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Eid AT, Eid KT, Odom JV, Hinkle D, Leys M. Autosomal Dominant Retinitis Pigmentosa Secondary to TOPORS Mutations: A Report of a Novel Mutation and Clinical Findings. J Clin Med 2024; 13:1498. [PMID: 38592336 PMCID: PMC10934045 DOI: 10.3390/jcm13051498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 04/10/2024] Open
Abstract
Purpose: Mutations in Topoisomerase I-binding RS protein (TOPORS) have been previously documented and have been described to result in pathological autosomal dominant retinitis pigmentosa (adRP). In our study, we describe the various genotypes and clinical/phenotypic manifestations of TOPORS-related mutations of our unique patient population in Rural Appalachia. Methods: The medical records of 416 patients with inherited retinal disease at the West Virginia University Eye Institute who had undergone genetic testing between the years of 2015-2022 were reviewed. Patients found to have pathologic RP and mutations related to TOPORS were then analyzed. Results: In total, 7 patients (ages 12-70) were identified amongst three unique families. All patients were female in our study. The average follow-up period was 7.7 years. A mother (70 yr) and daughter (51 yr) had a novel heterozygous nonsense point mutation in TOPORS c.2431C > T, p.Gln811X (Exon 3) that led to premature termination of the desired protein resulting in early onset vision loss, cataract formation, and visual field restriction. The mother developed a full-thickness macular hole which was successfully repaired. Five other patients were found to have previously described TOPORS mutations. Visual field loss was progressive with age in both cohorts. Conclusions: Seven patients at our institution were identified to have mutations in TOPORS resulting in autosomal dominant retinitis pigmentosa. Two patients were found to have novel truncating mutations in the TOPORS gene resulting in profound night blindness and visual field loss, recurrent macular edema, and in one individual, epiretinal membrane formation leading to a macular hole which was able to be successfully repaired.
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Affiliation(s)
- Alen T. Eid
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
| | - Kevin Toni Eid
- Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, UT 84112, USA;
| | - James Vernon Odom
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
| | - David Hinkle
- Tulane University School of Medicine, New Orleans, LA 70112, USA;
| | - Monique Leys
- Department of Ophthalmology and Visual Sciences, West Virginia University School of Medicine, Morgantown, WV 26506, USA;
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2
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Strong A, Qu H, Cullina S, McManus M, Zackai EH, Glessner J, Kenny EE, Hakonarson H. TOPORS as a novel causal gene for Joubert syndrome. Am J Med Genet A 2023; 191:2156-2163. [PMID: 37227088 PMCID: PMC10449431 DOI: 10.1002/ajmg.a.63303] [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: 03/03/2023] [Revised: 04/25/2023] [Accepted: 05/10/2023] [Indexed: 05/26/2023]
Abstract
Joubert syndrome (JBTS) is a Mendelian disorder of the primary cilium defined by the clinical triad of hypotonia, developmental delay, and a distinct cerebellar malformation called the molar tooth sign. JBTS is inherited in an autosomal recessive, autosomal dominant, or X-linked recessive manner. Though over 40 genes have been identified as causal for JBTS, molecular diagnosis is not made in 30%-40% of individuals who meet clinical criteria. TOPORS encodes topoisomerase I-binding arginine/serine-rich protein, and homozygosity for a TOPORS missense variant (c.29C > A; p.(Pro10Gln)) was identified in individuals with the ciliopathy oral-facial-digital syndrome in two families of Dominican descent. Here, we report an additional proband of Dominican ancestry with JBTS found by exome sequencing to be homozygous for the identical p.(Pro10Gln) TOPORS missense variant. Query of the Mount Sinai BioMe biobank, which includes 1880 individuals of Dominican ancestry, supports a high carrier frequency of the TOPORS p.(Pro10Gln) variant in individuals of Dominican descent. Our data nominates TOPORS as a novel causal gene for JBTS and suggests that TOPORS variants should be considered in the differential of ciliopathy-spectrum disease in individuals of Dominican ancestry.
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Affiliation(s)
- Alanna Strong
- The Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- The Center for Applied Genomics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Huiqi Qu
- The Center for Applied Genomics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Sinéad Cullina
- Institute for Genomic Health, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Morgan McManus
- The Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Elaine H. Zackai
- The Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Joseph Glessner
- The Center for Applied Genomics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Eimear E. Kenny
- Institute for Genomic Health, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Division of Genomic Medicine, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Hakon Hakonarson
- The Division of Human Genetics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- The Center for Applied Genomics, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
- Division of Pulmonary Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania
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3
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Cellular and Molecular Mechanisms of Pathogenesis Underlying Inherited Retinal Dystrophies. Biomolecules 2023; 13:biom13020271. [PMID: 36830640 PMCID: PMC9953031 DOI: 10.3390/biom13020271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/23/2023] [Accepted: 01/27/2023] [Indexed: 02/04/2023] Open
Abstract
Inherited retinal dystrophies (IRDs) are congenital retinal degenerative diseases that have various inheritance patterns, including dominant, recessive, X-linked, and mitochondrial. These diseases are most often the result of defects in rod and/or cone photoreceptor and retinal pigment epithelium function, development, or both. The genes associated with these diseases, when mutated, produce altered protein products that have downstream effects in pathways critical to vision, including phototransduction, the visual cycle, photoreceptor development, cellular respiration, and retinal homeostasis. The aim of this manuscript is to provide a comprehensive review of the underlying molecular mechanisms of pathogenesis of IRDs by delving into many of the genes associated with IRD development, their protein products, and the pathways interrupted by genetic mutation.
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Sánchez-Bellver L, Férriz-Gordillo A, Carrillo-Pz M, Rabanal L, Garcia-Gonzalo FR, Marfany G. The Deubiquitinating Enzyme USP48 Interacts with the Retinal Degeneration-Associated Proteins UNC119a and ARL3. Int J Mol Sci 2022; 23:ijms232012527. [PMID: 36293380 PMCID: PMC9603860 DOI: 10.3390/ijms232012527] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 11/16/2022] Open
Abstract
Proteins related to the ubiquitin-proteasome system play an important role during the differentiation and ciliogenesis of photoreceptor cells. Mutations in several genes involved in ubiquitination and proteostasis have been identified as causative of inherited retinal dystrophies (IRDs) and ciliopathies. USP48 is a deubiquitinating enzyme whose role in the retina is still unexplored although previous studies indicate its relevance for neurosensory organs. In this work, we describe that a pool of endogenous USP48 localises to the basal body in retinal cells and provide data that supports the function of USP48 in the photoreceptor cilium. We also demonstrate that USP48 interacts with the IRD-associated proteins ARL3 and UNC119a, and stabilise their protein levels using different mechanisms. Our results suggest that USP48 may act in the regulation/stabilisation of key ciliary proteins for photoreceptor function, in the modulation of intracellular protein transport, and in ciliary trafficking to the photoreceptor outer segment.
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Affiliation(s)
- Laura Sánchez-Bellver
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Andrea Férriz-Gordillo
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Marc Carrillo-Pz
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Laura Rabanal
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
| | - Francesc R. Garcia-Gonzalo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols”, Consejo Superior de Investigaciones Científicas (CSIC), 28029 Madrid, Spain
- Instituto de Investigación Hospital Universitario La Paz (IdiPAZ), 28029 Madrid, Spain
| | - Gemma Marfany
- Department of Genetics, Microbiology and Statistics, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Institut de Biomedicina-Institut de Recerca Sant Joan de Déu (IBUB-IRSJD), Universitat de Barcelona, 08028 Barcelona, Spain
- DBGen Ocular Genomics, 08028 Barcelona, Spain
- Correspondence:
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Wang J, Wang Y, Jiang Y, Li X, Xiao X, Li S, Jia X, Sun W, Wang P, Zhang Q. Autosomal Dominant Retinitis Pigmentosa-Associated TOPORS Protein Truncating Variants Are Exclusively Located in the Region of Amino Acid Residues 807 to 867. Invest Ophthalmol Vis Sci 2022; 63:19. [PMID: 35579903 PMCID: PMC9123486 DOI: 10.1167/iovs.63.5.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Heterozygous truncating variants of TOPORS have been reported to cause autosomal dominant retinitis pigmentosa (adRP). The purpose of this study was to investigate whether all heterozygous truncating variants, including copy number variants (CNVs), are pathogenic. Methods TOPORS truncating variants were collected and reviewed through an in-house dataset and existing databases. Individuals with truncating variants underwent ophthalmological evaluation. Results Six truncating variants were detected in seven families. Three N-terminus truncating variants were detected in three families without RP, and the other three were identified in four unrelated families with typical RP. Based on the in-house dataset and published literature, 17 truncating variants were identified in 47 families with RP. All RP-associated truncating alleles, except one, were distributed in the last exon of TOPORS and clustered in amino acid residues 807 to 867 (46/47, 97.9%). Conversely, in the gnomAD database, only one truncating allele (1/27, 3.7%) was in this region, and the others were outside (26/27, 96.3%), suggesting that the pathogenic truncating variants were significantly clustered in residues 807 to 867 (χ2 = 65.6, P = 1.1 × 10–17). Additionally, three CNVs involving the N-terminus of TOPORS were recorded in control populations but were absent in affected patients. Conclusions This study suggests that all pathogenic truncating variants of TOPORS were clustered in residues 807 to 867, whereas the truncating variants outside this region and the CNVs involving the N-terminus were not associated with RP. A dominant-negative effect, rather than haploinsufficiency, is speculated to be the underlying pathogenesis. These findings provide valuable information for interpreting variation in TOPORS and other genes in similar situations, especially for CNVs.
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Affiliation(s)
- Junwen Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Yingwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Yi Jiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Xueqing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Xueshan Xiao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Shiqiang Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Xiaoyun Jia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Wenmin Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Panfeng Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Qingjiong Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
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6
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He K, Zhou Y, Li N. Mutations of TOPORS identified in families with retinitis pigmentosa. Ophthalmic Genet 2022; 43:371-377. [PMID: 35254173 DOI: 10.1080/13816810.2022.2039721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Kaiwen He
- Department of Ophthalmology, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, China 100045
| | - Yunyu Zhou
- Department of Ophthalmology, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, China 100045
| | - Ningdong Li
- Department of Ophthalmology, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, China 100045
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7
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Kaur G, Singh NK. The Role of Inflammation in Retinal Neurodegeneration and Degenerative Diseases. Int J Mol Sci 2021; 23:ijms23010386. [PMID: 35008812 PMCID: PMC8745623 DOI: 10.3390/ijms23010386] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/24/2021] [Accepted: 12/28/2021] [Indexed: 12/19/2022] Open
Abstract
Retinal neurodegeneration is predominantly reported as the apoptosis or impaired function of the photoreceptors. Retinal degeneration is a major causative factor of irreversible vision loss leading to blindness. In recent years, retinal degenerative diseases have been investigated and many genes and genetic defects have been elucidated by many of the causative factors. An enormous amount of research has been performed to determine the pathogenesis of retinal degenerative conditions and to formulate the treatment modalities that are the critical requirements in this current scenario. Encouraging results have been obtained using gene therapy. We provide a narrative review of the various studies performed to date on the role of inflammation in human retinal degenerative diseases such as age-related macular degeneration, inherited retinal dystrophies, retinitis pigmentosa, Stargardt macular dystrophy, and Leber congenital amaurosis. In addition, we have highlighted the pivotal role of various inflammatory mechanisms in the progress of retinal degeneration. This review also offers an assessment of various therapeutic approaches, including gene-therapies and stem-cell-based therapies, for degenerative retinal diseases.
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Affiliation(s)
- Geetika Kaur
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA;
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Nikhlesh K. Singh
- Integrative Biosciences Center, Wayne State University, Detroit, MI 48202, USA;
- Department of Ophthalmology, Visual and Anatomical Sciences, Wayne State University School of Medicine, Detroit, MI 48202, USA
- Correspondence:
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8
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Strong A, Simone L, Krentz A, Vaccaro C, Watson D, Ron H, Kalish JM, Pedro HF, Zackai EH, Hakonarson H. Expanding the genetic landscape of oral-facial-digital syndrome with two novel genes. Am J Med Genet A 2021; 185:2409-2416. [PMID: 34132027 PMCID: PMC8361718 DOI: 10.1002/ajmg.a.62337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 12/18/2022]
Abstract
Oral‐facial‐digital syndromes (OFDS) are a heterogeneous and rare group of Mendelian disorders characterized by developmental abnormalities of the oral cavity, face, and digits caused by dysfunction of the primary cilium, a mechanosensory organelle that exists atop most cell types that facilitates organ patterning and growth. OFDS is inherited both in an X‐linked dominant, X‐linked recessive, and autosomal recessive manner. Importantly, though many of the causal genes for OFDS have been identified, up to 40% of OFD syndromes are of unknown genetic basis. Here we describe three children with classical presentations of OFDS including lingual hamartomas, polydactyly, and characteristic facial features found by exome sequencing to harbor variants in causal genes not previously associated with OFDS. We describe a female with hypothalamic hamartoma, urogenital sinus, polysyndactyly, and multiple lingual hamartomas consistent with OFDVI with biallelic pathogenic variants in CEP164, a gene associated with ciliopathy‐spectrum disease, but never before with OFDS. We additionally describe two unrelated probands with postaxial polydactyly, multiple lingual hamartomas, and dysmorphic features both found to be homozygous for an identical TOPORS missense variant, c.29 C>A; (p.Pro10Gln). Heterozygous TOPORS pathogenic gene variants are associated with autosomal dominant retinitis pigmentosa, but never before with syndromic ciliopathy. Of note, both probands are of Dominican ancestry, suggesting a possible founder allele.
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Affiliation(s)
- Alanna Strong
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Laurie Simone
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA
| | | | - Courtney Vaccaro
- The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Deborah Watson
- The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Hayley Ron
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Jennifer M Kalish
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Helio F Pedro
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA
| | - Elaine H Zackai
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hakon Hakonarson
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Division of Pulmonary Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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9
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Sánchez-Bellver L, Toulis V, Marfany G. On the Wrong Track: Alterations of Ciliary Transport in Inherited Retinal Dystrophies. Front Cell Dev Biol 2021; 9:623734. [PMID: 33748110 PMCID: PMC7973215 DOI: 10.3389/fcell.2021.623734] [Citation(s) in RCA: 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.
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Affiliation(s)
- Laura Sánchez-Bellver
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
| | - Vasileios Toulis
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Marfany
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain
- CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain
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10
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Buck TM, Vos RM, Alves CH, Wijnholds J. AAV- CRB2 protects against vision loss in an inducible CRB1 retinitis pigmentosa mouse model. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 20:423-441. [PMID: 33575434 PMCID: PMC7848734 DOI: 10.1016/j.omtm.2020.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/21/2020] [Indexed: 01/31/2023]
Abstract
Loss of Crumbs homolog 1 (CRB1) or CRB2 proteins in Müller cells or photoreceptors in the mouse retina results in a CRB dose-dependent retinal phenotype. In this study, we present a novel Müller cell-specific Crb1KOCrb2LowMGC retinitis pigmentosa mouse model (complete loss of CRB1 and reduced levels of CRB2 specifically in Müller cells). The Crb double mutant mice showed deficits in electroretinography, optokinetic head tracking, and retinal morphology. Exposure of retinas to low levels of dl-α-aminoadipate acid induced gliosis and retinal disorganization in Crb1KOCrb2LowMGC retinas but not in wild-type or Crb1-deficient retinas. Crb1KOCrb2LowMGC mice showed a substantial decrease in inner/outer photoreceptor segment length and optokinetic head-tracking response. Intravitreal application of rAAV vectors expressing human CRB2 (hCRB2) in Müller cells of Crb1KOCrb2LowMGC mice subsequently exposed to low levels of dl-α-aminoadipate acid prevented loss of vision, whereas recombinant adeno-associated viral (rAAV) vectors expressing human CRB1 (hCRB1) did not. Both rAAV vectors partially protected the morphology of the retina. The results suggest that hCRB expression in Müller cells is vital for control of retinal cell adhesion at the outer limiting membrane, and that the rAAV-cytomegalovirus (CMV)-hCRB2 vector is more potent than rAAV-minimal CMV (CMVmin)-hCRB1 in protection against loss of vision.
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Affiliation(s)
- Thilo M Buck
- Department of Ophthalmology, Leiden University Medical Center (LUMC), 2333 ZC Leiden, the Netherlands
| | - Rogier M Vos
- Netherlands Institute of Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, the Netherlands
| | - C Henrique Alves
- Department of Ophthalmology, Leiden University Medical Center (LUMC), 2333 ZC Leiden, the Netherlands
| | - Jan Wijnholds
- Department of Ophthalmology, Leiden University Medical Center (LUMC), 2333 ZC Leiden, the Netherlands.,Netherlands Institute of Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, the Netherlands
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11
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Tuo Y, Chu W, Zhang J, Cheng J, Chen L, Bao L, Xiao T. Analysis of Natural Selection of Immune Genes in Spinibarbus caldwelli by Transcriptome Sequencing. Front Genet 2020; 11:714. [PMID: 32793279 PMCID: PMC7393255 DOI: 10.3389/fgene.2020.00714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 06/11/2020] [Indexed: 12/03/2022] Open
Abstract
Spinibarbus caldwelli is an omnivorous cyprinid fish that is distributed widely in China. To investigate the adaptive evolution of S. caldwelli, the muscle transcriptome was sequenced by Illumina HiSeq 4000 platform. A total of 80,447,367 reads were generated by next-generation sequencing. Also, 211,386 unigenes were obtained by de novo assembly. Additionally, we calculated that the divergence time between S. caldwelli and Sinocyclocheilus grahami is 23.14 million years ago (Mya). And both of them diverged from Ctenopharyngodon idellus 46.95 Mya. Furthermore, 38 positive genes were identified by calculating Ka/Ks ratios from 9225 orthologs. Among them, several immune-related genes were identified as positively selected, such as POLR3B, PIK3C3, TOPORS, FASTKD3, CYPLP1A1, and UACA. Our results throw light on the nature of the natural selection of S. caldwelli and contribute to future immunological and transcriptome studies.
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Affiliation(s)
- Yun Tuo
- Hunan Engineering Technology Research Center of Featured Aquatic Resources Utilization, Hunan Agricultural University, Changsha, China.,College of Life Science and Resources Environment, Yichun University, Yichun, China
| | - Wuying Chu
- Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Jianshe Zhang
- Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Jia Cheng
- Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Lin Chen
- Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Lingsheng Bao
- Department of Biological and Environmental Engineering, Changsha University, Changsha, China
| | - Tiaoyi Xiao
- Hunan Engineering Technology Research Center of Featured Aquatic Resources Utilization, Hunan Agricultural University, Changsha, China
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12
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Borges R, Fonseca J, Gomes C, Johnson WE, O'Brien SJ, Zhang G, Gilbert MTP, Jarvis ED, Antunes A. Avian Binocularity and Adaptation to Nocturnal Environments: Genomic Insights from a Highly Derived Visual Phenotype. Genome Biol Evol 2020; 11:2244-2255. [PMID: 31386143 PMCID: PMC6735850 DOI: 10.1093/gbe/evz111] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2019] [Indexed: 01/04/2023] Open
Abstract
Typical avian eyes are phenotypically engineered for photopic vision (daylight). In contrast, the highly derived eyes of the barn owl (Tyto alba) are adapted for scotopic vision (dim light). The dramatic modifications distinguishing barn owl eyes from other birds include: 1) shifts in frontal orientation to improve binocularity, 2) rod-dominated retina, and 3) enlarged corneas and lenses. Some of these features parallel mammalian eye patterns, which are hypothesized to have initially evolved in nocturnal environments. Here, we used an integrative approach combining phylogenomics and functional phenotypes of 211 eye-development genes across 48 avian genomes representing most avian orders, including the stem lineage of the scotopic-adapted barn owl. Overall, we identified 25 eye-development genes that coevolved under intensified or relaxed selection in the retina, lens, cornea, and optic nerves of the barn owl. The agtpbp1 gene, which is associated with the survival of photoreceptor populations, was pseudogenized in the barn owl genome. Our results further revealed that barn owl retinal genes responsible for the maintenance, proliferation, and differentiation of photoreceptors experienced an evolutionary relaxation. Signatures of relaxed selection were also observed in the lens and cornea morphology-associated genes, suggesting that adaptive evolution in these structures was essentially structural. Four eye-development genes (ephb1, phactr4, prph2, and rs1) evolved in positive association with the orbit convergence in birds and under relaxed selection in the barn owl lineage, likely contributing to an increased reliance on binocular vision in the barn owl. Moreover, we found evidence of coevolutionary interactions among genes that are expressed in the retina, lens, and optic nerve, suggesting synergetic adaptive events. Our study disentangles the genomic changes governing the binocularity and low-light perception adaptations of barn owls to nocturnal environments while revealing the molecular mechanisms contributing to the shift from the typical avian photopic vision to the more-novel scotopic-adapted eye.
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Affiliation(s)
- Rui Borges
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Portugal
| | - João Fonseca
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal
| | - Cidália Gomes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal
| | - Warren E Johnson
- Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia.,Walter Reed Biosystematics Unit, Smithsonian Institution, Suitland, Maryland
| | - Stephen J O'Brien
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Russia.,Guy Harvey Oceanographic Center, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University
| | - Guojie Zhang
- Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Denmark.,China National GeneBank, BGI-Shenzen, Shenzhen, China.,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - M Thomas P Gilbert
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Denmark
| | - Erich D Jarvis
- Laboratory of Neurogenetics of Language, Rockefeller University.,Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Agostinho Antunes
- CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal.,Department of Biology, Faculty of Sciences, University of Porto, Portugal
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13
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Toulis V, Marfany G. By the Tips of Your Cilia: Ciliogenesis in the Retina and the Ubiquitin-Proteasome System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1233:303-310. [PMID: 32274763 DOI: 10.1007/978-3-030-38266-7_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Primary cilia are microtubule-based sensory organelles that are involved in the organization of numerous key signals during development and in differentiated tissue homeostasis. In fact, the formation and resorption of cilia highly depends on the cell cycle phase in replicative cells, and the ubiquitin proteasome pathway (UPS) proteins, such as E3 ligases and deubiquitinating enzymes, promote microtubule assembly and disassembly by regulating the degradation/availability of ciliary regulatory proteins. Also, many differentiated tissues display cilia, and mutations in genes encoding ciliary proteins are associated with several human pathologies, named ciliopathies, which are multi-organ rare diseases. The retina is one of the organs most affected by ciliary gene mutations because photoreceptors are ciliated cells. Photoreception and phototransduction occur in the outer segment, a highly specialized neurosensory cilium. In this review, we focus on the function of UPS proteins in ciliogenesis and cilia length control in replicative cells and compare it with the scanty data on the identified UPS genes that cause syndromic and non-syndromic inherited retinal disorders. Clearly, further work using animal models and gene-edited mutants of ciliary genes in cells and organoids will widen the landscape of UPS involvement in ciliogenesis and cilia homeostasis.
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Affiliation(s)
- 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. .,CIBERER, ISCIII, Universitat de Barcelona, Barcelona, Spain. .,Institut de Biomedicina (IBUB-IRSJD), Universitat de Barcelona, Barcelona, Spain.
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14
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Shivanna M, Anand M, Chakrabarti S, Khanna H. Ocular Ciliopathies: Genetic and Mechanistic Insights into Developing Therapies. Curr Med Chem 2019; 26:3120-3131. [PMID: 30221600 DOI: 10.2174/0929867325666180917102557] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 06/21/2018] [Accepted: 09/05/2018] [Indexed: 12/12/2022]
Abstract
Developing suitable medicines for genetic diseases requires a detailed understanding of not only the pathways that cause the disease, but also the identification of the genetic components involved in disease manifestation. This article focuses on the complexities associated with ocular ciliopathies - a class of debilitating disorders of the eye caused by ciliary dysfunction. Ciliated cell types have been identified in both the anterior and posterior segments of the eye. Photoreceptors (rods and cones) are the most studied ciliated neurons in the retina, which is located in the posterior eye. The photoreceptors contain a specialized lightsensing outer segment, or cilium. Any defects in the development or maintenance of the outer segment can result in severe retinal ciliopathies, such as retinitis pigmentosa and Leber congenital amaurosis. A role of cilia in the cell types involved in regulating aqueous fluid outflow in the anterior segment of the eye has also been recognized. Defects in these cell types are frequently associated with some forms of glaucoma. Here, we will discuss the significance of understanding the genetic heterogeneity and the pathogenesis of ocular ciliopathies to develop suitable treatment strategies for these blinding disorders.
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Affiliation(s)
- Mahesh Shivanna
- School of Optometry, Massachusetts College of Pharmacy and Health Sciences University, Worcester, MA, United States
| | - Manisha Anand
- UMASS Medical School, Worcester, MA 01605, United States
| | | | - Hemant Khanna
- UMASS Medical School, Worcester, MA 01605, United States
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15
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Williams LB, Javed A, Sabri A, Morgan DJ, Huff CD, Grigg JR, Heng XT, Khng AJ, Hollink IHIM, Morrison MA, Owen LA, Anderson K, Kinard K, Greenlees R, Novacic D, Nida Sen H, Zein WM, Rodgers GM, Vitale AT, Haider NB, Hillmer AM, Ng PC, Shankaracharya, Cheng A, Zheng L, Gillies MC, van Slegtenhorst M, van Hagen PM, Missotten TOAR, Farley GL, Polo M, Malatack J, Curtin J, Martin F, Arbuckle S, Alexander SI, Chircop M, Davila S, Digre KB, Jamieson RV, DeAngelis MM. ALPK1 missense pathogenic variant in five families leads to ROSAH syndrome, an ocular multisystem autosomal dominant disorder. Genet Med 2019; 21:2103-2115. [PMID: 30967659 PMCID: PMC6752478 DOI: 10.1038/s41436-019-0476-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/25/2019] [Indexed: 01/07/2023] Open
Abstract
Purpose To identify the molecular cause in five unrelated families with a distinct autosomal dominant ocular systemic disorder we called ROSAH syndrome due to clinical features of retinal dystrophy, optic nerve edema, splenomegaly, anhidrosis, and migraine headache. Methods Independent discovery exome and genome sequencing in families 1, 2, and 3, and confirmation in families 4 and 5. Expression of wild-type messenger RNA and protein in human and mouse tissues and cell lines. Ciliary assays in fibroblasts from affected and unaffected family members. Results We found the heterozygous missense variant in the ɑ-kinase gene, ALPK1, (c.710C>T, [p.Thr237Met]), segregated with disease in all five families. All patients shared the ROSAH phenotype with additional low-grade ocular inflammation, pancytopenia, recurrent infections, and mild renal impairment in some. ALPK1 was notably expressed in retina, retinal pigment epithelium, and optic nerve, with immunofluorescence indicating localization to the basal body of the connecting cilium of the photoreceptors, and presence in the sweat glands. Immunocytofluorescence revealed expression at the centrioles and spindle poles during metaphase, and at the base of the primary cilium. Affected family member fibroblasts demonstrated defective ciliogenesis. Conclusion Heterozygosity for ALPK1, p.Thr237Met leads to ROSAH syndrome, an autosomal dominant ocular systemic disorder.
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Affiliation(s)
- Lloyd B Williams
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Asif Javed
- Genome Institute of Singapore, Singapore, Singapore.,School of Biomedical Sciences, The University of Hong Kong, Hong Kong, Hong Kong
| | - Amin Sabri
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
| | - Denise J Morgan
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Chad D Huff
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA.,Department of Epidemiology, Division of OVP, Cancer Prevention and Population Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - John R Grigg
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia.,Discipline of Ophthalmology, University of Sydney, Sydney, NSW, Australia
| | | | | | | | - Margaux A Morrison
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Leah A Owen
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | | | - Krista Kinard
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Rebecca Greenlees
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
| | - Danica Novacic
- National Institutes of Health, National Human Genome Research Institute, Undiagnosed Diseases Network, Bethesda, MD, USA
| | - H Nida Sen
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Wadih M Zein
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - George M Rodgers
- Department of Hematology, Utah Health Sciences Center, Salt Lake City, UT, USA
| | - Albert T Vitale
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Neena B Haider
- Department of Ophthalmology, Schepens Eye Research Institute/Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | | | - Pauline C Ng
- Genome Institute of Singapore, Singapore, Singapore
| | - Shankaracharya
- Department of Epidemiology, Division of OVP, Cancer Prevention and Population Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Anson Cheng
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
| | - Linda Zheng
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia
| | - Mark C Gillies
- Discipline of Ophthalmology, University of Sydney, Sydney, NSW, Australia
| | | | | | | | | | - Michael Polo
- Drs. Farley, Polo and Ho, Colonial Heights, VA, USA
| | - James Malatack
- Nemours/Alfred I. DuPont Hospital for Children, Wilmington, DE, USA
| | - Julie Curtin
- Department of Haematology, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Frank Martin
- Department of Ophthalmology, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Susan Arbuckle
- Department of Pathology, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Stephen I Alexander
- Department of Nephrology, The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Megan Chircop
- Cell Cycle Unit, Children's Medical Research Institute, University of Sydney, Sydney, NSW, Australia
| | - Sonia Davila
- Genome Institute of Singapore, Singapore, Singapore
| | - Kathleen B Digre
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Robyn V Jamieson
- Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, NSW, Australia. .,Disciplines of Genomic Medicine, and Child and Adolescent Health, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia. .,Department of Clinical Genetics, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney Children's Hospitals Network, Sydney, NSW, Australia.
| | - Margaret M DeAngelis
- Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA. .,Department of Pharmacotherapy, College of Pharmacy, University of Utah, Salt Lake City, UT, USA. .,Department of Population Health Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA.
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16
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Graham AM, Lavretsky P, Muñoz-Fuentes V, Green AJ, Wilson RE, McCracken KG. Migration-Selection Balance Drives Genetic Differentiation in Genes Associated with High-Altitude Function in the Speckled Teal (Anas flavirostris) in the Andes. Genome Biol Evol 2018; 10:14-32. [PMID: 29211852 PMCID: PMC5757641 DOI: 10.1093/gbe/evx253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2017] [Indexed: 12/30/2022] Open
Abstract
Local adaptation frequently occurs across populations as a result of migration-selection balance between divergent selective pressures and gene flow associated with life in heterogeneous landscapes. Studying the effects of selection and gene flow on the adaptation process can be achieved in systems that have recently colonized extreme environments. This study utilizes an endemic South American duck species, the speckled teal (Anas flavirostris), which has both high- and low-altitude populations. High-altitude speckled teal (A. f. oxyptera) are locally adapted to the Andean environment and mostly allopatric from low-altitude birds (A. f. flavirostris); however, there is occasional gene flow across altitudinal gradients. In this study, we used next-generation sequencing to explore genetic patterns associated with high-altitude adaptation in speckled teal populations, as well as the extent to which the balance between selection and migration have affected genetic architecture. We identified a set of loci with allele frequencies strongly correlated with altitude, including those involved in the insulin-like signaling pathway, bone morphogenesis, oxidative phosphorylation, responders to hypoxia-induced DNA damage, and feedback loops to the hypoxia-inducible factor pathway. These same outlier loci were found to have depressed gene flow estimates, as well as being highly concentrated on the Z-chromosome. Our results suggest a multifactorial response to life at high altitudes through an array of interconnected pathways that are likely under positive selection and whose genetic components seem to be providing an effective genomic barrier to interbreeding, potentially functioning as an avenue for population divergence and speciation.
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Affiliation(s)
| | | | - Violeta Muñoz-Fuentes
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Estación Biológica de Doñana, EBD-CSIC, Sevilla, Spain
| | - Andy J Green
- Estación Biológica de Doñana, EBD-CSIC, Sevilla, Spain
| | - Robert E Wilson
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska, Fairbanks
| | - Kevin G McCracken
- Department of Biology, University of Miami
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska, Fairbanks
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine
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17
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El Shamieh S, Méjécase C, Bertelli M, Terray A, Michiels C, Condroyer C, Fouquet S, Sadoun M, Clérin E, Liu B, Léveillard T, Goureau O, Sahel JA, Audo I, Zeitz C. Further Insights into the Ciliary Gene and Protein KIZ and Its Murine Ortholog PLK1S1 Mutated in Rod-Cone Dystrophy. Genes (Basel) 2017; 8:genes8100277. [PMID: 29057815 PMCID: PMC5664127 DOI: 10.3390/genes8100277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/04/2017] [Accepted: 10/06/2017] [Indexed: 11/16/2022] Open
Abstract
We identified herein additional patients with rod-cone dystrophy (RCD) displaying mutations in KIZ, encoding the ciliary centrosomal protein kizuna and performed functional characterization of the respective protein in human fibroblasts and of its mouse ortholog PLK1S1 in the retina. Mutation screening was done by targeted next generation sequencing and subsequent Sanger sequencing validation. KIZ mRNA levels were assessed on blood and serum-deprived human fibroblasts from a control individual and a patient, compound heterozygous for the c.52G>T (p.Glu18*) and c.119_122del (p.Lys40Ilefs*14) mutations in KIZ. KIZ localization, documentation of cilium length and immunoblotting were performed in these two fibroblast cell lines. In addition, PLK1S1 immunolocalization was conducted in mouse retinal cryosections and isolated rod photoreceptors. Analyses of additional RCD patients enabled the identification of two homozygous mutations in KIZ, the known c.226C>T (p.Arg76*) mutation and a novel variant, the c.3G>A (p.Met1?) mutation. Albeit the expression levels of KIZ were three-times lower in the patient than controls in whole blood cells, further analyses in control- and mutant KIZ patient-derived fibroblasts unexpectedly revealed no significant difference between the two genotypes. Furthermore, the averaged monocilia length in the two fibroblast cell lines was similar, consistent with the preserved immunolocalization of KIZ at the basal body of the primary cilia. Analyses in mouse retina and isolated rod photoreceptors showed PLK1S1 localization at the base of the photoreceptor connecting cilium. In conclusion, two additional patients with mutations in KIZ were identified, further supporting that defects in KIZ/PLK1S1, detected at the basal body of the primary cilia in fibroblasts, and the photoreceptor connecting cilium in mouse, respectively, are involved in RCD. However, albeit the mutations were predicted to lead to nonsense mediated mRNA decay, we could not detect changes upon expression levels, protein localization or cilia length in KIZ-mutated fibroblast cells. Together, our findings unveil the limitations of fibroblasts as a cellular model for RCD and call for other models such as induced pluripotent stem cells to shed light on retinal pathogenic mechanisms of KIZ mutations.
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Affiliation(s)
- Said El Shamieh
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Department of Medical Laboratory Technology, Faculty of Health Sciences, Beirut Arab University, 115020 Beirut, Lebanon.
| | - Cécile Méjécase
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | | | - Angélique Terray
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Christelle Michiels
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Christel Condroyer
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Stéphane Fouquet
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Maxime Sadoun
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Emmanuelle Clérin
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Binqian Liu
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Thierry Léveillard
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - Olivier Goureau
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
| | - José-Alain Sahel
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, 75012 Paris, France.
- Fondation Ophtalmologique Adolphe de Rothschild, 75019 Paris, France.
- Académie des Sciences-Institut de France, 75006 Paris, France.
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburg, PA 15213, USA.
- Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.
| | - Isabelle Audo
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
- Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, DHU Sight Restore, INSERM-DHOS CIC 1423, 75012 Paris, France.
- Institute of Ophthalmology, University College of London, London, EC1V 9EL, UK.
| | - Christina Zeitz
- Sorbonne Universités, UPMC University Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, 75012 Paris, France.
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18
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Bujakowska KM, Liu Q, Pierce EA. Photoreceptor Cilia and Retinal Ciliopathies. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a028274. [PMID: 28289063 DOI: 10.1101/cshperspect.a028274] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Photoreceptors are sensory neurons designed to convert light stimuli into neurological responses. This process, called phototransduction, takes place in the outer segments (OS) of rod and cone photoreceptors. OS are specialized sensory cilia, with analogous structures to those present in other nonmotile cilia. Deficient morphogenesis and/or dysfunction of photoreceptor sensory cilia (PSC) caused by mutations in a variety of photoreceptor-specific and common cilia genes can lead to inherited retinal degenerations (IRDs). IRDs can manifest as isolated retinal diseases or syndromic diseases. In this review, we describe the structure and composition of PSC and different forms of ciliopathies with retinal involvement. We review the genetics of the IRDs, which are monogenic disorders but genetically diverse with regard to causality.
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Affiliation(s)
- Kinga M Bujakowska
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Qin Liu
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114
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19
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Genetic characterization and disease mechanism of retinitis pigmentosa; current scenario. 3 Biotech 2017; 7:251. [PMID: 28721681 DOI: 10.1007/s13205-017-0878-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 07/10/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa is a group of genetically transmitted disorders affecting 1 in 3000-8000 individual people worldwide ultimately affecting the quality of life. Retinitis pigmentosa is characterized as a heterogeneous genetic disorder which leads by progressive devolution of the retina leading to a progressive visual loss. It can occur in syndromic (with Usher syndrome and Bardet-Biedl syndrome) as well as non-syndromic nature. The mode of inheritance can be X-linked, autosomal dominant or autosomal recessive manner. To date 58 genes have been reported to associate with retinitis pigmentosa most of them are either expressed in photoreceptors or the retinal pigment epithelium. This review focuses on the disease mechanisms and genetics of retinitis pigmentosa. As retinitis pigmentosa is tremendously heterogeneous disorder expressing a multiplicity of mutations; different variations in the same gene might induce different disorders. In recent years, latest technologies including whole-exome sequencing contributing effectively to uncover the hidden genesis of retinitis pigmentosa by reporting new genetic mutations. In future, these advancements will help in better understanding the genotype-phenotype correlations of disease and likely to develop new therapies.
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20
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Latasiewicz M, Salvetti AP, MacLaren RE. A novel mutation in the dominantly inherited TOPORS gene supports haploinsufficiency as the mechanism of retinitis pigmentosa. Ophthalmic Genet 2017; 38:562-566. [PMID: 28453362 DOI: 10.1080/13816810.2017.1313994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND Inherited retinal degenerations are a major cause of untreatable blindness in the younger age group. Recent advances in gene therapy using adeno-associated viral (AAV) vectors have raised the possibility of slowing or stopping retinal degenerations with gene replacement in cases of gene deficiency. MATERIALS AND METHODS In this report, we present a family with autosomal dominant retinitis pigmentosa. A screen for common ADRP genes was performed with 105 genes targeted. Next generation sequencing was used to identify the mutation which was next confirmed by bidirectional Sanger sequencing. RESULTS A novel mutation of the TOPORS gene was identified, c.2539C>T p.(Arg847Ter), resulting in a premature termination codon and suggesting haploinsufficiency as the pathological mechanism. CONCLUSIONS Since the cDNA encoding TOPORS is 3,135 nucleotides (within the coding capacity of AAV vectors) and haploinsufficiency is a mechanism relating to inadequate gene expression, gene replacement therapy may be an option for patients with this condition.
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Affiliation(s)
- Marta Latasiewicz
- a Oxford Eye Hospital , Oxford University Hospitals NHS Foundation Trust , Oxford , UK
| | - Anna Paola Salvetti
- a Oxford Eye Hospital , Oxford University Hospitals NHS Foundation Trust , Oxford , UK.,b Nuffield Laboratory of Ophthalmology, University of Oxford , Oxford , UK
| | - Robert E MacLaren
- a Oxford Eye Hospital , Oxford University Hospitals NHS Foundation Trust , Oxford , UK.,b Nuffield Laboratory of Ophthalmology, University of Oxford , Oxford , UK
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21
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Broadgate S, Yu J, Downes SM, Halford S. Unravelling the genetics of inherited retinal dystrophies: Past, present and future. Prog Retin Eye Res 2017; 59:53-96. [PMID: 28363849 DOI: 10.1016/j.preteyeres.2017.03.003] [Citation(s) in RCA: 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.
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Affiliation(s)
- Suzanne Broadgate
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Jing Yu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK
| | - Susan M Downes
- Oxford Eye Hospital, Oxford University Hospitals NHS Trust, Oxford, OX3 9DU, UK
| | - Stephanie Halford
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, University of Oxford, Levels 5 and 6 West Wing, John Radcliffe Hospital, Headley Way, Oxford, OX3 9DU, UK.
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22
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Blanco-Sánchez B, Clément A, Phillips JB, Westerfield M. Zebrafish models of human eye and inner ear diseases. Methods Cell Biol 2016; 138:415-467. [PMID: 28129854 DOI: 10.1016/bs.mcb.2016.10.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Eye and inner ear diseases are the most common sensory impairments that greatly impact quality of life. Zebrafish have been intensively employed to understand the fundamental mechanisms underlying eye and inner ear development. The zebrafish visual and vestibulo-acoustic systems are very similar to these in humans, and although not yet mature, they are functional by 5days post-fertilization (dpf). In this chapter, we show how the zebrafish has significantly contributed to the field of biomedical research and how researchers, by establishing disease models and meticulously characterizing their phenotypes, have taken the first steps toward therapies. We review here models for (1) eye diseases, (2) ear diseases, and (3) syndromes affecting eye and/or ear. The use of new genome editing technologies and high-throughput screening systems should increase considerably the speed at which knowledge from zebrafish disease models is acquired, opening avenues for better diagnostics, treatments, and therapies.
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Affiliation(s)
| | - A Clément
- University of Oregon, Eugene, OR, United States
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23
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Coppieters F, Ascari G, Dannhausen K, Nikopoulos K, Peelman F, Karlstetter M, Xu M, Brachet C, Meunier I, Tsilimbaris M, Tsika C, Blazaki S, Vergult S, Farinelli P, Van Laethem T, Bauwens M, De Bruyne M, Chen R, Langmann T, Sui R, Meire F, Rivolta C, Hamel C, Leroy B, De Baere E. Isolated and Syndromic Retinal Dystrophy Caused by Biallelic Mutations in RCBTB1, a Gene Implicated in Ubiquitination. Am J Hum Genet 2016; 99:470-80. [PMID: 27486781 PMCID: PMC4974088 DOI: 10.1016/j.ajhg.2016.06.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 06/20/2016] [Indexed: 11/24/2022] Open
Abstract
Inherited retinal dystrophies (iRDs) are a group of genetically and clinically heterogeneous conditions resulting from mutations in over 250 genes. Here, homozygosity mapping and whole-exome sequencing (WES) in a consanguineous family revealed a homozygous missense mutation, c.973C>T (p.His325Tyr), in RCBTB1. In affected individuals, it was found to segregate with retinitis pigmentosa (RP), goiter, primary ovarian insufficiency, and mild intellectual disability. Subsequent analysis of WES data in different cohorts uncovered four additional homozygous missense mutations in five unrelated families in whom iRD segregates with or without syndromic features. Ocular phenotypes ranged from typical RP starting in the second decade to chorioretinal dystrophy with a later age of onset. The five missense mutations affect highly conserved residues either in the sixth repeat of the RCC1 domain or in the BTB1 domain. A founder haplotype was identified for mutation c.919G>A (p.Val307Met), occurring in two families of Mediterranean origin. We showed ubiquitous mRNA expression of RCBTB1 and demonstrated predominant RCBTB1 localization in human inner retina. RCBTB1 was very recently shown to be involved in ubiquitination, more specifically as a CUL3 substrate adaptor. Therefore, the effect on different components of the CUL3 and NFE2L2 (NRF2) pathway was assessed in affected individuals’ lymphocytes, revealing decreased mRNA expression of NFE2L2 and several NFE2L2 target genes. In conclusion, our study puts forward mutations in RCBTB1 as a cause of autosomal-recessive non-syndromic and syndromic iRD. Finally, our data support a role for impaired ubiquitination in the pathogenetic mechanism of RCBTB1 mutations.
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Marshall RA, Osborn DPS. Zebrafish: a vertebrate tool for studying basal body biogenesis, structure, and function. Cilia 2016; 5:16. [PMID: 27168933 PMCID: PMC4862167 DOI: 10.1186/s13630-016-0036-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/01/2016] [Indexed: 02/27/2023] Open
Abstract
Understanding the role of basal bodies (BBs) during development and disease has been largely overshadowed by research into the function of the cilium. Although these two organelles are closely associated, they have specific roles to complete for successful cellular development. Appropriate development and function of the BB are fundamental for cilia function. Indeed, there are a growing number of human genetic diseases affecting ciliary development, known collectively as the ciliopathies. Accumulating evidence suggests that BBs establish cell polarity, direct ciliogenesis, and provide docking sites for proteins required within the ciliary axoneme. Major contributions to our knowledge of BB structure and function have been provided by studies in flagellated or ciliated unicellular eukaryotic organisms, specifically Tetrahymena and Chlamydomonas. Reproducing these and other findings in vertebrates has required animal in vivo models. Zebrafish have fast become one of the primary organisms of choice for modeling vertebrate functional genetics. Rapid ex-utero development, proficient egg laying, ease of genetic manipulation, and affordability make zebrafish an attractive vertebrate research tool. Furthermore, zebrafish share over 80 % of disease causing genes with humans. In this article, we discuss the merits of using zebrafish to study BB functional genetics, review current knowledge of zebrafish BB ultrastructure and mechanisms of function, and consider the outlook for future zebrafish-based BB studies.
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Affiliation(s)
- Ryan A Marshall
- Cell Sciences and Genetics Research Centre, St George's University of London, London, SW17 0RE UK
| | - Daniel P S Osborn
- Cell Sciences and Genetics Research Centre, St George's University of London, London, SW17 0RE UK
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25
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TOPORS, a Dual E3 Ubiquitin and Sumo1 Ligase, Interacts with 26 S Protease Regulatory Subunit 4, Encoded by the PSMC1 Gene. PLoS One 2016; 11:e0148678. [PMID: 26872363 PMCID: PMC4752349 DOI: 10.1371/journal.pone.0148678] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 01/20/2016] [Indexed: 11/19/2022] Open
Abstract
The significance of the ubiquitin-proteasome system (UPS) for protein degradation has been highlighted in the context of neurodegenerative diseases, including retinal dystrophies. TOPORS, a dual E3 ubiquitin and SUMO1 ligase, forms a component of the UPS and selected substrates for its enzymatic activities, such as DJ-1/PARK7 and APOBEC2, are important for neuronal as well as retinal homeostasis, respectively. TOPORS is ubiquitously expressed, yet its mutations are only known to result in autosomal dominant retinitis pigmentosa. We performed a yeast two-hybrid (Y2H) screen of a human retinal cDNA library in order to identify interacting protein partners of TOPORS from the retina, and thus begin delineating the putative disease mechanism(s) associated with the retina-specific phenotype resulting from mutations in TOPORS. The screen led to isolation of the 26 S protease regulatory subunit 4 (P26s4/ PSMC1), an ATPase indispensable for correct functioning of UPS-mediated proteostasis. The interaction between endogenous TOPORS and P26s4 proteins was validated by co-immuno-precipitation from mammalian cell extracts and further characterised by immunofluorescent co-localisation studies in cell lines and retinal sections. Findings from hTERT-RPE1 and 661W cells demonstrated that TOPORS and P26s4 co-localise at the centrosome in cultured cells. Immunofluorescent staining of mouse retinae revealed a strong P26s4 reactivity at the interface between retinal pigmented epithelium (RPE) layer and the photoreceptors outer segments (OS). This finding leads us to speculate that P26s4, along with TOPORS, may have a role(s) in RPE phagocytosis, in addition to contributing to the overall photoreceptor and retinal homeostasis via the UPS.
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Abstract
Visual defects affect a large proportion of humanity, have a significant negative impact on quality of life, and cause significant economic burden. The wide variety of visual disorders and the large number of gene mutations responsible require a flexible animal model system to carry out research for possible causes and cures for the blinding conditions. With eyes similar to humans in structure and function, zebrafish are an important vertebrate model organism that is being used to study genetic and environmental eye diseases, including myopia, glaucoma, retinitis pigmentosa, ciliopathies, albinism, and diabetes. This review details the use of zebrafish in modeling human ocular diseases.
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Affiliation(s)
- Brian A Link
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226; ,
| | - Ross F Collery
- Department of Cell Biology, Neurobiology & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226; ,
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27
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McIntyre JC, Joiner AM, Zhang L, Iñiguez-Lluhí J, Martens JR. SUMOylation regulates ciliary localization of olfactory signaling proteins. J Cell Sci 2015; 128:1934-45. [PMID: 25908845 PMCID: PMC4457158 DOI: 10.1242/jcs.164673] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 03/24/2015] [Indexed: 11/20/2022] Open
Abstract
Cilia are evolutionarily conserved organelles found on many mammalian cell types, including neuronal populations. Although neuronal cilia, including those on olfactory sensory neurons (OSNs), are often delineated by localization of adenylyl cyclase 3 (AC3, also known as ADCY3), the mechanisms responsible for targeting integral membrane proteins are largely unknown. Post-translational modification by small ubiquitin-like modifier (SUMO) proteins plays an important role in protein localization processes such as nuclear-cytosolic transport. Here, we identified through bioinformatic analysis that adenylyl cyclases harbor conserved SUMOylation motifs, and show that AC3 is a substrate for SUMO modification. Functionally, overexpression of the SUMO protease SENP2 prevented ciliary localization of AC3, without affecting ciliation or cilia maintenance. Furthermore, AC3-SUMO mutants did not localize to cilia. To test whether SUMOylation is sufficient for cilia entry, we compared localization of ANO2, which possesses a SUMO motif, and ANO1, which lacks SUMOylation sites and does not localize to cilia. Introduction of SUMOylation sites into ANO1 was not sufficient for ciliary entry. These data suggest that SUMOylation is necessary but not sufficient for ciliary trafficking of select constituents, further establishing the link between ciliary and nuclear import.
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Affiliation(s)
- Jeremy C McIntyre
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, FL 32610, USA
| | - Ariell M Joiner
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lian Zhang
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, FL 32610, USA
| | - Jorge Iñiguez-Lluhí
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jeffrey R Martens
- Department of Pharmacology and Therapeutics, University of Florida, PO Box 100267, Gainesville, FL 32610, USA
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28
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Nash BM, Wright DC, Grigg JR, Bennetts B, Jamieson RV. Retinal dystrophies, genomic applications in diagnosis and prospects for therapy. Transl Pediatr 2015; 4:139-63. [PMID: 26835369 PMCID: PMC4729094 DOI: 10.3978/j.issn.2224-4336.2015.04.03] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Retinal dystrophies (RDs) are degenerative diseases of the retina which have marked clinical and genetic heterogeneity. Common presentations among these disorders include night or colour blindness, tunnel vision and subsequent progression to complete blindness. The known causative disease genes have a variety of developmental and functional roles with mutations in more than 120 genes shown to be responsible for the phenotypes. In addition, mutations within the same gene have been shown to cause different disease phenotypes, even amongst affected individuals within the same family highlighting further levels of complexity. The known disease genes encode proteins involved in retinal cellular structures, phototransduction, the visual cycle, and photoreceptor structure or gene regulation. This review aims to demonstrate the high degree of genetic complexity in both the causative disease genes and their associated phenotypes, highlighting the more common clinical manifestation of retinitis pigmentosa (RP). The review also provides insight to recent advances in genomic molecular diagnosis and gene and cell-based therapies for the RDs.
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Affiliation(s)
- Benjamin M Nash
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Dale C Wright
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - John R Grigg
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Bruce Bennetts
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
| | - Robyn V Jamieson
- 1 Eye Genetics Research Group, Children's Medical Research Institute, University of Sydney, The Children's Hospital at Westmead and Save Sight Institute, Sydney, NSW, Australia ; 2 Sydney Genome Diagnostics, The Children's Hospital at Westmead, Sydney, NSW, Australia ; 3 Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia
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29
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Di Gioia SA, Farinelli P, Letteboer SJF, Arsenijevic Y, Sharon D, Roepman R, Rivolta C. Interactome analysis reveals that FAM161A, deficient in recessive retinitis pigmentosa, is a component of the Golgi-centrosomal network. Hum Mol Genet 2015; 24:3359-71. [PMID: 25749990 DOI: 10.1093/hmg/ddv085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 03/04/2015] [Indexed: 11/13/2022] Open
Abstract
Defects in FAM161A, a protein of unknown function localized at the cilium of retinal photoreceptor cells, cause retinitis pigmentosa, a form of hereditary blindness. By using different fragments of this protein as baits to screen cDNA libraries of human and bovine retinas, we defined a yeast two-hybrid-based FAM161A interactome, identifying 53 bona fide partners. In addition to statistically significant enrichment in ciliary proteins, as expected, this interactome revealed a substantial bias towards proteins from the Golgi apparatus, the centrosome and the microtubule network. Validation of interaction with key partners by co-immunoprecipitation and proximity ligation assay confirmed that FAM161A is a member of the recently recognized Golgi-centrosomal interactome, a network of proteins interconnecting Golgi maintenance, intracellular transport and centrosome organization. Notable FAM161A interactors included AKAP9, FIP3, GOLGA3, KIFC3, KLC2, PDE4DIP, NIN and TRIP11. Furthermore, analysis of FAM161A localization during the cell cycle revealed that this protein followed the centrosome during all stages of mitosis, likely reflecting a specific compartmentalization related to its role at the ciliary basal body during the G0 phase. Altogether, these findings suggest that FAM161A's activities are probably not limited to ciliary tasks but also extend to more general cellular functions, highlighting possible novel mechanisms for the molecular pathology of retinal disease.
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Affiliation(s)
| | - Pietro Farinelli
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
| | - Stef J F Letteboer
- Department of Human Genetics and Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands and
| | - Yvan Arsenijevic
- Unit of Gene Therapy and Stem Cell Biology, Jules-Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland
| | - Dror Sharon
- Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ronald Roepman
- Department of Human Genetics and Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands and
| | - Carlo Rivolta
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
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30
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Tsang SH, Burke T, Oll M, Yzer S, Lee W, Xie YA, Allikmets R. Whole exome sequencing identifies CRB1 defect in an unusual maculopathy phenotype. Ophthalmology 2014; 121:1773-82. [PMID: 24811962 DOI: 10.1016/j.ophtha.2014.03.010] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 03/07/2014] [Accepted: 03/07/2014] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVE To report a new phenotype caused by mutations in the CRB1 gene in a family with 2 affected siblings. DESIGN Molecular genetics and observational case studies. PARTICIPANTS Two affected siblings and 3 unaffected family members. METHODS Each subject received a complete ophthalmic examination together with color fundus photography, fundus autofluorescence (FAF), and spectral-domain optical coherence tomography (SD-OCT). Microperimetry 1 (MP-1) mapping and electroretinogram (ERG) analysis were performed on the proband. Screening for disease-causing mutations was performed by whole exome sequencing in 3 family members followed by segregation analyses in the entire family. MAIN OUTCOME MEASURES Appearance of the macula as examined by clinical examination, fundus photography, FAF imaging, SD-OCT, and visual function by MP-1 and ERG. RESULTS The proband and her affected brother exhibited unusual, previously unreported, findings of a macular dystrophy with relative sparing of the retinal periphery beyond the vascular arcades. The FAF imaging showed severely affected areas of hypoautofluorescence that extended nasally beyond the optic disc in both eyes. A central macular patch of retinal pigment epithelium (RPE) sparing was evident in both eyes on FAF, whereas photoreceptor sparing was documented in the right eye only using SD-OCT. The affected brother presented with irregular patterns of autofluorescence in both eyes characterized by concentric rings of alternating hyper- and hypoautofluorescence, and foveal sparing of photoreceptors and RPE, as seen on SD-OCT, bilaterally. After negative results in screening for mutations in candidate genes including ABCA4 and PRPH2, DNA from 3 members of the family, including both affected siblings and their mother, was screened by whole exome sequencing resulting in identification of 2 CRB1 missense mutations, c.C3991T:p.R1331C and c.C4142T:p.P1381L, which segregated with the disease in the family. Of the 2, the p.R1331C CRB1 mutation has not been described before and the p.P1381L variant has been described in 1 patient with Leber congenital amaurosis. CONCLUSIONS This report illustrates a novel presentation of a macular dystrophy caused by CRB1 mutations. Both affected siblings exhibited a relatively well-developed retinal structure and preservation of generalized retinal function. An unusual 5-year progression of macular atrophy alone was observed that has not been described in any other CRB1-associated phenotypes.
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Affiliation(s)
- Stephen H Tsang
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology & Cell Biology, Columbia University, New York, New York
| | - Tomas Burke
- Department of Ophthalmology, Columbia University, New York, New York; Department of Ophthalmology, Stoke Mandeville Hospital, Aylesbury, Buckinghamshire, United Kingdom
| | - Maris Oll
- Department of Ophthalmology, Columbia University, New York, New York; University Eye Clinic, Tartu University, Tartu, Estonia
| | - Suzanne Yzer
- Department of Ophthalmology, Columbia University, New York, New York; Rotterdam Eye Hospital, Rotterdam, The Netherlands
| | - Winston Lee
- Department of Ophthalmology, Columbia University, New York, New York
| | - Yajing Angela Xie
- Department of Ophthalmology, Columbia University, New York, New York
| | - Rando Allikmets
- Department of Ophthalmology, Columbia University, New York, New York; Department of Pathology & Cell Biology, Columbia University, New York, New York.
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31
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Sergouniotis P, Chakarova C, Murphy C, Becker M, Lenassi E, Arno G, Lek M, MacArthur D, Bhattacharya S, Moore A, Holder G, Robson A, Wolfrum U, Webster A, Plagnol V, Plagnol V. Biallelic variants in TTLL5, encoding a tubulin glutamylase, cause retinal dystrophy. Am J Hum Genet 2014; 94:760-9. [PMID: 24791901 DOI: 10.1016/j.ajhg.2014.04.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 04/02/2014] [Indexed: 12/30/2022] Open
Abstract
In a subset of inherited retinal degenerations (including cone, cone-rod, and macular dystrophies), cone photoreceptors are more severely affected than rods; ABCA4 mutations are the most common cause of this heterogeneous class of disorders. To identify retinal-disease-associated genes, we performed exome sequencing in 28 individuals with "cone-first" retinal disease and clinical features atypical for ABCA4 retinopathy. We then conducted a gene-based case-control association study with an internal exome data set as the control group. TTLL5, encoding a tubulin glutamylase, was highlighted as the most likely disease-associated gene; 2 of 28 affected subjects harbored presumed loss-of-function variants: c.[1586_1589delAGAG];[1586_1589delAGAG], p.[Glu529Valfs(∗)2];[Glu529Valfs(∗)2], and c.[401delT(;)3354G>A], p.[Leu134Argfs(∗)45(;)Trp1118(∗)]. We then inspected previously collected exome sequence data from individuals with related phenotypes and found two siblings with homozygous nonsense variant c.1627G>T (p.Glu543(∗)) in TTLL5. Subsequently, we tested a panel of 55 probands with retinal dystrophy for TTLL5 mutations; one proband had a homozygous missense change (c.1627G>A [p.Glu543Lys]). The retinal phenotype was highly similar in three of four families; the sibling pair had a more severe, early-onset disease. In human and murine retinae, TTLL5 localized to the centrioles at the base of the connecting cilium. TTLL5 has been previously reported to be essential for the correct function of sperm flagella in mice and play a role in polyglutamylation of primary cilia in vitro. Notably, genes involved in the polyglutamylation and deglutamylation of tubulin have been associated with photoreceptor degeneration in mice. The electrophysiological and fundus autofluorescence imaging presented here should facilitate the molecular diagnosis in further families.
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32
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El Shamieh S, Neuillé M, Terray A, Orhan E, Condroyer C, Démontant V, Michiels C, Antonio A, Boyard F, Lancelot ME, Letexier M, Saraiva JP, Léveillard T, Mohand-Saïd S, Goureau O, Sahel JA, Zeitz C, Audo I. Whole-exome sequencing identifies KIZ as a ciliary gene associated with autosomal-recessive rod-cone dystrophy. Am J Hum Genet 2014; 94:625-33. [PMID: 24680887 DOI: 10.1016/j.ajhg.2014.03.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/11/2014] [Indexed: 12/22/2022] Open
Abstract
Rod-cone dystrophy (RCD), also known as retinitis pigmentosa, is a progressive inherited retinal disorder characterized by photoreceptor cell death and genetic heterogeneity. Mutations in many genes have been implicated in the pathophysiology of RCD, but several others remain to be identified. Herein, we applied whole-exome sequencing to a consanguineous family with one subject affected with RCD and identified a homozygous nonsense mutation, c.226C>T (p.Arg76(∗)), in KIZ, which encodes centrosomal protein kizuna. Subsequent Sanger sequencing of 340 unrelated individuals with sporadic and autosomal-recessive RCD identified two other subjects carrying pathogenic variants in KIZ: one with the same homozygous nonsense mutation (c.226C>T [p.Arg76(∗)]) and another with compound-heterozygous mutations c.119_122delAACT (p.Lys40Ilefs(∗)14) and c.52G>T (p.Glu18(∗)). Transcriptomic analysis in mice detected mRNA levels of the mouse ortholog (Plk1s1) in rod photoreceptors, as well as its decreased expression when photoreceptors degenerated in rd1 mice. The presence of the human KIZ transcript was confirmed by quantitative RT-PCR in the retina, the retinal pigment epithelium, fibroblasts, and whole-blood cells (highest expression was in the retina). RNA in situ hybridization demonstrated the presence of Plk1s1 mRNA in the outer nuclear layer of the mouse retina. Immunohistology revealed KIZ localization at the basal body of the cilia in human fibroblasts, thus shedding light on another ciliary protein implicated in autosomal-recessive RCD.
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Affiliation(s)
- Said El Shamieh
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Marion Neuillé
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Angélique Terray
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Elise Orhan
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Christel Condroyer
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Vanessa Démontant
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Christelle Michiels
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Aline Antonio
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Fiona Boyard
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Marie-Elise Lancelot
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Mélanie Letexier
- IntegraGen SA, Genopole Campus 1, Building G8, Evry 91030, France
| | | | - Thierry Léveillard
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - Saddek Mohand-Saïd
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France; Institut National de la Santé et de la Recherche Médicale and Direction de l'Hospitalisation et de l'Organisation des Soins Centre d'Investigation Clinique 1423, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris 75012, France
| | - Olivier Goureau
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France
| | - José-Alain Sahel
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France; Institut National de la Santé et de la Recherche Médicale and Direction de l'Hospitalisation et de l'Organisation des Soins Centre d'Investigation Clinique 1423, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris 75012, France; Fondation Ophtalmologique Adolphe de Rothschild, Paris 75019, France; Académie des Sciences, Institut de France, Paris 75006, France; University College London Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK
| | - Christina Zeitz
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France.
| | - Isabelle Audo
- Institut National de la Santé et de la Recherche Médicale U968, Paris 75012, France; Centre National de la Recherche Scientifique UMR_7210, Paris 75012, France; Institut de la Vision UMR_S 968, Université Pierre et Marie Curie (Paris 6), Sorbonne Universités, Paris 75012, France; Institut National de la Santé et de la Recherche Médicale and Direction de l'Hospitalisation et de l'Organisation des Soins Centre d'Investigation Clinique 1423, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris 75012, France; University College London Institute of Ophthalmology, 11-43 Bath Street, London EC1V 9EL, UK.
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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.
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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
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Daiger SP, Sullivan LS, Bowne SJ. Genes and mutations causing retinitis pigmentosa. Clin Genet 2013; 84:132-41. [PMID: 23701314 PMCID: PMC3856531 DOI: 10.1111/cge.12203] [Citation(s) in RCA: 397] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Revised: 05/20/2013] [Accepted: 05/20/2013] [Indexed: 12/19/2022]
Abstract
Retinitis pigmentosa (RP) is a heterogeneous set of inherited retinopathies with many disease-causing genes, many known mutations, and highly varied clinical consequences. Progress in finding treatments is dependent on determining the genes and mutations causing these diseases, which includes both gene discovery and mutation screening in affected individuals and families. Despite the complexity, substantial progress has been made in finding RP genes and mutations. Depending on the type of RP, and the technology used, it is possible to detect mutations in 30-80% of cases. One of the most powerful approaches to genetic testing is high-throughput 'deep sequencing', that is, next-generation sequencing (NGS). NGS has identified several novel RP genes but a substantial fraction of previously unsolved cases have mutations in genes that are known causes of retinal disease but not necessarily RP. Apparent discrepancy between the molecular defect and clinical findings may warrant reevaluation of patients and families. In this review, we summarize the current approaches to gene discovery and mutation detection for RP, and indicate pitfalls and unsolved problems. Similar considerations apply to other forms of inherited retinal disease.
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Affiliation(s)
- S P Daiger
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center, Houston, TX 77030, USA.
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35
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Riera M, Burguera D, Garcia-Fernàndez J, Gonzàlez-Duarte R. CERKL knockdown causes retinal degeneration in zebrafish. PLoS One 2013; 8:e64048. [PMID: 23671706 PMCID: PMC3650063 DOI: 10.1371/journal.pone.0064048] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 04/08/2013] [Indexed: 12/21/2022] Open
Abstract
The human CERKL gene is responsible for common and severe forms of retinal dystrophies. Despite intense in vitro studies at the molecular and cellular level and in vivo analyses of the retina of murine knockout models, CERKL function remains unknown. In this study, we aimed to approach the developmental and functional features of cerkl in Danio rerio within an Evo-Devo framework. We show that gene expression increases from early developmental stages until the formation of the retina in the optic cup. Unlike the high mRNA-CERKL isoform multiplicity shown in mammals, the moderate transcriptional complexity in fish facilitates phenotypic studies derived from gene silencing. Moreover, of relevance to pathogenicity, teleost CERKL shares the two main human protein isoforms. Morpholino injection has been used to generate a cerkl knockdown zebrafish model. The morphant phenotype results in abnormal eye development with lamination defects, failure to develop photoreceptor outer segments, increased apoptosis of retinal cells and small eyes. Our data support that zebrafish Cerkl does not interfere with proliferation and neural differentiation during early developmental stages but is relevant for survival and protection of the retinal tissue. Overall, we propose that this zebrafish model is a powerful tool to unveil CERKL contribution to human retinal degeneration.
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Affiliation(s)
- Marina Riera
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- CIBERER, Instituto de Salud Carlos III, Barcelona, Spain
| | - Demian Burguera
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Jordi Garcia-Fernàndez
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
| | - Roser Gonzàlez-Duarte
- Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
- Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
- CIBERER, Instituto de Salud Carlos III, Barcelona, Spain
- * E-mail:
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36
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Li Y, Zhang Q, Wei Q, Zhang Y, Ling K, Hu J. SUMOylation of the small GTPase ARL-13 promotes ciliary targeting of sensory receptors. J Cell Biol 2012; 199:589-98. [PMID: 23128241 PMCID: PMC3494855 DOI: 10.1083/jcb.201203150] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 10/10/2012] [Indexed: 11/22/2022] Open
Abstract
Primary cilia serve as cellular antenna for various sensory signaling pathways. However, how the sensory receptors are properly targeted to the ciliary surface remains poorly understood. Here, we show that UBC-9, the sole E2 small ubiquitin-like modifier (SUMO)-conjugating enzyme, physically interacts with and SUMOylates the C terminus of small GTPase ARL-13, the worm orthologue of ARL13B that mutated in ciliopathy Joubert syndrome. Mutations that totally abolish the SUMOylation of ARL-13 do not affect its established role in ciliogenesis, but fail to regulate the proper ciliary targeting of various sensory receptors and consequently compromise the corresponding sensory functions. Conversely, constitutively SUMOylated ARL-13 fully rescues all ciliary defects of arl-13-null animals. Furthermore, SUMOylation modification of human ARL13B is required for the ciliary entry of polycystin-2, the protein mutated in autosomal dominant polycystic kidney disease. Our data reveal a novel but conserved role for the SUMOylation modification of ciliary small GTPase ARL13B in specifically regulating the proper ciliary targeting of various sensory receptors.
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Affiliation(s)
- Yujie Li
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
| | - Qing Zhang
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
| | - Qing Wei
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
| | - Yuxia Zhang
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
| | - Kun Ling
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
| | - Jinghua Hu
- Department of Biochemistry and Molecular Biology, Division of Nephrology and Hypertension, and Department of Internal Medicine, Mayo Translational Polycystic Kidney Disease (PKD) Center, Mayo Clinic, Rochester, MN 55905
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Evidence of a role of inositol polyphosphate 5-phosphatase INPP5E in cilia formation in zebrafish. Vision Res 2012; 75:98-107. [PMID: 23022135 DOI: 10.1016/j.visres.2012.09.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/28/2012] [Accepted: 09/17/2012] [Indexed: 11/23/2022]
Abstract
Inositol phosphatases are important regulators of cell signaling and membrane trafficking. Mutations in inositol polyphosphate 5-phosphatase, INPP5E, have been identified in Joubert syndrome, a rare congenital disorder characterized by midbrain malformation, retinitis pigmentosa, renal cysts, and polydactyly. Previous studies have implicated primary cilia abnormalities in Joubert syndrome, yet the role of INPP5E in cilia formation is not well understood. In this study, we examined the function of INPP5E in cilia development in zebrafish. Using specific antisense morpholino oligonucleotides to knockdown Inpp5e expression, we observed phenotypes of microphthalmia, pronephros cysts, pericardial effusion, and left-right body axis asymmetry. The Inpp5e morphant zebrafish exhibited shortened and decreased cilia formation in the Kupffer's vesicle and pronephric ducts as compared to controls. Epinephrine-stimulated melanosome trafficking was delayed in the Inpp5e zebrafish morphants. Expression of human INPP5E expression rescued the phenotypic defects in the Inpp5e morphants. Taken together, we showed that INPP5E is critical for the cilia development in zebrafish.
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Di Gioia SA, Letteboer SJF, Kostic C, Bandah-Rozenfeld D, Hetterschijt L, Sharon D, Arsenijevic Y, Roepman R, Rivolta C. FAM161A, associated with retinitis pigmentosa, is a component of the cilia-basal body complex and interacts with proteins involved in ciliopathies. Hum Mol Genet 2012; 21:5174-84. [PMID: 22940612 DOI: 10.1093/hmg/dds368] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Retinitis pigmentosa (RP) is a retinal degenerative disease characterized by the progressive loss of photoreceptors. We have previously demonstrated that RP can be caused by recessive mutations in the human FAM161A gene, encoding a protein with unknown function that contains a conserved region shared only with a distant paralog, FAM161B. In this study, we show that FAM161A localizes at the base of the photoreceptor connecting cilium in human, mouse and rat. Furthermore, it is also present at the ciliary basal body in ciliated mammalian cells, both in native conditions and upon the expression of recombinant tagged proteins. Yeast two-hybrid analysis of binary interactions between FAM161A and an array of ciliary and ciliopathy-associated proteins reveals direct interaction with lebercilin, CEP290, OFD1 and SDCCAG8, all involved in hereditary retinal degeneration. These interactions are mediated by the C-terminal moiety of FAM161A, as demonstrated by pull-down experiments in cultured cell lines and in bovine retinal extracts. As other ciliary proteins, FAM161A can also interact with the microtubules and organize itself into microtubule-dependent intracellular networks. Moreover, small interfering RNA-mediated depletion of FAM161A transcripts in cultured cells causes the reduction in assembled primary cilia. Taken together, these data indicate that FAM161A-associated RP can be considered as a novel retinal ciliopathy and that its molecular pathogenesis may be related to other ciliopathies.
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Braun KR, DeWispelaere AM, Bressler SL, Fukai N, Kenagy RD, Chen L, Clowes AW, Kinsella MG. Inhibition of PDGF-B induction and cell growth by syndecan-1 involves the ubiquitin and SUMO-1 ligase, Topors. PLoS One 2012; 7:e43701. [PMID: 22912899 PMCID: PMC3422340 DOI: 10.1371/journal.pone.0043701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/23/2012] [Indexed: 01/14/2023] Open
Abstract
Syndecans are receptors for soluble ligands, including heparin-binding growth factors, and matrix proteins. However, intracellular targets of syndecan-1 (Sdc-1)-mediated signaling are not fully understood. A yeast two-hybrid protein interaction screening of a mouse embryo library identified the ubiquitin and SUMO-1 E3 ligase, Topors, as a novel ligand of the Sdc-1 cytoplasmic domain (S1CD), a finding confirmed by ligand blotting and co-precipitation with Sdc-1 from cell lysates. Deletion mutagenesis identified an 18-amino acid sequence of Topors required for the interaction with the S1CD. By immunohistochemistry, Topors and Sdc-1 co-localized near the cell periphery in normal murine mammary gland (NMuMG) cells in vitro and in mouse embryonic epithelia in vivo. Finally, siRNA-mediated knockdown of Topors demonstrated that Topors is a growth promoter for murine arterial smooth muscle cells and is required for the inhibitory effect of Sdc-1 on cell growth and platelet-derived growth factor-B induction. These data suggest a novel mechanism for the inhibitory effects of Sdc-1 on cell growth that involves the interaction between the cytoplasmic domain of Sdc-1 and the SUMO-1 E3 ligase, Topors.
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Affiliation(s)
- Kathleen R. Braun
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Allison M. DeWispelaere
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Steven L. Bressler
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Nozomi Fukai
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Richard D. Kenagy
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Lihua Chen
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Alexander W. Clowes
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Michael G. Kinsella
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
- * E-mail:
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40
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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.
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Dynamic compression of chondrocyte-agarose constructs reveals new candidate mechanosensitive genes. PLoS One 2012; 7:e36964. [PMID: 22615857 PMCID: PMC3355169 DOI: 10.1371/journal.pone.0036964] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 04/16/2012] [Indexed: 11/19/2022] Open
Abstract
Articular cartilage is physiologically exposed to repeated loads. The mechanical properties of cartilage are due to its extracellular matrix, and homeostasis is maintained by the sole cell type found in cartilage, the chondrocyte. Although mechanical forces clearly control the functions of articular chondrocytes, the biochemical pathways that mediate cellular responses to mechanical stress have not been fully characterised. The aim of our study was to examine early molecular events triggered by dynamic compression in chondrocytes. We used an experimental system consisting of primary mouse chondrocytes embedded within an agarose hydrogel; embedded cells were pre-cultured for one week and subjected to short-term compression experiments. Using Western blots, we demonstrated that chondrocytes maintain a differentiated phenotype in this model system and reproduce typical chondrocyte-cartilage matrix interactions. We investigated the impact of dynamic compression on the phosphorylation state of signalling molecules and genome-wide gene expression. After 15 min of dynamic compression, we observed transient activation of ERK1/2 and p38 (members of the mitogen-activated protein kinase (MAPK) pathways) and Smad2/3 (members of the canonical transforming growth factor (TGF)-β pathways). A microarray analysis performed on chondrocytes compressed for 30 min revealed that only 20 transcripts were modulated more than 2-fold. A less conservative list of 325 modulated genes included genes related to the MAPK and TGF-β pathways and/or known to be mechanosensitive in other biological contexts. Of these candidate mechanosensitive genes, 85% were down-regulated. Down-regulation may therefore represent a general control mechanism for a rapid response to dynamic compression. Furthermore, modulation of transcripts corresponding to different aspects of cellular physiology was observed, such as non-coding RNAs or primary cilium. This study provides new insight into how chondrocytes respond to mechanical forces.
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Luo N, West CC, Murga-Zamalloa CA, Sun L, Anderson RM, Wells CD, Weinreb RN, Travers JB, Khanna H, Sun Y. OCRL localizes to the primary cilium: a new role for cilia in Lowe syndrome. Hum Mol Genet 2012; 21:3333-44. [PMID: 22543976 PMCID: PMC3392109 DOI: 10.1093/hmg/dds163] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Oculocerebral renal syndrome of Lowe (OCRL or Lowe syndrome), a severe X-linked congenital disorder characterized by congenital cataracts and glaucoma, mental retardation and kidney dysfunction, is caused by mutations in the OCRL gene. OCRL is a phosphoinositide 5-phosphatase that interacts with small GTPases and is involved in intracellular trafficking. Despite extensive studies, it is unclear how OCRL mutations result in a myriad of phenotypes found in Lowe syndrome. Our results show that OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia and this phenotype can be rescued by the introduction of wild-type OCRL; in vivo, knockdown of ocrl in zebrafish embryos results in defective cilia formation in Kupffer vesicles and cilia-dependent phenotypes. Cumulatively, our data provide evidence for a role of OCRL in cilia maintenance and suggest the involvement of ciliary dysfunction in the manifestation of Lowe syndrome.
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Affiliation(s)
- Na Luo
- Department of Ophthalmology, Glick Eye Institute, Indiana University, 1601 W Michigan St., Indianapolis, IN 46202, USA
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Mühlhans J, Brandstätter JH, Gießl A. The centrosomal protein pericentrin identified at the basal body complex of the connecting cilium in mouse photoreceptors. PLoS One 2011; 6:e26496. [PMID: 22031837 PMCID: PMC3198765 DOI: 10.1371/journal.pone.0026496] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 09/28/2011] [Indexed: 11/30/2022] Open
Abstract
Background Pericentrin (Pcnt), a conserved protein of the pericentriolar material, serves as a multifunctional scaffold for numerous proteins and plays an important role in microtubule organization. Recent studies indicate that Pcnt mutations are associated with a range of diseases including primordial dwarfism and ciliopathies. To date, three Pcnt splice variants from orthologous genes in mice and humans are known. Principal Findings We generated a specific Pcnt antiserum detecting all known Pcnt splice variants and examined the cellular and subcellular distribution of Pcnt in ciliated tissues of the mouse, the olfactory epithelium and the retina. For the first time, we identified Pcnt and its centrosomal interaction partners at the basal body complex of mouse retinal photoreceptors. Photoreceptors are morphologically and functionally subdivided into the light sensitive outer segment and the inner segment comprising the metabolic function of the cell. The two compartments are linked via a modified, specialized, non-motile cilium, the connecting cilium. Here, Pcnt colocalized with the whole protein machinery responsible for transport processes between the two compartments. Surprisingly, photoreceptors expressed a small Pcnt splice transcript – most likely a modified variant of Pcnt S – which was not present in receptor neurons of the olfactory epithelium. Conclusions Our findings suggest distinct functional roles of several Pcnt variants in different ciliated tissues and sensory neurons, like the olfactory epithelium and the retina of the mouse. The individual patchwork of different Pcnt splice transcripts seems to reflect the complexity of Pcnt function, an assumption corroborated by the heterogeneous clinical manifestations associated with mutations in the Pcnt gene.
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Affiliation(s)
- Johanna Mühlhans
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | | | - Andreas Gießl
- Department of Biology, Animal Physiology, University of Erlangen-Nuremberg, Erlangen, Germany
- * E-mail:
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44
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Nuclear structure and chromosome segregation in Drosophila male meiosis depend on the ubiquitin ligase dTopors. Genetics 2011; 189:779-93. [PMID: 21900273 DOI: 10.1534/genetics.111.133819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many organisms, homolog pairing and synapsis at meiotic prophase depend on interactions between chromosomes and the nuclear membrane. Male Drosophila lack synapsis, but nonetheless, their chromosomes closely associate with the nuclear periphery at prophase I. To explore the functional significance of this association, we characterize mutations in nuclear blebber (nbl), a gene required for both spermatocyte nuclear shape and meiotic chromosome transmission. We demonstrate that nbl corresponds to dtopors, the Drosophila homolog of the mammalian dual ubiquitin/small ubiquitin-related modifier (SUMO) ligase Topors. We show that mutations in dtopors cause abnormalities in lamin localizations, centriole separation, and prophase I chromatin condensation and also cause anaphase I bridges that likely result from unresolved homolog connections. Bridge formation does not require mod(mdg4) in meiosis, suggesting that bridges do not result from misregulation of the male homolog conjunction complex. At the ultrastructural level, we observe disruption of nuclear shape, an uneven perinuclear space, and excess membranous structures. We show that dTopors localizes to the nuclear lamina at prophase, and also transiently to intranuclear foci. As a role of dtopors at gypsy insulator has been reported, we also asked whether these new alleles affected expression of the gypsy-induced mutation ct(6) and found that it was unaltered in dtopors homozygotes. Our results indicate that dTopors is required for germline nuclear structure and meiotic chromosome segregation, but in contrast, is not necessary for gypsy insulator function. We suggest that dtopors plays a structural role in spermatocyte lamina that is critical for multiple aspects of meiotic chromosome transmission.
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Patil SB, Hurd TW, Ghosh AK, Murga-Zamalloa CA, Khanna H. Functional analysis of retinitis pigmentosa 2 (RP2) protein reveals variable pathogenic potential of disease-associated missense variants. PLoS One 2011; 6:e21379. [PMID: 21738648 PMCID: PMC3124502 DOI: 10.1371/journal.pone.0021379] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 05/26/2011] [Indexed: 11/18/2022] Open
Abstract
Genetic mutations are frequently associated with diverse phenotypic consequences, which limits the interpretation of the consequence of a variation in patients. Mutations in the retinitis pigmentosa 2 (RP2) gene are associated with X-linked RP, which is a phenotypically heterogenic form of retinal degeneration. The purpose of this study was to assess the functional consequence of disease-associated mutations in the RP2 gene using an in vivo assay. Morpholino-mediated depletion of rp2 in zebrafish resulted in perturbations in photoreceptor development and microphthalmia (small eye). Ultrastructural and immunofluorescence analyses revealed defective photoreceptor outer segment development and lack of expression of photoreceptor-specific proteins. The retinopathy phenotype could be rescued by expressing the wild-type human RP2 protein. Notably, the tested RP2 mutants exhibited variable degrees of rescue of rod versus cone photoreceptor development as well as microphthalmia. Our results suggest that RP2 plays a key role in photoreceptor development and maintenance in zebrafish and that the clinical heterogeneity associated with RP2 mutations may, in part, result from its potentially distinct functional relevance in rod versus cone photoreceptors.
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Affiliation(s)
- Suresh B. Patil
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Toby W. Hurd
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Amiya K. Ghosh
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Carlos A. Murga-Zamalloa
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Hemant Khanna
- Department of Ophthalmology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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