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Wagner BA, Buettner GR. Stability of aqueous solutions of ascorbate for basic research and for intravenous administration. ADVANCES IN REDOX RESEARCH : AN OFFICIAL JOURNAL OF THE SOCIETY FOR REDOX BIOLOGY AND MEDICINE AND THE SOCIETY FOR FREE RADICAL RESEARCH-EUROPE 2023; 9:100077. [PMID: 37808406 PMCID: PMC10552410 DOI: 10.1016/j.arres.2023.100077] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Ascorbate (vitamin C) can rapidly oxidize in many near-neutral pH, aqueous solutions. We report on the stability of ascorbate solutions prepared for infusion into patients using standard pharmacy protocols, for example, 75 g of ascorbate/L in water for infusion. The concentration of ascorbate was monitored for changes over time using direct UV-Vis spectroscopy. The pH of the solution was about 5.7 with no significant change over 24 h. There was only an approximate loss of 1% per day over the first 3 days of storage. This information allows decisions on how far ahead of need such preparations can be made. We also provide laboratory approaches to minimize or control the rate of oxidation of ascorbate solutions for use in chemical and biochemical studies as well as preclinical animal studies. The goal is to have the amount of ascorbate intended to be used in experiments be the actual amount available.
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Affiliation(s)
- Brett A. Wagner
- Free Radical and Radiation Biology Program, ESR Facility, The University of Iowa, Iowa City, IA 52242, USA
| | - Garry R. Buettner
- Free Radical and Radiation Biology Program, ESR Facility, The University of Iowa, Iowa City, IA 52242, USA
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2
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Liu L, Liu L, Xie J, Shen M. Formation mechanism of AGEs in Maillard reaction model systems containing ascorbic acid. Food Chem 2022; 378:132108. [PMID: 35032811 DOI: 10.1016/j.foodchem.2022.132108] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/22/2021] [Accepted: 01/05/2022] [Indexed: 01/04/2023]
Abstract
The dietary advanced glycation end products (AGEs) contribute to the development of major chronic diseases. Maillard reactions are the main mechanism for AGEs formation but their formation involving ascorbic acid (AA) is far from being fully understood. This study investigated the effect of pH (6-10) and temperature (65, 100 and 120 ℃) on AGEs formation in three model systems: glucose (Glu) + lysine (Lys), AA + Lys and Glu + Lys + AA. In addition, the formation pathway of AGEs in Glu + Lys + AA model system was proposed by carbon module labeling (CAMOLA) technique. The results suggested alkaline environment can promote the production of N-carboxymethyllysine (CML) and N-carboxyethyllysine (CEL), but inhibit the production of pyrraline (Pyr). Meanwhile the high temperature favored AGEs formation. In the U-13C-Glu + Lys + AA model, AA produced glyoxal (GO), methylglyoxal (MGO), CML and CEL, which was significantly higher than with Glu alone. This study provides a theoretical basis for the formation mechanism of AGEs in the Maillard reaction involving AA.
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Affiliation(s)
- Lichun Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Lei Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Jianhua Xie
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Mingyue Shen
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
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3
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Fan X, Monnier VM. Protein posttranslational modification (PTM) by glycation: Role in lens aging and age-related cataractogenesis. Exp Eye Res 2021; 210:108705. [PMID: 34297945 DOI: 10.1016/j.exer.2021.108705] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 07/09/2021] [Accepted: 07/17/2021] [Indexed: 01/11/2023]
Abstract
Crystallins, the most prevalent lens proteins, have no turnover throughout the entire human lifespan. These long-lived proteins are susceptible to post-synthetic modifications, including oxidation and glycation, which are believed to be some of the primary mechanisms for age-related cataractogenesis. Thanks to high glutathione (GSH) and ascorbic acid (ASA) levels as well as low oxygen content, the human lens is able to maintain its transparency for several decades. Aging accumulates substantial changes in the human lens, including a decreased glutathione concentration, increased reactive oxygen species (ROS) formation, impaired antioxidative defense capacity, and increased redox-active metal ions, which induce glucose and ascorbic acid degradation and protein glycation. The glycated lens crystallins are either prone to UVA mediated free radical production or they attract metal ion binding, which can trigger additional protein oxidation and modification. This vicious cycle is expected to be exacerbated with older age or diabetic conditions. ASA serves as an antioxidant in the human lens under reducing conditions to protect the human lens from damage, but ASA converts to the pro-oxidative role and causes lens protein damage by ascorbylation in high oxidation or enriched redox-active metal ion conditions. This review is dedicated in honor of Dr. Frank Giblin, a great friend and superb scientist, whose pioneering and relentless work over the past 45 years has provided critical insight into lens redox regulation and glutathione homeostasis during aging and cataractogenesis.
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Affiliation(s)
- Xingjun Fan
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, United States.
| | - Vincent M Monnier
- Department of Pathology, United States; Biochemistry, Case Western Reserve University, Cleveland, OH, United States
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4
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Lim JC, Caballero Arredondo M, Braakhuis AJ, Donaldson PJ. Vitamin C and the Lens: New Insights into Delaying the Onset of Cataract. Nutrients 2020; 12:E3142. [PMID: 33066702 PMCID: PMC7602486 DOI: 10.3390/nu12103142] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 12/18/2022] Open
Abstract
Cataracts or clouding of the lens is the leading cause of blindness in the world. Age and diabetes are major risk factors, and with an increasing aging and diabetic population, the burden of cataracts will grow. Cataract surgery is an effective way to restore vision; however, alternatives to cataract surgery are required to reduce the looming cataract epidemic. Since it is well established that oxidative damage plays a major role in the etiology of cataracts, antioxidants have been promoted as therapies to delay and/or prevent cataracts. However, many antioxidant interventions including vitamin C have produced mixed results as anti-cataract therapies. Progress has been made towards our understanding of lens physiology and the mechanisms involved in the delivery and uptake of antioxidants to the lens which may guide future studies aimed at addressing some of the inconsistencies seen in previous animal and human studies. Of interest is the potential for vitamin C based supplements in delaying the onset of cataracts post vitrectomy which occurs in up to 80% of patients within two years. These targeted approaches are required to reduce the burden of cataract on hospitals and improve the quality of life of our aging and diabetic population.
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Affiliation(s)
- Julie C Lim
- Department of Physiology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1142, New Zealand;
| | - Mariana Caballero Arredondo
- Discipline of Nutrition, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1142, New Zealand; (M.C.A.); (A.J.B.)
| | - Andrea J. Braakhuis
- Discipline of Nutrition, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1142, New Zealand; (M.C.A.); (A.J.B.)
| | - Paul J. Donaldson
- Department of Physiology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland 1142, New Zealand;
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5
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Nandi SK, Nahomi RB, Rankenberg J, Glomb MA, Nagaraj RH. Glycation-mediated inter-protein cross-linking is promoted by chaperone-client complexes of α-crystallin: Implications for lens aging and presbyopia. J Biol Chem 2020; 295:5701-5716. [PMID: 32184356 PMCID: PMC7186181 DOI: 10.1074/jbc.ra120.012604] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 03/12/2020] [Indexed: 12/16/2022] Open
Abstract
Lens proteins become increasingly cross-linked through nondisulfide linkages during aging and cataract formation. One mechanism that has been implicated in this cross-linking is glycation through formation of advanced glycation end products (AGEs). Here, we found an age-associated increase in stiffness in human lenses that was directly correlated with levels of protein-cross-linking AGEs. α-Crystallin in the lens binds to other proteins and prevents their denaturation and aggregation through its chaperone-like activity. Using a FRET-based assay, we examined the stability of the αA-crystallin-γD-crystallin complex for up to 12 days and observed that this complex is stable in PBS and upon incubation with human lens-epithelial cell lysate or lens homogenate. Addition of 2 mm ATP to the lysate or homogenate did not decrease the stability of the complex. We also generated complexes of human αA-crystallin or αB-crystallin with alcohol dehydrogenase or citrate synthase by applying thermal stress. Upon glycation under physiological conditions, the chaperone-client complexes underwent greater extents of cross-linking than did uncomplexed protein mixtures. LC-MS/MS analyses revealed that the levels of cross-linking AGEs were significantly higher in the glycated chaperone-client complexes than in glycated but uncomplexed protein mixtures. Mouse lenses subjected to thermal stress followed by glycation lost resilience more extensively than lenses subjected to thermal stress or glycation alone, and this loss was accompanied by higher protein cross-linking and higher cross-linking AGE levels. These results uncover a protein cross-linking mechanism in the lens and suggest that AGE-mediated cross-linking of α-crystallin-client complexes could contribute to lens aging and presbyopia.
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Affiliation(s)
- Sandip K Nandi
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Rooban B Nahomi
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Johanna Rankenberg
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045
| | - Marcus A Glomb
- Institute of Chemistry-Food Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Ram H Nagaraj
- Sue Anschutz-Rodgers Eye Center and Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, Colorado 80045; Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado 80045.
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6
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Braakhuis AJ, Donaldson CI, Lim JC, Donaldson PJ. Nutritional Strategies to Prevent Lens Cataract: Current Status and Future Strategies. Nutrients 2019; 11:nu11051186. [PMID: 31137834 PMCID: PMC6566364 DOI: 10.3390/nu11051186] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/21/2019] [Accepted: 05/23/2019] [Indexed: 12/24/2022] Open
Abstract
Oxidative stress and the subsequent oxidative damage to lens proteins is a known causative factor in the initiation and progression of cataract formation, the leading cause of blindness in the world today. Due to the role of oxidative damage in the etiology of cataract, antioxidants have been prompted as therapeutic options to delay and/or prevent disease progression. However, many exogenous antioxidant interventions have to date produced mixed results as anti-cataract therapies. The aim of this review is to critically evaluate the efficacy of a sample of dietary and topical antioxidant interventions in the light of our current understanding of lens structure and function. Situated in the eye behind the blood-eye barrier, the lens receives it nutrients and antioxidants from the aqueous and vitreous humors. Furthermore, being a relatively large avascular tissue the lens cannot rely of passive diffusion alone to deliver nutrients and antioxidants to the distinctly different metabolic regions of the lens. We instead propose that the lens utilizes a unique internal microcirculation system to actively deliver antioxidants to these different regions, and that selecting antioxidants that can utilize this system is the key to developing novel nutritional therapies to delay the onset and progression of lens cataract.
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Affiliation(s)
- Andrea J Braakhuis
- Discipline of Nutrition, Faculty of Medical and Health Sciences, the University of Auckland, Auckland 1142, New Zealand.
| | - Caitlin I Donaldson
- Discipline of Nutrition, Faculty of Medical and Health Sciences, the University of Auckland, Auckland 1142, New Zealand.
| | - Julie C Lim
- Department of Physiology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, the University of Auckland, Auckland 1142, New Zealand.
| | - Paul J Donaldson
- Department of Physiology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, the University of Auckland, Auckland 1142, New Zealand.
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7
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Abstract
PURPOSE OF REVIEW To provide a comprehensive summary of the latest evidence-based data on nutrients linked to the pathogenesis of cataract formation and progression. RECENT FINDINGS This summary of peer-reviewed publications emphasizes the ongoing effort to modulate the cataractogenous process through nutrition, and points at an only weak evidence for the contribution of a specific nutrient to this process. Although observational studies successfully demonstrated a positive correlation between specific nutrients intake and age-related cataract, such evidence was usually lacking in following interventional studies. Three metanalyses point towards a beneficial effect of high intake of vitamin C, vitamin E and vitamin A on the risk of age-related cataract. New studies point at a protective effect of a high intake of vitamin K1 and vitamin D but negate the influence of Mediterranean diet or an overall high dairy consumption on the progression of cataract in a subgroup of patients. Sterols are candidate nutrients for future investigation. SUMMARY Nutrition rich in fruits and vegetables, and a high dietary intake of vitamins A, C, D, E and K1 may be inversely associated with the risk of age-related cataract. More studies involving patients in a wide range of nutritional status are required to establish the long-term benefit of nutritional supplements.
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8
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Hohmann C, Liehr K, Henning C, Fiedler R, Girndt M, Gebert M, Hulko M, Storr M, Glomb MA. Detection of Free Advanced Glycation End Products in Vivo during Hemodialysis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:930-937. [PMID: 28112514 DOI: 10.1021/acs.jafc.6b05013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Advanced glycation end products (AGEs) are often regarded as glycotoxins, which are normally removed by the kidney. Patients with end-stage renal failure rely on hemodialysis (HD) treatment to eliminate these compounds. In the present work, a highly selective LC-MS/MS method was used for quantitation of AGE levels in plasma and in dialysis fluids of HD patients, with a focus on AGE-free adducts. A broad range of 19 amino acid modifications was identified and quantitated. It was expected that the AGE-free adducts are successfully eliminated by dialysis treatment. Indeed, with a mean elimination rate of 71%, this assumption proved to be valid for all target analytes with the exception of pyrraline, which showed an opposite behavior. Here, plasma and dialysate levels increased during the treatment by about 59%. The notions that pyrraline was formed in high amounts in the patient's bloodstream (I) after intake of the corresponding precursor compound 3-deoxyglucosone with the dialysis fluid or (II) by catalytic effects on the formation by the dialysis membrane were ruled out. In contrast, in a dietary study, the comparison of pyrraline concentrations in plasma before and after food consumption confirmed that the increase in pyrraline originates solely from digestion of glycated food proteins. Additionally, by detailed analyses of the food consumed during dialysis sessions, bread rolls with a pyrraline content of about 21.7 μmol per serving were identified as the main source.
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Affiliation(s)
- Christoph Hohmann
- Institute of Chemistry, Food Chemistry, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
| | - Kristin Liehr
- Institute of Chemistry, Food Chemistry, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
| | - Christian Henning
- Institute of Chemistry, Food Chemistry, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
| | - Roman Fiedler
- Department of Internal Medicine II, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
| | - Matthias Girndt
- Department of Internal Medicine II, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
| | - Michael Gebert
- Department of Research and Development, Gambro Dialysatoren GmbH , Hechingen, Germany
| | - Michael Hulko
- Department of Research and Development, Gambro Dialysatoren GmbH , Hechingen, Germany
| | - Markus Storr
- Department of Research and Development, Gambro Dialysatoren GmbH , Hechingen, Germany
| | - Marcus A Glomb
- Institute of Chemistry, Food Chemistry, Martin-Luther-University Halle-Wittenberg , Halle/Salle, Germany
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9
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Rakete S, Nagaraj RH. UVA Light-mediated Ascorbate Oxidation in Human Lenses. Photochem Photobiol 2017; 93:1091-1095. [PMID: 28084012 DOI: 10.1111/php.12717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 12/05/2016] [Indexed: 12/11/2022]
Abstract
Whether ascorbate oxidation is promoted by UVA light in human lenses and whether this process is influenced by age and GSH levels are not known. In this study, we used paired lenses from human donors. One lens of each pair was exposed to UVA light, whereas the other lens was kept in the dark for the same period of time as the control. Using LC-MS/MS analyses, we found that older lenses (41-73 years) were more susceptible to UVA-induced ascorbate oxidation than younger lenses (18-40 years). Approximately 36% of the ascorbate (relative to control) was oxidized in older lenses compared to ~16% in younger lenses. Furthermore, lenses with higher levels of GSH were less susceptible to UVA-induced ascorbate oxidation compared to those with lower levels, and this effect was not dependent on age. The oxidation of ascorbate led to elevated levels of reactive α-dicarbonyl compounds. In summary, our study showed that UVA light exposure leads to ascorbate oxidation in human lenses and that such oxidation is more pronounced in aged lenses and is inversely related to GSH levels. Our findings suggest that UVA light exposure could lead to protein aggregation through ascorbate oxidation in human lenses.
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Affiliation(s)
- Stefan Rakete
- Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, CO
| | - Ram H Nagaraj
- Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, CO.,Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO
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10
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Conibear AC, Farbiarz K, Mayer RL, Matveenko M, Kählig H, Becker CFW. Arginine side-chain modification that occurs during copper-catalysed azide-alkyne click reactions resembles an advanced glycation end product. Org Biomol Chem 2016; 14:6205-11. [PMID: 27282129 DOI: 10.1039/c6ob00932h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dehydroascorbate is a by-product of copper-catalysed azide-alkyne click (CuAAC) reactions and also forms advanced glycation end products (AGEs) in tissues undergoing oxidative stress. Here we isolate and characterize an arginine-dehydroascorbate adduct formed during CuAAC reactions, investigate strategies for preventing its formation, and propose its biological relevance as an AGE.
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Affiliation(s)
- Anne C Conibear
- University of Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Straße 38, 1090 Vienna, Austria.
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11
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Rakete S, Nagaraj RH. Identification of Kynoxazine, a Novel Fluorescent Product of the Reaction between 3-Hydroxykynurenine and Erythrulose in the Human Lens, and Its Role in Protein Modification. J Biol Chem 2016; 291:9596-609. [PMID: 26941078 DOI: 10.1074/jbc.m116.716621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Indexed: 11/06/2022] Open
Abstract
Kynurenine pathway metabolites and ascorbate degradation products are present in human lenses. In this study, we showed that erythrulose, a major ascorbate degradation product, reacts spontaneously with 3-hydroxykynurenine to form a fluorescent product. Structural characterization of the product revealed it to be 2-amino-4-(2-hydroxy-3-(2-hydroxyethyl)-2H-benzo[b][1,4]oxazin-5-yl)-4-oxobutanoic acid, which we named kynoxazine. Unlike 3-hydroxykynurenine, 3-hydroxykynurenine glucoside and kynurenine were unable to form a kynoxazine-like compound, which suggested that the aminophenol moiety in 3-hydroxykynurenine is essential for the formation of kynoxazine. This reasoning was confirmed using a model compound, 1-(2-amino-3-hydroxyphenyl)ethan-1-one, which is an aminophenol lacking the amino acid moiety of 3-hydroxykynurenine. Ultra-performance liquid chromatography-tandem mass spectrometry analyses showed that kynoxazine is present in the human lens at levels ranging from 0 to 64 pmol/mg lens. Kynoxazine as well as erythrulose degraded under physiological conditions to generate 3-deoxythreosone, which modified and cross-linked proteins through the formation of an arginine adduct, 3-deoxythreosone-derived hydroimidazolone, and a lysine-arginine cross-linking adduct, 3-deoxythreosone-derived hydroimidazolimine cross-link. Ultra-performance liquid chromatography-tandem mass spectrometry quantification showed that 32-169 pmol/mg protein of 3-deoxythreosone-derived hydroimidazolone and 1.1-11.2 pmol/mg protein of 3-deoxythreosone-derived hydroimidazolimine cross-link occurred in aging lenses. Taken together, these results demonstrate a novel biochemical mechanism by which ascorbate oxidation and the kynurenine pathway intertwine, which could promote protein modification and cross-linking in aging human lenses.
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Affiliation(s)
- Stefan Rakete
- From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Ram H Nagaraj
- From the Department of Ophthalmology, University of Colorado School of Medicine, Aurora, Colorado 80045
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12
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Smuda M, Henning C, Raghavan CT, Johar K, Vasavada AR, Nagaraj RH, Glomb MA. Comprehensive analysis of maillard protein modifications in human lenses: effect of age and cataract. Biochemistry 2015; 54:2500-7. [PMID: 25849437 DOI: 10.1021/bi5013194] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In human lens proteins, advanced glycation endproducts (AGEs) originate from the reaction of glycating agents, e.g., vitamin C and glucose. AGEs have been considered to play a significant role in lens aging and cataract formation. Although several AGEs have been detected in the human lens, the contribution of individual glycating agents to their formation remains unclear. A highly sensitive liquid chromatography-tandem mass spectrometry multimethod was developed that allowed us to quantitate 21 protein modifications in normal and cataractous lenses, respectively. N(6)-Carboxymethyl lysine, N(6)-carboxyethyl lysine, N(7)-carboxyethyl arginine, methylglyoxal hydroimidazolone 1, and N(6)-lactoyl lysine were found to be the major Maillard protein modifications among these AGEs. The novel vitamin C specific amide AGEs, N(6)-xylonyl and N(6)-lyxonyl lysine, but also AGEs from glyoxal were detected, albeit in minor quantities. Among the 21 modifications, AGEs from the Amadori product (derived from the reaction of glucose and lysine) and methylglyoxal were dominant.
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Affiliation(s)
- Mareen Smuda
- †Institute of Chemistry-Food Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Christian Henning
- †Institute of Chemistry-Food Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle/Saale, Germany
| | - Cibin T Raghavan
- ‡Department of Ophthalmology and Visual Sciences, Case Western Reserve University School of Medicine, 2085 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Kaid Johar
- §Iladevi Cataract and IOL Research Center, Gurukul Road, Memnagar, Ahmedabad, Gujarat 380052, India
| | - Abhay R Vasavada
- §Iladevi Cataract and IOL Research Center, Gurukul Road, Memnagar, Ahmedabad, Gujarat 380052, India
| | - Ram H Nagaraj
- ‡Department of Ophthalmology and Visual Sciences, Case Western Reserve University School of Medicine, 2085 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Marcus A Glomb
- †Institute of Chemistry-Food Chemistry, Martin-Luther-University Halle-Wittenberg, 06120 Halle/Saale, Germany
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13
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Avila F, Friguet B, Silva E. Photosensitizing Activity of Endogenous Eye Lens Chromophores: An Attempt to Unravel Their Contributions to Photo-Aging and Cataract Disease. Photochem Photobiol 2015; 91:767-79. [DOI: 10.1111/php.12443] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/20/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Felipe Avila
- Escuela de Nutrición y Dietética; Facultad de Ciencias de la Salud; Universidad de Talca; Talca Chile
- Programa de Investigación de Excelencia Interdisciplinario en Envejecimiento Saludable (PIEI-ES); Universidad de Talca; Talca Chile
| | - Bertrand Friguet
- UPMC Univ. Paris 06; CNRS UMR 8256; INSERM U1164; Adaptation Biologique et Vieillissement; Institute of Biology Paris-Seine; Paris France
| | - Eduardo Silva
- Departamento de Química Física; Facultad de Química; Pontifícia Universidad Católica de Chile; Santiago Chile
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14
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Blair JA, McGee H, Bhatta S, Palm R, Casadesus G. Hypothalamic-pituitary-gonadal axis involvement in learning and memory and Alzheimer's disease: more than "just" estrogen. Front Endocrinol (Lausanne) 2015; 6:45. [PMID: 25859241 PMCID: PMC4373369 DOI: 10.3389/fendo.2015.00045] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/12/2015] [Indexed: 11/25/2022] Open
Abstract
Accumulating studies affirm the effects of age-related endocrine dysfunction on cognitive decline and increasing risk of neurodegenerative diseases. It is well known that estrogens can be protective for cognitive function, and more recently androgens and luteinizing hormone have also been shown to modulate learning and memory. Understanding the mechanisms underlying hypothalamic-pituitary-gonadal axis-associated cognitive dysfunction is crucial for therapeutic advancement. Here, we emphasize that reproductive hormones are influential in maintaining neuronal health and enhancing signaling cascades that lead to cognitive impairment. We summarize and critically evaluate age-related changes in the endocrine system, their implications in the development of Alzheimer's disease, and the therapeutic potential of endocrine modulation in the prevention of age-related cognitive decline.
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Affiliation(s)
- Jeffrey A. Blair
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Henry McGee
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Sabina Bhatta
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Russell Palm
- University of Toledo School of Medicine, Toledo, OH, USA
| | - Gemma Casadesus
- Department of Biological Sciences, Kent State University, Kent, OH, USA
- *Correspondence: Gemma Casadesus, Department of Biological Sciences, Kent State University, 256 Cunningham Hall, Kent, OH 44242, USA e-mail:
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15
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Argirov OK, Hubenova Y, Argirova MD. Application of solid-phase extraction for the concentration of chromophores, fluorophores, and photosensitizers from lens protein digests. J Sep Sci 2014; 37:3106-9. [DOI: 10.1002/jssc.201400285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 08/05/2014] [Accepted: 08/05/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Ognyan K. Argirov
- Mason Eye Institute; University of Missouri; Columbia MO USA
- Department of Organic Chemistry; Plovdiv University “Paisii Hilendarski”; Plovdiv Bulgaria
| | - Yolina Hubenova
- Department of Biochemistry and Microbiology; Plovdiv University “Paisii Hilendarski”; Plovdiv Bulgaria
| | - Mariana D. Argirova
- Department of Chemistry and Biochemistry; Medical University; Plovdiv Bulgaria
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16
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Linetsky M, Raghavan CT, Johar K, Fan X, Monnier VM, Vasavada AR, Nagaraj RH. UVA light-excited kynurenines oxidize ascorbate and modify lens proteins through the formation of advanced glycation end products: implications for human lens aging and cataract formation. J Biol Chem 2014; 289:17111-23. [PMID: 24798334 DOI: 10.1074/jbc.m114.554410] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Advanced glycation end products (AGEs) contribute to lens protein pigmentation and cross-linking during aging and cataract formation. In vitro experiments have shown that ascorbate (ASC) oxidation products can form AGEs in proteins. However, the mechanisms of ASC oxidation and AGE formation in the human lens are poorly understood. Kynurenines are tryptophan oxidation products produced from the indoleamine 2,3-dioxygenase (IDO)-mediated kynurenine pathway and are present in the human lens. This study investigated the ability of UVA light-excited kynurenines to photooxidize ASC and to form AGEs in lens proteins. UVA light-excited kynurenines in both free and protein-bound forms rapidly oxidized ASC, and such oxidation occurred even in the absence of oxygen. High levels of GSH inhibited but did not completely block ASC oxidation. Upon UVA irradiation, pigmented proteins from human cataractous lenses also oxidized ASC. When exposed to UVA light (320-400 nm, 100 milliwatts/cm(2), 45 min to 2 h), young human lenses (20-36 years), which contain high levels of free kynurenines, lost a significant portion of their ASC content and accumulated AGEs. A similar formation of AGEs was observed in UVA-irradiated lenses from human IDO/human sodium-dependent vitamin C transporter-2 mice, which contain high levels of kynurenines and ASC. Our data suggest that kynurenine-mediated ASC oxidation followed by AGE formation may be an important mechanism for lens aging and the development of senile cataracts in humans.
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Affiliation(s)
- Mikhail Linetsky
- From the Departments of Chemistry, Ophthalmology and Visual Sciences,
| | | | - Kaid Johar
- the Iladevi Cataract and IOL Research Center, Gurukul Road, Memnagar, Ahmedabad, Gujarat-380052, India
| | | | - Vincent M Monnier
- Pathology, and Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106 and
| | - Abhay R Vasavada
- the Iladevi Cataract and IOL Research Center, Gurukul Road, Memnagar, Ahmedabad, Gujarat-380052, India
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17
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Abstract
Lens opacification or cataract reduces vision in over 80 million people worldwide and blinds 18 million. These numbers will increase dramatically as both the size of the elderly demographic and the number of those with carbohydrate metabolism-related problems increase. Preventative measures for cataract are critical because the availability of cataract surgery in much of the world is insufficient. Epidemiologic literature suggests that the risk of cataract can be diminished by diets that are optimized for vitamin C, lutein/zeaxanthin, B vitamins, omega-3 fatty acids, multivitamins, and carbohydrates: recommended levels of micronutrients are salutary. The limited data from intervention trials provide some support for observational studies with regard to nuclear - but not other types of - cataracts. Presented here are the beneficial levels of nutrients in diets or blood and the total number of participants surveyed in epidemiologic studies since a previous review in 2007.
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Affiliation(s)
- Karen A Weikel
- Laboratory for Nutrition and Vision Research, JM-USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, USA
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18
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Kay P, Wagner JR, Gagnon H, Day R, Klarskov K. Modification of peptide and protein cysteine thiol groups by conjugation with a degradation product of ascorbate. Chem Res Toxicol 2013; 26:1333-9. [PMID: 23865753 DOI: 10.1021/tx400061e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Ascorbate is an important water-soluble antioxidant, which when oxidized by reactive oxygen species is converted into dehydroascorbate (DHA). If not rapidly reduced back to ascorbate, DHA decomposes to a reactive 5-carbon compound (DHA*, +130 Da) that can modify reduced cysteinyl residues in peptides and proteins in vitro. The formation of cysteine adducts by DHA* was characterized by mass spectrometry using reduced insulin B-chain, α-lactalbumin, and hemoglobin. Mass spectrometry of DHA* modified insulin B-chain revealed the presence of one and two DHA* adducts. Enzymatic cleavage and tandem mass spectrometry of modified peptides allowed unambiguous localization of DHA* to the two cysteine residues in positions 7 and 19 of the insulin B-chain. Incubations of DHA with α-lactalbumin revealed that approximately 25% of the protein population was in a reduced state and could be modified by DHA*. The adduct was assigned to the N-terminally located cysteinyl residue in position 6. Incubation of hemoglobin with DHA followed by pepsin digestion and electrospray ionization tandem mass spectrometry (ESI-MSMS) of the peptide mixture allowed for the identification of three modified peptides. Tandem mass spectrometry of the modified peptides, two from the hemoglobin A-chain with identical mass and one from the hemoglobin B-chain, gave a complete series of y-type fragment ions, which were assigned to the cysteine containing peptides (100)LLSHCL(105) (A-chain), (101)LSHCLL(106) (A-chain), and (111)VCVLAHHFGKE(121) (B-chain). Although the DHA* adduct was lost from the peptides derived from α-lactalbumin and hemoglobin before fragmentation of the peptide bond, carbamidomethylation of the proteins prior to incubation with DHA abolished the formation of DHA*-protein adducts and confirmed that the target was indeed the cysteine thiol group. Future studies are focused on the modification of proteins by DHA* in cells and in vivo.
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Affiliation(s)
- Phyla Kay
- Department of Pharmacology, ‡Department of Nuclear Medicine and Radiobiology, §Institut de pharmacologie de Sherbrooke and Department of Surgery/Urology division, Faculty of Medicine and Health Sciences, University of Sherbrooke , Sherbrooke, QC, Canada J1H 5N4
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19
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Zheng Selin J, Rautiainen S, Lindblad BE, Morgenstern R, Wolk A. High-dose supplements of vitamins C and E, low-dose multivitamins, and the risk of age-related cataract: a population-based prospective cohort study of men. Am J Epidemiol 2013; 177:548-55. [PMID: 23420353 DOI: 10.1093/aje/kws279] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We examined the associations of high-dose supplements of vitamins C and E and low-dose multivitamins with the risk of age-related cataract among 31,120 Swedish men, aged 45-79 years, in a population-based prospective cohort. Dietary supplement use was assessed from a questionnaire at baseline in 1998. During follow-up (January 1998-December 2006), 2,963 incident age-related cataract cases were identified. The multivariable-adjusted hazard ratio for men using vitamin C supplements only was 1.21 (95% confidence interval (CI): 1.04, 1.41) in a comparison with that of non-supplement users. The hazard ratio for long-term vitamin C users (≥10 years before baseline) was 1.36 (95% CI: 1.02, 1.81). The risk of cataract with vitamin C use was stronger among older men (>65 years) (hazard ratio = 1.92, 95% CI: 1.41, 2.60) and corticosteroid users (hazard ratio = 2.11, 95% CI: 1.48, 3.02). The hazard ratio for vitamin E use only was 1.59 (95% CI: 1.12, 2.26). Use of multivitamins only or multiple supplements in addition to vitamin C or E was not associated with cataract risk. These results suggest that the use of high-dose (but not low-dose) single vitamin C or E supplements may increase the risk of age-related cataract. The risk may be even higher among older men, corticosteroid users, and long-term users.
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Affiliation(s)
- Jinjin Zheng Selin
- Division of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
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20
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Ishikawa Y, Hashizume K, Kishimoto S, Tezuka Y, Nishigori H, Yamamoto N, Kondo Y, Maruyama N, Ishigami A, Kurosaka D. Effect of vitamin C depletion on UVR-B induced cataract in SMP30/GNL knockout mice. Exp Eye Res 2012; 94:85-9. [DOI: 10.1016/j.exer.2011.11.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 11/15/2011] [Accepted: 11/15/2011] [Indexed: 11/16/2022]
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21
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Kyselova Z. Mass spectrometry-based proteomics approaches applied in cataract research. MASS SPECTROMETRY REVIEWS 2011; 30:1173-1184. [PMID: 22031278 DOI: 10.1002/mas.20317] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 07/12/2010] [Accepted: 07/12/2010] [Indexed: 05/31/2023]
Abstract
Cataract, the opacification of the eye lens, is the leading cause of blindness worldwide--it accounts for approximately 42% of all cases. The lens fibers have the highest protein content within the body, more than 35% of their wet weight. Given the eye lens pure composition of highly abundant structural proteins crystallins (up to 90%), it seems to be an ideal proteomic entity to study and might be also hypothesized to model the other protein conformational diseases. Crystallins are extremely long-lived, and there is virtually no protein turnover. This provides great opportunities for post-translational modifications (PTM) to occur and to predispose lens to the cataract formation. Despite recent progress in proteomics, the human lens proteome remains largely unknown. Mass spectrometry hold great promise to determine which crystallin modifications lead to a cataract. Quantitative analysis of PTMs at the peptide level with proteomics is a powerful bioanalytical tool for lens-tissue samples, and provides more comprehensive results. New mass spectrometry-based approaches that are being applied to lens research will be highlighted. Finally, the future directions of proteomics cataract research will be outlined.
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Affiliation(s)
- Z Kyselova
- Laboratory of Cell Cultures, Institute of Experimental Pharmacology and Toxicology, Slovak Academy of Sciences, Dubravska cesta 9, SK, 841 04 Bratislava, Slovak Republic.
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22
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Nemet I, Monnier VM. Vitamin C degradation products and pathways in the human lens. J Biol Chem 2011; 286:37128-36. [PMID: 21885436 DOI: 10.1074/jbc.m111.245100] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vitamin C and its degradation products participate in chemical modifications of proteins in vivo through non-enzymatic glycation (Maillard reaction) and formation of different products called advanced glycation end products. Vitamin C levels are particularly high in selected tissues, such as lens, brain and adrenal gland, and its degradation products can inflict substantial protein damage via formation of advanced glycation end products. However, the pathways of in vivo vitamin C degradation are poorly understood. Here we have determined the levels of vitamin C oxidation and degradation products dehydroascorbic acid, 2,3-diketogulonic acid, 3-deoxythreosone, xylosone, and threosone in the human lens using o-phenylenediamine to trap both free and protein-bound adducts. In the protein-free fraction and water-soluble proteins (WSP), all five listed degradation products were identified. Dehydroascorbic acid, 2,3-diketogulonic acid, and 3-deoxythreosone were the major products in the protein-free fraction, whereas in the WSP, 3-deoxythreosone was the most abundant measured dicarbonyl. In addition, 3-deoxythreosone in WSP showed positive linear correlation with age (p < 0.05). In water-insoluble proteins, only 3-deoxythreosone and threosone were detected, whereby the level of 3-deoxythreosone was ∼20 times higher than the level of threosone. The identification of 3-deoxythreosone as the major degradation product bound to human lens proteins provides in vivo evidence for the non-oxidative pathway of dehydroascorbate degradation into erythrulose as a major pathway for vitamin C degradation in vivo.
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Affiliation(s)
- Ina Nemet
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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23
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Linetsky M, Kaid Johar SR, Meltretter J, Padmanabha S, Parmar T, Vasavada AR, Pischetsrieder M, Nagaraj RH. Determination of dideoxyosone precursors of AGEs in human lens proteins. Arch Biochem Biophys 2011; 514:16-26. [PMID: 21820400 DOI: 10.1016/j.abb.2011.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 07/19/2011] [Indexed: 11/18/2022]
Abstract
Dideoxyosones (DDOs) are intermediates in the synthesis of advanced glycation endproducts (AGEs), such as pentosidine and glucosepane. Although the formation of pentosidine and glucosepane in the human lens has been firmly established, the formation of DDOs has not been demonstrated. The aim of this study was to develop a reliable method to detect DDOs in lens proteins. A specific DDO trapping agent, biotinyl-diaminobenzene (3,4-diamino-N-(3-[5-(2-oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl)pentanoyl]aminopropyl)benzamide) (BDAB) was added during in vitro protein glycation or during protein extraction from human lenses. In vitro glycated human lens protein showed strong reaction in monomeric and polymeric crosslinked proteins by Western blot and ELISA. Glycation of BSA in the presence of BDAB resulted in covalent binding of BDAB to the protein and inhibited pentosidine formation. Mass spectrometric analysis of lysozyme glycated in the presence of BDAB showed the presence of quinoxalines at lysine residues at positions K1, K33, K96, and K116. The ELISA results indicated that cataractous lens proteins contain significantly higher levels of DDO than non-cataractous lenses (101.9±67.8 vs. 31.7±19.5AU/mg protein, p<0.0001). This study provides first direct evidence of DDO presence in human tissue proteins and establishes that AGE crosslink synthesis in the human lens occurs via DDO intermediates.
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Affiliation(s)
- Mikhail Linetsky
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, USA.
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24
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The pathogenic role of Maillard reaction in the aging eye. Amino Acids 2010; 42:1205-20. [DOI: 10.1007/s00726-010-0778-x] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 08/25/2010] [Indexed: 12/31/2022]
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25
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Avila F, Friguet B, Silva E. Simultaneous chemical and photochemical protein crosslinking induced by irradiation of eye lens proteins in the presence of ascorbate: the photosensitizing role of an UVA-visible-absorbing decomposition product of vitamin C. Photochem Photobiol Sci 2010; 9:1351-8. [PMID: 20734005 DOI: 10.1039/c0pp00048e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exposure to light has been implicated as a risk factor during aging of the eye lens and in cataract generation. In order to visualize the actual effect of UVA-visible light on this tissue, we incubated water-soluble eye lens proteins with ascorbate in the presence and absence of UVA-visible light for 3, 6 and 9 days at low oxygen concentration. The samples incubated in the presence of light were characterized by an initially small but continuous increase over time of the protein crosslinking. This was not the result of more extensive glycation because the decrease in amino group content of the proteins and the decomposition of ascorbate was the same in both irradiated and unirradiated samples. The augmented crosslinking capacity observed in the presence of UVA-visible light is due to the generation of a chromophore from the decomposition of ascorbate. This chromophore, obtained after 3, 6 and 9 days of incubation of solutions containing only ascorbate, induces both protein-crosslinking and oxidation after exposure to UVA-visible light in the presence of lens proteins. The extent of the crosslinking was proportional to the amount of the chromophore present in the solution. The presence of this chromophore was also determined when ascorbate was incubated with four-fold higher concentrations of N-α-acetyl lysine and N-α-acetyl arginine. When these samples were used as photosensitizers, the crosslinking degree was conditioned by the presence of this chromophore; nonetheless, the ascorbate-mediated advanced glycation end product (AGE) generation also made a contribution. The results of this work indicate that ascorbate oxidation, which generates the AGEs responsible for the chemical crosslinking of the lens proteins, also simultaneously produces a chromophore that can act as a photosensitizer, further increasing the protein crosslinking.
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Affiliation(s)
- Felipe Avila
- Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago de Chile
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26
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Rautiainen S, Lindblad BE, Morgenstern R, Wolk A. Vitamin C supplements and the risk of age-related cataract: a population-based prospective cohort study in women. Am J Clin Nutr 2010; 91:487-93. [PMID: 19923367 DOI: 10.3945/ajcn.2009.28528] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Experimental animal studies have shown adverse effects of high-dose vitamin C supplements on age-related cataract. OBJECTIVE We examined whether vitamin C supplements (approximately 1000 mg) and multivitamins containing vitamin C (approximately 60 mg) are associated with the incidence of age-related cataract extraction in a population-based, prospective cohort of women. DESIGN Our study included 24,593 women aged 49-83 y from the Swedish Mammography Cohort (follow-up from September 1997 to October 2005). We collected information on dietary supplement use and lifestyle factors with the use of a self-administrated questionnaire. Cataract extraction cases were identified by linkage to the cataract extraction registers in the geographical study area. RESULTS During the 8.2 y of follow-up (184,698 person-years), we identified 2497 cataract extraction cases. The multivariable hazard ratio (HR) for vitamin C supplement users compared with that for nonusers was 1.25 (95% CI: 1.05, 1.50). The HR for the duration of >10 y of use before baseline was 1.46 (95% CI: 0.93, 2.31). The HR for the use of multivitamins containing vitamin C was 1.09 (95% CI: 0.94, 1.25). Among women aged > or = 65 y, vitamin C supplement use increased the risk of cataract by 38% (95% CI: 12%, 69%). Vitamin C use among hormone replacement therapy users compared with that among nonusers of supplements or of hormone replacement therapy was associated with a 56% increased risk of cataract (95% CI: 20%, 102%). Vitamin C use among corticosteroid users compared with that among nonusers of supplements and corticosteroids was associated with an HR of 1.97 (95% CI: 1.35, 2.88). CONCLUSION Our results indicate that the use of vitamin C supplements may be associated with higher risk of age-related cataract among women.
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Affiliation(s)
- Susanne Rautiainen
- Divisions of Nutritional Epidemiology, Karolinska Institutet, Stockholm, Sweden
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27
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Sharma KK, Santhoshkumar P. Lens aging: effects of crystallins. Biochim Biophys Acta Gen Subj 2009; 1790:1095-108. [PMID: 19463898 DOI: 10.1016/j.bbagen.2009.05.008] [Citation(s) in RCA: 234] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2009] [Revised: 05/01/2009] [Accepted: 05/13/2009] [Indexed: 02/01/2023]
Abstract
The primary function of the eye lens is to focus light on the retina. The major proteins in the lens--alpha, beta, and gamma-crystallins--are constantly subjected to age-related changes such as oxidation, deamidation, truncation, glycation, and methylation. Such age-related modifications are cumulative and affect crystallin structure and function. With time, the modified crystallins aggregate, causing the lens to increasingly scatter light on the retina instead of focusing light on it and causing the lens to lose its transparency gradually and become opaque. Age-related lens opacity, or cataract, is the major cause of blindness worldwide. We review deamidation, and glycation that occur in the lenses during aging keeping in mind the structural and functional changes that these modifications bring about in the proteins. In addition, we review proteolysis and discuss recent observations on how crystallin fragments generated in vivo, through their anti-chaperone activity may cause crystallin aggregation in aging lenses. We also review hyperbaric oxygen treatment induced guinea pig and 'humanized' ascorbate transporting mouse models as suitable options for studies on age-related changes in lens proteins.
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Affiliation(s)
- K Krishna Sharma
- Department of Ophthalmology, University of Missouri-Columbia, 1 Hospital Drive, Columbia, MO 65212, USA.
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28
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Liquid-chromatographic and mass-spectrometric identification of lens proteins using microwave-assisted digestion with trypsin-immobilized magnetic nanoparticles. Biochem Biophys Res Commun 2009; 380:603-8. [PMID: 19285008 DOI: 10.1016/j.bbrc.2009.01.132] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 01/23/2009] [Indexed: 11/21/2022]
Abstract
We used a newly developed method combining trypsin-immobilized magnetic nanoparticles (TIMNs) and microwave-assisted protein digestion to study the proteins of human lens tissue. The digested proteins were identified by liquid chromatography and mass spectrometry. The lens proteins were digested under optimized conditions (digestion time 1 min, microwave power 400 W, trypsin-to-protein ratio 1:5) determined using bovine serum albumin as the standard protein, before liquid-chromatographic and mass-spectrometric analysis. Twenty-six proteins were identified with the new digestion method compared with 11 proteins identified with traditional in-solution digestion (12h). gamma-Crystallin, beta-crystallin, and superoxide dismutase 1 proteins, identified with the microwave-assisted method but not the traditional method, are related to cataract development according to some studies. The TIMNs were easily separated from the digestion products. This new digestion method could prove extremely useful for large-scale proteomic analyses.
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29
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Pournamdari M, Saadi A, Ellis E, Andrew R, Walker B, Watson DG. Development of a derivatisation method for the analysis of aldehyde modified amino acid residues in proteins by Fourier transform mass spectrometry. Anal Chim Acta 2008; 633:216-22. [PMID: 19166725 DOI: 10.1016/j.aca.2008.11.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 11/15/2008] [Accepted: 11/24/2008] [Indexed: 01/22/2023]
Abstract
A method was developed for the analysis of amino acids within bovine serum albumin (BSA) which had been modified by reaction with different enals. BSA was reacted with the aldehydes and the reaction products were stabilised by reaction with NaBH(4). The protein was then hydrolysed with 6N HCl and the hydrolysis products were analysed by liquid chromatography-mass spectrometry (LC-MS). The modified amino acids were derivatised with propylchloroformate. High resolution mass spectrometry carried out using an LTQ-Orbitrap instrument which was able to characterise a wide range of adducts. In addition double adducts were observed to be formed with 4-hydroxynonenal (HNE) and lysine or lysine+histidine. Qualitatively it was possible to consistently observe a pyridinium adduct formed between lysine and pentenal in human plasma from normal subjects.
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Affiliation(s)
- Mostafa Pournamdari
- Strathclyde Institute for Pharmacy and Biomedical Science (SIPBS), 27 Taylor Street, Glasgow G4 0NR, United Kingdom
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30
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Fan X, Monnier VM. Vitamin C-mediated Maillard reaction in the lens probed in a transgenic-mouse model. Ann N Y Acad Sci 2008; 1126:194-200. [PMID: 18448816 DOI: 10.1196/annals.1433.064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Aging human lens crystallins are progressively modified by yellow glycation, oxidation, and cross-linked carbonyl compounds that have deleterious properties on protein structure and stability. In order to test the hypothesis that some of these compounds originate from oxidized vitamin C, we have overexpressed the human vitamin C transporter 2 (hSCVT2) in the mouse lens. We find that levels of ascorbic and dehydroascorbic acid are highly elevated compared to the wild type and that the lenses have accumulated yellow color and advanced Maillard reaction products identical with those of the human lens. Treatment of the mice with nucleophilic inhibitors can slow down the process, opening new avenues for the pharmacological prevention of senile cataractogenesis.
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Affiliation(s)
- Xingjun Fan
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
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31
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Linetsky M, Shipova E, Cheng R, Ortwerth BJ. Glycation by ascorbic acid oxidation products leads to the aggregation of lens proteins. Biochim Biophys Acta Mol Basis Dis 2007; 1782:22-34. [PMID: 18023423 DOI: 10.1016/j.bbadis.2007.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2007] [Revised: 10/03/2007] [Accepted: 10/10/2007] [Indexed: 11/30/2022]
Abstract
Previous studies from this laboratory have shown that there are striking similarities between the yellow chromophores, fluorophores and modified amino acids released by proteolytic digestion from calf lens proteins ascorbylated in vitro and their counterparts isolated from aged and cataractous lens proteins. The studies reported in this communication were conducted to further investigate whether ascorbic acid-mediated modification of lens proteins could lead to the formation of lens protein aggregates capable of scattering visible light, similar to the high molecular aggregates found in aged human lenses. Ascorbic acid, but not glucose, fructose, ribose or erythrulose, caused the aggregation of calf lens proteins to proteins ranging from 2.2 x 10(6) up to 3.0 x 10(8 )Da. This compared to proteins ranging from 1.8 x 10(6) up to 3.6 x 10(8 )Da for the water-soluble (WS) proteins isolated from aged human lenses. This aggregation was likely due to the glycation of lens crystallins because [U-(14)C] ascorbate was incorporated into the aggregate fraction and because NaCNBH(3), which reduces the initial Schiff base, prevented any protein aggregation. Reactions of ascorbate with purified crystallin fractions showed little or no aggregation of alpha-crystallin, significant aggregation of beta(H)-crystallin, but rapid precipitation of purified beta(L)- and gamma-crystallin. The aggregation of lens proteins can be prevented by the binding of damaged crystallins to alpha-crystallin due to its chaperone activity. Depending upon the ratios between the components of the incubation mixtures, alpha-crystallin prevented the precipitation of the purified beta(L)- and gamma-crystallin fractions during ascorbylation. The addition of at least 20% of alpha-crystallin by weight into glycation mixtures with beta(L)-, or gamma-crystallins completely inhibited protein precipitation, and increased the amount of the high molecular weight aggregates in solution. Static and dynamic light scattering measurements of the supernatants from the ascorbic acid-modified mixtures of alpha- and beta(L)-, or gamma-crystallins showed similar molar masses (up to 10(8 )Da) and hydrodynamic diameter (up to 80( )nm). These data support the hypothesis, that if the lens reducing environment is compromised, the ascorbylation of lens crystallins can significantly change the short range interactions between different classes of crystallins leading to protein aggregation, light scattering and eventually to senile cataract formation.
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32
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Puttaiah S, Biswas A, Staniszewska M, Nagaraj RH. Methylglyoxal inhibits glycation-mediated loss in chaperone function and synthesis of pentosidine in α-crystallin. Exp Eye Res 2007; 84:914-21. [PMID: 17368444 DOI: 10.1016/j.exer.2007.01.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Revised: 12/19/2006] [Accepted: 01/18/2007] [Indexed: 11/30/2022]
Abstract
Alpha-crystallin is a major protein in the eye lens and it functions as a molecular chaperone by preventing aggregation of mildly denatured proteins. Glycation, the reaction of sugars and ascorbate with proteins, causes covalent cross-linking and reduces the chaperone function of alpha-crystallin. We demonstrated that methylglyoxal (MGO), a metabolic alpha-dicarbonyl compound, modifies arginine residues in alpha-crystallin and enhances its chaperone function. We wanted to determine whether modification by MGO could protect alpha-crystallin from glycation-mediated cross-linking and loss of chaperone function. Our results show that MGO-modification of isolated bovine lens alpha-crystallin inhibits formation of pentosidine, a glycation-derived protein crosslink. Proteins in organ cultured rat lenses were similarly protected from pentosidine formation. Glycation by sugars and ascorbate resulted in almost complete loss of chaperone function of alpha-crystallin. Surprisingly, addition of MGO during or before glycation not only inhibited the loss of chaperone function, but it actually enhanced the chaperone function of alpha-crystallin. Together, these data suggest that in the aging lens, MGO inhibits glycation-mediated pentosidine synthesis and the loss of chaperone function of alpha-crystallin.
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Current literature in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:266-277. [PMID: 17262881 DOI: 10.1002/jms.1071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Fan X, Reneker LW, Obrenovich ME, Strauch C, Cheng R, Jarvis SM, Ortwerth BJ, Monnier VM. Vitamin C mediates chemical aging of lens crystallins by the Maillard reaction in a humanized mouse model. Proc Natl Acad Sci U S A 2006; 103:16912-7. [PMID: 17075057 PMCID: PMC1636553 DOI: 10.1073/pnas.0605101103] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Senile cataracts are associated with progressive oxidation, fragmentation, cross-linking, insolubilization, and yellow pigmentation of lens crystallins. We hypothesized that the Maillard reaction, which leads browning and aroma development during the baking of foods, would occur between the lens proteins and the highly reactive oxidation products of vitamin C. To test this hypothesis, we engineered a mouse that selectively overexpresses the human vitamin C transporter SVCT2 in the lens. Consequently, lenticular levels of vitamin C and its oxidation products were 5- to 15-fold elevated, resulting in a highly compressed aging process and accelerated formation of several protein-bound advanced Maillard reaction products identical with those of aging human lens proteins. These data strongly implicate vitamin C in lens crystallin aging and may serve as a model for protein aging in other tissues particularly rich in vitamin C, such as the hippocampal neurons and the adrenal gland. The hSVCT2 mouse is expected to facilitate the search for drugs that inhibit damage by vitamin C oxidation products.
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Affiliation(s)
- Xingjun Fan
- *Departments of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106-7288
| | - Lixing W. Reneker
- Department of Ophthalmology, University of Missouri, Columbia, MO 65212; and
| | - Mark E. Obrenovich
- *Departments of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106-7288
| | - Christopher Strauch
- *Departments of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106-7288
| | - Rongzhu Cheng
- Department of Ophthalmology, University of Missouri, Columbia, MO 65212; and
| | - Simon M. Jarvis
- School of Biosciences, University of Westminster, London W1W 6UW, United Kingdom
| | - Beryl J. Ortwerth
- Department of Ophthalmology, University of Missouri, Columbia, MO 65212; and
| | - Vincent M. Monnier
- *Departments of Pathology and Biochemistry, Case Western Reserve University, Cleveland, OH 44106-7288
- To whom correspondence should be addressed at:
Department of Pathology, Case Western Reserve University, Wolstein Building, Room 5137, 2103 Cornell Road, Cleveland, OH 44106-7288. E-mail:
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