scholarly journals Accumulative deamidation of human lens protein γS-crystallin leads to partially unfolded intermediates with enhanced aggregation propensity

2020 ◽  
Author(s):  
Calvin J. Vetter ◽  
David C. Thorn ◽  
Samuel G. Wheeler ◽  
Charlie Mundorff ◽  
Kate Halverson ◽  
...  
Keyword(s):  
Light Scattering ◽  
Molecular Mechanisms ◽  
Small Population ◽  
Site Directed Mutagenesis ◽  
Human Lens ◽  
Lens Protein ◽  
Triple Mutant ◽  
Age Related ◽  
Human Lenses ◽  
Partially Unfolded

AbstractAge-related cataract is a major cause of blindness worldwide. Yet, the molecular mechanisms whereby large, light scattering aggregates form is poorly understood, because of the complexity of the aggregates isolated from human lenses. The predominant proteins in the lens are structural proteins called crystallins. The γS-crystallin is heavily modified in cataractous lenses by deamidation, which introduces a negative charge at labile asparagine residues. The effects of deamidation at asparagines, N14, N76, and N143, were mimicked by replacing the asparagine with aspartate using site-directed mutagenesis. The effects of these surface deamidations on the stability, unfolding, and aggregation properties of γS were determined using dynamic light scattering, chemical and thermal-denaturation, and hydrogen-deuterium exchange with mass spectrometry. We found that a small population of all the deamidation mimics aggregated directly into large light scattering bodies with a radius greater than 10 nm that contributed 14-60% of the total scattering intensity compared to 7% for WT under the same conditions. A possible mechanism was identified under partially denaturing conditions, where deamidation led to significantly more rapid unfolding and aggregation particularly for N76D compared to WT. The triple mutant was further destabilized, reflecting the enhanced aggregation properties of N14D and N143D. Thus, the effects of deamidation were both site-specific and cumulative. αA-crystallin was ineffective at acting as a chaperone to prevent the aggregation of destabilized, deamidated γS. It is concluded that surface deamidations, while causing minimal structural disruption individually, progressively destabilize crystallin proteins, leading to their unfolding and precipitation in aged and cataractous lenses.

scholarly journals Nanoceria Prevents Glucose-Induced Protein Glycation in Eye Lens Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1473
Author(s):  
Belal I. Hanafy ◽  
Gareth W. V. Cave ◽  
Yvonne Barnett ◽  
Barbara K. Pierscionek
Keyword(s):  
Protein Glycation ◽  
Human Lens ◽  
Lens Epithelial Cells ◽  
Oxide Nanoparticles ◽  
Lens Protein ◽  
Oxygen Species ◽  
Human Lens Epithelial Cells ◽  
Age Related ◽  
Age Related Changes

Cerium oxide nanoparticles (nanoceria) are generally known for their recyclable antioxidative properties making them an appealing biomaterial for protecting against physiological and pathological age-related changes that are caused by reactive oxygen species (ROS). Cataract is one such pathology that has been associated with oxidation and glycation of the lens proteins (crystallins) leading to aggregation and opacification. A novel coated nanoceria formulation has been previously shown to enter the human lens epithelial cells (HLECs) and protect them from oxidative stress induced by hydrogen peroxide (H2O2). In this work, the mechanism of nanoceria uptake in HLECs is studied and multiple anti-cataractogenic properties are assessed in vitro. Our results show that the nanoceria provide multiple beneficial actions to delay cataract progression by (1) acting as a catalase mimetic in cells with inhibited catalase, (2) improving reduced to oxidised glutathione ratio (GSH/GSSG) in HLECs, and (3) inhibiting the non-enzymatic glucose-induced glycation of the chaperone lens protein α-crystallin. Given the multifactorial nature of cataract progression, the varied actions of nanoceria render them promising candidates for potential non-surgical therapeutic treatment.

scholarly journals Let-7c-3p Regulates Autophagy under Oxidative Stress by Targeting ATG3 in Lens Epithelial Cells

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
Ting Li ◽  
Yanhong Huang ◽  
Wenkai Zhou ◽  
Qichang Yan
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Western Blot ◽  
Molecular Mechanisms ◽  
Luciferase Reporter ◽  
Human Lens ◽  
Lens Epithelial Cells ◽  
Age Related ◽  
Spot Number ◽  
Gene Assay

Background. Oxidative stress is an important factor during age-related cataract formation. Apoptosis and autophagy induced by oxidative stress have been reported as key factors in age-related cataract. In our research, we investigated the role of let-7c-3p in the regulation of autophagy and apoptosis during the formation of age-related cataract. Material and Methods. Real-time PCR and western blot were employed to detect the expression of let-7c-3p in the tissues of age-related cataract. Human lens epithelial cells (LECs) were treated with H2O2 as an age-related cataract model. The extent of apoptosis was measured by flow cytometry and western blot. To detect autophagy, immunofluorescence was used to analyze the spot number of LC3, and western blot was used to detect the expression of LC3-II/I and ATG3. The molecular mechanisms of let-7c-3p regulating autophagy via ATG3 under oxidative stress were performed by a luciferase report gene assay and rescue experiment. Results. Downregulation of let-7c-3p was found in the age-related cataract group aged >65 years relative to the age-related cataract group aged ≤65 years. Consistently, the expression of let-7c-3p was also lower under oxidative stress. The activities of LEC apoptosis and autophagy induced by oxidative stress were inhibited by let-7c-3p. By the bioinformatics database and the luciferase reporter assay, ATG3 was found to be a direct target of let-7c-3p. Let-7c-3p reduced the ATG3-mediated autophagy level, which was induced by oxidative stress in LECs. Conclusion. Let-7c-3p inhibits autophagy by targeting ATG3 in LECs in age-related cataract.

Role of Novel UV Filters in Human Lens Protein Damage Link to Age Related Nuclear Cataract

2010 ◽  
Vol 49 ◽  
pp. S209
Author(s):  
Nicholas Gad ◽  
Jasminka Mizdrak ◽  
David Pattison ◽  
Michael Davies ◽  
Roger Truscott ◽  
...  
Keyword(s):  
Protein Damage ◽  
Human Lens ◽  
Lens Protein ◽  
Nuclear Cataract ◽  
Uv Filters ◽  
Age Related

scholarly journals Ghrelin Protects Human Lens Epithelial Cells against Oxidative Stress-Induced Damage

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jie Bai ◽  
Fan Yang ◽  
Li Dong ◽  
Yi Zheng
Keyword(s):  
Oxidative Stress ◽  
Molecular Mechanisms ◽  
Human Lens ◽  
Morphological Examination ◽  
Important Mediator ◽  
Age Related ◽  
Ros Accumulation ◽  
Cellular Apoptosis ◽  
Antioxidant Supplements

Oxidative stress has been recognized as an important mediator in the pathogenesis of age-related cataracts; using antioxidant supplements is one plausible strategy to protect the antioxidative defense system against oxidative stress. Ghrelin administration is expected to reduce ROS, preventing the onset of different diseases. The role of ghrelin, if any, in protecting against oxidative stress in HLECs has never been examined. In the present study, we investigated the effects of ghrelin against H2O2-induced oxidative stress and the associated molecular mechanisms in HLECs and rat lenses. The results showed that pretreatment with ghrelin reduced H2O2-induced cellular apoptosis and ROS accumulation, increased the expression levels of SOD and CAT, and decreased the expression level of MDA. The morphological examination showed that the ghrelin-treated lens organ culture maintained transparency. This is the first report to show that ghrelin can protect HLECs from H2O2-induced oxidative stress. Our findings suggest that ghrelin may prevent the progression of cataracts, which has treatment value for ophthalmologists.

scholarly journals RNA sequencing and bioinformatics analysis of human lens epithelial cells in age-related cataract

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhongying Wang ◽  
Dongmei Su ◽  
Shanhe Liu ◽  
Guiqian Zheng ◽  
Gaobo Zhang ◽  
...  
Keyword(s):  
Rna Sequencing ◽  
Molecular Mechanisms ◽  
Bioinformatics Analysis ◽  
Human Lens ◽  
Older Individuals ◽  
Disease Mechanism ◽  
Anterior Capsule ◽  
Bioinformatics Analyses ◽  
Age Related ◽  
Pathway Analyses

Abstract Background Age-related cataract (ARC) is the main cause of blindness in older individuals but its specific pathogenic mechanism is unclear. This study aimed to identify differentially expressed genes (DEGs) associated with ARC and to improve our understanding of the disease mechanism. Methods Anterior capsule samples of the human lens were collected from ARC patients and healthy controls and used for RNA sequencing to detect DEGs. Identified DEGs underwent bioinformatics analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Subsequently, reverse transcription quantitative RT-qPCR was used to validate the different expression levels of selected genes. Results A total of 698 up-regulated DEGs and 414 down-regulated DEGs were identified in ARC patients compared with controls by transcriptome analysis. Through GO and KEGG bioinformatics analysis, the functions of significantly DEGs and their possible molecular mechanisms were determined. Sequencing results were verified by RT-qPCR as being accurate and reliable. Conclusions This study identified several genes associated with ARC, which improves our knowledge of the disease mechanism.

scholarly journals A Potential Role for Fructosamine-3-Kinase in Cataract Treatment

2021 ◽  
Vol 22 (8) ◽  
pp. 3841
Author(s):  
Sander De De Bruyne ◽  
Loes van van Schie ◽  
Jonas Himpe ◽  
Filip De De Somer ◽  
Inge Everaert ◽  
...  
Keyword(s):  
Immune Response ◽  
Topical Treatment ◽  
Time Dependent ◽  
Human Lens ◽  
Extension Rate ◽  
Lens Protein ◽  
Human Eye ◽  
Age Related ◽  
Human Eyes

Cataracts are the major cause of blindness worldwide, largely resulting from aging and diabetes mellitus. Advanced glycation end-products (AGEs) have been identified as major contributors in cataract formation because they alter lens protein structure and stability and induce covalent cross-linking, aggregation, and insolubilization of lens crystallins. We investigated the potential of the deglycating enzyme fructosamine-3-kinase (FN3K) in the disruption of AGEs in cataractous lenses. Macroscopic changes of equine lenses were evaluated after ex vivo intravitreal FN3K injection. The mechanical properties of an equine lens pair were evaluated after treatment with saline and FN3K. AGE-type autofluorescence (AF) was measured to assess the time-dependent effects of FN3K on glycolaldehyde-induced AGE-modified porcine lens fragments and to evaluate its actions on intact lenses after in vivo intravitreal FN3K injection of murine eyes. A potential immune response after injection was evaluated by analysis of IL-2, TNFα, and IFNγ using an ELISA kit. Dose- and time-dependent AF kinetics were analyzed on pooled human lens fragments. Furthermore, AF measurements and a time-lapse of macroscopic changes were performed on intact cataractous human eye lenses after incubation with an FN3K solution. At last, AF measurements were performed on cataractous human eyes after crossover topical treatment with either saline- or FN3K-containing drops. While the lenses of the equine FN3K-treated eyes appeared to be clear, the saline-treated lenses had a yellowish-brown color. Following FN3K treatment, color restoration could be observed within 30 min. The extension rate of the equine FN3K-treated lens was more than twice the extension rate of the saline-treated lens. FN3K treatment induced significant time-dependent decreases in AGE-related AF values in the AGE-modified porcine lens fragments. Furthermore, in vivo intravitreal FN3K injection of murine eyes significantly reduced AF values of the lenses. Treatment did not provoke a systemic immune response in mice. AF kinetics of FN3K-treated cataractous human lens suspensions revealed dose- and time-dependent decreases. Incubation of cataractous human eye lenses with FN3K resulted in a macroscopic lighter color of the cortex and a decrease in AF values. At last, crossover topical treatment of intact human eyes revealed a decrease in AF values during FN3K treatment, while showing no notable changes with saline. Our study suggests, for the first time, a potential additional role of FN3K as an alternative treatment for AGE-related cataracts.

The Role of Vascular Aging in Atherosclerotic Plaque Development and Vulnerability

2019 ◽  
Vol 25 (29) ◽  
pp. 3098-3111 ◽  
Author(s):  
Luca Liberale ◽  
Giovanni G. Camici
Keyword(s):  
Atherosclerotic Plaque ◽  
Molecular Mechanisms ◽  
Driving Forces ◽  
Plaque Burden ◽  
Vascular Aging ◽  
Age Related ◽  
Plaque Development ◽  
Increased Risk ◽  
The Impact ◽  
Over Time

Background: The ongoing demographical shift is leading to an unprecedented aging of the population. As a consequence, the prevalence of age-related diseases, such as atherosclerosis and its thrombotic complications is set to increase in the near future. Endothelial dysfunction and vascular stiffening characterize arterial aging and set the stage for the development of cardiovascular diseases. Atherosclerotic plaques evolve over time, the extent to which these changes might affect their stability and predispose to sudden complications remains to be determined. Recent advances in imaging technology will allow for longitudinal prospective studies following the progression of plaque burden aimed at better characterizing changes over time associated with plaque stability or rupture. Oxidative stress and inflammation, firmly established driving forces of age-related CV dysfunction, also play an important role in atherosclerotic plaque destabilization and rupture. Several genes involved in lifespan determination are known regulator of redox cellular balance and pre-clinical evidence underlines their pathophysiological roles in age-related cardiovascular dysfunction and atherosclerosis. Objective: The aim of this narrative review is to examine the impact of aging on arterial function and atherosclerotic plaque development. Furthermore, we report how molecular mechanisms of vascular aging might regulate age-related plaque modifications and how this may help to identify novel therapeutic targets to attenuate the increased risk of CV disease in elderly people.

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration

2019 ◽  
Vol 19 (10) ◽  
pp. 705-718 ◽  
Author(s):  
Naima Mansoor ◽  
Fazli Wahid ◽  
Maleeha Azam ◽  
Khadim Shah ◽  
Anneke I. den Hollander ◽  
...  
Keyword(s):  
Matrix Metalloproteinases ◽  
Macular Degeneration ◽  
Complement System ◽  
Molecular Mechanisms ◽  
Critical Role ◽  
Age Related Macular Degeneration ◽  
Genetic Changes ◽  
Complement System Proteins ◽  
Age Related ◽  
Common Genetic Variants

: Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40–60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

Pathogenesis of Age-related Cataract: a systematic review of proteomic studies

2020 ◽  
Vol 17 ◽  
Author(s):  
Christina Karakosta ◽  
Argyrios Tzamalis ◽  
Michalis Aivaliotis ◽  
Ioannis Tsinopoulos
Keyword(s):  
Systematic Review ◽  
Oxidant Stress ◽  
Critical Role ◽  
Human Lens ◽  
Nuclear Cataract ◽  
Cataract Formation ◽  
Post Translational Modification ◽  
Ability To Act ◽  
Age Related

Background/Objective:: The aim of this systematic review is to identify all the available data on human lens proteomics with a critical role to age-related cataract formation in order to elucidate the physiopathology of the aging lens. Materials and Methods:: We searched on Medline and Cochrane databases. The search generated 328 manuscripts. We included nine original proteomic studies that investigated human cataractous lenses. Results:: Deamidation was the major age-related post-translational modification. There was a significant increase in the amount of αA-crystallin D-isoAsp58 present at all ages, while an increase in the extent of Trp oxidation was apparent in cataract lenses when compared to aged normal lenses. During aging, enzymes with oxidized cysteine at critical sites included GAPDH, glutathione synthase, aldehyde dehydrogenase, sorbitol dehydrogenase, and PARK7. Conclusion:: D-isoAsp in αA crystallin could be associated with the development of age-related cataract in human, by contributing to the denaturation of a crystallin, and decreasing its ability to act as a chaperone. Oxidation of Trp may be associated with nuclear cataract formation in human, while the role of oxidant stress in age-related cataract formation is dominant.

Review of the Literature Examining the Association of Serum Uric Acid with Osteoporosis and Mechanistic Insights into Its Effect on Bone Metabolism

2019 ◽  
Vol 19 (3) ◽  
pp. 259-273 ◽  
Author(s):  
Neelam Kaushal ◽  
Divya Vohora ◽  
Rajinder K Jalali ◽  
Sujeet Jha
Keyword(s):  
Risk Factors ◽  
Bone Mineral Density ◽  
Uric Acid ◽  
Bone Metabolism ◽  
Serum Uric Acid ◽  
Bone Mineral ◽  
Molecular Mechanisms ◽  
Association Studies ◽  
Mineral Density ◽  
Age Related

Background And Objective:Osteoporosis is a common bone disorder that increases susceptibility to fragility bone fractures. The clinical and public health repercussions of osteoporosis are huge due to the morbidity, mortality, and cost of medical care linked with fragility fractures. Clinical assessment of osteoporotic risk factors can help to identify candidates at an early stage that will benefit from medical intervention and potentially lowering the morbidity and mortality seen with fractures and complications. Given this, research is ongoing to evaluate the association of osteoporosis with some novel or less well-studied risk factors/bio-markers such as uric acid (UA).Discussion:Uric acid’s antioxidant activity has been proposed to be one of the factors responsible for increasing longevity and lowering rates of age-related cancers during primate evolution, the level of which increased markedly due to loss of uricase enzyme activity (mutational silencing). Accumulated evidence shows that oxidative stress is the fundamental mechanism of age-related bone loss and acts via enhancing osteoclastic activity and increasing bone resorption. Antioxidant substances such as ascorbic acid scavenge free radicals are positively related to bone health. Thus, it is hypothesized that uric acid holds bone-protective potential owing to its potent antioxidative property. Several correlation studies have been conducted globally to investigate the relationship between serum uric acid with bone mineral density and osteoporosis. Few pre-clinical studies have tried to investigate the interaction between uric acid and bone mineral density and reported important role played via Runt-related transcription factor 2 (RUNX2)/core-binding factor subunit alpha-1 (CBF-alpha-1), Wingless-related integration site (Wnt)-3a/β-catenin signaling pathway and 11β Hydroxysteroid Dehydrogenase type 1.Conclusion:In this review, the authors provided a comprehensive summary of the literature related to association studies reported in humans as well work done until date to understand the potential cellular and molecular mechanisms that interplay between uric acid and bone metabolism.

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