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Transgenic Overexpression of Myocilin Leads to Variable Ocular Anterior Segment and Retinal Alterations Associated with Extracellular Matrix Abnormalities in Adult Zebrafish. Int J Mol Sci 2022; 23:ijms23179989. [PMID: 36077382 PMCID: PMC9456529 DOI: 10.3390/ijms23179989] [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: 07/31/2022] [Revised: 08/18/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
Myocilin is an enigmatic glaucoma-associated glycoprotein whose biological role remains incompletely understood. To gain novel insight into its normal function, we used transposon-mediated transgenesis to generate the first zebrafish line stably overexpressing myocilin [Tg(actb1:myoc-2A-mCherry)]. qPCR showed an approximately four-fold increased myocilin expression in transgenic zebrafish embryos (144 hpf). Adult (13 months old) transgenic animals displayed variable and age-dependent ocular anterior segment alterations. Almost 60% of two-year-old male, but not female, transgenic zebrafish developed enlarged eyes with severe asymmetrical and variable abnormalities in the anterior segment, characterized by corneal limbus hypertrophy, and thickening of the cornea, iris, annular ligament and lens capsule. The most severe phenotype presented small or absent ocular anterior chamber and pupils, due to iris overgrowth along with dysplastic retinal growth and optic nerve hypertrophy. Immunohistochemistry revealed increased presence of myocilin in most altered ocular tissues of adult transgenic animals, as well as signs of retinal gliosis and expanded ganglion cells and nerve fibers. The preliminary results indicate that these cells contributed to retinal dysplasia. Visual impairment was demonstrated in all old male transgenic zebrafish. Transcriptomic analysis of the abnormal transgenic eyes identified disrupted expression of genes involved in lens, muscular and extracellular matrix activities, among other processes. In summary, the developed transgenic zebrafish provides a new tool to investigate this puzzling protein and provides evidence for the role of zebrafish myocilin in ocular anterior segment and retinal biology, through the influence of extracellular matrix organization and cellular proliferation.
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Lavanya Devi AL, Nongthomba U, Bobji MS. Quantitative characterization of adhesion and stiffness of corneal lens of Drosophila melanogaster using atomic force microscopy. J Mech Behav Biomed Mater 2015; 53:161-173. [PMID: 26327451 DOI: 10.1016/j.jmbbm.2015.08.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 07/26/2015] [Accepted: 08/07/2015] [Indexed: 11/25/2022]
Abstract
Atomic force Microscopy (AFM) has become a versatile tool in biology due to its advantage of high-resolution imaging of biological samples close to their native condition. Apart from imaging, AFM can also measure the local mechanical properties of the surfaces. In this study, we explore the possibility of using AFM to quantify the rough eye phenotype of Drosophila melanogaster through mechanical properties. We have measured adhesion force, stiffness and elastic modulus of the corneal lens using AFM. Various parameters affecting these measurements like cantilever stiffness and tip geometry are systematically studied and the measurement procedures are standardized. Results show that the mean adhesion force of the ommatidial surface varies from 36 nN to 16 nN based on the location. The mean stiffness is 483 ± 5 N/m, and the elastic modulus is 3.4 ± 0.05 GPa (95% confidence level) at the center of ommatidia. These properties are found to be different in corneal lens of eye expressing human mutant tau gene (mutant). The adhesion force, stiffness and elastic modulus are decreased in the mutant. We conclude that the measurement of surface and mechanical properties of D. melanogaster using AFM can be used for quantitative evaluation of 'rough eye' surface.
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Affiliation(s)
- A L Lavanya Devi
- Centre for Nanoscience and Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India; Department of Mechanical Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Upendra Nongthomba
- Department of Molecular Reproduction and Development Genetics, Indian Institute of Science, Bangalore, Karnataka 560012, India.
| | - M S Bobji
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India.
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Ayub H, Micheal S, Akhtar F, Khan MI, Bashir S, Waheed NK, Ali M, Schoenmaker-Koller FE, Shafique S, Qamar R, den Hollander AI. Association of a polymorphism in the BIRC6 gene with pseudoexfoliative glaucoma. PLoS One 2014; 9:e105023. [PMID: 25118708 PMCID: PMC4132048 DOI: 10.1371/journal.pone.0105023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 07/20/2014] [Indexed: 12/25/2022] Open
Abstract
Recently an association was observed between alleles in genes of the unfolded protein response pathway and primary open angle glaucoma (POAG). The goal of the current study is to investigate the role of these two genes, protein disulphide isomerase A member 5 (PDIA5) and baculoviral IAP repeat containing 6 (BIRC6), in different forms of glaucoma. 278 patients with POAG, 132 patients with primary angle closure glaucoma (PACG) and 135 patients with pseudoexfoliative glaucoma (PEXG) were genotyped for single nucleotide polymorphisms (SNPs) rs11720822 in PDIA5 and 471 POAG, 184 PACG and 218 PEXG patients were genotyped for rs2754511 in BIRC6. Genotyping was done by allelic discrimination PCR, and genotype and allele frequencies were calculated. Logistic regression analyses were performed using R software to determine the association of these SNPs with glaucoma. The allele and genotype frequencies of rs11720822 in PDIA5 were not associated with POAG, PACG or PEXG. The TT genotype of rs2754511 in BIRC6 was found to be protective for PEXG (p = 0.05, OR 0.42 [0.22–0.81]) in the Pakistani population, but not for POAG or PACG. This study did not confirm a previously reported association of risk alleles in PDIA5 and BIRC6 with POAG, but did demonstrate a protective role of the T allele of rs2754511 in the BIRC6 gene in PEXG. This supports a role for the unfolded protein response pathway and regulation of apoptotic cell death in the pathogenesis of PEXG.
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Affiliation(s)
- Humaira Ayub
- Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Shazia Micheal
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Farah Akhtar
- Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan
| | - Muhammad Imran Khan
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Shaheena Bashir
- Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Nadia K. Waheed
- Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Mahmood Ali
- Al-Shifa Trust Eye Hospital, Rawalpindi, Pakistan
| | | | - Sobia Shafique
- Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan
| | - Raheel Qamar
- Department of Biosciences, COMSATS Institute of Information Technology, Islamabad, Pakistan
- Al-Nafees Medical College & Hospital, Isra University, Islamabad, Pakistan
| | - Anneke I. den Hollander
- Department of Ophthalmology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail:
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Borrás T. The effects of myocilin expression on functionally relevant trabecular meshwork genes: a mini-review. J Ocul Pharmacol Ther 2014; 30:202-12. [PMID: 24564495 DOI: 10.1089/jop.2013.0218] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Myocilin is a secreted glaucoma-associated protein, specifically induced by dexamethasone in human trabecular meshwork cells, where it was discovered. Myocilin is expressed in several tissues of the body, but it causes disease only in the eye. The protein contains two domains: an N-terminal region with significant homologies to nonmuscle myosin, and a C-terminal region, which is similar to the olfactomedin proteins. Forty percent of myocilin undergoes an intracellular endoproteolytic cleavage by calpain II, a calcium-dependent cysteine protease, which releases the 2 domains. The protein is known to interact with intracellular and extracellular matrix proteins, and some is released into the extracellular space associated with exosomes. Myocilin mutations are linked to glaucoma and induce elevated intraocular pressure. Most of the glaucoma-causative mutations map to the olfactomedin domain, which appears to be a critical domain for the function of the protein. Myocilin mutants are misfolded, aggregate in the endoplasmic reticulum, and are not secreted. Overexpression of myocilin and of its mutants in primary human trabecular meshwork cells triggers changes in the expression of numerous genes, many of which have been known to be involved in mechanisms important for the physiology and pathology of the tissue. Here we review recent studies from our laboratory and those of others that deal with trabecular meshwork genes, which are altered by the overexpression of wild-type and glaucoma-causative mutant myocilin genes.
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Affiliation(s)
- Teresa Borrás
- Department of Ophthalmology, University of North Carolina School of Medicine , Chapel Hill, North Carolina
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Anholt RRH, Carbone MA. A molecular mechanism for glaucoma: endoplasmic reticulum stress and the unfolded protein response. Trends Mol Med 2013; 19:586-93. [PMID: 23876925 PMCID: PMC3795998 DOI: 10.1016/j.molmed.2013.06.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/20/2013] [Accepted: 06/28/2013] [Indexed: 10/26/2022]
Abstract
Primary open angle glaucoma (POAG) is a common late-onset neurodegenerative disease. Ocular hypertension represents a major risk factor, but POAG etiology remains poorly understood. Some cases of early-onset congenital glaucoma and adult POAG are linked to mutations in myocilin, a secreted protein of poorly defined function. Transgenic overexpression of myocilin in Drosophila and experiments in mice and human populations implicate the unfolded protein response (UPR) in the pathogenesis of glaucoma. We postulate that compromised ability of the UPR to eliminate misfolded mutant or damaged proteins, including myocilin, causes endoplasmic reticulum stress, resulting in functional impairment of trabecular meshwork cells that regulate intraocular pressure. This mechanism of POAG is reminiscent of other age-dependent neurodegenerative diseases that involve accumulation of protein aggregates.
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Affiliation(s)
- Robert R H Anholt
- Department of Biological Sciences and W.M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, NC 27695-7617, USA.
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Mookherjee S, Acharya M, Banerjee D, Bhattacharjee A, Ray K. Molecular basis for involvement of CYP1B1 in MYOC upregulation and its potential implication in glaucoma pathogenesis. PLoS One 2012; 7:e45077. [PMID: 23028769 PMCID: PMC3448602 DOI: 10.1371/journal.pone.0045077] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 08/17/2012] [Indexed: 01/30/2023] Open
Abstract
CYP1B1 has been implicated in primary congenital glaucoma with autosomal recessive mode of inheritance. Mutations in CYP1B1 have also been reported in primary open angle glaucoma (POAG) cases and suggested to act as a modifier of the disease along with Myocilin (MYOC). Earlier reports suggest that over-expression of myocilin leads to POAG pathogenesis. Taken together, we propose a functional interaction between CYP1B1 and myocilin where 17β estradiol acts as a mediator. Therefore, we hypothesize that 17β estradiol can induce MYOC expression through the putative estrogen responsive elements (EREs) located in its promoter and CYP1B1 could manipulate MYOC expression by metabolizing 17β estradiol to 4-hydroxy estradiol, thus preventing it from binding to MYOC promoter. Hence any mutation in CYP1B1 that reduces its 17β estradiol metabolizing activity might lead to MYOC upregulation, which in turn might play a role in glaucoma pathogenesis. It was observed that 17β estradiol is present in Human Trabecular Meshwork cells (HTM) and Retinal Pigment Epithelial cells (RPE) by immunoflouresence and ELISA. Also, the expression of enzymes related to estrogen biosynthesis pathway was observed in both cell lines by RT-PCR. Subsequent evaluation of the EREs in the MYOC promoter by luciferase assay, with dose and time dependent treatment of 17β estradiol, showed that the EREs are indeed active. This observation was further validated by direct binding of estrogen receptors (ER) on EREs in MYOC promoter and subsequent upregulation in MYOC level in HTM cells on 17β estradiol treatment. Interestingly, CYP1B1 mutants with less than 10% enzymatic activity were found to increase the level of endogenous myocilin in HTM cells. Thus the experimental observations are consistent with our proposed hypothesis that mutant CYP1B1, lacking the 17β estradiol metabolizing activity, can cause MYOC upregulation, which might have a potential implication in glaucoma pathogenesis.
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Affiliation(s)
- Suddhasil Mookherjee
- Molecular & Human Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Moulinath Acharya
- Molecular & Human Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Deblina Banerjee
- Molecular & Human Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Ashima Bhattacharjee
- Molecular & Human Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Kunal Ray
- Molecular & Human Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
- * E-mail:
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Ghanem AA, El-Awady HE, Wolfs RCW, Arafa LF. Myocilin levels in the aqueous humor of open-angle glaucoma patients. Interv Med Appl Sci 2012. [DOI: 10.1556/imas.4.2012.1.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
AbstractPurpose:To investigate the concentration of myocilin in the aqueous humor of open-angle glaucoma (OAG) patients, including correlations with glaucoma subtypes and intraocular pressure (IOP).Patients and Methods:The study comprised 85 patients with OAG. Glaucoma subtypes included 35 cases of high tension glaucoma (HTG), 25 cases of normal tension glaucoma (NTG), and 25 cases of exfoliation glaucoma (ExG). Forty-five patients with senile cataract were included as control. The concentrations of myocilin in the aqueous humor were measured by plotting the densitometry readings of the aqueous humor samples against a recombinant myocilin standard curve. Additionally, the relationships with the glaucoma subtypes, IOP, and glaucoma severity were analyzed.Results:A significantly higher percentage of patients in the glaucoma subgroups were positive for myocilin compared with the cataract group. The mean myocilin concentrations among the glaucoma positive case subgroups were not different (P=0.326). Myocilin levels were significantly higher in human HTG compared with cataract group (P<0.05). There were no significant correlations between the myocilin concentration and the IOP or the severity of glaucoma.Conclusion:Myocilin-positive patients were significant in the glaucoma subgroups than in the cataract group, with a highly significant difference observed for HTG patients.
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Affiliation(s)
- Asaad A. Ghanem
- 1 Department of Ophthalmology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Hatem E. El-Awady
- 1 Department of Ophthalmology, Faculty of Medicine, Mansoura University, Mansoura, Egypt
| | - Roger C. W. Wolfs
- 2 Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Lmiaa F. Arafa
- 3 Department of Medical Biochemistry, Faculty of Medicine, Mansoura University, Mansoura, Egypt
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Genes of the unfolded protein response pathway harbor risk alleles for primary open angle glaucoma. PLoS One 2011; 6:e20649. [PMID: 21655191 PMCID: PMC3105107 DOI: 10.1371/journal.pone.0020649] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 05/06/2011] [Indexed: 11/22/2022] Open
Abstract
The statistical power of genome-wide association (GWA) studies to detect risk alleles for human diseases is limited by the unfavorable ratio of SNPs to study subjects. This multiple testing problem can be surmounted with very large population sizes when common alleles of large effects give rise to disease status. However, GWA approaches fall short when many rare alleles may give rise to a common disease, or when the number of subjects that can be recruited is limited. Here, we demonstrate that this multiple testing problem can be overcome by a comparative genomics approach in which an initial genome-wide screen in a genetically amenable model organism is used to identify human orthologues that may harbor risk alleles for adult-onset primary open angle glaucoma (POAG). Glaucoma is a major cause of blindness, which affects over 60 million people worldwide. Several genes have been associated with juvenile onset glaucoma, but genetic factors that predispose to adult onset primary open angle glaucoma (POAG) remain largely unknown. Previous genome-wide analysis in a Drosophila ocular hypertension model identified transcripts with altered regulation and showed induction of the unfolded protein response (UPR) upon overexpression of transgenic human glaucoma-associated myocilin (MYOC). We selected 16 orthologous genes with 62 polymorphic markers and identified in two independent human populations two genes of the UPR that harbor POAG risk alleles, BIRC6 and PDIA5. Thus, effectiveness of the UPR in response to accumulation of misfolded or aggregated proteins may contribute to the pathogenesis of POAG and provide targets for early therapeutic intervention.
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Yu M, Sun J, Peng W, Chen Z, Lin X, Liu X, Li M, Wu K. Protein expression in human trabecular meshwork: downregulation of RhoGDI by dexamethasone in vitro. Mol Vis 2010; 16:213-23. [PMID: 20161819 PMCID: PMC2822554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 02/04/2010] [Indexed: 12/04/2022] Open
Abstract
PURPOSE The characterization of the human trabecular meshwork (TM) proteome is a valuable step toward understanding its role under normal and glaucomatous conditions. This study uses proteomic techniques to investigate the set of proteins expressed in normal human TM and to identify those differentially expressed in response to dexamethasone (DEX) treatment of TM cells (TMCs) in vitro. METHODS TM tissue (TMT) was isolated from human donor eyes and pooled. Immortalized human TMCs were cultured with or without DEX. Protein extracts from each were separated by two-dimensional electrophoresis (2-DE). Protein spots in TMT gel were excised, destained, and subjected to in-gel tryptic digestion and identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). To determine those proteins whose expression patterns were affected by glucocorticoids, TMCs were treated with DEX and assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) dye and 2-DE. A differentially expressed protein, RhoGDI, was validated by both western blotting and immunocytological staining. RESULTS The comprehensive protein set included more than 850 protein spots from both the TMT and TMCs, as visualized on 2-DE gel. Two-hundred-and-thirty-five spots were successfully identified in the TMT gel. The functional categories of the identified proteins were mainly comprised of metabolic process, cell adhesion, anti-apoptosis, cell motility, carbohydrate metabolic process, signal transduction, and regulation of transcription. During three days of DEX treatment, TMCs' proliferation was inhibited in a time- and dose-dependent manner, as evidenced by MTT assay. In the 48 h cultured cell group, RhoGDI expression was reduced, as detected by 2-DE, western blotting, and immunocytological staining. In contrast, the expression of RhoA, a target of RhoGDI, increased in response to DEX treatment. CONCLUSIONS Using the classic proteomic workflow, the main protein complement of normal human TMT was detected, identified, and categorized. The DEX inhibition of RhoGDI expression in TMCs was evidenced.
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Affiliation(s)
- Minbin Yu
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China
| | - Jing Sun
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China
| | - Wei Peng
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China
| | - Ziyan Chen
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China
| | - Xianchai Lin
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China
| | - Xuyang Liu
- Department of Ophthalmology and Ophthalmic Laboratories, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Mingtao Li
- The Proteomics Lab, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, P.R. China
| | - Kaili Wu
- Zhongshan Ophthalmic Center; State Key Laboratory of Ophthalmology, Sun Yat-sen University, Guangzhou, P.R. China,The Proteomics Lab, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, P.R. China
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Carbone MA, Ayroles JF, Yamamoto A, Morozova TV, West SA, Magwire MM, Mackay TFC, Anholt RRH. Overexpression of myocilin in the Drosophila eye activates the unfolded protein response: implications for glaucoma. PLoS One 2009; 4:e4216. [PMID: 19148291 PMCID: PMC2615221 DOI: 10.1371/journal.pone.0004216] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2008] [Accepted: 12/05/2008] [Indexed: 12/18/2022] Open
Abstract
Background Glaucoma is the world's second leading cause of bilateral blindness with progressive loss of vision due to retinal ganglion cell death. Myocilin has been associated with congenital glaucoma and 2–4% of primary open angle glaucoma (POAG) cases, but the pathogenic mechanisms remain largely unknown. Among several hypotheses, activation of the unfolded protein response (UPR) has emerged as a possible disease mechanism. Methodology / Principal Findings We used a transgenic Drosophila model to analyze whole-genome transcriptional profiles in flies that express human wild-type or mutant MYOC in their eyes. The transgenic flies display ocular fluid discharge, reflecting ocular hypertension, and a progressive decline in their behavioral responses to light. Transcriptional analysis shows that genes associated with the UPR, ubiquitination, and proteolysis, as well as metabolism of reactive oxygen species and photoreceptor activity undergo altered transcriptional regulation. Following up on the results from these transcriptional analyses, we used immunoblots to demonstrate the formation of MYOC aggregates and showed that the formation of such aggregates leads to induction of the UPR, as evident from activation of the fluorescent UPR marker, xbp1-EGFP. Conclusions / Significance Our results show that aggregation of MYOC in the endoplasmic reticulum activates the UPR, an evolutionarily conserved stress pathway that culminates in apoptosis. We infer from the Drosophila model that MYOC-associated ocular hypertension in the human eye may result from aggregation of MYOC and induction of the UPR in trabecular meshwork cells. This process could occur at a late age with wild-type MYOC, but might be accelerated by MYOC mutants to account for juvenile onset glaucoma.
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Affiliation(s)
- Mary Anna Carbone
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Julien F. Ayroles
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Akihiko Yamamoto
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- Department of Zoology, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Tatiana V. Morozova
- Department of Zoology, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Steven A. West
- Department of Zoology, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Michael M. Magwire
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Trudy F. C. Mackay
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Robert R. H. Anholt
- Department of Zoology, North Carolina State University, Raleigh, North Carolina, United States of America
- W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, United States of America
- * E-mail:
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MacKay EO, Kallberg ME, Barrie KP, Miller W, Sapienza JS, Denis H, Ollivier FJ, Plummer C, Rinkoski T, Scotty N, Gelatt KN. Myocilin protein levels in the aqueous humor of the glaucomas in selected canine breeds. Vet Ophthalmol 2008; 11:234-41. [PMID: 18638349 DOI: 10.1111/j.1463-5224.2008.00631.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To compare aqueous humor myocilin protein levels in dogs with the primary glaucomas to those with the secondary glaucomas, primary cataracts, and diabetic cataracts. MATERIALS AND METHODS Four groups were selected, based on diagnosis by the attending veterinary ophthalmologists and included: primary glaucoma (primary open-angle glaucoma (POAG) and primary closed angle glaucoma (PCAG); n = 155); secondary glaucoma (n = 94); primary (presumed inherited) cataract (n = 142), and diabetic cataract (n = 83). A total of 474 samples (187 males, 263 females, 24 unreported) with average ages of 117 months for the males and 101 months for the females were analyzed. Myocilin protein was measured using the Coomassie staining and Western blot methods relative to a myocilin control. RESULTS Differences were seen between nonglaucomatous (cataractous) and glaucomatous dogs with myocilin levels in glaucomatous eyes being many times higher than those in the cataractous dogs. Primary glaucomatous dogs were found to have an aqueous humor myocilin protein level of 17.30 +/- 1.03 units. Secondary glaucomas had the highest level of myocilin in the aqueous humor with 19.27 +/- 1.41 units. Diabetic cataractous dogs had the lowest levels of myocilin reported with 6.60 +/- 0.88 (mean +/- SEM) units. Normal (cataractous) dogs had a myocilin level in the aqueous humor of 8.05 +/- 0.86 units. CONCLUSION Aqueous humor protein levels were elevated, relative to the myocilin control, in both the primary and secondary glaucoma groups compared to the cataract and diabetic cataract groups. Like in the Beagle POAG, aqueous humor myocilin protein levels are increased. Further studies are indicated to investigate the exact role of the aqueous humor myocilin protein in the genesis in increased IOP in these primary glaucomatous breeds.
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Affiliation(s)
- E O MacKay
- Department of Small Animal Clinical Sciences and Gwathmey-Adams Laboratory for Vision Research, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
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MacKay EO, Källberg ME, Gelatt KN. Aqueous humor myocilin protein levels in normal, genetic carriers, and glaucoma Beagles. Vet Ophthalmol 2008; 11:177-85. [DOI: 10.1111/j.1463-5224.2008.00617.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
Understanding the genetic and environmental factors affecting human complex genetic traits and diseases is a major challenge because of many interacting genes with individually small effects, whose expression is sensitive to the environment. Dissection of complex traits using the powerful genetic approaches available with Drosophila melanogaster has provided important lessons that should be considered when studying human complex traits. In Drosophila, large numbers of pleiotropic genes affect complex traits; quantitative trait locus alleles often have sex-, environment-, and genetic background-specific effects, and variants associated with different phenotypic are in noncoding as well as coding regions of candidate genes. Such insights, in conjunction with the strong evolutionary conservation of key genes and pathways between flies and humans, make Drosophila an excellent model system for elucidating the genetic mechanisms that affect clinically relevant human complex traits, such as alcohol dependence, sleep, and neurodegenerative diseases.
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Affiliation(s)
- Trudy F C Mackay
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, 27695, USA.
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Huang AJW. Suppression of keratoepithelin and myocilin by small interfering RNA (an American Ophthalmological Society thesis). TRANSACTIONS OF THE AMERICAN OPHTHALMOLOGICAL SOCIETY 2007; 105:365-378. [PMID: 18427622 PMCID: PMC2258103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PURPOSE Mutations of keratoepithelin (KE) and myocilin (MYOC) have been linked to certain types of inherited corneal stromal dystrophy and open-angle glaucoma, respectively. In this study, the feasibility of using small interfering RNAs (siRNAs) to suppress the expression of keratoepithelin and myocilin and their capabilities to reduce the related cytotoxic effects caused by mutant myocilins were investigated. METHODS cDNAs of human KE gene and myocilin gene were amplified by polymerase chain reaction and subcloned into pEGFP-N1 to construct respective plasmids, KEpEGFP and MYOCpEGFP, to produce fluorescence-generating fusion proteins. Short hairpin RNAs (shRNAs) were generated from an RNA polymerase III promoter-driven vector (pH1-RNA). Transformed HEK293 and trabecular meshwork (TM) cells were cotransfected via liposomes with either KEpEGFP or MYOCpEGFP and respective shRNA-generating plasmids to evaluate the suppression efficacy of shRNAs. Suppression of KE-EGFP by KE-specific shRNAs was evaluated by fluorescence microscopy and Western blotting. Suppression of MYOC-EGFP by myocilin-specific shRNAs was quantified with UN-SCAN-IT software on digitized protein bands of Western blots. A BiP promoter-driven luciferase reporter assay was used to evaluate the stress response of TM cells induced by misfolded mutant myocilins. RESULTS Two KE-specific shRNAs that effectively suppressed the expression of KE-EGFP in HEK293 cells were identified. One shRNA (targeting the coding sequence starting at 1528bp of KE) reduced the expression of KE-EGFP approximately by 50%, whereas the other shRNA (targeting the 3'-UTR region of KE) suppressed greater than 80% of the expression. Cotransfection of MYOCpEGFP and various shRNA-generating plasmids targeting different regions of myocilin (containing amino acid residues R76, E352, K423, or N480 associated with inherited glaucoma) showed effective reduction of MYOC-EGFP, ranging from 78% to 90% on average. The activation of BiP gene (as a stress response induced by mutant myocilins) in transformed TM cells was significantly reduced when mutant myocilin proteins were suppressed by myocilin-specific shRNAs. CONCLUSIONS KE- or myocilin-specific shRNAs could effectively suppress the expression of recombinant KE or myocilin proteins and the related cytotoxicity of mutant myocilins. RNA interference may have future therapeutic implications in suppressing these genes.
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Affiliation(s)
- Andrew J W Huang
- Department of Ophthalmology, University of Minnesota, Minneapolis, USA
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Borrás T, Bryant PA, Chisolm SS. First look at the effect of overexpression of TIGR/MYOC on the transcriptome of the human trabecular meshwork. Exp Eye Res 2006; 82:1002-10. [PMID: 16476427 DOI: 10.1016/j.exer.2005.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Revised: 11/08/2005] [Accepted: 11/12/2005] [Indexed: 11/23/2022]
Abstract
Wild-type TIGR/MYOC is a secreted protein implicated in the development of steroid glaucoma. Mutations in TIGR/MYOC have been linked to some patients who develop elevated intraocular pressure (IOP) and glaucoma. Because there is evidence of some other factors contributing to the TIGR/MYOC causative role in glaucoma, and because substantial increased levels of a particular cellular mRNA and protein might alter expression of other host genes, we began to investigate the effect of TIGR/MYOC overexpression on the transcriptome of human trabecular meshwork cells. We used a recombinant adenovirus carrying wild-type TIGR/MYOC cDNA, primary HTM cells, 300 viral particles per cell and U133 Affymetrix GeneChips. Our results indicate that 2361 out of the 22,284 genes (10.6%) were altered more than two-fold (p<or=0.005) by the overexpression of TIGR/MYOC. A higher proportion of the altered genes were downregulated (1412 vs. 949). Potentially relevant upregulated genes include angiopoietin 2, matrix metalloproteinase 1 (MMP1) and thrombomodulin; among those downregulated we observed growth arrest specific 1, proteins involved in the ubiquitination pathway and vascular cell adhesion molecule 1. In addition, collagen type 1, one of the MMP1 substrates, was also downregulated. Genes affected by wild-type TIGR/MYOC might prove to be candidate mediators for future studies of the mechanisms of glaucoma.
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Affiliation(s)
- Teresa Borrás
- Department of Ophthalmology, School of Medicine, University of North Carolina, at Chapel Hill, 6109 Neuroscience Research Building CB 7041, 103 Mason Farm Road, Chapel Hill, NC 27599-7041, USA.
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Anholt RRH, Mackay TFC. Quantitative genetic analyses of complex behaviours in Drosophila. Nat Rev Genet 2004; 5:838-49. [PMID: 15520793 DOI: 10.1038/nrg1472] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Behaviours are exceptionally complex quantitative traits. Sensitivity to environmental variation and genetic background, the presence of sexual dimorphism, and the widespread functional pleiotropy that is inherent in behavioural phenotypes pose daunting challenges for unravelling their underlying genetics. Drosophila melanogaster provides an attractive system for elucidating the unifying principles of the genetic architectures that drive behaviours, as genetically identical individuals can be reared rapidly in controlled environments and extensive publicly accessible genetic resources are available. Recent advances in quantitative genetic and functional genomic approaches now enable the extensive characterization of complex genetic networks that mediate behaviours in this important model organism.
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Affiliation(s)
- Robert R H Anholt
- Department of Zoology, W. M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina 27695-7617, USA.
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Vu Manh TP, Mokrane M, Georgenthum E, Flavigny J, Carrier L, Sémériva M, Piovant M, Röder L. Expression of cardiac myosin-binding protein-C (cMyBP-C) in Drosophila as a model for the study of human cardiomyopathies. Hum Mol Genet 2004; 14:7-17. [PMID: 15525659 DOI: 10.1093/hmg/ddi002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations in the MYBPC3 gene encoding human cardiac myosin-binding protein-C (cMyBP-C) are associated with familial hypertrophic cardiomyopathy (FHC), but the molecular mechanisms involved are not fully understood. In addition, development of FHC is sensitive to genetic background, and the search for candidate modifier genes is crucial with a view to proposing diagnosis and exploring new therapies. We used Drosophila as the model to investigate the in vivo consequences of human cMyBP-C mutations. We first produced transgenic flies that specifically express human wild-type or two C-terminal truncated cMyBP-Cs in indirect flight muscles (IFM), a tissue particularly amenable to genetic and molecular analyses. First, incorporation of human cMyBP-C into the IFM led to sarcomeric structural abnormalities and to a flightless phenotype aggravated by age and human gene dosage. Second, transcriptome analysis of transgenic IFM using nylon microarrays showed the remodelling of a transcriptional program involving 97 out of 3570 Drosophila genes. Among them, the Calmodulin gene encoding a key component of muscle contraction, found up-regulated in transgenic IFM, was evaluated as a potential modifier gene. Calmodulin mutant alleles rescued the flightless phenotype, and therefore behave as dominant suppressors of the flightless phenotype suggesting that Calmodulin might be a modifier gene in the context of human FHC. In conclusion, we suggest that the combination of heterologous transgenesis and transcriptome analysis in Drosophila could be of great value as a way to glean insights into the molecular mechanisms underlying FHC and to propose potential candidate modifier genes.
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