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Concepcion F, Chen J. Q344ter mutation causes mislocalization of rhodopsin molecules that are catalytically active: a mouse model of Q344ter-induced retinal degeneration. PLoS One 2010; 5:e10904. [PMID: 20532191 PMCID: PMC2880002 DOI: 10.1371/journal.pone.0010904] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Accepted: 04/22/2010] [Indexed: 11/29/2022] Open
Abstract
Q344ter is a naturally occurring rhodopsin mutation in humans that causes autosomal dominant retinal degeneration through mechanisms that are not fully understood, but are thought to involve an early termination that removed the trafficking signal, QVAPA, leading to its mislocalization in the rod photoreceptor cell. To better understand the disease mechanism(s), transgenic mice that express Q344ter were generated and crossed with rhodopsin knockout mice. Dark-reared Q344ter(rho+/-) mice exhibited retinal degeneration, demonstrating that rhodopsin mislocalization caused photoreceptor cell death. This degeneration is exacerbated by light-exposure and is correlated with the activation of transducin as well as other G-protein signaling pathways. We observed numerous sub-micrometer sized vesicles in the inter-photoreceptor space of Q344ter(rho+/-) and Q344ter(rho-/-) retinas, similar to that seen in another rhodopsin mutant, P347S. Whereas light microscopy failed to reveal outer segment structures in Q344ter(rho-/-) rods, shortened and disorganized rod outer segment structures were visible using electron microscopy. Thus, some Q344ter molecules trafficked to the outer segment and formed disc structures, albeit inefficiently, in the absence of full length wildtype rhodopsin. These findings helped to establish the in vivo role of the QVAPA domain as well as the pathways leading to Q344ter-induced retinal degeneration.
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Affiliation(s)
- Francis Concepcion
- Department of Cell and Neurobiology and Department of Ophthalmology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Jeannie Chen
- Department of Cell and Neurobiology and Department of Ophthalmology, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
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602
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Berger W, Kloeckener-Gruissem B, Neidhardt J. The molecular basis of human retinal and vitreoretinal diseases. Prog Retin Eye Res 2010; 29:335-75. [PMID: 20362068 DOI: 10.1016/j.preteyeres.2010.03.004] [Citation(s) in RCA: 404] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During the last two to three decades, a large body of work has revealed the molecular basis of many human disorders, including retinal and vitreoretinal degenerations and dysfunctions. Although belonging to the group of orphan diseases, they affect probably more than two million people worldwide. Most excitingly, treatment of a particular form of congenital retinal degeneration is now possible. A major advantage for treatment is the unique structure and accessibility of the eye and its different components, including the vitreous and retina. Knowledge of the many different eye diseases affecting retinal structure and function (night and colour blindness, retinitis pigmentosa, cone and cone rod dystrophies, photoreceptor dysfunctions, as well as vitreoretinal traits) is critical for future therapeutic development. We have attempted to present a comprehensive picture of these disorders, including biological, clinical, genetic and molecular information. The structural organization of the review leads the reader through non-syndromic and syndromic forms of (i) rod dominated diseases, (ii) cone dominated diseases, (iii) generalized retinal degenerations and (iv) vitreoretinal disorders, caused by mutations in more than 165 genes. Clinical variability and genetic heterogeneity have an important impact on genetic testing and counselling of affected families. As phenotypes do not always correlate with the respective genotypes, it is of utmost importance that clinicians, geneticists, counsellors, diagnostic laboratories and basic researchers understand the relationships between phenotypic manifestations and specific genes, as well as mutations and pathophysiologic mechanisms. We discuss future perspectives.
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Affiliation(s)
- Wolfgang Berger
- Division of Medical Molecular Genetics and Gene Diagnostics, Institute of Medical Genetics, University of Zurich, Schorenstrasse 16, CH-8603 Schwerzenbach, Switzerland.
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603
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Aldahmesh MA, Abu Safieh L, Alkuraya H, Al-Rajhi A, Shamseldin H, Hashem M, Alzahrani F, Khan AO, Alqahtani F, Rahbeeni Z, Alowain M, Khalak H, Al-Hazzaa S, Meyer BF, Alkuraya FS. Molecular characterization of retinitis pigmentosa in Saudi Arabia. Mol Vis 2009; 15:2464-9. [PMID: 19956407 PMCID: PMC2786884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Accepted: 11/18/2009] [Indexed: 12/02/2022] Open
Abstract
PURPOSE To catalog mutations that underlie retinitis pigmentosa (RP) in Saudi Arabia using a representative sample. METHODS Fifty-two patients with RP were recruited and their homozygosity mapping, with or without linkage analysis, was used to suggest the causative genes followed by bidirectional sequencing. RESULTS Mutations were identified in 94% of our study cohort, including seven that were novel. CONCLUSIONS Homozygosity mapping is an extremely robust approach in the study of retinitis pigmentosa in the setting of high rates of consanguinity. BBS3 mutations can rarely present as nonsyndromic RP.
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604
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Abstract
PURPOSE OF REVIEW To introduce the issues specific to the genetic counseling profession for genetic eye diseases. RECENT FINDINGS To discuss current issues in ocular genetic counseling including the use of a focused ophthalmology pedigree, informed consent in the blind population, genetic testing trends and psychosocial issues. SUMMARY Introduce the time-consuming issues to be addressed in genetic counseling for genetic eye disease patients.
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605
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Geller SF, Guerin KI, Visel M, Pham A, Lee ES, Dror AA, Avraham KB, Hayashi T, Ray CA, Reh TA, Bermingham-McDonogh O, Triffo WJ, Bao S, Isosomppi J, Västinsalo H, Sankila EM, Flannery JG. CLRN1 is nonessential in the mouse retina but is required for cochlear hair cell development. PLoS Genet 2009; 5:e1000607. [PMID: 19680541 PMCID: PMC2719914 DOI: 10.1371/journal.pgen.1000607] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Accepted: 07/17/2009] [Indexed: 02/02/2023] Open
Abstract
Mutations in the CLRN1 gene cause Usher syndrome type 3 (USH3), a human disease characterized by progressive blindness and deafness. Clarin 1, the protein product of CLRN1, is a four-transmembrane protein predicted to be associated with ribbon synapses of photoreceptors and cochlear hair cells, and recently demonstrated to be associated with the cytoskeleton. To study Clrn1, we created a Clrn1 knockout (KO) mouse and characterized the histological and functional consequences of Clrn1 deletion in the retina and cochlea. Clrn1 KO mice do not develop a retinal degeneration phenotype, but exhibit progressive loss of sensory hair cells in the cochlea and deterioration of the organ of Corti by 4 months. Hair cell stereocilia in KO animals were longer and disorganized by 4 months, and some Clrn1 KO mice exhibited circling behavior by 5-6 months of age. Clrn1 mRNA expression was localized in the retina using in situ hybridization (ISH), laser capture microdissection (LCM), and RT-PCR. Retinal Clrn1 transcripts were found throughout development and adulthood by RT-PCR, although expression peaked at P7 and declined to undetectable levels in adult retina by ISH. LCM localized Clrn1 transcripts to the retinas inner nuclear layer, and WT levels of retinal Clrn1 expression were observed in photoreceptor-less retinas. Examination of Clrn1 KO mice suggests that CLRN1 is unnecessary in the murine retina but essential for normal cochlear development and function. This may reflect a redundancy in the mouse retina not present in human retina. In contrast to mouse KO models of USH1 and USH2, our data indicate that Clrn1 expression in the retina is restricted to the Müller glia. This is a novel finding, as most retinal degeneration associated proteins are expressed in photoreceptors, not in glia. If CLRN1 expression in humans is comparable to the expression pattern observed in mice, this is the first report of an inner retinal protein that, when mutated, causes retinal degeneration.
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Affiliation(s)
- Scott F. Geller
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
- * E-mail: (SFG); (JGF)
| | - Karen I. Guerin
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
- Vision Science, University of California, Berkeley, California, United States of America
| | - Meike Visel
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Aaron Pham
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Edwin S. Lee
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Amiel A. Dror
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Karen B. Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Toshinori Hayashi
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Catherine A. Ray
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Thomas A. Reh
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Olivia Bermingham-McDonogh
- Department of Biological Structure, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - William J. Triffo
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Shaowen Bao
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
| | - Juha Isosomppi
- Folkhälsan Institute of Genetics, Biomedicum Helsinki and Department of Medical Genetics, University of Helsinki, Helsinki, Finland
| | - Hanna Västinsalo
- Folkhälsan Institute of Genetics, Biomedicum Helsinki and Department of Medical Genetics, University of Helsinki, Helsinki, Finland
| | - Eeva-Marja Sankila
- Folkhälsan Institute of Genetics, Biomedicum Helsinki and Department of Medical Genetics, University of Helsinki, Helsinki, Finland
- Helsinki University Eye Hospital, Helsinki, Finland
| | - John G. Flannery
- Helen Wills Neuroscience Institute, University of California, Berkeley, California, United States of America
- Vision Science, University of California, Berkeley, California, United States of America
- * E-mail: (SFG); (JGF)
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606
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Ksantini M, Sénéchal A, Humbert G, Arnaud B, Hamel CP. RRH, Encoding the RPE-Expressed Opsin-Like Peropsin, Is Not Mutated in Retinitis Pigmentosa and Allied Diseases. Ophthalmic Genet 2009; 28:31-7. [PMID: 17454745 DOI: 10.1080/13816810701202052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Many genes from retinoid metabolism cause retinitis pigmentosa. Peropsin, an opsin-like protein with unknown function, is specifically expressed in apical retinal pigment epithelium microvilli. Since rhodopsin and RGR, another opsin-like protein, cause retinitis pigmentosa, we used D-HPLC to screen for the peropsin gene RRH in 331 patients (288 with retinitis pigmentosa and 82 with other retinal dystrophies). We found 13 nonpathogenic variants only, among which a c.730_731delATinsG that truncates the last two transmembrane-spanning fragments and the Lys284 required for retinol binding, but does not segregate with the disease phenotype. We conclude that RRH is not a frequent gene in retinitis pigmentosa.
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Affiliation(s)
- Mohamed Ksantini
- INSERM, Institut des Neurosciences de Montpellier, Hôpital Saint-Eloi, Montpellier, Cedex, France
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607
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Enzmann V, Yolcu E, Kaplan HJ, Ildstad ST. Stem cells as tools in regenerative therapy for retinal degeneration. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2009; 127:563-71. [PMID: 19365041 PMCID: PMC3192438 DOI: 10.1001/archophthalmol.2009.65] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To describe the use of stem cells (SCs) for regeneration of retinal degenerations. Regenerative medicine intends to provide therapies for severe injuries or chronic diseases where endogenous repair does not sufficiently restore the tissue. Pluripotent SCs, with their capacity to give rise to specialized cells, are the most promising candidates for clinical application. Despite encouraging results, a combination with up-to-date tissue engineering might be critical for ultimate success. DESIGN The focus is on the use of SCs for regeneration of retinal degenerations. Cell populations include embryonic, neural, and bone marrow-derived SCs, and engineered grafts will also be described. RESULTS Experimental approaches have successfully replaced damaged photoreceptors and retinal pigment epithelium using endogenous and exogenous SCs. CONCLUSIONS Stem cells have the potential to significantly impact retinal regeneration. A combination with bioengineering may bear even greater promise. However, ethical and scientific issues have yet to be solved.
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Affiliation(s)
- Volker Enzmann
- Department of Ophthalmology, Inselspital, University of Bern, Switzerland
| | - Esma Yolcu
- Institute for Cellular Therapeutics, University of Louisville, Louisville, KY USA
| | - Henry J. Kaplan
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY USA
| | - Suzanne T. Ildstad
- Institute for Cellular Therapeutics, University of Louisville, Louisville, KY USA
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608
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Hamel CP, Meunier I, Arndt C, Salah SB, Lopez S, Bazalgette C, Bazalgette C, Zanlonghi X, Arnaud B, Defoort-Dellhemmes S, Puech B. Extensive macular atrophy with pseudodrusen-like appearance: a new clinical entity. Am J Ophthalmol 2009; 147:609-20. [PMID: 19181301 DOI: 10.1016/j.ajo.2008.10.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 10/26/2008] [Accepted: 10/27/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE To describe a previously unreported clinical entity of progressive extensive macular atrophy and pseudodrusen-like appearance in middle-aged patients. DESIGN Clinical, electrophysiologic, and molecular retrospective study. METHODS The database of an outpatient clinic unit for genetic sensory diseases was screened for patients older than 40 years with uncharacterized macular dystrophy. Patients with extensive macular atrophy and pseudodrusen-like appearance were included. RESULTS Eighteen patients of 45 records (40%) matched the inclusion criteria. Bilateral polycyclic well-delineated chorioretinal atrophy extending to the temporal vascular arcades, with a larger vertical axis and without sparing of the fovea featured the macular lesion. The pseudodrusen-like appearance was widespread throughout the posterior pole and the peripheral retina. In the extreme periphery, paving stone lesions were located mostly in the inferior quadrants. In contrast to age-related macular degeneration, a rapid progression of the atrophy was observed with an early involvement of the foveal zone, thus leading to a severe visual loss. All the patients except 2 were legally blind at the end of the follow-up. Unlike age-related macular degeneration, in none of these patients did choroidal neovascularization develop. In all patients, the scotopic and photopic electroretinography responses were reduced. CONCLUSIONS Extensive macular atrophy with pseudodrusen should be considered as a possible pattern of severe macular dystrophy occurring in the middle-aged adult.
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609
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An epidemiological approach for the estimation of disease onset in Central Europe in central and peripheral monogenic retinal dystrophies. Graefes Arch Clin Exp Ophthalmol 2009; 247:885-94. [DOI: 10.1007/s00417-009-1059-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 02/07/2009] [Accepted: 02/13/2009] [Indexed: 12/20/2022] Open
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610
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Mladenovich D, Langeggen I. The Impact of War and Economic Sanction on the Incidence of Retinopathy of Prematurity in Serbia. JOURNAL OF VISUAL IMPAIRMENT & BLINDNESS 2009. [DOI: 10.1177/0145482x0910300305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study compared the distribution of various types of visual impairments among Serbian children who were born prior to the imposed economic sanctions and wars of the 1990s in the former Yugoslavia to that of children who were born during the years of economic sanctions and active war.
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Affiliation(s)
- Derek Mladenovich
- Institute for Public Health Optometry, Salus University, Pennsylvania College of Optometry, 8360 Old York Road, 4th floor, Elkins Park, PA 19027
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611
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Uygun BE, Sharma N, Yarmush M. Retinal pigment epithelium differentiation of stem cells: current status and challenges. Crit Rev Biomed Eng 2009; 37:355-375. [PMID: 20528731 PMCID: PMC4635560 DOI: 10.1615/critrevbiomedeng.v37.i4-5.30] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Degeneration and loss of retinal pigment epithelium (RPE) is the cause of a number of degenerative retinal diseases, including age-related macular degeneration (AMD), retinitis pigmentosa, and diabetic retinopathy, leading to blindness that affects three million Americans as of now. Transplantation of RPE aims to restore retinal structure and the interaction between the RPE and photoreceptors, which is fundamental to sight. Although a significant amount of progress has been made in the past 20 years in autologous RPE transplantation, sources for RPE cells are limited. Recent advances in stem cell culture and differentiation techniques have allowed the generation of RPE cells from pluripotent stem cells. In this review, we discuss strategies for generating functional RPE cells from human embryonic stem cells and induced pluripotent stem cells, and summarize transplantation studies of these derived RPEs. We conclude with challenges in cell-replacement therapies using human embryonic and induced pluripotent stem cell-derived RPEs.
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Affiliation(s)
- Basak E. Uygun
- Center For Engineering in Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Nripen Sharma
- Center For Engineering in Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey
| | - Martin Yarmush
- Center For Engineering in Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
- Department of Biomedical Engineering, Rutgers University, Piscataway, New Jersey
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612
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Kellner U, Kellner S, Weber BHF, Fiebig B, Weinitz S, Ruether K. Lipofuscin- and melanin-related fundus autofluorescence visualize different retinal pigment epithelial alterations in patients with retinitis pigmentosa. Eye (Lond) 2008; 23:1349-59. [PMID: 18791550 DOI: 10.1038/eye.2008.280] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIMS To compare melanin-related near-infrared fundus autofluorescence (FAF; NIA, excitation 787 nm, emission >800 nm) with lipofuscin-related FAF (excitation 488 nm, emission >500 nm) in retinitis pigmentosa (RP). METHODS Thirty-three consecutive RP patients with different modes of inheritance were diagnosed clinically, with full-field ERG, and if possible with molecular genetic methods. FAF and NIA imaging were performed with a confocal scanning laser ophthalmoscope (Heidelberg Retina Angiograph 2). RESULTS Rings of increased FAF were present within an area of preserved retinal pigment epithelium (RPE) at the posterior pole (31/33). Rings of increased NIA were located in the same region as rings of increased FAF. In contrast to FAF, NIA showed a precipitous decline of NIA peripheral to the ring. In larger areas of preserved NIA (11/31), pericentral and foveal NIA were of similar intensity with an area of lower NIA in between. In smaller areas of preserved NIA (20/31), NIA was homogeneous from the perifovea to the fovea. In one patient without a ring of increased FAF, NIA distribution was normal. In the remaining patient with severely advanced RP, no residual RPE as well as no FAF and NIA were detectable. CONCLUSION Characteristic features for FAF and NIA alterations in a heterogeneous group of RP patients indicate a common pathway of RPE degeneration. Patterns of NIA and FAF indicate different pathophysiologic processes involving melanin and lipofuscin. Combined NIA and FAF imaging will provide further insight into the pathogenesis of RP and non-invasive monitoring of future therapeutic interventions.
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Affiliation(s)
- U Kellner
- Retina Science, AugenZentrum Siegburg, Siegburg, Germany.
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613
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Vilboux T, Chaudieu G, Jeannin P, Delattre D, Hedan B, Bourgain C, Queney G, Galibert F, Thomas A, André C. Progressive retinal atrophy in the Border Collie: a new XLPRA. BMC Vet Res 2008; 4:10. [PMID: 18315866 PMCID: PMC2324077 DOI: 10.1186/1746-6148-4-10] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 03/03/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Several forms of progressive retinal atrophy (PRA) segregate in more than 100 breeds of dog with each PRA segregating in one or a few breeds. This breed specificity may be accounted for by founder effects and genetic drift, which have reduced the genetic heterogeneity of each breed, thereby facilitating the identification of causal mutations. We report here a new form of PRA segregating in the Border Collie breed. The clinical signs, including the loss of night vision and a progressive loss of day vision, resulting in complete blindness, occur at the age of three to four years and may be detected earlier through systematic ocular fundus examination and electroretinography (ERG). RESULTS Ophthalmic examinations performed on 487 dogs showed that affected dogs present a classical form of PRA. Of those, 274 have been sampled for DNA extraction and 87 could be connected through a large pedigree. Segregation analysis suggested an X-linked mode of transmission; therefore both XLPRA1 and XLPRA2 mutations were excluded through the genetic tests. CONCLUSION Having excluded these mutations, we suggest that this PRA segregating in Border Collie is a new XLPRA (XLPRA3) and propose it as a potential model for the homologous human disease, X-Linked Retinitis Pigmentosa.
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Affiliation(s)
- Thierry Vilboux
- IGDR CNRS, Génétique et Développement, Faculté de Médecine, Université de Rennes1, 35043 Rennes Cedex, France.
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614
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Gonzalez-Santos JM, Cao H, Duan RC, Hu J. Mutation in the splicing factor Hprp3p linked to retinitis pigmentosa impairs interactions within the U4/U6 snRNP complex. Hum Mol Genet 2007; 17:225-39. [PMID: 17932117 DOI: 10.1093/hmg/ddm300] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in PRPF3, a gene encoding the essential pre-mRNA splicing factor Hprp3p, have been identified in patients with autosomal dominant retinitis pigmentosa type 18 (RP18). Patients with RP18 have one of two single amino acid substitutions, Pro493Ser or Thr494Met, at the highly conserved Hprp3p C-terminal region. Pro493Ser occurs sporadically, whereas Thr494Met is observed in several unlinked RP families worldwide. The latter mutation also alters a potential recognition motif for phosphorylation by casein kinase II (CKII). To understand the molecular basis of RP18, we examined the consequences of Thr494Met mutation on Hprp3p molecular interactions with components of the U4/U6.U5 small nuclear ribonucleoprotein particles (snRNPs) complex. Since numerous mutations causing human diseases change pre-mRNA splice sites, we investigated whether Thr494Met substitution affects the processing of PRPF3 mRNA. We found that Thr494Met does not affect PRPF3 mRNA processing, indicating that the mutation may exert its effect primarily at the protein level. We used small hairpin RNAs to specifically silence the endogenous PRPF3 while simultaneously expressing HA-tagged Thr494Met. We demonstrated that the C- but not N-terminal region of Hprp3p is indeed phosphorylated by CKII in vitro and in cells. CKII-mediated Hprp3p phosphorylation was significantly reduced by Thr494Met mutation. Consequently, the Hprp3p C-terminal region is rendered partially defective in its association with itself, Hprp4p, and U4/U6 snRNA. Our findings provide new insights into the biology of Hprp3p and suggest that the loss of Hprp3p phosphorylation at Thr494 is a key step for initiating Thr494Met aberrant interactions within U4/U6 snRNP complex and that these are likely linked to the RP18 phenotype.
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615
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Stephan A, Vaughan S, Shaw MK, Gull K, McKean PG. An essential quality control mechanism at the eukaryotic basal body prior to intraflagellar transport. Traffic 2007; 8:1323-30. [PMID: 17645436 DOI: 10.1111/j.1600-0854.2007.00611.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Constructing a eukaryotic cilium/flagellum is a demanding task requiring the transport of proteins from their cytoplasmic synthesis site into a spatially and environmentally distinct cellular compartment. The clear potential hazard is that import of aberrant proteins could seriously disable cilia/flagella assembly or turnover processes. Here, we reveal that tubulin protein destined for incorporation into axonemal microtubules interacts with a tubulin cofactor C (TBCC) domain-containing protein that is specifically located at the mature basal body transitional fibres. RNA interference-mediated ablation of this protein results in axonemal microtubule defects but no effect on other microtubule populations within the cell. Bioinformatics analysis indicates that this protein belongs to a clade of flagellum-specific TBCC-like proteins that includes the human protein, XRP2, mutations which lead to certain forms of the hereditary eye disease retinitis pigmentosa. Taken with other observations regarding the role of transitional fibres in cilium/flagellum assembly, we suggest that a localized protein processing capacity embedded at transitional fibres ensures the 'quality' of tubulin imported into the cilium/flagellum, and further, that loss of a ciliary/flagellar quality control capability may underpin a number of human genetic disorders.
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Affiliation(s)
- Angela Stephan
- Biomedical Sciences Unit, Department of Biological Sciences, Lancaster University, Lancaster, LA1 4YQ, UK
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616
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Kan E, Yilmaz T, Aydemir O, Güler M, Kurt J. Coats-like retinitis pigmentosa: Reports of three cases. Clin Ophthalmol 2007; 1:193-8. [PMID: 19668510 PMCID: PMC2704518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Describing the ophthalmic findings of an exudative vasculopathy called as Coats-like retinitis pigmentosa on three patients. The etiology of the Coats-like retinitis pigmentosa is obscure. The principal theories have been discussed in this article. METHODS Three observational case series have been discussed. Complete ophthalmic examinations and color fundus photos, visual field, and fluorescein angiography have been performed. RESULTS We have identified 3 patients who have some typical clinical features of Coats-like retinitis pigmentosa; peripheral serous retinal detachment, telangiectasia, prominent lipid deposition, pigmentary changes in peripheral retina, and loss of vision. None of the three patients had positive family history. All of the patients have had symptoms of nyctalopia, decreased central vision, and two of them have had constriction of visual field. All of the patients have had cataracts and two of them underwent cataract surgery. Fundus examination and fluorescein angiography of patients revealed typical retinitis pigmentosa with Coats-type changes in bilateral inferiotemporal quadrants. CONCLUSION A better understanding of clinical features and genetic etiology of Coats-type retinitis pigmentosa will aid diagnosis and development of new therapies. If sufficient conditions arise, genetic factors that influence the expression of CRB1 mutations in Coats-like retinitis pigmentosa should be detected.
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Affiliation(s)
| | | | - Orhan Aydemir
- Correspondence: Orhan Aydemir, Firat University School of Medicine, Department of Ophthalmology, Elaziğ, Turkey, Tel +90 4242333555, Fax +90 4242388096, Email
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