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Veerappa AM. Cascade of interactions between candidate genes reveals convergent mechanisms in keratoconus disease pathogenesis. Ophthalmic Genet 2021; 42:114-131. [PMID: 33554698 DOI: 10.1080/13816810.2020.1868013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Keratoconus is a progressive thinning, steepening and distortion of the cornea which can lead to loss of vision if left untreated. Keratoconus has a complex multifactorial etiology, with genetic and environmental components contributing to the disease pathophysiology. Studies have observed high concordance between monozygotic twins, discordance between dizygotic twins, and high familial segregation indicating the presence of a very strong genetic component in the pathogenesis of keratoconus. The use of genome-wide linkage studies on families and twins, genome-wide association studies (GWAS) on case-controls, next-generation sequencing (NGS)-based genomic screens on both familial and non-familial cohorts have led to the identification of keratoconus candidate genes with much greater success and increased resproducibility of genetic findings. This review focuses on candidate genes identified till date and attempts to understand their role in biological processes underlying keratoconus pathogenesis. In addition, using these genes I propose molecular pathways that could contribute to keratoconus pathogenesis. The pathways identified the presence of direct cross-talk between known candidate genes of keratoconus and remarkably, 28 known candidate genes have a direct relationship among themselves that involves direct protein-protein binding, regulatory activities such as activation and inhibition, chaperone, transcriptional activation/co-activation, and enzyme catalysis. This review attempts to describe these relationships and cross-talks in the context of keratoconus pathogenesis.
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Affiliation(s)
- Avinash M Veerappa
- Department of Ophthalmology, NYU Langone Medical Center, New York, New York, USA
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2
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Mohammadi A, Ahmadi Shadmehri A, Taghavi M, Yaghoobi G, Pourreza MR, Tabatabaiefar MA. A pathogenic variant in the transforming growth factor beta I ( TGFBI) in four Iranian extended families segregating granular corneal dystrophy type II: A literature review. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2020; 23:1020-1027. [PMID: 32952948 PMCID: PMC7478261 DOI: 10.22038/ijbms.2020.36763.8757] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 03/15/2020] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Granular and lattice corneal dystrophies (GCDs & LCDs) are autosomal dominant inherited disorders of the cornea. Due to genetic heterogeneity and large genes, unraveling the mutation is challenging. MATERIALS AND METHODS Patients underwent comprehensive clinical examination, and targeted next-generation sequencing (NGS) was used for mutation detection. Co-segregation and in silico analysis was accomplished. RESULTS Patients suffered from GCD. NGS disclosed a known pathogenic variant, c.371G>A (p.R124H), in exon 4 of TGFBI. The variant co-segregated with the phenotype in the family. Homozygous patients manifested with more severe phenotypes. Variable expressivity was observed among heterozygous patients. CONCLUSION The results, in accordance with previous studies, indicate that the c.371G>A in TGFBI is associated with GCD. Some phenotypic variations are related to factors such as modifier genes, reduced penetrance and environmental effects.
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Affiliation(s)
- Aliasgar Mohammadi
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Azam Ahmadi Shadmehri
- Department of Genetics, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | | | - Gholamhossein Yaghoobi
- Department of Ophthalmology, Birjand University of Medical Science, South Khorasan, Iran
- Social Detrimental Health Center, Birjand University of Medical Science, South Khorasan, Iran
| | - Mohammad Reza Pourreza
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Amin Tabatabaiefar
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
- Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
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Lv Y, Li XJ, Wang HP, Liu B, Chen W, Zhang L. TGF-β1 enhanced myocardial differentiation through inhibition of the Wnt/β-catenin pathway with rat BMSCs. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2020; 23:1012-1019. [PMID: 32952947 PMCID: PMC7478252 DOI: 10.22038/ijbms.2020.42396.10019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 04/28/2020] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To investigate and test the hypotheses that TGF-β1 enhanced myocardial differentiation through Wnt/β-catenin pathway with rat bone marrow mesenchymal stem cells (BMSCs). MATERIALS AND METHODS Lentiviral vectors carrying the TGF-β1 gene were transduced into rat BMSCs firstly. Then several kinds of experimental methods were used to elucidate the related mechanisms by which TGF-β1 adjusts myocardial differentiation in rat BMSCs. RESULTS Immunocytochemistry revealed that cTnI and Cx43 expressed positively in the cells that were transduced with TGF-β1. The results of Western blot (WB) test showed that the levels of intranuclear β-catenin and total β-catenin were all significantly decreased. However, the cytoplasmic β-catenin level was largely unchanged. Moreover, the levels of GSK-3β were largely unchanged in BMSCs, whereas phosphorylated GSK-3β was significantly decreased in BMSCs. When given the activator of Wnt/β-catenin pathway (lithium chloride, LiCl) to BMSCs transducted with TGF-β1, β-catenin was increased, while phosphorylated β-catenin was decreased. In addition, cyclinD1, MMP-7, and c-Myc protein in BMSCs transducted with Lenti-TGF-β1-GFP were significantly lower. CONCLUSION These results indicate that TGF-β1 promotes BMSCs cardiomyogenic differentiation by promoting the phosphorylation of β-catenin and inhibiting cyclinD1, MMP-7, and c-Myc expression in Wnt/β-catenin signaling pathway.
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Affiliation(s)
- Yang Lv
- Department of Histology and Embryology, Hebei North University, Zhangjiakou, Hebei, China
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Xiu-juan Li
- Department of Histology and Embryology, Hebei North University, Zhangjiakou, Hebei, China
| | - Hai-Ping Wang
- Department of Histology and Embryology, Hebei North University, Zhangjiakou, Hebei, China
| | - Bo Liu
- Department of Pathology, the First Affiliated Hospital of Hebei North University, Zhangjiakou, Hebei, China
| | - Wei Chen
- Department of Pathology, the First Affiliated Hospital of Hebei North University, Zhangjiakou, Hebei, China
| | - Lei Zhang
- Department of Histology and Embryology, Hebei Medical University, Shijiazhuang, Hebei, China
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Nielsen NS, Poulsen ET, Lukassen MV, Chao Shern C, Mogensen EH, Weberskov CE, DeDionisio L, Schauser L, Moore TC, Otzen DE, Hjortdal J, Enghild JJ. Biochemical mechanisms of aggregation in TGFBI-linked corneal dystrophies. Prog Retin Eye Res 2020; 77:100843. [DOI: 10.1016/j.preteyeres.2020.100843] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 01/17/2020] [Accepted: 01/23/2020] [Indexed: 12/22/2022]
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De Sousa Peixoto R, Mutch S, Eason J, Jaakson K, Haamer E, Maharajan VS. Association of unilateral lattice corneal dystrophy on slit lamp and bilateral confocal microscopy features with H572R mutation in the TGFBI gene. Eye (Lond) 2019; 33:1973-1975. [PMID: 31270466 DOI: 10.1038/s41433-019-0508-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 05/24/2019] [Accepted: 06/12/2019] [Indexed: 11/09/2022] Open
Affiliation(s)
| | - Stacey Mutch
- East Midlands Regional Molecular Genetics Laboratory, Nottingham University Hospitals trust, Nottingham, NG5 1PB, UK
| | - Jacqueline Eason
- Clinical Genetics Service, Nottingham University Hospitals trust, Nottingham, NG5 1PB, UK
| | - Kaie Jaakson
- Asper Biogene LLC, Vaksali 17a, 50410, Tartu, Estonia
| | - Eneli Haamer
- Asper Biogene LLC, Vaksali 17a, 50410, Tartu, Estonia
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Kheir V, Cortés-González V, Zenteno JC, Schorderet DF. Mutation update: TGFBI pathogenic and likely pathogenic variants in corneal dystrophies. Hum Mutat 2019; 40:675-693. [PMID: 30830990 DOI: 10.1002/humu.23737] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 02/26/2019] [Accepted: 02/28/2019] [Indexed: 01/07/2023]
Abstract
Human transforming growth factor β-induced (TGFBI), is a gene responsible for various corneal dystrophies. TGFBI produces a protein called TGFBI, which is involved in cell adhesion and serves as a recognition sequence for integrins. An alteration in cell surface interactions could be the underlying cause for the progressive accumulation of extracellular deposits in different layers of the cornea with the resulting changes of refractive index and transparency. To this date, 69 different pathogenic or likely pathogenic variants in TGFBI have been identified in a heterozygous or homozygous state in various corneal dystrophies, including a novel variant reported here. All disease-associated variants were inherited as autosomal-dominant traits but one; this latter was inherited as an autosomal recessive trait. Most corneal dystrophy-associated variants are located at amino acids Arg124 and Arg555. To keep the list of corneal dystrophy-associated variant current, we generated a locus-specific database for TGFBI (http://databases.lovd.nl/shared/variants/TGFBI) containing all pathogenic and likely pathogenic variants reported so far. Non-disease-associated variants are described in specific databases, like gnomAD and ExAC but are not listed here. This article presents the most recent up-to-date list of disease-associated variants.
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Affiliation(s)
- Valeria Kheir
- Institute for Research in Ophthalmology, Sion, Switzerland.,Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Vianney Cortés-González
- Department of Genetics, Hospital "Dr. Luis Sanchez Bulnes", Asociación Para Evitar la Ceguera en México, Mexico City, Mexico
| | - Juan C Zenteno
- Department of Genetics, Institute of Ophthalmology "Conde de Valenciana", Mexico City, Mexico.,Department of Biochemistry, Faculty of Medicine, UNAM, Mexico City, Mexico
| | - Daniel F Schorderet
- Institute for Research in Ophthalmology, Sion, Switzerland.,Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.,Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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Han J, Zhang M, Lin HY, Huang FY, Lin YY, Tan GH, Zheng ZY. Impaired Autophagic Degradation of Transforming Growth Factor-β-Induced Protein by Macrophages in Lattice Corneal Dystrophy. Invest Ophthalmol Vis Sci 2019; 60:978-989. [PMID: 30884524 DOI: 10.1167/iovs.18-25838] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Lattice corneal dystrophy (LCD) is related to the denaturation of transforming growth factor-β-induced protein (TGFBIp). Autophagic degradation of the denatured proteins by macrophages is one pathway to remove the denatured proteins. Thus, we investigated the role of autophagy in the degradation of mutant (MU) TGFBIp in macrophages. Methods Corneas from participants were observed by slit-lamp photography and subjected to histopathologic and genetic analysis. Wild-type (WT) and MU TGFBIp were recombined and expressed. Macrophages from MU participants were isolated and cocultured with the recombinant TGFBIp. Colocalization of the two molecules was observed by immunofluorescent microscopy. Enzyme-linked immunosorbent assay, Western blotting, and flow cytometry were used to detect changes in molecule expression related to the phenotype and autophagy process. Results Fourteen members from a family of 25 were identified as LCD sufferers. Significant TGFBIp aggregates and macrophage infiltration were found only in the corneas of LCD sufferers. Marker accumulation of TGFBIp was found in macrophages exposed to MU TGFBIp even at 5 hours after MU TGFBIp was withdrawn. High expressions of CD68 and CD36 were found in macrophages exposed to WT TGFBIp, but not to MU TGFBIp. Impaired autophagic flux due to defective autophagosome fusion to lysosomes was found in macrophages exposed to MU TGFBIp. Blockage of the autophagic process suppressed the expression of CD68 and CD36 in macrophages exposed to WT TGFBIp to levels similar to those found in macrophages exposed to MU TGFBIp. Conclusions Our results suggested that reversion of the defective autophagic process in macrophages may be a therapeutic strategy for patients with LCD.
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Affiliation(s)
- Ji Han
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China.,Department of Ophthalmology, The First Affiliated Hospital of Hainan Medical College, Haikou, China
| | - Ming Zhang
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China
| | - Hai-Yan Lin
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China
| | - Feng-Ying Huang
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China
| | - Ying-Ying Lin
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China
| | - Guang-Hong Tan
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China
| | - Zhen-You Zheng
- Hainan Provincial Key Laboratory of Tropical Medicine, Hainan Medical College, Haikou, China.,Department of Ophthalmology, The First Affiliated Hospital of Hainan Medical College, Haikou, China
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García-Castellanos R, Nielsen NS, Runager K, Thøgersen IB, Lukassen MV, Poulsen ET, Goulas T, Enghild JJ, Gomis-Rüth FX. Structural and Functional Implications of Human Transforming Growth Factor β-Induced Protein, TGFBIp, in Corneal Dystrophies. Structure 2017; 25:1740-1750.e2. [PMID: 28988748 DOI: 10.1016/j.str.2017.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 08/02/2017] [Accepted: 09/01/2017] [Indexed: 12/31/2022]
Abstract
A major cause of visual impairment, corneal dystrophies result from accumulation of protein deposits in the cornea. One of the proteins involved is transforming growth factor β-induced protein (TGFBIp), an extracellular matrix component that interacts with integrins but also produces corneal deposits when mutated. Human TGFBIp is a multi-domain 683-residue protein, which contains one CROPT domain and four FAS1 domains. Its structure spans ∼120 Å and reveals that vicinal domains FAS1-1/FAS1-2 and FAS1-3/FAS1-4 tightly interact in an equivalent manner. The FAS1 domains are sandwiches of two orthogonal four-stranded β sheets decorated with two three-helix insertions. The N-terminal FAS1 dimer forms a compact moiety with the structurally novel CROPT domain, which is a five-stranded all-β cysteine-knot solely found in TGFBIp and periostin. The overall TGFBIp architecture discloses regions for integrin binding and that most dystrophic mutations cluster at both molecule ends, within domains FAS1-1 and FAS1-4.
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Affiliation(s)
- Raquel García-Castellanos
- Proteolysis Laboratory, Structural Biology Unit ("María-de-Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona (CSIC), Barcelona Science Park, c/Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain
| | - Nadia Sukusu Nielsen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - Kasper Runager
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - Ida B Thøgersen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - Marie V Lukassen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - Ebbe T Poulsen
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - Theodoros Goulas
- Proteolysis Laboratory, Structural Biology Unit ("María-de-Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona (CSIC), Barcelona Science Park, c/Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain
| | - Jan J Enghild
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej, 10, 8000 Aarhus C, Denmark
| | - F Xavier Gomis-Rüth
- Proteolysis Laboratory, Structural Biology Unit ("María-de-Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona (CSIC), Barcelona Science Park, c/Baldiri Reixac 15-21, 08028 Barcelona, Catalonia, Spain.
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pH Induced Conformational Transitions in the Transforming Growth Factor β-Induced Protein (TGFβIp) Associated Corneal Dystrophy Mutants. Sci Rep 2016; 6:23836. [PMID: 27030015 PMCID: PMC4814907 DOI: 10.1038/srep23836] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 02/12/2016] [Indexed: 11/24/2022] Open
Abstract
Most stromal corneal dystrophies are associated with aggregation and deposition of the mutated transforming growth factor-β induced protein (TGFβIp). The 4th_FAS1 domain of TGFβIp harbors ~80% of the mutations that forms amyloidogenic and non-amyloidogenic aggregates. To understand the mechanism of aggregation and the differences between the amyloidogenic and non-amyloidogenic phenotypes, we expressed the 4th_FAS1 domains of TGFβIp carrying the mutations R555W (non-amyloidogenic) and H572R (amyloidogenic) along with the wild-type (WT). R555W was more susceptible to acidic pH compared to H572R and displayed varying chemical stabilities with decreasing pH. Thermal denaturation studies at acidic pH showed that while WT did not undergo any conformational transition, the mutants exhibited a clear pH-dependent irreversible conversion from αβ conformation to β-sheet oligomers. The β-oligomers of both mutants were stable at physiological temperature and pH. Electron microscopy and dynamic light scattering studies showed that β-oligomers of H572R were larger compared to R555W. The β-oligomers of both mutants were cytotoxic to primary human corneal stromal fibroblast (pHCSF) cells. The β-oligomers of both mutants exhibit variations in their morphologies, sizes, thermal and chemical stabilities, aggregation patterns and cytotoxicities.
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Pathogenesis and treatments of TGFBI corneal dystrophies. Prog Retin Eye Res 2015; 50:67-88. [PMID: 26612778 DOI: 10.1016/j.preteyeres.2015.11.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/12/2015] [Accepted: 11/16/2015] [Indexed: 11/22/2022]
Abstract
Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.
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Han YP, Sim AJ, Vora SC, Huang AJW. Unique TGFBI protein in lattice corneal dystrophy. Invest Ophthalmol Vis Sci 2011; 52:8401-6. [PMID: 21948648 DOI: 10.1167/iovs.11-7618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Specific components of transforming growth factor-beta-induced protein (TGFBIp) responsible for amyloid deposits in lattice corneal dystrophy (LCD) have not been delineated. LCD has been associated with various TGFBIp mutations such as R124C, L518P, and L527R. Using recombinant TGFBIp, this study was undertaken to identify TGFBIp components potentially contributing to the protein deposits in LCD. METHODS Recombinant wild-type (WT) TGFBIp and four mutants (R124C, R124H, L518P, and L527R) were generated in HEK293FT cells. WT and mutant TGFBIp were collected from crude cell lysates or purified from culture media. Immunoblot analyses were performed with four different anti-TGFBIp antibodies raised against various regions of TGFBIp. RESULTS Consistent with the authors' previous findings, purified recombinant proteins are more prone to polymerize than crude cell lysates. As expected, all monomers and polymers of TGFBIp WT and mutants were detected by these antibodies. However, the authors noted WT and TGFBIp mutants showed differential reactivities with these antibodies. A 47-kDa band was detected in purified 2-tag proteins of L518P by all four antibodies. A unique 43-kDa band was detected in both 1-tag cell lysates and purified proteins of R124C by the authors' custom-made antibody (KE50) and a commercial anti-TGFBIp. CONCLUSIONS Based on its universal reactivity with various antibodies, the authors surmise that the 47-kDa protein is a ubiquitous TGFBIp fragment derived from the N-terminus of the L518P mutant. The fact that the 43-kDa protein fragment was present primarily in R124C and R124H but not in WT implicates its potential role in the protein deposits of LCD.
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Affiliation(s)
- Yu-Ping Han
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Weiss JS, Møller HU, Lisch W, Kinoshita S, Aldave AJ, Belin MW, Kivelä T, Busin M, Munier FL, Seitz B, Sutphin J, Bredrup C, Mannis MJ, Rapuano CJ, Van Rij G, Kim EK, Klintworth GK. The IC3D classification of the corneal dystrophies. Cornea 2008; 27 Suppl 2:S1-83. [PMID: 19337156 PMCID: PMC2866169 DOI: 10.1097/ico.0b013e31817780fb] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND The recent availability of genetic analyses has demonstrated the shortcomings of the current phenotypic method of corneal dystrophy classification. Abnormalities in different genes can cause a single phenotype, whereas different defects in a single gene can cause different phenotypes. Some disorders termed corneal dystrophies do not appear to have a genetic basis. PURPOSE The purpose of this study was to develop a new classification system for corneal dystrophies, integrating up-to-date information on phenotypic description, pathologic examination, and genetic analysis. METHODS The International Committee for Classification of Corneal Dystrophies (IC3D) was created to devise a current and accurate nomenclature. RESULTS This anatomic classification continues to organize dystrophies according to the level chiefly affected. Each dystrophy has a template summarizing genetic, clinical, and pathologic information. A category number from 1 through 4 is assigned, reflecting the level of evidence supporting the existence of a given dystrophy. The most defined dystrophies belong to category 1 (a well-defined corneal dystrophy in which a gene has been mapped and identified and specific mutations are known) and the least defined belong to category 4 (a suspected dystrophy where the clinical and genetic evidence is not yet convincing). The nomenclature may be updated over time as new information regarding the dystrophies becomes available. CONCLUSIONS The IC3D Classification of Corneal Dystrophies is a new classification system that incorporates many aspects of the traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Standardized templates provide key information that includes a level of evidence for there being a corneal dystrophy. The system is user-friendly and upgradeable and can be retrieved on the website www.corneasociety.org/ic3d.
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Affiliation(s)
- Jayne S Weiss
- Department of Ophthalmology, Kresge Eye Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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