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Fu Z, Qiu C, Cagnone G, Tomita Y, Huang S, Cakir B, Kotoda Y, Allen W, Bull E, Akula JD, Joyal JS, Hellström A, Talukdar S, Smith LEH. Retinal glial remodeling by FGF21 preserves retinal function during photoreceptor degeneration. iScience 2021; 24:102376. [PMID: 33937726 PMCID: PMC8079476 DOI: 10.1016/j.isci.2021.102376] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/13/2021] [Accepted: 03/25/2021] [Indexed: 12/18/2022] Open
Abstract
The group of retinal degenerations, retinitis pigmentosa (RP), comprises more than 150 genetic abnormalities affecting photoreceptors. Finding degenerative pathways common to all genetic abnormalities may allow general treatment such as neuroprotection. Neuroprotection may include enhancing the function of cells that directly support photoreceptors, retinal pigment epithelial cells, and Müller glia. Treatment with fibroblast growth factor 21 (FGF21), a neuroprotectant, from postnatal week 4-10, during rod and cone loss in P23H mice (an RP model) with retinal degeneration, preserved photoreceptor function and normalized Müller glial cell morphology. Single-cell transcriptomics of retinal cells showed that FGF21 receptor Fgfr1 was specifically expressed in Müller glia/astrocytes. Of all retinal cells, FGF21 predominantly affected genes in Müller glia/astrocytes with increased expression of axon development and synapse formation pathway genes. Therefore, enhancing retinal glial axon and synapse formation with neurons may preserve retinal function in RP and may suggest a general therapeutic approach for retinal degenerative diseases.
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Affiliation(s)
- Zhongjie Fu
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,The Manton Center for Orphan Disease, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Chenxi Qiu
- Department of Medicine, Division of Translational Therapeutics, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Gael Cagnone
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, Qc H3A 0C4, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc H3A 0C4, Canada
| | - Yohei Tomita
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Shuo Huang
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Bertan Cakir
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Yumi Kotoda
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - William Allen
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Edward Bull
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - James D Akula
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jean-Sébastien Joyal
- Department of Pediatrics, Pharmacology and Ophthalmology, CHU Sainte-Justine Research Center, Université de Montréal, Montreal, Qc H3A 0C4, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montreal, Qc H3A 0C4, Canada
| | - Ann Hellström
- Section for Ophthalmology, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Göteborg 405 30, Sweden
| | - Saswata Talukdar
- Cardiometabolic Diseases, Merck Research Laboratories, 33 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Lois E H Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Park SJ, Woon QTS, Er JC, Wong BH, Liu X, Kang NY, Barathi VA, Silver DL, Chang YT. Application of Neuron-Selective Fluorescent Probe, NeuA, To Identify Mouse Retinal Degeneration. Chembiochem 2021; 22:1915-1919. [PMID: 33617145 DOI: 10.1002/cbic.202100011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 02/20/2021] [Indexed: 11/09/2022]
Abstract
The retina is part of the central nerve system (CNS) and has various interneurons and sensory neurons such as photoreceptor cells. Retinitis pigmentosa (RP) is an inherited condition that is characterized by photoreceptor degeneration. Herein, we developed a fluorescent probe-NeuA-for detecting retinal neuronal cells and applied NeuA to discriminate between healthy and RP retinas. The staining pattern of NeuA in the retinas of healthy and RP mouse models was examined in vitro, ex vivo and in vivo using confocal microscopy, the fluorescent fundus microscopy and optical coherent tomography (OCT). NeuA strongly stained the outer segment layer of photoreceptor cells and some bipolar cells in the healthy retina, but there was only weak staining in the photoreceptor degenerated retinas. Therefore, NeuA probe can be used as the detecting RP tools in the preclinical conditions.
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Affiliation(s)
- Sung-Jin Park
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, 138667, Republic of Singapore
| | - Queenie Tan Shu Woon
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore, 169856, Republic of Singapore
| | - Jun Cheng Er
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, 138667, Republic of Singapore
| | - Bernice H Wong
- Program in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, 169857, Republic of Singapore
| | - Xiao Liu
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Nam-Young Kang
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, 138667, Republic of Singapore.,Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Veluchamy A Barathi
- Singapore Eye Research Institute, Singapore, 169856, Republic of Singapore.,Eye-ACP, Duke-NUS Graduate Medical School, Singapore, 169857, Republic of Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Republic of Singapore
| | - David L Silver
- Program in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore, 169857, Republic of Singapore
| | - Young-Tae Chang
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research, Singapore, 138667, Republic of Singapore.,Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.,Center for Self-assembly and Complexity, Institute for Basic Science (IBS), Pohang, 37673, Republic of Korea
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Krishnamoorthy V, Cherukuri P, Poria D, Goel M, Dagar S, Dhingra NK. Retinal Remodeling: Concerns, Emerging Remedies and Future Prospects. Front Cell Neurosci 2016; 10:38. [PMID: 26924962 PMCID: PMC4756099 DOI: 10.3389/fncel.2016.00038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 02/01/2016] [Indexed: 12/21/2022] Open
Abstract
Deafferentation results not only in sensory loss, but also in a variety of alterations in the postsynaptic circuitry. These alterations may have detrimental impact on potential treatment strategies. Progressive loss of photoreceptors in retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration, leads to several changes in the remnant retinal circuitry. Müller glial cells undergo hypertrophy and form a glial seal. The second- and third-order retinal neurons undergo morphological, biochemical and physiological alterations. A result of these alterations is that retinal ganglion cells (RGCs), the output neurons of the retina, become hyperactive and exhibit spontaneous, oscillatory bursts of spikes. This aberrant electrical activity degrades the signal-to-noise ratio in RGC responses, and thus the quality of information they transmit to the brain. These changes in the remnant retina, collectively termed “retinal remodeling”, pose challenges for genetic, cellular and bionic approaches to restore vision. It is therefore crucial to understand the nature of retinal remodeling, how it affects the ability of remnant retina to respond to novel therapeutic strategies, and how to ameliorate its effects. In this article, we discuss these topics, and suggest that the pathological state of the retinal output following photoreceptor loss is reversible, and therefore, amenable to restorative strategies.
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Affiliation(s)
| | - Pitchaiah Cherukuri
- Developmental Neurobiology Laboratory, European Neuroscience Institute Göttingen Göttingen, Germany
| | - Deepak Poria
- National Brain Research Centre Manesar, Haryana, India
| | - Manvi Goel
- National Brain Research Centre Manesar, Haryana, India
| | - Sushma Dagar
- Institute of Neuro- and Sensory Physiology, Heinrich-Heine University Düsseldorf, Germany
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Yang J, Nan C, Ripps H, Shen W. Destructive Changes in the Neuronal Structure of the FVB/N Mouse Retina. PLoS One 2015; 10:e0129719. [PMID: 26091175 PMCID: PMC4475023 DOI: 10.1371/journal.pone.0129719] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 05/12/2015] [Indexed: 11/18/2022] Open
Abstract
We applied a series of selective antibodies for labeling the various cell types in the mammalian retina. These were used to identify the progressive loss of neurons in the FVB/N mouse, a model of early onset retinal degeneration produced by a mutation in the pde6b gene. The immunocytochemical studies, together with electroretinogram (ERG) recordings, enabled us to examine the time course of the degenerative changes that extended from the photoreceptors to the ganglion cells at the proximal end of the retina. Our study indicates that photoreceptors in FVB/N undergo a rapid degeneration within three postnatal weeks, and that there is a concomitant loss of retinal neurons in the inner nuclear layer. Although the loss of rods was detected at an earlier age during which time M- and S-opsin molecules were translocated to the cone nuclei; by 6 months all cones had also degenerated. Neuronal remodeling was also seen in the second-order neurons with horizontal cells sprouting processes proximally and dendritic retraction in rod-driven bipolar cells. Interestingly, the morphology of cone-driven bipolar cells were affected less by the disease process. The cellular structure of inner retinal neurons, i.e., ChAT amacrine cells, ganglion cells, and melanopsin-positive ganglion cells did not exhibit any gross changes of cell densities and appeared to be relatively unaffected by the massive photoreceptor degeneration in the distal retina. However, Muller cell processes began to express GFAP at their endfeet at p14, and it climbed progressively to the cell’s distal ends by 6 months. Our study indicates that FVB/N mouse provides a useful model with which to assess possible intervention strategies to arrest photoreceptor death in related diseases.
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Affiliation(s)
- Jinnan Yang
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States of America
| | - ChangLong Nan
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States of America
| | - Harris Ripps
- Marine Biological Laboratory, Woods Hole 02543, United States of America
| | - Wen Shen
- Department of Biomedical Science, Charles E Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33431, United States of America
- * E-mail:
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Cuenca N, Fernández-Sánchez L, Campello L, Maneu V, De la Villa P, Lax P, Pinilla I. Cellular responses following retinal injuries and therapeutic approaches for neurodegenerative diseases. Prog Retin Eye Res 2014; 43:17-75. [PMID: 25038518 DOI: 10.1016/j.preteyeres.2014.07.001] [Citation(s) in RCA: 296] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 01/17/2023]
Abstract
Retinal neurodegenerative diseases like age-related macular degeneration, glaucoma, diabetic retinopathy and retinitis pigmentosa each have a different etiology and pathogenesis. However, at the cellular and molecular level, the response to retinal injury is similar in all of them, and results in morphological and functional impairment of retinal cells. This retinal degeneration may be triggered by gene defects, increased intraocular pressure, high levels of blood glucose, other types of stress or aging, but they all frequently induce a set of cell signals that lead to well-established and similar morphological and functional changes, including controlled cell death and retinal remodeling. Interestingly, an inflammatory response, oxidative stress and activation of apoptotic pathways are common features in all these diseases. Furthermore, it is important to note the relevant role of glial cells, including astrocytes, Müller cells and microglia, because their response to injury is decisive for maintaining the health of the retina or its degeneration. Several therapeutic approaches have been developed to preserve retinal function or restore eyesight in pathological conditions. In this context, neuroprotective compounds, gene therapy, cell transplantation or artificial devices should be applied at the appropriate stage of retinal degeneration to obtain successful results. This review provides an overview of the common and distinctive features of retinal neurodegenerative diseases, including the molecular, anatomical and functional changes caused by the cellular response to damage, in order to establish appropriate treatments for these pathologies.
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Affiliation(s)
- Nicolás Cuenca
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain; Multidisciplinary Institute for Environmental Studies "Ramon Margalef", University of Alicante, Alicante, Spain.
| | - Laura Fernández-Sánchez
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Laura Campello
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Victoria Maneu
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Pedro De la Villa
- Department of Systems Biology, University of Alcalá, Alcalá de Henares, Spain
| | - Pedro Lax
- Department of Physiology, Genetics and Microbiology, University of Alicante, Alicante, Spain
| | - Isabel Pinilla
- Department of Ophthalmology, Lozano Blesa University Hospital, Aragon Institute of Health Sciences, Zaragoza, Spain
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6
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Zheng L, Yan Y, An J, Zhang L, Liu W, Xia F, Zhang Z. Retinal horizontal cells reduced in a rat model of congenital stationary night blindness. Neurosci Lett 2012; 521:26-30. [DOI: 10.1016/j.neulet.2012.05.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Revised: 04/29/2012] [Accepted: 05/16/2012] [Indexed: 10/28/2022]
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Abstract
Retinal photoreceptor degeneration takes many forms. Mutations in rhodopsin genes or disorders of the retinal pigment epithelium, defects in the adenosine triphosphate binding cassette transporter, ABCR gene defects, receptor tyrosine kinase defects, ciliopathies and transport defects, defects in both transducin and arrestin, defects in rod cyclic guanosine 3',5'-monophosphate phosphodiesterase, peripherin defects, defects in metabotropic glutamate receptors, synthetic enzymatic defects, defects in genes associated with signaling, and many more can all result in retinal degenerative disease like retinitis pigmentosa (RP) or RP-like disorders. Age-related macular degeneration (AMD) and AMD-like disorders are possibly due to a constellation of potential gene targets and gene/gene interactions, while other defects result in diabetic retinopathy or glaucoma. However, all of these insults as well as traumatic insults to the retina result in retinal remodeling. Retinal remodeling is a universal finding subsequent to retinal degenerative disease that results in deafferentation of the neural retina from photoreceptor input as downstream neuronal elements respond to loss of input with negative plasticity. This negative plasticity is not passive in the face of photoreceptor degeneration, with a phased revision of retinal structure and function found at the molecular, synaptic, cell, and tissue levels involving all cell classes in the retina, including neurons and glia. Retinal remodeling has direct implications for the rescue of vision loss through bionic or biological approaches, as circuit revision in the retina corrupts any potential surrogate photoreceptor input to a remnant neural retina. However, there are a number of potential opportunities for intervention that are revealed through the study of retinal remodeling, including therapies that are designed to slow down photoreceptor loss, interventions that are designed to limit or arrest remodeling events, and optogenetic approaches that target appropriate classes of neurons in the remnant neural retina.
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8
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Lin Y, Jones BW, Liu A, Vazquéz-Chona FR, Lauritzen JS, Ferrell WD, Marc RE. Rapid glutamate receptor 2 trafficking during retinal degeneration. Mol Neurodegener 2012; 7:7. [PMID: 22325330 PMCID: PMC3296582 DOI: 10.1186/1750-1326-7-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 02/10/2012] [Indexed: 01/03/2023] Open
Abstract
Background Retinal degenerations, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP), are characterized by photoreceptor loss and anomalous remodeling of the surviving retina that corrupts visual processing and poses a barrier to late-stage therapeutic interventions in particular. However, the molecular events associated with retinal remodeling remain largely unknown. Given our prior evidence of ionotropic glutamate receptor (iGluR) reprogramming in retinal degenerations, we hypothesized that the edited glutamate receptor 2 (GluR2) subunit and its trafficking may be modulated in retinal degenerations. Results Adult albino Balb/C mice were exposed to intense light for 24 h to induce light-induced retinal degeneration (LIRD). We found that prior to the onset of photoreceptor loss, protein levels of GluR2 and related trafficking proteins, including glutamate receptor-interacting protein 1 (GRIP1) and postsynaptic density protein 95 (PSD-95), were rapidly increased. LIRD triggered neuritogenesis in photoreceptor survival regions, where GluR2 and its trafficking proteins were expressed in the anomalous dendrites. Immunoprecipitation analysis showed interaction between KIF3A and GRIP1 as well as PSD-95, suggesting that KIF3A may mediate transport of GluR2 and its trafficking proteins to the novel dendrites. However, in areas of photoreceptor loss, GluR2 along with its trafficking proteins nearly vanished in retracted retinal neurites. Conclusions All together, LIRD rapidly triggers GluR2 plasticity, which is a potential mechanism behind functionally phenotypic revisions of retinal neurons and neuritogenesis during retinal degenerations.
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Affiliation(s)
- Yanhua Lin
- Department of Ophthalmology, John A, Moran Eye Center, University of Utah School of Medicine, 65 Mario Capecchi Drive, Salt Lake City, UT 84132, USA
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Scott PA, Kaplan HJ, Sandell JH. Anatomical evidence of photoreceptor degeneration induced by iodoacetic acid in the porcine eye. Exp Eye Res 2011; 93:513-27. [PMID: 21740901 DOI: 10.1016/j.exer.2011.06.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 06/11/2011] [Accepted: 06/22/2011] [Indexed: 01/31/2023]
Abstract
Iodoacetic acid (IAA) induces photoreceptor (PR) degeneration in small animal models, however, eye size and anatomic differences detract from the usefulness of these models for studying retinal rescue strategies intended for humans. Porcine eyes are closer in size to human eyes and have a rich supply of rod and cones. This study investigated whether IAA also produced PR degeneration in the porcine retina, whether the damage was preferential for rods or cones, and whether IAA induced remodeling of the inner retina. Pigs were given a single i.v. injection of IAA and were euthanized 2-5 weeks later. Eyes were enucleated and immersed in fixative. Forty-six eyes were studied: Control (n = 13), and from pigs that had received the following IAA doses: 5.0 mg/kg (n = 7); 7.5 mg/kg (n = 10); 10.0 mg/kg (n = 6); 12.0 mg/kg (n = 6). Tissue was retrieved from four retinal locations: 8 mm and 2 mm above the dorsal margin of the optic disc, and 2 mm and 8 mm below the disc, and was processed for conventional histology, immunohistochemistry, and transmission electron microscopy. At 5.0 mg/kg IAA produced mild, variable cell loss, but remaining cells exhibited normal features. At doses above 5.0 mg/kg, a dose-dependent reduction was observed in the length of PR inner and outer segments, and in the number of PR nuclei. Specific labeling revealed a massive dropout of rod cell bodies with relative sparing of cone cell bodies, and electron microscopy revealed a reduction in the number of PR synaptic terminals. Mild dendritic retraction of rod bipolar cells and hypertrophy of Müller cell stalks was also observed, although the inner nuclear layer appeared intact. The porcine IAA model may be useful for developing and testing retinal rescue strategies for human diseases in which rods are more susceptible than cones, or are affected earlier in the disease process.
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Affiliation(s)
- Patrick A Scott
- Department of Anatomy & Neurobiology, Boston University School of Medicine, Boston, MA 02118, USA.
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10
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Abstract
In the mammalian retina, excitatory and inhibitory circuitries enable retinal ganglion cells (RGCs) to signal the occurrence of visual features to higher brain areas. This functionality disappears in certain diseases of retinal degeneration because of the progressive loss of photoreceptors. Recent work in a mouse model of retinal degeneration (rd1) found that, although some intraretinal circuitry is preserved and RGCs maintain characteristic physiological properties, they exhibit increased and aberrant rhythmic activity. Here, extracellular recordings were made to assess the degree of aberrant activity in adult rd1 retinas and to investigate the mechanism underlying such behavior. A multi-transistor array with thousands of densely packed sensors allowed for simultaneous recordings of spiking activity in populations of RGCs and of local field potentials (LFPs). The majority of identified RGCs displayed rhythmic (7-10 Hz) but asynchronous activity. The spiking activity correlated with the LFPs, which reflect an average synchronized excitatory input to the RGCs. LFPs initiated from random positions and propagated across the retina. They disappeared when ionotrophic glutamate receptors or electrical synapses were blocked. They persisted in the presence of other pharmacological blockers, including TTX and inhibitory receptor antagonists. Our results suggest that excitation-transmitted laterally through a network of electrically coupled interneurons-leads to large-scale retinal network oscillations, reflected in the rhythmic spiking of most rd1 RGCs. This result may explain forms of photopsias reported by blind patients, while the mechanism involved should be considered in future treatment strategies targeting the disease of retinitis pigmentosa.
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11
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Early remodeling in an inducible animal model of retinal degeneration. Neuroscience 2009; 160:517-29. [PMID: 19272416 DOI: 10.1016/j.neuroscience.2009.02.056] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/25/2009] [Accepted: 02/25/2009] [Indexed: 01/02/2023]
Abstract
Photoreceptor degeneration is followed by significant morphological changes in the second-order retinal neurons in humans and in several genetic animal models. However, it is not clear whether similar changes occur when photoreceptor degeneration is induced nongenetically, raising the question whether these changes are a general effect of deafferentation independent of the cause of degeneration. We addressed this by inducing selective photoreceptor degeneration with N-methyl-N-nitrosourea (MNU) and studying its effects on inner retinal neurons in a mouse for up to 3 months, using immunocytochemistry and iontophoretic labeling. To develop objective measures of photoreceptor degeneration and of retinal remodeling, we measured several retinal proteins using immunoblot analysis, and quantified gross visual ability of the animal in a visual cliff test. The MNU-induced progressive degeneration of rods and cones was associated with declining levels of postsynaptic density 95 protein in the retina, and with deteriorating visual performance of the animal. Müller glial cells showed enhanced reactivity for glial fibrillary acidic protein as demonstrated by immunocytochemistry, which also reflected in increased levels of the protein as demonstrated by immunoblotting. Horizontal cells and rod bipolar cells progressively lost their dendritic processes, which correlated with a slight decline in the levels of calbindin and protein kinase C alpha respectively. Horizontal cell axons, immunoreactive for nonphosphorylated neurofilaments, showed sprouting into the inner nuclear layer. Ganglion cells and their synaptic inputs, probed by immunolocalizing beta-III-tubulin, neurofilaments, bassoon and synaptophysin, appeared to be unaffected. These results demonstrate that MNU-induced photoreceptor degeneration leads to retinal remodeling similar to that observed in genetic models, suggesting that the remodeling does not depend on the etiopathology that underlies photoreceptor degeneration.
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The absence of the clathrin-dependent endocytosis in rod bipolar cells of the FVB/N mouse retina. Neurosci Lett 2008; 439:165-9. [PMID: 18514403 DOI: 10.1016/j.neulet.2008.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Revised: 04/10/2008] [Accepted: 05/01/2008] [Indexed: 11/21/2022]
Abstract
The high rate of exocytosis at the ribbon synapses is balanced by following compensatory endocytosis. Unlike conventional synaptic terminals where clathrin-mediated endocytosis (CME) is a predominant mechanism for membrane retrieval, CME is thought to be only a minor mechanism of endocytosis at the retinal ribbon synapses, but CME is present there and it works. We examined the clathrin expression in the FVB/N rd1 mouse, which is an animal model of retinitis pigmentosa. The broadly distributed pattern of clathrin immunoreactivity in the inner plexiform layer was similar in both the control and FVB/N mouse retinas, but the immunoreactive punta within the rod bipolar axon terminals located in the proximal IPL were decreased in number and reduced in size at postnatal days 14 and they came to disappear at postnatal days 21. This preferential decrease of the clathrin expression at ribbon synapses in the rod bipolar cell axon terminals of the FVB/N mouse retina demonstrates another plastic change after photoreceptor degeneration and this suggests that clathrin may be important for normal synaptic function at the rod bipolar ribbon synapses in the mammalian retina.
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13
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Lee EJ, Padilla M, Merwine DK, Grzywacz NM. Developmental regulation of the morphology of mouse retinal horizontal cells by visual experience. Eur J Neurosci 2008; 27:1423-31. [DOI: 10.1111/j.1460-9568.2008.06122.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Jones BW, Marc RE, Watt CB, Vaughan DK, Organisciak DT. Neural plasticity revealed by light-induced photoreceptor lesions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 572:405-10. [PMID: 17249603 DOI: 10.1007/0-387-32442-9_57] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Bryan W Jones
- Ophthalmology, Univ Utah/Moran Eye Center, Salt Lake City, UT, USA
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15
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Raven MA, Oh ECT, Swaroop A, Reese BE. Afferent control of horizontal cell morphology revealed by genetic respecification of rods and cones. J Neurosci 2007; 27:3540-7. [PMID: 17392470 PMCID: PMC6672121 DOI: 10.1523/jneurosci.0372-07.2007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The first inhibitory interneurons of the retina, the horizontal cells, stratify within the outer plexiform layer, extending dendritic terminals that connect to the pedicles of cone photoreceptors and an axon terminal system contacting the spherules of rod photoreceptors. How the horizontal cells acquire this morphology is unknown, but instructive interactions with afferents are suggested to play a role in the development of synaptic circuits. Here, we show that the morphology of the axon terminal system and the dendritic field are selectively regulated by innervation from their respective afferents: genetic respecification of all cones to become rods, in Crxp-Nrl transgenic mice, produces an atrophic dendritic field yet leaves the axon terminal system largely intact. In contrast, in the retinas of Nrl-/- mice, in which the population of rod photoreceptors is respecified to adopt a cone fate, the dendritic field is hypertrophic, whereas the axon terminal system is underdeveloped. Our studies reveal that, although cell-intrinsic mechanisms drive the formation of independent dendritic versus axonal domains, the afferents play a selectively instructive role in defining their respective morphologies.
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Affiliation(s)
| | - Edwin C. T. Oh
- Program in Neuroscience and
- Departments of Ophthalmology and Visual Sciences and
| | - Anand Swaroop
- Program in Neuroscience and
- Departments of Ophthalmology and Visual Sciences and
- Human Genetics, University of Michigan, Ann Arbor, Michigan 48105
| | - Benjamin E. Reese
- Neuroscience Research Institute and
- Department of Psychology, University of California at Santa Barbara, Santa Barbara, California 93106, and
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16
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Jones BW, Watt CB, Marc RE. Retinal remodelling. Clin Exp Optom 2006; 88:282-91. [PMID: 16255687 DOI: 10.1111/j.1444-0938.2005.tb06712.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2005] [Revised: 07/01/2005] [Accepted: 07/15/2005] [Indexed: 11/27/2022] Open
Abstract
Retinal degenerative diseases that progress through loss of photoreceptors initiate a sequence of events that culminates in negative remodelling of the retina. Initially, photoreceptor loss ablates glutamatergic signalling to the neural retina and eliminates coordinate Ca++-coupled homeostatic signalling. Retinal neurons react to this loss of glutamatergic input through retinal rewiring and migration of neurons throughout the axis of the retina. All diseases that kill photoreceptors trigger retinal remodelling as the final common pathway and cell death is a common feature. Retinal remodelling resembles CNS pathologic remodelling and constitutes a major challenge to all rescue strategies.
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Affiliation(s)
- Bryan W Jones
- Moran Eye Center, 75 N Medical Drive, Salt Lake City, Utah, 84132, USA.
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Cuenca N, Pinilla I, Sauvé Y, Lund R. Early changes in synaptic connectivity following progressive photoreceptor degeneration in RCS rats. Eur J Neurosci 2006; 22:1057-72. [PMID: 16176347 DOI: 10.1111/j.1460-9568.2005.04300.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Royal College of Surgeons (RCS) rat has a retinal pigment epithelial cell defect that causes progressive loss of photoreceptors. Although it is extensively used in retinal degeneration and repair studies, how photoreceptor degeneration affects retinal circuitry has not been fully explored. This study examined the changes in synaptic connectivity between photoreceptors and their target cells using immunocytochemistry and correlated these changes with retinal function using the electroretinogram (ERG). Immunostaining with bassoon and synaptophysin (as presynaptic markers) and metabotropic glutamate receptor (mGluR6, a postsynaptic marker for ON-bipolar dendrites) was already impaired at postnatal day (P) 21 and progressively lost with infrequent pairing of presynaptic and postsynaptic elements at P60. By P90 to P120, staining became increasingly patchy and was eventually restricted to sparsely and irregularly distributed foci in which the normal pairing of presynaptic and postsynaptic markers was lost. ERG results showed that mixed scotopic a-waves and b-waves were already reduced by P21 but not oscillatory potentials. While cone-driven responses (photopic b-wave) reached normal levels at P30, they were impaired by P60 but could still be recorded at P120, although with reduced amplitude; rod responses never reached normal amplitudes. Thus, only cone-driven activity attained normal levels, but declined rapidly thereafter. In conclusion, the synaptic markers associated with photoreceptors and processes of bipolar and horizontal cells show abnormalities prior to significant photoreceptor loss. These changes are paralleled with the deterioration of specific aspects of ERG responsiveness with age. Besides providing information on the effects of photoreceptor dysfunction and loss on connection patterns in the retina, the work addresses the more general issue of how disorder of input neurons affects downstream circuitry.
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Affiliation(s)
- Nicolás Cuenca
- Moran Eye Center, Ophthalmology and Visual Sciences, 75 North Medical Dr, University of Utah, 84132 Salt Lake City, Utah, USA
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18
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Sharma RK, O'Leary TE, Fields CM, Johnson DA. Development of the outer retina in the mouse. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 145:93-105. [PMID: 14519497 DOI: 10.1016/s0165-3806(03)00217-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mice represent a valuable species for studies of development and disease. With the availability of transgenic models for retinal degeneration in this species, information regarding development and structure of mouse retina has become increasingly important. Of special interest is the differentiation and synaptogenesis of photoreceptors since these cells are predominantly involved in hereditary retinal degenerations. Thus, some of the keys to future clinical management of these retinal diseases may lie in understanding the molecular mechanisms of outer retinal development. In this study, we describe the expression of markers for photoreceptors (recoverin), horizontal cells (calbindin), bipolar cells (protein kinase C; PKC) and cytoskeletal elements pivotal to axonogenesis (beta-tubulin and actin) during perinatal development of mouse retina. Immunocytochemical localization of recoverin, calbindin, PKC and beta-tubulin was monitored in developing mouse retina (embryonic day (E) 18.5 to postnatal day (PN) 14), whereas f-actin was localized by Phalloidin binding. Recoverin immunoreactive cells, presumably the photoreceptors, were observed embryonically (E 18.5) and their number increased until PN 14. Neurite projections from the immunoreactive cells towards the outer plexiform layer (OPL) were noted at PN 0 and these processes reached the OPL at PN 7 coincident with histological evidence for the differentiation of the OPL. Outer segments, all the cell bodies in the ONL, as well as the OPL were immunoreactive to recoverin at PN 14. Calbindin immunoreactive horizontal cells were also present in E 18.5 retinas. These cells became progressively displaced proximally as the ONL developed. A calbindin immunoreactive plexus was seen in the OPL at PN 7. PKC immunoreactive bipolar cells developed postnatally, becoming distinguished at PN 7. Both beta-tubulin and actin immunoreactive cells were present in the IPL as early as E 18.5; however, appearance of processes labeled with these markers in the OPL was delayed until PN 7, concurrent with the first appearance of photoreceptor neurites, development of the horizontal cell plexus, and development of synaptophysin immunoreactivity at this location. These results provide a developmental timeframe for the expression of recoverin, calbindin, synaptophysin, beta-tubulin and actin. Our findings suggest that the time between PN 3 and PN 7 represents a critical period during which elements of the OPL are assembled.
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Affiliation(s)
- Rajesh K Sharma
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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19
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Abstract
Mammalian retinal degenerations initiated by gene defects in rods, cones or the retinal pigmented epithelium (RPE) often trigger loss of the sensory retina, effectively leaving the neural retina deafferented. The neural retina responds to this challenge by remodeling, first by subtle changes in neuronal structure and later by large-scale reorganization. Retinal degenerations in the mammalian retina generally progress through three phases. Phase 1 initiates with expression of a primary insult, followed by phase 2 photoreceptor death that ablates the sensory retina via initial photoreceptor stress, phenotype deconstruction, irreversible stress and cell death, including bystander effects or loss of trophic support. The loss of cones heralds phase 3: a protracted period of global remodeling of the remnant neural retina. Remodeling resembles the responses of many CNS assemblies to deafferentation or trauma, and includes neuronal cell death, neuronal and glial migration, elaboration of new neurites and synapses, rewiring of retinal circuits, glial hypertrophy and the evolution of a fibrotic glial seal that isolates the remnant neural retina from the surviving RPE and choroid. In early phase 2, stressed photoreceptors sprout anomalous neurites that often reach the inner plexiform and ganglion cell layers. As death of rods and cones progresses, bipolar and horizontal cells are deafferented and retract most of their dendrites. Horizontal cells develop anomalous axonal processes and dendritic stalks that enter the inner plexiform layer. Dendrite truncation in rod bipolar cells is accompanied by revision of their macromolecular phenotype, including the loss of functioning mGluR6 transduction. After ablation of the sensory retina, Müller cells increase intermediate filament synthesis, forming a dense fibrotic layer in the remnant subretinal space. This layer invests the remnant retina and seals it from access via the choroidal route. Evidence of bipolar cell death begins in phase 1 or 2 in some animal models, but depletion of all neuronal classes is evident in phase 3. As remodeling progresses over months and years, more neurons are lost and patches of the ganglion cell layer can become depleted. Some survivor neurons of all classes elaborate new neurites, many of which form fascicles that travel hundreds of microns through the retina, often beneath the distal glial seal. These and other processes form new synaptic microneuromas in the remnant inner nuclear layer as well as cryptic connections throughout the retina. Remodeling activity peaks at mid-phase 3, where neuronal somas actively migrate on glial surfaces. Some amacrine and bipolar cells move into the former ganglion cell layer while other amacrine cells are everted through the inner nuclear layer to the glial seal. Remodeled retinas engage in anomalous self-signaling via rewired circuits that might not support vision even if they could be driven anew by cellular or bionic agents. We propose that survivor neurons actively seek excitation as sources of homeostatic Ca(2+) fluxes. In late phase 3, neuron loss continues and the retina becomes increasingly glial in composition. Retinal remodeling is not plasticity, but represents the invocation of mechanisms resembling developmental and CNS plasticities. Together, neuronal remodeling and the formation of the glial seal may abrogate many cellular and bionic rescue strategies. However, survivor neurons appear to be stable, healthy, active cells and given the evidence of their reactivity to deafferentation, it may be possible to influence their emergent rewiring and migration habits.
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Affiliation(s)
- Robert E Marc
- John A. Moran Eye Center, Department of Ophthalmology, University of Utah School of Medicine, 50 N Medical Center, Salt Lake City, UT 84132, USA
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Strettoi E, Pignatelli V, Rossi C, Porciatti V, Falsini B. Remodeling of second-order neurons in the retina of rd/rd mutant mice. Vision Res 2003; 43:867-77. [PMID: 12668056 DOI: 10.1016/s0042-6989(02)00594-1] [Citation(s) in RCA: 163] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This is a brief review of data obtained by analyzing the morphology and the physiology of the retinas in rd/rd and normal, wt mice, aged 10-90 days. Second-order neurons of the rd/rd show abnormalities that start with the anomalous development of rod bipolar cells around P10 and culminate with the atrophy of dendrites in cone bipolar cells, mostly evident at P90. Horizontal cells remodel considerably. Cone-mediated ERGs, (recorded between 13 and 16 days of age) have reduced a-wave and b-wave amplitudes and longer b-wave latency and duration. B-wave abnormalities indicate specific postreceptoral dysfunction. Morphological and ERG changes in rd/rd retinas are consistent with substantial inner retinal remodeling associated to photoreceptor degeneration.
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Affiliation(s)
- Enrica Strettoi
- Laboratorio di Neurofisiologia, Istituto di Neuroscienze del CNR, Area della Ricerca, Via G. Moruzzi 1, 56100, Pisa, Italy.
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Park SJ, Oh SJ, Chung JW, Chun MH. Tolerance of horizontal cells to excitotoxicity in the developing FVB/N mouse retina. Neuroreport 2002; 13:2091-5. [PMID: 12438932 DOI: 10.1097/00001756-200211150-00020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigated the effect of L-glutamate on horizontal cell growth after postnatal photoreceptor degeneration in the developing FVB/N mouse retina, using immunocytochemistry with antisera against calbindin D-28 K (calbindin) or neurofilament 200 NE14. The numbers of horizontal cells and amount of axonal arborization in the outer plexiform layer were unchanged in FVB/N mice injected with L-glutamate. Instead, more numerous processes emerging from horizontal cells descended into the inner plexiform layer (IPL) and formed a loose network in stratum 1. Our results clearly demonstrate that horizontal cells are resistant to excitotoxicity by excessive glutamate, and that sprouting of horizontal cell axons into the IPL is potentiated by excessive glutamate in FVB/N mice as they mature.
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Affiliation(s)
- Sung-Jin Park
- Department of Anatomy, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea
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