, neuropathology & neuroprotection, materials science & biomedical engineering, and regenerative neuroscience. While significant hurdles remain, the RReSTORe Consortium's efforts provide a comprehensive roadmap for advancing the RGC repopulation field and hold potential for transformative progress in restoring vision in patients suffering from optic neuropathies.
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Affiliation(s)
- Jonathan R Soucy
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Erika A Aguzzi
- The Institute of Ophthalmology, University College London, London, England, UK
| | - Julie Cho
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Michael James Gilhooley
- The Institute of Ophthalmology, University College London, London, England, UK
- Moorfields Eye Hospital, London, England, UK
| | - Casey Keuthan
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ziming Luo
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Aboozar Monavarfeshani
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
| | - Meher A Saleem
- Bascom Palmer Eye Institute, University of Miami Health System, Miami, FL, USA
| | - Xue-Wei Wang
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Petr Baranov
- Department of Ophthalmology, Schepens Eye Research Institute of Mass. Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Adriana Di Polo
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
- University of Montreal Hospital Research Centre, Montreal, QC, Canada
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, OR, USA
| | - Kimberly K Gokoffski
- Department of Ophthalmology, Roski Eye Institute, University of Southern California, Los Angeles, CA, USA
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - William Guido
- Department of Anatomical Sciences and Neurobiology, School of Medicine, University of Louisville, Louisville, KY, USA
| | - Alex L Kolodkin
- The Solomon H Snyder, Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Carol A Mason
- Departments of Pathology and Cell Biology, Neuroscience, and Ophthalmology, College of Physicians and Surgeons, Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Yvonne Ou
- Department of Ophthalmology, University of California, San Francisco, CA, USA
| | - Thomas A Reh
- Department of Biological Structure, University of Washington, Seattle, WA, USA
| | - Ahmara G Ross
- Departments of Ophthalmology and Neurology, University of Pennsylvania, Philadelphia, PA, USA
| | - Brian C Samuels
- Department of Ophthalmology and Visual Sciences, Callahan Eye Hospital, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Derek Welsbie
- Shiley Eye Institute and Viterbi Family Department of Ophthalmology, University of California, San Diego, CA, USA
| | - Donald J Zack
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thomas V Johnson
- Departments of Neuroscience, Molecular Biology & Genetics, and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Cellular & Molecular Medicine Program, Johns Hopkins University School of Medicine, Baltimore, 21287 MD, USA.
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6
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Soliño M, Yu A, Della Santina L, Ou Y. Large-scale survey of excitatory synapses reveals sublamina-specific and asymmetric synapse disassembly in a neurodegenerative circuit. iScience 2023; 26:107262. [PMID: 37609630 PMCID: PMC10440711 DOI: 10.1016/j.isci.2023.107262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 05/09/2023] [Accepted: 06/27/2023] [Indexed: 08/24/2023] Open
Abstract
In the nervous system, parallel circuits are organized in part by the lamina-specific compartmentalization of synaptic connections. In sensory systems such as mammalian retina, degenerating third-order neurons remodel their local presynaptic connectivity with second-order neurons. To determine whether there are sublamina-specific perturbations after injury of adult retinal ganglion cells, we comprehensively analyzed excitatory synapses across the inner plexiform layer (IPL) where bipolar cells connect to ganglion cells. Here, we show that pre- and postsynaptic component loss occurs throughout the IPL in a sublamina-dependent fashion after transient intraocular pressure elevation. Partnered synaptic components are lost as neurodegeneration progresses, while unpartnered synaptic components remain stable. Furthermore, presynaptic components are either lost first or simultaneously with the postsynaptic component. Our results demonstrate that this degenerating neural circuit exhibits differential vulnerability of excitatory synapses depending on IPL depth, highlighting the ordered disassembly of synapses that is specific to laminar compartments of the retina.
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Affiliation(s)
- Manuel Soliño
- Department of Ophthalmology, University of California San Francisco School of Medicine, San Francisco, CA 94143, USA
| | - Alfred Yu
- Department of Ophthalmology, University of California San Francisco School of Medicine, San Francisco, CA 94143, USA
| | - Luca Della Santina
- Department of Ophthalmology, University of California San Francisco School of Medicine, San Francisco, CA 94143, USA
- College of Optometry, University of Houston, Houston, TX 77204, USA
| | - Yvonne Ou
- Department of Ophthalmology, University of California San Francisco School of Medicine, San Francisco, CA 94143, USA
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7
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Wang J, Feng S, Zhang Q, Qin H, Xu C, Fu X, Yan L, Zhao Y, Yao K. Roles of Histone Acetyltransferases and Deacetylases in the Retinal Development and Diseases. Mol Neurobiol 2023; 60:2330-2354. [PMID: 36637745 DOI: 10.1007/s12035-023-03213-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/04/2023] [Indexed: 01/14/2023]
Abstract
The critical role of epigenetic modification of histones in maintaining the normal function of the nervous system has attracted increasing attention. Among these modifications, the level of histone acetylation, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is essential in regulating gene expression. In recent years, the research progress on the function of HDACs in retinal development and disease has advanced remarkably, while that regarding HATs remains to be investigated. Here, we overview the roles of HATs and HDACs in regulating the development of diverse retinal cells, including retinal progenitor cells, photoreceptor cells, bipolar cells, ganglion cells, and Müller glial cells. The effects of HATs and HDACs on the progression of various retinal diseases are also discussed with the highlight of the proof-of-concept research regarding the application of available HDAC inhibitors in treating retinal diseases.
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Affiliation(s)
- Jingjing Wang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Shuyu Feng
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Qian Zhang
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Huan Qin
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Chunxiu Xu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Xuefei Fu
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Lin Yan
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Yaqin Zhao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China.,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China
| | - Kai Yao
- Institute of Visual Neuroscience and Stem Cell Engineering, Wuhan University of Science and Technology, Wuhan, 430065, China. .,College of Life Sciences and Health, Wuhan University of Science and Technology, Wuhan, 430065, China. .,Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan, 430065, China.
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8
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Tapia ML, Nascimento-dos-Santos G, Park KK. Subtype-specific survival and regeneration of retinal ganglion cells in response to injury. Front Cell Dev Biol 2022; 10:956279. [PMID: 36035999 PMCID: PMC9411869 DOI: 10.3389/fcell.2022.956279] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/28/2022] [Indexed: 11/19/2022] Open
Abstract
Retinal ganglion cells (RGCs) are a heterogeneous population of neurons that function synchronously to convey visual information through the optic nerve to retinorecipient target areas in the brain. Injury or disease to the optic nerve results in RGC degeneration and loss of visual function, as few RGCs survive, and even fewer can be provoked to regenerate their axons. Despite causative insults being broadly shared, regeneration studies demonstrate that RGC types exhibit differential resilience to injury and undergo selective survival and regeneration of their axons. While most early studies have identified these RGC types based their morphological and physiological characteristics, recent advances in transgenic and gene sequencing technologies have further enabled type identification based on unique molecular features. In this review, we provide an overview of the well characterized RGC types and identify those shown to preferentially survive and regenerate in various regeneration models. Furthermore, we discuss cellular characteristics of both the resilient and susceptible RGC types including the combinatorial expression of different molecular markers that identify these specific populations. Lastly, we discuss potential molecular mechanisms and genes found to be selectively expressed by specific types that may contribute to their reparative capacity. Together, we describe the studies that lay the important groundwork for identifying factors that promote neural regeneration and help advance the development of targeted therapy for the treatment of RGC degeneration as well as neurodegenerative diseases in general.
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Mavlyutov TA, Myrah JJ, Chauhan AK, Liu Y, McDowell CM. Fibronectin extra domain A (FN-EDA) causes glaucomatous trabecular meshwork, retina, and optic nerve damage in mice. Cell Biosci 2022; 12:72. [PMID: 35619185 PMCID: PMC9137085 DOI: 10.1186/s13578-022-00800-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/27/2022] [Indexed: 12/15/2022] Open
Abstract
Background Elevated intraocular pressure (IOP) is a major risk factor for the development and progression of primary open angle glaucoma and is due to trabecular meshwork (TM) damage. Here, we investigate the role of an endogenous Toll-like receptor 4 (TLR4) ligand, FN-EDA, in the development of glaucoma utilizing a transgenic mouse strain (B6.EDA+/+) that constitutively expresses only FN containing the EDA isoform. Methods Eyes from C57BL6/J (wild-type), B6.EDA+/+ (constitutively active EDA), B6.EDA-/- (EDA null) mice were processed for electron microscopy and consecutive images of the entire length of the TM and Schlemm’s canal (SC) from anterior to posterior were collected and montaged into a single image. ECM accumulation, basement membrane length, and size and number of giant vacuoles were quantified by ImageJ analysis. Tlr4 and Iba1 expression in the TM and ONH cells was conducted using RNAscope in situ hybridization and immunohistochemistry protocols. IOP was measured using a rebound tonometer, ON damage assessed by PPD stain, and RGC loss quantified in RBPMS labeled retina flat mounts. Results Ultrastructure analyses show the TM of B6.EDA+/+ mice have significantly increased accumulation of ECM between TM beams with few empty spaces compared to C57BL/6 J mice (p < 0.05). SC basement membrane is thicker and more continuous in B6.EDA+/+ mice compared to C57BL/6 J. No significant structural differences are detected in the TM of EDA null mice. Tlr4 and Iba1 expression is increased in the TM of B6.EDA+/+ mice compared to C57BL/6 J eyes (p < 0.05). IOP is significantly higher in B6.EDA+/+ mice compared to C57BL/6 J eyes (p < 0.001), and significant ON damage (p < 0.001) and RGC loss (p < 0.05) detected at 1 year of age. Tlr4 mRNA is expressed in mouse ONH cells, and is present in ganglion cell axons, microglia, and astrocytes. There is a significant increase in the area occupied by Iba-1 positive microglia cells in the ONH of B6.EDA+/+ mice compared to C57BL/6 J control eyes (p < 0.01). Conclusions B6.EDA+/+ mice have increased ECM accumulation in the TM, elevated IOP, enhanced proinflammatory changes in the ONH, loss of RGCs, and ONH damage. These data suggest B6.EDA+/+ mice recapitulate many aspects of glaucomatous damage. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00800-y.
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Affiliation(s)
- Timur A Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Justin J Myrah
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Anil K Chauhan
- Department of Internal Medicine, Division of Hematology/Oncology, University of Iowa, Iowa City, IA, USA
| | - Yang Liu
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Colleen M McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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10
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Early-Onset Glaucoma in egl1 Mice Homozygous for Pitx2 Mutation. Biomedicines 2022; 10:biomedicines10030516. [PMID: 35327318 PMCID: PMC8945683 DOI: 10.3390/biomedicines10030516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/18/2022] [Accepted: 02/19/2022] [Indexed: 02/04/2023] Open
Abstract
Mutations in PITX2 cause Axenfeld–Rieger syndrome, with congenital glaucoma as an ocular feature. The egl1 mouse strain carries a chemically induced Pitx2 mutation and develops early-onset glaucoma. In this study, we characterized the glaucomatous features in egl1 mice. The eyes of egl1 and C57BL/6J control mice were assessed by slit lamp examination, total aqueous humor outflow facility, intraocular pressure (IOP) measurement, pattern electroretinography (PERG) recording, and histologic and immunohistochemistry assessment beginning at 3 weeks and up to 12 months of age. The egl1 mice developed elevated IOP as early as 4 weeks old. The IOP elevation was variable and asymmetric within and between the animals. The aqueous humor outflow facility was significantly reduced in 12-month-old animals. PERG detected a decreased response at 2 weeks after the development of IOP elevation. Retinal ganglion cell (RGC) loss was detected after 8 weeks of IOP elevation. Slit lamp and histologic evaluation revealed corneal opacity, iridocorneal adhesions (anterior synechiae), and ciliary body atrophy in egl1 mice. Immunohistochemistry assessment demonstrated glial cell activation and RGC axonal injury in response to IOP elevation. These results show that the eyes of egl1 mice exhibit anterior segment dysgenesis and early-onset glaucoma. The egl1 mouse strain may represent a useful model for the study of congenital glaucoma.
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11
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Differential susceptibility of retinal ganglion cell subtypes against neurodegenerative diseases. Graefes Arch Clin Exp Ophthalmol 2022; 260:1807-1821. [PMID: 35038014 DOI: 10.1007/s00417-022-05556-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 11/27/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022] Open
Abstract
Retinal ganglion cells (RGCs) are essential to propagate external visual information from the retina to the brain. Death of RGCs is speculated to be closely correlated with blinding retinal diseases, such as glaucoma and traumatic optic neuropathy (TON). Emerging innovative technologies have helped refine and standardize the classification of RGCs; at present, they are classified into more than 40 subpopulations in mammals. These RGC subtypes are identified by a combination of anatomical morphologies, electrophysiological functions, and genetic profiles. Increasing evidence suggests that neurodegenerative diseases do not collectively affect the RGCs. In fact, which RGC subtype exhibits the strongest or weakest susceptibility is hotly debated. Although a consensus has not yet been reached, it is certain that assorted RGCs display differential susceptibility against irreversible degeneration. Interestingly, a single RGC subtype can exhibit various vulnerabilities to optic nerve damage in diverse injury models. Thus, elucidating how susceptible RGC subtypes are to various injuries can protect vulnerable RGCs from damage and improve the possibility of preventing and treating visual impairment caused by neurodegenerative diseases. In this review, we summarize in detail the progress and status quo of research on the type-specific susceptibility of RGCs and point out current limitations and the possible directions for future research in this field.
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12
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Di Pierdomenico J, Henderson DCM, Giammaria S, Smith VL, Jamet AJ, Smith CA, Hooper ML, Chauhan BC. Age and intraocular pressure in murine experimental glaucoma. Prog Retin Eye Res 2021; 88:101021. [PMID: 34801667 DOI: 10.1016/j.preteyeres.2021.101021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/25/2021] [Accepted: 11/08/2021] [Indexed: 12/23/2022]
Abstract
Age and intraocular pressure (IOP) are the two most important risk factors for the development and progression of open-angle glaucoma. While IOP is commonly considered in models of experimental glaucoma (EG), most studies use juvenile or adult animals and seldom older animals which are representative of the human disease. This paper provides a concise review of how retinal ganglion cell (RGC) loss, the hallmark of glaucoma, can be evaluated in EG with a special emphasis on serial in vivo imaging, a parallel approach used in clinical practice. It appraises the suitability of EG models for the purpose of in vivo imaging and argues for the use of models that provide a sustained elevation of IOP, without compromise of the ocular media. In a study with parallel cohorts of adult (3-month-old, equivalent to 20 human years) and old (2-year-old, equivalent to 70 human years) mice, we compare the effects of elevated IOP on serial ganglion cell complex thickness and individual RGC dendritic morphology changes obtained in vivo. We also evaluate how age modulates the impact of elevated IOP on RGC somal and axonal density in histological analysis as well the density of melanopsin RGCs. We discuss the challenges of using old animals and emphasize the potential of single RGC imaging for understanding the pathobiology of RGC loss and evaluating new therapeutic avenues.
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Affiliation(s)
- Johnny Di Pierdomenico
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Delaney C M Henderson
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sara Giammaria
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Victoria L Smith
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Aliénor J Jamet
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Corey A Smith
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Michele L Hooper
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Balwantray C Chauhan
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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13
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van der Heide CJ, Meyer KJ, Hedberg-Buenz A, Pellack D, Pomernackas N, Mercer HE, Anderson MG. Quantification and image-derived phenotyping of retinal ganglion cell nuclei in the nee mouse model of congenital glaucoma. Exp Eye Res 2021; 212:108774. [PMID: 34597676 PMCID: PMC8608716 DOI: 10.1016/j.exer.2021.108774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 12/31/2022]
Abstract
The nee mouse model exhibits characteristic features of congenital glaucoma, a common cause of childhood blindness. The current study of nee mice had two components. First, the time course of neurodegeneration in nee retinal flat-mounts was studied over time using a retinal ganglion cell (RGC)-marker, BRN3A; a pan-nuclear marker, TO-PRO-3; and H&E staining. Based on segmentation of nuclei using ImageJ and RetFM-J, this analysis identified a rapid loss of BRN3A+ nuclei from 4 to 15 weeks of age, with the first statistically significant difference in average density compared to age-matched controls detected in 8-week-old cohorts (49% reduction in nee). Consistent with a model of glaucoma, no reductions in BRN3A- nuclei were detected, but the combined analysis indicated that some RGCs lost BRN3A marker expression prior to actual cell loss. These results have a practical application in the design of experiments using nee mice to study mechanisms or potential therapies for congenital glaucoma. The second component of the study pertains to a discovery-based analysis of the large amount of image data with 748,782 segmented retinal nuclei. Using the automatedly collected region of interest feature data captured by ImageJ, we tested whether RGC density of glaucomatous mice was significantly correlated to average nuclear area, perimeter, Feret diameter, or MinFeret diameter. These results pointed to two events influencing nuclear size. For variations in RGC density above approximately 3000 nuclei/mm2 apparent spreading was observed, in which BRN3A- nuclei-regardless of genotype-became slightly larger as RGC density decreased. This same spreading occurred in BRN3A+ nuclei of wild-type mice. For variation in RGC density below 3000 nuclei/mm2, which only occurred in glaucomatous nee mutants, BRN3A+ nuclei became smaller as disease was progressively severe. These observations have relevance to defining RGCs of relatively higher sensitivity to glaucomatous cell death and the nuclear dynamics occurring during their demise.
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Affiliation(s)
- Carly J van der Heide
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA.
| | - Kacie J Meyer
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA.
| | - Adam Hedberg-Buenz
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA; VA Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, 601 Hwy 6 West (151), Iowa City, IA, 52246, USA.
| | - Danielle Pellack
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA.
| | - Nicholas Pomernackas
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA.
| | - Hannah E Mercer
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA.
| | - Michael G Anderson
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Rd., Iowa City, IA, 52242, USA; VA Center for the Prevention and Treatment of Visual Loss, Iowa City VA Health Care System, 601 Hwy 6 West (151), Iowa City, IA, 52246, USA; Department of Ophthalmology and Visual Sciences, University of Iowa, 200 Hawkins Dr., Iowa City, IA, 52242, USA.
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14
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Kong AW, Turner ML, Chan H, Stamper RL, Arnold BF, Della Santina L, Ou Y. Asymmetric Functional Impairment of ON and OFF Retinal Pathways in Glaucoma. OPHTHALMOLOGY SCIENCE 2021; 1:100026. [PMID: 35756578 PMCID: PMC9232180 DOI: 10.1016/j.xops.2021.100026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 11/17/2022]
Abstract
Purpose To investigate ON-pathway versus OFF-pathway dysfunction in glaucoma using handheld electroretinography (ERG) with a temporally modulated sinusoidal flicker stimulus. Design Cross-sectional study. Participants Fifty-nine participants accounting for 104 eyes, comprised of 19 control eyes, 26 glaucoma suspect eyes, and 59 glaucoma eyes. Methods Participants underwent portable ERG testing, which included the photopic flash, photopic flicker, photopic negative response stimulus, ON-OFF stimulus, and a custom-written sinusoidal flicker stimulus that was modulated from 50 to 0.3 Hz. Main Outcome and Measures The ERG response amplitudes were measured by the handheld ERG. For the custom-written sinusoidal flicker stimulus, we derived and compared the log10 first harmonic frequency response amplitudes. Patient discomfort and fatigue after ERG testing were rated on a scale from 1 to 5. Results Baseline demographics were not significantly different between groups, except for ocular characteristics. Analysis was performed adjusting for participant age, sex, race, and dilation status, and the sinusoidal frequency responses were stratified at 10 Hz because higher frequencies are associated with the OFF-pathway, whereas lower frequencies are associated with the ON-pathway. After stratification, glaucoma eyes showed an adjusted decrease of 32.1% at frequencies of more than 10 Hz (95% confidence interval [CI], -51.8% to -4.1%; P = 0.03). For 10 Hz stimulus frequencies or less, an adjusted 11.5% reduction was found (95% CI, -39.5% to 29.1%; P = 0.50). Glaucoma suspect eyes did show a decreased response, but this was not significant at either frequency range. When comparing handheld ERG with traditional visual field assessments, participants found the handheld ERG to result in much less discomfort and fatigue. Conclusions Our finding that glaucoma participants showed greater decreases in ERG response at higher frequencies supports the hypothesis that the OFF-pathway may be more vulnerable in human glaucoma. Using a handheld ERG device with a sinusoidal flicker stimulus may provide an objective assessment of visual function in glaucoma.
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Affiliation(s)
- Alan W. Kong
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Marcus L. Turner
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Hoover Chan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Robert L. Stamper
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
| | - Benjamin F. Arnold
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, California
| | - Luca Della Santina
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, California
| | - Yvonne Ou
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California
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15
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Kong AW, Della Santina L, Ou Y. Probing ON and OFF Retinal Pathways in Glaucoma Using Electroretinography. Transl Vis Sci Technol 2020; 9:14. [PMID: 33117606 PMCID: PMC7571283 DOI: 10.1167/tvst.9.11.14] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 09/14/2020] [Indexed: 12/31/2022] Open
Abstract
Glaucoma is a progressive neurodegenerative disease involving damage and eventually death of retinal ganglion cells (RGCs) that comprise the optic nerve. This review summarizes current understanding of specific RGC type vulnerability in glaucoma and how electroretinography (ERG) may provide an objective measure of these functional perturbations. There is building evidence to suggest that ON RGCs, which respond to light increments, may be more resilient to elevated intraocular pressure and glaucoma, whereas OFF RGCs, which respond to light decrements, may be more susceptible. ERG experiments in nonhuman primates and mice have also shown that the ON- and OFF-pathways can be separated using a variety of techniques such as pattern ERG and the photopic negative response. Another ERG paradigm of interest to separate the ON and OFF responses is a flicker stimulus at varying temporal frequencies. Response to lower temporal frequencies is associated with the ON-pathway, and ERG response to higher frequencies is associated with the OFF-pathway. In mice, experimental glaucoma models have shown greater decreases in ERG response at higher frequencies, suggesting that the OFF-pathway is more susceptible. We also summarize current clinical ERG protocols used for glaucoma and discuss innovations for developing new types of stimuli that can further separate the ON- and OFF-pathways. Applying these novel paradigms that distinguish ON- and OFF-pathways may ultimately improve glaucoma diagnostics and monitoring of glaucoma progression.
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Affiliation(s)
- Alan W Kong
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Luca Della Santina
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
| | - Yvonne Ou
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, USA
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16
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VanderWall KB, Lu B, Alfaro JS, Allsop AR, Carr AS, Wang S, Meyer JS. Differential susceptibility of retinal ganglion cell subtypes in acute and chronic models of injury and disease. Sci Rep 2020; 10:17359. [PMID: 33060618 PMCID: PMC7566630 DOI: 10.1038/s41598-020-71460-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 08/11/2020] [Indexed: 12/21/2022] Open
Abstract
Retinal ganglion cells (RGCs) are a heterogeneous population of neurons, comprised of numerous subtypes that work synchronously to transmit visual information to the brain. In blinding disorders such as glaucoma, RGCs are the main cell type to degenerate and lead to loss of vision. Previous studies have identified and characterized a variety of RGC subtypes in animal models, although only a handful of studies demonstrate the differential loss of these RGC subtypes in response to disease or injury. Thus, efforts of the current study utilized both chronic (bead occlusion) and acute (optic nerve crush, ONC) rat models to characterize disease response and differential loss of RGC subtypes. Bead occlusion and ONC retinas demonstrated significant RGC loss, glial reactivity and apoptosis compared to control retinas. Importantly, bead occlusion and ONC retinas resulted in differential subtype-specific loss of RGCs, with a high susceptibility for alpha- and direction selective-RGCs and preferential survival of ipRGCs. Results of this study serve as an important foundation for future experiments focused on the mechanisms resulting in the loss of RGCs in optic neuropathies, as well as the development of targeted therapeutics for RGC subtype-specific neuroprotection.
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Affiliation(s)
- Kirstin B VanderWall
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Bin Lu
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Regenerative Medicine Institute, Los Angeles, CA, 90048, USA
| | - Jorge S Alfaro
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Regenerative Medicine Institute, Los Angeles, CA, 90048, USA
| | - Anna R Allsop
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Alexa S Carr
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Shaomei Wang
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Regenerative Medicine Institute, Los Angeles, CA, 90048, USA.
| | - Jason S Meyer
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Deparment of Ophthalmology, Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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Kerr A, Patel PA, LaConte LEW, Liang C, Chen CK, Shah V, Fox MA, Mukherjee K. Non-Cell Autonomous Roles for CASK in Optic Nerve Hypoplasia. Invest Ophthalmol Vis Sci 2019; 60:3584-3594. [PMID: 31425583 PMCID: PMC6701874 DOI: 10.1167/iovs.19-27197] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Purpose Heterozygous mutations in the essential X-linked gene CASK associate with optic nerve hypoplasia (ONH) and other retinal disorders in girls. CASK+/− heterozygous knockout mice with mosaic CASK expression exhibit ONH with a loss of retinal ganglion cells (RGCs) but no changes in retinal morphology. It remains unclear if CASK deficiency selectively affects RGCs or also affects other retinal cells. Furthermore, it is not known if CASK expression in RGCs is critical for optic nerve (ON) development and maintenance. Methods The visual behavior of CASK+/− mice was assessed and electroretinography (ERG) was performed. Using a mouse line with a floxed CASK gene that expresses approximately 40% CASK globally in all cells (hypomorph) under hemizygous and homozygous conditions, we investigated effects of CASK reduction on the retina and ON. CASK then was completely deleted from RGCs to examine its cell-autonomous role. Finally, for the first time to our knowledge, we describe a hemizygous CASK missense mutation in a boy with ONH. Results CASK+/− heterozygous mutant mice display reduced visual contrast sensitivity, but ERG is indistinguishable from wildtype. CASK hypomorph mice exhibit ONH, but deletion of CASK from RGCs in this background does not exacerbate the condition. The boy with ONH harbors a missense mutation (p.Pro673Leu) that destabilizes CASK and weakens the crucial CASK–neurexin interaction. Conclusions Our results demonstrate that mosaic or global reduction in CASK expression and/or function disproportionately affects RGCs. CASK expression in RGCs does not appear critical for cell survival, indicating a noncell autonomous role for CASK in the development of ON.
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Affiliation(s)
- Alicia Kerr
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States.,Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Paras A Patel
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States.,Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, Virginia, United States
| | - Leslie E W LaConte
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States.,Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, United States
| | - Chen Liang
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States
| | - Ching-Kang Chen
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
| | - Veeral Shah
- Department of Ophthalmology, Baylor College of Medicine, Houston, Texas, United States.,Texas Children's Hospital, Houston, Texas, United States
| | - Michael A Fox
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States.,Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, United States.,Department of Pediatrics, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, United States
| | - Konark Mukherjee
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, United States.,Department of Psychiatry and Behavioral Medicine, Virginia Tech Carilion School of Medicine, Roanoke, Virginia, United States
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