1
|
Zhou Y, Huang L, Xie Y, Liu W, Zhang S, Liu L, Lin P, Li N. Clinical and genetic studies for a cohort of patients with Leber congenital amaurosis. Graefes Arch Clin Exp Ophthalmol 2024:10.1007/s00417-024-06450-9. [PMID: 38662103 DOI: 10.1007/s00417-024-06450-9] [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: 11/08/2023] [Revised: 02/28/2024] [Accepted: 03/08/2024] [Indexed: 04/26/2024] Open
Abstract
PURPOSE Leber congenital amaurosis (LCA) is a group of early-onset retinal degenerative disorders, resulting in blindness in children. This study aimed to describe the clinical and genetic characteristics of a cohort of patients with LCA and to investigate the retinal vascular characteristics in LCA patients. METHODS Fifty-two children with LCA were included in the study. All patients underwent detailed ocular examinations. Electroretinography (ERG) was used to evaluate the retinal function. Optical coherence tomography (OCT) was used to assess the structure change of the retina for those patients who were able to cooperate very well. Panel-based next-generation sequencing was performed to identify pathogenic variants in genes associated with LCA. Diameters of the retinal vessels were measured using the EVision AI screening system with an artificial intelligence (AI) technique. An ultrasound Doppler was used to evaluate hemodynamic parameters, including peak systolic velocity (PSV), resistive index (RI), and pulsatility index (PI), in the ophthalmic, central retinal, posterior ciliary, carotid, and internal carotid as well as external carotid arteries in 12 patients aged from 3 to 14 years. RESULTS We detected 75 pathogenic variants from ten genes of RPGRIP1, CEP290, GUCY2D, LCA5, AIPL1, CRB1, RPE65, CRX, RDH12, and TULP1, including 29 novel and 36 previously reported variants in 52 affected children with LCA, with the highest detective rate in RPGRIP1 (26.9%). Fundus appearance is diverse in patients with LCA, ranging from normal to severe peripheral or central retinopathy. Retinal vasculature was evaluated in 12 patients with different gene variants, showing narrowed arteries with an average diameter of 43.6 ± 3.8 μm compared to that of 51.7 ± 2.6 μm in the normal controls (P < 0.001, n = 12). Meanwhile, their hemodynamic parameters were changed as well in the ophthalmic artery (OA), with a decreased PSV (P = 0.0132, n = 12) and slightly increased PI (P = 0.0488, n = 12) compared to the normal controls. However, the hemodynamic parameters did not change significantly in the other vessels. CONCLUSIONS Blood supply to the eyeball is predicted to be reduced in patients with LCA, presumably due to photoreceptor cell degeneration. The novel identified variants will expand the spectrum of variants in LCA-related genes and be useful for studying the molecular mechanisms of LCA.
Collapse
Affiliation(s)
- Yunyu Zhou
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Lijuan Huang
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
- Department of Ophthalmology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, China
| | - Yan Xie
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Wen Liu
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Shasha Zhang
- Department of Ophthalmology, Xi'an Children's Hospital, Xi'an, 710002, China
| | - Lili Liu
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China
| | - Ping Lin
- Department of Ophthalmology, Xi'an Children's Hospital, Xi'an, 710002, China.
| | - Ningdong Li
- Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, 100045, China.
- Department of Ophthalmology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, 362000, China.
- Department of Ophthalmology, Xi'an Children's Hospital, Xi'an, 710002, China.
- Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200940, China.
| |
Collapse
|
2
|
Torii K, Nishina S, Morikawa H, Mizobuchi K, Takayama M, Tachibana N, Kurata K, Hikoya A, Sato M, Nakano T, Fukami M, Azuma N, Hayashi T, Saitsu H, Hotta Y. The Structural Abnormalities Are Deeply Involved in the Cause of RPGRIP1-Related Retinal Dystrophy in Japanese Patients. Int J Mol Sci 2023; 24:13678. [PMID: 37761981 PMCID: PMC10531429 DOI: 10.3390/ijms241813678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Revised: 08/31/2023] [Accepted: 09/02/2023] [Indexed: 09/29/2023] Open
Abstract
Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophy. RPGRIP1-related LCA accounts for 5-6% of LCA. We performed whole-exome sequencing and whole-genome sequencing (WGS) on 29 patients with clinically suspected LCA and examined ophthalmic findings in patients with biallelic pathogenic variants of RPGRIP1. In addition to five previously reported cases, we identified five cases from four families with compound heterozygous RPGRIP1 variants using WGS. Five patients had null variants comprising frameshift variants, an Alu insertion, and microdeletions. A previously reported 1339 bp deletion involving exon 18 was found in four cases, and the deletion was relatively prevalent in the Japanese population (allele frequency: 0.002). Microdeletions involving exon 1 were detected in four cases. In patients with RPGRIP1 variants, visual acuity remained low, ranging from light perception to 0.2, and showed no correlation with age. In optical coherence tomography images, the ellipsoid zone (EZ) length decreased with age in all but one case of unimpaired EZ. The retinal structure was relatively preserved in all cases; however, there were cases with great differences in visual function compared to their siblings and a 56-year-old patient who still had a faint EZ line. Structural abnormalities may be important genetic causes of RPGRIP1-related retinal dystrophy in Japanese patients, and WGS was useful for detecting them.
Collapse
Affiliation(s)
- Kaoruko Torii
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Sachiko Nishina
- Division of Ophthalmology, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
| | - Hazuki Morikawa
- Division of Ophthalmology, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
| | - Kei Mizobuchi
- Department of Ophthalmology, The Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Masakazu Takayama
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Nobutaka Tachibana
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Kentaro Kurata
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Akiko Hikoya
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Miho Sato
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Tadashi Nakano
- Department of Ophthalmology, The Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
| | - Noriyuki Azuma
- Division of Ophthalmology, National Center for Child Health and Development, 2-10-1 Okura, Setagaya-ku, Tokyo 157-8535, Japan
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Takaaki Hayashi
- Department of Ophthalmology, The Jikei University School of Medicine, 3-25-8 Nishi-shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Yoshihiro Hotta
- Department of Ophthalmology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| |
Collapse
|
3
|
A tapt1 knock-out zebrafish line with aberrant lens development and impaired vision models human early-onset cataract. Hum Genet 2023; 142:457-476. [PMID: 36697720 DOI: 10.1007/s00439-022-02518-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/19/2022] [Indexed: 01/27/2023]
Abstract
Bi-allelic mutations in the gene coding for human trans-membrane anterior-posterior transformation protein 1 (TAPT1) result in a broad phenotypic spectrum, ranging from syndromic disease with severe skeletal and congenital abnormalities to isolated early-onset cataract. We present here the first patient with a frameshift mutation in the TAPT1 gene, resulting in both bilateral early-onset cataract and skeletal abnormalities, in addition to several dysmorphic features, in this way further expanding the phenotypic spectrum associated with TAPT1 mutations. A tapt1a/tapt1b double knock-out (KO) zebrafish model generated by CRISPR/Cas9 gene editing revealed an early larval phenotype with eye malformations, loss of vision, increased photokinetics and hyperpigmentation, without visible skeletal involvement. Ultrastructural analysis of the eyes showed a smaller condensed lens, loss of integrity of the lens capsule with formation of a secondary lens and hyperplasia of the cells in the ganglion and inner plexiform layers of the retina. Transcriptomic analysis pointed to an impaired lens development with aberrant expression of many of the crystallin and other lens-specific genes. Furthermore, the phototransduction and visual perception pathways were found to be significantly disturbed. Differences in light perception are likely the cause of the increased dark photokinetics and generalized hyperpigmentation observed in this zebrafish model. In conclusion, this study validates TAPT1 as a new gene for early-onset cataract and sheds light on its ultrastructural and molecular characteristics.
Collapse
|
4
|
Liu Z, Wang H, He X, Tao D, Li L. Identifying two pathogenic variants in a patient with pigmented paravenous retinochoroidal atrophy. Open Life Sci 2023; 18:20220532. [PMID: 36713053 PMCID: PMC9843229 DOI: 10.1515/biol-2022-0532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/06/2022] [Accepted: 11/02/2022] [Indexed: 01/17/2023] Open
Abstract
Little is known about the genetic background of pigmented paravenous retinochoroidal atrophy (PPRCA) due to rarity of patients. In this study, we identified two pathogenic variants in RPGRIP1 in a 2-year-old boy with PPRCA screened by whole-exome sequencing (WES). The patient presented to our department with photophobia for 17 months, and then he underwent fundus photography and fluorescein fundus angiography. Genomic DNA was extracted from peripheral blood of the proband and the parents. Trio-WES strategy was utilized to identify the causal variants from the proband and the parents, followed by validation based on Sanger sequencing. The patient was finally diagnosed with PPRCA after differential diagnosis. Two heterozygous pathogenic variants were detected by WES according to the American college of medical genetics and genomics guidelines, including NM_020366.4: c.2592T > G: p.Y864* and NM_020366.4: c.154C > T: p.R52* in RPGRIP1 located in exon 17 and exon 3, leading to termination codon, respectively. This is the first study reporting pathogenic variants within RPGRIP1 as causal for PPRCA.
Collapse
Affiliation(s)
- Zeyuan Liu
- Department of Ophthalmology, Kunming Children’s Hospital, No. 288, Qianxing Road, Xishan District, Kunming 650228, China
| | - He Wang
- Department of Ophthalmology, Kunming Children’s Hospital, No. 288, Qianxing Road, Xishan District, Kunming 650228, China
| | - Xiaoli He
- Department of Ophthalmology, Kunming Children’s Hospital, Yunnan Institute of Pediatrics, Yunnan Province Clinical Research Center for Children’s Health and Disease, Yunnan Key Laboratory of Children’s Major Disease Research, No. 288, Qianxing Road, Xishan District, Kunming 650228, China
| | - Dan Tao
- Department of Ophthalmology, Kunming Children’s Hospital, No. 288, Qianxing Road, Xishan District, Kunming 650228, China
| | - Li Li
- Department of Ophthalmology, Kunming Children’s Hospital, Yunnan Institute of Pediatrics, Yunnan Province Clinical Research Center for Children’s Health and Disease, Yunnan Key Laboratory of Children’s Major Disease Research, No. 288, Qianxing Road, Xishan District, Kunming 650228, China
| |
Collapse
|
5
|
Cehajic-Kapetanovic J, Martinez-Fernandez de la Camara C, Birtel J, Rehman S, McClements ME, Charbel Issa P, Lotery AJ, MacLaren RE. Impaired glutamylation of RPGR ORF15 underlies the cone-dominated phenotype associated with truncating distal ORF15 variants. Proc Natl Acad Sci U S A 2022; 119:e2208707119. [PMID: 36445968 PMCID: PMC9897430 DOI: 10.1073/pnas.2208707119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Pathogenic variants in the Retinitis pigmentosa GTPase regulator (RPGR) gene lead to a clinically severe form of X-linked retinal dystrophy. However, it remains unclear why some variants cause a predominant rod, while others result in a cone-dominated phenotype. Post-translational glutamylation of the photoreceptor-specific RPGRORF15 isoform by the TTLL5 enzyme is essential for its optimal function in photoreceptors, and loss of TTLL5 leads to retinal dystrophy with a cone phenotype. Here we show that RPGR retinal disease, studied in a single cohort of 116 male patients, leads to a clear progressive shift from rod- to cone-dominating phenotype as the RPGRORF15 variant location approaches the distal part of the Open Reading Frame 15 (ORF15) region. The rod photoreceptor involvement on the contrary diminishes along the RGPR sequence, and the variants associated with the cone only phenotype are located predominantly in the very distal part, including the C-terminal basic domain. Moreover, these distal truncating RPGRORF15 variants disrupt the interaction with TTLL5 and lead to a significant impairment of RPGR glutamylation. Thus, consistent with the phenotype of TTLL5 pathogenic variants, our study shows that RPGRORF15 variants, which disrupt its basic domain and the interaction with TTLL5, also impair RPGR glutamylation and lead to the cone phenotype. This has implications for ongoing gene therapy clinical trials where the application of RPGR with impaired glutamylation may be less effective in treating RGPR dystrophies and may even convert a rod-cone dystrophy into a cone dystrophy phenotype.
Collapse
Affiliation(s)
- Jasmina Cehajic-Kapetanovic
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
| | - Cristina Martinez-Fernandez de la Camara
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
| | - Johannes Birtel
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- cDepartment of Ophthalmology, University of Bonn, 53127Bonn, Germany
| | - Salwah Rehman
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Michelle E. McClements
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Peter Charbel Issa
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
| | - Andrew J Lotery
- dClinical Neurosciences Research Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, SO16 6YDSouthampton, United Kingdom
- eUniversity Hospital Southampton NHS Foundation Trust, SO16 6YDSouthampton, United Kingdom
| | - Robert E. MacLaren
- aNuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Level 5 & 6, West WingOX3 9DU, United Kingdom
- bOxford Eye Hospital, Oxford University Hospitals The National Health Service Trust, John Radcliffe Hospital, West WingOX3 9DU, United Kingdom
- 2To whom correspondence may be addressed.
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Hyde LF, Kong Y, Zhao L, Rao SR, Wang J, Stone L, Njaa A, Collin GB, Krebs MP, Chang B, Fliesler SJ, Nishina PM, Naggert JK. A Dpagt1 Missense Variant Causes Degenerative Retinopathy without Myasthenic Syndrome in Mice. Int J Mol Sci 2022; 23:12005. [PMID: 36233305 PMCID: PMC9570038 DOI: 10.3390/ijms231912005] [Citation(s) in RCA: 2] [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: 07/29/2022] [Revised: 09/29/2022] [Accepted: 10/04/2022] [Indexed: 01/12/2023] Open
Abstract
Congenital disorders of glycosylation (CDG) are a heterogenous group of primarily autosomal recessive mendelian diseases caused by disruptions in the synthesis of lipid-linked oligosaccharides and their transfer to proteins. CDGs usually affect multiple organ systems and vary in presentation, even within families. There is currently no cure, and treatment is aimed at ameliorating symptoms and improving quality of life. Here, we describe a chemically induced mouse mutant, tvrm76, with early-onset photoreceptor degeneration. The recessive mutation was mapped to Chromosome 9 and associated with a missense mutation in the Dpagt1 gene encoding UDP-N-acetyl-D-glucosamine:dolichyl-phosphate N-acetyl-D-glucosaminephosphotransferase (EC 2.7.8.15). The mutation is predicted to cause a substitution of aspartic acid with glycine at residue 166 of DPAGT1. This represents the first viable animal model of a Dpagt1 mutation and a novel phenotype for a CDG. The increased expression of Ddit3, and elevated levels of HSPA5 (BiP) suggest the presence of early-onset endoplasmic reticulum (ER) stress. These changes were associated with the induction of photoreceptor apoptosis in tvrm76 retinas. Mutations in human DPAGT1 cause myasthenic syndrome-13 and severe forms of a congenital disorder of glycosylation Type Ij. In contrast, Dpagt1tvrm76 homozygous mice present with congenital photoreceptor degeneration without overt muscle or muscular junction involvement. Our results suggest the possibility of DPAGT1 mutations in human patients that present primarily with retinitis pigmentosa, with little or no muscle disease. Variants in DPAGT1 should be considered when evaluating cases of non-syndromic retinal degeneration.
Collapse
Affiliation(s)
| | - Yang Kong
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
- The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
| | - Lihong Zhao
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Research Service, VA Western New York Healthcare System, Buffalo, NY 14215, USA
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Lisa Stone
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Andrew Njaa
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | | | - Mark P Krebs
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, ME 04609, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14203, USA
- Research Service, VA Western New York Healthcare System, Buffalo, NY 14215, USA
| | | | | |
Collapse
|
8
|
Li X, Alhasani RH, Cao Y, Zhou X, He Z, Zeng Z, Strang N, Shu X. Gypenosides Alleviate Cone Cell Death in a Zebrafish Model of Retinitis Pigmentosa. Antioxidants (Basel) 2021; 10:antiox10071050. [PMID: 34209942 PMCID: PMC8300748 DOI: 10.3390/antiox10071050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/09/2021] [Accepted: 06/22/2021] [Indexed: 01/05/2023] Open
Abstract
Retinitis pigmentosa (RP) is a group of visual disorders caused by mutations in over 70 genes. RP is characterized by initial degeneration of rod cells and late cone cell death, regardless of genetic abnormality. Rod cells are the main consumers of oxygen in the retina, and after the death of rod cells, the cone cells have to endure high levels of oxygen, which in turn leads to oxidative damage and cone degeneration. Gypenosides (Gyp) are major dammarane-type saponins of Gynostemma pentaphyllum that are known to reduce oxidative stress and inflammation. In this project we assessed the protective effect of Gyp against cone cell death in the rpgrip1 mutant zebrafish, which recapitulate the classical pathological features found in RP patients. Rpgrip1 mutant zebrafish were treated with Gyp (50 µg/g body weight) from two-months post fertilization (mpf) until 6 mpf. Gyp treatment resulted in a significant decrease in cone cell death compared to that of untreated mutant zebrafish. A markedly low level of reactive oxygen species and increased expression of antioxidant genes were detected in Gyp-incubated mutant zebrafish eyes compared to that of untreated mutant zebrafish. Similarly, the activities of catalase and superoxide dismutase and the level of glutathione were significantly increased in Gyp-treated mutant zebrafish eyes compared to that of untreated mutant zebrafish. Gyp treatment also decreased endoplasmic reticulum stress in rpgrip1 mutant eyes. Expression of proinflammatory cytokines was also significantly decreased in Gyp-treated mutant zebrafish eyes compared to that of untreated mutant zebrafish. Network pharmacology analysis demonstrated that the promotion of cone cell survival by Gyp is possibly mediated by multiple hub genes and associated signalling pathways. These data suggest treatment with Gyp will benefit RP patients.
Collapse
Affiliation(s)
- Xing Li
- School of Basic Medical Sciences, Shaoyang University, Shaoyang 422000, China; (X.L.); (Y.C.); (Z.H.)
| | - Reem Hasaballah Alhasani
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (R.H.A.); (X.Z.)
- Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah 21961, Saudi Arabia
| | - Yanqun Cao
- School of Basic Medical Sciences, Shaoyang University, Shaoyang 422000, China; (X.L.); (Y.C.); (Z.H.)
| | - Xinzhi Zhou
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (R.H.A.); (X.Z.)
| | - Zhiming He
- School of Basic Medical Sciences, Shaoyang University, Shaoyang 422000, China; (X.L.); (Y.C.); (Z.H.)
| | - Zhihong Zeng
- College of Biological and Environmental Engineering, Changsha University, Changsha 410022, China;
| | - Niall Strang
- Department of Vision Science, Glasgow Caledonian University, Glasgow G4 0BA, UK;
| | - Xinhua Shu
- School of Basic Medical Sciences, Shaoyang University, Shaoyang 422000, China; (X.L.); (Y.C.); (Z.H.)
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow G4 0BA, UK; (R.H.A.); (X.Z.)
- Department of Vision Science, Glasgow Caledonian University, Glasgow G4 0BA, UK;
- Correspondence:
| |
Collapse
|
9
|
Jiang K, Fairless E, Kanda A, Gotoh N, Cogliati T, Li T, Swaroop A. Divergent Effects of HSP70 Overexpression in Photoreceptors During Inherited Retinal Degeneration. Invest Ophthalmol Vis Sci 2021; 61:25. [PMID: 33107904 PMCID: PMC7594617 DOI: 10.1167/iovs.61.12.25] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Purpose Disruption of proteostasis is a key event in many neurodegenerative diseases. Heat shock proteins (HSPs) participate in multiple functions associated with intracellular transport and proteostasis. We evaluated the effect of augmented HSP70 expression in mutant photoreceptors of mouse retinal degeneration models to test the hypothesis that failure to sustain HSP70 expression contributes to photoreceptor cell death. Methods We examined HSP70 expression in retinas of wild-type and mutant mice by RNA and protein analysis. A transgenic mouse line, TgCrx-Hspa1a-Flag, was generated to express FLAG-tagged full-length HSP70 protein under control of a 2.3 kb mouse Crx promoter. This line was crossed to three distinct retinal degeneration mouse models. Retinal structure and function were evaluated by histology, immunohistochemistry, and electroretinography. Results In seven different mouse models of retinal degeneration, we detected transient elevation of endogenous HSP70 expression at early stages, followed by a dramatic reduction as cell death ensues, suggesting an initial adaptive response to cellular stress. Augmented expression of HSP70 in RHOT17M mice, in which mutant rhodopsin is misfolded, marginally improved photoreceptor survival, whereas elevated HSP70 led to more severe retinal degeneration in rd10 mutants that produce a partially functional PDE6B. In Rpgrip1−/− mice that display a ciliary defect, higher HSP70 had no impact on photoreceptor survival or function. Conclusions HSP70 overexpression has divergent effects in photoreceptors determined, at least in part, by the nature of the mutant protein each model carries. Additional investigations on HSP pathways and associated chaperone networks in photoreceptors are needed before designing therapeutic strategies targeting proteostasis.
Collapse
Affiliation(s)
- Ke Jiang
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Elizabeth Fairless
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Atsuhiro Kanda
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Norimoto Gotoh
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Tiziana Cogliati
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Tiansen Li
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anand Swaroop
- Neurobiology, Neurodegeneration, and Repair Laboratory (NNRL), National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| |
Collapse
|
10
|
Zou G, Zhang T, Cheng X, Igelman AD, Wang J, Qian X, Fu S, Wang K, Koenekoop RK, Fishman GA, Yang P, Li Y, Pennesi ME, Chen R. Noncoding mutation in RPGRIP1 contributes to inherited retinal degenerations. Mol Vis 2021; 27:95-106. [PMID: 33907365 PMCID: PMC8056464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/16/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose Despite the extensive use of next-generation sequencing (NGS) technology to identify disease-causing genomic variations, a major gap in our understanding of Mendelian diseases is the unidentified molecular lesion in a significant portion of patients. For inherited retinal degenerations (IRDs), although currently close to 300 disease-associated genes have been identified, the mutations in approximately one-third of patients remain unknown. With mounting evidence that noncoding mutations might contribute significantly to disease burden, we aimed to systematically investigate the contributions of noncoding regions in the genome to IRDs. Methods In this study, we focused on RPGRIP1, which has been linked to various IRD phenotypes, including Leber congenital amaurosis (LCA), retinitis pigmentosa (RP), and macular dystrophy (MD). As several noncoding mutant alleles have been reported in RPGRIP1, and we observed that the mutation carrier frequency of RPGRIP1 is higher in patient cohorts with unsolved IRDs, we hypothesized that mutations in the noncoding regions of RPGRIP1 might be a significant contributor to pathogenicity. To test this hypothesis, we performed whole-genome sequencing (WGS) for 25 patients with unassigned IRD who carry a single mutation in RPGRIP1. Results Three noncoding variants in RPGRIP1, including a 2,890 bp deletion and two deep-intronic variants (c.2710+233G>A and c.1468-263G>C), were identified as putative second hits of RPGRIP1 in three patients with LCA. The mutant alleles were validated with direct sequencing or in vitro assays. Conclusions The results highlight the significance of the contribution of noncoding pathogenic variants to unsolved IRD cases.
Collapse
Affiliation(s)
- Gang Zou
- 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, China
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Tao Zhang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Xuesen Cheng
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Austin D. Igelman
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon
| | - Jun Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Xinye Qian
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Shangyi Fu
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Keqing Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Robert K. Koenekoop
- Department of Paediatric Surgery, Human Genetics and Adult Ophthalmology, MUHC, Montréal, Quebec, Canada
| | - Gerald A. Fishman
- Pangere Center for Inherited Retinal Diseases, The Chicago Lighthouse, Chicago, IL
| | - Paul Yang
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon
| | - Yumei Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| | - Mark E. Pennesi
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon
| | - Rui Chen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas
| |
Collapse
|
11
|
Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 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: 10/30/2020] [Accepted: 02/09/2021] [Indexed: 01/14/2023] Open
Abstract
Ciliopathies are a group of heterogeneous inherited disorders associated with dysfunction of the cilium, a ubiquitous microtubule-based organelle involved in a broad range of cellular functions. Most ciliopathies are syndromic, since several organs whose cells produce a cilium, such as the retina, cochlea or kidney, are affected by mutations in ciliary-related genes. In the retina, photoreceptor cells present a highly specialized neurosensory cilium, the outer segment, stacked with membranous disks where photoreception and phototransduction occurs. The daily renewal of the more distal disks is a unique characteristic of photoreceptor outer segments, resulting in an elevated protein demand. All components necessary for outer segment formation, maintenance and function have to be transported from the photoreceptor inner segment, where synthesis occurs, to the cilium. Therefore, efficient transport of selected proteins is critical for photoreceptor ciliogenesis and function, and any alteration in either cargo delivery to the cilium or intraciliary trafficking compromises photoreceptor survival and leads to retinal degeneration. To date, mutations in more than 100 ciliary genes have been associated with retinal dystrophies, accounting for almost 25% of these inherited rare diseases. Interestingly, not all mutations in ciliary genes that cause retinal degeneration are also involved in pleiotropic pathologies in other ciliated organs. Depending on the mutation, the same gene can cause syndromic or non-syndromic retinopathies, thus emphasizing the highly refined specialization of the photoreceptor neurosensory cilia, and raising the possibility of photoreceptor-specific molecular mechanisms underlying common ciliary functions such as ciliary transport. In this review, we will focus on ciliary transport in photoreceptor cells and discuss the molecular complexity underpinning retinal ciliopathies, with a special emphasis on ciliary genes that, when mutated, cause either syndromic or non-syndromic retinal ciliopathies.
Collapse
Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| |
Collapse
|
12
|
Perrault I, Hanein S, Gérard X, Mounguengue N, Bouyakoub R, Zarhrate M, Fourrage C, Jabot-Hanin F, Bocquet B, Meunier I, Zanlonghi X, Kaplan J, Rozet JM. Whole Locus Sequencing Identifies a Prevalent Founder Deep Intronic RPGRIP1 Pathologic Variant in the French Leber Congenital Amaurosis Cohort. Genes (Basel) 2021; 12:genes12020287. [PMID: 33670832 PMCID: PMC7922592 DOI: 10.3390/genes12020287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/10/2021] [Accepted: 02/16/2021] [Indexed: 01/04/2023] Open
Abstract
Leber congenital amaurosis (LCA) encompasses the earliest and most severe retinal dystrophies and can occur as a non-syndromic or a syndromic disease. Molecular diagnosis in LCA is of particular importance in clinical decision-making and patient care since it can provide ocular and extraocular prognostics and identify patients eligible to develop gene-specific therapies. Routine high-throughput molecular testing in LCA yields 70%–80% of genetic diagnosis. In this study, we aimed to investigate the non-coding regions of one non-syndromic LCA gene, RPGRIP1, in a series of six families displaying one single disease allele after a gene-panel screening of 722 LCA families which identified 26 biallelic RPGRIP1 families. Using trio-based high-throughput whole locus sequencing (WLS) for second disease alleles, we identified a founder deep intronic mutation (NM_020366.3:c.1468-128T>G) in 3/6 families. We employed Sanger sequencing to search for the pathologic variant in unresolved LCA cases (106/722) and identified three additional families (two homozygous and one compound heterozygous with the NM_020366.3:c.930+77A>G deep intronic change). This makes the c.1468-128T>G the most frequent RPGRIP1 disease allele (8/60, 13%) in our cohort. Studying patient lymphoblasts, we show that the pathologic variant creates a donor splice-site and leads to the insertion of the pseudo-exon in the mRNA, which we were able to hamper using splice-switching antisense oligonucleotides (AONs), paving the way to therapies.
Collapse
Affiliation(s)
- Isabelle Perrault
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
- Correspondence:
| | - Sylvain Hanein
- Translational Genetics, Institute of Genetic Diseases, INSERM UMR1163, Imagine and Paris Descartes University, 75015 Paris, France;
| | - Xavier Gérard
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
| | - Nelson Mounguengue
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
| | - Ryme Bouyakoub
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
| | - Mohammed Zarhrate
- Genomics Platform, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France;
| | - Cécile Fourrage
- Bioinformatic Platform, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (C.F.); (F.J.-H.)
| | - Fabienne Jabot-Hanin
- Bioinformatic Platform, Institute of Genetic Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (C.F.); (F.J.-H.)
- Bioinformatics Core Facility, Université Paris Descartes-Structure Fédérative de Recherche Necker, INSERM US24/CNRS UMS3633, 75015 Paris, France
| | - Béatrice Bocquet
- Centre de Référence des Affections Sensorielles Génétiques, Institut des Neurosciences de Montpellier, CHU-Saint Eloi Montpellier, 34091 Montpellier, France; (B.B.); (I.M.)
| | - Isabelle Meunier
- Centre de Référence des Affections Sensorielles Génétiques, Institut des Neurosciences de Montpellier, CHU-Saint Eloi Montpellier, 34091 Montpellier, France; (B.B.); (I.M.)
- National Reference Centre for Inherited Sensory Diseases, Univ Montpellier, CHU, 34091 Montpellier, France
| | - Xavier Zanlonghi
- Eye Clinic Jules Verne, 44300 Nantes, France;
- CHU, 35000 Rennes, France
| | - Josseline Kaplan
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
- Ophthalmology Department, University Hospital Henri Mondor, APHP, 94000 Créteil, France
| | - Jean-Michel Rozet
- Laboratory of Genetics in Ophthalmology (LGO), INSERM UMR1163, Institute of Genetics Diseases, Imagine and Paris Descartes University, 75015 Paris, France; (X.G.); (N.M.); (R.B.); (J.K.); (J.-M.R.)
| |
Collapse
|
13
|
Alhasani RH, Zhou X, Biswas L, Li X, Reilly J, Zeng Z, Shu X. Gypenosides attenuate retinal degeneration in a zebrafish retinitis pigmentosa model. Exp Eye Res 2020; 201:108291. [PMID: 33049273 DOI: 10.1016/j.exer.2020.108291] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 09/07/2020] [Accepted: 10/05/2020] [Indexed: 12/16/2022]
Abstract
Retinitis pigmentosa (RP) is a collection of heterogenous genetic retinal disorders resulting in cumulative retinal deterioration involving progressive loss of photoreceptors and eventually in total blindness. Oxidative stress plays a central role in this photoreceptor loss. Gypenosides (Gyp) are the main functional component isolated from the climbing vine Gynostemma pentaphyllum and have been shown to defend cells against the effects of oxidative stress and inflammation, providing protection in experimentally-induced optic neuritis. The zebrafish model has been used to investigate a range of human diseases. Previously we reported early retinal degeneration in a mutant zebrafish line carrying a point-nonsense mutation in the retinitis pigmentosa GTPase regulator interacting protein 1 (rpgrip1) gene that is mutated in RP patients. The current study investigated the potential protective effects of Gyp against photoreceptor degeneration in the Rpgrip1 deleted zebrafish. Rpgrip1 mutant zebrafish were treated with 5 μg/ml of Gyp in E3 medium from 6 h post fertilization (hpf) till 1 month post fertilization (mpf). Rpgrip1 mutant zebrafish treated with 5 μg/ml of Gyp showed a significant decrease by 68.41% (p = 0.0002) in photoreceptor cell death compared to that of untreated mutant zebrafish. Expression of antioxidant genes catalase, sod1, sod2, gpx1, gclm, nqo-1 and nrf-2 was significantly decreased in rpgrip1 mutant zebrafish eyes by 61.51%, 77.40%, 60.11%, 81.17%, 72.07%, 78.95% and 85.42% (all p < 0.0001), respectively, when compared to that of wildtype zebrafish; superoxide dismutase and catalase activities, and glutathione levels in rpgrip1 mutant zebrafish eyes were significantly decreased by 87.21%, 21.55% and 96.51% (all p < 0.0001), respectively. There were marked increases in the production of reactive oxygen species (ROS) and malondialdehyde (MDA) by 2738.73% and 510.69% (all p < 0.0001), respectively, in rpgrip1 mutant zebrafish eyes; expression of pro-inflammatory cytokines IL-1β, IL-6 and TNF-α was also significantly increased by 150.11%, 267.79% and 190.72% (all p < 0.0001), respectively, in rpgrip1 mutant zebrafish eyes, compared to that of wildtype zebrafish. Treatment with Gyp significantly counteracted these effects. This study indicates that Gyp has a potential role in the treatment of RP.
Collapse
Affiliation(s)
- Reem Hasaballah Alhasani
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom; Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Xinzhi Zhou
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom
| | - Lincoln Biswas
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom
| | - Xing Li
- School of Basic Medical Sciences, Shaoyang University, Shaoyang, Hunan, 422000, PR China
| | - James Reilly
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom
| | - Zhihong Zeng
- College of Biological and Environmental Engineering, Changsha University, Changsha, Hunan, 410022, PR China.
| | - Xinhua Shu
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom; Department of Vision Science, Glasgow Caledonian University, Glasgow, G4 0BA, United Kingdom; School of Basic Medical Sciences, Shaoyang University, Shaoyang, Hunan, 422000, PR China.
| |
Collapse
|
14
|
The Genetic and Endoplasmic Reticulum-Mediated Molecular Mechanisms of Primary Open-Angle Glaucoma. Int J Mol Sci 2020; 21:ijms21114171. [PMID: 32545285 PMCID: PMC7312987 DOI: 10.3390/ijms21114171] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 12/14/2022] Open
Abstract
Glaucoma is a heterogenous, chronic, progressive group of eye diseases, which results in irreversible loss of vision. There are several types of glaucoma, whereas the primary open-angle glaucoma (POAG) constitutes the most common type of glaucoma, accounting for three-quarters of all glaucoma cases. The pathological mechanisms leading to POAG pathogenesis are multifactorial and still poorly understood, but it is commonly known that significantly elevated intraocular pressure (IOP) plays a crucial role in POAG pathogenesis. Besides, genetic predisposition and aggregation of abrogated proteins within the endoplasmic reticulum (ER) lumen and subsequent activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent unfolded protein response (UPR) signaling pathway may also constitute important factors for POAG pathogenesis at the molecular level. Glaucoma is commonly known as a ‘silent thief of sight’, as it remains asymptomatic until later stages, and thus its diagnosis is frequently delayed. Thereby, detailed knowledge about the glaucoma pathophysiology is necessary to develop both biochemical and genetic tests to improve its early diagnosis as well as develop a novel, ground-breaking treatment strategy, as currently used medical therapies against glaucoma are limited and may evoke numerous adverse side-effects in patients.
Collapse
|
15
|
Collin GB, Gogna N, Chang B, Damkham N, Pinkney J, Hyde LF, Stone L, Naggert JK, Nishina PM, Krebs MP. Mouse Models of Inherited Retinal Degeneration with Photoreceptor Cell Loss. Cells 2020; 9:cells9040931. [PMID: 32290105 PMCID: PMC7227028 DOI: 10.3390/cells9040931] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 12/12/2022] Open
Abstract
Inherited retinal degeneration (RD) leads to the impairment or loss of vision in millions of individuals worldwide, most frequently due to the loss of photoreceptor (PR) cells. Animal models, particularly the laboratory mouse, have been used to understand the pathogenic mechanisms that underlie PR cell loss and to explore therapies that may prevent, delay, or reverse RD. Here, we reviewed entries in the Mouse Genome Informatics and PubMed databases to compile a comprehensive list of monogenic mouse models in which PR cell loss is demonstrated. The progression of PR cell loss with postnatal age was documented in mutant alleles of genes grouped by biological function. As anticipated, a wide range in the onset and rate of cell loss was observed among the reported models. The analysis underscored relationships between RD genes and ciliary function, transcription-coupled DNA damage repair, and cellular chloride homeostasis. Comparing the mouse gene list to human RD genes identified in the RetNet database revealed that mouse models are available for 40% of the known human diseases, suggesting opportunities for future research. This work may provide insight into the molecular players and pathways through which PR degenerative disease occurs and may be useful for planning translational studies.
Collapse
Affiliation(s)
- Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Navdeep Gogna
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Bo Chang
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Nattaya Damkham
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
- Siriraj Center of Excellence for Stem Cell Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
| | - Jai Pinkney
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Lillian F. Hyde
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Lisa Stone
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Jürgen K. Naggert
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Correspondence: (P.M.N.); (M.P.K.); Tel.: +1-207-2886-383 (P.M.N.); +1-207-2886-000 (M.P.K.)
| | - Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, ME 04609, USA; (G.B.C.); (N.G.); (B.C.); (N.D.); (J.P.); (L.F.H.); (L.S.); (J.K.N.)
- Correspondence: (P.M.N.); (M.P.K.); Tel.: +1-207-2886-383 (P.M.N.); +1-207-2886-000 (M.P.K.)
| |
Collapse
|
16
|
Liang Q, Dharmat R, Owen L, Shakoor A, Li Y, Kim S, Vitale A, Kim I, Morgan D, Liang S, Wu N, Chen K, DeAngelis MM, Chen R. Single-nuclei RNA-seq on human retinal tissue provides improved transcriptome profiling. Nat Commun 2019; 10:5743. [PMID: 31848347 PMCID: PMC6917696 DOI: 10.1038/s41467-019-12917-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 10/02/2019] [Indexed: 12/23/2022] Open
Abstract
Single-cell RNA-seq is a powerful tool in decoding the heterogeneity in complex tissues by generating transcriptomic profiles of the individual cell. Here, we report a single-nuclei RNA-seq (snRNA-seq) transcriptomic study on human retinal tissue, which is composed of multiple cell types with distinct functions. Six samples from three healthy donors are profiled and high-quality RNA-seq data is obtained for 5873 single nuclei. All major retinal cell types are observed and marker genes for each cell type are identified. The gene expression of the macular and peripheral retina is compared to each other at cell-type level. Furthermore, our dataset shows an improved power for prioritizing genes associated with human retinal diseases compared to both mouse single-cell RNA-seq and human bulk RNA-seq results. In conclusion, we demonstrate that obtaining single cell transcriptomes from human frozen tissues can provide insight missed by either human bulk RNA-seq or animal models.
Collapse
Affiliation(s)
- Qingnan Liang
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, 77030, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Rachayata Dharmat
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, 77030, TX, USA
- St. Jude Children's Research Hospital, 262 Danny Thomas Pl, Memphis, TN, 38105, USA
| | - Leah Owen
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
| | - Akbar Shakoor
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
| | - Yumei Li
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Sangbae Kim
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Albert Vitale
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
| | - Ivana Kim
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
| | - Denise Morgan
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA
- Department of Pharmacotherapy, the College of Pharmacy, University of Utah, Salt Lake City, UT, 84132, USA
| | - Shaoheng Liang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Nathaniel Wu
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Ken Chen
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Margaret M DeAngelis
- Department of Ophthalmology and Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA.
- Department of Pharmacotherapy, the College of Pharmacy, University of Utah, Salt Lake City, UT, 84132, USA.
- Department of Population Health Sciences, University of Utah School of Medicine, Salt Lake City, UT, 84132, USA.
| | - Rui Chen
- HGSC, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, 77030, TX, USA.
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
| |
Collapse
|
17
|
Miyamichi D, Nishina S, Hosono K, Yokoi T, Kurata K, Sato M, Hotta Y, Azuma N. Retinal structure in Leber's congenital amaurosis caused by RPGRIP1 mutations. Hum Genome Var 2019; 6:32. [PMID: 31666973 PMCID: PMC6804879 DOI: 10.1038/s41439-019-0064-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/29/2019] [Accepted: 05/12/2019] [Indexed: 12/27/2022] Open
Abstract
This study aimed to evaluate retinal structure in the early stage of Leber’s congenital amaurosis (LCA) caused by RPGRIP1 mutations. Four patients from two families were included. Case 1 was a 13-year-old girl, cases 2 and 3 were 7-year-old monozygotic twin brothers of case 1, and case 4 was a 17-year-old boy. Comprehensive ophthalmic examinations were performed, including visual acuity measurements, perimetry, electroretinography (ERG), and optical coherence tomography (OCT). To identify potential pathogenic mutations, 74 genes known to cause retinitis pigmentosa or LCA were assessed using targeted next-generation sequencing. OCT showed photoreceptor outer nuclear layer (ONL) thinning in all patients. The lamellar structure was retained in all patients, whereas the ellipsoid zone was extinguished in cases 1, 2, and 3. In case 4, the ellipsoid zone was maintained at 9 years of age but became blurred at 17 years of age. In case 1, OCT indicated slight photoreceptor ONL thinning during the period between 7 and 11 years of age. Mutation analysis revealed RPGRIP1 mutations as the cause for autosomal recessive LCA in all patients. Photoreceptor ONL on OCT is relatively well preserved in the early stage of LCA caused by RPGRIP1 mutations. Researchers in Japan have characterized the early stages of the inherited retinal disease Leber’s congenital amaurosis (LCA), raising hope that gene therapy could help before the disease progresses too far. LCA results in early-onset blindness or severe visual impairment and has been linked with several genes, including RPGRIP1. Daisuke Miyamichi from Hamamatsu University School of Medicine, Japan, and coworkers conducted ophthalamic tests on four young patients with RPGRIP1 mutations. In all four cases, they found thinning of the photoreceptor outer nuclear layer, a layer of the retina. The outer nuclear layer progressively thinned in consecutive samples taken from the same patient at different ages, and was better retained in the younger patients. Taken together, these findings suggest that gene therapy to correct RPGRIP1 mutations could be effective if carried out in early childhood.
Collapse
Affiliation(s)
- Daisuke Miyamichi
- 1Department of Ophthalmology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Sachiko Nishina
- 2Department of Ophthalmology and Laboratory for Visual Science, National Center for Child Health and Development, Tokyo, Japan
| | - Katsuhiro Hosono
- 1Department of Ophthalmology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Tadashi Yokoi
- 2Department of Ophthalmology and Laboratory for Visual Science, National Center for Child Health and Development, Tokyo, Japan
| | - Kentaro Kurata
- 1Department of Ophthalmology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Miho Sato
- 1Department of Ophthalmology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Yoshihiro Hotta
- 1Department of Ophthalmology, Hamamatsu University School of Medicine, Shizuoka, Japan
| | - Noriyuki Azuma
- 2Department of Ophthalmology and Laboratory for Visual Science, National Center for Child Health and Development, Tokyo, Japan
| |
Collapse
|
18
|
Zhang X, Shahani U, Reilly J, Shu X. Disease mechanisms and neuroprotection by tauroursodeoxycholic acid in Rpgr knockout mice. J Cell Physiol 2019; 234:18801-18812. [PMID: 30924157 DOI: 10.1002/jcp.28519] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 02/22/2019] [Accepted: 03/06/2019] [Indexed: 12/16/2022]
Abstract
Mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene are the predominant cause of retinitis pigmentosa. RPGR plays a critical role as a scaffold protein in the regulation of protein trafficking from the basal body to the axoneme, where the cargoes are transported to the outer segments (OSs) of photoreceptors. This trafficking process is controlled directly by intraflagellar transport complexes and regulated by the RPGR protein complex, although the precise mechanisms have yet to be defined. We used an Rpgr conditional knockout (cko) mouse model to investigate the disease mechanisms during retinal degeneration and to evaluate the protective effects of tauroursodeoxycholic acid (TUDCA). Rhodopsin, cone opsins and transducin were mislocalized in Rpgr cko photoreceptors, while localization of NPHP4 to connecting cilia was absent, suggesting that RPGR is required for ciliary protein trafficking. Microglia were activated in advance of retinal degeneration in Rpgr cko mouse retinas. TUDCA treatment suppressed microglial activation and inflammation and prevented photoreceptor degeneration in Rpgr cko mice. Our data demonstrated that TUDCA has therapeutic potential for RPGR-associated RP patients.
Collapse
Affiliation(s)
- Xun Zhang
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, Scotland
| | - Uma Shahani
- Department of Vision Science, Glasgow Caledonian University, Glasgow, Scotland
| | - James Reilly
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, Scotland
| | - Xinhua Shu
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Glasgow, Scotland.,Department of Vision Science, Glasgow Caledonian University, Glasgow, Scotland
| |
Collapse
|
19
|
Baehr W, Hanke-Gogokhia C, Sharif A, Reed M, Dahl T, Frederick JM, Ying G. Insights into photoreceptor ciliogenesis revealed by animal models. Prog Retin Eye Res 2018; 71:26-56. [PMID: 30590118 DOI: 10.1016/j.preteyeres.2018.12.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/10/2018] [Accepted: 12/18/2018] [Indexed: 12/11/2022]
Abstract
Photoreceptors are polarized neurons, with very specific subcellular compartmentalization and unique requirements for protein expression and trafficking. Each photoreceptor contains an outer segment, the site of photon capture that initiates vision, an inner segment that houses the biosynthetic machinery and a synaptic terminal for signal transmission to downstream neurons. Outer segments and inner segments are connected by a connecting cilium (CC), the equivalent of a transition zone (TZ) of primary cilia. The connecting cilium is part of the basal body/axoneme backbone that stabilizes the outer segment. This report will update the reader on late developments in photoreceptor ciliogenesis and transition zone formation, specifically in mouse photoreceptors, focusing on early events in photoreceptor ciliogenesis. The connecting cilium, an elongated and narrow structure through which all outer segment proteins and membrane components must traffic, functions as a gate that controls access to the outer segment. Here we will review genes and their protein products essential for basal body maturation and for CC/TZ genesis, sorted by phenotype. Emphasis is given to naturally occurring mouse mutants and gene knockouts that interfere with CC/TZ formation and ciliogenesis.
Collapse
Affiliation(s)
- Wolfgang Baehr
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA.
| | - Christin Hanke-Gogokhia
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Ali Sharif
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Michelle Reed
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Tiffanie Dahl
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Jeanne M Frederick
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| | - Guoxin Ying
- Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences, Salt Lake City, UT, 84132, USA
| |
Collapse
|
20
|
Wiegering A, Rüther U, Gerhardt C. The ciliary protein Rpgrip1l in development and disease. Dev Biol 2018; 442:60-68. [DOI: 10.1016/j.ydbio.2018.07.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/13/2018] [Accepted: 07/28/2018] [Indexed: 12/28/2022]
|
21
|
Patnaik SR, Zhang X, Biswas L, Akhtar S, Zhou X, Kusuluri DK, Reilly J, May-Simera H, Chalmers S, McCarron JG, Shu X. RPGR protein complex regulates proteasome activity and mediates store-operated calcium entry. Oncotarget 2018; 9:23183-23197. [PMID: 29796181 PMCID: PMC5955404 DOI: 10.18632/oncotarget.25259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 04/07/2018] [Indexed: 11/25/2022] Open
Abstract
Ciliopathies are a group of genetically heterogeneous disorders, characterized by defects in cilia genesis or maintenance. Mutations in the RPGR gene and its interacting partners, RPGRIP1 and RPGRIP1L, cause ciliopathies, but the function of their proteins remains unclear. Here we show that knockdown (KD) of RPGR, RPGRIP1 or RPGRIP1L in hTERT-RPE1 cells results in abnormal actin cytoskeleton organization. The actin cytoskeleton rearrangement is regulated by the small GTPase RhoA via the planar cell polarity (PCP) pathway. RhoA activity was upregulated in the absence of RPGR, RPGRIP1 or RPGRIP1L proteins. In RPGR, RPGRIP1 or RPGRIP1L KD cells, we observed increased levels of DVl2 and DVl3 proteins, the core components of the PCP pathway, due to impaired proteasomal activity. RPGR, RPGRIP1 or RPGRIP1L KD cells treated with thapsigargin (TG), an inhibitor of sarcoendoplasmic reticulum Ca2+- ATPases, showed impaired store-operated Ca2+ entry (SOCE), which is mediated by STIM1 and Orai1 proteins. STIM1 was not localized to the ER-PM junction upon ER store depletion in RPGR, RPGRIP1 or RPGRIP1L KD cells. Our results demonstrate that the RPGR protein complex is required for regulating proteasomal activity and for modulating SOCE, which may contribute to the ciliopathy phenotype.
Collapse
Affiliation(s)
- Sarita Rani Patnaik
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
- Institute of Molecular Physiology, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany
| | - Xun Zhang
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
| | - Lincoln Biswas
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
| | - Saeed Akhtar
- Cornea Research Chair, Department of Optometry, King Saud University, Riyadh 11433, Kingdom of Saudi Arabia
| | - Xinzhi Zhou
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
| | - Deva Krupakar Kusuluri
- Institute of Molecular Physiology, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany
| | - James Reilly
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
| | - Helen May-Simera
- Institute of Molecular Physiology, Johannes Gutenberg-Universität Mainz, D-55128 Mainz, Germany
| | - Susan Chalmers
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, Scotland
| | - John G. McCarron
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, Scotland
| | - Xinhua Shu
- Department of Life Sciences, Glasgow Caledonian University, Glasgow G4 0BA, Scotland
| |
Collapse
|
22
|
The Role of the Microglial Cx3cr1 Pathway in the Postnatal Maturation of Retinal Photoreceptors. J Neurosci 2018; 38:4708-4723. [PMID: 29669747 DOI: 10.1523/jneurosci.2368-17.2018] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 03/22/2018] [Accepted: 04/10/2018] [Indexed: 11/21/2022] Open
Abstract
Microglia are the resident immune cells of the CNS, and their response to infection, injury and disease is well documented. More recently, microglia have been shown to play a role in normal CNS development, with the fractalkine-Cx3cr1 signaling pathway of particular importance. This work describes the interaction between the light-sensitive photoreceptors and microglia during eye opening, a time of postnatal photoreceptor maturation. Genetic removal of Cx3cr1 (Cx3cr1GFP/GFP ) led to an early retinal dysfunction soon after eye opening [postnatal day 17 (P17)] and cone photoreceptor loss (P30 onward) in mice of either sex. This dysfunction occurred at a time when fractalkine expression was predominantly outer retinal, when there was an increased microglial presence near the photoreceptor layer and increased microglial-cone photoreceptor contacts. Photoreceptor maturation and outer segment elongation was coincident with increased opsin photopigment expression in wild-type retina, while this was aberrant in the Cx3cr1GFP/GFP retina and outer segment length was reduced. A beadchip array highlighted Cx3cr1 regulation of genes involved in the photoreceptor cilium, a key structure that is important for outer segment elongation. This was confirmed with quantitative PCR with specific cilium-related genes, Rpgr and Rpgrip1, downregulated at eye opening (P14). While the overall cilium structure was unaffected, expression of Rpgr, Rpgrip1, and centrin were restricted to more proximal regions of the transitional zone. This study highlighted a novel role for microglia in postnatal neuronal development within the retina, with loss of fractalkine-Cx3cr1 signaling leading to an altered distribution of cilium proteins, failure of outer segment elongation and ultimately cone photoreceptor loss.SIGNIFICANCE STATEMENT Microglia are involved in CNS development and disease. This work highlights the role of microglia in postnatal development of the light-detecting photoreceptor neurons within the mouse retina. Loss of the microglial Cx3cr1 signaling pathway resulted in specific alterations in the cilium, a key structure in photoreceptor outer segment elongation. The distribution of key components of the cilium transitional zone, Rpgr, Rpgrip1, and centrin, were altered in retinae lacking Cx3cr1 with reduced outer segment length and cone photoreceptor death observed at later postnatal ages. This work identifies a novel role for microglia in the postnatal maturation of retinal photoreceptors.
Collapse
|
23
|
Wiegering A, Dildrop R, Kalfhues L, Spychala A, Kuschel S, Lier JM, Zobel T, Dahmen S, Leu T, Struchtrup A, Legendre F, Vesque C, Schneider-Maunoury S, Saunier S, Rüther U, Gerhardt C. Cell type-specific regulation of ciliary transition zone assembly in vertebrates. EMBO J 2018; 37:embj.201797791. [PMID: 29650680 PMCID: PMC5978567 DOI: 10.15252/embj.201797791] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 03/12/2018] [Accepted: 03/15/2018] [Indexed: 01/07/2023] Open
Abstract
Ciliopathies are life-threatening human diseases caused by defective cilia. They can often be traced back to mutations of genes encoding transition zone (TZ) proteins demonstrating that the understanding of TZ organisation is of paramount importance. The TZ consists of multimeric protein modules that are subject to a stringent assembly hierarchy. Previous reports place Rpgrip1l at the top of the TZ assembly hierarchy in Caenorhabditis elegans By performing quantitative immunofluorescence studies in RPGRIP1L-/- mouse embryos and human embryonic cells, we recognise a different situation in vertebrates in which Rpgrip1l deficiency affects TZ assembly in a cell type-specific manner. In cell types in which the loss of Rpgrip1l alone does not affect all modules, additional truncation or removal of vertebrate-specific Rpgrip1 results in an impairment of all modules. Consequently, Rpgrip1l and Rpgrip1 synergistically ensure the TZ composition in several vertebrate cell types, revealing a higher complexity of TZ assembly in vertebrates than in invertebrates.
Collapse
Affiliation(s)
- Antonia Wiegering
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Renate Dildrop
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Lisa Kalfhues
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - André Spychala
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Stefanie Kuschel
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Johanna Maria Lier
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Thomas Zobel
- Center for Advanced Imaging (CAi), Heinrich Heine University, Düsseldorf, Germany
| | - Stefanie Dahmen
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Tristan Leu
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Andreas Struchtrup
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Flora Legendre
- INSERM, U983, Hôpital Necker-Enfants Malades, Paris, France.,Sorbonne Paris Cité, Faculté de Médecine, Université Paris-Descartes, Paris, France
| | - Christine Vesque
- Paris-Seine (IBPS) - Developmental Biology Laboratory, Institut de Biologie, CNRS, UMR7622, INSERM U1156, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, Paris, France
| | - Sylvie Schneider-Maunoury
- Paris-Seine (IBPS) - Developmental Biology Laboratory, Institut de Biologie, CNRS, UMR7622, INSERM U1156, Paris, France.,Sorbonne Universités, UPMC Univ Paris 06, Paris, France
| | - Sophie Saunier
- INSERM, U983, Hôpital Necker-Enfants Malades, Paris, France.,Sorbonne Paris Cité, Faculté de Médecine, Université Paris-Descartes, Paris, France
| | - Ulrich Rüther
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| | - Christoph Gerhardt
- Institute for Animal Developmental and Molecular Biology, Heinrich Heine University, Düsseldorf, Germany
| |
Collapse
|
24
|
Petit L, Ma S, Cheng SY, Gao G, Punzo C. Rod Outer Segment Development Influences AAV-Mediated Photoreceptor Transduction After Subretinal Injection. Hum Gene Ther 2018; 28:464-481. [PMID: 28510482 PMCID: PMC5488363 DOI: 10.1089/hum.2017.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Vectors based on the adeno-associated virus (AAV) are currently the preferred tools for delivering genes to photoreceptors (PR) in small and large animals. AAVs have been applied successfully in various models of PR dystrophies. However, unknown barriers still limit AAV's efficient application in several forms of severe PR degenerations due to insufficient transgene expression and/or treated cells at the time of injection. Optimizations of PR gene therapy strategies will likely benefit from the identification of the cellular factors that influence PR transduction. Interestingly, recent studies have shown that the AAV transduction profile of PRs differs significantly between neonatal and adult mouse retinas after subretinal injection. This phenomenon may provide clues to identify host factors that influence the efficiency of AAV-mediated PR transduction. This study demonstrates that rod outer segments are critical modulators of efficient AAV-mediated rod transduction. During retinal development, rod transduction correlated temporally and spatially with the differentiation order of PRs when vectors were introduced subretinally but not when introduced intravitreally. All subretinally injected vectors had an initial preference to transduce cones in the absence of formed rod outer segments and then displayed a preference for rods as the cells matured, independently of the expression cassette or AAV serotype. Consistent with this observation, altered development of rod outer segments was associated with a strong reduction of rod transduction and an increase in the percentage of transduced cones by 2- to 2.8-fold. A similar increase of cone transduction was observed in the adult retinal degeneration 1 (rd1) retina compared to wild-type mice. These results suggest that the loss of rod outer segments in diseased retinas could markedly affect gene transfer efficiency of AAV vectors by limiting the ability of AAVs to infect dying rods efficiently. This information could be exploited for the development of more efficient AAV-based PR gene delivery procedures.
Collapse
Affiliation(s)
- Lolita Petit
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Shan Ma
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Shun-Yun Cheng
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Guangping Gao
- 3 Department of Microbiology and Physiological Systems and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Claudio Punzo
- 1 Department of Ophthalmology and Gene Therapy Center, University of Massachusetts Medical School , Worcester, Massachusetts.,2 Department of Neurobiology, University of Massachusetts Medical School , Worcester, Massachusetts
| |
Collapse
|
25
|
Martinez-Fernandez De La Camara C, Nanda A, Salvetti AP, Fischer MD, MacLaren RE. Gene therapy for the treatment of X-linked retinitis pigmentosa. Expert Opin Orphan Drugs 2018; 6:167-177. [PMID: 30057863 PMCID: PMC6059358 DOI: 10.1080/21678707.2018.1444476] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
INTRODUCTION X-linked retinitis pigmentosa caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene is the most common form of recessive RP. The phenotype is characterised by its severity and rapid disease progression. Gene therapy using adeno-associated viral vectors is currently the most promising therapeutic approach. However, the construction of a stable vector encoding the full-length RPGR transcript has previously proven to be a limiting step towards gene therapy clinical trials. Recently however, a codon optimised version of RPGR has been shown to increase the stability and fidelity of the sequence, conferring a therapeutic effect in murine and canine animal models. AREAS COVERED This manuscript reviews the natural history of X-linked retinitis pigmentosa and the research performed from the discovery of the causative gene, RPGR, to the preclinical testing of potential therapies that have led to the initiation of three clinical trials. EXPERT OPINION X-linked retinitis pigmentosa is an amenable disease to be treated by gene therapy. Codon optimisation has overcome the challenge of designing an RPGR vector without mutations, and with a therapeutic effect in different animal models. With the RPGR gene therapy clinical trials still in the early stages, the confirmation of the safety, tolerability and potency of the therapy is still ongoing.
Collapse
Affiliation(s)
| | - Anika Nanda
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Oxford, UK
| | - Anna Paola Salvetti
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
- Department of Biomedical and Clinical Sciences “Luigi Sacco”, Sacco Hospital, University of Milan, Milano, Italy
| | - M. Dominik Fischer
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
- Centre for Ophthalmology Tübingen, University Eye Hospital, Tübingen, Germany
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Department of Clinical Neurosciences, John Radcliffe Hospital, Oxford, UK
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, John Radcliffe Hospital, Oxford, UK
| |
Collapse
|
26
|
Rpgrip1 is required for rod outer segment development and ciliary protein trafficking in zebrafish. Sci Rep 2017; 7:16881. [PMID: 29203866 PMCID: PMC5715152 DOI: 10.1038/s41598-017-12838-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 09/14/2017] [Indexed: 12/23/2022] Open
Abstract
Mutations in the RPGR-interacting protein 1 (RPGRIP1) gene cause recessive Leber congenital amaurosis (LCA), juvenile retinitis pigmentosa (RP) and cone-rod dystrophy. RPGRIP1 interacts with other retinal disease-causing proteins and has been proposed to have a role in ciliary protein transport; however, its function remains elusive. Here, we describe a new zebrafish model carrying a nonsense mutation in the rpgrip1 gene. Rpgrip1homozygous mutants do not form rod outer segments and display mislocalization of rhodopsin, suggesting a role for RPGRIP1 in rhodopsin-bearing vesicle trafficking. Furthermore, Rab8, the key regulator of rhodopsin ciliary trafficking, was mislocalized in photoreceptor cells of rpgrip1 mutants. The degeneration of rod cells is early onset, followed by the death of cone cells. These phenotypes are similar to that observed in LCA and juvenile RP patients. Our data indicate RPGRIP1 is necessary for rod outer segment development through regulating ciliary protein trafficking. The rpgrip1 mutant zebrafish may provide a platform for developing therapeutic treatments for RP patients.
Collapse
|
27
|
Seo S, Datta P. Photoreceptor outer segment as a sink for membrane proteins: hypothesis and implications in retinal ciliopathies. Hum Mol Genet 2017; 26:R75-R82. [PMID: 28453661 DOI: 10.1093/hmg/ddx163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
The photoreceptor outer segment (OS) is a unique modification of the primary cilium, specialized for light perception. Being homologous organelles, the primary cilium and the OS share common building blocks and molecular machinery to construct and maintain them. The OS, however, has several unique structural features that are not seen in primary cilia. Although these unique features of the OS have been well documented, their implications in protein localization have been under-appreciated. In this review, we compare the structural properties of the primary cilium and the OS, and propose a hypothesis that the OS can act as a sink for membrane proteins. We further discuss the implications of this hypothesis in polarized protein localization in photoreceptors and mechanisms of photoreceptor degeneration in retinal ciliopathies.
Collapse
Affiliation(s)
- Seongjin Seo
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Poppy Datta
- Department of Ophthalmology and Visual Sciences, Wynn Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| |
Collapse
|
28
|
Krebs MP, Collin GB, Hicks WL, Yu M, Charette JR, Shi LY, Wang J, Naggert JK, Peachey NS, Nishina PM. Mouse models of human ocular disease for translational research. PLoS One 2017; 12:e0183837. [PMID: 28859131 PMCID: PMC5578669 DOI: 10.1371/journal.pone.0183837] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/12/2017] [Indexed: 01/24/2023] Open
Abstract
Mouse models provide a valuable tool for exploring pathogenic mechanisms underlying inherited human disease. Here, we describe seven mouse models identified through the Translational Vision Research Models (TVRM) program, each carrying a new allele of a gene previously linked to retinal developmental and/or degenerative disease. The mutations include four alleles of three genes linked to human nonsyndromic ocular diseases (Aipl1tvrm119, Aipl1tvrm127, Rpgrip1tvrm111, RhoTvrm334) and three alleles of genes associated with human syndromic diseases that exhibit ocular phentoypes (Alms1tvrm102, Clcn2nmf289, Fkrptvrm53). Phenotypic characterization of each model is provided in the context of existing literature, in some cases refining our current understanding of specific disease attributes. These murine models, on fixed genetic backgrounds, are available for distribution upon request and may be useful for understanding the function of the gene in the retina, the pathological mechanisms induced by its disruption, and for testing experimental approaches to treat the corresponding human ocular diseases.
Collapse
Affiliation(s)
- Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wanda L. Hicks
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Lan Ying Shi
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| |
Collapse
|
29
|
Gonçalves J, Pelletier L. The Ciliary Transition Zone: Finding the Pieces and Assembling the Gate. Mol Cells 2017; 40:243-253. [PMID: 28401750 PMCID: PMC5424270 DOI: 10.14348/molcells.2017.0054] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/05/2017] [Indexed: 12/23/2022] Open
Abstract
Eukaryotic cilia are organelles that project from the surface of cells to fulfill motility and sensory functions. In vertebrates, the functions of both motile and immotile cilia are critical for embryonic development and adult tissue homeostasis. Importantly, a multitude of human diseases is caused by abnormal cilia biogenesis and functions which rely on the compartmentalization of the cilium and the maintenance of its protein composition. The transition zone (TZ) is a specialized ciliary domain present at the base of the cilium and is part of a gate that controls protein entry and exit from this organelle. The relevance of the TZ is highlighted by the fact that several of its components are coded by ciliopathy genes. Here we review recent developments in the study of TZ proteomes, the mapping of individual components to the TZ structure and the establishment of the TZ as a lipid gate.
Collapse
Affiliation(s)
- João Gonçalves
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5,
Canada
| | - Laurence Pelletier
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, 600 University Avenue, Toronto, ON M5G 1X5,
Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8,
Canada
| |
Collapse
|
30
|
Broadgate S, Yu J, Downes SM, Halford S. Unravelling the genetics of inherited retinal dystrophies: Past, present and future. Prog Retin Eye Res 2017; 59:53-96. [PMID: 28363849 DOI: 10.1016/j.preteyeres.2017.03.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 02/07/2023]
Abstract
The identification of the genes underlying monogenic diseases has been of interest to clinicians and scientists for many years. Using inherited retinal dystrophies as an example of monogenic disease we describe the history of molecular genetic techniques that have been pivotal in the discovery of disease causing genes. The methods that were developed in the 1970's and 80's are still in use today but have been refined and improved. These techniques enabled the concept of the Human Genome Project to be envisaged and ultimately realised. When the successful conclusion of the project was announced in 2003 many new tools and, as importantly, many collaborations had been developed that facilitated a rapid identification of disease genes. In the post-human genome project era advances in computing power and the clever use of the properties of DNA replication has allowed the development of next-generation sequencing technologies. These methods have revolutionised the identification of disease genes because for the first time there is no need to define the position of the gene in the genome. The use of next generation sequencing in a diagnostic setting has allowed many more patients with an inherited retinal dystrophy to obtain a molecular diagnosis for their disease. The identification of novel genes that have a role in the development or maintenance of retinal function is opening up avenues of research which will lead to the development of new pharmacological and gene therapy approaches. Neither of which can be used unless the defective gene and protein is known. The continued development of sequencing technologies also holds great promise for the advent of truly personalised medicine.
Collapse
Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
| |
Collapse
|
31
|
Soens ZT, Li Y, Zhao L, Eblimit A, Dharmat R, Li Y, Chen Y, Naqeeb M, Fajardo N, Lopez I, Sun Z, Koenekoop RK, Chen R. Hypomorphic mutations identified in the candidate Leber congenital amaurosis gene CLUAP1. Genet Med 2016; 18:1044-51. [PMID: 26820066 PMCID: PMC4965339 DOI: 10.1038/gim.2015.205] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/04/2015] [Indexed: 12/11/2022] Open
Abstract
PURPOSE Leber congenital amaurosis (LCA) is an early-onset form of retinal degeneration. Six of the 22 known LCA genes encode photoreceptor ciliary proteins. Despite the identification of 22 LCA genes, the genetic basis of ~30% of LCA patients remains unknown. We sought to investigate the cause of disease in the remaining 30% by examining cilia-associated genes. METHODS Whole-exome sequencing was performed on an LCA cohort of 212 unsolved probands previously screened for mutations in known retinal-disease genes. Immunohistochemistry using mouse retinas was used to confirm protein localization and zebrafish were used to perform rescue experiments. RESULTS A homozygous nonsynonymous mutation was found in a single proband in CLUAP1, a gene required for ciliogenesis and cilia maintenance. Cluap1 knockout zebrafish exhibit photoreceptor cell death as early as 5 days after fertilization, and rescue experiments revealed that our proband's mutation is significantly hypomorphic. CONCLUSION Consistent with the knowledge that CLUAP1 plays an important role in cilia function and that cilia are critical to photoreceptor function, our results indicate that hypomorphic mutations in CLUAP1 can result in dysfunctional photoreceptors without systemic abnormalities. This is the first report linking mutations in CLUAP1 to human disease and establishes CLUAP1 as a candidate LCA gene.Genet Med 18 10, 1044-1051.
Collapse
Affiliation(s)
- Zachry T. Soens
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
| | - Yuanyuan Li
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, United States
| | - Li Zhao
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
- Department of Structural and Computational Biology & Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, United States
| | - Aiden Eblimit
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
| | - Rachayata Dharmat
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
| | - Yumei Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
| | - Yiyun Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
| | - Mohammed Naqeeb
- Department of Ophthalmology, Um Al Qura University Medical School, Makkah, Saudi Arabia
| | - Norma Fajardo
- McGill Ocular Genetics Laboratory and Centre, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, QC H3H 1P3, Canada
| | - Irma Lopez
- McGill Ocular Genetics Laboratory and Centre, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, QC H3H 1P3, Canada
| | - Zhaoxia Sun
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, United States
| | - Robert K. Koenekoop
- McGill Ocular Genetics Laboratory and Centre, Departments of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, QC H3H 1P3, Canada
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, United States
- Department of Structural and Computational Biology & Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, United States
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
- Program of Developmental Biology, Baylor College of Medicine, Houston, TX 77030, United States
| |
Collapse
|
32
|
Greenwald SH, Charette JR, Staniszewska M, Shi LY, Brown SDM, Stone L, Liu Q, Hicks WL, Collin GB, Bowl MR, Krebs MP, Nishina PM, Pierce EA. Mouse Models of NMNAT1-Leber Congenital Amaurosis (LCA9) Recapitulate Key Features of the Human Disease. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:1925-1938. [PMID: 27207593 DOI: 10.1016/j.ajpath.2016.03.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/08/2016] [Accepted: 03/16/2016] [Indexed: 12/20/2022]
Abstract
The nicotinamide nucleotide adenylyltransferase 1 (NMNAT1) enzyme is essential for regenerating the nuclear pool of NAD(+) in all nucleated cells in the body, and mounting evidence also suggests that it has a separate role in neuroprotection. Recently, mutations in the NMNAT1 gene were associated with Leber congenital amaurosis, a severe retinal degenerative disease that causes blindness during infancy. Availability of a reliable mammalian model of NMNAT1-Leber congenital amaurosis would assist in determining the mechanisms through which disruptions in NMNAT1 lead to retinal cell degeneration and would provide a resource for testing treatment options. To this end, we identified two separate N-ethyl-N-nitrosourea-generated mouse lines that harbor either a p.V9M or a p.D243G mutation. Both mouse models recapitulate key aspects of the human disease and confirm the pathogenicity of mutant NMNAT1. Homozygous Nmnat1 mutant mice develop a rapidly progressing chorioretinal disease that begins with photoreceptor degeneration and includes attenuation of the retinal vasculature, optic atrophy, and retinal pigment epithelium loss. Retinal function deteriorates in both mouse lines, and, in the more rapidly progressing homozygous Nmnat1(V9M) mutant mice, the electroretinogram becomes undetectable and the pupillary light response weakens. These mouse models offer an opportunity for investigating the cellular mechanisms underlying disease pathogenesis, evaluating potential therapies for NMNAT1-Leber congenital amaurosis, and conducting in situ studies on NMNAT1 function and NAD(+) metabolism.
Collapse
Affiliation(s)
- Scott H Greenwald
- Ocular Genomics Institute, Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts
| | | | - Magdalena Staniszewska
- Ocular Genomics Institute, Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts
| | | | - Steve D M Brown
- Mammalian Genetics Unit, Medical Research Council (MRC), Harwell Campus, Oxfordshire, United Kingdom
| | - Lisa Stone
- The Jackson Laboratory, Bar Harbor, Maine
| | - Qin Liu
- Ocular Genomics Institute, Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts
| | | | | | - Michael R Bowl
- Mammalian Genetics Unit, Medical Research Council (MRC), Harwell Campus, Oxfordshire, United Kingdom
| | | | | | - Eric A Pierce
- Ocular Genomics Institute, Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Harvard Medical School, Boston, Massachusetts.
| |
Collapse
|
33
|
Kooragayala K, Gotoh N, Cogliati T, Nellissery J, Kaden TR, French S, Balaban R, Li W, Covian R, Swaroop A. Quantification of Oxygen Consumption in Retina Ex Vivo Demonstrates Limited Reserve Capacity of Photoreceptor Mitochondria. Invest Ophthalmol Vis Sci 2016; 56:8428-36. [PMID: 26747773 DOI: 10.1167/iovs.15-17901] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Cell death in neurodegeneration occurs at the convergence of diverse metabolic pathways. In the retina, a common underlying mechanism involves mitochondrial dysfunction since photoreceptor homeostasis and survival are highly susceptible to altered aerobic energy metabolism. We sought to develop an assay to directly measure oxygen consumption in intact retina with the goal of identifying alterations in respiration during photoreceptor dysfunction and degeneration. METHODS Circular punches of freshly isolated mouse retina, adjacent to the optic nerve head, were used in the microplate-based Seahorse Extracellular Flux Analyzer to measure oxygen consumption. Tissue integrity was evaluated by propidium iodide staining and live imaging. Different substrates were tested for mitochondrial respiration. Basal and maximal respiration were expressed as oxygen consumption rate (OCR) and respectively measured in Ames' medium before and after the addition of mitochondrial uncoupler, BAM15. RESULTS We show that glucose is an essential substrate for retinal mitochondria. At baseline, mitochondria respiration in the intact wild-type retina was close to maximal, with limited reserve capacity. Similar OCR and limited mitochondrial reserve capacity was also observed in cone-only Nrl-/- retina. However, the retina of Pde6brd1/rd1, Cep290rd16/rd16 and Rpgrip1-/- mice, all with dysfunctional or no photoreceptors, had reduced OCR and higher mitochondrial reserve capacity. CONCLUSIONS We have optimized a method to directly measure oxygen consumption in acutely isolated, ex vivo mouse retina and demonstrate that photoreceptors have low mitochondrial reserve capacity. Our data provide a plausible explanation for the high vulnerability of photoreceptors to altered energy homeostasis caused by mutations or metabolic challenges.
Collapse
Affiliation(s)
- Keshav Kooragayala
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Norimoto Gotoh
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Tiziana Cogliati
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Jacob Nellissery
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Talia R Kaden
- Retinal Neurobiology Section, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Stephanie French
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Robert Balaban
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Wei Li
- Retinal Neurobiology Section, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Raul Covian
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States
| |
Collapse
|
34
|
Bales KL, Gross AK. Aberrant protein trafficking in retinal degenerations: The initial phase of retinal remodeling. Exp Eye Res 2015; 150:71-80. [PMID: 26632497 DOI: 10.1016/j.exer.2015.11.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/04/2015] [Accepted: 11/09/2015] [Indexed: 12/18/2022]
Abstract
Retinal trafficking proteins are involved in molecular assemblies that govern protein transport, orchestrate cellular events involved in cilia formation, regulate signal transduction, autophagy and endocytic trafficking, all of which if not properly controlled initiate retinal degeneration. Improper function and or trafficking of these proteins and molecular networks they are involved in cause a detrimental cascade of neural retinal remodeling due to cell death, resulting as devastating blinding diseases. A universal finding in retinal degenerative diseases is the profound detection of retinal remodeling, occurring as a phased modification of neural retinal function and structure, which begins at the molecular level. Retinal remodeling instigated by aberrant trafficking of proteins encompasses many forms of retinal degenerations, such as the diverse forms of retinitis pigmentosa (RP) and disorders that resemble RP through mutations in the rhodopsin gene, retinal ciliopathies, and some forms of glaucoma and age-related macular degeneration (AMD). As a large majority of genes associated with these different retinopathies are overlapping, it is imperative to understand their underlying molecular mechanisms. This review will discuss some of the most recent discoveries in vertebrate retinal remodeling and retinal degenerations caused by protein mistrafficking.
Collapse
Affiliation(s)
- Katie L Bales
- University of Alabama at Birmingham, Birmingham, AL, United States
| | - Alecia K Gross
- University of Alabama at Birmingham, Birmingham, AL, United States.
| |
Collapse
|
35
|
Megaw RD, Soares DC, Wright AF. RPGR: Its role in photoreceptor physiology, human disease, and future therapies. Exp Eye Res 2015; 138:32-41. [PMID: 26093275 PMCID: PMC4553903 DOI: 10.1016/j.exer.2015.06.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 12/21/2022]
Abstract
Mammalian photoreceptors contain specialised connecting cilia that connect the inner (IS) to the outer segments (OS). Dysfunction of the connecting cilia due to mutations in ciliary proteins are a common cause of the inherited retinal dystrophy retinitis pigmentosa (RP). Mutations affecting the Retinitis Pigmentosa GTPase Regulator (RPGR) protein is one such cause, affecting 10-20% of all people with RP and the majority of those with X-linked RP. RPGR is located in photoreceptor connecting cilia. It interacts with a wide variety of ciliary proteins, but its exact function is unknown. Recently, there have been important advances both in our understanding of RPGR function and towards the development of a therapy. This review summarises the existing literature on human RPGR function and dysfunction, and suggests that RPGR plays a role in the function of the ciliary gate, which controls access of both membrane and soluble proteins to the photoreceptor outer segment. We discuss key models used to investigate and treat RPGR disease and suggest that gene augmentation therapy offers a realistic therapeutic approach, although important questions still remain to be answered, while cell replacement therapy based on retinal progenitor cells represents a more distant prospect.
Collapse
Affiliation(s)
- Roly D Megaw
- Scottish Centre for Regenerative Medicine, University of Edinburgh, 5 Little France Drive, Edinburgh EH16 4UU, United Kingdom.
| | - Dinesh C Soares
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom.
| | - Alan F Wright
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom.
| |
Collapse
|
36
|
The Role of RPGR and Its Interacting Proteins in Ciliopathies. J Ophthalmol 2015; 2015:414781. [PMID: 26124960 PMCID: PMC4466403 DOI: 10.1155/2015/414781] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 04/13/2015] [Accepted: 04/19/2015] [Indexed: 11/28/2022] Open
Abstract
Ciliopathies encompass a group of genetic disorders characterized by defects in the formation, maintenance, or function of cilia. Retinitis pigmentosa (RP) is frequently one of the clinical features presented in diverse ciliopathies. RP is a heterogeneous group of inherited retinal disorders, characterized by the death of photoreceptors and affecting more than one million individuals worldwide. The retinitis pigmentosa GTPase regulator (RPGR) gene is mutated in up to 20% of all RP patients. RPGR protein has different interacting partners to function in ciliary protein trafficking. In this review, we specifically focus on RPGR and its two interacting proteins: RPGRIP1 and RPGRIP1L. We summarize the function of the three proteins and highlight recent studies that provide insight into the cellular function of those proteins.
Collapse
|
37
|
Li T. Leber congenital amaurosis caused by mutations in RPGRIP1. Cold Spring Harb Perspect Med 2014; 5:cshperspect.a017384. [PMID: 25414380 DOI: 10.1101/cshperspect.a017384] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Recessive null mutations in retinitis pigmentosa GTPase regulator interacting protein 1 (RPGRIP1) gene are the cause of LCA6 and account for 5% to 6% of the total patient population. RPGRIP1 has an essential role in the photoreceptor connecting cilia, and photoreceptors lacking RPGRIP1 are unable to maintain the light sensing outer segments. As a result, patients lose retinal functions at an early age but retain photoreceptors in the central retina well into adulthood thus holding out the prospect for gene augmentation therapies. Laboratory studies in animal models have demonstrated efficacy of gene therapy in slowing disease progression. With further refinement in the design of the replacement gene construct, clinical trials for Leber congenital amaurosis (LCA) caused by RPGRIP1 mutations could be in the offing in the near future.
Collapse
Affiliation(s)
- Tiansen Li
- Retinal Cell Biology and Degeneration Section, Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, Bethesda, Maryland 20892
| |
Collapse
|
38
|
Vogel P, Gelfman CM, Issa T, Payne BJ, Hansen GM, Read RW, Jones C, Pitcher MR, Ding ZM, DaCosta CM, Shadoan MK, Vance RB, Powell DR. Nephronophthisis and retinal degeneration in tmem218-/- mice: a novel mouse model for Senior-Løken syndrome? Vet Pathol 2014; 52:580-95. [PMID: 25161209 DOI: 10.1177/0300985814547392] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mice deficient in TMEM218 (Tmem218(-/-) ) were generated as part of an effort to identify and validate pharmaceutically tractable targets for drug development through large-scale phenotypic screening of knockout mice. Routine diagnostics, expression analysis, histopathology, and electroretinogram analyses completed on Tmem218(-/-) mice identified a previously unknown role for TMEM218 in the development and function of the kidney and eye. The major observed phenotypes in Tmem218(-/-) mice were progressive cystic kidney disease and retinal degeneration. The renal lesions were characterized by diffuse renal cyst development with tubulointerstitial nephropathy and disruption of tubular basement membranes in essentially normal-sized kidneys. The retinal lesions were characterized by slow-onset loss of photoreceptors, which resulted in reduced electroretinogram responses. These renal and retinal lesions are most similar to those associated with nephronophthisis (NPHP) and retinitis pigmentosa in humans. At least 10% of NPHP cases present with extrarenal conditions, which most often include retinal degeneration. Senior-Løken syndrome is characterized by the concurrent development of autosomal recessive NPHP and retinitis pigmentosa. Since mutations in the known NPHP genes collectively account for only about 30% of NPHP cases, it is possible that TMEM218 could be involved in the development of similar ciliopathies in humans. In reviewing all other reported mouse models of NPHP, we suggest that Tmem218(-/-) mice could provide a useful model for elucidating the pathogenesis of cilia-associated disease in both the kidney and the retina, as well as in developing and testing novel therapeutic strategies for Senior-Løken syndrome.
Collapse
Affiliation(s)
- P Vogel
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C M Gelfman
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - T Issa
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - B J Payne
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - G M Hansen
- Department of Molecular Genetics, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - R W Read
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C Jones
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - M R Pitcher
- Department of Ophthalmology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - Z-M Ding
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - C M DaCosta
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - M K Shadoan
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - R B Vance
- Department of Pathology, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| | - D R Powell
- Department of Metabolism, Lexicon Pharmaceuticals Inc., The Woodlands, TX, USA
| |
Collapse
|
39
|
Roosing S, Thiadens AAHJ, Hoyng CB, Klaver CCW, den Hollander AI, Cremers FPM. Causes and consequences of inherited cone disorders. Prog Retin Eye Res 2014; 42:1-26. [PMID: 24857951 DOI: 10.1016/j.preteyeres.2014.05.001] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/29/2014] [Accepted: 05/06/2014] [Indexed: 11/18/2022]
Abstract
Hereditary cone disorders (CDs) are characterized by defects of the cone photoreceptors or retinal pigment epithelium underlying the macula, and include achromatopsia (ACHM), cone dystrophy (COD), cone-rod dystrophy (CRD), color vision impairment, Stargardt disease (STGD) and other maculopathies. Forty-two genes have been implicated in non-syndromic inherited CDs. Mutations in the 5 genes implicated in ACHM explain ∼93% of the cases. On the contrary, only 21% of CRDs (17 genes) and 25% of CODs (8 genes) have been elucidated. The fact that the large majority of COD and CRD-associated genes are yet to be discovered hints towards the existence of unknown cone-specific or cone-sensitive processes. The ACHM-associated genes encode proteins that fulfill crucial roles in the cone phototransduction cascade, which is the most frequently compromised (10 genes) process in CDs. Another 7 CD-associated proteins are required for transport processes towards or through the connecting cilium. The remaining CD-associated proteins are involved in cell membrane morphogenesis and maintenance, synaptic transduction, and the retinoid cycle. Further novel genes are likely to be identified in the near future by combining large-scale DNA sequencing and transcriptomics technologies. For 31 of 42 CD-associated genes, mammalian models are available, 14 of which have successfully been used for gene augmentation studies. However, gene augmentation for CDs should ideally be developed in large mammalian models with cone-rich areas, which are currently available for only 11 CD genes. Future research will aim to elucidate the remaining causative genes, identify the molecular mechanisms of CD, and develop novel therapies aimed at preventing vision loss in individuals with CD in the future.
Collapse
Affiliation(s)
- Susanne Roosing
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | | | - Carel B Hoyng
- Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands; Department of Epidemiology, Erasmus Medical Centre, 3000 CA, Rotterdam, The Netherlands
| | - Anneke I den Hollander
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Department of Ophthalmology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Frans P M Cremers
- Department of Human Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands; Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| |
Collapse
|
40
|
Airik R, Slaats GG, Guo Z, Weiss AC, Khan N, Ghosh A, Hurd TW, Bekker-Jensen S, Schrøder JM, Elledge SJ, Andersen JS, Kispert A, Castelli M, Boletta A, Giles RH, Hildebrandt F. Renal-retinal ciliopathy gene Sdccag8 regulates DNA damage response signaling. J Am Soc Nephrol 2014; 25:2573-83. [PMID: 24722439 DOI: 10.1681/asn.2013050565] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Nephronophthisis-related ciliopathies (NPHP-RCs) are developmental and degenerative kidney diseases that are frequently associated with extrarenal pathologies such as retinal degeneration, obesity, and intellectual disability. We recently identified mutations in a gene encoding the centrosomal protein SDCCAG8 as causing NPHP type 10 in humans. To study the role of Sdccag8 in disease pathogenesis, we generated a Sdccag8 gene-trap mouse line. Homozygous Sdccag8(gt/gt) mice lacked the wild-type Sdccag8 transcript and protein, and recapitulated the human phenotypes of NPHP and retinal degeneration. These mice exhibited early onset retinal degeneration that was associated with rhodopsin mislocalization in the photoreceptors and reduced cone cell numbers, and led to progressive loss of vision. By contrast, renal histologic changes occurred later, and no global ciliary defects were observed in the kidneys. Instead, renal pathology was associated with elevated levels of DNA damage response signaling activity. Cell culture studies confirmed the aberrant activation of DNA damage response in Sdccag8(gt/gt)-derived cells, characterized by elevated levels of γH2AX and phosphorylated ATM and cell cycle profile abnormalities. Our analysis of Sdccag8(gt/gt) mice indicates that the pleiotropic phenotypes in these mice may arise through multiple tissue-specific disease mechanisms.
Collapse
Affiliation(s)
- Rannar Airik
- Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts
| | - Gisela G Slaats
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Zhi Guo
- Department of Genetics, Harvard Medical School, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts
| | - Anna-Carina Weiss
- Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Naheed Khan
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan Medical School, Ann Arbor, Michigan
| | - Amiya Ghosh
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Toby W Hurd
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics and Molecular Medicine, Western General Hospital, Edinburgh, United Kingdom
| | - Simon Bekker-Jensen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob M Schrøder
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Steve J Elledge
- Department of Genetics, Harvard Medical School, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts
| | - Jens S Andersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Andreas Kispert
- Institute of Molecular Biology, Hannover Medical School, Hannover, Germany
| | - Maddalena Castelli
- Division of Genetics and Cell Biology, Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy; and
| | - Alessandra Boletta
- Division of Genetics and Cell Biology, Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy; and
| | - Rachel H Giles
- Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Friedhelm Hildebrandt
- Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts; Howard Hughes Medical Institute, Chevy Chase, Maryland
| |
Collapse
|
41
|
Shukla R, Kannabiran C, Jalali S. Genetics of Leber congenital amaurosis: an update. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.12.14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
42
|
Wheway G, Parry DA, Johnson CA. The role of primary cilia in the development and disease of the retina. Organogenesis 2014; 10:69-85. [PMID: 24162842 PMCID: PMC4049897 DOI: 10.4161/org.26710] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 02/07/2023] Open
Abstract
The normal development and function of photoreceptors is essential for eye health and visual acuity in vertebrates. Mutations in genes encoding proteins involved in photoreceptor development and function are associated with a suite of inherited retinal dystrophies, often as part of complex multi-organ syndromic conditions. In this review, we focus on the role of the photoreceptor outer segment, a highly modified and specialized primary cilium, in retinal health and disease. We discuss the many defects in the structure and function of the photoreceptor primary cilium that can cause a class of inherited conditions known as ciliopathies, often characterized by retinal dystrophy and degeneration, and highlight the recent insights into disease mechanisms.
Collapse
Affiliation(s)
- Gabrielle Wheway
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - David A Parry
- Section of Genetics; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| | - Colin A Johnson
- Section of Ophthalmology and Neurosciences; Leeds Institute of Molecular Medicine; The University of Leeds; Leeds, United Kingdom
| |
Collapse
|
43
|
Successful gene therapy in the RPGRIP1-deficient dog: a large model of cone-rod dystrophy. Mol Ther 2013; 22:265-277. [PMID: 24091916 DOI: 10.1038/mt.2013.232] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 09/22/2013] [Indexed: 12/31/2022] Open
Abstract
For the development of new therapies, proof-of-concept studies in large animal models that share clinical features with their human counterparts represent a pivotal step. For inherited retinal dystrophies primarily involving photoreceptor cells, the efficacy of gene therapy has been demonstrated in canine models of stationary cone dystrophies and progressive rod-cone dystrophies but not in large models of progressive cone-rod dystrophies, another important cause of blindness. To address the last issue, we evaluated gene therapy in the retinitis pigmentosa GTPase regulator interacting protein 1 (RPGRIP1)-deficient dog, a model exhibiting a severe cone-rod dystrophy similar to that seen in humans. Subretinal injection of AAV5 (n = 5) or AAV8 (n = 2) encoding the canine Rpgrip1 improved photoreceptor survival in transduced areas of treated retinas. Cone function was significantly and stably rescued in all treated eyes (18-72% of those recorded in normal eyes) up to 24 months postinjection. Rod function was also preserved (22-29% of baseline function) in four of the five treated dogs up to 24 months postinjection. No detectable rod function remained in untreated contralateral eyes. More importantly, treatment preserved bright- and dim-light vision. Efficacy of gene therapy in this large animal model of cone-rod dystrophy provides great promise for human treatment.
Collapse
|
44
|
Tiwari S, Hudson S, Gattone VH, Miller C, Chernoff EAG, Belecky-Adams TL. Meckelin 3 is necessary for photoreceptor outer segment development in rat Meckel syndrome. PLoS One 2013; 8:e59306. [PMID: 23516626 PMCID: PMC3596335 DOI: 10.1371/journal.pone.0059306] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 02/15/2013] [Indexed: 11/20/2022] Open
Abstract
Ciliopathies lead to multiorgan pathologies that include renal cysts, deafness, obesity and retinal degeneration. Retinal photoreceptors have connecting cilia joining the inner and outer segment that are responsible for transport of molecules to develop and maintain the outer segment process. The present study evaluated meckelin (MKS3) expression during outer segment genesis and determined the consequences of mutant meckelin on photoreceptor development and survival in Wistar polycystic kidney disease Wpk/Wpk rat using immunohistochemistry, analysis of cell death and electron microscopy. MKS3 was ubiquitously expressed throughout the retina at postnatal day 10 (P10) and P21. However, in the mature retina, MKS3 expression was restricted to photoreceptors and the retinal ganglion cell layer. At P10, both the wild type and homozygous Wpk mutant retina had all retinal cell types. In contrast, by P21, cells expressing rod- and cone-specific markers were fewer in number and expression of opsins appeared to be abnormally localized to the cell body. Cell death analyses were consistent with the disappearance of photoreceptor-specific markers and showed that the cells were undergoing caspase-dependent cell death. By electron microscopy, P10 photoreceptors showed rudimentary outer segments with an axoneme, but did not develop outer segment discs that were clearly present in the wild type counterpart. At p21 the mutant outer segments appeared much the same as the P10 mutant outer segments with only a short axoneme, while the wild-type controls had developed outer segments with many well-organized discs. We conclude that MKS3 is not important for formation of connecting cilium and rudimentary outer segments, but is critical for the maturation of outer segment processes.
Collapse
Affiliation(s)
- Sarika Tiwari
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Scott Hudson
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Vincent H. Gattone
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Caroline Miller
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Ellen A. G. Chernoff
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
| | - Teri L. Belecky-Adams
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- Center for Regenerative Biology and Medicine, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana, United States of America
- * E-mail:
| |
Collapse
|
45
|
Photoreceptor sensory cilia and ciliopathies: focus on CEP290, RPGR and their interacting proteins. Cilia 2012; 1:22. [PMID: 23351659 PMCID: PMC3563624 DOI: 10.1186/2046-2530-1-22] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 09/19/2012] [Indexed: 02/08/2023] Open
Abstract
Ciliopathies encompass a broad array of clinical findings associated with genetic defects in biogenesis and/or function of the primary cilium, a ubiquitous organelle involved in the transduction of diverse biological signals. Degeneration or dysfunction of retinal photoreceptors is frequently observed in diverse ciliopathies. The sensory cilium in a photoreceptor elaborates into unique outer segment discs that provide extensive surface area for maximal photon capture and efficient visual transduction. The daily renewal of approximately 10% of outer segments requires a precise control of ciliary transport. Here, we review the ciliopathies with associated retinal degeneration, describe the distinctive structure of the photoreceptor cilium, and discuss mouse models that allow investigations into molecular mechanisms of cilia biogenesis and defects. We have specifically focused on two ciliary proteins - CEP290 and RPGR - that underlie photoreceptor degeneration and syndromic ciliopathies. Mouse models of CEP290 and RPGR disease, and of their multiple interacting partners, have helped unravel new functional insights into cell type-specific phenotypic defects in distinct ciliary proteins. Elucidation of multifaceted ciliary functions and associated protein complexes will require concerted efforts to assimilate diverse datasets from in vivo and in vitro studies. We therefore discuss a possible framework for investigating genetic networks associated with photoreceptor cilia biogenesis and pathology.
Collapse
|
46
|
Kuznetsova T, Iwabe S, Boesze-Battaglia K, Pearce-Kelling S, Chang-Min Y, McDaid K, Miyadera K, Komaromy A, Aguirre GD. Exclusion of RPGRIP1 ins44 from primary causal association with early-onset cone-rod dystrophy in dogs. Invest Ophthalmol Vis Sci 2012; 53:5486-501. [PMID: 22807295 DOI: 10.1167/iovs.12-10178] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
PURPOSE Canine cone-rod dystrophy 1 (cord1) has been previously mapped to CFA15, and a homozygous 44-bp insertion in exon 2 (Ins44) of canine RPGRIP1 (cRPGRIP1(Ins/Ins)) has been associated with the disease. However, from the recent identification of a significant discordance in genotype-phenotype association, we have reexamined the role of cRPGRIP1 in cord1. METHODS Retinal structure and function was assessed by clinical retinal examination, noninvasive imaging, electroretinography, and histopathology/immunohistochemistry. cRPGRIP1 splicing was analyzed by RT-PCR. Retinal gene expression was determined by quantitative RT-PCR (qRT-PCR). Five markers spanning the entire cRPGRIP1 were identified and used for haplotyping. RESULTS Electroretinography demonstrated that cone responses were absent or present in cRPGRIP1(Ins/Ins) individuals. Moreover, performance in vision testing and optical coherence tomography (OCT) were comparable in cRPGRIP1(Ins/Ins) dogs, regardless of the cone ERG status. While histologic changes in retinal structure were minimal, immunohistochemistry demonstrated a lack of cone opsin labeling in cRPGRIP1(Ins/Ins) dogs. cDNA analysis revealed that Ins44 disrupts a putative exonic splicing enhancer that allows for skipping of exon 2, while retaining the functional RPGR-interacting domain (RID) of the protein. New cRPGRIP1 sequence changes were identified, including a 3-bp deletion affecting the 3' acceptor splice site of alternative exon 19c. The extended haplotype spanning cRPGRIP1 was identical in cRPGRIP1(Ins/Ins) dogs with and without retinal degeneration. Gene expression analysis showed that expression levels were not associated with Ins44 genotype. CONCLUSIONS The results indicated that cRPGRIP1 Ins44 is an unlikely primary cause of cord1, and that the causal gene and mutation are likely located elsewhere in the critical disease interval.
Collapse
Affiliation(s)
- Tatyana Kuznetsova
- Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Estrada-Cuzcano A, Roepman R, Cremers FPM, den Hollander AI, Mans DA. Non-syndromic retinal ciliopathies: translating gene discovery into therapy. Hum Mol Genet 2012; 21:R111-24. [PMID: 22843501 DOI: 10.1093/hmg/dds298] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Homozygosity mapping and exome sequencing have accelerated the discovery of gene mutations and modifier alleles implicated in inherited retinal degeneration in humans. To date, 158 genes have been found to be mutated in individuals with retinal dystrophies. Approximately one-third of the gene defects underlying retinal degeneration affect the structure and/or function of the 'connecting cilium' in photoreceptors. This structure corresponds to the transition zone of a prototypic cilium, a region with increasing relevance for ciliary homeostasis. The connecting cilium connects the inner and outer segments of the photoreceptor, mediating bi-directional transport of phototransducing proteins required for vision. In fact, the outer segment, connecting cilium and associated basal body, forms a highly specialized sensory cilium, fully dedicated to photoreception and subsequent signal transduction to the brain. At least 21 genes that encode ciliary proteins are implicated in non-syndromic retinal dystrophies such as cone dystrophy, cone-rod dystrophy, Leber congenital amaurosis (LCA), macular degeneration or retinitis pigmentosa (RP). The generation and characterization of vertebrate retinal ciliopathy animal models have revealed insights into the molecular disease mechanism which are indispensable for the development and evaluation of therapeutic strategies. Gene augmentation therapy has proven to be safe and successful in restoring long-term sight in mice, dogs and humans suffering from LCA or RP. Here, we present a comprehensive overview of the genes, mutations and modifier alleles involved in non-syndromic retinal ciliopathies, review the progress in dissecting the associated retinal disease mechanisms and evaluate gene augmentation approaches to antagonize retinal degeneration in these ciliopathies.
Collapse
|
48
|
Selective loss of RPGRIP1-dependent ciliary targeting of NPHP4, RPGR and SDCCAG8 underlies the degeneration of photoreceptor neurons. Cell Death Dis 2012; 3:e355. [PMID: 22825473 PMCID: PMC3406595 DOI: 10.1038/cddis.2012.96] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The retinitis pigmentosa GTPase regulator (RPGR) and nephrocystin-4 (NPHP4) comprise two key partners of the assembly complex of the RPGR-interacting protein 1 (RPGRIP1). Mutations in RPGR and NPHP4 are linked to severe multisystemic diseases with strong retinal involvement of photoreceptor neurons, whereas those in RPGRIP1 cause the fulminant photoreceptor dystrophy, Leber congenital amaurosis (LCA). Further, mutations in Rpgrip1 and Nphp4 suppress the elaboration of the outer segment compartment of photoreceptor neurons by elusive mechanisms, the understanding of which has critical implications in uncovering the pathogenesis of syndromic retinal dystrophies. Here we show RPGRIP1 localizes to the photoreceptor connecting cilium (CC) distally to the centriole/basal body marker, centrin-2 and the ciliary marker, acetylated-α-tubulin. NPHP4 abuts proximally RPGRIP1, RPGR and the serologically defined colon cancer antigen-8 (SDCCAG8), a protein thought to partake in the RPGRIP1 interactome and implicated also in retinal-renal ciliopathies. Ultrastructurally, RPGRIP1 localizes exclusively throughout the photoreceptor CC and Rpgrip1(nmf247) photoreceptors present shorter cilia with a ruffled membrane. Strikingly, Rpgrip1(nmf247) mice without RPGRIP1 expression lack NPHP4 and RPGR in photoreceptor cilia, whereas the SDCCAG8 and acetylated-α-tubulin ciliary localizations are strongly decreased, even though the NPHP4 and SDCCAG8 expression levels are unaffected and those of acetylated-α-tubulin and γ-tubulin are upregulated. Further, RPGRIP1 loss in photoreceptors shifts the subcellular partitioning of SDCCAG8 and NPHP4 to the membrane fraction associated to the endoplasmic reticulum. Conversely, the ciliary localization of these proteins is unaffected in glomeruli or tubular kidney cells of Rpgrip1(nmf247), but NPHP4 is downregulated developmentally and selectively in kidney cortex. Hence, RPGRIP1 presents cell type-dependent pathological effects crucial to the ciliary targeting and subcellular partitioning of NPHP4, RPGR and SDCCAG8, and acetylation of ciliary α-tubulin or its ciliary targeting, selectively in photoreceptors, but not kidney cells, and these pathological effects underlie photoreceptor degeneration and LCA.
Collapse
|
49
|
Collin GB, Won J, Hicks WL, Cook SA, Nishina PM, Naggert JK. Meckelin is necessary for photoreceptor intraciliary transport and outer segment morphogenesis. Invest Ophthalmol Vis Sci 2012; 53:967-74. [PMID: 22247471 PMCID: PMC3317434 DOI: 10.1167/iovs.11-8766] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/21/2011] [Accepted: 12/30/2011] [Indexed: 01/16/2023] Open
Abstract
PURPOSE Cilia, complex structures found ubiquitously in most vertebrate cells, serve a variety of functions ranging from cell and fluid movement, cell signaling, tissue homeostasis, to sensory perception. Meckelin is a component of ciliary and cell membranes and is encoded by Tmem67 (Mks3). In this study, the retinal morphology and ciliary function in a mouse model for Meckel Syndrome Type 3 (MKS3) throughout the course of photoreceptor development was examined. METHODS To study the effects of a disruption in the Mks3 gene on the retina, the authors introduced a functional allele of Pde6b into B6C3Fe a/a-bpck/J mice and evaluated their retinas by ophthalmoscopic, histologic, and ultrastructural examination. In addition, immunofluorescence microscopy was used to assess protein trafficking through the connecting cilium and to examine the localization of ciliary and synaptic proteins in Tmem67(bpck) mice and controls. RESULTS Photoreceptors degenerate early and rapidly in bpck/bpck mutant mice. In addition, phototransduction proteins, such as rhodopsin, arrestin, and transducin, are mislocalized. Ultrastructural examination of photoreceptors reveal morphologically intact connecting cilia but dysmorphic and misoriented outer segment (OS) discs, at the earliest time point examined. CONCLUSIONS These findings underscore the important role for meckelin in intraciliary transport of phototransduction molecules and their effects on subsequent OS morphogenesis and maintenance.
Collapse
|
50
|
Kuznetsova T, Zangerl B, Aguirre GD. RPGRIP1 and cone-rod dystrophy in dogs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 723:321-8. [PMID: 22183349 DOI: 10.1007/978-1-4614-0631-0_42] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Tatyana Kuznetsova
- Department of Clinical Studies, Section of Ophthalmology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | | | | |
Collapse
|