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Aljammal R, Saravanan T, Guan T, Rhodes S, Robichaux MA, Ramamurthy V. Excessive tubulin glutamylation leads to progressive cone-rod dystrophy and loss of outer segment integrity. Hum Mol Genet 2024; 33:802-817. [PMID: 38297980 DOI: 10.1093/hmg/ddae013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/29/2023] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
Mutations in Cytosolic Carboxypeptidase-like Protein 5 (CCP5) are associated with vision loss in humans. To decipher the mechanisms behind CCP5-associated blindness, we generated a novel mouse model lacking CCP5. In this model, we found that increased tubulin glutamylation led to progressive cone-rod dystrophy, with cones showing a more pronounced and earlier functional loss than rod photoreceptors. The observed functional reduction was not due to cell death, levels, or the mislocalization of major phototransduction proteins. Instead, the increased tubulin glutamylation caused shortened photoreceptor axonemes and the formation of numerous abnormal membranous whorls that disrupted the integrity of photoreceptor outer segments (OS). Ultimately, excessive tubulin glutamylation led to the progressive loss of photoreceptors, affecting cones more severely than rods. Our results highlight the importance of maintaining tubulin glutamylation for normal photoreceptor function. Furthermore, we demonstrate that murine cone photoreceptors are more sensitive to disrupted tubulin glutamylation levels than rods, suggesting an essential role for axoneme in the structural integrity of the cone outer segment. This study provides valuable insights into the mechanisms of photoreceptor diseases linked to excessive tubulin glutamylation.
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Affiliation(s)
- Rawaa Aljammal
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Thamaraiselvi Saravanan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Tongju Guan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Scott Rhodes
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Michael A Robichaux
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Visvanathan Ramamurthy
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
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2
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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. FASEB J 2024; 38:e23522. [PMID: 38445789 PMCID: PMC10949407 DOI: 10.1096/fj.202302491r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 02/07/2024] [Accepted: 02/16/2024] [Indexed: 03/07/2024]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (APOB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic depletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor-associated cholesterol deposits, and photoreceptor cell death, and loss of rod but not cone function. RPE-specific reduction in Mttp had no significant effect on plasma lipids and lipoproteins. While APOB was decreased in the RPE, most ocular retinoids remained unchanged, with the exception of the storage form of retinoid, retinyl ester. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but is not directly involved in plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY, 10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Neissi M, Sheikh‐Hosseini M, Mohammadi‐Asl J. Retinitis pigmentosa-1 due to an RP1 mutation in a consanguineous Iranian family: Report of a novel mutation. Clin Case Rep 2024; 12:e8666. [PMID: 38487646 PMCID: PMC10940001 DOI: 10.1002/ccr3.8666] [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: 12/06/2023] [Revised: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 03/17/2024] Open
Abstract
Key Clinical Message The identification of a novel RP1 gene mutation highlights the importance of precise variant identification for retinitis pigmentosa prognosis and genetic consultations, emphasizing comprehensive genetic analysis for personalized care. Abstract Our study unveils a noteworthy association between retinitis pigmentosa-1 and a newly discovered homozygous mutation (c.5326delC; p.Asp1777Ilefs*32) within the RP1 gene. This highlights the crucial role of accurate variant identification in not only informing prognosis but also improving genetic consultations and influencing future diagnostic approaches for individuals affected by retinitis pigmentosa.
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Affiliation(s)
- Mostafa Neissi
- Department of GeneticsKhuzestan Science and Research Branch, Islamic Azad UniversityAhvazIran
- Department of GeneticsAhvaz Branch, Islamic Azad UniversityAhvazIran
- Noor‐Gene Genetic LaboratoryAhvazIran
| | - Motahareh Sheikh‐Hosseini
- Noor‐Gene Genetic LaboratoryAhvazIran
- Pediatric Cell & Gene Therapy Research CenterTehran University of Medical SciencesTehranIran
| | - Javad Mohammadi‐Asl
- Noor‐Gene Genetic LaboratoryAhvazIran
- Department of Medical Genetics, School of MedicineAhvaz Jundishapur University of Medical SciencesAhvazIran
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4
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Grubaugh CR, Dhingra A, Prakash B, Montenegro D, Sparrow JR, Daniele LL, Curcio CA, Bell BA, Hussain MM, Boesze-Battaglia K. Microsomal triglyceride transfer protein is necessary to maintain lipid homeostasis and retinal function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570418. [PMID: 38105975 PMCID: PMC10723417 DOI: 10.1101/2023.12.06.570418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Lipid processing by the retinal pigment epithelium (RPE) is necessary to maintain retinal health and function. Dysregulation of retinal lipid homeostasis due to normal aging or to age-related disease triggers lipid accumulation within the RPE, on Bruch's membrane (BrM), and in the subretinal space. In its role as a hub for lipid trafficking into and out of the neural retina, the RPE packages a significant amount of lipid into lipid droplets for storage and into apolipoprotein B (apoB)-containing lipoproteins (Blps) for export. Microsomal triglyceride transfer protein (MTP), encoded by the MTTP gene, is essential for Blp assembly. Herein we test the hypothesis that MTP expression in the RPE is essential to maintain lipid balance and retinal function using the newly generated RPEΔMttp mouse model. Using non-invasive ocular imaging, electroretinography, and histochemical and biochemical analyses we show that genetic deletion of Mttp from the RPE results in intracellular lipid accumulation, increased photoreceptor -associated cholesterol deposits and photoreceptor cell death, and loss of rod but not cone function. RPE-specific ablation of Mttp had no significant effect on plasma lipids and lipoproteins. While, apoB was decreased in the RPE, ocular retinoid concentrations remained unchanged. Thus suggesting that RPE MTP is critical for Blp synthesis and assembly but not directly involved in ocular retinoid and plasma lipoprotein metabolism. These studies demonstrate that RPE-specific MTP expression is necessary to establish and maintain retinal lipid homeostasis and visual function.
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Affiliation(s)
- Catharina R. Grubaugh
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Anuradha Dhingra
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Binu Prakash
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Diego Montenegro
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Janet R. Sparrow
- Department of Ophthalmology and Department of Pathology and Cell Biology, Columbia University, New York, NY,10027 USA
| | - Lauren L. Daniele
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Christine A. Curcio
- Department of Ophthalmology and Visual Sciences, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Brent A. Bell
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, PA, 19104 USA
| | - M. Mahmood Hussain
- Department of Foundations of Medicine, New York University Grossman Long Island School of Medicine, Mineola, NY, 11501 USA
| | - Kathleen Boesze-Battaglia
- Department of Basic and Translational Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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Daich Varela M, Georgiadis A, Michaelides M. Genetic treatment for autosomal dominant inherited retinal dystrophies: approaches, challenges and targeted genotypes. Br J Ophthalmol 2023; 107:1223-1230. [PMID: 36038193 DOI: 10.1136/bjo-2022-321903] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 08/01/2022] [Indexed: 11/04/2022]
Abstract
Inherited retinal diseases (IRDs) have been in the front line of gene therapy development for the last decade, providing a useful platform to test novel therapeutic approaches. More than 40 clinical trials have been completed or are ongoing, tackling autosomal recessive and X-linked conditions, mostly through adeno-associated viral vector delivery of a normal copy of the disease-causing gene. However, only recently has autosomal dominant (ad) disease been targeted, with the commencement of a trial for rhodopsin (RHO)-associated retinitis pigmentosa (RP), implementing antisense oligonucleotide (AON) therapy, with promising preliminary results (NCT04123626).Autosomal dominant RP represents 15%-25% of all RP, with RHO accounting for 20%-30% of these cases. Autosomal dominant macular and cone-rod dystrophies (MD/CORD) correspond to approximately 7.5% of all IRDs, and approximately 35% of all MD/CORD cases, with the main causative gene being BEST1 Autosomal dominant IRDs are not only less frequent than recessive, but also tend to be less severe and have later onset; for example, an individual with RHO-adRP would typically become severely visually impaired at an age 2-3 times older than in X-linked RPGR-RP.Gain-of-function and dominant negative aetiologies are frequently seen in the prevalent adRP genes RHO, RP1 and PRPF31 among others, which would not be effectively addressed by gene supplementation alone and need creative, novel approaches. Zinc fingers, RNA interference, AON, translational read-through therapy, and gene editing by clustered regularly interspaced short palindromic repeats/Cas are some of the strategies that are currently under investigation and will be discussed here.
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Affiliation(s)
- Malena Daich Varela
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
| | | | - Michel Michaelides
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
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Tebbe L, Mwoyosvi ML, Crane R, Makia MS, Kakakhel M, Cosgrove D, Al-Ubaidi MR, Naash MI. The usherin mutation c.2299delG leads to its mislocalization and disrupts interactions with whirlin and VLGR1. Nat Commun 2023; 14:972. [PMID: 36810733 PMCID: PMC9944904 DOI: 10.1038/s41467-023-36431-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 02/01/2023] [Indexed: 02/24/2023] Open
Abstract
Usher syndrome (USH) is the leading cause of combined deafness-blindness with type 2 A (USH2A) being the most common form. Knockout models of USH proteins, like the Ush2a-/- model that develops a late-onset retinal phenotype, failed to mimic the retinal phenotype observed in patients. Since patient's mutations result in the expression of a mutant protein and to determine the mechanism of USH2A, we generated and evaluated an usherin (USH2A) knock-in mouse expressing the common human disease-mutation, c.2299delG. This mouse exhibits retinal degeneration and expresses a truncated, glycosylated protein which is mislocalized to the photoreceptor inner segment. The degeneration is associated with a decline in retinal function, structural abnormalities in connecting cilium and outer segment and mislocaliztion of the usherin interactors very long G-protein receptor 1 and whirlin. The onset of symptoms is significantly earlier compared to Ush2a-/-, proving expression of mutated protein is required to recapitulate the patients' retinal phenotype.
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Affiliation(s)
- Lars Tebbe
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Maggie L Mwoyosvi
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
- Department of Microbiology & Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Ryan Crane
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Mustafa S Makia
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | - Mashal Kakakhel
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA
| | | | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA.
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, 77204, USA.
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Naggert ASEN, Collin GB, Wang J, Krebs MP, Chang B. A mouse model of cone photoreceptor function loss (cpfl9) with degeneration due to a mutation in Gucy2e. Front Mol Neurosci 2023; 15:1080136. [PMID: 36698779 PMCID: PMC9868315 DOI: 10.3389/fnmol.2022.1080136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 12/15/2022] [Indexed: 01/11/2023] Open
Abstract
During routine screening of mouse strains and stocks by the Eye Mutant Resource at The Jackson Laboratory for genetic mouse models of human ocular disorders, we identified cpfl9, a mouse model with cone photoreceptor function loss. The mice exhibited an early-onset phenotype that was easily recognized by the absence of a cone-mediated b-wave electroretinography response and by a reduction in rod-mediated photoresponses at four weeks of age. By genetic mapping and high-throughput sequencing of a whole exome capture library of cpfl9, a homozygous 25 bp deletion within exon 11 of the Gucy2e gene was identified, which is predicted to result in a frame shift leading to premature termination. The corresponding protein in human, retinal guanylate cyclase 1 (GUCY2D), plays an important role in rod and cone photoreceptor cell function. Loss-of-function mutations in human GUCY2D cause LCA1, one of the most common forms of Leber congenital amaurosis, which results in blindness at birth or in early childhood. The early loss of cone and reduced rod photoreceptor cell function in the cpfl9 mutant is accompanied by a later, progressive loss of cone and rod photoreceptor cells, which may be relevant to understanding disease pathology in a subset of LCA1 patients and in individuals with cone-rod dystrophy caused by recessive GUCY2D variants. cpfl9 mice will be useful for studying the role of Gucy2e in the retina.
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Jaffal L, Ibrahim M, El Shamieh S. Analysis of rod-cone dystrophy genes reveals unique mutational patterns. BMJ OPEN SCIENCE 2022; 6:e100291. [PMID: 36618607 PMCID: PMC9812813 DOI: 10.1136/bmjos-2022-100291] [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: 03/08/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Background Rod-cone dystrophy (RCD) is the most common inherited retinal disease that is characterised by the progressive degeneration of retinal photoreceptors. RCD genes classification is based exclusively on gene mutations' prevalence and does not consider the implication of the same gene in different phenotypes. Therefore, we first investigated the mutations occurrence in autosomal recessive RCD (arRCD) and non-arRCD conditions. Then, finally, we identified arRCD enriched mutational patterns in specific genes and coding exons. Methods and results The mutations patterns differed according to arRCD (p=0.001). Specifically, When compared with missense; insertions/deletions (OR=1.2, p=0.007), nonsense (OR=1.2, p=0.014) and splice-site mutations (OR=1.6, p=0.038) increased the OR of arRCD by 20%-60% versus non-arRCD conditions. The gene-based analysis identified that EYS, IMPG2, RP1L1 and USH2A mutations were enriched in arRCD (p<0.05). The exon-based analysis revealed specific mutation patterns in exons of CRB1, RP1L1 and exons 12, 60 and 62 coding for Lamin EGF and FTIII domains of USH2A. Conclusion The current analysis showed that many aRCD genes have unique mutational patterns.
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Affiliation(s)
- Lama Jaffal
- Department of Biological and Chemical Sciences, School of Arts and Sciences, Lebanese International University, Nabatyeh, Lebanon,Rammal Hassan Rammal Research Laboratory, PhyToxE Research Group, Faculty of Sciences, Lebanese University, Nabatyeh, Lebanon
| | - Mariam Ibrahim
- Rammal Hassan Rammal Research Laboratory, PhyToxE Research Group, Faculty of Sciences, Lebanese University, Nabatyeh, Lebanon
| | - Said El Shamieh
- Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, Beirut, Lebanon
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Buckley TM, Cehajic-Kapetanovic J, Shanks M, Clouston P, MacLaren RE. Compound dominant-null heterozygosity in a family with RP1-related retinal dystrophy. Am J Ophthalmol Case Rep 2022; 28:101698. [PMID: 36393903 PMCID: PMC9650022 DOI: 10.1016/j.ajoc.2022.101698] [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: 06/22/2022] [Revised: 08/15/2022] [Accepted: 09/01/2022] [Indexed: 11/20/2022] Open
Abstract
Purpose To report on the presence of autosomal dominant and compound dominant-null RP1-related retinitis pigmentosa in the same non-consanguineous family. Observation The father was minimally symptomatic and referred by his optometrist aged 38. He was diagnosed with rod-cone dystrophy, confirmed to be caused by the previously reported RP1 c.2613dupA mutation. He was reassured that his 11-year-old daughter had a 50% chance of inheriting the same mutation and that the condition, if she had it, would most likely be similar. Clinical phenotyping of his daughter however revealed an early onset cone-rod dystrophy. The mother was entirely asymptomatic and clinically normal. Sanger sequencing of the RP1 gene in the daughter confirmed the presence of biallelic mutations - the dominant c.2613dupA variant from her father and a c.3843dupT truncating variant inherited from her mother, both located in exon 4 of the RP1 gene. The maternal c.3843dupT has previously been reported. Conclusions and importance Pathogenic variants in exon 4 of RP1 are known to cause differential dominant and recessive disease. The presence of both phenotypes in a single family has not yet been reported. The father, being minimally symptomatic, is affected by a known dominant variant which truncates the RP1 protein more proximally. However, inheritance of both variants in a compound heterozygous state in the daughter resulted in a much more severe, early onset cone-rod phenotype in a pattern akin to recessive disease. This raises challenges for genetic counselling and development of gene-based therapies for RP1 mutations.
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Affiliation(s)
- Thomas M.W. Buckley
- Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Headley Way, OX3 9DU, UK
| | | | - Morag Shanks
- Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Headley Way, OX3 9DU, UK
| | - Penny Clouston
- Oxford University Hospitals NHS Foundation Trust, John Radcliffe Hospital, Headley Way, OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Level 6, West Wing, John Radcliffe Hospital, Headley Way, OX3 9DU, UK
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Liu Y, Chen J, Sager R, Sasaki E, Hu H. Interactions between C8orf37 and FAM161A, Two Ciliary Proteins Essential for Photoreceptor Survival. Int J Mol Sci 2022; 23:12033. [PMID: 36233334 PMCID: PMC9570145 DOI: 10.3390/ijms231912033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/17/2022] Open
Abstract
Mutations in C8orf37 cause Bardet-Biedl syndrome (BBS), retinitis pigmentosa (RP), and cone-rod dystrophy (CRD), all manifest in photoreceptor degeneration. Little is known about which proteins C8orf37 interacts with to contribute to photoreceptor survival. To determine the proteins that potentially interact with C8orf37, we carried out a yeast two-hybrid (Y2H) screen using C8orf37 as a bait. FAM161A, a microtubule-binding protein localized at the photoreceptor cilium required for photoreceptor survival, was identified as one of the preys. Double immunofluorescence staining and proximity ligation assay (PLA) of marmoset retinal sections showed that C8orf37 was enriched and was co-localized with FAM161A at the ciliary base of photoreceptors. Epitope-tagged C8orf37 and FAM161A, expressed in HEK293 cells, were also found to be co-localized by double immunofluorescence staining and PLA. Furthermore, interaction domain mapping assays identified that the N-terminal region of C8orf37 and amino acid residues 341-517 within the PFAM UPF0564 domain of FAM161A were critical for C8orf37-FAM161A interaction. These data suggest that the two photoreceptor survival proteins, C8orf37 and FAM161A, interact with each other which may contribute to photoreceptor health.
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Affiliation(s)
- Yu Liu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY 13210, USA
| | - Jinjun Chen
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY 13210, USA
- College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Rachel Sager
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY 13210, USA
| | - Erika Sasaki
- Department of Marmoset Biology and Medicine, Central Institute for Experimental Animals, Tonomachi, Kawasaki 210-0821, Kanagawa, Japan
| | - Huaiyu Hu
- Center for Vision Research, Departments of Neuroscience and Physiology and of Ophthalmology and Visual Sciences, Upstate Medical University, Syracuse, NY 13210, USA
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Retinal Ciliopathy in the Patient with Transplanted Kidney: Case Report. Int J Mol Sci 2022; 23:ijms23147582. [PMID: 35886928 PMCID: PMC9321797 DOI: 10.3390/ijms23147582] [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: 06/01/2022] [Revised: 06/26/2022] [Accepted: 07/05/2022] [Indexed: 02/05/2023] Open
Abstract
A review of a rare case of a proven mutation in the RP1 gene (RP1c.2029C>T, p. (ARG677*) in a kidney transplant patient was presented herein. According to his medical history, he had tonsillectomy performed at the age of 20 due to erythrocyturia, and at the age of 32 he was treated for malignant hypertension. The patient had been diagnosed with chronic renal failure at age 56 years. During an eye examination in 2016, retinitis pigmentosa was suspected and the patient was advised to run further tests. After an ophthalmological examination and tests, genetic testing was performed and a mutation in the RP1 gene encoding a family of proteins which are components of microtubules in photoreceptor primary cilia was proven. The literature search found that mutations in the RP1 gene have so far been exclusively associated with a non-syndromic form of retinal degeneration. However, the RP1 protein is expressed in the kidneys, and it remains unclear why the mutation of this gene so far was only specifically related to retinal photoreceptor function and not to arterial hypertension and renal disease. Primary cilia are thought to act as potential mechanosensory fluid-flow receptors in the vascular endothelium and kidney and their dysfunction results in atherosclerotic changes, hypertension, and chronic renal failure.
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12
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Knapp B, Roedig J, Roedig H, Krzysko J, Horn N, Güler BE, Kusuluri DK, Yildirim A, Boldt K, Ueffing M, Liebscher I, Wolfrum U. Affinity Proteomics Identifies Interaction Partners and Defines Novel Insights into the Function of the Adhesion GPCR VLGR1/ADGRV1. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103108. [PMID: 35630584 PMCID: PMC9146371 DOI: 10.3390/molecules27103108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 05/05/2022] [Accepted: 05/06/2022] [Indexed: 12/20/2022]
Abstract
The very large G-protein-coupled receptor 1 (VLGR1/ADGRV1) is the largest member of the adhesion G-protein-coupled receptor (ADGR) family. Mutations in VLGR1/ADGRV1 cause human Usher syndrome (USH), a form of hereditary deaf-blindness, and have been additionally linked to epilepsy. In the absence of tangible knowledge of the molecular function and signaling of VLGR1, the pathomechanisms underlying the development of these diseases are still unknown. Our study aimed to identify novel, previously unknown protein networks associated with VLGR1 in order to describe new functional cellular modules of this receptor. Using affinity proteomics, we have identified numerous new potential binding partners and ligands of VLGR1. Tandem affinity purification hits were functionally grouped based on their Gene Ontology terms and associated with functional cellular modules indicative of functions of VLGR1 in transcriptional regulation, splicing, cell cycle regulation, ciliogenesis, cell adhesion, neuronal development, and retinal maintenance. In addition, we validated the identified protein interactions and pathways in vitro and in situ. Our data provided new insights into possible functions of VLGR1, related to the development of USH and epilepsy, and also suggest a possible role in the development of other neuronal diseases such as Alzheimer’s disease.
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Affiliation(s)
- Barbara Knapp
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Jens Roedig
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Heiko Roedig
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Jacek Krzysko
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Nicola Horn
- Core Facility for Medical Bioanalytics, Institute for Ophthalmic Research, University of Tuebingen, 72076 Tuebingen, Germany; (N.H.); (K.B.); (M.U.)
| | - Baran E. Güler
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Deva Krupakar Kusuluri
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Adem Yildirim
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
| | - Karsten Boldt
- Core Facility for Medical Bioanalytics, Institute for Ophthalmic Research, University of Tuebingen, 72076 Tuebingen, Germany; (N.H.); (K.B.); (M.U.)
| | - Marius Ueffing
- Core Facility for Medical Bioanalytics, Institute for Ophthalmic Research, University of Tuebingen, 72076 Tuebingen, Germany; (N.H.); (K.B.); (M.U.)
| | - Ines Liebscher
- Rudolf Schönheimer Institute of Biochemistry, Faculty of Medicine, Leipzig University, 04103 Leipzig, Germany;
| | - Uwe Wolfrum
- Institute of Molecular Physiology (ImP), Molecular Cell Biology, Johannes Gutenberg University Mainz, 55128 Mainz, Germany; (B.K.); (J.R.); (H.R.); (J.K.); (B.E.G.); (D.K.K.); (A.Y.)
- Correspondence:
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13
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Bedoukian EC, O'Neil EC, Aleman TS. RP1-associated recessive retinitis pigmentosa caused by paternal uniparental disomy. Ophthalmic Genet 2022; 43:555-560. [PMID: 35484846 DOI: 10.1080/13816810.2022.2062389] [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: 10/18/2022]
Abstract
BACKGROUND We report on a patient with a juvenile-onset inherited retinal degeneration (IRD) associated with homozygous RP1 mutations inherited by uniparental disomy (UPD). MATERIAL AND METHODS A 6-year-old healthy girl failed school vision screening and was diagnosed with a bull's eye maculopathy. She underwent complete ophthalmic examination, full-field electroretinograms (ERG), kinetic fields, full-field sensitivity testing (FST), and retinal imaging with spectral domain optical coherence tomography (SD-OCT) and near-infrared (NIR) and short wavelength (SW) fundus autofluorescence (FAF). RESULTS Visual acuities were relatively preserved (20/30+). There was subtle foveal depigmentation but an otherwise normal fundus examination. SD-OCT revealed a relatively preserved fovea with thinning of the photoreceptor outer nuclear layer with increasing distance from the foveal center coinciding with marked attenuation of the NIR and less marked loss of the SW-FAF signal. ERGs were non-detectable. Kinetic visual fields were generally full to large (V-4e) target but constricted to ~10°of eccentricity to I-4e stimuli. Dark-adapted thresholds by FST were rod-mediated and elevated by ~2 log units. Homozygous pathogenic mutations in RP1 (c.1720_1721del; p.Ser574Asnfs*8) were identified. Family member testing revealed father and siblings to be unaffected carriers; the mother carried wild-type alleles. Further testing suggested UPD of chromosome 8. CONCLUSION This report adds support to UPD as a mechanism of inheritance in IRDs and stresses the importance of familial testing for genetic diagnosis and counseling. Consistent with earlier descriptions of autosomal recessive RP1-IRDs our patient showed an early rod and cone photoreceptor degeneration.
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Affiliation(s)
- Emma C Bedoukian
- Division of Ophthalmology, Children's Hospital of Philadelphia.,Roberts Individualized Medical Genetics Center, Children's Hospital of Philadelphia, Pennsylvania, USA
| | - Erin C O'Neil
- Division of Ophthalmology, Children's Hospital of Philadelphia.,Center for Advanced Retinal and Ocular Therapeutics
| | - Tomas S Aleman
- Division of Ophthalmology, Children's Hospital of Philadelphia.,Center for Advanced Retinal and Ocular Therapeutics.,Scheie Eye Institute at the Perelman Center for Advanced Medicine, Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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14
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Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Ciliopathies are a group of heterogeneous inherited disorders associated with dysfunction of the cilium, a ubiquitous microtubule-based organelle involved in a broad range of cellular functions. Most ciliopathies are syndromic, since several organs whose cells produce a cilium, such as the retina, cochlea or kidney, are affected by mutations in ciliary-related genes. In the retina, photoreceptor cells present a highly specialized neurosensory cilium, the outer segment, stacked with membranous disks where photoreception and phototransduction occurs. The daily renewal of the more distal disks is a unique characteristic of photoreceptor outer segments, resulting in an elevated protein demand. All components necessary for outer segment formation, maintenance and function have to be transported from the photoreceptor inner segment, where synthesis occurs, to the cilium. Therefore, efficient transport of selected proteins is critical for photoreceptor ciliogenesis and function, and any alteration in either cargo delivery to the cilium or intraciliary trafficking compromises photoreceptor survival and leads to retinal degeneration. To date, mutations in more than 100 ciliary genes have been associated with retinal dystrophies, accounting for almost 25% of these inherited rare diseases. Interestingly, not all mutations in ciliary genes that cause retinal degeneration are also involved in pleiotropic pathologies in other ciliated organs. Depending on the mutation, the same gene can cause syndromic or non-syndromic retinopathies, thus emphasizing the highly refined specialization of the photoreceptor neurosensory cilia, and raising the possibility of photoreceptor-specific molecular mechanisms underlying common ciliary functions such as ciliary transport. In this review, we will focus on ciliary transport in photoreceptor cells and discuss the molecular complexity underpinning retinal ciliopathies, with a special emphasis on ciliary genes that, when mutated, cause either syndromic or non-syndromic retinal ciliopathies.
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Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
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15
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Wang J, Xiao X, Li S, Wang P, Sun W, Zhang Q. Dominant RP in the Middle While Recessive in Both the N- and C-Terminals Due to RP1 Truncations: Confirmation, Refinement, and Questions. Front Cell Dev Biol 2021; 9:634478. [PMID: 33681214 PMCID: PMC7935555 DOI: 10.3389/fcell.2021.634478] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/19/2021] [Indexed: 11/13/2022] Open
Abstract
RP1 truncation variants, including frameshift, nonsense, and splicing, are a common cause of retinitis pigmentosa (RP). RP1 is a unique gene where truncations cause either autosomal dominant RP (adRP) or autosomal recessive RP (arRP) depending on the location of the variants. This study aims to clarify the boundaries between adRP and arRP caused by RP1 truncation variants based on a systemic analysis of 165 RP1 variants from our in-house exome-sequencing data of 7,092 individuals as well as a thorough review of 185 RP1 variants from published literature. In our cohort, potential pathogenic variants were detected in 16 families, including 11 new and five previously described families. Of the 16, seven families with adRP had heterozygous truncations in the middle portion, while nine families with either arRP (eight) or macular degeneration had biallelic variants in the N- and C-terminals, involving 10 known and seven novel variants. In the literature, 147 truncations in RP1 were reported to be responsible for either arRP (85) or adRP (58) or both (four). An overall evaluation of RP1 causative variants suggested three separate regions, i.e., the N-terminal from c.1 (p.1) to c.1837 (p.613), the middle portion from c.1981 (p.661) to c.2749 (p.917), and the C-terminal from c.2816 (p.939) to c.6471 (p.2157), where truncations in the middle portion were associated with adRP, while those in the N- and C-terminals were responsible for arRP. Heterozygous truncations alone in the N- and C- terminals were unlikely pathogenic. However, conflict reports with reverse situation were present for 13 variants, suggesting a complicated pathogenicity awaiting to be further elucidated. In addition, pathogenicity for homozygous truncations around c.5797 and thereafter might also need to be further clarified, so as for missense variants and for truncations located in the two gaps. Our data not only confirmed and refined the boundaries between dominant and recessive RP1 truncations but also revealed unsolved questions valuable for further investigation. These findings remind us that great care is needed in interpreting the results of RP1 variants in clinical gene testing as well as similar features may also be present in some other genes.
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Affiliation(s)
- Junwen Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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16
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Hermenean A, Trotta MC, Gharbia S, Hermenean AG, Peteu VE, Balta C, Cotoraci C, Gesualdo C, Rossi S, Gherghiceanu M, D'Amico M. Changes in Retinal Structure and Ultrastructure in the Aged Mice Correlate With Differences in the Expression of Selected Retinal miRNAs. Front Pharmacol 2021; 11:593514. [PMID: 33519453 PMCID: PMC7838525 DOI: 10.3389/fphar.2020.593514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/29/2020] [Indexed: 12/19/2022] Open
Abstract
Age and gender are two important factors that may influence the function and structure of the retina and its susceptibility to retinal diseases. The aim of this study was to delineate the influence that biological sex and age exert on the retinal structural and ultrastructural changes in mice and to identify the age-related miRNA dysregulation profiles in the retina by gender. Experiments were undertaken on male and female Balb/c aged 24 months (approximately 75–85 years in humans) compared to the control (3 months). The retinas were analyzed by histology, transmission electron microscopy, and age-related miRNA expression profile analysis. Retinas of both sexes showed a steady decline in retinal thickness as follows: photoreceptor (PS) and outer layers (p < 0.01 for the aged male vs. control; p < 0.05 for the aged female vs. control); the inner retinal layers were significantly affected by the aging process in the males (p < 0.01) but not in the aged females. Electron microscopy revealed more abnormalities which involve the retinal pigment epithelium (RPE) and Bruch’s membrane, outer and inner layers, vascular changes, deposits of amorphous materials, and accumulation of lipids or lipofuscins. Age-related miRNAs, miR-27a-3p (p < 0.01), miR-27b-3p (p < 0.05), and miR-20a-5p (p < 0.05) were significantly up-regulated in aged male mice compared to the controls, whereas miR-20b-5p was significantly down-regulated in aged male (p < 0.05) and female mice (p < 0.05) compared to the respective controls. miR-27a-3p (5.00 fold; p < 0.01) and miR-27b (7.58 fold; p < 0.01) were significantly up-regulated in aged male mice vs. aged female mice, whereas miR-20b-5p (−2.10 fold; p < 0.05) was significantly down-regulated in aged male mice vs. aged female mice. Interestingly, miR-27a-3p, miR-27b-3p, miR-20a-5p, and miR-20b-5p expressions significantly correlated with the thickness of the retinal PS layer (p < 0.01), retinal outer layers (p < 0.01), and Bruch’s membrane (p < 0.01). Our results showed that biological sex can influence the structure and function of the retina upon aging, suggesting that this difference may be underlined by the dysregulation of age-related mi-RNAs.
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Affiliation(s)
- Anca Hermenean
- "Aurel Ardelean" Institute of Life Sciences, Vasile Goldis Western University of Arad, Arad, Romania.,Department of Biochemistry and Molecular Biology, University of Bucharest, Bucharest, Romania
| | - Maria Consiglia Trotta
- Section of Pharmacology, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Sami Gharbia
- "Aurel Ardelean" Institute of Life Sciences, Vasile Goldis Western University of Arad, Arad, Romania.,Department of Biochemistry and Molecular Biology, University of Bucharest, Bucharest, Romania
| | | | | | - Cornel Balta
- "Aurel Ardelean" Institute of Life Sciences, Vasile Goldis Western University of Arad, Arad, Romania
| | - Coralia Cotoraci
- Faculty of Medicine, Vasile Goldis Western University of Arad, Arad, Romania
| | - Carlo Gesualdo
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Settimio Rossi
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Mihaela Gherghiceanu
- Carol Davila University of Medicine and Pharmacy, Bucharest, Romania.,Victor Babes National Institute of Pathology, Bucharest, Romania
| | - Michele D'Amico
- Section of Pharmacology, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
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17
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Progressive Photoreceptor Dysfunction and Age-Related Macular Degeneration-Like Features in rp1l1 Mutant Zebrafish. Cells 2020; 9:cells9102214. [PMID: 33007938 PMCID: PMC7600334 DOI: 10.3390/cells9102214] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/17/2020] [Accepted: 09/25/2020] [Indexed: 12/23/2022] Open
Abstract
Photoreceptor disease results in irreparable vision loss and blindness, which has a dramatic impact on quality of life. Pathogenic mutations in RP1L1 lead to photoreceptor degenerations such as occult macular dystrophy and retinitis pigmentosa. RP1L1 is a component of the photoreceptor axoneme, the backbone structure of the photoreceptor's light-sensing outer segment. We generated an rp1l1 zebrafish mutant using CRISPR/Cas9 genome editing. Mutant animals had progressive photoreceptor functional defects as determined by electrophysiological assessment. Optical coherence tomography showed gaps in the photoreceptor layer, disrupted photoreceptor mosaics, and thinner retinas. Mutant retinas had disorganized photoreceptor outer segments and lipid-rich subretinal drusenoid deposits between the photoreceptors and retinal pigment epithelium. Our mutant is a novel model of RP1L1-associated photoreceptor disease and the first zebrafish model of photoreceptor degeneration with reported subretinal drusenoid deposits, a feature of age-related macular degeneration.
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18
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Ueno S, Koyanagi Y, Kominami T, Ito Y, Kawano K, Nishiguchi KM, Rivolta C, Nakazawa T, Sonoda KH, Terasaki H. Clinical characteristics and high resolution retinal imaging of retinitis pigmentosa caused by RP1 gene variants. Jpn J Ophthalmol 2020; 64:485-496. [PMID: 32627106 DOI: 10.1007/s10384-020-00752-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 05/14/2020] [Indexed: 11/27/2022]
Abstract
PURPOSE To report the clinical course and high resolution images of autosomal recessive retinitis pigmentosa (RP) associated with a variant of the RP1 gene (c.4052_4053ins328/p.Tyr1352Alafs*9; m1), a high frequency founder variant in Japanese RP patients. STUDY DESIGN Retrospective case series. METHODS Nine patients from 5 unrelated Japanese families were studied. Five patients had the m1 variant homozygously, and 4 patients had the m1 variant compound heterozygously with another frameshift variant (c.4196delG/p.Cys1399Leufs*5). Ophthalmic examinations including adaptive optics (AO) fundus imaging were performed periodically. RESULTS The fundus photographs, fundus autofluorescence (FAF) images, and optical coherence tomographic (OCT) images indicated severe retinal degeneration in all the patients involving the macula even at a young age (20 s). The areas of surviving photoreceptors in the central macula were seen as hyper-autofluorescent regions in the FAF images and preserved outer retinal structure in the OCT images; they were identifiable in the AO fundus images in 8 eyes. The borders of the surviving photoreceptor areas were surrounded by hyporeflective clumps, presumably containing melanin, and the size of these areas decreased progressively during the 4-year follow-up period. The disappearance of the surviving photoreceptor areas was associated with complete blindness. CONCLUSION Patients with RP associated with the m1 variant have a progressive and severe retinal degeneration that begins at an early age. Monitoring the surviving photoreceptor areas by AO fundus imaging can provide a more precise pathological record of retinal degeneration.
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Affiliation(s)
- Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.
| | - Yoshito Koyanagi
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan.,Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Taro Kominami
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Yasuki Ito
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Kenichi Kawano
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Koji M Nishiguchi
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Carlo Rivolta
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), Basel, Switzerland.,University of Basel, Basel, Switzerland.,Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan
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19
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Huckfeldt RM, Grigorian F, Place E, Comander JI, Vavvas D, Young LH, Yang P, Shurygina M, Pierce EA, Pennesi ME. Biallelic RP1-associated retinal dystrophies: Expanding the mutational and clinical spectrum. Mol Vis 2020; 26:423-433. [PMID: 32565670 PMCID: PMC7300197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 06/01/2020] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To evaluate the phenotypic spectrum of autosomal recessive RP1-associated retinal dystrophies and assess genotypic associations. METHODS A retrospective multicenter study was performed of patients with biallelic RP1-associated retinal dystrophies. Data including presenting symptoms and age, visual acuity, kinetic perimetry, full field electroretinogram, fundus examination, multimodal retinal imaging, and RP1 genotype were evaluated. RESULTS Nineteen eligible patients from 17 families were identified and ranged in age from 10 to 56 years at the most recent evaluation. Ten of the 21 unique RP1 variants identified were novel, and mutations within exon 2 accounted for nearly half of alleles across the cohort. Patients had clinical diagnoses of retinitis pigmentosa (13), cone-rod dystrophy (3), Leber congenital amaurosis (1), early-onset severe retinal dystrophy (1), and macular dystrophy (1). Macular atrophy was a common feature across the cohort. Symptom onset occurred between 4 and 30 years of age (mean 14.9 years, median 13 years), but there were clusters of onset age that correlated with the effects of RP1 mutations at a protein level. Patients with later-onset disease, including retinitis pigmentosa, had at least one missense variant in an exon 2 DCX domain. CONCLUSIONS Biallelic RP1 mutations cause a broad spectrum of retinal disease. Exon 2 missense mutations are a significant contributor to disease and can be associated with a considerably later onset of retinitis pigmentosa than that typically associated with biallelic RP1 mutations.
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Affiliation(s)
- Rachel M. Huckfeldt
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Florin Grigorian
- Casey Eye Institute, Oregon Health & Science University, Portland, OR,Department of Ophthalmology, University of Arkansas School of Medicine, Little Rock, AR
| | - Emily Place
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Jason I. Comander
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Demetrios Vavvas
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Lucy H. Young
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Paul Yang
- Casey Eye Institute, Oregon Health & Science University, Portland, OR
| | - Maria Shurygina
- Casey Eye Institute, Oregon Health & Science University, Portland, OR,S.N. Fyodorov Eye Microsurgery Federal State Institution of the Russian Ministry of Health, Moscow, Russia
| | - Eric A. Pierce
- Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA
| | - Mark E. Pennesi
- Casey Eye Institute, Oregon Health & Science University, Portland, OR
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20
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Verbakel SK, van Huet RAC, den Hollander AI, Geerlings MJ, Kersten E, Klevering BJ, Klaver CCW, Plomp AS, Wesseling NL, Bergen AAB, Nikopoulos K, Rivolta C, Ikeda Y, Sonoda KH, Wada Y, Boon CJF, Nakazawa T, Hoyng CB, Nishiguchi KM. Macular Dystrophy and Cone-Rod Dystrophy Caused by Mutations in the RP1 Gene: Extending the RP1 Disease Spectrum. Invest Ophthalmol Vis Sci 2019; 60:1192-1203. [PMID: 30913292 DOI: 10.1167/iovs.18-26084] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To describe the clinical and genetic spectrum of RP1-associated retinal dystrophies. Methods In this multicenter case series, we included 22 patients with RP1-associated retinal dystrophies from 19 families from The Netherlands and Japan. Data on clinical characteristics, visual acuity, visual field, ERG, and retinal imaging were extracted from medical records over a mean follow-up of 8.1 years. Results Eleven patients were diagnosed with autosomal recessive macular dystrophy (arMD) or autosomal recessive cone-rod dystrophy (arCRD), five with autosomal recessive retinitis pigmentosa (arRP), and six with autosomal dominant RP (adRP). The mean age of onset was 40.3 years (range 14-56) in the patients with arMD/arCRD, 26.2 years (range 18-40) in adRP, and 8.8 years (range 5-12) in arRP patients. All patients with arMD/arCRD carried either the hypomorphic p.Arg1933* variant positioned close to the C-terminus (8 of 11 patients) or a missense variant in exon 2 (3 of 11 patients), compound heterozygous with a likely deleterious frameshift or nonsense mutation, or the p.Gln1916* variant. In contrast, all mutations identified in adRP and arRP patients were frameshift and/or nonsense variants located far from the C-terminus. Conclusions Mutations in the RP1 gene are associated with a broad spectrum of progressive retinal dystrophies. In addition to adRP and arRP, our study provides further evidence that arCRD and arMD are RP1-associated phenotypes as well. The macular involvement in patients with the hypomorphic RP1 variant suggests that macular function may remain compromised if expression levels of RP1 do not reach adequate levels after gene augmentation therapy.
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Affiliation(s)
- Sanne K Verbakel
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ramon A C van Huet
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Maartje J Geerlings
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eveline Kersten
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - B Jeroen Klevering
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Astrid S Plomp
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Nieneke L Wesseling
- Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Arthur A B Bergen
- Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,The Netherlands Institute for Neuroscience (NIN-KNAW), Amsterdam, The Netherlands
| | - Konstantinos Nikopoulos
- Department of Computational Biology, Unit of Medical Genetics, University of Lausanne, Lausanne, Switzerland.,Service of Medical Genetics, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Carlo Rivolta
- Department of Computational Biology, Unit of Medical Genetics, University of Lausanne, Lausanne, Switzerland.,Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Yasuhiro Ikeda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | - Camiel J F Boon
- Department of Ophthalmology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands
| | - 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
| | - Carel B Hoyng
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - 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
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21
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Nikopoulos K, Cisarova K, Quinodoz M, Koskiniemi-Kuendig H, Miyake N, Farinelli P, Rehman AU, Khan MI, Prunotto A, Akiyama M, Kamatani Y, Terao C, Miya F, Ikeda Y, Ueno S, Fuse N, Murakami A, Wada Y, Terasaki H, Sonoda KH, Ishibashi T, Kubo M, Cremers FPM, Kutalik Z, Matsumoto N, Nishiguchi KM, Nakazawa T, Rivolta C. A frequent variant in the Japanese population determines quasi-Mendelian inheritance of rare retinal ciliopathy. Nat Commun 2019; 10:2884. [PMID: 31253780 PMCID: PMC6599023 DOI: 10.1038/s41467-019-10746-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 05/23/2019] [Indexed: 12/21/2022] Open
Abstract
Hereditary retinal degenerations (HRDs) are Mendelian diseases characterized by progressive blindness and caused by ultra-rare mutations. In a genomic screen of 331 unrelated Japanese patients, we identify a disruptive Alu insertion and a nonsense variant (p.Arg1933*) in the ciliary gene RP1, neither of which are rare alleles in Japan. p.Arg1933* is almost polymorphic (frequency = 0.6%, amongst 12,000 individuals), does not cause disease in homozygosis or heterozygosis, and yet is significantly enriched in HRD patients (frequency = 2.1%, i.e., a 3.5-fold enrichment; p-value = 9.2 × 10-5). Familial co-segregation and association analyses show that p.Arg1933* can act as a Mendelian mutation in trans with the Alu insertion, but might also associate with disease in combination with two alleles in the EYS gene in a non-Mendelian pattern of heredity. Our results suggest that rare conditions such as HRDs can be paradoxically determined by relatively common variants, following a quasi-Mendelian model linking monogenic and complex inheritance.
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Affiliation(s)
- Konstantinos Nikopoulos
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
- Service of Medical Genetics, Lausanne University Hospital (CHUV), 1011, Lausanne, Switzerland
| | - Katarina Cisarova
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Mathieu Quinodoz
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Hanna Koskiniemi-Kuendig
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Noriko Miyake
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Pietro Farinelli
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Atta Ur Rehman
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Muhammad Imran Khan
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6525 GA, Nijmegen, The Netherlands
| | - Andrea Prunotto
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland
| | - Masato Akiyama
- Laboratory for Statistical Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan
| | - Yoichiro Kamatani
- Laboratory for Statistical Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan
| | - Chikashi Terao
- Laboratory for Statistical Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan
| | - Fuyuki Miya
- Department of Medical Science Mathematics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, 113-8510, Japan
| | - Yasuhiro Ikeda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Shinji Ueno
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Nobuo Fuse
- Department of Integrative Genomics, Tohoku Medical Megabank Organization, Sendai, 980-8573, Japan
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, 113-8421, Japan
| | - Yuko Wada
- Yuko Wada Eye Clinic, Sendai, 980-0011, Japan
| | - Hiroko Terasaki
- Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Koh-Hei Sonoda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Tatsuro Ishibashi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Michiaki Kubo
- RIKEN Center for Integrative Medical Sciences, Yokohama, 230-0045, Japan
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, 6500 HB, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, 6525 GA, Nijmegen, The Netherlands
| | - Zoltán Kutalik
- Institute of Social and Preventive Medicine, Lausanne University Hospital, 1011, Lausanne, Switzerland
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004, Japan
| | - Koji M Nishiguchi
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
- Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, 980-8574, Japan
| | - Carlo Rivolta
- Unit of Medical Genetics, Department of Computational Biology, University of Lausanne, 1015, Lausanne, Switzerland.
- Department of Genetics and Genome Biology, University of Leicester, Leicester, LE1 7RH, UK.
- Institute of Molecular and Clinical Ophthalmology Basel (IOB), 4031, Basel, Switzerland.
- University of Basel, 4001, Basel, Switzerland.
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22
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Nanda A, McClements ME, Clouston P, Shanks ME, MacLaren RE. The Location of Exon 4 Mutations in RP1 Raises Challenges for Genetic Counseling and Gene Therapy. Am J Ophthalmol 2019; 202:23-29. [PMID: 30731082 DOI: 10.1016/j.ajo.2019.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/05/2018] [Accepted: 01/24/2019] [Indexed: 11/25/2022]
Abstract
PURPOSE Mutations in the photoreceptor gene RP1 lead to recessive or dominantly inherited retinitis pigmentosa (RP). Since the dominantly inherited phenotype is generally milder than recessive cases, it raises the possibility that it could arise by haploinsufficiency; however, most mutations are in the terminal exon 4, which would be predicted to generate truncated proteins. We therefore assessed a cohort of RP patients with confirmed mutations in RP1 to examine the genetic basis of the exon 4 mutations. DESIGN Observational case series. METHODS A retrospective review of 15 patients, aged between 36 and 84, with RP1 mutations in exon 4 confirmed by Sanger sequencing. All patients underwent full ophthalmic examination. RESULTS Two patients had homozygous mutations in RP1, p.(Glu1526*) and p.(Ser486fs), and presented with severe early-onset retinal degeneration. Their first-degree relatives were unaffected. Thirteen patients had dominantly inherited RP presenting in adult life with a rod-cone dystrophy phenotype. Four novel mutations were identified. All mutations were predicted to produce truncated RP1 protein of variable lengths, as follows: p.(Arg677*), p.(Gln679*), p.(Leu722*), p.(Ile725Argfs*6), p.(Ser734*)x2, p.(Leu762Tyrfs*17)x2, p.(Leu866Lysfs*7)x2, p.(Arg872Thrfs*2)x2, and p.(Gln917*). CONCLUSION The RP1 protein with a predicted length between 677 and 917 amino acids seems to have a dominant negative effect, whereas proteins shorter (486 amino acids) or longer than this (1526 amino acids) lead to a more severe phenotype, but only in homozygous individuals. Since mutations at various points along exon 4 have divergent consequences, genetic testing alone may be insufficient for counseling, but recessive inheritance should be considered likely in severe early-onset cases.
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23
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Ying G, Frederick JM, Baehr W. Deletion of both centrin 2 (CETN2) and CETN3 destabilizes the distal connecting cilium of mouse photoreceptors. J Biol Chem 2019; 294:3957-3973. [PMID: 30647131 DOI: 10.1074/jbc.ra118.006371] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 01/09/2019] [Indexed: 02/03/2023] Open
Abstract
Centrins (CETN1-4) are ubiquitous and conserved EF-hand-family Ca2+-binding proteins associated with the centrosome, basal body, and transition zone. Deletion of CETN1 or CETN2 in mice causes male infertility or dysosmia, respectively, without affecting photoreceptor function. However, it remains unclear to what extent centrins are redundant with each other in photoreceptors. Here, to explore centrin redundancy, we generated Cetn3 GT/GT single-knockout and Cetn2 -/-;Cetn3 GT/GT double-knockout mice. Whereas the Cetn3 deletion alone did not affect photoreceptor function, simultaneous ablation of Cetn2 and Cetn3 resulted in attenuated scotopic and photopic electroretinography (ERG) responses in mice at 3 months of age, with nearly complete retina degeneration at 1 year. Removal of CETN2 and CETN3 activity from the lumen of the connecting cilium (CC) destabilized the photoreceptor axoneme and reduced the CC length as early as postnatal day 22 (P22). In Cetn2 -/-;Cetn3 GT/GT double-knockout mice, spermatogenesis-associated 7 (SPATA7), a key organizer of the photoreceptor-specific distal CC, was depleted gradually, and CETN1 was condensed to the mid-segment of the CC. Ultrastructural analysis revealed that in this double knockout, the axoneme of the CC expanded radially at the distal end, with vertically misaligned outer segment discs and membrane whorls. These observations suggest that CETN2 and CETN3 cooperate in stabilizing the CC/axoneme structure.
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Affiliation(s)
- Guoxin Ying
- From the Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah 84132,
| | - Jeanne M Frederick
- From the Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah 84132
| | - Wolfgang Baehr
- From the Department of Ophthalmology, University of Utah Health Science Center, Salt Lake City, Utah 84132, .,the Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah 84112, and.,the Department of Biology, University of Utah, Salt Lake City, Utah 84132
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24
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Dilan TL, Singh RK, Saravanan T, Moye A, Goldberg AFX, Stoilov P, Ramamurthy V. Bardet-Biedl syndrome-8 (BBS8) protein is crucial for the development of outer segments in photoreceptor neurons. Hum Mol Genet 2019; 27:283-294. [PMID: 29126234 DOI: 10.1093/hmg/ddx399] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 11/06/2017] [Indexed: 11/15/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is an autosomal recessive ciliopathy characterized by developmental abnormalities and vision loss. To date, mutations in 21 genes have been linked to BBS. The products of eight of these BBS genes form a stable octameric complex termed the BBSome. Mutations in BBS8, a component of the BBSome, cause early vision loss, but the role of BBS8 in supporting vision is not known. To understand the mechanisms by which BBS8 supports rod and cone photoreceptor function, we generated animal models lacking BBS8. The loss of BBS8 protein led to concomitant decrease in the levels of BBSome subunits, BBS2 and BBS5 and increase in the levels of the BBS1 and BBS4 subunits. BBS8 ablation was associated with severe reduction of rod and cone photoreceptor function and progressive degeneration of each photoreceptor subtype. We observed disorganized and shortened photoreceptor outer segments (OS) at post-natal day 10 as the OS elaborates. Interestingly, loss of BBS8 led to changes in the distribution of photoreceptor axonemal proteins and hyper-acetylation of ciliary microtubules. In contrast to properly localized phototransduction machinery, we observed OS accumulation of syntaxin3, a protein normally found in the cytoplasm and the synaptic termini. In conclusion, our studies demonstrate the requirement for BBS8 in early development and elaboration of ciliated photoreceptor OS, explaining the need for BBS8 in normal vision. The findings from our study also imply that early targeting of both rods and cones in BBS8 patients is crucial for successful restoration of vision.
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Affiliation(s)
- Tanya L Dilan
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | - Ratnesh K Singh
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | | | - Abigail Moye
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | | | - Peter Stoilov
- Biochemistry, West Virginia University, Morgantown, WA 26506, USA
| | - Visvanathan Ramamurthy
- Departments of Ophthalmology, West Virginia University, Morgantown, WA 26506, USA.,Biochemistry, West Virginia University, Morgantown, WA 26506, USA.,Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WA 26506, USA
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25
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Hanke-Gogokhia C, Chiodo VA, Hauswirth WW, Frederick JM, Baehr W. Rescue of cone function in cone-only Nphp5 knockout mouse model with Leber congenital amaurosis phenotype. Mol Vis 2018; 24:834-846. [PMID: 30713422 PMCID: PMC6334983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 12/28/2018] [Indexed: 11/09/2022] Open
Abstract
Purpose Recessive mutations in the human IQCB1/NPHP5 gene are associated with Senior-Løken syndrome (SLS), a ciliopathy presenting with nephronophthisis and Leber congenital amaurosis (LCA). Nphp5-knockout mice develop LCA without nephronophthisis. Mutant rods rapidly degenerate while mutant cones survive for months. The purpose of this study was to reinitiate cone ciliogenesis in a Nphp5 -/-; Nrl -/- mouse with viral expression of full-length NPHP5 and rescue function. Methods Nphp5 -/- mice were mated with Nrl -/- mice to generate Nphp5-/-; Nrl-/- double-knockouts. Nphp5-/-; Nrl-/- mice and Nphp5+/-; Nrl-/- controls were phenotyped with confocal microscopy from postnatal day 10 (P10) until 6 months of age. Nphp5-/-; Nrl-/- mice and Nphp5+/-; Nrl-/- controls were injected at P15 with self-complementary adenoassociated virus 8 (Y733F) (AAV8(Y733F)) expressing GRK1-FL-cNPHP5. Expression of mutant NPHP5 was verified with confocal microscopy and electroretinography (ERG). Results In the Nphp5 -/- and cone-only Nphp5 -/-; Nrl -/- mice, cone outer segments did not form, but mutant cones continued to express cone pigments in the inner segments without obvious signs of cone cell death. The mutant cone outer nuclear layer (ONL) and the inner segments were stable for more than 6 months in the cone-only Nphp5 -/-; Nrl -/- retinas. Viral expression of NPHP5 initiated after eye opening showed that connecting cilia and RP1-positive axonemes were formed. Furthermore, cone pigments and other cone outer segment proteins (cone transducin and cone PDE6) were present in the nascent mutant cone outer segments, and rescued mutant cones exhibited a significant photopic b-wave (30% of Nphp5 +/-; Nrl -/- controls). Conclusions Nphp5-/-; Nrl-/- cones persistently express cone pigments in the inner segments without obvious degeneration, providing an extended duration interval for viral gene expression. Viral expression of full-length NPHP5 initiates ciliogenesis between P15 and P60, and mutant cones are, in part, functional, encouraging future retina gene replacement therapy.
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Affiliation(s)
- Christin Hanke-Gogokhia
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah Health Science Center, Salt Lake City, UT
| | - Vince A. Chiodo
- Department of Ophthalmology, University of Florida, Gainesville, FL
| | | | - Jeanne M. Frederick
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah Health Science Center, Salt Lake City, UT
| | - Wolfgang Baehr
- Department of Ophthalmology, John A. Moran Eye Center, University of Utah Health Science Center, Salt Lake City, UT,Department of Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, UT,Department of Biology, University of Utah, Salt Lake City, UT
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26
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Li S, Yang M, Liu W, Liu Y, Zhang L, Yang Y, Sundaresan P, Yang Z, Zhu X. Targeted Next-Generation Sequencing Reveals Novel RP1 Mutations in Autosomal Recessive Retinitis Pigmentosa. Genet Test Mol Biomarkers 2018; 22:109-114. [PMID: 29425069 DOI: 10.1089/gtmb.2017.0223] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Retinitis pigmentosa (RP) is a group of rare inherited retinal dystrophies that result in a progressive loss of vision. Molecular diagnosis of RP is difficult due to its phenotypic and genetic heterogeneities. AIMS To investigate causative genetic mutations in a collection of RP cases: one Indian and two Chinese families with autosomal-recessive RP and two sporadic patients with RP. MATERIALS AND METHODS A total of 163 genes, which have previously been found to be involved in inherited retinal disorders, were selected for targeted next-generation sequencing (NGS). Stringent NGS data analyses followed by confirmation using Sanger sequencing and segregation analyses were applied to evaluate all identified pathogenic mutations. RESULTS Four novel frameshift mutations and two compound heterozygous mutations were identified in RP1. In addition, all mutations were found to co-segregate with the disease in the three familial cases; none of the mutations were detected in control samples. CONCLUSION This study expands the mutational spectrums of RP1 for RP.
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Affiliation(s)
- Shujin Li
- 1 Chengdu Institute of Biology , Chinese Academy of Sciences, Chengdu, P.R. China .,2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China .,3 University of Chinese Academy of Sciences , Beijing, P.R. China
| | - Mu Yang
- 1 Chengdu Institute of Biology , Chinese Academy of Sciences, Chengdu, P.R. China .,2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China .,3 University of Chinese Academy of Sciences , Beijing, P.R. China
| | - Wenjing Liu
- 2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China
| | - Yuqing Liu
- 2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China
| | - Lin Zhang
- 2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China
| | - Yeming Yang
- 2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China
| | - Periasamy Sundaresan
- 4 Department of Genetics, Aravind Medical Research Foundation, Aravind Eye Hospital , Madurai, Tamilnadu, India
| | - Zhenglin Yang
- 1 Chengdu Institute of Biology , Chinese Academy of Sciences, Chengdu, P.R. China .,2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China
| | - Xianjun Zhu
- 2 Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China , Chengdu, Sichuan, P.R. China .,5 Institute of Laboratory Animal Sciences , Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan, P.R. China .,6 Department of Laboratory Medicine, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Sichuan Translational Medicine Research Hospital , Chengdu, Sichuan, P.R. China
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27
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Zobor D, Zobor G, Hipp S, Baumann B, Weisschuh N, Biskup S, Sliesoraityte I, Zrenner E, Kohl S. Phenotype Variations Caused by Mutations in theRP1L1Gene in a Large Mainly German Cohort. ACTA ACUST UNITED AC 2018; 59:3041-3052. [DOI: 10.1167/iovs.18-24033] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Ditta Zobor
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Gergely Zobor
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria
| | - Stephanie Hipp
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Britta Baumann
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Nicole Weisschuh
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
| | - Saskia Biskup
- Praxis für Humangenetik Tübingen & CeGaT GmbH, Tübingen, Tübingen, Germany
| | - Ieva Sliesoraityte
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- Institut de La Vision, INSERM Paris, France
| | - Eberhart Zrenner
- Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
- Werner Reichardt Center for Integrative Neuroscience, University of Tübingen, Tübingen, Germany
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tübingen, Tübingen, Germany
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28
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Gupta PR, Pendse N, Greenwald SH, Leon M, Liu Q, Pierce EA, Bujakowska KM. Ift172 conditional knock-out mice exhibit rapid retinal degeneration and protein trafficking defects. Hum Mol Genet 2018; 27:2012-2024. [PMID: 29659833 PMCID: PMC5961092 DOI: 10.1093/hmg/ddy109] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/19/2018] [Accepted: 03/26/2018] [Indexed: 01/01/2023] Open
Abstract
Intraflagellar transport (IFT) is a bidirectional transport process that occurs along primary cilia and specialized sensory cilia, such as photoreceptor outersegments. Genes coding for various IFT components are associated with ciliopathies. Mutations in IFT172 lead to diseases ranging from isolated retinal degeneration to severe syndromic ciliopathies. In this study, we created a mouse model of IFT172-associated retinal degeneration to investigate the ocular disease mechanism. We found that depletion of IFT172 in rod photoreceptors leads to a rapid degeneration of the retina, with severely reduced electroretinography (ERG) responses by 1 month and complete outer-nuclear layer (ONL) degeneration by 2 months. We investigated molecular mechanisms of degeneration and show that IFT172 protein reduction leads to mislocalization of specific photoreceptor outersegment (OS) proteins (RHO, RP1, IFT139), aberrant light-driven translocation of alpha transducin and altered localization of glioma-associated oncogene family member 1 (GLI1). This mouse model exhibits key features of the retinal phenotype observed in patients with IFT172-associated blindness and can be used for in vivo testing of ciliopathy therapies.
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Affiliation(s)
- Priya R Gupta
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
- Weill Cornell Medical College, New York, NY 10021, USA
| | - Nachiket Pendse
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Scott H Greenwald
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Mihoko Leon
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Qin Liu
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Eric A Pierce
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
| | - Kinga M Bujakowska
- Department of Ophthalmology, Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA
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29
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Moye AR, Singh R, Kimler VA, Dilan TL, Munezero D, Saravanan T, Goldberg AFX, Ramamurthy V. ARL2BP, a protein linked to retinitis pigmentosa, is needed for normal photoreceptor cilia doublets and outer segment structure. Mol Biol Cell 2018; 29:1590-1598. [PMID: 29718757 PMCID: PMC6080659 DOI: 10.1091/mbc.e18-01-0040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The outer segment (OS) of photoreceptor cells is an elaboration of a primary cilium with organized stacks of membranous disks that contain the proteins needed for phototransduction and vision. Though ciliary formation and function has been well characterized, little is known about the role of cilia in the development of photoreceptor OS. Nevertheless, progress has been made by studying mutations in ciliary proteins, which often result in malformed OSs and lead to blinding diseases. To investigate how ciliary proteins contribute to OS formation, we generated a knockout (KO) mouse model for ARL2BP, a ciliary protein linked to retinitis pigmentosa. The KO mice display an early and progressive reduction in visual response. Before photoreceptor degeneration, we observed disorganization of the photoreceptor OS, with vertically aligned disks and shortened axonemes. Interestingly, ciliary doublet microtubule (MT) structure was also impaired, displaying open B-tubule doublets, paired with loss of singlet MTs. On the basis of results from this study, we conclude that ARL2BP is necessary for photoreceptor ciliary doublet formation and axoneme elongation, which is required for OS morphogenesis and vision.
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Affiliation(s)
- Abigail R Moye
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Ratnesh Singh
- Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | | | - Tanya L Dilan
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | - Daniella Munezero
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506
| | | | | | - Visvanathan Ramamurthy
- Department of Ophthalmology, West Virginia University, Morgantown, WV 26506.,Department of Biochemistry, West Virginia University, Morgantown, WV 26506.,Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV 26506
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30
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Verbakel SK, van Huet RAC, Boon CJF, den Hollander AI, Collin RWJ, Klaver CCW, Hoyng CB, Roepman R, Klevering BJ. Non-syndromic retinitis pigmentosa. Prog Retin Eye Res 2018; 66:157-186. [PMID: 29597005 DOI: 10.1016/j.preteyeres.2018.03.005] [Citation(s) in RCA: 513] [Impact Index Per Article: 85.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 03/20/2018] [Accepted: 03/22/2018] [Indexed: 12/23/2022]
Abstract
Retinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. RP is a leading cause of visual disability, with a worldwide prevalence of 1:4000. Although the majority of RP cases are non-syndromic, 20-30% of patients with RP also have an associated non-ocular condition. RP typically manifests with night blindness in adolescence, followed by concentric visual field loss, reflecting the principal dysfunction of rod photoreceptors; central vision loss occurs later in life due to cone dysfunction. Photoreceptor function measured with an electroretinogram is markedly reduced or even absent. Optical coherence tomography (OCT) and fundus autofluorescence (FAF) imaging show a progressive loss of outer retinal layers and altered lipofuscin distribution in a characteristic pattern. Over the past three decades, a vast number of disease-causing variants in more than 80 genes have been associated with non-syndromic RP. The wide heterogeneity of RP makes it challenging to describe the clinical findings and pathogenesis. In this review, we provide a comprehensive overview of the clinical characteristics of RP specific to genetically defined patient subsets. We supply a unique atlas with color fundus photographs of most RP subtypes, and we discuss the relevant considerations with respect to differential diagnoses. In addition, we discuss the genes involved in the pathogenesis of RP, as well as the retinal processes that are affected by pathogenic mutations in these genes. Finally, we review management strategies for patients with RP, including counseling, visual rehabilitation, and current and emerging therapeutic options.
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Affiliation(s)
- Sanne K Verbakel
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ramon A C van Huet
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Leiden, The Netherlands; Department of Ophthalmology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Rob W J Collin
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Carel B Hoyng
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ronald Roepman
- Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - B Jeroen Klevering
- Department of Ophthalmology, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, The Netherlands.
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C8ORF37 Is Required for Photoreceptor Outer Segment Disc Morphogenesis by Maintaining Outer Segment Membrane Protein Homeostasis. J Neurosci 2018; 38:3160-3176. [PMID: 29440555 DOI: 10.1523/jneurosci.2964-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 01/30/2018] [Accepted: 02/05/2018] [Indexed: 01/09/2023] Open
Abstract
C8ORF37 is a causative gene for three different clinical forms of incurable retinal degeneration. However, the completely unknown function of C8ORF37 limits our understanding of the pathogenicity of C8ORF37 mutations. Here, we performed a comprehensive phenotypic characterization of a C8orf37 KO mouse line, generated using CRISPR/Cas9 technology. Both C8orf37 KO male and female mice exhibited progressive and simultaneous degeneration of rod and cone photoreceptors but no non-ocular phenotypes. The major ultrastructural feature of C8orf37 KO photoreceptors was massive disorganization of the outer segment (OS) membrane discs starting from the onset of disc morphogenesis during development. At the molecular level, the amounts of multiple OS-specific membrane proteins, including proteins involved in membrane disc organization, were reduced, although these proteins were targeted normally to the OS. Considering the distribution of C8ORF37 throughout the photoreceptor cell body, the normal structure of the KO photoreceptor connecting cilium, and the absence of defects in other ciliary organs of the KO mice, our findings do not support the previous notion that C8ORF37 was a ciliary protein. Because C8ORF37 is absent in the photoreceptor OS, C8ORF37 may participate in the secretory pathway of OS membrane proteins in the photoreceptor cell body and thus maintain the homeostasis of these proteins. This study established a valid animal model for future therapeutic studies of C8ORF37-associated retinal degeneration. This study also shed new light on the role of C8ORF37 in photoreceptors and on the pathogenic mechanism underlying retinal degeneration caused by C8ORF37 mutations.SIGNIFICANCE STATEMENT Inherited retinal degeneration is a group of incurable conditions with poorly understood underlying molecular mechanisms. We investigated C8ORF37, a causative gene for three retinal degenerative conditions: retinitis pigmentosa, cone-rod dystrophy, and Bardet-Biedl syndrome. C8ORF37 encodes a protein with no known functional domains and thus its biological function is unpredictable. We knocked out the C8ORF37 ortholog in mice, which resulted in a retinal phenotype similar to that observed in patients. We further demonstrated that C8ORF37 is required for photoreceptor outer segment disc formation and alignment, a process that is critical for photoreceptor function and survival. This study advances our understanding of the pathogenesis of retinal degeneration and establishes a valuable mouse model for future therapeutic development.
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32
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Li P, Kleinstiver BP, Leon MY, Prew MS, Navarro-Gomez D, Greenwald SH, Pierce EA, Joung JK, Liu Q. Allele-Specific CRISPR-Cas9 Genome Editing of the Single-Base P23H Mutation for Rhodopsin-Associated Dominant Retinitis Pigmentosa. CRISPR J 2018; 1:55-64. [PMID: 31021187 DOI: 10.1089/crispr.2017.0009] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Treatment strategies for dominantly inherited disorders typically involve silencing or ablating the pathogenic allele. CRISPR-Cas nucleases have shown promise in allele-specific knockout approaches when the dominant allele creates unique protospacer adjacent motifs that can lead to allele-restricted targeting. Here, we present a spacer-mediated allele-specific knockout approach that utilizes both SpCas9 variants and truncated single-guide RNAs to achieve efficient discrimination of a single-nucleotide mutation in rhodopsin (Rho)-P23H mice, a model of dominant retinitis pigmentosa. We found that approximately 45% of the mutant P23H allele was edited at the DNA level and that the relative RNA expression of wild-type Rho was about 2.8 times more than that of mutant Rho in treated retinas. Furthermore, the progression of photoreceptor cell degeneration in outer nuclear layer was significantly delayed in treated regions of the Rho-P23H retinas at 5 weeks of age. Our proof-of-concept study therefore outlines a general strategy that could potentially be expanded to examine the therapeutic benefit of allele-specific gene editing approach to treat human P23H patients. Our study also extends allele-specific editing strategies beyond discrimination within the protospacer adjacent motif sites, with potentially broad applicability to other dominant diseases.
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Affiliation(s)
- Pingjuan Li
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
| | - Benjamin P Kleinstiver
- 3 Molecular Pathology Unit and Center for Cancer Research, Massachusetts General Hospital , Charlestown, Massachusetts.,4 Center for Computational and Integrative Biology, Massachusetts General Hospital , Charlestown, Massachusetts.,5 Department of Pathology, Harvard Medical School, Boston, Massachusetts
| | - Mihoko Y Leon
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
| | - Michelle S Prew
- 3 Molecular Pathology Unit and Center for Cancer Research, Massachusetts General Hospital , Charlestown, Massachusetts.,4 Center for Computational and Integrative Biology, Massachusetts General Hospital , Charlestown, Massachusetts
| | - Daniel Navarro-Gomez
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
| | - Scott H Greenwald
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
| | - Eric A Pierce
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
| | - J Keith Joung
- 3 Molecular Pathology Unit and Center for Cancer Research, Massachusetts General Hospital , Charlestown, Massachusetts.,4 Center for Computational and Integrative Biology, Massachusetts General Hospital , Charlestown, Massachusetts.,5 Department of Pathology, Harvard Medical School, Boston, Massachusetts
| | - Qin Liu
- 1 Ocular Genomics Institute , Massachusetts Eye and Ear Infirmary, Boston, Massachusetts.,2 Department of Ophthalmology, Harvard Medical School , Boston, Massachusetts
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May-Simera H, Nagel-Wolfrum K, Wolfrum U. Cilia - The sensory antennae in the eye. Prog Retin Eye Res 2017; 60:144-180. [PMID: 28504201 DOI: 10.1016/j.preteyeres.2017.05.001] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 05/04/2017] [Accepted: 05/08/2017] [Indexed: 12/21/2022]
Abstract
Cilia are hair-like projections found on almost all cells in the human body. Originally believed to function merely in motility, the function of solitary non-motile (primary) cilia was long overlooked. Recent research has demonstrated that primary cilia function as signalling hubs that sense environmental cues and are pivotal for organ development and function, tissue hoemoestasis, and maintenance of human health. Cilia share a common anatomy and their diverse functional features are achieved by evolutionarily conserved functional modules, organized into sub-compartments. Defects in these functional modules are responsible for a rapidly growing list of human diseases collectively termed ciliopathies. Ocular pathogenesis is common in virtually all classes of syndromic ciliopathies, and disruptions in cilia genes have been found to be causative in a growing number of non-syndromic retinal dystrophies. This review will address what is currently known about cilia contribution to visual function. We will focus on the molecular and cellular functions of ciliary proteins and their role in the photoreceptor sensory cilia and their visual phenotypes. We also highlight other ciliated cell types in tissues of the eye (e.g. lens, RPE and Müller glia cells) discussing their possible contribution to disease progression. Progress in basic research on the cilia function in the eye is paving the way for therapeutic options for retinal ciliopathies. In the final section we describe the latest advancements in gene therapy, read-through of non-sense mutations and stem cell therapy, all being adopted to treat cilia dysfunction in the retina.
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Affiliation(s)
- Helen May-Simera
- Institute of Molecular Physiology, Cilia Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Kerstin Nagel-Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Uwe Wolfrum
- Institute of Molecular Physiology, Molecular Cell Biology, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany.
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Maturation arrest in early postnatal sensory receptors by deletion of the miR-183/96/182 cluster in mouse. Proc Natl Acad Sci U S A 2017; 114:E4271-E4280. [PMID: 28484004 DOI: 10.1073/pnas.1619442114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The polycistronic miR-183/96/182 cluster is preferentially and abundantly expressed in terminally differentiating sensory epithelia. To clarify its roles in the terminal differentiation of sensory receptors in vivo, we deleted the entire gene cluster in mouse germline through homologous recombination. The miR-183/96/182 null mice display impairment of the visual, auditory, vestibular, and olfactory systems, attributable to profound defects in sensory receptor terminal differentiation. Maturation of sensory receptor precursors is delayed, and they never attain a fully differentiated state. In the retina, delay in up-regulation of key photoreceptor genes underlies delayed outer segment elongation and possibly mispositioning of cone nuclei in the retina. Incomplete maturation of photoreceptors is followed shortly afterward by early-onset degeneration. Cell biologic and transcriptome analyses implicate dysregulation of ciliogenesis, nuclear translocation, and an epigenetic mechanism that may control timing of terminal differentiation in developing photoreceptors. In both the organ of Corti and the vestibular organ, impaired terminal differentiation manifests as immature stereocilia and kinocilia on the apical surface of hair cells. Our study thus establishes a dedicated role of the miR-183/96/182 cluster in driving the terminal differentiation of multiple sensory receptor cells.
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35
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Hsu KS, Chuang JZ, Sung CH. The Biology of Ciliary Dynamics. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a027904. [PMID: 28062565 DOI: 10.1101/cshperspect.a027904] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The cilium is an evolutionally conserved apical membrane protrusion that senses and transduces diverse signals to regulate a wide range of cellular activities. The cilium is dynamic in length, structure, and protein composition. Dysregulation of ciliary dynamics has been linked with ciliopathies and other human diseases. The cilium undergoes cell-cycle-dependent assembly and disassembly, with ciliary resorption linked with G1-S transition and cell-fate choice. In the resting cell, the cilium remains sensitive to environmental cues for remodeling during tissue homeostasis and repair. Recent findings further reveal an interplay between the cilium and extracellular vesicles and identify bioactive cilium-derived vesicles, posing a previously unrecognized role of cilia for sending signals. The photoreceptor outer segment is a notable dynamic cilium. A recently discovered protein transport mechanism in photoreceptors maintains light-regulated homeostasis of ciliary length.
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Affiliation(s)
- Kuo-Shun Hsu
- The Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10065
| | - Jen-Zen Chuang
- The Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, New York 10065
| | - Ching-Hwa Sung
- Departments of Cell and Developmental Biology, Weill Cornell Medical College, New York, New York 10065
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36
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D'Angelo R, Donato L, Venza I, Scimone C, Aragona P, Sidoti A. Possible protective role of the ABCA4 gene c.1268A>G missense variant in Stargardt disease and syndromic retinitis pigmentosa in a Sicilian family: Preliminary data. Int J Mol Med 2017; 39:1011-1020. [PMID: 28290600 DOI: 10.3892/ijmm.2017.2917] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/07/2017] [Indexed: 11/05/2022] Open
Abstract
In the wide horizon of ophthalmologically rare diseases among retinitis pigmentosa forms, Stargardt disease has gradually assumed a significant role due to its heterogeneity. In the present study, we aimed to support one of two opposite hypotheses concerning the causative or protective role of heterozygous c.1268A>G missense variant of the ABCA4 gene in Stargardt disease and in syndromic retinitis pigmentosa. This study was based on a family consisting of three members: proband, age 54, with high myopia, myopic chorioretinitis and retinal dystrophy; wife, age 65, with mild symptoms; daughter, age 29, asymptomatic. After genetic counseling, ABCA4 and RP1 gene analysis was performed. The results highlighted an important genetic picture. The proband was found to carry two variant RP1 SNPs, rs2293869 (c.2953A>T) and rs61739567 (c.6098G>A), and, a wild-type condition for four RP1 polymorphisms, rs444772 (c.2623G>A) and three SNPs in the 'hot-spot' region, exon 4. The proband's wife, instead, showed an opposite condition compared to her husband: a homozygous mutated condition for the first four SNPs analyzed, while the last two were wild-type. Regarding the ABCA4 gene, the proband evidenced a wild-type condition. Furthermore, the wife showed a heterozygous condition of ABCA4 rs3112831 (c.1268A>G). As expected, the daughter presented heterozygosity for all variants of both genes. In conclusion, even though the c.1268A>G missense variant of the ABCA4 gene has often been reported as causative of disease, and in other cases protective of disease, in our family case, the variant appears to reduce or delay the risk of onset of Stargardt disease.
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Affiliation(s)
- Rosalia D'Angelo
- Department of Biomedical Sciences, Odontoiatric and Morphofunctional Images, University of Messina, I-98125 Messina, Italy
| | - Luigi Donato
- Department of Biomedical Sciences, Odontoiatric and Morphofunctional Images, University of Messina, I-98125 Messina, Italy
| | - Isabella Venza
- Department of Clinical and Experimental Medicine, University of Messina, I-98125 Messina, Italy
| | - Concetta Scimone
- Department of Biomedical Sciences, Odontoiatric and Morphofunctional Images, University of Messina, I-98125 Messina, Italy
| | - Pasquale Aragona
- Department of Biomedical Sciences, Odontoiatric and Morphofunctional Images, University of Messina, I-98125 Messina, Italy
| | - Antonina Sidoti
- Department of Biomedical Sciences, Odontoiatric and Morphofunctional Images, University of Messina, I-98125 Messina, Italy
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37
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Goldberg AFX, Moritz OL, Williams DS. Molecular basis for photoreceptor outer segment architecture. Prog Retin Eye Res 2016; 55:52-81. [PMID: 27260426 DOI: 10.1016/j.preteyeres.2016.05.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 01/11/2023]
Abstract
To serve vision, vertebrate rod and cone photoreceptors must detect photons, convert the light stimuli into cellular signals, and then convey the encoded information to downstream neurons. Rods and cones are sensory neurons that each rely on specialized ciliary organelles to detect light. These organelles, called outer segments, possess elaborate architectures that include many hundreds of light-sensitive membranous disks arrayed one atop another in precise register. These stacked disks capture light and initiate the chain of molecular and cellular events that underlie normal vision. Outer segment organization is challenged by an inherently dynamic nature; these organelles are subject to a renewal process that replaces a significant fraction of their disks (up to ∼10%) on a daily basis. In addition, a broad range of environmental and genetic insults can disrupt outer segment morphology to impair photoreceptor function and viability. In this chapter, we survey the major progress that has been made for understanding the molecular basis of outer segment architecture. We also discuss key aspects of organelle lipid and protein composition, and highlight distributions, interactions, and potential structural functions of key OS-resident molecules, including: kinesin-2, actin, RP1, prominin-1, protocadherin 21, peripherin-2/rds, rom-1, glutamic acid-rich proteins, and rhodopsin. Finally, we identify key knowledge gaps and challenges that remain for understanding how normal outer segment architecture is established and maintained.
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Affiliation(s)
- Andrew F X Goldberg
- Eye Research Institute, Oakland University, 417 Dodge Hall, Rochester, MI, 48309, USA.
| | - Orson L Moritz
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, BC, Canada
| | - David S Williams
- Department of Ophthalmology and Jules Stein Eye Institute, Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
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Gene expression changes in the retina following subretinal injection of human neural progenitor cells into a rodent model for retinal degeneration. Mol Vis 2016; 22:472-90. [PMID: 27217715 PMCID: PMC4872275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/13/2016] [Indexed: 12/03/2022] Open
Abstract
PURPOSE Retinal degenerative diseases (RDDs) affect millions of people and are the leading cause of vision loss. Although treatment options for RDDs are limited, stem and progenitor cell-based therapies have great potential to halt or slow the progression of vision loss. Our previous studies have shown that a single subretinal injection of human forebrain derived neural progenitor cells (hNPCs) into the Royal College of Surgeons (RCS) retinal degenerate rat offers long-term preservation of photoreceptors and visual function. Furthermore, neural progenitor cells are currently in clinical trials for treating age-related macular degeneration; however, the molecular mechanisms of stem cell-based therapies are largely unknown. This is the first study to analyze gene expression changes in the retina of RCS rats following subretinal injection of hNPCs using high-throughput sequencing. METHODS RNA-seq data of retinas from RCS rats injected with hNPCs (RCS(hNPCs)) were compared to sham surgery in RCS (RCS(sham)) and wild-type Long Evans (LE(sham)) rats. Differential gene expression patterns were determined with in silico analysis and confirmed with qRT-PCR. Function, biologic, cellular component, and pathway analyses were performed on differentially expressed genes and investigated with immunofluorescent staining experiments. RESULTS Analysis of the gene expression data sets identified 1,215 genes that were differentially expressed between RCS(sham) and LE(sham) samples. Additionally, 283 genes were differentially expressed between the RCS(hNPCs) and RCS(sham) samples. Comparison of these two gene sets identified 68 genes with inverse expression (termed rescue genes), including Pdc, Rp1, and Cdc42ep5. Functional, biologic, and cellular component analyses indicate that the immune response is enhanced in RCS(sham). Pathway analysis of the differential expression gene sets identified three affected pathways in RCS(hNPCs), which all play roles in phagocytosis signaling. Immunofluorescent staining detected the increased presence of macrophages and microglia in RCS(sham) retinas, which decreased in RCS(hNPCs) retinas similar to the patterns detected in LE(sham). CONCLUSIONS The results from this study provide evidence of the gene expression changes that occur following treatment with hNPCs in the degenerating retina. This information can be used in future studies to potentially enhance or predict responses to hNPC and other stem cell therapies for retinal degenerative diseases.
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39
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Fernández-López B, Romaus-Sanjurjo D, Senra-Martínez P, Anadón R, Barreiro-Iglesias A, Rodicio MC. Spatiotemporal Pattern of Doublecortin Expression in the Retina of the Sea Lamprey. Front Neuroanat 2016; 10:5. [PMID: 26858609 PMCID: PMC4731500 DOI: 10.3389/fnana.2016.00005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/12/2016] [Indexed: 12/30/2022] Open
Abstract
Despite the importance of doublecortin (DCX) for the development of the nervous system, its expression in the retina of most vertebrates is still unknown. The key phylogenetic position of lampreys, together with their complex life cycle, with a long blind larval stage and an active predator adult stage, makes them an interesting model to study retinal development. Here, we studied the spatiotemporal pattern of expression of DCX in the retina of the sea lamprey. In order to characterize the DCX expressing structures, the expression of acetylated α-tubulin (a neuronal marker) and cytokeratins (glial marker) was also analyzed. Tract-tracing methods were used to label ganglion cells. DCX immunoreactivity appeared initially in photoreceptors, ganglion cells and in fibers of the prolarval retina. In larvae smaller than 100 mm, DCX expression was observed in photoreceptors, in cells located in the inner nuclear and inner plexiform layers (IPLs) and in fibers coursing in the nuclear and IPLs, and in the optic nerve (ON). In retinas of premetamorphic and metamorphic larvae, DCX immunoreactivity was also observed in radially oriented cells and fibers and in a layer of cells located in the outer part of the inner neuroblastic layer (INbL) of the lateral retina. Photoreceptors and fibers ending in the outer limitans membrane (OLM) showed DCX expression in adults. Some retinal pigment epithelium cells were also DCX immunoreactive. Immunofluorescence for α-tubulin in premetamorphic larvae showed coexpression in most of the DCX immunoreactive structures. No cells/fibers were found showing DCX and cytokeratins colocalization. The perikaryon of mature ganglion cells is DCX negative. The expression of DCX in sea lamprey retinas suggests that it could play roles in the migration of cells that differentiate in the metamorphosis, in the establishment of connections of ganglion cells and in the development of photoreceptors. Our results also suggest that the radial glia and retinal pigment epithelium cells of lampreys are neurogenic. Comparison of our observations with those reported in gnathostomes reveals similarities and interesting differences probably due to the peculiar development of the sea lamprey retina.
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Affiliation(s)
- Blanca Fernández-López
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
| | - Daniel Romaus-Sanjurjo
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
| | - Pablo Senra-Martínez
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
| | - Ramón Anadón
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
| | - Antón Barreiro-Iglesias
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
| | - María Celina Rodicio
- Faculty of Biology, Department of Cell Biology and Ecology, CIBUS, Universidade de Santiago de CompostelaSantiago de Compostela, Spain
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40
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Bales KL, Gross AK. Aberrant protein trafficking in retinal degenerations: The initial phase of retinal remodeling. Exp Eye Res 2015; 150:71-80. [PMID: 26632497 DOI: 10.1016/j.exer.2015.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/18/2022]
Abstract
Retinal trafficking proteins are involved in molecular assemblies that govern protein transport, orchestrate cellular events involved in cilia formation, regulate signal transduction, autophagy and endocytic trafficking, all of which if not properly controlled initiate retinal degeneration. Improper function and or trafficking of these proteins and molecular networks they are involved in cause a detrimental cascade of neural retinal remodeling due to cell death, resulting as devastating blinding diseases. A universal finding in retinal degenerative diseases is the profound detection of retinal remodeling, occurring as a phased modification of neural retinal function and structure, which begins at the molecular level. Retinal remodeling instigated by aberrant trafficking of proteins encompasses many forms of retinal degenerations, such as the diverse forms of retinitis pigmentosa (RP) and disorders that resemble RP through mutations in the rhodopsin gene, retinal ciliopathies, and some forms of glaucoma and age-related macular degeneration (AMD). As a large majority of genes associated with these different retinopathies are overlapping, it is imperative to understand their underlying molecular mechanisms. This review will discuss some of the most recent discoveries in vertebrate retinal remodeling and retinal degenerations caused by protein mistrafficking.
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Affiliation(s)
- Katie L Bales
- University of Alabama at Birmingham, Birmingham, AL, United States
| | - Alecia K Gross
- University of Alabama at Birmingham, Birmingham, AL, United States.
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Kumaramanickavel G, Denton MJ, Legge M. No evidence for a genetic blueprint: The case of the "complex" mammalian photoreceptor. Indian J Ophthalmol 2015; 63:353-4. [PMID: 26044481 PMCID: PMC4463566 DOI: 10.4103/0301-4738.158093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Despite the intensity of the search for genes causing inherited retinal degenerations over the past 3 decades, of the approximately 200 disease genes identified to date, all appear to be ordinary housekeeping genes specifying proteins playing basic structural and functional roles in the mature photoreceptor cells. No genes or genetic elements have been identified which can be construed as having a specific morphogenic role, directing the development of the cytoarchitecture of any particular retinal cell. The evidence suggests that the cytoarchitecture of the retinal photoreceptors, although enormously complex, arises from the self-organization of the cells constituents without any regulation or direction from an external genetic blueprint.
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Affiliation(s)
| | | | - M Legge
- Department of Biochemistry, University of Otago, Dunedin, NewZealand
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Jiang L, Wei Y, Ronquillo CC, Marc RE, Yoder BK, Frederick JM, Baehr W. Heterotrimeric kinesin-2 (KIF3) mediates transition zone and axoneme formation of mouse photoreceptors. J Biol Chem 2015; 290:12765-78. [PMID: 25825494 DOI: 10.1074/jbc.m115.638437] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Indexed: 11/06/2022] Open
Abstract
Anterograde intraflagellar transport (IFT) employing kinesin-2 molecular motors has been implicated in trafficking of photoreceptor outer segment proteins. We generated embryonic retina-specific (prefix "emb") and adult tamoxifen-induced (prefix "tam") deletions of KIF3a and IFT88 in adult mice to study photoreceptor ciliogenesis and protein trafficking. In (emb)Kif3a(-/-) and in (emb)Ift88(-/-) mice, basal bodies failed to extend transition zones (connecting cilia) with outer segments, and visual pigments mistrafficked. In contrast, (tam)Kif3a(-/-) and (tam)Ift88(-/-) photoreceptor axonemes disintegrated slowly post-induction, starting distally, but rhodopsin and cone pigments trafficked normally for more than 2 weeks, a time interval during which the outer segment is completely renewed. The results demonstrate that visual pigments transport to the retinal outer segment despite removal of KIF3 and IFT88, and KIF3-mediated anterograde IFT is responsible for photoreceptor transition zone and axoneme formation.
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Affiliation(s)
- Li Jiang
- From the Departments of Ophthalmology and Visual Sciences and
| | - Yuxiao Wei
- From the Departments of Ophthalmology and Visual Sciences and
| | | | - Robert E Marc
- From the Departments of Ophthalmology and Visual Sciences and
| | - Bradley K Yoder
- the Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, and
| | | | - Wolfgang Baehr
- From the Departments of Ophthalmology and Visual Sciences and the Department of Biology, University of Utah, Salt Lake City, Utah 84112 Neurobiology and Anatomy, University of Utah Health Science Center, Salt Lake City, Utah 84132,
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43
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Kevany BM, Zhang N, Jastrzebska B, Palczewski K. Animals deficient in C2Orf71, an autosomal recessive retinitis pigmentosa-associated locus, develop severe early-onset retinal degeneration. Hum Mol Genet 2015; 24:2627-40. [PMID: 25616964 DOI: 10.1093/hmg/ddv025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/21/2015] [Indexed: 02/01/2023] Open
Abstract
Genetic mapping was recently used to identify the underlying cause for a previously uncharacterized cohort of autosomal recessive retinitis pigmentosa cases. Genetic mapping of affected individuals resulted in the identification of an uncharacterized gene, C2Orf71, as the causative locus. However, initial homology searches failed to reveal similarities to any previously characterized protein or domain. To address this issue, we characterized the mouse homolog, BC027072. Immunohistochemistry with a custom polyclonal antibody showed staining localized to the inner segments (IS) of photoreceptor cells, as well as the outer segments (OS) of cone cells. A knockout mouse line (BC(-/-)) was generated and demonstrated that loss of this gene results in a severe, early-onset retinal degeneration. Histology and electron microscopy (EM) revealed disorganized OS as early as 3 weeks with complete loss by 24 weeks of age. EM micrographs displayed packets of cellular material containing OS discs or IS organelles in the OS region and abnormal retinal pigmented epithelium cells. Analyses of retinoids and rhodopsin levels showed <20% in BC(-/-) versus wild-type mice early in development. Electroretinograms demonstrated that affected mice were virtually non-responsive to light by 8 weeks of age. Lastly, RNAseq analysis of ocular gene expression in BC(-/-) mice revealed clues to the causes of the progressive retinal degenerations. Although its function remains unknown, this protein appears essential for normal OS development/maintenance and vision in humans and mice. RNAseq data are available in the GEO database under accession: GSE63810.
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Affiliation(s)
- Brian M Kevany
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Ning Zhang
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Beata Jastrzebska
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA
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Targeted next generation sequencing identifies novel mutations in RP1 as a relatively common cause of autosomal recessive rod-cone dystrophy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:485624. [PMID: 25692139 PMCID: PMC4307388 DOI: 10.1155/2015/485624] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 07/10/2014] [Indexed: 01/01/2023]
Abstract
We report ophthalmic and genetic findings in families with autosomal recessive rod-cone dystrophy (arRCD) and RP1 mutations. Detailed ophthalmic examination was performed in 242 sporadic and arRCD subjects. Genomic DNA was investigated using our customized next generation sequencing panel targeting up to 123 genes implicated in inherited retinal disorders. Stringent filtering coupled with Sanger sequencing and followed by cosegregation analysis was performed to confirm biallelism and the implication of the most likely disease causing variants. Sequencing identified 9 RP1 mutations in 7 index cases. Eight of the mutations were novel, and all cosegregated with severe arRCD phenotype, found associated with additional macular changes. Among the identified mutations, 4 belong to a region, previously associated with arRCD, and 5 others in a region previously associated with adRCD. Our prevalence studies showed that RP1 mutations account for up to 2.5% of arRCD. These results point out for the necessity of sequencing RP1 when genetically investigating sporadic and arRCD. It further highlights the interest of unbiased sequencing technique, which allows investigating the implication of the same gene in different modes of inheritance. Finally, it reports that different regions of RP1 can also lead to arRCD.
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Vogel P, Gelfman CM, Issa T, Payne BJ, Hansen GM, Read RW, Jones C, Pitcher MR, Ding ZM, DaCosta CM, Shadoan MK, Vance RB, Powell DR. Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome? Vet Pathol 2014; 52:580-95. [PMID: 25161209 DOI: 10.1177/0300985814547392] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.
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Affiliation(s)
- P Vogel
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C M Gelfman
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - T Issa
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - B J Payne
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - G M Hansen
- Department of Molecular Genetics, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - R W Read
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C Jones
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - M R Pitcher
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - Z-M Ding
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C M DaCosta
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - M K Shadoan
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - R B Vance
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - D R Powell
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
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Song D, Grieco S, Li Y, Hunter A, Chu S, Zhao L, Song Y, DeAngelis RA, Shi LY, Liu Q, Pierce EA, Nishina PM, Lambris JD, Dunaief JL. A murine RP1 missense mutation causes protein mislocalization and slowly progressive photoreceptor degeneration. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 184:2721-9. [PMID: 25088982 DOI: 10.1016/j.ajpath.2014.06.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 06/04/2014] [Accepted: 06/10/2014] [Indexed: 11/28/2022]
Abstract
Mutations in the RP1 gene can cause retinitis pigmentosa. We identified a spontaneous L66P mutation caused by two adjacent point mutations in the Rp1 gene in a colony of C57BL/6J mice. Mice homozygous for the L66P mutation exhibited slow, progressive photoreceptor degeneration throughout their lifespan. Optical coherence tomography imaging found abnormal photoreceptor reflectivity at 1 month of age. Histology found shortening and disorganization of the photoreceptor inner and outer segments and progressive thinning of the outer nuclear layer. Electroretinogram a- and b-wave amplitudes were decreased with age. Western blot analysis found that the quantity and size of the mutated retinitis pigmentosa 1 (RP1) protein were normal. However, immunohistochemistry found that the mutant Rp1 protein partially mislocalized to the transition zone of the shortened axonemes. This mutation disrupted colocalization with cytoplasmic microtubules in vitro. In conclusion, the L66P mutation in the first doublecortin domain of the Rp1 gene impairs Rp1 protein localization and function, leading to abnormalities in photoreceptor outer segment structure and progressive photoreceptor degeneration. This is the first missense mutation in Rp1 shown to cause retinal degeneration. It provides a unique, slowly progressive photoreceptor degeneration model that mirrors the slow degeneration kinetics in most patients with retinitis pigmentosa.
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Affiliation(s)
- Delu Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Steve Grieco
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yafeng Li
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Allan Hunter
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sally Chu
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Liangliang Zhao
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Ophthalmology, Second Hospital of Jilin University, Changchun, China
| | - Ying Song
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Robert A DeAngelis
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Qin Liu
- Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts
| | - Eric A Pierce
- Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts
| | | | - John D Lambris
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joshua L Dunaief
- F.M. Kirby Center for Molecular Ophthalmology, Scheie Eye Institute, University of Pennsylvania, Philadelphia, Pennsylvania.
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Karlstetter M, Sorusch N, Caramoy A, Dannhausen K, Aslanidis A, Fauser S, Boesl MR, Nagel-Wolfrum K, Tamm ER, Jägle H, Stoehr H, Wolfrum U, Langmann T. Disruption of the retinitis pigmentosa 28 gene Fam161a in mice affects photoreceptor ciliary structure and leads to progressive retinal degeneration. Hum Mol Genet 2014; 23:5197-210. [DOI: 10.1093/hmg/ddu242] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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48
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Sakami S, Kolesnikov AV, Kefalov VJ, Palczewski K. P23H opsin knock-in mice reveal a novel step in retinal rod disc morphogenesis. Hum Mol Genet 2013; 23:1723-41. [PMID: 24214395 DOI: 10.1093/hmg/ddt561] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Retinal rod photoreceptor cells have double membrane discs located in their outer segments (ROS) that are continuously formed proximally from connecting cilia (CC) and phagocytized distally by the retinal pigmented epithelium. The major component of these rod discs, the light-sensitive visual pigment rhodopsin (Rho), consists of an opsin protein linked to 11-cis-retinal. The P23H mutation of rod opsin (P23H opsin) is the most common cause of human blinding autosomal dominant retinitis pigmentosa (adRP). A mouse model of adRP with this mutation (Rho(P23H/+)) shows low levels of P23H opsin protein, partial misalignment of discs and progressive retinal degeneration. However, the impact of mutant P23H opsin on the formation of abnormal discs is unclear and it is still unknown whether this mutant pigment can mediate phototransduction. Using transretinal ERG recordings, we demonstrate that P23H mutant Rho can trigger phototransduction but Rho(P23H/P23H) rods are ∼17 000-fold less sensitive to light than Rho(+/+) rods and produce abnormally fast photo-responses. By analyzing homozygous Rho(P23H/P23H) knock-in mice, we show that P23H opsin is transported to ciliary protrusions where it forms sagittally elongated discs. Transmission electron microscopy of postnatal day (PND) 14 Rho(P23H/+) mouse retina revealed disordered sagittally oriented discs before the onset of retinal degeneration. Surprisingly, we also observed smaller, immature sagittally oriented discs in PND14 Rho(+/)(-) and Rho(+/+) mice that were not seen in older animals. These findings provide fundamental insights into the pathogenesis of the P23H mutant opsin and reveal a novel early sagittally aligned disc formation step in normal ROS disc expansion.
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Affiliation(s)
- Sanae Sakami
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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49
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Atherton J, Houdusse A, Moores C. MAPping out distribution routes for kinesin couriers. Biol Cell 2013; 105:465-87. [PMID: 23796124 DOI: 10.1111/boc.201300012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 06/17/2013] [Indexed: 12/14/2022]
Abstract
In the crowded environment of eukaryotic cells, diffusion is an inefficient distribution mechanism for cellular components. Long-distance active transport is required and is performed by molecular motors including kinesins. Furthermore, in highly polarised, compartmentalised and plastic cells such as neurons, regulatory mechanisms are required to ensure appropriate spatio-temporal delivery of neuronal components. The kinesin machinery has diversified into a large number of kinesin motor proteins as well as adaptor proteins that are associated with subsets of cargo. However, many mechanisms contribute to the correct delivery of these cargos to their target domains. One mechanism is through motor recognition of sub-domain-specific microtubule (MT) tracks, sign-posted by different tubulin isoforms, tubulin post-translational modifications, tubulin GTPase activity and MT-associated proteins (MAPs). With neurons as a model system, a critical review of these regulatory mechanisms is presented here, with a particular focus on the emerging contribution of compartmentalised MAPs. Overall, we conclude that - especially for axonal cargo - alterations to the MT track can influence transport, although in vivo, it is likely that multiple track-based effects act synergistically to ensure accurate cargo distribution.
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Affiliation(s)
- Joseph Atherton
- Institute of Structural and Molecular Biology, Birkbeck College, London, WC1E 7HX, UK
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50
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Tiwari S, Hudson S, Gattone VH, Miller C, Chernoff EAG, Belecky-Adams TL. Meckelin 3 is necessary for photoreceptor outer segment development in rat Meckel syndrome. PLoS One 2013; 8:e59306. [PMID: 23516626 PMCID: PMC3596335 DOI: 10.1371/journal.pone.0059306] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 02/15/2013] [Indexed: 11/20/2022] Open
Abstract
Ciliopathies lead to multiorgan pathologies that include renal cysts, deafness, obesity and retinal degeneration. Retinal photoreceptors have connecting cilia joining the inner and outer segment that are responsible for transport of molecules to develop and maintain the outer segment process. The present study evaluated meckelin (MKS3) expression during outer segment genesis and determined the consequences of mutant meckelin on photoreceptor development and survival in Wistar polycystic kidney disease Wpk/Wpk rat using immunohistochemistry, analysis of cell death and electron microscopy. MKS3 was ubiquitously expressed throughout the retina at postnatal day 10 (P10) and P21. However, in the mature retina, MKS3 expression was restricted to photoreceptors and the retinal ganglion cell layer. At P10, both the wild type and homozygous Wpk mutant retina had all retinal cell types. In contrast, by P21, cells expressing rod- and cone-specific markers were fewer in number and expression of opsins appeared to be abnormally localized to the cell body. Cell death analyses were consistent with the disappearance of photoreceptor-specific markers and showed that the cells were undergoing caspase-dependent cell death. By electron microscopy, P10 photoreceptors showed rudimentary outer segments with an axoneme, but did not develop outer segment discs that were clearly present in the wild type counterpart. At p21 the mutant outer segments appeared much the same as the P10 mutant outer segments with only a short axoneme, while the wild-type controls had developed outer segments with many well-organized discs. We conclude that MKS3 is not important for formation of connecting cilium and rudimentary outer segments, but is critical for the maturation of outer segment processes.
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Affiliation(s)
- Sarika Tiwari
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Scott Hudson
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Vincent H. Gattone
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Caroline Miller
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Ellen A. G. Chernoff
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Teri L. Belecky-Adams
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- * E-mail:
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