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Ying R, Li C, Li H, Zou J, Hu M, Hong Q, Shen Y, Hou L, Cheng H, Zhou R. RPGR is a guanine nucleotide exchange factor for the small GTPase RAB37 required for retinal function via autophagy regulation. Cell Rep 2024; 43:114010. [PMID: 38536817 DOI: 10.1016/j.celrep.2024.114010] [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: 07/26/2023] [Revised: 01/28/2024] [Accepted: 03/13/2024] [Indexed: 04/28/2024] Open
Abstract
Although the small GTPase RAB37 acts as an organizer of autophagosome biogenesis, the upstream regulatory mechanism of autophagy via guanosine diphosphate (GDP)-guanosine triphosphate (GTP) exchange in maintaining retinal function has not been determined. We found that retinitis pigmentosa GTPase regulator (RPGR) is a guanine nucleotide exchange factor that activates RAB37 by accelerating GDP-to-GTP exchange. RPGR directly interacts with RAB37 via the RPGR-RCC1-like domain to promote autophagy through stimulating exchange. Rpgr knockout (KO) in mice leads to photoreceptor degeneration owing to autophagy impairment in the retina. Notably, the retinopathy phenotypes of Rpgr KO retinas are rescued by the adeno-associated virus-mediated transfer of pre-trans-splicing molecules, which produce normal Rpgr mRNAs via trans-splicing in the Rpgr KO retinas. This rescue upregulates autophagy through the re-expression of RPGR in KO retinas to accelerate GDP-to-GTP exchange; thus, retinal homeostasis reverts to normal. Taken together, these findings provide an important missing link for coordinating RAB37 GDP-GTP exchange via the RPGR and retinal homeostasis by autophagy regulation.
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Affiliation(s)
- Ruhong Ying
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Cong Li
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Huirong Li
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou 325003, China
| | - Juan Zou
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Mengxin Hu
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Qiang Hong
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Yin Shen
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Ling Hou
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou 325003, China.
| | - Hanhua Cheng
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China.
| | - Rongjia Zhou
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China.
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Baz-Redón N, Sánchez-Bellver L, Fernández-Cancio M, Rovira-Amigo S, Burgoyne T, Ranjit R, Aquino V, Toro-Barrios N, Carmona R, Polverino E, Cols M, Moreno-Galdó A, Camats-Tarruella N, Marfany G. Primary Ciliary Dyskinesia and Retinitis Pigmentosa: Novel RPGR Variant and Possible Modifier Gene. Cells 2024; 13:524. [PMID: 38534367 DOI: 10.3390/cells13060524] [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: 02/02/2024] [Revised: 03/09/2024] [Accepted: 03/13/2024] [Indexed: 03/28/2024] Open
Abstract
We report a novel RPGR missense variant co-segregated with a familial X-linked retinitis pigmentosa (XLRP) case. The brothers were hemizygous for this variant, but only the proband presented with primary ciliary dyskinesia (PCD). Thus, we aimed to elucidate the role of the RPGR variant and other modifier genes in the phenotypic variability observed in the family and its impact on motile cilia. The pathogenicity of the variant on the RPGR protein was evaluated by in vitro studies transiently transfecting the mutated RPGR gene, and immunofluorescence analysis on nasal brushing samples. Whole-exome sequencing was conducted to identify potential modifier variants. In vitro studies showed that the mutated RPGR protein could not localise to the cilium and impaired cilium formation. Accordingly, RPGR was abnormally distributed in the siblings' nasal brushing samples. In addition, a missense variant in CEP290 was identified. The concurrent RPGR variant influenced ciliary mislocalisation of the protein. We provide a comprehensive characterisation of motile cilia in this XLRP family, with only the proband presenting PCD symptoms. The variant's pathogenicity was confirmed, although it alone does not explain the respiratory symptoms. Finally, the CEP290 gene may be a potential modifier for respiratory symptoms in patients with RPGR mutations.
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Affiliation(s)
- Noelia Baz-Redón
- Growth and Development Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Laura Sánchez-Bellver
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Mónica Fernández-Cancio
- Growth and Development Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Sandra Rovira-Amigo
- Growth and Development Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Department of Paediatrics, Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus, 08035 Barcelona, Spain
| | - Thomas Burgoyne
- Royal Brompton Hospital, Guy's and St Thomas' NHS Foundation Trust, London SW3 6NP, UK
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Rai Ranjit
- Royal Brompton Hospital, Guy's and St Thomas' NHS Foundation Trust, London SW3 6NP, UK
| | - Virginia Aquino
- Plataforma Andaluza de Medicina Computacional, Fundación Pública Andaluza Progreso y Salud, 41092 Sevilla, Spain
| | - Noemí Toro-Barrios
- Plataforma Andaluza de Medicina Computacional, Fundación Pública Andaluza Progreso y Salud, 41092 Sevilla, Spain
| | - Rosario Carmona
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Plataforma Andaluza de Medicina Computacional, Fundación Pública Andaluza Progreso y Salud, 41092 Sevilla, Spain
| | - Eva Polverino
- Pneumology Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Pneumology Department, Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Maria Cols
- Paediatric Pulmonology Department and Cystic Fibrosis Unit, Hospital Sant Joan de Déu, 08950 Esplugues de Llobregat, Spain
| | - Antonio Moreno-Galdó
- Growth and Development Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Department of Paediatrics, Vall d'Hebron Hospital Universitari, Vall d'Hebron Barcelona Hospital Campus, 08035 Barcelona, Spain
- Department of Paediatrics, Obstetrics, Gynecology, Preventive Medicine and Public Health, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Núria Camats-Tarruella
- Growth and Development Research Group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Gemma Marfany
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, 08028 Barcelona, Spain
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Jiménez-Berríos GA, Vázquez-Folch SJ, Izquierdo N. Open-Angle and Steroid-Induced Glaucoma in Patients With Retinitis Pigmentosa: A Dangerous Liaison. Cureus 2024; 16:e55632. [PMID: 38586746 PMCID: PMC10996434 DOI: 10.7759/cureus.55632] [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] [Accepted: 03/06/2024] [Indexed: 04/09/2024] Open
Abstract
Previous studies have reported that patients with retinitis pigmentosa (RP) may develop open-angle and angle-closure glaucoma. We conducted a chart review of patients with RP. Two siblings with RP associated with a mutation in the PDE6B gene (c. 1540del, p.Leu514Trpfs*61) developed cystoid macular edema (CME) as part of the disease. For this reason, they both underwent intravitreal steroid injections. Both brothers developed steroid-induced glaucoma (SIG). Despite undergoing maximal medical therapy, they underwent seton implants to control their intraocular pressure. A third female patient with RP due to a mutation in the RPGR gene underwent cataract surgery. Topical steroids were prescribed and developed SIG. Increased intraocular pressure remains a complication of topical, injected, and systemic steroids. However, steroids may be needed to treat post-operatively and patients with CME. This case series unveils a complex association between RP and key comorbidities in these patients, with a focus on cataracts, glaucoma, and macular edema. Cataract surgery in patients with RP shows a link to the emergence of glaucoma, particularly in those with RPGR and PDE6B gene mutations, revealing a novel association with PDE6B mutations not previously documented. Furthermore, the paper explores a unique parallel with Schwartz-Matsuo syndrome, suggesting that patients with RP undergoing cataract surgery may develop increased intraocular pressure due to an outflow disturbance akin to Schwartz syndrome. This novel perspective deepens our understanding of the pathophysiological mechanisms governing intraocular pressure dynamics in patients with RP. To our knowledge, this is the first report of steroid-induced glaucoma in patients with RP due to mutations in the PDE6B gene. Intraocular pressure evaluation remains of utmost importance in the follow-up of patients with the disease.
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Affiliation(s)
| | | | - Natalio Izquierdo
- Department of Surgery, School of Medicine, Medical Sciences Campus, University of Puerto Rico, San Juan, PRI
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Pantrangi M, Rath J, Kaetterhenry N, Branham K, Talsness D, Weber JL. Clinical sequencing of the retinitis pigmentosa gene RPGR in over 1,000 cases of vision loss. Mol Vis 2024; 30:49-57. [PMID: 38586605 PMCID: PMC10994678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 02/17/2024] [Indexed: 04/09/2024] Open
Abstract
RPGR pathogenic variants are the major cause of X-linked retinitis pigmentosa. Here, we report the results from 1,033 clinical DNA tests that included sequencing of RPGR. A total of 184 RPGR variants were identified: 78 pathogenic or likely pathogenic, 14 uncertain, and 92 likely benign or benign. Among the pathogenic and likely pathogenic variants, 23 were novel, and most were frameshift or nonsense mutations (87%) and enriched (67%) in RPGR exon 15 (ORF15). Identical pathogenic variants found in different families were largely on different haplotype backgrounds, indicating relatively frequent, recurrent RPGR mutations. None of the 16 mother/affected son pairs showed de novo mutations; all 16 mothers were heterozygous for the pathogenic variant. These last two observations support the occurrence of most RPGR mutations in the male germline.
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Affiliation(s)
- Madhulatha Pantrangi
- PreventionGenetics, part of Exact Sciences, Marshfield, WI
- Weill Cornell Medicine, Department of Pathology and Laboratory Medicine, New York, NY
| | - Julie Rath
- PreventionGenetics, part of Exact Sciences, Marshfield, WI
| | | | - Kari Branham
- University of Michigan, Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, Ann Arbor, MI
| | - Dana Talsness
- PreventionGenetics, part of Exact Sciences, Marshfield, WI
| | - James L Weber
- PreventionGenetics, part of Exact Sciences, Marshfield, WI
- University of Wisconsin, School of Medicine and Public Health, Department of Pediatrics, Madison, WI
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Kolkova Z, Durdik P, Holubekova V, Durdikova A, Jesenak M, Banovcin P. Identification of a novel RPGR mutation associated with retinitis pigmentosa and primary ciliary dyskinesia in a Slovak family: a case report. Front Pediatr 2024; 12:1339664. [PMID: 38333087 PMCID: PMC10850321 DOI: 10.3389/fped.2024.1339664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/10/2024] [Indexed: 02/10/2024] Open
Abstract
Background The mutations in the RPGR (retinitis pigmentosa GTPase regulator) gene are the most common cause of X-linked retinitis pigmentosa (XLRP), a rare genetic disorder affecting the photoreceptor cells in the retina. Several reported cases identified this gene as a genetic link between retinitis pigmentosa (RP) and primary ciliary dyskinesia (PCD), characterised by impaired ciliary function predominantly in the respiratory tract. Since different mutations in the same gene can result in various clinical manifestations, it is important to describe a correlation between the gene variant and the observed phenotype. Methods Two young brothers from a non-consanguineous Slovak family with diagnosed retinal dystrophy and recurrent respiratory infections were examined. Suspected PCD was diagnosed based on a PICADAR questionnaire, nasal nitric oxide analysis, transmission electron microscopy, high-speed video microscopy analysis, and genetic testing. Results We identified a novel frameshift RPGR mutation NM_001034853: c.309_310insA, p.Glu104Argfs*12, resulting in a complex X-linked phenotype combining PCD and RP. In our patients, this mutation was associated with normal ultrastructure of respiratory cilia, reduced ciliary epithelium, more aciliary respiratory epithelium, shorter cilia, and uncoordinated beating with a frequency at a lower limit of normal beating, explaining the clinical manifestation of PCD in our patients. Conclusion The identified novel pathogenic mutation in the RPGR gene expands the spectrum of genetic variants associated with the X-linked PCD phenotype overlapping with RP, highlighting the diversity of mutations contributing to the disorder. The described genotype-phenotype correlation can be useful in clinical practice to recognise a broader spectrum of PCD phenotypes as well as for future research focused on the genetic basis of PCD, gene interactions, the pathways implicated in PCD pathogenesis, and the role of RPGR protein for the proper functioning of cilia in various tissues throughout the body.
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Affiliation(s)
- Zuzana Kolkova
- Biomedical Center Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Peter Durdik
- Department of Pediatrics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
- Department of Pediatrics, University Hospital Martin, Martin, Slovakia
| | - Veronika Holubekova
- Biomedical Center Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
| | - Anna Durdikova
- Department of Pediatrics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
- Department of Pediatrics, University Hospital Martin, Martin, Slovakia
| | - Milos Jesenak
- Department of Pediatrics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
- Department of Pediatrics, University Hospital Martin, Martin, Slovakia
- Department of Pulmonology and Phthisiology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, University Hospital in Martin, Martin, Slovakia
- Department of Clinical Immunology and Allergology, University Hospital in Martin, Martin, Slovakia
| | - Peter Banovcin
- Department of Pediatrics, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia
- Department of Pediatrics, University Hospital Martin, Martin, Slovakia
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Han RC, Taylor LJ, Martinez-Fernandez de la Camara C, Henderson RH, Thompson DA, Cehajic-Kapetanovic J, MacLaren RE. Is RPGR-related retinal dystrophy associated with systemic disease? A case series. Ophthalmic Genet 2023; 44:577-584. [PMID: 36602268 DOI: 10.1080/13816810.2022.2163405] [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: 09/09/2022] [Revised: 11/30/2022] [Accepted: 12/23/2022] [Indexed: 01/06/2023]
Abstract
BACKGROUND Ciliopathies responsible for retinitis pigmentosa can also cause systemic manifestations. RPGR is a ciliary gene and pathogenic variants in RPGR cause a retinal ciliopathy, the commonest cause of X-linked recessive retinitis pigmentosa. The RPGR protein interacts with numerous other ciliary proteins present in the transition zone of both motile and sensory cilia, and may play an important role in regulating ciliary protein transport. There has been a growing, putative association of RPGR variants with systemic ciliopathies: mainly sino-respiratory infections and primary ciliary dyskinesia. MATERIALS AND METHODS Retrospective case series of patients with RPGR-RP presenting to Oxford Eye Hospital with systemic disease. RESULTS We report three children with RPGR-related rod-cone dystrophy, all of whom have mutations in the N-terminus of RPGR. Two cases co-presented with confirmed diagnoses of primary ciliary dyskinesia and one case with multiple sino-respiratory symptoms strongly suggestive of primary ciliary dyskinesia. These and all previously reported RPGR co-pathologies relate to ciliopathies and have no other systemic associations. CONCLUSIONS The link between RPGR variants and a systemic ciliopathy remains plausible, but currently unproven.
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Affiliation(s)
- Ruofan Connie Han
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Laura J Taylor
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | | | - Robert H Henderson
- Department of Ophthalmology, Great Ormond Street Children's Hospital, London, UK
| | - Dorothy A Thompson
- Department of Ophthalmology, Great Ormond Street Children's Hospital, London, UK
- Clinical and Academic Department of Ophthalmology, Great Ormond Street Hospital for Children, London, UK
| | - Jasmina Cehajic-Kapetanovic
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Robert E MacLaren
- Oxford Eye Hospital, John Radcliffe Hospital, Oxford, UK
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Usman M, Jüschke C, Song F, Kastrati D, Owczarek-Lipska M, Eilers J, Pauleikhoff L, Lange C, Neidhardt J. Skewed X-inactivation is associated with retinal dystrophy in female carriers of RPGR mutations. Life Sci Alliance 2023; 6:e202201814. [PMID: 37541846 PMCID: PMC10403639 DOI: 10.26508/lsa.202201814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 07/18/2023] [Accepted: 07/24/2023] [Indexed: 08/06/2023] Open
Abstract
Progressive degeneration of rod and cone photoreceptors frequently is caused by mutations in the X-chromosomal gene Retinitis Pigmentosa GTPase Regulator (RPGR). Males hemizygous for a RPGR mutation often are affected by Retinitis Pigmentosa (RP), whereas female mutation carriers only occasionally present with severe RP phenotypes. The underlying pathomechanism leading to RP in female carriers is not well understood. Here, we analyzed a three-generation family in which two of three female carriers of a nonsense RPGR mutation presented with RP. Among two cell lines derived from the same female family members, differences were detected in RPGR transcript expression, in localization of RPGR along cilia, as well as in primary cilium length. Significantly, these differences correlated with alterations in X-chromosomal inactivation patterns found in the patient-derived cell lines from females. In summary, our data suggest that skewed X-chromosomal inactivation is an important factor that determines the disease manifestation of RP among female carriers of pathogenic sequence alterations in the RPGR gene.
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Affiliation(s)
- Muhammad Usman
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Christoph Jüschke
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Fei Song
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Dennis Kastrati
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Marta Owczarek-Lipska
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Junior Research Group, Genetics of Childhood Brain Malformations, School of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany
| | - Jannis Eilers
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Laurenz Pauleikhoff
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Clemens Lange
- Eye Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
- Ophtha-Lab, Department of Ophthalmology at St. Franziskus Hospital, Muenster, Germany
| | - John Neidhardt
- Human Genetics, Medical Faculty, School of Medicine and Health Sciences, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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Appelbaum T, Aguirre GD, Beltran WA. Identification of circular RNAs hosted by the RPGR ORF15 genomic locus. RNA Biol 2023; 20:31-47. [PMID: 36593651 PMCID: PMC9817113 DOI: 10.1080/15476286.2022.2159165] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/23/2022] [Accepted: 12/07/2022] [Indexed: 01/04/2023] Open
Abstract
Mutations in the retina-specific isoform of the gene encoding retinitis pigmentosa GTPase regulator (RPGRorf15) cause X-linked retinitis pigmentosa, a severe and early onset inherited retinal degeneration. The underlying pathogenic mechanisms and variability in disease severity remain to be fully elucidated. The present study examines structural features of the ORF15 exonic region to provide new insights into the disease pathogenesis. Using canine and human RNA samples, we identified several novel RPGR ORF15-like linear RNA transcripts containing cryptic introns (exitrons) within the annotated exon ORF15. Furthermore, using outward-facing primers designed inside exitrons in the ORF15 exonic region, we found many of previously unidentified circular RNAs (circRNAs) that formed via back fusion of linear parts of the RPGRorf15 pre-mRNAs. These circRNAs (resistant to RNAse R treatment) were found in all studied cells and tissues. Notably, some circRNAs were present in cytoplasmic and polysomal RNA fractions. Although certain RPGR circRNAs may be cell type specific, we found some of the same circRNAs expressed in different cell types, suggesting similarities in their biogenesis and functions. Sequence analysis of RPGR circRNAs revealed several remarkable features, including identification of N6-methyladenosine (m6A) consensus sequence motifs and high prevalence of predictive microRNA binding sites pointing to the functional roles of these circRNAs. Our findings also illustrate the presence of non-canonical RPGR circRNA biogenesis pathways independent of the known back splicing mechanism. The obtained data on novel RPGR circRNAs further underline structural complexity of the RPGR ORF15 region and provide a potential molecular basis for the disease phenotypic heterogeneity.
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Affiliation(s)
- Tatyana Appelbaum
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gustavo D. Aguirre
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William A. Beltran
- Division of Experimental Retinal Therapies, Department of Clinical Sciences & Advanced Medicine, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Martinez-Fernandez de la Camara C, Cehajic-Kapetanovic J, MacLaren RE. Emerging gene therapy products for RPGR-associated X-linked retinitis pigmentosa. Expert Opin Emerg Drugs 2022; 27:431-443. [PMID: 36562395 DOI: 10.1080/14728214.2022.2152003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 11/22/2022] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Mutations in the RPGR gene are responsible for one of the most prevalent and severe types of retinitis pigmentosa. Gene therapy has shown great promise to treat inherited retinal diseases, and currently, four RPGR gene therapy vectors are being evaluated in clinical trials. AREAS COVERED This manuscript reviews the gene therapy products that are in development for X-linked retinitis pigmentosa caused by mutations in RPGR, and the challenges that scientists and clinicians have faced. EXPERT OPINION The development of a gene therapy product for RPGR-associated retinal degeneration has been a great challenge due to the incomplete understanding of the underlying genetics and mechanism of action of RPGR, and on the other hand, due to the instability of the RPGR gene. Three of the four gene therapy vectors currently in clinical trials include a codon-optimized version of the human RPGR sequence, and the other vector contains a shortened version of the human RPGR. To date, the only Phase I/II results published in a peer-reviewed journal demonstrate a good safety profile and an improvement in the visual field using a codon optimized version of RPGRORF15.
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Affiliation(s)
- Cristina Martinez-Fernandez de la Camara
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West Wing, Headley Way, OX3 9DU, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, West Wing, Headley Way, OX3 9DU, Oxford, UK
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Cilleros-Rodriguez D, Martin-Morales R, Barbeito P, Deb Roy A, Loukil A, Sierra-Rodero B, Herranz G, Pampliega O, Redrejo-Rodriguez M, Goetz SC, Izquierdo M, Inoue T, Garcia-Gonzalo FR. Multiple ciliary localization signals control INPP5E ciliary targeting. eLife 2022; 11:78383. [PMID: 36063381 PMCID: PMC9444247 DOI: 10.7554/elife.78383] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/21/2022] [Indexed: 12/04/2022] Open
Abstract
Primary cilia are sensory membrane protrusions whose dysfunction causes ciliopathies. INPP5E is a ciliary phosphoinositide phosphatase mutated in ciliopathies like Joubert syndrome. INPP5E regulates numerous ciliary functions, but how it accumulates in cilia remains poorly understood. Herein, we show INPP5E ciliary targeting requires its folded catalytic domain and is controlled by four conserved ciliary localization signals (CLSs): LLxPIR motif (CLS1), W383 (CLS2), FDRxLYL motif (CLS3) and CaaX box (CLS4). We answer two long-standing questions in the field. First, partial CLS1-CLS4 redundancy explains why CLS4 is dispensable for ciliary targeting. Second, the essential need for CLS2 clarifies why CLS3-CLS4 are together insufficient for ciliary accumulation. Furthermore, we reveal that some Joubert syndrome mutations perturb INPP5E ciliary targeting, and clarify how each CLS works: (i) CLS4 recruits PDE6D, RPGR and ARL13B, (ii) CLS2-CLS3 regulate association to TULP3, ARL13B, and CEP164, and (iii) CLS1 and CLS4 cooperate in ATG16L1 binding. Altogether, we shed light on the mechanisms of INPP5E ciliary targeting, revealing a complexity without known parallels among ciliary cargoes.
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Affiliation(s)
- Dario Cilleros-Rodriguez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain.,Instituto de Investigación del Hospital Universitario de La Paz (IdiPAZ), Madrid, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Raquel Martin-Morales
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain.,Instituto de Investigación del Hospital Universitario de La Paz (IdiPAZ), Madrid, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Pablo Barbeito
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain.,Instituto de Investigación del Hospital Universitario de La Paz (IdiPAZ), Madrid, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Abhijit Deb Roy
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Abdelhalim Loukil
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, United States
| | - Belen Sierra-Rodero
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain.,Instituto de Investigación del Hospital Universitario de La Paz (IdiPAZ), Madrid, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Gonzalo Herranz
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain
| | - Olatz Pampliega
- Department of Neurosciences, University of the Basque Country, Achucarro Basque Center for Neuroscience-UPV/EHU, Leioa, Spain
| | - Modesto Redrejo-Rodriguez
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain
| | - Sarah C Goetz
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, United States
| | - Manuel Izquierdo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain
| | - Takanari Inoue
- Department of Cell Biology, Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Francesc R Garcia-Gonzalo
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid (UAM), Madrid, Spain.,Instituto de Investigaciones Biomédicas "Alberto Sols" (IIBM), Consejo Superior de Investigaciones Científicas (CSIC)-UAM, Madrid, Spain.,Instituto de Investigación del Hospital Universitario de La Paz (IdiPAZ), Madrid, Spain.,CIBER de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
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11
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Bhardwaj A, Yadav A, Yadav M, Tanwar M. Genetic dissection of non-syndromic retinitis pigmentosa. Indian J Ophthalmol 2022; 70:2355-2385. [PMID: 35791117 PMCID: PMC9426071 DOI: 10.4103/ijo.ijo_46_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Retinitis pigmentosa (RP) belongs to a group of pigmentary retinopathies. It is the most common form of inherited retinal dystrophy, characterized by progressive degradation of photoreceptors that leads to nyctalopia, and ultimately, complete vision loss. RP is distinguished by the continuous retinal degeneration that progresses from the mid-periphery to the central and peripheral retina. RP was first described and named by Franciscus Cornelius Donders in the year 1857. It is one of the leading causes of bilateral blindness in adults, with an incidence of 1 in 3000 people worldwide. In this review, we are going to focus on the genetic heterogeneity of this disease, which is provided by various inheritance patterns, numerosity of variations and inter-/intra-familial variations based upon penetrance and expressivity. Although over 90 genes have been identified in RP patients, the genetic cause of approximately 50% of RP cases remains unknown. Heterogeneity of RP makes it an extremely complicated ocular impairment. It is so complicated that it is known as “fever of unknown origin”. For prognosis and proper management of the disease, it is necessary to understand its genetic heterogeneity so that each phenotype related to the various genetic variations could be treated.
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Affiliation(s)
- Aarti Bhardwaj
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Anshu Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Manoj Yadav
- Department of Genetics, M. D. University, Rohtak, Haryana, India
| | - Mukesh Tanwar
- Department of Genetics, M. D. University, Rohtak, Haryana, India
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12
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Zhang R, Tang J, Li T, Zhou J, Pan W. INPP5E and Coordination of Signaling Networks in Cilia. Front Mol Biosci 2022; 9:885592. [PMID: 35463949 PMCID: PMC9019342 DOI: 10.3389/fmolb.2022.885592] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/22/2022] [Indexed: 11/13/2022] Open
Abstract
Primary cilia are ubiquitous mechanosensory organelles that specifically coordinate a series of cellular signal transduction pathways to control cellular physiological processes during development and in tissue homeostasis. Defects in the function or structure of primary cilia have been shown to be associated with a large range of diseases called ciliopathies. Inositol polyphosphate-5-phosphatase E (INPP5E) is an inositol polyphosphate 5-phosphatase that is localized on the ciliary membrane by anchorage via its C-terminal prenyl moiety and hydrolyzes both phosphatidylinositol-4, 5-bisphosphate (PtdIns(4,5)P2) and PtdIns(3,4,5)P3, leading to changes in the phosphoinositide metabolism, thereby resulting in a specific phosphoinositide distribution and ensuring proper localization and trafficking of proteins in primary cilia. In addition, INPP5E also works synergistically with cilia membrane-related proteins by playing key roles in the development and maintenance homeostasis of cilia. The mutation of INPP5E will cause deficiency of primary cilia signaling transduction, ciliary instability and ciliopathies. Here, we present an overview of the role of INPP5E and its coordination of signaling networks in primary cilia.
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Affiliation(s)
- Renshuai Zhang
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Institute of Biomedical Sciences, Shandong Normal University, Jinan, China
| | - Jianming Tang
- Zhenjiang Hospital of Traditional Chinese Medicine, Zhenjiang, China
| | - Tianliang Li
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Institute of Biomedical Sciences, Shandong Normal University, Jinan, China
| | - Jun Zhou
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Institute of Biomedical Sciences, Shandong Normal University, Jinan, China
| | - Wei Pan
- Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Institute of Biomedical Sciences, Shandong Normal University, Jinan, China
- *Correspondence: Wei Pan,
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13
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Covello G, Ibrahim GH, Bacchi N, Casarosa S, Denti MA. Exon Skipping Through Chimeric Antisense U1 snRNAs to Correct Retinitis Pigmentosa GTPase-Regulator ( RPGR) Splice Defect. Nucleic Acid Ther 2022; 32:333-349. [PMID: 35166581 PMCID: PMC9416563 DOI: 10.1089/nat.2021.0053] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Inherited retinal dystrophies are caused by mutations in more than 250 genes, each of them carrying several types of mutations that can lead to different clinical phenotypes. Mutations in Retinitis Pigmentosa GTPase-Regulator (RPGR) cause X-linked Retinitis pigmentosa (RP). A nucleotide substitution in intron 9 of RPGR causes the increase of an alternatively spliced isoform of the mature mRNA, bearing exon 9a (E9a). This introduces a stop codon, leading to truncation of the protein. Aiming at restoring impaired gene expression, we developed an antisense RNA-based therapeutic approach for the skipping of RPGR E9a. We designed a set of specific U1 antisense snRNAs (U1_asRNAs) and tested their efficacy in vitro, upon transient cotransfection with RPGR minigene reporter systems in HEK-293T, 661W, and PC-12 cell lines.
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Affiliation(s)
- Giuseppina Covello
- RNA Biology and Biotechnology Laboratory, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento, Italy
| | - Gehan H Ibrahim
- Department of Medical Biochemistry, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Niccolò Bacchi
- RNA Biology and Biotechnology Laboratory, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento, Italy
| | - Simona Casarosa
- Neural Development and Regeneration Laboratory, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento, Italy.,Centre for Medical Science - CIS Med, University of Trento, Trento, Italy.,CNR Neuroscience Institute, Pisa, Italy
| | - Michela Alessandra Denti
- RNA Biology and Biotechnology Laboratory, Department of Cellular, Computational and Integrative Biology - CIBIO, University of Trento, Trento, Italy.,CNR Neuroscience Institute, Pisa, Italy
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14
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Li Y, Hu L, Xu C. Kirsten rat sarcoma inhibitors in clinical development against nonsmall cell lung cancer. Curr Opin Oncol 2022; 34:66-76. [PMID: 34690284 DOI: 10.1097/cco.0000000000000808] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
PURPOSE OF REVIEW The unique structure made Kirsten rat sarcoma (KRAS) 'undruggable' for quite an extended period. The functional mechanism of this small protein is well illustrated. However, there is no precision medicine for nonsmall cell lung cancer (NSCLC) patients burden with KRAS mutation. The attempts made by scientists to make challenge history against KRAS mutation and their druggable targets are worth elucidating. RECENT FINDINGS The appearance of orphan drug AMG510 in the market specifically targeting KRASG12C is a tremendous breakthrough. Several KRAS inhibitors are under development now. More studies focus on combo treatment of KRAS inhibition and immune checkpoint inhibitors (ICIs). Recent preclinical and clinical investigations have been reported that NSCLC patients with KRAS mutation can benefit from ICIs. SUMMARY The current review elucidates the development of KRAS inhibitors from basic research to clinical precision medicines. We retrospectively analyze the development of KRAS mutation targeting drugs and discuss the investigations for future development of KRAS inhibitors.
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Affiliation(s)
- Yunchang Li
- Integrative Cancer Center and Cancer Clinical Research Center, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
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15
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Yang J, Zhou L, Ouyang J, Xiao X, Sun W, Li S, Zhang Q. Genotype-Phenotype Analysis of RPGR Variations: Reporting of 62 Chinese Families and a Literature Review. Front Genet 2021; 12:600210. [PMID: 34745198 PMCID: PMC8565807 DOI: 10.3389/fgene.2021.600210] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 04/27/2021] [Indexed: 02/05/2023] Open
Abstract
Purpose RPGR is the most common cause of X-linked retinitis pigmentosa (RP), of which female carriers are also frequently affected. The aim of the current study was to explore the RPGR variation spectrum and associated phenotype based on the data from our lab and previous studies. Methods Variants in RPGR were selected from exome sequencing data of 7,092 probands with different eye conditions. The probands and their available family members underwent comprehensive ocular examinations. Similar data were collected from previous reports through searches in PubMed, Web of Science, and Google Scholar. Systematic analyses of genotypes, phenotypes and their correlations were performed. Results A total of 46 likely pathogenic variants, including nine missense and one in-frame variants in RCC1-like domain and 36 truncation variants, in RPGR were detected in 62 unrelated families in our in-house cohort. In addition, a total of 585 variants, including 491 (83.9%) truncation variants, were identified from the literature. Systematic analysis of variants from our in-house dataset, literature, and gnomAD suggested that most of the pathogenic variants of RPGR were truncation variants while pathogenic missense and in-frame variants were enriched in the RCC1-like domain. Phenotypic variations were present between males and female carriers, including more severe refractive error but better best corrected visual acuity (BCVA) in female carriers than those in males. The male patients showed a significant reduction of BCVA with increase of age and males with exon1-14 variants presented a better BCVA than those with ORF15 variants. For female carriers, the BCVA also showed significant reduction with increase of age, but BCVA in females with exon1-14 variants was not significant difference compared with those with ORF15 variants. Conclusion Most pathogenic variants of RPGR are truncations. Missense and in-frame variants located outside of the RCC1-like domain might be benign and the pathogenicity criteria for these variants should be considered with greater caution. The BCVA and refractive error are different between males and female carriers. Increase of age and location of variants in ORF15 contribute to the reduction of BCVA in males. These results are valuable for understanding genotypes and phenotypes of RPGR.
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Affiliation(s)
- Junxing Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lin Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, China
| | - Jiamin Ouyang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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16
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Next-Generation Sequencing Applications for Inherited Retinal Diseases. Int J Mol Sci 2021; 22:ijms22115684. [PMID: 34073611 PMCID: PMC8198572 DOI: 10.3390/ijms22115684] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal diseases (IRDs) represent a collection of phenotypically and genetically diverse conditions. IRDs phenotype(s) can be isolated to the eye or can involve multiple tissues. These conditions are associated with diverse forms of inheritance, and variants within the same gene often can be associated with multiple distinct phenotypes. Such aspects of the IRDs highlight the difficulty met when establishing a genetic diagnosis in patients. Here we provide an overview of cutting-edge next-generation sequencing techniques and strategies currently in use to maximise the effectivity of IRD gene screening. These techniques have helped researchers globally to find elusive causes of IRDs, including copy number variants, structural variants, new IRD genes and deep intronic variants, among others. Resolving a genetic diagnosis with thorough testing enables a more accurate diagnosis and more informed prognosis and should also provide information on inheritance patterns which may be of particular interest to patients of a child-bearing age. Given that IRDs are heritable conditions, genetic counselling may be offered to help inform family planning, carrier testing and prenatal screening. Additionally, a verified genetic diagnosis may enable access to appropriate clinical trials or approved medications that may be available for the condition.
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17
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Di Iorio V, Karali M, Melillo P, Testa F, Brunetti-Pierri R, Musacchia F, Condroyer C, Neidhardt J, Audo I, Zeitz C, Banfi S, Simonelli F. Spectrum of Disease Severity in Patients With X-Linked Retinitis Pigmentosa Due to RPGR Mutations. Invest Ophthalmol Vis Sci 2021; 61:36. [PMID: 33372982 PMCID: PMC7774109 DOI: 10.1167/iovs.61.14.36] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose The purpose of this study was to perform a detailed longitudinal phenotyping of X-linked retinitis pigmentosa (RP) caused by mutations in the RPGR gene during a long follow-up period. Methods An Italian cohort of 48 male patients (from 31 unrelated families) with RPGR-associated RP was clinically assessed at a single center (mean follow-up = 6.5 years), including measurements of best-corrected visual acuity (BCVA), Goldmann visual field (GVF), optical coherence tomography (OCT), fundus autofluorescence (FAF), microperimetry, and full-field electroretinography (ERG). Results Patients (29.6 ± 15.2 years) showed a mean BCVA of 0.6 ± 0.7 logMAR, mostly with myopic refraction (79.2%). Thirty patients (62.5%) presented a typical RP fundus, while the remaining sine pigmento RP. Over the follow-up, BCVA significantly declined at a mean rate of 0.025 logMAR/year. Typical RP and high myopia were associated with a significantly faster decline of BCVA. Blindness was driven primarily by GVF loss. ERG responses with a rod-cone pattern of dysfunction were detectable in patients (50%) that were significantly younger and more frequently presented sine pigmento RP. Thirteen patients (27.1%) had macular abnormalities without cystoid macular edema. Patients (50%) with a perimacular hyper-FAF ring were significantly younger, had a higher BCVA and a better-preserved ellipsoid zone band than those with markedly decreased FAF. Patients harboring pathogenic variants in exons 1 to 14 showed a milder phenotype compared to those with ORF15 mutations. Conclusions Our monocentric, longitudinal retrospective study revealed a spectrum disease progression in male patients with RPGR-associated RP. Slow disease progression correlated with sine pigmento RP, absence of high myopia, and mutations in RPGR exons 1 to 14.
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Affiliation(s)
- Valentina Di Iorio
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
| | - Marianthi Karali
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy.,Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
| | - Paolo Melillo
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
| | - Francesco Testa
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
| | - Raffaella Brunetti-Pierri
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
| | | | | | - John Neidhardt
- Human Genetics, Faculty of Medicine and Health Sciences, University of Oldenburg, Oldenburg, Germany.,Research Center Neurosensory Science, University Oldenburg, Oldenburg, Germany
| | - Isabelle Audo
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France.,CHNO des Quinze-Vingts, DHU Sight Restore, INSERM-DGOS CIC, France.,Institute of Ophthalmology, University College of London, London, United Kingdom
| | - Christina Zeitz
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, Paris, France
| | - Sandro Banfi
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy.,Medical Genetics, Department of Precision Medicine, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, Università degli Studi della Campania "Luigi Vanvitelli," Naples, Italy
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18
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The Major Ciliary Isoforms of RPGR Build Different Interaction Complexes with INPP5E and RPGRIP1L. Int J Mol Sci 2021; 22:ijms22073583. [PMID: 33808286 PMCID: PMC8037643 DOI: 10.3390/ijms22073583] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/21/2021] [Accepted: 03/24/2021] [Indexed: 01/24/2023] Open
Abstract
X-linked retinitis pigmentosa (XLRP) is frequently caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. A complex splicing process acts on the RPGR gene resulting in three major isoforms: RPGRex1-19, RPGRORF15 and RPGRskip14/15. We characterized the widely expressed, alternatively spliced transcript RPGRskip14/15 lacking exons 14 and 15. Using the CRISPR/eSpCas9 system, we generated HEK293T cell lines exclusively expressing the RPGRskip14/15 transcript from the endogenous RPGR gene. RPGRex1-19 and RPGRORF15 were knocked out. Immunocytochemistry demonstrated that the RPGRskip14/15 protein localizes along primary cilia, resembling the expression pattern of RPGRex1-19. The number of cilia-carrying cells was not affected by the absence of the RPGRex1-19 and RPGRORF15 isoforms. Co-immunoprecipitation assays demonstrated that both RPGRex1-19 and RPGRskip14/15 interact with PDE6D, further supporting that RPGRskip14/15 is associated with the protein networks along the primary cilium. Interestingly, interaction complexes with INPP5E or RPGRIP1L were only detectable with isoform RPGRex1-19, but not with RPGRskip14/15, demonstrating distinct functional properties of the major RPGR isoforms in spite of their similar subcellular localization. Our findings lead to the conclusion that protein binding sites within RPGR are mediated through alternative splicing. A tissue-specific expression ratio between RPGRskip14/15 and RPGRex1-19 seems required to regulate the ciliary concentration of RPGR interaction partners.
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19
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Hadalin V, Šuštar M, Volk M, Maver A, Sajovic J, Jarc-Vidmar M, Peterlin B, Hawlina M, Fakin A. Cone Dystrophy Associated with a Novel Variant in the Terminal Codon of the RPGR- ORF15. Genes (Basel) 2021; 12:genes12040499. [PMID: 33805381 PMCID: PMC8066792 DOI: 10.3390/genes12040499] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/30/2022] Open
Abstract
Mutations in RPGRORF15 are associated with rod-cone or cone/cone-rod dystrophy, the latter associated with mutations at the distal end. We describe the phenotype associated with a novel variant in the terminal codon of the RPGRORF15 c.3457T>A (Ter1153Lysext*38), which results in a C-terminal extension. Three male patients from two families were recruited, aged 31, 35, and 38 years. Genetic testing was performed by whole exome sequencing. Filtered variants were analysed according to the population frequency, ClinVar database, the variant’s putative impact, and predicted pathogenicity; and were classified according to the ACMG guidelines. Examination included visual acuity (Snellen), colour vision (Ishihara), visual field, fundus autofluorescence (FAF), optical coherence tomography (OCT), and electrophysiology. All patients were myopic, and had central scotoma and reduced colour vision. Visual acuities on better eyes were counting fingers, 0.3 and 0.05. Electrophysiology showed severely reduced cone-specific responses and macular dysfunction, while the rod-specific response was normal. FAF showed hyperautofluorescent ring centred at the fovea encompassing an area of photoreceptor loss approximately two optic discs in diameter (3462–6342 μm). Follow up after 2–11 years showed enlargement of the diameter (avg. 100 μm/year). The novel c.3457T>A (Ter1153Lysext*38) mutation in the terminal RPGRORF15 codon is associated with cone dystrophy, which corresponds to the previously described phenotypes associated with mutations in the distal end of the RPGRORF15. Minimal progression during follow-up years suggests a relatively stable disease after the initial loss of the central cones.
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Affiliation(s)
- Vlasta Hadalin
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
| | - Maja Šuštar
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
| | - Marija Volk
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (A.M.); (B.P.)
| | - Aleš Maver
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (A.M.); (B.P.)
| | - Jana Sajovic
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
| | - Martina Jarc-Vidmar
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
| | - Borut Peterlin
- Clinical Institute of Medical Genetics, University Medical Centre Ljubljana, Šlajmerjeva ulica 4, 1000 Ljubljana, Slovenia; (M.V.); (A.M.); (B.P.)
| | - Marko Hawlina
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
| | - Ana Fakin
- Eye Hospital, University Medical Centre Ljubljana, Grablovičeva 46, 1000 Ljubljana, Slovenia; (V.H.); (M.Š.); (J.S.); (M.J.-V.); (M.H.)
- Correspondence:
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Qiu H, Fujisawa S, Nozaki S, Katoh Y, Nakayama K. Interaction of INPP5E with ARL13B is essential for its ciliary membrane retention but dispensable for its ciliary entry. Biol Open 2021; 10:bio057653. [PMID: 33372066 PMCID: PMC7860134 DOI: 10.1242/bio.057653] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 12/09/2020] [Indexed: 12/11/2022] Open
Abstract
Compositions of proteins and lipids within cilia and on the ciliary membrane are maintained to be distinct from those of the cytoplasm and plasma membrane, respectively, by the presence of the ciliary gate. INPP5E is a phosphoinositide 5-phosphatase that is localized on the ciliary membrane by anchorage via its C-terminal prenyl moiety. In addition, the ciliary membrane localization of INPP5E is determined by the small GTPase ARL13B. However, it remained unclear as to how ARL13B participates in the localization of INPP5E. We here show that wild-type INPP5E, INPP5E(WT), in ARL13B-knockout cells and an INPP5E mutant defective in ARL13B binding, INPP5E(ΔCTS), in control cells were unable to show steady-state localization on the ciliary membrane. However, not only INPP5E(WT) but also INPP5E(ΔCTS) was able to rescue the abnormal localization of ciliary proteins in INPP5E-knockout cells. Analysis using the chemically induced dimerization system demonstrated that INPP5E(WT) in ARL13B-knockout cells and INPP5E(ΔCTS) in control cells were able to enter cilia, but neither was retained on the ciliary membrane due to the lack of the INPP5E-ARL13B interaction. Thus, our data demonstrate that binding of INPP5E to ARL13B is essential for its steady-state localization on the ciliary membrane but is dispensable for its entry into cilia.
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Affiliation(s)
- Hantian Qiu
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Sayaka Fujisawa
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shohei Nozaki
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yohei Katoh
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kazuhisa Nakayama
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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Translational Read-Through Therapy of RPGR Nonsense Mutations. Int J Mol Sci 2020; 21:ijms21228418. [PMID: 33182541 PMCID: PMC7697989 DOI: 10.3390/ijms21228418] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/28/2020] [Accepted: 11/05/2020] [Indexed: 12/14/2022] Open
Abstract
X-chromosomal retinitis pigmentosa (RP) frequently is caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. We evaluated the potential of PTC124 (Ataluren, TranslamaTM) treatment to promote ribosomal read-through of premature termination codons (PTC) in RPGR. Expression constructs in HEK293T cells showed that the efficacy of read-through reagents is higher for UGA than UAA PTCs. We identified the novel hemizygous nonsense mutation c.1154T > A, p.Leu385* (NM_000328.3) causing a UAA PTC in RPGR and generated patient-derived fibroblasts. Immunocytochemistry of serum-starved control fibroblasts showed the RPGR protein in a dot-like expression pattern along the primary cilium. In contrast, RPGR was no longer detectable at the primary cilium in patient-derived cells. Applying PTC124 restored RPGR at the cilium in approximately 8% of patient-derived cells. RT-PCR and Western blot assays verified the pathogenic mechanisms underlying the nonsense variant. Immunofluorescence stainings confirmed the successful PTC124 treatment. Our results showed for the first time that PTC124 induces read-through of PTCs in RPGR and restores the localization of the RPGR protein at the primary cilium in patient-derived cells. These results may provide a promising new treatment option for patients suffering from nonsense mutations in RPGR or other genetic diseases.
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Abstract
Taurine is a sulfur-containing amino acid that is not incorporated into protein but is abundant in retina. Schiff base adducts that form nonenzymatically and reversibly from reactions between taurine and vitamin A aldehyde (A1T) are increased under conditions in which the visual chromophore 11-cis-retinal is more abundant. These settings include black versus albino mice, dark-adapted versus light-adapted mice, and mice expressing the Rpe65-Leu450 versus Rpe65-Met450 variant. Conversely, A1T is less abundant in mouse models deficient in 11-cis-retinal. As an amphiphile, protonated A1T may serve to facilitate retinoid trafficking and could constitute a small-molecule reserve of mobilizable 11-cis-retinal in photoreceptor cells. Visual pigment consists of opsin covalently linked to the vitamin A-derived chromophore, 11-cis-retinaldehyde. Photon absorption causes the chromophore to isomerize from the 11-cis- to all-trans-retinal configuration. Continued light sensitivity necessitates the regeneration of 11-cis-retinal via a series of enzyme-catalyzed steps within the visual cycle. During this process, vitamin A aldehyde is shepherded within photoreceptors and retinal pigment epithelial cells to facilitate retinoid trafficking, to prevent nonspecific reactivity, and to conserve the 11-cis configuration. Here we show that redundancy in this system is provided by a protonated Schiff base adduct of retinaldehyde and taurine (A1-taurine, A1T) that forms reversibly by nonenzymatic reaction. A1T was present as 9-cis, 11-cis, 13-cis, and all-trans isomers, and the total levels were higher in neural retina than in retinal pigment epithelium (RPE). A1T was also more abundant under conditions in which 11-cis-retinaldehyde was higher; this included black versus albino mice, dark-adapted versus light-adapted mice, and mice carrying the Rpe65-Leu450 versus Rpe65-450Met variant. Taurine levels paralleled these differences in A1T. Moreover, A1T was substantially reduced in mice deficient in the Rpe65 isomerase and in mice deficient in cellular retinaldehyde-binding protein; in these models the production of 11-cis-retinal is compromised. A1T is an amphiphilic small molecule that may represent a mechanism for escorting retinaldehyde. The transient Schiff base conjugate that the primary amine of taurine forms with retinaldehyde would readily hydrolyze to release the retinoid and thus may embody a pool of 11-cis-retinal that can be marshalled in photoreceptor cells.
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A novel missense variant c.G644A (p.G215E) of the RPGR gene in a Chinese family causes X-linked retinitis pigmentosa. Biosci Rep 2020; 39:220828. [PMID: 31652454 PMCID: PMC6822503 DOI: 10.1042/bsr20192235] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/11/2019] [Accepted: 09/24/2019] [Indexed: 01/01/2023] Open
Abstract
The mutations in patients with X-linked retinitis pigmentosa (xlRP) have not been well described in the Chinese population. In the present study, a five-generation Chinese retinitis pigmentosa (RP) family was recruited; targeted next-generation sequencing (TGS) was used to identify causative genes and Sanger sequencing for co-segregation. RNA-seq data analysis and revere transcriptional-polymerase chain reaction (RT-PCR) were applied to investigate gene expression patterns of RP GTPase regulator (RPGR) in human and Rpgr in mouse. A novel, hemizygous, deleterious and missense variant: c.G644A (p.G215E) in the RPGR gene (NM_000328.2) exon 7 of X-chromosome was identified in the proband, which was co-segregated with the clinical phenotypes in this family. RNA-seq data showed that RPGR is ubiquitously expressed in 27 human tissues with testis in highest, but no eye tissues data. Then the expressions for Rpgr mRNA in mice including eye tissues were conducted and showed that Rpgr transcript is ubiquitously expressed very highly in retina and testis, and highly in other eye tissues including lens, sclera, and cornea; and expressed highly in the six different developmental times of retinal tissue. Ubiquitous expression in different tissues from eye and very high expression in the retina indicated that RPGR plays a vital role in eye functions, particularly in retina. In conclusion, our study is the first to indicate that the novel missense variant c.G644A (p.G215E) in the RPGR gene might be the disease-causing mutation in this xlRP family, expanding mutation spectrum. These findings facilitate better understanding of the molecular pathogenesis of this disease; provide new insights for genetic counseling and healthcare.
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De Silva SR, Arno G, Robson AG, Fakin A, Pontikos N, Mohamed MD, Bird AC, Moore AT, Michaelides M, Webster AR, Mahroo OA. The X-linked retinopathies: Physiological insights, pathogenic mechanisms, phenotypic features and novel therapies. Prog Retin Eye Res 2020; 82:100898. [PMID: 32860923 DOI: 10.1016/j.preteyeres.2020.100898] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 08/07/2020] [Accepted: 08/21/2020] [Indexed: 02/08/2023]
Abstract
X-linked retinopathies represent a significant proportion of monogenic retinal disease. They include progressive and stationary conditions, with and without syndromic features. Many are X-linked recessive, but several exhibit a phenotype in female carriers, which can help establish diagnosis and yield insights into disease mechanisms. The presence of affected carriers can misleadingly suggest autosomal dominant inheritance. Some disorders (such as RPGR-associated retinopathy) show diverse phenotypes from variants in the same gene and also highlight limitations of current genetic sequencing methods. X-linked disease frequently arises from loss of function, implying potential for benefit from gene replacement strategies. We review X-inactivation and X-linked inheritance, and explore burden of disease attributable to X-linked genes in our clinically and genetically characterised retinal disease cohort, finding correlation between gene transcript length and numbers of families. We list relevant genes and discuss key clinical features, disease mechanisms, carrier phenotypes and novel experimental therapies. We consider in detail the following: RPGR (associated with retinitis pigmentosa, cone and cone-rod dystrophy), RP2 (retinitis pigmentosa), CHM (choroideremia), RS1 (X-linked retinoschisis), NYX (complete congenital stationary night blindness (CSNB)), CACNA1F (incomplete CSNB), OPN1LW/OPN1MW (blue cone monochromacy, Bornholm eye disease, cone dystrophy), GPR143 (ocular albinism), COL4A5 (Alport syndrome), and NDP (Norrie disease and X-linked familial exudative vitreoretinopathy (FEVR)). We use a recently published transcriptome analysis to explore expression by cell-type and discuss insights from electrophysiology. In the final section, we present an algorithm for genes to consider in diagnosing males with non-syndromic X-linked retinopathy, summarise current experimental therapeutic approaches, and consider questions for future research.
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Affiliation(s)
- Samantha R De Silva
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Gavin Arno
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony G Robson
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Ana Fakin
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Ljubljana University Medical Centre, Ljubljana, Slovenia
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Moin D Mohamed
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Alan C Bird
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Anthony T Moore
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, UCSF School of Medicine, San Francisco, CA, USA
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Andrew R Webster
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Omar A Mahroo
- UCL Institute of Ophthalmology, University College London, UK; Moorfields Eye Hospital NHS Foundation Trust, London, UK; Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, London, UK; Section of Ophthalmology, King's College London, UK; Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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Li HP, Yuan SQ, Wang XG, Sheng XL, Li XR. Myopia with X-linked retinitis pigmentosa results from a novel gross deletion of RPGR gene. Int J Ophthalmol 2020; 13:1306-1311. [PMID: 32821686 DOI: 10.18240/ijo.2020.08.18] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 06/29/2020] [Indexed: 12/31/2022] Open
Abstract
AIM To identify mutations with whole exome sequencing (WES) in a Chinese X-linked retinitis pigmentosa (XLRP) family. METHODS Patients received the comprehensive ophthalmic evaluation. Genomic DNA was extracted from peripheral blood and subjected to SureSelect Human All Exon 6+ UTR exon capture kit. The exons were sequenced as 100 base paired reads on Illumina HiSeq2500 system. Only mutations that resulted in a change in amino acid sequence were selected. A pattern of inheritance of the RP family was aligned to identified causal mutation. RESULTS We analysed the data of WES information from XLRP family. The analysis revealed a hemizygous large genomic deletion of RPGR c.29_113del was responsible for this XLRP. The gross deletion lead to a frame-shift mutation and generate stop codon at 7 animo acid behind Asp (D10Afs*7), which would serious truncate RPGR protein. The novel frame-shift mutation was found to segregate with retinitis pigmentosa (RP) phenotype in this family. Bilateral myopia was present on the male patients, but carrier female showed unilateral myopia without RP. CONCLUSION Our study identifies a novel frame-shift mutation of RPGR in a Chinese family, which would expand the spectrum of RPGR mutations. The geno-phenotypic analysis reveals a correlation between RP and myopia. Although exact mechanism of RP related myopia is still unknown, but the novel frame-shift mutation will give our hit on studying the molecular pathogenesis of RP and myopia.
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Affiliation(s)
- Hui-Ping Li
- Tianjin Medical University Eye Hospital, Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin 300384, China.,Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Ningxia Clinical Research Center on Diseases of Blindness in Eye, Yinchuan 750002, Ningxia Hui Autonomous Region, China
| | - Shi-Qin Yuan
- Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Ningxia Clinical Research Center on Diseases of Blindness in Eye, Yinchuan 750002, Ningxia Hui Autonomous Region, China
| | - Xiao-Guang Wang
- Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Ningxia Clinical Research Center on Diseases of Blindness in Eye, Yinchuan 750002, Ningxia Hui Autonomous Region, China
| | - Xun-Lun Sheng
- Department of Ophthalmology, Ningxia Eye Hospital, People's Hospital of Ningxia Hui Autonomous Region, First Affiliated Hospital of Northwest University for Nationalities, Ningxia Clinical Research Center on Diseases of Blindness in Eye, Yinchuan 750002, Ningxia Hui Autonomous Region, China
| | - Xiao-Rong Li
- Tianjin Medical University Eye Hospital, Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin 300384, China
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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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27
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Actin-based regulation of ciliogenesis - The long and the short of it. Semin Cell Dev Biol 2019; 102:132-138. [PMID: 31862221 DOI: 10.1016/j.semcdb.2019.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 11/23/2019] [Accepted: 12/07/2019] [Indexed: 12/11/2022]
Abstract
The primary cilia is found on the mammalian cell surface where it serves as an antenna for the reception and transmission of a variety of cellular signaling pathways. At its core the cilium is a microtubule-based organelle, but it is clear that its assembly and function are dependent upon the coordinated regulation of both actin and microtubule dynamics. In particular, the discovery that the centrosome is able to act as both a microtubule and actin organizing centre implies that both cytoskeletal networks are acting directly on the process of cilia assembly. In this review, we set our recent results with the formin FHDC1 in the context of current reports that show each stage of ciliogenesis is impacted by changes in actin dynamics. These include direct effects of actin filament assembly on basal body positioning, vesicle trafficking to and entry into the cilium, cilia length, cilia membrane organization and cilia-dependent signaling.
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Rare Human Diseases: Model Organisms in Deciphering the Molecular Basis of Primary Ciliary Dyskinesia. Cells 2019; 8:cells8121614. [PMID: 31835861 PMCID: PMC6952885 DOI: 10.3390/cells8121614] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/02/2019] [Accepted: 12/10/2019] [Indexed: 12/17/2022] Open
Abstract
Primary ciliary dyskinesia (PCD) is a recessive heterogeneous disorder of motile cilia, affecting one per 15,000-30,000 individuals; however, the frequency of this disorder is likely underestimated. Even though more than 40 genes are currently associated with PCD, in the case of approximately 30% of patients, the genetic cause of the manifested PCD symptoms remains unknown. Because motile cilia are highly evolutionarily conserved organelles at both the proteomic and ultrastructural levels, analyses in the unicellular and multicellular model organisms can help not only to identify new proteins essential for cilia motility (and thus identify new putative PCD-causative genes), but also to elucidate the function of the proteins encoded by known PCD-causative genes. Consequently, studies involving model organisms can help us to understand the molecular mechanism(s) behind the phenotypic changes observed in the motile cilia of PCD affected patients. Here, we summarize the current state of the art in the genetics and biology of PCD and emphasize the impact of the studies conducted using model organisms on existing knowledge.
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Zhang Z, Dai H, Wang L, Tao T, Xu J, Sun X, Yang L, Li G. Novel mutations of RPGR in Chinese families with X-linked retinitis pigmentosa. BMC Ophthalmol 2019; 19:240. [PMID: 31775781 PMCID: PMC6882249 DOI: 10.1186/s12886-019-1250-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/18/2019] [Indexed: 12/15/2022] Open
Abstract
Background RP (retinitis pigmentosa) is a group of hereditary retinal degenerative diseases. XLRP is a relatively severe subtype of RP. Thus, it is necessary to identify genes and mutations in patients who present with X-linked retinitis pigmentosa. Methods Genomic DNA was extracted from peripheral blood. The coding regions and intron-exon boundaries of the retinitis pigmentosa GTPase regulator (RPGR) and RP2 genes were amplified by PCR and then sequenced directly. Ophthalmic examinations were performed to identify affected individuals from two families and to characterize the phenotype of the disease. Results Mutation screening demonstrated two novel nonsense mutations (c.1541C > G; p.S514X and c.2833G > T; p.E945X) in the RPGR gene. The clinical manifestation of family 1 with mutations in exon 13 was mild. Genotype-phenotype correlation analysis suggested that patients with mutations close to the downstream region of ORF15 in family 2 manifested an early loss of cone function. Family 2 carried a nonsense mutation in ORF15 that appeared to have a semi-dominant pattern of inheritance. All male patients and two female carriers in family 2 manifested pathological myopia (PM), indicating that there may be a distinctive X-linked genotype-phenotype correlation between RP and PM. Conclusions We identified two novel mutations of the RPGR gene, which broadens the spectrum of RPGR mutations and the phenotypic spectrum of the disease in Chinese families.
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Affiliation(s)
- Zhimeng Zhang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Hehua Dai
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Lei Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Tianchang Tao
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Jing Xu
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Xiaowei Sun
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China
| | - Liping Yang
- Department of Ophthalmology, Key Laboratory of Vision Loss and Restoration, Ministry of Education, Peking University Third Hospital, Beijing, People's Republic of China
| | - Genlin Li
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, People's Republic of China.
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Falasconi A, Biagioni M, Novelli E, Piano I, Gargini C, Strettoi E. Retinal Phenotype in the rd9 Mutant Mouse, a Model of X-Linked RP. Front Neurosci 2019; 13:991. [PMID: 31607844 PMCID: PMC6761883 DOI: 10.3389/fnins.2019.00991] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/03/2019] [Indexed: 12/25/2022] Open
Abstract
Retinal degeneration 9 (rd9) mice carry a mutation in the retina specific “Retinitis Pigmentosa GTPase Regulator (RPGR)” Open Reading Frame (ORF) 15 gene, located on the X chromosome and represent a rare model of X-linked Retinitis Pigmentosa (XLRP), a common and severe form of retinal degeneration (Wright et al., 2010; Tsang and Sharma, 2018). The rd9 RPGR-ORF15 mutation in mice causes lack of the protein in photoreceptors and a slow degeneration of these cells with consequent decrease in Outer Nuclear Layer (ONL) thickness and amplitude of ERG responses, as previously described (Thompson et al., 2012). However, relative rates of rod and cone photoreceptor loss, as well as secondary alterations occurring in neuronal and non-neuronal retinal cell types of rd9 mutants remain to be assessed. Aim of this study is to extend phenotype analysis of the rd9 mouse retina focusing on changes occurring in cells directly interacting with photoreceptors. To this purpose, first we estimated rod and cone survival and its degree of intraretinal variation over time; then, we studied the morphology of horizontal and bipolar cells and of the retinal pigment epithelium (RPE), extending our observations to glial cell reactivity. We found that in rd9 retinas rod (but not cone) death is the main cause of decrease in ONL thickness and that degeneration shows a high degree of intraretinal variation. Rod loss drives remodeling in the outer retina, with sprouting of second-order neurons of the rod-pathway and relative sparing of cone pathway elements. Remarkably, despite cone survival, functional defects can be clearly detected in ERG recordings in both scotopic and photopic conditions. Moderate levels of Muller cells and microglial reactivity are sided by striking attenuation of staining for RPE tight junctions, suggesting altered integrity of the outer Blood Retina Barrier (BRB). Because of many features resembling slowly progressing photoreceptor degeneration paradigms or early stages of more aggressive forms of RP, the rd9 mouse model can be considered a rare and useful tool to investigate retinal changes associated to a process of photoreceptor death sustained throughout life and to reveal disease biomarkers (e.g., BRB alterations) of human XLRP.
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Affiliation(s)
- Antonio Falasconi
- Institute of Neuroscience, National Research Council (CNR), Pisa, Italy.,Sant'Anna School of Advanced Studies, Pisa, Italy
| | - Martina Biagioni
- Institute of Neuroscience, National Research Council (CNR), Pisa, Italy
| | - Elena Novelli
- Institute of Neuroscience, National Research Council (CNR), Pisa, Italy
| | - Ilaria Piano
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | | | - Enrica Strettoi
- Institute of Neuroscience, National Research Council (CNR), Pisa, Italy
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31
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Cehajic Kapetanovic J, McClements ME, Martinez-Fernandez de la Camara C, MacLaren RE. Molecular Strategies for RPGR Gene Therapy. Genes (Basel) 2019; 10:genes10090674. [PMID: 31487940 PMCID: PMC6770968 DOI: 10.3390/genes10090674] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 08/27/2019] [Accepted: 09/01/2019] [Indexed: 11/16/2022] Open
Abstract
Mutations affecting the Retinitis Pigmentosa GTPase Regulator (RPGR) gene are the commonest cause of X-linked and recessive retinitis pigmentosa (RP), accounting for 10%-20% of all cases of RP. The phenotype is one of the most severe amongst all causes of RP, characteristic for its early onset and rapid progression to blindness in young people. At present there is no cure for RPGR-related retinal disease. Recently, however, there have been important advances in RPGR research from bench to bedside that increased our understanding of RPGR function and led to the development of potential therapies, including the progress of adeno-associated viral (AAV)-mediated gene replacement therapy into clinical trials. This manuscript discusses the advances in molecular research, which have connected the RPGR protein with an important post-translational modification, known as glutamylation, that is essential for its optimal function as a key regulator of photoreceptor ciliary transport. In addition, we review key pre-clinical research that addressed challenges encountered during development of therapeutic vectors caused by high infidelity of the RPGR genomic sequence. Finally, we discuss the structure of three current phase I/II clinical trials based on three AAV vectors and RPGR sequences and link the rationale behind the use of the different vectors back to the bench research that led to their development.
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Affiliation(s)
- Jasmina Cehajic Kapetanovic
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK. '
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK. '
| | | | - Cristina Martinez-Fernandez de la Camara
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, University of Oxford, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford OX3 9DU, UK
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