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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.
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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.
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Sun Y, Wang X, Chen B, Huang M, Ma P, Xiong L, Huang J, Chen J, Huang S, Liu Y. TFEB-Mediated Lysosomal Restoration Alleviates High Glucose-Induced Cataracts Via Attenuating Oxidative Stress. Invest Ophthalmol Vis Sci 2022; 63:26. [PMID: 35758908 PMCID: PMC9248753 DOI: 10.1167/iovs.63.6.26] [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] [Indexed: 11/24/2022] Open
Abstract
Purpose Diabetic cataract (DC) is a visual disorder arising from diabetes mellitus (DM). Autophagy, a prosurvival intracellular process through lysosomal fusion and degradation, has been implicated in multiple diabetic complications. Herein, we performed in vivo and in vitro assays to explore the specific roles of the autophagy-lysosome pathway in DC. Methods Streptozotocin-induced DM and incubation in high glucose (HG) led to rat lens opacification. Protein Simple Wes, Western blot, and immunoassay were utilized to investigate autophagic changes in lens epithelial cells (LECs) and lens fiber cells (LFCs). RNA-sequencing (RNA-seq) was performed to explore genetic changes in the lenses of diabetic rats. Moreover, autophagy-lysosomal functions were examined using lysotracker, Western blot, and immunofluorescence analyses in HG-cultured primary rabbit LECs. Results First, DM and HG culture led to fibrotic LECs, swelling LFCs, and eventually cataracts. Further analysis showed aberrant autophagic degradation in LECs and LFCs during cataract formation. RNA-seq data revealed that the differentially expressed genes (DEGs) were enriched in the lysosome pathway. In primary LECs, HG treatment resulted in decreased transcription factor EB (TFEB) and cathepsin B (CTSB) activity, and increased lysosomal size and pH values. Moreover, TFEB-mediated dysfunctional lysosomes resulted from excessive oxidative stress in LECs under HG conditions. Furthermore, TFEB activation by curcumin analog C1 alleviated HG-induced cataracts through enhancing lysosome biogenesis and activating protective autophagy, thereby attenuating HG-mediated oxidative damage. Conclusions In summary, we first identified that ROS-TFEB-dependent lysosomal dysfunction contributed to autophagy blockage in HG-induced cataracts. Additionally, TFEB-mediated lysosomal restoration might be a promising therapeutic method for preventing and treating DC through mitigating oxidative stress.
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Affiliation(s)
- Yan Sun
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Xiaoran Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Baoxin Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Mi Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Pengjuan Ma
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Lang Xiong
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Jingqi Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Jieping Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Shan Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
| | - Yizhi Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangzhou, China
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Jin A, Zhao Q, Liu S, Jin ZB, Li S, Xiang M, Zeng M, Jin K. Identification of a New Mutation p.P88L in Connexin 50 Associated with Dominant Congenital Cataract. Front Cell Dev Biol 2022; 10:794837. [PMID: 35531093 PMCID: PMC9068895 DOI: 10.3389/fcell.2022.794837] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 03/29/2022] [Indexed: 11/13/2022] Open
Abstract
Congenital hereditary cataract is genetically heterogeneous and the leading cause of visual impairment in children. Identification of hereditary causes is critical to genetic counselling and family planning. Here, we examined a four-generation Chinese pedigree with congenital dominant cataract and identified a new mutation in GJA8 via targeted exome sequencing. A heterozygous missense mutation c.263C > T, leading to a proline-to-Leucine conversion at the conserved residue 88 in the second transmembrane domain of human connexin 50 (Cx50), was identified in all patients but not in unaffected family members. Functional analyses of the mutation revealed that it disrupted the stability of Cx50 and had a deleterious effect on protein function. Indeed, the mutation compromised normal membrane permeability and gating of ions, and impeded cell migration when overexpressed. Together, our results expand the pathogenic mutation spectrum of Cx50 underlying congenital cataract and lend more support to clinical diagnosis and genetic counseling.
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Affiliation(s)
- Aixia Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Qingqing Zhao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Shuting Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
| | - Zi-bing Jin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Laboratory, Beijing, China
| | - Shuyan Li
- Department of Biochemistry and Biophysics, Peking University Health Science Center, Beijing, China
| | - Mengqing Xiang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
- *Correspondence: Kangxin Jin, ; Mengqing Xiang, ; Mingbing Zeng,
| | - Mingbing Zeng
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
- Hainan Eye Hospital, Hainan Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Haikou, China
- *Correspondence: Kangxin Jin, ; Mengqing Xiang, ; Mingbing Zeng,
| | - Kangxin Jin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-Sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, China
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology and Visual Science Key Laboratory, Beijing, China
- *Correspondence: Kangxin Jin, ; Mengqing Xiang, ; Mingbing Zeng,
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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.
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Thompson B, Chen Y, Davidson EA, Garcia-Milian R, Golla JP, Apostolopoulos N, Orlicky DJ, Schey K, Thompson DC, Vasiliou V. Impaired GSH biosynthesis disrupts eye development, lens morphogenesis and PAX6 function. Ocul Surf 2021; 22:190-203. [PMID: 34425299 DOI: 10.1016/j.jtos.2021.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/29/2021] [Accepted: 08/16/2021] [Indexed: 12/14/2022]
Abstract
PURPOSE The purpose of this study was to elucidate the role and molecular consequences of impaired glutathione (GSH) biosynthesis on eye development. METHODS GSH biosynthesis was impaired in surface ectoderm-derived ocular tissues by crossing Gclcf/f mice with hemizygous Le-Cre transgenic mice to produce Gclcf/f/Le-CreTg/- (KO) mice. Control mice included Gclcf/fand Gclcwt/wt/Le-CreTg/- mice (CRE). Eyes from all mice (at various stages of eye development) were subjected to histological, immunohistochemical, Western blot, RT-qPCR, RNA-seq, and subsequent Gene Ontology, Ingenuity Pathway Analysis and TRANSFAC analyses. PAX6 transactivation activity was studied using a luciferase reporter assay in HEK293T cells depleted of GSH using buthionine sulfoximine (BSO). RESULTS Deletion of Gclc diminished GSH levels, increased reactive oxygen species (ROS), and caused an overt microphthalmia phenotype characterized by malformation of the cornea, iris, lens, and retina that is distinct from and much more profound than the one observed in CRE mice. In addition, only the lenses of KO mice displayed reduced crystallin (α, β), PITX3 and Foxe3 expression. RNA-seq analyses at postnatal day 1 revealed 1552 differentially expressed genes (DEGs) in the lenses of KO mice relative to those from Gclcf/f mice, with Crystallin and lens fiber cell identity genes being downregulated while lens epithelial cell identity and immune response genes were upregulated. Bioinformatic analysis of the DEGs implicated PAX6 as a key upstream regulator. PAX6 transactivation activity was impaired in BSO-treated HEK293T cells. CONCLUSIONS These data suggest that impaired ocular GSH biosynthesis may disrupt eye development and PAX6 function.
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Affiliation(s)
- Brian Thompson
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, 60 College Street, New Haven, CT, USA
| | - Ying Chen
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, 60 College Street, New Haven, CT, USA
| | - Emily A Davidson
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, 60 College Street, New Haven, CT, USA; Department of Cellular & Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT, USA
| | - Rolando Garcia-Milian
- Bioinformatics Support Program, Cushing/Whitney Medical Library, Yale School of Medicine, New Haven, CT, USA
| | - Jaya Prakash Golla
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, 60 College Street, New Haven, CT, USA; Department of Medicine, Yale University School of Medicine, New Haven, CT, USA; Veterans Affairs Connecticut Healthcare System, West Haven, CT, USA
| | | | - David J Orlicky
- Department of Pathology, Anschutz School of Medicine, University of Colorado, Aurora, CO, USA
| | - Kevin Schey
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - David C Thompson
- Department of Clinical Pharmacy, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver, Aurora, CO, USA
| | - Vasilis Vasiliou
- Department of Environmental Health Sciences, Yale School of Public Health, Yale University, 60 College Street, New Haven, CT, USA.
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