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Heutinck PAT, van den Born LI, Vermeer M, Iglesias Gonzales AI, Hoyng CB, Pott JWR, Kroes HY, van Schooneveld MJ, Boon CJF, van Genderen MM, Plomp AS, de Jong-Hesse Y, van Egmond-Ebbeling MB, Hoefsloot LH, A. Bergen A, Klaver CCW, Meester-Smoor MA, Thiadens AAHJ, Verhoeven VJM. Frequency and Genetic Spectrum of Inherited Retinal Dystrophies in a Large Dutch Pediatric Cohort: The RD5000 Consortium. Invest Ophthalmol Vis Sci 2024; 65:40. [PMID: 39189993 PMCID: PMC11361385 DOI: 10.1167/iovs.65.10.40] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 08/03/2024] [Indexed: 08/28/2024] Open
Abstract
Purpose Gene-based therapies for inherited retinal dystrophies (IRDs) are upcoming. Treatment before substantial vision loss will optimize outcomes. It is crucial to identify common phenotypes and causative genes in children. This study investigated the frequency of these in pediatric IRD with the aim of highlighting relevant groups for future therapy. Methods Diagnostic, genetic, and demographic data, collected from medical charts of patients with IRD aged up to 20 years (n = 624, 63% male), registered in the Dutch RD5000 database, were analyzed to determine frequencies of phenotypes and genetic causes. Phenotypes were categorized as nonsyndromic (progressive and stationary IRD) and syndromic IRD. Genetic causes, mostly determined by whole-exome sequencing (WES), were examined. Additionally, we investigated the utility of periodic reanalysis of WES data in genetically unresolved cases. Results Median age at registration was 13 years (interquartile range, 9-16). Retinitis pigmentosa (RP; n = 123, 20%), Leber congenital amaurosis (LCA; n = 97, 16%), X-linked retinoschisis (n = 64, 10%), and achromatopsia (n = 63, 10%) were the most frequent phenotypes. The genetic cause was identified in 76% of the genetically examined patients (n = 473). The most frequently disease-causing genes were RS1 (n = 32, 9%), CEP290 (n = 28, 8%), CNGB3 (n = 21, 6%), and CRB1 (n = 17, 5%). Diagnostic yield after reanalysis of genetic data increased by 7%. Conclusions As in most countries, RP and LCA are the most prominent pediatric IRDs in the Netherlands, and variants in RS1 and CEP290 were the most prominent IRD genotypes. Our findings can guide therapy development to target the diseases and genes with the greatest needs in young patients.
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Affiliation(s)
- Pam A. T. Heutinck
- Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | | | - Maikel Vermeer
- Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
- The Rotterdam Eye Hospital and Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands
| | | | - Carel B. Hoyng
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jan Willem R. Pott
- Department of Ophthalmology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Hester Y. Kroes
- Department of Clinical Genetics, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Mary J. van Schooneveld
- Department of Ophthalmology, Amsterdam University Medical Center, Amsterdam, the Netherlands
- Bartiméus Diagnostic Center for Complex Visual Disorders, Zeist, the Netherlands
| | - Camiel J. F. Boon
- Department of Ophthalmology, Amsterdam University Medical Center, Amsterdam, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Maria M. van Genderen
- Bartiméus Diagnostic Center for Complex Visual Disorders, Zeist, the Netherlands
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Astrid S. Plomp
- Department of Human Genetics, Amsterdam Reproduction & Development, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Yvonne de Jong-Hesse
- Department of Ophthalmology, Amsterdam University Medical Center, Amsterdam, the Netherlands
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Lies H. Hoefsloot
- Department of Clinical Genetics, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Arthur A. Bergen
- Department of Human Genetics, Amsterdam Reproduction & Development, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
- The Rotterdam Eye Hospital and Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, the Netherlands
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - Magda A. Meester-Smoor
- Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
- The Rotterdam Eye Hospital and Rotterdam Ophthalmic Institute, Rotterdam, the Netherlands
| | | | - Virginie J. M. Verhoeven
- Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
- Department of Clinical Genetics, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
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Martin CG, Bent JS, Hill T, Topalidou I, Singhvi A. Epithelial UNC-23 limits mechanical stress to maintain glia-neuron architecture in C. elegans. Dev Cell 2024; 59:1668-1688.e7. [PMID: 38670103 PMCID: PMC11233253 DOI: 10.1016/j.devcel.2024.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/23/2023] [Accepted: 04/03/2024] [Indexed: 04/28/2024]
Abstract
For an organ to maintain correct architecture and function, its diverse cellular components must coordinate their size and shape. Although cell-intrinsic mechanisms driving homotypic cell-cell coordination are known, it is unclear how cell shape is regulated across heterotypic cells. We find that epithelial cells maintain the shape of neighboring sense-organ glia-neuron units in adult Caenorhabditis elegans (C. elegans). Hsp co-chaperone UNC-23/BAG2 prevents epithelial cell shape from deforming, and its loss causes head epithelia to stretch aberrantly during animal movement. In the sense-organ glia, amphid sheath (AMsh), this causes progressive fibroblast growth factor receptor (FGFR)-dependent disruption of the glial apical cytoskeleton. Resultant glial cell shape alteration causes concomitant shape change in glia-associated neuron endings. Epithelial UNC-23 maintenance of glia-neuron shape is specific both spatially, within a defined anatomical zone, and temporally, in a developmentally critical period. As all molecular components uncovered are broadly conserved across central and peripheral nervous systems, we posit that epithelia may similarly regulate glia-neuron architecture cross-species.
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Affiliation(s)
- Cecilia G Martin
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - James S Bent
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Tyler Hill
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
| | - Irini Topalidou
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Aakanksha Singhvi
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98195, USA.
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Zhang Z, Moye AR, He F, Chen M, Agosto MA, Wensel TG. Centriole and transition zone structures in photoreceptor cilia revealed by cryo-electron tomography. Life Sci Alliance 2024; 7:e202302409. [PMID: 38182160 PMCID: PMC10770417 DOI: 10.26508/lsa.202302409] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 12/12/2023] [Accepted: 12/12/2023] [Indexed: 01/07/2024] Open
Abstract
Primary cilia mediate sensory signaling in multiple organisms and cell types but have structures adapted for specific roles. Structural defects in them lead to devastating diseases known as ciliopathies in humans. Key to their functions are structures at their base: the basal body, the transition zone, the "Y-shaped links," and the "ciliary necklace." We have used cryo-electron tomography with subtomogram averaging and conventional transmission electron microscopy to elucidate the structures associated with the basal region of the "connecting cilia" of rod outer segments in mouse retina. The longitudinal variations in microtubule (MT) structures and the lumenal scaffold complexes connecting them have been determined, as well as membrane-associated transition zone structures: Y-shaped links connecting MT to the membrane, and ciliary beads connected to them that protrude from the cell surface and form a necklace-like structure. These results represent a clearer structural scaffold onto which molecules identified by genetics, proteomics, and superresolution fluorescence can be placed in our emerging model of photoreceptor sensory cilia.
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Affiliation(s)
- Zhixian Zhang
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Abigail R Moye
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
- Department of Ophthalmic Genetics, Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Feng He
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Muyuan Chen
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
| | - Melina A Agosto
- Department of Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Theodore G Wensel
- https://ror.org/02pttbw34 Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
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Grudzinska Pechhacker MK, Molnar A, Pekkola Pacheco N, Thonberg H, Querat L, Birkeldh U, Nordgren A, Lindstrand A. Reduced cone photoreceptor function and subtle systemic manifestations in two siblings with loss of SCLT1. Ophthalmic Genet 2024; 45:95-102. [PMID: 37246745 DOI: 10.1080/13816810.2023.2215332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 05/14/2023] [Indexed: 05/30/2023]
Abstract
BACKGROUND The sodium channel and clathrin linker 1 gene (SCLT1) has been involved in the pathogenesis of various ciliopathy disorders such as Bardet-Biedl syndrome, orofaciodigital syndrome type IX, and Senior-Løken syndrome. Detailed exams are warranted to outline all clinical features. Here, we present a family with a milder phenotype of SCLT1-related disease. MATERIAL AND METHODS Comprehensive eye examination including fundus images, OCT, color vision, visual fields and electroretinography were performed. Affected individuals were assessed by a pediatrician and a medical geneticist for systemic features of ciliopathy. Investigations included echocardiography, abdominal ultrasonography, blood work-up for diabetes, liver and kidney function. Genetic testing included NGS retinal dystrophy panel, segregation analysis and transcriptome sequencing. RESULTS Two male children, age 10 and 8 years, were affected with attention deficit hyperactivity disorder (ADHD), obesity and mild photophobia. The ophthalmic exam revealed reduced best-corrected visual acuity (BCVA), strabismus, hyperopia, astigmatism and moderate red-green defects. Milder changes suggesting photoreceptors disease were found on retinal imaging. Electroretinogram confirmed cone photoreceptors dysfunction. Genetic testing revealed a homozygous likely pathogenic, splice-site variant in SCLT1 gene NM_144643.3: c.1439 + 1del in the proband and in the affected brother. The unaffected parents were heterozygous for the SCLT1 variant. Transcriptome sequencing showed retention of intron 16 in the proband. CONCLUSIONS In this report, we highlight the importance of further extensive diagnostics in patients with unexplained reduced vision, strabismus, refractive errors and ADHD spectrum disorders. SCLT1-related retinal degeneration is very rare and isolated reduced function of cone photoreceptors has not previously been observed.
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Affiliation(s)
- Monika K Grudzinska Pechhacker
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Pediatric Ophthalmology, Strabismus and Electrophysiology, St. Erik Eye Hospital, Stockholm, Sweden
| | - Anna Molnar
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Pediatric Ophthalmology, Strabismus and Electrophysiology, St. Erik Eye Hospital, Stockholm, Sweden
| | - Nadja Pekkola Pacheco
- Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Håkan Thonberg
- Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Laurence Querat
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Pediatric Ophthalmology, Strabismus and Electrophysiology, St. Erik Eye Hospital, Stockholm, Sweden
| | - Ulrika Birkeldh
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Pediatric Ophthalmology, Strabismus and Electrophysiology, St. Erik Eye Hospital, Stockholm, Sweden
| | - Ann Nordgren
- Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Anna Lindstrand
- Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
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Liu X, Hu F, Zhang D, Li Z, He J, Zhang S, Wang Z, Zhao Y, Wu J, Liu C, Li C, Li X, Wu J. Whole genome sequencing enables new genetic diagnosis for inherited retinal diseases by identifying pathogenic variants. NPJ Genom Med 2024; 9:6. [PMID: 38245557 PMCID: PMC10799956 DOI: 10.1038/s41525-024-00391-2] [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: 05/29/2023] [Accepted: 12/19/2023] [Indexed: 01/22/2024] Open
Abstract
Inherited retinal diseases (IRDs) are a group of common primary retinal degenerative disorders. Conventional genetic testing strategies, such as panel-based sequencing and whole exome sequencing (WES), can only elucidate the genetic etiology in approximately 60% of IRD patients. Studies have suggested that unsolved IRD cases could be attributed to previously undetected structural variants (SVs) and intronic variants in IRD-related genes. The aim of our study was to obtain a definitive genetic diagnosis by employing whole genome sequencing (WGS) in IRD cases where the causative genes were inconclusive following an initial screening by panel sequencing. A total of 271 unresolved IRD patients and their available family members (n = 646) were screened using WGS to identify pathogenic SVs and intronic variants in 792 known ocular disease genes. Overall, 13% (34/271) of IRD patients received a confirmed genetic diagnosis, among which 7% were exclusively attributed to SVs, 4% to a combination of single nucleotide variants (SNVs) and SVs while another 2% were linked to intronic variants. 22 SVs, 3 deep-intronic variants, and 2 non-canonical splice-site variants across 14 IRD genes were identified in the entire cohort. Notably, all of these detected SVs and intronic variants were novel pathogenic variants. Among those, 74% (20/27) of variants were found in genes causally linked to Retinitis Pigmentosa (RP), with the gene EYS being the most frequently affected by SVs. The identification of SVs and intronic variants through WGS enhances the genetic diagnostic yield of IRDs and broadens the mutational spectrum of known IRD-associated genes.
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Affiliation(s)
- Xubing Liu
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fangyuan Hu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Daowei Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Zhe Li
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jianquan He
- Computer Center, Eye & ENT Hospital, Fudan University, Shanghai, China
| | - Shenghai Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Zhenguo Wang
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Yingke Zhao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Jiawen Wu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Chen Liu
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Chenchen Li
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
| | - Xin Li
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.
| | - Jihong Wu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China.
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China.
- Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China.
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Kruczek K, Swaroop A. Patient stem cell-derived in vitro disease models for developing novel therapies of retinal ciliopathies. Curr Top Dev Biol 2023; 155:127-163. [PMID: 38043950 DOI: 10.1016/bs.ctdb.2023.09.003] [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] [Indexed: 12/05/2023]
Abstract
Primary cilia are specialized organelles on the surface of almost all cells in vertebrate tissues and are primarily involved in the detection of extracellular stimuli. In retinal photoreceptors, cilia are uniquely modified to form outer segments containing components required for the detection of light in stacks of membrane discs. Not surprisingly, vision impairment is a frequent phenotype associated with ciliopathies, a heterogeneous class of conditions caused by mutations in proteins required for formation, maintenance and/or function of primary cilia. Traditionally, immortalized cell lines and model organisms have been used to provide insights into the biology of ciliopathies. The advent of methods for reprogramming human somatic cells into pluripotent stem cells has enabled the generation of in vitro disease models directly from patients suffering from ciliopathies. Such models help us in investigating pathological mechanisms specific to human physiology and in developing novel therapeutic approaches. In this article, we review current protocols to differentiate human pluripotent stem cells into retinal cell types, and discuss how these cellular and/or organoid models can be utilized to interrogate pathobiology of ciliopathies affecting the retina and for testing prospective treatments.
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Affiliation(s)
- Kamil Kruczek
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, United States.
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, United States.
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Saito M, Otsu W, Miyadera K, Nishimura Y. Recent advances in the understanding of cilia mechanisms and their applications as therapeutic targets. Front Mol Biosci 2023; 10:1232188. [PMID: 37780208 PMCID: PMC10538646 DOI: 10.3389/fmolb.2023.1232188] [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: 05/31/2023] [Accepted: 08/24/2023] [Indexed: 10/03/2023] Open
Abstract
The primary cilium is a single immotile microtubule-based organelle that protrudes into the extracellular space. Malformations and dysfunctions of the cilia have been associated with various forms of syndromic and non-syndromic diseases, termed ciliopathies. The primary cilium is therefore gaining attention due to its potential as a therapeutic target. In this review, we examine ciliary receptors, ciliogenesis, and ciliary trafficking as possible therapeutic targets. We first discuss the mechanisms of selective distribution, signal transduction, and physiological roles of ciliary receptors. Next, pathways that regulate ciliogenesis, specifically the Aurora A kinase, mammalian target of rapamycin, and ubiquitin-proteasome pathways are examined as therapeutic targets to regulate ciliogenesis. Then, in the photoreceptors, the mechanism of ciliary trafficking which takes place at the transition zone involving the ciliary membrane proteins is reviewed. Finally, some of the current therapeutic advancements highlighting the role of large animal models of photoreceptor ciliopathy are discussed.
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Affiliation(s)
- Masaki Saito
- Department of Molecular Physiology and Pathology, School of Pharma-Sciences, Teikyo University, Tokyo, Japan
| | - Wataru Otsu
- Department of Biomedical Research Laboratory, Gifu Pharmaceutical University, Gifu, Japan
| | - Keiko Miyadera
- Department of Clinical Sciences and Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yuhei Nishimura
- Department of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
- Mie University Research Center for Cilia and Diseases, Tsu, Mie, Japan
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8
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Zufiaurre-Seijo M, García-Arumí J, Duarri A. Clinical and Molecular Aspects of C2orf71/PCARE in Retinal Diseases. Int J Mol Sci 2023; 24:10670. [PMID: 37445847 DOI: 10.3390/ijms241310670] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Mutations in the photoreceptor-specific C2orf71 gene (also known as photoreceptor cilium actin regulator protein PCARE) cause autosomal recessive retinitis pigmentosa type 54 and cone-rod dystrophy. No treatments are available for patients with C2orf71 retinal ciliopathies exhibiting a severe clinical phenotype. Our understanding of the disease process and the role of PCARE in the healthy retina significantly limits our capacity to transfer recent technical developments into viable therapy choices. This study summarizes the current understanding of C2orf71-related retinal diseases, including their clinical manifestations and an unclear genotype-phenotype correlation. It discusses molecular and functional studies on the photoreceptor-specific ciliary PCARE, focusing on the photoreceptor cell and its ciliary axoneme. It is proposed that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane during the development of a new outer segment disk in photoreceptor cells. This review also introduces various cellular and animal models used to model these diseases and provides an overview of potential treatments.
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Affiliation(s)
- Maddalen Zufiaurre-Seijo
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - José García-Arumí
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
| | - Anna Duarri
- Ophthalmology Research Group, Vall d'Hebron Institut de Recerca (VHIR), Vall d'Hebron Hospital Universitari, 08035 Barcelona, Spain
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9
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Melluso A, Secondulfo F, Capolongo G, Capasso G, Zacchia M. Bardet-Biedl Syndrome: Current Perspectives and Clinical Outlook. Ther Clin Risk Manag 2023; 19:115-132. [PMID: 36741589 PMCID: PMC9896974 DOI: 10.2147/tcrm.s338653] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/20/2023] [Indexed: 02/04/2023] Open
Abstract
The Bardet Biedl syndrome (BBS) is a rare inherited disorder considered a model of non-motile ciliopathy. It is in fact caused by mutations of genes encoding for proteins mainly localized to the base of the cilium. Clinical features of BBS patients are widely shared with patients suffering from other ciliopathies, especially autosomal recessive syndromic disorders; moreover, mutations in cilia-related genes can cause different clinical ciliopathy entities. Besides the best-known clinical features, as retinal degeneration, learning disabilities, polydactyly, obesity and renal defects, several additional clinical signs have been reported in BBS, expanding our understanding of the complexity of its clinical spectrum. The present review aims to describe the current knowledge of BBS i) pathophysiology, ii) clinical manifestations, highlighting both the most common and the less described features, iii) current and future perspective for treatment.
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Affiliation(s)
- Andrea Melluso
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Floriana Secondulfo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Giovanna Capolongo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Giovambattista Capasso
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy,Biogem Scarl, Ariano Irpino, AV, 83031, Italy
| | - Miriam Zacchia
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy,Correspondence: Miriam Zacchia, Via Pansini 5, Naples, 80131, Italy, Tel +39 081 566 6650, Fax +39 081 566 6671, Email
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10
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Delvallée C, Dollfus H. Retinal Degeneration Animal Models in Bardet-Biedl Syndrome and Related Ciliopathies. Cold Spring Harb Perspect Med 2023; 13:13/1/a041303. [PMID: 36596648 PMCID: PMC9808547 DOI: 10.1101/cshperspect.a041303] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Retinal degeneration due to photoreceptor ciliary-related proteins dysfunction accounts for more than 25% of all inherited retinal dystrophies. The cilium, being an evolutionarily conserved and ubiquitous organelle implied in many cellular functions, can be investigated by way of many models from invertebrate models to nonhuman primates, all these models have massively contributed to the pathogenesis understanding of human ciliopathies. Taking the Bardet-Biedl syndrome (BBS) as an emblematic example as well as other related syndromic ciliopathies, the contribution of a wide range of models has enabled to characterize the role of the BBS proteins in the archetypical cilium but also at the level of the connecting cilium of the photoreceptors. There are more than 24 BBS genes encoding for proteins that form different complexes such as the BBSome and the chaperone proteins complex. But how they lead to retinal degeneration remains a matter of debate with the possible accumulation of proteins in the inner segment and/or accumulation of unwanted proteins in the outer segment that cannot return in the inner segment machinery. Many BBS proteins (but not the chaperonins for instance) can be modeled in primitive organisms such as Paramecium, Chlamydomonas reinardtii, Trypanosoma brucei, and Caenorhabditis elegans These models have enabled clarifying the role of a subset of BBS proteins in the primary cilium as well as their relations with other modules such as the intraflagellar transport (IFT) module, the nephronophthisis (NPHP) module, or the Meckel-Gruber syndrome (MKS)/Joubert syndrome (JBTS) module mostly involved with the transition zone of the primary cilia. Assessing the role of the primary cilia structure of the connecting cilium of the photoreceptor cells has been very much studied by way of zebrafish modeling (Danio rerio) as well as by a plethora of mouse models. More recently, large animal models have been described for three BBS genes and one nonhuman primate model in rhesus macaque for BBS7 In completion to animal models, human cell models can now be used notably thanks to gene editing and the use of induced pluripotent stem cells (iPSCs). All these models are not only important for pathogenesis understanding but also very useful for studying therapeutic avenues, their pros and cons, especially for gene replacement therapy as well as pharmacological triggers.
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Affiliation(s)
- Clarisse Delvallée
- Laboratoire de Génétique Médicale UMRS1112, Centre de Recherche Biomédicale de Strasbourg, CRBS, Institut de Génétique Médicale d'Alsace, IGMA, Strasbourg 67000, France
| | - Hélène Dollfus
- Laboratoire de Génétique Médicale UMRS1112, Centre de Recherche Biomédicale de Strasbourg, CRBS, Institut de Génétique Médicale d'Alsace, IGMA, Strasbourg 67000, France
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11
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Mascibroda LG, Shboul M, Elrod ND, Colleaux L, Hamamy H, Huang KL, Peart N, Singh MK, Lee H, Merriman B, Jodoin JN, Sitaram P, Lee LA, Fathalla R, Al-Rawashdeh B, Ababneh O, El-Khateeb M, Escande-Beillard N, Nelson SF, Wu Y, Tong L, Kenney LJ, Roy S, Russell WK, Amiel J, Reversade B, Wagner EJ. INTS13 variants causing a recessive developmental ciliopathy disrupt assembly of the Integrator complex. Nat Commun 2022; 13:6054. [PMID: 36229431 PMCID: PMC9559116 DOI: 10.1038/s41467-022-33547-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/22/2022] [Indexed: 12/24/2022] Open
Abstract
Oral-facial-digital (OFD) syndromes are a heterogeneous group of congenital disorders characterized by malformations of the face and oral cavity, and digit anomalies. Mutations within 12 cilia-related genes have been identified that cause several types of OFD, suggesting that OFDs constitute a subgroup of developmental ciliopathies. Through homozygosity mapping and exome sequencing of two families with variable OFD type 2, we identified distinct germline variants in INTS13, a subunit of the Integrator complex. This multiprotein complex associates with RNA Polymerase II and cleaves nascent RNA to modulate gene expression. We determined that INTS13 utilizes its C-terminus to bind the Integrator cleavage module, which is disrupted by the identified germline variants p.S652L and p.K668Nfs*9. Depletion of INTS13 disrupts ciliogenesis in human cultured cells and causes dysregulation of a broad collection of ciliary genes. Accordingly, its knockdown in Xenopus embryos leads to motile cilia anomalies. Altogether, we show that mutations in INTS13 cause an autosomal recessive ciliopathy, which reveals key interactions between components of the Integrator complex.
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Affiliation(s)
- Lauren G Mascibroda
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Mohammad Shboul
- Department of Medical Laboratory Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | - Nathan D Elrod
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Laurence Colleaux
- Inserm UMR 1163, Institut Imagine, 24 Boulevard du Montparnasse, 75015, Paris, France
| | - Hanan Hamamy
- Department of Genetic Medicine and Development, University Hospital, Geneva, Switzerland
| | - Kai-Lieh Huang
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine Dentistry, Rochester, NY, 14642, USA
- Center for RNA Biology, University of Rochester School of Medicine Dentistry, Rochester, NY, 14642, USA
| | - Natoya Peart
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Moirangthem Kiran Singh
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Hane Lee
- Department of Pathology and Laboratory Medicine, Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
- 3billion, Inc., Seoul, South Korea
| | - Barry Merriman
- Department of Pathology and Laboratory Medicine, Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Jeanne N Jodoin
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Poojitha Sitaram
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Laura A Lee
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Raja Fathalla
- National Center for Diabetes, Endocrinology and Genetics, Amman, Jordan
| | - Baeth Al-Rawashdeh
- Faculty of Medicine, Hospital of the University of Jordan, University of Jordan, Amman, Jordan
| | - Osama Ababneh
- Faculty of Medicine, Hospital of the University of Jordan, University of Jordan, Amman, Jordan
| | | | - Nathalie Escande-Beillard
- Department of Medical Genetics, KOÇ University, Istanbul, Turkey
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore
| | - Stanley F Nelson
- Department of Pathology and Laboratory Medicine, Department of Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Yixuan Wu
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Linda J Kenney
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Sudipto Roy
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore
- Department of Paediatrics, School of Medicine, NUS, Singapore, Singapore
- Department of Biological Sciences, Faculty of Science, NUS, Singapore, Singapore
| | - William K Russell
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA
| | - Jeanne Amiel
- Service de Génétique, Institut Imagine, 24 Boulevard du Montparnasse, 75015, Paris, France
| | - Bruno Reversade
- Department of Medical Genetics, KOÇ University, Istanbul, Turkey.
- Institute of Molecular and Cell Biology, A*STAR, Singapore, Singapore.
- Department of Paediatrics, School of Medicine, NUS, Singapore, Singapore.
- Smart-Health Initiative, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
- Laboratory of Human Genetics & Therapeutics, Genome Institute of Singapore, A*STAR, Singapore, 137673, Singapore.
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch at Galveston, Galveston, TX, 77550, USA.
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine Dentistry, Rochester, NY, 14642, USA.
- Center for RNA Biology, University of Rochester School of Medicine Dentistry, Rochester, NY, 14642, USA.
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12
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Nazlamova L, Villa Vasquez SS, Lord J, Karthik V, Cheung MK, Lakowski J, Wheway G. Microtubule modification defects underlie cilium degeneration in cell models of retinitis pigmentosa associated with pre-mRNA splicing factor mutations. Front Genet 2022; 13:1009430. [PMID: 36176300 PMCID: PMC9513239 DOI: 10.3389/fgene.2022.1009430] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 08/19/2022] [Indexed: 11/17/2022] Open
Abstract
Retinitis pigmentosa (RP) is the most common cause of hereditary blindness, and may occur in isolation as a non-syndromic condition or alongside other features in a syndromic presentation. Biallelic or monoallelic mutations in one of eight genes encoding pre-mRNA splicing factors are associated with non-syndromic RP. The molecular mechanism of disease remains incompletely understood, limiting opportunities for targeted treatment. Here we use CRISPR and base edited PRPF6 and PRPF31 mutant cell lines, and publicly-available data from human PRPF31+/− patient derived retinal organoids and PRPF31 siRNA-treated organotypic retinal cultures to confirm an enrichment of differential splicing of microtubule, centrosomal, cilium and DNA damage response pathway genes in these cells. We show that genes with microtubule/centrosome/centriole/cilium gene ontology terms are enriched for weak 3′ and 5′ splice sites, and that subtle defects in spliceosome activity predominantly affect efficiency of splicing of these exons. We suggest that the primary defect in PRPF6 or PRPF31 mutant cells is microtubule and centrosomal defects, leading to defects in cilium and mitotic spindle stability, with the latter leading to DNA damage, triggering differential splicing of DNA damage response genes to activate this pathway. Finally, we expand understanding of “splicing factor RP” by investigating the function of TTLL3, one of the most statistically differentially expressed genes in PRPF6 and PRPF31 mutant cells. We identify that TTLL3 is the only tubulin glycylase expressed in the human retina, essential for monoglycylation of microtubules of the cilium, including the retinal photoreceptor cilium, to prevent cilium degeneration and retinal degeneration. Our preliminary data suggest that rescue of tubulin glycylation through overexpression of TTLL3 is sufficient to rescue cilium number in PRPF6 and PRPF31 mutant cells, suggesting that this defect underlies the cellular defect and may represent a potential target for therapeutic intervention in this group of disorders.
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Affiliation(s)
- Liliya Nazlamova
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Suly Saray Villa Vasquez
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Jenny Lord
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Varshini Karthik
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Man-Kim Cheung
- Centre for Research in Biosciences, University of the West of England, Bristol, United Kingdom
| | - Jörn Lakowski
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Gabrielle Wheway
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
- *Correspondence: Gabrielle Wheway,
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13
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Mayer SK, Thomas J, Helms M, Kothapalli A, Cherascu I, Salesevic A, Stalter E, Wang K, Datta P, Searby C, Seo S, Hsu Y, Bhattarai S, Sheffield VC, Drack AV. Progressive retinal degeneration of rods and cones in a Bardet-Biedl syndrome type 10 mouse model. Dis Model Mech 2022; 15:dmm049473. [PMID: 36125046 PMCID: PMC9536196 DOI: 10.1242/dmm.049473] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/03/2022] [Indexed: 11/23/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is a multi-organ autosomal-recessive disorder caused by mutations in at least 22 different genes. A constant feature is early-onset retinal degeneration leading to blindness. Among the most common forms is BBS type 10 (BBS10), which is caused by mutations in a gene encoding a chaperonin-like protein. To aid in developing treatments, we phenotyped a Bbs10 knockout (Bbs10-/-) mouse model. Analysis by optical coherence tomography (OCT), electroretinography (ERG) and a visually guided swim assay (VGSA) revealed a progressive degeneration (from P19 to 8 months of age) of the outer nuclear layer that is visible by OCT and histology. Cone ERG was absent from at least P30, at which time rod ERG was reduced to 74.4% of control levels; at 8 months, rod ERG was 2.3% of that of controls. VGSA demonstrated loss of functional vision at 9 months. These phenotypes progressed more rapidly than retinal degeneration in the Bbs1M390R/M390R knock-in mouse. This study defines endpoints for preclinical trials that can be utilized to detect a treatment effect in the Bbs10-/- mouse and extrapolated to human clinical trials.
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Affiliation(s)
- Sara K. Mayer
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Jacintha Thomas
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Megan Helms
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Aishwarya Kothapalli
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Ioana Cherascu
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Adisa Salesevic
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Elliot Stalter
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Kai Wang
- Department of Biostatistics, University of Iowa, Iowa City, IA 52242, USA
| | - Poppy Datta
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Charles Searby
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Ying Hsu
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Sajag Bhattarai
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
| | - Val C. Sheffield
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
| | - Arlene V. Drack
- Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA
- Department of Pediatrics, University of Iowa, Iowa City, IA 52242, USA
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14
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Best S, Lord J, Roche M, Watson CM, Poulter JA, Bevers RPJ, Stuckey A, Szymanska K, Ellingford JM, Carmichael J, Brittain H, Toomes C, Inglehearn C, Johnson CA, Wheway G. Molecular diagnoses in the congenital malformations caused by ciliopathies cohort of the 100,000 Genomes Project. J Med Genet 2022; 59:737-747. [PMID: 34716235 PMCID: PMC9340050 DOI: 10.1136/jmedgenet-2021-108065] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/27/2021] [Indexed: 12/19/2022]
Abstract
BACKGROUND Primary ciliopathies represent a group of inherited disorders due to defects in the primary cilium, the 'cell's antenna'. The 100,000 Genomes Project was launched in 2012 by Genomics England (GEL), recruiting National Health Service (NHS) patients with eligible rare diseases and cancer. Sequence data were linked to Human Phenotype Ontology (HPO) terms entered by recruiting clinicians. METHODS Eighty-three prescreened probands were recruited to the 100,000 Genomes Project suspected to have congenital malformations caused by ciliopathies in the following disease categories: Bardet-Biedl syndrome (n=45), Joubert syndrome (n=14) and 'Rare Multisystem Ciliopathy Disorders' (n=24). We implemented a bespoke variant filtering and analysis strategy to improve molecular diagnostic rates for these participants. RESULTS We determined a research molecular diagnosis for n=43/83 (51.8%) probands. This is 19.3% higher than previously reported by GEL (n=27/83 (32.5%)). A high proportion of diagnoses are due to variants in non-ciliopathy disease genes (n=19/43, 44.2%) which may reflect difficulties in clinical recognition of ciliopathies. n=11/83 probands (13.3%) had at least one causative variant outside the tiers 1 and 2 variant prioritisation categories (GEL's automated triaging procedure), which would not be reviewed in standard 100,000 Genomes Project diagnostic strategies. These include four structural variants and three predicted to cause non-canonical splicing defects. Two unrelated participants have biallelic likely pathogenic variants in LRRC45, a putative novel ciliopathy disease gene. CONCLUSION These data illustrate the power of linking large-scale genome sequence to phenotype information. They demonstrate the value of research collaborations in order to maximise interpretation of genomic data.
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Affiliation(s)
- Sunayna Best
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
- Department of Clinical Genetics, Leeds Teaching Hospitals NHS Trust, Leeds, UK
| | - Jenny Lord
- Department of Human Development and Health, University of Southampton Faculty of Medicine, Southampton, UK
- University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | - Christopher M Watson
- Department of Yorkshire Regional Genetics Service, Leeds Teaching Hospitals NHS Trust, Leeds, West Yorkshire, UK
- School of Medicine, University of Leeds, Leeds, UK
| | - James A Poulter
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
| | - Roel P J Bevers
- Genomics England, Queen Mary University of London, London, UK
| | - Alex Stuckey
- Genomics England, Queen Mary University of London, London, UK
| | - Katarzyna Szymanska
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
| | - Jamie M Ellingford
- Division of Evolution and Genomic Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Manchester Centre for Genomic Medicine, Manchester, UK
| | - Jenny Carmichael
- East Anglian Medical Genetics Service, Addenbrooke's Hospital, Cambridge, UK
| | - Helen Brittain
- Genomics England, Queen Mary University of London, London, UK
| | - Carmel Toomes
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
| | - Chris Inglehearn
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
| | - Colin A Johnson
- Division of Molecular Medicine, University of Leeds Leeds Institute of Medical Research at St James's, Leeds, West Yorkshire, UK
| | - Gabrielle Wheway
- Department of Human Development and Health, University of Southampton Faculty of Medicine, Southampton, UK
- Southampton University Hospitals NHS Trust, Southampton, UK
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15
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Lindemann CB. The flagellar germ-line hypothesis: How flagellate and ciliate gametes significantly shaped the evolution of organismal complexity. Bioessays 2021; 44:e2100143. [PMID: 34967029 DOI: 10.1002/bies.202100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 12/10/2021] [Accepted: 12/15/2021] [Indexed: 11/10/2022]
Abstract
This essay presents a hypothesis which contends that the development of organismic complexity in the eukaryotes depended extensively on propagation via flagellated and ciliated gametes. Organisms utilizing flagellate and ciliate gametes to propagate their germ line have contributed most of the organismic complexity found in the higher animals. The genes of the flagellum and the flagellar assembly system (intraflagellar transport) have played a disproportionately important role in the construction of complex tissues and organs. The hypothesis also proposes that competition between large numbers of haploid flagellated male gametes rigorously conserved the functionality of a key set of flagellar genes for more than 700 million years. This in turn has insured that a large set (>600) of highly functional cytoskeletal and signal pathway genes is always present in the lineage of organisms with flagellated or ciliated gametes to act as a dependable resource, or "toolkit," for organ elaboration.
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Chandra B, Tung ML, Hsu Y, Scheetz T, Sheffield VC. Retinal ciliopathies through the lens of Bardet-Biedl Syndrome: Past, present and future. Prog Retin Eye Res 2021; 89:101035. [PMID: 34929400 DOI: 10.1016/j.preteyeres.2021.101035] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 12/15/2022]
Abstract
The primary cilium is a highly specialized and evolutionary conserved organelle in eukaryotes that plays a significant role in cell signaling and trafficking. Over the past few decades tremendous progress has been made in understanding the physiology of cilia and the underlying pathomechanisms of various ciliopathies. Syndromic ciliopathies consist of a group of disorders caused by ciliary dysfunction or abnormal ciliogenesis. These disorders have multiorgan involvement in addition to retinal degeneration underscoring the ubiquitous distribution of primary cilia in different cell types. Genotype-phenotype correlation is often challenging due to the allelic heterogeneity and pleiotropy of these disorders. In this review, we discuss the clinical and genetic features of syndromic ciliopathies with a focus on Bardet-Biedl syndrome (BBS) as a representative disorder. We discuss the structure and function of primary cilia and their role in retinal photoreceptors. We describe the progress made thus far in understanding the functional and genetic characterization including expression quantitative trait locus (eQTL) analysis of BBS genes. In the future directions section, we discuss the emerging technologies, such as gene therapy, as well as anticipated challenges and their implications in therapeutic development for ciliopathies.
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Affiliation(s)
- Bharatendu Chandra
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Moon Ley Tung
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ying Hsu
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA
| | - Todd Scheetz
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA
| | - Val C Sheffield
- Stead Family Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Carver College of Medicine, Iowa City, IA, USA; Department of Ophthalmology and Visual Sciences, Carver College of Medicine, Iowa City, IA, USA.
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Primary Cilia Structure Is Prolonged in Enteric Neurons of 5xFAD Alzheimer's Disease Model Mice. Int J Mol Sci 2021; 22:ijms222413564. [PMID: 34948356 PMCID: PMC8707868 DOI: 10.3390/ijms222413564] [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: 11/09/2021] [Revised: 12/09/2021] [Accepted: 12/15/2021] [Indexed: 02/06/2023] Open
Abstract
Neurodegenerative diseases such as Alzheimer’s disease (AD) have long been acknowledged as mere disorders of the central nervous system (CNS). However, in recent years the gut with its autonomous nervous system and the multitude of microbial commensals has come into focus. Changes in gut properties have been described in patients and animal disease models such as altered enzyme secretion or architecture of the enteric nervous system. The underlying cellular mechanisms have so far only been poorly investigated. An important organelle for integrating potentially toxic signals such as the AD characteristic A-beta peptide is the primary cilium. This microtubule-based signaling organelle regulates numerous cellular processes. Even though the role of primary cilia in a variety of developmental and disease processes has recently been recognized, the contribution of defective ciliary signaling to neurodegenerative diseases such as AD, however, has not been investigated in detail so far. The AD mouse model 5xFAD was used to analyze possible changes in gut functionality by organ bath measurement of peristalsis movement. Subsequently, we cultured primary enteric neurons from mutant mice and wild type littermate controls and assessed for cellular pathomechanisms. Neurite mass was quantified within transwell culturing experiments. Using a combination of different markers for the primary cilium, cilia number and length were determined using fluorescence microscopy. 5xFAD mice showed altered gut anatomy, motility, and neurite mass of enteric neurons. Moreover, primary cilia could be demonstrated on the surface of enteric neurons and exhibited an elongated phenotype in 5xFAD mice. In parallel, we observed reduced β-Catenin expression, a key signaling molecule that regulates Wnt signaling, which is regulated in part via ciliary associated mechanisms. Both results could be recapitulated via in vitro treatments of enteric neurons from wild type mice with A-beta. So far, only a few reports on the probable role of primary cilia in AD can be found. Here, we reveal for the first time an architectural altered phenotype of primary cilia in the enteric nervous system of AD model mice, elicited potentially by neurotoxic A-beta. Potential changes on the sub-organelle level—also in CNS-derived neurons—require further investigations.
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Grudzinska Pechhacker MK, Jacobson SG, Drack AV, Scipio MD, Strubbe I, Pfeifer W, Duncan JL, Dollfus H, Goetz N, Muller J, Vincent AL, Aleman TS, Tumber A, Van Cauwenbergh C, De Baere E, Bedoukian E, Leroy BP, Maynes JT, Munier FL, Tavares E, Saleh E, Vincent A, Heon E. Comparative Natural History of Visual Function From Patients With Biallelic Variants in BBS1 and BBS10. Invest Ophthalmol Vis Sci 2021; 62:26. [PMID: 34940782 PMCID: PMC8711006 DOI: 10.1167/iovs.62.15.26] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to compare the natural history of visual function change in cohorts of patients affected with retinal degeneration due to biallelic variants in Bardet-Biedl syndrome genes: BBS1 and BBS10. Methods Patients were recruited from nine academic centers from six countries (Belgium, Canada, France, New Zealand, Switzerland, and the United States). Inclusion criteria were: (1) female or male patients with a clinical diagnosis of retinal dystrophy, (2) biallelic disease-causing variants in BBS1 or BBS10, and (3) measures of visual function for at least one visit. Retrospective data collected included genotypes, age, onset of symptoms, and best corrected visual acuity (VA). When possible, data on refractive error, fundus images and autofluorescence (FAF), optical coherence tomography (OCT), Goldmann kinetic perimetry (VF), electroretinography (ERG), and the systemic phenotype were collected. Results Sixty-seven individuals had variants in BBS1 (n = 38; 20 female patients and 18 male patients); or BBS10 (n = 29; 14 female patients and 15 male patients). Missense variants were the most common type of variants for patients with BBS1, whereas frameshift variants were most common for BBS10. When ERGs were recordable, rod-cone dystrophy (RCD) was observed in 82% (23/28) of patients with BBS1 and 73% (8/11) of patients with BBS10; cone-rod dystrophy (CORD) was seen in 18% of patients with BBS1 only, and cone dystrophy (COD) was only seen in 3 patients with BBS10 (27%). ERGs were nondetectable earlier in patients with BBS10 than in patients with BBS1. Similarly, VA and VF declined more rapidly in patients with BBS10 compared to patients with BBS1. Conclusions Retinal degeneration appears earlier and is more severe in BBS10 cases as compared to those with BBS1 variants. The course of change of visual function appears to relate to genetic subtypes of BBS.
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Affiliation(s)
- Monika K Grudzinska Pechhacker
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Arlene V Drack
- Department of Ophthalmology, Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
| | - Matteo Di Scipio
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Ine Strubbe
- Department of Ophthalmology, Ghent University Hospital & Department of Head and Skin, Ghent University, Ghent, Belgium
| | - Wanda Pfeifer
- Department of Ophthalmology, Institute for Vision Research, University of Iowa, Iowa City, Iowa, United States
| | - Jacque L Duncan
- Department of Ophthalmology, University of California, San Francisco, San Francisco, California, United States
| | - Helene Dollfus
- CARGO ( Centre de référence pour les affections rares génétiques ), IGMA Institut de Génétqiue Médicale d'Alsace , Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,UMRS_1112, IGMA ( Institut de génétique Médicale d'Alsace ) Université de Strasbourg, Strasbourg, France
| | - Nathalie Goetz
- UMRS_1112, IGMA ( Institut de génétique Médicale d'Alsace ) Université de Strasbourg, Strasbourg, France
| | - Jean Muller
- CARGO ( Centre de référence pour les affections rares génétiques ), IGMA Institut de Génétqiue Médicale d'Alsace , Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,UMRS_1112, IGMA ( Institut de génétique Médicale d'Alsace ) Université de Strasbourg, Strasbourg, France.,Laboratoire de diagnostique génétique, IGMA ( Institut de génétique Médicale d'Alsace ) Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Andrea L Vincent
- Department of Ophthalmology, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand.,Eye Department, Greenlane Clinical Centre, Auckland District Health Board, Auckland, New Zealand
| | - Tomas S Aleman
- Center for Advanced Retinal and Ocular Therapeutics, Perelman School of Medicine, Philadelphia, Pennsylvania, United States.,Scheie Eye Institute at the Perelman Center for Advanced Medicine, Philadelphia, Pennsylvania, United States.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada
| | - Caroline Van Cauwenbergh
- Department of Ophthalmology, Ghent University Hospital & Department of Head and Skin, Ghent University, Ghent, Belgium.,Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Elfride De Baere
- Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Emma Bedoukian
- Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Bart P Leroy
- Department of Ophthalmology, Ghent University Hospital & Department of Head and Skin, Ghent University, Ghent, Belgium.,Center for Advanced Retinal and Ocular Therapeutics, Perelman School of Medicine, Philadelphia, Pennsylvania, United States.,Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States.,Center for Medical Genetics, Ghent University and Ghent University Hospital, Ghent, Belgium.,Center for Molecular Therapeutics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States
| | - Jason T Maynes
- Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.,Departments of Biochemistry and Anesthesiology and Pain Medicine, University of Toronto, Program in Molecular Medicine, The Hospital for Sick Children, Toronto, Canada
| | - Francis L Munier
- Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, University of Lausanne, Lausanne, Switzerland
| | - Erika Tavares
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.,Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Eman Saleh
- Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Ajoy Vincent
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada.,Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
| | - Elise Heon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Canada.,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Canada.,Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Canada
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19
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cGMP-PKG dependent transcriptome in normal and degenerating retinas: Novel insights into the retinitis pigmentosa pathology. Exp Eye Res 2021; 212:108752. [PMID: 34478738 DOI: 10.1016/j.exer.2021.108752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 06/25/2021] [Accepted: 08/25/2021] [Indexed: 12/26/2022]
Abstract
Retinitis Pigmentosa represents a group of genetic disorders that cause progressive vision loss via degeneration of photoreceptors, but there is in principle no treatment available. For any therapy development, a deeper comprehension of the disease-leading mechanism(s) at the molecular level is needed. Here we focused on the cGMP-PKG system, which has been suggested to be a driver in several models of the disease. To gain insights in its downstream signaling we manipulated the cGMP-PKG system with the aid of organotypic retinal explant cultures from either a mouse-based disease model, i.e. the rd1 mouse, or its healthy wild-type counterpart (wt), by adding different types of cGMP analogues to either inhibit or activate PKG in retinal explants from rd1 and wt, respectively. An RNA sequencing was then performed to study the cGMP-PKG dependent transcriptome. Expression changes of gene sets related to specific pathways or functions, that fulfilled criteria involving that the changes should match PKG activation and inhibition, were determined via bioinformatics. The analyses highlighted that several gene sets linked to oxidative phosphorylation and mitochondrial pathways were regulated by this enzyme system. Specifically, the expression of such pathway components was upregulated in the rd1 treated with PKG inhibitor and downregulated in the wt with PKG activator treatment, suggesting that cGMP-PKG act as a negative regulator in this context. Downregulation of energy production pathways may thus play an integral part in the mechanism behind the degeneration for at least several RP mutations.
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20
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Datta P, Ruffcorn A, Seo S. Limited time window for retinal gene therapy in a preclinical model of ciliopathy. Hum Mol Genet 2021; 29:2337-2352. [PMID: 32568387 DOI: 10.1093/hmg/ddaa124] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/04/2020] [Accepted: 06/15/2020] [Indexed: 12/15/2022] Open
Abstract
Retinal degeneration is a common clinical feature of ciliopathies, a group of genetic diseases linked to ciliary dysfunction, and gene therapy is an attractive treatment option to prevent vision loss. Although the efficacy of retinal gene therapy is well established by multiple proof-of-concept preclinical studies, its long-term effect, particularly when treatments are given at advanced disease stages, is controversial. Incomplete treatment and intrinsic variability of gene delivery methods may contribute to the variable outcomes. Here, we used a genetic rescue approach to 'optimally' treat retinal degeneration at various disease stages and examined the long-term efficacy of gene therapy in a mouse model of ciliopathy. We used a Bardet-Biedl syndrome type 17 (BBS17) mouse model, in which the gene-trap that suppresses Bbs17 (also known as Lztfl1) expression can be removed by tamoxifen administration, restoring normal gene expression systemically. Our data indicate that therapeutic effects of retinal gene therapy decrease gradually as treatments are given at later stages. These results suggest the presence of limited time window for successful gene therapy in certain retinal degenerations. Our study also implies that the long-term efficacy of retinal gene therapy may depend on not only the timing of treatment but also other factors such as the function of mutated genes and residual activities of mutant alleles.
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Affiliation(s)
- Poppy Datta
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.,Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA
| | - Avri Ruffcorn
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.,Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA
| | - Seongjin Seo
- Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.,Institute for Vision Research, The University of Iowa, Iowa City, IA 52242, USA
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21
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Focșa IO, Budișteanu M, Bălgrădean M. Clinical and genetic heterogeneity of primary ciliopathies (Review). Int J Mol Med 2021; 48:176. [PMID: 34278440 PMCID: PMC8354309 DOI: 10.3892/ijmm.2021.5009] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 06/28/2021] [Indexed: 01/11/2023] Open
Abstract
Ciliopathies comprise a group of complex disorders, with involvement of the majority of organs and systems. In total, >180 causal genes have been identified and, in addition to Mendelian inheritance, oligogenicity, genetic modifications, epistatic interactions and retrotransposon insertions have all been described when defining the ciliopathic phenotype. It is remarkable how the structural and functional impairment of a single, minuscule organelle may lead to the pathogenesis of highly pleiotropic diseases. Thus, combined efforts have been made to identify the genetic substratum and to determine the pathophysiological mechanism underlying the clinical presentation, in order to diagnose and classify ciliopathies. Yet, predicting the phenotype, given the intricacy of the genetic cause and overlapping clinical characteristics, represents a major challenge. In the future, advances in proteomics, cell biology and model organisms may provide new insights that could remodel the field of ciliopathies.
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Affiliation(s)
- Ina Ofelia Focșa
- Department of Medical Genetics, University of Medicine and Pharmacy 'Carol Davila', 021901 Bucharest, Romania
| | - Magdalena Budișteanu
- Department of Pediatric Neurology, 'Prof. Dr. Alexandru Obregia' Clinical Hospital of Psychiatry, 041914 Bucharest, Romania
| | - Mihaela Bălgrădean
- Department of Pediatrics and Pediatric Nephrology, Emergency Clinical Hospital for Children 'Maria Skłodowska Curie', 077120 Bucharest, Romania
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22
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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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23
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Koyanagi Y, Ueno S, Ito Y, Kominami T, Komori S, Akiyama M, Murakami Y, Ikeda Y, Sonoda KH, Terasaki H. Relationship Between Macular Curvature and Common Causative Genes of Retinitis Pigmentosa in Japanese Patients. Invest Ophthalmol Vis Sci 2021; 61:6. [PMID: 32749464 PMCID: PMC7441377 DOI: 10.1167/iovs.61.10.6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To determine the relationship between the macular curvature and the causative genes of retinitis pigmentosa (RP). Methods We examined the medical records of the right eyes of 65 cases with RP (31 men and 34 women; average age, 47.6 years). There were 31 cases with the EYS variants, 11 cases with the USH2A variants, six cases with the RPGR variants, 13 cases with the RP1 variants, and four cases with the RP1L1 variants. The mean curvature of Bruch's membrane was calculated within 6 mm of the fovea as the mean macular curvature index (MMCI, 1/µm). We used multiple linear regression analysis to determine the independence of the causative genes contributing to the MMCIs after adjustments for age, sex, axial length, and width of the ellipsoid zone. Results The median MMCI was −31.2 × 10−5/µm for the RPGR eyes, −16.5 × 10−5/µm for the RP1L1 eyes, −13.0 × 10−5/µm for the RP1 eyes, −9.8 × 10−5/µm for the EYS eyes, and −9.0 × 10−5/µm for the USH2A eyes. Compared with the EYS gene as the reference gene, the RPGR gene was significantly related to the MMCI values after adjusting for the other parameters (P = 5.30 × 10−6). In contrast, the effects of the other genes, USH2A, RP1, and RP1L1, were not significantly different from that of the EYS gene (P = 0.26, P = 0.49, and P = 0.92, respectively). Conclusions The RPGR gene had a stronger effect on the steep macular curvature than the other ciliopathy-related genes.
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24
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Hargrove-Grimes P, Mondal AK, Gumerson J, Nellissery J, Aponte AM, Gieser L, Qian H, Fariss RN, Bonifacino JS, Li T, Swaroop A. Loss of endocytosis-associated RabGEF1 causes aberrant morphogenesis and altered autophagy in photoreceptors leading to retinal degeneration. PLoS Genet 2020; 16:e1009259. [PMID: 33362196 PMCID: PMC7790415 DOI: 10.1371/journal.pgen.1009259] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 01/07/2021] [Accepted: 11/09/2020] [Indexed: 12/17/2022] Open
Abstract
Rab-GTPases and associated effectors mediate cargo transport through the endomembrane system of eukaryotic cells, regulating key processes such as membrane turnover, signal transduction, protein recycling and degradation. Using developmental transcriptome data, we identified Rabgef1 (encoding the protein RabGEF1 or Rabex-5) as the only gene associated with Rab GTPases that exhibited strong concordance with retinal photoreceptor differentiation. Loss of Rabgef1 in mice (Rabgef1-/-) resulted in defects specifically of photoreceptor morphology and almost complete loss of both rod and cone function as early as eye opening; however, aberrant outer segment formation could only partly account for visual function deficits. RabGEF1 protein in retinal photoreceptors interacts with Rabaptin-5, and RabGEF1 absence leads to reduction of early endosomes consistent with studies in other mammalian cells and tissues. Electron microscopy analyses reveal abnormal accumulation of macromolecular aggregates in autophagosome-like vacuoles and enhanced immunostaining for LC3A/B and p62 in Rabgef1-/- photoreceptors, consistent with compromised autophagy. Transcriptome analysis of the developing Rabgef1-/- retina reveals altered expression of 2469 genes related to multiple pathways including phototransduction, mitochondria, oxidative stress and endocytosis, suggesting an early trajectory of photoreceptor cell death. Our results implicate an essential role of the RabGEF1-modulated endocytic and autophagic pathways in photoreceptor differentiation and homeostasis. We propose that RabGEF1 and associated components are potential candidates for syndromic traits that include a retinopathy phenotype. Endocytosis and autophagy are evolutionarily conserved processes that are essential for maintenance of cellular homeostasis. RabGEF1 is a major regulator of the Rab5-GTPase, which participates in key steps during endocytosis and autophagy. We demonstrate that loss of RabGEF1 in mice causes specific developmental defects during photoreceptor outer segment formation, leading to visual dysfunction as early as eye opening followed by retinal degeneration. Rabgef1-/- retina shows a clear reduction in early endosomes as well as accumulation of autophagic vacuoles in developing photoreceptors. Together with transcriptome analysis, our studies suggest a trajectory of cellular events including altered autophagy that precede photoreceptor cell death in the absence of RabGEF1 and establish a critical role of endocytosis and autophagy in retinal development and proteostasis.
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Affiliation(s)
- Passley Hargrove-Grimes
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Institute of Biomedical Sciences, George Washington University, Washington, District of Columbia, United States of America
| | - Anupam K. Mondal
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jessica Gumerson
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jacob Nellissery
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Angel M. Aponte
- Proteomics Core, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Linn Gieser
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Haohua Qian
- Visual Function Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Robert N. Fariss
- Biological Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Juan S. Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute for Child Health and Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tiansen Li
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Anand Swaroop
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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25
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Brücker L, Kretschmer V, May-Simera HL. The entangled relationship between cilia and actin. Int J Biochem Cell Biol 2020; 129:105877. [PMID: 33166678 DOI: 10.1016/j.biocel.2020.105877] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/23/2020] [Accepted: 10/26/2020] [Indexed: 12/14/2022]
Abstract
Primary cilia are microtubule-based sensory cell organelles that are vital for tissue and organ development. They act as an antenna, receiving and transducing signals, enabling communication between cells. Defects in ciliogenesis result in severe genetic disorders collectively termed ciliopathies. In recent years, the importance of the direct and indirect involvement of actin regulators in ciliogenesis came into focus as it was shown that F-actin polymerisation impacts ciliation. The ciliary basal body was further identified as both a microtubule and actin organising centre. In the current review, we summarize recent studies on F-actin in and around primary cilia, focusing on different actin regulators and their effect on ciliogenesis, from the initial steps of basal body positioning and regulation of ciliary assembly and disassembly. Since primary cilia are also involved in several intracellular signalling pathways such as planar cell polarity (PCP), subsequently affecting actin rearrangements, the multiple effectors of this pathway are highlighted in more detail with a focus on the feedback loops connecting actin networks and cilia proteins. Finally, we elucidate the role of actin regulators in the development of ciliopathy symptoms and cancer.
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Affiliation(s)
- Lena Brücker
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, Germany
| | - Viola Kretschmer
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, Germany
| | - Helen Louise May-Simera
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes-Gutenberg University, Mainz, Germany.
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26
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Ran J, Zhou J. Targeting the photoreceptor cilium for the treatment of retinal diseases. Acta Pharmacol Sin 2020; 41:1410-1415. [PMID: 32753732 DOI: 10.1038/s41401-020-0486-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 06/28/2020] [Indexed: 02/08/2023] Open
Abstract
Photoreceptors, as polarised sensory neurons, are essential for light sensation and phototransduction, which are highly dependent on the photoreceptor cilium. Structural defects and/or dysfunction of the photoreceptor cilium caused by mutations in photoreceptor-specific genes or common ciliary genes can lead to retinal diseases, including syndromic and nonsyndromic diseases. In this review, we describe the structure and function of the photoreceptor cilium. We also discuss recent findings that underscore the dysregulation of the photoreceptor cilium in various retinal diseases and the therapeutic potential of targeting ciliary genes in these diseases.
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27
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Nadolski NJ, Balay SD, Wong CXL, Waskiewicz AJ, Hocking JC. Abnormal Cone and Rod Photoreceptor Morphogenesis in gdf6a Mutant Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32293666 PMCID: PMC7401959 DOI: 10.1167/iovs.61.4.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants. Methods Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes. Results Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis. Conclusions GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
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28
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Yu T, Matsuda M. Epb41l5 interacts with Iqcb1 and regulates ciliary function in zebrafish embryos. J Cell Sci 2020; 133:jcs240648. [PMID: 32501287 PMCID: PMC7338265 DOI: 10.1242/jcs.240648] [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: 10/21/2019] [Accepted: 05/13/2020] [Indexed: 11/20/2022] Open
Abstract
Erythrocyte protein band 4.1 like 5 (EPB41L5) is an adaptor protein beneath the plasma membrane that functions to control epithelial morphogenesis. Here we report a previously uncharacterized role of EPB41L5 in controlling ciliary function. We found that EPB41L5 forms a complex with IQCB1 (previously known as NPHP5), a ciliopathy protein. Overexpression of EPB41L5 reduced IQCB1 localization at the ciliary base in cultured mammalian epithelial cells. Conversely, epb41l5 knockdown increased IQCB1 localization at the ciliary base. epb41l5-deficient zebrafish embryos or embryos expressing C-terminally modified forms of Epb41l5 developed cilia with reduced motility and exhibited left-right patterning defects, an outcome of abnormal ciliary function. We observed genetic synergy between epb41l5 and iqcb1. Moreover, EPB41L5 decreased IQCB1 interaction with CEP290, another ciliopathy protein and a component of the ciliary base and centrosome. Together, these observations suggest that EPB41L5 regulates the composition of the ciliary base and centrosome through IQCB1 and CEP290.
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Affiliation(s)
- Tiffany Yu
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ 07302, USA
| | - Miho Matsuda
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ 07302, USA
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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Application of CRISPR Tools for Variant Interpretation and Disease Modeling in Inherited Retinal Dystrophies. Genes (Basel) 2020; 11:genes11050473. [PMID: 32349249 PMCID: PMC7290804 DOI: 10.3390/genes11050473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 04/23/2020] [Accepted: 04/23/2020] [Indexed: 12/27/2022] Open
Abstract
Inherited retinal dystrophies are an assorted group of rare diseases that collectively account for the major cause of visual impairment of genetic origin worldwide. Besides clinically, these vision loss disorders present a high genetic and allelic heterogeneity. To date, over 250 genes have been associated to retinal dystrophies with reported causative variants of every nature (nonsense, missense, frameshift, splice-site, large rearrangements, and so forth). Except for a fistful of mutations, most of them are private and affect one or few families, making it a challenge to ratify the newly identified candidate genes or the pathogenicity of dubious variants in disease-associated loci. A recurrent option involves altering the gene in in vitro or in vivo systems to contrast the resulting phenotype and molecular imprint. To validate specific mutations, the process must rely on simulating the precise genetic change, which, until recently, proved to be a difficult endeavor. The rise of the CRISPR/Cas9 technology and its adaptation for genetic engineering now offers a resourceful suite of tools to alleviate the process of functional studies. Here we review the implementation of these RNA-programmable Cas9 nucleases in culture-based and animal models to elucidate the role of novel genes and variants in retinal dystrophies.
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Krishnan AK, Jacobson SG, Roman AJ, Iyer BS, Garafalo AV, Héon E, Cideciyan AV. Transient pupillary light reflex in CEP290- or NPHP5-associated Leber congenital amaurosis: Latency as a potential outcome measure of cone function. Vision Res 2020; 168:53-63. [PMID: 32088401 PMCID: PMC7068155 DOI: 10.1016/j.visres.2020.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/08/2020] [Accepted: 01/13/2020] [Indexed: 12/16/2022]
Abstract
Mutations in photoreceptor cilium genes CEP290 and NPHP5 cause a form of Leber congenital amaurosis (LCA) which typically lacks rods but retains central cones. The current study evaluated the transient pupillary light reflex (TPLR) as an objective outcome measure to assess efficacy of ongoing and future therapies. Eleven eyes of six patients selected for retained cone function were tested with TPLR using full-field stimuli in the dark-adapted state. Stimuli were red or blue with 1 s duration and spanned a 6-log unit dynamic range. TPLR response amplitude was quantified at fixed times of 0.9 and 2 s after stimulus onset and TPLR latency was defined as the time to reach 0.3 mm constriction. Full-field stimulus testing (FST) and static perimetry were used to correlate subjective perception with objective TPLR parameters. TPLR and FST thresholds with both red and blue stimuli were abnormally elevated in patients to near -1.25 log phot-cd·m-2 consistent with the lack of rods. TPLR latencies were delayed on average but showed some differences among patients. Remnant extrafoveal vision was correlated with faster TPLR latencies. Our results support the use of a short TPLR protocol with full-field red stimuli of 0.7 log phot-cd·m-2 or brighter as an objective and convenient outcome measure of cone function in CEP290- and NPHP5-LCA. The latency parameter of the TPLR would be expected to show a detectable change when an intervention modifies cone sensitivity in the extrafoveal region.
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Affiliation(s)
- Arun K Krishnan
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Samuel G Jacobson
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Alejandro J Roman
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Bhavya S Iyer
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Alexandra V Garafalo
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Elise Héon
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
| | - Artur V Cideciyan
- Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
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31
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Wheway G, Lord J, Baralle D. Splicing in the pathogenesis, diagnosis and treatment of ciliopathies. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194433. [PMID: 31698098 DOI: 10.1016/j.bbagrm.2019.194433] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/12/2019] [Accepted: 09/17/2019] [Indexed: 12/12/2022]
Abstract
Primary cilia are essential signalling organelles found on the apical surface of epithelial cells, where they coordinate chemosensation, mechanosensation and light sensation. Motile cilia play a central role in establishing fluid flow in the respiratory tract, reproductive tract, brain ventricles and ear. Genetic defects affecting the structure or function of cilia can lead to a broad range of developmental and degenerative diseases known as ciliopathies. Splicing contributes to the pathogenesis, diagnosis and treatment of ciliopathies. Tissue-specific alternative splicing contributes to the tissue-specific manifestation of ciliopathy phenotypes, for example the retinal-specific effects of some genetic defects, due to specific transcript expression in the highly specialised ciliated cells of the retina, the photoreceptor cells. Ciliopathies can arise both as a result of genetic variants in spliceosomal proteins, or as a result of variants affecting splicing of specific cilia genes. Here we discuss the opportunities and challenges in diagnosing ciliopathies using RNA sequence analysis and the potential for treating ciliopathies in a relatively mutation-neutral way by targeting splicing. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Gabrielle Wheway
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland
| | - Jenny Lord
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland
| | - Diana Baralle
- Faculty of Medicine, University of Southampton, Human Development and Health, United Kingdom of Great Britain and Northern Ireland; University Hospital Southampton NHS Foundation Trust, United Kingdom of Great Britain and Northern Ireland.
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32
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Mice deficient in the lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1) display a complex retinal phenotype. Sci Rep 2019; 9:14185. [PMID: 31578378 PMCID: PMC6775149 DOI: 10.1038/s41598-019-50726-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/13/2019] [Indexed: 01/09/2023] Open
Abstract
Neuronal ceroid lipofuscinosis (NCL) type 1 (CLN1) is a neurodegenerative storage disorder caused by mutations in the gene encoding the lysosomal enzyme palmitoyl-protein thioesterase 1 (PPT1). CLN1 patients suffer from brain atrophy, mental and motor retardation, seizures, and retinal degeneration ultimately resulting in blindness. Here, we performed an in-depth analysis of the retinal phenotype of a PPT1-deficient mouse, an animal model of this condition. Reactive astrogliosis and microgliosis were evident in mutant retinas prior to the onset of retinal cell loss. Progressive accumulation of storage material, a pronounced dysregulation of various lysosomal proteins, and accumulation of sequestosome/p62-positive aggregates in the inner nuclear layer also preceded retinal degeneration. At advanced stages of the disease, the mutant retina was characterized by a significant loss of ganglion cells, rod and cone photoreceptor cells, and rod and cone bipolar cells. Results demonstrate that PPT1 dysfunction results in early-onset pathological alterations in the mutant retina, followed by a progressive degeneration of various retinal cell types at relatively late stages of the disease. Data will serve as a reference for future work aimed at developing therapeutic strategies for the treatment of retinal degeneration in CLN1 disease.
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Kim YJ, Kim J. Therapeutic perspectives for structural and functional abnormalities of cilia. Cell Mol Life Sci 2019; 76:3695-3709. [PMID: 31147753 PMCID: PMC11105626 DOI: 10.1007/s00018-019-03158-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/17/2019] [Accepted: 05/22/2019] [Indexed: 12/15/2022]
Abstract
Ciliopathies are a group of hereditary disorders that result from structural or functional abnormalities of cilia. Recent intense research efforts have uncovered the genetic bases of ciliopathies, and our understanding of the assembly and functions of cilia has been improved significantly. Although mechanism-specific therapies for ciliopathies have not yet received regulatory approval, the use of innovative therapeutic modalities such as oligonucleotide therapy, gene replacement therapy, and gene editing in addition to symptomatic treatments are expected to provide valid treatment options in the near future. Moreover, candidate chemical compounds for developing small molecule drugs to treat ciliopathies have been identified. This review introduces the key features of cilia and ciliopathies, and summarizes the advances as well as the challenges that remain with the development of therapies for treating ciliopathies.
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Affiliation(s)
- Yong Joon Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Republic of Korea
| | - Joon Kim
- Graduate School of Medical Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon, 34141, Republic of Korea.
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34
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Brun A, Yu X, Obringer C, Ajoy D, Haser E, Stoetzel C, Roux MJ, Messaddeq N, Dollfus H, Marion V. In vivo phenotypic and molecular characterization of retinal degeneration in mouse models of three ciliopathies. Exp Eye Res 2019; 186:107721. [DOI: 10.1016/j.exer.2019.107721] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 05/29/2019] [Accepted: 07/08/2019] [Indexed: 12/17/2022]
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Kretschmer V, Patnaik SR, Kretschmer F, Chawda MM, Hernandez-Hernandez V, May-Simera HL. Progressive Characterization of Visual Phenotype in Bardet-Biedl Syndrome Mutant Mice. Invest Ophthalmol Vis Sci 2019; 60:1132-1143. [PMID: 30901771 DOI: 10.1167/iovs.18-25210] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Bardet-Biedl syndrome (BBS) is an archetypical ciliopathy caused by defective ciliary trafficking and consequent function. Insights gained from BBS mouse models are applicable to other syndromic and nonsyndromic retinal diseases. This progressive characterization of the visual phenotype in three BBS mouse models sets a baseline for testing therapeutic interventions. Methods Longitudinal acquisition of electroretinograms, optical coherence tomography scans, and visual acuity using the optomotor reflex in Bbs6/Mkks, Bbs8/Ttc8, and Bbs5 knockout mice. Gene and protein expression analysis in vivo and in vitro. Results Complete loss of BBS5, BBS6, or BBS8 leads to different rates of retinal degeneration and visual function over time. BBS8-deficient mice showed the fastest rate of degeneration, and BBS8 seems to be required for cone photoreceptors to reach functional maturity. In contrast, the loss of BBS5 (a further BBSome component) showed very little degeneration. Loss of BBS8 versus BBS5 resulted in different physiologic responses both in vivo and in vitro. BBS6-deficient mice show a slower rate of degeneration with both rod and cone function reducing at a similar rate. Conclusions The mouse models analyzed show distinct and diverging courses of degeneration upon loss of BBS5, BBS6, or BBS8, which can be used as a benchmark to test therapeutic interventions. Close consideration of the different phenotypes reveal subtle but important differences relating to their function. Because we also see differences in terms of phenotype depending on the type of visual assessment used, our data highlight the importance of using a combinatorial approach for assessment of visual function.
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Affiliation(s)
- Viola Kretschmer
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
| | - Sarita Rani Patnaik
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
| | - Friedrich Kretschmer
- Scientific Computing Facility, Max Planck Institute for Brain Research, Frankfurt, Germany
| | - Mira Manilal Chawda
- Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Victor Hernandez-Hernandez
- Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom.,Department of Life Sciences, College of Health and Life Sciences, Brunel University London, London, United Kingdom
| | - Helen Louise May-Simera
- Cilia Cell Biology, Institute of Molecular Physiology, Johannes Gutenberg University, Mainz, Germany
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36
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Huang XF, Xiang L, Fang XL, Liu WQ, Zhuang YY, Chen ZJ, Shen RJ, Cheng W, Han RY, Zheng SS, Chen XJ, Liu X, Jin ZB. Functional characterization of CEP250 variant identified in nonsyndromic retinitis pigmentosa. Hum Mutat 2019; 40:1039-1045. [PMID: 30998843 DOI: 10.1002/humu.23759] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 03/16/2019] [Accepted: 04/02/2019] [Indexed: 12/29/2022]
Abstract
Retinitis pigmentosa (RP) is the most common manifestation of inherited retinal diseases with high degree of genetic, allelic, and phenotypic heterogeneity. CEP250 encodes the C-Nap1 protein and has been associated with various retinal phenotypes. Here, we report the identification of a mutation (c.562C>T, p.R188*) in the CEP250 in a consanguineous family with nonsyndromic RP. To gain insights into the molecular pathomechanism underlying CEP250 defects and the functional relevance of CEP250 variants in humans, we conducted a functional characterization of CEP250 variant using a novel Cep250 knockin mouse line. Remarkably, the disruption of Cep250 resulted in severe impairment of retinal function and significant retinal morphological alterations. The homozygous knockin mice showed significantly reduced retinal thickness and ERG responses. This study not only broadens the spectrum of phenotypes associated with CEP250 mutations, but also, for the first time, elucidates the function of CEP250 in photoreceptors using a newly established animal model.
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Affiliation(s)
- Xiu-Feng Huang
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Lue Xiang
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Xiao-Long Fang
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Wei-Qin Liu
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - You-Yuan Zhuang
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Zhen-Ji Chen
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Ren-Juan Shen
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Wan Cheng
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Ru-Yi Han
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Si-Si Zheng
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Xue-Jiao Chen
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
| | - Xiaoling Liu
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
- Department of Medical Retina, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Zi-Bing Jin
- Division of Ophthalmic Genetics, The Eye Hospital, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, National International Joint Research Center for Regenerative Medicine and Neurogenetics, Wenzhou Medical University, Wenzhou, China
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37
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Takahashi VKL, Xu CL, Takiuti JT, Apatoff MBL, Duong JK, Mahajan VB, Tsang SH. Comparison of structural progression between ciliopathy and non-ciliopathy associated with autosomal recessive retinitis pigmentosa. Orphanet J Rare Dis 2019; 14:187. [PMID: 31370859 PMCID: PMC6676605 DOI: 10.1186/s13023-019-1163-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 07/22/2019] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND To evaluate and compare the progression of ciliopathy and non-ciliopathy autosomal recessive Retinitis Pigmentosa patients (arRP) by measuring the constriction of hyperautofluorescent rings in fundus autofluorescence (FAF) images and the progressive shortening of the ellipsoid zone line width obtained by spectral-domain optical coherence tomography (SD-OCT). RESULTS For the ciliopathy group, the estimated mean shortening of the ellipsoid zone line was 259 μm per year and the ring area decreased at a rate of 2.46 mm2 per year. For the non-ciliopathy group, the estimated mean shortening of the ellipsoid zone line was 84 μm per year and the ring area decreased at a rate of 0.7 mm2 per year. CONCLUSIONS Our study was able to quantify and compare the loss of EZ line width and short-wavelength autofluorescence (SW-AF) ring constriction progression over time for ciliopathy and non-ciliopathy arRP genes. These results may serve as a basis for modeling RP disease progression, and furthermore, they could potentially be used as endpoints in clinical trials seeking to promote cone and rod survival in RP patients.
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Affiliation(s)
- Vitor K L Takahashi
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Jonas Children's Vision Care, and the Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, Institute of Human Nutrition, Columbia University, New York, NY, USA.,Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | - Christine L Xu
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Jonas Children's Vision Care, and the Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Júlia T Takiuti
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Jonas Children's Vision Care, and the Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, Institute of Human Nutrition, Columbia University, New York, NY, USA.,Division of Ophthalmology, University of São Paulo Medical School, São Paulo, Brazil
| | - Mary Ben L Apatoff
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Jonas Children's Vision Care, and the Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, Institute of Human Nutrition, Columbia University, New York, NY, USA
| | - Jimmy K Duong
- Department of Biostatistics, Columbia University, New York, NY, USA
| | - Vinit B Mahajan
- Byers Eye Institute, Omics Laboratory, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA.,Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, NY, USA. .,Jonas Children's Vision Care, and the Bernard & Shirlee Brown Glaucoma Laboratory, Departments of Ophthalmology, Pathology & Cell Biology, Columbia Stem Cell Initiative, Institute of Human Nutrition, Columbia University, New York, NY, USA. .,Department of Pathology & Cell Biology, Stem Cell Initiative (CSCI), Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY, USA. .,Harkness Eye Institute, Columbia University Medical Center, 635 West 165th Street, Box 212, New York, NY, 10032, USA.
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Chen HY, Welby E, Li T, Swaroop A. Retinal disease in ciliopathies: Recent advances with a focus on stem cell-based therapies. ACTA ACUST UNITED AC 2019; 4:97-115. [PMID: 31763178 PMCID: PMC6839492 DOI: 10.3233/trd-190038] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ciliopathies display extensive genetic and clinical heterogeneity, varying in severity, age of onset, disease progression and organ systems affected. Retinal involvement, as demonstrated by photoreceptor dysfunction or death, is a highly penetrant phenotype among a vast majority of ciliopathies. Photoreceptor cells possess a specialized and modified sensory cilium with membrane discs where efficient photon capture and ensuing signaling cascade initiate the visual process. Disruptions of cilia biogenesis and protein transport lead to impairment of photoreceptor function and eventually degeneration. Despite advances in elucidation of ciliogenesis and photoreceptor cilia defects, we have limited understanding of pathogenic mechanisms underlying retinal phenotype(s) observed in human ciliopathies. Patient-derived induced pluripotent stem cell (iPSC)-based approaches offer a unique opportunity to complement studies with model organisms and examine cilia disease relevant to humans. Three-dimensional retinal organoids from iPSC lines feature laminated cytoarchitecture, apical-basal polarity and emergence of a ciliary structure, thereby permitting pathogenic modeling of human photoreceptors in vitro. Here, we review the biology of photoreceptor cilia and associated defects and discuss recent progress in evolving treatment modalities, especially using patient-derived iPSCs, for retinal ciliopathies.
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Affiliation(s)
- Holly Yu Chen
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Emily Welby
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tiansen Li
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
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Khanna H. More Than Meets the Eye: Current Understanding of RPGR Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1074:521-538. [PMID: 29721984 DOI: 10.1007/978-3-319-75402-4_64] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
This article summarizes the recent advances in our understanding of a major retinal disease gene RPGR (retinitis pigmentosa GTPase regulator), mutations in which are associated with majority of X-linked forms of retinal degenerations. A great deal of work has been done to uncover the ciliary localization of RPGR and its interacting proteins in the retina. However, the molecular mechanisms of action of RPGR in the photoreceptors are still unclear. Recent studies have begun to shed light on the intracellular pathways in which RPGR is likely involved. The deregulation of such pathways may underlie the pathogenesis of severe retinal degeneration associated with RPGR. With the recent advances in the gene augmentation therapy for RPGR-associated disease, there is a lot of excitement in the field. Patients with RPGR mutations, however, present with clinically heterogeneous manifestations. It is therefore imperative to examine the function of RPGR in detail, so that we can design patient-oriented therapeutic strategies for this disease.
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Affiliation(s)
- Hemant Khanna
- Department of Ophthalmology and Neurobiology, UMASS Medical School, Worcester, MA, USA.
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40
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Cideciyan AV, Jacobson SG. Leber Congenital Amaurosis (LCA): Potential for Improvement of Vision. Invest Ophthalmol Vis Sci 2019; 60:1680-1695. [PMID: 31009524 PMCID: PMC6892385 DOI: 10.1167/iovs.19-26672] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Artur V. Cideciyan
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Samuel G. Jacobson
- Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
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41
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Wheway G, Mitchison HM. Opportunities and Challenges for Molecular Understanding of Ciliopathies-The 100,000 Genomes Project. Front Genet 2019; 10:127. [PMID: 30915099 PMCID: PMC6421331 DOI: 10.3389/fgene.2019.00127] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/05/2019] [Indexed: 01/11/2023] Open
Abstract
Cilia are highly specialized cellular organelles that serve multiple functions in human development and health. Their central importance in the body is demonstrated by the occurrence of a diverse range of developmental disorders that arise from defects of cilia structure and function, caused by a range of different inherited mutations found in more than 150 different genes. Genetic analysis has rapidly advanced our understanding of the cell biological basis of ciliopathies over the past two decades, with more recent technological advances in genomics rapidly accelerating this progress. The 100,000 Genomes Project was launched in 2012 in the UK to improve diagnosis and future care for individuals affected by rare diseases like ciliopathies, through whole genome sequencing (WGS). In this review we discuss the potential promise and medical impact of WGS for ciliopathies and report on current progress of the 100,000 Genomes Project, reviewing the medical, technical and ethical challenges and opportunities that new, large scale initiatives such as this can offer.
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Affiliation(s)
- Gabrielle Wheway
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom
| | - Hannah M. Mitchison
- Genetics and Genomic Medicine, University College London, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
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Photoreceptor cell development requires prostaglandin signaling in the zebrafish retina. Biochem Biophys Res Commun 2019; 510:230-235. [DOI: 10.1016/j.bbrc.2019.01.073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Accepted: 01/16/2019] [Indexed: 01/02/2023]
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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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Abstract
Cilia are microtubule-based organelles extending from a basal body at the surface of eukaryotic cells. Cilia regulate cell and fluid motility, sensation and developmental signaling, and ciliary defects cause human diseases (ciliopathies) affecting the formation and function of many tissues and organs. Over the past decade, various Rab and Rab-like membrane trafficking proteins have been shown to regulate cilia-related processes such as basal body maturation, ciliary axoneme extension, intraflagellar transport and ciliary signaling. In this review, we provide a comprehensive overview of Rab protein ciliary associations, drawing on findings from multiple model systems, including mammalian cell culture, mice, zebrafish, C. elegans, trypanosomes, and green algae. We also discuss several emerging mechanistic themes related to ciliary Rab cascades and functional redundancy.
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Affiliation(s)
- Oliver E Blacque
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
| | - Noemie Scheidel
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
| | - Stefanie Kuhns
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
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Singh M, Tyagi SC. Genes and genetics in eye diseases: a genomic medicine approach for investigating hereditary and inflammatory ocular disorders. Int J Ophthalmol 2018; 11:117-134. [PMID: 29376001 DOI: 10.18240/ijo.2018.01.20] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 10/31/2017] [Indexed: 12/27/2022] Open
Abstract
Past 25y have witnessed an exponential increase in knowledge and understanding of ocular diseases and their respective genetic underpinnings. As a result, scientists have mapped many genes and their variants that can influence vision and health of our eyes. Based on these findings, it is becoming clear that an early diagnosis employing genetic testing can help evaluate patients' conditions for instituting treatment plan(s) and follow-up care to avoid vision complications later. For example, knowing family history becomes crucial for inherited eye diseases as it can benefit members in family who may have similar eye diseases or predispositions. Therefore, gathering information from an elaborate examination along with complete assessment of past medical illness by ophthalmologists followed by consultation with geneticists can help create a roadmap for making diagnosis and treatment precise and beneficial. In this review, we present an update on ocular genomic medicine that we believe has tremendous potential towards unraveling genetic implications in ocular diseases and patients' susceptibilities. We also discuss translational aspects of genetic ophthalmology and genome engineering that may help advance molecular diagnostics and therapeutics.
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Affiliation(s)
- Mahavir Singh
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Suresh C Tyagi
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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Thompson JA, De Roach JN, McLaren TL, Lamey TM. A Mini-Review: Leber Congenital Amaurosis: Identification of Disease-Causing Variants and Personalised Therapies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1074:265-271. [DOI: 10.1007/978-3-319-75402-4_32] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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47
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Forsythe E, Kenny J, Bacchelli C, Beales PL. Managing Bardet-Biedl Syndrome-Now and in the Future. Front Pediatr 2018; 6:23. [PMID: 29487844 PMCID: PMC5816783 DOI: 10.3389/fped.2018.00023] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 01/25/2018] [Indexed: 11/13/2022] Open
Abstract
Bardet-Biedl syndrome is a rare autosomal recessive multisystem disorder caused by defects in genes encoding for proteins that localize to the primary cilium/basal body complex. Twenty-one disease-causing genes have been identified to date. It is one of the most well-studied conditions in the family of diseases caused by defective cilia collectively known as ciliopathies. In this review, we provide an update on diagnostic developments, clinical features, and progress in the management of Bardet-Biedl syndrome. Advances in diagnostic technologies including exome and whole genome sequencing are expanding the spectrum of patients who are diagnosed with Bardet-Biedl syndrome and increasing the number of cases with diagnostic uncertainty. As a result of the diagnostic developments, a small number of patients with only one or two clinical features of Bardet-Biedl syndrome are being diagnosed. Our understanding of the syndrome-associated renal disease has evolved and is reviewed here. Novel interventions are developing at a rapid pace and are explored in this review including genetic therapeutics such as gene therapy, exon skipping therapy, nonsense suppression therapy, and gene editing. Other non-genetic therapies such as gene repurposing, targeted therapies, and non-pharmacological interventions are also discussed.
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Affiliation(s)
- Elizabeth Forsythe
- Genetics and Genomic Medicine Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Joanna Kenny
- Genetics and Genomic Medicine Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Chiara Bacchelli
- Genetics and Genomic Medicine Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Philip L Beales
- Genetics and Genomic Medicine Programme, UCL Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
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48
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Seo S, Datta P. Photoreceptor outer segment as a sink for membrane proteins: hypothesis and implications in retinal ciliopathies. Hum Mol Genet 2017; 26:R75-R82. [PMID: 28453661 DOI: 10.1093/hmg/ddx163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
The photoreceptor outer segment (OS) is a unique modification of the primary cilium, specialized for light perception. Being homologous organelles, the primary cilium and the OS share common building blocks and molecular machinery to construct and maintain them. The OS, however, has several unique structural features that are not seen in primary cilia. Although these unique features of the OS have been well documented, their implications in protein localization have been under-appreciated. In this review, we compare the structural properties of the primary cilium and the OS, and propose a hypothesis that the OS can act as a sink for membrane proteins. We further discuss the implications of this hypothesis in polarized protein localization in photoreceptors and mechanisms of photoreceptor degeneration in retinal ciliopathies.
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Affiliation(s)
- Seongjin Seo
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Poppy Datta
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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49
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Abstract
Cilia are microtubule-based organelles extending from a basal body at the surface of eukaryotic cells. Cilia regulate cell and fluid motility, sensation and developmental signaling, and ciliary defects cause human diseases (ciliopathies) affecting the formation and function of many tissues and organs. Over the past decade, various Rab and Rab-like membrane trafficking proteins have been shown to regulate cilia-related processes such as basal body maturation, ciliary axoneme extension, intraflagellar transport and ciliary signaling. In this review, we provide a comprehensive overview of Rab protein ciliary associations, drawing on findings from multiple model systems, including mammalian cell culture, mice, zebrafish, C. elegans, trypanosomes, and green algae. We also discuss several emerging mechanistic themes related to ciliary Rab cascades and functional redundancy.
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Affiliation(s)
- Oliver E Blacque
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
| | - Noemie Scheidel
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
| | - Stefanie Kuhns
- a School of Biomolecular and Biomedical Science , University College Dublin , Belfield, Dublin , Ireland
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50
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El Shamieh S, Méjécase C, Bertelli M, Terray A, Michiels C, Condroyer C, Fouquet S, Sadoun M, Clérin E, Liu B, Léveillard T, Goureau O, Sahel JA, Audo I, Zeitz C. Further Insights into the Ciliary Gene and Protein KIZ and Its Murine Ortholog PLK1S1 Mutated in Rod-Cone Dystrophy. Genes (Basel) 2017; 8:genes8100277. [PMID: 29057815 PMCID: PMC5664127 DOI: 10.3390/genes8100277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/04/2017] [Accepted: 10/06/2017] [Indexed: 11/16/2022] Open
Abstract
We identified herein additional patients with rod-cone dystrophy (RCD) displaying mutations in KIZ, encoding the ciliary centrosomal protein kizuna and performed functional characterization of the respective protein in human fibroblasts and of its mouse ortholog PLK1S1 in the retina. Mutation screening was done by targeted next generation sequencing and subsequent Sanger sequencing validation. KIZ mRNA levels were assessed on blood and serum-deprived human fibroblasts from a control individual and a patient, compound heterozygous for the c.52G>T (p.Glu18*) and c.119_122del (p.Lys40Ilefs*14) mutations in KIZ. KIZ localization, documentation of cilium length and immunoblotting were performed in these two fibroblast cell lines. In addition, PLK1S1 immunolocalization was conducted in mouse retinal cryosections and isolated rod photoreceptors. Analyses of additional RCD patients enabled the identification of two homozygous mutations in KIZ, the known c.226C>T (p.Arg76*) mutation and a novel variant, the c.3G>A (p.Met1?) mutation. Albeit the expression levels of KIZ were three-times lower in the patient than controls in whole blood cells, further analyses in control- and mutant KIZ patient-derived fibroblasts unexpectedly revealed no significant difference between the two genotypes. Furthermore, the averaged monocilia length in the two fibroblast cell lines was similar, consistent with the preserved immunolocalization of KIZ at the basal body of the primary cilia. Analyses in mouse retina and isolated rod photoreceptors showed PLK1S1 localization at the base of the photoreceptor connecting cilium. In conclusion, two additional patients with mutations in KIZ were identified, further supporting that defects in KIZ/PLK1S1, detected at the basal body of the primary cilia in fibroblasts, and the photoreceptor connecting cilium in mouse, respectively, are involved in RCD. However, albeit the mutations were predicted to lead to nonsense mediated mRNA decay, we could not detect changes upon expression levels, protein localization or cilia length in KIZ-mutated fibroblast cells. Together, our findings unveil the limitations of fibroblasts as a cellular model for RCD and call for other models such as induced pluripotent stem cells to shed light on retinal pathogenic mechanisms of KIZ mutations.
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Affiliation(s)
- Said El Shamieh
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, 115020 Beirut, Lebanon.
| | - Cécile Méjécase
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | | | - Angélique Terray
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Christelle Michiels
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Christel Condroyer
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Stéphane Fouquet
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Maxime Sadoun
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Emmanuelle Clérin
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Binqian Liu
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Thierry Léveillard
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Olivier Goureau
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - José-Alain Sahel
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, 75012 Paris, France.
- Fondation Ophtalmologique Adolphe de Rothschild, 75019 Paris, France.
- Académie des Sciences-Institut de France, 75006 Paris, France.
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburg, PA 15213, USA.
- Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.
| | - Isabelle Audo
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, 75012 Paris, France.
- Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.
| | - Christina Zeitz
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
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