1
|
Scalabrino ML, Thapa M, Wang T, Sampath AP, Chen J, Field GD. Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa. Nat Commun 2023; 14:8256. [PMID: 38086857 PMCID: PMC10716155 DOI: 10.1038/s41467-023-44063-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Retinitis pigmentosa is an inherited photoreceptor degeneration that begins with rod loss followed by cone loss. This cell loss greatly diminishes vision, with most patients becoming legally blind. Gene therapies are being developed, but it is unknown how retinal function depends on the time of intervention. To uncover this dependence, we utilize a mouse model of retinitis pigmentosa capable of artificial genetic rescue. This model enables a benchmark of best-case gene therapy by removing variables that complicate answering this question. Complete genetic rescue was performed at 25%, 50%, and 70% rod loss (early, mid and late, respectively). Early and mid treatment restore retinal output to near wild-type levels. Late treatment retinas exhibit continued, albeit slowed, loss of sensitivity and signal fidelity among retinal ganglion cells, as well as persistent gliosis. We conclude that gene replacement therapies delivered after 50% rod loss are unlikely to restore visual function to normal. This is critical information for administering gene therapies to rescue vision.
Collapse
Affiliation(s)
- Miranda L Scalabrino
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Mishek Thapa
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Tian Wang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alapakkam P Sampath
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Greg D Field
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, CA, USA.
- Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA.
| |
Collapse
|
2
|
Patel SH, Lamba DA. Factors Affecting Stem Cell-Based Regenerative Approaches in Retinal Degeneration. Annu Rev Vis Sci 2023; 9:155-175. [PMID: 37713278 DOI: 10.1146/annurev-vision-120222-012817] [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: 09/17/2023]
Abstract
Inherited and age-associated vision loss is often associated with degeneration of the cells of the retina, the light-sensitive layer at the back of the eye. The mammalian retina, being a postmitotic neural tissue, does not have the capacity to repair itself through endogenous regeneration. There has been considerable excitement for the development of cell replacement approaches since the isolation and development of culture methods for human pluripotent stem cells, as well as the generation of induced pluripotent stem cells. This has now been combined with novel three-dimensional organoid culture systems that closely mimic human retinal development in vitro. In this review, we cover the current state of the field, with emphasis on the cell delivery challenges, role of the recipient immunological microenvironment, and challenges related to connectivity between transplanted cells and host circuitry both locally and centrally to the different areas of the brain.
Collapse
Affiliation(s)
- Sachin H Patel
- Department of Ophthalmology, University of California, San Francisco, California, USA;
| | - Deepak A Lamba
- Department of Ophthalmology, University of California, San Francisco, California, USA;
- Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, University of California, San Francisco, California, USA
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Hagiwara A, Mizutani A, Kawamura S, Abe M, Hida Y, Sakimura K, Ohtsuka T. Critical Role of the Presynaptic Protein CAST in Maintaining the Photoreceptor Ribbon Synapse Triad. Int J Mol Sci 2023; 24:ijms24087251. [PMID: 37108413 PMCID: PMC10138387 DOI: 10.3390/ijms24087251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 04/08/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
The cytomatrix at the active zone-associated structural protein (CAST) and its homologue, named ELKS, being rich in glutamate (E), leucine (L), lysine (K), and serine (S), belong to a family of proteins that organize presynaptic active zones at nerve terminals. These proteins interact with other active zone proteins, including RIMs, Munc13s, Bassoon, and the β subunit of Ca2+ channels, and have various roles in neurotransmitter release. A previous study showed that depletion of CAST/ELKS in the retina causes morphological changes and functional impairment of this structure. In this study, we investigated the roles of CAST and ELKS in ectopic synapse localization. We found that the involvement of these proteins in ribbon synapse distribution is complex. Unexpectedly, CAST and ELKS, in photoreceptors or in horizontal cells, did not play a major role in ribbon synapse ectopic localization. However, depletion of CAST and ELKS in the mature retina resulted in degeneration of the photoreceptors. These findings suggest that CAST and ELKS play critical roles in maintaining neural signal transduction in the retina, but the regulation of photoreceptor triad synapse distribution is not solely dependent on their actions within photoreceptors and horizontal cells.
Collapse
Affiliation(s)
- Akari Hagiwara
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Ayako Mizutani
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
| | - Saki Kawamura
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba 278-8510, Japan
| | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Yamato Hida
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Toshihisa Ohtsuka
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| |
Collapse
|
5
|
Scalabrino ML, Thapa M, Wang T, Sampath AP, Chen J, Field GD. Late gene therapy limits the restoration of retinal function in a mouse model of retinitis pigmentosa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.07.536035. [PMID: 37066264 PMCID: PMC10104154 DOI: 10.1101/2023.04.07.536035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Retinitis pigmentosa is an inherited photoreceptor degeneration that begins with rod loss followed by cone loss and eventual blindness. Gene therapies are being developed, but it is unknown how retinal function depends on the time of intervention. To uncover this dependence, we utilized a mouse model of retinitis pigmentosa capable of artificial genetic rescue. This model enables a benchmark of best-case gene therapy by removing the variables that complicate the ability to answer this vital question. Complete genetic rescue was performed at 25%, 50%, and 70% rod loss (early, mid and late, respectively). Early and mid treatment restored retinal function to near wild-type levels, specifically the sensitivity and signal fidelity of retinal ganglion cells (RGCs), the 'output' neurons of the retina. However, some anatomical defects persisted. Late treatment retinas exhibited continued, albeit slowed, loss of sensitivity and signal fidelity among RGCs, as well as persistent gliosis. We conclude that gene replacement therapies delivered after 50% rod loss are unlikely to restore visual function to normal. This is critical information for administering gene therapies to rescue vision.
Collapse
Affiliation(s)
- Miranda L Scalabrino
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
| | - Mishek Thapa
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
| | - Tian Wang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles CA
| | - Alapakkam P Sampath
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
| | - Jeannie Chen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles CA
| | - Greg D Field
- Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles CA
- Department of Neurobiology, Duke University School of Medicine, Durham NC
| |
Collapse
|
6
|
Leinonen H, Fu Z, Bull E. Neural and Müller glial adaptation of the retina to photoreceptor degeneration. Neural Regen Res 2023; 18:701-707. [DOI: 10.4103/1673-5374.354511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
7
|
Fei Z, Fei F, Huan Y, Wu XQ, Chen T, Dou YN, Jia B, He X, Wei DY. Necroptosis plays a crucial role in the exacerbation of retinal injury after blunt ocular trauma. Neural Regen Res 2023; 18:922-928. [DOI: 10.4103/1673-5374.353848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
8
|
Hanineva A, Park KS, Wang JJ, DeAngelis MM, Farkas MH, Zhang SX. Emerging roles of circular RNAs in retinal diseases. Neural Regen Res 2022; 17:1875-1880. [PMID: 35142661 PMCID: PMC8848606 DOI: 10.4103/1673-5374.335691] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Retinal disorders are a group of ocular diseases whose onset is associated with a number of aberrant molecular and cellular processes or physical damages that affect retinal structure and function resulting in neural and vascular degeneration in the retina. Current research has primarily focused on delaying retinal disease with minimal success in preventing or reversing neuronal degeneration. In this review, we explore a relatively new field of research involving circular RNAs, whose potential roles as biomarkers and mediators of retinal disease pathogenesis have only just emerged. While knowledge of circular RNAs function is limited given its novelty, current evidence has highlighted their roles as modulators of microRNAs, regulators of gene transcription, and biomarkers of disease development and progression. Here, we summarize how circular RNAs may be implicated in the pathogenesis of common retinal diseases including diabetic retinopathy, glaucoma, proliferative vitreoretinopathy, and age-related macular degeneration. Further, we explore the potential of circular RNAs as novel biomarkers and therapeutic targets for the diagnosis and treatment of retinal diseases.
Collapse
Affiliation(s)
- Aneliya Hanineva
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Karen Sophia Park
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Joshua J Wang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Margaret M DeAngelis
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York; Research Service, Veterans Administration Western New York Healthcare System, Buffalo, NY, USA
| | - Michael H Farkas
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York; Research Service, Veterans Administration Western New York Healthcare System; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| |
Collapse
|
9
|
Ahmed M, Kojima Y, Masai I. Strip1 regulates retinal ganglion cell survival by suppressing Jun-mediated apoptosis to promote retinal neural circuit formation. eLife 2022; 11:74650. [PMID: 35314028 PMCID: PMC8940179 DOI: 10.7554/elife.74650] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 02/04/2022] [Indexed: 12/13/2022] Open
Abstract
In the vertebrate retina, an interplay between retinal ganglion cells (RGCs), amacrine (AC), and bipolar (BP) cells establishes a synaptic layer called the inner plexiform layer (IPL). This circuit conveys signals from photoreceptors to visual centers in the brain. However, the molecular mechanisms involved in its development remain poorly understood. Striatin-interacting protein 1 (Strip1) is a core component of the striatin-interacting phosphatases and kinases (STRIPAK) complex, and it has shown emerging roles in embryonic morphogenesis. Here, we uncover the importance of Strip1 in inner retina development. Using zebrafish, we show that loss of Strip1 causes defects in IPL formation. In strip1 mutants, RGCs undergo dramatic cell death shortly after birth. AC and BP cells subsequently invade the degenerating RGC layer, leading to a disorganized IPL. Mechanistically, zebrafish Strip1 interacts with its STRIPAK partner, Striatin 3 (Strn3), and both show overlapping functions in RGC survival. Furthermore, loss of Strip1 or Strn3 leads to activation of the proapoptotic marker, Jun, within RGCs, and Jun knockdown rescues RGC survival in strip1 mutants. In addition to its function in RGC maintenance, Strip1 is required for RGC dendritic patterning, which likely contributes to proper IPL formation. Taken together, we propose that a series of Strip1-mediated regulatory events coordinates inner retinal circuit formation by maintaining RGCs during development, which ensures proper positioning and neurite patterning of inner retinal neurons. The back of the eye is lined with an intricate tissue known as the retina, which consists of carefully stacked neurons connecting to each other in well-defined ‘synaptic’ layers. Near the surface, photoreceptors cells detect changes in light levels, before passing this information through the inner plexiform layer to retinal ganglion cells (or RGCs) below. These neurons will then relay the visual signals to the brain. Despite the importance of this inner retinal circuit, little is known about how it is created as an organism develops. As a response, Ahmed et al. sought to identify which genes are essential to establish the inner retinal circuit, and how their absence affects retinal structure. To do this, they introduced random errors in the genetic code of zebrafish and visualised the resulting retinal circuits in these fast-growing, translucent fish. Initial screening studies found fish with mutations in a gene encoding a protein called Strip1 had irregular layering of the inner retina. Further imaging experiments to pinpoint the individual neurons affected showed that in zebrafish without Strip1, RGCs died in the first few days of development. Consequently, other neurons moved into the RGC layer to replace the lost cells, leading to layering defects. Ahmed et al. concluded that Strip1 promotes RGC survival and thereby coordinates proper positioning of neurons in the inner retina. In summary, these findings help to understand how the inner retina is wired; they could also shed light on the way other layered structures are established in the nervous system. Moreover, this study paves the way for future research investigating Strip1 as a potential therapeutic target to slow down the death of RGCs in conditions such as glaucoma.
Collapse
Affiliation(s)
- Mai Ahmed
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University
| | - Yutaka Kojima
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University
| | - Ichiro Masai
- Developmental Neurobiology Unit, Okinawa Institute of Science and Technology Graduate University
| |
Collapse
|
10
|
Bharathan SP, Ferrario A, Stepanian K, Fernandez GE, Reid MW, Kim JS, Hutchens C, Harutyunyan N, Marks C, Thornton ME, Grubbs BH, Cobrinik D, Aparicio JG, Nagiel A. Characterization and staging of outer plexiform layer development in human retina and retinal organoids. Development 2021; 148:272710. [PMID: 34738615 DOI: 10.1242/dev.199551] [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: 07/07/2021] [Accepted: 10/26/2021] [Indexed: 11/20/2022]
Abstract
The development of the first synapse of the visual system between photoreceptors and bipolar cells in the outer plexiform layer (OPL) of the human retina is critical for visual processing but poorly understood. By studying the maturation state and spatial organization of photoreceptors, depolarizing bipolar cells, and horizontal cells in the human fetal retina, we establish a pseudo-temporal staging system for OPL development that we term OPL-Stages 0 to 4. This was validated through quantification of increasingly precise subcellular localization of Bassoon to the OPL with each stage (p<0.0001). By applying these OPL staging criteria to human retinal organoids (HROs) derived from human embryonic and induced pluripotent stem cells, we observed comparable maturation from OPL-Stage 0 at day 100 in culture up to OPL-Stage 3 by day 160. Quantification of presynaptic protein localization confirmed progression from OPL-Stage 0 to 3 (p<0.0001). Overall, this study defines stages of human OPL development through mid-gestation and establishes HROs as a model system that recapitulates key aspects of human photoreceptor-bipolar cell synaptogenesis in vitro.
Collapse
Affiliation(s)
- Sumitha Prameela Bharathan
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Angela Ferrario
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Kayla Stepanian
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - G Esteban Fernandez
- The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Mark W Reid
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Justin S Kim
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Chloe Hutchens
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Narine Harutyunyan
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Carolyn Marks
- Core Center of Excellence in Nano Imaging, University of Southern California, Los Angeles, CA, USA
| | - Matthew E Thornton
- Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Brendan H Grubbs
- Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - David Cobrinik
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.,Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jennifer G Aparicio
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Aaron Nagiel
- The Vision Center, Department of Surgery, Children's Hospital Los Angeles, Los Angeles, CA, USA.,The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, CA, USA.,Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
11
|
Riccitelli S, Di Paolo M, Ashley J, Bisti S, Di Marco S. The Timecourses of Functional, Morphological, and Molecular Changes Triggered by Light Exposure in Sprague-Dawley Rat Retinas. Cells 2021; 10:1561. [PMID: 34205615 PMCID: PMC8234029 DOI: 10.3390/cells10061561] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 06/01/2021] [Accepted: 06/16/2021] [Indexed: 01/11/2023] Open
Abstract
Retinal neurodegeneration can impair visual perception at different levels, involving not only photoreceptors, which are the most metabolically active cells, but also the inner retina. Compensatory mechanisms may hide the first signs of these impairments and reduce the likelihood of receiving timely treatments. Therefore, it is essential to characterize the early critical steps in the neurodegenerative progression to design adequate therapies. This paper describes and correlates early morphological and biochemical changes in the degenerating retina with in vivo functional analysis of retinal activity and investigates the progression of neurodegenerative stages for up to 7 months. For these purposes, Sprague-Dawley rats were exposed to 1000 lux light either for different durations (12 h to 24 h) and examined seven days afterward (7d) or for a fixed duration (24 h) and monitored at various time points following the exposure (up to 210d). Flash electroretinogram (fERG) recordings were correlated with morphological and histological analyses to evaluate outer and inner retinal disruptions, gliosis, trophic factor release, and microglial activation. Twelve hours or fifteen hours of exposure to constant light led to a severe retinal dysfunction with only minor morphological changes. Therefore, early pathological signs might be hidden by compensatory mechanisms that silence retinal dysfunction, accounting for the discrepancy between photoreceptor loss and retinal functional output. The long-term analysis showed a transient functional recovery, maximum at 45 days, despite a progressive loss of photoreceptors and coincident increases in glial fibrillary acidic protein (GFAP) and basic fibroblast growth factor-2 (bFGF-2) expression. Interestingly, the progression of the disease presented different patterns in the dorsal and ventral retina. The information acquired gives us the potential to develop a specific diagnostic tool to monitor the disease's progression and treatment efficacy.
Collapse
Affiliation(s)
- Serena Riccitelli
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (S.R.); (M.D.P.); (S.B.)
| | - Mattia Di Paolo
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (S.R.); (M.D.P.); (S.B.)
| | - James Ashley
- School of Biological Sciences, The University of Manchester, Manchester M13 9PL, UK;
| | - Silvia Bisti
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (S.R.); (M.D.P.); (S.B.)
- Istituto Nazionale di Biostrutture e Biosistemi (INBB), 00136 Roma, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Stefano Di Marco
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (S.R.); (M.D.P.); (S.B.)
- Istituto Nazionale di Biostrutture e Biosistemi (INBB), 00136 Roma, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
- IRCCS, Ospedale Policlinico San Martino, 16132 Genova, Italy
| |
Collapse
|
12
|
Tsukamoto Y, Iseki K, Omi N. Helical Fasciculation of Bipolar and Horizontal Cell Neurites for Wiring With Photoreceptors in Macaque and Mouse Retinas. Invest Ophthalmol Vis Sci 2021; 62:31. [PMID: 33507230 PMCID: PMC7846946 DOI: 10.1167/iovs.62.1.31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The three-dimensional configurations of rod and cone bipolar cell (BC) dendrites and horizontal cell (HC) processes outside rod and cone synaptic terminals have not been fully elucidated. We reveal how these neurites are mutually arranged to coordinate formation and maintenance of the postsynaptic complex of ribbon synapses in mouse and monkey retinas. Methods Serial section transmission electron microscopy was utilized to reconstruct BC and HC neurites in macaque monkey and mouse, including metabotropic glutamate receptor 6 (mGluR6)-knockout mice. Results Starting from sporadically distributed branching points, rod BC and HC neurites (B and H, respectively) took specific paths to rod spherules by gradually adjusting their mutual positions, which resulted in a closed alternating pattern of H‒B‒H‒B neurites at the rod spherule aperture. This order corresponded to the array of elements constituting the postsynaptic complex of ribbon synapses. We identified novel helical coils of HC processes surrounding the rod BC dendrite in both mouse and macaque retinas, and these structures occurred more frequently in mGluR6-knockout than wild-type mouse retinas. Horizontal cell processes also formed hook-like protrusions that encircled cone BC and HC neurites below the cone pedicles in the macaque retina. Conclusions Bipolar and horizontal cell neurites take specific paths to adjust their mutual positions at the rod spherule aperture. Some HC processes are helically coiled around rod BC dendrites or form hook-like protrusions around cone BC dendrites and HC processes. Loss of mGluR6 signaling may be one factor promoting unbalanced neurite growth and compensatory neurite coiling.
Collapse
Affiliation(s)
- Yoshihiko Tsukamoto
- Department of Biology, Hyogo College of Medicine, Mukogawa, Nishinomiya, Hyogo, Japan.,Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
| | - Kyoko Iseki
- Laboratory for Retinal Regeneration, RIKEN Center for Developmental Biology, Minatojima Minamimachi, Chuo-ku, Kobe, Hyogo, Japan
| | - Naoko Omi
- Studio EM-Retina, Satonaka, Nishinomiya, Hyogo, Japan
| |
Collapse
|
13
|
Ribeiro J, Procyk CA, West EL, O'Hara-Wright M, Martins MF, Khorasani MM, Hare A, Basche M, Fernando M, Goh D, Jumbo N, Rizzi M, Powell K, Tariq M, Michaelides M, Bainbridge JWB, Smith AJ, Pearson RA, Gonzalez-Cordero A, Ali RR. Restoration of visual function in advanced disease after transplantation of purified human pluripotent stem cell-derived cone photoreceptors. Cell Rep 2021; 35:109022. [PMID: 33882303 PMCID: PMC8065177 DOI: 10.1016/j.celrep.2021.109022] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 01/08/2021] [Accepted: 03/31/2021] [Indexed: 12/19/2022] Open
Abstract
Age-related macular degeneration and other macular diseases result in the loss of light-sensing cone photoreceptors, causing irreversible sight impairment. Photoreceptor replacement may restore vision by transplanting healthy cells, which must form new synaptic connections with the recipient retina. Despite recent advances, convincing evidence of functional connectivity arising from transplanted human cone photoreceptors in advanced retinal degeneration is lacking. Here, we show restoration of visual function after transplantation of purified human pluripotent stem cell-derived cones into a mouse model of advanced degeneration. Transplanted human cones elaborate nascent outer segments and make putative synapses with recipient murine bipolar cells (BCs), which themselves undergo significant remodeling. Electrophysiological and behavioral assessments demonstrate restoration of surprisingly complex light-evoked retinal ganglion cell responses and improved light-evoked behaviors in treated animals. Stringent controls exclude alternative explanations, including material transfer and neuroprotection. These data provide crucial validation for photoreceptor replacement therapy and for the potential to rescue cone-mediated vision.
Collapse
Affiliation(s)
- Joana Ribeiro
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Emma L West
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Monica F Martins
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Aura Hare
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Mark Basche
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Milan Fernando
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Debbie Goh
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Neeraj Jumbo
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Matteo Rizzi
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Kate Powell
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Menahil Tariq
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | | | - Alexander J Smith
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Rachael A Pearson
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | | | - Robin R Ali
- UCL Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK; Kellogg Eye Centre, University of Michigan, 1000 Wall St., Ann Arbor, MI 48105, USA.
| |
Collapse
|
14
|
Circuit Reorganization Shapes the Developing Human Foveal Midget Connectome toward Single-Cone Resolution. Neuron 2020; 108:905-918.e3. [PMID: 33027639 DOI: 10.1016/j.neuron.2020.09.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 08/11/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023]
Abstract
The human visual pathway is specialized for the perception of fine spatial detail. The neural circuitry that determines visual acuity begins in the retinal fovea, where the resolution afforded by a dense array of cone photoreceptors is preserved in the retinal output by a remarkable non-divergent circuit: cone → midget bipolar interneuron → midget ganglion cell (the "private line"). How the private line develops is unknown; it could involve early specification of extremely precise synaptic connections or, by contrast, emerge slowly in concordance with the gradual maturation of foveal architecture and visual sensitivity. To distinguish between these hypotheses, we reconstructed the midget circuitry in the fetal human fovea by serial electron microscopy. We discovered that the midget private line is sculpted by synaptic remodeling beginning early in fetal life, with midget bipolar cells contacting a single cone by mid-gestation and bipolar cell-ganglion cell connectivity undergoing a more protracted period of refinement.
Collapse
|
15
|
Xu B, Tang X, Jin M, Zhang H, Du L, Yu S, He J. Unifying developmental programs for embryonic and postembryonic neurogenesis in the zebrafish retina. Development 2020; 147:dev.185660. [PMID: 32467236 DOI: 10.1242/dev.185660] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 05/13/2020] [Indexed: 01/14/2023]
Abstract
The zebrafish retina grows for a lifetime. Whether embryonic and postembryonic retinogenesis conform to the same developmental program is an outstanding question that remains under debate. Using single-cell RNA sequencing of ∼20,000 cells of the developing zebrafish retina at four different stages, we identified seven distinct developmental states. Each state explicitly expresses a gene set. Disruption of individual state-specific marker genes results in various defects ranging from small eyes to the loss of distinct retinal cell types. Using a similar approach, we further characterized the developmental states of postembryonic retinal stem cells (RSCs) and their progeny in the ciliary marginal zone. Expression pattern analysis of state-specific marker genes showed that the developmental states of postembryonic RSCs largely recapitulated those of their embryonic counterparts, except for some differences in rod photoreceptor genesis. Thus, our findings reveal the unifying developmental program used by the embryonic and postembryonic retinogenesis in zebrafish.
Collapse
Affiliation(s)
- Baijie Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Xia Tang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China .,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Mengmeng Jin
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Hui Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Lei Du
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Shuguang Yu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100049, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| | - Jie He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China .,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai 201210, China
| |
Collapse
|
16
|
D'Orazi FD, Suzuki SC, Darling N, Wong RO, Yoshimatsu T. Conditional and biased regeneration of cone photoreceptor types in the zebrafish retina. J Comp Neurol 2020; 528:2816-2830. [PMID: 32342988 PMCID: PMC8496684 DOI: 10.1002/cne.24933] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 04/19/2020] [Accepted: 04/20/2020] [Indexed: 12/17/2022]
Abstract
A major challenge in regenerative medicine is replacing cells lost through injury or disease. While significant progress has been made, much remains unknown about the accuracy of native regenerative programs in cell replacement. Here, we capitalized on the regenerative capacity and stereotypic retinal organization of zebrafish to determine the specificity with which retinal Müller glial cells replace lost neuronal cell types. By utilizing a targeted genetic ablation technique, we restricted death to all or to distinct cone photoreceptor types (red, blue, or UV-sensitive cones), enabling us to compare the composition of cones that are regenerated. We found that Müller glia produce cones of all types upon nondiscriminate ablation of these photoreceptors, or upon selective ablation of red or UV cones. Pan-ablation of cones led to regeneration of the various cone types in relative abundances that resembled those of nonablated controls, that is, red > green > UV ~ blue cones. Moreover, selective loss of red or UV cones biased production toward the cone type that was ablated. In contrast, ablation of blue cones alone largely failed to induce cone production at all, although it did induce cell division in Müller glia. The failure to produce cones upon selective elimination of blue cones may be due to their low abundance compared to other cone types. Alternatively, it may be that blue cone death alone does not trigger a change in progenitor competency to support cone genesis. Our findings add to the growing notion that cell replacement during regeneration does not perfectly mimic programs of cell generation during development.
Collapse
Affiliation(s)
- Florence D D'Orazi
- Department Biological Structure, University of Washington, Seattle, Washington, USA.,Allen Institute for Brain Science, Seattle, Washington, USA
| | - Sachihiro C Suzuki
- Department Biological Structure, University of Washington, Seattle, Washington, USA.,Technology Licensing Section, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Nicole Darling
- Department Biological Structure, University of Washington, Seattle, Washington, USA.,Department of Biosciences, Durham University, Durham, UK
| | - Rachel O Wong
- Department Biological Structure, University of Washington, Seattle, Washington, USA
| | - Takeshi Yoshimatsu
- Department Biological Structure, University of Washington, Seattle, Washington, USA.,School of Life Sciences, University of Sussex, Brighton, UK
| |
Collapse
|
17
|
Furukawa T, Ueno A, Omori Y. Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells. Cell Mol Life Sci 2020; 77:1251-1266. [PMID: 31586239 PMCID: PMC11105113 DOI: 10.1007/s00018-019-03324-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/21/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022]
Abstract
In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.
Collapse
Affiliation(s)
- Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| |
Collapse
|
18
|
Appelbaum T, Santana E, Aguirre GD. Critical Decrease in the Level of Axon Guidance Receptor ROBO1 in Rod Synaptic Terminals Is Followed by Axon Retraction. Invest Ophthalmol Vis Sci 2020; 61:11. [PMID: 32176262 PMCID: PMC7405958 DOI: 10.1167/iovs.61.3.11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/14/2019] [Indexed: 12/24/2022] Open
Abstract
Purpose To define remodeling of photoreceptor synaptic terminals and second-order retinal neurons in canine X-linked progressive retinal atrophy 1 caused by a five-nucleotide deletion in the RPGR exon ORF15. Methods Retinas of normal and mutant dogs were used for gene expression, Western blot, and immunohistochemistry. Cell-specific markers were used to examine disease-dependent retinal remodeling. Results In mutant retinas, a number of rod axon terminals retract into the outer nuclear layer. This neuritic atrophy preceded significant loss of rods and was evident early in disease. Rod bipolar and horizontal cell processes were found to extend into the outer nuclear layer, where they seemed to form contacts with the spherules of rod photoreceptors. No ectopic rewiring was observed. Because cytoskeletal reorganization was previously shown to underlie photoreceptor axon retraction, we examined normal and mutant retinas for expression of axon guidance receptors ROBO1 and ROBO2, which are known to regulate actin cytoskeleton dynamics. We found that the overall expression of both ROBO1 and ROBO2 is retained at the same level in premature and fully developed normal retinas. However, analysis of predisease and early disease retinas identified markedly decreased levels of ROBO1 in rod spherules compared with controls. In contrast, no differences in ROBO1 signals were noted in cone pedicles in normal and mutant retinas, where ROBO1 levels remained similarly low. Conclusions Depletion of ROBO1 in rod synaptic terminals correlates with the remodeling of axonal and dendritic processes in the outer retina of dogs with X-linked progressive retinal atrophy 1 and may play a role in the retraction of rod axons.
Collapse
Affiliation(s)
- Tatyana Appelbaum
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Evelyn Santana
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Gustavo D. Aguirre
- Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| |
Collapse
|
19
|
Simmons AB, Camerino MJ, Clemons MR, Sukeena JM, Bloomsburg S, Borghuis BG, Fuerst PG. Increased density and age-related sharing of synapses at the cone to OFF bipolar cell synapse in the mouse retina. J Comp Neurol 2019; 528:1140-1156. [PMID: 31721194 DOI: 10.1002/cne.24810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/22/2019] [Accepted: 11/06/2019] [Indexed: 11/09/2022]
Abstract
Neural circuits in the adult nervous system are characterized by stable, cell type-specific patterns of synaptic connectivity. In many parts of the nervous system these patterns are established during development through initial over-innervation by multiple pre- or postsynaptic targets, followed by a process of refinement that takes place during development and is in many instances activity dependent. Here we report on an identified synapse in the mouse retina, the cone photoreceptor➔type 4 bipolar cell (BC4) synapse, and show that its development is distinctly different from the common motif of over-innervation followed by refinement. Indeed, the majority of cones are contacted by single BC4 throughout development, but are contacted by multiple BC4s through ongoing dendritic elaboration between 1 and 6 months of age-well into maturity. We demonstrate that cell density drives contact patterns downstream of single cones in Bax null mice and may serve to maintain constancy in both the dendritic and axonal projective field.
Collapse
Affiliation(s)
- Aaron B Simmons
- Department of Biological Sciences, University of Idaho, Moscow, Idaho
| | | | - Mellisa R Clemons
- Department of Biological Sciences, University of Idaho, Moscow, Idaho
| | - Joshua M Sukeena
- Department of Biological Sciences, University of Idaho, Moscow, Idaho
| | - Samuel Bloomsburg
- Department of Biological Sciences, University of Idaho, Moscow, Idaho
| | - Bart G Borghuis
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville
| | - Peter G Fuerst
- Department of Biological Sciences, University of Idaho, Moscow, Idaho.,WWAMI Medical Education Program, University of Washington School of Medicine, Moscow, Idaho
| |
Collapse
|
20
|
Activation of Rod Input in a Model of Retinal Degeneration Reverses Retinal Remodeling and Induces Formation of Functional Synapses and Recovery of Visual Signaling in the Adult Retina. J Neurosci 2019; 39:6798-6810. [PMID: 31285302 DOI: 10.1523/jneurosci.2902-18.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 05/28/2019] [Accepted: 06/18/2019] [Indexed: 12/31/2022] Open
Abstract
A major cause of human blindness is the death of rod photoreceptors. As rods degenerate, synaptic structures between rod and rod bipolar cells disappear and the rod bipolar cells extend their dendrites and occasionally make aberrant contacts. Such changes are broadly observed in blinding disorders caused by photoreceptor cell death and are thought to occur in response to deafferentation. How the remodeled retinal circuit affects visual processing following rod rescue is not known. To address this question, we generated male and female transgenic mice wherein a disrupted cGMP-gated channel (CNG) gene can be repaired at the endogenous locus and at different stages of degeneration by tamoxifen-inducible cre-mediated recombination. In normal rods, light-induced closure of CNG channels leads to hyperpolarization of the cell, reducing neurotransmitter release at the synapse. Similarly, rods lacking CNG channels exhibit a resting membrane potential that was ~10 mV hyperpolarized compared to WT rods, indicating diminished glutamate release. Retinas from these mice undergo stereotypic retinal remodeling as a consequence of rod malfunction and degeneration. Upon tamoxifen-induced expression of CNG channels, rods recovered their structure and exhibited normal light responses. Moreover, we show that the adult mouse retina displays a surprising degree of plasticity upon activation of rod input. Wayward bipolar cell dendrites establish contact with rods to support normal synaptic transmission, which is propagated to the retinal ganglion cells. These findings demonstrate remarkable plasticity extending beyond the developmental period and support efforts to repair or replace defective rods in patients blinded by rod degeneration.SIGNIFICANCE STATEMENT Current strategies for treatment of neurodegenerative disorders are focused on the repair of the primary affected cell type. However, the defective neurons function within a complex neural circuitry, which also becomes degraded during disease. It is not known whether rescued neurons and the remodeled circuit will establish communication to regain normal function. We show that the adult mammalian neural retina exhibits a surprising degree of plasticity following rescue of rod photoreceptors. The wayward dendrites of rod bipolar cells re-establish contact with rods to support normal synaptic transmission, which is propagated to the retinal ganglion cells. These findings support efforts to repair or replace defective rods in patients blinded by rod cell loss.
Collapse
|
21
|
Molecular and Cellular Mechanisms Underlying Somatostatin-Based Signaling in Two Model Neural Networks, the Retina and the Hippocampus. Int J Mol Sci 2019; 20:ijms20102506. [PMID: 31117258 PMCID: PMC6566141 DOI: 10.3390/ijms20102506] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/16/2019] [Accepted: 05/20/2019] [Indexed: 02/06/2023] Open
Abstract
Neural inhibition plays a key role in determining the specific computational tasks of different brain circuitries. This functional "braking" activity is provided by inhibitory interneurons that use different neurochemicals for signaling. One of these substances, somatostatin, is found in several neural networks, raising questions about the significance of its widespread occurrence and usage. Here, we address this issue by analyzing the somatostatinergic system in two regions of the central nervous system: the retina and the hippocampus. By comparing the available information on these structures, we identify common motifs in the action of somatostatin that may explain its involvement in such diverse circuitries. The emerging concept is that somatostatin-based signaling, through conserved molecular and cellular mechanisms, allows neural networks to operate correctly.
Collapse
|
22
|
He J, Zhao C, Dai J, Weng CH, Bian BSJ, Gong Y, Ge L, Fang Y, Liu H, Xu H, Yin ZQ. Microglia Mediate Synaptic Material Clearance at the Early Stage of Rats With Retinitis Pigmentosa. Front Immunol 2019; 10:912. [PMID: 31105708 PMCID: PMC6499027 DOI: 10.3389/fimmu.2019.00912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 04/09/2019] [Indexed: 12/11/2022] Open
Abstract
Resident microglia are the main immune cells in the retina and play a key role in the pathogenesis of retinitis pigmentosa (RP). Many previous studies on the roles of microglia mainly focused on the neurotoxicity or neuroprotection of photoreceptors, while their contributions to synaptic remodeling of neuronal circuits in the retina of early RP remained unclarified. In the present study, we used Royal College of Surgeons (RCS) rats, a classic RP model characterized by progressive microglia activation and synapse loss, to investigate the constitutive effects of microglia on the synaptic lesions and ectopic neuritogenesis. Rod degeneration resulted in synapse disruption and loss in the outer plexiform layer (OPL) at the early stage of RP. Coincidentally, the resident microglia in the OPL increased phagocytosis and mainly engaged in phagocytic engulfment of postsynaptic mGluR6 of rod bipolar cells (RBCs). Complement pathway might be involved in clearance of postsynaptic elements of RBCs by microglia. We pharmacologically deleted microglia using a CSF1 receptor (CSF1R) inhibitor to confirm this finding, and found that it caused the accumulation of postsynaptic mGluR6 levels and increased the number and length of ectopic dendrites in the RBCs. Interestingly, the numbers of presynaptic sites expressing CtBP2 and colocalized puncta in the OPL of RCS rats were not affected by microglia elimination. However, sustained microglial depletion led to progressive functional deterioration in the retinal responses to light in RCS rats. Based on our results, microglia mediated the remodeling of RBCs by phagocytosing postsynaptic materials and inhibiting ectopic neuritogenesis, contributing to delay the deterioration of vision at the early stage of RP.
Collapse
Affiliation(s)
- Juncai He
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Congjian Zhao
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Jiaman Dai
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Chuan Huang Weng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Bai Shi Jiao Bian
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yu Gong
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Lingling Ge
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Yajie Fang
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Hui Liu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Haiwei Xu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| | - Zheng Qin Yin
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University (Amy Medical University), Chongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of Chongqing, Chongqing, China
| |
Collapse
|
23
|
Yoong LF, Pai YJ, Moore AW. Stages and transitions in dendrite arbor differentiation. Neurosci Res 2019; 138:70-78. [DOI: 10.1016/j.neures.2018.09.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/10/2018] [Accepted: 08/14/2018] [Indexed: 12/26/2022]
|
24
|
Gambrill AC, Faulkner RL, McKeown CR, Cline HT. Enhanced visual experience rehabilitates the injured brain in Xenopus tadpoles in an NMDAR-dependent manner. J Neurophysiol 2018; 121:306-320. [PMID: 30517041 DOI: 10.1152/jn.00664.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Traumatic brain injuries introduce functional and structural circuit deficits that must be repaired for an organism to regain function. We developed an injury model in which Xenopus laevis tadpoles are given a penetrating stab wound that damages the optic tectal circuit and impairs visuomotor behavior. In tadpoles, as in other systems, injury induces neurogenesis. The newly generated neurons are thought to integrate into the existing circuit; however, whether they integrate via the same mechanisms that govern normal neuronal maturation during development is not understood. Development of the functional visuomotor circuit in Xenopus is driven by sensory activity. We hypothesized that enhanced visual experience would improve recovery from injury by facilitating integration of newly generated neurons into the tectal circuit. We labeled newly generated neurons in the injured tectum by green fluorescent protein expression and examined their circuit integration using electrophysiology and in vivo imaging. Providing animals with brief bouts of enhanced visual experience starting 24 h after injury increased synaptogenesis and circuit integration of new neurons and facilitated behavioral recovery. To investigate mechanisms of neuronal integration and behavioral recovery after injury, we interfered with N-methyl-d-aspartate (NMDA) receptor function. Ifenprodil, which blocks GluN2B-containing NMDA receptors, impaired dendritic arbor elaboration. GluN2B blockade inhibited functional integration of neurons generated in response to injury and prevented behavioral recovery. Furthermore, tectal GluN2B knockdown blocked the beneficial effects of enhanced visual experience on functional plasticity and behavioral recovery. We conclude that visual experience-mediated rehabilitation of the injured tectal circuit occurs by GluN2B-containing NMDA receptor-dependent integration of newly generated neurons. NEW & NOTEWORTHY Recovery from brain injury is difficult in most systems. The study of regenerative animal models that are capable of injury repair can provide insight into cellular and circuit mechanisms underlying repair. Using Xenopus tadpoles, we show enhanced sensory experience rehabilitates the injured visual circuit and that this experience-dependent recovery depends on N-methyl-d-aspartate receptor function. Understanding the mechanisms of rehabilitation in this system may facilitate recovery in brain regions and systems where repair is currently impossible.
Collapse
Affiliation(s)
- Abigail C Gambrill
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Regina L Faulkner
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Caroline R McKeown
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| | - Hollis T Cline
- Department of Neuroscience, the Dorris Neuroscience Center, The Scripps Research Institute , La Jolla, California
| |
Collapse
|
25
|
Hagiwara A, Kitahara Y, Grabner CP, Vogl C, Abe M, Kitta R, Ohta K, Nakamura K, Sakimura K, Moser T, Nishi A, Ohtsuka T. Cytomatrix proteins CAST and ELKS regulate retinal photoreceptor development and maintenance. J Cell Biol 2018; 217:3993-4006. [PMID: 30190286 PMCID: PMC6219712 DOI: 10.1083/jcb.201704076] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/18/2018] [Accepted: 08/03/2018] [Indexed: 01/06/2023] Open
Abstract
The retinal ribbon synapse is important for the processing of visual information. Hagiwara et al. show that the active zone proteins CAST and ELKS perform both redundant and unique functions in photoreceptors to promote the maturation, maintenance, and activity of ribbon synapses. At the presynaptic active zone (AZ), the related cytomatrix proteins CAST and ELKS organize the presynaptic release machinery. While CAST is known to regulate AZ size and neurotransmitter release, the role of ELKS and the integral system of CAST/ELKS together is poorly understood. Here, we show that CAST and ELKS have both redundant and unique roles in coordinating synaptic development, function, and maintenance of retinal photoreceptor ribbon synapses. A CAST/ELKS double knockout (dKO) mouse showed high levels of ectopic synapses and reduced responses to visual stimulation. Ectopic formation was not observed in ELKS conditional KO but progressively increased with age in CAST KO mice with higher rates in the dKO. Presynaptic calcium influx was strongly reduced in rod photoreceptors of CAST KO and dKO mice. Three-dimensional scanning EM reconstructions showed structural abnormalities in rod triads of CAST KO and dKO. Remarkably, AAV-mediated acute ELKS deletion after synapse maturation induced neurodegeneration and loss of ribbon synapses. These results suggest that CAST and ELKS work in concert to promote retinal synapse formation, transmission, and maintenance.
Collapse
Affiliation(s)
- Akari Hagiwara
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yosuke Kitahara
- Department of Pharmacology, Kurume University School of Medicine, Fukuoka, Japan
| | - Chad Paul Grabner
- Institute for Auditory Neuroscience and Inner Ear Lab, University Medical Center Göttingen, Göttingen, Germany.,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian Vogl
- Institute for Auditory Neuroscience and Inner Ear Lab, University Medical Center Göttingen, Göttingen, Germany
| | - Manabu Abe
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Ryo Kitta
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Keisuke Ohta
- Department of Anatomy, Kurume University School of Medicine, Fukuoka, Japan
| | - Keiichiro Nakamura
- Department of Anatomy, Kurume University School of Medicine, Fukuoka, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tobias Moser
- Institute for Auditory Neuroscience and Inner Ear Lab, University Medical Center Göttingen, Göttingen, Germany .,Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
| | - Akinori Nishi
- Department of Pharmacology, Kurume University School of Medicine, Fukuoka, Japan
| | - Toshihisa Ohtsuka
- Department of Biochemistry, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| |
Collapse
|
26
|
Beier C, Palanker D, Sher A. Stereotyped Synaptic Connectivity Is Restored during Circuit Repair in the Adult Mammalian Retina. Curr Biol 2018; 28:1818-1824.e2. [PMID: 29804805 DOI: 10.1016/j.cub.2018.04.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/14/2018] [Accepted: 04/18/2018] [Indexed: 01/03/2023]
Abstract
Proper function of the central nervous system (CNS) depends on the specificity of synaptic connections between cells of various types. Cellular and molecular mechanisms responsible for the establishment and refinement of these connections during development are the subject of an active area of research [1-6]. However, it is unknown if the adult mammalian CNS can form new type-selective synapses following neural injury or disease. Here, we assess whether selective synaptic connections can be reestablished after circuit disruption in the adult mammalian retina. The stereotyped circuitry at the first synapse in the retina, as well as the relatively short distances new neurites must travel compared to other areas of the CNS, make the retina well suited to probing for synaptic specificity during circuit reassembly. Selective connections between short-wavelength sensitive cone photoreceptors (S-cones) and S-cone bipolar cells provides the foundation of the primordial blue-yellow vision, common to all mammals [7-18]. We take advantage of the ground squirrel retina, which has a one-to-one S-cone-to-S-cone-bipolar-cell connection, to test if this connectivity can be reestablished following local photoreceptor loss [8, 19]. We find that after in vivo selective photoreceptor ablation, deafferented S-cone bipolar cells expand their dendritic trees. The new dendrites randomly explore the proper synaptic layer, bypass medium-wavelength sensitive cone photoreceptors (M-cones), and selectively synapse with S-cones. However, non-connected dendrites are not pruned back to resemble unperturbed S-cone bipolar cells. We show, for the first time, that circuit repair in the adult mammalian retina can recreate stereotypic selective wiring.
Collapse
Affiliation(s)
- Corinne Beier
- Department of Electrical Engineering, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Daniel Palanker
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA; Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
| | - Alexander Sher
- Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
| |
Collapse
|
27
|
Lrit1, a Retinal Transmembrane Protein, Regulates Selective Synapse Formation in Cone Photoreceptor Cells and Visual Acuity. Cell Rep 2018; 22:3548-3561. [DOI: 10.1016/j.celrep.2018.03.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 02/09/2018] [Accepted: 02/28/2018] [Indexed: 12/31/2022] Open
|
28
|
Vonhoff F, Keshishian H. Activity-Dependent Synaptic Refinement: New Insights from Drosophila. Front Syst Neurosci 2017; 11:23. [PMID: 28484377 PMCID: PMC5399093 DOI: 10.3389/fnsys.2017.00023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/03/2017] [Indexed: 01/26/2023] Open
Abstract
During development, neurons establish inappropriate connections as they seek out their synaptic partners, resulting in supernumerary synapses that must be pruned away. The removal of miswired synapses usually involves electrical activity, often through a Hebbian spike-timing mechanism. A novel form of activity-dependent refinement is used by Drosophila that may be non-Hebbian, and is critical for generating the precise connectivity observed in that system. In Drosophila, motoneurons use both glutamate and the biogenic amine octopamine for neurotransmission, and the muscle fibers receive multiple synaptic inputs. Motoneuron growth cones respond in a time-regulated fashion to multiple chemotropic signals arising from their postsynaptic partners. Central to this mechanism is a very low frequency (<0.03 Hz) oscillation of presynaptic cytoplasmic calcium, that regulates and coordinates the action of multiple downstream effectors involved in the withdrawal from off-target contacts. Low frequency calcium oscillations are widely observed in developing neural circuits in mammals, and have been shown to be critical for normal connectivity in a variety of neural systems. In Drosophila these mechanisms allow the growth cone to sample widely among possible synaptic partners, evaluate opponent chemotropic signals, and withdraw from off-target contacts. It is possible that the underlying molecular mechanisms are conserved widely among invertebrates and vertebrates.
Collapse
Affiliation(s)
- Fernando Vonhoff
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| | - Haig Keshishian
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| |
Collapse
|
29
|
Functional ectopic neuritogenesis by retinal rod bipolar cells is regulated by miR-125b-5p during retinal remodeling in RCS rats. Sci Rep 2017; 7:1011. [PMID: 28432360 PMCID: PMC5430652 DOI: 10.1038/s41598-017-01261-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 03/24/2017] [Indexed: 01/15/2023] Open
Abstract
Following retinal degeneration, retinal remodeling can cause neuronal microcircuits to undergo structural alterations, which particularly affect the dendrites of bipolar cells. However, the mechanisms and functional consequences of such changes remain unclear. Here, we used Royal College of Surgeon (RCS) rats as a model of retinal degeneration, to study structural changes in rod bipolar cells (RBCs) and the underlying mechanisms of these changes. We found that, with retinal degeneration, RBC dendrites extended into the outer nuclear layer (ONL) of the retina, and the ectopic dendrites formed synapses with the remaining photoreceptors. This ectopic neuritogenesis was associated with brain-derived neurotrophic factor (BDNF) - expression of which was negatively regulated by miR-125b-5p. Overexpression of miR-125b-5p in the retinae of RCS rats diminished RBC ectopic dendrites, and compromised the b-wave of the flash electroretinogram (ERG). In contrast, down-regulation of miR-125b-5p (or exogenous BDNF treatment) increased RBC ectopic dendrites, and improved b-wave. Furthermore, we showed that the regulation of ectopic neuritogenesis by BDNF occurred via the downstream modulation of the TrkB-CREB signaling pathway. Based on these findings, we conclude that ectopic dendrites are likely to be providing functional benefits and that, in RCS rats, miR-125b-5p regulates ectopic neuritogenesis by RBCs through modulation of the BDNF-TrkB-CREB pathway. This suggests that therapies that reduce miR-125b-5p expression could be beneficial in human retinal degenerative disease.
Collapse
|
30
|
Hou B, Fu Y, Weng C, Liu W, Zhao C, Yin ZQ. Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats. Front Cell Neurosci 2017; 11:98. [PMID: 28473754 PMCID: PMC5397418 DOI: 10.3389/fncel.2017.00098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/22/2017] [Indexed: 11/14/2022] Open
Abstract
Rod-cone gap junctions open at night to allow rod signals to pass to cones and activate the cone-bipolar pathway. This enhances the ability to detect large, dim objects at night. This electrical synaptic switch is governed by the circadian clock and represents a novel form of homeostatic plasticity that regulates retinal excitability according to network activity. We used tracer labeling and ERG recording in the retinae of control and retinal degenerative dystrophic RCS rats. We found that in the control animals, rod-cone gap junction coupling was regulated by the circadian clock via the modulation of the phosphorylation of the melatonin synthetic enzyme arylalkylamine N-acetyltransferase (AANAT). However, in dystrophic RCS rats, AANAT was constitutively phosphorylated, causing rod-cone gap junctions to remain open. A further b/a-wave ratio analysis revealed that dystrophic RCS rats had stronger synaptic strength between photoreceptors and bipolar cells, possibly because rod-cone gap junctions remained open. This was despite the fact that a decrease was observed in the amplitude of both a- and b-waves as a result of the progressive loss of rods during early degenerative stages. These results suggest that electric synaptic strength is increased during the day to allow cone signals to pass to the remaining rods and to be propagated to rod bipolar cells, thereby partially compensating for the weak visual input caused by the loss of rods.
Collapse
Affiliation(s)
- Baoke Hou
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Department of Ophthalmology, Chinese PLA General HospitalBeijing, China
| | - Yan Fu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Chuanhuang Weng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Weiping Liu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Congjian Zhao
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Zheng Qin Yin
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| |
Collapse
|
31
|
Deafferented Adult Rod Bipolar Cells Create New Synapses with Photoreceptors to Restore Vision. J Neurosci 2017; 37:4635-4644. [PMID: 28373392 DOI: 10.1523/jneurosci.2570-16.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 03/24/2017] [Accepted: 03/27/2017] [Indexed: 11/21/2022] Open
Abstract
Upon degeneration of photoreceptors in the adult retina, interneurons, including bipolar cells, exhibit a plastic response leading to their aberrant rewiring. Photoreceptor reintroduction has been suggested as a potential approach to sight restoration, but the ability of deafferented bipolar cells to establish functional synapses with photoreceptors is poorly understood. Here we use photocoagulation to selectively destroy photoreceptors in adult rabbits while preserving the inner retina. We find that rods and cones shift into the ablation zone over several weeks, reducing the blind spot at scotopic and photopic luminances. During recovery, rod and cone bipolar cells exhibit markedly different responses to deafferentation. Rod bipolar cells extend their dendrites to form new synapses with healthy photoreceptors outside the lesion, thereby restoring visual function in the deafferented retina. Secretagogin-positive cone bipolar cells did not exhibit such obvious dendritic restructuring. These findings are encouraging to the idea of photoreceptor reintroduction for vision restoration in patients blinded by retinal degeneration. At the same time, they draw attention to the postsynaptic side of photoreceptor reintroduction; various bipolar cell types, representing different visual pathways, vary in their response to the photoreceptor loss and in their consequent dendritic restructuring.SIGNIFICANCE STATEMENT Loss of photoreceptors during retinal degeneration results in permanent visual impairment. Strategies for vision restoration based on the reintroduction of photoreceptors inherently rely on the ability of the remaining retinal neurons to correctly synapse with new photoreceptors. We show that deafferented bipolar cells in the adult mammalian retina can reconnect to rods and cones and restore retinal sensitivity at scotopic and photopic luminances. Rod bipolar cells extend their dendrites to form new synapses with healthy rod photoreceptors. These findings support the idea that bipolar cells might be able to synapse with reintroduced photoreceptors, thereby restoring vision in patients blinded by retinal degeneration.
Collapse
|
32
|
DuVal MG, Allison WT. Impacts of the retinal environment and photoreceptor type on functional regeneration. Neural Regen Res 2017; 12:376-379. [PMID: 28469643 PMCID: PMC5399706 DOI: 10.4103/1673-5374.202930] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Retinal regeneration is a promising central nervous system (CNS) target amongst the various stem cell therapy pursuits, due to its accessibility for manipulation and its disposition towards longitudinal monitoring of treatment safety and efficacy. We offer our perspective on current hurdles towards functional regeneration of cone photoreceptors. Cones are key: For patients suffering vision loss, cone photoreceptors are a required cellular component to restoring daytime vision, colour vision, and high acuity vision. The challenges of regenerating cones contrast with logistic challenges of regenerating rod photoreceptors, which underlines the importance of evaluating context in degeneration and regeneration studies. Foundational research is required to delineate the factors required to generate a diversity of cones in the human macula, and to coax both remaining and newly regenerating cones to rewire towards restoring daytime colour vision. A complex interplay between cell-intrinsic factors and the retinal environment determine both the specification of cone fates and the synaptic plasticity enabling their functional integration. Recent revelations that cellular materials are transferred amongst photoreceptor progenitors further emphasize the critical role of neighbouring cells in directing stem cell fates. From our vantage point, translation of stem cell therapies to restore the cone-rich human macula must be borne upon foundational research in cone-rich retinas. Research frameworks centered on patient outcomes should prioritize animal models and functional outputs that enable and report functional restoration of cone-mediated vision.
Collapse
Affiliation(s)
- Michèle G DuVal
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - W Ted Allison
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.,Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
33
|
D'Orazi FD, Zhao XF, Wong RO, Yoshimatsu T. Mismatch of Synaptic Patterns between Neurons Produced in Regeneration and during Development of the Vertebrate Retina. Curr Biol 2016; 26:2268-79. [PMID: 27524481 DOI: 10.1016/j.cub.2016.06.063] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 06/25/2016] [Accepted: 06/28/2016] [Indexed: 01/09/2023]
Abstract
Stereotypic patterns of synaptic connections between neurons underlie the ability of the CNS to perform complex but circuit-specific information processing. Tremendous progress has been made toward advancing our understanding of how circuits are assembled during development, but whether the precision of this process can be recaptured after regeneration of neurons in the damaged CNS remains unclear. Here, we harnessed the endogenous regenerative capacity of the zebrafish retina to reconstruct the circuitry of neurons produced after damage. We tracked the input connectivity of identified bipolar cell (BC) types across stages of retinal development and after BC regeneration. We found that BCs of each type generate a unique and stereotypic wiring pattern with cone photoreceptors by gaining synapses with specific photoreceptor types over time. After selective ablation, the targeted BC types are rapidly reproduced and largely re-establish their characteristic morphological features. The regenerated population connects with appropriate photoreceptor types and establishes the original number of synaptic contacts. However, BC types that normally bias their connectivity in favor of red cones fail to precisely recapture this synaptic partner preference upon regeneration. Furthermore, regenerated BCs succeed in forming synaptic specializations at their axon terminals, but in excess of the usual number. Altogether, we find that regenerated BCs reinstate some, but not all, major features of their stereotypic wiring, suggesting that circuit patterns may be unable to regenerate with the same fidelity as in development.
Collapse
Affiliation(s)
- Florence D D'Orazi
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Box 357420, Seattle, WA 98195, USA
| | - Xiao-Feng Zhao
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Rachel O Wong
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Box 357420, Seattle, WA 98195, USA.
| | - Takeshi Yoshimatsu
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Box 357420, Seattle, WA 98195, USA.
| |
Collapse
|
34
|
Tu HY, Chiao CC. Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina. Dev Neurobiol 2016; 76:473-86. [PMID: 26084632 DOI: 10.1002/dneu.22320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/09/2015] [Accepted: 06/11/2015] [Indexed: 12/20/2022]
Abstract
Gap junctions are composed of connexin 36 (Cx36) and play a critical role in the rod photoreceptor signaling pathways of the vertebrate retina. Despite the fact that their connection and modulation in various rod pathways have been extensively studied in adult animals, little is known about the contribution and regulation of gap junctions to the development of the AII amacrine cell (AC)-mediated rod pathway. Using immunohistochemistry and microinjection, this study demonstrates a steady increase in relative Cx36 protein expression in both plexiform layers of the rabbit retina at around the time of eye opening. However, immediately after eye opening, most Cx36 immunoreactive AII ACs show no gap junction coupling pattern to neighboring cells and it is not until the third postnatal week that AII cells begin to exhibit an adult-like tracer-coupling pattern. Moreover, studies using dark-rearing and AMPA receptor blockade during postnatal development both revealed that relative levels of Cx36 immunoreactivity in AII ACs were increased when neural activity was inhibited. Our findings suggest that Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina.
Collapse
Affiliation(s)
- Hung-Ya Tu
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chuan-Chin Chiao
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Institute of Systems Neuroscience, National Tsing Hua University, Hsinchu, 30013, Taiwan
| |
Collapse
|
35
|
Abstract
UNLABELLED A hallmark of the nervous system is the presence of precise patterns of connections between different types of neurons. Many mechanisms can be used to establish specificity, including homophilic adhesion and synaptic refinement, but the range of strategies used across the nervous system remains unclear. To broaden the understanding of how neurons find their targets, we studied the developing murine cochlea, where two classes of spiral ganglion neurons (SGNs), type I and type II, navigate together to the sensory epithelium and then diverge to contact inner hair cells (IHCs) or outer hair cells (OHCs), respectively. Neurons with type I and type II morphologies are apparent before birth, suggesting that target selection might be accomplished by excluding type I processes from the OHC region. However, because type I processes appear to overshoot into type II territory postnatally, specificity may also depend on elimination of inappropriate synapses. To resolve these differences, we analyzed the morphology and dynamic behaviors of individual fibers and their branches as they interact with potential partners. We found that SGN processes continue to be segregated anatomically in the postnatal cochlea. Although type I-like fibers branched locally, few branches contacted OHCs, arguing against synaptic elimination. Instead, time-lapse imaging studies suggest a prominent role for retraction, first positioning processes to the appropriate region and then corralling branches during a subsequent period of exuberant growth and refinement. Thus, sequential stages of retraction can help to achieve target specificity, adding to the list of mechanisms available for sculpting neural circuits. SIGNIFICANCE STATEMENT During development, different types of neurons must form connections with specific synaptic targets, thereby creating the precise wiring diagram necessary for adult function. Although studies have revealed multiple mechanisms for target selection, we still know little about how different strategies are used to produce each circuit's unique pattern of connectivity. Here we combined neurite-tracing and time-lapse imaging to define the events that lead to the simple binary wiring specificity of the cochlea. A better understanding of how the cochlea is innervated will broaden our knowledge of target selection across the nervous system, offer new insights into the developmental origins of deafness, and guide efforts to restore connectivity in the damaged cochlea.
Collapse
|
36
|
Li S, Mitchell J, Briggs DJ, Young JK, Long SS, Fuerst PG. Morphological Diversity of the Rod Spherule: A Study of Serially Reconstructed Electron Micrographs. PLoS One 2016; 11:e0150024. [PMID: 26930660 PMCID: PMC4773090 DOI: 10.1371/journal.pone.0150024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/08/2016] [Indexed: 11/25/2022] Open
Abstract
Purpose Rod spherules are the site of the first synaptic contact in the retina’s rod pathway, linking rods to horizontal and bipolar cells. Rod spherules have been described and characterized through electron micrograph (EM) and other studies, but their morphological diversity related to retinal circuitry and their intracellular structures have not been quantified. Most rod spherules are connected to their soma by an axon, but spherules of rods on the surface of the Mus musculus outer plexiform layer often lack an axon and have a spherule structure that is morphologically distinct from rod spherules connected to their soma by an axon. Retraction of the rod axon and spherule is often observed in disease processes and aging, and the retracted rod spherule superficially resembles rod spherules lacking an axon. We hypothesized that retracted spherules take on an axonless spherule morphology, which may be easier to maintain in a diseased state. To test our hypothesis, we quantified the spatial organization and subcellular structures of rod spherules with and without axons. We then compared them to the retracted spherules in a disease model, mice that overexpress Dscam (Down syndrome cell adhesion molecule), to gain a better understanding of the rod synapse in health and disease. Methods We reconstructed serial EM images of wild type and DscamGoF (gain of function) rod spherules at a resolution of 7 nm in the X-Y axis and 60 nm in the Z axis. Rod spherules with and without axons, and retracted spherules in the DscamGoF retina, were reconstructed. The rod spherule intracellular organelles, the invaginating dendrites of rod bipolar cells and horizontal cell axon tips were also reconstructed for statistical analysis. Results Stereotypical rod (R1) spherules occupy the outer two-thirds of the outer plexiform layer (OPL), where they present as spherical terminals with large mitochondria. This spherule group is highly uniform and composed more than 90% of the rod spherule population. Rod spherules lacking an axon (R2) were also described and characterized. This rod spherule group consists of a specific spatial organization that is strictly located at the apical OPL-facing layer of the Outer Nuclear Layer (ONL). The R2 spherule displays a large bowl-shaped synaptic terminal that hugs the rod soma. Retracted spherules in the DscamGoF retina were also reconstructed to test if they are structurally similar to R2 spherules. The misplaced rod spherules in DscamGoF have a gross morphology that is similar to R2 spherules but have significant disruption in internal synapse organization. Conclusion We described a morphological diversity within Mus musculus rod spherules. This diversity is correlated with rod location in the ONL and contributes to the intracellular differences within spherules. Analysis of the DscamGoF retina indicated that their R2 spherules are not significantly different than wild type R2 spherules, but that their retracted rod spherules have abnormal synaptic organization.
Collapse
Affiliation(s)
- Shuai Li
- University of Idaho, Department of Biological Sciences, Moscow, Idaho, 83844, United States of America
| | - Joe Mitchell
- North Idaho College, Natural Sciences Division, Coeur d’Alene, Idaho, 83814, United States of America
| | - Deidrie J. Briggs
- University of Idaho, Department of Biological Sciences, Moscow, Idaho, 83844, United States of America
| | - Jaime K. Young
- University of Idaho, Department of Biological Sciences, Moscow, Idaho, 83844, United States of America
| | - Samuel S. Long
- Lewis-Clark State College, Department of Computer Sciences, Lewiston, Idaho, 83501, United States of America
| | - Peter G. Fuerst
- University of Idaho, Department of Biological Sciences, Moscow, Idaho, 83844, United States of America
- WWAMI Medical Education Program, Moscow, Idaho, 83844, United States of America
- * E-mail:
| |
Collapse
|
37
|
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.
Collapse
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
| | | |
Collapse
|
38
|
Presynaptic partner selection during retinal circuit reassembly varies with timing of neuronal regeneration in vivo. Nat Commun 2016; 7:10590. [PMID: 26838932 PMCID: PMC4742908 DOI: 10.1038/ncomms10590] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/04/2016] [Indexed: 12/13/2022] Open
Abstract
Whether neurons can restore their original connectivity patterns during circuit repair is unclear. Taking advantage of the regenerative capacity of zebrafish retina, we show here the remarkable specificity by which surviving neurons reassemble their connectivity upon regeneration of their major input. H3 horizontal cells (HCs) normally avoid red and green cones, and prefer ultraviolet over blue cones. Upon ablation of the major (ultraviolet) input, H3 HCs do not immediately increase connectivity with other cone types. Instead, H3 dendrites retract and re-extend to contact new ultraviolet cones. But, if regeneration is delayed or absent, blue-cone synaptogenesis increases and ectopic synapses are made with red and green cones. Thus, cues directing synapse specificity can be maintained following input loss, but only within a limited time period. Further, we postulate that signals from the major input that shape the H3 HC's wiring pattern during development persist to restrict miswiring after damage. Neurons in the zebrafish retina regenerate. Here, Yoshimatsu and colleagues show that retinal horizontal cells maintain their synaptic preferences for a limited period before circuit remodeling is triggered after photoreceptor loss.
Collapse
|
39
|
Retinal synaptic regeneration via microfluidic guiding channels. Sci Rep 2015; 5:13591. [PMID: 26314276 PMCID: PMC4551994 DOI: 10.1038/srep13591] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 07/31/2015] [Indexed: 11/08/2022] Open
Abstract
In vitro culture of dissociated retinal neurons is an important model for investigating retinal synaptic regeneration (RSR) and exploring potentials in artificial retina. Here, retinal precursor cells were cultured in a microfluidic chip with multiple arrays of microchannels in order to reconstruct the retinal neuronal synapse. The cultured retinal cells were physically connected through microchannels. Activation of electric signal transduction by the cells through the microchannels was demonstrated by administration of glycinergic factors. In addition, an image-based analytical method was used to quantify the synaptic connections and to assess the kinetics of synaptic regeneration. The rate of RSR decreased significantly below 100 μM of inhibitor glycine and then approached to a relatively constant level at higher concentrations. Furthermore, RSR was enhanced by chemical stimulation with potassium chloride. Collectively, the microfluidic synaptic regeneration chip provides a novel tool for high-throughput investigation of RSR at the cellular level and may be useful in quality control of retinal precursor cell transplantation.
Collapse
|
40
|
Schubert T, Wissinger B. Restoration of synaptic function in sight for degenerative retinal disease. J Clin Invest 2015; 125:2572-5. [PMID: 26098210 DOI: 10.1172/jci82577] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Synaptic disorganization is a prominent feature of many neurological diseases of the CNS, including Parkinson's disease, intellectual development disorders, and autism. Although synaptic plasticity is critical for learning and memory, it is unclear whether this innate property helps restore synaptic function in disease once the primary cause of disease is abrogated. An answer to this question may come from a recent investigation in X-linked retinoschisis, a currently untreatable retinopathy. In this issue of the JCI, Ou, Vijayasarathy, and colleagues showed progressive disorganization of key functional elements of the synapse between photoreceptors and ON-bipolar cells in a retinoschisin-deficient mouse model. Moreover, they demonstrated that adeno-associated virus-mediated (AAV-mediated) delivery of the retinoschisin gene restores structure and function to the photoreceptor to ON-bipolar cell synapse in mouse models, even in adults at advanced stages of the disease. The results of this study hold promise that AAV-based supplemental gene therapy will benefit patients with X-linked retinoschisis in a forthcoming clinical trial.
Collapse
|