1
|
Reis LM, Seese S, Costakos D, Semina EV. Congenital anterior segment ocular disorders: genotype-phenotype correlations and emerging novel mechanisms. Prog Retin Eye Res 2024:101288. [PMID: 39097141 DOI: 10.1016/j.preteyeres.2024.101288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 07/30/2024] [Accepted: 07/31/2024] [Indexed: 08/05/2024]
Abstract
Development of the anterior segment of the eye requires reciprocal sequential interactions between the arising tissues, facilitated by numerous genetic factors. Disruption of any of these processes results in congenital anomalies in the affected tissue(s) leading to anterior segment disorders (ASD) including aniridia, Axenfeld-Rieger anomaly, congenital corneal opacities (Peters anomaly, cornea plana, congenital primary aphakia), and primary congenital glaucoma. Current understanding of the genetic factors involved in ASD remains incomplete, with approximately 50% overall receiving a genetic diagnosis. While some genes are strongly associated with a specific clinical diagnosis, the majority of known factors are linked with highly variable phenotypic presentations, with pathogenic variants in FOXC1, CYP1B1, and PITX2 resulting in the broadest spectrum of ASD conditions. This review discusses typical clinical presentations including associated systemic features of various forms of ASD; the latest functional data and genotype-phenotype correlations related to 25 ASD factors including newly identified genes; promising novel candidates; and current and emerging treatments for these complex conditions. Recent developments of interest in the genetics of ASD include identification of phenotypic expansions for several factors, discovery of multiple modes of inheritance for some genes, and novel mechanisms including a growing number of non-coding variants and alleles affecting specific domains/residues and requiring further studies.
Collapse
Affiliation(s)
- Linda M Reis
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| | - Sarah Seese
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| | - Deborah Costakos
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| | - Elena V Semina
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA; Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
| |
Collapse
|
2
|
Pan X, Muir ER, Sellitto C, Jiang Z, Donaldson PJ, White TW. Connexin 50 Influences the Physiological Optics of the In Vivo Mouse Lens. Invest Ophthalmol Vis Sci 2024; 65:19. [PMID: 38984874 PMCID: PMC11238879 DOI: 10.1167/iovs.65.8.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2024] Open
Abstract
Purpose The purpose of this study was to utilize multi-parametric magnetic resonance imaging (MRI) to investigate in vivo age-related changes in the physiology and optics of mouse lenses where Connexin 50 has been deleted (Cx50KO) or replaced by Connexin 46 (Cx50KI46). Methods The lenses of transgenic Cx50KO and Cx50KI46 mice were imaged between 3 weeks and 6 months of age using a 7T MRI. Measurements of lens geometry, the T2 (water-bound protein ratios), the refractive index (n), and T1 (free water content) values were calculated by processing the acquired images. The lens power was calculated from an optical model that combined the geometry and the n. All transgenic mice were compared with control mice at the same age. Results Cx50KO and Cx50KI46 mice developed smaller lenses compared with control mice. The lens thickness, volume, and surface radii of curvatures all increased with age but were limited to the size of the lenses. Cx50KO lenses exhibited higher lens power than Cx50KI46 lenses at all ages, and this was correlated with significantly lower water content in these lenses, which was probably modulated by the gap junction coupling. The refractive power tended to a steady state with age, similar to the control mice. Conclusions The modification of Cx50 gap junctions significantly impacted lens growth and physiological optics as the mouse aged. The lenses showed delayed development growth, and altered optics governed by different lens physiology. This research provides new insights into how gap junctions regulate the development of the lens's physiological optics.
Collapse
Affiliation(s)
- Xingzheng Pan
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
| | - Eric R Muir
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Caterina Sellitto
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Zhao Jiang
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand Eye Centre, University of Auckland, New Zealand
| | - Thomas W White
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, New York, United States
| |
Collapse
|
3
|
Giannone AA, Sellitto C, Rosati B, McKinnon D, White TW. Single-Cell RNA Sequencing Analysis of the Early Postnatal Mouse Lens Epithelium. Invest Ophthalmol Vis Sci 2023; 64:37. [PMID: 37870847 PMCID: PMC10599162 DOI: 10.1167/iovs.64.13.37] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/06/2023] [Indexed: 10/24/2023] Open
Abstract
Purpose The lens epithelium maintains the overall health of the organ. We used single-cell RNA sequencing (scRNA-seq) technology to assess transcriptional heterogeneity between cells in the postnatal day 2 (P2) epithelium and identify distinct epithelial cell subtypes. Analysis of these data was used to better understand lens growth, differentiation, and homeostasis on P2. Methods scRNA-seq on P2 mouse lenses was performed using the 10x Genomics Chromium Single Cell 3' Kit (v3.1) and short-read Illumina sequencing. Sequence alignment and preprocessing of data were conducted using 10x Genomics Cell Ranger software. Seurat was employed for preprocessing, quality control, dimensionality reduction, and cell clustering, and Monocle was utilized for trajectory analysis to understand the developmental progression of the lens cells. CellChat and GO analyses were used to explore cell-cell communication networks and signaling interactions. Results Lens epithelial cells (LECs) were divided into seven subclusters, classified by specific gene markers. The expression of crystallin, cell-cycle, and metabolic genes was not uniform, indicating distinct functional roles of LECs. Trajectory analysis predicted a bifurcation of differentiating and cycling cells from an Igfbp5+ progenitor pool. We also identified heterogeneity in signaling molecules and pathways, suggesting that cycling and progenitor subclusters have prominent roles in coordinating crosstalk. Conclusions scRNA-seq corroborated many known markers of epithelial differentiation and proliferation while providing further insight into the pathways and genes directing these processes. Interestingly, we demonstrated that the developing epithelium can be divided into distinct subpopulations. These clusters reflect the transcriptionally diverse roles of the epithelium in proliferation, signaling, and maintenance.
Collapse
Affiliation(s)
- Adrienne A. Giannone
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Caterina Sellitto
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Barbara Rosati
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
- Veterans Affairs Medical Center, Northport, New York, United States
| | - David McKinnon
- Department of Neurobiology and Behavior, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| | - Thomas W. White
- Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook University, Stony Brook, New York, United States
| |
Collapse
|
4
|
Shen J, Wu Q, You J, Zhang X, Zhu L, Xia X, Xue C, Tian X. Characterization of a Novel Gja8 (Cx50) Mutation in a New Cataract Rat Model. Invest Ophthalmol Vis Sci 2023; 64:18. [PMID: 37294706 DOI: 10.1167/iovs.64.7.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023] Open
Abstract
Purpose To describe a novel spontaneous cataract inbred strain isolated from large-scale breeding SD rats, identify the responsible gene mutation, and understand how this mutation affects lens function. Methods Exome sequencing of 12 cataract-associated genes was performed in the affected and healthy relatives. Sequences of rat wild-type or mutant gap junction protein alpha 8 gene (Gja8) were transfected into cells. The expression level of protein was assayed by Western blot analysis. Subcellular localization of connexin 50 (Cx50) was analyzed in confocal fluorescent images. Wound-healing, 5-ethynyl-2'-deoxyuridine incorporation, and attachment assay were performed to characterize the cell migration, proliferation and adhesion. Results The abnormality was found to be inheritable in an autosomal semi-dominant pattern through different mating patterns. We found a G to T transversion at codon 655 in Gja8, leading to a substitution of valine by phenylalanine (p.V219F). Gja8V219F/+ heterozygotes expressed nuclear cataract while Gja8V219F/V219F homozygotes manifested microphthalmia in addition to cataract. Histology revealed fiber disorders and loss of organelle-free zone in the mutant lens. Cx50V219F altered its location in HeLa cells and inhibited the proliferation, migration and adhesion abilities of HLEB3 cells. The mutation also reduced the expression of focal adhesion kinase and its phosphorylation. Conclusions The c.655G>T mutation (p.V219F) is a novel mutation in Gja8, inducing semi-dominant nuclear cataracts in a new spontaneous cataract rat model. The p.V219F mutation altered Cx50 distribution, inhibited lens epithelial cell proliferation, migration, and adhesion, and disrupted fiber cell differentiation. As a consequence, the nuclear cataract and small lens formed.
Collapse
Affiliation(s)
- Jiawei Shen
- Department of Ophthalmology, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Qiuyue Wu
- Institute of Laboratory Medicine, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Jinwei You
- Laboratory Animal Department of Medical Security Center, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Xiaoran Zhang
- Department of Ophthalmology, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Lei Zhu
- Department of Ophthalmology, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Xinyi Xia
- Institute of Laboratory Medicine, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Chunyan Xue
- Department of Ophthalmology, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| | - Xiaoyun Tian
- Laboratory Animal Department of Medical Security Center, Nanjing Jinling Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, Jiangsu, China
| |
Collapse
|
5
|
Zhou Y, Bennett TM, White TW, Shiels A. Charged multivesicular body protein 4b forms complexes with gap junction proteins during lens fiber cell differentiation. FASEB J 2023; 37:e22801. [PMID: 36880430 PMCID: PMC10101236 DOI: 10.1096/fj.202201368rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 01/19/2023] [Accepted: 01/23/2023] [Indexed: 03/08/2023]
Abstract
Charged multivesicular body protein 4b (CHMP4B) is a core sub-unit of the endosomal sorting complex required for transport III (ESCRT-III) machinery that serves myriad remodeling and scission processes of biological membranes. Mutation of the human CHMP4B gene underlies rare forms of early-onset lens opacities or cataracts, and CHMP4B is required for lens growth and differentiation in mice. Here, we determine the sub-cellular distribution of CHMP4B in the lens and uncover a novel association with gap junction alpha-3 protein (GJA3) or connexin 46 (Cx46) and GJA8 or Cx50. Immunofluorescence confocal microscopy revealed that CHMP4B localized to cell membranes of elongated fiber cells in the outer cortex of the lens-where large gap junction plaques begin to form-particularly, on the broad faces of these flattened hexagon-like cells in cross-section. Dual immunofluorescence imaging showed that CHMP4B co-localized with gap junction plaques containing Cx46 and/or Cx50. When combined with the in situ proximity ligation assay, immunofluorescence confocal imaging indicated that CHMP4B lay in close physical proximity to Cx46 and Cx50. In Cx46-knockout (Cx46-KO) lenses, CHMP4B-membrane distribution was similar to that of wild-type, whereas, in Cx50-KO lenses, CHMP4B localization to fiber cell membranes was lost. Immunoprecipitation and immunoblotting analyses revealed that CHMP4B formed complexes with Cx46 and Cx50 in vitro. Collectively, our data suggest that CHMP4B forms plasma membrane complexes, either directly and/or indirectly, with gap junction proteins Cx46 and Cx50 that are often associated with "ball-and-socket" double-membrane junctions during lens fiber cell differentiation.
Collapse
Affiliation(s)
- Yuefang Zhou
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Thomas M. Bennett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| | - Thomas W. White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| | - Alan Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO, USA
| |
Collapse
|
6
|
Du Y, Tong Y, Quan Y, Wang G, Cheng H, Gu S, Jiang JX. Protein kinase A activation alleviates cataract formation via increased gap junction intercellular communication. iScience 2023; 26:106114. [PMID: 36852280 PMCID: PMC9958365 DOI: 10.1016/j.isci.2023.106114] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 12/09/2022] [Accepted: 01/28/2023] [Indexed: 02/05/2023] Open
Abstract
Cataract is the leading cause of blindness worldwide. Here, we reported a potential, effective therapeutic mean for cataract prevention and treatment. Gap junction communication, an important mechanism in maintaining lens transparency, is increased by protein kinase A (PKA). We found that PKA activation reduced cataracts induced by oxidative stress, increased gap junctions/hemichannels in connexin (Cx) 50, Cx46 or Cx50 and Cx46 co-expressing cells, and decreased reactive oxygen species (ROS) levels. However, ROS reduction was shown in wild-type, Cx46 and Cx50 knockout, but not in Cx46/Cx50 double KO lens. In addition, PKA activation protects lens fiber cell death induced by oxidative stress via hemichannel-mediated glutathione transport. Connexin deletion increased lens opacity induced by oxidative stress associated with reduction of anti-oxidative stress gene expression. Together, our results suggest that PKA activation through increased connexin channels in lens fiber cell decreases ROS levels and cell death, leading to alleviated cataracts.
Collapse
Affiliation(s)
- Yu Du
- Department of Ophthalmology, Lanzhou University Second Hospital; Second Clinical School, Lanzhou University, Lanzhou, Gansu, 730000, China
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Yuxin Tong
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Yumeng Quan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
- Department of Ophthalmology, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Guangyan Wang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
- Department of Ophthalmology, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China
| | - Hongyun Cheng
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
| |
Collapse
|
7
|
Li Z, Quan Y, Wang G, Ma B, Gu S, Jiang JX. The second extracellular domain of connexin 50 is important for in cell adhesion, lens differentiation, and adhesion molecule expression. J Biol Chem 2023; 299:102965. [PMID: 36736424 PMCID: PMC10011516 DOI: 10.1016/j.jbc.2023.102965] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 01/12/2023] [Accepted: 01/13/2023] [Indexed: 02/04/2023] Open
Abstract
Connexin (Cx)-forming channels play essential roles in maintaining lens homeostasis and transparency. We showed here channel-independent roles of Cx50 in cell-cell adhesion and confirmed the second extracellular (E2) domain as a critical domain for cell adhesion function. We found that cell adhesion decreased in cells expressing chimeric Cx50 in which the E2 domain was swapped with the E2 domain of either Cx43 or Cx46. In contrast, adhesion increased in cells expressing chimeric Cx43 and Cx46 with the Cx50 (E2) domain. This function is Cx channel-independent and Cx50 E2 domain-dependent cell adhesion acting in both homotypic and heterotypic manners. In addition, we generated eight site mutations of unique residues between Cx50 and the other two lens Cxs and found that mutation of any one of the residues abolished the adhesive function. Moreover, expression of adhesive-impaired mutants decreased adhesion-related proteins, N-cadherin and β-catenin. Expression of the adhesion-impaired Cx50W188P mutant in embryonic chick lens caused enlarged extracellular spaces, distorted fiber organization, delayed nuclear condensation, and cortical cataracts. In summary, the results from both in vitro and in vivo studies demonstrate the importance of the adhesive function of Cx50 in the lens.
Collapse
Affiliation(s)
- Zhen Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA; State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yumeng Quan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Guangyan Wang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Bo Ma
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, Texas, USA.
| |
Collapse
|
8
|
Liu Z, Huang S, Zheng Y, Zhou T, Hu L, Xiong L, Li DWC, Liu Y. The lens epithelium as a major determinant in the development, maintenance, and regeneration of the crystalline lens. Prog Retin Eye Res 2023; 92:101112. [PMID: 36055924 DOI: 10.1016/j.preteyeres.2022.101112] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/28/2022] [Accepted: 08/02/2022] [Indexed: 02/01/2023]
Abstract
The crystalline lens is a transparent and refractive biconvex structure formed by lens epithelial cells (LECs) and lens fibers. Lens opacity, also known as cataracts, is the leading cause of blindness in the world. LECs are the principal cells of lens throughout human life, exhibiting different physiological properties and functions. During the embryonic stage, LECs proliferate and differentiate into lens fibers, which form the crystalline lens. Genetics and environment are vital factors that influence normal lens development. During maturation, LECs help maintain lens homeostasis through material transport, synthesis and metabolism as well as mitosis and proliferation. If disturbed, this will result in loss of lens transparency. After cataract surgery, the repair potential of LECs is activated and the structure and transparency of the regenerative tissue depends on postoperative microenvironment. This review summarizes recent research advances on the role of LECs in lens development, homeostasis, and regeneration, with a particular focus on the role of cholesterol synthesis (eg., lanosterol synthase) in lens development and homeostasis maintenance, and how the regenerative potential of LECs can be harnessed to develop surgical strategies and improve the outcomes of cataract surgery (Fig. 1). These new insights suggest that LECs are a major determinant of the physiological and pathological state of the lens. Further studies on their molecular biology will offer possibility to explore new approaches for cataract prevention and treatment.
Collapse
Affiliation(s)
- Zhenzhen Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Shan Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yingfeng Zheng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Tian Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Leyi Hu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Lang Xiong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - David Wan-Cheng Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China; Research Unit of Ocular Development and Regeneration, Chinese Academy of Medical Sciences, Beijing, 100085, China.
| |
Collapse
|
9
|
Zhou L, Sun X, Wang X, Liu K, Zhong Z, Chen J. Identification and functional analysis of two GJA8 variants in Chinese families with eye anomalies. Mol Genet Genomics 2022; 297:1553-1564. [PMID: 35980487 DOI: 10.1007/s00438-022-01939-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 07/30/2022] [Indexed: 11/30/2022]
Abstract
In this study, we report on two different GJA8 variants related to congenital eye anomalies in two unrelated families, respectively. GJA8 (or Cx50) encoding a transmembrane protein to form lens connexons has been known as a common causative gene in congenital cataracts and its variants have recently been reported related to a wide phenotypic spectrum of eye defects. We identified two GJA8 variants, c.134G>T (p.Try45Leu, W45L) detected in a cataract family by Sanger sequencing and c.281G>A (p.Gly94Glu, G94E) found in a family with severe eye malformations including microphthalmia by whole-exome sequencing. These two variants were absent in healthy population and predicted deleterious by bioinformatic analysis. Furthermore, we compared the expression in cell lines between these mutants and the wildtype to explore their potential mechanism. Cell counting kit-8 assay showed that overexpression of either W45L or G94E decreased cell viability compared with wild-type Cx50 and the control. A lower protein level in W45L found by western blotting and fewer punctate fluorescent signals showed by fluorescence microscopy suggested that W45L may have less protein expression. A higher G94E protein level and abundant dotted distribution indicated that G94E may cause aberrant protein degradation and accumulation. Such results from in vitro assays confirmed the impact of these two variants and gave us a hint about their different pathogenic roles in different phenotypes. In conclusion, our study is the first to have the functional analysis of two GJA8 variants c.134G>T and c.281G>A in Chinese pedigrees and explore the impact of these variants, which can help in prenatal diagnosis and genetic counseling as well in basic studies on GJA8.
Collapse
Affiliation(s)
- Linlin Zhou
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China.,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China
| | - Xuejiao Sun
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China.,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China
| | - Xinyao Wang
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China.,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China
| | - Kangyu Liu
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China.,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China
| | - Zilin Zhong
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China.,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China
| | - Jianjun Chen
- Department of Pediatrics, Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Key Laboratory of Anesthesiology and Brain Functional Modulation, Shanghai Fourth People's Hospital, School of Medicine, Tongji University, Shanghai, 200434, China. .,Department of Medical Genetics, School of Medicine, Tongji University, Room 505, Birth defect group, Medical Wing Building, 1239 Siping Road, Yangpu District, Shanghai, 200092, China.
| |
Collapse
|
10
|
Connexin Mutations and Hereditary Diseases. Int J Mol Sci 2022; 23:ijms23084255. [PMID: 35457072 PMCID: PMC9027513 DOI: 10.3390/ijms23084255] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/04/2022] [Accepted: 04/09/2022] [Indexed: 02/01/2023] Open
Abstract
Inherited diseases caused by connexin mutations are found in multiple organs and include hereditary deafness, congenital cataract, congenital heart diseases, hereditary skin diseases, and X-linked Charcot–Marie–Tooth disease (CMT1X). A large number of knockout and knock-in animal models have been used to study the pathology and pathogenesis of diseases of different organs. Because the structures of different connexins are highly homologous and the functions of gap junctions formed by these connexins are similar, connexin-related hereditary diseases may share the same pathogenic mechanism. Here, we analyze the similarities and differences of the pathology and pathogenesis in animal models and find that connexin mutations in gap junction genes expressed in the ear, eye, heart, skin, and peripheral nerves can affect cellular proliferation and differentiation of corresponding organs. Additionally, some dominant mutations (e.g., Cx43 p.Gly60Ser, Cx32 p.Arg75Trp, Cx32 p.Asn175Asp, and Cx32 p.Arg142Trp) are identified as gain-of-function variants in vivo, which may play a vital role in the onset of dominant inherited diseases. Specifically, patients with these dominant mutations receive no benefits from gene therapy. Finally, the complete loss of gap junctional function or altered channel function including permeability (ions, adenosine triphosphate (ATP), Inositol 1,4,5-trisphosphate (IP3), Ca2+, glucose, miRNA) and electric activity are also identified in vivo or in vitro.
Collapse
|
11
|
Li Z, Quan Y, Gu S, Jiang JX. Beyond the Channels: Adhesion Functions of Aquaporin 0 and Connexin 50 in Lens Development. Front Cell Dev Biol 2022; 10:866980. [PMID: 35465319 PMCID: PMC9022433 DOI: 10.3389/fcell.2022.866980] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
Lens, an avascular tissue involved in light transmission, generates an internal microcirculatory system to promote ion and fluid circulation, thus providing nutrients to internal lens cells and excreting the waste. This unique system makes up for the lack of vasculature and distinctively maintains lens homeostasis and lens fiber cell survival through channels of connexins and other transporters. Aquaporins (AQP) and connexins (Cx) comprise the majority of channels in the lens microcirculation system and are, thus, essential for lens development and transparency. Mutations of AQPs and Cxs result in abnormal channel function and cataract formation. Interestingly, in the last decade or so, increasing evidence has emerged suggesting that in addition to their well-established channel functions, AQP0 and Cx50 play pivotal roles through channel-independent actions in lens development and transparency. Specifically, AQP0 and Cx50 have been shown to have a unique cell adhesion function that mediates lens development and transparency. Precise regulation of cell-matrix and cell-cell adhesion is necessary for cell migration, a critical process during lens development. This review will provide recent advances in basic research of cell adhesion mediated by AQP0 and Cx50.
Collapse
Affiliation(s)
- Zhen Li
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Yumeng Quan
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Sumin Gu
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| |
Collapse
|
12
|
Retamal MA, Altenberg GA. Role and Posttranslational Regulation of Cx46 Hemichannels and Gap Junction Channels in the Eye Lens. Front Physiol 2022; 13:864948. [PMID: 35431975 PMCID: PMC9006113 DOI: 10.3389/fphys.2022.864948] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 03/14/2022] [Indexed: 12/31/2022] Open
Abstract
Connexins are a family of proteins that can form two distinct types of channels: hemichannels and gap junction channels. Hemichannels are composed of six connexin subunits and when open allow for exchanges between the cytoplasm and the extracellular milieu. Gap junction channels are formed by head-to-head docking of two hemichannels in series, each one from one of two adjacent cells. These channels allow for exchanges between the cytoplasms of contacting cells. The lens is a transparent structure located in the eye that focuses light on the retina. The transparency of the lens depends on its lack of blood irrigation and the absence of organelles in its cells. To survive such complex metabolic scenario, lens cells express Cx43, Cx46 and Cx50, three connexins isoforms that form hemichannels and gap junction channels that allow for metabolic cooperation between lens cells. This review focuses on the roles of Cx46 hemichannels and gap junction channels in the lens under physiological conditions and in the formation of cataracts, with emphasis on the modulation by posttranslational modifications.
Collapse
Affiliation(s)
- Mauricio A. Retamal
- Universidad del Desarrollo, Centro de Fisiología Celular e Integrativa, Clínica Alemana Facultad de Medicina, Santiago, Chile
- Universidad del Desarrollo, Programa de Comunicación Celular en Cáncer, Clínica Alemana Facultad de Medicina, Santiago, Chile
- Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- *Correspondence: Mauricio A. Retamal, ; Guillermo A. Altenberg,
| | - Guillermo A. Altenberg
- Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
- *Correspondence: Mauricio A. Retamal, ; Guillermo A. Altenberg,
| |
Collapse
|
13
|
van der Sande E, Haarman AEG, Quint WH, Tadema KCD, Meester-Smoor MA, Kamermans M, De Zeeuw CI, Klaver CCW, Winkelman BHJ, Iglesias AI. The Role of GJD2(Cx36) in Refractive Error Development. Invest Ophthalmol Vis Sci 2022; 63:5. [PMID: 35262731 PMCID: PMC8934558 DOI: 10.1167/iovs.63.3.5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/16/2022] [Indexed: 02/06/2023] Open
Abstract
Refractive errors are common eye disorders characterized by a mismatch between the focal power of the eye and its axial length. An increased axial length is a common cause of the refractive error myopia (nearsightedness). The substantial increase in myopia prevalence over the last decades has raised public health concerns because myopia can lead to severe ocular complications later in life. Genomewide association studies (GWAS) have made considerable contributions to the understanding of the genetic architecture of refractive errors. Among the hundreds of genetic variants identified, common variants near the gap junction delta-2 (GJD2) gene have consistently been reported as one of the top hits. GJD2 encodes the connexin 36 (Cx36) protein, which forms gap junction channels and is highly expressed in the neural retina. In this review, we provide current evidence that links GJD2(Cx36) to the development of myopia. We summarize the gap junctional communication in the eye and the specific role of GJD2(Cx36) in retinal processing of visual signals. Finally, we discuss the pathways involving dopamine and gap junction phosphorylation and coupling as potential mechanisms that may explain the role of GJD2(Cx36) in refractive error development.
Collapse
Affiliation(s)
- Emilie van der Sande
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
| | - Annechien E. G. Haarman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Wim H. Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kirke C. D. Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A. Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Maarten Kamermans
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Biomedical Physics and Biomedical Photonics, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Chris I. De Zeeuw
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland
| | - Beerend H. J. Winkelman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience (NIN), Royal Dutch Academy of Art & Science (KNAW), Amsterdam, The Netherlands
- Department of Neuroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adriana I. Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| |
Collapse
|
14
|
Giannone AA, Li L, Sellitto C, White TW. Physiological Mechanisms Regulating Lens Transport. Front Physiol 2022; 12:818649. [PMID: 35002784 PMCID: PMC8735835 DOI: 10.3389/fphys.2021.818649] [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] [Received: 11/19/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
The transparency and refractive properties of the lens are maintained by the cellular physiology provided by an internal microcirculation system that utilizes spatial differences in ion channels, transporters and gap junctions to establish standing electrochemical and hydrostatic pressure gradients that drive the transport of ions, water and nutrients through this avascular tissue. Aging has negative effects on lens transport, degrading ion and water homeostasis, and producing changes in lens water content. This alters the properties of the lens, causing changes in optical quality and accommodative amplitude that initially result in presbyopia in middle age and ultimately manifest as cataract in the elderly. Recent advances have highlighted that the lens hydrostatic pressure gradient responds to tension transmitted to the lens through the Zonules of Zinn through a mechanism utilizing mechanosensitive channels, multiple sodium transporters respond to changes in hydrostatic pressure to restore equilibrium, and that connexin hemichannels and diverse intracellular signaling cascades play a critical role in these responses. The mechanistic insight gained from these studies has advanced our understanding of lens transport and how it responds and adapts to different inputs both from within the lens, and from surrounding ocular structures.
Collapse
Affiliation(s)
- Adrienne A Giannone
- Master of Science Program, Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
| | - Leping Li
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Caterina Sellitto
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Thomas W White
- Department of Physiology and Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| |
Collapse
|
15
|
Vanita V, Goyal S, Tibrewal S, Ganesh S. Molecular diagnosis of autosomal dominant congenital cataract in two families from North India reveals a novel and a known variant in GJA8 and GJA3. Front Pediatr 2022; 10:1003909. [PMID: 36533234 PMCID: PMC9755747 DOI: 10.3389/fped.2022.1003909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 11/11/2022] [Indexed: 12/05/2022] Open
Abstract
AIMS The study aims to detect the underlying genetic defect in two autosomal dominant congenital cataract (ADCC) families. METHODS A detailed family history was collected, pedigrees were drawn, and slit-lamp examination and lens photography were performed. Mutation screening was carried out in the genes for crystallins and connexins by PCR and Sanger sequencing. Ethnically matched controls were tested for the identified variants. Different bioinformatics tools were used to assess the pathogenicity of the observed variants. RESULTS In an ADCC family with total cataract, a novel change (c.166A > G) (p.Thr56Ala) in GJA8 was identified. In another ADCC family with nuclear cataract, c.134G > C (p.Trp45Ser) in GJA3 has been detected. These variants co-segregated completely in patients in their respective families and were neither observed in unaffected family members nor in ethnically matched 100 controls, excluding them as polymorphisms. CONCLUSIONS The present study identifies a novel variant c.166A > G (p.Thr56Ala) in GJA8 in an ADCC family having total cataract and a previously known mutation c.134G > C (p.Trp45Ser) in GJA3 in another ADCC family. Thr56 in GJA8 seems to be a mutation hotspot, as previously an ADCC Mauritanian family harbored a different substitution (p.Thr56Pro) at the same codon, although for a different phenotype (nuclear cataract). Similarly, Trp45 in GJA3 appears as a mutation hotspot, as p.Trp45Ser has previously been reported for nuclear cataract in a Chinese ADCC family. p.Thr56 (GJA8) and p.Trp45 (GJA3) are in the extracellular loop 1 (EL1) in their respective connexin proteins, which, along with EL2, are essential for gap junction formation, hemichannel docking, and regulating the voltage gating of the channels. Hence, residues in these regions seem crucial for maintaining eye lens transparency.
Collapse
Affiliation(s)
- Vanita Vanita
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India
| | - Shiwali Goyal
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, India
| | - Shailja Tibrewal
- Department of Pediatric Ophthalmology, Strabismus and Neuro-Ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, India.,Department of Ocular Genetics, Dr. Shroff's Charity Eye Hospital, Daryaganj, India
| | - Suma Ganesh
- Department of Pediatric Ophthalmology, Strabismus and Neuro-Ophthalmology, Dr. Shroff's Charity Eye Hospital, Daryaganj, India
| |
Collapse
|
16
|
Hassan AY, Yousaf S, Levin MR, Saeedi OJ, Riazuddin S, Alexander JL, Ahmed ZM. Novel Homozygous Missense Variant in GJA3 Connexin Domain Causing Congenital Nuclear and Cortical Cataracts. Int J Mol Sci 2021; 23:240. [PMID: 35008666 PMCID: PMC8745576 DOI: 10.3390/ijms23010240] [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: 11/15/2021] [Revised: 12/17/2021] [Accepted: 12/24/2021] [Indexed: 11/29/2022] Open
Abstract
Congenital cataracts (CC) are responsible for approximately one-tenth of childhood blindness cases globally. Here, we report an African American family with a recessively inherited form of CC. The proband demonstrated decreased visual acuity and bilateral cataracts, with nuclear and cortical cataracts in the right and left eye, respectively. Exome sequencing revealed a novel homozygous variant (c.563A > G; p.(Asn188Ser)) in GJA3, which was predicted to be pathogenic by structural analysis. Dominantly inherited variants in GJA3 are known to cause numerous types of cataracts in various populations. Our study represents the second case of recessive GJA3 allele, and the first report in African Americans. These results validate GJA3 as a bona fide gene for recessively inherited CC in humans.
Collapse
Affiliation(s)
- Abdullah Y. Hassan
- Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (A.Y.H.); (S.Y.); (S.R.)
| | - Sairah Yousaf
- Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (A.Y.H.); (S.Y.); (S.R.)
| | - Moran R. Levin
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (M.R.L.); (O.J.S.)
| | - Osamah J. Saeedi
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (M.R.L.); (O.J.S.)
| | - Saima Riazuddin
- Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (A.Y.H.); (S.Y.); (S.R.)
- Department of Molecular Biology and Biochemistry, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Janet L. Alexander
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (M.R.L.); (O.J.S.)
| | - Zubair M. Ahmed
- Department of Otorhinolaryngology Head and Neck Surgery, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (A.Y.H.); (S.Y.); (S.R.)
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Maryland, Baltimore, MD 21201, USA; (M.R.L.); (O.J.S.)
- Department of Molecular Biology and Biochemistry, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| |
Collapse
|
17
|
Tiwari R, Sethiya NK, Gulbake AS, Mehra NK, Murty USN, Gulbake A. A review on albumin as a biomaterial for ocular drug delivery. Int J Biol Macromol 2021; 191:591-599. [PMID: 34562538 DOI: 10.1016/j.ijbiomac.2021.09.112] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 02/06/2023]
Abstract
Development of ocular drug delivery system is one of the most technically challenging tasks, when compared with other routes of drug delivery. Eye (an intricate organ) is highly sophisticated and sensitive organ due to presence of various structurally differed anatomical layers, which many times limits the drug delivery approaches. Despite several limitations, many advancements have been made as evidence from various recent studies involving improvement of both residence time and permeation of the drug at the ocular region. In the last few decades, albumin(s) based ophthalmic products have been gained most attention to solve the major challenges associated with conventional ocular drug delivery systems. Interestingly, an albumin-based micro, nano, conjugates, and genetically fused target specific to ligand(s) formulation being exploited through many studies for successful ocular delivery of bioactives (mostly repurposed drugs). Past and current studies suggested that albumin(s) based ocular drug delivery system is multifunctional in nature and capable of extending both drug residence time and sustaining the release of drugs to deliver desired pharmacological outcomes. Despite wide applications, still complete progress made in albumin based ocular drug delivery is limited in literature and missing in market. So, herein we presented an overview to explore the key concepts of albumin-based nanocarrier(s) including strategies involved in the treatment of ocular disease, that have yet to be explored.
Collapse
Affiliation(s)
- Rahul Tiwari
- Faculty of Pharmacy, DIT University, Mussoorie Diversion Road, Dehradun, Uttarakhand 248009, India
| | - Neeraj K Sethiya
- Faculty of Pharmacy, DIT University, Mussoorie Diversion Road, Dehradun, Uttarakhand 248009, India
| | - Anamika Sahu Gulbake
- Faculty of Pharmacy, DIT University, Mussoorie Diversion Road, Dehradun, Uttarakhand 248009, India
| | - Neelesh Kumar Mehra
- Pharmaceutical Nanotechnology Research Laboratory, Department of Pharmaceutics, National Institute of Pharmaceutical Education & Research (NIPER), Hyderabad, Telangana 500037, India
| | - U S N Murty
- National Institute of Pharmaceutical Education & Research (NIPER), Guwahati, Assam 781101, India
| | - Arvind Gulbake
- Department of Pharmaceutics, National Institute of Pharmaceutical Education & Research (NIPER), Guwahati, Assam 781101, India.
| |
Collapse
|
18
|
Modeling congenital cataract in vitro using patient-specific induced pluripotent stem cells. NPJ Regen Med 2021; 6:60. [PMID: 34599192 PMCID: PMC8486789 DOI: 10.1038/s41536-021-00171-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 09/01/2021] [Indexed: 11/30/2022] Open
Abstract
Congenital cataracts are the leading cause of childhood blindness. To date, surgical removal of cataracts is the only established treatment, but surgery is associated with multiple complications, which often lead to visual impairment. Therefore, mechanistic studies and drug-candidate screening have been intrigued by the aims of developing novel therapeutic strategies. However, these studies have been hampered by a lack of an appropriate human-disease model of congenital cataracts. Herein, we report the establishment of a human congenital cataract in vitro model through differentiation of patient-specific induced pluripotent stem cells (iPSCs) into regenerated lenses. The regenerated lenses derived from patient-specific iPSCs with known causative mutations of congenital cataracts (CRYBB2 [p. P24T] and CRYGD [p. Q155X]) showed obvious opacification that closely resembled that seen in patients’ cataracts in terms of opacification severity and disease course accordingly, as compared with lentoid bodies (LBs) derived from healthy individuals. Increased protein aggregation and decreased protein solubility corresponding to the patients’ cataract severity were observed in the patient-specific LBs and were attenuated by lanosterol treatment. Taken together, the in vitro model described herein, which recapitulates patient-specific clinical manifestations of congenital cataracts and protein aggregation in patient-specific LBs, provides a robust system for research on the pathological mechanisms of cataracts and screening of drug candidates for cataract treatment.
Collapse
|
19
|
Gong XD, Wang Y, Hu XB, Zheng SY, Fu JL, Nie Q, Wang L, Hou M, Xiang JW, Xiao Y, Gao Q, Bai YY, Liu YZ, Li DWC. Aging-dependent loss of GAP junction proteins Cx46 and Cx50 in the fiber cells of human and mouse lenses accounts for the diminished coupling conductance. Aging (Albany NY) 2021; 13:17568-17591. [PMID: 34226295 PMCID: PMC8312418 DOI: 10.18632/aging.203247] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 06/12/2021] [Indexed: 06/13/2023]
Abstract
The homeostasis of the ocular lens is maintained by a microcirculation system propagated through gap junction channels. It is well established that the intercellular communications of the lens become deteriorative during aging. However, the molecular basis for this change in human lenses has not been well defined. Here, we present evidence to show that over 90% of Cx46 and Cx50 are lost in the fiber cells of normal human lenses aged 50 and above. From transparent to cataractous lenses, while Cx43 was upregulated, both Cx46 and Cx50 were significantly down-regulated in the lens epithelia. During aging of mouse lenses, Cx43 remained unchanged, but both Cx46 and Cx50 were significantly downregulated. Under oxidative stress treatment, mouse lenses develop in vitro cataractogenesis. Associated with this process, Cx43 was significantly upregulated, in contrast, Cx46 and Cx50 were sharply downregulated. Together, our results for the first time reveal that downregulation in Cx46 and Cx50 levels appears to be the major reason for the diminished coupling conductance, and the aging-dependent loss of Cx46 and Cx50 promotes senile cataractogenesis.
Collapse
Affiliation(s)
- Xiao-Dong Gong
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yan Wang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Xue-Bin Hu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Shu-Yu Zheng
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Jia-Ling Fu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Qian Nie
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Ling Wang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Min Hou
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Jia-Wen Xiang
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yuan Xiao
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Qian Gao
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yue-Yue Bai
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - Yi-Zhi Liu
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| | - David Wan-Cheng Li
- The State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, Guangdong 510230, China
| |
Collapse
|
20
|
Srivastava P, Kane A, Harrison C, Levin M. A Meta-Analysis of Bioelectric Data in Cancer, Embryogenesis, and Regeneration. Bioelectricity 2021; 3:42-67. [PMID: 34476377 DOI: 10.1089/bioe.2019.0034] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Developmental bioelectricity is the study of the endogenous role of bioelectrical signaling in all cell types. Resting potentials and other aspects of ionic cell physiology are known to be important regulatory parameters in embryogenesis, regeneration, and cancer. However, relevant quantitative measurement and genetic phenotyping data are distributed throughout wide-ranging literature, hampering experimental design and hypothesis generation. Here, we analyze published studies on bioelectrics and transcriptomic and genomic/phenotypic databases to provide a novel synthesis of what is known in three important aspects of bioelectrics research. First, we provide a comprehensive list of channelopathies-ion channel and pump gene mutations-in a range of important model systems with developmental patterning phenotypes, illustrating the breadth of channel types, tissues, and phyla (including man) in which bioelectric signaling is a critical endogenous aspect of embryogenesis. Second, we perform a novel bioinformatic analysis of transcriptomic data during regeneration in diverse taxa that reveals an electrogenic protein to be the one common factor specifically expressed in regeneration blastemas across Kingdoms. Finally, we analyze data on distinct Vmem signatures in normal and cancer cells, revealing a specific bioelectrical signature corresponding to some types of malignancies. These analyses shed light on fundamental questions in developmental bioelectricity and suggest new avenues for research in this exciting field.
Collapse
Affiliation(s)
- Pranjal Srivastava
- Rye High School, Rye, New York, USA; Current Affiliation: College of Chemistry, University of California, Berkeley, Berkeley, California, USA
| | - Anna Kane
- Department of Biology, Allen Discovery Center, Tufts University, Medford, Massachusetts, USA
| | - Christina Harrison
- Department of Biology, Allen Discovery Center, Tufts University, Medford, Massachusetts, USA
| | - Michael Levin
- Department of Biology, Allen Discovery Center, Tufts University, Medford, Massachusetts, USA
| |
Collapse
|
21
|
Brink PR, Valiunas V, White TW. Lens Connexin Channels Show Differential Permeability to Signaling Molecules. Int J Mol Sci 2020; 21:ijms21186943. [PMID: 32971763 PMCID: PMC7555617 DOI: 10.3390/ijms21186943] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 12/12/2022] Open
Abstract
Gap junction channels mediate the direct intercellular passage of small ions as well as larger solutes such as second messengers. A family of proteins called connexins make up the subunits of gap junction channels in chordate animals. Each individual connexin forms channels that exhibit distinct permeability to molecules that influence cellular signaling, such as calcium ions, cyclic nucleotides, or inositol phosphates. In this review, we examine the permeability of connexin channels containing Cx43, Cx46, and Cx50 to signaling molecules and attempt to relate the observed differences in permeability to possible in vivo consequences that were revealed by studies of transgenic animals where these connexin genes have been manipulated. Taken together, these data suggest that differences in the permeability of individual connexin channels to larger solutes like 3',5'-cyclic adenosine monophosphate (cAMP) and inositol 1,4,5-trisphosphate (IP3) could play a role in regulating epithelial cell division, differentiation, and homeostasis in organs like the ocular lens.
Collapse
|
22
|
Tjahjono N, Xia CH, Li R, Chu S, Wang J, Gong X. Connexin 50-R205G Mutation Perturbs Lens Epithelial Cell Proliferation and Differentiation. Invest Ophthalmol Vis Sci 2020; 61:25. [PMID: 32182330 PMCID: PMC7401428 DOI: 10.1167/iovs.61.3.25] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Purpose To investigate the underlying mechanisms for how the mouse Cx50-R205G point mutation, a homologue of the human Cx50-R198W mutation that is linked to cataract-microcornea syndrome, affects proper lens growth and fiber cell differentiation to lead to severe lens phenotypes. Methods EdU labeling, immunostaining, confocal imaging analysis, and primary lens epithelial cell culture were performed to characterize the lens epithelial cell (LEC) proliferation and fiber cell differentiation in wild-type and Cx50-R205G mutant lenses in vivo and in vitro. Results The Cx50-R205G mutation severely disrupts the lens size and transparency. Heterozygous and homozygous Cx50-R205G mutant and Cx50 knockout lenses all show decreased central epithelium proliferation while only the homozygous Cx50-R205G mutant lenses display obviously decreased proliferating LECs in the germinative zone of neonatal lenses. Cultured Cx50-R205G lens epithelial cells reveal predominantly reduced Cx50 gap junction staining but no change of the endoplasmic reticulum stress marker BiP. The heterozygous Cx50-R205G lens fibers show moderately disrupted Cx50 and Cx46 gap junctions while the homozygous Cx50-R205G lens fibers have drastically reduced Cx50 and Cx46 gap junctions with severely altered fiber cell shape in vivo. Conclusions The Cx50-R205G mutation inhibits both central and equatorial lens epithelial cell proliferation to cause small lenses. This mutation also disrupts the assembly and functions of both Cx50 and Cx46 gap junctions in lens fibers to alter fiber cell differentiation and shape to lead to severe lens phenotypes.
Collapse
|
23
|
Valiunas V, White TW. Connexin43 and connexin50 channels exhibit different permeability to the second messenger inositol triphosphate. Sci Rep 2020; 10:8744. [PMID: 32457413 PMCID: PMC7251084 DOI: 10.1038/s41598-020-65761-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/07/2020] [Indexed: 11/12/2022] Open
Abstract
Gap junction channels made of different connexins have distinct permeability to second messengers, which could affect many cell processes, including lens epithelial cell division. Here, we have compared the permeability of IP3 and Ca2+ through channels made from two connexins, Cx43 and Cx50, that are highly expressed in vertebrate lens epithelial cells. Solute transfer was measured while simultaneously monitoring junctional conductance via dual whole-cell/perforated patch clamp. HeLa cells expressing Cx43 or Cx50 were loaded with Fluo-8, and IP3 or Ca2+ were delivered via patch pipette to one cell of a pair, or to a monolayer while fluorescence intensity changes were recorded. Cx43 channels were permeable to IP3 and Ca2+. Conversely, Cx50 channels were impermeable to IP3, while exhibiting high permeation of Ca2+. Reduced Cx50 permeability to IP3 could play a role in regulating cell division and homeostasis in the lens.
Collapse
Affiliation(s)
- Virginijus Valiunas
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA
| | - Thomas W White
- The Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY, 11794, USA.
| |
Collapse
|
24
|
Muir ER, Pan X, Donaldson PJ, Vaghefi E, Jiang Z, Sellitto C, White TW. Multi-parametric MRI of the physiology and optics of the in-vivo mouse lens. Magn Reson Imaging 2020; 70:145-154. [PMID: 32380160 DOI: 10.1016/j.mri.2020.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/30/2020] [Accepted: 04/19/2020] [Indexed: 02/07/2023]
Abstract
The optics of the ocular lens are determined by its geometry (shape and volume) and its inherent gradient of refractive index (water to protein ratio), which are in turn maintained by unique cellular physiology known as the lens internal microcirculation system. Previously, magnetic resonance imaging (MRI) has been used on ex vivo organ cultured bovine lenses to show that pharmacological perturbations to this microcirculation system disrupt ionic and fluid homeostasis and overall lens optics. In this study, we have optimised in vivo MRI protocols for use on wild-type and transgenic mouse models so that the effects of genetically perturbing the lens microcirculation system on lens properties can be studied. In vivo MRI protocols and post-analysis methods for studying the mouse lens were optimised and used to measure the lens geometry, diffusion, T1 and T2, as well as the refractive index (n) calculated from T2, in wild-type mice and the genetically modified Cx50KI46 mouse. In this animal line, gap junctional coupling in the lens is increased by knocking in the gap junction protein Cx46 into the Cx50 locus. Relative to wild-type mice, Cx50KI46 mice showed significantly reduced lens size and radius of curvature, increased T1 and T2 values, and decreased n in the lens nucleus, which was consistent with the developmental and functional changes characterised previously in this lens model. These proof of principle experiments show that in vivo MRI can be applied to transgenic mouse models to gain mechanistic insights into the relationship between lens physiology and optics, and in the future suggest that longitudinal studies can be performed to determine how this relationship is altered by age in mouse models of cataract.
Collapse
Affiliation(s)
- Eric R Muir
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Xingzheng Pan
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Paul J Donaldson
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand; Department of Physiology, School of Medical Sciences, University of Auckland, New Zealand
| | - Ehsan Vaghefi
- School of Optometry and Vision Science, New Zealand National Eye Centre, University of Auckland, New Zealand
| | - Zhao Jiang
- Department of Radiology, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Caterina Sellitto
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Thomas W White
- Department of Physiology & Biophysics, School of Medicine, Stony Brook University, Stony Brook, NY, USA.
| |
Collapse
|
25
|
Biological convergence of three human and animal model quantitative trait loci for blood pressure. J Hypertens 2020; 38:322-331. [DOI: 10.1097/hjh.0000000000002267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
26
|
Li L, Fan DB, Zhao YT, Li Y, Yang ZB, Zheng GY. GJA8 missense mutation disrupts hemichannels and induces cell apoptosis in human lens epithelial cells. Sci Rep 2019; 9:19157. [PMID: 31844091 PMCID: PMC6915756 DOI: 10.1038/s41598-019-55549-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 11/29/2019] [Indexed: 12/16/2022] Open
Abstract
Autosomal dominant congenital cataract (ADCC), the most common hereditary disease, is a major cause of eye disease in children. Due to its high genetic and clinical heterogeneity, the identification of ADCC-associated gene mutations is essential for the development of molecular therapies. In this study, we examined a four-generation Chinese pedigree with ADCC and identified putative mutations in ADCC candidate genes via next-generation sequencing (NGS) followed by Sanger sequencing. A novel missense mutation in GJA8 (c.T217C) in ADCC patients causes a serine-to-proline substitution at residue 73 of connexin 50 (Cx50); no mutation was found in unaffected family members and unrelated healthy individuals. Functional analysis revealed that this missense mutation disrupts protein function in human lens epithelial cells (HLEpiCs), which fails to form calcium-sensitive hemichannels. Furthermore, mutant Cx50 leads to decreased ROS scavenging by inhibiting G6PD expression and thus induces cell apoptosis via aberrant activation of the unfolded protein response (UPR). In conclusion, we report a novel GJA8 heterozygous mutation in a Chinese family with a vital role in ADCC, broadening the genetic spectrum of this disease.
Collapse
Affiliation(s)
- Li Li
- Ophthalmologic Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Da-Bei Fan
- Endocrine Department, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Ya-Ting Zhao
- Ophthalmologic Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Yun Li
- Ophthalmologic Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Zi-Bing Yang
- Ophthalmologic Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Guang-Ying Zheng
- Ophthalmologic Center, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China.
| |
Collapse
|
27
|
Wu X, Zhang W, Li Y, Lin X. Structure and Function of Cochlear Gap Junctions and Implications for the Translation of Cochlear Gene Therapies. Front Cell Neurosci 2019; 13:529. [PMID: 31827424 PMCID: PMC6892400 DOI: 10.3389/fncel.2019.00529] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/13/2019] [Indexed: 12/23/2022] Open
Abstract
Connexins (Cxs) are ubiquitous membrane proteins that are found throughout vertebrate organs, acting as building blocks of the gap junctions (GJs) known to play vital roles in the normal function of many organs. Mutations in Cx genes (particularly GJB2, which encodes Cx26) cause approximately half of all cases of congenital hearing loss in newborns. Great progress has been made in understanding GJ function and the molecular mechanisms for the role of Cxs in the cochlea. Data reveal that multiple types of Cxs work together to ensure normal development and function of the cochlea. These findings include many aspects not proposed in the classic K+ recycling theory, such as the formation of normal cochlear morphology (e.g., the opening of the tunnel of Corti), the fine-tuning of the innervation of nerve fibers to the hair cells (HCs), the maturation of the ribbon synapses, and the initiation of the endocochlear potential (EP). New data, especially those collected from targeted modification of major Cx genes in the mouse cochlea, have demonstrated that Cx26 plays an essential role in the postnatal maturation of the cochlea. Studies also show that Cx26 and Cx30 assume very different roles in the EP generation, given that only Cx26 is required for normal hearing. This article will review our current understanding of the molecular structure, cellular distribution, and major functions of cochlear GJs. Potential implications of the knowledge of cochlear GJs on the design and implementation of translational studies of cochlear gene therapies for Cx mutations are also discussed.
Collapse
Affiliation(s)
- Xuewen Wu
- Department of Otolaryngology, Head-Neck and Surgery, Xiangya Hospital of Central South University, Changsha, China
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
| | - Wenjuan Zhang
- Department of Otolaryngology, Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yihui Li
- Department of Pharmacy, Changsha Hospital of Traditional Medicine, Changsha, China
| | - Xi Lin
- Department of Otolaryngology, Emory University School of Medicine, Atlanta, GA, United States
| |
Collapse
|
28
|
Expression pattern of Connexin 26 and Connexin 30 in mature cochlea of the monkey. Biochem Biophys Res Commun 2019; 518:357-361. [PMID: 31421828 DOI: 10.1016/j.bbrc.2019.08.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/11/2019] [Indexed: 10/26/2022]
Abstract
Connexin26 (Cx26) and Cx30 are the predominant connexin subtypes found in the cochlea. They play an essential role in the cochlear functions. However, most studies use mice and the data on the cochlear expression profiles of the two Cxs in higher animals (e.g., humans) are scarce. Studies using the cochleae from non-human primate other than mice may provide information needed to narrow this gap. Here we studied cellular distributions of Cx26 and Cx30 in the adult monkey and guinea pig cochleae by immunofluorescent labeling and confocal microscopy observations. We detected Cx26 and Cx30 expressions in the type I, II& V fibrocytes in the spiral ligament, fibrocytes of the spiral limbus, in the supporting cells of organ of Corti, inner and outer sulcus cells, and in the basal cells of the stria vascularis. Both Cx26 and Cx30 were not detected in hair cells, in mesenchymal cells under the basilar membrane and cells lining the scala vestibule. Cells of the Reissner's membrane and spiral ganglion neurons are also negative. These findings demonstrate that cochlear expressions of Cx26 and Cx30 in the adult mouse, guinea pig and non-human primate have a common cellular pattern.
Collapse
|
29
|
Ye Y, Wu M, Qiao Y, Xie T, Yu Y, Yao K. Identification and preliminary functional analysis of two novel congenital cataract associated mutations of Cx46 and Cx50. Ophthalmic Genet 2019; 40:428-435. [PMID: 31618082 DOI: 10.1080/13816810.2019.1675179] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 09/10/2019] [Accepted: 09/25/2019] [Indexed: 01/24/2023]
Abstract
Background: Congenital cataract is a significant cause of visual impairment and blindness. The present study examined the disease-causing mutations in three Chinese families with autosomal dominant congenital cataract (ADCC) to provide the preliminary evidence of the mechanisms underlying congenital cataract formation.Methods: Three pedigrees affected with ADCC were recruited. All participants underwent detailed ophthalmic examinations. Leucocyte DNA was extracted from venous blood for direct sequencing of candidate genes. In silico bioinformatics analysis was conducted to verify the functional impacts of the mutant proteins. Distribution patterns of connexin proteins were assessed through fluorescence microscopy using an enhanced green fluorescent protein (EGFP)-labeled expression vector in stably transfected Hek293 cells.Results: We identified three Chinese pedigrees with ADCC. Family 1 and family 2 presented with pulverized cataract and family 3 with an unknown phenotype. Direct sequencing of family 1 and family 2 revealed a missense mutation of c.64G>A encoding for G22S of connexin46 (Cx46), while a similar c.64G>A encoding for G22S of connexin50 (Cx50) was found in family 3; both mutations co-segregated well within all affected individuals in their families and were absent from 100 unrelated controls. Bioinformatics analysis revealed with high confidence that both mutations were deleterious. Confocal microscopy revealed the accumulation of both mutant connexins in the cytoplasm with punctate staining and a failure of gap junction formation between adjacent cells.Conclusions: Two novel G22S mutations of Cx46 and Cx50 were identified, and preliminary functional analysis revealed a potential deleterious effect of these mutations due to the malfunction of connexins.Abbreviations: ADCC: autosomal dominant congenital cataract; Cx26: connexin26; Cx32: connexin32; Cx46: connexin46; Cx46WT: wild-type connexin46; Cx50: Connexin50; Cx50WT: wild-type connexin50; DAPI: 4',6-diamidino-2-phenylindole; EGFP: enhanced green fluorescent protein; FBS: fetal bovine serum; GJA-:gap junction alpha-; PCR: polymerase chain reaction; PolyPhen: polymorphism phenotyping; PSIC: position-specific independent count; RPMI: Roswell Park Memorial Institute; TM1: first transmembrane.
Collapse
Affiliation(s)
- Yang Ye
- Department of Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, China
| | - Menghan Wu
- Intensive Care Unit, Zhejiang Hospital, Hangzhou, China
| | - Yue Qiao
- Institute of Translational Medicine, Zhejiang University, Hangzhou, China
| | - Tingting Xie
- Institute of Translational Medicine, Zhejiang University, Hangzhou, China
| | - Yinhui Yu
- Department of Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, China
| | - Ke Yao
- Department of Eye Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
- Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, China
| |
Collapse
|
30
|
Valiunas V, Brink PR, White TW. Lens Connexin Channels Have Differential Permeability to the Second Messenger cAMP. Invest Ophthalmol Vis Sci 2019; 60:3821-3829. [PMID: 31529078 PMCID: PMC6750889 DOI: 10.1167/iovs.19-27302] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 08/13/2019] [Indexed: 01/14/2023] Open
Abstract
Purpose Gap junction channels exhibit connexin specific biophysical properties, including the selective intercellular passage of larger solutes, such as second messengers. Here, we have examined the cyclic nucleotide permeability of the lens connexins, which could influence events like epithelial cell division and differentiation. Methods We compared the cAMP permeability through channels composed of Cx43, Cx46, or Cx50 using simultaneous measurements of junctional conductance and intercellular transfer. For cAMP detection, the recipient cells were transfected with a cAMP sensor gene, the cyclic nucleotide-modulated channel from sea urchin sperm (SpIH). cAMP was introduced via patch pipette into the cell of the pair that did not express SpIH. SpIH-derived currents were recorded from the other cell of a pair that expressed SpIH. cAMP permeability was also directly visualized in transfected cells using a chemically modified fluorescent form of the molecule. Results cAMP transfer was observed for homotypic Cx43 channels over a wide range of junctional conductance. Homotypic Cx46 channels also transferred cAMP, but permeability was reduced compared with Cx43. In contrast, homotypic Cx50 channels exhibited extremely low permeability to cAMP, when compared with either Cx43, or Cx46. Conclusions These data show that channels made from Cx43 and Cx46 result in the intercellular delivery of cAMP in sufficient quantity to activate cyclic nucleotide-modulated channels. The data also suggest that the greatly reduced cAMP permeability of Cx50 channels could play a role in the regulation of cell division in the lens.
Collapse
Affiliation(s)
- Virginijus Valiunas
- The Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Peter R. Brink
- The Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| | - Thomas W. White
- The Renaissance Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, New York, United States
| |
Collapse
|
31
|
Yan N, Xiao L, Hou C, Guo B, Fan W, Deng Y, Ma K. X-linked inheritances recessive of congenital nystagmus and autosomal dominant inheritances of congenital cataracts coexist in a Chinese family: a case report and literature review. BMC MEDICAL GENETICS 2019; 20:41. [PMID: 30890130 PMCID: PMC6423883 DOI: 10.1186/s12881-019-0780-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 03/07/2019] [Indexed: 02/05/2023]
Abstract
BACKGROUND Congenital nystagmus (CN) and congenital cataracts are distinct eye diseases and are usually isolated. Cases with CN and congenital cataracts caused by different genes in one family have been rarely reported. CASE PRESENTATION A 27-year-old man presented with CN and congenital cataracts and he underwent cataract extraction 2 weeks after birth. Three years later, he had posterior chamber intraocular lens implantation. The proband's mother was only afflicted by bilateral lens opacities. Lensectomy was performed in both eyes at age 15. The proband's daughter had bilateral central cataracts and no nystagmus. She had undergone cataract extraction when she was two months old. In this family, 8 affected individuals were affected by bilateral cataracts, and three of them presented with CN. The genetic analysis was performed using a specific Hereditary Ophthalmological Disease Gene Panel on proband and his parents (one of which was a patient). PCR and Sanger sequencing verified the presence of these variants in all members of the family. The novel mutation, c.498-3C > T, in FRMD7 explains why X-Linked recessive inheritance of CN was found in a subset of patients. A heterozygous mutation of the GJA8 gene (c.139G > C), was identified in all patients and thus explains the autosomal dominant pattern of inheritance of congenital cataracts within the family. CONCLUSIONS This is the first time that FRMD7 and GJA8 gene mutations have been linked to the pathogenesis of a family with both CN and congenital cataracts. The phenomenon of two different genetic patterns coexisting in one family is rare.
Collapse
Affiliation(s)
- Naihong Yan
- Research Laboratory of Ophthalmology and Vision Sciences, Torsten-Wiesel Research Institute of World Eye Organization, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Lirong Xiao
- Research Laboratory of Ophthalmology and Vision Sciences, Torsten-Wiesel Research Institute of World Eye Organization, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Chen Hou
- Research Laboratory of Ophthalmology and Vision Sciences, Torsten-Wiesel Research Institute of World Eye Organization, West China Hospital, Sichuan University, Chengdu, 610041, China.,Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Bo Guo
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Wei Fan
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Yingping Deng
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China
| | - Ke Ma
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, 610041, China.
| |
Collapse
|
32
|
Connexin43 mutations linked to skin disease have augmented hemichannel activity. Sci Rep 2019; 9:19. [PMID: 30631135 PMCID: PMC6328547 DOI: 10.1038/s41598-018-37221-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/04/2018] [Indexed: 01/22/2023] Open
Abstract
Mutations in the gene (GJA1) encoding connexin43 (Cx43) are responsible for several rare genetic disorders, including non-syndromic skin-limited diseases. Here we used two different functional expression systems to characterize three Cx43 mutations linked to palmoplantar keratoderma and congenital alopecia-1, erythrokeratodermia variabilis et progressiva, or inflammatory linear verrucous epidermal nevus. In HeLa cells and Xenopus oocytes, we show that Cx43-G8V, Cx43-A44V and Cx43-E227D all formed functional gap junction channels with the same efficiency as wild-type Cx43, with normal voltage gating and a unitary conductance of ~110 pS. In HeLa cells, all three mutations also localized to regions of cell-cell contact and displayed a punctate staining pattern. In addition, we show that Cx43-G8V, Cx43-A44V and Cx43-E227D significantly increase membrane current flow through formation of active hemichannels, a novel activity that was not displayed by wild-type Cx43. The increased membrane current was inhibited by either 2 mM calcium, or 5 µM gadolinium, mediated by hemichannels with a unitary conductance of ~250 pS, and was not due to elevated mutant protein expression. The three Cx43 mutations all showed the same gain of function activity, suggesting that augmented hemichannel activity could play a role in skin-limited diseases caused by human Cx43 mutations.
Collapse
|
33
|
Varadaraj K, Kumari SS. Molecular mechanism of Aquaporin 0-induced fiber cell to fiber cell adhesion in the eye lens. Biochem Biophys Res Commun 2018; 506:284-289. [PMID: 30348525 DOI: 10.1016/j.bbrc.2018.10.066] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 10/10/2018] [Indexed: 01/16/2023]
Abstract
Cell-to-cell adhesion (CTCA), which is key for establishing lens transparency, is a critical function of Aquaporin 0 (AQP0). The aim of this investigation was to find out the possible mechanism by which AQP0 exerts CTCA between fiber cells, since there are two proposals currently, either an AQP0-AQP0 interaction or an AQP0-lipid interaction. We studied the mechanism of AQP0-induced CTCA in intact AQP0 and C-terminally cleaved AQP0 (CTC-AQP0). Assays showed CTCA between L-cells transfected with intact AQP0 or CTC-AQP0 and parental L-cells indicating AQP0-membrane interaction. Both forms of AQP0 significantly (P < 0.001) promoted adhesion to negatively charged l-α-phosphatidylserine lipid vesicles signifying AQP0-lipid interaction. AQP0-expressing L-cells also promoted adhesion of WT and AQP0-KO mouse lens fiber cell membrane vesicles (FCMVs) significantly (P < 0.001). However, when FCMVs of WT or AQP0-KO were plated over parental L-cells, only WT vesicles adhered significantly, corroborating AQP0-membrane interaction. After incubating with extracellular domain-specific AQP0 antibody, L-cells expressing intact AQP0 or CTC-AQP0 showed a significant reduction (P < 0.001) in the adhesion of AQP0-KO FCMVs indicating extracellular loop involvement in CTCA. WT FCMVs from outer cortex and inner cortex promoted adhesion to parental L-cells, without any statistically significant difference in adhesion efficiency (P > 0.05). Ultrastructure studies of WT, AQP0-KO and transgenic lenses showed AQP0 is critical for fiber CTCA and compaction. The data collected clearly demonstrate that the positively charged amino acids in the AQP0 extracellular loop domains interact with the negatively charged lipids in the plasma membrane to promote CTCA for compaction of fiber cells.
Collapse
Affiliation(s)
- Kulandaiappan Varadaraj
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA; SUNY Eye Institute, New York, NY, USA.
| | - S Sindhu Kumari
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, USA
| |
Collapse
|
34
|
Zhang L, Liang Y, Zhou Y, Zeng H, Jia S, Shi J. A Missense Mutation in GJA8 Encoding Connexin 50 in a Chinese Pedigree with Autosomal Dominant Congenital Cataract. TOHOKU J EXP MED 2018; 244:105-111. [PMID: 29434075 DOI: 10.1620/tjem.244.105] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Congenital cataract is leading cause of visual impairment and blindness in children worldwide. Approximately one-third of congenital cataract cases are familial, whose genetic etiology can be distinguished by targeted exome sequencing. Here, a three-generation congenital cataract pedigree was recruited, and physical and ophthalmologic examinations were taken. Targeted exome sequencing of 139 cataract-related genes was performed on the proband III:1. Sanger sequencing was used to validate the presence of variation identified via exome sequencing in family members and 200 controls. Conservative and functional prediction was performed with bioinformatic tools. We, thus, found a heterozygous missense mutation c.10T>A (p.W4R) in gap junction protein alpha 8 (GJA8) in the patients. However, this mutation was not present in normal family members and 200 unrelated controls. The GJA8 gene encodes a gap junction protein, connexin 50 (Cx50), in lens fibers that provide channels for exchange of ions and small molecules between adjacent cells. Conservative and functional prediction suggests that the W-to-R substitution at codon 4 may impair the function of the human Cx50 protein. Accordingly, we analyzed the distribution of Flag-tagged mutant Cx50 protein in HeLa cervical cancer cells. Immunofluorescent staining showed that the W-to-R substitution impaired Cx50 trafficking to the plasma membrane to form the gap junction. In conclusion, c.10T>A (p.W4R) in GJA8 is the newly identified genetic cause of familial congenital cataract. The W-to-R substitution near the amino-terminus may alter the localization of mutant Cx50, thereby impairing gap junction formation, which is the molecular pathogenic mechanism of this mutation.
Collapse
Affiliation(s)
- Lusi Zhang
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| | - Youling Liang
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| | - Yedi Zhou
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| | - Huilan Zeng
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| | - Songbai Jia
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| | - Jingming Shi
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University.,Hunan Clinical Research Center of Ophthalmic Disease
| |
Collapse
|
35
|
Berry V, Ionides ACW, Pontikos N, Moghul I, Moore AT, Cheetham ME, Michaelides M. Whole-genome sequencing reveals a recurrent missense mutation in the Connexin 46 (GJA3) gene causing autosomal-dominant lamellar cataract. Eye (Lond) 2018; 32:1661-1668. [PMID: 29934635 PMCID: PMC6189195 DOI: 10.1038/s41433-018-0154-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 04/24/2018] [Accepted: 05/03/2018] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Congenital cataract, opacification of the ocular lens, is clinically and genetically a heterogeneous childhood disease. In this study we aimed to identify the underlying genetic cause of isolated autosomal-dominant lamellar cataract in a multi-generation English family. METHODS Whole-genome sequencing (WGS) was undertaken in two affected subjects and one unaffected individual. Segregation analysis was performed and a known cataract-causing mutation was identified. Segregation was further validated by sanger sequencing in the entire pedigree. RESULTS A heterozygous mutation c.7 G > T; p.D3Y was identified in an NH2-terminal region of the gap junction protein GJA3 and found to co-segregate with disease. CONCLUSION We have identified a recurrent mutation in GJA3 in a large British pedigree causing the novel phenotype of autosomal-dominant congenital lamellar cataract. Previously, p.D3Y was found in a Hispanic family causing pulverulent cataract. WGS proved an efficient method to find the underlying molecular cause in this large family, which could not be mapped due to uninformative markers.
Collapse
Affiliation(s)
- Vanita Berry
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | | | - Nikolas Pontikos
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
- UCL Genetics Institute, University College London, London, WC1E 6BT, UK
| | - Ismail Moghul
- UCL Cancer Institute, University College London, London, WC1E 6DD, UK
| | - Anthony T Moore
- Moorfields Eye Hospital, London, EC1V 2PD, UK
- Ophthalmology Department, University of California School of Medicine, San Francisco, CA, 94158, USA
| | | | - Michel Michaelides
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
- Moorfields Eye Hospital, London, EC1V 2PD, UK.
| |
Collapse
|
36
|
Gao J, Minogue PJ, Beyer EC, Mathias RT, Berthoud VM. Disruption of the lens circulation causes calcium accumulation and precipitates in connexin mutant mice. Am J Physiol Cell Physiol 2018; 314:C492-C503. [PMID: 29351411 PMCID: PMC5966789 DOI: 10.1152/ajpcell.00277.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/26/2017] [Accepted: 12/27/2017] [Indexed: 01/01/2023]
Abstract
The lens is an avascular organ whose function and survival depend on an internal circulation system. Cx46fs380 mice model a human autosomal dominant cataract caused by a mutant lens connexin. In these mice, fiber cell connexin levels and gap junction coupling are severely decreased. The present studies were conducted to examine components of the lens circulation system that might be altered and contribute to the pathogenesis of cataracts. Lenses from wild-type mice and Cx46fs380 heterozygotes and homozygotes were studied at 2 months of age. Cx46fs380-expressing lens fiber cells were depolarized. Cx46fs380 lenses had increased intracellular hydrostatic pressure and concentrations of Na+ and Ca2+. The activity of epithelial Na+-K+-ATPase was decreased in Cx46fs380 lenses. All of these changes were more severe in homozygous than in heterozygous Cx46fs380 lenses. Cx46fs380 cataracts were stained by Alizarin red, a dye used to detect insoluble Ca2+. These data suggest that the lens internal circulation was disrupted by expression of Cx46fs380, leading to several consequences including accumulation of Ca2+ to levels so high that precipitates formed. Similar Ca2+-containing precipitates may contribute to cataract formation due to other genetic or acquired etiologies.
Collapse
Affiliation(s)
- Junyuan Gao
- Department of Physiology and Biophysics, Stony Brook University , Stony Brook, New York
| | - Peter J Minogue
- Department of Pediatrics, University of Chicago , Chicago, Illinois
| | - Eric C Beyer
- Department of Pediatrics, University of Chicago , Chicago, Illinois
| | - Richard T Mathias
- Department of Physiology and Biophysics, Stony Brook University , Stony Brook, New York
| | | |
Collapse
|
37
|
Cui X, Zhou Z, Zhu K, Feng R, Han J, Li M, Wang S, Li J, Zhang J, Jiang Q, Zhang W, Mu H, Liu Y, Hu Y. A Novel Cx50 Insert Mutation from a Chinese Congenital Cataract Family Impairs Its Cellular Membrane Localization and Function. DNA Cell Biol 2018; 37:449-456. [PMID: 29489419 DOI: 10.1089/dna.2017.4051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mutations in GJA8 are associated with hereditary autosomal dominant and recessive cataract formation. In this study, a novel insert mutation in GJA8 was identified in a Chinese congenital cataract family and cosegregated with the disease in this pedigree. This insert mutation introduces five additional amino acid residues YAVHY after histidine at the 95 site (p.H95_A96insYAVHY) within the second transmembrane (TM2) domain of Cx50 protein (Cx50-insert). Ectopic expression of Cx50-insert protein impairs the hemichannel functions and gap junction activity compared to wild-type Cx50 protein in human lens epithelial cells. Cx50-insert proteins were mislocated from cytoplasmic membrane to endoplasmic reticulum and lysosome. In mouse lens tissue, our results showed that Cx50 predominant expresses in epithelial cells and fiber cells at the transition zone of lens hinting its roles in lens differentiation. Taken together, these data suggest that the novel insert mutation in the TM2 domain of Cx50 protein, which impairs its trafficking to the cell membrane and gap-junction function, is associated with the cataract formation in this Chinese pedigree.
Collapse
Affiliation(s)
- Xiukun Cui
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Zheng Zhou
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Keke Zhu
- 2 Kaifeng Key Lab of Cataract and Myopia, Institute of Eye Diseases , Kaifeng Centre Hospital, Kaifeng, China
| | - Ruiping Feng
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Jiuli Han
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Mengyuan Li
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Shuangfeng Wang
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Jing Li
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Jing Zhang
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Qiying Jiang
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China
| | - Wanting Zhang
- 2 Kaifeng Key Lab of Cataract and Myopia, Institute of Eye Diseases , Kaifeng Centre Hospital, Kaifeng, China
| | - Hongmei Mu
- 2 Kaifeng Key Lab of Cataract and Myopia, Institute of Eye Diseases , Kaifeng Centre Hospital, Kaifeng, China
| | - Yutao Liu
- 3 Department of Cell Biology and Anatomy, Augusta University , Augusta, Georgia
| | - Yanzhong Hu
- 1 Joint National Laboratory for Antibody Drug Engineering, Henan International Union Laboratory of Antibody Medicine, Department of Cell Biology and Genetics, Henan University School of Medicine , Kaifeng, China .,2 Kaifeng Key Lab of Cataract and Myopia, Institute of Eye Diseases , Kaifeng Centre Hospital, Kaifeng, China
| |
Collapse
|
38
|
Ceroni F, Aguilera-Garcia D, Chassaing N, Bax DA, Blanco-Kelly F, Ramos P, Tarilonte M, Villaverde C, da Silva LRJ, Ballesta-Martínez MJ, Sanchez-Soler MJ, Holt RJ, Cooper-Charles L, Bruty J, Wallis Y, McMullan D, Hoffman J, Bunyan D, Stewart A, Stewart H, Lachlan K, Fryer A, McKay V, Roume J, Dureau P, Saggar A, Griffiths M, Calvas P, Ayuso C, Corton M, Ragge NK. New GJA8 variants and phenotypes highlight its critical role in a broad spectrum of eye anomalies. Hum Genet 2018; 138:1027-1042. [PMID: 29464339 DOI: 10.1007/s00439-018-1875-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 02/09/2018] [Indexed: 12/23/2022]
Abstract
GJA8 encodes connexin 50 (Cx50), a transmembrane protein involved in the formation of lens gap junctions. GJA8 mutations have been linked to early onset cataracts in humans and animal models. In mice, missense mutations and homozygous Gja8 deletions lead to smaller lenses and microphthalmia in addition to cataract, suggesting that Gja8 may play a role in both lens development and ocular growth. Following screening of GJA8 in a cohort of 426 individuals with severe congenital eye anomalies, primarily anophthalmia, microphthalmia and coloboma, we identified four known [p.(Thr39Arg), p.(Trp45Leu), p.(Asp51Asn), and p.(Gly94Arg)] and two novel [p.(Phe70Leu) and p.(Val97Gly)] likely pathogenic variants in seven families. Five of these co-segregated with cataracts and microphthalmia, whereas the variant p.(Gly94Arg) was identified in an individual with congenital aphakia, sclerocornea, microphthalmia and coloboma. Four missense variants of unknown or unlikely clinical significance were also identified. Furthermore, the screening of GJA8 structural variants in a subgroup of 188 individuals identified heterozygous 1q21 microdeletions in five families with coloboma and other ocular and/or extraocular findings. However, the exact genotype-phenotype correlation of these structural variants remains to be established. Our data expand the spectrum of GJA8 variants and associated phenotypes, confirming the importance of this gene in early eye development.
Collapse
Affiliation(s)
- Fabiola Ceroni
- Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Domingo Aguilera-Garcia
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Nicolas Chassaing
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France
- UMR 1056 Inserm, Université de Toulouse, Toulouse, France
| | - Dorine Arjanne Bax
- Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Fiona Blanco-Kelly
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
- Institute of Ophthalmology, University College London, London, UK
| | - Patricia Ramos
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Maria Tarilonte
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Cristina Villaverde
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Luciana Rodrigues Jacy da Silva
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | | | | | - Richard James Holt
- Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Lisa Cooper-Charles
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Jonathan Bruty
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Yvonne Wallis
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Dominic McMullan
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Jonathan Hoffman
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners, Birmingham Women's and Children's NHS Foundation Trust, Mindelsohn Way, Birmingham, B15 2TG, UK
| | - David Bunyan
- Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Alison Stewart
- Sheffield Clinical Genetics Department, Northern General Hospital, Sheffield, UK
| | - Helen Stewart
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Katherine Lachlan
- Wessex Clinical Genetics Service, Princess Anne Hospital, University Hospital Southampton NHS Foundation Trust, Southampton, UK
- Human Genetics and Genomic Medicine, Southampton General Hospital, University of Southampton, Southampton, UK
| | - Alan Fryer
- Cheshire and Merseyside Genetics Service, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Victoria McKay
- Cheshire and Merseyside Genetics Service, Liverpool Women's NHS Foundation Trust, Liverpool, UK
| | - Joëlle Roume
- Department of Clinical Genetics, Centre de Référence "AnDDI Rares", Poissy Hospital GHU PIFO, Poissy, France
| | - Pascal Dureau
- Fondation Ophtalmologique Adolphe-de-Rothschild, Paris, France
| | - Anand Saggar
- Clinical Genetics Unit, St Georges University of London, London, UK
| | - Michael Griffiths
- West Midlands Regional Genetics Laboratory, Birmingham Women's and Children's NHS Foundation Trust, Birmingham, UK
| | - Patrick Calvas
- Service de Génétique Médicale, Hôpital Purpan, CHU Toulouse, Toulouse, France
- UMR 1056 Inserm, Université de Toulouse, Toulouse, France
| | - Carmen Ayuso
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Marta Corton
- Genetics Service, Instituto de Investigación Sanitaria-Fundación Jiménez Díaz University Hospital, Universidad Autónoma de Madrid (IIS-FJD, UAM), Madrid, Spain
- Centre for Biomedical Network Research on Rare Diseases (CIBERER), ISCIII, Madrid, Spain
| | - Nicola K Ragge
- Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
- West Midlands Regional Clinical Genetics Service and Birmingham Health Partners, Birmingham Women's and Children's NHS Foundation Trust, Mindelsohn Way, Birmingham, B15 2TG, UK.
| |
Collapse
|
39
|
Delineation of Novel Autosomal Recessive Mutation in GJA3 and Autosomal Dominant Mutations in GJA8 in Pakistani Congenital Cataract Families. Genes (Basel) 2018; 9:genes9020112. [PMID: 29461512 PMCID: PMC5852608 DOI: 10.3390/genes9020112] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 02/09/2018] [Accepted: 02/09/2018] [Indexed: 12/14/2022] Open
Abstract
Congenital cataract is a clinically and genetically heterogeneous disease. The present study was undertaken to find the genetic cause of congenital cataract families. DNA samples of a large consanguineous Pakistani family were genotyped with a high resolution single nucleotide polymorphism Illumina microarray. Homozygosity mapping identified a homozygous region of 4.4 Mb encompassing the gene GJA3. Sanger sequence analysis of the GJA3 gene revealed a novel homozygous variant c.950dup p.(His318ProfsX8) segregating in an autosomal recessive (AR) manner. The previously known mode of inheritance for GJA3 gene mutations in cataract was autosomal dominant (AD) only. The screening of additional probands (n = 41) of cataract families revealed a previously known mutation c.56C>T p.(Thr19Met) in GJA3 gene. In addition, sequencing of the exon-intron boundaries of the GJA8 gene in 41 cataract probands revealed two additional mutations: a novel c.53C>T p.(Ser18Phe) and a known c.175C>G p.(Pro59Ala) mutation, both co-segregating with the disease phenotype in an AD manner. All these mutations are predicted to be pathogenic by in silico analysis and were absent in the control databases. In conclusion, results of the current study enhance our understanding of the genetic basis of cataract, and identified the involvement of the GJA3 in the disease etiology in both AR and AD manners.
Collapse
|
40
|
Zhu X, Zhang S, Chang R, Lu Y. New cataract markers: Mechanisms of disease. Clin Chim Acta 2017; 472:41-45. [PMID: 28705775 DOI: 10.1016/j.cca.2017.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 07/08/2017] [Accepted: 07/09/2017] [Indexed: 11/28/2022]
Abstract
Cataract is caused by nutritional, metabolic, environmental, and genetic factors, and is a significant cause of blindness and visual impairment. In recent years, extensive research into the human genome has revealed that numerous genetic mutations are associated with cataract. These mutations affect a variety of genes, including those encoding crystallin, membrane proteins, cytoskeletal proteins, transcription factors, and metabolism-related proteins. Elucidation of these mutations and the genetic and molecular mechanisms has helped clarify the etiology of cataract and may facilitate its early diagnosis and treatment. This review summarizes recent advances in our knowledge and potential clinical of genetic markers of cataract.
Collapse
Affiliation(s)
- Xiangjia Zhu
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Shaohua Zhang
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Ruiqi Chang
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China
| | - Yi Lu
- Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Eye Institute, Eye and Ear, Nose, and Throat Hospital of Fudan University, 83 Fenyang Road, Shanghai 200031, People's Republic of China; Key Laboratory of Myopia, Ministry of Health, Shanghai 200031, People's Republic of China; Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai 200031, People's Republic of China.
| |
Collapse
|
41
|
Wang E, Geng A, Maniar AM, Mui BWH, Gong X. Connexin 50 Regulates Surface Ball-and-Socket Structures and Fiber Cell Organization. Invest Ophthalmol Vis Sci 2017; 57:3039-46. [PMID: 27281269 PMCID: PMC4913802 DOI: 10.1167/iovs.16-19521] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Purpose The roles of gap junction protein connexin 50 (Cx50) encoded by Gja8, during lens development are not fully understood. Connexin 50 knockout (KO) lenses have decreased proliferation of epithelial cells and altered fiber cell denucleation. We further investigated the mechanism for cellular defects in Cx50 KO (Gja8−/−) lenses. Methods Fiber cell morphology and subcellular distribution of various lens membrane/cytoskeleton proteins from wild-type and Cx50 KO mice were visualized by immunofluorescent staining and confocal microscopy. Results We observed multiple morphological defects in the cortical fibers of Cx50 KO lenses, including abnormal fiber cell packing geometry, decreased F-actin enrichment at tricellular vertices, and disrupted ball-and-socket (BS) structures on the long sides of hexagonal fibers. Moreover, only small gap junction plaques consisting of Cx46 (α3 connexin) were detected in cortical fibers and the distributions of the BS-associated beta-dystroglycan and ZO-1 proteins were altered. Conclusions Connexin 50 gap junctions are important for BS structure maturation and cortical fiber cell organization. Connexin 50–based gap junction plaques likely form structural domains with an array of membrane/cytoskeletal proteins to stabilize BS. Loss of Cx50-mediated coupling, BS disruption, and altered F-actin in Cx50 KO fibers, thereby contribute to the small lens and mild cataract phenotypes.
Collapse
|
42
|
Sellitto C, Li L, Vaghefi E, Donaldson PJ, Lin RZ, White TW. The Phosphoinosotide 3-Kinase Catalytic Subunit p110α is Required for Normal Lens Growth. Invest Ophthalmol Vis Sci 2017; 57:3145-51. [PMID: 27304846 PMCID: PMC4928694 DOI: 10.1167/iovs.16-19607] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purpose Signal transduction pathways influence lens growth, but little is known about the role(s) of the class 1A phosphoinositide 3-kinases (PI3Ks). To further investigate how signaling regulates lens growth, we generated and characterized mice in which the p110α and p110β catalytic subunits of PI3K were conditionally deleted in the mouse lens. Methods Floxed alleles of the catalytic subunits of PI3K were conditionally deleted in the lens by using MLR10-cre transgenic mice. Lenses of age-matched animals were dissected and photographed. Postnatal lenses were fixed, paraffin embedded, sectioned, and stained with hematoxylin-eosin. Cell proliferation was quantified by labeling S-phase cells in intact lenses with 5-ethynyl-2′-deoxyuridine. Protein kinase B (AKT) activation was examined by Western blotting. Results Lens-specific deletion of p110α resulted in a significant reduction of eye and lens size, without compromising lens clarity. Conditional knockout of p110β had no effect on lens size or clarity, and deletion of both the p110α and p110β subunits resulted in a phenotype that resembled the p110α single-knockout phenotype. Levels of activated AKT were decreased more in p110α- than in p110β-deficient lenses. A significant reduction in proliferating cells in the germinative zone was observed on postnatal day 0 in p110α knockout mice, which was temporally correlated with decreased lens volume. Conclusions These data suggest that the class 1A PI3K signaling pathway plays an important role in the regulation of lens size by influencing the extent and spatial location of cell proliferation in the perinatal period.
Collapse
Affiliation(s)
- Caterina Sellitto
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
| | - Leping Li
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
| | - Ehsan Vaghefi
- School of Optometry and Vision Science, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, University of Auckland, Auckland, New Zealand
| | - Richard Z Lin
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States 4Medical Service, Department of Veterans Affairs Medical Center, Northport, New York, United States
| | - Thomas W White
- Department of Physiology and Biophysics Stony Brook University, Stony Brook, New York, United States
| |
Collapse
|
43
|
Mathews J, Levin M. Gap junctional signaling in pattern regulation: Physiological network connectivity instructs growth and form. Dev Neurobiol 2017; 77:643-673. [PMID: 27265625 PMCID: PMC10478170 DOI: 10.1002/dneu.22405] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022]
Abstract
Gap junctions (GJs) are aqueous channels that allow cells to communicate via physiological signals directly. The role of gap junctional connectivity in determining single-cell functions has long been recognized. However, GJs have another important role: the regulation of large-scale anatomical pattern. GJs are not only versatile computational elements that allow cells to control which small molecule signals they receive and emit, but also establish connectivity patterns within large groups of cells. By dynamically regulating the topology of bioelectric networks in vivo, GJs underlie the ability of many tissues to implement complex morphogenesis. Here, a review of recent data on patterning roles of GJs in growth of the zebrafish fin, the establishment of left-right patterning, the developmental dysregulation known as cancer, and the control of large-scale head-tail polarity, and head shape in planarian regeneration has been reported. A perspective in which GJs are not only molecular features functioning in single cells, but also enable global neural-like dynamics in non-neural somatic tissues has been proposed. This view suggests a rich program of future work which capitalizes on the rapid advances in the biophysics of GJs to exploit GJ-mediated global dynamics for applications in birth defects, regenerative medicine, and morphogenetic bioengineering. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 643-673, 2017.
Collapse
Affiliation(s)
- Juanita Mathews
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
| | - Michael Levin
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
| |
Collapse
|
44
|
Srinivas M, Verselis VK, White TW. Human diseases associated with connexin mutations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:192-201. [PMID: 28457858 DOI: 10.1016/j.bbamem.2017.04.024] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/20/2017] [Accepted: 04/25/2017] [Indexed: 01/11/2023]
Abstract
Gap junctions and hemichannels comprised of connexins impact many cellular processes. Significant advances in our understanding of the functional role of these channels have been made by the identification of a host of genetic diseases caused by connexin mutations. Prominent features of connexin disorders are the inability of other connexins expressed in the same cell type to compensate for the mutated one, and the ability of connexin mutants to dominantly influence the activity of other wild-type connexins. Functional studies have begun to identify some of the underlying mechanisms whereby connexin channel mutation contributes to the disease state. Detailed mechanistic understanding of these functional differences will help to facilitate new pathophysiology driven therapies for the diverse array of connexin genetic disorders. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
Collapse
Affiliation(s)
- Miduturu Srinivas
- Department of Biological and Vision Sciences, SUNY College of Optometry, New York, NY 10036, USA
| | - Vytas K Verselis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Thomas W White
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA.
| |
Collapse
|
45
|
Bassnett S, Šikić H. The lens growth process. Prog Retin Eye Res 2017; 60:181-200. [PMID: 28411123 DOI: 10.1016/j.preteyeres.2017.04.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/17/2023]
Abstract
The factors that regulate the size of organs to ensure that they fit within an organism are not well understood. A simple organ, the ocular lens serves as a useful model with which to tackle this problem. In many systems, considerable variance in the organ growth process is tolerable. This is almost certainly not the case in the lens, which in addition to fitting comfortably within the eyeball, must also be of the correct size and shape to focus light sharply onto the retina. Furthermore, the lens does not perform its optical function in isolation. Its growth, which continues throughout life, must therefore be coordinated with that of other tissues in the optical train. Here, we review the lens growth process in detail, from pioneering clinical investigations in the late nineteenth century to insights gleaned more recently in the course of cell and molecular studies. During embryonic development, the lens forms from an invagination of surface ectoderm. Consequently, the progenitor cell population is located at its surface and differentiated cells are confined to the interior. The interactions that regulate cell fate thus occur within the obligate ellipsoidal geometry of the lens. In this context, mathematical models are particularly appropriate tools with which to examine the growth process. In addition to identifying key growth determinants, such models constitute a framework for integrating cell biological and optical data, helping clarify the relationship between gene expression in the lens and image quality at the retinal plane.
Collapse
Affiliation(s)
- Steven Bassnett
- Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, USA.
| | - Hrvoje Šikić
- Department of Mathematics, Faculty of Science, University of Zagreb, Croatia
| |
Collapse
|
46
|
Abstract
The lens is an avascular organ composed of an anterior epithelial cell layer and fiber cells that form the bulk of the organ. The lens expresses connexin43 (Cx43), connexin46 (Cx46) and connexin50 (Cx50). Epithelial Cx50 has critical roles in cell proliferation and differentiation, likely involving growth factor-dependent signaling pathways. Both Cx46 and Cx50 are crucial for lens transparency; mutations in their genes have been linked to congenital and age-related cataracts. Congenital cataract-associated connexin mutants can affect protein trafficking, stability and/or function, and the functional effects may differ between gap junction channels and hemichannels. Dominantly inherited cataracts may result from effects of the connexin mutant on its wild type isotype, the other co-expressed wild type connexin and/or its interaction with other cellular components.
Collapse
Affiliation(s)
| | - Anaclet Ngezahayo
- Institute of Biophysics, Leibniz University Hannover, Hannover, Germany.
| |
Collapse
|
47
|
Ren M, Yang XG, Dang XJ, Xiao JA. Exome sequencing identifies a novel mutation in GJA8 associated with inherited cataract in a Chinese family. Graefes Arch Clin Exp Ophthalmol 2016; 255:141-151. [DOI: 10.1007/s00417-016-3513-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/30/2016] [Accepted: 10/03/2016] [Indexed: 12/14/2022] Open
|
48
|
Identification and functional analysis of two novel connexin 50 mutations associated with autosome dominant congenital cataracts. Sci Rep 2016; 6:26551. [PMID: 27216975 PMCID: PMC4877569 DOI: 10.1038/srep26551] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/03/2016] [Indexed: 01/14/2023] Open
Abstract
Autosomal dominant congenital cataracts (ADCC) are clinically and genetically heterogeneous diseases. The present study recruited two Chinese families with bilateral nuclear cataract or zonular pulverulent phenotype. Direct sequencing of candidate genes identified two novel missense mutations of Cx50, Cx50P59A (c.175C > G) and Cx50R76H (c.227G > A), both co-segregated well with all affected individuals. Bioinformatics analysis predicted deleterious for both mutations. Functional and cellular behaviors of wild type and mutant Cx50 examined by stably transfecting recombinant systems revealed similar protein expression levels. Protein distribution pattern by fluorescence microscopy showed that Cx50R76H localized at appositional membranes forming gap junctions with enormous cytoplasmic protein accumulation, whereas the Cx50P59A mutation was found inefficient at forming detectable plaques. Cell growth test by MTT assay showed that induction of Cx50P59A decreased cell viability. Our study constitutes the first report that the Cx50P59A and Cx50R76H mutations are associated with ADCC and expands the mutation spectrum of Cx50 in association with congenital cataracts. The genetic, cellular, and functional data suggest that the altered intercellular communication governed by mutated Cx50 proteins may act as the molecular mechanism underlying ADCC, which further confirms the role of Cx50 in the maintenance of human lens transparency.
Collapse
|
49
|
Li B, Liu Y, Liu Y, Guo H, Hu Z, Xia K, Jin X. Identification of a GJA3 Mutation in a Large Family with Bilateral Congenital Cataract. DNA Cell Biol 2016; 35:135-9. [PMID: 26683566 DOI: 10.1089/dna.2015.3125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The congenital cataract has been a clinically important cause of impaired vision development, making up about 10% of the cases of childhood blindness. Mutations of more than 40 genes have been identified causing congenital cataract with Mendelian inheritance, which indicated that it has an extremely high genetic heterogeneity. In this study, we recruited a large congenital cataract family and identified a missense mutation (c.143A>G: p.E48G) within gap junction protein alpha-3 (GJA3) gene in the proband using whole exome sequencing. Subsequent Sanger sequencing of this mutation in all family members revealed that this mutation cosegregated with the phenotype in the family with full penetrance. Our study identified a mutation in GJA3 that correlated with congenital cataract phenotype, which was not reported previously, and would be of benefit to the diagnosis of this genetic disorder. This finding expands the mutation spectrum of GJA3 and provides useful information for further study of the molecular pathogenesis of congenital cataract.
Collapse
Affiliation(s)
- Bin Li
- 1 State Key Laboratory of Medical Genetics, School of Life Sciences, Central South University , Changsha, China
| | - Yuying Liu
- 2 The First Affiliated Hospital of Zhengzhou University , Zhengzhou, China
| | - Yaning Liu
- 1 State Key Laboratory of Medical Genetics, School of Life Sciences, Central South University , Changsha, China
| | - Hui Guo
- 1 State Key Laboratory of Medical Genetics, School of Life Sciences, Central South University , Changsha, China
| | - Zhengmao Hu
- 1 State Key Laboratory of Medical Genetics, School of Life Sciences, Central South University , Changsha, China
| | - Kun Xia
- 1 State Key Laboratory of Medical Genetics, School of Life Sciences, Central South University , Changsha, China
- 3 College of Life Science and Technology, Xinjiang University , Urumqi, China
- 4 Key Laboratory of Medical Information Research, Central South University , Changsha, China
| | - Xuemin Jin
- 2 The First Affiliated Hospital of Zhengzhou University , Zhengzhou, China
| |
Collapse
|
50
|
Andley UP, Goldman JW. Autophagy and UPR in alpha-crystallin mutant knock-in mouse models of hereditary cataracts. Biochim Biophys Acta Gen Subj 2015; 1860:234-9. [PMID: 26071686 DOI: 10.1016/j.bbagen.2015.06.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 06/03/2015] [Accepted: 06/04/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Knock-in mice provide useful models of congenital and age-related cataracts caused by α-crystallin mutations. R49C αA-crystallin and R120G αB-crystallin mutations are linked with hereditary cataracts. Knock-in αA-R49C+/- heterozygotes develop cataracts by 1-2months, whereas homozygote mice have cataracts at birth. The R49C mutation drastically reduces lens protein water solubility and causes cell death in knock-in mouse lenses. Mutant crystallin cannot function as a chaperone, which leads to protein aggregation and lens opacity. Protein aggregation disrupts the lens fiber cell structure and normal development and causes cell death in epithelial and fiber cells. We determined what aspects of the wild-type phenotype are age-dependently altered in the mutant lens. METHODS Wild-type, heterozygote (αA-R49C+/-), and homozygote (αA-R49C+/+) mouse lenses were assessed pre- and postnatally for lens morphology (electron microscopy, immunohistochemistry), and autophagy or unfolded protein response markers (immunoblotting). RESULTS Morphology was altered by embryonic day 17 in R49C+/+ lenses; R49C+/- lens morphology was unaffected at this stage. Active autophagy in the lens epithelium of mutant lenses was indicated by the presence of autophagosomes using electron microscopy. Protein p62 levels, which are degraded specifically by autophagy, increased in αA-R49C mutant versus wild-type lenses, suggesting autophagy inhibition in the mutant lenses. The unfolded protein response marker XBP-1 was upregulated in adult lenses of αB-R120G+/+ mice, suggesting its role in lens opacification. CONCLUSIONS Mutated crystallins alter lens morphology, autophagy, and stress responses. GENERAL SIGNIFICANCE Therapeutic modulation of autophagic pathways may improve protein degradation in cataractous lenses and reduce lens opacity. This article is part of a Special Issue entitled Crystallin Biochemistry in Health and Disease.
Collapse
Affiliation(s)
- Usha P Andley
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Joshua W Goldman
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| |
Collapse
|