51
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Iwatani-Yoshihara M, Ito M, Klein MG, Yamamoto T, Yonemori K, Tanaka T, Miwa M, Morishita D, Endo S, Tjhen R, Qin L, Nakanishi A, Maezaki H, Kawamoto T. Discovery of Allosteric Inhibitors Targeting the Spliceosomal RNA Helicase Brr2. J Med Chem 2017; 60:5759-5771. [PMID: 28586220 DOI: 10.1021/acs.jmedchem.7b00461] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Brr2 is an RNA helicase belonging to the Ski2-like subfamily and an essential component of spliceosome. Brr2 catalyzes an ATP-dependent unwinding of the U4/U6 RNA duplex, which is a critical step for spliceosomal activation. An HTS campaign using an RNA-dependent ATPase assay and initial SAR study identified two different Brr2 inhibitors, 3 and 12. Cocrystal structures revealed 3 binds to an unexpected allosteric site between the C-terminal and the N-terminal helicase cassettes, while 12 binds an RNA-binding site inside the N-terminal cassette. Selectivity profiling indicated the allosteric inhibitor 3 is more Brr2-selective than the RNA site binder 12. Chemical optimization of 3 using SBDD culminated in the discovery of the potent and selective Brr2 inhibitor 9 with helicase inhibitory activity. Our findings demonstrate an effective strategy to explore selective inhibitors for helicases, and 9 could be a promising starting point for exploring molecular probes to elucidate biological functions and the therapeutic relevance of Brr2.
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Affiliation(s)
| | | | - Michael G Klein
- Department of Structural Biology, Takeda California Inc. , 10410 Science Center Drive, San Diego, California 92121, United States
| | | | | | | | | | | | | | - Richard Tjhen
- Department of Structural Biology, Takeda California Inc. , 10410 Science Center Drive, San Diego, California 92121, United States
| | - Ling Qin
- Department of Structural Biology, Takeda California Inc. , 10410 Science Center Drive, San Diego, California 92121, United States
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52
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Bujakowska KM, Fernandez-Godino R, Place E, Consugar M, Navarro-Gomez D, White J, Bedoukian EC, Zhu X, Xie HM, Gai X, Leroy BP, Pierce EA. Copy-number variation is an important contributor to the genetic causality of inherited retinal degenerations. Genet Med 2017; 19:643-651. [PMID: 27735924 PMCID: PMC6377944 DOI: 10.1038/gim.2016.158] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 08/30/2016] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Despite substantial progress in sequencing, current strategies can genetically solve only approximately 55-60% of inherited retinal degeneration (IRD) cases. This can be partially attributed to elusive mutations in the known IRD genes, which are not easily identified by the targeted next-generation sequencing (NGS) or Sanger sequencing approaches. We hypothesized that copy-number variations (CNVs) are a major contributor to the elusive genetic causality of IRDs. METHODS Twenty-eight cases previously unsolved with a targeted NGS were investigated with whole-genome single-nucleotide polymorphism (SNP) and comparative genomic hybridization (CGH) arrays. RESULTS Deletions in the IRD genes were detected in 5 of 28 families, including a de novo deletion. We suggest that the de novo deletion occurred through nonallelic homologous recombination (NAHR) and we constructed a genomic map of NAHR-prone regions with overlapping IRD genes. In this article, we also report an unusual case of recessive retinitis pigmentosa due to compound heterozygous mutations in SNRNP200, a gene that is typically associated with the dominant form of this disease. CONCLUSIONS CNV mapping substantially increased the genetic diagnostic rate of IRDs, detecting genetic causality in 18% of previously unsolved cases. Extending the search to other structural variations will probably demonstrate an even higher contribution to genetic causality of IRDs.Genet Med advance online publication 13 October 2016.
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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, USA
| | - Rosario Fernandez-Godino
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Emily Place
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Mark Consugar
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel Navarro-Gomez
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Joseph White
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
| | - Emma C Bedoukian
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Xiaosong Zhu
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Hongbo M Xie
- Department of BioMedical Health Informatics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Xiaowu Gai
- Center for Personalized Medicine, Children's Hospital Los Angeles, Los Angeles, California, USA
| | - Bart P Leroy
- Ophthalmic Genetics &Visual Electrophysiology, Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Ophthalmology &Center for Medical Genetics, Ghent University Hospital &Ghent University, Ghent, Belgium
| | - Eric A Pierce
- Ocular Genomics Institute, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
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53
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Sharma TP, Wiley LA, Whitmore SS, Anfinson KR, Cranston CM, Oppedal DJ, Daggett HT, Mullins RF, Tucker BA, Stone EM. Patient-specific induced pluripotent stem cells to evaluate the pathophysiology of TRNT1-associated Retinitis pigmentosa. Stem Cell Res 2017; 21:58-70. [PMID: 28390992 DOI: 10.1016/j.scr.2017.03.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 02/20/2017] [Accepted: 03/10/2017] [Indexed: 12/18/2022] Open
Abstract
Retinitis pigmentosa (RP) is a heterogeneous group of monogenic disorders characterized by progressive death of the light-sensing photoreceptor cells of the outer neural retina. We recently identified novel hypomorphic mutations in the tRNA Nucleotidyl Transferase, CCA-Adding 1 (TRNT1) gene that cause early-onset RP. To model this disease in vitro, we generated patient-specific iPSCs and iPSC-derived retinal organoids from dermal fibroblasts of patients with molecularly confirmed TRNT1-associated RP. Pluripotency was confirmed using rt-PCR, immunocytochemistry, and a TaqMan Scorecard Assay. Mutations in TRNT1 caused reduced levels of full-length TRNT1 protein and expression of a truncated smaller protein in both patient-specific iPSCs and iPSC-derived retinal organoids. Patient-specific iPSCs and iPSC-derived retinal organoids exhibited a deficit in autophagy, as evidenced by aberrant accumulation of LC3-II and elevated levels of oxidative stress. Autologous stem cell-based disease modeling will provide a platform for testing multiple avenues of treatment in patients suffering from TRNT1-associated RP.
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Affiliation(s)
- Tasneem P Sharma
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Luke A Wiley
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - S Scott Whitmore
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Kristin R Anfinson
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Cathryn M Cranston
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Douglas J Oppedal
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Heather T Daggett
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Robert F Mullins
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Budd A Tucker
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
| | - Edwin M Stone
- Stephen A Wynn Institute for Vision Research, Department of Ophthalmology and Visual Science, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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54
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Xu M, Xie Y(A, Abouzeid H, Gordon CT, Fiorentino A, Sun Z, Lehman A, Osman IS, Dharmat R, Riveiro-Alvarez R, Bapst-Wicht L, Babino D, Arno G, Busetto V, Zhao L, Li H, Lopez-Martinez MA, Azevedo LF, Hubert L, Pontikos N, Eblimit A, Lorda-Sanchez I, Kheir V, Plagnol V, Oufadem M, Soens ZT, Yang L, Bole-Feysot C, Pfundt R, Allaman-Pillet N, Nitschké P, Cheetham ME, Lyonnet S, Agrawal SA, Li H, Pinton G, Michaelides M, Besmond C, Li Y, Yuan Z, von Lintig J, Webster AR, Le Hir H, Stoilov P, Amiel J, Hardcastle AJ, Ayuso C, Sui R, Chen R, Allikmets R, Schorderet DF, Black G, Hall G, Gillespie R, Ramsden S, Manson F, Sergouniotis P, Inglehearn C, Toomes C, Ali M, McKibbin M, Poulter J, Lord E, Nemeth A, Halford S, Downes S, Yu J. Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies. Am J Hum Genet 2017; 100:592-604. [PMID: 28285769 DOI: 10.1016/j.ajhg.2017.02.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 02/15/2017] [Indexed: 10/20/2022] Open
Abstract
Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network.
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55
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Lv JN, Zhou GH, Chen X, Chen H, Wu KC, Xiang L, Lei XL, Zhang X, Wu RH, Jin ZB. Targeted RP9 ablation and mutagenesis in mouse photoreceptor cells by CRISPR-Cas9. Sci Rep 2017; 7:43062. [PMID: 28216641 PMCID: PMC5317003 DOI: 10.1038/srep43062] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 01/17/2017] [Indexed: 01/24/2023] Open
Abstract
Precursor messenger RNA (Pre-mRNA) splicing is an essential biological process in eukaryotic cells. Genetic mutations in many spliceosome genes confer human eye diseases. Mutations in the pre-mRNA splicing factor, RP9 (also known as PAP1), predispose autosomal dominant retinitis pigmentosa (adRP) with an early onset and severe vision loss. However, underlying molecular mechanisms of the RP9 mutation causing photoreceptor degeneration remains fully unknown. Here, we utilize the CRISPR/Cas9 system to generate both the Rp9 gene knockout (KO) and point mutation knock in (KI) (Rp9, c.A386T, P.H129L) which is analogous to the reported one in the retinitis pigmentosa patients (RP9, c.A410T, P.H137L) in 661 W retinal photoreceptor cells in vitro. We found that proliferation and migration were significantly decreased in the mutated cells. Gene expression profiling by RNA-Seq demonstrated that RP associated genes, Fscn2 and Bbs2, were down-regulated in the mutated cells. Furthermore, pre-mRNA splicing of the Fscn2 gene was markedly affected. Our findings reveal a functional relationship between the ubiquitously expressing RP9 and the disease-specific gene, thereafter provide a new insight of disease mechanism in RP9-related retinitis pigmentosa.
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Affiliation(s)
- Ji-Neng Lv
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Gao-Hui Zhou
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Xuejiao Chen
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Hui Chen
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Kun-Chao Wu
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Lue Xiang
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Xin-Lan Lei
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Xiao Zhang
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Rong-Han Wu
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
| | - Zi-Bing Jin
- Lab for Stem Cell &Retinal Regeneration, Institute of Stem Cell Research, The Eye Hospital of Wenzhou Medical University, The State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health Wenzhou 325027, China.,Division of Ophthalmic Genetics, The Eye Hospital of Wenzhou Medical University, Wenzhou 325027, China
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GUCA1A mutation causes maculopathy in a five-generation family with a wide spectrum of severity. Genet Med 2017; 19:945-954. [PMID: 28125083 PMCID: PMC5548935 DOI: 10.1038/gim.2016.217] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 11/18/2016] [Indexed: 12/19/2022] Open
Abstract
PURPOSE The aim of this study was to investigate the genetic basis and pathogenic mechanism of variable maculopathies, ranging from mild photoreceptor degeneration to central areolar choroidal dystrophy, in a five-generation family. METHODS Clinical characterizations, whole-exome sequencing, and genome-wide linkage analysis were carried out on the family. Zebrafish models were used to investigate the pathogenesis of GUCA1A mutations. RESULTS A novel mutation, GUCA1A p.R120L, was identified in the family and predicted to alter the tertiary structure of guanylyl cyclase-activating protein 1, a photoreceptor-expressed protein encoded by the GUCA1A gene. The mutation was shown in zebrafish to cause significant disruptions in photoreceptors and retinal pigment epithelium, together with atrophies of retinal vessels and choriocapillaris. Those phenotypes could not be fully rescued by exogenous wild-type GUCA1A, suggesting a likely gain-of-function mechanism for p.R120L. GUCA1A p.D100E, another mutation previously implicated in cone dystrophy, also impaired the retinal pigment epithelium and photoreceptors in zebrafish, but probably via a dominant negative effect. CONCLUSION We conclude that GUCA1A mutations could cause significant variability in maculopathies, including central areolar choroidal dystrophy, which represents a severe pattern of maculopathy. The diverse pathogenic modes of GUCA1A mutations may explain the phenotypic diversities.Genet Med advance online publication 26 January 2017.
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57
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Van Cauwenbergh C, Coppieters F, Roels D, De Jaegere S, Flipts H, De Zaeytijd J, Walraedt S, Claes C, Fransen E, Van Camp G, Depasse F, Casteels I, de Ravel T, Leroy BP, De Baere E. Mutations in Splicing Factor Genes Are a Major Cause of Autosomal Dominant Retinitis Pigmentosa in Belgian Families. PLoS One 2017; 12:e0170038. [PMID: 28076437 PMCID: PMC5226823 DOI: 10.1371/journal.pone.0170038] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/27/2016] [Indexed: 12/14/2022] Open
Abstract
Purpose Autosomal dominant retinitis pigmentosa (adRP) is characterized by an extensive genetic heterogeneity, implicating 27 genes, which account for 50 to 70% of cases. Here 86 Belgian probands with possible adRP underwent genetic testing to unravel the molecular basis and to assess the contribution of the genes underlying their condition. Methods Mutation detection methods evolved over the past ten years, including mutation specific methods (APEX chip analysis), linkage analysis, gene panel analysis (Sanger sequencing, targeted next-generation sequencing or whole exome sequencing), high-resolution copy number screening (customized microarray-based comparative genomic hybridization). Identified variants were classified following American College of Medical Genetics and Genomics (ACMG) recommendations. Results Molecular genetic screening revealed mutations in 48/86 cases (56%). In total, 17 novel pathogenic mutations were identified: four missense mutations in RHO, five frameshift mutations in RP1, six mutations in genes encoding spliceosome components (SNRNP200, PRPF8, and PRPF31), one frameshift mutation in PRPH2, and one frameshift mutation in TOPORS. The proportion of RHO mutations in our cohort (14%) is higher than reported in a French adRP population (10.3%), but lower than reported elsewhere (16.5–30%). The prevalence of RP1 mutations (10.5%) is comparable to other populations (3.5%-10%). The mutation frequency in genes encoding splicing factors is unexpectedly high (altogether 19.8%), with PRPF31 the second most prevalent mutated gene (10.5%). PRPH2 mutations were found in 4.7% of the Belgian cohort. Two families (2.3%) have the recurrent NR2E3 mutation p.(Gly56Arg). The prevalence of the recurrent PROM1 mutation p.(Arg373Cys) was higher than anticipated (3.5%). Conclusions Overall, we identified mutations in 48 of 86 Belgian adRP cases (56%), with the highest prevalence in RHO (14%), RP1 (10.5%) and PRPF31 (10.5%). Finally, we expanded the molecular spectrum of PRPH2, PRPF8, RHO, RP1, SNRNP200, and TOPORS-associated adRP by the identification of 17 novel mutations.
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Affiliation(s)
- Caroline Van Cauwenbergh
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Frauke Coppieters
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Dimitri Roels
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sarah De Jaegere
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Helena Flipts
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
- Center for Human Genetics, University Hospitals Leuven, Louvain, Belgium
| | - Julie De Zaeytijd
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Sophie Walraedt
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
| | - Charlotte Claes
- Center for Medical Genetics Antwerp, Antwerp University, Antwerp, Belgium
| | - Erik Fransen
- Center for Medical Genetics Antwerp, Antwerp University, Antwerp, Belgium
| | - Guy Van Camp
- Center for Medical Genetics Antwerp, Antwerp University, Antwerp, Belgium
| | - Fanny Depasse
- Department of Ophthalmology, Hôpital Erasme-ULB, Brussels, Belgium
| | - Ingele Casteels
- Department of Ophthalmology, University Hospitals Leuven, Louvain, Belgium
| | - Thomy de Ravel
- Center for Human Genetics, University Hospitals Leuven, Louvain, Belgium
| | - Bart P. Leroy
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
- Department of Ophthalmology, Ghent University and Ghent University Hospital, Ghent, Belgium
- Division of Ophthalmology & Center for Cellular & Molecular Therapy, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Elfride De Baere
- Center for Medical Genetics Ghent, Ghent University and Ghent University Hospital, Ghent, Belgium
- * E-mail:
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58
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Ezquerra-Inchausti M, Barandika O, Anasagasti A, Irigoyen C, López de Munain A, Ruiz-Ederra J. High prevalence of mutations affecting the splicing process in a Spanish cohort with autosomal dominant retinitis pigmentosa. Sci Rep 2017; 7:39652. [PMID: 28045043 PMCID: PMC5206707 DOI: 10.1038/srep39652] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/24/2016] [Indexed: 01/24/2023] Open
Abstract
Retinitis pigmentosa is the most frequent group of inherited retinal dystrophies. It is highly heterogeneous, with more than 80 disease-causing genes 27 of which are known to cause autosomal dominant RP (adRP), having been identified. In this study a total of 29 index cases were ascertained based on a family tree compatible with adRP. A custom panel of 31 adRP genes was analysed by targeted next-generation sequencing using the Ion PGM platform in combination with Sanger sequencing. This allowed us to detect putative disease-causing mutations in 14 out of the 29 (48.28%) families analysed. Remarkably, around 38% of all adRP cases analysed showed mutations affecting the splicing process, mainly due to mutations in genes coding for spliceosome factors (SNRNP200 and PRPF8) but also due to splice-site mutations in RHO. Twelve of the 14 mutations found had been reported previously and two were novel mutations found in PRPF8 in two unrelated patients. In conclusion, our results will lead to more accurate genetic counselling and will contribute to a better characterisation of the disease. In addition, they may have a therapeutic impact in the future given the large number of studies currently underway based on targeted RNA splicing for therapeutic purposes.
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Affiliation(s)
| | - Olatz Barandika
- Division of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain
| | - Ander Anasagasti
- Division of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain
| | - Cristina Irigoyen
- Division of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain.,Department of Ophthalmology, Donostia University Hospital, San Sebastián, Spain
| | - Adolfo López de Munain
- Division of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain.,Department of Neurology, Donostia University Hospital, San Sebastián, Spain.,CIBERNED, Center for Networked Biomedical Research on Neurodegenerative Diseases, Institute of Health Carlos III, Ministry of Economy and Competitiveness, Spain.,Department of Neurosciences, University of the Basque Country UPV-EHU, Spain
| | - Javier Ruiz-Ederra
- Division of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain
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59
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Absmeier E, Santos KF, Wahl MC. Functions and regulation of the Brr2 RNA helicase during splicing. Cell Cycle 2016; 15:3362-3377. [PMID: 27792457 DOI: 10.1080/15384101.2016.1249549] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Pre-mRNA splicing entails the stepwise assembly of an inactive spliceosome, its catalytic activation, splicing catalysis and spliceosome disassembly. Transitions in this reaction cycle are accompanied by compositional and conformational rearrangements of the underlying RNA-protein interaction networks, which are driven and controlled by 8 conserved superfamily 2 RNA helicases. The Ski2-like helicase, Brr2, provides the key remodeling activity during spliceosome activation and is additionally implicated in the catalytic and disassembly phases of splicing, indicating that Brr2 needs to be tightly regulated during splicing. Recent structural and functional analyses have begun to unravel how Brr2 regulation is established via multiple layers of intra- and inter-molecular mechanisms. Brr2 has an unusual structure, including a long N-terminal region and a catalytically inactive C-terminal helicase cassette, which can auto-inhibit and auto-activate the enzyme, respectively. Both elements are essential, also serve as protein-protein interaction devices and the N-terminal region is required for stable Brr2 association with the tri-snRNP, tri-snRNP stability and retention of U5 and U6 snRNAs during spliceosome activation in vivo. Furthermore, a C-terminal region of the Prp8 protein, comprising consecutive RNase H-like and Jab1/MPN-like domains, can both up- and down-regulate Brr2 activity. Biochemical studies revealed an intricate cross-talk among the various cis- and trans-regulatory mechanisms. Comparison of isolated Brr2 to electron cryo-microscopic structures of yeast and human U4/U6•U5 tri-snRNPs and spliceosomes indicates how some of the regulatory elements exert their functions during splicing. The various modulatory mechanisms acting on Brr2 might be exploited to enhance splicing fidelity and to regulate alternative splicing.
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Affiliation(s)
- Eva Absmeier
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Karine F Santos
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany
| | - Markus C Wahl
- a Freie Universität Berlin, Laboratory of Structural Biochemistry , Berlin , Germany.,b Helmholtz-Zentrum Berlin für Materialien und Energie, Macromolecular Crystallography , Berlin , Germany
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60
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Gao L, Li L, Ye J, Zhu X, Shen N, Zhang X, Wang D, Gao Y, Lin H, Wang Y, Liu Y. Identification of a novel mutation in PLA2G6 gene in a Chinese pedigree with familial cortical myoclonic tremor with epilepsy. Seizure 2016; 41:81-5. [PMID: 27513994 DOI: 10.1016/j.seizure.2016.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 07/21/2016] [Accepted: 07/21/2016] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Familial cortical myoclonic tremor with epilepsy (FCMTE) is an epileptic syndrome with autosomal dominant inheritance, of which four genetic subtypes (FCMTE1-4) have been reported. In the present study, we described the clinical and neurophysiologic features of a newly diagnosed Chinese FCMTE family, and investigated the genetic cause for this disease. METHODS Clinical information was obtained from affected and normal individuals of an FCMTE family comprising 41 members. Electroencephalographies were analyzed in five of six affected members (including the proband). Brain magnetic resonance imaging, somatosensory evoked potential with C-reflex analysis and magnetoencephalography was performed in the proband. Genomic DNA of three affected and two unaffected individuals was analyzed to detect the genetic mutations by using whole-exome sequencing. RESULTS The inheritance pattern of the pedigree was autosomal dominant. A novel missense mutation c.475C>T (p.Ala159Thr) of PLA2G6 were identified in this family. The mutated locus is highly conserved among other species. The mutation is predicted to have a functional impact, and completely co-segregated with the phenotype. CONCLUSION This study identifies a novel PLA2G6 mutation that is the possible genetic cause of FCMTE in this family. This mutation and associated clinical features expand the spectrum and phenotypes of PLA2G6-related disorders including neurodegenerative diseases.
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Affiliation(s)
- Lehong Gao
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Liping Li
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Jing Ye
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Xilin Zhu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing 100101, China
| | - Ning Shen
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing 100101, China
| | - Xiating Zhang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Dequan Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Yu Gao
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Hua Lin
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China
| | - Yuping Wang
- Department of Neurology, Xuanwu Hospital, Capital Medical University, The Beijing Key Laboratory of Neuromodulation, Beijing 100053, China.
| | - Ying Liu
- State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing 100101, China.
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Tremblay N, Baril M, Chatel-Chaix L, Es-Saad S, Park AY, Koenekoop RK, Lamarre D. Spliceosome SNRNP200 Promotes Viral RNA Sensing and IRF3 Activation of Antiviral Response. PLoS Pathog 2016; 12:e1005772. [PMID: 27454487 PMCID: PMC4959778 DOI: 10.1371/journal.ppat.1005772] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/27/2016] [Indexed: 12/18/2022] Open
Abstract
Spliceosomal SNRNP200 is a Ski2-like RNA helicase that is associated with retinitis pigmentosa 33 (RP33). Here we found that SNRNP200 promotes viral RNA sensing and IRF3 activation through the ability of its amino-terminal Sec63 domain (Sec63-1) to bind RNA and to interact with TBK1. We show that SNRNP200 relocalizes into TBK1-containing cytoplasmic structures upon infection, in contrast to the RP33-associated S1087L mutant, which is also unable to rescue antiviral response of SNRNP200 knockdown cells. This functional rescue correlates with the Sec63-1-mediated binding of viral RNA. The hindered IFN-β production of knockdown cells was further confirmed in peripheral blood cells of RP33 patients bearing missense mutation in SNRNP200 upon infection with Sendai virus (SeV). This work identifies a novel immunoregulatory role of the spliceosomal SNRNP200 helicase as an RNA sensor and TBK1 adaptor for the activation of IRF3-mediated antiviral innate response. The innate immune system is the first line of defense against pathogens and relies on the recognition of molecular structures specific to pathogens by sensor receptors. These receptors activate a signaling cascade and induce a protective cellular innate immune response. In this study, we provide evidence for a role of the spliceosomal SNRNP200 RNA helicase in promoting antiviral response that is clearly distinguishable of the one in pre-mRNA splicing. The depletion of SNRNP200 in human cells resulted in a reduced interferon-β (IFNB1) production and increased susceptibility to viral infection. We showed that SNRNP200 positively regulates activation of the key transcription factor IRF3 via interaction with TANK kinase 1 (TBK1). Upon infection, SNRNP200 binds viral RNA and relocalizes into TBK1-containing cytoplasmic structures to promote IRF3 activation and IFNB1 production. Of clinical relevance, we observed a significantly hindered antiviral response of PBMCs from patients carrying a dominant SNRNP200 mutation associated with retina pigmentosa type 33 (RP33), an inherited degenerative eye disease. We showed that the RP33-associated S1087L SNRNP200 mutant has lost the ability to bind RNA and that its expression fails to rescue antiviral response in SNRNP200 silenced cells. Our study provides new insights into a role within the antiviral response for spliceosome SNRNP200 helicase as an RNA sensor and TBK1 adaptor in IRF3 signaling.
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Affiliation(s)
- Nicolas Tremblay
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
| | - Martin Baril
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
| | | | - Salwa Es-Saad
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
| | - Alex Young Park
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
| | - Robert K. Koenekoop
- Departments of Pediatric Surgery, Human Genetics and Ophthalmology, McGill University, Montréal, Canada
| | - Daniel Lamarre
- Centre de Recherche du CHUM (CRCHUM), Montréal, Québec, Canada
- Faculté de Médecine, Université de Montréal, Montréal, Canada
- * E-mail:
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Ullah I, Kabir F, Iqbal M, Gottsch CBS, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Pathogenic mutations in TULP1 responsible for retinitis pigmentosa identified in consanguineous familial cases. Mol Vis 2016; 22:797-815. [PMID: 27440997 PMCID: PMC4947966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 07/14/2016] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To identify pathogenic mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous familial cases. METHODS Seven large familial cases with multiple individuals diagnosed with retinitis pigmentosa were included in the study. Affected individuals in these families underwent ophthalmic examinations to document the symptoms and confirm the initial diagnosis. Blood samples were collected from all participating members, and genomic DNA was extracted. An exclusion analysis with microsatellite markers spanning the TULP1 locus on chromosome 6p was performed, and two-point logarithm of odds (LOD) scores were calculated. All coding exons along with the exon-intron boundaries of TULP1 were sequenced bidirectionally. We constructed a single nucleotide polymorphism (SNP) haplotype for the four familial cases harboring the K489R allele and estimated the likelihood of a founder effect. RESULTS The ophthalmic examinations of the affected individuals in these familial cases were suggestive of RP. Exclusion analyses confirmed linkage to chromosome 6p harboring TULP1 with positive two-point LOD scores. Subsequent Sanger sequencing identified the single base pair substitution in exon14, c.1466A>G (p.K489R), in four families. Additionally, we identified a two-base deletion in exon 4, c.286_287delGA (p.E96Gfs77*); a homozygous splice site variant in intron 14, c.1495+4A>C; and a novel missense variation in exon 15, c.1561C>T (p.P521S). All mutations segregated with the disease phenotype in the respective families and were absent in ethnically matched control chromosomes. Haplotype analysis suggested (p<10(-6)) that affected individuals inherited the causal mutation from a common ancestor. CONCLUSIONS Pathogenic mutations in TULP1 are responsible for the RP phenotype in seven familial cases with a common ancestral mutation responsible for the disease phenotype in four of the seven families.
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Affiliation(s)
- Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Muhammad Iqbal
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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Abstract
A majority of human genes contain non-coding intervening sequences – introns that must be precisely excised from the pre-mRNA molecule. This event requires the coordinated action of five major small nuclear ribonucleoprotein particles (snRNPs) along with additional non-snRNP splicing proteins. Introns must be removed with nucleotidal precision, since even a single nucleotide mistake would result in a reading frame shift and production of a non-functional protein. Numerous human inherited diseases are caused by mutations that affect splicing, including mutations in proteins which are directly involved in splicing catalysis. One of the most common hereditary diseases associated with mutations in core splicing proteins is retinitis pigmentosa (RP). So far, mutations in more than 70 genes have been connected to RP. While the majority of mutated genes are expressed specifically in the retina, eight target genes encode for ubiquitous core snRNP proteins (Prpf3, Prpf4, Prpf6, Prpf8, Prpf31, and SNRNP200/Brr2) and splicing factors (RP9 and DHX38). Why mutations in spliceosomal proteins, which are essential in nearly every cell in the body, causes a disease that displays such a tissue-specific phenotype is currently a mystery. In this review, we recapitulate snRNP functions, summarize the missense mutations which are found in spliceosomal proteins as well as their impact on protein functions and discuss specific models which may explain why the retina is sensitive to these mutations.
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Affiliation(s)
- Šárka Růžičková
- a Department of RNA Biology , Institute of Molecular Genetics AS CR , Prague , Czech Republic
| | - David Staněk
- a Department of RNA Biology , Institute of Molecular Genetics AS CR , Prague , Czech Republic
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Kabir F, Ullah I, Ali S, Gottsch AD, Naeem MA, Assir MZ, Khan SN, Akram J, Riazuddin S, Ayyagari R, Hejtmancik JF, Riazuddin SA. Loss of function mutations in RP1 are responsible for retinitis pigmentosa in consanguineous familial cases. Mol Vis 2016; 22:610-25. [PMID: 27307693 PMCID: PMC4901054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 06/08/2016] [Indexed: 10/31/2022] Open
Abstract
PURPOSE This study was undertaken to identify causal mutations responsible for autosomal recessive retinitis pigmentosa (arRP) in consanguineous families. METHODS Large consanguineous families were ascertained from the Punjab province of Pakistan. An ophthalmic examination consisting of a fundus evaluation and electroretinography (ERG) was completed, and small aliquots of blood were collected from all participating individuals. Genomic DNA was extracted from white blood cells, and a genome-wide linkage or a locus-specific exclusion analysis was completed with polymorphic short tandem repeats (STRs). Two-point logarithm of odds (LOD) scores were calculated, and all coding exons and exon-intron boundaries of RP1 were sequenced to identify the causal mutation. RESULTS The ophthalmic examination showed that affected individuals in all families manifest cardinal symptoms of RP. Genome-wide scans localized the disease phenotype to chromosome 8q, a region harboring RP1, a gene previously implicated in the pathogenesis of RP. Sanger sequencing identified a homozygous single base deletion in exon 4: c.3697delT (p.S1233Pfs22*), a single base substitution in intron 3: c.787+1G>A (p.I263Nfs8*), a 2 bp duplication in exon 2: c.551_552dupTA (p.Q185Yfs4*) and an 11,117 bp deletion that removes all three coding exons of RP1. These variations segregated with the disease phenotype within the respective families and were not present in ethnically matched control samples. CONCLUSIONS These results strongly suggest that these mutations in RP1 are responsible for the retinal phenotype in affected individuals of all four consanguineous families.
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Affiliation(s)
- Firoz Kabir
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Inayat Ullah
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Shahbaz Ali
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | | | - Muhammad Asif Naeem
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Zaman Assir
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Shaheen N. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Javed Akram
- Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Sheikh Riazuddin
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan,Allama Iqbal Medical College, University of Health Sciences, Lahore, Pakistan,National Centre for Genetic Diseases, Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan
| | - Radha Ayyagari
- Shiley Eye Institute, University of California, San Diego, CA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
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65
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Ledoux S, Guthrie C. Retinitis Pigmentosa Mutations in Bad Response to Refrigeration 2 (Brr2) Impair ATPase and Helicase Activity. J Biol Chem 2016; 291:11954-65. [PMID: 27072132 DOI: 10.1074/jbc.m115.710848] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Indexed: 11/06/2022] Open
Abstract
Brr2 is an RNA-dependent ATPase required to unwind the U4/U6 snRNA duplex during spliceosome assembly. Mutations within the ratchet helix of the Brr2 RNA binding channel result in a form of degenerative human blindness known as retinitis pigmentosa (RP). The biochemical consequences of these mutations on Brr2's RNA binding, helicase, and ATPase activity have not yet been characterized. Therefore, we identified the largest construct of Brr2 that is soluble in vitro, which truncates the first 247 amino acids of the N terminus (Δ247-Brr2), to characterize the effects of the RP mutations on Brr2 activity. The Δ247-Brr2 RP mutants exhibit a gradient of severity of weakened RNA binding, reduced helicase activity, and reduced ATPase activity compared with wild type Δ247-Brr2. The globular C-terminal Jab1/Mpn1-like domain of Prp8 increases the ability of Δ247-Brr2 to bind the U4/U6 snRNA duplex at high pH and increases Δ247-Brr2's RNA-dependent ATPase activity and the extent of RNA unwinding. However, this domain of Prp8 does not differentially affect the Δ247-Brr2 RP mutants compared with the wild type Δ247-Brr2. When stimulated by Prp8, wild type Δ247-Brr2 is able to unwind long stable duplexes in vitro, and even the RP mutants capable of binding RNA with tight affinity are incapable of fully unwinding short duplex RNAs. Our data suggest that the RP mutations within the ratchet helix impair Brr2 translocation through RNA helices.
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Affiliation(s)
- Sarah Ledoux
- From the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
| | - Christine Guthrie
- From the Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158
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Vichas A, Laurie MT, Zallen JA. The Ski2-family helicase Obelus regulates Crumbs alternative splicing and cell polarity. J Cell Biol 2016; 211:1011-24. [PMID: 26644515 PMCID: PMC4674277 DOI: 10.1083/jcb.201504083] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The conserved Ski2-family helicase Obelus regulates alternative splicing of the Crumbs polarity protein to control epithelial polarity and junctional organization in Drosophila. Alternative splicing can have profound consequences for protein activity, but the functions of most alternative splicing regulators are not known. We show that Obelus, a conserved Ski2-family helicase, is required for cell polarity and adherens junction organization in the Drosophila melanogaster embryo. In obelus mutants, epithelial cells display an expanded apical domain, aggregation of adherens junctions at the cell membrane, and microtubule-dependent defects in centrosome positioning. Through whole-genome transcriptome analysis, we found that Obelus is required for the alternative splicing of a small number of transcripts in the early embryo, including the pre-mRNA that encodes the apical polarity protein Crumbs. In obelus mutants, inclusion of an alternative exon results in increased expression of a Crumbs isoform that contains an additional epidermal growth factor–like repeat in the extracellular domain. Overexpression of this alternative Crumbs isoform recapitulates the junctional aggregation and centrosome positioning defects of obelus mutants. These results indicate that regulation of Crumbs alternative splicing by the Obelus helicase modulates epithelial polarity during development.
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Affiliation(s)
- Athea Vichas
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Matthew T Laurie
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
| | - Jennifer A Zallen
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065
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Rose AM, Bhattacharya SS. Variant haploinsufficiency and phenotypic non-penetrance in PRPF31-associated retinitis pigmentosa. Clin Genet 2016; 90:118-26. [PMID: 26853529 DOI: 10.1111/cge.12758] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Revised: 02/02/2016] [Accepted: 02/03/2016] [Indexed: 11/30/2022]
Abstract
Retinitis pigmentosa (RP) is a genetically heterogenous group of inherited disorders, characterized by death of the retinal photoreceptor cells, leading to progressive visual impairment. One form of RP is caused by mutations in the ubiquitously expressed splicing factor, PRPF31, this form being known as RP11. An intriguing feature of RP11 is the presence of non-penetrance, which has been observed in the majority of PRPF31 mutation-carrying families. In contrast to variable expressivity, which is highly pervasive, true non-penetrance is a very rare phenomenon in Mendelian disorders. In this article, the molecular mechanisms underlying phenotypic non-penetrance in RP11 are explored. It is an elegant example of how our understanding of monogenic disorders has evolved from studying only the disease gene, to considering a mutation on the genetic background of the individual - the logical evolution in this genomic era.
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Affiliation(s)
- A M Rose
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - S S Bhattacharya
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
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Rubio-Peña K, Fontrodona L, Aristizábal-Corrales D, Torres S, Cornes E, García-Rodríguez FJ, Serrat X, González-Knowles D, Foissac S, Porta-De-La-Riva M, Cerón J. Modeling of autosomal-dominant retinitis pigmentosa in Caenorhabditis elegans uncovers a nexus between global impaired functioning of certain splicing factors and cell type-specific apoptosis. RNA (NEW YORK, N.Y.) 2015; 21:2119-31. [PMID: 26490224 PMCID: PMC4647465 DOI: 10.1261/rna.053397.115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/19/2015] [Indexed: 06/05/2023]
Abstract
Retinitis pigmentosa (RP) is a rare genetic disease that causes gradual blindness through retinal degeneration. Intriguingly, seven of the 24 genes identified as responsible for the autosomal-dominant form (adRP) are ubiquitous spliceosome components whose impairment causes disease only in the retina. The fact that these proteins are essential in all organisms hampers genetic, genomic, and physiological studies, but we addressed these difficulties by using RNAi in Caenorhabditis elegans. Our study of worm phenotypes produced by RNAi of splicing-related adRP (s-adRP) genes functionally distinguishes between components of U4 and U5 snRNP complexes, because knockdown of U5 proteins produces a stronger phenotype. RNA-seq analyses of worms where s-adRP genes were partially inactivated by RNAi, revealed mild intron retention in developing animals but not in adults, suggesting a positive correlation between intron retention and transcriptional activity. Interestingly, RNAi of s-adRP genes produces an increase in the expression of atl-1 (homolog of human ATR), which is normally activated in response to replicative stress and certain DNA-damaging agents. The up-regulation of atl-1 correlates with the ectopic expression of the pro-apoptotic gene egl-1 and apoptosis in hypodermal cells, which produce the cuticle, but not in other cell types. Our model in C. elegans resembles s-adRP in two aspects: The phenotype caused by global knockdown of s-adRP genes is cell type-specific and associated with high transcriptional activity. Finally, along with a reduced production of mature transcripts, we propose a model in which the retina-specific cell death in s-adRP patients can be induced through genomic instability.
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Affiliation(s)
- Karinna Rubio-Peña
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Laura Fontrodona
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - David Aristizábal-Corrales
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Silvia Torres
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Eric Cornes
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Francisco J García-Rodríguez
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Xènia Serrat
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - David González-Knowles
- Integromics, Integromics SL, Parque Científico de Madrid, 28760, Tres Cantos, Madrid, Spain
| | | | - Montserrat Porta-De-La-Riva
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain C. elegans Core Facility, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
| | - Julián Cerón
- Cancer and Human Molecular Genetics, Bellvitge Biomedical Research Institute-IDIBELL, Hospitalet de Llobregat, Barcelona 08908, Spain
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Zhang JX, Wang NL, Lu QJ. Development of gene and stem cell therapy for ocular neurodegeneration. Int J Ophthalmol 2015; 8:622-30. [PMID: 26086019 DOI: 10.3980/j.issn.2222-3959.2015.03.33] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 11/12/2014] [Indexed: 12/21/2022] Open
Abstract
Retinal degenerative diseases pose a serious threat to eye health, but there is currently no effective treatment available. Recent years have witnessed rapid development of several cutting-edge technologies, such as gene therapy, stem cell therapy, and tissue engineering. Due to the special features of ocular structure, some of these technologies have been translated into ophthalmological clinic practice with fruitful achievements, setting a good example for other fields. This paper reviews the development of the gene and stem cell therapies in ophthalmology.
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Affiliation(s)
- Jing-Xue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, China
| | - Ning-Li Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, China
| | - Qing-Jun Lu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing 100005, China
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Knocking Down Snrnp200 Initiates Demorphogenesis of Rod Photoreceptors in Zebrafish. J Ophthalmol 2015; 2015:816329. [PMID: 26137319 PMCID: PMC4469172 DOI: 10.1155/2015/816329] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 12/17/2014] [Accepted: 12/29/2014] [Indexed: 11/18/2022] Open
Abstract
Purpose. The small nuclear ribonucleoprotein 200 kDa (SNRNP200) gene is a fundamental component for precursor message RNA (pre-mRNA) splicing and has been implicated in the etiology of autosomal dominant retinitis pigmentosa (adRP). This study aims to determine the consequences of knocking down Snrnp200 in zebrafish. Methods. Expression of the Snrnp200 transcript in zebrafish was determined via whole mount in situ hybridization. Morpholino oligonucleotide (MO) aiming to knock down the expression of Snrnp200 was injected into zebrafish embryos, followed by analyses of aberrant splicing and expression of the U4/U6-U5 tri-small nuclear ribonucleoproteins (snRNPs) components and retina-specific transcripts. Systemic changes and retinal phenotypes were further characterized by histological study and immunofluorescence staining. Results. Snrnp200 was ubiquitously expressed in zebrafish. Knocking down Snrnp200 in zebrafish triggered aberrant splicing of the cbln1 gene, upregulation of other U4/U6-U5 tri-snRNP components, and downregulation of a panel of retina-specific transcripts. Systemic defects were found correlated with knockdown of Snrnp200 in zebrafish. Only demorphogenesis of rod photoreceptors was detected in the initial stage, mimicking the disease characteristics of RP. Conclusions. We conclude that knocking down Snrnp200 in zebrafish could alter regular splicing and expression of a panel of genes, which may eventually trigger rod defects.
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71
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Linder B, Fischer U, Gehring NH. mRNA metabolism and neuronal disease. FEBS Lett 2015; 589:1598-606. [DOI: 10.1016/j.febslet.2015.04.052] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/26/2015] [Accepted: 04/27/2015] [Indexed: 12/12/2022]
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72
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Lehalle D, Wieczorek D, Zechi-Ceide RM, Passos-Bueno MR, Lyonnet S, Amiel J, Gordon CT. A review of craniofacial disorders caused by spliceosomal defects. Clin Genet 2015; 88:405-15. [PMID: 25865758 DOI: 10.1111/cge.12596] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 03/26/2015] [Accepted: 04/07/2015] [Indexed: 02/04/2023]
Abstract
The spliceosome is a large ribonucleoprotein complex that removes introns from pre-mRNA transcripts. Mutations in EFTUD2, encoding a component of the major spliceosome, have recently been identified as the cause of mandibulofacial dysostosis, Guion-Almeida type (MFDGA), characterized by mandibulofacial dysostosis, microcephaly, external ear malformations and intellectual disability. Mutations in several other genes involved in spliceosomal function or linked aspects of mRNA processing have also recently been identified in human disorders with specific craniofacial malformations: SF3B4 in Nager syndrome, an acrofacial dysostosis (AFD); SNRPB in cerebrocostomandibular syndrome, characterized by Robin sequence and rib defects; EIF4A3 in the AFD Richieri-Costa-Pereira syndrome, characterized by Robin sequence, median mandibular cleft and limb defects; and TXNL4A in Burn-McKeown syndrome, involving specific craniofacial dysmorphisms. Here, we review phenotypic and molecular aspects of these syndromes. Given the apparent sensitivity of craniofacial development to defects in mRNA processing, it is possible that mutations in other proteins involved in spliceosomal function will emerge in the future as causative for related human disorders.
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Affiliation(s)
- D Lehalle
- Department of Genetics, APHP, Hôpital Necker-Enfants Malades, Paris, France
| | - D Wieczorek
- Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany
| | - R M Zechi-Ceide
- Departamento de Genetica Clinica, Hospital de Reabilitacao de Anomalias Craniofaciais, Universidade de Sao Paulo (HRAC-USP), Bauru, Brasil
| | - M R Passos-Bueno
- Centro de Estudos do Genoma Humano, Instituto de Biociencias, Universidade de Sao Paulo, Sao Paulo, Brasil
| | - S Lyonnet
- Department of Genetics, APHP, Hôpital Necker-Enfants Malades, Paris, France.,INSERM UMR 1163, Institut Imagine, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - J Amiel
- Department of Genetics, APHP, Hôpital Necker-Enfants Malades, Paris, France.,INSERM UMR 1163, Institut Imagine, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
| | - C T Gordon
- INSERM UMR 1163, Institut Imagine, Paris, France.,Université Paris Descartes-Sorbonne Paris Cité, Institut Imagine, Paris, France
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73
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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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74
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Absmeier E, Rosenberger L, Apelt L, Becke C, Santos KF, Stelzl U, Wahl MC. A noncanonical PWI domain in the N-terminal helicase-associated region of the spliceosomal Brr2 protein. ACTA ACUST UNITED AC 2015; 71:762-71. [DOI: 10.1107/s1399004715001005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/16/2015] [Indexed: 11/10/2022]
Abstract
The spliceosomal RNA helicase Brr2 is required for the assembly of a catalytically active spliceosome on a messenger RNA precursor. Brr2 exhibits an unusual organization with tandem helicase units, each comprising dual RecA-like domains and a Sec63 homology unit, preceded by a more than 400-residue N-terminal helicase-associated region. Whereas recent crystal structures have provided insights into the molecular architecture and regulation of the Brr2 helicase region, little is known about the structural organization and function of its N-terminal part. Here, a near-atomic resolution crystal structure of a PWI-like domain that resides in the N-terminal region ofChaetomium thermophilumBrr2 is presented. CD spectroscopic studies suggested that this domain is conserved in the yeast and human Brr2 orthologues. Although canonical PWI domains act as low-specificity nucleic acid-binding domains, no significant affinity of the unusual PWI domain of Brr2 for a broad spectrum of DNAs and RNAs was detected in band-shift assays. Consistently, theC. thermophilumBrr2 PWI-like domain, in the conformation seen in the present crystal structure, lacks an expanded positively charged surface patch as observed in at least one canonical, nucleic acid-binding PWI domain. Instead, in a comprehensive yeast two-hybrid screen against human spliceosomal proteins, fragments of the N-terminal region of human Brr2 were found to interact with several other spliceosomal proteins. At least one of these interactions, with the Prp19 complex protein SPF27, depended on the presence of the PWI-like domain. The results suggest that the N-terminal region of Brr2 serves as a versatile protein–protein interaction platform in the spliceosome and that some interactions require or are reinforced by the PWI-like domain.
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75
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Zhang L, Li X, Hill RC, Qiu Y, Zhang W, Hansen KC, Zhao R. Brr2 plays a role in spliceosomal activation in addition to U4/U6 unwinding. Nucleic Acids Res 2015; 43:3286-97. [PMID: 25670679 PMCID: PMC4381053 DOI: 10.1093/nar/gkv062] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Accepted: 01/19/2015] [Indexed: 12/22/2022] Open
Abstract
Brr2 is a DExD/H-box RNA helicase that is responsible for U4/U6 unwinding, a critical step in spliceosomal activation. Brr2 is a large protein (∼250 kD) that consists of an N-terminal domain (∼500 residues) with unknown function and two Hel308-like modules that are responsible for RNA unwinding. Here we demonstrate that removal of the entire N-terminal domain is lethal to Saccharomyces cerevisiae and deletion of the N-terminal 120 residues leads to splicing defects and severely impaired growth. This N-terminal truncation does not significantly affect Brr2's helicase activity. Brr2-Δ120 can be successfully assembled into the tri-snRNP (albeit at a lower level than the WT Brr2) and the spliceosomal B complex. However, the truncation significantly impairs spliceosomal activation, leading to a dramatic reduction of U5, U6 snRNAs and accumulation of U1 snRNA in the Bact complex. The N-terminal domain of Brr2 does not seem to be directly involved in regulating U1/5'ss unwinding. Instead, the N-terminal domain seems to be critical for retaining U5 and U6 snRNPs during/after spliceosomal activation through its interaction with snRNAs and possibly other spliceosomal proteins, revealing a new role of Brr2 in spliceosomal activation in addition to U4/U6 unwinding.
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Affiliation(s)
- Lingdi Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Xueni Li
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Ryan C Hill
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Yan Qiu
- College of Bioscience and Bioengineering, Hebei University of Science and Technology, Shijiazhuang 050018, P. R. China
| | - Wenzheng Zhang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Rui Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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76
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Wickramasinghe VO, Gonzàlez-Porta M, Perera D, Bartolozzi AR, Sibley CR, Hallegger M, Ule J, Marioni JC, Venkitaraman AR. Regulation of constitutive and alternative mRNA splicing across the human transcriptome by PRPF8 is determined by 5' splice site strength. Genome Biol 2015; 16:201. [PMID: 26392272 PMCID: PMC4578845 DOI: 10.1186/s13059-015-0749-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 07/27/2015] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Sequential assembly of the human spliceosome on RNA transcripts regulates splicing across the human transcriptome. The core spliceosome component PRPF8 is essential for spliceosome assembly through its participation in ribonucleoprotein (RNP) complexes for splice-site recognition, branch-point formation and catalysis. PRPF8 deficiency is linked to human diseases like retinitis pigmentosa or myeloid neoplasia, but its genome-wide effects on constitutive and alternative splicing remain unclear. RESULTS Here, we show that alterations in RNA splicing patterns across the human transcriptome that occur in conditions of restricted cellular PRPF8 abundance are defined by the altered splicing of introns with weak 5' splice sites. iCLIP of spliceosome components reveals that PRPF8 depletion decreases RNP complex formation at most splice sites in exon-intron junctions throughout the genome. However, impaired splicing affects only a subset of human transcripts, enriched for mitotic cell cycle factors, leading to mitotic arrest. Preferentially retained introns and differentially used exons in the affected genes contain weak 5' splice sites, but are otherwise indistinguishable from adjacent spliced introns. Experimental enhancement of splice-site strength in mini-gene constructs overcomes the effects of PRPF8 depletion on the kinetics and fidelity of splicing during transcription. CONCLUSIONS Competition for PRPF8 availability alters the transcription-coupled splicing of RNAs in which weak 5' splice sites predominate, enabling diversification of human gene expression during biological processes like mitosis. Our findings exemplify the regulatory potential of changes in the core spliceosome machinery, which may be relevant to slow-onset human genetic diseases linked to PRPF8 deficiency.
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Affiliation(s)
- Vihandha O. Wickramasinghe
- The Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Box 197, Cambridge, CB2 0XZ UK
| | - Mar Gonzàlez-Porta
- European Molecular Biology Laboratory - European Bioinformatics Institute (EMBL-EBI), Hinxton, UK
| | - David Perera
- The Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Box 197, Cambridge, CB2 0XZ UK
| | - Arthur R. Bartolozzi
- The Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Box 197, Cambridge, CB2 0XZ UK
| | - Christopher R. Sibley
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, WC1N 3BG UK
| | - Martina Hallegger
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, WC1N 3BG UK
| | - Jernej Ule
- Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, WC1N 3BG UK
| | - John C. Marioni
- European Molecular Biology Laboratory - European Bioinformatics Institute (EMBL-EBI), Hinxton, UK
| | - Ashok R. Venkitaraman
- The Medical Research Council Cancer Unit, University of Cambridge, Cambridge Biomedical Campus, Box 197, Cambridge, CB2 0XZ UK
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77
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Linder B, Hirmer A, Gal A, Rüther K, Bolz HJ, Winkler C, Laggerbauer B, Fischer U. Identification of a PRPF4 loss-of-function variant that abrogates U4/U6.U5 tri-snRNP integration and is associated with retinitis pigmentosa. PLoS One 2014; 9:e111754. [PMID: 25383878 PMCID: PMC4226509 DOI: 10.1371/journal.pone.0111754] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 09/30/2014] [Indexed: 12/19/2022] Open
Abstract
Pre-mRNA splicing by the spliceosome is an essential step in the maturation of nearly all human mRNAs. Mutations in six spliceosomal proteins, PRPF3, PRPF4, PRPF6, PRPF8, PRPF31 and SNRNP200, cause retinitis pigmentosa (RP), a disease characterized by progressive photoreceptor degeneration. All splicing factors linked to RP are constituents of the U4/U6.U5 tri-snRNP subunit of the spliceosome, suggesting that the compromised function of this particle may lead to RP. Here, we report the identification of the p.R192H variant of the tri-snRNP factor PRPF4 in a patient with RP. The mutation affects a highly conserved arginine residue that is crucial for PRPF4 function. Introduction of a corresponding mutation into the zebrafish homolog of PRPF4 resulted in a complete loss of function in vivo. A series of biochemical experiments suggested that p.R192H disrupts the binding interface between PRPF4 and its interactor PRPF3. This interferes with the ability of PRPF4 to integrate into the tri-snRNP, as shown in a human cell line and in zebrafish embryos. These data suggest that the p.R192H variant of PRPF4 represents a functional null allele. The resulting haploinsufficiency of PRPF4 compromises the function of the tri-snRNP, reinforcing the notion that this spliceosomal particle is of crucial importance in the physiology of the retina.
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Affiliation(s)
- Bastian Linder
- Department of Biochemistry, University of Würzburg, Würzburg, Germany
| | - Anja Hirmer
- Department of Biochemistry, University of Würzburg, Würzburg, Germany
| | - Andreas Gal
- Department of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Klaus Rüther
- Department of Ophthalmology, Sankt Gertrauden-Krankenhaus, Berlin, Germany
| | - Hanno Jörn Bolz
- Institute of Human Genetics, University Hospital of Cologne, Cologne, Germany
- Bioscientia Center for Human Genetics, Ingelheim, Germany
| | - Christoph Winkler
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | | | - Utz Fischer
- Department of Biochemistry, University of Würzburg, Würzburg, Germany
- * E-mail:
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78
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Benaglio P, San Jose PF, Avila-Fernandez A, Ascari G, Harper S, Manes G, Ayuso C, Hamel C, Berson EL, Rivolta C. Mutational screening of splicing factor genes in cases with autosomal dominant retinitis pigmentosa. Mol Vis 2014; 20:843-51. [PMID: 24959063 PMCID: PMC4063357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 06/16/2014] [Indexed: 11/04/2022] Open
Abstract
PURPOSE Mutations in genes encoding proteins from the tri-snRNP complex of the spliceosome account for more than 12% of cases of autosomal dominant retinitis pigmentosa (adRP). Although the exact mechanism by which splicing factor defects trigger photoreceptor death is not completely clear, their role in retinitis pigmentosa has been demonstrated by several genetic and functional studies. To test for possible novel associations between splicing factors and adRP, we screened four tri-snRNP splicing factor genes (EFTUD2, PRPF4, NHP2L1, and AAR2) as candidate disease genes. METHODS We screened up to 303 patients with adRP from Europe and North America who did not carry known RP mutations. Exon-PCR and Sanger methods were used to sequence the NHP2L1 and AAR2 genes, while the sequences of EFTUD2 and PRPF4 were obtained by using long-range PCRs spanning coding and non-coding regions followed by next-generation sequencing. RESULTS We detected novel missense changes in individual patients in the sequence of the genes PRPF4 and EFTUD2, but the role of these changes in relationship to disease could not be verified. In one other patient we identified a novel nucleotide substitution in the 5' untranslated region (UTR) of NHP2L1, which did not segregate with the disease in the family. CONCLUSIONS The absence of clearly pathogenic mutations in the candidate genes screened in our cohort suggests that EFTUD2, PRPF4, NHP2L1, and AAR2 are either not involved in adRP or are associated with the disease in rare instances, at least as observed in this study in patients of European and North American origin.
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Affiliation(s)
- Paola Benaglio
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
| | - Patricia Fernandez San Jose
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital (IIS-FJD, UAM), Madrid, Spain,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Almudena Avila-Fernandez
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital (IIS-FJD, UAM), Madrid, Spain,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Giulia Ascari
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
| | - Shyana Harper
- The Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA
| | - Gaël Manes
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, Montpellier, France
| | - Carmen Ayuso
- Department of Genetics, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital (IIS-FJD, UAM), Madrid, Spain,Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, Madrid, Spain
| | - Christian Hamel
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, Montpellier, France
| | - Eliot L. Berson
- The Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA
| | - Carlo Rivolta
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
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79
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Pan X, Chen X, Liu X, Gao X, Kang X, Xu Q, Chen X, Zhao K, Zhang X, Chu Q, Wang X, Zhao C. Mutation analysis of pre-mRNA splicing genes in Chinese families with retinitis pigmentosa. Mol Vis 2014; 20:770-9. [PMID: 24940031 PMCID: PMC4043610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 05/30/2014] [Indexed: 10/24/2022] Open
Abstract
PURPOSE Seven genes involved in precursor mRNA (pre-mRNA) splicing have been implicated in autosomal dominant retinitis pigmentosa (adRP). We sought to detect mutations in all seven genes in Chinese families with RP, to characterize the relevant phenotypes, and to evaluate the prevalence of mutations in splicing genes in patients with adRP. METHODS Six unrelated families from our adRP cohort (42 families) and two additional families with RP with uncertain inheritance mode were clinically characterized in the present study. Targeted sequence capture with next-generation massively parallel sequencing (NGS) was performed to screen mutations in 189 genes including all seven pre-mRNA splicing genes associated with adRP. Variants detected with NGS were filtered with bioinformatics analyses, validated with Sanger sequencing, and prioritized with pathogenicity analysis. RESULTS Mutations in pre-mRNA splicing genes were identified in three individual families including one novel frameshift mutation in PRPF31 (p.Leu366fs*1) and two known mutations in SNRNP200 (p.Arg681His and p.Ser1087Leu). The patients carrying SNRNP200 p.R681H showed rapid disease progression, and the family carrying p.S1087L presented earlier onset ages and more severe phenotypes compared to another previously reported family with p.S1087L. In five other families, we identified mutations in other RP-related genes, including RP1 p. Ser781* (novel), RP2 p.Gln65* (novel) and p.Ile137del (novel), IMPDH1 p.Asp311Asn (recurrent), and RHO p.Pro347Leu (recurrent). CONCLUSIONS Mutations in splicing genes identified in the present and our previous study account for 9.5% in our adRP cohort, indicating the important role of pre-mRNA splicing deficiency in the etiology of adRP. Mutations in the same splicing gene, or even the same mutation, could correlate with different phenotypic severities, complicating the genotype-phenotype correlation and clinical prognosis.
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Affiliation(s)
- Xinyuan Pan
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xue Chen
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiaoxing Liu
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xiang Gao
- Department of Ophthalmology, Jiaozuo Health College, Henan, China
| | - Xiaoli Kang
- Department of Ophthalmology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qihua Xu
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Xuejuan Chen
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Kanxing Zhao
- Tianjin Medical University, Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin, China
| | - Xiumei Zhang
- Department of Ophthalmology, Jiaozuo Health College, Henan, China
| | - Qiaomei Chu
- Department of Ophthalmology, Liqun Hospital, Shanghai, China
| | - Xiuying Wang
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
| | - Chen Zhao
- Department of Ophthalmology of the First Affiliated Hospital and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, China
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80
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Abstract
This review summarizes the current understanding of the role of nuclear bodies in regulating gene expression. The compartmentalization of cellular processes, such as ribosome biogenesis, RNA processing, cellular response to stress, transcription, modification and assembly of spliceosomal snRNPs, histone gene synthesis and nuclear RNA retention, has significant implications for gene regulation. These functional nuclear domains include the nucleolus, nuclear speckle, nuclear stress body, transcription factory, Cajal body, Gemini of Cajal body, histone locus body and paraspeckle. We herein review the roles of nuclear bodies in regulating gene expression and their relation to human health and disease.
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Affiliation(s)
| | - Cornelius F. Boerkoel
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-604-875-2157; Fax: +1-604-875-2376
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81
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Nancollis V, Ruckshanthi JPD, Frazer LN, O'Keefe RT. The U5 snRNA internal loop 1 is a platform for Brr2, Snu114 and Prp8 protein binding during U5 snRNP assembly. J Cell Biochem 2014; 114:2770-84. [PMID: 23857713 PMCID: PMC4065371 DOI: 10.1002/jcb.24625] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 06/26/2013] [Indexed: 12/25/2022]
Abstract
The U5 small nuclear ribonucleoprotein particle (snRNP) forms the heart of the spliceosome which is required for intron removal from pre-mRNA. The proteins Prp8, Snu114 and Brr2 all assemble with the U5 small nuclear RNA (snRNA) to produce the U5 snRNP. Successful assembly of the U5 snRNP, then incorporation of this snRNP into the U4/U6.U5 tri-snRNP and the spliceosome, is essential for producing an active spliceosome. We have investigated the requirements for Prp8, Snu114 and Brr2 association with the U5 snRNA to form the U5 snRNP in yeast. Mutations were constructed in the highly conserved loop 1 and internal loop 1 (IL1) of the U5 snRNA and their function assessed in vivo. The influence of these U5 mutations on association of Prp8, Snu114 and Brr2 with the U5 snRNA were then determined. U5 snRNA loop 1 and both sides of IL1 in U5 were important for association of Prp8, Snu114 and Brr2 with the U5 snRNA. Mutations in the 3′ side of U5 IL1 resulted in the greatest reduction of Prp8, Snu114 and Brr2 association with the U5 snRNA. Genetic screening of brr2 and U5 snRNA mutants revealed synthetic lethal interactions between alleles in Brr2 and the 3′ side of U5 snRNA IL1 which reflects reduced association between Brr2 and U5 IL1. We propose that the U5 snRNA IL1 is a platform for protein binding and is required for Prp8, Brr2 and Snu114 association with the U5 snRNA to form the U5 snRNP. J. Cell. Biochem. 114: 2770–2784, 2013. © 2013 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals Inc.
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Affiliation(s)
- Verity Nancollis
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester, M13 9PT, United Kingdom
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82
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Ajmal M, Khan MI, Neveling K, Khan YM, Azam M, Waheed NK, Hamel CP, Ben-Yosef T, De Baere E, Koenekoop RK, Collin RWJ, Qamar R, Cremers FPM. A missense mutation in the splicing factor gene DHX38 is associated with early-onset retinitis pigmentosa with macular coloboma. J Med Genet 2014; 51:444-8. [PMID: 24737827 DOI: 10.1136/jmedgenet-2014-102316] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Retinitis pigmentosa (RP) is the most frequent inherited retinal disease, which shows a relatively high incidence of the autosomal-recessive form in Pakistan. METHODS Genome-wide high-density single-nucleotide polymorphism (SNP) microarrays were used to identify homozygous regions shared by affected individuals of one consanguineous family. DNA of three affected and two healthy siblings was used for SNP genotyping. Genotyping data were then analysed by Homozygosity Mapper. DNA of the proband was further analysed employing exome sequencing. RESULTS Homozygosity mapping revealed a single homozygous region on chromosome 16, shared by three affected individuals. Subsequent exome sequencing identified a novel missense mutation, c.995G>A; p.(Gly332Asp), in DHX38. This mutation was found to be present in a homozygous state in four affected individuals while two healthy siblings and the parents of the affected persons were heterozygous for this mutation. This variant thereby yields a logarithm of the odds (LOD) score of 3.25, which is highly suggestive for linkage. This variant was neither detected in 180 ethnically matched control individuals, nor in 7540 Africans or Caucasians and an in-house database that contained the exome data of 400 individuals. CONCLUSIONS By combining genome-wide homozygosity mapping and exome sequencing, a novel missense mutation was identified in the DHX38 gene that encodes the pre-mRNA splicing factor PRP16, in a Pakistani family with early-onset autosomal-recessive RP. The phenotype is different from those associated with other retinal pre-mRNA splicing factors and DHX38 is the first pre-mRNA splicing gene that is putatively associated with autosomal-recessive inherited RP.
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Affiliation(s)
- Muhammad Ajmal
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Muhammad Imran Khan
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Kornelia Neveling
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Yar Muhammad Khan
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Department of Chemistry, University of Science and Technology, Bannu, Pakistan
| | - Maleeha Azam
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Christian P Hamel
- Department of Genetics, Institut National de la Santé et de la Recherche Médicale U, Université Paris Descartes-Sorbonne Paris Cité, Montpellier, France
| | - Tamar Ben-Yosef
- Department of Genetics, The Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Elfride De Baere
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium
| | - Robert K Koenekoop
- Department of Paediatric Surgery, Human Genetics and Ophthalmology, McGill University Health Centre, Montreal, Canada
| | - Rob W J Collin
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Raheel Qamar
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Al-Nafees Medical College & Hospital, Isra University, Islamabad, Pakistan
| | - Frans P M Cremers
- Faculty of Science, Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands Radboud Institute for Molecular Life Sciences, Radboud University Nijmegen, Nijmegen, The Netherlands
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83
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Cauchi RJ. Gem depletion: amyotrophic lateral sclerosis and spinal muscular atrophy crossover. CNS Neurosci Ther 2014; 20:574-81. [PMID: 24645792 DOI: 10.1111/cns.12242] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 01/25/2014] [Accepted: 01/27/2014] [Indexed: 12/22/2022] Open
Abstract
The determining factor of spinal muscular atrophy (SMA), the most common motor neuron degenerative disease of childhood, is the survival motor neuron (SMN) protein. SMN and its Gemin associates form a complex that is indispensible for the biogenesis of small nuclear ribonucleoproteins (snRNPs), which constitute the building blocks of spliceosomes. It is as yet unclear whether a decreased capacity of SMN in snRNP assembly, and, hence, transcriptome abnormalities, account for the specific neuromuscular phenotype in SMA. Across metazoa, the SMN-Gemins complex concentrates in multiple nuclear gems that frequently neighbour or overlap Cajal bodies. The number of gems has long been known to be a faithful indicator of SMN levels, which are linked to SMA severity. Intriguingly, a flurry of recent studies have revealed that depletion of this nuclear structure is also a signature feature of amyotrophic lateral sclerosis (ALS), the most common adult-onset motor neuron disease. This review discusses such a surprising crossover in addition to highlighting the most recent work on the intricate world of spliceosome building, which seems to be at the heart of motor neuron physiology and survival.
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Affiliation(s)
- Ruben J Cauchi
- Department of Physiology and Biochemistry, University of Malta, Msida 2080, Malta
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84
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Chen X, Liu Y, Sheng X, Tam POS, Zhao K, Chen X, Rong W, Liu Y, Liu X, Pan X, Chen LJ, Zhao Q, Vollrath D, Pang CP, Zhao C. PRPF4 mutations cause autosomal dominant retinitis pigmentosa. Hum Mol Genet 2014; 23:2926-39. [PMID: 24419317 DOI: 10.1093/hmg/ddu005] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retinitis pigmentosa (RP), a disease characterized by progressive loss of photoreceptors, exhibits significant genetic heterogeneity. Several genes associated with U4/U6-U5 triple small nuclear ribonucleoprotein (tri-snRNP) complex of the spliceosome have been implicated in autosomal dominant RP (adRP). HPrp4, encoded by PRPF4, regulates the stability of U4/U6 di-snRNP, which is essential for continuous splicing. Here, we identified two heterozygous variants in PRPF4, including c.-114_-97del in a simplex RP patient and c.C944T (p.Pro315Leu), which co-segregates with disease phenotype in a family with adRP. Both variants were absent in 400 unrelated controls. The c.-114_-97del, predicted to affect two transcription factor binding sites, was shown to down-regulate the promoter activity of PRPF4 by a luciferase assay, and was associated with a significant reduction of PRPF4 expression in the blood cells of the patient. In fibroblasts from an affected individual with the p.Pro315Leu variant, the expression levels of several tri-snRNP components, including PRPF4 itself, were up-regulated, with altered expression pattern of SC35, a spliceosome marker. The same alterations were also observed in cells over expressing hPrp4(Pro315Leu), suggesting that they arose as a compensatory response to a compromised splicing mechanism caused by hPrp4 dysfunction. Further, over expression of hPrp4(Pro315Leu), but not hPrp4(WT), triggered systemic deformities in wild-type zebrafish embryos with the retina primarily affected, and dramatically augmented death rates in morphant embryos, in which orthologous zebrafish prpf4 gene was silenced. We conclude that mutations of PRPF4 cause RP via haploinsufficiency and dominant-negative effects, and establish PRPF4 as a new U4/U6-U5 snRNP component associated with adRP.
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Affiliation(s)
- Xue Chen
- Department of Ophthalmology, The First Affiliated Hospital of Nanjing Medical University and State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, China
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85
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Evolutionary conservation and expression of human RNA-binding proteins and their role in human genetic disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:1-55. [PMID: 25201102 DOI: 10.1007/978-1-4939-1221-6_1] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
RNA-binding proteins (RBPs) are effectors and regulators of posttranscriptional gene regulation (PTGR). RBPs regulate stability, maturation, and turnover of all RNAs, often binding thousands of targets at many sites. The importance of RBPs is underscored by their dysregulation or mutations causing a variety of developmental and neurological diseases. This chapter globally discusses human RBPs and provides a brief introduction to their identification and RNA targets. We review RBPs based on common structural RNA-binding domains, study their evolutionary conservation and expression, and summarize disease associations of different RBP classes.
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86
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Cvačková Z, Matějů D, Staněk D. Retinitis Pigmentosa Mutations ofSNRNP200Enhance Cryptic Splice-Site Recognition. Hum Mutat 2013; 35:308-17. [DOI: 10.1002/humu.22481] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 11/05/2013] [Indexed: 12/16/2022]
Affiliation(s)
- Zuzana Cvačková
- Laboratory of RNA Biology; Institute of Molecular Genetics ASCR; Prague 142 20 Czech Republic
| | - Daniel Matějů
- Laboratory of RNA Biology; Institute of Molecular Genetics ASCR; Prague 142 20 Czech Republic
| | - David Staněk
- Laboratory of RNA Biology; Institute of Molecular Genetics ASCR; Prague 142 20 Czech Republic
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87
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Bowne SJ, Sullivan LS, Avery CE, Sasser EM, Roorda A, Duncan JL, Wheaton DH, Birch DG, Branham KE, Heckenlively JR, Sieving PA, Daiger SP. Mutations in the small nuclear riboprotein 200 kDa gene (SNRNP200) cause 1.6% of autosomal dominant retinitis pigmentosa. Mol Vis 2013; 19:2407-17. [PMID: 24319334 PMCID: PMC3850977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 11/22/2013] [Indexed: 12/02/2022] Open
Abstract
PURPOSE The purpose of this project was to determine the spectrum and frequency of mutations in the small nuclear riboprotein 200 kDa gene (SNRNP200) that cause autosomal dominant retinitis pigmentosa (adRP). METHODS A well-characterized adRP cohort of 251 families was tested for mutations in the exons and intron/exon junctions of SNRNP200 using fluorescent dideoxy sequencing. An additional 21 adRP families from the eyeGENE® Network were tested for possible mutations. Bioinformatic and segregation analysis was performed on novel variants. RESULTS SNRNP200 mutations were identified in seven of the families tested. Two previously reported mutations, p.Arg681Cys and p.Ser1087Leu, were found in two families each. One family had the previously reported p.Arg681His mutation. Two novel SNRNP200 variants, p.Pro682Ser and p.Ala542Val, were also identified in one family each. Bioinformatic and segregation analyses suggested that these novel variants are likely to be pathogenic. Clinical examination of patients with SNRNP200 mutations showed a wide range of clinical symptoms and severity, including one instance of non-penetrance. CONCLUSIONS Mutations in SNRNP200 caused 1.6% of disease in our adRP cohort. Pathogenic mutations were found primarily in exons 16 and 25, but the novel p.Ala542Val mutation in exon 13 suggests that variation in other genetic regions is also responsible for causing dominant disease. SNRNP200 mutations were associated with a wide range of clinical symptoms similar to those of individuals with other splice-factor gene mutations.
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Affiliation(s)
- Sara J. Bowne
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center Houston, TX
| | - Lori S. Sullivan
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center Houston, TX
| | - Cheryl E. Avery
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center Houston, TX
| | - Elizabeth M. Sasser
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center Houston, TX
| | - Austin Roorda
- School of Optometry and Vision Sciences Graduate Group, University of California, Berkeley, CA
| | - Jacque L. Duncan
- Department of Ophthalmology, University of California, San Francisco, CA
| | | | | | | | | | - Paul A. Sieving
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Stephen P. Daiger
- Human Genetics Center, School of Public Health, The University of Texas Health Science Center Houston, TX
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88
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Rose AM, Shah AZ, Venturini G, Rivolta C, Rose GE, Bhattacharya SS. Dominant PRPF31 mutations are hypostatic to a recessive CNOT3 polymorphism in retinitis pigmentosa: a novel phenomenon of "linked trans-acting epistasis". Ann Hum Genet 2013; 78:62-71. [PMID: 24116917 PMCID: PMC4240469 DOI: 10.1111/ahg.12042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 09/01/2013] [Indexed: 12/31/2022]
Abstract
Mutations in PRPF31 are responsible for autosomal dominant retinitis pigmentosa (adRP, RP11 form) and affected families show nonpenetrance. Differential expression of the wildtype PRPF31 allele is responsible for this phenomenon: coinheritance of a mutation and a higher expressing wildtype allele provide protection against development of disease. It has been suggested that a major modulating factor lies in close proximity to the wildtype PRPF31 gene on Chromosome 19, implying that a cis-acting factor directly alters PRPF31 expression. Variable expression of CNOT3 is one determinant of PRPF31 expression. This study explored the relationship between CNOT3 (a trans-acting factor) and its paradoxical cis-acting nature in relation to RP11. Linkage analysis on Chromosome 19 was performed in mutation-carrying families, and the inheritance of the wildtype PRPF31 allele in symptomatic–asymptomatic sibships was assessed—confirming that differential inheritance of wildtype chromosome 19q13 determines the clinical phenotype (P < 2.6 × 10−7). A theoretical model was constructed that explains the apparent conflict between the linkage data and the recent demonstration that a trans-acting factor (CNOT3) is a major nonpenetrance factor: we propose that this apparently cis-acting effect arises due to the intimate linkage of CNOT3 and PRPF31 on Chromosome 19q13—a novel mechanism that we have termed “linked trans-acting epistasis.”
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Affiliation(s)
- Anna M Rose
- Department of Genetics, UCL Institute of Ophthalmology, London, United Kingdom
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89
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Zhang X, Lai TYY, Chiang SWY, Tam POS, Liu DTL, Chan CKM, Pang CP, Zhao C, Chen LJ. Contribution of SNRNP200 sequence variations to retinitis pigmentosa. Eye (Lond) 2013; 27:1204-13. [PMID: 23887765 DOI: 10.1038/eye.2013.137] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 05/21/2013] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Mutations in the SNRNP200 gene have been reported to cause autosomal dominant retinitis pigmentosa (adRP). In this study, we evaluate the mutation profile of SNRNP200 in a cohort of southern Chinese RP patients. METHODS Twenty adRP patients from 11 families and 165 index patients with non-syndromic RP with mixed inheritance patterns were screened for mutations in the mutation hotspots of SNRNP200. These included exons 12-16, 22-32, and 38-45, which covered the two helicase ATP-binding domains in DEAD-box and two sec-63 domains. The targeted regions were amplified by polymerase chain reaction and analyzed by direct DNA sequencing, followed by in silico analyses. RESULTS Totally 26 variants were identified, 18 of which were novel. Three non-synonymous variants (p.C502R, p.R1779H and p.I698V) were found exclusively in patients. Two of them, p.C502R and p.R1779H, were each identified in one simplex RP patient, whereas p.I698V occurred in one patient with unknown inheritance pattern. All three residues are highly conserved in SNRNP200 orthologs. Nevertheless, only p.C502R and p.R1779H were predicted to affect protein function by in silico analyses, suggesting these two variants are likely to be disease-causing mutations. Notably, all mutations previously identified in other study populations were not detected in this study. CONCLUSIONS Our results reveal a distinct mutation profile of the SNRNP200 gene in a southern Chinese cohort of RP patients. The identification of two novel candidate mutations in two respective patients affirmed that SNRNP200 contributes to a proportion of overall RP.
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Affiliation(s)
- X Zhang
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
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90
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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: 409] [Impact Index Per Article: 37.2] [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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91
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Liu MM, Zack DJ. Alternative splicing and retinal degeneration. Clin Genet 2013; 84:142-9. [PMID: 23647439 DOI: 10.1111/cge.12181] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/30/2013] [Accepted: 04/30/2013] [Indexed: 12/27/2022]
Abstract
Alternative splicing is highly regulated in tissue-specific and development-specific patterns, and it has been estimated that 15% of disease-causing point mutations affect pre-mRNA splicing. In this review, we consider the cis-acting splice site and trans-acting splicing factor mutations that affect pre-mRNA splicing and contribute to retinal degeneration. Numerous splice site mutations have been identified in retinitis pigmentosa (RP) and various cone-rod dystrophies. Mutations in alternatively spliced retina-specific exons of the widely expressed RPGR and COL2A1 genes lead primarily to X-linked RP and ocular variants of Stickler syndrome, respectively. Furthermore, mutations in general pre-mRNA splicing factors, such as PRPF31, PRPF8, and PRPF3, predominantly cause autosomal dominant RP. These findings suggest an important role for pre-mRNA splicing in retinal homeostasis and the pathogenesis of retinal degenerative diseases. The development of novel therapeutic strategies to modulate aberrant splicing, including small molecule-based therapies, has the potential to lead to new treatments for retinal degenerative diseases.
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Affiliation(s)
- M M Liu
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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92
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Ehsani A, Alluin JV, Rossi JJ. Cell cycle abnormalities associated with differential perturbations of the human U5 snRNP associated U5-200kD RNA helicase. PLoS One 2013; 8:e62125. [PMID: 23637979 PMCID: PMC3639242 DOI: 10.1371/journal.pone.0062125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 03/19/2013] [Indexed: 12/04/2022] Open
Abstract
Splicing of pre-messenger RNAs into functional messages requires a concerted assembly of proteins and small RNAs that identify the splice junctions and facilitate cleavage of exon-intron boundaries and ligation of exons. One of the key steps in the splicing reaction is the recruitment of a tri-snRNP harboring the U5/U4/U6 snRNPs. The U5 snRNP is also required for both steps of splicing and exon-exon joining. One of the key components of the tri-snRNP is the U5 200kd helicase. The human U5-200kD gene isolated from Hela cells encodes a 200 kDa protein with putative RNA helicase function. Surprisingly, little is known about the functional role of this protein in humans. Therefore, we have investigated the role of the U5-200kD RNA helicase in mammalian cell culture. We created and expressed a dominant negative domain I mutant of the RNA helicase in HEK293 cells and used RNAi to downregulate expression of the endogenous protein. Transient and stable expression of the domain I mutant U5-200kD protein using an ecdysone-inducible system and transient expression of an anti-U5-200kD short hairpin RNA (shRNA) resulted in differential splicing and growth defects in the 293/EcR cells. Cell cycle analysis of the dominant negative clones revealed delayed exit from the G2/M phase of the cell cycle due to a mild splicing defect. In contrast to the domain I dominant negative mutant expressing cells, transient expression of an anti-U5-200kD shRNA resulted in a pronounced S phase arrest and a minute splicing defect. Collectively, this work demonstrates for the first time establishment of differential human cell culture splicing and cell cycle defect models due to perturbed levels of an essential core splicing factor.
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Affiliation(s)
- Ali Ehsani
- Department of Molecular and Cellular Biology, and Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - Jessica V. Alluin
- Department of Molecular and Cellular Biology, and Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
| | - John J. Rossi
- Department of Molecular and Cellular Biology, and Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, California, United States of America
- * E-mail:
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93
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Panel-based next generation sequencing as a reliable and efficient technique to detect mutations in unselected patients with retinal dystrophies. Eur J Hum Genet 2013; 22:99-104. [PMID: 23591405 DOI: 10.1038/ejhg.2013.72] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/05/2013] [Accepted: 03/15/2013] [Indexed: 11/08/2022] Open
Abstract
Hereditary retinal dystrophies (RD) constitute a group of blinding diseases that are characterized by clinical variability and pronounced genetic heterogeneity. The different forms of RD can be caused by mutations in >100 genes, including >1600 exons. Consequently, next generation sequencing (NGS) technologies are among the most promising approaches to identify mutations in RD. So far, NGS is not routinely used in gene diagnostics. We developed a diagnostic NGS pipeline to identify mutations in 170 genetically and clinically unselected RD patients. NGS was applied to 105 RD-associated genes. Underrepresented regions were examined by Sanger sequencing. The NGS approach was successfully established using cases with known sequence alterations. Depending on the initial clinical diagnosis, we identified likely causative mutations in 55% of retinitis pigmentosa and 80% of Bardet-Biedl or Usher syndrome cases. Seventy-one novel mutations in 40 genes were newly associated with RD. The genes USH2A, EYS, ABCA4, and RHO were more frequently affected than others. Occasionally, cases carried mutations in more than one RD-associated gene. In addition, we found possible dominant de-novo mutations in cases with sporadic RD, which implies consequences for counseling of patients and families. NGS-based mutation analyses are reliable and cost-efficient approaches in gene diagnostics of genetically heterogeneous diseases like RD.
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94
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Utz VM, Beight CD, Marino MJ, Hagstrom SA, Traboulsi EI. Autosomal dominant retinitis pigmentosa secondary to pre-mRNA splicing-factor gene PRPF31 (RP11): review of disease mechanism and report of a family with a novel 3-base pair insertion. Ophthalmic Genet 2013; 34:183-8. [PMID: 23343310 DOI: 10.3109/13816810.2012.762932] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Several forms of autosomal dominant retinitis pigmentosa (adRP) are caused by mutations in genes encoding proteins that are ubiquitously expressed and involved in the pre-mRNA spliceosome such as PRPF31. This paper provides an overview of the molecular genetics, pathophysiology, and mechanism for incomplete penetrance and retina-specific disease in pedigrees of families who harbor mutations in PRPF31 (RP11). The molecular and clinical features of a family with a novel 3-base insertion, c.914_915insTGT (p.Val305_Asp306insVal) in exon 9 of PRPF31 are described to illustrate the salient clinical features of mutations in this gene.
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Affiliation(s)
- Virginia M Utz
- Cole Eye Institute, Cleveland Clinic , Cleveland, OH , USA , and
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95
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Nielsen KH, Staley JP. Spliceosome activation: U4 is the path, stem I is the goal, and Prp8 is the keeper. Let's cheer for the ATPase Brr2! Genes Dev 2013; 26:2461-7. [PMID: 23154979 DOI: 10.1101/gad.207514.112] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
During pre-mRNA splicing, the spliceosome is activated for catalysis by unwinding base-paired U4/U6 small nuclear RNAs, a step that must be precisely timed. We know that unwinding requires the ATPase Brr2, but the mechanism and regulation of unwinding have been understood poorly. In the November 1, 2012, issue of Genes & Development, Hahn and colleagues (pp. 2408-2421) and Mozaffari-Jovin and colleagues (pp. 2422-2434) defined a pathway for U4/U6 unwinding. Moreover, Mozaffari-Jovin and colleagues suggested a mechanism for regulating Brr2.
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Affiliation(s)
- Klaus H Nielsen
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA
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96
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Pasternack SM, Refke M, Paknia E, Hennies HC, Franz T, Schäfer N, Fryer A, van Steensel M, Sweeney E, Just M, Grimm C, Kruse R, Ferrándiz C, Nöthen MM, Fischer U, Betz RC. Mutations in SNRPE, which encodes a core protein of the spliceosome, cause autosomal-dominant hypotrichosis simplex. Am J Hum Genet 2013; 92:81-7. [PMID: 23246290 DOI: 10.1016/j.ajhg.2012.10.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/05/2012] [Accepted: 10/29/2012] [Indexed: 11/16/2022] Open
Abstract
Hypotrichosis simplex (HS) comprises a group of hereditary isolated alopecias that are characterized by a diffuse and progressive loss of hair starting in childhood and shows a wide phenotypic variability. We mapped an autosomal-dominant form of HS to chromosome 1q31.3-1q41 in a Spanish family. By direct sequencing, we identified the heterozygous mutation c.1A>G (p.Met1?) in SNRPE that results in loss of the start codon of the transcript. We identified the same mutation in a simplex HS case from the UK and an additional mutation (c.133G>A [p.Gly45Ser]) in a simplex HS case originating from Tunisia. SNRPE encodes a core protein of U snRNPs, the key factors of the pre-mRNA processing spliceosome. The missense mutation c.133G>A leads to a glycine to serine substitution and is predicted to disrupt the structure of SNRPE. Western blot analyses of HEK293T cells expressing SNRPE c.1A>G revealed an N-terminally truncated protein, and therefore the mutation might result in use of an alternative in-frame downstream start codon. Subcellular localization of mutant SNRPE by immunofluorescence analyses as well as incorporation of mutant SNRPE proteins into U snRNPs was found to be normal, suggesting that the function of U snRNPs in splicing, rather than their biogenesis, is affected. In this report we link a core component of the spliceosome to hair loss, thus adding another specific factor in the complexity of hair growth. Furthermore, our findings extend the range of human phenotypes that are linked to the splicing machinery.
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Abstract
In eukaryotic cells, introns are spliced from pre-mRNAs by the spliceosome. Both the composition and the structure of the spliceosome are highly dynamic, and eight DExD/H RNA helicases play essential roles in controlling conformational rearrangements. There is evidence that the various helicases are functionally and physically connected with each other and with many other factors in the spliceosome. Understanding the dynamics of those interactions is essential to comprehend the mechanism and regulation of normal as well as of pathological splicing. This review focuses on recent advances in the characterization of the splicing helicases and their interactions, and highlights the deep integration of splicing helicases in global mRNP biogenesis pathways.
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Affiliation(s)
- Olivier Cordin
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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99
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Structural basis for functional cooperation between tandem helicase cassettes in Brr2-mediated remodeling of the spliceosome. Proc Natl Acad Sci U S A 2012; 109:17418-23. [PMID: 23045696 DOI: 10.1073/pnas.1208098109] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Assembly of a spliceosome, catalyzing precursor-messenger RNA splicing, involves multiple RNA-protein remodeling steps, driven by eight conserved DEXD/H-box RNA helicases. The 250-kDa Brr2 enzyme, which is essential for U4/U6 di-small nuclear ribonucleoprotein disruption during spliceosome catalytic activation and for spliceosome disassembly, is the only member of this group that is permanently associated with the spliceosome, thus requiring its faithful regulation. At the same time, Brr2 represents a unique subclass of superfamily 2 nucleic acid helicases, containing tandem helicase cassettes. Presently, the mechanistic and regulatory consequences of this unconventional architecture are unknown. Here we show that in human Brr2, two ring-like helicase cassettes intimately interact and functionally cooperate and how retinitis pigmentosa-linked Brr2 mutations interfere with the enzyme's function. Only the N-terminal cassette harbors ATPase and helicase activities in isolation. Comparison with other helicases and mutational analyses show how it threads single-stranded RNA, and structural features suggest how it can load onto an internal region of U4/U6 di-snRNA. Although the C-terminal cassette does not seem to engage RNA in the same fashion, it binds ATP and strongly stimulates the N-terminal helicase. Mutations at the cassette interface, in an intercassette linker or in the C-terminal ATP pocket, affect this cross-talk in diverse ways. Together, our results reveal the structural and functional interplay between two helicase cassettes in a tandem superfamily 2 enzyme and point to several sites through which Brr2 activity may be regulated.
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100
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Liu T, Jin X, Zhang X, Yuan H, Cheng J, Lee J, Zhang B, Zhang M, Wu J, Wang L, Tian G, Wang W. A novel missense SNRNP200 mutation associated with autosomal dominant retinitis pigmentosa in a Chinese family. PLoS One 2012; 7:e45464. [PMID: 23029027 PMCID: PMC3446876 DOI: 10.1371/journal.pone.0045464] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 08/22/2012] [Indexed: 11/18/2022] Open
Abstract
The SNRNP200 gene encodes hBrr2, a helicase essential for pre-mRNA splicing. Six mutations in SNRNP200 have recently been discovered to be associated with autosomal dominant retinitis pigmentosa (adRP). In this work, we analyzed a Chinese family with adRP and identified a novel missense mutation in SNRNP200. To identify the genetic defect in this family, exome of the proband was captured and sequencing analysis was performed to exclude known genetic defects and find possible pathogenic mutations. Subsequently, candidate mutations were validated in affected family members using Sanger sequencing. A novel missense mutation, c.2653C>G transition (p.Q885E), in exon 20 of SNRNP200 was identified. The mutation co-segregated with the disease phenotype over four generations and was absent in 100 normal unaffected individuals. This mutation occurs at highly conserved position in hBrr2 and is predicted to have a functional impact, suggesting that hBrr2-dependent small nuclear riboproteins (snRNPs) unwinding and spliceosome activation is important in the pathogenesis of some variants of RP.
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Affiliation(s)
- Tiecheng Liu
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
- Department of Ophthalmology, Hainan Branch of Chinese PLA General Hospital, Sanya, China
| | - Xin Jin
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
| | - Xuemin Zhang
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
| | - Huijun Yuan
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Jing Cheng
- Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Janet Lee
- Department of Ophthalmology and Shiley Eye Center, University of California San Diego, La Jolla, California, United States of America
| | - Baoquan Zhang
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
| | - Maonian Zhang
- Department of Ophthalmology, Chinese PLA General Hospital, Beijing, China
| | - Jing Wu
- Department of Science and Technology, BGI-Tianjin, Tianjin, China
| | - Lijuan Wang
- Department of Reproductive Health, BGI-Shenzhen, Shenzhen, China
| | - Geng Tian
- Department of Science and Technology, BGI-Tianjin, Tianjin, China
| | - Weifeng Wang
- Department of Gastroenterology and Hepatology, Hainan Branch of Chinese PLA General Hospital, Sanya, China
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