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Shiels A. Through the Cat-Map Gateway: A Brief History of Cataract Genetics. Genes (Basel) 2024; 15:785. [PMID: 38927721 PMCID: PMC11202810 DOI: 10.3390/genes15060785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/06/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Clouding of the transparent eye lens, or cataract(s), is a leading cause of visual impairment that requires surgical replacement with a synthetic intraocular lens to effectively restore clear vision. Most frequently, cataract is acquired with aging as a multifactorial or complex trait. Cataract may also be inherited as a classic Mendelian trait-often with an early or pediatric onset-with or without other ocular and/or systemic features. Since the early 1990s, over 85 genes and loci have been genetically associated with inherited and/or age-related forms of cataract. While many of these underlying genes-including those for lens crystallins, connexins, and transcription factors-recapitulate signature features of lens development and differentiation, an increasing cohort of unpredicted genes, including those involved in cell-signaling, membrane remodeling, and autophagy, has emerged-providing new insights regarding lens homeostasis and aging. This review provides a brief history of gene discovery for inherited and age-related forms of cataract compiled in the Cat-Map database and highlights potential gene-based therapeutic approaches to delay, reverse, or even prevent cataract formation that may help to reduce the increasing demand for cataract surgery.
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Affiliation(s)
- Alan Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
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Strofaldi A, Quinn MK, Seddon AM, McManus JJ. Polymorphic protein phase transitions driven by surface anisotropy. J Chem Phys 2023; 158:014905. [PMID: 36610968 DOI: 10.1063/5.0125452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Phase transitions of proteins are strongly influenced by surface chemical modifications or mutations. Human γD-crystallin (HGD) single-mutants have been extensively studied because they are associated with the onset of juvenile cataract. However, they have also provided a rich library of molecules to examine how specific inter-protein interactions direct protein assembly, providing new insights and valuable experimental data for coarse-grained patchy-particle models. Here, we demonstrate that the addition of new inter-protein interactions by mutagenesis is additive and increases the number and variety of condensed phases formed by proteins. When double mutations incorporating two specific single point mutations are made, the properties of both single mutations are retained in addition to the formation of a new condensed phase. We find that the HGD double-mutant P23VC110M self-assembles into spherical particles with retrograde solubility, orthorhombic crystals, and needle/plate shape crystals, while retaining the ability to undergo liquid-liquid phase separation. This rich polymorphism is only partially predicted by the experimental data on the constituent single mutants. We also report a previously un-characterized amorphous protein particle, with unique properties that differ from those of protein spherulites, protein particulates previously described. The particles we observe are amorphous, reversible with temperature, tens of microns in size, and perfectly spherical. When they are grown on pristine surfaces, they appear to form by homogeneous nucleation, making them unique, and we believe a new form of protein condensate. This work highlights the challenges in predicting protein behavior, which has frustrated rational assembly and crystallization but also provides rich data to develop new coarse-grained models to explain the observed polymorphism.
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Affiliation(s)
| | - Michelle K Quinn
- Department of Chemistry Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Annela M Seddon
- HH Wills Physics Laboratory, School of Physics, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - Jennifer J McManus
- HH Wills Physics Laboratory, School of Physics, University of Bristol, Bristol BS8 1TL, United Kingdom
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Abstract
OBJECTIVE Schizophrenia (SCZ) is a debilitating disease with a complex genetic cause in which age at onset may reflect genetic vulnerability. Though there has been some association between genetic polymorphisms and age of onset, there has been little exploration of the role of epigenetic processes. We sought to explore the influence of DNA methylation, a key epigenetic mechanism, and its association with the age of onset of illness. METHODS One hundred thirty-eight participants aged 18-75 years and previously diagnosed with SCZ spectrum disorders by the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (SCID DSM-5) were recruited. Venous blood was collected and genome-wide DNA methylation was quantified using the Illumina Infinium HumanMethylation450 BeadChip array. Individual CpG sites and regions of differential methylation were explored by the age of onset; covariates included age, sex, as well as white blood cell composition. RESULTS Binary grouping (early vs. late onset) revealed four intergenic CpG sites on chromosome 2 that were above the expected P-value threshold, with hypermethylation of the CpG site cg10392614 most strongly associated with early-onset SCZ. The four most strongly associated CpG sites, including cg 10392614, were intergenic. Continuous analysis revealed the top CpG site to be cg11723066 , which is linked to the JAM3 gene, with hypomethylation associated with earlier onset; however, results were below the expected P-value threshold. CONCLUSION Studies on DNA methylation in the first-episode psychosis population may help further our understanding of the role of epigenetics in the age of onset of SCZ.
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Peng Y, Zheng Y, Deng Z, Zhang S, Tan Y, Hu Z, Tao L, Luo Y. Case Report: A de novo Variant of CRYGC Gene Associated With Congenital Cataract and Microphthalmia. Front Genet 2022; 13:866246. [PMID: 35719371 PMCID: PMC9198712 DOI: 10.3389/fgene.2022.866246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Congenital cataract is one of the most common causes of blindness in children. A rapid and accurate genetic diagnosis benefit the patients in the pediatric department. The current study aims to identify the genetic defects in a congenital cataract patient without a family history. Case presentation: A congenital cataract patient with microphthalmia and nystagmus was recruited for this study. Trio-based whole-exome sequencing revealed a de novo variant (c.394delG, p.V132Sfs*15) in CRYGC gene. According to the American College of Medical Genetics and Genomics (ACMG) criteria, the variant could be annontated as pathogenic. Conclusion: Our findings provide new knowledge of the variant spectrum of CRYGC gene and are essential for understanding the heterogeneity of cataracts in the Chinese population.
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Affiliation(s)
- Yu Peng
- Department of Ophthalmology & Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Yu Zheng
- Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Zifeng Deng
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Shuju Zhang
- Pediatrics Research Institute of Hunan Province, Hunan Children's Hospital, Changsha, China
| | - Yilan Tan
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Zhengmao Hu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, China
| | - Lijuan Tao
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
| | - Yulin Luo
- Department of Ophthalmology, Hunan Children's Hospital, Changsha, China
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Hsueh SS, Lu JH, Wu JW, Lin TH, Wang SSS. Protection of human γD-crystallin protein from ultraviolet C-induced aggregation by ortho-vanillin. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 261:120023. [PMID: 34098480 DOI: 10.1016/j.saa.2021.120023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 05/20/2021] [Accepted: 05/24/2021] [Indexed: 06/12/2023]
Abstract
Cataract is known as one of the leading causes of vision impairment worldwide. While the detailed mechanism of cataratogenesis remains unclear, cataract is believed to be correlated with the aggregation and/or misfolding of human ocular lens proteins called crystallins. A 173-residue structural protein human γD-crystallin is a major γ-crystallin protein in the human eye lens and associated with the development of juvenile and mature-onset cataracts. This work is aimed at investigating the effect of a small molecule, e.g., ortho-vanillin, on human γD-crystallin aggregation upon exposure to ultraviolet-C irradiation. According to the findings of right-angle light scattering, transmission electron microscopy, and gel electrophoresis, ortho-vanillin was demonstrated to dose-dependently suppress ultraviolet-C-triggered aggregation of human γD-crystallin. Results from the synchronous fluorescence spectroscopy, tryptophan fluorescence quenching, and molecular docking studies revealed the structural change of γD-crystallin induced by the interaction/binding between ortho-vanillin and protein. We believe the outcome from this work may contribute to the development of potential therapeutics for cataract.
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Affiliation(s)
- Shu-Shun Hsueh
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Jian-Hong Lu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Josephine W Wu
- Department of Optometry, Yuanpei University of Medical Technology, Hsinchu City 30015, Taiwan.
| | - Ta-Hsien Lin
- Basic Research Division, Medical Research Department, Taipei Veterans General Hospital, Taipei 11217, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan.
| | - Steven S-S Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan.
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Wang X, Wang D, Wang Q, Huang W, Dongye M, Zhang X, Lin D, Lin Z, Li J, Hu W, Li X, Lin X, Zhong Q, Chen W, Lin H. Broadening the Mutation Spectrum in GJA8 and CHMP4B: Novel Missense Variants and the Associated Phenotypes in Six Chinese Han Congenital Cataracts Families. Front Med (Lausanne) 2021; 8:713284. [PMID: 34722561 PMCID: PMC8554029 DOI: 10.3389/fmed.2021.713284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 09/21/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose: To broaden the mutation and phenotype spectrum of the GJA8 and CHMP4B genes and to reveal genotype-phenotype correlations in a cohort of Chinese patients with congenital cataracts (CCs). Methods: Six Chinese Han families with CCs inherited in an autosomal dominant (AD) pattern were recruited for this study. All patients underwent full ocular examinations. Genomic DNA was extracted from the leukocytes of peripheral blood collected from all available patients and their unaffected family members. Whole-exome sequencing (WES) was performed on all probands and at least one of their parents. Candidate variants were further confirmed by Sanger sequencing. Bioinformatic analysis with several computational predictive programs was performed to assess the impacts of the candidate variants on the structure and function of the proteins. Results: Four heterozygous candidate variants in three different genes (CRYBB2, GJA8, and CHMP4B) were identified in affected individuals from the six families, including two novel missense variants (GJA8: c.64G > C/p. G22R, and CHMP4B: c.587C > G/p. S196C), one missense mutation (CRYBB2: c.562C > T/p. R188C), and one small deletion (GJA8: c.426_440delGCTGGAGGGGACCCT/p.143_147delLEGTL). The three missense mutations were predicted as deleterious in all four computational prediction programs. In the homologous model, the GJA8: p.143_147delLEGTL mutation showed a sequence deletion of five amino acids at the cytoplasmic loop of the Cx50 protein, close to the third transmembrane domain. Patients carrying mutations in the same gene showed similar cataract phenotypes at a young age, including total cataracts, Y-sutural with fetal nuclear cataracts, and subcapsular cataracts. Conclusion: This study further expands the mutation spectrum and genotype-phenotype correlation of CRYBB2, GJA8, and CHMP4B underlying CCs. This study sheds light on the importance of comparing congenital cataract phenotypes in patients at the same age stage. It offers clues for the pathogenesis of CCs and allows for an early prenatal diagnosis for families carrying these genetic variants.
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Affiliation(s)
- Xun Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Dongni Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qiwei Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Weiming Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Meimei Dongye
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xulin Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Duoru Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Zhuoling Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Jing Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Weiling Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiaoyan Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Xiaoshan Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Qiuping Zhong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Weirong Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Haotian Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.,Center for Precision Medicine, Sun Yat-sen University, Guangzhou, China
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Cataract-Associated New Mutants S175G/H181Q of βΒ2-Crystallin and P24S/S31G of γD-Crystallin Are Involved in Protein Aggregation by Structural Changes. Int J Mol Sci 2020; 21:ijms21186504. [PMID: 32899552 PMCID: PMC7555777 DOI: 10.3390/ijms21186504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/21/2020] [Accepted: 09/01/2020] [Indexed: 12/15/2022] Open
Abstract
β/γ-Crystallins, the main structural protein in human lenses, have highly stable structure for keeping the lens transparent. Their mutations have been linked to cataracts. In this study, we identified 10 new mutations of β/γ-crystallins in lens proteomic dataset of cataract patients using bioinformatics tools. Of these, two double mutants, S175G/H181Q of βΒ2-crystallin and P24S/S31G of γD-crystallin, were found mutations occurred in the largest loop linking the distant β-sheets in the Greek key motif. We selected these double mutants for identifying the properties of these mutations, employing biochemical assay, the identification of protein modifications with nanoUPLC-ESI-TOF tandem MS and examining their structural dynamics with hydrogen/deuterium exchange-mass spectrometry (HDX-MS). We found that both double mutations decrease protein stability and induce the aggregation of β/γ-crystallin, possibly causing cataracts. This finding suggests that both the double mutants can serve as biomarkers of cataracts.
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Lin M, Jin Y, Chen X, Sui Y, Li Y, Li H, Ni X, Zhao N, Lu Y, Jiang M. Increased hydrophobicity of CRYGD p.(Ala159ProfsTer9): Suspected cause of congenital cataracts in a large Chinese family. Mol Genet Genomic Med 2020; 8:e1436. [PMID: 33460241 PMCID: PMC7549552 DOI: 10.1002/mgg3.1436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 12/05/2022] Open
Abstract
Objective This study aimed to identify the disease‐causing mutation of congenital cataract disease in a large northeastern Chinese family. Materials and Methods The subjects’ peripheral blood was collected, their genomic DNA was extracted, mutation screening of candidate genes was performed using polymerase chain reaction, and the amplified products were sequenced. Recombinant C‐terminal enhanced green fluorescent protein‐tagged wild‐type or mutant CRYGD was expressed in HEK293T cells, and the expression pattern was observed under a fluorescence microscope. The CRYGD protein mutation was analyzed via bioinformatics analysis. Results c.475delG, a novel frameshift mutation in CRYGD, was identified in the affected family members. This mutation causes premature termination of the polypeptide, resulting in truncated p.(Ala159ProfsTer9). According to the bioinformatics analysis results, compared with wild‐type CRYGD, p.(Ala159ProfsTer9) exhibits significantly decreased hydrophilicity. Fluorescence microscopy revealed that p.(Ala159ProfsTer9) aggregates in the cell in the form of granular deposits. Conclusion In this study, the novel frameshift mutation c.475delG, p.(Ala159ProfsTer9) in CRYGD was identified to cause congenital cataracts in a large Chinese family; increased hydrophobicity of p.(Ala159ProfsTer9) protein may be the underlying mechanism.
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Affiliation(s)
- Meina Lin
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Ying Jin
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Xinren Chen
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yu Sui
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yan Li
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Huan Li
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Xiang Ni
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Ning Zhao
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Yongping Lu
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
| | - Miao Jiang
- NHC Key Laboratory of Reproductive Health and Medical Genetics, Liaoning Research Institute of Family Planning, The Affiliated Reproductive Hospital of China Medical University, Shenyang, China
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Yang Y, Xu X, Liu Q, Huang H, Huang X, Lv H. Myricetin Prevents Cataract Formation by Inhibiting the Apoptotic Cell Death Mediated Cataractogenesis. Med Sci Monit 2020; 26:e922519. [PMID: 32335580 PMCID: PMC7199429 DOI: 10.12659/msm.922519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 01/27/2020] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The current research work aimed to explore the protective role of myricetin against cataractogenesis in humans, in terms of its anti-apoptotic potential. MATERIAL AND METHODS Human eye lens epithelial cells were exposed to oxidative stress by treating with hydrogen peroxide (H₂O₂). The levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) were determined using standard detection kits. DAPI (4',6-diamidino-2-phenylindole), AO/EB (acridine orange/ethidium bromide) and Annexin V/propidium iodide (PI) staining assays were used for the assessment of cell apoptosis. Western blotting was used to examine the protein concentrations. RESULTS The exposure of human epithelial eye lens cells to H₂O₂ led to significant accumulation of reactive oxygen species molecules. Treatment of the H₂O₂-stressed epithelial cells with myricetin caused significant (P<0.05) increased levels of SOD, CAT, and GSH. Western blot analysis also showed a significant (P<0.05) increase in the expression of SOD, CAT, and GSH levels in human epithelial eye lens cells. Additionally, myricetin administration to H₂O₂-treated epithelial eye lens cells caused a significant decline in cell apoptosis ratio. The induction of apoptosis was associated with upregulation of Bax and downregulation of Bcl-2. CONCLUSIONS The results of this study showed the potential of myricetin in protecting the apoptosis driven cataract formation in humans.
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Affiliation(s)
- Yu Yang
- Department of Ophthalmology, Nanchong Central Hospital (The Second Clinical Medical College of North Sichuan Medical College), Nanchong, Sichuan, P.R. China
| | - Xiaoxia Xu
- Department of Ophthalmology, Nanchong Central Hospital (The Second Clinical Medical College of North Sichuan Medical College), Nanchong, Sichuan, P.R. China
| | - Qi Liu
- Department of Pediatrics, Nanchong Central Hospital (The Second Clinical Medical College of North Sichuan Medical College), Nanchong, Sichuan, P.R. China
| | - Hai Huang
- Department of Ophthalmology, Nanchong Central Hospital (The Second Clinical Medical College of North Sichuan Medical College), Nanchong, Sichuan, P.R. China
| | - Xuewen Huang
- Department of Ophthalmology, Nanchong Central Hospital (The Second Clinical Medical College of North Sichuan Medical College), Nanchong, Sichuan, P.R. China
| | - Hongbin Lv
- Department of Ophthalmology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, P.R. China
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Two Pathogenic Gene Mutations Identified Associating with Congenital Cataract and Iris Coloboma Respectively in a Chinese Family. J Ophthalmol 2020; 2020:7054315. [PMID: 32148946 PMCID: PMC7049832 DOI: 10.1155/2020/7054315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 12/26/2019] [Indexed: 12/13/2022] Open
Abstract
Purpose To screen out pathogenic genes in a Chinese family with congenital cataract and iris coloboma. Material and Methods. A three-generation family with congenital cataract and iris coloboma from a Han ethnicity was recruited. DNA was extracted from peripheral blood samples collected from all individuals in the family. Whole exon sequencing was employed for screening the disease-causing gene mutations in the proband, and Sanger sequencing was used for other members of the family and a control group of 500 healthy individuals. Bioinformatics analysis and three-dimensional structure predictions were used to predict the impact of amino acid changes on protein structure and function. Results The candidate genes of cataract and iris coloboma were successfully screened out. A heterozygote mutation, CRYGD c.70C>A (p.P24T), was identified as cosegregating with congenital cataracts, while another heterozygous mutation, WFS1 c.1514G>C (p.C505S), which had not been reported previously, cosegregated with congenital iris coloboma. Bioinformatic analyses and three-dimensional structure prediction proved that the three-dimensional structures of WFS1 c.1514G>C (p.C505S), which had not been reported previously, cosegregated with congenital iris coloboma. Bioinformatic analyses and three-dimensional structure prediction proved that the three-dimensional structures of CRYGD c.70C>A (p.P24T), was identified as cosegregating with congenital cataracts, while another heterozygous mutation, Conclusions We report a novel mutation, WFS1 p.C505S, and a known mutation, CRYGD p.P24T, that cosegregate with iris coloboma and congenital cataract, respectively, in a Chinese family. This is the first time the association of WFS1 p.C505S with iris coloboma has been demonstrated, although CRYGD p.P24T has been widely reported as being associated with congenital cataract, especially in the Eastern Asian population. These findings may have future therapeutic benefit for the diagnosis of iris coloboma and congenital cataract. The results may also be relevant in further studies aiming to investigate the molecular pathogenesis of iris coloboma and congenital cataract.WFS1 c.1514G>C (p.C505S), which had not been reported previously, cosegregated with congenital iris coloboma. Bioinformatic analyses and three-dimensional structure prediction proved that the three-dimensional structures of CRYGD c.70C>A (p.P24T), was identified as cosegregating with congenital cataracts, while another heterozygous mutation, WFS1 c.1514G>C (p.C505S), which had not been reported previously, cosegregated with congenital iris coloboma. Bioinformatic analyses and three-dimensional structure prediction proved that the three-dimensional structures of CRYGD c.70C>A (p.P24T), was identified as cosegregating with congenital cataracts, while another heterozygous mutation,
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Aryal S, Anand D, Hernandez FG, Weatherbee BAT, Huang H, Reddy AP, Wilmarth PA, David LL, Lachke SA. MS/MS in silico subtraction-based proteomic profiling as an approach to facilitate disease gene discovery: application to lens development and cataract. Hum Genet 2019; 139:151-184. [PMID: 31797049 DOI: 10.1007/s00439-019-02095-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 11/24/2019] [Indexed: 12/20/2022]
Abstract
While the bioinformatics resource-tool iSyTE (integrated Systems Tool for Eye gene discovery) effectively identifies human cataract-associated genes, it is currently based on just transcriptome data, and thus, it is necessary to include protein-level information to gain greater confidence in gene prioritization. Here, we expand iSyTE through development of a novel proteome-based resource on the lens and demonstrate its utility in cataract gene discovery. We applied high-throughput tandem mass spectrometry (MS/MS) to generate a global protein expression profile of mouse lens at embryonic day (E)14.5, which identified 2371 lens-expressed proteins. A major challenge of high-throughput expression profiling is identification of high-priority candidates among the thousands of expressed proteins. To address this problem, we generated new MS/MS proteome data on mouse whole embryonic body (WB). WB proteome was then used as a reference dataset for performing "in silico WB-subtraction" comparative analysis with the lens proteome, which effectively identified 422 proteins with lens-enriched expression at ≥ 2.5 average spectral counts, ≥ 2.0 fold enrichment (FDR < 0.01) cut-off. These top 20% candidates represent a rich pool of high-priority proteins in the lens including known human cataract-linked genes and many new potential regulators of lens development and homeostasis. This rich information is made publicly accessible through iSyTE (https://research.bioinformatics.udel.edu/iSyTE/), which enables user-friendly visualization of promising candidates, thus making iSyTE a comprehensive tool for cataract gene discovery.
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Affiliation(s)
- Sandeep Aryal
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Deepti Anand
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Francisco G Hernandez
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Bailey A T Weatherbee
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA
| | - Hongzhan Huang
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, 19716, USA
| | - Ashok P Reddy
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Phillip A Wilmarth
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Larry L David
- Proteomics Shared Resource, Oregon Health and Science University, Portland, OR, 97239, USA
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, 105 The Green, Delaware Avenue, 236 Wolf Hall, Newark, DE, USA.
- Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, 19716, USA.
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12
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Khan AR, James S, Quinn MK, Altan I, Charbonneau P, McManus JJ. Temperature-Dependent Interactions Explain Normal and Inverted Solubility in a γD-Crystallin Mutant. Biophys J 2019; 117:930-937. [PMID: 31422822 PMCID: PMC6731388 DOI: 10.1016/j.bpj.2019.07.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/04/2019] [Accepted: 07/08/2019] [Indexed: 11/30/2022] Open
Abstract
Protein crystal production is a major bottleneck in the structural characterization of proteins. To advance beyond large-scale screening, rational strategies for protein crystallization are crucial. Understanding how chemical anisotropy (or patchiness) of the protein surface, due to the variety of amino-acid side chains in contact with solvent, contributes to protein-protein contact formation in the crystal lattice is a major obstacle to predicting and optimizing crystallization. The relative scarcity of sophisticated theoretical models that include sufficient detail to link collective behavior, captured in protein phase diagrams, and molecular-level details, determined from high-resolution structural information, is a further barrier. Here, we present two crystal structures for the P23T + R36S mutant of γD-crystallin, each with opposite solubility behavior: one melts when heated, the other when cooled. When combined with the protein phase diagram and a tailored patchy particle model, we show that a single temperature-dependent interaction is sufficient to stabilize the inverted solubility crystal. This contact, at the P23T substitution site, relates to a genetic cataract and reveals at a molecular level the origin of the lowered and retrograde solubility of the protein. Our results show that the approach employed here may present a productive strategy for the rationalization of protein crystallization.
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Affiliation(s)
- Amir R Khan
- School of Biochemistry and Immunology, Trinity College Dublin, Dublin, Ireland
| | - Susan James
- Department of Chemistry, Maynooth University, Maynooth, Ireland
| | | | - Irem Altan
- Department of Chemistry, Duke University, Durham, North Carolina
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13
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Quinn MK, James S, McManus JJ. Chemical Modification Alters Protein-Protein Interactions and Can Lead to Lower Protein Solubility. J Phys Chem B 2019; 123:4373-4379. [PMID: 31046277 DOI: 10.1021/acs.jpcb.9b02368] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The chemical modification of proteins is at the frontier of developments in biological imaging and biopharmaceutics. With the advent of more sensitive and higher resolution imaging techniques, researchers increasingly rely on the functionalization of proteins to enable these techniques to capture cellular processes. For biopharmaceutical therapies, chemically modified proteins, for example, antibody-drug conjugates (ADCs) offer the possibility of more tailored treatments for the disease with lower toxicities than traditional small molecule therapies. However, relatively little consideration is paid to how chemical modifications impact protein-protein interactions and solution stability. Using human γD-crystallin as a model, we demonstrate that chemical modification of the protein surface alters protein-protein interactions, which can result in lower solubility depending on the chemical nature of the modifier and the position on the protein where the modification is made. Understanding these effects is essential to ensure that modifying proteins effectively occurs with minimum self-association and that studies carried out using labeled proteins accurately reflect those of unmodified proteins.
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Affiliation(s)
- Michelle K Quinn
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
| | - Susan James
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
| | - Jennifer J McManus
- Department of Chemistry , Maynooth University , Maynooth , Co. Kildare , Ireland
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14
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Li CT, How SC, Chen ME, Lo CH, Chun MC, Chang CK, Chen WA, Wu JW, Wang SSS. Effects of glycation on human γd-crystallin proteins by different glycation-inducing agents. Int J Biol Macromol 2018; 118:442-451. [DOI: 10.1016/j.ijbiomac.2018.06.108] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 06/17/2018] [Accepted: 06/22/2018] [Indexed: 01/22/2023]
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15
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Reis LM, Semina EV. Genetic landscape of isolated pediatric cataracts: extreme heterogeneity and variable inheritance patterns within genes. Hum Genet 2018; 138:847-863. [PMID: 30187164 DOI: 10.1007/s00439-018-1932-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 08/29/2018] [Indexed: 12/12/2022]
Abstract
Pediatric cataract represents an important cause of pediatric visual impairment. While both genetic and environmental causes for pediatric cataract are known, a large proportion remains idiopathic. The purpose of this review is to discuss genes involved in isolated pediatric cataract, with a focus on variable inheritance patterns within genes. Mutations in over 52 genes are known to cause isolated pediatric cataract, with a major contribution from genes encoding for crystallins, transcription factors, membrane proteins, and cytoskeletal proteins. Interestingly, both dominant and recessive inheritance patterns have been reported for mutations in 13 different cataract genes. For some genes, dominant and recessive alleles represent distinct types of mutations, but for many, especially missense variants, there are no clear patterns to distinguish between dominant and recessive alleles. Further research into the functional effects of these mutations, as well as additional data on the frequency of the identified variants, is needed to clarify variant pathogenicity. Exome sequencing continues to be successful in identifying novel genes associated with congenital cataract but is hindered by the extreme genetic heterogeneity of this condition. The large number of idiopathic cases suggests that more genes and potentially novel mechanisms of gene disruption remain to be identified.
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Affiliation(s)
- Linda M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Elena V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. .,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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16
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Zhou HX, Pang X. Electrostatic Interactions in Protein Structure, Folding, Binding, and Condensation. Chem Rev 2018; 118:1691-1741. [PMID: 29319301 DOI: 10.1021/acs.chemrev.7b00305] [Citation(s) in RCA: 485] [Impact Index Per Article: 80.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Charged and polar groups, through forming ion pairs, hydrogen bonds, and other less specific electrostatic interactions, impart important properties to proteins. Modulation of the charges on the amino acids, e.g., by pH and by phosphorylation and dephosphorylation, have significant effects such as protein denaturation and switch-like response of signal transduction networks. This review aims to present a unifying theme among the various effects of protein charges and polar groups. Simple models will be used to illustrate basic ideas about electrostatic interactions in proteins, and these ideas in turn will be used to elucidate the roles of electrostatic interactions in protein structure, folding, binding, condensation, and related biological functions. In particular, we will examine how charged side chains are spatially distributed in various types of proteins and how electrostatic interactions affect thermodynamic and kinetic properties of proteins. Our hope is to capture both important historical developments and recent experimental and theoretical advances in quantifying electrostatic contributions of proteins.
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Affiliation(s)
- Huan-Xiang Zhou
- Department of Chemistry and Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.,Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
| | - Xiaodong Pang
- Department of Physics and Institute of Molecular Biophysics, Florida State University , Tallahassee, Florida 32306, United States
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17
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Segregation of a novel p.(Ser270Tyr) MAF mutation and p.(Tyr56∗) CRYGD variant in a family with dominantly inherited congenital cataracts. Mol Biol Rep 2017; 44:435-440. [DOI: 10.1007/s11033-017-4121-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 08/19/2017] [Indexed: 12/17/2022]
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18
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Chaudhury S, Bag S, Bose M, Das AK, Ghosh AK, Dasgupta S. Protection of human γB-crystallin from UV-induced damage by epigallocatechin gallate: spectroscopic and docking studies. MOLECULAR BIOSYSTEMS 2017; 12:2901-9. [PMID: 27410057 DOI: 10.1039/c6mb00256k] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The transparency of the human eye lens depends on the solubility and stability of the structural proteins of the eye lens, the crystallins. Although the mechanism of cataract formation is still unclear, it is believed to involve protein misfolding and/or aggregation of proteins due to the influence of several external factors such as ultraviolet (UV) radiation, low pH, temperature and exposure to chemical agents. In this article, we report the study of UV induced photo-damage (under oxidative stress) of recombinant human γB-crystallin in vitro in the presence of the major green tea polyphenol, (-)-epigallocatechin gallate (EGCG). We have shown that EGCG has the ability to protect human γB-crystallin from oxidative stress-induced photo-damage.
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Affiliation(s)
| | - Sudipta Bag
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
| | - Madhuparna Bose
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Amit Kumar Das
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Ananta Kumar Ghosh
- Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Swagata Dasgupta
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, India.
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19
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Whitley MJ, Xi Z, Bartko JC, Jensen MR, Blackledge M, Gronenborn AM. A Combined NMR and SAXS Analysis of the Partially Folded Cataract-Associated V75D γD-Crystallin. Biophys J 2017; 112:1135-1146. [PMID: 28355541 DOI: 10.1016/j.bpj.2017.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/03/2017] [Accepted: 02/08/2017] [Indexed: 11/19/2022] Open
Abstract
A cataract is a pathological condition characterized by the clouding of the normally clear eye lens brought about by deposition of crystallin proteins in the lens fiber cells. These protein aggregates reduce visual acuity by scattering or blocking incoming light. Chemical damage to proteins of the crystallin family, accumulated over a lifetime, leads to age-related cataract, whereas inherited mutations are associated with congenital or early-onset cataract. The V75D mutant of γD-crystallin is associated with congenital cataract in mice and was previously shown to un/fold via a partially folded intermediate. Here, we structurally characterized the stable equilibrium urea unfolding intermediate of V75D at the ensemble level using solution NMR and small-angle x-ray scattering. Our data show that, in the intermediate, the C-terminal domain retains a folded conformation that is similar to the native wild-type protein, whereas the N-terminal domain is unfolded and comprises an ensemble of random conformers, without any detectable residual structural propensities.
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Affiliation(s)
- Matthew J Whitley
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Zhaoyong Xi
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jonathan C Bartko
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | | | - Martin Blackledge
- Institut de Biologie Structurale, CEA, CNRS, Université Grenoble Alpes, Grenoble, France
| | - Angela M Gronenborn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
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20
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Chaudhury S, Ghosh P, Parveen S, Dasgupta S. Glycation of human γB-crystallin: A biophysical investigation. Int J Biol Macromol 2017; 96:392-402. [DOI: 10.1016/j.ijbiomac.2016.12.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 11/28/2022]
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21
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Messina-Baas O, Cuevas-Covarrubias SA. Inherited Congenital Cataract: A Guide to Suspect the Genetic Etiology in the Cataract Genesis. Mol Syndromol 2017; 8:58-78. [PMID: 28611546 DOI: 10.1159/000455752] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2016] [Indexed: 01/23/2023] Open
Abstract
Cataracts are the principal cause of treatable blindness worldwide. Inherited congenital cataract (CC) shows all types of inheritance patterns in a syndromic and nonsyndromic form. There are more than 100 genes associated with cataract with a predominance of autosomal dominant inheritance. A cataract is defined as an opacity of the lens producing a variation of the refractive index of the lens. This variation derives from modifications in the lens structure resulting in light scattering, frequently a consequence of a significant concentration of high-molecular-weight protein aggregates. The aim of this review is to introduce a guide to identify the gene involved in inherited CC. Due to the manifold clinical and genetic heterogeneity, we discarded the cataract phenotype as a cardinal sign; a 4-group classification with the genes implicated in inherited CC is proposed. We consider that this classification will assist in identifying the probable gene involved in inherited CC.
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22
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Yang G, Chen Z, Zhang W, Liu Z, Zhao J. Novel mutations in CRYGD are associated with congenital cataracts in Chinese families. Sci Rep 2016; 6:18912. [PMID: 26732753 PMCID: PMC4702117 DOI: 10.1038/srep18912] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/30/2015] [Indexed: 11/26/2022] Open
Abstract
Congenital cataract disease is a clinically and genetically heterogeneous lens disorder. The purpose of this study was to identify the genetic defects and to investigate the relationships between disease-causing genes and lens morphology in congenital cataracts. Patients were given a physical examination, and their blood samples were collected for DNA extraction. Mutation analysis was performed by direct sequencing of the following candidate genes: CRYGC, CRYGD, CRYGS, GJA8, GJA3 and CRYAA. Mutational analysis of CRYGD identified a recurrent (p.P24T) mutation in two unrelated families with congenital coralliform cataracts and three novel (p.Q101X, p.E104fsX4 and p.E135X) mutations in three families with congenital nuclear cataracts. The p.E135X mutation is a de novo mutation. Haplotype analysis showed patients inherited the same CRYGD allele originated from father. The p.E135X mutation seen in two siblings suggests a mechanism of gonadal mosaicism in the father.
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Affiliation(s)
- Guoxing Yang
- Department of Opthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, China.,Department of Opthalmology, Hebei Provincial Ophthalmic Hospital, Hebei, China.,Hebei Provincial Key laboratory of ophthalmology, Hebei, China
| | - Zhimin Chen
- Department of Opthalmology, Hebei Provincial Ophthalmic Hospital, Hebei, China
| | - Wulin Zhang
- Department of Opthalmology, Hebei Provincial Ophthalmic Hospital, Hebei, China
| | - Zhiqiang Liu
- Department of Opthalmology, Hebei Provincial Ophthalmic Hospital, Hebei, China
| | - Jialiang Zhao
- Department of Opthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences &Peking Union Medical College, Beijing, China
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23
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Vendra VPR, Khan I, Chandani S, Muniyandi A, Balasubramanian D. Gamma crystallins of the human eye lens. Biochim Biophys Acta Gen Subj 2015; 1860:333-43. [PMID: 26116913 DOI: 10.1016/j.bbagen.2015.06.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/08/2015] [Accepted: 06/19/2015] [Indexed: 01/12/2023]
Abstract
BACKGROUND Protein crystallins co me in three types (α, β and γ) and are found predominantly in the eye, and particularly in the lens, where they are packed into a compact, plastic, elastic, and transparent globule of proper refractive power range that aids in focusing incoming light on to the retina. Of these, the γ-crystallins are found largely in the nuclear region of the lens at very high concentrations (>400 mg/ml). The connection between their structure and inter-molecular interactions and lens transparency is an issue of particular interest. SCOPE OF REVIEW We review the origin and phylogeny of the gamma crystallins, their special structure involving the use of Greek key supersecondary structural motif, and how they aid in offering the appropriate refractive index gradient, intermolecular short range attractive interactions (aiding in packing them into a transparent ball), the role that several of the constituent amino acid residues play in this process, the thermodynamic and kinetic stability and how even single point mutations can upset this delicate balance and lead to intermolecular aggregation, forming light-scattering particles which compromise transparency. We cite several examples of this, and illustrate this by cloning, expressing, isolating and comparing the properties of the mutant protein S39C of human γS-crystallin (associated with congenital cataract-microcornea), with those of the wild type molecule. In addition, we note that human γ-crystallins are also present in other parts of the eye (e.g., retina), where their functions are yet to be understood. MAJOR CONCLUSIONS There are several 'crucial' residues in and around the Greek key motifs which are essential to maintain the compact architecture of the crystallin molecules. We find that a mutation that replaces even one of these residues can lead to reduction in solubility, formation of light-scattering particles and loss of transparency in the molecular assembly. GENERAL SIGNIFICANCE Such a molecular understanding of the process helps us construct the continuum of genotype-molecular structural phenotype-clinical (pathological) phenotype. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
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Affiliation(s)
- Venkata Pulla Rao Vendra
- Ophthalmic Molecular Genetics Section, National Eye Institute, Building 5635FL, Room 1S24, 5625 Fishers Lane, Rockville, MD 20852, United States.
| | - Ismail Khan
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad 500034 Telangana, India.
| | - Sushil Chandani
- Plot 32, LIC Colony, W Marredpally, Secunderabad 500026, Telangana, India.
| | - Anbukkarasi Muniyandi
- Department of Animal Science, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India.
| | - Dorairajan Balasubramanian
- Prof. Brien Holden Eye Research Centre, Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad 500034 Telangana, India.
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24
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SIPA1L3 identified by linkage analysis and whole-exome sequencing as a novel gene for autosomal recessive congenital cataract. Eur J Hum Genet 2015; 23:1627-33. [PMID: 25804400 DOI: 10.1038/ejhg.2015.46] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 02/10/2015] [Accepted: 02/11/2015] [Indexed: 12/25/2022] Open
Abstract
Congenital cataract (CC) is one of the most important causes for blindness or visual impairment in infancy. A substantial proportion of isolated CCs has monogenic causes. The disease is genetically heterogeneous, and all Mendelian modes of inheritance have been reported. We mapped a locus for isolated CC on 19p13.1-q13.2 in a distantly consanguineous German family with two sisters affected by dense white cataracts. Whole-exome sequencing identified a homozygous nonsense variant c.4489C>T (p.(R1497*)) in SIPA1L3 (signal-induced proliferation-associated 1 like 3) in both affected children. SIPA1L3 encodes a GTPase-activating protein (GAP), which interacts with small GTPases of the Rap family via its Rap-GAP-domain. The suggested role of Rap GTPases in cell growth, differentiation and organization of the cytoskeleton in the human lens, and lens-enriched expression of the murine ortholog gene Sipa1l3 in embryonic mice indicates that this gene is crucial for early lens development. Our results provide evidence that sequence variants in human SIPA1L3 cause autosomal recessive isolated CC and give new insight into the molecular pathogenesis underlying human cataracts.
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25
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Hu Y, Gao L, Feng Y, Yang T, Huang S, Shao Z, Yuan H. Identification of a novel mutation of the gene for gap junction protein α3 (GJA3) in a Chinese family with congenital cataract. Mol Biol Rep 2014; 41:4753-8. [PMID: 24728566 DOI: 10.1007/s11033-014-3346-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 03/24/2014] [Indexed: 11/28/2022]
Abstract
Cataract, defined as any opacity of the crystallin lens, can be divided into early onset (congenital or infantile) and age-related. It is the leading cause of visual disability in children, and mutations in many genes have currently been linked with this disorder. In the present study, we identified a genetic defect in a Chinese family with congenital cataract. Genomic DNA was extracted from the venous blood of the family and 100 normal controls. To screen for the disease-causing mutation, we sequenced eight candidate genes, and to predict the functional consequences of the mutation, a structural model of the protein was developed using the Protein Data Bank and PyMOL 1.1r1. We found a novel variant (c.163 A > G transition) in the gene for gap junction protein α3, or the connexin46 gene. This mutation resulted in the substitution of a highly conserved asparagine at codon 55 by aspartic acid (p.N55D). There were no nucleotide polymorphisms in the other candidate genes sequenced.
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Affiliation(s)
- Ying Hu
- Department of Ophthalmology, the 2nd Affiliated Hospital of Harbin Medical University, 246 XuefuRoad, Harbin, 150086, Heilongjiang, China
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26
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Zhai Y, Li J, Zhu Y, Xia Y, Wang W, Yu Y, Yao K. A nonsense mutation of γD-crystallin associated with congenital nuclear and posterior polar cataract in a Chinese family. Int J Med Sci 2014; 11:158-63. [PMID: 24465161 PMCID: PMC3894400 DOI: 10.7150/ijms.7567] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 12/17/2013] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE The goal of this study was to characterize the disease-causing mutations in a Chinese family with congenital nuclear and posterior polar cataracts. METHODS Clinical data of patients in the family were recorded using slit-lamp photography and high definition video. Genomic DNA samples were extracted from the peripheral blood of the pedigree members and 100 healthy controls. Mutation screening was performed in the candidate genes by bi-directional sequencing of the amplified products. RESULTS The congenital cataract phenotype of the pedigree was identified by slit-lamp examinations and observation during surgery as nuclear and posterior polar cataracts. Through the sequencing of the candidate genes, a heterozygous c. 418C>T change was detected in the coding region of the γD-crystallin gene (CRYGD). As a result of this change, a highly conserved arginine residue was replaced by a stop codon (p. R140X). This change was discovered among all of the affected individuals with cataracts, but not among the unaffected family members or the 100 ethnically matched controls. CONCLUSIONS This study identified a novel congenital nuclear and posterior polar cataract phenotype caused by the recurrent mutation p. R140X in CRYGD.
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Affiliation(s)
- Yi Zhai
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
| | - Jinyu Li
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
| | - Yanan Zhu
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
| | - Yan Xia
- 3. Center for Structural Biology and Department of Chemistry and the Institute for Chemical Biology, Vanderbilt University Medical Center, USA
| | - Wei Wang
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
| | - Yinhui Yu
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
| | - Ke Yao
- 1. Eye Center, Second Affiliated Hospital of Medical College, Zhejiang University, Hangzhou, Zhejiang, China ; 2. Key Laboratory of Ophthalmology of Zhejiang Province, China
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27
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Wu JWR, Kao CY, Lin LTW, Wen WS, Lai JT, Wang SSS. Human γD-crystallin aggregation induced by ultraviolet C irradiation is suppressed by resveratrol. Biochem Eng J 2013. [DOI: 10.1016/j.bej.2013.03.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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28
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Moran SD, Zhang TO, Decatur SM, Zanni MT. Amyloid fiber formation in human γD-Crystallin induced by UV-B photodamage. Biochemistry 2013; 52:6169-81. [PMID: 23957864 DOI: 10.1021/bi4008353] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
γD-Crystallin is an abundant structural protein of the lens that is found in native and modified forms in cataractous aggregates. We establish that UV-B irradiation of γD-Crystallin leads to structurally specific modifications and precipitation via two mechanisms: amorphous aggregates and amyloid fibers. UV-B radiation causes cleavage of the backbone, in large measure near the interdomain interface, where side chain oxidations are also concentrated. 2D IR spectroscopy and expressed protein ligation localize fiber formation exclusively to the C-terminal domain of γD-Crystallin. The native β-sandwich domains are not retained upon precipitation by either mechanism. The similarities between the amyloid forming pathways when induced by either UV-B radiation or low pH suggest that the propensity for the C-terminal β-sandwich domain to form amyloid β-sheets determines the misfolding pathway independent of the mechanism of denaturation.
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Affiliation(s)
- Sean D Moran
- Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, WI, United States 53706
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29
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A CRYGC gene mutation associated with autosomal dominant pulverulent cataract. Gene 2013; 529:181-5. [PMID: 23954869 DOI: 10.1016/j.gene.2013.07.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 06/07/2013] [Accepted: 07/08/2013] [Indexed: 11/17/2022]
Abstract
PURPOSE To describe at molecular level a family with pulverulent congenital cataract associated with a CRYGC gene mutation. METHODS One family with several affected members with pulverulent congenital cataract and 230 healthy controls were examined. Genomic DNA from leukocytes was isolated to analyze the CRYGA-D cluster, CX46, CX50 and MIP genes through high-resolution melting curve and DNA sequencing. RESULTS DNA sequencing in the affected members revealed the c.143G>A mutation (p.R48H) in exon 2 of the CRYGC gene; 230 healthy controls and ten healthy relatives were also analyzed and none of them showed the c.143G>A mutation. No other polymorphisms or mutations were found to be present. CONCLUSION In the present study, we described a family with pulverulent congenital cataract that segregated the c.143G>A mutation (p.R48H) in the CRYGC gene. A few mutations have been described in the CRYGC gene in autosomal dominant cataract, none of them with pulverulent cataract making clear the clinical heterogeneity of congenital cataract. This mutation has been associated with the phenotype of congenital cataract but also is considered an SNP in the NCBI data base. Our data and previous report suggest that p.R48H could be a disease-causing mutation and not an SNP.
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30
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Structural integrity of the Greek key motif in βγ-crystallins is vital for central eye lens transparency. PLoS One 2013; 8:e70336. [PMID: 23936409 PMCID: PMC3735602 DOI: 10.1371/journal.pone.0070336] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/13/2013] [Indexed: 11/19/2022] Open
Abstract
Background We highlight an unrecognized physiological role for the Greek key motif, an evolutionarily conserved super-secondary structural topology of the βγ-crystallins. These proteins constitute the bulk of the human eye lens, packed at very high concentrations in a compact, globular, short-range order, generating transparency. Congenital cataract (affecting 400,000 newborns yearly worldwide), associated with 54 mutations in βγ-crystallins, occurs in two major phenotypes nuclear cataract, which blocks the central visual axis, hampering the development of the growing eye and demanding earliest intervention, and the milder peripheral progressive cataract where surgery can wait. In order to understand this phenotypic dichotomy at the molecular level, we have studied the structural and aggregation features of representative mutations. Methods Wild type and several representative mutant proteins were cloned, expressed and purified and their secondary and tertiary structural details, as well as structural stability, were compared in solution, using spectroscopy. Their tendencies to aggregate in vitro and in cellulo were also compared. In addition, we analyzed their structural differences by molecular modeling in silico. Results Based on their properties, mutants are seen to fall into two classes. Mutants A36P, L45PL54P, R140X, and G165fs display lowered solubility and structural stability, expose several buried residues to the surface, aggregate in vitro and in cellulo, and disturb/distort the Greek key motif. And they are associated with nuclear cataract. In contrast, mutants P24T and R77S, associated with peripheral cataract, behave quite similar to the wild type molecule, and do not affect the Greek key topology. Conclusion When a mutation distorts even one of the four Greek key motifs, the protein readily self-aggregates and precipitates, consistent with the phenotype of nuclear cataract, while mutations not affecting the motif display ‘native state aggregation’, leading to peripheral cataract, thus offering a protein structural rationale for the cataract phenotypic dichotomy “distort motif, lose central vision”.
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Association between a Tetranucleotide Repeat Polymorphism of SPAG16 Gene and Cataract in Male Children. J Biomark 2013; 2013:810395. [PMID: 26317022 PMCID: PMC4437386 DOI: 10.1155/2013/810395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 08/13/2012] [Indexed: 11/17/2022] Open
Abstract
Purpose. Studies involving genotyping of STR markers at 2q34 have repeatedly found the region to host the disease haplotype for pediatric cataract. Present study investigated the association of D2S2944 marker, in sperm associated antigen 16 (SPAG16) gene and rs2289917 polymorphism, in γ-crystallin B gene, with childhood cataract. Methods. 97 pediatric cataract cases and 110 children with no ocular defects were examined for tetranucleotide repeat marker/SNP using PCR-SSLP/RFLP techniques. Polymorphisms were assessed for association using contingency tables and linkage disequilibrium among alleles of the markers was estimated. Energy-optimization program predicted the secondary structure models of repeats of D2S2944. Results. Seven alleles of D2S2944, with 9–15 “GATA” repeats, were observed. Frequency of the longer allele of D2S2944, ≥(GATA)13 repeats, was 0.73 in cases and 0.56 in controls (P = 0.0123). Male children bearing ≥(GATA)13 repeats showed >3-fold higher risk for cataract (CI95% = 1.43–7.00, P = 0.0043, Pc = 0.0086) as compared to female children (OR = 1.19, CI95% = 0.49–2.92, P = 0.70). Cases with haplotype—≥(GATA)13 of D2S2944 and “C” allele rs2289917—have a higher risk for pediatric cataract (OR = 2.952, CI95% = 1.595~5.463, P = 0.000453). >(GATA)13 repeats formed energetically more favorable stem-loop structure. Conclusion. Intragenic microsatellite repeat expansion in SPAG16 gene increases predisposition to pediatric cataract by probably interfering posttranscriptional events and affecting the expression of adjacent lens transparency gene/s in a gender bias manner.
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AlFadhli S, Abdelmoaty S, Al-Hajeri A, Behbehani A, Alkuraya F. Novel crystallin gamma B mutations in a Kuwaiti family with autosomal dominant congenital cataracts reveal genetic and clinical heterogeneity. Mol Vis 2012; 18:2931-6. [PMID: 23288985 PMCID: PMC3533929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 12/07/2012] [Indexed: 12/03/2022] Open
Abstract
PURPOSE To explore the disease locus and causative mutation for autosomal dominant congenital cataracts (ADCC) in a Kuwaiti family. There were seven affected and three unaffected subjects in the family. METHODS Whole-genome linkage analysis was performed using Gene Chip Human Mapping 250 K Arrays to identify regions of linkage. Potential genes within this region were cloned and sequenced to identify the disease-causing mutation. RESULTS The highest logarithm of odds score (1.5) region 2q34-36.1, spanning the crystallin beta A2 (CRYBA2) gene, showed no sequence changes. Thus, the second highest logarithm of odds score (1.49) region, 2q33-37, spanning the gamma crystalline gene cluster (CRYG), was considered. Sequencing of the CRYGA, B, C, and D genes revealed two novel heterozygous deletions and one trinucleotide polymorphism in the CRYGB gene. These mutations included a heterozygous g.67delG, intron 1 deletion in four of the affected family members with lamellar cataracts and a heterozygous g.167delC, exon 2 deletion inherited from the Egyptian grandmother by her granddaughter, resulting in anterior polar cataracts. Another patient with complete cataracts was a compound heterozygote with both of the above-mentioned mutations. In addition, the novel trinucleotide polymorphism g.20-22 GGT>AAA was detected in three of the family members. CONCLUSIONS We report the linkage of ADCC to chromosome 2q33-37, which spans the CRYGB gene. This study is the first to report complex heterogeneous mutations in the CRYGB gene resulting in ADCC with three distinct phenotypes (lamellar, anterior polar, and complete cataracts) in the same family.
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Affiliation(s)
- Suad AlFadhli
- Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Kuwait University, Kuwait
| | | | - Amal Al-Hajeri
- Department of Medical Laboratory Sciences, Faculty of Allied Health Sciences, Kuwait University, Kuwait
| | - Abdulmutalib Behbehani
- Al Bahar Eye Centre, Ministry of Health, Kuwait,Department of surgery, Faculty of Medicine, Kuwait University, Kuwait
| | - Fowzan Alkuraya
- College of Medicine -AlFaisal University, Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
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Abstract
Crystallins are the abundant, long-lived proteins of the eye lens. The major human crystallins belong to two different superfamilies: the small heat-shock proteins (α-crystallins) and the βγ-crystallins. During evolution, other proteins have sometimes been recruited as crystallins to modify the properties of the lens. In the developing human lens, the enzyme betaine-homocysteine methyltransferase serves such a role. Evolutionary modification has also resulted in loss of expression of some human crystallin genes or of specific splice forms. Crystallin organization is essential for lens transparency and mutations; even minor changes to surface residues can cause cataract and loss of vision.
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Affiliation(s)
- Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-0608, USA.
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Solomon BD, Hadley DW, Pineda-Alvarez DE, Kamat A, Teer JK, Cherukuri PF, Hansen NF, Cruz P, Young AC, Berkman BE, Chandrasekharappa SC, Mullikin JC, Mullikin JC. Incidental medical information in whole-exome sequencing. Pediatrics 2012; 129:e1605-11. [PMID: 22585771 PMCID: PMC3362899 DOI: 10.1542/peds.2011-0080] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Genomic technologies, such as whole-exome sequencing, are a powerful tool in genetic research. Such testing yields a great deal of incidental medical information, or medical information not related to the primary research target. We describe the management of incidental medical information derived from whole-exome sequencing in the research context. We performed whole-exome sequencing on a monozygotic twin pair in which only 1 child was affected with congenital anomalies and applied an institutional review board-approved algorithm to determine what genetic information would be returned. Whole-exome sequencing identified 79525 genetic variants in the twins. Here, we focus on novel variants. After filtering artifacts and excluding known single nucleotide polymorphisms and variants not predicted to be pathogenic, the twins had 32 novel variants in 32 genes that were felt to be likely to be associated with human disease. Eighteen of these novel variants were associated with recessive disease and 18 were associated with dominantly manifesting conditions (variants in some genes were potentially associated with both recessive and dominant conditions), but only 1 variant ultimately met our institutional review board-approved criteria for return of information to the research participants.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Benjamin E. Berkman
- Department of Bioethics, Clinical Center, and Office of the Clinical Director, and
| | - Settara C. Chandrasekharappa
- Cancer Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
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VanderVeen DK, Andrews C, Nihalani BR, Engle EC. Crystalline cataract caused by a heterozygous missense mutation in γD-crystallin (CRYGD). Mol Vis 2011; 17:3333-8. [PMID: 22219628 PMCID: PMC3247172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 12/14/2011] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To describe phenotypic characteristics of two pedigrees manifesting early onset crystalline cataract with mutations in the γD-crystallin gene (CRYGD). METHODS A detailed medical history was obtained from two Caucasian pedigrees manifesting autosomal dominant congenital cataracts. Genomic DNA was extracted from saliva (DNA Genotek). Single Nucleotide Polymorphism (SNP) based genome analysis of the larger pedigree revealed linkage to an 8.2 MB region on chromosome 2q33-q35 which encompassed the crystallin-gamma gene cluster (CRYG). Exons and flanking introns of CRYGA, CRYGB, CRYGC and CRYGD were amplified and sequenced to identify disease-causing mutations. RESULTS A morphologically unique cataract with extensive refractile "crystals" scattered throughout the nucleus and perinuclear cortex was found in the probands from both pedigrees. A heterozygous C→A mutation was identified at position 109 of the coding sequence (R36S of the processed protein) in exon 2 of CRYGD and this missense mutation was found to cosegregate with the disease in the larger family; this mutation was then identified in affected individuals of pedigree 2 as well. CONCLUSIONS The heterozygous 109C→A CRYGD missense mutation is associated with a distinct crystalline cataract in two US Caucasian pedigrees. This confirms crystalline cataract formation with this mutation, as previously reported in sporadic childhood case from the Czech Republic and in members of a Chinese family.
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Affiliation(s)
- Deborah K. VanderVeen
- Department of Ophthalmology, Children's Hospital Boston, Harvard Medical School, Boston MA
| | - Caroline Andrews
- Department of Neurology, M Kirby Neurobiology Center, and The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Harvard Medical School, Boston, MA,Howard Hughes Medical Institute, Chevy Chase MD
| | - Bharti R. Nihalani
- Department of Ophthalmology, Children's Hospital Boston, Harvard Medical School, Boston MA
| | - Elizabeth C. Engle
- Department of Ophthalmology, Children's Hospital Boston, Harvard Medical School, Boston MA,Department of Neurology, M Kirby Neurobiology Center, and The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Harvard Medical School, Boston, MA,Howard Hughes Medical Institute, Chevy Chase MD
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Wang B, Yu C, Xi YB, Cai HC, Wang J, Zhou S, Zhou S, Wu Y, Yan YB, Ma X, Xie L. A novel CRYGD mutation (p.Trp43Arg) causing autosomal dominant congenital cataract in a Chinese family. Hum Mutat 2011; 32:E1939-47. [PMID: 21031598 PMCID: PMC3035819 DOI: 10.1002/humu.21386] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To identify the genetic defect associated with autosomal dominant congenital nuclear cataract in a Chinese family, molecular genetic investigation via haplotype analysis and direct sequencing were performed Sequencing of the CRYGD gene revealed a c.127T>C transition, which resulted in a substitution of a highly conserved tryptophan with arginine at codon 43 (p.Trp43Arg). This mutation co-segregated with all affected individuals and was not observed in either unaffected family members or in 200 normal unrelated individuals. Biophysical studies indicated that the p.Trp43Arg mutation resulted in significant tertiary structural changes. The mutant protein was much less stable than the wild-type protein, and was more prone to aggregate when subjected to environmental stresses such as heat and UV irradiation. © 2010 Wiley-Liss, Inc.
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Affiliation(s)
- Binbin Wang
- Shandong Eye Institute, Qingdao University Eye College, China
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Wen WS, Hsieh MC, Wang SSS. High-level expression and purification of human γD-crystallin in Escherichia coli. J Taiwan Inst Chem Eng 2011. [DOI: 10.1016/j.jtice.2010.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Zhang W, Cai HC, Li FF, Xi YB, Ma X, Yan YB. The congenital cataract-linked G61C mutation destabilizes γD-crystallin and promotes non-native aggregation. PLoS One 2011; 6:e20564. [PMID: 21655238 PMCID: PMC3105094 DOI: 10.1371/journal.pone.0020564] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Accepted: 05/03/2011] [Indexed: 11/18/2022] Open
Abstract
γD-crystallin is one of the major structural proteins in human eye lens. The solubility and stability of γD-crystallin play a crucial role in maintaining the optical properties of the lens during the life span of an individual. Previous study has shown that the inherited mutation G61C results in autosomal dominant congenital cataract. In this research, we studied the effects of the G61C mutation on γD-crystallin structure, stability and aggregation via biophysical methods. CD, intrinsic and extrinsic fluorescence spectroscopy indicated that the G61C mutation did not affect the native structure of γD-crystallin. The stability of γD-crystallin against heat- or GdnHCl-induced denaturation was significantly decreased by the mutation, while no influence was observed on the acid-induced unfolding. The mutation mainly affected the transition from the native state to the intermediate but not that from the intermediate to the unfolded or aggregated states. At high temperatures, both proteins were able to form aggregates, and the aggregation of the mutant was much more serious than the wild type protein at the same temperature. At body temperature and acidic conditions, the mutant was more prone to form amyloid-like fibrils. The aggregation-prone property of the mutant was not altered by the addition of reductive reagent. These results suggested that the decrease in protein stability followed by aggregation-prone property might be the major cause in the hereditary cataract induced by the G61C mutation.
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Affiliation(s)
- Wang Zhang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hong-Chen Cai
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Fei-Feng Li
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
- Peking Union Medical College, Tsinghua University, Beijing, China
| | - Yi-Bo Xi
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
- Institute of Biophysics, Lanzhou University, Lanzhou, China
| | - Xu Ma
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
- Peking Union Medical College, Tsinghua University, Beijing, China
- * E-mail: (XM); (YBY)
| | - Yong-Bin Yan
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China
- * E-mail: (XM); (YBY)
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Ding X, Wang B, Luo Y, Hu S, Zhou G, Zhou Z, Wang J, Ma X, Qi Y. A novel mutation in the connexin 46 (GJA3) gene associated with congenital cataract in a Chinese pedigree. Mol Vis 2011; 17:1343-9. [PMID: 21647269 PMCID: PMC3107996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 05/13/2011] [Indexed: 10/26/2022] Open
Abstract
PURPOSE To identify the potential pathogenic mutation in a three-generation Chinese family with congenital nuclear pulverulent cataracts. METHODS A three-generation pedigree was recruited for our study. Three patients and four healthy members of the family underwent a comprehensive clinical examination. Genomic DNA extracted from peripheral blood was amplified using the polymerase chain reaction (PCR) method and the exons of all candidate genes were sequenced. RESULTS When sequencing the encoding regions of the candidate genes, a novel mutation (c.559C>T) was identified in the gap junction protein alpha 3 (GJA3) gene, which resulted in the substitution of highly conserved proline by serine at codon 187 (P187S). There was no noticeable nucleotide polymorphism in other candidate genes. The mutation co-segregated with all patients, but was absent in the healthy members and 100 normal individuals. CONCLUSIONS The present study identified a novel mutation (c.559C>T) in the GJA3 gene associated with autosomal dominant pulverulent cataracts in a Chinese family. As the first report to relate p.P187S mutation in GJA3, it expands the mutation spectrum of GJA3 in association with congenital cataracts.
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Affiliation(s)
- Xuchen Ding
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Binbin Wang
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Yongfeng Luo
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shanshan Hu
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Guangkai Zhou
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Zhou Zhou
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Jing Wang
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Xu Ma
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Yanhua Qi
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
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Yang G, Xiong C, Li S, Wang Y, Zhao J. A recurrent mutation in CRYGD is associated with autosomal dominant congenital coralliform cataract in two unrelated Chinese families. Mol Vis 2011; 17:1085-9. [PMID: 21552497 PMCID: PMC3086606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 04/19/2011] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Congenital cataract is a clinically and genetically heterogeneous lens disorder. The purpose of this study was to identify the mutation responsible for autosomal dominant congenital coralliform cataracts in two Chinese families and to investigate the relationship between virulence genes and lens morphology. METHODS Patients received a physical examination, and blood samples were collected for DNA extraction. Mutation analysis was performed by direct sequencing of the candidate genes: gammaC-crystallin (CRYGC), gammaD-crystallin (CRYGD), gammaS-crystallin (CRYGS), gap-junction protein, alpha 8 (GJA8), gap-junction protein, alpha 3 (GJA3), and alphaA-crystallin (CRYAA). RESULTS The affected individuals in two families had congenital coralliform cataracts. Mutational analysis of the CRYGD identified a C→A transversion at nucleotide position c.70 in exon 2, which resulted in a threonine substitution for proline at amino-acid residue 24 (P24T). This mutation was identified in all affected individuals but was not found in healthy relatives or 100 control chromosomes from the same ethnic background. CONCLUSIONS Our results indicated that the P24T mutation of CRYGD was responsible for two Chinese pedigrees with congenital coralliform cataracts. CRYGD and coralliform cataracts are highly related, and P24T may be a hot-point mutation for this disorder.
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Affiliation(s)
- Guoxing Yang
- Department of Opthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Chunlei Xiong
- Department of Opthalmology, Hai Cheng Rehabilitation Hospital, Liaoning, China
| | - Shanlan Li
- Department of Opthalmology, Hai Cheng Rehabilitation Hospital, Liaoning, China
| | - Yuanyuan Wang
- Department of Opthalmology, Hai Cheng Rehabilitation Hospital, Liaoning, China
| | - Jialiang Zhao
- Department of Opthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Wang L, Chen X, Lu Y, Wu J, Yang B, Sun X. A novel mutation in γD-crystallin associated with autosomal dominant congenital cataract in a Chinese family. Mol Vis 2011; 17:804-9. [PMID: 21527994 PMCID: PMC3081795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 03/17/2011] [Indexed: 12/03/2022] Open
Abstract
PURPOSE To identify the pathogenic gene mutation in a Chinese family with autosomal dominant congenital nuclear cataract. METHODS After obtaining informed consent, detailed ophthalmic examinations were performed and genomic DNAs were obtained from eleven family members in a three-generation Chinese family with five affected. All exons of candidate genes associated with congenital nuclear cataract were amplified by polymerase chain reaction (PCR) and the PCR products were sequenced in both directions. The hydrophobic property of the mutant protein was analyzed with bioinformatics program ProtScale. The structure homology modeling of the mutant protein was based on Swiss-Model Serve, and its structure was displayed and compared with native γD-crystallin (CRYGD) using the RasMol software. RESULTS By sequencing the encoding regions of the candidate genes, a novel mutation (c.110G>C) was detected in exon 2 of CRYGD, which resulted in the substitution of a highly conserved arginine by proline at codon 36 (p.R36P). The mutation co-segregated with all patients and was absent in 100 normal Chinese controls. Bioinformatics analysis showed an obvious increase of the local hydrophilicity of the R36P mutant γD-crystallin. The homology modeling showed that the structure of the mutant protein was similar with that of native human γD-crystallin. CONCLUSIONS The study identified a novel mutation (c. 110G>C) in CRYGD associated with autosomal dominant congenital cataract in a Chinese family. It expands the mutation spectrum of CRYGD in association with congenital cataract.
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Kumar M, Agarwal T, Khokhar S, Kumar M, Kaur P, Roy TS, Dada R. Mutation screening and genotype phenotype correlation of α-crystallin, γ-crystallin and GJA8 gene in congenital cataract. Mol Vis 2011; 17:693-707. [PMID: 21423869 PMCID: PMC3060158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Accepted: 03/07/2011] [Indexed: 11/29/2022] Open
Abstract
PURPOSE To screen α-crystallin (CRYAB), γ-crystallin (CRYGC and CRYGD), and Connexin 50 (Cx-50 or GJA8) genes in congenital cataract patients and controls. METHODS Thirty clinically diagnosed congenital cataract cases below 3 years of age from northern India, presenting at Dr. R. P. Centre for Ophthalmic Sciences (AIIMS, New Delhi, India) were enrolled in this study. Genomic DNA was extracted from peripheral blood, all coding and exon/intron regions were amplified using PCR and direct sequencing was performed to detect any nucleotide variation. ProtScale and Discovery Studio programs were used for insilico and structural analysis of non-synonymous mutations. RESULTS DNA sequencing analysis of CRYAB, CRYGC, CRYGD, and GJA8 showed a total of six variations of which two were novel (CRYGC:p.R48H and GJA8:p.L281C) and four have been previously reported (CRYAB: rs11603779T>G, GJA8: p.L268L, CRYGD: p.R95R, and c.T564C). Both the novel changes, in CRYGC and GJA8 were found in 16.6% of the patients. Previously reported nucleotide alterations (CRYGD:p.R95R and c.T564C) were found in 90% of the patients. Insilico and structural analysis data suggested that two novel non-synonymous mutations altered the stability and solvent accessibility of γC-crystallin and Cx-50 proteins which may lead to lens opacification. CONCLUSIONS We observed two novel nonsynonymous variations and four reported variations in CRYAB, CRYGC, CRYGD, and GJA8. The p.R48H variation in γC-crystallin may disrupt the normal structure of lens and can cause cataract. Cx50 is responsible for joining the lens cells into a functional syncytium and a mutation (p.L281C) in GJA8 may lead to lens opacification resulting in cataract formation. This study further expands the mutation spectrum of congenital cataract and help understanding how mutant proteins lead to opacification of lens.
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Affiliation(s)
- Manoj Kumar
- Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Tushar Agarwal
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Sudarshan Khokhar
- Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India
| | - Manoj Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Punit Kaur
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi, India
| | - Tara Sankar Roy
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Rima Dada
- Laboratory for Molecular Reproduction and Genetics, Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
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Banerjee PR, Pande A, Patrosz J, Thurston GM, Pande J. Cataract-associated mutant E107A of human gammaD-crystallin shows increased attraction to alpha-crystallin and enhanced light scattering. Proc Natl Acad Sci U S A 2011; 108:574-9. [PMID: 21173272 PMCID: PMC3021023 DOI: 10.1073/pnas.1014653107] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Several point mutations in human γD-crystallin (HGD) are now known to be associated with cataract. So far, the in vitro studies of individual mutants of HGD alone have been sufficient in providing plausible molecular mechanisms for the associated cataract in vivo. Nearly all the mutant proteins in solution showed compromised solubility and enhanced light scattering due to altered homologous γ-γ crystallin interactions. In sharp contrast, here we present an intriguing case of a human nuclear cataract-associated mutant of HGD--namely Glu107 to Ala (E107A), which is nearly identical to the wild type in structure, stability, and solubility properties, with one exception: Its pI is higher by nearly one pH unit. This increase dramatically alters its interaction with α-crystallin. There is a striking difference in the liquid-liquid phase separation behavior of E107A-α-crystallin mixtures compared to HGD-α-crystallin mixtures, and the light-scattering intensities are significantly higher for the former. The data show that the two coexisting phases in the E107A-α mixtures differ much more in protein density than those that occur in HGD-α mixtures, as the proportion of α-crystallin approaches that in the lens nucleus. Thus in HGD-α mixtures, the demixing of phases occurs primarily by protein type while in E107A-α mixtures it is increasingly governed by protein density. Analysis of these results suggests that the cataract due to the E107A mutation could result from the instability caused by the altered attractive interactions between dissimilar proteins--i.e., heterologous γ-α crystallin interactions--primarily due to the change in surface electrostatic potential in the mutant protein.
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Affiliation(s)
| | | | - Julita Patrosz
- Department of Biology, University at Albany, State University of New York, Albany, NY 12222; and
| | - George M. Thurston
- Department of Physics, Rochester Institute of Technology, Rochester, NY 14623
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Molecular genetic analysis of autosomal dominant late-onset cataract in a Chinese Family. ACTA ACUST UNITED AC 2010; 30:792-7. [PMID: 21181374 DOI: 10.1007/s11596-010-0660-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Indexed: 10/18/2022]
Abstract
Congenital cataract is a highly heterogeneous disorder at both the genetic and the clinical-phenotypic levels. A unique cataract was observed in a 4-generation Chinese family, which was characterized by autosomal dominant inheritance and late-onset. Mutations in the 13 known genes (CRYAA, CRYAB, CRYBB1, CRYBB2, CRYGC, CRYBA1/A3, CRYGD, Connexin50, Connexin46, intrinsic membrane protein LIM2, cytoskeletal protein BFSP2, the major intrinsic protein-MIP and the heat shock factor HSF4) have previously been demonstrated to be the frequent reason for isolated congenital cataracts, but the exact molecular basis and underlying mechanisms of congenital cataract still remain unclear. This study was designed to find whether these 13 genes developed any mutation in the family members and to identify the disease-causing gene. Polymerase chain reaction (PCR) and direct DNA sequence analysis were carried out to detect the 13 genes. The results showed that no mutation causing amino acid alternations was found in these potential candidate genes among all patients in the family, and only several single-nucleotide polymorphisms (SNPs) were identified. A transitional mutation in the fourth intron of CRYBB2 and some silent mutations in the first exon of BFSP2 and CRYGD were found in the cataract family, but further study showed that these mutations could also be found in normal controls. It was concluded that some unidentified genes may underlie the occurrence of late-onset cataract in this family. A genome-wide screening will be carried out in the next study.
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Wang SSS, Wen WS. Examining the influence of ultraviolet C irradiation on recombinant human γD-crystallin. Mol Vis 2010; 16:2777-90. [PMID: 21197112 PMCID: PMC3008712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 12/10/2010] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Human γD crystallin is a principal protein component of the human eye lens and associated with the development of juvenile and mature-onset cataracts. Exposure to ultraviolet (UV) light is thought to perturb protein structure and eventually lead to aggregation. This work is aimed at exploring the effects of UV-C irradiation on recombinant human γD-crystallin (HGDC). METHODS Recombinant HGDC proteins were expressed in E. coli strain BL21(DE3) harboring plasmid pEHisHGDC and purified using chromatographic methods. The proteins were then exposed to UV-C light (λ(max)=254 nm, 15 W) at the intensity of 420, 800, or 1850 μW/cm(2). The UV-C-unexposed, supernatant fraction of UV-C-exposed, and re-dissolved precipitated fraction of UV-C exposed preparations were characterized by SDS-PAGE, turbidity measurement, CD spectroscopy, tryptophan fluorescence spectroscopy, acrylamide fluorescence quenching analysis, and sulfhydryl group measurements. RESULTS The turbidity of the HGDC sample solution was found to be positively correlated with HGDC concentration, UV-C irradiation intensity, and UV-C irradiation duration. When exposed to UV-C, HGDC sample solutions became visibly turbid and a noticeable amount of larger protein particle, perceptible to the naked eye, was observed upon prolonged irradiation. The precipitated fraction of irradiated HGDC sample was found to be re-dissolved by guanidine hydrochloride. Electrophoresis, acrylamide fluorescence quenching, and spectroscopic analyses revealed differences in structures among the non-irradiated HGDC, the supernatant fraction of irradiated HGDC, and the re-dissolved precipitated fraction of irradiated HGDC. Through the use of L-cysteine, the measurements of sulfhydryl contents, and the reducing as well as non-reducing SDS-PAGE, our data further suggested that disulfide bond formation and/or cleavage probably play an important role in aggregation and/or precipitation of HGDC elicited by UV-C irradiation. CONCLUSIONS Our findings highlight the close connections among disulfide bond cleavage and/or formation, intermolecular interactions, and the resultant formation of aggregates of HGDC induced by UV-C irradiation. The results from this research may not only contribute to the understanding of the environmental factors causing protein aggregation but also have implications for deciphering the molecular mechanism of cataractogenesis.
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Phase behavior of mixtures of human lens proteins Gamma D and Beta B1. Proc Natl Acad Sci U S A 2010; 107:13282-7. [PMID: 20616077 DOI: 10.1073/pnas.1008353107] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have experimentally determined the coexistence surface characterizing the phase behavior of gammaD-betaB1-water ternary solutions. The coexistence surface fully describes the solution conditions, i.e., temperature, protein concentration, and protein composition, at which liquid-liquid phase separation occurs in a ternary solution. We have observed a significant demixing of gammaD and betaB1 i.e., large difference of composition in the two coexisting phases. This demixing suggests that the energy of the gammaD-betaB1 attractive interaction is significantly smaller than the energy of the gammaD-gammaD attractive interaction. We also observed the lowering of the phase separation temperature upon increasing of the fraction of betaB1 in solution. We provide a theoretical analysis of our experimental data, which enables a quantitative description of our principal experimental findings. In this way, we have evaluated the magnitude and temperature dependence of the relevant interprotein interaction energies. Our findings provide insight into the factors essential for maintaining lens proteins in a single homogeneous phase, thereby enabling lens transparency.
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Roshan M, Vijaya PH, Lavanya GR, Shama PK, Santhiya S, Graw J, Gopinath P, Satyamoorthy K. A novel human CRYGD mutation in a juvenile autosomal dominant cataract. Mol Vis 2010; 16:887-96. [PMID: 20508808 PMCID: PMC2875257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Accepted: 05/12/2010] [Indexed: 10/26/2022] Open
Abstract
PURPOSE Identification of causal mutation in the crystallin, connexin, and paired box gene 6 (PAX6) genes associated with childhood cataract in patients from India. METHODS In this study, forty eight members from seventeen families and 148 sporadic cases of childhood cataract were evaluated. Clinical and ophthalmologic examinations were performed on available affected and unaffected family members. Samples of genomic DNA were PCR amplified to screen for mutations in the candidate genes viz., alpha-A crystallin (CRYAA), beta- B2 crystallin (CRYBB2), gamma-A crystallin (CRYGA), gamma-B crystallin (CRYGB), gamma-C crystallin (CRYGC), gamma-D crystallin (CRYGD), gap junction alpha-3 (GJA3), gap junction alpha-8 (GJA8), and PAX6 based on polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) analysis. Samples showing any band mobility shift were subjected to bidirectional sequencing to confirm the variation. Co-segregation of the observed change with the disease phenotype was further tested by restriction fragment length polymorphism (RFLP) for the appropriate restriction site. RESULTS DNA sequencing analysis of CRYAA, CRYBB2, CRYGA-D, GJA3, GJA8, and PAX6 of the affected members of a family (C-35) showed a novel heterozygous missense mutation C>A at position 229 in CRYGD in three affected members of family C-35 with anterior polar coronary cataract. This variation C229A substitution created a novel restriction site for AluI and resulted in a substitution of highly conserved arginine at position 77 by serine (R77S). AluI restriction site analysis confirmed the transversion mutation. Analysis of the available unaffected members of the family (C-35) and 100 unrelated control subjects (200 chromosomes) of the same ethnic background did not show R77S variation. Data generated using ProtScale and PyMOL programs revealed that the mutation altered the stability and solvent-accessibility of the CRYGD protein. CONCLUSIONS We describe here a family having anterior polar coronary cataract that co-segregates with the novel allele R77S of CRYGD in all the affected members. The same was found to be absent in the ethnically matched controls (n=100) studied. Interestingly the residue Arg has been frequently implicated in four missense (R15C, R15S, R37S, and R59H) and in one truncation mutation (R140X) of CRYGD. In two of the reported mutations Arg residues have been replaced with Serine. This finding further expands the mutation spectrum of CRYGD in association with childhood cataract and demonstrates a possible mechanism of cataractogenesis. Screening of other familial (n=48) and sporadic (n=148) cases of childhood cataract, did not reveal any previously reported or novel mutation in the candidate genes screened.
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Affiliation(s)
- Mascarenhas Roshan
- Department of Biotechnology, Manipal Life Sciences Centre, Manipal University, Manipal, India
| | - Pai H. Vijaya
- Department of Ophthalmology, Kasturba Hospital, Manipal University, Manipal, India
| | - G. Rao Lavanya
- Department of Ophthalmology, Kasturba Hospital, Manipal University, Manipal, India
| | - Prasada K. Shama
- Department of Biotechnology, Manipal Life Sciences Centre, Manipal University, Manipal, India
| | - S.T. Santhiya
- Department of Genetics, Dr. ALM P.G. Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, India
| | - Jochen Graw
- Institute of Developmental Genetics, Helmholtz Center Munich, German Research Center for Environmental Health, Neuherberg, Germany
| | - P.M. Gopinath
- Department of Biotechnology, Manipal Life Sciences Centre, Manipal University, Manipal, India
| | - K. Satyamoorthy
- Department of Biotechnology, Manipal Life Sciences Centre, Manipal University, Manipal, India
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Zhou Z, Hu S, Wang B, Zhou N, Zhou S, Ma X, Qi Y. Mutation analysis of congenital cataract in a Chinese family identified a novel missense mutation in the connexin 46 gene (GJA3). Mol Vis 2010; 16:713-9. [PMID: 20431721 PMCID: PMC2861125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 04/15/2010] [Indexed: 11/03/2022] Open
Abstract
PURPOSE To identify the genetic defects in a three-generation Chinese family with congenital nuclear cataract. METHODS Four patients and three healthy members from the family underwent complete physical and ophthalmic examinations. Genomic DNA was extracted from peripheral blood leukocytes of the family members as well as from 100 healthy normal controls. Polymerase chain reaction (PCR) amplification and direct sequencing of all coding exons of candidate genes were performed. The functional consequences of the mutation were analyzed with biology softwares. RESULTS A novel mutation (c.130G>A) was identified in the connexin 46 gene (GJA3), which resulted in the substitution of valine by methionine at the highly conserved codon 44 of connexin 46. This mutation co-segregated among the affected members of the family and was not observed in either unaffected members or the 100 normal controls. CONCLUSIONS This is a novel missense mutation identified in the first extracellular loop of connexin 46; this expands the mutation spectrum of GJA3 in association with congenital cataract.
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Affiliation(s)
- Zhou Zhou
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shanshan Hu
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Binbin Wang
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Nan Zhou
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Shiyi Zhou
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Xu Ma
- Department of Genetics, National Research Institute for Family Planning, Beijing, China
| | - Yanhua Qi
- Department of Ophthalmology, The Second Affiliated Hospital of Harbin Medical University, Harbin, China
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A single destabilizing mutation (F9S) promotes concerted unfolding of an entire globular domain in gammaS-crystallin. J Mol Biol 2010; 399:320-30. [PMID: 20382156 DOI: 10.1016/j.jmb.2010.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Revised: 03/30/2010] [Accepted: 04/01/2010] [Indexed: 11/22/2022]
Abstract
Conformational change and aggregation of native proteins are associated with many serious age-related and neurological diseases. gammaS-Crystallin is a highly stable, abundant structural component of vertebrate eye lens. A single F9S mutation in the N-terminal domain of mouse gammaS-crystallin causes the severe Opj cataract, with disruption of cellular organization and appearance of fibrillar structures in the lens. Although the mutant protein has a near-native fold at room temperature, significant increases in hydrogen/deuterium exchange rates were observed by NMR for all the well-protected beta-sheet core residues throughout the entire N-terminal domain of the mutant protein, resulting in up to a 3.5-kcal/mol reduction in the free energy of the folding/unfolding equilibrium. No difference was detected for the C-terminal domain. At a higher temperature, this effect further increases to allow for a much more uniform exchange rate among the N-terminal core residues and those of the least well-structured surface loops. This suggests a concerted unfolding intermediate of the N-terminal domain, while the C-terminal domain stays intact. Increasing concentrations of guanidinium chloride produced two transitions for the Opj mutant, with an unfolding intermediate at approximately 1 M guanidinium chloride. The consequence of this partial unfolding, whether by elevated temperature or by denaturant, is the formation of thioflavin T staining aggregates, which demonstrated fibril-like morphology by atomic force microscopy. Seeding with the already unfolded protein enhanced the formation of fibrils. The Opj mutant protein provides a model for stress-related unfolding of an essentially normally folded protein and production of aggregates with some of the characteristics of amyloid fibrils.
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Ma Z, Piszczek G, Wingfield PT, Sergeev YV, Hejtmancik JF. The G18V CRYGS mutation associated with human cataracts increases gammaS-crystallin sensitivity to thermal and chemical stress. Biochemistry 2009; 48:7334-41. [PMID: 19558189 DOI: 10.1021/bi900467a] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
GammaS-crystallin, important in maintaining lens transparency, is a monomeric betagamma-crystallin comprising two paired homologous domains, each with two Greek key motifs. An autosomal dominant cortical progressive cataract has been associated with a G18V mutation in human gammaS-crystallin. To investigate the molecular mechanism of this cataract and confirm the causative nature of the G18V mutation, we examined resultant changes in conformation and stability. Human gammaS-crystallin cDNA was cloned into pET-20b(+), and the G18V mutant was generated by site-directed mutagenesis. Recombinant HgammaS-crystallins were expressed in Escherichia coli and purified by ion-exchange and size-exclusion chromatography. By analytical ultracentrifugation wild-type and mutant HgammaS-crystallins are monomers of about 21.95 +/- 0.21 and 20.89 +/- 0.18 kDa, respectively, and have similar secondary structures by far-UV CD. In increasing levels of guanidine hydrochloride (GuHCl), a sharp red shift in fluorescence lambda(max) and increase in emission correlating with exposure of tryptophans to the protein surface are detected earlier in the mutant protein. Under thermal stress, the G18V mutant begins to show changes in tryptophan fluorescence above 42 degrees C and shows a Tm of 65 degrees C as monitored by CD at 218 nm, while wild-type HgammaS-crystallin is very stable with Tm values of 75.5 and 75.0 degrees C as measured by fluorescence and CD, respectively. Equilibrium unfolding/refolding experiments as a function of GuHCl confirm the relative instability of the G18V mutant. Wild-type HgammaS-crystallin exhibits a two-state transition and reversible refolding above 1.0 M GuHCl, but the unfolding transition of mutant HgammaS-crystallin shows an intermediate state. The first transition (N --> I) shows a [GuHCl](1/2) of 0.5 M while the second transition (I --> U) has the same [GuHCl](1/2) as wild-type HgammaS-crystallin, about 2.0 M. Our present study confirms the high stability of wild-type HgammaS-crystallin and demonstrates that the G18V mutation destabilizes the protein toward heat and GuHCl-induced unfolding. These biophysical characteristics are consistent with the progressive cataract formation seen in the family members carrying this mutation.
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Affiliation(s)
- Zhiwei Ma
- National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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