1
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Choi M, Tichenor AA. Regional Conjunctival Differences in Glycocalyx Mucin Expression in Dry Eye and Normal Subjects. Invest Ophthalmol Vis Sci 2024; 65:20. [PMID: 38334701 PMCID: PMC10860684 DOI: 10.1167/iovs.65.2.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 01/10/2024] [Indexed: 02/10/2024] Open
Abstract
Purpose To compare regional conjunctival expression of membrane-associated mucins (MAMs) MUC1, MUC4, and MUC16 in normal and dry eye (DE) subjects. Methods Adults with and without signs and symptoms of DE were recruited. Impression cytology was performed to collect MAMs from four bulbar and upper eyelid palpebral conjunctival regions of both eyes. After protein extraction, samples from both eyes of a single subject were pooled by region, and expression was analyzed using a capillary electrophoresis nano-immunoassay system. The chemiluminescence intensity of each antigen binding signal was calculated after normalization to the total protein amount. Statistical analyses were conducted using GraphPad Prime 9. Results Samples from thirteen to sixteen DE and seven to eleven normal subjects were analyzed. In normal samples, MUC1 expression from the nasal bulbar conjunctiva was significantly greater than superior (P = 0.004) and inferior (P = 0.005). In DE samples, MUC1 expression was highest superiorly. Significant differences in MUC4 and MUC16 expression were not seen in normal samples. MUC4 and MUC16 expression was upregulated superiorly (P < 0.0001) and inferiorly (P < 0.0001) in DE compared with those regions in normal samples. Conclusions Although MAMs form a hydrophilic barrier called the glycocalyx, each mucin may have unique functions that are currently unexplored. All MAMs were expressed in the upper palpebral conjunctiva. Increased MUC1 expression nasally in healthy subjects suggests a functional need for increased protection. When comparing DE with normal eyes, upregulation of MUC1 superiorly, and in both MUC4 and MUC16 both superiorly and inferiorly, may indicate a need to decrease eyelid friction during blinking, especially in DE.
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Affiliation(s)
- Moonjung Choi
- New England College of Optometry, Boston, Massachusetts, United States
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2
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Wang T, Liu L, Voglmeir J. mAbs N-glycosylation: Implications for biotechnology and analytics. Carbohydr Res 2022; 514:108541. [DOI: 10.1016/j.carres.2022.108541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 12/29/2022]
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3
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Argüeso P. Human ocular mucins: The endowed guardians of sight. Adv Drug Deliv Rev 2022; 180:114074. [PMID: 34875287 PMCID: PMC8724396 DOI: 10.1016/j.addr.2021.114074] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/22/2021] [Accepted: 11/30/2021] [Indexed: 01/03/2023]
Abstract
Mucins are an ancient group of glycoproteins that provide viscoelastic, lubricating and hydration properties to fluids bathing wet surfaced epithelia. They are involved in the protection of underlying tissues by forming a barrier with selective permeability properties. The expression, processing and spatial distribution of mucins are often determined by organ-specific requirements that in the eye involve protecting against environmental insult while allowing the passage of light. The human ocular surface epithelia have evolved to produce an extremely thin and watery tear film containing a distinct soluble mucin product secreted by goblet cells outside the visual axis. The adaptation to the ocular environment is notably evidenced by the significant contribution of transmembrane mucins to the tear film, where they can occupy up to one-quarter of its total thickness. This article reviews the tissue-specific properties of human ocular mucins, methods of isolation and detection, and current approaches to model mucin systems recapitulating the human ocular surface mucosa. This knowledge forms the fundamental basis to develop applications with a promising biological and clinical impact.
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Affiliation(s)
- Pablo Argüeso
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States.
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4
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Cheeseman J, Badia C, Thomson RI, Kuhnle G, Gardner RA, Spencer DIR, Osborn H. Quantitative Standards of 4-O acetyl and 9-O acetyl N-acetyl Neuraminic Acid for the Analysis of Plasma and Serum. Chembiochem 2021; 23:e202100662. [PMID: 34874597 PMCID: PMC9303589 DOI: 10.1002/cbic.202100662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/06/2021] [Indexed: 11/10/2022]
Abstract
N‐Acetylneuraminic acid (sialic acid, Neu5Ac) is one of a large, diverse family of nine‐carbon monosaccharides that play roles in many biological functions such as immune response. Neu5Ac has previously been identified as a potential biomarker for the presence and pathogenesis of cardiovascular disease (CVD), diabetes and cancer. More recent research has highlighted acetylated sialic acid derivatives, specifically Neu5,9Ac2, as biomarkers for oral and breast cancers, but advances in analysis have been hampered due to a lack of commercially available quantitative standards. We report here the synthesis of 9‐O‐ and 4‐O‐acetylated sialic acids (Neu5,9Ac2 and Neu4,5Ac2) with optimisation of previously reported synthetic routes. Neu5,9Ac2 was synthesised in 1 step in 68 % yield. Neu4,5Ac2 was synthesised in 4 steps in 39 % overall yield. Synthesis was followed by analysis of these standards via quantitative NMR (qNMR) spectroscopy. Their utilisation for the identification and quantification of specific acetylated sialic acid derivatives in biological samples is also demonstrated.
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Affiliation(s)
- Jack Cheeseman
- University of Reading - Whiteknights Campus: University of Reading, Pharmacy, UNITED KINGDOM
| | | | - Rebecca I Thomson
- University of Reading - Whiteknights Campus: University of Reading, Pharmacy, UNITED KINGDOM
| | | | | | | | - Helen Osborn
- The university of Reading, School of Chemistry, PO Box 224, Whiteknights, RG6 6AD, Reading, UNITED KINGDOM
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5
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Martinez-Carrasco R, Argüeso P, Fini ME. Membrane-associated mucins of the human ocular surface in health and disease. Ocul Surf 2021; 21:313-330. [PMID: 33775913 PMCID: PMC8328898 DOI: 10.1016/j.jtos.2021.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/02/2021] [Accepted: 03/08/2021] [Indexed: 02/06/2023]
Abstract
Mucins are a family of high molecular weight, heavily-glycosylated proteins produced by wet epithelial tissues, including the ocular surface epithelia. Densely-packed O-linked glycan chains added post-translationally confer the biophysical properties of hydration, lubrication, anti-adhesion and repulsion. Membrane-associated mucins (MAMs) are the distinguishing components of the mucosal glycocalyx. At the ocular surface, MAMs maintain wetness, lubricate the blink, stabilize the tear film, and create a physical barrier to the outside world. In addition, it is increasingly appreciated that MAMs function as cell surface receptors that transduce information from the outside to the inside of the cell. Recently, our team published a comprehensive review/perspectives article for molecular scientists on ocular surface MAMs, including previously unpublished data and analyses on two new genes MUC21 and MUC22, as well as new MAM functions and biological roles, comparing human and mouse (PMID: 31493487). The current article is a refocus for the audience of The Ocular Surface. First, we update the gene and protein information in a more concise form, and include a new section on glycosylation. Next, we discuss biological roles, with some new sections and further updating from our previous review. Finally, we provide a new chapter on MAM involvement in ocular surface disease. We end this with discussion of an emerging mechanism responsible for damage to the epithelia and their mucosal glycocalyces: the unfolded protein response (UPR). The UPR offers a novel target for therapeutic intervention.
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Affiliation(s)
- Rafael Martinez-Carrasco
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center, Boston, MA, 02111, USA.
| | - Pablo Argüeso
- Department of Ophthalmology, Harvard Medical School at Schepens Eye Research Institute of Mass, Eye and Ear, Boston, MA, 02114, USA.
| | - M Elizabeth Fini
- Department of Ophthalmology, Tufts University School of Medicine at New England Eye Center, Tufts Medical Center: Program in Pharmacology & Drug Development, Graduate School of Biomedical Sciences, Tufts University, Boston, MA, O2111, USA.
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6
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Albers M, Schröter L, Belousov S, Hartmann M, Grove M, Abeln M, Mühlenhoff M. The sialyl-O-acetylesterase NanS of Tannerella forsythia encompasses two catalytic modules with different regiospecificity for O7 and O9 of sialic acid. Glycobiology 2021; 31:1176-1191. [PMID: 33909048 DOI: 10.1093/glycob/cwab034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/14/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
The periodontal pathogen Tannerella forsythia utilizes host sialic acids as a nutrient source. To also make O-acetylated sialyl residues susceptible to the action of its sialidase and sialic acid up-take system, Tannerella produces NanS, an O-acetylesterase with two putative catalytic domains. Here, we analyzed NanS by homology modeling, predicted a catalytic serine-histidine-aspartate triad for each catalytic domain and performed individual domain inactivation by single alanine exchanges of the triad nucleophiles S32 and S311. Subsequent functional analyses revealed that both domains possess sialyl-O-acetylesterase activity, but differ in their regioselectivity with respect to position O9 and O7 of sialic acid. The 7-O-acetylesterase activity inherent to the C-terminal domain of NanS is unique among sialyl-O-acetylesterases and fills the current gap in tools targeting 7-O-acetylation. Application of the O7-specific variant NanS-S32A allowed us to evidence the presence of cellular 7,9-di-O-acetylated sialoglycans by monitoring the gain in 9-O-acetylation upon selective removal of acetyl groups from O7. Moreover, we established de-7,9-O-acetylation by wild-type NanS as an easy and efficient method to validate the specific binding of three viral lectins commonly used for the recognition of (7),9-O-acetylated sialoglycans. Their binding critically depends on an acetyl group in O9, yet de-7,9-O-acetylation proved advantageous over de-9-O-acetylation as the additional removal of the 7-O-acetyl group eliminated ligand formation by 7,9-ester migration. Together, our data show that NanS gained dual functionality through recruitment of two esterase modules with complementary activities. This enables Tannerella to scavenge 7,9-di-O-acetylated sialyl residues and provides a novel, O7-specific tool for studying sialic acid O-acetylation.
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Affiliation(s)
- Malena Albers
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Larissa Schröter
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Sergej Belousov
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Maike Hartmann
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Melanie Grove
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Markus Abeln
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
| | - Martina Mühlenhoff
- Institute of Clinical Biochemistry, Hannover Medical School, 30625 Hannover, Germany
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7
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Abstract
The glycocalyx is a dense and diverse coat of glycans and glycoconjugates responsible for maintaining cell surface integrity and regulating the interaction of cells with the external environment. Transmembrane mucins such as MUC1 and MUC16 comprise a major component of the epithelial glycocalyx and are currently used to monitor disease progression in cancer. At the ocular surface, multiple lines of evidence indicate that abnormal expression of the enzymes responsible for glycan biosynthesis during pathological conditions impairs the glycosylation of transmembrane mucins. It is now becoming clear that these changes contribute to modify the interaction of mucins with galectin-3, a multimeric lectin crucial for preserving the ocular surface epithelial barrier. This review highlights the potential of using the epithelial glycocalyx as a reliable source for the generation of biomarkers to diagnose and monitor ocular surface disease.
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8
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Willcox MDP, Walsh K, Nichols JJ, Morgan PB, Jones LW. The ocular surface, coronaviruses and COVID-19. Clin Exp Optom 2020; 103:418-424. [PMID: 32406140 PMCID: PMC7272971 DOI: 10.1111/cxo.13088] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/24/2020] [Accepted: 04/22/2020] [Indexed: 12/21/2022] Open
Abstract
The ocular surface has been suggested as a site of infection with Coronavirus-2 (SARS-CoV-2) responsible for the coronavirus disease-19 (COVID-19). This review examines the evidence for this hypothesis, and its implications for clinical practice. Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), responsible for the COVID-19 pandemic, is transmitted by person-to-person contact, via airborne droplets, or through contact with contaminated surfaces. SARS-CoV-2 binds to angiotensin converting enzyme-2 (ACE2) to facilitate infection in humans. This review sets out to evaluate evidence for the ocular surface as a route of infection. A literature search in this area was conducted on 15 April 2020 using the Scopus database. In total, 287 results were returned and reviewed. There is preliminary evidence for ACE2 expression on corneal and conjunctival cells, but most of the other receptors to which coronaviruses bind appear to be found under epithelia of the ocular surface. Evidence from animal studies is limited, with a single study suggesting viral particles on the eye can travel to the lung, resulting in very mild infection. Coronavirus infection is rarely associated with conjunctivitis, with occasional cases reported in patients with confirmed COVID-19, along with isolated cases of conjunctivitis as a presenting sign. Coronaviruses have been rarely isolated from tears or conjunctival swabs. The evidence suggests coronaviruses are unlikely to bind to ocular surface cells to initiate infection. Additionally, hypotheses that the virus could travel from the nasopharynx or through the conjunctival capillaries to the ocular surface during infection are probably incorrect. Conjunctivitis and isolation of the virus from the ocular surface occur only rarely, and overwhelmingly in patients with confirmed COVID-19. Necessary precautions to prevent person-to-person transmission should be employed in clinical practice throughout the pandemic, and patients should be reminded to maintain good hygiene practices.
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Affiliation(s)
- Mark DP Willcox
- School of Optometry and Vision ScienceThe University of New South WalesSydneyNew South WalesAustralia
| | - Karen Walsh
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision ScienceUniversity of WaterlooWaterlooOntarioCanada
| | - Jason J Nichols
- School of OptometryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Philip B Morgan
- Eurolens Research, Division of Pharmacy and Optometry, The University of ManchesterManchesterUK
| | - Lyndon W Jones
- Centre for Ocular Research & Education (CORE), School of Optometry and Vision ScienceUniversity of WaterlooWaterlooOntarioCanada
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9
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Darula Z, Pap Á, Medzihradszky KF. Extended Sialylated O-Glycan Repertoire of Human Urinary Glycoproteins Discovered and Characterized Using Electron-Transfer/Higher-Energy Collision Dissociation. J Proteome Res 2018; 18:280-291. [PMID: 30407017 DOI: 10.1021/acs.jproteome.8b00587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A relatively novel activation technique, electron-transfer/higher-energy collision dissociation (EThcD) was used in the LC-MS/MS analysis of tryptic glycopeptides enriched with wheat germ agglutinin from human urine samples. We focused on the characterization of mucin-type O-glycopeptides. EThcD in a single spectrum provided information on both the peptide modified and the glycan carried. Unexpectedly, glycan oxonium ions indicated the presence of O-acetyl, and even O-diacetyl-sialic acids. B and Y fragment ions revealed that (i) in core 1 structures the Gal residue featured the O-acetyl-sialic acid, when there was only one in the glycan; (ii) several glycopeptides featured core 1 glycans with disialic acids, in certain instances O-acetylated; (iii) the disialic acid was linked to the GalNAc residue whatever the degree of O-acetylation; (iv) core 2 isomers with a single O-acetyl-sialic acid were chromatographically resolved. Glycan fragmentation also helped to decipher additional core 2 oligosaccharides: a LacdiNAc-like structure, glycans carrying sialyl LewisX/A at different stages of O-acetylation, and blood antigens. A sialo core 3 structure was also identified. We believe this is the first study when such structures were characterized from a very complex mixture and were linked not only to a specific protein, but also the sites of modifications have been determined.
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Affiliation(s)
- Zsuzsanna Darula
- Biological Research Centre of the Hungarian Academy of Sciences , Temesvari krt. 62. , H-6726 Szeged , Hungary
| | - Ádám Pap
- Biological Research Centre of the Hungarian Academy of Sciences , Temesvari krt. 62. , H-6726 Szeged , Hungary.,Doctoral School in Biology, Faculty of Science and Informatics , University of Szeged , Kozep fasor 52. , H-6726 Szeged , Hungary
| | - Katalin F Medzihradszky
- Biological Research Centre of the Hungarian Academy of Sciences , Temesvari krt. 62. , H-6726 Szeged , Hungary
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10
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Abstract
Glycosylation is a major form of enzymatic modification of organic molecules responsible for multiple biological processes in an organism. The biosynthesis of glycans is controlled by a series of glycosyltransferases, glycosidases and glycan-modifying enzymes that collectively assemble and process monosaccharide moieties into a diverse array of structures. Many studies have provided insight into various pathways of glycosylation at the ocular surface, such as those related to the biosynthesis of mucin-type O-glycans and N-glycans on proteins, but many others still remain largely unknown. This review provides an overview of the different classes of glycans described at the ocular surface focusing on their biosynthetic pathways and biological relevance. A precise understanding of these pathways under physiological and pathological conditions could help identify biomarkers and novel targets for therapeutic intervention.
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11
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Abstract
The members of the Tear Film Subcommittee reviewed the role of the tear film in dry eye disease (DED). The Subcommittee reviewed biophysical and biochemical aspects of tears and how these change in DED. Clinically, DED is characterized by loss of tear volume, more rapid breakup of the tear film and increased evaporation of tears from the ocular surface. The tear film is composed of many substances including lipids, proteins, mucins and electrolytes. All of these contribute to the integrity of the tear film but exactly how they interact is still an area of active research. Tear film osmolarity increases in DED. Changes to other components such as proteins and mucins can be used as biomarkers for DED. The Subcommittee recommended areas for future research to advance our understanding of the tear film and how this changes with DED. The final report was written after review by all Subcommittee members and the entire TFOS DEWS II membership.
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12
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Chen BJ, Lam TC, Liu LQ, To CH. Post-translational modifications and their applications in eye research (Review). Mol Med Rep 2017; 15:3923-3935. [PMID: 28487982 DOI: 10.3892/mmr.2017.6529] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 02/22/2017] [Indexed: 02/05/2023] Open
Abstract
Gene expression is the process by which genetic information is used for the synthesis of a functional gene product, and ultimately regulates cell function. The increase of biological complexity from genome to proteome is vast, and the post-translational modification (PTM) of proteins contribute to this complexity. The study of protein expression and PTMs has attracted attention in the post‑genomic era. Due to the limited capability of conventional biochemical techniques in the past, large‑scale PTM studies were technically challenging. The introduction of effective protein separation methods, specific PTM purification strategies and advanced mass spectrometers has enabled the global profiling of PTMs and the identification of a targeted PTM within the proteome. The present review provides an overview of current proteomic technologies being applied in eye research, with a particular focus on studies of PTMs in ocular tissues and ocular diseases.
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Affiliation(s)
- Bing-Jie Chen
- Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Thomas Chuen Lam
- Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR, P.R. China
| | - Long-Qian Liu
- Department of Optometry and Visual Science, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Chi-Ho To
- Laboratory of Experimental Optometry, Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR, P.R. China
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13
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Corfield A. Eukaryotic protein glycosylation: a primer for histochemists and cell biologists. Histochem Cell Biol 2017; 147:119-147. [PMID: 28012131 PMCID: PMC5306191 DOI: 10.1007/s00418-016-1526-4] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2016] [Indexed: 12/21/2022]
Abstract
Proteins undergo co- and posttranslational modifications, and their glycosylation is the most frequent and structurally variegated type. Histochemically, the detection of glycan presence has first been performed by stains. The availability of carbohydrate-specific tools (lectins, monoclonal antibodies) has revolutionized glycophenotyping, allowing monitoring of distinct structures. The different types of protein glycosylation in Eukaryotes are described. Following this educational survey, examples where known biological function is related to the glycan structures carried by proteins are given. In particular, mucins and their glycosylation patterns are considered as instructive proof-of-principle case. The tissue and cellular location of glycoprotein biosynthesis and metabolism is reviewed, with attention to new findings in goblet cells. Finally, protein glycosylation in disease is documented, with selected examples, where aberrant glycan expression impacts on normal function to let disease pathology become manifest. The histological applications adopted in these studies are emphasized throughout the text.
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Affiliation(s)
- Anthony Corfield
- Mucin Research Group, School of Clinical Sciences, Bristol Royal Infirmary, University of Bristol, Bristol, BS2 8HW, UK.
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14
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Uchino Y, Woodward AM, Argüeso P. Differential effect of rebamipide on transmembrane mucin biosynthesis in stratified ocular surface epithelial cells. Exp Eye Res 2016; 153:1-7. [PMID: 27725198 DOI: 10.1016/j.exer.2016.10.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 09/29/2016] [Accepted: 10/06/2016] [Indexed: 10/20/2022]
Abstract
Mucins are a group of highly glycosylated glycoproteins responsible for the protection of wet-surfaced epithelia. Recent data indicate that transmembrane mucins differ in their contribution to the protective function of the ocular surface, with MUC16 being the most effective barrier on the apical surface glycocalyx. Here, we investigated the role of the mucoprotective drug rebamipide in the regulation of transmembrane mucin biosynthesis using stratified cultures of human corneal and conjunctival epithelial cells. We find that the addition of rebamipide to corneal, but not conjunctival, epithelial cells increased MUC16 protein biosynthesis. Rebamipide did not affect the levels of MUC1, 4 and 20 compared to control. In these experiments, rebamipide had no effect on the expression levels of Notch intracellular domains, suggesting that the rebamipide-induced increase in MUC16 biosynthesis in differentiated corneal cultures is not regulated by Notch signaling. Overall these findings indicate that rebamipide induces the differential upregulation of MUC16 in stratified cultures of human corneal epithelial cells, which may have implications to the proper restoration of barrier function in ocular surface disease.
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Affiliation(s)
- Yuichi Uchino
- Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
| | - Ashley M Woodward
- Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
| | - Pablo Argüeso
- Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
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15
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Epidemic Keratoconjunctivitis-Causing Adenoviruses Induce MUC16 Ectodomain Release To Infect Ocular Surface Epithelial Cells. mSphere 2016; 1:mSphere00112-15. [PMID: 27303700 PMCID: PMC4863608 DOI: 10.1128/msphere.00112-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 01/13/2016] [Indexed: 01/26/2023] Open
Abstract
Human adenoviruses (HAdVs) are double-stranded DNA viruses that cause infections across all mucosal tissues in the body. At the ocular surface, HAdVs cause keratoconjunctivitis (E. Ford, K. E. Nelson, and D. Warren, Epidemiol Rev 9:244–261, 1987, and C. M. Robinson, D. Seto, M. S. Jones, D. W. Dyer, and J. Chodosh, Infect Genet Evol 11:1208–1217, 2011, doi:10.1016/j.meegid.2011.04.031)—a highly contagious infection that accounts for nearly 60% of conjunctivitis cases in the United States (R. P. Sambursky, N. Fram, and E. J. Cohen, Optometry 78:236–239, 2007, doi:10.1016/j.optm.2006.11.012, and A. M. Pihos, J Optom 6:69–74, 2013, doi:10.1016/j.optom.2012.08.003). The infection begins with HAdV entry within ocular surface epithelial cells; however, the mechanisms used by HAdVs to transit the otherwise protective mucosal barrier of ocular surface epithelial cells prior to entry remain unknown. Here, we report that the highly virulent keratoconjunctivitis-causing HAdV-D37 induces release of the extracellular domain (ectodomain) of MUC16, a major component of the mucosal barrier of ocular surface epithelial cells, prior to infecting underlying cells. Currently, there is no specific treatment for controlling this infection. Understanding the early steps involved in the pathogenesis of keratoconjunctivitis and using this information to intercept adenoviral entry within cells may guide the development of novel strategies for controlling the infection. Human adenoviruses (HAdV), species D in particular (HAdV-D), are frequently associated with epidemic keratoconjunctivitis (EKC). Although the infection originates at the ocular surface epithelium, the mechanisms by which HAdV-Ds bypass the membrane-associated mucin (MAM)-rich glycocalyx of the ocular surface epithelium to trigger infection and inflammation remain unknown. Here, we report that an EKC-causing adenovirus (HAdV-D37), but not a non-EKC-causing one (HAdV-D19p), induces ectodomain release of MUC16—a MAM with barrier functions at the ocular surface—from cultured human corneal and conjunctival epithelial cells. HAdV-D37, but not HAdV-D19p, is also found to decrease the glycocalyx barrier function of corneal epithelial cells, as determined by rose bengal dye penetrance assays. Furthermore, results from quantitative PCR (qPCR) amplification of viral genomic DNA using primers specific to a conserved region of the E1B gene show that, in comparison to infection by HAdV-D19p, infection by HAdV-D37 is significantly increased in corneal epithelial cells. Collectively, these results point to a MUC16 ectodomain release-dependent mechanism utilized by the EKC-causing HAdV-D37 to initiate infection at the ocular surface. These findings are important in terms of understanding the pathogenesis of adenoviral keratoconjunctivitis. Similar MAM ectodomain release mechanisms may be prevalent across other mucosal epithelia in the body (e.g., the airway epithelium) that are prone to adenoviral infection. IMPORTANCE Human adenoviruses (HAdVs) are double-stranded DNA viruses that cause infections across all mucosal tissues in the body. At the ocular surface, HAdVs cause keratoconjunctivitis (E. Ford, K. E. Nelson, and D. Warren, Epidemiol Rev 9:244–261, 1987, and C. M. Robinson, D. Seto, M. S. Jones, D. W. Dyer, and J. Chodosh, Infect Genet Evol 11:1208–1217, 2011, doi:10.1016/j.meegid.2011.04.031)—a highly contagious infection that accounts for nearly 60% of conjunctivitis cases in the United States (R. P. Sambursky, N. Fram, and E. J. Cohen, Optometry 78:236–239, 2007, doi:10.1016/j.optm.2006.11.012, and A. M. Pihos, J Optom 6:69–74, 2013, doi:10.1016/j.optom.2012.08.003). The infection begins with HAdV entry within ocular surface epithelial cells; however, the mechanisms used by HAdVs to transit the otherwise protective mucosal barrier of ocular surface epithelial cells prior to entry remain unknown. Here, we report that the highly virulent keratoconjunctivitis-causing HAdV-D37 induces release of the extracellular domain (ectodomain) of MUC16, a major component of the mucosal barrier of ocular surface epithelial cells, prior to infecting underlying cells. Currently, there is no specific treatment for controlling this infection. Understanding the early steps involved in the pathogenesis of keratoconjunctivitis and using this information to intercept adenoviral entry within cells may guide the development of novel strategies for controlling the infection.
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Gipson IK, Spurr-Michaud S, Tisdale A. Human conjunctival goblet cells express the membrane associated mucin MUC16: Localization to mucin granules. Exp Eye Res 2015; 145:230-234. [PMID: 26731719 DOI: 10.1016/j.exer.2015.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 10/22/2022]
Abstract
MUC16 is an extraordinarily large 22,152 amino acid membrane spanning mucin that has been shown to be present in the glycocalyx of the apical cells of the human cornea and conjunctiva where it interfaces with the tear film. The ectodomain of the molecule has been demonstrated in tears, where it has been presumed to be from surface epithelial cells. Data presented here from multiple assays, including immunohistochemistry, immunoelectron microscopy, in situ hybridization, and RT-PCR of RNA isolated from goblet cells isolated by laser capture microdissection, demonstrate that the membrane tethered mucin is also expressed by conjunctival goblet cells both in humans and in mice. The mucin is present in mucin granules and appears to be localized to the mucin granule membrane. Correlation analyses of the amounts of the goblet cell secreted mucin MUC5AC and the amounts of MUC16 and of MUC1 another membrane tethered mucin ectodomain found in human tear samples demonstrated that MUC5AC amounts correlated to the amounts of MUC16 but not to MUC1. These data suggest that goblet cells are a second source of the mucin in tears. The function of the membrane tethered mucin in the mucin granule remains to be determined.
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Affiliation(s)
- Ilene K Gipson
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston MA, USA.
| | - Sandra Spurr-Michaud
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston MA, USA
| | - Ann Tisdale
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston MA, USA
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Bron A, Argüeso P, Irkec M, Bright F. Clinical staining of the ocular surface: Mechanisms and interpretations. Prog Retin Eye Res 2015; 44:36-61. [DOI: 10.1016/j.preteyeres.2014.10.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 10/24/2022]
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Comparison of the transmembrane mucins MUC1 and MUC16 in epithelial barrier function. PLoS One 2014; 9:e100393. [PMID: 24968021 PMCID: PMC4072602 DOI: 10.1371/journal.pone.0100393] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 05/25/2014] [Indexed: 01/09/2023] Open
Abstract
Membrane-anchored mucins are present in the apical surface glycocalyx of mucosal epithelial cells, each mucosal epithelium having at least two of the mucins. The mucins have been ascribed barrier functions, but direct comparisons of their functions within the same epithelium have not been done. In an epithelial cell line that expresses the membrane-anchored mucins, MUC1 and MUC16, the mucins were independently and stably knocked down using shRNA. Barrier functions tested included dye penetrance, bacterial adherence and invasion, transepithelial resistance, tight junction formation, and apical surface size. Knockdown of MUC16 decreased all barrier functions tested, causing increased dye penetrance and bacterial invasion, decreased transepithelial resistance, surprisingly, disruption of tight junctions, and greater apical surface cell area. Knockdown of MUC1 did not decrease barrier function, in fact, barrier to dye penetrance and bacterial invasion increased significantly. These data suggest that barrier functions of membrane-anchored mucins vary in the context of other membrane mucins, and MUC16 provides a major barrier when present.
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Iwatsuka K, Iwamoto H, Kinoshita M, Inada K, Yasueda SI, Kakehi K. Comparative Studies ofN-Glycans and Glycosaminoglycans Present in SIRC (Statens Seruminstitut Rabbit Cornea) Cells and Corneal Epithelial Cells from Rabbit Eyes. Curr Eye Res 2014; 39:686-94. [DOI: 10.3109/02713683.2013.863940] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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The use of sialidase therapy for respiratory viral infections. Antiviral Res 2013; 98:401-9. [PMID: 23602850 PMCID: PMC7172378 DOI: 10.1016/j.antiviral.2013.04.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 03/29/2013] [Accepted: 04/11/2013] [Indexed: 01/16/2023]
Abstract
DAS181 is a novel inhaled therapy for the treatment of influenza. Treatment targets sialic acid on the cell surface. The sialidase removes both α2-3 and α2-6 linked sialic acids. The use of an amphiregulin tag to the sialidase anchors it to the cell surface. Treatment for 3 days appears effective in treating influenza and parainfluenza.
DAS181 is an inhaled bacterial sialidase which functions by removing sialic acid (Sia) from the surface of epithelial cells, preventing attachment and subsequent infection by respiratory viruses that utilize Sia as a receptor. DAS181 is typical of bacterial sialidases in cleaving Sia α2-3 and Sia α2-6 linkages, and it also has a demonstrated effect against acetylated and hydroxylated forms of Sia. The potency of the compound has been enhanced by coupling the active sialidase with an amphiregulin tag, allowing a longer duration of action and minimizing spread to the systemic circulation. DAS181 is now in Phase II development for the treatment of influenza, and it has also demonstrated activity in individual cases of parainfluenza in immunosuppressed patients. Continued evaluation of the roles and activities of bacterial sialidases is required to expand the range of successful antiviral therapies targeting Sia or its derivatives.
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Argüeso P. Glycobiology of the ocular surface: mucins and lectins. Jpn J Ophthalmol 2013; 57:150-5. [PMID: 23325272 DOI: 10.1007/s10384-012-0228-2] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 12/02/2012] [Indexed: 11/28/2022]
Abstract
Glycosylation is an important and common form of posttranscriptional modification of proteins in cells. During the last decade, a vast array of biological functions has been ascribed to glycans because of a rapid evolution in glycomic technologies. Glycogenes that are highly expressed at the human ocular surface include families of glycosyltransferases, proteoglycans, and glycan degradation proteins, as well as mucins and carbohydrate-binding proteins, such as the galectins. On the apical glycocalyx, mucin O-glycans promote boundary lubrication, prevent bacterial adhesion and endocytic activity, and maintain epithelial barrier function through interactions with galectins. The emerging roles attributed to glycans are contributing to the appreciation of their biological capabilities at the ocular surface.
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Affiliation(s)
- Pablo Argüeso
- Schepens Eye Research Institute and Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA.
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Abstract
Sialic acids have a pivotal functional impact in many biological interactions such as virus attachment, cellular adhesion, regulation of proliferation, and apoptosis. A common modification of sialic acids is O-acetylation. O-Acetylated sialic acids occur in bacteria and parasites and are also receptor determinants for a number of viruses. Moreover, they have important functions in embryogenesis, development, and immunological processes. O-Acetylated sialic acids represent cancer markers, as shown for acute lymphoblastic leukemia, and they are known to play significant roles in the regulation of ganglioside-mediated apoptosis. Expression of O-acetylated sialoglycans is regulated by sialic acid-specific O-acetyltransferases and O-acetylesterases. Recent developments in the identification of the enigmatic sialic acid-specific O-acetyltransferase are discussed.
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Affiliation(s)
- Chitra Mandal
- Cancer and Cell Biology, Council of Scientific and Industrial Research - Indian Institute of Chemical Biology, 4 Raja S.C. Mallick Road, Kolkata, 700 032 India
| | - Reinhard Schwartz-Albiez
- Department of Translational Immunology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Reinhard Vlasak
- Department of Molecular Biology, University Salzburg, Billrothstr 11, 5020 Salzburg, Austria
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Assessing mucin expression and function in human ocular surface epithelia in vivo and in vitro. Methods Mol Biol 2012; 842:313-25. [PMID: 22259145 DOI: 10.1007/978-1-61779-513-8_19] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mucins of the corneal and conjunctival epithelia are necessary for the protection of the ocular surface against desiccation, pathogen access, and injury. Detection and quantification of mucins is important for the understanding of ocular surface diseases that cause impaired vision and, in advanced stages, blindness. Advances in the field of molecular biology have made it possible to study membrane mucins and their associated O-glycans in established cell culture models of human ocular surface epithelia. This chapter discusses procedures to detect and quantify mucin RNA and protein in biological samples, as well as methods to experimentally manipulate the epithelia in culture by shRNA, to understand the function of specific mucins. Example protocols are provided to evaluate the role of ocular surface mucins in mucosal barrier function and bacteria-host interactions.
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Gipson IK, Spurr-Michaud SJ, Senchyna M, Ritter R, Schaumberg D. Comparison of mucin levels at the ocular surface of postmenopausal women with and without a history of dry eye. Cornea 2011; 30:1346-52. [PMID: 22089171 PMCID: PMC3219908 DOI: 10.1097/ico.0b013e31820d852a] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine if levels of the glycocalyx membrane mucins, MUC1 and MUC16, and the secreted goblet cell mucin MUC5AC are altered in conjunctival cells and tears of postmenopausal women presenting with a history of non-Sjögren dry eye and if mucin levels correlate with dry eye clinical diagnostic data. METHODS Eighty-four postmenopausal women with a history of non-Sjögren dry eye and 30 normal subjects were recruited for this study. Impression cytology samples were collected for mucin messenger RNA (mRNA) and protein analysis. Tears were collected for mucin protein assay. Quantitative polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay were used to quantitate MUC1, MUC16, and MUC5AC levels. RESULTS Postmenopausal women with a history of dry eye displayed significantly increased MUC1 mRNA expression and cellular protein compared with normal subjects (P < 0.001 and P < 0.01, respectively). Similarly, cellular MUC16 protein levels were significantly higher (P < 0.001). Mucin levels were found to be correlated with the clinical characterization of the subjects, including staining and symptoms. Although cellular MUC5AC protein levels were increased in symptomatic subjects, the increase did not reach statistical significance. CONCLUSIONS Elevation in MUC1 and MUC16 mRNA and/or protein levels in postmenopausal women with non-Sjögren dry eye with a history of dry eye may be a compensatory response to irritation and inflammation associated with the disease. Understanding the pattern of mucin expression associated with the dry eye pathology may clarify factors involved in the progression of the disease and enhance the development of targeted therapies.
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Affiliation(s)
- Ilene K Gipson
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
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Abstract
Marx's line is a line of mucosal staining behind the mucocutaneous junction. It can be demonstrated throughout life in all normal lids by staining with lissamine green and related dyes. Of all the body orifices, only the mucosae of the eye and mouth are directly exposed to the atmosphere. In this paper, we suggest that for the eye, this exposure leads to the formation of Marx's line. The tear meniscus thins progressively toward its apex, where it is pinned at the mucocutaneous junction of the lid. It also thins toward the black line, which segregates the meniscus from the tear film after the blink. We predict that, because of the geometry of the tear meniscus, evaporation generates a solute gradient across the meniscus profile in the anteroposterior plane, which peaks at the meniscus apices at the end of the interblink. One outcome would be to amplify the level of tear molarity at these sites so that they reach hyperosmolar proportions. Preliminary mathematical modeling suggests that dilution of this effect by advection and diffusion of solute away from the meniscus apex at the mucocutaneous junction will be restricted by spatial constraints, the presence of tear and surface mucins at this site, and limited fluid flow. We conclude that evaporative water loss from the tear meniscus may result in a physiological zone of hyperosmolar and related stresses to the occlusal conjunctiva, directly behind the mucocutaneous junction. We hypothesize that this stimulates a high epithelial cell turnover at this site, incomplete epithelial maturation, and a failure to express key molecules such as MUC 16 and galectin-3, which, with the tight junctions between surface epithelial cells, are necessary to seal the ocular surface and prevent penetration of dyes and other molecules into the epithelium. This is proposed as the basis for Marx's line. In Part II of this paper (also published in this issue of The Ocular Surface), we address additional pathophysiological consequences of this mechanism, affecting lid margins.
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Shahrokh Z, Royle L, Saldova R, Bones J, Abrahams JL, Artemenko NV, Flatman S, Davies M, Baycroft A, Sehgal S, Heartlein MW, Harvey DJ, Rudd PM. Erythropoietin Produced in a Human Cell Line (Dynepo) Has Significant Differences in Glycosylation Compared with Erythropoietins Produced in CHO Cell Lines. Mol Pharm 2010; 8:286-96. [DOI: 10.1021/mp100353a] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Zahra Shahrokh
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Louise Royle
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Radka Saldova
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Jonathan Bones
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Jodie L. Abrahams
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Natalia V. Artemenko
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Steve Flatman
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Mike Davies
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Alison Baycroft
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Surinder Sehgal
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Michael W. Heartlein
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - David J. Harvey
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
| | - Pauline M. Rudd
- Shire Human Genetic Therapies, Cambridge, MA, USA, Lonza Biologics, plc, Slough, U.K., NIBRT Dublin Oxford Glycobiology Laboratory, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland, and Glycobiology Institute, Department of Biochemistry, Oxford University, Oxford, U.K
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Lakhiari H, Boukir A, Muller D. New Thiophilic Adsorbent for the Purification of Insulin and Immunoglobulins G. Chromatographia 2010. [DOI: 10.1365/s10337-010-1657-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Milutinović B, Mitić N, Janković M. Identification of pregnancy-associated CA125-reactive protein as a carbohydrate-binding immunoglobulin G. Arch Biochem Biophys 2010; 499:69-76. [PMID: 20488159 DOI: 10.1016/j.abb.2010.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 05/12/2010] [Accepted: 05/13/2010] [Indexed: 11/26/2022]
Abstract
Cancer antigen 125 (CA125), also referred to as mucin 16, is expressed under both normal and pathological conditions and the complexity of its structure indicates multifunctionality, i.e. both the protein and carbohydrate parts may be involved in diverse interactions at different levels of cell and tissue organization. Its biological role is not understood, but involvement in immune response modulation and influence on cell adhesion have been speculated. This study aimed at isolation and characterization of endogenous ligands for CA125 as an initial step in gaining insight into its activity. A CA125-reactive fraction was separated from human placental extract by affinity chromatography. The isolated preparation was characterized by SDS-PAGE, immunoblotting, peptide mass fingerprinting and binding assay. The CA125-reactive fraction from placental extract was identified as carbohydrate-binding IgG. The glycan composition of inhibitors of carbohydrate-binding pointed to sialic acid as one determinant for recognition but indicated that sialylation was not alone and that glycotopes containing galactose, N-acetylgalactosamine and N-acetylglucosamine were also important. CA125-reactive IgG could be selectively enriched using fetuin as the ligand and represents a distinct IgG subfraction differing from abundant natural carbohydrate-binding antibodies. Taking advantage of the particular properties of ligands for CA125 may have biomedical potential for use as biological modifiers or delivery agents and have an impact beyond pregnancy, since many immunoregulatory molecular pathways are common to embryonic development and malignant transformation.
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Affiliation(s)
- Bojana Milutinović
- Department for Immunochemistry and Glycobiology, Institute for the Application of Nuclear Energy-INEP, University of Belgrade, Zemun-Belgrade, Serbia
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Glycoprofiling Investigation of Hepatocellular Carcinoma Cell Surface With Lectin Microarray*. PROG BIOCHEM BIOPHYS 2010. [DOI: 10.3724/sp.j.1206.2009.00622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Guzman-Aranguez A, Argüeso P. Structure and Biological Roles of Mucin-type O-glycans at the Ocular Surface. Ocul Surf 2010; 8:8-17. [DOI: 10.1016/s1542-0124(12)70213-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Guzman-Aranguez A, Mantelli F, Argüeso P. Mucin-type O-glycans in tears of normal subjects and patients with non-Sjögren's dry eye. Invest Ophthalmol Vis Sci 2009; 50:4581-7. [PMID: 19407012 PMCID: PMC2751810 DOI: 10.1167/iovs.09-3563] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE O-linked carbohydrates (O-glycans) contribute to the hydrophilic character of mucins in mucosal tissues. This study was conducted to identify the repertoire of O-glycans in the tear film and the glycosyltransferases associated with their biosynthesis, in normal subjects and patients with non-Sjögren's dry eye. METHODS Human tear fluid was collected from the inferior conjunctival fornix. O-glycans were released by hydrazinolysis, labeled with 2-aminobenzamide, and analyzed by fluorometric, high-performance liquid chromatography (HPLC) coupled with exoglycosidase digestions. O-glycan structures identified in tears were related to potential biosynthetic pathways in human conjunctival epithelium by using a glycogene microarray database. Lectin-binding analyses were performed with agglutinins from Arachis hypogaea, Maackia amurensis, and Sambucus nigra. RESULTS The O-glycan profile of human tears consisted primarily of core 1 (Gal beta 1-3GalNAc alpha 1-Ser/Thr)-based structures. Mono-sialyl O-glycans represented approximately 66% of the glycan pool, with alpha2-6-sialyl core 1 being the predominant O-glycan structure in human tears (48%). Four families of glycosyltransferases potentially related to the biosynthesis of these structures were identified in human conjunctiva. These included 13 polypeptide-GalNAc-transferases (GALNT), the core 1 beta-3-galactosyltransferase (T-synthase), three alpha2-6-sialyltransferases (ST6GalNAc), and two alpha2-3-sialyltransferases (ST3Gal). No significant differences in total amount of O-glycans were detected between tears of normal subjects and patients with dry eye, by HPLC and lectin blot. Likewise, no differences in glycosyltransferase expression were found by glycogene microarray. CONCLUSIONS This study identified the most common mucin-type O-glycans in human tears and their expected biosynthetic pathways in ocular surface epithelia. Patients with non-Sjögren's dry eye showed no alterations in composition and amount of O-glycans in the tear fluid.
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Affiliation(s)
- Ana Guzman-Aranguez
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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Hüffmeier U, Lascorz J, Becker T, Schürmeier-Horst F, Magener A, Ekici AB, Endele S, Thiel CT, Thoma-Uszynski S, Mössner R, Reich K, Kurrat W, Wienker TF, Traupe H, Reis A. Characterisation of psoriasis susceptibility locus 6 (PSORS6) in patients with early onset psoriasis and evidence for interaction with PSORS1. J Med Genet 2009; 46:736-44. [PMID: 19525279 PMCID: PMC3272665 DOI: 10.1136/jmg.2008.065029] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Psoriasis is a genetically complex, chronic inflammatory skin disease. The authors have previously identified a susceptibility locus on chromosome 19p13 (PSORS6). METHODS AND RESULTS In a follow-up linkage disequilibrium (LD) study in an independent family based cohort, the authors found evidence for association to a newly discovered microsatellite at this locus (D19SPS21, p<5.3x10(-5)). An LD based association scan in 300 trios revealed association to several single, single nucleotide polymorphisms (SNPs) in one LD block. When the authors stratified this cohort for carrying the PSORS1 risk allele at the HLA-C locus, evidence for association became much stronger at single SNP and haplotype levels (p values between 1.0x10(-4) and 8.0x10(-4)). In a replication study of 1114 patients and 937 control individuals, evidence for association was also observed after stratification to the PSORS1 risk allele. In both study groups, logistic regression showed evidence for interaction between the risk alleles at PSORS1 and PSORS6. Best p values for rs12459358 in both study groups remained significant after correction for multiple testing. The associated LD block did not comprise any known genes. Interestingly, an adjacent gene, MUC16, coding for a large glycosylated protein expressed in epithelia and of unknown function, could be shown to be also expressed in tissues relevant for pathogenesis of psoriasis such as skin and thymus. Immunohistochemical analyses of skin revealed focal staining for MUC16 in suprabasal epidermal cells. Further functional studies are required to clarify its potential role in psoriasis and identify the causal variant(s) at this locus. CONCLUSION The data establish PSORS6 as a confirmed psoriasis susceptibility locus showing interaction with PSORS1.
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Affiliation(s)
- U Hüffmeier
- Institute of Human Genetics, University Hospital Erlangen, University of Erlangen-Nuremberg, 91054 Erlangen, Germany.
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Ricciuto J, Heimer SR, Gilmore MS, Argüeso P. Cell surface O-glycans limit Staphylococcus aureus adherence to corneal epithelial cells. Infect Immun 2008; 76:5215-20. [PMID: 18794288 PMCID: PMC2573382 DOI: 10.1128/iai.00708-08] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 07/30/2008] [Accepted: 09/03/2008] [Indexed: 11/20/2022] Open
Abstract
The mucin-rich environment of the intact corneal epithelium is thought to contribute to the prevention of Staphylococcus aureus infection. This study examined whether O-glycans, which constitute the majority of the mucin mass of epithelial cell glycocalyces, prevented bacterial adhesion and growth. Abrogation of mucin O glycosylation using the chemical primer benzyl-alpha-GalNAc resulted in increased adherence of parental strain RN6390 to apical human corneal-limbal epithelial (HCLE) cells and to biotinylated cell surface protein in static and liquid phase adhesion assays, consistent with a role of mucin O-glycans in preventing bacterial adhesion. Comparable results were found with ALC135, an isogenic mutant strain defective in the accessory gene regulators agr and sar, indicating that the agr- and/or sar-regulated virulence factors did not play a major role in mediating adhesion to the corneal cell surface after mucin O-glycan truncation. In exoglycosidase digestion studies, treatment with sialidase from Arthrobacter ureafaciens--which hydrolyzed mucin-associated O-acetyl sialic acid--but not from Clostridium perfringens resulted in an increase in RN6390 and ALC135 adhesion. Abrogation of mucin O glycosylation in HCLE cell cultures did not affect bacterial growth. Overall, these data indicate that mucin O-glycans contribute to the prevention of bacterial adherence to the apical surface of corneal epithelial cells and suggest that alteration of cell surface glycosylation from disease or trauma, including that stemming from contact lens wear, could contribute to a higher risk of infection.
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Affiliation(s)
- Jessica Ricciuto
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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Abstract
PURPOSE OF REVIEW The purpose of the present review is to describe new concepts on the role of mucins in the protection of corneal and conjunctival epithelia and to identify alterations of mucins in ocular surface diseases. RECENT FINDINGS New evidence indicates that gel-forming and cell surface-associated mucins contribute differently to the protection of the ocular surface against allergens, pathogens, extracellular molecules, abrasive stress, and drying. SUMMARY Mucins are high-molecular weight glycoproteins characterized by their extensive O-glycosylation. Major mucins expressed by the ocular surface epithelia include cell surface-associated mucins MUC1, MUC4, MUC16, and the gel-forming mucin MUC5AC. Recent advances using functional assays have allowed the examination of their roles in the protection of corneal and conjunctival epithelia. Alterations in mucin and mucin O-glycan biosynthesis in ocular surface disorders, including allergy, nonautoimmune dry eye, autoimmune dry eye, and infection, are presented.
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Affiliation(s)
- Flavio Mantelli
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
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Glycan structures of ocular surface mucins in man, rabbit and dog display species differences. Glycoconj J 2008; 25:763-73. [DOI: 10.1007/s10719-008-9136-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 04/02/2008] [Accepted: 04/03/2008] [Indexed: 01/22/2023]
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Sumiyoshi M, Ricciuto J, Tisdale A, Gipson IK, Mantelli F, Argüeso P. Antiadhesive character of mucin O-glycans at the apical surface of corneal epithelial cells. Invest Ophthalmol Vis Sci 2008; 49:197-203. [PMID: 18172093 PMCID: PMC2247472 DOI: 10.1167/iovs.07-1038] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Prolonged contact of opposite mucosal surfaces, which occurs on the ocular surface, oral cavity, reproductive tract, and gut, requires a specialized apical cell surface that prevents adhesion. The purpose of this study was to evaluate the contribution of mucin O-glycans to the antiadhesive character of human corneal-limbal epithelial (HCLE) cells. METHODS Mucin O-glycan biosynthesis in HCLE cells was disrupted by metabolic interference with benzyl-alpha-GalNAc. The cell surface mucin MUC16 and its carbohydrate epitope H185 were detected by immunofluorescence and Western blot. HCLE cell surface features were assessed by field emission scanning electron microscopy. Cell-cell adhesion assays were performed under static conditions and in a parallel plate laminar flow chamber. RESULTS Benzyl-alpha-GalNAc disrupted the biosynthesis of O-glycans without affecting apomucin biosynthesis or cell surface morphology. Static adhesion assays showed that the apical surface of differentiated HCLE cells expressing MUC16 and H185 was more antiadhesive than undifferentiated HCLE cells, which lacked MUC16. Abrogation of mucin O-glycosylation in differentiated cultures with benzyl-alpha-GalNAc resulted in increased adhesion of applied corneal epithelial cells and corneal fibroblasts. The antiadhesive effect of mucin O-glycans was further demonstrated by fluorescence video microscopy in dynamic flow adhesion assays. Cationized ferritin labeling of the cell surface indicated that anionic repulsion did not contribute to the antiadhesive character of the apical surface. CONCLUSIONS These results indicate that epithelial O-glycans contribute to the antiadhesive properties of cell surface-associated mucins in corneal epithelial cells and suggest that alterations in mucin O-glycosylation are involved in the pathology of drying mucosal diseases (e.g., dry eye).
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Affiliation(s)
- Mika Sumiyoshi
- Schepens Eye Research Institute and the Department of Ophthalmology, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
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Gipson IK. The ocular surface: the challenge to enable and protect vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2007; 48:4390; 4391-8. [PMID: 17898256 PMCID: PMC2886589 DOI: 10.1167/iovs.07-0770] [Citation(s) in RCA: 201] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Ilene K Gipson
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
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