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Tam BM, Burns P, Chiu CN, Moritz OL. Synchronized Photoactivation of T4K Rhodopsin Causes a Chromophore-Dependent Retinal Degeneration That Is Moderated by Interaction with Phototransduction Cascade Components. J Neurosci 2024; 44:e0453242024. [PMID: 39089885 PMCID: PMC11376340 DOI: 10.1523/jneurosci.0453-24.2024] [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: 03/06/2024] [Revised: 06/29/2024] [Accepted: 07/24/2024] [Indexed: 08/04/2024] Open
Abstract
Multiple mutations in the Rhodopsin gene cause sector retinitis pigmentosa in humans and a corresponding light-exacerbated retinal degeneration (RD) in animal models. Previously we have shown that T4K rhodopsin requires photoactivation to exert its toxic effect. Here we further investigated the mechanisms involved in rod cell death caused by T4K rhodopsin in mixed male and female Xenopus laevis In this model, RD was prevented by rearing animals in constant darkness but surprisingly also in constant light. RD was maximized by light cycles containing at least 1 h of darkness and 20 min of light exposure, light intensities >750 lux, and by a sudden light onset. Under conditions of frequent light cycling, RD occurred rapidly and synchronously, with massive shedding of ROS fragments into the RPE initiated within hours and subsequent death and phagocytosis of rod cell bodies. RD was minimized by reduced light levels, pretreatment with constant light, and gradual light onset. RD was prevented by genetic ablation of the retinal isomerohydrolase RPE65 and exacerbated by ablation of phototransduction components GNAT1, SAG, and GRK1. Our results indicate that photoactivated T4K rhodopsin is toxic, that cell death requires synchronized photoactivation of T4K rhodopsin, and that toxicity is mitigated by interaction with other rod outer segment proteins regardless of whether they participate in activation or shutoff of phototransduction. In contrast, RD caused by P23H rhodopsin does not require photoactivation of the mutant protein, as it was exacerbated by RPE65 ablation, suggesting that these phenotypically similar disorders may require different treatment strategies.
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Affiliation(s)
- Beatrice M Tam
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, British Columbia V5Z 3N9, Canada
| | - Paloma Burns
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, British Columbia V5Z 3N9, Canada
| | - Colette N Chiu
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, British Columbia V5Z 3N9, Canada
| | - Orson L Moritz
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, British Columbia V5Z 3N9, Canada
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2
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Sanghi P, Bober E, Mahroo OA, Nicholson L. Central serous chorioretinopathy with a golden sheen. Eye (Lond) 2024; 38:92-93. [PMID: 38355672 PMCID: PMC11428783 DOI: 10.1038/s41433-024-02971-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 01/13/2024] [Accepted: 01/26/2024] [Indexed: 02/16/2024] Open
Affiliation(s)
- Priyanka Sanghi
- Medical Retina Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK.
| | - Emilia Bober
- Medical Retina Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Omar A Mahroo
- Medical Retina Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK
- Institute of Ophthalmology, University College London, London, UK
| | - Luke Nicholson
- Medical Retina Service, Moorfields Eye Hospital NHS Foundation Trust, London, UK
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3
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Akhtar HN, Nicholson L, Ockrim Z, Neveu M, Webster AR, Michaelides M, Mahroo OA. Loss of sheen in Oguchi disease following short wavelength exposure. Eye (Lond) 2024:10.1038/s41433-024-03237-4. [PMID: 39003433 DOI: 10.1038/s41433-024-03237-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 06/21/2024] [Accepted: 07/09/2024] [Indexed: 07/15/2024] Open
Affiliation(s)
- Haseeb N Akhtar
- UCL Institute of Ophthalmology, University College London, London, UK
- Retinal Service, Moorfields Eye Hospital, London, UK
| | | | - Zoe Ockrim
- Retinal Service, Moorfields Eye Hospital, London, UK
| | - Magella Neveu
- Electrophysiology Service, Moorfields Eye Hospital, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, London, UK
- Retinal Service, Moorfields Eye Hospital, London, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, London, UK
- Retinal Service, Moorfields Eye Hospital, London, UK
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, University College London, London, UK.
- Retinal Service, Moorfields Eye Hospital, London, UK.
- Department of Ophthalmology, St Thomas' Hospital, London, UK.
- Section of Ophthalmology, King's College London St Thomas' Hospital Campus, London, UK.
- Translational Ophthalmology, Wills Eye Hospital, Philadelphia, USA.
- Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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Vishnivetskiy SA, Weinstein LD, Zheng C, Gurevich EV, Gurevich VV. Functional Role of Arrestin-1 Residues Interacting with Unphosphorylated Rhodopsin Elements. Int J Mol Sci 2023; 24:ijms24108903. [PMID: 37240250 DOI: 10.3390/ijms24108903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 05/11/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Arrestin-1, or visual arrestin, exhibits an exquisite selectivity for light-activated phosphorylated rhodopsin (P-Rh*) over its other functional forms. That selectivity is believed to be mediated by two well-established structural elements in the arrestin-1 molecule, the activation sensor detecting the active conformation of rhodopsin and the phosphorylation sensor responsive to the rhodopsin phosphorylation, which only active phosphorylated rhodopsin can engage simultaneously. However, in the crystal structure of the arrestin-1-rhodopsin complex there are arrestin-1 residues located close to rhodopsin, which do not belong to either sensor. Here we tested by site-directed mutagenesis the functional role of these residues in wild type arrestin-1 using a direct binding assay to P-Rh* and light-activated unphosphorylated rhodopsin (Rh*). We found that many mutations either enhanced the binding only to Rh* or increased the binding to Rh* much more than to P-Rh*. The data suggest that the native residues in these positions act as binding suppressors, specifically inhibiting the arrestin-1 binding to Rh* and thereby increasing arrestin-1 selectivity for P-Rh*. This calls for the modification of a widely accepted model of the arrestin-receptor interactions.
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Affiliation(s)
| | - Liana D Weinstein
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Chen Zheng
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
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Ruiz-Ceja KA, Capasso D, Pinelli M, Del Prete E, Carrella D, di Bernardo D, Banfi S. Definition of the transcriptional units of inherited retinal disease genes by meta-analysis of human retinal transcriptome data. BMC Genomics 2023; 24:206. [PMID: 37072692 PMCID: PMC10111803 DOI: 10.1186/s12864-023-09300-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 04/07/2023] [Indexed: 04/20/2023] Open
Abstract
BACKGROUND Inherited retinal diseases (IRD) are genetically heterogeneous disorders that cause the dysfunction or loss of photoreceptor cells and ultimately lead to blindness. To date, next-generation sequencing procedures fail to detect pathogenic sequence variants in coding regions of known IRD disease genes in about 30-40% of patients. One of the possible explanations for this missing heritability is the presence of yet unidentified transcripts of known IRD genes. Here, we aimed to define the transcript composition of IRD genes in the human retina by a meta-analysis of publicly available RNA-seq datasets using an ad-hoc designed pipeline. RESULTS We analysed 218 IRD genes and identified 5,054 transcripts, 3,367 of which were not previously reported. We assessed their putative expression levels and focused our attention on 435 transcripts predicted to account for at least 5% of the expression of the corresponding gene. We looked at the possible impact of the newly identified transcripts at the protein level and experimentally validated a subset of them. CONCLUSIONS This study provides an unprecedented, detailed overview of the complexity of the human retinal transcriptome that can be instrumental in contributing to the resolution of some cases of missing heritability in IRD patients.
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Affiliation(s)
- Karla Alejandra Ruiz-Ceja
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Program in Molecular Life Science, University of Campania "Luigi Vanvitelli", Via Vivaldi, 43, 81100, Caserta, Italy
| | - Dalila Capasso
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Scuola Superiore Meridionale (SSM, School of Advanced Studies), Genomic and Experimental Medicine Program, University of Naples "Federico II", Largo S. Marcellino, 10, 80138, Napoli, Italy
| | - Michele Pinelli
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Eugenio Del Prete
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Diego Carrella
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
| | - Diego di Bernardo
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy
- Chemical Engineering, University of Naples "Federico II", Piazzale Tecchio, 80, 80125, Napoli, Italy
| | - Sandro Banfi
- Telethon Institute of Genetics and Medicine (TIGEM), Via Campi Flegrei, 34, 80078, Pozzuoli, Italy.
- Department of Precision Medicine, University of Campania "Luigi Vanvitelli", Via de Crecchio, 7, 80138, Napoli, Italy.
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Gulati S, Palczewski K. Structural view of G protein-coupled receptor signaling in the retinal rod outer segment. Trends Biochem Sci 2023; 48:172-186. [PMID: 36163145 PMCID: PMC9868064 DOI: 10.1016/j.tibs.2022.08.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 01/26/2023]
Abstract
Visual phototransduction is the most extensively studied G protein-coupled receptor (GPCR) signaling pathway because of its quantifiable stimulus, non-redundancy of genes, and immense importance in vision. We summarize recent discoveries that have advanced our understanding of rod outer segment (ROS) morphology and the pathological basis of retinal diseases. We have combined recently published cryo-electron tomography (cryo-ET) data on the ROS with structural knowledge on individual proteins to define the precise spatial limitations under which phototransduction occurs. Although hypothetical, the reconstruction of the rod phototransduction system highlights the potential roles of phosphodiesterase 6 (PDE6) and guanylate cyclases (GCs) in maintaining the spacing between ROS discs, suggesting a plausible mechanism by which intrinsic optical signals are generated in the retina.
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Affiliation(s)
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, Center for Translational Vision Research, Department of Physiology and Biophysics, Department of Chemistry, Molecular Biology, and Biochemistry, University of California Irvine, 850 Health Sciences Road, Irvine, CA 92697-4375, USA.
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Wei X, Li H, Wu S, Zhu T, Sui R. Genetic analysis and clinical features of three Chinese patients with Oguchi disease. Doc Ophthalmol 2023; 146:17-32. [PMID: 36417138 DOI: 10.1007/s10633-022-09910-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 10/27/2022] [Indexed: 11/24/2022]
Abstract
BACKGROUND Oguchi disease is a rare autosomal recessive form of congenital stationary night blindness caused by disease-causing variants in the rhodopsin kinase gene (GRK1) or the arrestin gene (SAG). Our study aims to describe the clinical features and identify the genetic defects for three Chinese patients with Oguchi disease. METHODS We conducted detailed ophthalmologic examinations for three patients from three unrelated non-consanguineous Chinese families. Targeted next-generation sequencing (targeted NGS) and copy number variations (CNVs) analysis were applied to screen pathogenic variants. Sanger sequencing validation, quantitative real-time PCR (qPCR), and segregation analysis were further performed for confirmation. Subsequently, a combined genetic and structural biology approach was used to infer the likely functional consequences of novel variants. RESULTS All three patients presented with typical clinical features of Oguchi disease, including night blindness, characteristic fundus appearance (Mizuo-Nakamura phenomenon), attenuated rod responses, and negative ERG waveforms. Their visual acuity and visual field were normal. Genetic analysis revealed two pathogenic variants in SAG and four pathogenic variants in GRK1. Patient 1 was identified to harbor compound heterozygous SAG variants c.874C > T (p.R292*) and exon2 deletion. Compound heterozygous GRK1 variants c.55C > T (p.R19*) and c.1412delC (p.P471Lfs*52) were found in patient 2. In patient 3, compound heterozygous GRK1 variants c.946C > A (p.R316S) and c.1388 T > C (p. L463P) were detected. CONCLUSIONS We reported the first two Chinese Oguchi patients with novel GRK1 pathogenic variants (P471Lfs*52, R316S, L463P) and one Oguchi case with SAG, indicating both GRK1 and SAG are important causative genes in Chinese Oguchi patients.
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Affiliation(s)
- Xing Wei
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, No. 1, Shuai Fu Yuan, Beijing, 100730, People's Republic of China
| | - Hui Li
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, No. 1, Shuai Fu Yuan, Beijing, 100730, People's Republic of China
| | - Shijing Wu
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, No. 1, Shuai Fu Yuan, Beijing, 100730, People's Republic of China
| | - Tian Zhu
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, No. 1, Shuai Fu Yuan, Beijing, 100730, People's Republic of China
| | - Ruifang Sui
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College Hospital, No. 1, Shuai Fu Yuan, Beijing, 100730, People's Republic of China.
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8
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Sarici K, Vyas A, Iannaccone A. The double-edged sword of inflammation in inherited retinal degenerations: Clinical and preclinical evidence for mechanistically and prognostically impactful but treatable complications. Front Cell Dev Biol 2023; 11:1177711. [PMID: 37123408 PMCID: PMC10135873 DOI: 10.3389/fcell.2023.1177711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/03/2023] [Indexed: 05/02/2023] Open
Abstract
We present retrospective data from our clinical research efforts of the past several years alongside a review of past and current clinical and preclinical data independently by several investigators supporting our clinical evidence for the importance of inflammation in inherited retinal degenerations (IRDs). We show how inflammation is a complicating factor in IRDs but, if recognized and managed, also a great opportunity to mitigate disease severity immediately, improve patient prognosis and quality of life, extend the treatment windows for gene-specific and agnostic therapeutic approaches, mitigate the impact of inflammatory complications on the accurate estimate of vision changes in IRD natural history studies, improve the chances of safer outcomes following cataract surgery, and potentially reduce the likelihood of inflammatory adverse events and augment the efficacy of viral vector-based treatment approaches to IRDs. Manuscript contribution to the field. Inflammation has been suspected to be at play in IRDs since the beginning of the 1900s and became a research focus through the early 1990s but was then largely abandoned in favor of genetic-focused research. Thanks to regained cognizance, better research tools, and a more holistic approach to IRDs, the recent reappraisal of the role of inflammation in IRDs has brought back to the surface its importance. A potential confounder in natural history studies and a limiting factor in clinical trials if not accounted for, inflammation can be managed and often offers an opportunity for immediately improved prognosis and outcomes for IRD patients. We present our retrospective clinical evidence for connections with a measurable secondary autoimmune component that can develop in IRDs and contribute to vision loss but is at least in part treatable. We also present ample lines of evidence from the literature corroborating our clinical observations at the preclinical level.
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Chrispell JD, Xiong Y, Weiss ER. Grk7 but not Grk1 undergoes cAMP-dependent phosphorylation in zebrafish cone photoreceptors and mediates cone photoresponse recovery to elevated cAMP. J Biol Chem 2022; 298:102636. [PMID: 36273582 PMCID: PMC9692042 DOI: 10.1016/j.jbc.2022.102636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/07/2022] Open
Abstract
In the vertebrate retina, phosphorylation of photoactivated visual pigments in rods and cones by G protein-coupled receptor kinases (GRKs) is essential for sustained visual function. Previous in vitro analysis demonstrated that GRK1 and GRK7 are phosphorylated by PKA, resulting in a reduced capacity to phosphorylate rhodopsin. In vivo observations revealed that GRK phosphorylation occurs in the dark and is cAMP dependent. In many vertebrates, including humans and zebrafish, GRK1 is expressed in both rods and cones while GRK7 is expressed only in cones. However, mice express only GRK1 in both rods and cones and lack GRK7. We recently generated a mutation in Grk1 that deletes the phosphorylation site, Ser21. This mutant demonstrated delayed dark adaptation in mouse rods but not in cones in vivo, suggesting GRK1 may serve a different role depending upon the photoreceptor cell type in which it is expressed. Here, zebrafish were selected to evaluate the role of cAMP-dependent GRK phosphorylation in cone photoreceptor recovery. Electroretinogram analyses of larvae treated with forskolin show that elevated intracellular cAMP significantly decreases recovery of the cone photoresponse, which is mediated by Grk7a rather than Grk1b. Using a cone-specific dominant negative PKA transgene, we show for the first time that PKA is required for Grk7a phosphorylation in vivo. Lastly, immunoblot analyses of rod grk1a-/- and cone grk1b-/- zebrafish and Nrl-/- mouse show that cone-expressed Grk1 does not undergo cAMP-dependent phosphorylation in vivo. These results provide a better understanding of the function of Grk phosphorylation relative to cone adaptation and recovery.
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Bo J, Xu H, Lv W, Wang C, He S, Yang L. Molecular Mechanisms of the Convergent Adaptation of Bathypelagic and Abyssopelagic Fishes. Genome Biol Evol 2022; 14:evac109. [PMID: 35866587 PMCID: PMC9348623 DOI: 10.1093/gbe/evac109] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2022] [Indexed: 11/24/2022] Open
Abstract
Harsh environments provide opportunities to study how different species adapt, at the molecular level, to similar environmental stressors. High hydrostatic pressure, low temperature, and absence of sunlight in the deep-sea environment are challenging conditions for gene expression, cell morphology and vision. Adaptation of fish to this environment appears independently in at least 22 orders of fish, but it remains uncertain whether these adaptations represent convergent evolution. In this study, we performed comparative genomic analysis of 80 fish species to determine genetic evidences for adaptations to the deep-sea environment. The 80 fishes were divided into six groups according to their order. Positive selection and convergent evolutionary analysis were performed and functional enrichment analysis of candidate genes was performed. Positively selected genes (pik3ca, pik3cg, vcl and sphk2) were identified to be associated with the cytoskeletal response to mechanical forces and gene expression. Consistent signs of molecular convergence genes (grk1, ednrb, and nox1) in dark vision, skin color, and bone rarefaction were revealed. Functional assays of Grk1 showed that the convergent sites improved dark vision in deep-sea fish. By identifying candidate genes and functional profiles potentially involved in cold, dark, and high-pressure responses, the results of this study further enrich the understanding of fish adaptations to deep-sea environments.
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Affiliation(s)
- Jing Bo
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Han Xu
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenqi Lv
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cheng Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shunping He
- Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China
| | - Liandong Yang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
- Academy of Plateau Science and Sustainability, Qinghai Normal University, Xining, China
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Gurevich VV, Gurevich EV. Solo vs. Chorus: Monomers and Oligomers of Arrestin Proteins. Int J Mol Sci 2022; 23:ijms23137253. [PMID: 35806256 PMCID: PMC9266314 DOI: 10.3390/ijms23137253] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 06/28/2022] [Accepted: 06/29/2022] [Indexed: 02/05/2023] Open
Abstract
Three out of four subtypes of arrestin proteins expressed in mammals self-associate, each forming oligomers of a distinct kind. Monomers and oligomers have different subcellular localization and distinct biological functions. Here we summarize existing evidence regarding arrestin oligomerization and discuss specific functions of monomeric and oligomeric forms, although too few of the latter are known. The data on arrestins highlight biological importance of oligomerization of signaling proteins. Distinct modes of oligomerization might be an important contributing factor to the functional differences among highly homologous members of the arrestin protein family.
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12
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Tawfik CA, Elbagoury NM, Khater NI, Essawi ML. Mutation analysis reveals novel and known mutations in SAG gene in first two Egyptian families with Oguchi disease. BMC Ophthalmol 2022; 22:217. [PMID: 35549688 PMCID: PMC9103117 DOI: 10.1186/s12886-022-02444-5] [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: 01/10/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022] Open
Abstract
Background Oguchi disease is a rare type of congenital stationary night blindness associated with an abnormal fundus appearance. It is inherited in an autosomal recessive manner where two types exist according to the gene affected; type 1 associated with S-antigen (SAG) gene mutations and type 2 associated with rhodopsin kinase (GRK1) gene mutations. Purpose The aim of this work was to describe the clinical and genetic findings of the first two reported families of Oguchi disease in Egypt and African region. Methods Four members of two consanguineous Egyptian families with history of night blindness since childhood underwent complete ophthalmological examination, standard automated static perimetry, fundus color photography, fundus autofluorescence (FAF), fundus fluorescein angiography (FFA) in light-adapted state and spectral-domain optical coherence tomography (SD-OCT) of both the macula and the optic nerve head as well as central corneal thickness with repeated fundus photography following prolonged dark adaptation. Mutation screening of 7 coding exons of GRK1 gene and 15 coding exons of SAG gene as well as some flanking regions were performed using Sanger sequencing technique. The variants were tested for pathogenicity using different in silico functional analysis tools. Results The clinical examination and investigations confirmed Oguchi disease phenotype. One patient showed p.R193* (c.577C > T) which is a previously reported SAG gene mutation in a homozygous form. The other three patients from a different family showed (c.649–1 G > C), a novel canonical splice site SAG gene mutation in a homozygous form. Conclusion The identification of the novel canonical splice site SAG gene variant in three members of the same family with clinically confirmed Oguchi disease reinforces its pathogenicity. A fourth patient from another family carried a previously reported mutation in the same gene. SAG gene variants may be the underlying genetic cause for Oguchi disease in Egypt. Our findings have expanded the spectrum of Oguchi disease-associated mutations in SAG gene and may serve as a basis for genetic diagnosis for Oguchi disease.
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Affiliation(s)
- Caroline Atef Tawfik
- Department of Ophthalmology, Ain Shams University, 38 Abbasseya, Nour Mosque, El-Mohamady, Al Waili, Cairo, 11566, Egypt.
| | - Nagham Maher Elbagoury
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt.,Center of Excellence for Human Genetics, National Research Centre, Cairo, Egypt
| | - Noha Ibrahim Khater
- Department of Ophthalmology, Cairo University, Giza, Egypt.,Al Mouneer Diabetic Eye Center, Dokki, Giza, Egypt
| | - Mona Lotfi Essawi
- Medical Molecular Genetics Department, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt.,Center of Excellence for Human Genetics, National Research Centre, Cairo, Egypt
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Millette MA, Roy S, Salesse C. Farnesylation and lipid unsaturation are critical for the membrane binding of the C-terminal segment of G-Protein Receptor Kinase 1. Colloids Surf B Biointerfaces 2022; 211:112315. [PMID: 35026543 DOI: 10.1016/j.colsurfb.2021.112315] [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: 11/01/2021] [Revised: 12/15/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022]
Abstract
Many proteins are modified by the covalent addition of different types of lipids, such as myristoylation, palmitoylation and prenylation. Lipidation is expected to promote membrane association of proteins. Visual phototransduction involves many lipid-modified proteins. The G-Protein-coupled receptor of rod photoreceptors, rhodopsin, is inactivated by G-Protein-coupled Receptor Kinase 1 (GRK1). The C-terminus of GRK1 is farnesylated and its truncation has been shown to result in a very high decrease of its enzymatic activity, most likely because of the loss of its membrane localization. Little information is available on the membrane binding of GRK1 as well as of most prenylated proteins. Measurements of the membrane binding of the non-farnesylated and farnesylated C-terminal segment of GRK1 were thus performed using lipids typical of those found in rod outer segment disk membranes. Their random coil secondary structure was determined using circular dichroism and infrared spectroscopy. The non-farnesylated C-terminal segment of GRK1 has no surface activity. In contrast, the farnesylated C-terminal segment of GRK1 shows a particularly strong binding to lipid monolayers bearing at least one unsaturated fatty acyl chain. No binding is observed in the presence of monolayers of saturated phospholipids, in agreement with the low affinity of farnesylated Ras proteins for lipids in the liquid-ordered state. Altogether, these data demonstrate that the farnesyl group of the C-terminal segment of GRK1 is mandatory for its membrane binding, which is favored by particular lipids or lipid mixtures. This information will also be useful for the understanding of the membrane binding of other prenylated proteins.
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Affiliation(s)
- Marc-Antoine Millette
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sarah Roy
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de médecine, and Regroupement stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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14
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Azhar Baig HM, Ansar M, Iqbal A, Naeem MA, Quinodoz M, Calzetti G, Iqbal M, Rivolta C. Genetic analysis of consanguineous Pakistani families with congenital stationary night blindness. Ophthalmic Res 2021; 65:104-110. [PMID: 34781300 DOI: 10.1159/000520895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/28/2021] [Indexed: 11/19/2022]
Abstract
AIM Congenital stationary night blindness (CSNB) is a rare, largely non progressive, inherited retinal disorder that can be clinically classified on the basis of fundus and electroretinogram (ERG) abnormalities. METHODS We analyzed four large consanguineous families from the Southern Punjab region of Pakistan including multiple individuals affected with CSNB. Exome sequencing (ES) was performed in probands of all four families; Sanger sequencing was performed in additional members to test co-segregation of the variants identified. RESULTS We identified two novel and likely pathogenic variants in two pedigrees, namely NM_002905.4:c.668A>C (p.Gln223Pro) in RDH5, and NM_022567.2:c.908del (p.Gly303ValfsTer45) in NYX. In the two other families, the variants NM_002905.4:c.319G>C (p.Gly107Arg) in RDH5 and NM_000541.5:c.874C>T (p.Arg292Ter) in SAG were identified. These variants have been reported previously, but not in the Pakistani population. CONCLUSIONS Our findings expand the mutational spectrum of CSNB, in particular within the population of Southern Punjab.
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Affiliation(s)
- Hafiz Muhammad Azhar Baig
- Department of Biotechnology, Institute of Biochemistry, Biotechnology and Bioinformatics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Muhammad Ansar
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Afia Iqbal
- Department of Zoology, Lahore College for Women University, Lahore, Pakistan
| | - Muhammad Asif Naeem
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Mathieu Quinodoz
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Giacomo Calzetti
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Muhammad Iqbal
- Department of Biotechnology, Institute of Biochemistry, Biotechnology and Bioinformatics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Carlo Rivolta
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland
- Department of Ophthalmology, University of Basel, Basel, Switzerland
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
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15
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Jiang X, Mahroo OA. Negative electroretinograms: genetic and acquired causes, diagnostic approaches and physiological insights. Eye (Lond) 2021; 35:2419-2437. [PMID: 34127841 PMCID: PMC8377097 DOI: 10.1038/s41433-021-01604-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/05/2021] [Accepted: 05/10/2021] [Indexed: 02/07/2023] Open
Abstract
The dark-adapted human electroretinogram (ERG) response to a standard bright flash includes a negative-going a-wave followed by a positive-going b-wave that crosses the baseline. An electronegative waveform (or negative ERG) results when the b-wave is selectively reduced such that the ERG fails to cross the baseline following the a-wave. In the context of a normally sized a-wave, it indicates a site of retinal dysfunction occurring after phototransduction (commonly at the photoreceptor to bipolar cell synapse). This is an important finding. In genetic disease, the pattern of ERG abnormality can point to variants in a small group of genes (frequently those associated with congenital stationary night blindness and X-linked retinoschisis, but negative ERGs can also be seen in other conditions including syndromic disease). In acquired disease, there are numerous causes, but specific features may point to melanoma-associated retinopathy (MAR). In some cases, the visual symptoms precede the diagnosis of the melanoma and so the ERG findings can initiate investigations facilitating early detection and treatment. Negative ERGs can occur in other paraneoplastic conditions, and in a range of other diseases. This review will outline the physiological basis for the negative ERG, report prevalences in the literature from different cohorts, discuss the range of causes, displaying examples of a number of ERG phenotypes, highlight features of a clinical approach to patients, and briefly discuss further insights relating to current flows shaping the a-wave trough and from single-cell transcriptome analysis.
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Affiliation(s)
- Xiaofan Jiang
- grid.83440.3b0000000121901201Institute of Ophthalmology, University College London, London, UK ,grid.439257.e0000 0000 8726 5837Retinal and Genetics Services, Moorfields Eye Hospital, London, UK ,grid.425213.3Section of Ophthalmology and Department of Twin Research and Genetic Epidemiology, King’s College London, St Thomas’ Hospital Campus, London, UK
| | - Omar A. Mahroo
- grid.83440.3b0000000121901201Institute of Ophthalmology, University College London, London, UK ,grid.439257.e0000 0000 8726 5837Retinal and Genetics Services, Moorfields Eye Hospital, London, UK ,grid.425213.3Section of Ophthalmology and Department of Twin Research and Genetic Epidemiology, King’s College London, St Thomas’ Hospital Campus, London, UK ,grid.5335.00000000121885934Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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16
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Spedicati B, Cocca M, Palmisano R, Faletra F, Barbieri C, Francescatto M, Mezzavilla M, Morgan A, Pelliccione G, Gasparini P, Girotto G. Natural human knockouts and Mendelian disorders: deep phenotyping in Italian isolates. Eur J Hum Genet 2021; 29:1272-1281. [PMID: 33727708 PMCID: PMC8384846 DOI: 10.1038/s41431-021-00850-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 12/30/2020] [Accepted: 02/23/2021] [Indexed: 02/02/2023] Open
Abstract
Whole genome sequencing (WGS) allows the identification of human knockouts (HKOs), individuals in whom loss of function (LoF) variants disrupt both alleles of a given gene. HKOs are a valuable model for understanding the consequences of genes function loss. Naturally occurring biallelic LoF variants tend to be significantly enriched in "genetic isolates," making these populations specifically suited for HKO studies. In this work, a meticulous WGS data analysis combined with an in-depth phenotypic assessment of 947 individuals from three Italian genetic isolates led to the identification of ten biallelic LoF variants in ten OMIM genes associated with known autosomal recessive diseases. Notably, only a minority of the identified HKOs (C7, F12, and GPR68 genes) displayed the expected phenotype. For most of the genes, instead, (ACADSB, FANCL, GRK1, LGI4, MPO, PGAM2, and RP1L1), the carriers showed none or few of the signs and symptoms typically associated with the related diseases. Of particular interest is a case presenting with a FANCL biallelic LoF variant and a positive diepoxybutane test but lacking a full Fanconi anemia phenotypic spectrum. Identifying KO subjects displaying expected phenotypes suggests that the lack of correct genetic diagnoses may lead to inappropriate and delayed treatment. In contrast, the presence of HKOs with phenotypes deviating from the expected patterns underlines how LoF variants may be responsible for broader phenotypic spectra. Overall, these results highlight the importance of in-depth phenotypical characterization to understand the role of LoF variants and the advantage of studying these variants in genetic isolates.
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Affiliation(s)
- Beatrice Spedicati
- grid.5133.40000 0001 1941 4308Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Massimiliano Cocca
- grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Roberto Palmisano
- grid.5133.40000 0001 1941 4308Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Flavio Faletra
- grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Caterina Barbieri
- grid.18887.3e0000000417581884Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milan, Italy
| | - Margherita Francescatto
- grid.5133.40000 0001 1941 4308Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
| | - Massimo Mezzavilla
- grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Anna Morgan
- grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Giulia Pelliccione
- grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Paolo Gasparini
- grid.5133.40000 0001 1941 4308Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy ,grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
| | - Giorgia Girotto
- grid.5133.40000 0001 1941 4308Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy ,grid.418712.90000 0004 1760 7415Institute for Maternal and Child Health – I.R.C.C.S. “Burlo Garofolo”, Trieste, Italy
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17
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Tkatchenko TV, Tkatchenko AV. Genetic network regulating visual acuity makes limited contribution to visually guided eye emmetropization. Genomics 2021; 113:2780-2792. [PMID: 34147636 DOI: 10.1016/j.ygeno.2021.06.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/25/2021] [Accepted: 06/14/2021] [Indexed: 12/13/2022]
Abstract
During postnatal development, the eye undergoes a refinement process whereby optical defocus guides eye growth towards sharp vision in a process of emmetropization. Optical defocus activates a signaling cascade originating in the retina and propagating across the back of the eye to the sclera. Several observations suggest that visual acuity might be important for optical defocus detection and processing in the retina; however, direct experimental evidence supporting or refuting the role of visual acuity in refractive eye development is lacking. Here, we used genome-wide transcriptomics to determine the relative contribution of the retinal genetic network regulating visual acuity to the signaling cascade underlying visually guided eye emmetropization. Our results provide evidence that visual acuity is regulated at the level of molecular signaling in the retina by an extensive genetic network. The genetic network regulating visual acuity makes relatively small contribution to the signaling cascade underlying refractive eye development. This genetic network primarily affects baseline refractive eye development and this influence is primarily facilitated by the biological processes related to melatonin signaling, nitric oxide signaling, phototransduction, synaptic transmission, and dopamine signaling. We also observed that the visual-acuity-related genes associated with the development of human myopia are chiefly involved in light perception and phototransduction. Our results suggest that the visual-acuity-related genetic network primarily contributes to the signaling underlying baseline refractive eye development, whereas its impact on visually guided eye emmetropization is modest.
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Affiliation(s)
| | - Andrei V Tkatchenko
- Department of Ophthalmology, Columbia University, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY, USA.
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18
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Tkatchenko TV, Tkatchenko AV. Genome-wide analysis of retinal transcriptome reveals common genetic network underlying perception of contrast and optical defocus detection. BMC Med Genomics 2021; 14:153. [PMID: 34107987 PMCID: PMC8190860 DOI: 10.1186/s12920-021-01005-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/04/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Refractive eye development is regulated by optical defocus in a process of emmetropization. Excessive exposure to negative optical defocus often leads to the development of myopia. However, it is still largely unknown how optical defocus is detected by the retina. METHODS Here, we used genome-wide RNA-sequencing to conduct analysis of the retinal gene expression network underlying contrast perception and refractive eye development. RESULTS We report that the genetic network subserving contrast perception plays an important role in optical defocus detection and emmetropization. Our results demonstrate an interaction between contrast perception, the retinal circadian clock pathway and the signaling pathway underlying optical defocus detection. We also observe that the relative majority of genes causing human myopia are involved in the processing of optical defocus. CONCLUSIONS Together, our results support the hypothesis that optical defocus is perceived by the retina using contrast as a proxy and provide new insights into molecular signaling underlying refractive eye development.
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Affiliation(s)
| | - Andrei V. Tkatchenko
- Department of Ophthalmology, Columbia University, New York, NY USA
- Department of Pathology and Cell Biology, Columbia University, New York, NY USA
- Edward S. Harkness Eye Institute, Research Annex Room 415, 635 W. 165th Street, New York, NY 10032 USA
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19
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Kumar V, Goel N, Bhaskaran UK, Garg I. Mizuo‐Nakamura phenomenon in cone‐rod dystrophy. Clin Exp Optom 2021; 100:388-391. [DOI: 10.1111/cxo.12491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 07/23/2016] [Accepted: 08/30/2016] [Indexed: 11/29/2022] Open
Affiliation(s)
- Vinod Kumar
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,
| | - Neha Goel
- ICARE Eye Hospital and Postgraduate Institute, Noida, Uttar Pradesh, India,
| | - Ullattil K Bhaskaran
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,
| | - Itika Garg
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India,
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20
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Leahy KE, Wright T, Grudzinska Pechhacker MK, Audo I, Tumber A, Tavares E, MacDonald H, Locke J, VandenHoven C, Zeitz C, Heon E, Buncic JR, Vincent A. Optic Atrophy and Inner Retinal Thinning in CACNA1F-related Congenital Stationary Night Blindness. Genes (Basel) 2021; 12:genes12030330. [PMID: 33668843 PMCID: PMC7996180 DOI: 10.3390/genes12030330] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/06/2021] [Accepted: 02/20/2021] [Indexed: 12/25/2022] Open
Abstract
Hemizygous pathogenic variants in CACNA1F lead to defective signal transmission from retinal photoreceptors to bipolar cells and cause incomplete congenital stationary night blindness in humans. Although the primary defect is at the terminal end of first-order neurons (photoreceptors), there is limited knowledge of higher-order neuronal changes (inner retinal) in this disorder. This study aimed to investigate inner retinal changes in CACNA1F-retinopathy by analyzing macular ganglion cell layer-inner plexiform layer (GCL-IPL) thickness and optic disc pallor in 22 subjects with molecularly confirmed CACNA1F-retinopathy. Detailed ocular phenotypic data including distance and color vision, refraction and electroretinogram (ERG) were collected. Distance vision was universally reduced (mean: 0.42 LogMAR), six had abnormal color vision and myopia was common (n = 15; mean: −6.32 diopters). Mean GCL-IPL thickness was significantly lower in patients (55.00 µm) compared to age-matched controls (n = 87; 84.57 µm; p << 0.001). The GCL-IPL thickness correlated with scotopic standard (p = 0.04) and bright-flash (p = 0.014) ERG b/a ratios and photopic b-wave amplitudes (p = 0.05). Twenty-one patients had some degree of disc pallor (bilateral in 19). Fifteen putative disease-causing, including five novel variants were identified. This study establishes macular inner retinal thinning and optic atrophy as characteristic features of CACNA1F-retinopathy, which are independent of myopia and could impact potential future treatment strategies.
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Affiliation(s)
- Kate E Leahy
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
| | - Tom Wright
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
- Kensington Eye Institute, Toronto, ON M5T 3A9, Canada
| | - Monika K Grudzinska Pechhacker
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
| | - Isabelle Audo
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, 75012 Paris, France; (I.A.); (C.Z.)
- CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC 1423, 75012 Paris, France
- Institute of Ophthalmology, University College of London, London EC1V 9EL, UK
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
| | - Erika Tavares
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
| | - Heather MacDonald
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Genetic Counselling, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Jeff Locke
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
| | - Cynthia VandenHoven
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
| | - Christina Zeitz
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, 75012 Paris, France; (I.A.); (C.Z.)
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
| | - J Raymond Buncic
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; (K.E.L.); (M.K.G.P.); (A.T.); (H.M.); (J.L.); (C.V.); (E.H.); (J.R.B.)
- Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada;
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada;
- Correspondence: ; Tel.: +1-416-813-1500
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21
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Zang J, Neuhauss SCF. Biochemistry and physiology of zebrafish photoreceptors. Pflugers Arch 2021; 473:1569-1585. [PMID: 33598728 PMCID: PMC8370914 DOI: 10.1007/s00424-021-02528-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 02/06/2023]
Abstract
All vertebrates share a canonical retina with light-sensitive photoreceptors in the outer retina. These photoreceptors are of two kinds: rods and cones, adapted to low and bright light conditions, respectively. They both show a peculiar morphology, with long outer segments, comprised of ordered stacks of disc-shaped membranes. These discs host numerous proteins, many of which contribute to the visual transduction cascade. This pathway converts the light stimulus into a biological signal, ultimately modulating synaptic transmission. Recently, the zebrafish (Danio rerio) has gained popularity for studying the function of vertebrate photoreceptors. In this review, we introduce this model system and its contribution to our understanding of photoreception with a focus on the cone visual transduction cascade.
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Affiliation(s)
- Jingjing Zang
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland
| | - Stephan C F Neuhauss
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrase 190, CH - 8057, Zürich, Switzerland.
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22
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Poulter JA, Gravett MSC, Taylor RL, Fujinami K, De Zaeytijd J, Bellingham J, Rehman AU, Hayashi T, Kondo M, Rehman A, Ansar M, Donnelly D, Toomes C, Ali M, De Baere E, Leroy BP, Davies NP, Henderson RH, Webster AR, Rivolta C, Zeitz C, Mahroo OA, Arno G, Black GCM, McKibbin M, Harris SA, Khan KN, Inglehearn CF. New variants and in silico analyses in GRK1 associated Oguchi disease. Hum Mutat 2021; 42:164-176. [PMID: 33252155 PMCID: PMC7898643 DOI: 10.1002/humu.24140] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 09/15/2020] [Accepted: 11/05/2020] [Indexed: 12/16/2022]
Abstract
Biallelic mutations in G-Protein coupled receptor kinase 1 (GRK1) cause Oguchi disease, a rare subtype of congenital stationary night blindness (CSNB). The purpose of this study was to identify disease causing GRK1 variants and use in-depth bioinformatic analyses to evaluate how their impact on protein structure could lead to pathogenicity. Patients' genomic DNA was sequenced by whole genome, whole exome or focused exome sequencing. Disease associated variants, published and novel, were compared to nondisease associated missense variants. The impact of GRK1 missense variants at the protein level were then predicted using a series of computational tools. We identified twelve previously unpublished cases with biallelic disease associated GRK1 variants, including eight novel variants, and reviewed all GRK1 disease associated variants. Further structure-based scoring revealed a hotspot for missense variants in the kinase domain. In addition, to aid future clinical interpretation, we identified the bioinformatics tools best able to differentiate disease associated from nondisease associated variants. We identified GRK1 variants in Oguchi disease patients and investigated how disease-causing variants may impede protein function in-silico.
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Affiliation(s)
- James A. Poulter
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | | | - Rachel L. Taylor
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicines and HealthUniversity of ManchesterManchesterUK
| | - Kaoru Fujinami
- National Institute of Sensory Organs, National Hospital Organization Tokyo Medical CentreTokyoJapan
- Moorfields Eye HospitalLondonUK
- UCL Institute of OphthalmologyLondonUK
- Keio University School of MedicineTokyoJapan
| | | | | | - Atta Ur Rehman
- Division of Genetic Medicine, Centre Hospitalier Universitaire Vaudois (CHUV)University of LausanneLausanneSwitzerland
| | | | - Mineo Kondo
- Mie University Graduate School of MedicineMieJapan
| | - Abdur Rehman
- Department of Genetics, Faculty of ScienceHazara University MansehraDhodialPakistan
| | - Muhammad Ansar
- Clinical Research Center, Institute of Molecular and Clinical Ophthalmology Basel (IOB)BaselSwitzerland
| | - Dan Donnelly
- School of Biomedical Sciences, University of LeedsLeedsUK
| | - Carmel Toomes
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | - Manir Ali
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
| | | | | | - Bart P. Leroy
- Ghent UniversityGhentBelgium
- Children's Hospital of PhiladelphiaPhiladelphiaPennsylvaniaUSA
| | | | | | - Andrew R. Webster
- Moorfields Eye HospitalLondonUK
- UCL Institute of OphthalmologyLondonUK
| | - Carlo Rivolta
- Department of Genetics and Genome BiologyUniversity of LeicesterLeicesterUK
- Clinical Research Center, Institute of Molecular and Clinical Ophthalmology Basel (IOB)BaselSwitzerland
- Department of OphthalmologyUniversity Hospital BaselBaselSwitzerland
| | - Christina Zeitz
- Sorbonne UniversitéINSERM, CNRS, Institut de la VisionParisFrance
| | - Omar A. Mahroo
- Moorfields Eye HospitalLondonUK
- UCL Institute of OphthalmologyLondonUK
| | - Gavin Arno
- National Institute of Sensory Organs, National Hospital Organization Tokyo Medical CentreTokyoJapan
- Moorfields Eye HospitalLondonUK
- UCL Institute of OphthalmologyLondonUK
| | - Graeme C. M. Black
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicines and HealthUniversity of ManchesterManchesterUK
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation TrustManchesterUK
| | - Martin McKibbin
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
- Leeds Teaching Hospitals NHS Trust, St James’ University HospitalLeedsUK
| | | | - Kamron N. Khan
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
- Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University NHS Foundation TrustManchesterUK
| | - Chris F. Inglehearn
- Division of Molecular Medicine, Leeds Institute of Medical ResearchUniversity of LeedsLeedsUK
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Zhang Q, Xu Z, Lai Y. An Empirical Bayes approach for the identification of long-range chromosomal interaction from Hi-C data. Stat Appl Genet Mol Biol 2021; 20:1-15. [PMID: 33544558 DOI: 10.1515/sagmb-2020-0026] [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: 04/23/2020] [Accepted: 01/06/2021] [Indexed: 11/15/2022]
Abstract
Hi-C experiments have become very popular for studying the 3D genome structure in recent years. Identification of long-range chromosomal interaction, i.e., peak detection, is crucial for Hi-C data analysis. But it remains a challenging task due to the inherent high dimensionality, sparsity and the over-dispersion of the Hi-C count data matrix. We propose EBHiC, an empirical Bayes approach for peak detection from Hi-C data. The proposed framework provides flexible over-dispersion modeling by explicitly including the "true" interaction intensities as latent variables. To implement the proposed peak identification method (via the empirical Bayes test), we estimate the overall distributions of the observed counts semiparametrically using a Smoothed Expectation Maximization algorithm, and the empirical null based on the zero assumption. We conducted extensive simulations to validate and evaluate the performance of our proposed approach and applied it to real datasets. Our results suggest that EBHiC can identify better peaks in terms of accuracy, biological interpretability, and the consistency across biological replicates. The source code is available on Github (https://github.com/QiZhangStat/EBHiC).
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Affiliation(s)
- Qi Zhang
- Department of Mathematics and Statistics, University of New Hampshire, Durham, NH03824, USA
| | - Zheng Xu
- Department of Mathematics and Statistics, Wright State University, Dayton, OH45435, USA
| | - Yutong Lai
- ClinChoice, Fort Washington, PA19034, USA
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Suwanmajo T, Ramesh V, Krishnan J. Exploring cyclic networks of multisite modification reveals origins of information processing characteristics. Sci Rep 2020; 10:16542. [PMID: 33024185 PMCID: PMC7539153 DOI: 10.1038/s41598-020-73045-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 09/07/2020] [Indexed: 12/20/2022] Open
Abstract
Multisite phosphorylation (and generally multisite modification) is a basic way of encoding substrate function and circuits/networks of post-translational modifications (PTM) are ubiquitous in cell signalling. The information processing characteristics of PTM systems are a focal point of broad interest. The ordering of modifications is a key aspect of multisite modification, and a broad synthesis of the impact of ordering of modifications is still missing. We focus on a basic class of multisite modification circuits: the cyclic mechanism, which corresponds to the same ordering of phosphorylation and dephosphorylation, and examine multiple variants involving common/separate kinases and common/separate phosphatases. This is of interest both because it is encountered in concrete cellular contexts, and because it serves as a bridge between ordered (sequential) mechanisms (representing one type of ordering) and random mechanisms (which have no ordering). We show that bistability and biphasic dose response curves of the maximally modified phosphoform are ruled out for basic structural reasons independent of parameters, while oscillations can result with even just one shared enzyme. We then examine the effect of relaxing some basic assumptions about the ordering of modification. We show computationally and analytically how bistability, biphasic responses and oscillations can be generated by minimal augmentations to the cyclic mechanism even when these augmentations involved reactions operating in the unsaturated limit. All in all, using this approach we demonstrate (1) how the cyclic mechanism (with single augmentations) represents a modification circuit using minimal ingredients (in terms of shared enzymes and sequestration of enzymes) to generate bistability and oscillations, when compared to other mechanisms, (2) new design principles for rationally designing PTM systems for a variety of behaviour, (3) a basis and a necessary step for understanding the origins and robustness of behaviour observed in basic multisite modification systems.
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Affiliation(s)
- Thapanar Suwanmajo
- Center of Excellence in Materials Science and Technology, Chiang Mai University, Chiang Mai, 50200, Thailand
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Vaidhiswaran Ramesh
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London, SW7 2AZ, UK
| | - J Krishnan
- Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, London, SW7 2AZ, UK.
- Institute for Systems and Synthetic Biology, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
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Oguchi disease caused by a homozygous novel SAG splicing alteration associated with the multiple evanescent white dot syndrome: A 15-month follow-up. Doc Ophthalmol 2020; 141:217-226. [DOI: 10.1007/s10633-020-09766-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 03/31/2020] [Indexed: 10/24/2022]
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Ballios BG, Weisbrod D, Kohly R, Muni RH, Wright T, Yan P. Wide-field true-colour imaging and clinical characterization of a novel GRK1 mutation in Oguchi disease. Doc Ophthalmol 2020; 141:181-185. [DOI: 10.1007/s10633-020-09759-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 02/18/2020] [Indexed: 10/24/2022]
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Kubota D, Oishi N, Gocho K, Kikuchi S, Yamaki K, Igarashi T, Takahashi H, Ishida N, Iwata T, Mizota A, Kameya S. Novel homozygous in-frame deletion of GNAT1 gene causes golden appearance of fundus and reduced scotopic ERGs similar to that in Oguchi disease in Japanese family. Ophthalmic Genet 2019; 40:480-487. [PMID: 31696758 DOI: 10.1080/13816810.2019.1686159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: The GNAT1 gene encodes the alpha-subunit of transducin in rod photoreceptors and is an important part of the phototransduction cascade. Defects in GNAT1 are very rare but have been identified in autosomal dominant and recessive congenital stationary night blindness (CSNB) and autosomal recessive rod-cone dystrophy. The purpose of this study was to determine the phenotype-genotype relationship in a non-consanguineous Japanese family with a GNAT1 mutation.Methods: Detailed ophthalmic examinations were performed on the patients and their family members. Whole exome sequencing (WES) was applied to the DNA obtained from the family members. Sanger sequencing and co-segregation analyses were performed to identify the most likely pathogenic variant.Results: Two female (13- and 11-years) and one male (15-years) patients from a family had night blindness from their childhood. The fundus had a mild golden appearance regardless of the state of light- or dark-adaptation. Electroretinographic (ERG) analyses showed that the scotopic a-wave was extinguished, and the mixed rod-cone responses were severely reduced with an electronegative form in patients. The shapes of the dark-adapted ERGs were similar to those recorded from patients with Oguchi disease. We identified a homozygous in-frame deletion c.818_820delAGA, p.Lys273del in the GNAT1 gene. Variants were verified by Sanger sequencing and co-segregated with the disease in five members of the family.Conclusions: Our findings indicate that a recessive GNAT1 mutation found in this family could be the cause of the golden appearance of the fundus and negative ERGs with reduced a-waves, and nearly absent b-waves in the mixed rod-cone ERGs.
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Affiliation(s)
- Daiki Kubota
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
| | - Noriko Oishi
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
| | - Kiyoko Gocho
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
| | - Sachiko Kikuchi
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
| | - Kunihiko Yamaki
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
| | - Tsutomu Igarashi
- Department of Ophthalmology, Nippon Medical School, Tokyo, Japan
| | | | | | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, Tokyo, Japan
| | - Atsushi Mizota
- Department of Ophthalmology, Teikyo University School of Medicine, Tokyo, Japan
| | - Shuhei Kameya
- Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Inzai, Chiba, Japan
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Colombo L, Abeshi A, Maltese PE, Frecer V, Miertuš J, Cerra D, Bertelli M, Rossetti L. Oguchi type I caused by a homozygous missense variation in the SAG gene. Eur J Med Genet 2019; 62:103548. [DOI: 10.1016/j.ejmg.2018.09.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 08/28/2018] [Accepted: 09/26/2018] [Indexed: 12/22/2022]
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Nishiguchi KM, Ikeda Y, Fujita K, Kunikata H, Akiho M, Hashimoto K, Hosono K, Kurata K, Koyanagi Y, Akiyama M, Suzuki T, Kawasaki R, Wada Y, Hotta Y, Sonoda KH, Murakami A, Nakazawa M, Nakazawa T, Abe T. Phenotypic Features of Oguchi Disease and Retinitis Pigmentosa in Patients with S-Antigen Mutations: A Long-Term Follow-up Study. Ophthalmology 2019; 126:1557-1566. [PMID: 31257036 DOI: 10.1016/j.ophtha.2019.05.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/20/2019] [Accepted: 05/24/2019] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To present phenotypic features of 22 patients with S-antigen (SAG) mutations. DESIGN Retrospective cohort study. PARTICIPANTS Twenty-one Japanese patients from 16 families with a homozygous c.924delA mutation and 1 patient with a homozygous c.636delT mutation in the SAG gene. METHODS Clinical records on symptoms; best-corrected visual acuity; and Goldmann perimetry, fundus photography, fundus autofluorescence (FAF), OCT, and electroretinography results were reviewed. MAIN OUTCOME MEASURES Best-corrected visual acuity, Goldmann perimetry results, imaging findings, and electroretinography results. RESULTS Ten patients had Oguchi disease and 12 had retinitis pigmentosa (RP) with mean follow-up periods of 13.8 and 10.2 years, respectively. Retinitis pigmentosa patients were older (mean age, 56.0 years) than those with Oguchi disease (mean age, 22.1 years; P < 0.001) at the initial visit. Night blindness noted in childhood was the most common initial symptom for both Oguchi disease (80.0%) and RP (91.7%) patients. Best-corrected visual acuity in the logarithm of the minimum angle of resolution (logMAR) was well preserved in Oguchi disease patients (mean, 0.02 logMAR in both eyes) but reduced in most RP patients (mean, 1.32 logMAR [right eye] and 1.35 logMAR [left eye]). Similarly, the visual field in the retinal area was preserved in Oguchi disease patients (mean, 677 mm2 right eye and 667 mm2 left eye) and reduced in RP patients (mean, 369 mm2 right eye and 294 mm2 left eye). Fundus images revealed a characteristic golden sheen with no retinal degeneration in Oguchi disease patients, excluding 2 with macular degeneration detected by FAF, OCT, or both and 1 with mild retinal degeneration confirmed by OCT and fluorescein angiography. Pigmentary retinal degeneration most evident posteriorly was observed in RP patients, accompanied by a characteristic golden sheen in 12 of 14 patients undergoing ultra-widefield fundus imaging. OCT showed disrupted macular structure, and FAF revealed variable hypofluorescence. Electroretinography identified absent rod responses in both diseases, along with relative preservation of cone responses in Oguchi disease patients. Three patients showed progressive loss of the golden sheen based on fundus images, including 1 who demonstrated RP 26 years after the initial diagnosis of Oguchi disease. CONCLUSIONS Retinitis pigmentosa with SAG mutations often shows a characteristic golden sheen surrounding posterior pigmentary retinal degeneration. Oguchi disease can show progressive degeneration in adulthood, rarely resulting in RP.
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Affiliation(s)
- Koji M Nishiguchi
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | - Yasuhiro Ikeda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Kosuke Fujita
- Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroshi Kunikata
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Makoto Akiho
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kazuki Hashimoto
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Katsuhiro Hosono
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kentaro Kurata
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yoshito Koyanagi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masato Akiyama
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | - Ryo Kawasaki
- Department of Ophthalmology, Yamagata University School of Medicine, Yamagata, Japan
| | | | - Yoshihiro Hotta
- Department of Ophthalmology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University Faculty of Medicine, Tokyo, Japan
| | - Mitsuru Nakazawa
- Department of Ophthalmology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Toru Nakazawa
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Ophthalmic Imaging and Information Analytics, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Toshiaki Abe
- Division of Clinical Cell Therapy, Center for Translational and Advanced Animal Research, Tohoku University Graduate School of Medicine, Sendai, Japan
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Shi L, Mu C, Gao T, Chai W, Sheng A, Chen T, Yang J, Zhu X, Li G. Rhodopsin-Like Ionic Gate Fabricated with Graphene Oxide and Isomeric DNA Switch for Efficient Photocontrol of Ion Transport. J Am Chem Soc 2019; 141:8239-8243. [DOI: 10.1021/jacs.9b01759] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Liu Shi
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China
| | - Chaoli Mu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China
| | - Tao Gao
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, P.R. China
| | - Wenxin Chai
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China
| | - Anzhi Sheng
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Tianshu Chen
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Jie Yang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China
| | - Xiaoli Zhu
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
| | - Genxi Li
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210023, P.R. China
- Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai 200444, P.R. China
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31
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Haider RS, Wilhelm F, Rizk A, Mutt E, Deupi X, Peterhans C, Mühle J, Berger P, Schertler GFX, Standfuss J, Ostermaier MK. Arrestin-1 engineering facilitates complex stabilization with native rhodopsin. Sci Rep 2019; 9:439. [PMID: 30679635 PMCID: PMC6346018 DOI: 10.1038/s41598-018-36881-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 11/23/2018] [Indexed: 01/14/2023] Open
Abstract
Arrestin-1 desensitizes the activated and phosphorylated photoreceptor rhodopsin by forming transient rhodopsin−arrestin-1 complexes that eventually decay to opsin, retinal and arrestin-1. Via a multi-dimensional screening setup, we identified and combined arrestin-1 mutants that form lasting complexes with light-activated and phosphorylated rhodopsin in harsh conditions, such as high ionic salt concentration. Two quadruple mutants, D303A + T304A + E341A + F375A and R171A + T304A + E341A + F375A share similar heterologous expression and thermo-stability levels with wild type (WT) arrestin-1, but are able to stabilize complexes with rhodopsin with more than seven times higher half-maximal inhibitory concentration (IC50) values for NaCl compared to the WT arrestin-1 protein. These quadruple mutants are also characterized by higher binding affinities to phosphorylated rhodopsin, light-activated rhodopsin and phosphorylated opsin, as compared with WT arrestin-1. Furthermore, the assessed arrestin-1 mutants are still specifically associating with phosphorylated or light-activated receptor states only, while binding to the inactive ground state of the receptor is not significantly altered. Additionally, we propose a novel functionality for R171 in stabilizing the inactive arrestin-1 conformation as well as the rhodopsin–arrestin-1 complex. The achieved stabilization of the active rhodopsin–arrestin-1 complex might be of great interest for future structure determination, antibody development studies as well as drug-screening efforts targeting G protein-coupled receptors (GPCRs).
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Affiliation(s)
- Raphael S Haider
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland.,Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland.,Institute of Molecular Cell Biology, Jena, 07745, Germany
| | - Florian Wilhelm
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland
| | - Aurélien Rizk
- InterAx Biotech AG, PARK InnovAARE, Villigen, 5234, Switzerland
| | - Eshita Mutt
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Xavier Deupi
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Christian Peterhans
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Jonas Mühle
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Philipp Berger
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
| | - Gebhard F X Schertler
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland.,ETH Zurich, Zurich, 8093, Switzerland
| | - Jörg Standfuss
- Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen, 5232, Switzerland
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Chrispell JD, Dong E, Osawa S, Liu J, Cameron DJ, Weiss ER. Grk1b and Grk7a Both Contribute to the Recovery of the Isolated Cone Photoresponse in Larval Zebrafish. Invest Ophthalmol Vis Sci 2018; 59:5116-5124. [PMID: 30372740 PMCID: PMC6203174 DOI: 10.1167/iovs.18-24455] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 09/06/2018] [Indexed: 12/14/2022] Open
Abstract
Purpose To define the functional roles of Grk1 and Grk7 in zebrafish cones in vivo. Methods Genome editing was used to generate grk7a and grk1b knockout zebrafish. Electroretinogram (ERG) analyses of the isolated cone mass receptor potential and the b-wave were performed in dark-adapted zebrafish using a paired flash paradigm to determine recovery of cone photoreceptors and the inner retina after an initial flash. In addition, psychophysical visual response was measured using the optokinetic response (OKR). Results ERG analysis demonstrated that deletion of either Grk1b or Grk7a in zebrafish larvae resulted in modestly lower rates of recovery of the isolated cone mass receptor potential from an initial flash compared to wildtype larvae. On the other hand, grk1b-/- and grk7a-/- larvae exhibited a b-wave recovery that was similar to wildtype larvae. We evaluated the OKR and found that deletion of either Grk1b or Grk7a leads to a small decrease in temporal contrast sensitivity and alterations in visual acuity. Conclusions For the first time, we demonstrate that Grk1b and Grk7a both contribute to visual function in larval zebrafish cones. Since the difference between wildtype and each knockout fish is modest, it appears that either GRK is sufficient for adequate cone visual function.
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Affiliation(s)
- Jared D. Chrispell
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | - Enheng Dong
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | - Shoji Osawa
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | - Jiandong Liu
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | - D. Joshua Cameron
- College of Optometry, Western University of Health Sciences, Pomona, California, United States
| | - Ellen R. Weiss
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
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Yu S, Sun L, Jiao Y, Lee LTO. The Role of G Protein-coupled Receptor Kinases in Cancer. Int J Biol Sci 2018; 14:189-203. [PMID: 29483837 PMCID: PMC5821040 DOI: 10.7150/ijbs.22896] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/17/2017] [Indexed: 01/14/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest family of plasma membrane receptors. Emerging evidence demonstrates that signaling through GPCRs affects numerous aspects of cancer biology such as vascular remolding, invasion, and migration. Therefore, development of GPCR-targeted drugs could provide a new therapeutic strategy to treating a variety of cancers. G protein-coupled receptor kinases (GRKs) modulate GPCR signaling by interacting with the ligand-activated GPCR and phosphorylating its intracellular domain. This phosphorylation initiates receptor desensitization and internalization, which inhibits downstream signaling pathways related to cancer progression. GRKs can also regulate non-GPCR substrates, resulting in the modulation of a different set of pathophysiological pathways. In this review, we will discuss the role of GRKs in modulating cell signaling and cancer progression, as well as the therapeutic potential of targeting GRKs.
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Affiliation(s)
- Shan Yu
- Centre of Reproduction Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
| | - Litao Sun
- Department of Ultrasound, The Secondary Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yufei Jiao
- Department of Pathology, The Secondary Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Leo Tsz On Lee
- Centre of Reproduction Development and Aging, Faculty of Health Sciences, University of Macau, Taipa, Macau
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Bujakowska KM, Liu Q, Pierce EA. Photoreceptor Cilia and Retinal Ciliopathies. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028274. [PMID: 28289063 DOI: 10.1101/cshperspect.a028274] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
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Affiliation(s)
- Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Qin Liu
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
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Abstract
Glaucoma is characterized by a slow and progressive degeneration of the optic nerve, including retinal ganglion cell (RGC) axons in the optic nerve head (ONH), leading to visual impairment. Despite its high prevalence, the biological basis of glaucoma pathogenesis still is not yet fully understood, and the factors contributing to its progression are currently not well characterized. Intraocular pressure (IOP) is the only modifiable risk factor, and reduction of IOP is the standard treatment for glaucoma. However, lowering IOP itself is not always effective for preserving visual function in patients with primary open-angle glaucoma. The second messenger cyclic adenosine 3′,5′-monophosphate (cAMP) regulates numerous biological processes in the central nervous system including the retina and the optic nerve. Although recent studies revealed that cAMP generated by adenylyl cyclases (ACs) is important in regulating aqueous humor dynamics in ocular tissues, such as the ciliary body and trabecular meshwork, as well as cell death and growth in the retina and optic nerve, the functional role and significance of cAMP in glaucoma remain to be elucidated. In this review, we will discuss the functional role of cAMP in aqueous humor dynamics and IOP regulation, and review the current medications, which are related to the cAMP signaling pathway, for glaucoma treatment. Also, we will further focus on cAMP signaling in RGC growth and regeneration by soluble AC as well as ONH astrocytes by transmembrane ACs to understand its potential role in the pathogenesis of glaucoma neurodegeneration
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Affiliation(s)
- Myoung Sup Shim
- Hamilton Glaucoma Center and Department of Ophthalmology, Shiley Eye Institute, University of California San Diego, La Jolla, CA 92037, USA
| | - Keun-Young Kim
- Center for Research on Biological Systems, National Center for Microscopy and Imaging Research and Department of Neuroscience, University of California San Diego, La Jolla 92093, CA 92093, USA
| | - Won-Kyu Ju
- Hamilton Glaucoma Center and Department of Ophthalmology, Shiley Eye Institute, University of California San Diego, La Jolla, CA 92037, USA
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36
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Broadgate S, Yu J, Downes SM, Halford S. Unravelling the genetics of inherited retinal dystrophies: Past, present and future. Prog Retin Eye Res 2017; 59:53-96. [PMID: 28363849 DOI: 10.1016/j.preteyeres.2017.03.003] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
Abstract
The identification of the genes underlying monogenic diseases has been of interest to clinicians and scientists for many years. Using inherited retinal dystrophies as an example of monogenic disease we describe the history of molecular genetic techniques that have been pivotal in the discovery of disease causing genes. The methods that were developed in the 1970's and 80's are still in use today but have been refined and improved. These techniques enabled the concept of the Human Genome Project to be envisaged and ultimately realised. When the successful conclusion of the project was announced in 2003 many new tools and, as importantly, many collaborations had been developed that facilitated a rapid identification of disease genes. In the post-human genome project era advances in computing power and the clever use of the properties of DNA replication has allowed the development of next-generation sequencing technologies. These methods have revolutionised the identification of disease genes because for the first time there is no need to define the position of the gene in the genome. The use of next generation sequencing in a diagnostic setting has allowed many more patients with an inherited retinal dystrophy to obtain a molecular diagnosis for their disease. The identification of novel genes that have a role in the development or maintenance of retinal function is opening up avenues of research which will lead to the development of new pharmacological and gene therapy approaches. Neither of which can be used unless the defective gene and protein is known. The continued development of sequencing technologies also holds great promise for the advent of truly personalised medicine.
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Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
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Dutta N, Seo S. RPGR, a prenylated retinal ciliopathy protein, is targeted to cilia in a prenylation- and PDE6D-dependent manner. Biol Open 2016; 5:1283-9. [PMID: 27493202 PMCID: PMC5051646 DOI: 10.1242/bio.020461] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
RPGR (retinitis pigmentosa GTPase regulator) is a ciliary protein associated with several forms of inherited retinal degenerative diseases. PDE6D is a ubiquitously expressed prenyl-binding protein and involved in ciliary targeting of prenylated proteins. The current working model for the RPGR function depicts that RPGR acts as a scaffold protein to recruit cargo-loaded PDE6D to primary cilia. Here, we present evidence demonstrating an alternative relationship between RPGR and PDE6D, in which RPGR is a cargo of PDE6D for ciliary targeting. We found that the constitutive isoform of RPGR, which is prenylated, requires prenylation for its ciliary localization. We also found that there are at least two independent ciliary targeting signals in RPGR: one within the N-terminal region that contains the RCC1-like domain and the other near the prenylation site at the C-terminus. Ablation of PDE6D blocked ciliary targeting of RPGR. Our study indicates that prenylated RPGR is one of the cargos of PDE6D for ciliary trafficking and provides insight into the mechanisms by which RPGR is targeted to cilia. Summary: RPGR is a ciliary protein that functions as a scaffold to recruit cargo-loaded PDE6D to cilia. Our study shows that RPGR is also a cargo of PDE6D.
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Affiliation(s)
- Nirmal Dutta
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, IA 52242, USA
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, University of Iowa College of Medicine, Iowa City, IA 52242, USA
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Teke MY, Citirik M, Kabacam S, Demircan S, Alikasifoglu M. A novel missense mutation of the GRK1 gene in Oguchi disease. Mol Med Rep 2016; 14:3129-33. [PMID: 27511724 PMCID: PMC5042745 DOI: 10.3892/mmr.2016.5620] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 07/01/2016] [Indexed: 11/06/2022] Open
Abstract
Oguchi disease is a rare form of congenital stationary night blindness with an autosomal recessive inheritance pattern. The presence of S‑antigen (SAG) and G‑protein‑dependent receptor kinase 1 (GRK1) mutations were investigated in the family members with Oguchi disease. All exons of the SAG and GRK1 genes were amplified by polymerase chain reaction and sequenced. The patients were shown to have characteristic clinical features of Oguchi disease. Gene analysis determined a novel GRK1 mutation c.923T>C, which caused Oguchi disease in all siblings. This mutation, was demonstrated by amino acid alignment analysis to be in a phylogenetically conserved region and resulted in an amino acid change from leucine to proline at position 308. Thus, the present study reports a novel missense mutation of GRK1 in the affected members of a consanguineous Turkish family. Homozygosity at position 308, which resides in the catalytic domain of the GRK1 gene, is the cause of Oguchi disease in this Turkish family.
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Affiliation(s)
- Mehmet Yasin Teke
- SB Ankara Ulucanlar Eye Education and Research Hospital, Ankara 06230, Turkey
| | - Mehmet Citirik
- SB Ankara Ulucanlar Eye Education and Research Hospital, Ankara 06230, Turkey
| | - Serkan Kabacam
- Department of Medical Genetics, Hacettepe University, School of Medicine, Ankara 06230, Turkey
| | - Suleyman Demircan
- SB Ankara Ulucanlar Eye Education and Research Hospital, Ankara 06230, Turkey
| | - Mehmet Alikasifoglu
- Department of Medical Genetics, Hacettepe University, School of Medicine, Ankara 06230, Turkey
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Charette JR, Samuels IS, Yu M, Stone L, Hicks W, Shi LY, Krebs MP, Naggert JK, Nishina PM, Peachey NS. A Chemical Mutagenesis Screen Identifies Mouse Models with ERG Defects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:177-83. [PMID: 26427409 PMCID: PMC6716159 DOI: 10.1007/978-3-319-17121-0_24] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mouse models provide important resources for many areas of vision research, pertaining to retinal development, retinal function and retinal disease. The Translational Vision Research Models (TVRM) program uses chemical mutagenesis to generate new mouse models for vision research. In this chapter, we report the identification of mouse models for Grm1, Grk1 and Lrit3. Each of these is characterized by a primary defect in the electroretinogram. All are available without restriction to the research community.
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Affiliation(s)
| | - Ivy S Samuels
- Louis Stokes Cleveland VA Medical Center, 44106, Cleveland, OH, USA.
| | - Minzhong Yu
- Cole Eye Institute, Cleveland Clinic, 44195, Cleveland, OH, USA.
| | - Lisa Stone
- The Jackson Laboratory, 04609, Bar Harbor, ME, USA.
| | - Wanda Hicks
- The Jackson Laboratory, 04609, Bar Harbor, ME, USA.
| | - Lan Ying Shi
- The Jackson Laboratory, 04609, Bar Harbor, ME, USA.
| | - Mark P Krebs
- The Jackson Laboratory, 04609, Bar Harbor, ME, USA.
| | | | | | - Neal S Peachey
- Louis Stokes Cleveland VA Medical Center, 44106, Cleveland, OH, USA.
- Cole Eye Institute, Cleveland Clinic, 44195, Cleveland, OH, USA.
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA.
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“Barcode” and Differential Effects of GPCR Phosphorylation by Different GRKs. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2016. [DOI: 10.1007/978-1-4939-3798-1_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Simunovic MP. Acquired color vision deficiency. Surv Ophthalmol 2015; 61:132-55. [PMID: 26656928 DOI: 10.1016/j.survophthal.2015.11.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 11/06/2015] [Accepted: 11/11/2015] [Indexed: 02/02/2023]
Abstract
Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.
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Affiliation(s)
- Matthew P Simunovic
- Nuffield Laboratory of Ophthalmology, University of Oxford & Oxford Eye Hospital, University of Oxford NHS Trust, West Wing, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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Veleri S, Lazar CH, Chang B, Sieving PA, Banin E, Swaroop A. Biology and therapy of inherited retinal degenerative disease: insights from mouse models. Dis Model Mech 2015; 8:109-29. [PMID: 25650393 PMCID: PMC4314777 DOI: 10.1242/dmm.017913] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Retinal neurodegeneration associated with the dysfunction or death of photoreceptors is a major cause of incurable vision loss. Tremendous progress has been made over the last two decades in discovering genes and genetic defects that lead to retinal diseases. The primary focus has now shifted to uncovering disease mechanisms and designing treatment strategies, especially inspired by the successful application of gene therapy in some forms of congenital blindness in humans. Both spontaneous and laboratory-generated mouse mutants have been valuable for providing fundamental insights into normal retinal development and for deciphering disease pathology. Here, we provide a review of mouse models of human retinal degeneration, with a primary focus on diseases affecting photoreceptor function. We also describe models associated with retinal pigment epithelium dysfunction or synaptic abnormalities. Furthermore, we highlight the crucial role of mouse models in elucidating retinal and photoreceptor biology in health and disease, and in the assessment of novel therapeutic modalities, including gene- and stem-cell-based therapies, for retinal degenerative diseases.
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Affiliation(s)
- Shobi Veleri
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Csilla H Lazar
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. Molecular Biology Center, Interdisciplinary Research Institute on Bio-Nano Sciences, Babes-Bolyai-University, Cluj-Napoca, 400271, Romania
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Paul A Sieving
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Eyal Banin
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA. Center for Retinal and Macular Degenerations, Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem 91120, Israel
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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Vinberg F, Wang T, Molday RS, Chen J, Kefalov VJ. A new mouse model for stationary night blindness with mutant Slc24a1 explains the pathophysiology of the associated human disease. Hum Mol Genet 2015; 24:5915-29. [PMID: 26246500 DOI: 10.1093/hmg/ddv319] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 07/31/2015] [Indexed: 11/12/2022] Open
Abstract
Mutations that affect calcium homeostasis (Ca(2+)) in rod photoreceptors are linked to retinal degeneration and visual disorders such as retinitis pigmentosa and congenital stationary night blindness (CSNB). It is thought that the concentration of Ca(2+) in rod outer segments is controlled by a dynamic balance between influx via cGMP-gated (CNG) channels and extrusion via Na(+)/Ca(2+), K(+) exchangers (NCKX1). The extrusion-driven lowering of rod [Ca(2+)]i following light exposure controls their light adaptation and response termination. Mutant NCKX1 has been linked to autosomal-recessive stationary night blindness. However, whether NCKX1 contributes to light adaptation has not been directly tested and the mechanisms by which human NCKX1 mutations cause night blindness are not understood. Here, we report that the deletion of NCKX1 in mice results in malformed outer segment disks, suppressed expression and function of rod CNG channels and a subsequent 100-fold reduction in rod responses, while preserving normal cone responses. The compensating loss of CNG channel function in the absence of NCKX1-mediated Ca(2+) extrusion may prevent toxic Ca(2+) buildup and provides an explanation for the stationary nature of the associated disorder in humans. Surprisingly, the lack of NCKX1 did not compromise rod background light adaptation, suggesting additional Ca(2+)-extruding mechanisms exist in these cells.
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Affiliation(s)
- Frans Vinberg
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Tian Wang
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Robert S Molday
- Biochemistry/Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Jeannie Chen
- Cell and Neurobiology, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA, USA and
| | - Vladimir J Kefalov
- Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA,
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Liu F, Chen J, Yu S, Raghupathy RK, Liu X, Qin Y, Li C, Huang M, Liao S, Wang J, Zou J, Shu X, Tang Z, Liu M. Knockout of RP2 decreases GRK1 and rod transducin subunits and leads to photoreceptor degeneration in zebrafish. Hum Mol Genet 2015; 24:4648-59. [PMID: 26034134 DOI: 10.1093/hmg/ddv197] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 05/26/2015] [Indexed: 12/14/2022] Open
Abstract
Retinitis pigmentosa (RP) affects about 1.8 million individuals worldwide. X-linked retinitis pigmentosa (XLRP) is one of the most severe forms of RP. Nearly 85% of XLRP cases are caused by mutations in the X-linked retinitis pigmentosa 2 (RP2) and RPGR. RP2 has been considered to be a GTPase activator protein for ARL3 and to play a role in the traffic of ciliary proteins. The mechanism of how RP2 mutations cause RP is still unclear. In this study, we generated an RP2 knockout zebrafish line using transcription activator-like effector nuclease technology. Progressive retinal degeneration could be observed in the mutant zebrafish. The degeneration of rods' outer segments (OSs) is predominant, followed by the degeneration of cones' OS. These phenotypes are similar to the characteristics of RP2 patients, and also partly consistent with the phenotypes of RP2 knockout mice and morpholino-mediated RP2 knockdown zebrafish. For the first time, we found RP2 deletion leads to decreased protein levels and abnormal retinal localizations of GRK1 and rod transducin subunits (GNAT1 and GNB1) in zebrafish. Furthermore, the distribution of the total farnesylated proteins in zebrafish retina is also affected by RP2 ablation. These molecular alterations observed in the RP2 knockout zebrafish might probably be responsible for the gradual loss of the photoreceptors' OSs. Our work identified the progression of retinal degeneration in RP2 knockout zebrafish, provided a foundation for revealing the pathogenesis of RP caused by RP2 mutations, and would help to develop potential therapeutics against RP in further studies.
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Affiliation(s)
- Fei Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Jiaxiang Chen
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Shanshan Yu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | | | - Xiliang Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Yayun Qin
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Chang Li
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Mi Huang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Shengjie Liao
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Jiuxiang Wang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China
| | - Jian Zou
- Institute of Translational Medicine, Zhejiang University, 268 Kaixuan Road, Zhongxin Beilou, Hangzhou, 310029 Zhejiang, PR China
| | - Xinhua Shu
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK and and
| | - Zhaohui Tang
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China,
| | - Mugen Liu
- Key Laboratory of Molecular Biophysics of Ministry of Education, Department of Genetics and Developmental Biology, College of Life Science and Technology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei 430074, PR China,
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Nash BM, Wright DC, Grigg JR, Bennetts B, Jamieson RV. Retinal dystrophies, genomic applications in diagnosis and prospects for therapy. Transl Pediatr 2015; 4:139-63. [PMID: 26835369 PMCID: PMC4729094 DOI: 10.3978/j.issn.2224-4336.2015.04.03] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Retinal dystrophies (RDs) are degenerative diseases of the retina which have marked clinical and genetic heterogeneity. Common presentations among these disorders include night or colour blindness, tunnel vision and subsequent progression to complete blindness. The known causative disease genes have a variety of developmental and functional roles with mutations in more than 120 genes shown to be responsible for the phenotypes. In addition, mutations within the same gene have been shown to cause different disease phenotypes, even amongst affected individuals within the same family highlighting further levels of complexity. The known disease genes encode proteins involved in retinal cellular structures, phototransduction, the visual cycle, and photoreceptor structure or gene regulation. This review aims to demonstrate the high degree of genetic complexity in both the causative disease genes and their associated phenotypes, highlighting the more common clinical manifestation of retinitis pigmentosa (RP). The review also provides insight to recent advances in genomic molecular diagnosis and gene and cell-based therapies for the RDs.
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Affiliation(s)
- Benjamin M Nash
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Dale C Wright
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - John R Grigg
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Bruce Bennetts
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Robyn V Jamieson
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
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Brennenstuhl C, Tanimoto N, Burkard M, Wagner R, Bolz S, Trifunovic D, Kabagema-Bilan C, Paquet-Durand F, Beck SC, Huber G, Seeliger MW, Ruth P, Wissinger B, Lukowski R. Targeted ablation of the Pde6h gene in mice reveals cross-species differences in cone and rod phototransduction protein isoform inventory. J Biol Chem 2015; 290:10242-55. [PMID: 25739440 DOI: 10.1074/jbc.m114.611921] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Indexed: 11/06/2022] Open
Abstract
Phosphodiesterase-6 (PDE6) is a multisubunit enzyme that plays a key role in the visual transduction cascade in rod and cone photoreceptors. Each type of photoreceptor utilizes discrete catalytic and inhibitory PDE6 subunits to fulfill its physiological tasks, i.e. the degradation of cyclic guanosine-3',5'-monophosphate at specifically tuned rates and kinetics. Recently, the human PDE6H gene was identified as a novel locus for autosomal recessive (incomplete) color blindness. However, the three different classes of cones were not affected to the same extent. Short wave cone function was more preserved than middle and long wave cone function indicating that some basic regulation of the PDE6 multisubunit enzyme was maintained albeit by a unknown mechanism. To study normal and disease-related functions of cone Pde6h in vivo, we generated Pde6h knock-out (Pde6h(-/-)) mice. Expression of PDE6H in murine eyes was restricted to both outer segments and synaptic terminals of short and long/middle cone photoreceptors, whereas Pde6h(-/-) retinae remained PDE6H-negative. Combined in vivo assessment of retinal morphology with histomorphological analyses revealed a normal overall integrity of the retinal organization and an unaltered distribution of the different cone photoreceptor subtypes upon Pde6h ablation. In contrast to human patients, our electroretinographic examinations of Pde6h(-/-) mice suggest no defects in cone/rod-driven retinal signaling and therefore preserved visual functions. To this end, we were able to demonstrate the presence of rod PDE6G in cones indicating functional substitution of PDE6. The disparities between human and murine phenotypes caused by mutant Pde6h/PDE6H suggest species-to-species differences in the vulnerability of biochemical and neurosensory pathways of the visual signal transduction system.
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Affiliation(s)
- Christina Brennenstuhl
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | - Markus Burkard
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | - Rebecca Wagner
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | | | - Clement Kabagema-Bilan
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | | | | | | | | | - Peter Ruth
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy
| | - Bernd Wissinger
- the Molecular Genetics Laboratory, Centre for Ophthalmology, University of Tuebingen, 72076 Tuebingen, Germany
| | - Robert Lukowski
- From the Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy,
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48
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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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Christiansen JR, Ramamurthy V. Greasing the protein biosynthesis machinery of photoreceptor neurons: Role for postprenylation processing of proteins. CELLULAR LOGISTICS 2014; 2:15-19. [PMID: 22645706 PMCID: PMC3355970 DOI: 10.4161/cl.19804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Daily phagocytosis of outer segments (OS) places extraordinary demands on protein biosynthesis and trafficking in photoreceptor neurons. While the members and roles of the phototransduction pathway in the OS are well characterized, details about protein trafficking are just beginning to emerge. Phosphodiesterase6 (PDE6), the effector enzyme in phototransduction cascade, serves as an example of the steps multimeric proteins must pass through to achieve their functional state in the OS. Genetic model systems have recently provided snapshots of various steps in the pathway, as experimental difficulties such as an inability to maintain ciliated photoreceptor outer segments or express functional PDE6 holoenzyme in vitro necessitate in vivo studies. We will highlight the significant findings, their implications to blinding diseases, as well as discuss the gaps requiring further investigation.
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50
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Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
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