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Nicolas WJ, Shiriaeva A, Martynowycz MW, Grey AC, Ruma Y, Donaldson PJ, Gonen T. Structure of the lens MP20 mediated adhesive junction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.13.594022. [PMID: 38798449 PMCID: PMC11118347 DOI: 10.1101/2024.05.13.594022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Human lens fiber membrane intrinsic protein MP20 is the second most abundant membrane protein of the human eye lens. Despite decades of effort its structure and function remained elusive. Here, we determined the MicroED structure of full-length human MP20 in lipidic-cubic phase to a resolution of 3.5 Å. MP20 forms tetramers each of which contain 4 transmembrane α-helices that are packed against one another forming a helical bundle. Both the N- and C- termini of MP20 are cytoplasmic. We found that each MP20 tetramer formed adhesive interactions with an opposing tetramer in a head-to-head fashion. These interactions were mediated by the extracellular loops of the protein. The dimensions of the MP20 adhesive junctions are consistent with the 11 nm thin lens junctions. Investigation of MP20 localization in human lenses indicated that in young fiber cells MP20 was stored intracellularly in vesicles and upon fiber cell maturation MP20 inserted into the plasma membrane and restricted the extracellular space. Together these results suggest that MP20 forms lens thin junctions in vivo confirming its role as a structural protein in the human eye lens, essential for its optical transparency.
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Affiliation(s)
- William J. Nicolas
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095
| | - Anna Shiriaeva
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Michael W. Martynowycz
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Angus C Grey
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, NZ
| | - Yasmeen Ruma
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, NZ
| | - Tamir Gonen
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
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Türkyılmaz A, Kaplan AT, Öskan Yalçın S, Sağer SG, Şimşek Ş. Identification of novel variants in Turkish families with non-syndromic congenital cataracts using whole-exome sequencing. Int Ophthalmol 2023; 43:4573-4583. [PMID: 37592116 DOI: 10.1007/s10792-023-02857-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 08/05/2023] [Indexed: 08/19/2023]
Abstract
PURPOSE The present study aimed to identify the molecular etiology of non-syndromic congenital cataract (CC) using whole-exome sequencing (WES) analysis. METHODS In the present study, ophthalmologic results and pedigree analysis of the families of 12 patients with non-syndromic CC were evaluated. WES analysis was conducted after DNA was isolated from peripheral blood samples obtained from the patients. RESULTS Twelve non-syndromic probands (10 males and 2 females) with bilateral CC were included in the study. Patient age ranged between 1 and 11 months. WES analysis showed pathogenic/likely pathogenic variant in 7 (58%) of the 12 families and variant of unknown significance (VUS) in 5 (42%) of them. All the 13 different variants detected in 9 different CC-related genes were co-segregated with the disease. Autosomal dominant inheritance was found in 7 (58%) of the families and autosomal recessive inheritance was found in 5 (42%) of them. CONCLUSION To the best of our knowledge, the present research is one of the limited numbers of studies in the Turkish population in which genetically heterogeneous non-syndromic CC was investigated using WES analysis. Novel variants that we identified in DNMBP, LSS, and WFS1 genes, which are rarely associated with the CC phenotype, have contributed to the mutation spectrum of this disease. Identifying the relevant molecular genetic etiology allows accurate genetic counseling to be provided to the families.
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Affiliation(s)
- Ayberk Türkyılmaz
- Department of Medical Genetics, Faculty of Medicine, Karadeniz Technical University, Ortahisar, Trabzon, Turkey.
| | - Ayşin Tuba Kaplan
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Sibel Öskan Yalçın
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Safiye Güneş Sağer
- Department of Pediatric Neurology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
| | - Şaban Şimşek
- Department of Ophthalmology, Kartal Dr. Lütfi Kırdar City Hospital, Istanbul, Turkey
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Wu J, Chen S, Xu J, Xu W, Zheng S, Tian Q, Luo C, Chen X, Shentu X. Insight into Pathogenic Mechanism Underlying the Hereditary Cataract Caused by βB2-G149V Mutation. Biomolecules 2023; 13:biom13050864. [PMID: 37238733 DOI: 10.3390/biom13050864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 04/17/2023] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
Congenital cataracts account for approximately 5-20% of childhood blindness worldwide and 22-30% of childhood blindness in developing countries. Genetic disorders are the primary cause of congenital cataracts. In this work, we investigated the underlying molecular mechanism of G149V point missense mutation in βB2-crystallin, which was first identified in a three-generation Chinese family with two affected members diagnosed with congenital cataracts. Spectroscopic experiments were performed to determine the structural differences between the wild type (WT) and the G149V mutant of βB2-crystallin. The results showed that the G149V mutation significantly changed the secondary and tertiary structure of βB2-crystallin. The polarity of the tryptophan microenvironment and the hydrophobicity of the mutant protein increased. The G149V mutation made the protein structure loose and the interaction between oligomers was reduced, which decreased the stability of the protein. Furthermore, we compared βB2-crystallin WT and the G149V mutant with their biophysical properties under environmental stress. We found that the G149V mutation makes βB2-crystallin more sensitive to environmental stresses (oxidative stress, UV irradiation, and heat shock) and more likely to aggregate and form precipitation. These features might be important to the pathogenesis of βB2-crystallin G149V mutant related to congenital cataracts.
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Affiliation(s)
- Jing Wu
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
- Department of Ophthalmology, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, 158 Shangtang Road, Hangzhou 310053, China
| | - Silong Chen
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
| | - Jingjie Xu
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
| | - Wanyue Xu
- Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310030, China
| | - Sifan Zheng
- GKT School of Medical Education, King's College London, London SE1 1UL, UK
| | - Qing Tian
- Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310030, China
| | - Chenqi Luo
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
| | - Xiangjun Chen
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
- Institute of Translational Medicine, Zhejiang University School of Medicine, 268 Kaixuan Road, Hangzhou 310030, China
| | - Xingchao Shentu
- Department of Ophthalmology, The Second Affiliated Hospital, Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou 310030, China
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Cvekl A, Camerino MJ. Generation of Lens Progenitor Cells and Lentoid Bodies from Pluripotent Stem Cells: Novel Tools for Human Lens Development and Ocular Disease Etiology. Cells 2022; 11:cells11213516. [PMID: 36359912 PMCID: PMC9658148 DOI: 10.3390/cells11213516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
In vitro differentiation of human pluripotent stem cells (hPSCs) into specialized tissues and organs represents a powerful approach to gain insight into those cellular and molecular mechanisms regulating human development. Although normal embryonic eye development is a complex process, generation of ocular organoids and specific ocular tissues from pluripotent stem cells has provided invaluable insights into the formation of lineage-committed progenitor cell populations, signal transduction pathways, and self-organization principles. This review provides a comprehensive summary of recent advances in generation of adenohypophyseal, olfactory, and lens placodes, lens progenitor cells and three-dimensional (3D) primitive lenses, "lentoid bodies", and "micro-lenses". These cells are produced alone or "community-grown" with other ocular tissues. Lentoid bodies/micro-lenses generated from human patients carrying mutations in crystallin genes demonstrate proof-of-principle that these cells are suitable for mechanistic studies of cataractogenesis. Taken together, current and emerging advanced in vitro differentiation methods pave the road to understand molecular mechanisms of cataract formation caused by the entire spectrum of mutations in DNA-binding regulatory genes, such as PAX6, SOX2, FOXE3, MAF, PITX3, and HSF4, individual crystallins, and other genes such as BFSP1, BFSP2, EPHA2, GJA3, GJA8, LIM2, MIP, and TDRD7 represented in human cataract patients.
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Affiliation(s)
- Aleš Cvekl
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: ; Tel.: +1-718-430-3217; Fax: +1-718-430-8778
| | - Michael John Camerino
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Berry V, Fujinami K, Mochizuki K, Iwata T, Pontikos N, Quinlan RA, Michaelides M. A recurrent variant in LIM2 causes an isolated congenital sutural/lamellar cataract in a Japanese family. Ophthalmic Genet 2022; 43:622-626. [PMID: 35736209 PMCID: PMC9612932 DOI: 10.1080/13816810.2022.2090010] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Genetically determined cataract is both clinically and molecularly highly heterogeneous. Here, we have identified a heterozygous variant in the lens integral membrane protein LIM2, the second most abundant protein in the lens, responsible for congenital sutural/lamellar cataract in a three-generation Japanese family. Methods Whole exome sequencing (WES) was undertaken in one affected and one unaffected individual from a family with autosomal dominant congenital cataract to establish the underlying genetic basis. Results A recurrent missense variant LIM2: c.388C>T; p.R130C was identified and found to co-segregate with disease. In addition, one variant COL11A1:c.3788C>T of unknown significance (VUS) was also identified. Conclusions We report a variant in LIM2 causing an isolated autosomal-dominant congenital sutural/lamellar cataract in a Japanese family. This is the first report of a LIM2 variant in the Japanese population. Hence, we expand the mutation spectrum of LIM2 variants in different ethnic groups.
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Affiliation(s)
- Vanita Berry
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Kaoru Fujinami
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK.,Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization, Tokyo Medical Centre, Tokyo, Japan
| | - Kiyofumi Mochizuki
- Department of Ophthalmology, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Takeshi Iwata
- Division of Molecular and Cellular Biology, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
| | - Nikolas Pontikos
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
| | - Roy A Quinlan
- Department of Biosciences, University of Durham, Durham, UK
| | - Michel Michaelides
- Department of Genetics, UCL Institute of Ophthalmology, University College London, London, UK.,Moorfields Eye Hospital NHS Foundation Trust, London, UK
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Fernández-Alcalde C, Nieves-Moreno M, Noval S, Peralta JM, Montaño VEF, del Pozo Á, Santos-Simarro F, Vallespín E. Molecular and Genetic Mechanism of Non-Syndromic Congenital Cataracts. Mutation Screening in Spanish Families. Genes (Basel) 2021; 12:580. [PMID: 33923544 PMCID: PMC8072554 DOI: 10.3390/genes12040580] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 11/28/2022] Open
Abstract
Our purpose was to identify mutations responsible for non-syndromic congenital cataracts through the implementation of next-generation sequencing (NGS) in our center. A sample of peripheral blood was obtained from probands and willing family members and genomic DNA was extracted from leukocytes. DNA was analyzed implementing a panel (OFTv2.1) including 39 known congenital cataracts disease genes. 62 probands from 51 families were recruited. Pathogenic or likely pathogenic variants were identified in 32 patients and 25 families; in 16 families (64%) these were de novo mutations. The mutation detection rate was 49%. Almost all reported mutations were autosomal dominant. Mutations in crystallin genes were found in 30% of the probands. Mutations in membrane proteins were detected in seven families (two in GJA3 and five in GJA8). Mutations in LIM2 and MIP were each found in three families. Other mutations detected affected EPHA2, PAX6, HSF4 and PITX3. Variants classified as of unknown significance were found in 5 families (9.8%), affecting CRYBB3, LIM2, EPHA2, ABCB6 and TDRD7. Mutations lead to different cataract phenotypes within the same family.
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Affiliation(s)
- Celia Fernández-Alcalde
- Department of Ophthalmology, Hospital Universitario La Paz, 28046 Madrid, Spain; (M.N.-M.); (S.N.); (J.M.P.)
| | - María Nieves-Moreno
- Department of Ophthalmology, Hospital Universitario La Paz, 28046 Madrid, Spain; (M.N.-M.); (S.N.); (J.M.P.)
| | - Susana Noval
- Department of Ophthalmology, Hospital Universitario La Paz, 28046 Madrid, Spain; (M.N.-M.); (S.N.); (J.M.P.)
| | - Jesús M. Peralta
- Department of Ophthalmology, Hospital Universitario La Paz, 28046 Madrid, Spain; (M.N.-M.); (S.N.); (J.M.P.)
| | - Victoria E. F. Montaño
- Department of Molecular Ophthalmology, Medical and Molecular Genetics Institute (INGEMM) IdiPaz, CIBERER, Hospital Universitario La Paz, 28046 Madrid, Spain; (V.E.F.M.); (E.V.)
| | - Ángela del Pozo
- Department of Clinical Bioinformatics, Medical and Molecular Genetics Institute (INGEMM) IdiPaz, CIBERER, Hospital Universitario La Paz, 28046 Madrid, Spain;
| | - Fernando Santos-Simarro
- Department of Clinical Genetics, Medical and Molecular Genetics Institute (INGEMM) IdiPaz, CIBERER, Hospital Universitario La Paz, 28046 Madrid, Spain;
| | - Elena Vallespín
- Department of Molecular Ophthalmology, Medical and Molecular Genetics Institute (INGEMM) IdiPaz, CIBERER, Hospital Universitario La Paz, 28046 Madrid, Spain; (V.E.F.M.); (E.V.)
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Wang X, Qin Y, Abudoukeremuahong A, Dongye M, Zhang X, Wang D, Li J, Lin Z, Yang Y, Ding L, Lin H. Elongated axial length and myopia-related fundus changes associated with the Arg130Cys mutation in the LIM2 gene in four Chinese families with congenital cataracts. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:235. [PMID: 33708862 PMCID: PMC7940952 DOI: 10.21037/atm-20-4275] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background Congenital cataract (CC) is a congenital abnormality characterized by lens opacity present at birth and is associated with highly heterogeneous clinical manifestations. Lens-specific integral membrane protein (LIM2) gene expression is localized to tight junctional domains of different lens fiber membranes. To date, only four mutations in LIM2 have been reported to be associated with congenital or presenile cataracts. Due to the rarity of variants detected in the gene, there is limited progress in understanding the correlation between the genotype and phenotype of patients with mutations in LIM2. Methods A total of four Chinese families with CCs were recruited for this study, including three families inheriting in an autosomal dominant (AD) pattern and one sporadic case. Genomic DNA was extracted from the leukocytes of peripheral blood collected from all available patients. Whole-exome sequencing (WES) was performed on all probands and at least one of their parents. Bioinformatics analysis was performed to evaluate the pathogenicity of the candidate variants. Exon 4 of LIM2 was amplified by polymerase chain reaction and directly sequenced. All patients underwent full ocular examinations. This was an observational study to explore the genotype-phenotype relationships in the four families with a common candidate variant. Results Various ocular phenotypes were detected in these families, mainly including CCs, elongated axial length, and myopia-related fundus changes. The LIM2 gene mutation, p.Arg130Cys, was detected in all patients. This was further confirmed by Sanger sequencing. The proportion of probands with this mutation in our CCs database was 3.1% (4/130), which indicated that this mutation appears to be a frequent cause of cataracts in the Han Chinese population. This variation has been reported by other investigators before and was correlated with isolated cataracts. Conclusions This is the first study that reports various ocular phenotypes associated with the p.Arg130Cys mutation in the LIM2 gene, which indicated the phenotypic heterogeneity of this gene. LIM2 might not only function as an integral membrane protein in lens fiber cells but also be associated with the axial development of the eyeball. Functional studies of the LIM2 gene are important and should receive more attention.
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Affiliation(s)
- Xun Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yanli Qin
- Department of Ophthalmology, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi, 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
| | - Dongni Wang
- 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
| | - Zhuoling Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yahan Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Lin Ding
- Department of Ophthalmology, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi, China
| | - Haotian Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
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