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Miller ML, Pindwarawala M, Agosto MA. Complex N-glycosylation of mGluR6 is required for trans-synaptic interaction with ELFN adhesion proteins. J Biol Chem 2024; 300:107119. [PMID: 38428819 PMCID: PMC10973816 DOI: 10.1016/j.jbc.2024.107119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/30/2024] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
Synaptic transmission from retinal photoreceptors to downstream ON-type bipolar cells (BCs) depends on the postsynaptic metabotropic glutamate receptor mGluR6, located at the BC dendritic tips. Glutamate binding to mGluR6 initiates G-protein signaling that ultimately leads to BC depolarization in response to light. The mGluR6 receptor also engages in trans-synaptic interactions with presynaptic ELFN adhesion proteins. The roles of post-translational modifications in mGluR6 trafficking and function are unknown. Treatment with glycosidase enzymes PNGase F and Endo H demonstrated that both endogenous and heterologously expressed mGluR6 contain complex N-glycosylation acquired in the Golgi. Pull-down experiments with ELFN1 and ELFN2 extracellular domains revealed that these proteins interact exclusively with the complex glycosylated form of mGluR6. Mutation of the four predicted N-glycosylation sites, either singly or in combination, revealed that all four sites are glycosylated. Single mutations partially reduced, but did not abolish, surface expression in heterologous cells, while triple mutants had little or no surface expression, indicating that no single glycosylation site is necessary or sufficient for plasma membrane trafficking. Mutation at N445 severely impaired both ELFN1 and ELFN2 binding. All single mutants exhibited dendritic tip enrichment in rod BCs, as did the triple mutant with N445 as the sole N-glycosylation site, demonstrating that glycosylation at N445 is sufficient but not necessary for dendritic tip localization. The quadruple mutant was completely mislocalized. These results reveal a key role for complex N-glycosylation in regulating mGluR6 trafficking and ELFN binding, and by extension, function of the photoreceptor synapses.
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Affiliation(s)
- Michael L Miller
- Faculty of Science, Medical Sciences Program, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Mustansir Pindwarawala
- Faculty of Science, Medical Sciences Program, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Melina A Agosto
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada.
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2
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Bai D, Guo R, Huang D, Ji J, Liu W. Compound heterozygous mutations in GRM6 causing complete Schubert-Bornschein type congenital stationary night blindness. Heliyon 2024; 10:e27039. [PMID: 38434377 PMCID: PMC10907788 DOI: 10.1016/j.heliyon.2024.e27039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/26/2023] [Accepted: 02/22/2024] [Indexed: 03/05/2024] Open
Abstract
Background To explore the genetic defects of a Chinese family with complete Schubert-Bornschein type congenital stationary night blindness (CSNB). Methods A Chinese family with complete Schubert-Bornschein type CSNB was enrolled in this study. The detailed ocular presentations of the patient were recorded. Targeted gene sequencing including 156 genes related to retinal diseases was used to detect the gene mutation. Sanger sequencing was performed to validate the potential pathogenic variants, and segregation analysis was performed on all available family members. Bioinformatics analysis was performed to predict the impact of the mutations. Results By targeted gene sequencing and Sanger sequencing, we identified compound heterozygous mutations in GRM6: c.152G>T (p.Gly51Val) and c.727delG (p.Val243SerfsX21). Segregation analysis demonstrated that the mother of the proband carried the missense mutation (c.152G>T) while her father carried the frameshift mutation (c.727delG), indicating CSNB was autosomal recessively inherited in this family. Several bioinformatics prediction programs revealed the mutations were "Damaging" or "Disease Causing" and conservation analysis showed both the codons Gly51 and Val243 were highly conserved among species, suggesting the changes were pathogenic. Conclusion By targeted gene sequencing and Sanger sequencing, we detected compound heterozygous mutations (c.152G>T, p.Gly51Val and c.727delG, p.Val243SerfsX21) in GRM6. The mutations co-segregated with the phenotype of the family members and are considered to be responsible for complete Schubert-Bornschein type CSNB. However, functional experiments in the future are needed to confirm the pathogenicity of the variants and to elucidate their exact molecular mechanisms causing CSNB.
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Affiliation(s)
- Dong'e Bai
- Department of Ophthalmology, Characteristic Medical Center of Chinese People's Armed Police Force, Tianjin, China
| | - Ruru Guo
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, 300384, China
| | - Dandan Huang
- Department of Ophthalmology, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Jian Ji
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, 300384, China
| | - Wei Liu
- Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, 300384, China
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3
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Chen W, Zhong W, Yu L, Lin X, Xie J, Liu Z. A Drosophila Model Reveals the Potential Role for mtt in Retinal Disease. Int J Mol Sci 2024; 25:899. [PMID: 38255972 PMCID: PMC10815649 DOI: 10.3390/ijms25020899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/03/2024] [Accepted: 01/06/2024] [Indexed: 01/24/2024] Open
Abstract
Congenital stationary night blindness (CSNB) is a genetically heterogeneous inherited retinal disorder, caused by over 300 mutations in 17 different genes. While there are numerous fly models available for simulating ocular diseases, most are focused on mimicking retinitis pigmentosa (RP), with animal models specifically addressing CSNB limited to mammals. Here, we present a CSNB fly model associated with the mtt gene, utilizing RNA interference (RNAi) to silence the mtt gene in fly eyes (homologous to the mammalian GRM6 gene) and construct a CSNB model. Through this approach, we observed significant defects in the eye structure and function upon reducing mtt expression in fly eyes. This manifested as disruptions in the compound eye lens structure and reduced sensitivity to light responses. These results suggest a critical role for mtt in the function of fly adult eyes. Interestingly, we found that the mtt gene is not expressed in the photoreceptor neurons of adult flies but is localized to the inner lamina neurons. In summary, these results underscore the crucial involvement of mtt in fly retinal function, providing a framework for understanding the pathogenic mechanisms of CSNB and facilitating research into potential therapeutic interventions.
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Affiliation(s)
- Wenfeng Chen
- Institute of Life Sciences, College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Wenmiao Zhong
- Institute of Life Sciences, College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Lingqi Yu
- Institute of Life Sciences, College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Xiang Lin
- Institute of Life Sciences, College of Biological Science and Engineering, Fuzhou University, Fuzhou 350108, China
| | - Jiayu Xie
- School of Medicine, Chongqing University, Chongqing 400044, China;
- State Key Laboratory of Resource Insects, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China
| | - Zhenxing Liu
- State Key Laboratory of Resource Insects, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China
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4
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Hölzel MB, Kamermans W, Winkelman BHJ, Howlett MHC, De Zeeuw CI, Kamermans M. A common cause for nystagmus in different congenital stationary night blindness mouse models. J Physiol 2023; 601:5317-5340. [PMID: 37864560 DOI: 10.1113/jp284965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 09/22/2023] [Indexed: 10/23/2023] Open
Abstract
In Nyxnob mice, a model for congenital nystagmus associated with congenital stationary night blindness (CSNB), synchronous oscillating retinal ganglion cells (RGCs) lead to oscillatory eye movements, i.e. nystagmus. Given the specific expression of mGluR6 and Cav 1.4 in the photoreceptor to bipolar cell synapses, as well as their clinical association with CSNB, we hypothesize that Grm6nob3 and Cav 1.4-KO mutants show, like the Nyxnob mouse, oscillations in both their RGC activity and eye movements. Using multi-electrode array recordings of RGCs and measurements of the eye movements, we demonstrate that Grm6nob3 and Cav 1.4-KO mice also show oscillations of their RGCs as well as a nystagmus. Interestingly, the preferred frequencies of RGC activity as well as the eye movement oscillations of the Grm6nob3 , Cav 1.4-KO and Nyxnob mice differ among mutants, but the neuronal activity and eye movement behaviour within a strain remain aligned in the same frequency domain. Model simulations indicate that mutations affecting the photoreceptor-bipolar cell synapse can form a common cause of the nystagmus of CSNB by driving oscillations in RGCs via AII amacrine cells. KEY POINTS: In Nyxnob mice, a model for congenital nystagmus associated with congenital stationary night blindness (CSNB), their oscillatory eye movements (i.e. nystagmus) are caused by synchronous oscillating retinal ganglion cells. Here we show that the same mechanism applies for two other CSNB mouse models - Grm6nob3 and Cav 1.4-KO mice. We propose that the retinal ganglion cell oscillations originate in the AII amacrine cells. Model simulations show that by only changing the input to ON-bipolar cells, all phenotypical differences between the various genetic mouse models can be reproduced.
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Affiliation(s)
- Maj-Britt Hölzel
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
| | - Wouter Kamermans
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
| | - Beerend H J Winkelman
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Marcus H C Howlett
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
| | - Chris I De Zeeuw
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience Amsterdam, Amsterdam, the Netherlands
- Department of Biomedical Physics, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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5
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Avilés EC, Wang SK, Patel S, Shi S, Lin L, Kefalov VJ, Goodrich LV, Cepko CL, Xue Y. High temporal frequency light response in mouse retina is mediated by ON and OFF bipolar cells and requires FAT3 signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.02.565326. [PMID: 37961274 PMCID: PMC10635074 DOI: 10.1101/2023.11.02.565326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Vision is initiated by the reception of light by photoreceptors and subsequent processing via parallel retinal circuits. Proper circuit organization depends on the multi-functional tissue polarity protein FAT3, which is required for amacrine cell connectivity and retinal lamination. Here we investigated the retinal function of Fat3 mutant mice and found decreases in physiological and perceptual responses to high frequency flashes. These defects did not correlate with abnormal amacrine cell wiring, pointing instead to a role in bipolar cell subtypes that also express FAT3. Indeed, similar deficits were observed in mice lacking the bipolar cell glutamate receptors GRIK1 (OFF-bipolar cells) and GRM6 (ON-bipolar cells). Mechanistically, FAT3 binds to the synaptic protein PTPσ and is required to localize GRIK1 to OFF-cone bipolar cell synapses with cone photoreceptors. How FAT3 impacts ON-cone bipolar cell function at high temporal frequency remains to be uncovered. These findings expand the repertoire of FAT3's functions and reveal the importance of both ON- and OFF-bipolar cells for high frequency light response.
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Affiliation(s)
- Evelyn C. Avilés
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
- Present address: Facultad de Ciencias Biologicas, Pontificia Universidad Catolica deChile, Santiago, Chile
| | - Sean K. Wang
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, MA 02115
- Howard Hughes Medical Institute, Boston, MA 02115
| | - Sarina Patel
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Shuxiang Shi
- Lingang Laboratory, Shanghai, China, 200031
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China, 201210
| | - Lucas Lin
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, MA 02115
| | - Vladimir J. Kefalov
- Gavin Herbert Eye Institute & Center for Translational Vision Research, University of California, Irvine, CA 92697
| | - Lisa V. Goodrich
- Department of Neurobiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Constance L. Cepko
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, MA 02115
- Howard Hughes Medical Institute, Boston, MA 02115
| | - Yunlu Xue
- Departments of Genetics and Ophthalmology, Harvard Medical School, Boston, MA 02115
- Lingang Laboratory, Shanghai, China, 200031
- Lead contact
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6
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Senapati S, Park PSH. Understanding the Rhodopsin Worldview Through Atomic Force Microscopy (AFM): Structure, Stability, and Activity Studies. CHEM REC 2023; 23:e202300113. [PMID: 37265335 PMCID: PMC10908267 DOI: 10.1002/tcr.202300113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/12/2023] [Indexed: 06/03/2023]
Abstract
Rhodopsin is a G protein-coupled receptor (GPCR) present in the rod outer segment (ROS) of photoreceptor cells that initiates the phototransduction cascade required for scotopic vision. Due to the remarkable advancements in technological tools, the chemistry of rhodopsin has begun to unravel especially over the past few decades, but mostly at the ensemble scale. Atomic force microscopy (AFM) is a tool capable of providing critical information from a single-molecule point of view. In this regard, to bolster our understanding of rhodopsin at the nanoscale level, AFM-based imaging, force spectroscopy, and nano-indentation techniques were employed on ROS disc membranes containing rhodopsin, isolated from vertebrate species both in normal and diseased states. These AFM studies on samples from native retinal tissue have provided fundamental insights into the structure and function of rhodopsin under normal and dysfunctional states. We review here the findings from these AFM studies that provide important insights on the supramolecular organization of rhodopsin within the membrane and factors that contribute to this organization, the molecular interactions stabilizing the structure of the receptor and factors that can modify those interactions, and the mechanism underlying constitutive activity in the receptor that can cause disease.
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Affiliation(s)
- Subhadip Senapati
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
- Prayoga Institute of Education Research, Bengaluru, KA 560116, India
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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7
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Zeitz C, Roger JE, Audo I, Michiels C, Sánchez-Farías N, Varin J, Frederiksen H, Wilmet B, Callebert J, Gimenez ML, Bouzidi N, Blond F, Guilllonneau X, Fouquet S, Léveillard T, Smirnov V, Vincent A, Héon E, Sahel JA, Kloeckener-Gruissem B, Sennlaub F, Morgans CW, Duvoisin RM, Tkatchenko AV, Picaud S. Shedding light on myopia by studying complete congenital stationary night blindness. Prog Retin Eye Res 2023; 93:101155. [PMID: 36669906 DOI: 10.1016/j.preteyeres.2022.101155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 01/20/2023]
Abstract
Myopia is the most common eye disorder, caused by heterogeneous genetic and environmental factors. Rare progressive and stationary inherited retinal disorders are often associated with high myopia. Genes implicated in myopia encode proteins involved in a variety of biological processes including eye morphogenesis, extracellular matrix organization, visual perception, circadian rhythms, and retinal signaling. Differentially expressed genes (DEGs) identified in animal models mimicking myopia are helpful in suggesting candidate genes implicated in human myopia. Complete congenital stationary night blindness (cCSNB) in humans and animal models represents an ON-bipolar cell signal transmission defect and is also associated with high myopia. Thus, it represents also an interesting model to identify myopia-related genes, as well as disease mechanisms. While the origin of night blindness is molecularly well established, further research is needed to elucidate the mechanisms of myopia development in subjects with cCSNB. Using whole transcriptome analysis on three different mouse models of cCSNB (in Gpr179-/-, Lrit3-/- and Grm6-/-), we identified novel actors of the retinal signaling cascade, which are also novel candidate genes for myopia. Meta-analysis of our transcriptomic data with published transcriptomic databases and genome-wide association studies from myopia cases led us to propose new biological/cellular processes/mechanisms potentially at the origin of myopia in cCSNB subjects. The results provide a foundation to guide the development of pharmacological myopia therapies.
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Affiliation(s)
- Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.
| | - Jérome E Roger
- Paris-Saclay Institute of Neuroscience, CERTO-Retina France, CNRS, Université Paris-Saclay, Saclay, France
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France; CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, France
| | | | | | - Juliette Varin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Helen Frederiksen
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Baptiste Wilmet
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Jacques Callebert
- Service of Biochemistry and Molecular Biology, INSERM U942, Hospital Lariboisière, APHP, Paris, France
| | | | - Nassima Bouzidi
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Frederic Blond
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Stéphane Fouquet
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Vasily Smirnov
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Elise Héon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON, Canada; Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, Canada; Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France; CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, Paris, France; Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Florian Sennlaub
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Catherine W Morgans
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR, USA
| | - Robert M Duvoisin
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR, USA
| | - Andrei V Tkatchenko
- Oujiang Laboratory, Zhejiang Laboratory for Regenerative Medicine, Vision and Brain Health, Wenzhou, China; Department of Ophthalmology, Edward S. Harkness Eye Institute, Columbia University, New York, NY, USA
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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8
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Wilmet B, Callebert J, Duvoisin R, Goulet R, Tourain C, Michiels C, Frederiksen H, Schaeffel F, Marre O, Sahel JA, Audo I, Picaud S, Zeitz C. Mice Lacking Gpr179 with Complete Congenital Stationary Night Blindness Are a Good Model for Myopia. Int J Mol Sci 2022; 24:ijms24010219. [PMID: 36613663 PMCID: PMC9820543 DOI: 10.3390/ijms24010219] [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: 10/04/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 12/25/2022] Open
Abstract
Mutations in GPR179 are one of the most common causes of autosomal recessive complete congenital stationary night blindness (cCSNB). This retinal disease is characterized in patients by impaired dim and night vision, associated with other ocular symptoms, including high myopia. cCSNB is caused by a complete loss of signal transmission from photoreceptors to ON-bipolar cells. In this study, we hypothesized that the lack of Gpr179 and the subsequent impaired ON-pathway could lead to myopic features in a mouse model of cCSNB. Using ultra performance liquid chromatography, we show that adult Gpr179-/- mice have a significant decrease in both retinal dopamine and 3,4-dihydroxyphenylacetic acid, compared to Gpr179+/+ mice. This alteration of the dopaminergic system is thought to be correlated with an increased susceptibility to lens-induced myopia but does not affect the natural refractive development. Altogether, our data added a novel myopia model, which could be used to identify therapeutic interventions.
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Affiliation(s)
- Baptiste Wilmet
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
- Correspondence: (B.W.); (C.Z.); Tel.: +33-1-53-46-25-26 (B.W.); +33-1-53-46-25-40 (C.Z.)
| | - Jacques Callebert
- Service of Biochemistry and Molecular Biology, INSERM U942, Hospital Lariboisière, AP-HP, 75010 Paris, France
| | - Robert Duvoisin
- Department of Chemical Physiology & Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | - Ruben Goulet
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Christophe Tourain
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
- Wavefront-Engineering Microscopy Group, Neurophotonics Laboratory, CNRS UMR8250, Paris Descartes University, 75270 Paris, France
| | - Christelle Michiels
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Helen Frederiksen
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Frank Schaeffel
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), 4056 Basel, Switzerland
- Section of Neurobiology of the Eye, Ophthalmic Research Institute, University of Tuebingen, 72076 Tuebingen, Germany
- Zeiss Vision Lab, Ophthalmic Research Institute, University of Tuebingen, 72076 Tuebingen, Germany
| | - Olivier Marre
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - José Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, 75012 Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, 75019 Paris, France
- Académie des Sciences, Institut de France, 75006 Paris, France
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC 1423, 75012 Paris, France
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 75012 Paris, France
- Correspondence: (B.W.); (C.Z.); Tel.: +33-1-53-46-25-26 (B.W.); +33-1-53-46-25-40 (C.Z.)
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9
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Divergent outer retinal circuits drive image and non-image visual behaviors. Cell Rep 2022; 39:111003. [PMID: 35767957 PMCID: PMC9400924 DOI: 10.1016/j.celrep.2022.111003] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/25/2022] [Accepted: 06/03/2022] [Indexed: 11/22/2022] Open
Abstract
Image- and non-image-forming vision are essential for animal behavior. Here we use genetically modified mouse lines to examine retinal circuits driving image- and non-image-functions. We describe the outer retinal circuits underlying the pupillary light response (PLR) and circadian photoentrainment, two non-image-forming behaviors. Rods and cones signal light increments and decrements through the ON and OFF pathways, respectively. We find that the OFF pathway drives image-forming vision but cannot drive circadian photoentrainment or the PLR. Cone light responses drive image formation but fail to drive the PLR. At photopic levels, rods use the primary and secondary rod pathways to drive the PLR, whereas at the scotopic and mesopic levels, rods use the primary pathway to drive the PLR, and the secondary pathway is insufficient. Circuit dynamics allow rod ON pathways to drive two non-image-forming behaviors across a wide range of light intensities, whereas the OFF pathway is potentially restricted to image formation.
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10
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Agosto MA, Adeosun AAR, Kumar N, Wensel TG. The mGluR6 ligand-binding domain, but not the C-terminal domain, is required for synaptic localization in retinal ON-bipolar cells. J Biol Chem 2021; 297:101418. [PMID: 34793838 PMCID: PMC8671642 DOI: 10.1016/j.jbc.2021.101418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/03/2021] [Accepted: 11/08/2021] [Indexed: 11/26/2022] Open
Abstract
Signals from retinal photoreceptors are processed in two parallel channels—the ON channel responds to light increments, while the OFF channel responds to light decrements. The ON pathway is mediated by ON type bipolar cells (BCs), which receive glutamatergic synaptic input from photoreceptors via a G-protein-coupled receptor signaling cascade. The metabotropic glutamate receptor mGluR6 is located at the dendritic tips of all ON-BCs and is required for synaptic transmission. Thus, it is critically important for delivery of information from photoreceptors into the ON pathway. In addition to detecting glutamate, mGluR6 participates in interactions with other postsynaptic proteins, as well as trans-synaptic interactions with presynaptic ELFN proteins. Mechanisms of mGluR6 synaptic targeting and functional interaction with other synaptic proteins are unknown. Here, we show that multiple regions in the mGluR6 ligand-binding domain are necessary for both synaptic localization in BCs and ELFN1 binding in vitro. However, these regions were not required for plasma membrane localization in heterologous cells, indicating that secretory trafficking and synaptic localization are controlled by different mechanisms. In contrast, the mGluR6 C-terminus was dispensable for synaptic localization. In mGluR6 null mice, localization of the postsynaptic channel protein TRPM1 was compromised. Introducing WT mGluR6 rescued TRPM1 localization, while a C-terminal deletion mutant had significantly reduced rescue ability. We propose a model in which trans-synaptic ELFN1 binding is necessary for mGluR6 postsynaptic localization, whereas the C-terminus has a role in mediating TRPM1 trafficking. These findings reveal different sequence determinants of the multifunctional roles of mGluR6 in ON-BCs.
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Affiliation(s)
- Melina A Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA.
| | - Abiodun Adefola R Adeosun
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA; Pharmacology and Chemical Biology Graduate Program, Baylor College of Medicine, Houston TX, USA
| | - Nitin Kumar
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston TX, USA; Pharmacology and Chemical Biology Graduate Program, Baylor College of Medicine, Houston TX, USA
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11
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Orhan E, Neuillé M, de Sousa Dias M, Pugliese T, Michiels C, Condroyer C, Antonio A, Sahel JA, Audo I, Zeitz C. A New Mouse Model for Complete Congenital Stationary Night Blindness Due to Gpr179 Deficiency. Int J Mol Sci 2021; 22:ijms22094424. [PMID: 33922602 PMCID: PMC8122890 DOI: 10.3390/ijms22094424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/19/2021] [Accepted: 04/20/2021] [Indexed: 01/24/2023] Open
Abstract
Mutations in GPR179 lead to autosomal recessive complete congenital stationary night blindness (cCSNB). This condition represents a signal transmission defect from the photoreceptors to the ON-bipolar cells. To confirm the phenotype, better understand the pathogenic mechanism in vivo, and provide a model for therapeutic approaches, a Gpr179 knock-out mouse model was genetically and functionally characterized. We confirmed that the insertion of a neo/lac Z cassette in intron 1 of Gpr179 disrupts the same gene. Spectral domain optical coherence tomography reveals no obvious retinal structure abnormalities. Gpr179 knock-out mice exhibit a so-called no-b-wave (nob) phenotype with severely reduced b-wave amplitudes in the electroretinogram. Optomotor tests reveal decreased optomotor responses under scotopic conditions. Consistent with the genetic disruption of Gpr179, GPR179 is absent at the dendritic tips of ON-bipolar cells. While proteins of the same signal transmission cascade (GRM6, LRIT3, and TRPM1) are correctly localized, other proteins (RGS7, RGS11, and GNB5) known to regulate GRM6 are absent at the dendritic tips of ON-bipolar cells. These results add a new model of cCSNB, which is important to better understand the role of GPR179, its implication in patients with cCSNB, and its use for the development of therapies.
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Affiliation(s)
- Elise Orhan
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Marion Neuillé
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Miguel de Sousa Dias
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Thomas Pugliese
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Christelle Michiels
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Christel Condroyer
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - Aline Antonio
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
| | - José-Alain Sahel
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC1423, F-75012 Paris, France
- Fondation Ophtalmologique Adolphe de Rothschild, F-75019 Paris, France
- Academie des Sciences, Institut de France, F-75006 Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Isabelle Audo
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, INSERM-DGOS CIC1423, F-75012 Paris, France
- Institute of Ophthalmology, University College of London, London EC1V 9EL, UK
| | - Christina Zeitz
- Institut de la Vision, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Sorbonne Université, F-75012 Paris, France; (E.O.); (M.N.); (M.d.S.D.); (T.P.); (C.M.); (C.C.); (A.A.); (J.-A.S.); (I.A.)
- Correspondence: ; Tel.: +33-1-53-46-25-40
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12
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Varin J, Bouzidi N, Dias MMDS, Pugliese T, Michiels C, Robert C, Desrosiers M, Sahel JA, Audo I, Dalkara D, Zeitz C. Restoration of mGluR6 Localization Following AAV-Mediated Delivery in a Mouse Model of Congenital Stationary Night Blindness. Invest Ophthalmol Vis Sci 2021; 62:24. [PMID: 33729473 PMCID: PMC7980044 DOI: 10.1167/iovs.62.3.24] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Complete congenital stationary night blindness (cCSNB) is an incurable inherited retinal disorder characterized by an ON-bipolar cell (ON-BC) defect. GRM6 mutations are the third most prevalent cause of cCSNB. The Grm6-/- mouse model mimics the human phenotype, showing no b-wave in the electroretinogram (ERG) and a loss of mGluR6 and other proteins of the same cascade at the outer plexiform layer (OPL). Our aim was to restore protein localization and function in Grm6-/- adult mice targeting specifically ON-BCs or the whole retina. Methods Adeno-associated virus-encoding Grm6 under two different promoters (GRM6-Grm6 and CAG-Grm6) were injected intravitreally in P15 Grm6-/- mice. ERG recordings at 2 and 4 months were performed in Grm6+/+, untreated and treated Grm6-/- mice. Similarly, immunolocalization studies were performed on retinal slices before or after treatment using antibodies against mGluR6, TRPM1, GPR179, RGS7, RGS11, Gβ5, and dystrophin. Results Following treatment, mGluR6 was localized to the dendritic tips of ON-BCs when expressed with either promoter. The relocalization efficiency in mGluR6-transduced retinas at the OPL was 2.5% versus 11% when the GRM6-Grm6 and CAG-Grm6 were used, respectively. Albeit no functional rescue was seen in ERGs, relocalization of TRPM1, GPR179, and Gβ5 was also noted using both constructs. The restoration of the localization of RGS7, RGS11, and dystrophin was more obvious in retinas treated with GRM6-Grm6 than in retinas treated with CAG-Grm6. Conclusions Our findings show the potential of treating cCSNB with GRM6 mutations; however, it appears that the transduction rate must be improved to restore visual function.
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Affiliation(s)
- Juliette Varin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Nassima Bouzidi
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Thomas Pugliese
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - Camille Robert
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | | | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Academie des Sciences, Institut de France, Paris, France.,Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, Paris, France.,Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
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13
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Senapati S, Park PSH. Differential adaptations in rod outer segment disc membranes in different models of congenital stationary night blindness. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183396. [PMID: 32533975 DOI: 10.1016/j.bbamem.2020.183396] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/01/2020] [Accepted: 06/08/2020] [Indexed: 01/20/2023]
Abstract
Rod photoreceptor cells initiate scotopic vision when the light receptor rhodopsin absorbs a photon of light to initiate phototransduction. These photoreceptor cells are exquisitely sensitive and have adaptive mechanisms in place to maintain optimal function and to overcome dysfunctional states. One adaptation rod photoreceptor cells exhibit is in the packing properties of rhodopsin within the membrane. The mechanism underlying these adaptations is unclear. Mouse models of congenital stationary night blindness with different molecular causes were investigated to determine which signals are important for adaptations in rod photoreceptor cells. Night blindness in these mice is caused by dysfunction in either rod photoreceptor cell signaling or bipolar cell signaling. Changes in the packing of rhodopsin within photoreceptor cell membranes were examined by atomic force microscopy. Mice expressing constitutively active rhodopsin did not exhibit any adaptations, even under constant dark conditions. Mice with disrupted bipolar cell signaling exhibited adaptations, however, they were distinct from those in mice with disrupted phototransduction. These differential adaptations demonstrate that although multiple molecular defects can lead to a similar primary defect causing disease (i.e., night blindness), they can cause different secondary effects (i.e., adaptations). The lighting environment or signaling defects present from birth and during early rearing can condition mice and affect the adaptations occurring in more mature animals. A comparison of effects in wild-type mice, mice with defective phototransduction, and mice with defective bipolar cell signaling, indicated that bipolar cell signaling plays a role in this conditioning but is not required for adaptations in more mature animals.
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Affiliation(s)
- Subhadip Senapati
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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14
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Furukawa T, Ueno A, Omori Y. Molecular mechanisms underlying selective synapse formation of vertebrate retinal photoreceptor cells. Cell Mol Life Sci 2020; 77:1251-1266. [PMID: 31586239 PMCID: PMC11105113 DOI: 10.1007/s00018-019-03324-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/21/2019] [Accepted: 09/25/2019] [Indexed: 11/29/2022]
Abstract
In vertebrate central nervous systems (CNSs), highly diverse neurons are selectively connected via synapses, which are essential for building an intricate neural network. The vertebrate retina is part of the CNS and is comprised of a distinct laminar organization, which serves as a good model system to study developmental synapse formation mechanisms. In the retina outer plexiform layer, rods and cones, two types of photoreceptor cells, elaborate selective synaptic contacts with ON- and/or OFF-bipolar cell terminals as well as with horizontal cell terminals. In the mouse retina, three photoreceptor subtypes and at least 15 bipolar subtypes exist. Previous and recent studies have significantly progressed our understanding of how selective synapse formation, between specific subtypes of photoreceptor and bipolar cells, is designed at the molecular level. In the ON pathway, photoreceptor-derived secreted and transmembrane proteins directly interact in trans with the GRM6 (mGluR6) complex, which is localized to ON-bipolar cell dendritic terminals, leading to selective synapse formation. Here, we review our current understanding of the key factors and mechanisms underlying selective synapse formation of photoreceptor cells with bipolar and horizontal cells in the retina. In addition, we describe how defects/mutations of the molecules involved in photoreceptor synapse formation are associated with human retinal diseases and visual disorders.
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Affiliation(s)
- Takahisa Furukawa
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Akiko Ueno
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Omori
- Laboratory for Molecular and Developmental Biology, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
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15
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Hasan N, Pangeni G, Ray TA, Fransen KM, Noel J, Borghuis BG, McCall MA, Gregg RG. LRIT3 is Required for Nyctalopin Expression and Normal ON and OFF Pathway Signaling in the Retina. eNeuro 2020; 7:ENEURO.0002-20.2020. [PMID: 31959619 PMCID: PMC7031853 DOI: 10.1523/eneuro.0002-20.2020] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 01/05/2020] [Indexed: 12/20/2022] Open
Abstract
The first retinal synapse, photoreceptor→bipolar cell (BC), is both anatomically and functionally complex. Within the same synaptic region, a change in presynaptic glutamate release is sensed by both ON BCs (DBCs) via the metabotropic glutamate receptor 6 (mGluR6), and OFF BCs (HBCs) via ionotropic glutamate receptors to establish parallel signaling pathways that preferentially encode light increments (ON) or decrements (OFF), respectively. The synaptic structural organization of ON and OFF-type BCs at the photoreceptor terminal differs. DBCs make an invaginating synapse that contains a diverse but incompletely understood complex of interacting proteins (signalplex). HBCs make primarily flat contacts that contain an apparent different set of proteins that is equally uncharacterized. LRIT3 is a synaptic protein known to be essential for ON pathway visual function. In both male and female mice, we demonstrate that LRIT3 interacts with and is required for expression of nyctalopin, and thus TRPM1 at all DBC dendritic tips, but DBC signalplex components are not required for LRIT3 expression. Using whole-cell and multielectrode array (MEA) electrophysiology and glutamate imaging, we demonstrate that the loss of LRIT3 impacts both ON and OFF signaling pathway function. Without LRIT3, excitatory input to type 1 BCs is reduced, as are the visually evoked responses of many OFF retinal ganglion cells (RGCs). We conclude that the absence of LRIT3 expression disrupts excitatory input to OFF BCs and, thus disrupts the normal function of OFF RGCs.
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Affiliation(s)
- Nazarul Hasan
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292
| | - Gobinda Pangeni
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292
| | - Thomas A Ray
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292
| | - Kathryn M Fransen
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292
| | - Jennifer Noel
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Bart G Borghuis
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292
| | - Ronald G Gregg
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40292
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16
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Kinoshita J, Hasan N, Bell BA, Peachey NS. Reduced expression of the nob8 gene does not normalize the distribution or function of mGluR6 in the mouse retina. Mol Vis 2019; 25:890-901. [PMID: 32025181 PMCID: PMC6982428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 12/30/2019] [Indexed: 11/21/2022] Open
Abstract
Purpose The Grm6nob8 mouse carries a missense mutation in the Grm6 gene (p.Met66Leu), and exhibits a reduced b-wave of the electroretinogram (ERG), abnormal localization of metabotropic glutamate receptor 6 (mGluR6) to the depolarizing bipolar cell (DBC) soma, and a reduced level of mGluR6 at the DBC dendritic tips. Although the underlying mechanism remains unknown, one possible explanation is that DBCs cannot efficiently traffic the mutant mGluR6. In that scenario, reducing the total amount of mutant mGluR6 protein might normalize localization, and thus, improve the ERG phenotype as well. The second purpose of this study was to determine whether the abnormal cellular distribution of mutant mGluR6 in Grm6nob8 retinas might induce late onset DBC degeneration. Methods We crossed Grm6nob8 animals with Grm6nob3 mice, which carry a null mutation in Grm6, to generate Grm6nob3/nob8 compound heterozygotes. We used western blotting to measure the total mGluR6 content, and immunohistochemistry to document mGluR6 localization within DBCs. In addition, we examined outer retinal function with ERG and retinal architecture in vivo with spectral domain optical coherence tomography (SD-OCT). Results The retinal content of mGluR6 was reduced in the retinas of the Grm6nob3/nob8 compound heterozygotes compared to the Grm6nob8 homozygotes. The cellular distribution of mGluR6 in the Grm6nob3/nob8 compound heterozygotes matched that of the Grm6nob8 homozygotes, with extensive expression throughout the DBC cell body and limited expression at the DBC dendritic tips. The dark-adapted ERG b-waves of the Grm6nob3/nob8 mice were reduced in comparison to those of the Grm6nob8 homozygotes at postnatal day 21 and 28. The overall ERG waveforms obtained from 4- through 68-week old Grm6nob8 mice were in general agreement for dark- and light-adapted conditions. The maximum response and sensitivity of the dark-adapted ERG b-wave did not change statistically significantly with age. SD-OCT revealed the maintained laminar structure of the retina, including a clear inner nuclear layer (INL) at each age examined (from 11 to 57 weeks old), although the INL in the mice older than 39 weeks of age was somewhat thinner than that seen at 11 weeks. Conclusions Mislocalization of mutant mGluR6 is not normalized by reducing the total mGluR6. Mislocalized mutant mGluR6 does not trigger substantial loss of DBCs.
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Affiliation(s)
| | - Nazarul Hasan
- Department of Biochemistry & Molecular Genetics, University of Louisville, Louisville, KY
| | | | - Neal S. Peachey
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, OH
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH
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17
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Das RG, Becker D, Jagannathan V, Goldstein O, Santana E, Carlin K, Sudharsan R, Leeb T, Nishizawa Y, Kondo M, Aguirre GD, Miyadera K. Genome-wide association study and whole-genome sequencing identify a deletion in LRIT3 associated with canine congenital stationary night blindness. Sci Rep 2019; 9:14166. [PMID: 31578364 PMCID: PMC6775105 DOI: 10.1038/s41598-019-50573-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 09/05/2019] [Indexed: 01/11/2023] Open
Abstract
Congenital stationary night blindness (CSNB), in the complete form, is caused by dysfunctions in ON-bipolar cells (ON-BCs) which are secondary neurons of the retina. We describe the first disease causative variant associated with CSNB in the dog. A genome-wide association study using 12 cases and 11 controls from a research colony determined a 4.6 Mb locus on canine chromosome 32. Subsequent whole-genome sequencing identified a 1 bp deletion in LRIT3 segregating with CSNB. The canine mutant LRIT3 gives rise to a truncated protein with unaltered subcellular expression in vitro. Genetic variants in LRIT3 have been associated with CSNB in patients although there is limited evidence regarding its apparently critical function in the mGluR6 pathway in ON-BCs. We determine that in the canine CSNB retina, the mutant LRIT3 is correctly localized to the region correlating with the ON-BC dendritic tips, albeit with reduced immunolabelling. The LRIT3-CSNB canine model has direct translational potential enabling studies to help understand the CSNB pathogenesis as well as to develop new therapies targeting the secondary neurons of the retina.
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Affiliation(s)
- Rueben G Das
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America
| | - Doreen Becker
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America.,Institute of Genome Biology, Leibniz Institute for Farm Animal Biology, Dummerstorf, Germany
| | | | - Orly Goldstein
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Evelyn Santana
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America
| | - Kendall Carlin
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America
| | - Raghavi Sudharsan
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America
| | - Tosso Leeb
- Institute of Genetics, University of Bern, Bern, Switzerland
| | - Yuji Nishizawa
- Department of Biomedical Sciences, Chubu University, Kasugai, Aichi, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Gustavo D Aguirre
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America
| | - Keiko Miyadera
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Pennsylvania, United States of America.
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18
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Abstract
The transient receptor potential channel TRPM1 is required for synaptic transmission between photoreceptors and the ON subtype of bipolar cells (ON-BPC), mediating depolarization in response to light. TRPM1 is present in the somas and postsynaptic dendritic tips of ON-BPCs. Monoclonal antibodies generated against full-length TRPM1 were found to have differential labeling patterns when used to immunostain the mouse retina, with some yielding reduced labeling of dendritic tips relative to the labeling of cell bodies. Epitope mapping revealed that those antibodies that poorly label the dendritic tips share a binding site (N2d) in the N-terminal arm near the transmembrane domain. A major splice variant of TRPM1 lacking exon 19 does not contain the N2d binding site, but quantitative immunoblotting revealed no enrichment of this variant in synaptsomes. One explanation of the differential labeling is masking of the N2d epitope by formation of a synapse-specific multiprotein complex. Identifying the binding partners that are specific for the fraction of TRPM1 present at the synapses is an ongoing challenge for understanding TRPM1 function.
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19
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Agosto MA, Anastassov IA, Robichaux MA, Wensel TG. A Large Endoplasmic Reticulum-Resident Pool of TRPM1 in Retinal ON-Bipolar Cells. eNeuro 2018; 5:ENEURO.0143-18.2018. [PMID: 30027108 PMCID: PMC6051591 DOI: 10.1523/eneuro.0143-18.2018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 12/22/2022] Open
Abstract
The chemical signal of light onset, a decrease in glutamate release from rod and cone photoreceptors, is processed by a postsynaptic G protein signaling cascade in ON-bipolar cells (BPCs). The metabotropic glutamate receptor mGluR6, along with other cascade elements, is localized synaptically at the BPC dendritic tips. The effector ion channel protein transient receptor potential melastatin-1 (TRPM1), in contrast, is located not only at the dendritic tips but also in BPC bodies and axons. Little is known about the intracellular localization of TRPM1, or its trafficking route to the dendritic tip plasma membrane. Recombinant TRPM1 expressed in mammalian cells colocalized with endoplasmic reticulum (ER) markers, with little or none detected at the plasma membrane. In mouse retina, somatic TRPM1 was similarly intracellular, and not at the plasma membrane. Labeling of ER membranes by expression of a fluorescent marker showed that in BPCs the ER extends into axons and dendrites, but not dendritic tips. In cell bodies, TRPM1 colocalized with the ER, and not with the Golgi apparatus. Fluorescence protease protection (FPP) assays with TRPM1-GFP fusions in heterologous cells revealed that the N and C termini are both accessible to the cytoplasm, consistent with the transmembrane domain topology of related TRP channels. These results indicate that the majority of TRPM1 is present in the ER, from which it can potentially be transported to the dendritic tips as needed for ON light responses. The excess of ER-resident TRPM1 relative to the amount needed at the dendritic tips suggests a potential new function for TRPM1 in the ER.
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Affiliation(s)
- Melina A. Agosto
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Ivan A. Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Michael A. Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
| | - Theodore G. Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030
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20
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Neuillé M, Cao Y, Caplette R, Guerrero-Given D, Thomas C, Kamasawa N, Sahel JA, Hamel CP, Audo I, Picaud S, Martemyanov KA, Zeitz C. LRIT3 Differentially Affects Connectivity and Synaptic Transmission of Cones to ON- and OFF-Bipolar Cells. Invest Ophthalmol Vis Sci 2017; 58:1768-1778. [PMID: 28334377 PMCID: PMC5374884 DOI: 10.1167/iovs.16-20745] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). Using a cCSNB mouse model lacking Lrit3 (nob6), we recently have shown that LRIT3 has a role in the correct localization of TRPM1 (transient receptor potential melastatin 1) to the dendritic tips of ON-bipolar cells (BCs), contacting both rod and cone photoreceptors. Furthermore, postsynaptic clustering of other mGluR6 cascade components is selectively eliminated at the dendritic tips of cone ON-BCs. The purpose of this study was to further define the role of LRIT3 in structural and functional organization of cone synapses. Methods Exhaustive electroretinogram analysis was performed in a patient with LRIT3 mutations. Multielectrode array recordings were performed at the level of retinal ganglion cells in nob6 mice. Targeting of GluR1 and GluR5 at the dendritic tips of OFF-BCs in nob6 retinas was assessed by immunostaining and confocal microscopy. The ultrastructure of photoreceptor synapses was evaluated by electron microscopy in nob6 mice. Results The patient with LRIT3 mutations had a selective ON-BC dysfunction with relatively preserved OFF-BC responses. In nob6 mice, complete lack of ON-pathway function with robust, yet altered signaling processing in OFF-pathways was detected. Consistent with these observations, molecules essential for the OFF-BC signaling were normally targeted to the synapse. Finally, synaptic contacts made by ON-BC but not OFF-BC neurons with the cone pedicles were disorganized without ultrastructural alterations in cone terminals, horizontal cell processes, or synaptic ribbons. Conclusions These results suggest that LRIT3 is likely involved in coordination of the transsynaptic communication between cones and ON-BCs during synapse formation and function.
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Affiliation(s)
- Marion Neuillé
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Romain Caplette
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | | | - Connon Thomas
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - Naomi Kamasawa
- Max Planck Florida Institute for Neuroscience, Jupiter, Florida United States
| | - José-Alain Sahel
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom 6Fondation Ophtalmologique Adolphe de Rothschild, Paris, France 8Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Christian P Hamel
- INSERM U583, Physiopathologie et thérapie des déficits sensoriels et moteurs, Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, Montpellier, France
| | - Isabelle Audo
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France 4CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC1423, Paris, France 5Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Serge Picaud
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida United States
| | - Christina Zeitz
- Sorbonne Universités, UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Paris, France
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21
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Peachey NS, Hasan N, FitzMaurice B, Burrill S, Pangeni G, Karst SY, Reinholdt L, Berry ML, Strobel M, Gregg RG, McCall MA, Chang B. A missense mutation in Grm6 reduces but does not eliminate mGluR6 expression or rod depolarizing bipolar cell function. J Neurophysiol 2017; 118:845-854. [PMID: 28490646 DOI: 10.1152/jn.00888.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 05/03/2017] [Accepted: 05/03/2017] [Indexed: 01/01/2023] Open
Abstract
GRM6 encodes the metabotropic glutamate receptor 6 (mGluR6) used by retinal depolarizing bipolar cells (DBCs). Mutations in GRM6 lead to DBC dysfunction and underlie the human condition autosomal recessive complete congenital stationary night blindness. Mouse mutants for Grm6 are important models for this condition. Here we report a new Grm6 mutant, identified in an electroretinogram (ERG) screen of mice maintained at The Jackson Laboratory. The Grm6nob8 mouse has a reduced-amplitude b-wave component of the ERG, which reflects light-evoked DBC activity. Sequencing identified a missense mutation that converts a highly conserved methionine within the ligand binding domain to leucine (p.Met66Leu). Consistent with prior studies of Grm6 mutant mice, the laminar size and structure in the Grm6nob8 retina were comparable to control. The Grm6nob8 phenotype is distinguished from other Grm6 mutants that carry a null allele by a reduced but not absent ERG b-wave, decreased but present expression of mGluR6 at DBC dendritic tips, and mislocalization of mGluR6 to DBC somas. Consistent with a reduced but not absent b-wave, there were a subset of retinal ganglion cells whose responses to light onset have times to peak within the range of those in control retinas. These data indicate that the p.Met66Leu mutant mGluR6 is trafficked less than control. However, the mGluR6 that is localized to the DBC dendritic tips is able to initiate DBC signal transduction. The Grm6nob8 mouse extends the Grm6 allelic series and will be useful for elucidating the role of mGluR6 in DBC signal transduction and in human disease.NEW & NOTEWORTHY This article describes a mouse model of the human disease complete congenital stationary night blindness in which the mutation reduces but does not eliminate GRM6 expression and bipolar cell function, a distinct phenotype from that seen in other Grm6 mouse models.
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Affiliation(s)
- Neal S Peachey
- Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio.,Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio.,Department of Ophthalmology, Cleveland Clinic College of Medicine of Case Western Reserve University, Cleveland, Ohio
| | - Nazarul Hasan
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky
| | | | | | - Gobinda Pangeni
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and
| | | | | | | | | | - Ronald G Gregg
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky.,Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and
| | - Maureen A McCall
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky; and.,Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine;
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22
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Wang Y, Fehlhaber KE, Sarria I, Cao Y, Ingram NT, Guerrero-Given D, Throesch B, Baldwin K, Kamasawa N, Ohtsuka T, Sampath AP, Martemyanov KA. The Auxiliary Calcium Channel Subunit α2δ4 Is Required for Axonal Elaboration, Synaptic Transmission, and Wiring of Rod Photoreceptors. Neuron 2017; 93:1359-1374.e6. [PMID: 28262416 PMCID: PMC5364038 DOI: 10.1016/j.neuron.2017.02.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 12/31/2016] [Accepted: 02/08/2017] [Indexed: 11/24/2022]
Abstract
Neural circuit wiring relies on selective synapse formation whereby a presynaptic release apparatus is matched with its cognate postsynaptic machinery. At metabotropic synapses, the molecular mechanisms underlying this process are poorly understood. In the mammalian retina, rod photoreceptors form selective contacts with rod ON-bipolar cells by aligning the presynaptic voltage-gated Ca2+ channel directing glutamate release (CaV1.4) with postsynaptic mGluR6 receptors. We show this coordination requires an extracellular protein, α2δ4, which complexes with CaV1.4 and the rod synaptogenic mediator, ELFN1, for trans-synaptic alignment with mGluR6. Eliminating α2δ4 in mice abolishes rod synaptogenesis and synaptic transmission to rod ON-bipolar cells, and disrupts postsynaptic mGluR6 clustering. We further find that in rods, α2δ4 is crucial for organizing synaptic ribbons and setting CaV1.4 voltage sensitivity. In cones, α2δ4 is essential for CaV1.4 function, but is not required for ribbon organization, synaptogenesis, or synaptic transmission. These findings offer insights into retinal pathologies associated with α2δ4 dysfunction.
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Affiliation(s)
- Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Katherine E Fehlhaber
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ignacio Sarria
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Norianne T Ingram
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Debbie Guerrero-Given
- Electron Microscopy Core Facility, Max Planck Florida Institute, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Ben Throesch
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92121, USA
| | - Kristin Baldwin
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92121, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute, 1 Max Planck Way, Jupiter, FL 33458, USA
| | - Toshihisa Ohtsuka
- Department of Biochemistry, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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23
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Identification of a new mutant allele, Grm6(nob7), for complete congenital stationary night blindness. Vis Neurosci 2016; 32:E004. [PMID: 26241901 DOI: 10.1017/s0952523815000012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Electroretinogram (ERG) studies identified a new mouse line with a normal a-wave but lacking the b-wave component. The ERG phenotype of this new allele, nob7, matched closely that of mouse mutants for Grm6, Lrit3, Trpm1, and Nyx, which encode for proteins expressed in depolarizing bipolar cells (DBCs). To identify the underlying mutation, we first crossed nob7 mice with Grm6 nob3 mutants and measured the ERGs in offspring. All the offspring lacked the b-wave, indicating that nob7 is a new allele for Grm6: Grm6 nob7 . Sequence analyses of Grm6 nob7 cDNAs identified a 28 base pair insertion between exons 8 and 9, which would result in a frameshift mutation in the open reading frame that encodes the metabotropic glutamate receptor 6 (Grm6). Sequencing both the cDNA and genomic DNA from exon 8 and intron 8, respectively, from the Grm6 nob7 mouse revealed a G to A transition at the last position in exon 8. This mutation disrupts splicing and the normal exon 8 is extended by 28 base pairs, because splicing occurs 28 base pairs downstream at a cryptic splice donor. Consistent with the impact of the resulting frameshift mutation, there is a loss of mGluR6 protein (encoded by Grm6) from the dendritic tips of DBCs in the Grm6 nob7 retina. These results indicate that Grm6 nob7 is a new model of the complete form of congenital stationary night blindness, a human condition that has been linked to mutations of GRM6.
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24
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Chang B. Mouse Models as Tools to Identify Genetic Pathways for Retinal Degeneration, as Exemplified by Leber's Congenital Amaurosis. Methods Mol Biol 2016; 1438:417-430. [PMID: 27150101 DOI: 10.1007/978-1-4939-3661-8_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Leber's congenital amaurosis (LCA) is an inherited retinal degenerative disease characterized by severe loss of vision in the first year of life. In addition to early vision loss, a variety of other eye-related abnormalities including roving eye movements, deep-set eyes, and sensitivity to bright light also occur with this disease. Many animal models of LCA are available and the study them has led to a better understanding of the pathology of the disease, and has led to the development of therapeutic strategies aimed at curing or slowing down LCA. Mouse models, with their well-developed genetics and similarity to human physiology and anatomy, serve as powerful tools with which to investigate the etiology of human LCA. Such mice provide reproducible, experimental systems for elucidating pathways of normal development, function, designing strategies and testing compounds for translational research and gene-based therapies aimed at delaying the diseases progression. In this chapter, I describe tools used in the discovery and evaluation of mouse models of LCA including a Phoenix Image-Guided Optical Coherence Tomography (OCT) and a Diagnosys Espion Visual Electrophysiology System. Three mouse models are described, the rd3 mouse model for LCA12 and LCA1, the rd12 mouse model for LCA2, and the rd16 mouse model for LCA10.
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Affiliation(s)
- Bo Chang
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME, 04609, USA.
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25
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Naeem MA, Gottsch ADH, Ullah I, Khan SN, Husnain T, Butt NH, Qazi ZA, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Mutations in GRM6 identified in consanguineous Pakistani families with congenital stationary night blindness. Mol Vis 2015; 21:1261-71. [PMID: 26628857 PMCID: PMC4636350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/28/2015] [Indexed: 12/03/2022] Open
Abstract
PURPOSE This study was undertaken to investigate the causal mutations responsible for autosomal recessive congenital stationary night blindness (CSNB) in consanguineous Pakistani families. METHODS Two consanguineous families with multiple individuals manifesting symptoms of stationary night blindness were recruited. Affected individuals underwent a detailed ophthalmological examination, including fundus examination and electroretinography. Blood samples were collected and genomic DNA was extracted. Exclusion analyses were completed by genotyping closely spaced microsatellite markers, and two-point logarithm of odds (LOD) scores were calculated. All coding exons, along with the exon-intron boundaries of GRM6, were sequenced bidirectionally. RESULTS According to the medical history available to us, affected individuals in both families had experienced night blindness from the early years of their lives. Fundus photographs of affected individuals in both the families appeared normal, with no signs of attenuated arteries or bone spicule pigmentation. The scotopic electroretinogram (ERG) response were absent in all of the affected individuals, while the photopic measurements show reduced b-waves. During exclusion analyses, both families localized to a region on chromosome 5q that harbors GRM6, a gene previously associated with autosomal recessive CSNB. Bidirectional sequencing of GRM6 identified homozygous single base pair changes, specifically c.1336C>T (p.R446X) and c.2267G>A (p.G756D) in families PKRP170 and PKRP172, respectively. CONCLUSIONS We identified a novel nonsense and a previously reported missense mutation in GRM6 that were responsible for autosomal recessive CSNB in patients of Pakistani decent.
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Affiliation(s)
- Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Tayyab Husnain
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Nadeem H. Butt
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan
| | | | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California San Diego, La Jolla CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore MD
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26
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Neuillé M, Morgans CW, Cao Y, Orhan E, Michiels C, Sahel JA, Audo I, Duvoisin RM, Martemyanov KA, Zeitz C. LRIT3 is essential to localize TRPM1 to the dendritic tips of depolarizing bipolar cells and may play a role in cone synapse formation. Eur J Neurosci 2015; 42:1966-75. [PMID: 25997951 DOI: 10.1111/ejn.12959] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/30/2015] [Accepted: 05/17/2015] [Indexed: 02/06/2023]
Abstract
Mutations in LRIT3 lead to complete congenital stationary night blindness (cCSNB). The exact role of LRIT3 in ON-bipolar cell signaling cascade remains to be elucidated. Recently, we have characterized a novel mouse model lacking Lrit3 [no b-wave 6, (Lrit3(nob6/nob6) )], which displays similar abnormalities to patients with cCSNB with LRIT3 mutations. Here we compare the localization of components of the ON-bipolar cell signaling cascade in wild-type and Lrit3(nob6/nob6) retinal sections by immunofluorescence confocal microscopy. An anti-LRIT3 antibody was generated. Immunofluorescent staining of LRIT3 in wild-type mice revealed a specific punctate labeling in the outer plexiform layer (OPL), which was absent in Lrit3(nob6/nob6) mice. LRIT3 did not co-localize with ribeye or calbindin but co-localized with mGluR6. TRPM1 staining was severely decreased at the dendritic tips of all depolarizing bipolar cells in Lrit3(nob6/nob6) mice. mGluR6, GPR179, RGS7, RGS11 and Gβ5 immunofluorescence was absent at the dendritic tips of cone ON-bipolar cells in Lrit3(nob6/nob6) mice, while it was present at the dendritic tips of rod bipolar cells. Furthermore, peanut agglutinin (PNA) labeling was severely reduced in the OPL in Lrit3(nob6/nob6) mice. This study confirmed the localization of LRIT3 at the dendritic tips of depolarizing bipolar cells in mouse retina and demonstrated the dependence of TRPM1 localization on the presence of LRIT3. As tested components of the ON-bipolar cell signaling cascade and PNA revealed disrupted localization, an additional function of LRIT3 in cone synapse formation is suggested. These results point to a possibly different regulation of the mGluR6 signaling cascade between rod and cone ON-bipolar cells.
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Affiliation(s)
- Marion Neuillé
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - Catherine W Morgans
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Elise Orhan
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - Christelle Michiels
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
| | - José-Alain Sahel
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.,Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC, 1423, Paris, F-75012, France.,Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.,Fondation Ophtalmologique Adolphe de Rothschild, Paris, F-75019, France.,Académie des Sciences-Institut de France, Paris, F-75006, France
| | - Isabelle Audo
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France.,Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU ViewMaintain, INSERM-DHOS CIC, 1423, Paris, F-75012, France.,Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK
| | - Robert M Duvoisin
- Department of Physiology & Pharmacology, Oregon Health & Science University, Portland, OR, 97239, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, 33458, USA
| | - Christina Zeitz
- INSERM, U968, Paris, F-75012, France.,CNRS, UMR_7210, Paris, F-75012, France.,Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, F-75012, France
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27
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Congenital stationary night blindness: An analysis and update of genotype–phenotype correlations and pathogenic mechanisms. Prog Retin Eye Res 2015; 45:58-110. [DOI: 10.1016/j.preteyeres.2014.09.001] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/25/2014] [Accepted: 09/30/2014] [Indexed: 01/18/2023]
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28
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Gene therapy restores vision in rd1 mice after removal of a confounding mutation in Gpr179. Nat Commun 2015; 6:6006. [PMID: 25613321 PMCID: PMC4354202 DOI: 10.1038/ncomms7006] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 12/01/2014] [Indexed: 12/21/2022] Open
Abstract
The rd1 mouse with a mutation in the Pde6b gene was the first strain of mice identified with a retinal degeneration. However, AAV-mediated gene supplementation of rd1 mice only results in structural preservation of photoreceptors, and restoration of the photoreceptor-mediated a-wave, but not in restoration of the bipolar cell-mediated b-wave. Here we show that a mutation in Gpr179 prevents the full restoration of vision in rd1 mice. Backcrossing rd1 with C57BL6 mice reveals the complete lack of b-wave in a subset of mice, consistent with an autosomal recessive Mendelian inheritance pattern. We identify a mutation in the Gpr179 gene, which encodes for a G-protein coupled receptor localized to the dendrites of ON-bipolar cells. Gene replacement in rd1 mice that are devoid of the mutation in Gpr179 successfully restores the function of both photoreceptors and bipolar cells, which is maintained for up to 13 months. Our discovery may explain the failure of previous gene therapy attempts in rd1 mice, and we propose that Grp179 mutation status should be taken into account in future studies involving rd1 mice.
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29
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Effects of mGluR6-deficiency on photoreceptor ribbon synapse formation: comparison of electron microscopic analysis of serial sections with random sections. Vis Neurosci 2015; 31:39-46. [PMID: 24801622 DOI: 10.1017/s0952523813000473] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This study examined the effects of metabotropic glutamate receptor 6 (mGluR6) deficiency on ribbon synapse formation in rod spherules and cone pedicles using serial-section electron microscopy. In a wild-type (WT) mouse, only 3% of spherules had one invaginating bipolar dendrite (1B-type) and 97% of spherules were 2B-type. In contrast, in an mGluR6-knockout (KO) mouse, 29% of spherules were 1B-type and 71% of spherules were 2B-type. Spherules without bipolar invagination were not observed in either genotype. The single invaginating dendrites in 1B-type spherules were larger and the surface areas of synaptic ribbons were 23% smaller in the mGluR6-KO mouse than in the WT mouse. In cones, the number of invaginating bipolar dendrites decreased from 12 in the WT mouse to 9.5 in the mGluR6-KO mouse. This decrease correlated with a decrease in the number of cone synaptic ribbons from 10 in the WT mouse to 8 in the mGluR6-KO mouse. The mGluR6-KO phenotype showed negative effects on ribbon synapse formation. This negativity was similar to those in mGluR6-nob4, Gβ3-KO, Gβ5-KO, and RGS-7:RGS-11 double-KO mice, but the detailed manners and degrees of alterations appeared to vary depending on different missing components. Two published morphological assessments of the RGS-7:RGS-11 double-KO phenotype reported conflicting data; therefore, we tested the statistical techniques used in the two analyses. One statistical evaluation measure was effective in identifying a significant difference in structure between the mutant and WT phenotypes, whereas the other measure was ineffective. Conventional random section analysis using the effective measure provided sufficient data for a statistical test of the occurrence of structural changes. However, serial section analysis was required to determine the absolute numbers of ribbons and invaginating dendrites and to estimate structural parameters such as ribbon surface area.
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30
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Martemyanov KA. G protein signaling in the retina and beyond: the Cogan lecture. Invest Ophthalmol Vis Sci 2014; 55:8201-7. [PMID: 25511392 PMCID: PMC4541486 DOI: 10.1167/iovs.14-15928] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Kirill A. Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, United States
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31
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Neuillé M, El Shamieh S, Orhan E, Michiels C, Antonio A, Lancelot ME, Condroyer C, Bujakowska K, Poch O, Sahel JA, Audo I, Zeitz C. Lrit3 deficient mouse (nob6): a novel model of complete congenital stationary night blindness (cCSNB). PLoS One 2014; 9:e90342. [PMID: 24598786 PMCID: PMC3943948 DOI: 10.1371/journal.pone.0090342] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/31/2014] [Indexed: 01/10/2023] Open
Abstract
Mutations in LRIT3, coding for a Leucine-Rich Repeat, immunoglobulin-like and transmembrane domains 3 protein lead to autosomal recessive complete congenital stationary night blindness (cCSNB). The role of the corresponding protein in the ON-bipolar cell signaling cascade remains to be elucidated. Here we genetically and functionally characterize a commercially available Lrit3 knock-out mouse, a model to study the function and the pathogenic mechanism of LRIT3. We confirm that the insertion of a Bgeo/Puro cassette in the knock-out allele introduces a premature stop codon, which presumably codes for a non-functional protein. The mouse line does not harbor other mutations present in common laboratory mouse strains or in other known cCSNB genes. Lrit3 mutant mice exhibit a so-called no b-wave (nob) phenotype with lacking or severely reduced b-wave amplitudes in the scotopic and photopic electroretinogram (ERG), respectively. Optomotor tests reveal strongly decreased optomotor responses in scotopic conditions. No obvious fundus auto-fluorescence or histological retinal structure abnormalities are observed. However, spectral domain optical coherence tomography (SD-OCT) reveals thinned inner nuclear layer and part of the retina containing inner plexiform layer, ganglion cell layer and nerve fiber layer in these mice. To our knowledge, this is the first time that SD-OCT technology is used to characterize an animal model for CSNB. This phenotype is noted at 6 weeks and at 6 months. The stationary nob phenotype of mice lacking Lrit3, which we named nob6, confirms the findings previously reported in patients carrying LRIT3 mutations and is similar to other cCSNB mouse models. This novel mouse model will be useful for investigating the pathogenic mechanism(s) associated with LRIT3 mutations and clarifying the role of LRIT3 in the ON-bipolar cell signaling cascade.
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Affiliation(s)
- Marion Neuillé
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Said El Shamieh
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Elise Orhan
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Christelle Michiels
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Aline Antonio
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France
| | - Marie-Elise Lancelot
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Christel Condroyer
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
| | - Kinga Bujakowska
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
- Massachusetts Eye and Ear Infirmary, Ocular Genomics Institute, Boston, Massachusetts, United States of America
| | - Olivier Poch
- Laboratoire de Bioinformatique Intégrative et Génomique, ICube, CNRS, UMR_7357, Strasbourg, France
| | - José-Alain Sahel
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France
- Institute of Ophthalmology, University College of London, London, United Kingdom
- Fondation Ophtalmologique Adolphe de Rothschild, Paris, France
- Académie des Sciences–Institut de France, Paris, France
| | - Isabelle Audo
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, INSERM-DHOS CIC 503, Paris, France
- Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Christina Zeitz
- INSERM, U968, Paris, France
- CNRS, UMR_7210, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 968, Institut de la Vision, Paris, France
- * E-mail:
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Sarnaik R, Chen H, Liu X, Cang J. Genetic disruption of the On visual pathway affects cortical orientation selectivity and contrast sensitivity in mice. J Neurophysiol 2014; 111:2276-86. [PMID: 24598523 DOI: 10.1152/jn.00558.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The retina signals stimulus contrast via parallel On and Off pathways and sends the information to higher visual centers. Here we study the role of the On pathway using mice that have null mutations in the On-specific GRM6 receptor in the retina (Pinto LH, Vitaterna MH, Shimomura K, Siepka SM, Balannik V, McDearmon EL, Omura C, Lumayag S, Invergo BM, Brandon M, Glawe B, Cantrell DR, Donald R, Inayat S, Olvera MA, Vessey KA, Kirstan A, McCall MA, Maddox D, Morgans CW, Young B, Pletcher MT, Mullins RF, Troy JB, Takahashi JS. Vis Neurosci 24: 111-123, 2007; Maddox DM, Vessey KA, Yarbrough GL, Invergo BM, Cantrell DR, Inayat S, Balannik V, Hicks WL, Hawes NL, Byers S, Smith RS, Hurd R, Howell D, Gregg RG, Chang B, Naggert JK, Troy JB, Pinto LH, Nishina PM, McCall MA. J Physiol 586: 4409-4424, 2008). In these "nob" mice, single unit recordings in the primary visual cortex (V1) reveal degraded selectivity for orientations due to an increased response at nonpreferred orientations. Contrast sensitivity in the nob mice is reduced with severe deficits at low contrast, consistent with the phenotype of night blindness in human patients with mutations in Grm6. These cortical deficits can be largely explained by reduced input drive and increased response variability seen in nob V1. Interestingly, increased variability is also observed in the superior colliculus of these mice but does not affect its tuning properties. Further, the increased response variability in the nob mice is traced to the retina, a result phenocopied by acute pharmacological blockade of the On pathway in wild-type retina. Together, our results suggest that the On and Off pathways normally interact to increase response reliability in the retina, which in turn propagates to various central visual targets and affects their functional properties.
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Affiliation(s)
- Rashmi Sarnaik
- Department of Neurobiology, Northwestern University, Evanston, Illinois; Interdepartmental Neuroscience Program, Northwestern University, Evanston, Illinois; and
| | - Hui Chen
- Department of Ophthalmology, Northwestern University, Evanston, Illinois
| | - Xiaorong Liu
- Department of Neurobiology, Northwestern University, Evanston, Illinois; Department of Ophthalmology, Northwestern University, Evanston, Illinois
| | - Jianhua Cang
- Department of Neurobiology, Northwestern University, Evanston, Illinois;
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Abstract
The b-wave is a major component of the electroretinogram that reflects the activity of depolarizing bipolar cells (DBCs). The b-wave is used diagnostically to identify patients with defects in DBC signaling or in transmission from photoreceptors to DBCs. In mouse models, an abnormal b-wave has been used to demonstrate a critical role of a particular protein in the release of glutamate from photoreceptor terminals, in establishing the structure of the photoreceptor-to-DBC synapse, in DBC signal transduction, and also in DBC development, survival, or metabolic support. The purpose of this review is to summarize these models and how they have advanced our understanding of outer retinal function.
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Balmer J, Ji R, Ray TA, Selber F, Gassmann M, Peachey NS, Gregg RG, Enzmann V. Presence of the Gpr179(nob5) allele in a C3H-derived transgenic mouse. Mol Vis 2013; 19:2615-25. [PMID: 24415894 PMCID: PMC3883591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 12/27/2013] [Indexed: 10/27/2022] Open
Abstract
PURPOSE To identify the mutation responsible for an abnormal electroretinogram (ERG) in a transgenic mouse line (tg21) overexpressing erythropoietin (Epo). The tg21 line was generated on a mixed (C3H; C57BL/6) background and lacked the b-wave component of the ERG. This no-b-wave (nob) ERG is seen in other mouse models with depolarizing bipolar cell (DBC) dysfunction and in patients with the complete form of congenital stationary night blindness (cCSNB). We determined the basis for the nob ERG phenotype and screened C3H mice for the mutation to evaluate whether this finding is important for the vision research community. METHODS ERGs were used to examine retinal function. The retinal structure of the transgenic mice was investigated using histology and immunohistochemistry. Inverse PCR was performed to identify the insertion site of the Epo transgene in the mouse genome. Affected mice were backcrossed to follow the inheritance pattern of the nob ERG phenotype. Quantitative real-time PCR (qRT PCR), Sanger sequencing, and immunohistochemistry were used to identify the mutation causing the defect. Additional C3H sublines were screened for the detected mutation. RESULTS Retinal histology and blood vessel structure were not disturbed, and no loss of DBCs was observed in the tg21 nob mice. The mutation causing the nob ERG phenotype is inherited independently of the tg21 transgene. The qRT PCR experiments revealed that the nob ERG phenotype reflected a mutation in Gpr179, a gene involved in DBC signal transduction. PCR analysis confirmed the presence of the Gpr179(nob5) insertional mutation in intron 1 of Gpr179. Screening for mutations in other C3H-derived lines revealed that C3H.Pde6b(+) mice carry the Gpr179 (nob5) allele whereas C3H/HeH mice do not. CONCLUSIONS We identified the presence of the Gpr179(nob5) mutation causing DBC dysfunction in a C3H-derived transgenic mouse line. The nob phenotype is not related to the presence of the transgene. The Gpr179(nob5) allele can be added to the list of background alleles that impact retinal function in commonly used mouse lines. By providing primers to distinguish between Gpr179 mutant and wild-type alleles, this study allows investigators to monitor for the presence of the Gpr179(nob5) mutation in other mouse lines derived from C3H.
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Affiliation(s)
- Jasmin Balmer
- Department of Ophthalmology, Inselspital, University of Bern, Switzerland,Graduate School for Cellular and Biomedical Sciences, University of Bern, Switzerland
| | - Rui Ji
- Department of Biochemistry and Molecular Biology, University of Louisville, KY
| | - Thomas A. Ray
- Department of Biochemistry and Molecular Biology, University of Louisville, KY
| | - Fabia Selber
- Department of Ophthalmology, Inselspital, University of Bern, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, University of Zürich, Switzerland
| | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland OH,Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland OH,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland OH
| | - Ronald G. Gregg
- Department of Biochemistry and Molecular Biology, University of Louisville, KY
| | - Volker Enzmann
- Department of Ophthalmology, Inselspital, University of Bern, Switzerland
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Orlandi C, Cao Y, Martemyanov KA. Orphan receptor GPR179 forms macromolecular complexes with components of metabotropic signaling cascade in retina ON-bipolar neurons. Invest Ophthalmol Vis Sci 2013; 54:7153-61. [PMID: 24114537 DOI: 10.1167/iovs.13-12907] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE In the mammalian retina, synaptic transmission between light-excited rod photoreceptors and downstream ON-bipolar neurons is indispensable for dim vision, and disruption of this process leads to congenital stationary night blindness in human patients. The ON-bipolar neurons use the metabotropic signaling cascade, initiated by the mGluR6 receptor, to generate depolarizing responses to light-induced changes in neurotransmitter glutamate release from the photoreceptor axonal terminals. Evidence for the identity of the components involved in transducing these signals is growing rapidly. Recently, the orphan receptor, GPR179, a member of the G protein-coupled receptor (GPCR) superfamily, has been shown to be indispensable for the synaptic responses of ON-bipolar cells. In our study, we investigated the interaction of GPR179 with principle components of the signal transduction cascade. METHODS We used immunoprecipitation and proximity ligation assays in transfected cells and native retinas to characterize the protein-protein interactions involving GPR179. The influence of cascade components on GPR179 localization was examined through immunohistochemical staining of the retinas from genetic mouse models. RESULTS We demonstrated that, in mouse retinas, GPR179 forms physical complexes with the main components of the metabotropic cascade, recruiting mGluR6, TRPM1, and the RGS proteins. Elimination of mGluR6 or RGS proteins, but not TRPM1, detrimentally affects postsynaptic targeting or GPR179 expression. CONCLUSIONS These observations suggest that the mGluR6 signaling cascade is scaffolded as a macromolecular complex in which the interactions between the components ensure the optimal spatiotemporal characteristics of signal transduction.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
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Klooster J, van Genderen MM, Yu M, Florijn RJ, Riemslag FCC, Bergen AAB, Gregg RG, Peachey NS, Kamermans M. Ultrastructural localization of GPR179 and the impact of mutant forms on retinal function in CSNB1 patients and a mouse model. Invest Ophthalmol Vis Sci 2013; 54:6973-81. [PMID: 24084093 DOI: 10.1167/iovs.13-12293] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Complete congenital stationary night blindness (CSNB1) is characterized by loss of night vision due to a defect in the retinal ON-bipolar cells (BCs). Mutations in GPR179, encoding the G-protein-coupled receptor 179, have been found in CSNB1 patients. In the mouse, GPR179 is localized to the tips of ON-BC dendrites. In this study we determined the ultrastructural localization of GPR179 in human retina and determined the functional consequences of mutations in GPR179 in patients and mice. METHODS The localization of GRP179 was analyzed in postmortem human retinas with immunohistochemistry. The functional consequences of the loss of GPR179 were analyzed with standard and 15-Hz flicker ERG protocols. RESULTS In the human retina, GPR179 is localized on the tips of ON-BC dendrites, which invaginate photoreceptors and terminate juxtaposed to the synaptic ribbon. The 15-Hz flicker ERG abnormalities found in patients with mutations in GPR179 more closely resemble those from patients with mutations in either TRPM1 or NYX than in GRM6. 15-Hz flicker ERG abnormalities of Gpr179(nob5) and Grm6(nob3) mice were comparable. CONCLUSIONS GRP179 is expressed on dendrites of ON-BCs, indicating that GRP179 is involved in the ON-BCs' signaling cascade. The similarities of 15-Hz flicker ERGs noted in GPR179 patients and NYX or TRPM1 patients suggest that the loss of GPR179 leads to the loss or closure of TRPM1 channels. The difference between the 15-Hz flicker ERGs of mice and humans indicates the presence of important species differences in the retinal activity that this signal represents.
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Affiliation(s)
- Jan Klooster
- Retinal Signal Processing, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
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Chang B, Hurd R, Wang J, Nishina P. Survey of common eye diseases in laboratory mouse strains. Invest Ophthalmol Vis Sci 2013; 54:4974-81. [PMID: 23800770 DOI: 10.1167/iovs.13-12289] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE As in human populations, in which founder mutations have been identified in groups of families, a number of founder mutations have been observed across strains in mice. In this report, we provide a phenotype and genotype survey of three common eye diseases in the collection of JAX mice strains at The Jackson Laboratory (JAX). These eye diseases are retinal degeneration 1 (Pde6b(rd1)), retinal degeneration 8 (Crb1(rd8)), and cone photoreceptor function loss 3 (Gnat2(cpfl3)). METHODS Ocular lesions for rd1 and rd8 were evaluated by fundus examination and fundus photography, and the abnormal retinal function observed in mice homozygous for cpfl3 was assessed by ERG. Genotyping protocols for rd1, rd8, and cpfl3 mutations were performed by PCR with appropriate primers. RESULTS We have actively screened retired breeders for surface dysmorphologies, and for intraocular defects by indirect ophthalmoscopy, slit-lamp biomicroscopy, and ERG to discover new spontaneous mutations in strains from the Genetic Resource Science (GRS) production colony. Through this process, we have found that of the strains screened, 99 strains carried the rd1 mutation, 85 strains carried the rd8 mutation, and 20 strains carried the cpfl3 mutation. CONCLUSIONS Of the 1000 of strains screened during this study, 204 carried one of three founder mutations in Pde6b, Crb1, or Gnat2. Since these three retinal mutations occur commonly in various mouse strains, genotyping for these mutations, and/or avoiding mouse strains or stocks carrying these mutant alleles when studying new retinal disorders is recommended. The robust PCR genotyping protocols to test for these common alleles are described herein.
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Affiliation(s)
- Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine 04609, USA.
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Raghuram A, Hansen RM, Moskowitz A, Fulton AB. Photoreceptor and postreceptor responses in congenital stationary night blindness. Invest Ophthalmol Vis Sci 2013; 54:4648-58. [PMID: 23761088 DOI: 10.1167/iovs.13-12111] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate photoreceptor and postreceptor retinal function in patients with congenital stationary night blindness (CSNB). METHODS Forty-one patients with CSNB (ages 0.19-32 years) were studied. ERG responses to a series of full-field stimuli were obtained under scotopic and photopic conditions and were used to categorize the CSNB patients as complete (cCSNB) or incomplete (iCSNB). Rod and cone photoreceptor (R(ROD), S(ROD), R(CONE), S(CONE)) and rod-driven postreceptor (V(MAX), log σ) response parameters were calculated from the a- and b-waves. Cone-driven responses to 30 Hz flicker and ON and OFF responses to a long duration (150 ms) flash were also obtained. Dark-adapted thresholds were measured. Analysis of variance was used to compare data from patients with cCSNB, patients with iCSNB, and controls. RESULTS We found significant reduction in saturated photoreceptor amplitude (R(ROD), R(CONE)) but normal photoreceptor sensitivity (S(ROD), S(CONE)) in both CSNB groups. Rod-driven postreceptor response amplitude (V(MAX)) and sensitivity (log σ) were significantly reduced in CSNB. Log σ was significantly worse in cCSNB than in iCSNB; this was the only scotopic parameter that differed between the two CSNB groups. Photopic b-wave amplitude increased monotonically with stimulus strength in CSNB patients rather than showing a normal photopic hill. The amplitude of the 30-Hz flicker response was reduced compared with controls, more so in iCSNB than in cCSNB. The mean dark-adapted threshold was significantly elevated in CSNB, more so in cCSNB than in iCSNB. CONCLUSIONS These results are evidence of normal photoreceptor function (despite the low saturated photoresponse amplitude) and anomalous postreceptor retinal circuitry.
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Affiliation(s)
- Aparna Raghuram
- Department of Ophthalmology, Boston Children's Hospital, Boston, Massachusetts 02215, USA.
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Abstract
The mammalian retina consists of neurons of >60 distinct types, each playing a specific role in processing visual images. They are arranged in three main stages. The first decomposes the outputs of the rod and cone photoreceptors into ∼12 parallel information streams. The second connects these streams to specific types of retinal ganglion cells. The third combines bipolar and amacrine cell activity to create the diverse encodings of the visual world--roughly 20 of them--that the retina transmits to the brain. New transformations of the visual input continue to be found: at least half of the encodings sent to the brain (ganglion cell response selectivities) remain to be discovered. This diversity of the retina's outputs has yet to be incorporated into our understanding of higher visual function.
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Affiliation(s)
- Richard H Masland
- Department of Opthamology, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA.
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Dhingra A, Vardi N. "mGlu Receptors in the Retina" - WIREs Membrane Transport and Signaling. WILEY INTERDISCIPLINARY REVIEWS. MEMBRANE TRANSPORT AND SIGNALING 2012; 1:641-653. [PMID: 24003403 PMCID: PMC3755759 DOI: 10.1002/wmts.43] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Glutamate, a key neurotransmitter in the vertebrate retina, acts via ionotropic and metabotropic receptors. Retina expresses mRNA for all metabotropic glutamate receptors and proteins for all but mGluR3. Every retinal cell class expresses one or more of these receptors. In general, these receptors are present presynaptically and serve to modulate synaptic transmission. While mGluRs on the photoreceptor terminal act as autoreceptors to titer glutamate levels, those on horizontal cell processes seem to shape the light response. Similarly, autoreceptors on bipolar axon terminals modulate glutamate release and the receptors on amacrine and ganglion cells modulate feedforward signals by modulating K+ or Ca2+ current to fine tune light responses. Since most of the mGluR sub-types are present in amacrine and ganglion cells that belong to many cell types, the pathways downstream of mGluRs are highly diverse with primarily modulatory effects. An exception to most mGluRs which have modulatory function is mGluR6 because it plays a key role in the feedforward transmission from photoreceptors to ON bipolar cells and is also required for the correct localization of the synaptic proteins in the dendritic tips. In humans, mutations in the gene encoding mGluR6 cause autosomal recessive night blindness. In addition, mGluRs appear to play a trophic role in development and after retinal damage, suggesting potential future therapeutic implications.
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Peachey NS, Pearring JN, Bojang P, Hirschtritt ME, Sturgill-Short G, Ray TA, Furukawa T, Koike C, Goldberg AFX, Shen Y, McCall MA, Nawy S, Nishina PM, Gregg RG. Depolarizing bipolar cell dysfunction due to a Trpm1 point mutation. J Neurophysiol 2012; 108:2442-51. [PMID: 22896717 DOI: 10.1152/jn.00137.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations in TRPM1 are found in humans with an autosomal recessive form of complete congenital stationary night blindness (cCSNB). The Trpm1(-/-) mouse has been an important animal model for this condition. Here we report a new mouse mutant, tvrm27, identified in a chemical mutagenesis screen. Genetic mapping of the no b-wave electroretinogram (ERG) phenotype of tvrm27 localized the mutation to a chromosomal region that included Trpm1. Complementation testing with Trpm1(-/-) mice confirmed a mutation in Trpm1. Sequencing identified a nucleotide change in exon 23, converting a highly conserved alanine within the pore domain to threonine (p.A1068T). Consistent with prior studies of Trpm1(-/-) mice, no anatomical changes were noted in the Trpm1(tvrm27/tvrm27) retina. The Trpm1(tvrm27/tvrm27) phenotype is distinguished from that of Trpm1(-/-) by the retention of TRPM1 expression on the dendritic tips of depolarizing bipolar cells (DBCs). While ERG b-wave amplitudes of Trpm1(+/-) heterozygotes are comparable to wild type, those of Trpm1(+/tvrm27) mice are reduced by 32%. A similar reduction in the response of Trpm1(+/tvrm27) DBCs to LY341495 or capsaicin is evident in whole cell recordings. These data indicate that the p.A1068T mutant TRPM1 acts as a dominant negative with respect to TRPM1 channel function. Furthermore, these data indicate that the number of functional TRPM1 channels at the DBC dendritic tips is a key factor in defining DBC response amplitude. The Trpm1(tvrm27/tvrm27) mutant will be useful for elucidating the role of TRPM1 in DBC signal transduction, for determining how Trpm1 mutations impact central visual processing, and for evaluating experimental therapies for cCSNB.
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Affiliation(s)
- Neal S Peachey
- Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA.
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Peachey NS, Sturgill-Short GM. Response properties of slow PIII in the Large (vls) mutant. Doc Ophthalmol 2012; 125:203-9. [PMID: 22865473 DOI: 10.1007/s10633-012-9347-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 07/23/2012] [Indexed: 11/24/2022]
Abstract
PURPOSE Mouse mutants for proteins expressed in the dystrophin-glycoprotein complex at the photoreceptor terminal have electroretinogram (ERG) b-waves with a delayed onset and time course. The b-wave is defined by the sum of PII generated by depolarizing bipolar cells and slow PIII generated by Müller glial cells. In this study, we evaluated the hypothesis that the abnormalities observed in one of these mutants, Large (vls) , are caused by abnormal response properties of slow PIII. METHODS To isolate slow PIII, we crossed the Large (vls) mutant to a mouse line (Gpr179 (nob5) ) that lacks the ERG b-wave but maintains normal photoreceptor function and in which retinal degeneration does not occur. ERGs were recorded to strobe flash stimuli after overnight dark adaptation. RESULTS In comparison with control responses, the a-wave and slow PIII had comparable waveforms but were reduced in amplitude in Large (vls) mice. The magnitude of this reduction was comparable for these components, and across stimulus luminance. There was no stimulus condition where the amplitude of slow PIII was larger than control. CONCLUSIONS The data obtained are inconsistent with the idea that the b-wave abnormalities noted in Large (vls) mutant mice are caused by abnormal response properties of slow PIII.
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Affiliation(s)
- Neal S Peachey
- Louis Stokes Cleveland VA Medical Center, 10701 East Boulevard, Cleveland, OH 44106, USA. ,Cole Eye Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. .,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.
| | - Gwen M Sturgill-Short
- Louis Stokes Cleveland VA Medical Center, 10701 East Boulevard, Cleveland, OH, 44106, USA
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GPR179 is required for depolarizing bipolar cell function and is mutated in autosomal-recessive complete congenital stationary night blindness. Am J Hum Genet 2012; 90:331-9. [PMID: 22325362 DOI: 10.1016/j.ajhg.2011.12.006] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 11/21/2011] [Accepted: 12/08/2011] [Indexed: 01/06/2023] Open
Abstract
Complete congenital stationary night blindness (cCSNB) is a clinically and genetically heterogeneous group of retinal disorders characterized by nonprogressive impairment of night vision, absence of the electroretinogram (ERG) b-wave, and variable degrees of involvement of other visual functions. We report here that mutations in GPR179, encoding an orphan G protein receptor, underlie a form of autosomal-recessive cCSNB. The Gpr179(nob5/nob5) mouse model was initially discovered by the absence of the ERG b-wave, a component that reflects depolarizing bipolar cell (DBC) function. We performed genetic mapping, followed by next-generation sequencing of the critical region and detected a large transposon-like DNA insertion in Gpr179. The involvement of GPR179 in DBC function was confirmed in zebrafish and humans. Functional knockdown of gpr179 in zebrafish led to a marked reduction in the amplitude of the ERG b-wave. Candidate gene analysis of GPR179 in DNA extracted from patients with cCSNB identified GPR179-inactivating mutations in two patients. We developed an antibody against mouse GPR179, which robustly labeled DBC dendritic terminals in wild-type mice. This labeling colocalized with the expression of GRM6 and was absent in Gpr179(nob5/nob5) mutant mice. Our results demonstrate that GPR179 plays a critical role in DBC signal transduction and expands our understanding of the mechanisms that mediate normal rod vision.
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Abstract
Mouse models, with their well-developed genetics and similarity to human physiology and anatomy, serve as powerful tools with which to investigate the etiology of human retinal degeneration. Mutant mice also provide reproducible, experimental systems for elucidating pathways of normal development and function. Here, I describe the tools used in the discoveries of many retinal degeneration models, including indirect ophthalmoscopy (to look at the fundus appearance), fundus photography and fluorescein angiography (to document the fundus appearance), electroretinography (to check retinal function), as well as the heritability test (for genetic characterization).
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Affiliation(s)
- Bo Chang
- The Jackson Laboratory, Bar Harbor, ME, USA,
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Luo X, Frishman LJ. Retinal pathway origins of the pattern electroretinogram (PERG). Invest Ophthalmol Vis Sci 2011; 52:8571-84. [PMID: 21948546 DOI: 10.1167/iovs.11-8376] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE To determine retinal pathway origins of pattern electroretinogram (PERG) in macaque monkeys using pharmacologic dissections, uniform-field flashes, and PERG simulations. METHODS Transient (2 Hz, 4 reversals/s) and steady state (8.3 Hz, 16.6 reversals/s) PERGs and uniform-field ERGs were recorded before and after intravitreal injections of L-AP4 (not APB) (2-amino-4-phosphonobutyric acid, 1.6-2.0 mM), to prevent ON pathway responses; PDA (cis-2,3-piperidinedicarboxylic acid, 3.3-3.8 mM), to block activity of hyperpolarizing second- and all third-order retinal neurons; and TTX (tetrodotoxin, 6 μM), to block Na+-dependent spiking. PERGs were also recorded from macaques with advanced unilateral experimental glaucoma, and were simulated by averaging ON and OFF responses to uniform-field flashes. RESULTS For 2-Hz stimulation, L-AP4 reduced both negative- and positive-going (N95 and P50) amplitudes in transient PERGs, and their counterparts, N2 and P1 in simulations, to half-amplitude. PDA eliminated N95 and N2, but increased P50 and P1 amplitudes, in that it enhanced b-waves. As previously reported, severe experimental glaucoma or TTX eliminated photopic negative responses, N95, and N2; glaucoma eliminated P50 and reduced P1 amplitude; TTX reduced P50 and hardly altered P1. For 8.3-Hz stimulation, L-AP4 eliminated the steady state PERG and reduced simulated PERG amplitude, whereas PDA enhanced both responses. TTX reduced PERG amplitude to less than half; simulations were less reduced. Blockade of all postreceptoral activity eliminated transient and steady state PERGs, but left small residual P1 in simulations. CONCLUSIONS Transient PERG receives nearly equal amplitude contributions from ON and OFF pathways. N95 reflects spiking activity of ganglion cells; P50 reflects nonspiking activity as well. Steady state PERG, in contrast, reflects mainly spike-related ON pathway activity.
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Affiliation(s)
- Xunda Luo
- University of Houston College of Optometry, Houston, Texas 77204-2020, USA
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TRPM1 forms complexes with nyctalopin in vivo and accumulates in postsynaptic compartment of ON-bipolar neurons in mGluR6-dependent manner. J Neurosci 2011; 31:11521-6. [PMID: 21832182 DOI: 10.1523/jneurosci.1682-11.2011] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptic transmission between light-sensory photoreceptor cells and downstream ON-bipolar neurons plays an important role for vertebrate vision. This process is mediated by the G-protein-coupled receptor pathway involving glutamate receptor mGluR6 and effector channel TRPM1. The signal transmission occurs on a rapid timescale; however, the molecular organization that ensures timely signaling in this cascade is unknown. Genetic studies in human patients and animal models reveal that ON-bipolar cell signaling depends on the synaptic protein nyctalopin. We have conducted a proteomic search for proteins associated with nyctalopin in the mouse retina and identified TRPM1 as the binding partner. We further demonstrate that nyctalopin additionally interacts with mGluR6 receptor. Disruption of mGluR6 prevented targeting of TRPM1 to the postsynaptic compartment of ON-bipolar neurons. These results reveal a unique macromolecular organization of the mGluR6 cascade, where principal signaling components are scaffolded by nyctalopin, creating an organization essential for the correct localization of the signaling ensemble and ultimately intact transmission of the signal at the first visual synapse.
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DeAngelis MM, Silveira AC, Carr EA, Kim IK. Genetics of age-related macular degeneration: current concepts, future directions. Semin Ophthalmol 2011; 26:77-93. [PMID: 21609220 PMCID: PMC4242505 DOI: 10.3109/08820538.2011.577129] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Age-related macular degeneration (AMD) is a progressive degenerative disease which leads to blindness, affecting the quality of life of millions of Americans. More than 1.75 million individuals in the United States are affected by the advanced form of AMD. The etiological pathway of AMD is not yet fully understood, but there is a clear genetic influence on disease risk. To date, the 1q32 (CFH) and 10q26 (PLEKHA1/ARMS2/HTRA1) loci are the most strongly associated with disease; however, the variation in these genomic regions alone is unable to predict disease development with high accuracy. Therefore, current genetic studies are aimed at identifying new genes associated with AMD and their modifiers, with the goal of discovering diagnostic or prognostic biomarkers. Moreover, these studies provide the foundation for further investigation into the pathophysiology of AMD by utilizing a systems-biology-based approach to elucidate underlying mechanistic pathways.
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Affiliation(s)
- Margaret M. DeAngelis
- Ocular Molecular Genetics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Alexandra C. Silveira
- Ocular Molecular Genetics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Elizabeth A. Carr
- John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA
| | - Ivana K. Kim
- Retina Service, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
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Stasheff SF, Shankar M, Andrews MP. Developmental time course distinguishes changes in spontaneous and light-evoked retinal ganglion cell activity in rd1 and rd10 mice. J Neurophysiol 2011; 105:3002-9. [PMID: 21389300 DOI: 10.1152/jn.00704.2010] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In a subset of hereditary retinal diseases, early photoreceptor degeneration causes rapidly progressive blindness in children. To better understand how retinal development may interact with degenerative processes, we compared spontaneous and light-evoked activity among retinal ganglion cells in rd1 and rd10 mice, strains with closely related retinal disease. In each, a mutation in the Pde6b gene causes photoreceptor dysfunction and death, but in rd10 mice degeneration starts after a peak in developmental plasticity of retinal circuitry and thereafter progresses more slowly. In vitro multielectrode action potential recordings revealed that spontaneous waves of correlated ganglion cell activity comparable to those in wild-type mice were present in rd1 and rd10 retinas before eye opening [postnatal day (P) 7 to P8]. In both strains, spontaneous firing rates increased by P14-P15 and were many times higher by 4-6 wk of age. Among rd1 ganglion cells, all responses to light had disappeared by ~P28, yet in rd10 retinas vigorous ON and OFF responses were maintained well beyond this age and were not completely lost until after P60. This difference in developmental time course separates mechanisms underlying the hyperactivity from those that alter light-driven responses in rd10 retinas. Moreover, several broad physiological groups of cells remained identifiable according to response polarity and time course as late as P60. This raises hope that visual function might be preserved or restored despite ganglion cell hyperactivity seen in inherited retinal degenerations, particularly if treatment or manipulation of early developmental plasticity were to be timed appropriately.
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Affiliation(s)
- Steven F Stasheff
- Department of Pediatrics (Neurology), The University of Iowa and The Carver College of Medicine, Iowa City, IA 52242, USA.
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Fletcher EL, Jobling AI, Vessey KA, Luu C, Guymer RH, Baird PN. Animal models of retinal disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 100:211-86. [PMID: 21377628 DOI: 10.1016/b978-0-12-384878-9.00006-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Diseases of the retina are the leading causes of blindness in the industrialized world. The recognition that animals develop retinal diseases with similar traits to humans has led to not only a dramatic improvement in our understanding of the pathogenesis of retinal disease but also provided a means for testing possible treatment regimes and successful gene therapy trials. With the advent of genetic and molecular biological tools, the association between specific gene mutations and retinal signs has been made. Animals carrying natural mutations usually in one gene now provide well-established models for a host of inherited retinal diseases, including retinitis pigmentosa, Leber congenital amaurosis, inherited macular degeneration, and optic nerve diseases. In addition, the development of transgenic technologies has provided a means by which to study the effects of these and novel induced mutations on retinal structure and function. Despite these advances, there is a paucity of suitable animal models for complex diseases, including age-related macular degeneration (AMD) and diabetic retinopathy, largely because these diseases are not caused by single gene defects, but involve complex genetics and/or exacerbation through environmental factors, epigenetic, or other modes of genetic influence. In this review, we outline in detail the available animal models for inherited retinal diseases and how this information has furthered our understanding of retinal diseases. We also examine how transgenic technologies have helped to develop our understanding of the role of isolated genes or pathways in complex diseases like AMD, diabetes, and glaucoma.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Cell Biology, The University of Melbourne, Parkville, Victoria, Australia
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Schaumberg DA, Chasman D, Morrison MA, Adams SM, Guo Q, Hunter DJ, Hankinson SE, DeAngelis MM. Prospective study of common variants in the retinoic acid receptor-related orphan receptor α gene and risk of neovascular age-related macular degeneration. ACTA ACUST UNITED AC 2010; 128:1462-71. [PMID: 21060049 DOI: 10.1001/archophthalmol.2010.261] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES The retinoic acid receptor (RAR)-related orphan receptor α gene (RORA) is implicated as a candidate for age-related macular degeneration (AMD) through a previous microarray expression study, linkage data, biological plausibility, and 2 clinic-based cross-sectional studies. We aimed to determine if common variants in RORA predict future risk of neovascular AMD. METHODS We measured genotypes for 18 variants in intron 1 of the RORA gene among 164 cases who developed neovascular AMD and 485 age- and sex-matched controls in a prospective, nested, case-control study within the Nurses' Health Study and the Health Professionals Follow-up Study. We determined the incidence rate ratios and 95% confidence intervals (CI) for neovascular AMD for each variant and examined interactions with other AMD-associated variants and modifiable risk factors. RESULTS We identified one single-nucleotide polymorphism (rs12900948) that was significantly associated with increased incidence of neovascular AMD. Participants with 1 and 2 copies of the G allele were 1.73 (CI, 1.32-2.27) and 2.99 (CI, 1.74-5.14) times more likely to develop neovascular AMD. Individuals homozygous for both the G allele of rs12900948 and ARMS2 A69S had a 40.8-fold increased risk of neovascular AMD (CI, 10.1-164; P = .017). Cigarette smokers who carried 2 copies of the G allele had a 9.89-fold risk of neovascular AMD but the interaction was not significant (P = .08). We identified a significant AMD-associated haplotype block containing the single-nucleotide polymorphisms rs730754, rs8034864, and rs12900948, with P values for ACA = 1.16 × 10(-9), ACG = 5.85 × 10(-12), and GAA = .0001 when compared with all other haplotypes. CONCLUSIONS Common variants and haplotypes within the RORA gene appear to act synergistically with the ARMS2 A69S polymorphism to increase risk of neovascular AMD. These data add further evidence of a high level of complexity linking genetic and modifiable risk factors to AMD development and should help efforts at risk prediction.
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Affiliation(s)
- Debra A Schaumberg
- Division of Preventive Medicine, Department of Medicine, Brigham and Women’s Hospital, Boston, MA 02215, USA.
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