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Moore NA, Morral N, Ciulla TA, Bracha P. Gene therapy for inherited retinal and optic nerve degenerations. Expert Opin Biol Ther 2017; 18:37-49. [DOI: 10.1080/14712598.2018.1389886] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Nicholas A. Moore
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Nuria Morral
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Thomas A. Ciulla
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Retina Service, Midwest Eye Institute, Indianapolis, IN, USA
| | - Peter Bracha
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
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52
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Martemyanov KA, Sampath AP. The Transduction Cascade in Retinal ON-Bipolar Cells: Signal Processing and Disease. Annu Rev Vis Sci 2017; 3:25-51. [PMID: 28715957 DOI: 10.1146/annurev-vision-102016-061338] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Our robust visual experience is based on the reliable transfer of information from our photoreceptor cells, the rods and cones, to higher brain centers. At the very first synapse of the visual system, information is split into two separate pathways, ON and OFF, which encode increments and decrements in light intensity, respectively. The importance of this segregation is borne out in the fact that receptive fields in higher visual centers maintain a separation between ON and OFF regions. In the past decade, the molecular mechanisms underlying the generation of ON signals have been identified, which are unique in their use of a G-protein signaling cascade. In this review, we consider advances in our understanding of G-protein signaling in ON-bipolar cell (BC) dendrites and how insights about signaling have emerged from visual deficits, mostly night blindness. Studies of G-protein signaling in ON-BCs reveal an intricate mechanism that permits the regulation of visual sensitivity over a wide dynamic range.
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Affiliation(s)
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, University of California, Los Angeles, California 90095;
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53
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Ramsay EP, Collins RF, Owens TW, Siebert CA, Jones RPO, Wang T, Roseman AM, Baldock C. Structural analysis of X-linked retinoschisis mutations reveals distinct classes which differentially effect retinoschisin function. Hum Mol Genet 2017; 25:5311-5320. [PMID: 27798099 PMCID: PMC5418834 DOI: 10.1093/hmg/ddw345] [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: 09/02/2016] [Accepted: 09/30/2016] [Indexed: 01/09/2023] Open
Abstract
Retinoschisin, an octameric retinal-specific protein, is essential for retinal architecture with mutations causing X-linked retinoschisis (XLRS), a monogenic form of macular degeneration. Most XLRS-associated mutations cause intracellular retention, however a subset are secreted as octamers and the cause of their pathology is ill-defined. Therefore, here we investigated the solution structure of the retinoschisin monomer and the impact of two XLRS-causing mutants using a combinatorial approach of biophysics and cryo-EM. The retinoschisin monomer has an elongated structure which persists in the octameric assembly. Retinoschisin forms a dimer of octamers with each octameric ring adopting a planar propeller structure. Comparison of the octamer with the hexadecamer structure indicated little conformational change in the retinoschisin octamer upon dimerization, suggesting that the octamer provides a stable interface for the construction of the hexadecamer. The H207Q XLRS-associated mutation was found in the interface between octamers and destabilized both monomeric and octameric retinoschisin. Octamer dimerization is consistent with the adhesive function of retinoschisin supporting interactions between retinal cell layers, so disassembly would prevent structural coupling between opposing membranes. In contrast, cryo-EM structural analysis of the R141H mutation at ∼4.2Å resolution was found to only cause a subtle conformational change in the propeller tips, potentially perturbing an interaction site. Together, these findings support distinct mechanisms of pathology for two classes of XLRS-associated mutations in the retinoschisin assembly.
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Affiliation(s)
- Ewan P Ramsay
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Richard F Collins
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Thomas W Owens
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - C Alistair Siebert
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Research Campus, UK
| | - Richard P O Jones
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Tao Wang
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Alan M Roseman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Clair Baldock
- Wellcome Trust Centre for Cell-Matrix Research, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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54
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Altschwager P, Ambrosio L, Swanson EA, Moskowitz A, Fulton AB. Juvenile Macular Degenerations. Semin Pediatr Neurol 2017; 24:104-109. [PMID: 28941524 PMCID: PMC5709045 DOI: 10.1016/j.spen.2017.05.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In this article, we review the following 3 common juvenile macular degenerations: Stargardt disease, X-linked retinoschisis, and Best vitelliform macular dystrophy. These are inherited disorders that typically present during childhood, when vision is still developing. They are sufficiently common that they should be included in the differential diagnosis of visual loss in pediatric patients. Diagnosis is secured by a combination of clinical findings, optical coherence tomography imaging, and genetic testing. Early diagnosis promotes optimal management. Although there is currently no definitive cure for these conditions, therapeutic modalities under investigation include pharmacologic treatment, gene therapy, and stem cell transplantation.
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Affiliation(s)
- Pablo Altschwager
- Departamento de Oftalmología, Escuela de Medicina, Pontificia, Universidad Católica de Chile, Santiago, Chile.
| | - Lucia Ambrosio
- Department of Ophthalmology, Children's Hospital, Boston, MA 02115 USA,Department of Ophthalmology, Harvard Medical School, Boston, MA 02115 USA
| | - Emily A. Swanson
- Department of Ophthalmology, Children's Hospital, Boston, MA 02115 USA
| | - Anne Moskowitz
- Department of Ophthalmology, Children's Hospital, Boston, MA 02115 USA,Department of Ophthalmology, Harvard Medical School, Boston, MA 02115 USA
| | - Anne B. Fulton
- Department of Ophthalmology, Children's Hospital, Boston, MA 02115 USA,Department of Ophthalmology, Harvard Medical School, Boston, MA 02115 USA
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55
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Yu WQ, Grzywacz NM, Lee EJ, Field GD. Cell type-specific changes in retinal ganglion cell function induced by rod death and cone reorganization in rats. J Neurophysiol 2017; 118:434-454. [PMID: 28424296 PMCID: PMC5506261 DOI: 10.1152/jn.00826.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 04/17/2017] [Accepted: 04/17/2017] [Indexed: 02/02/2023] Open
Abstract
We have determined the impact of rod death and cone reorganization on the spatiotemporal receptive fields (RFs) and spontaneous activity of distinct retinal ganglion cell (RGC) types. We compared RGC function between healthy and retinitis pigmentosa (RP) model rats (S334ter-3) at a time when nearly all rods were lost but cones remained. This allowed us to determine the impact of rod death on cone-mediated visual signaling, a relevant time point because the diagnosis of RP frequently occurs when patients are nightblind but daytime vision persists. Following rod death, functionally distinct RGC types persisted; this indicates that parallel processing of visual input remained largely intact. However, some properties of cone-mediated responses were altered ubiquitously across RGC types, such as prolonged temporal integration and reduced spatial RF area. Other properties changed in a cell type-specific manner, such as temporal RF shape (dynamics), spontaneous activity, and direction selectivity. These observations identify the extent of functional remodeling in the retina following rod death but before cone loss. They also indicate new potential challenges to restoring normal vision by replacing lost rod photoreceptors.NEW & NOTEWORTHY This study provides novel and therapeutically relevant insights to retinal function following rod death but before cone death. To determine changes in retinal output, we used a large-scale multielectrode array to simultaneously record from hundreds of retinal ganglion cells (RGCs). These recordings of large-scale neural activity revealed that following the death of all rods, functionally distinct RGCs remain. However, the receptive field properties and spontaneous activity of these RGCs are altered in a cell type-specific manner.
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Affiliation(s)
- Wan-Qing Yu
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California
| | - Norberto M Grzywacz
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California.,Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Department of Electrical Engineering, University of Southern California, Los Angeles, California.,Department of Neuroscience, Department of Physics, and Graduate School of Arts and Sciences, Georgetown University, Washington, District of Columbia
| | - Eun-Jin Lee
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California.,Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Greg D Field
- Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina
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Hu QR, Huang LZ, Chen XL, Xia HK, Li TQ, Li XX. Genetic analysis and clinical features of X-linked retinoschisis in Chinese patients. Sci Rep 2017; 7:44060. [PMID: 28272453 PMCID: PMC5341047 DOI: 10.1038/srep44060] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 02/03/2017] [Indexed: 11/10/2022] Open
Abstract
Many mutations in the retinoschisis (RS1) gene have been identified, but there are limited clinical data relating to the different genotypes. This study investigated the genotype, clinical phenotype and therapies for X-linked juvenile retinoschisis (XLRS) patients in China to evaluate the effects of gene mutations and therapies on the prognosis of the disease. Thirty patients were recruited in the study. Genetic examination identified 8 novel RS1 gene mutations. Twenty-four patients were identified as missense mutation, which was the most common gene mutation in XLRS patients. Amino acids 102 and 209 were the most common mutation areas, accounting for a total 35.7% of all patients. Mutations affecting amino acid 102 were associated with poor results on the flash electroretinogram (ERG). Sixteen patients had various complications. Anti-vascular endothelial growth factor (VEGF) drugs were given to four patients with hemorrhage or other complications, and serious adverse events did not occur. Our outcome demonstrates that missense mutation was the leading cause of XLRS and more than half of the patients with this missense had various complications. Anti-VEGF drugs may be an effective and safe way to prevent deterioration of XLRS with certain complications. There is wide genotypic and phenotypic variability in Chinese patients with XLRS.
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Affiliation(s)
- Qin-Rui Hu
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
| | - Lv-Zhen Huang
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
| | - Xiao-Li Chen
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
| | - Hui-Ka Xia
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
| | - Tian-Qi Li
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
| | - Xiao-Xin Li
- Department of Ophthalmology, Peking University People's Hospital, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Xizhimen South Street 11, Beijing, China
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Marangoni D, Yong Z, Kjellström S, Vijayasarathy C, A Sieving P, Bush RA. Rearing Light Intensity Affects Inner Retinal Pathology in a Mouse Model of X-Linked Retinoschisis but Does Not Alter Gene Therapy Outcome. Invest Ophthalmol Vis Sci 2017; 58:1656-1664. [PMID: 28297725 PMCID: PMC5361586 DOI: 10.1167/iovs.16-21016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Purpose To test the effects of rearing light intensity on retinal function and morphology in the retinoschisis knockout (Rs1-KO) mouse model of X-linked retinoschisis, and whether it affects functional outcome of RS1 gene replacement. Methods Seventy-six Rs1-KO mice were reared in either cyclic low light (LL, 20 lux) or moderate light (ML, 300 lux) and analyzed at 1 and 4 months. Retinal function was assessed by electroretinogram and cavity size by optical coherence tomography. Expression of inward-rectifier K+ channel (Kir4.1), water channel aquaporin-4 (AQP4), and glial fibrillary acidic protein (GFAP) were analyzed by Western blotting. In a separate study, Rs1-KO mice reared in LL (n = 29) or ML (n = 27) received a unilateral intravitreal injection of scAAV8-hRs-IRBP at 21 days, and functional outcome was evaluated at 4 months by electroretinogram. Results At 1 month, no functional or structural differences were found between LL- or ML-reared Rs1-KO mice. At 4 months, ML-reared Rs1-KO mice showed significant reduction of b-wave amplitude and b-/a-wave ratio with no changes in a-wave, and a significant increase in cavity size, compared to LL-reared animals. Moderate light rearing increased Kir4.1 expression in Rs1-KO mice by 4 months, but not AQP4 and GFAP levels. Administration of scAAV8-hRS1-IRBP to Rs1-KO mice showed similar improvement of inner retinal ERG function independent of LL or ML rearing. Conclusions Rearing light conditions affect the development of retinal cavities and post-photoreceptor function in Rs1-KO mice. However, the effect of rearing light intensity does not interact with the efficacy of RS1 gene replacement in Rs1-KO mice.
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Affiliation(s)
- Dario Marangoni
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Zeng Yong
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Sten Kjellström
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Camasamudram Vijayasarathy
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
| | - Paul A Sieving
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States 2National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Ronald A Bush
- Section on Translational Research for Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States
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58
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Bush RA, Zeng Y, Colosi P, Kjellstrom S, Hiriyanna S, Vijayasarathy C, Santos M, Li J, Wu Z, Sieving PA. Preclinical Dose-Escalation Study of Intravitreal AAV-RS1 Gene Therapy in a Mouse Model of X-linked Retinoschisis: Dose-Dependent Expression and Improved Retinal Structure and Function. Hum Gene Ther 2016; 27:376-89. [PMID: 27036983 DOI: 10.1089/hum.2015.142] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Gene therapy for inherited retinal diseases has been shown to ameliorate functional and structural defects in both animal models and in human clinical trials. X-linked retinoschisis (XLRS) is an early-age onset macular dystrophy resulting from loss of an extracellular matrix protein (RS1). In preparation for a human clinical gene therapy trial, we conducted a dose-range efficacy study of the clinical vector, a self-complementary AAV delivering a human retinoschisin (RS1) gene under control of the RS1 promoter and an interphotoreceptor binding protein enhancer (AAV8-scRS/IRBPhRS), in the retinoschisin knockout (Rs1-KO) mouse. The therapeutic vector at 1 × 10(6) to 2.5 × 10(9) (1E6-2.5E9) vector genomes (vg)/eye or vehicle was administered to one eye of 229 male Rs1-KO mice by intravitreal injection at 22 ± 3 days postnatal age (PN). Analysis of retinal function (dark-adapted electroretinogram, ERG), structure (cavities and outer nuclear layer thickness) by in vivo retinal imaging using optical coherence tomography, and retinal immunohistochemistry (IHC) for RS1 was done 3-4 months and/or 6-9 months postinjection (PI). RS1 IHC staining was dose dependent across doses ≥1E7 vg/eye, and the threshold for significant improvement in all measures of retinal structure and function was 1E8 vg/eye. Higher doses, however, did not produce additional improvement. At all doses showing efficacy, RS1 staining in Rs1-KO mouse was less than that in wild-type mice. Improvement in the ERG and RS1 staining was unchanged or greater at 6-9 months than at 3-4 months PI. This study demonstrates that vitreal administration of AAV8 scRS/IRBPhRS produces significant improvement in retinal structure and function in the mouse model of XLRS over a vector dose range that can be extended to a human trial. It indicates that a fully normal level of RS1 expression is not necessary for a therapeutic effect.
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Affiliation(s)
- Ronald A Bush
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland
| | - Yong Zeng
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland
| | - Peter Colosi
- 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland
| | - Sten Kjellstrom
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.,3 Department of Ophthalmology, Lund University , Lund, Sweden
| | - Suja Hiriyanna
- 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland
| | - Camasamudram Vijayasarathy
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland
| | - Maria Santos
- 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland
| | - Jinbo Li
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland
| | - Zhijian Wu
- 2 National Eye Institute, National Institutes of Health , Bethesda, Maryland
| | - Paul A Sieving
- 1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland.,2 National Eye Institute, National Institutes of Health , Bethesda, Maryland
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Plössl K, Weber BHF, Friedrich U. The X-linked juvenile retinoschisis protein retinoschisin is a novel regulator of mitogen-activated protein kinase signalling and apoptosis in the retina. J Cell Mol Med 2016; 21:768-780. [PMID: 27995734 PMCID: PMC5345684 DOI: 10.1111/jcmm.13019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 09/26/2016] [Indexed: 02/01/2023] Open
Abstract
X-linked juvenile retinoschisis (XLRS) is a hereditary retinal dystrophy in young males, caused by mutations in the RS1 gene. The function of the encoded protein, termed retinoschisin, and the molecular mechanisms underlying XLRS pathogenesis are still unresolved, although a direct interaction partner of the secreted retinoschisin, the retinal Na/K-ATPase, was recently identified. Earlier gene expression studies in retinoschisin-deficient (Rs1h-/Y ) mice provided a first indication of pathological up-regulation of mitogen-activated protein (MAP) kinase signalling in disease pathogenesis. To further investigate the role for retinoschisin in MAP kinase regulation, we exposed Y-79 cells and murine Rs1h-/Y retinae to recombinant retinoschisin and the XLRS-associated mutant RS1-C59S. Although normal retinoschisin stably bound to retinal cells, RS1-C59S exhibited a strongly reduced binding affinity. Simultaneously, exposure to normal retinoschisin significantly reduced phosphorylation of C-RAF and MAP kinases ERK1/2 in Y-79 cells and murine Rs1h-/Y retinae. Expression of MAP kinase target genes C-FOS and EGR1 was also down-regulated in both model systems. Finally, retinoschisin treatment decreased pro-apoptotic BAX-2 transcript levels in Y-79 cells and Rs1h-/Y retinae. Upon retinoschisin treatment, these cells showed increased resistance against apoptosis, reflected by decreased caspase-3 activity (in Y-79 cells) and increased photoreceptor survival (in Rs1h-/Y retinal explants). RS1-C59S did not influence C-RAF or ERK1/2 activation, C-FOS or EGR1 expression, or apoptosis. Our data imply that retinoschisin is a novel regulator of MAP kinase signalling and exerts an anti-apoptotic effect on retinal cells. We therefore discuss that disturbances of MAP kinase signalling by retinoschisin deficiency could be an initial step in XLRS pathogenesis.
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Affiliation(s)
- Karolina Plössl
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Bernhard H F Weber
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
| | - Ulrike Friedrich
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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STRUCTURAL AND FUNCTIONAL MONITORING OF EXTRAMACULAR CYSTOID SPACES IN A CASE OF X-LINKED RETINOSCHISIS TREATED WITH ACETAZOLAMIDE. Retin Cases Brief Rep 2016; 12:318-321. [PMID: 27984356 DOI: 10.1097/icb.0000000000000495] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Carbonic anhydrase inhibitors (CAIs) have been shown to have a beneficial effect on cystoid macular edema in X-linked retinoschisis (XLRS) and other inherited retinal conditions. The effect of CAIs outside the macula has been less well studied. METHODS Snellen visual acuity, spectral-domain optical coherence tomography (SD-OCT), kinetic visual field, and dark-adapted single-flash full-field electroretinogram (ERG) testing were all done at baseline and at least one follow-up visit. A 55-year-old male diagnosed with XLRS exhibited extensive macular and extramacular cystoid splitting in the right eye and was treated with oral extended-release acetazolamide 500 mg/day. RESULTS By 6 months of follow-up on acetazolamide treatment, SD-OCT demonstrated resolution of cystoid spaces both within the macula and out to the midperiphery. Visual acuity improved from 20/70 to 20/30. The full-field ERG was distinctly electronegative at both baseline and at a follow-up visit, with oscillatory potentials becoming more apparent at the follow-up visit. Peripheral visual field boundaries did not change significantly. CONCLUSION This report demonstrates structural resolution of cystoid spaces throughout much of the retina in a patient with XLRS, adding to a published case report in which we first noted that extramacular cystoid spaces observed in XLRS may respond to CAI treatment. To our knowledge, this is the first reported study of follow-up functional studies (ERG and perimetry) in a CAI treatment responder with XLRS.
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Abstract
BACKGROUND Gene therapy for inherited retinal diseases (IRDs) is currently being validated in several clinical trials and is becoming a promising therapeutic option for these previously incurable diseases. OBJECTIVES The aim of this review is to give an overview of the concept, the application and the challenges associated with gene therapy. In particular, the pertinence of gene therapy for IRDs will be highlighted along with ongoing clinical trials in the field. MATERIAL AND METHODS A systematic review of relevant entries on gene therapy and on gene therapy for IRDs, in particular in PubMed and ClinicalTrials.gov. RESULTS Gene therapy is emerging not only as a therapy for monogenetic retinal diseases but also for complex genetic diseases, such as neovascular age-related macular degeneration. The discovery of adeno-associated viral vectors (AAVs) has marked a great improvement for IRD gene therapy. All clinical studies since 2006 demonstrated the safety and initial efficacy; however, not all expectations based on very successful preclinical studies were met. CONCLUSION In future we can expect gene therapy to continue to become more clinically relevant. More than ever, it is now essential to generate precise characterizations of the natural disease progression of IRDs through observational or retrospective studies in order to guarantee a most effective study design.
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Affiliation(s)
- J-S Bellingrath
- Universitäts-Augenklinik, Department für Augenheilkunde, Universitätsklinikum Tübingen, Schleichstr. 12-16, 72076, Tübingen, Deutschland
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford, OX3 9DU,, England
| | - M D Fischer
- Universitäts-Augenklinik, Department für Augenheilkunde, Universitätsklinikum Tübingen, Schleichstr. 12-16, 72076, Tübingen, Deutschland.
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Headley Way, Oxford, OX3 9DU,, England.
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Sengillo JD, Justus S, Tsai YT, Cabral T, Tsang SH. Gene and cell-based therapies for inherited retinal disorders: An update. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2016; 172:349-366. [PMID: 27862925 DOI: 10.1002/ajmg.c.31534] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Retinal degenerations present a unique challenge as disease progression is irreversible and the retina has little regenerative potential. No current treatments for inherited retinal disease have the ability to reverse blindness, and current dietary supplement recommendations only delay disease progression with varied results. However, the retina is anatomically accessible and capable of being monitored at high resolution in vivo. This, in addition to the immune-privileged status of the eye, has put ocular disease at the forefront of advances in gene- and cell-based therapies. This review provides an update on gene therapies and randomized control trials for inherited retinal disease, including Leber congenital amaurosis, choroideremia, retinitis pigmentosa, Usher syndrome, X-linked retinoschisis, Leber hereditary optic neuropathy, and achromatopsia. New gene-modifying and cell-based strategies are also discussed. © 2016 Wiley Periodicals, Inc.
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Human neural progenitor cells decrease photoreceptor degeneration, normalize opsin distribution and support synapse structure in cultured porcine retina. Brain Res 2016; 1646:522-534. [PMID: 27369448 DOI: 10.1016/j.brainres.2016.06.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/27/2016] [Accepted: 06/27/2016] [Indexed: 11/24/2022]
Abstract
Retinal neurodegenerative disorders like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy and retinal detachment decrease retinal functionality leading to visual impairment. The pathological events are characterized by photoreceptor degeneration, synaptic disassembly, remodeling of postsynaptic neurons and activation of glial cells. Despite intense research, no effective treatment has been found for these disorders. The current study explores the potential of human neural progenitor cell (hNPC) derived factors to slow the degenerative processes in adult porcine retinal explants. Retinas were cultured for 3 days with or without hNPCs as a feeder layer and investigated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), immunohistochemical, western blot and quantitative real time-polymerase chain reaction (qRT-PCR) techniques. TUNEL showed that hNPCs had the capacity to limit photoreceptor cell death. Among cone photoreceptors, hNPC coculture resulted in better maintenance of cone outer segments and reduced opsin mislocalization. Additionally, maintained synaptic structural integrity and preservation of second order calbindin positive horizontal cells was also observed. However, Müller cell gliosis only seemed to be alleviated in terms of reduced Müller cell density. Our observations indicate that at 3 days of coculture, hNPC derived factors had the capacity to protect photoreceptors, maintain synaptic integrity and support horizontal cell survival. Human neural progenitor cell applied treatment modalities may be an effective strategy to help maintain retinal functionality in neurodegenerative pathologies. Whether hNPCs can independently hinder Müller cell gliosis by utilizing higher concentrations or by combination with other pharmacological agents still needs to be determined.
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Abstract
Over the last few years, huge progress has been made with regard to the understanding of molecular mechanisms underlying the pathogenesis of neurodegenerative diseases of the eye. Such knowledge has led to the development of gene therapy approaches to treat these devastating disorders. Challenges regarding the efficacy and efficiency of therapeutic gene delivery have driven the development of novel therapeutic approaches, which continue to evolve the field of ocular gene therapy. In this review article, we will discuss the evolution of preclinical and clinical strategies that have improved gene therapy in the eye, showing that treatment of vision loss has a bright future.
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Affiliation(s)
- Lolita Petit
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Hemant Khanna
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts.,2 Department of Neurobiology, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Claudio Punzo
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts.,2 Department of Neurobiology, University of Massachusetts Medical School , Worcester, Massachusetts
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Paired octamer rings of retinoschisin suggest a junctional model for cell-cell adhesion in the retina. Proc Natl Acad Sci U S A 2016; 113:5287-92. [PMID: 27114531 DOI: 10.1073/pnas.1519048113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Retinoschisin (RS1) is involved in cell-cell junctions in the retina, but is unique among known cell-adhesion proteins in that it is a soluble secreted protein. Loss-of-function mutations in RS1 lead to early vision impairment in young males, called X-linked retinoschisis. The disease is characterized by separation of inner retinal layers and disruption of synaptic signaling. Using cryo-electron microscopy, we report the structure at 4.1 Å, revealing double octamer rings not observed before. Each subunit is composed of a discoidin domain and a small N-terminal (RS1) domain. The RS1 domains occupy the centers of the rings, but are not required for ring formation and are less clearly defined, suggesting mobility. We determined the structure of the discoidin rings, consistent with known intramolecular and intermolecular disulfides. The interfaces internal to and between rings feature residues implicated in X-linked retinoschisis, indicating the importance of correct assembly. Based on this structure, we propose that RS1 couples neighboring membranes together through octamer-octamer contacts, perhaps modulated by interactions with other membrane components.
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Marangoni D, Bush RA, Zeng Y, Wei LL, Ziccardi L, Vijayasarathy C, Bartoe JT, Palyada K, Santos M, Hiriyanna S, Wu Z, Colosi P, Sieving PA. Ocular and systemic safety of a recombinant AAV8 vector for X-linked retinoschisis gene therapy: GLP studies in rabbits and Rs1-KO mice. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2016; 5:16011. [PMID: 27626041 PMCID: PMC5008245 DOI: 10.1038/mtm.2016.11] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 01/15/2016] [Accepted: 01/18/2016] [Indexed: 01/10/2023]
Abstract
X-linked retinoschisis (XLRS) is a retinal disease caused by mutations in the gene encoding the protein retinoschisin (RS1) and is one of the most common causes of macular degeneration in young men. Our therapeutic approach for XLRS is based on the administration of AAV8-scRS/IRBPhRS, an adeno-associated viral vector coding the human RS1 protein, via the intravitreal (IVT) route. Two Good Laboratory Practice studies, a 9-month study in New Zealand White rabbits (n = 124) injected with AAV8-scRS/IRBPhRS at doses of 2E9, 2E10, 2E11, and 1.5E12 vector genomes/eye (vg/eye), and a 6-month study in Rs1-KO mice (n = 162) dosed with 2E9 and 2E10 vg/eye of the same vector were conducted to assess ocular and systemic safety. A self-resolving, dose-dependent vitreal inflammation was the main ocular finding, and except for a single rabbit dosed with 1.5E12 vg/eye, which showed a retinal detachment, no other ocular adverse event was reported. Systemic toxicity was not identified in either species. Biodistribution analysis in Rs1-KO mice detected spread of vector genome in extraocular tissues, but no evidence of organ or tissues damage was found. These studies indicate that IVT administration of AAV8-scRS/IRBPhRS is safe and well tolerated and support its advancement into a phase 1/2a clinical trial for XLRS.
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Affiliation(s)
- Dario Marangoni
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA; Department of Biotechnology and Applied Clinical Science, University of L'Aquila, L'Aquila, Italy
| | - Ronald A Bush
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland, USA
| | - Yong Zeng
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland, USA
| | - Lisa L Wei
- National Eye Institute, National Institutes of Health , Bethesda, Maryland, USA
| | - Lucia Ziccardi
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland, USA
| | - Camasamudram Vijayasarathy
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland, USA
| | | | | | - Maria Santos
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health , Bethesda, Maryland, USA
| | - Suja Hiriyanna
- National Eye Institute, National Institutes of Health , Bethesda, Maryland, USA
| | - Zhijian Wu
- National Eye Institute, National Institutes of Health , Bethesda, Maryland, USA
| | - Peter Colosi
- National Eye Institute, National Institutes of Health , Bethesda, Maryland, USA
| | - Paul A Sieving
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA; National Eye Institute, National Institutes of Health, Bethesda, Maryland, USA
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Apaolaza PS, Del Pozo-Rodríguez A, Solinís MA, Rodríguez JM, Friedrich U, Torrecilla J, Weber BHF, Rodríguez-Gascón A. Structural recovery of the retina in a retinoschisin-deficient mouse after gene replacement therapy by solid lipid nanoparticles. Biomaterials 2016; 90:40-9. [PMID: 26986855 DOI: 10.1016/j.biomaterials.2016.03.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/29/2016] [Accepted: 03/02/2016] [Indexed: 11/26/2022]
Abstract
X-linked juvenile retinoschisis (XLRS) is a retinal degenerative disorder caused by mutations in the RS1 gene encoding a protein termed retinoschisin. The disease is an excellent candidate for gene replacement therapy as the majority of mutations have been shown to lead to a complete deficiency of the secreted protein in the retinal structures. In this work, we have studied the ability of non-viral vectors based on solid lipid nanoparticles (SLN) to induce the expression of retinoschisin in photoreceptors (PR) after intravitreal administration to Rs1h-deficient mice. We designed two vectors prepared with SLN, protamine, and dextran (DX) or hyaluronic acid (HA), bearing a plasmid containing the human RS1 gene under the control of the murin opsin promoter (mOPS). In vitro, the nanocarriers were able to induce the expression of retinoschisin in a PR cell line. After injection into the murine vitreous, the formulation prepared with HA induced a higher transfection level in PR than the formulation prepared with DX. Moreover, the level of retinoschisin in the inner nuclear layer (INL), where bipolar cells are located, was also higher. Two weeks after vitreal administration into Rs1h-deficient mice, both formulations showed significant improvement of the retinal structure by inducing a decrease of cavities and PR loss, and an increase of retinal and outer nuclear layer (ONL) thickness. HA-SLN resulted in a significant higher increase in the thickness of both retina and ONL, which can be explained by the higher transfection level of PR. In conclusion, we have shown the structural improvement of the retina of Rs1h-deficient mice with PR specific expression of the RS1 gene driven by the specific promoter mOPS, after successful delivery via SLN-based non-viral vectors.
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Affiliation(s)
- P S Apaolaza
- Pharmacokinetic, Nanotechnology and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, Centro de investigación Lascaray ikergunea, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain
| | - A Del Pozo-Rodríguez
- Pharmacokinetic, Nanotechnology and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, Centro de investigación Lascaray ikergunea, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain
| | - M A Solinís
- Pharmacokinetic, Nanotechnology and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, Centro de investigación Lascaray ikergunea, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain
| | - J M Rodríguez
- Physiology Laboratory, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain
| | - U Friedrich
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauß-Allee 11, D-93053 Regensburg, Germany
| | - J Torrecilla
- Pharmacokinetic, Nanotechnology and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, Centro de investigación Lascaray ikergunea, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain
| | - B H F Weber
- Institute of Human Genetics, University of Regensburg, Franz-Josef-Strauß-Allee 11, D-93053 Regensburg, Germany
| | - A Rodríguez-Gascón
- Pharmacokinetic, Nanotechnology and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, Centro de investigación Lascaray ikergunea, University of the Basque Country UPV/EHU, Paseo de la Universidad, 7, 01006 Vitoria-Gasteiz, Spain.
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Dalkara D, Goureau O, Marazova K, Sahel JA. Let There Be Light: Gene and Cell Therapy for Blindness. Hum Gene Ther 2016; 27:134-47. [PMID: 26751519 PMCID: PMC4779297 DOI: 10.1089/hum.2015.147] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 01/06/2016] [Indexed: 12/14/2022] Open
Abstract
Retinal degenerative diseases are a leading cause of irreversible blindness. Retinal cell death is the main cause of vision loss in genetic disorders such as retinitis pigmentosa, Stargardt disease, and Leber congenital amaurosis, as well as in complex age-related diseases such as age-related macular degeneration. For these blinding conditions, gene and cell therapy approaches offer therapeutic intervention at various disease stages. The present review outlines advances in therapies for retinal degenerative disease, focusing on the progress and challenges in the development and clinical translation of gene and cell therapies. A significant body of preclinical evidence and initial clinical results pave the way for further development of these cutting edge treatments for patients with retinal degenerative disorders.
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Affiliation(s)
- Deniz Dalkara
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, France
| | - Olivier Goureau
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, France
| | - Katia Marazova
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, France
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de la Vision, France
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, France
- Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
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69
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Bush M, Setiaputra D, Yip CK, Molday RS. Cog-Wheel Octameric Structure of RS1, the Discoidin Domain Containing Retinal Protein Associated with X-Linked Retinoschisis. PLoS One 2016; 11:e0147653. [PMID: 26812435 PMCID: PMC4728063 DOI: 10.1371/journal.pone.0147653] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/06/2016] [Indexed: 11/19/2022] Open
Abstract
RS1, also known as retinoschisin, is a disulphide-linked, discoidin domain containing homo-oligomeric protein that plays a crucial role in maintaining the cellular and synaptic organization of the retina. This is highlighted by the finding that over 130 mutations in RS1 cause X-linked retinoschisis, a retinal degenerative disease characterized by the splitting of the retinal cell layers, disruption of the photoreceptor-bipolar synapses, degeneration of photoreceptors, and severe loss in central vision. In this study, we investigated the arrangement of the RS1 subunits within the oligomer complex using single particle electron microscopy. RS1 was seen as two stacked rings with each ring displaying a symmetrical cog wheel-like structure with eight teeth or projections corresponding to the RS1 subunits. Three dimensional reconstruction and molecular modelling indicated that the discoidin domain, the principal functional unit of RS1, projects outward, and the Rs1 domain and C-terminal segment containing intermolecular disulphide bonds are present in the inner ring to form the core octameric structure. These studies provide a basis for further understanding the role of the novel core RS1 octameric complex in retinal cell biology and X-linked retinoschisis.
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Affiliation(s)
- Martin Bush
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dheva Setiaputra
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Calvin K. Yip
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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70
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Gayet-Primo J, Puthussery T. Alterations in Kainate Receptor and TRPM1 Localization in Bipolar Cells after Retinal Photoreceptor Degeneration. Front Cell Neurosci 2015; 9:486. [PMID: 26733812 PMCID: PMC4686838 DOI: 10.3389/fncel.2015.00486] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2015] [Accepted: 11/30/2015] [Indexed: 11/21/2022] Open
Abstract
Photoreceptor degeneration differentially impacts glutamatergic signaling in downstream On and Off bipolar cells. In rodent models, photoreceptor degeneration leads to loss of glutamatergic signaling in On bipolar cells, whereas Off bipolar cells appear to retain glutamate sensitivity, even after extensive photoreceptor loss. The localization and identity of the receptors that mediate these residual glutamate responses in Off bipolar cells have not been determined. Recent studies show that macaque and mouse Off bipolar cells receive glutamatergic input primarily through kainate-type glutamate receptors. Here, we studied the impact of photoreceptor degeneration on glutamate receptor and their associated proteins in Off and On bipolar cells. We show that the kainate receptor subunit, GluK1, persists in remodeled Off bipolar cell dendrites of the rd10 mouse retina. However, the pattern of expression is altered and the intensity of staining is reduced compared to wild-type retina. The kainate receptor auxiliary subunit, Neto1, also remains in Off bipolar cell dendrites after extensive photoreceptor degeneration. Similar preservation of kainate receptor subunits was evident in human retina in which photoreceptors had degenerated due to serous retinal detachment. In contrast, photoreceptor degeneration leads to loss of synaptic expression of TRPM1 in mouse and human On bipolar cells, but strong somatic expression remains. These findings demonstrate that Off bipolar cells retain dendritic glutamate receptors during retinal degeneration and could thus serve as a conduit for signal transmission from transplanted or optogenetically restored photoreceptors.
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Affiliation(s)
- Jacqueline Gayet-Primo
- Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, Portland OR, USA
| | - Theresa Puthussery
- Casey Eye Institute, Department of Ophthalmology, Oregon Health and Science University, Portland OR, USA
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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.
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