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Zhou B, Lin X, Li Z, Yao Y, Yang J, Zhu Y. Structure‒function‒pathogenicity analysis of C-terminal myocilin missense variants based on experiments and 3D models. Front Genet 2022; 13:1019208. [PMID: 36267417 PMCID: PMC9577182 DOI: 10.3389/fgene.2022.1019208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/16/2022] [Indexed: 11/13/2022] Open
Abstract
MYOC is a common pathogenic gene for primary open-angle glaucoma and encodes the protein named myocilin. Multiple MYOC variations have been found, with different clinical significance. However, the pathogenesis of glaucoma induced by MYOC mutations has not been fully clarified. Here, we analyze the molecular and cellular biological differences caused by multiple variant myocilins, including protein secretion characteristics, structural changes, subcellular localization, cellular autophagic activity and oxidative stress. Denaturing and nondenaturing electrophoresis showed myocilin to be a secreted protein with the tendency to self-oligomerize. The full-length myocilin and its C-terminal cleavage fragment are secreted. Secretion analysis of 23 variant myocilins indicated that secretion defects are closely related to the pathogenicity of MYOC variants. Structural analysis showed that the alteration of steric clash is associated with the secretion characteristics and pathogenicity of myocilin variants. Immunocytochemistry results demonstrated that mutated myocilins are retained in the endoplasmic reticulum and disrupt autophagy. MTT assay, MitoTracker staining, and DCFH-DA staining showed increased oxidative injury in cells expressing MYOC mutants. Taken together, MYOC mutations are able to induce cell dysfunction via secretion defects and intracellular accumulation resulting from steric clash alterations.
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Affiliation(s)
- Biting Zhou
- Department of Ophthalmology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xiaojia Lin
- Department of Ophthalmology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Zhong Li
- Department of Bioengineering and Biopharmaceutics, School of Pharmacy, Fujian Medical University, Fuzhou, China
| | - Yihua Yao
- Department of Ophthalmology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Juhua Yang
- Department of Bioengineering and Biopharmaceutics, School of Pharmacy, Fujian Medical University, Fuzhou, China
- *Correspondence: Yihua Zhu, ; Juhua Yang,
| | - Yihua Zhu
- Department of Ophthalmology, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
- *Correspondence: Yihua Zhu, ; Juhua Yang,
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Pumphrey SA, Zitek-Morrison E, Pizzirani S, Meola DM. Evaluation of matrix metalloproteinases and tissue inhibitors of metalloproteinases in aqueous humor of dogs with versus without naturally occurring primary angle-closure glaucoma. Am J Vet Res 2021; 83:245-255. [PMID: 34936570 DOI: 10.2460/ajvr.21.04.0062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in aqueous humor from ophthalmologically normal dogs and dogs with naturally occurring primary angle-closure glaucoma (cPACG). SAMPLE Aqueous humor samples from 12 eyes with cPACG and 18 ophthalmologically normal eyes of dogs. PROCEDURES A multiplex fluorescence-based ELISA was used to measure concentrations of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-13, TIMP-1, TIMP-2, and TIMP-4. Results for eyes with versus without cPACG were compared. RESULTS Significantly higher mean concentrations of MMP-1 (45% higher), MMP-2 (55% higher), MMP-3 (39% higher), MMP-8 (79% higher), MMP-9 (29% higher), MMP-10 (60% higher), TIMP-1 (63% higher), and TIMP-2 (136% higher) were detected in aqueous humor from eyes with cPACG, compared with ophthalmologically normal eyes. CLINICAL RELEVANCE MMPs and TIMPs have pivotal roles in extracellular matrix turnover and homeostasis in the outflow pathways of the eye. Results of the present study documented higher concentrations of MMPs and TIMPs in aqueous humor samples from dog eyes with late-stage cPACG. Although, to our knowledge, TIMPs have not previously been evaluated in the context of cPACG, the markedly higher concentration of TIMPs in eyes with cPACG suggested that inhibition of proteolysis and extracellular matrix turnover might be a factor in the development of glaucoma in susceptible individuals. However, because the present study used samples from dogs with late-stage cPACG, further work is required to characterize the temporal relationship between MMP and TIMP concentration changes and onset or progression of disease.
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Affiliation(s)
- Stephanie A Pumphrey
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
| | - Emily Zitek-Morrison
- Department of Population and Quantitative Health Sciences, UMass Chan Medical School, University of Massachusetts, Worcester, MA
| | - Stefano Pizzirani
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
| | - Dawn M Meola
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
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Wilson MR, Satapathy S, Jeong S, Fini ME. Clusterin, other extracellular chaperones, and eye disease. Prog Retin Eye Res 2021; 89:101032. [PMID: 34896599 DOI: 10.1016/j.preteyeres.2021.101032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 11/30/2021] [Accepted: 11/30/2021] [Indexed: 12/15/2022]
Abstract
Proteostasis refers to all the processes that maintain the correct expression level, location, folding and turnover of proteins, essential to organismal survival. Both inside cells and in body fluids, molecular chaperones play key roles in maintaining proteostasis. In this article, we focus on clusterin, the first-recognized extracellular mammalian chaperone, and its role in diseases of the eye. Clusterin binds to and inhibits the aggregation of proteins that are misfolded due to mutations or stresses, clears these aggregating proteins from extracellular spaces, and facilitates their degradation. Clusterin exhibits three main homeostatic activities: proteostasis, cytoprotection, and anti-inflammation. The so-called "protein misfolding diseases" are caused by aggregation of misfolded proteins that accumulate pathologically as deposits in tissues; we discuss several such diseases that occur in the eye. Clusterin is typically found in these deposits, which is interpreted to mean that its capacity as a molecular chaperone to maintain proteostasis is overwhelmed in the disease state. Nevertheless, the role of clusterin in diseases involving such deposits needs to be better defined before therapeutic approaches can be entertained. A more straightforward case can be made for therapeutic use of clusterin based on its proteostatic role as a proteinase inhibitor, as well as its cytoprotective and anti-inflammatory properties. It is likely that clusterin works together in this way with other extracellular chaperones to protect the eye from disease, and we discuss several examples. We end this article by predicting future steps that may lead to development of clusterin as a biological drug.
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Affiliation(s)
- Mark R Wilson
- Molecular Horizons and the School of Chemistry and Molecular Bioscience, University of Wollongong; Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, New South Wales, 2522, Australia.
| | - Sandeep Satapathy
- Molecular Horizons and the School of Chemistry and Molecular Bioscience, University of Wollongong; Illawarra Health and Medical Research Institute, Northfields Avenue, Wollongong, New South Wales, 2522, Australia.
| | - Shinwu Jeong
- USC Roski Eye Institute and Department of Ophthalmology, Keck School of Medicine of USC, University of Southern California, 1333 San Pablo Street., Los Angeles, CA, 90033, USA.
| | - M Elizabeth Fini
- New England Eye Center, Tufts Medical Center and Department of Ophthalmology, Tufts University School of Medicine; Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences, Tufts University, 800 Washington St, Boston, MA, 02111, USA.
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Martin MD, Huard DJ, Guerrero-Ferreira RC, Desai IM, Barlow BM, Lieberman RL. Molecular architecture and modifications of full-length myocilin. Exp Eye Res 2021; 211:108729. [DOI: 10.1016/j.exer.2021.108729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/26/2021] [Accepted: 08/12/2021] [Indexed: 01/06/2023]
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Gindina S, Hu Y, Barron AO, Qureshi Z, Danias J. Tissue plasminogen activator attenuates outflow facility reduction in mouse model of juvenile open angle glaucoma. Exp Eye Res 2020; 199:108179. [PMID: 32739292 DOI: 10.1016/j.exer.2020.108179] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/19/2020] [Accepted: 07/29/2020] [Indexed: 12/12/2022]
Abstract
Tissue plasminogen activator (tPA) has been shown to prevent steroid-induced reduction in aqueous humor outflow facility via an upregulation in matrix metalloproteinase (Mmp) expression. The purpose of this study was to determine whether tPA can rescue outflow facility reduction in the Tg-MYOCY437H mouse model, which replicates human juvenile open angle glaucoma. Outflow facility was measured in Tg-MYOCY437H mice following: periocular steroid exposure and intraocular protein treatment with enzymatically active or enzymatically inactive tPA. Effects of tPA on outflow facility were compared to those of animals treated with topical sodium phenylbutarate (PBA), a modulator of endoplasmic reticulum stress. Gene expression of fibrinolytic pathway components (Plat, Plau, and Pai-1) and matrix metalloproteinases (Mmp-2, -9, and -13) was determined in angle ring tissues containing the trabecular meshwork. Tg-MYOCY437H mice did not display further outflow facility reduction following steroid exposure. Enzymatically active and enzymatically inactive tPA were equally effective in attenuating outflow facility reduction in Tg-MYOCY437H mice and caused enhanced expression of matrix metalloproteinases (Mmp-9 and Mmp-13). tPA was equally effective to topical PBA treatment in ameliorating outflow facility reduction in Tg-MYOCY437H mice. Both treatments were associated with an upregulation in Mmp-9 expression while tPA also upregulated Mmp-13 expression. tPA increases the expression of matrix metalloproteinases and may cause extracellular matrix remodeling at the trabecular meshwork, which results in reversal of outflow facility reduction in Tg-MYOCY437H mice.
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Affiliation(s)
- Sofya Gindina
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
| | - Yan Hu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Arturo O Barron
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Zain Qureshi
- Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - John Danias
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
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O'Gorman L, Cree AJ, Ward D, Griffiths HL, Sood R, Denniston AK, Self JE, Ennis S, Lotery AJ, Gibson J. Comprehensive sequencing of the myocilin gene in a selected cohort of severe primary open-angle glaucoma patients. Sci Rep 2019; 9:3100. [PMID: 30816137 PMCID: PMC6395666 DOI: 10.1038/s41598-019-38760-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 01/07/2019] [Indexed: 11/16/2022] Open
Abstract
Primary open-angle glaucoma (POAG) is the most common form of glaucoma, prevalent in approximately 1–2% of Caucasians in the UK over the age of 40. It is characterised by an open anterior chamber angle, raised intraocular pressure (IOP) and optic nerve damage leading to loss of sight. The myocilin gene (MYOC) is the most common glaucoma-causing gene, accounting for ~2% of British POAG cases. 358 patients were selected for next generation sequencing (NGS) with the following selection criteria: Caucasian ethnicity, intraocular pressure (IOP) 21–40 mm Hg, cup:disc ratio ≥0.6 and visual field mean deviation ≤−3. The entire MYOC gene (17,321 bp) was captured including the promoter, introns, UTRs and coding exons. We identify 12 exonic variants (one stop-gain, five missense and six synonymous variants), two promoter variants, 133 intronic variants, two 3′ UTR variants and 23 intergenic variants. Four known or predicted pathogenic exonic variants (p.R126W, p.K216K, p.Q368* and p.T419A) were identified across 11 patients, which accounts for 3.07% of this POAG cohort. This is the first time that the entire region of MYOC has been sequenced and variants reported for a cohort of POAG patients.
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Affiliation(s)
- Luke O'Gorman
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Angela J Cree
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Daniel Ward
- Molecular Genetics Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, UK
| | - Helen L Griffiths
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Roshan Sood
- Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
| | - Alastair K Denniston
- Department of Ophthalmology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Jay E Self
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.,Eye Unit, University Hospital Southampton, Southampton, UK
| | - Sarah Ennis
- Human Genetics & Genomic Medicine, Faculty of Medicine, University of Southampton, Southampton, UK.
| | - Andrew J Lotery
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.,Eye Unit, University Hospital Southampton, Southampton, UK
| | - Jane Gibson
- Biological Sciences, Faculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK
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Wang H, Li M, Zhang Z, Xue H, Chen X, Ji Y. Physiological function of myocilin and its role in the pathogenesis of glaucoma in the trabecular meshwork (Review). Int J Mol Med 2018; 43:671-681. [PMID: 30483726 PMCID: PMC6317685 DOI: 10.3892/ijmm.2018.3992] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Accepted: 11/16/2018] [Indexed: 12/26/2022] Open
Abstract
Myocilin is highly expressed in the trabecular meshwork (TM), which plays an important role in the regulation of intraocular pressure (IOP). Myocilin abnormalities may cause dysfunction of the TM, potentially leading to increased IOP. High IOP is a well‑known primary risk factor for glaucoma. Myocilin mutations are common among glaucoma patients, and they are implicated in juvenile‑onset open‑angle glaucoma (JOAG) and adult‑onset primary open‑angle glaucoma (POAG). Aggregation of aberrant mutant myocilins is closely associated with glaucoma pathogenesis. The aim of the present review was to discuss the recent findings regarding the major physiological functions of myocilin, such as intra‑ and extracellular proteolytic processes. We also aimed to discuss the risk factors associated with myocilin and the development of glaucoma, such as misfolded/mutant myocilin, imbalance of myocilin and extracellular proteins, and instability of mutant myocilin associated with temperature. Finally, we further outlined certain issues that are yet to be resolved, which may represent the basis for future studies on the role of myocilin in glaucoma.
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Affiliation(s)
- Hongwei Wang
- Department of Ophthalmology, Jingjiang People's Hospital, Jingjiang, Jiangsu 214500, P.R. China
| | - Mingzhe Li
- Department of Ophthalmology, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai 201399, P.R. China
| | - Zhenzhen Zhang
- Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, P.R. China
| | - Haifeng Xue
- Public Health School, Qiqihar Medical University, Qiqihar, Heilongjiang 161006, P.R. China
| | - Xing Chen
- Department of Science and Education, Jingjiang People's Hospital, Jingjiang, Jiangsu 214500, P.R. China
| | - Yong Ji
- Department of General Surgery, Jingjiang People's Hospital, Jingjiang, Jiangsu 214500, P.R. China
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Affiliation(s)
- M Elizabeth Fini
- Keck School of Medicine of USC, University of Southern California, Los Angeles, California, United States
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