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Li S, Hu Y, Li Y, Hu M, Wang W, Ma Y, Cai Y, Wei M, Yao Y, Wang Y, Dong K, Gu Y, Zhao H, Bao J, Qiu Z, Zhang M, Hu X, Xue T. Generation of nonhuman primate retinitis pigmentosa model by in situ knockout of RHO in rhesus macaque retina. Sci Bull (Beijing) 2021; 66:374-385. [PMID: 36654417 DOI: 10.1016/j.scib.2020.09.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/11/2020] [Accepted: 07/15/2020] [Indexed: 01/20/2023]
Abstract
Retinitis pigmentosa (RP) is a form of inherited retinal degenerative diseases that ultimately involves the macula, which is present in primates but not in the rodents. Therefore, creating nonhuman primate (NHP) models of RP is of critical importance to study its mechanism of pathogenesis and to evaluate potential therapeutic options in the future. Here we applied adeno-associated virus (AAV)-delivered CRISPR/SaCas9 technology to knockout the RHO gene in the retinae of the adult rhesus macaque (Macaca mulatta) to investigate the hypothesis whether non-germline mutation of the RHO gene is sufficient to recapitulate RP. Through a series of studies, we were able to demonstrate successful somatic editing of the RHO gene and reduced RHO protein expression. More importantly, the mutant macaque retinae displayed clinical RP phenotypes, including photoreceptor degeneration, retinal thinning, abnormal rod subcellular structures, and reduced photoresponse. Therefore, we suggest somatic editing of the RHO gene is able to phenocopy RP, and the reduced time span in generating NHP mutant accelerates RP research and expands the utility of NHP model for human disease study.
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Affiliation(s)
- Shouzhen Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yingzhou Hu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; National Research Facility for Phenotypic & Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650107, China
| | - Yunqin Li
- Second People's Hospital of Yunnan Province, Yunnan Eye Institute, Key Laboratory of Yunnan Province for the Prevention and Treatment of Ophthalmology, Kunming 650223, China
| | - Min Hu
- Second People's Hospital of Yunnan Province, Yunnan Eye Institute, Key Laboratory of Yunnan Province for the Prevention and Treatment of Ophthalmology, Kunming 650223, China
| | - Wenchao Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Yuqian Ma
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yuan Cai
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Min Wei
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yichuan Yao
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yun Wang
- Kunming Primate Research Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Kai Dong
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yonghao Gu
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Huan Zhao
- Department of Biological and Environmental Engineering, Hefei University, Hefei 230601, China
| | - Jin Bao
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Zilong Qiu
- Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; Institute of Neuroscience, State Key Laboratory of Neuroscience, Chinese Academy of Sciences, Shanghai 200031, China
| | - Mei Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, University of Science and Technology of China, Hefei 230026, China.
| | - Xintian Hu
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences & Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; Kunming Primate Research Center, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; National Research Facility for Phenotypic & Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650107, China.
| | - Tian Xue
- Hefei National Laboratory for Physical Sciences at the Microscale, Eye Center at The First Affiliated Hospital of USTC, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China; Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, University of Science and Technology of China, Hefei 230026, China.
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Retinal histopathology in eyes from patients with autosomal dominant retinitis pigmentosa caused by rhodopsin mutations. Graefes Arch Clin Exp Ophthalmol 2015. [PMID: 26202387 DOI: 10.1007/s00417-015-3099-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PURPOSE To evaluate the histopathology in donor eyes from patients with autosomal dominant retinitis pigmentosa (ADRP) caused by p.P23H, p.P347T and p.P347L rhodopsin ( RHO ) gene mutations. METHODS Eyes from a 72-year-old male (donor 1), an 83-year-old female (donor 2), an 80-year-old female (donor 3), and three age-similar normal eyes were examined macroscopically, by scanning laser ophthalmoscopy and optical coherence tomography imaging. Perifoveal and peripheral pieces were processed for microscopy and immunocytochemistry with markers for photoreceptor cells. RESULTS DNA analysis revealed RHO mutations c.68C>A (p.P23H) in donor 1, c.1040C>T (p.P347L) in donor 2 and c.1039C>A (p.P347T) in donor 3. Histology of the ADRP eyes showed retinas with little evidence of stratified nuclear layers in the periphery and a prominent inner nuclear layer present in the perifoveal region in the p.P23H and p.P347T eyes, while it was severely atrophic in the p.P347L eye. The p.P23H and p.P347T mutations cause a profound loss of rods in both the periphery and perifovea, while the p.P347L mutation displays near complete absence of rods in both regions. All three rhodopsin mutations caused a profound loss of cones in the periphery. The p.P23H and p.P347T mutations led to the presence of highly disorganized cones in the perifovea. However, the p.P347L mutation led to near complete absence of cones also in the perifovea. CONCLUSIONS Our results support clinical findings indicating that mutations affecting residue P347 develop more severe phenotypes than those affecting P23. Furthermore, our results indicate a more severe phenotype in the p.P347L retina as compared to the p.P347T retina.
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Zheng L, Farrell DM, Fulton RM, Bagg EE, Salcedo E, Manino M, Britt SG. Analysis of Conserved Glutamate and Aspartate Residues in Drosophila Rhodopsin 1 and Their Influence on Spectral Tuning. J Biol Chem 2015. [PMID: 26195627 PMCID: PMC4571949 DOI: 10.1074/jbc.m115.677765] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molecular mechanisms that regulate invertebrate visual pigment absorption are poorly understood. Studies of amphioxus Go-opsin have demonstrated that Glu-181 functions as the counterion in this pigment. This finding has led to the proposal that Glu-181 may function as the counterion in other invertebrate visual pigments as well. Here we describe a series of mutagenesis experiments to test this hypothesis and to also test whether other conserved acidic amino acids in Drosophila Rhodopsin 1 (Rh1) may serve as the counterion of this visual pigment. Of the 5 Glu and Asp residues replaced by Gln or Asn in our experiments, none of the mutant pigments shift the absorption of Rh1 by more than 6 nm. In combination with prior studies, these results suggest that the counterion in Drosophila Rh1 may not be located at Glu-181 as in amphioxus, or at Glu-113 as in bovine rhodopsin. Conversely, the extremely low steady state levels of the E194Q mutant pigment (bovine opsin site Glu-181), and the rhabdomere degeneration observed in flies expressing this mutant demonstrate that a negatively charged residue at this position is essential for normal rhodopsin function in vivo. This work also raises the possibility that another residue or physiologic anion may compensate for the missing counterion in the E194Q mutant.
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Affiliation(s)
- Lijun Zheng
- From the Departments of Cell and Developmental Biology
| | | | - Ruth M Fulton
- From the Departments of Cell and Developmental Biology
| | - Eve E Bagg
- From the Departments of Cell and Developmental Biology
| | | | | | - Steven G Britt
- From the Departments of Cell and Developmental Biology, Ophthalmology and Rocky Mountain Lions Eye Institute, University of Colorado, Anschutz Medical Campus, School of Medicine, Aurora, Colorado 80045
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Bonilha VL, Rayborn ME, Bell BA, Marino MJ, Pauer GJ, Beight CD, Chiang J, Traboulsi EI, Hollyfield JG, Hagstrom SA. Histopathological comparison of eyes from patients with autosomal recessive retinitis pigmentosa caused by novel EYS mutations. Graefes Arch Clin Exp Ophthalmol 2015; 253:295-305. [PMID: 25491159 PMCID: PMC10846590 DOI: 10.1007/s00417-014-2868-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/12/2014] [Accepted: 11/14/2014] [Indexed: 10/24/2022] Open
Abstract
To evaluate the retinal histopathology in donor eyes from patients with autosomal recessive retinitis pigmentosa (arRP) caused by EYS mutations. Eyes from a 72-year-old female (donor 1, family 1), a 91-year-old female (donor 2, family 2), and her 97-year-old sister (donor 3, family 2) were evaluated with macroscopic, scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) imaging. Age-similar normal eyes and an eye donated by donor 1's asymptomatic mother (donor 4, family 1) were used as controls. The perifovea and peripheral retina were processed for microscopy and immunocytochemistry with markers for cone and rod photoreceptor cells. DNA analysis revealed EYS mutations c.2259 + 1G > A and c.2620C > T (p.Q874X) in family 1, and c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del in family 2. Imaging studies revealed the presence of bone spicule pigment in arRP donor retinas. Histology of all three affected donor eyes showed very thin retinas with little evidence of stratified nuclear layers in the periphery. In contrast, the perifovea displayed a prominent inner nuclear layer. Immunocytochemistry analysis demonstrated advanced retinal degenerative changes in all eyes, with near-total absence of rod photoreceptors. In addition, we found that the perifoveal cones were more preserved in retinas from the donor with the midsize genomic rearrangement (c.4350_4356del (p.I1451Pfs*3) and c.2739-?_3244 + ?del) than in retinas from the donors with the truncating (c.2259 + 1G > A and c.2620C > T (p.Q874X) mutations. Advanced retinal degenerative changes with near-total absence of rods and preservation of some perifoveal cones are observed in arRP donor retinas with EYS mutations.
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Affiliation(s)
- Vera L Bonilha
- Ophthalmic Research - i31, Cleveland Clinic, Cole Eye Institute, 9500 Euclid Avenue, Cleveland, OH, 44195, USA,
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Ando R, Noda K, Tomaru U, Kamoshita M, Ozawa Y, Notomi S, Hisatomi T, Noda M, Kanda A, Ishibashi T, Kasahara M, Ishida S. Decreased proteasomal activity causes photoreceptor degeneration in mice. Invest Ophthalmol Vis Sci 2014; 55:4682-90. [PMID: 24994871 DOI: 10.1167/iovs.13-13272] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
PURPOSE To study the retinal degeneration caused by decreased proteasomal activity in β5t transgenic (β5t-Tg) mice, an animal model of senescence acceleration. METHODS β5t-Tg mice and age-matched littermate control (WT) mice were used. Proteasomal activities and protein level of poly-ubiquitinated protein in retinal extracts were quantified. Fundus images of β5t-Tg mice were taken and their features were assessed. For histologic evaluation, the thicknesses of inner nuclear layer (INL), outer nuclear layer (ONL), and photoreceptor outer segment (OS) were measured. For functional analysis, ERG was recorded under scotopic and photopic illumination conditions. Immunofluorescence (IF) staining and TUNEL were performed to investigate the mechanism of photoreceptor degeneration. RESULTS Chymotrypsin-like activity was partially suppressed in retinal tissues of β5t-Tg mice. Retinal degenerative changes with arterial attenuation were present in β5t-Tg, but not in WT mice. Inner nuclear layer thickness showed no significant change between β5t-Tg and WT mice at 1, 3, 6, and 9 months of age. By contrast, thicknesses of ONL and OS in β5t-Tg mice were significantly decreased at 3, 6, and 9 months compared with those in WT mice. Electroretinograms showed decrease of scotopic a-wave amplitude in β5t-Tg mice. The number of TUNEL-positive cells in ONL were significantly increased in β5t-Tg mice and colocalized with apoptosis-inducing factor, but not with cleaved caspase-3 and -9, indicating that the photoreceptor cell death was induced via a caspase-independent pathway. CONCLUSIONS The current data showed that impaired proteasomal function causes photoreceptor degeneration.
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Affiliation(s)
- Ryo Ando
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Kousuke Noda
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Utano Tomaru
- Department of Pathology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Mamoru Kamoshita
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Yoko Ozawa
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Shoji Notomi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toshio Hisatomi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mika Noda
- Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Atsuhiro Kanda
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Tatsuro Ishibashi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masanori Kasahara
- Department of Pathology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Susumu Ishida
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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Mullins RF, Kuehn MH, Radu RA, Enriquez GS, East JS, Schindler EI, Travis GH, Stone EM. Autosomal recessive retinitis pigmentosa due to ABCA4 mutations: clinical, pathologic, and molecular characterization. Invest Ophthalmol Vis Sci 2012; 53:1883-94. [PMID: 22395892 DOI: 10.1167/iovs.12-9477] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
PURPOSE Autosomal recessive retinitis pigmentosa (ARRP) is a genetically heterogeneous condition characterized by progressive loss of retinal photoreceptor cells. In order to gain new insights into the pathogenesis of ARRP, we evaluated the morphological, biochemical, and gene expression changes in eyes from a human donor with ARRP due to mutations in the ABCA4 gene. METHODS Eyes were obtained postmortem from a donor with end-stage retinitis pigmentosa. The coding sequences of the RDS, RHO, and ABCA4 genes were screened for disease-causing mutations. Morphological changes in different regions of the retina were examined histologically, and levels of lipofuscin-associated bisretinoids were measured. Gene expression was examined in retinal/choroidal tissue using microarray analysis, and all parameters were compared to those in unaffected control donors. RESULTS Genetic analysis of the donor's DNA identified two mutations in the ABCA4 gene, IVS14+1G > C and Phe1440del1 cT, each on a separate allele. Morphological evaluation revealed complete loss of the outer nuclear layer, remodeling of the inner retina, loss of retinal vasculature, and regional neovascularization. The retinal pigment epithelium and choriocapillaris exhibited regional preservation. Microarray analysis revealed loss of photoreceptor cell-associated transcripts, with preservation of multiple genes expressed specifically in inner retinal neurons. CONCLUSIONS The persistence of transcripts expressed by inner retinal neurons suggests that despite significant plasticity that occurs during retinal degeneration, bipolar cells and ganglion cells remain at least partially differentiated. Findings from this study suggest that some forms of therapy currently under investigation may have benefit even in advanced retinal degeneration.
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Affiliation(s)
- Robert F Mullins
- Department of Ophthalmology and Visual Sciences, The University of Iowa, Iowa City, Iowa, USA
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Ben-Arie-Weintrob Y, Berson EL, Dryja TP. Histopathologic-genotypic correlations in retinitis pigmentosa and allied diseases. Ophthalmic Genet 2005; 26:91-100. [PMID: 16020312 DOI: 10.1080/13816810590968032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This paper reviews the published histopathologic findings of patients with retinitis pigmentosa (RP) or an allied disease in whom the responsible gene defect was identified, including 10 cases with dominant RP (cases with mutations in RHO, PRPC8, and RP1), three with dominant spinocerebellar ataxia (SCA7), three X-linked RP carrier females (RPGR), two with congenital retinal blindness (AIPL1 and RPE65), two with mitochondrial encephalomyopathy overlap syndrome (MTTL1), and one case each with dominant cone degeneration (GCAP1), X-linked cone degeneration (RCP), enhanced S-cone syndrome (NR2E3), and dominant late-onset retinal degeneration (CTRP5). No histopathologic descriptions were found of the vast majority of genetically defined forms of retinal degeneration.
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Affiliation(s)
- Yael Ben-Arie-Weintrob
- The Cogan Eye Pathology Laboratory and the Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye & Ear Infirmary, 243 Charles Street, Boston, MA 02114, U.S.A
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To K, Adamian M, Berson EL. Histologic study of retinitis pigmentosa due to a mutation in the RP13 gene (PRPC8): comparison with rhodopsin Pro23His, Cys110Arg, and Glu181Lys. Am J Ophthalmol 2004; 137:946-8. [PMID: 15126168 DOI: 10.1016/j.ajo.2003.10.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2003] [Indexed: 10/26/2022]
Abstract
PURPOSE To evaluate the retina in autopsy eyes from patients over age 60 with autosomal dominant retinitis pigmentosa and a mutation in the RP13 gene (designated as PRPC8, Arg2310Gly), rhodopsin Pro23His, rhodopsin Cys110Arg, or rhodopsin Glu181Lys. DESIGN Histologic study of the retina. METHODS All eyes were prepared for electron microscopy within 12 hours after death. RESULTS All eyes showed loss of rod photoreceptors. Remaining cones showed perinuclear membranous swirls, inclusion bodies in the inner segments, and shortened or absent outer segments despite causation by various gene defects. CONCLUSION The comparable histologic findings in these four cases suggest a final common pathway leading to photoreceptor cell death in these dominant forms of retinitis pigmentosa.
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Affiliation(s)
- King To
- Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA
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Huang D, Eudy JD, Uzvolgyi E, Davis JR, Talmadge CB, Pretto D, Weston MD, Lehman JE, Zhou M, Seemayer TA, Ahmad I, Kimberling WJ, Sumegi J. Identification of the mouse and rat orthologs of the gene mutated in Usher syndrome type IIA and the cellular source of USH2A mRNA in retina, a target tissue of the disease. Genomics 2002; 80:195-203. [PMID: 12160733 DOI: 10.1006/geno.2002.6823] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Usher syndrome type IIA (MIM: 27601) is an autosomal recessive disorder characterized by moderate to severe congenital deafness and progressive retinitis pigmentosa. We recently identified the human Usher syndrome type IIA gene (USH2A) on chromosome 1q41, which encodes a protein possessing 10 laminin epidermal growth factor and four fibronectin type 3 domains, both commonly observed in extracellular matrix proteins. To gain insight into the pathogenesis of Usher syndrome type IIA, we isolated and characterized the murine (Ush2a) and rat (rat Ush2a) orthologs of human USH2A. We mapped mouse Ush2a by fluorescence in situ hybridization to mouse chromosome 1 in the region syntenic to human chromosome 1q41. Rat Ush2a has been localized by radiation hybrid mapping to rat chromosome 13 between d13rat49 and d13rat76. The mouse and rat genes, similar to human USH2A, are expressed primarily in retina and cochlea. Mouse Ush2a encodes a 161-kDa protein that shows 68% identity and 9% similarity to the human USH2A protein. Rat Ush2a encodes a 167-kDa protein with 64% identity and 10% similarity to the human protein and 81% identity and 5% similarity to the mouse USH2A protein. The predicted amino acid sequence of the mouse and rat proteins, like their human counterpart, contains a leader sequence, an amino-terminal globular domain, 10 laminin epidermal growth factor domains, and four carboxy-terminal fibronectin type III motifs. With in situ hybridization, we compared the cellular expression of the USH2A gene in rat, mouse, and human retinas. USH2A mRNA in the adult rat, mouse, and human is expressed in the cells of the outer nuclear layer of the retina, one of the target tissues of the disease. In the developing rat retina, Ush2a mRNA expression appears in the neuroepithelium at embryonic day 17.
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Affiliation(s)
- Dali Huang
- Department of Pathology and Microbiology, Omaha, Nebraska 68198, USA
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