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Tarchick MJ, Beight C, Bonezzi PB, Peachey NS, Renna JM. Photoreceptor deficits appear at eye opening in Rs1 mutant mouse models of X-linked retinoschisis. Exp Eye Res 2024; 242:109872. [PMID: 38514024 DOI: 10.1016/j.exer.2024.109872] [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: 11/21/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 03/23/2024]
Abstract
X-linked retinoschisis (XLRS) is an early onset degenerative retinal disease characterized by cystic lesions in the middle layers of the retina. These structural changes are accompanied by a loss of visual acuity and decreased contrast sensitivity. XLRS is caused by mutations in the gene Rs1 which encodes the secreted protein Retinoschisin 1. Young Rs1-mutant mouse models develop key hallmarks of XLRS including intraretinal schisis and abnormal electroretinograms. The electroretinogram (ERG) comprises activity of multiple cellular generators, and it is not known how and when each of these is impacted in Rs1 mutant mice. Here we use an ex vivo ERG system and pharmacological blockade to determine how ERG components generated by photoreceptors, ON-bipolar, and Müller glial cells are impacted in Rs1 mutants and to determine the time course of these changes. We report that ERG abnormalities begin near eye-opening and that all ERG components are involved.
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Affiliation(s)
| | - Craig Beight
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Paul B Bonezzi
- Department of Biology, University of Akron, Akron, OH, USA
| | - Neal S Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA; Research Service, VA Northeast Ohio Healthcare System, Cleveland, OH, 44106, USA; Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Jordan M Renna
- Department of Biology, University of Akron, Akron, OH, USA.
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2
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Asteriti S, Marino V, Avesani A, Biasi A, Dal Cortivo G, Cangiano L, Dell'Orco D. Recombinant protein delivery enables modulation of the phototransduction cascade in mouse retina. Cell Mol Life Sci 2023; 80:371. [PMID: 38001384 PMCID: PMC10673981 DOI: 10.1007/s00018-023-05022-0] [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: 07/24/2023] [Revised: 10/10/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023]
Abstract
Inherited retinal dystrophies are often associated with mutations in the genes involved in the phototransduction cascade in photoreceptors, a paradigmatic signaling pathway mediated by G protein-coupled receptors. Photoreceptor viability is strictly dependent on the levels of the second messengers cGMP and Ca2+. Here we explored the possibility of modulating the phototransduction cascade in mouse rods using direct or liposome-mediated administration of a recombinant protein crucial for regulating the interplay of the second messengers in photoreceptor outer segments. The effects of administration of the free and liposome-encapsulated human guanylate cyclase-activating protein 1 (GCAP1) were compared in biological systems of increasing complexity (in cyto, ex vivo, and in vivo). The analysis of protein biodistribution and the direct measurement of functional alteration in rod photoresponses show that the exogenous GCAP1 protein is fully incorporated into the mouse retina and photoreceptor outer segments. Furthermore, only in the presence of a point mutation associated with cone-rod dystrophy in humans p.(E111V), protein delivery induces a disease-like electrophysiological phenotype, consistent with constitutive activation of the retinal guanylate cyclase. Our study demonstrates that both direct and liposome-mediated protein delivery are powerful complementary tools for targeting signaling cascades in neuronal cells, which could be particularly important for the treatment of autosomal dominant genetic diseases.
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Affiliation(s)
- Sabrina Asteriti
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy
- Department of Translational Research, University of Pisa, 56123, Pisa, Italy
| | - Valerio Marino
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy
| | - Anna Avesani
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy
| | - Amedeo Biasi
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy
| | - Giuditta Dal Cortivo
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy
| | - Lorenzo Cangiano
- Department of Translational Research, University of Pisa, 56123, Pisa, Italy.
| | - Daniele Dell'Orco
- Department of Neurosciences, Biomedicine and Movement Sciences, Section of Biological Chemistry, University of Verona, 37134, Verona, Italy.
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Mano F, Sugioka K, Kuniyoshi K, Kondo H, Kusaka S. Identification of Interphotoreceptor retinoid-binding protein in the Schisis cavity fluid of a patient with congenital X-linked Retinoschisis. BMC Ophthalmol 2022; 22:14. [PMID: 34991515 PMCID: PMC8740355 DOI: 10.1186/s12886-021-02234-5] [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: 03/25/2021] [Accepted: 12/23/2021] [Indexed: 11/10/2022] Open
Abstract
Background This case report describes the surgical outcome in a patient with congenital X-linked retinoschisis (CXLRS) and the results of proteomic analysis of surgically extracted samples from both vitreous and intraschisis cavities by mass spectrometry. Case presentation A 3-month-old boy presented with extensive retinoschisis involving macula and retinal periphery in both eyes. Genetic analysis confirmed retinoschisin 1 mutation (c.554C > T), and an electroretinogram showed significant reduction of b-wave and decreased cone and rod responses, which led to a diagnosis of CXLRS. By performing pars plana vitrectomy, including inner wall retinectomy, clear visual axes with stable retinal conditions and functional vision in both eyes were obtained during the 4 years of follow-up. Proteomic analysis of surgically retrieved fluid from the intraschisis cavity revealed a higher expression of interphotoreceptor retinoid-binding protein (IRBP) than that from the vitreous humor. However, both samples showed equal levels of albumin, transferrin, and pigment epithelium-derived factor. Conclusions Cellular adhesive imperfection in CXLRS may cause IRBP diffusion from the interphotoreceptor matrix, resulting in the strong expression of IRBP in the intraschisis cavity. An impaired retinoid cycle caused by an absence of IRBP in the retina may potentially underlie the pathology of CXLRS. Supplementary Information The online version contains supplementary material available at 10.1186/s12886-021-02234-5.
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Affiliation(s)
- Fukutaro Mano
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osakasayama, Japan
| | - Koji Sugioka
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osakasayama, Japan. .,Department of Ophthalmology, Kindai University Nara Hospital, 1248-1 Otodacho, Ikoma City, Nara, 630-0293, Japan.
| | - Kazuki Kuniyoshi
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osakasayama, Japan
| | - Hiroyuki Kondo
- Department of Ophthalmology, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Shunji Kusaka
- Department of Ophthalmology, Kindai University Faculty of Medicine, Osakasayama, Japan
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Eastlake K, Heywood WE, Banerjee P, Bliss E, Mills K, Khaw PT, Charteris D, Limb GA. Comparative proteomic analysis of normal and gliotic PVR retina and contribution of Müller glia to this profile. Exp Eye Res 2018; 177:197-207. [PMID: 30176221 PMCID: PMC6280037 DOI: 10.1016/j.exer.2018.08.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 08/07/2018] [Accepted: 08/20/2018] [Indexed: 12/21/2022]
Abstract
Müller glia are responsible for the neural retina regeneration observed in fish and amphibians throughout life. Despite the presence of these cells in the adult human retina, there is no evidence of regeneration occurring in humans following disease or injury. It may be possible that factors present in the degenerated retina could prevent human Müller glia from proliferating and neurally differentiating within the diseased retina. On this basis, investigations into the proteomic profile of these cells and the abundance of key proteins associated to Müller glia in the gliotic PVR retina, may assist in the identification of factors with the potential to control Müller proliferation and neural differentiation in vivo. Label free mass spectrometry identified 1527 proteins in Müller glial cell preparations, 1631 proteins in normal retina and 1074 in gliotic PVR retina. Compared to normal retina, 28 proteins were upregulated and 196 proteins downregulated by 2-fold or more in the gliotic PVR retina. As determined by comparative proteomic analyses, of the proteins highly upregulated in the gliotic PVR retina, the most highly abundant proteins in Müller cell lysates included vimentin, GFAP, polyubiquitin and HSP90a. The observations that proteins highly upregulated in the gliotic retina constitute major proteins expressed by Müller glia provide the basis for further studies into mechanisms that regulate their production. In addition investigations aimed at controlling the expression of these proteins may aid in the identification of factors that could potentially promote endogenous regeneration of the adult human retina after disease or injury. Proteomic analyses showed evidence for Müller glia contribution to retinal gliosis. Polyubiquitin-C and HSP90a produced by Müller glia, are upregulated in gliotic retina. Müller glia are a source of prelamin, elongation factor and serpin found in retina.
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Affiliation(s)
- Karen Eastlake
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - Wendy E Heywood
- Centre for Translational Omics, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Phillip Banerjee
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - Emily Bliss
- Centre for Translational Omics, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Kevin Mills
- Centre for Translational Omics, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Peng T Khaw
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - David Charteris
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - G Astrid Limb
- NIHR Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.
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Shi L, Chang JYA, Yu F, Ko ML, Ko GYP. The Contribution of L-Type Ca v1.3 Channels to Retinal Light Responses. Front Mol Neurosci 2017; 10:394. [PMID: 29259539 PMCID: PMC5723326 DOI: 10.3389/fnmol.2017.00394] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/10/2017] [Indexed: 01/28/2023] Open
Abstract
L-type voltage-gated calcium channels (LTCCs) regulate tonic neurotransmitter release from sensory neurons including retinal photoreceptors. There are three types of LTCCs (Cav1.2, Cav1.3, and Cav1.4) expressed in the retina. While Cav1.2 is expressed in all retinal cells including the Müller glia and neurons, Cav1.3 and Cav1.4 are expressed in the retinal neurons with Cav1.4 exclusively expressed in the photoreceptor synaptic terminals. Mutations in the gene encoding Cav1.4 cause incomplete X-linked congenital stationary night blindness in humans. Even though Cav1.3 is present in the photoreceptor inner segments and the synaptic terminals in various vertebrate species, its role in vision is unclear, since genetic alterations in Cav1.3 are not associated with severe vision impairment in humans or in Cav1.3-null (Cav1.3-/-) mice. However, a failure to regulate Cav1.3 was found in a mouse model of Usher syndrome, the most common cause of combined deafness and blindness in humans, indicating that Cav1.3 may contribute to retinal function. In this report, we combined physiological and morphological data to demonstrate the role of Cav1.3 in retinal physiology and function that has been undervalued thus far. Through ex vivo and in vivo electroretinogram (ERG) recordings and immunohistochemical staining, we found that Cav1.3 plays a role in retinal light responses and synaptic plasticity. Pharmacological inhibition of Cav1.3 decreased ex vivo ERG a- and b-wave amplitudes. In Cav1.3-/- mice, their dark-adapted ERG a-, b-wave, and oscillatory potential amplitudes were significantly dampened, and implicit times were delayed compared to the wild type (WT). Furthermore, the density of ribbon synapses was reduced in the outer plexiform layer of Cav1.3-/- mice retinas. Hence, Cav1.3 plays a more prominent role in retinal physiology and function than previously reported.
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Affiliation(s)
- Liheng Shi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Janet Ya-An Chang
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Fei Yu
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Michael L Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States
| | - Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX, United States.,Texas A&M Institute of Neuroscience, Texas A&M University, College Station, TX, United States
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Assessment of Ocriplasmin Effects on the Vitreoretinal Compartment in Porcine and Human Model Systems. J Ophthalmol 2017; 2017:2060765. [PMID: 29214073 PMCID: PMC5682056 DOI: 10.1155/2017/2060765] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 09/17/2017] [Indexed: 11/17/2022] Open
Abstract
Ocriplasmin (Jetrea®) is a recombinant protease used to treat vitreomacular traction. To gain insight into vitreoretinal observations reported after ocriplasmin treatment, we have developed an in vivo porcine ocriplasmin-induced posterior vitreous detachment (PVD) model in which we investigated vitreoretinal tissues by optical coherence tomography, histology, and cytokine profiling. Eight weeks postinjection, ocriplasmin yielded PVD in 82% of eyes. Subretinal fluid (85%) and vitreous hyperreflective spots (45%) were resolved by week 3. Histological analysis of extracellular matrix (ECM) proteins such as laminin, fibronectin, and collagen IV indicated no retinal ocriplasmin-induced ECM distribution changes. Retinal morphology was unaffected in all eyes. Cytokine profiles of ocriplasmin-treated eyes were not different from vehicle. In cell-based electrical resistance assays, blood-retinal barrier permeability was altered by ocriplasmin concentrations of 6 μg/mL and higher, with all effects being nontoxic, cell-type specific, and reversible. Ocriplasmin was actively taken up by RPE and Müller cells, and our data suggest both lysosomal and transcellular clearance routes for ocriplasmin. In conclusion, transient hyperreflective spots and fluid in a porcine ocriplasmin-induced PVD model did not correlate with retinal ECM rearrangement nor inflammation. Reversible in vitro effects on blood-retinal barrier permeability provide grounds for a hypothesis on the mechanisms behind transient subretinal fluid observed in ocriplasmin-treated patients.
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7
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Shi L, Ko ML, Ko GYP. Retinoschisin Facilitates the Function of L-Type Voltage-Gated Calcium Channels. Front Cell Neurosci 2017; 11:232. [PMID: 28848397 PMCID: PMC5550728 DOI: 10.3389/fncel.2017.00232] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 07/25/2017] [Indexed: 11/18/2022] Open
Abstract
Modulation of ion channels by extracellular proteins plays critical roles in shaping synaptic plasticity. Retinoschisin (RS1) is an extracellular adhesive protein secreted from photoreceptors and bipolar cells, and it plays an important role during retinal development, as well as in maintaining the stability of retinal layers. RS1 is known to form homologous octamers and interact with molecules on the plasma membrane including phosphatidylserine, sodium-potassium exchanger complex, and L-type voltage-gated calcium channels (LTCCs). However, how this physical interaction between RS1 and ion channels might affect the channel gating properties is unclear. In retinal photoreceptors, two major LTCCs are Cav1.3 (α1D) and Cav1.4 (α1F) with distinct biophysical properties, functions and distributions. Cav1.3 is distributed from the inner segment (IS) to the synaptic terminal and is responsible for calcium influx to the photoreceptors and overall calcium homeostasis. Cav1.4 is only expressed at the synaptic terminal and is responsible for neurotransmitter release. Mutations of the gene encoding Cav1.4 cause X-linked incomplete congenital stationary night blindness type 2 (CSNB2), while null mutations of Cav1.3 cause a mild decrease of retinal light responses in mice. Even though RS1 is known to maintain retinal architecture, in this study, we present that RS1 interacts with both Cav1.3 and Cav1.4 and regulates their activations. RS1 was able to co-immunoprecipitate with Cav1.3 and Cav1.4 from porcine retinas, and it increased the LTCC currents and facilitated voltage-dependent activation in HEK cells co-transfected with RS1 and Cav1.3 or Cav1.4, thus providing evidence of a functional interaction between RS1 and LTCCs. The interaction between RS1 and Cav1.3 did not change the calcium-dependent inactivation of Cav1.3. In mice lacking RS1, the expression of Cav1.3 and Cav1.4 in the retina decreased, while in mice with Cav1.4 deletion, the retinal level of RS1 decreased. These results provide important evidence that RS1 is not only an adhesive protein promoting cell-cell adhesion, it is essential for anchoring other membrane proteins including ion channels and enhancing their function in the retina.
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Affiliation(s)
- Liheng Shi
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M UniversityCollege Station, TX, United States
| | - Michael L Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M UniversityCollege Station, TX, United States
| | - Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M UniversityCollege Station, TX, United States.,Texas A&M Institute for Neuroscience, Texas A&M UniversityCollege Station, TX, United States
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8
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MacDonald RB, Randlett O, Oswald J, Yoshimatsu T, Franze K, Harris WA. Müller glia provide essential tensile strength to the developing retina. J Cell Biol 2015; 210:1075-83. [PMID: 26416961 PMCID: PMC4586739 DOI: 10.1083/jcb.201503115] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
When the formation of Müller glia is inhibited in the zebrafish retina, a major consequence is that the retina begins to rip apart due to a loss of the mechanical resilience that these glial cells provide to the neural tissue. To investigate the cellular basis of tissue integrity in a vertebrate central nervous system (CNS) tissue, we eliminated Müller glial cells (MG) from the zebrafish retina. For well over a century, glial cells have been ascribed a mechanical role in the support of neural tissues, yet this idea has not been specifically tested in vivo. We report here that retinas devoid of MG rip apart, a defect known as retinoschisis. Using atomic force microscopy, we show that retinas without MG have decreased resistance to tensile stress and are softer than controls. Laser ablation of MG processes showed that these cells are under tension in the tissue. Thus, we propose that MG act like springs that hold the neural retina together, finally confirming an active mechanical role of glial cells in the CNS.
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Affiliation(s)
- Ryan B MacDonald
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
| | - Owen Randlett
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
| | - Julia Oswald
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
| | - Takeshi Yoshimatsu
- Department of Biological Structure, University of Washington, Seattle, WA 98195
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
| | - William A Harris
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, England, UK
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10
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Byrne LC, Oztürk BE, Lee T, Fortuny C, Visel M, Dalkara D, Schaffer DV, Flannery JG. Retinoschisin gene therapy in photoreceptors, Müller glia or all retinal cells in the Rs1h-/- mouse. Gene Ther 2014; 21:585-92. [PMID: 24694538 PMCID: PMC4047144 DOI: 10.1038/gt.2014.31] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 01/28/2014] [Accepted: 02/25/2014] [Indexed: 01/21/2023]
Abstract
X-linked retinoschisis, a disease characterized by splitting of the retina, is caused by mutations in the retinoschisin gene, which encodes a secreted cell adhesion protein. Currently, there is no effective treatment for retinoschisis, though viral vector-mediated gene replacement therapies offer promise. We used intravitreal delivery of three different AAV vectors to target delivery of the RS1 gene to Müller glia, photoreceptors, or multiple cell types throughout the retina. Müller glia radially span the entire retina, are accessible from the vitreous, and remain intact throughout progression of the disease. However, photoreceptors, not glia, normally secrete retinoschisin. We compared the efficacy of rescue mediated by retinoschisin secretion from these specific subtypes of retinal cells in the Rs1h−/− mouse model of retinoschisis. Our results indicate that all three vectors deliver the RS1 gene, and that several cell types can secrete retinoschisin, leading to transport of the protein across the retina. The greatest long-term rescue was observed when photoreceptors produce retinoschisin. Similar rescue was observed with photoreceptor-specific or generalized expression, though photoreceptor secretion may contribute to rescue in the latter case. These results collectively point to the importance of cell targeting and appropriate vector choice in the success of retinal gene therapies.
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Affiliation(s)
- L C Byrne
- 1] Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [2] Department of Chemical and Biomolecular Engineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [3] Department of Bioengineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - B E Oztürk
- Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - T Lee
- Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - C Fortuny
- 1] Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [2] Department of Vision Science, The University of California, Berkeley, CA, USA
| | - M Visel
- Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - D Dalkara
- 1] Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [2] Department of Chemical and Biomolecular Engineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [3] Department of Bioengineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - D V Schaffer
- 1] Department of Chemical and Biomolecular Engineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [2] Department of Bioengineering, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA
| | - J G Flannery
- 1] Department of Molecular and Cellular Biology, The Helen Wills Neuroscience Institute, The University of California, Berkeley, CA, USA [2] Department of Vision Science, The University of California, Berkeley, CA, USA
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Abstract
Ion channels are the gatekeepers to neuronal excitability. Retinal neurons of vertebrates and invertebrates, neurons of the suprachiasmatic nucleus (SCN) of vertebrates, and pinealocytes of non-mammalian vertebrates display daily rhythms in their activities. The interlocking transcription-translation feedback loops with specific post-translational modulations within individual cells form the molecular clock, the basic mechanism that maintains the autonomic approximately 24-h rhythm. The molecular clock regulates downstream output signaling pathways that further modulate activities of various ion channels. Ultimately, it is the circadian regulation of ion channel properties that govern excitability and behavior output of these neurons. In this review, we focus on the recent development of research in circadian neurobiology mainly from 1980 forward. We will emphasize the circadian regulation of various ion channels, including cGMP-gated cation channels, various voltage-gated calcium and potassium channels, Na(+)/K(+)-ATPase, and a long-opening cation channel. The cellular mechanisms underlying the circadian regulation of these ion channels and their functions in various tissues and organisms will also be discussed. Despite the magnitude of chronobiological studies in recent years, the circadian regulation of ion channels still remains largely unexplored. Through more investigation and understanding of the circadian regulation of ion channels, the future development of therapeutic strategies for the treatment of sleep disorders, cardiovascular diseases, and other illnesses linked to circadian misalignment will benefit.
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Affiliation(s)
- Gladys Y-P Ko
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843-4458, USA.
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Vijayasarathy C, Ziccardi L, Zeng Y, Smaoui N, Caruso RC, Sieving PA. Null retinoschisin-protein expression from an RS1 c354del1-ins18 mutation causing progressive and severe XLRS in a cross-sectional family study. Invest Ophthalmol Vis Sci 2009; 50:5375-83. [PMID: 19474399 DOI: 10.1167/iovs.09-3839] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To explore the retinoschisin (RS1) protein biochemical phenotype from an RS1 exon-5 deletion/insertion frame-shift mutation in a family with X-linked retinoschisis (XLRS) and describe the clinical and electrophysiological features. METHODS Six XLRS males underwent ophthalmic examination and electroretinogram (ERG) recording. The RS1 gene was sequenced. Mutant RS1-RNA and protein expression were assessed by transfecting COS-7 cells with minigene constructs. RESULTS All six males carried the RS1 c354del1-ins18 mutation in which an 18-bp insertion replaced nucleotide 354, duplicating the adjacent upstream intron 4-to-exon 5 junction and creating a premature termination codon downstream. Analysis indicated normal pre-mRNA splicing producing mRNA transcripts. Truncated RS1 protein was expressed transiently but was degraded rapidly by a proteasomal pathway rather than by nonsense-mediated mRNA decay. Two boys, 1.5 and 5 years of age, had foveal cysts and minimal peripheral schisis, and retained near-normal scotopic b-wave amplitude and normal ERG waveforms. The 5-year-old's ERG was diminished when repeated 3 years later. Four older XLRS relatives 32 to 45 years old had substantial b-wave loss and strongly electronegative ERGs; three had overt macular atrophy. Cross-sectional family analysis showed the b-/a-wave amplitude ratio as inversely related to age in the six males. CONCLUSIONS The c354del1-ins18 mutation caused an RS1-null biochemical phenotype and a progressive clinical phenotype in a 5-year-old boy, whereas the older XLRS relatives had macular atrophy and marked ERG changes. The phenotypic heterogeneity with age by cross-sectional study of this family mutation argues that XLRS disease is not stationary and raises questions regarding factors involved in progression.
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Affiliation(s)
- Camasamudram Vijayasarathy
- Section for Translational Research in Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
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Shi L, Jian K, Ko ML, Trump D, Ko GYP. Retinoschisin, a new binding partner for L-type voltage-gated calcium channels in the retina. J Biol Chem 2008; 284:3966-75. [PMID: 19074145 DOI: 10.1074/jbc.m806333200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The L-type voltage-gated calcium channels (L-VGCCs) are activated under high depolarization voltages. They are vital for diverse biological events, including cell excitability, differentiation, and synaptic transmission. In retinal photoreceptors, L-VGCCs are responsible for neurotransmitter release and are under circadian influences. However, the mechanism of L-VGCC regulation in photoreceptors is not fully understood. Here, we show that retinoschisin, a highly conserved extracellular protein, interacts with the L-VGCCalpha1D subunit and regulates its activities in a circadian manner. Mutations in the gene encoding retinoschisin (RS1) cause retinal disorganization that leads to early onset of macular degeneration. Since ion channel activities can be modulated through interactions with extracellular proteins, disruption of these interactions can alter physiology and be the root cause of disease states. Co-immunoprecipitation and mammalian two-hybrid assays showed that retinoschisin and the N-terminal fragment of the L-VGCCalpha1 subunit physically interacted with one another. The expression and secretion of retinoschisin are under circadian regulation with a peak at night and nadir during the day. Inhibition of L-type VGCCs decreased membrane-bound retinoschisin at night. Overexpression of a missense RS1 mutant gene, R141G, into chicken cone photoreceptors caused a decrease of L-type VGCC currents at night. Our findings demonstrate a novel bidirectional relationship between an ion channel and an extracellular protein; L-type VGCCs regulate the circadian rhythm of retinoschisin secretion, whereas secreted retinoschisin feeds back to regulate L-type VGCCs. Therefore, physical interactions between L-VGCCalpha1 subunits and retinoschisin play an important role in the membrane retention of L-VGCCalpha1 subunits and photoreceptor-bipolar synaptic transmission.
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Affiliation(s)
- Liheng Shi
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77843-4458, USA
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Takada Y, Vijayasarathy C, Zeng Y, Kjellstrom S, Bush RA, Sieving PA. Synaptic pathology in retinoschisis knockout (Rs1-/y) mouse retina and modification by rAAV-Rs1 gene delivery. Invest Ophthalmol Vis Sci 2008; 49:3677-86. [PMID: 18660429 DOI: 10.1167/iovs.07-1071] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE At an early age, the retinoschisin knockout (Rs1-KO) mouse retina has progressive photoreceptor degeneration with severe disruption of the outer plexiform layer (OPL) that decreases at older ages. The electroretinogram (ERG) undergoes parallel changes. The b-wave amplitude from bipolar cells is reduced disproportionately to the photoreceptor a-wave at young but not at older ages. The protein expression and morphology of the OPL in Rs1-KO mice was investigated at different ages, to explore the role of the synaptic layer in these ERG changes. METHODS Retinas of wild-type (Wt) and Rs1-KO mice from postnatal day (P)7 to 12 months were evaluated by light and electron microscopy (EM) and biochemistry. PSD95 (postsynaptic density protein), mGluR6 (metabotropic glutamate receptor subtype 6), retinoschisin (Rs1), the Müller cell proteins glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS), the bipolar cell marker protein kinase C alpha (PKCalpha), and the horizontal cell marker calbindin were localized by immunofluorescence and immuno-EM. Levels of PSD95 and mGluR6 were determined by quantitative Western blot. Rs1-KO mice treated by intravitreous injection of rAAV(2/2)-CMV-Rs1 in one eye at P14 were evaluated at 8 months by full-field scotopic ERG responses and retinal immunohistochemistry. RESULTS Rs1 was associated with the outer surface of synaptic membranes in wild-type (Wt) retinas. PSD95 and mGluR6 were juxtaposed in the OPL of the Rs1-KO retinas by P14, implying that synaptic structures are formed. Light microscopic retinal morphology was similar in Wt and Rs1-KO at P14, but by P21, the OPL was disrupted in Rs1-KO, and some PSD95 and mGluR6 was mislocalized in the outer nuclear layer (ONL). GFAP expression spanned all retinal layers. EM showed synaptic structures adjacent to photoreceptor nuclei. PSD95 and mGluR6 levels were normal at 1 month on Western blot but declined to 59% (P < 0.001) and 55% (P < 0.05) of Wt, respectively, by 4 months. Levels thereafter showed no further reduction out to 12 months. Eyes injected with AAV-Rs1 were studied at 8 months by immunohistochemistry and had higher expression of PSD95 and mGluR6 and less GFAP expression compared with fellow untreated eyes. CONCLUSIONS In the Rs1-KO mouse, retinal layer formation and synaptic protein expression in the OPL is normal up to P14, implying normal development of synaptic connections. Aberrant localization of synaptic proteins by P21 indicates that displacement of developing and/or mature synapses contributes to the b-wave reduction at young ages, when photoreceptor numbers and synaptic protein levels are normal. The subsequent decline in PSD95 and mGluR6 between 1 and 12 months in Rs1-KO retina mirrors the course of b-wave change and provides evidence of causal relationship between the ERG and OPL changes. These findings and the improved structural integrity of the OPL and b-wave amplitude after Rs1 gene transfer therapy provide a cellular and molecular basis for interpreting the changes in retinal signaling in this model.
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Affiliation(s)
- Yuichiro Takada
- Section for Translational Research in Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
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Janssen A, Min SH, Molday LL, Tanimoto N, Seeliger MW, Hauswirth WW, Molday RS, Weber BHF. Effect of Late-stage Therapy on Disease Progression in AAV-mediated Rescue of Photoreceptor Cells in the Retinoschisin-deficient Mouse. Mol Ther 2008; 16:1010-7. [DOI: 10.1038/mt.2008.57] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Vijayasarathy C, Takada Y, Zeng Y, Bush RA, Sieving PA. Organization and molecular interactions of retinoschisin in photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 613:291-7. [PMID: 18188957 DOI: 10.1007/978-0-387-74904-4_34] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Affiliation(s)
- Camasamudram Vijayasarathy
- Section for Translational Research in Retinal and Macular Degeneration, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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Iannaccone A, Mura M, Dyka FM, Ciccarelli ML, Yashar BM, Ayyagari R, Jablonski MM, Molday RS. An unusual X-linked retinoschisis phenotype and biochemical characterization of the W112C RS1 mutation. Vision Res 2006; 46:3845-52. [PMID: 16884758 DOI: 10.1016/j.visres.2006.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2006] [Revised: 06/02/2006] [Accepted: 06/09/2006] [Indexed: 10/24/2022]
Abstract
A 52-year-old subject harboring an RS1 gene W112C mutation presented with a prominent and asymmetric tapetal-like retinal sheen. Transient ERG responses were smaller and slower in the eye with the more extensive sheen, an association that, to our knowledge, had not been previously reported. An ON-pathway dysfunction explained the abnormalities of the transient but not those of the flicker ERGs. Although in vitro studies showed that the W112C mutant retinoschisin is present only in the cellular fraction and is not secreted, disease expression was remarkably mild, consistent with the notion of the existence of genetic and/or epigenetic disease modifiers.
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Affiliation(s)
- Alessandro Iannaccone
- Hamilton Eye Institute, Department of Ophthalmology, University of Tennessee Health Science Center, 930 Madison Avenue, Suite 731, Memphis, TN 38163, USA.
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Gehrig A, Janssen A, Horling F, Grimm C, Weber BHF. The role of caspases in photoreceptor cell death of the retinoschisin-deficient mouse. Cytogenet Genome Res 2006; 115:35-44. [PMID: 16974082 DOI: 10.1159/000094799] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2005] [Accepted: 03/09/2006] [Indexed: 12/28/2022] Open
Abstract
Early schisis cavities in the retinal bipolar cell layer accompanied by progressive loss of cone and rod photoreceptor cells are the hallmark of the retinoschisin-deficient (Rs1h(-/Y)) murine retina. With this study we aimed at elucidating the molecular events underlying the photoreceptor cell death in this established murine model of X-linked juvenile retinoschisis. We show that photoreceptor degeneration in the Rs1h(-/Y) mouse is due to apoptotic events peaking around postnatal day 18. Cell death is accompanied by increased expression of initiator and inflammatory caspases but not by downstream effector caspases. The strong induction of caspase-1 (Casp1) prompted us to explore its involvement in the apoptotic process. We therefore generated double knock-out mice deficient for both retinoschisin and Casp1. No direct influence of the Casp1 genotype on apoptosis could be identified although striking differences in the overall number of resident microglia were observed independent of the Rs1h genotype.
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Affiliation(s)
- A Gehrig
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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Eksandh L, Andréasson S, Abrahamson M. Juvenile X-linked retinoschisis with normal scotopic b-wave in the electroretinogram at an early stage of the disease. Ophthalmic Genet 2005; 26:111-7. [PMID: 16272055 DOI: 10.1080/13816810500228688] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE To report four cases of genetically verified juvenile X-linked retinoschisis (XLRS) with normal scotopic b-waves in full-field ERG, including one patient with a novel mutation (W50X) in the RS1 gene. METHODS Four XLRS patients from different families were examined with regard to visual acuity, kinetic perimetry, fundus photography, full-field ERG, and OCT. Two of these patients were also examined with multifocal-ERG (mfERG). Mutations in the RS1 gene were identified by sequence analysis. RESULTS The full-field ERG presented normal b-wave amplitudes on scotopic white-light stimulation. OCT and mfERG presented macular schisis and macular dysfunction. Genetic analysis revealed a deletion of exon 1 and the promotor region in one patient and mutations giving rise to the amino acid substitutions R209C and W96R in two others. The fourth patient carried a novel mutation in exon 3 of the RS1 gene (nt 149 G-->A), causing the introduction of a stop codon after amino acid 49 in the RS protein. CONCLUSION Four young males with XLRS did not present with reduction in the scotopic b-wave amplitude on full-field ERG, which is otherwise often considered to be characteristic of the disease. Full-field ERG and molecular genetic analysis of the RS1 gene still remain the most important diagnostic tools for this retinal disorder, although the OCT can be a valuable complement in order to make the diagnosis at an early stage.
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Affiliation(s)
- Louise Eksandh
- Department of Ophthalmology, University Hospital of Lund, Sweden.
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