1
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Qiang B, Xu Q, Hu A, Fang J, Shen C, Zhang Y, Wang J. Feasibility of shear wave elastography for evaluating lens stiffness in patients with age-related cataracts: A quantitative analysis. Heliyon 2024; 10:e32255. [PMID: 38882265 PMCID: PMC11180308 DOI: 10.1016/j.heliyon.2024.e32255] [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: 09/20/2023] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/18/2024] Open
Abstract
Background Shear wave elastography (SWE) is a novel imaging technique that provides quantitative assessments of tissue stiffness. This non-invasive method offers real-time, quantitative measurements and has been widely applied to various tissues, providing valuable diagnostic insights. Purpose This study aimed to investigate the feasibility of using SWE to evaluate the stiffness of the lens in patients with age-related cataracts. Materials and methods A comparative analysis involving 92 patients diagnosed with age-related cataracts and 39 healthy controls was conducted. Lens stiffness was quantified using SWE measurements. The lens nucleus of all participants was graded based on the Lens Opacities Classification System II (LOCS II). Correlations between the stiffness of the lens and age were also analyzed. Results The study indicates that both the stiffness of the lens and the lens nucleus were significantly higher in patients with age-related cataracts compared to healthy controls (P < 0.001). In patients with age-related cataracts, although lens nucleus stiffness variations across different grades of cataract severity were not statistically significant, all grades displayed increased stiffness relative to healthy controls. Additionally, a significant positive correlation between lens stiffness and age was observed in all participants (P < 0.001). Conclusion SWE appears to be a promising imaging technique for quantitatively assessing the mechanical characteristics of the lens in patients with age-related cataracts.
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Affiliation(s)
- Banghong Qiang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Qiancheng Xu
- Department of Critical Care Medicine, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241000, Anhui, China
| | - Aili Hu
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Jiagui Fang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Chunyun Shen
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Yu Zhang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Junli Wang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
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2
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Camerino M, Chang W, Cvekl A. Analysis of long-range chromatin contacts, compartments and looping between mouse embryonic stem cells, lens epithelium and lens fibers. Epigenetics Chromatin 2024; 17:10. [PMID: 38643244 PMCID: PMC11031936 DOI: 10.1186/s13072-024-00533-x] [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: 11/15/2023] [Accepted: 03/08/2024] [Indexed: 04/22/2024] Open
Abstract
BACKGROUND Nuclear organization of interphase chromosomes involves individual chromosome territories, "open" and "closed" chromatin compartments, topologically associated domains (TADs) and chromatin loops. The DNA- and RNA-binding transcription factor CTCF together with the cohesin complex serve as major organizers of chromatin architecture. Cellular differentiation is driven by temporally and spatially coordinated gene expression that requires chromatin changes of individual loci of various complexities. Lens differentiation represents an advantageous system to probe transcriptional mechanisms underlying tissue-specific gene expression including high transcriptional outputs of individual crystallin genes until the mature lens fiber cells degrade their nuclei. RESULTS Chromatin organization between mouse embryonic stem (ES) cells, newborn (P0.5) lens epithelium and fiber cells were analyzed using Hi-C. Localization of CTCF in both lens chromatins was determined by ChIP-seq and compared with ES cells. Quantitative analyses show major differences between number and size of TADs and chromatin loop size between these three cell types. In depth analyses show similarities between lens samples exemplified by overlaps between compartments A and B. Lens epithelium-specific CTCF peaks are found in mostly methylated genomic regions while lens fiber-specific and shared peaks occur mostly within unmethylated DNA regions. Major differences in TADs and loops are illustrated at the ~ 500 kb Pax6 locus, encoding the critical lens regulatory transcription factor and within a larger ~ 15 Mb WAGR locus, containing Pax6 and other loci linked to human congenital diseases. Lens and ES cell Hi-C data (TADs and loops) together with ATAC-seq, CTCF, H3K27ac, H3K27me3 and ENCODE cis-regulatory sites are shown in detail for the Pax6, Sox1 and Hif1a loci, multiple crystallin genes and other important loci required for lens morphogenesis. The majority of crystallin loci are marked by unexpectedly high CTCF-binding across their transcribed regions. CONCLUSIONS Our study has generated the first data on 3-dimensional (3D) nuclear organization in lens epithelium and lens fibers and directly compared these data with ES cells. These findings generate novel insights into lens-specific transcriptional gene control, open new research avenues to study transcriptional condensates in lens fiber cells, and enable studies of non-coding genetic variants linked to cataract and other lens and ocular abnormalities.
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Affiliation(s)
- Michael Camerino
- The Departments Genetics, Albert Einstein College of Medicine, NY10461, Bronx, USA
| | - William Chang
- Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, NY10461, Bronx, USA
| | - Ales Cvekl
- The Departments Genetics, Albert Einstein College of Medicine, NY10461, Bronx, USA.
- Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, NY10461, Bronx, USA.
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3
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Subczynski WK, Pasenkiewicz-Gierula M, Widomska J. Protecting the Eye Lens from Oxidative Stress through Oxygen Regulation. Antioxidants (Basel) 2023; 12:1783. [PMID: 37760086 PMCID: PMC10525422 DOI: 10.3390/antiox12091783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/08/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Molecular oxygen is a primary oxidant that is involved in the formation of active oxygen species and in the oxidation of lipids and proteins. Thus, controlling oxygen partial pressure (concentration) in the human organism, tissues, and organs can be the first step in protecting them against oxidative stress. However, it is not an easy task because oxygen is necessary for ATP synthesis by mitochondria and in many biochemical reactions taking place in all cells in the human body. Moreover, the blood circulatory system delivers oxygen to all parts of the body. The eye lens seems to be the only organ that is protected from the oxidative stress through the regulation of oxygen partial pressure. The basic mechanism that developed during evolution to protect the eye lens against oxidative damage is based on the maintenance of a very low concentration of oxygen within the lens. This antioxidant mechanism is supported by the resistance of both the lipid components of the lens membrane and cytosolic proteins to oxidation. Any disturbance, continuous or acute, in the working of this mechanism increases the oxygen concentration, in effect causing cataract development. Here, we describe the biophysical basis of the mechanism and its correlation with lens transparency.
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Affiliation(s)
| | - Marta Pasenkiewicz-Gierula
- Department of Computational Biophysics and Bioinformatics, Jagiellonian University, 30-387 Krakow, Poland;
| | - Justyna Widomska
- Department of Biophysics, Medical University of Lublin, 20-090 Lublin, Poland
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4
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Feng L, Wei Y, Sun Y, Zhou L, Bi S, Chen W, Xiang W. MIR34A modulates lens epithelial cell apoptosis and cataract development via the HK1/caspase 3 signaling pathway. Aging (Albany NY) 2023; 15:6331-6345. [PMID: 37414399 PMCID: PMC10373963 DOI: 10.18632/aging.204854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/15/2023] [Indexed: 07/08/2023]
Abstract
Cataracts are the leading cause of blindness in the world. Age is a major risk factor for cataracts, and with increasing aging, the burden of cataracts will grow, but the exact details of cataractogenesis remain unclear. A recent study showed that microRNA-34a (MIR34A) is involved in the development of cataracts, but the underlying pathogenesis remains obscure. Here, our results of microRNA target prediction showed that hexokinase 1 (HK1) is one of the genes targeted by MIR34A. Based on this finding, we focused on the function of MIR34A and HK1 in the progress of cataracts, whereby the human lens epithelial cell line SRA01/04 and mouse lens were treated with MIR34A mimics and HK1 siRNA. We found that HK1 mRNA is a direct target of MIR34A, whereby the high expression of MIR34A in the cataract lens suppresses the expression of HK1. In vitro, the upregulation of MIR34A together with the downregulation of HK1 inhibits the proliferation, induces the apoptosis of SRA01/04 cells, and accelerates the opacification of mouse lenses via the HK1/caspase 3 signaling pathway. In summary, our study demonstrates that MIR34A modulates lens epithelial cell (LEC) apoptosis and cataract development through the HK1/caspase 3 signaling pathway.
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Affiliation(s)
- Lujia Feng
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
- Shenzhen Eye Hospital, Jinan University, Shenzhen Eye Institute, Shenzhen 518040, China
| | - Yantao Wei
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
| | - Yimeng Sun
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
| | - Linbin Zhou
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
| | - Shaowei Bi
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
| | - Weirong Chen
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
| | - Wu Xiang
- State Key Laboratory of Ophthalmology; Zhongshan Ophthalmic Center, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science; Guangdong Provincial Clinical Research Center for Ocular Diseases, Guangzhou 510060, China
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5
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Huang Y, Ping X, Cui Y, Yang H, Bao J, Yin Q, Ailifeire H, Shentu X. Glycolysis Aids in Human Lens Epithelial Cells' Adaptation to Hypoxia. Antioxidants (Basel) 2023; 12:1304. [PMID: 37372033 DOI: 10.3390/antiox12061304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
Hypoxic environments are known to trigger pathological damage in multiple cellular subtypes. Interestingly, the lens is a naturally hypoxic tissue, with glycolysis serving as its main source of energy. Hypoxia is essential for maintaining the long-term transparency of the lens in addition to avoiding nuclear cataracts. Herein, we explore the complex mechanisms by which lens epithelial cells adapt to hypoxic conditions while maintaining their normal growth and metabolic activity. Our data show that the glycolysis pathway is significantly upregulated during human lens epithelial (HLE) cells exposure to hypoxia. The inhibition of glycolysis under hypoxic conditions incited endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) production in HLE cells, leading to cellular apoptosis. After ATP was replenished, the damage to the cells was not completely recovered, and ER stress, ROS production, and cell apoptosis still occurred. These results suggest that glycolysis not only performs energy metabolism in the process of HLE cells adapting to hypoxia, but also helps them continuously resist cell apoptosis caused by ER stress and ROS production. Furthermore, our proteomic atlas provides possible rescue mechanisms for cellular damage caused by hypoxia.
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Affiliation(s)
- Yuxin Huang
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Xiyuan Ping
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Yilei Cui
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Hao Yang
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Jing Bao
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Qichuan Yin
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Hailaiti Ailifeire
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
| | - Xingchao Shentu
- Eye Center, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Provincial Key Laboratory of Ophthalmology, Zhejiang Provincial Clinical Research Center for Eye Diseases, Zhejiang Provincial Engineering Institute on Eye Diseases, Hangzhou 310009, China
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6
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Uwineza A, Cummins I, Jarrin M, Kalligeraki AA, Barnard S, Mol M, Degani G, Altomare AA, Aldini G, Schreurs A, Balschun D, Ainsbury EA, Dias IHK, Quinlan RA. Identification and quantification of ionising radiation-induced oxysterol formation in membranes of lens fibre cells. ADVANCES IN REDOX RESEARCH 2023; 7:None. [PMID: 38798747 PMCID: PMC11112148 DOI: 10.1016/j.arres.2022.100057] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 12/06/2022] [Accepted: 12/13/2022] [Indexed: 05/29/2024]
Abstract
Ionising radiation (IR) is a cause of lipid peroxidation, and epidemiological data have revealed a correlation between exposure to IR and the development of eye lens cataracts. Cataracts remain the leading cause of blindness around the world. The plasma membranes of lens fibre cells are one of the most cholesterolrich membranes in the human body, forming lipid rafts and contributing to the biophysical properties of lens fibre plasma membrane. Liquid chromatography followed by mass spectrometry was used to analyse bovine eye lens lipid membrane fractions after exposure to 5 and 50 Gy and eye lenses taken from wholebody 2 Gy-irradiated mice. Although cholesterol levels do not change significantly, IR dose-dependant formation of the oxysterols 7β-hydroxycholesterol, 7-ketocholesterol and 5, 6-epoxycholesterol in bovine lens nucleus membrane extracts was observed. Whole-body X-ray exposure (2 Gy) of 12-week old mice resulted in an increase in 7β-hydroxycholesterol and 7-ketocholesterol in their eye lenses. Their increase regressed over 24 h in the living lens cortex after IR exposure. This study also demonstrated that the IR-induced fold increase in oxysterols was greater in the mouse lens cortex than the nucleus. Further work is required to elucidate the mechanistic link(s) between oxysterols and IR-induced cataract, but these data evidence for the first time that IR exposure of mice results in oxysterol formation in their eye lenses.
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Affiliation(s)
- Alice Uwineza
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, University of Durham, South Road, Durham D1 3LE, United Kingdom
| | - Ian Cummins
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
| | - Miguel Jarrin
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, University of Durham, South Road, Durham D1 3LE, United Kingdom
| | - Alexia A. Kalligeraki
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, University of Durham, South Road, Durham D1 3LE, United Kingdom
| | - Stephen Barnard
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, University of Durham, South Road, Durham D1 3LE, United Kingdom
- UK Health Security Agency, Cytogenetics and Pathology Group, Centre for Radiation, Chemical and Environmental Hazards Division, Chilton, Oxon OX11 0RQ, Didcot, United Kingdom
| | - Marco Mol
- Department of Pharmaceutical Sciences, Via Mangiagalli 25, Milano 20133, Italy
| | - Genny Degani
- Department of Biosciences, Via Celoria 26, Milano 20133, Italy
| | | | - Giancarlo Aldini
- Department of Pharmaceutical Sciences, Via Mangiagalli 25, Milano 20133, Italy
| | - An Schreurs
- Brain & Cognition, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Detlef Balschun
- Brain & Cognition, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Elizabeth A. Ainsbury
- UK Health Security Agency, Cytogenetics and Pathology Group, Centre for Radiation, Chemical and Environmental Hazards Division, Chilton, Oxon OX11 0RQ, Didcot, United Kingdom
| | - Irundika HK Dias
- Aston Medical School, Aston University, B4 7ET, Birmingham, United Kingdom
| | - Roy A. Quinlan
- Department of Biosciences, University of Durham, Upper Mountjoy Science Site, South Road, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, University of Durham, South Road, Durham D1 3LE, United Kingdom
- Department of Biological Structure, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, United States
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7
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Li H, Gao L, Du J, Ma T, Li W, Ye Z, Li Z. Impacts of autophagy on the formation of organelle-free zone during the lens development. Mol Biol Rep 2023; 50:4551-4564. [PMID: 36877352 DOI: 10.1007/s11033-023-08323-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/02/2023] [Indexed: 03/07/2023]
Abstract
The thorough degeneration of organelles in the core of the lens is certainly a hallmark event during the lens development. Organelles degradation in the terminal differentiation process of lens fiber cells to form an organelle-free zone is critical for lens maturation and transparency. Several mechanisms have been proposed to expand our understanding of lens organelles degradation, including apoptotic pathways, the participation of ribozyme, proteolytic enzyme and phospholipase A and acyltransferase, and the newly discovered roles for autophagy. Autophagy is a lysosome-dependent degradation reaction during which the "useless" cellular components are degraded and recycled. These cellular components, such as incorrectly folded proteins, damaged organelles and other macromolecules, are first engulfed by the autophagosome before being further delivered to lysosomes for degradation. Although autophagy has been recognized involving in organelle degradation of the lens, the detailed functions remain to be discovered. Recent advances have revealed that autophagy not only plays a vital role in the intracellular quality control of the lens but is also involved in the degradation of nonnuclear organelles in the process of lens fiber cell differentiation. Herein, we first review the potential mechanisms of organelle-free zone formation, then discuss the roles of autophagy in intracellular quality control and cataract formation, and finally substantially summarize the potential involvement of autophagy in the development of organelle-free zone formation.
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Affiliation(s)
- Hongyu Li
- Medical School of Chinese PLA, Beijing, China.,Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China
| | - Lixiong Gao
- Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China
| | - Jinlin Du
- Medical School of Chinese PLA, Beijing, China.,Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China
| | - Tianju Ma
- Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China
| | - Wen Li
- Medical School of Chinese PLA, Beijing, China.,Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China
| | - Zi Ye
- Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China.
| | - Zhaohui Li
- Medical School of Chinese PLA, Beijing, China. .,Senior Department of Ophthalmology, the Third Medical Center of PLA General Hospital, Beijing, China.
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8
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Brennan L, Costello MJ, Hejtmancik JF, Menko AS, Riazuddin SA, Shiels A, Kantorow M. Autophagy Requirements for Eye Lens Differentiation and Transparency. Cells 2023; 12:475. [PMID: 36766820 PMCID: PMC9914699 DOI: 10.3390/cells12030475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/17/2023] [Accepted: 01/25/2023] [Indexed: 02/05/2023] Open
Abstract
Recent evidence points to autophagy as an essential cellular requirement for achieving the mature structure, homeostasis, and transparency of the lens. Collective evidence from multiple laboratories using chick, mouse, primate, and human model systems provides evidence that classic autophagy structures, ranging from double-membrane autophagosomes to single-membrane autolysosomes, are found throughout the lens in both undifferentiated lens epithelial cells and maturing lens fiber cells. Recently, key autophagy signaling pathways have been identified to initiate critical steps in the lens differentiation program, including the elimination of organelles to form the core lens organelle-free zone. Other recent studies using ex vivo lens culture demonstrate that the low oxygen environment of the lens drives HIF1a-induced autophagy via upregulation of essential mitophagy components to direct the specific elimination of the mitochondria, endoplasmic reticulum, and Golgi apparatus during lens fiber cell differentiation. Pioneering studies on the structural requirements for the elimination of nuclei during lens differentiation reveal the presence of an entirely novel structure associated with degrading lens nuclei termed the nuclear excisosome. Considerable evidence also indicates that autophagy is a requirement for lens homeostasis, differentiation, and transparency, since the mutation of key autophagy proteins results in human cataract formation.
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Affiliation(s)
- Lisa Brennan
- Department of Biomedical Science, Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33460, USA
| | - M. Joseph Costello
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - J. Fielding Hejtmancik
- Ophthalmic Genetics and Visual Function Branch, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - A. Sue Menko
- Department of Pathology, Anatomy and Cell Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
- Department of Ophthalmology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - S. Amer Riazuddin
- The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Alan Shiels
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Marc Kantorow
- Department of Biomedical Science, Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33460, USA
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9
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Shu DY, Chaudhary S, Cho KS, Lennikov A, Miller WP, Thorn DC, Yang M, McKay TB. Role of Oxidative Stress in Ocular Diseases: A Balancing Act. Metabolites 2023; 13:187. [PMID: 36837806 PMCID: PMC9960073 DOI: 10.3390/metabo13020187] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/22/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.
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Affiliation(s)
- Daisy Y. Shu
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Suman Chaudhary
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Kin-Sang Cho
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Anton Lennikov
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - William P. Miller
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - David C. Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Menglu Yang
- Department of Ophthalmology, Schepens Eye Research Institute of Mass Eye and Ear, Harvard Medical School, Boston, MA 02114, USA
| | - Tina B. McKay
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
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10
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Cvekl A, Camerino MJ. Generation of Lens Progenitor Cells and Lentoid Bodies from Pluripotent Stem Cells: Novel Tools for Human Lens Development and Ocular Disease Etiology. Cells 2022; 11:cells11213516. [PMID: 36359912 PMCID: PMC9658148 DOI: 10.3390/cells11213516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022] Open
Abstract
In vitro differentiation of human pluripotent stem cells (hPSCs) into specialized tissues and organs represents a powerful approach to gain insight into those cellular and molecular mechanisms regulating human development. Although normal embryonic eye development is a complex process, generation of ocular organoids and specific ocular tissues from pluripotent stem cells has provided invaluable insights into the formation of lineage-committed progenitor cell populations, signal transduction pathways, and self-organization principles. This review provides a comprehensive summary of recent advances in generation of adenohypophyseal, olfactory, and lens placodes, lens progenitor cells and three-dimensional (3D) primitive lenses, "lentoid bodies", and "micro-lenses". These cells are produced alone or "community-grown" with other ocular tissues. Lentoid bodies/micro-lenses generated from human patients carrying mutations in crystallin genes demonstrate proof-of-principle that these cells are suitable for mechanistic studies of cataractogenesis. Taken together, current and emerging advanced in vitro differentiation methods pave the road to understand molecular mechanisms of cataract formation caused by the entire spectrum of mutations in DNA-binding regulatory genes, such as PAX6, SOX2, FOXE3, MAF, PITX3, and HSF4, individual crystallins, and other genes such as BFSP1, BFSP2, EPHA2, GJA3, GJA8, LIM2, MIP, and TDRD7 represented in human cataract patients.
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Affiliation(s)
- Aleš Cvekl
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Correspondence: ; Tel.: +1-718-430-3217; Fax: +1-718-430-8778
| | - Michael John Camerino
- Departments Ophthalmology and Visual Sciences, Albert Einstein College of Medicine, Bronx, NY 10461, USA
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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11
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Sherin PS, Vyšniauskas A, López-Duarte I, Ogilby PR, Kuimova MK. Visualising UV-A light-induced damage to plasma membranes of eye lens. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2021; 225:112346. [PMID: 34736070 DOI: 10.1016/j.jphotobiol.2021.112346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 10/01/2021] [Accepted: 10/19/2021] [Indexed: 01/16/2023]
Abstract
An eye lens is constantly exposed to the solar UV radiation, which is considered the most important external source of age-related changes to eye lens constituents. The accumulation of modifications of proteins and lipids with age can eventually lead to the development of progressive lens opacifications, such as cataracts. Though the impact of solar UV radiation on the structure and function of proteins is actively studied, little is known about the effect of photodamage on plasma membranes of lens cells. In this work we exploit Fluorescence Lifetime Imaging Microscopy (FLIM), together with viscosity-sensitive fluorophores termed molecular rotors, to study the changes in viscosity of plasma membranes of porcine eye lens resulting from two different types of photodamage: Type I (electron transfer) and Type II (singlet oxygen) reactions. We demonstrate that these two types of photodamage result in clearly distinct changes in viscosity - a decrease in the case of Type I damage and an increase in the case of Type II processes. Finally, to simulate age-related changes that occur in vivo, we expose an intact eye lens to UV-A light under anaerobic conditions. The observed decrease in viscosity within plasma membranes is consistent with the ability of eye lens constituents to sensitize Type I photodamage under natural irradiation conditions. These changes are likely to alter the transport of metabolites and predispose the whole tissue to the development of pathological processes such as cataracts.
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Affiliation(s)
- Peter S Sherin
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK; International Tomography Center SB RAS, Institutskaya street 3A, Novosibirsk 630090, Russia.
| | - Aurimas Vyšniauskas
- Center for Physical Sciences and Technology, Saulėtekio av. 3, Vilnius LT-10257, Lithuania; Chemistry Department, Vilnius University, Naugarduko st. 24, Vilnius LT-03225, Lithuania
| | - Ismael López-Duarte
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK
| | - Peter R Ogilby
- Department of Chemistry, Aarhus University, Langelandsgade 140, Aarhus DK-8000, Denmark
| | - Marina K Kuimova
- Chemistry Department, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, London W12 0BZ, UK.
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12
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Serebryany E, Thorn DC, Quintanar L. Redox chemistry of lens crystallins: A system of cysteines. Exp Eye Res 2021; 211:108707. [PMID: 34332989 PMCID: PMC8511183 DOI: 10.1016/j.exer.2021.108707] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/09/2021] [Accepted: 07/23/2021] [Indexed: 11/28/2022]
Abstract
The nuclear region of the lens is metabolically quiescent, but it is far from inert chemically. Without cellular renewal and with decades of environmental exposures, the lens proteome, lipidome, and metabolome change. The lens crystallins have evolved exquisite mechanisms for resisting, slowing, adapting to, and perhaps even harnessing the effects of these cumulative chemical modifications to minimize the amount of light-scattering aggregation in the lens over a lifetime. Redox chemistry is a major factor in these damages and mitigating adaptations, and as such, it is likely to be a key component of any successful therapeutic strategy for preserving or rescuing lens transparency, and perhaps flexibility, during aging. Protein redox chemistry is typically mediated by Cys residues. This review will therefore focus primarily on the Cys-rich γ-crystallins of the human lens, taking care to extend these findings to the β- and α-crystallins where pertinent.
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Affiliation(s)
- Eugene Serebryany
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA.
| | - David C Thorn
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Liliana Quintanar
- Department of Chemistry, Centro de Investigación y de Estudios Avanzados (Cinvestav), Mexico City, Mexico
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13
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Zhuravleva YS, Sherin PS. Influence of pH on radical reactions between kynurenic acid and amino acids tryptophan and tyrosine. Part II. Amino acids within the protein globule of lysozyme. Free Radic Biol Med 2021; 174:211-224. [PMID: 34363946 DOI: 10.1016/j.freeradbiomed.2021.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/29/2021] [Accepted: 08/01/2021] [Indexed: 12/20/2022]
Abstract
An acidosis, a decrease of pH within a living tissue, may alter yields of radical reactions if participating radicals undergo partial or complete protonation. One of photosensitizers found in the human eye lens, kynurenic acid (KNA-), possesses pKa 5.5 for its radical form that is close to physiological pH 6.89 for a healthy lens. In this work we studied the influence of pH on mechanisms and products of photoinduced radical reactions between KNA- and amino acids tryptophan (Trp) and tyrosine (Tyr) within a globule of model protein, Hen White Egg Lysozyme (HEWL). Our results show that the rate constant of back electron transfer from kynurenyl to HEWL• radicals with the restoration of initial reagents - the major decay pathway for these radicals - does not change in the pH 3-7. The quantum yield of HEWL degradation is also pH independent, however a shift of pH from 7 to 5 completely changes the outcome of photoinduced damage to HEWL from intermolecular cross-linking to oxygenation. HPLC-MS analysis has shown that four of six Trp and all Tyr residues of HEWL are modified in different extents at all pH, but the lowering of pH from 7 to 5 significantly changes the direction of main photodamage from Trp62 to Trp108 located at the entrance and bottom of enzymatic center, respectively. A decrease of intermolecular cross-links via Trp62 is followed by an increase in quantities of intramolecular cross-links Tyr20-Tyr23 and Tyr23-Tyr53. The obtained results point out the competence of cross-linking and oxygenation reactions for Trp and Tyr radicals within a protein globule and significant increase of oxygenation to the total damage of protein in the case of cross-linking deceleration by coulombic repulsion of positively charged protein globules.
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Affiliation(s)
- Yuliya S Zhuravleva
- International Tomography Center SB RAS, Institutskaya street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova street 2, Novosibirsk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova street 2, Novosibirsk, Russia.
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14
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Zhuravleva YS, Sherin PS. Influence of pH on radical reactions between kynurenic acid and amino acids tryptophan and tyrosine. Part I. Amino acids in free state. Free Radic Biol Med 2021; 172:331-339. [PMID: 34146664 DOI: 10.1016/j.freeradbiomed.2021.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/14/2021] [Indexed: 01/06/2023]
Abstract
In the human eye lens the endogenous chromophores of UV-A light (315-400 nm) are able to sensitize radical reactions leading to protein modifications during normal aging and the cataract progression. Kynurenic acid (KNA-) is the most photochemically active dye of the human eye lens reported to date with pKa(KNAH2•) 5.5 for its radical form. Cataract is thought to develop under oxidative stress which could be accompanied by acidosis, an acidification of the intracellular environment. Protonation of kynurenyl radicals at mildly acidic conditions may change the outcome of radical reactions leading to additional damage to proteins. In this work we investigated the influence of pH on the degradation of initial reagents and the formation of products in photoinduced radical reactions between KNA- and amino acids tryptophan (Trp) and tyrosine (Tyr) in free states. Our results have shown that pH variation has minor influence on kinetics of reagent decay and accumulation of products in reactions between tyrosyl and kynurenic acid radicals. However in the case of Trp a two-fold decrease of the reagent degradation without visible changes in the composition of formed products was observed with pH decrease from 7 to 3. Time-resolved measurements have shown similar acidification-induced two-fold acceleration of decay of kynurenyl and tryptophanyl radicals via Back Electron Transfer (BET) with the restoration of initial reagents. Experiments with tryptophan derivatives with different pKa values for their radical forms point out the protonation of tryptophanyl radical as the driving force for BET acceleration at low pH. Our results demonstrate that the protonation of kynurenyl radical does not change its reactivity towards amino acids radicals but the total yield of radical photodamage decreases with the protonation of tryptophanyl radicals. It could be expected that radical induced damage to proteins will depend on the pKa of tryptophanyl radicals within a protein globule.
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Affiliation(s)
- Yuliya S Zhuravleva
- International Tomography Center SB RAS, Institutskaya Street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova Street 2, Novosibirsk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya Street 3a, Novosibirsk, Russia; Novosibirsk State University, Pirogova Street 2, Novosibirsk, Russia.
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15
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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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16
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Disatham J, Brennan L, Chauss D, Kantorow J, Afzali B, Kantorow M. A functional map of genomic HIF1α-DNA complexes in the eye lens revealed through multiomics analysis. BMC Genomics 2021; 22:497. [PMID: 34215186 PMCID: PMC8254356 DOI: 10.1186/s12864-021-07795-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 06/09/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND During eye lens development the embryonic vasculature regresses leaving the lens without a direct oxygen source. Both embryonically and throughout adult life, the lens contains a decreasing oxygen gradient from the surface to the core that parallels the natural differentiation of immature surface epithelial cells into mature core transparent fiber cells. These properties of the lens suggest a potential role for hypoxia and the master regulator of the hypoxic response, hypoxia-inducible transcription factor 1 (HIF1), in the regulation of genes required for lens fiber cell differentiation, structure and transparency. Here, we employed a multiomics approach combining CUT&RUN, RNA-seq and ATACseq analysis to establish the genomic complement of lens HIF1α binding sites, genes activated or repressed by HIF1α and the chromatin states of HIF1α-regulated genes. RESULTS CUT&RUN analysis revealed 8375 HIF1α-DNA binding complexes in the chick lens genome. One thousand one hundred ninety HIF1α-DNA binding complexes were significantly clustered within chromatin accessible regions (χ2 test p < 1 × 10- 55) identified by ATACseq. Formation of the identified HIF1α-DNA complexes paralleled the activation or repression of 526 genes, 116 of which contained HIF1α binding sites within 10kB of the transcription start sites. Some of the identified HIF1α genes have previously established lens functions while others have novel functions never before examined in the lens. GO and pathway analysis of these genes implicate HIF1α in the control of a wide-variety of cellular pathways potentially critical for lens fiber cell formation, structure and function including glycolysis, cell cycle regulation, chromatin remodeling, Notch and Wnt signaling, differentiation, development, and transparency. CONCLUSIONS These data establish the first functional map of genomic HIF1α-DNA complexes in the eye lens. They identify HIF1α as an important regulator of a wide-variety of genes previously shown to be critical for lens formation and function and they reveal a requirement for HIF1α in the regulation of a wide-variety of genes not yet examined for lens function. They support a requirement for HIF1α in lens fiber cell formation, structure and function and they provide a basis for understanding the potential roles and requirements for HIF1α in the development, structure and function of more complex tissues.
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Affiliation(s)
- Joshua Disatham
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431 USA
| | - Lisa Brennan
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431 USA
| | - Daniel Chauss
- Immunoregulation Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, MD 20892 USA
| | | | - Behdad Afzali
- Immunoregulation Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), NIH, Bethesda, MD 20892 USA
| | - Marc Kantorow
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd., Boca Raton, FL 33431 USA
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17
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Mechanisms of organelle elimination for lens development and differentiation. Exp Eye Res 2021; 209:108682. [PMID: 34214522 DOI: 10.1016/j.exer.2021.108682] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/03/2021] [Accepted: 06/19/2021] [Indexed: 12/23/2022]
Abstract
A hallmark feature of lens development and differentiation is the complete elimination of organelles from the center of the eye lens. A long unanswered question in lens biology is what are the mechanisms that control the elimination of organelles during the terminal remodeling program to form mature lens fiber cells? Recent advances have expanded our understanding of these mechanisms including newly discovered signaling pathways, proteasomal regulators, autophagy proteins, transcription factors and the hypoxic environment of the lens itself. These recent discoveries suggest that distinct mechanisms coordinate the elimination of the nucleus, mitochondria, endoplasmic reticulum and Golgi apparatus during lens fiber cell differentiation. Since regulation of organelle number and distribution is also a feature of the terminal remodeling programs of more complex cell-types and tissues, these advances are likely to impact a wide-variety of fields.
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18
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Hernandez-Bogantes E, Abdala-Figuerola A, Olivo-Payne A, Quiros F, Wu L. Cataract Following Pars Plana Vitrectomy: A Review. Semin Ophthalmol 2021; 36:824-831. [PMID: 34096468 DOI: 10.1080/08820538.2021.1924799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: The indications for pars plana vitrectomy (PPV) have increased over the years. The vitreous is no longer considered an inert ocular structure and it is well known that its removal has anatomical and physiological consequences. The vitreous is no longer considered an inert ocular structure. The vitreous plays a key role as an intraocular physiologic oxygen regulator. In order to maintain its transparency, the crystalline lens needs protection from an excessive oxygen exposure. PPV leads to progression of nuclear sclerosis in most eyes.Methods: A systematic review of the literature was conducted using Embase and Medline databases. Articles studying the physiology, pathogenesis and surgical treatment of cataract after PPV were included in this review.Results: The pathogenesis of cataract formation after PPV remains unclear. Predisposing factors include advanced patient age, preexisting nuclear sclerosis, light toxicity, intraoperative oxidation of lens proteins, use of silicone oil or intravitreal gas, mechanical trauma and the duration of exposure to an irrigating solution.Conclusion: Cataract surgery in vitrectomized eyes presents with more technical difficulties, is more challenging and often has a higher risk of intraoperative and postoperative complications than in non vitrectomized eyes. There is no standardized technique or management in these cases; therefore, it requires more precautions during surgery.
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Affiliation(s)
- Erick Hernandez-Bogantes
- Retina, Asociados De Macula Vitreo Y Retina De Costa Rica, San Jose, Costa Rica.,Centro Ocular, Heredia, Costa Rica
| | | | - Andrew Olivo-Payne
- Cuidad De Mexico, Insituto De Oftalmologia "Conde De Valenciana", Mexico City, Mexico
| | - Fabian Quiros
- Retina, Asociados De Macula Vitreo Y Retina De Costa Rica, San Jose, Costa Rica
| | - Lihteh Wu
- Retina, Asociados De Macula Vitreo Y Retina De Costa Rica, San Jose, Costa Rica.,Illinois Eye and Ear Infirmary, Dpt of Ophthalmology, University of Illinois School of Medicine, Chicago, Illinois, USA
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19
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Borchman D. Lipid conformational order and the etiology of cataract and dry eye. J Lipid Res 2021; 62:100039. [PMID: 32554545 PMCID: PMC7910524 DOI: 10.1194/jlr.tr120000874] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/15/2020] [Indexed: 12/12/2022] Open
Abstract
Lens and tear film lipids are as unique as the systems they reside in. The major lipid of the human lens is dihydrosphingomylein, found in quantity only in the lens. The lens contains a cholesterol to phospholipid molar ratio as high as 10:1, more than anywhere else in the body. Lens lipids contribute to maintaining lens clarity, and alterations in lens lipid composition due to age are likely to contribute to cataract. Lens lipid composition reflects adaptations to the unique characteristics of the lens: no turnover of lens lipids or proteins; the lowest amount of oxygen of any tissue; and contains almost no intracellular organelles. The tear film lipid layer (TFLL) is also unique. The TFLL is a thin (100 nm) layer of lipid on the surface of tears covering the cornea that contributes to tear film stability. The major lipids of the TFLL are wax esters and cholesterol esters that are not found in the lens. The hydrocarbon chains associated with the esters are longer than those found anywhere else in the body (as long as 32 carbons), and many are branched. Changes in the composition and structure of the 30,000 different moieties of TFLL contribute to the instability of tears. The focus of the current review is how spectroscopy has been used to elucidate the relationships between lipid composition, conformational order and function, and the etiology of cataract and dry eye.
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Affiliation(s)
- Douglas Borchman
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY 40202.
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20
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The Protective Effects of Flavonoids in Cataract Formation through the Activation of Nrf2 and the Inhibition of MMP-9. Nutrients 2020; 12:nu12123651. [PMID: 33261005 PMCID: PMC7759919 DOI: 10.3390/nu12123651] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 11/24/2020] [Accepted: 11/26/2020] [Indexed: 12/11/2022] Open
Abstract
Cataracts account for over half of global blindness. Cataracts formations occur mainly due to aging and to the direct insults of oxidative stress and inflammation to the eye lens. The nuclear factor-erythroid-2-related factor 2 (Nrf2), a transcriptional factor for cell cytoprotection, is known as the master regulator of redox homeostasis. Nrf2 regulates nearly 600 genes involved in cellular protection against contributing factors of oxidative stress, including aging, disease, and inflammation. Nrf2 was reported to disrupt the oxidative stress that activates Nuclear factor-κB (NFκB) and proinflammatory cytokines. One of these cytokines is matrix metalloproteinase 9 (MMP-9), which participates in the decomposition of lens epithelial cells (LECs) extracellular matrix and has been correlated with cataract development. Thus, during inflammatory processes, MMP production may be attenuated by the Nrf2 pathway or by the Nrf2 inhibition of NFκB pathway activation. Moreover, plant-based polyphenols have garnered attention due to their presumed safety and efficacy, nutritional, and antioxidant effects. Polyphenol compounds can activate Nrf2 and inhibit MMP-9. Therefore, this review focuses on discussing Nrf2's role in oxidative stress and cataract formation, epigenetic effect in Nrf2 activity, and the association between Nrf2 and MMP-9 in cataract development. Moreover, we describe the protective role of flavonoids in cataract formation, targeting Nrf2 activation and MMP-9 synthesis inhibition as potential molecular targets in preventing cataracts.
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21
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Paviani V, Junqueira de Melo P, Avakin A, Di Mascio P, Ronsein GE, Augusto O. Human cataractous lenses contain cross-links produced by crystallin-derived tryptophanyl and tyrosyl radicals. Free Radic Biol Med 2020; 160:356-367. [PMID: 32858158 DOI: 10.1016/j.freeradbiomed.2020.08.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 08/19/2020] [Indexed: 01/13/2023]
Abstract
Protein insolubilization, cross-linking and aggregation are considered critical to the development of lens opacity in cataract. However, the information about the presence of cross-links other than disulfides in cataractous lenses is limited. A potential role for cross-links produced from tryptophanyl radicals in cataract development is suggested by the abundance of the UV light-sensitive Trp residues in crystallin proteins. Here we developed a LC-MS/MS approach to examine the presence of Trp-Trp, Trp-Tyr and Tyr-Tyr cross-links and of peptides containing Trp-2H (-2.0156 Da) in the lens of three patients diagnosed with advanced nuclear cataract. In the proteins of two of the lenses, we characterized intermolecular cross-links between βB2-Tyr153-Tyr104-βA3 and βB2-Trp150-Tyr139-βS. An additional intermolecular cross-link (βB2-Tyr61-Trp200-βB3) was present in the lens of the oldest patient. In the proteins of all three lenses, we characterized two intramolecular Trp-Trp cross-links (Trp123-Trp126 in βB1 and Trp81-Trp84 in βB2) and six peptides containing Trp -2H residues, which indicate the presence of additional Trp-Trp cross-links. Relevantly, we showed that similar cross-links and peptides with modified Trp-2H residues are produced in a time-dependent manner in bovine β-crystallin irradiated with a solar simulator. Therefore, different crystallin proteins cross-linked by crystalline-derived tryptophanyl and tyrosyl radicals are present in advanced nuclear cataract lenses and similar protein modifications can be promoted by solar irradiation even in the absence of photosensitizers. Overall, the results indicate that a role for Trp-Tyr and Trp-Trp cross-links in the development of human cataract is possible and deserves further investigation.
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Affiliation(s)
- Verônica Paviani
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil
| | - Paulo Junqueira de Melo
- Hospital Das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 255, 05403-000, São Paulo, Brazil
| | - Amaryllis Avakin
- Hospital Das Clínicas, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar 255, 05403-000, São Paulo, Brazil
| | - Paolo Di Mascio
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil
| | - Graziella Eliza Ronsein
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
| | - Ohara Augusto
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
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22
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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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23
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Richardson RB, Ainsbury EA, Prescott CR, Lovicu FJ. Etiology of posterior subcapsular cataracts based on a review of risk factors including aging, diabetes, and ionizing radiation. Int J Radiat Biol 2020; 96:1339-1361. [DOI: 10.1080/09553002.2020.1812759] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Richard B. Richardson
- Radiobiology and Health Branch, Canadian Nuclear Laboratories (CNL), Chalk River, Canada
- McGill University’s Medical Physics Unit, Cedars Cancer Centre, Montreal, Canada
| | - Elizabeth A. Ainsbury
- Public Health England’s Centre for Chemical, Radiological and Environmental Hazards, Oxford, UK
| | | | - Frank J. Lovicu
- School of Medical Sciences, The University of Sydney, Sydney, Australia
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Hypoxia regulates the degradation of non-nuclear organelles during lens differentiation through activation of HIF1a. Exp Eye Res 2020; 198:108129. [PMID: 32628953 DOI: 10.1016/j.exer.2020.108129] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 06/05/2020] [Accepted: 06/23/2020] [Indexed: 12/31/2022]
Abstract
Formation of the eye lens depends on the continuous differentiation of lens epithelial cells into lens fiber cells. To attain their mature structure and transparent function, nascent lens fiber cells must complete a precise cellular remodeling program hallmarked by the complete elimination of organelles to form the core lens organelle-free zone (OFZ). Lacking a blood supply, the lens resides in a hypoxic environment that results in a decreasing oxygen concentration from the lens surface to the lens core. This oxygen gradient results in a hypoxic microenvironment in the region of the lens where immature lens fiber cells initiate loss of organelles to form the core OFZ. These features of the lens suggest a potential role for low lens oxygen levels in the regulation of organelle degradation and other events critical for mature lens fiber cell formation. Hypoxia activates the master regulator of the hypoxic response, hypoxia-inducible factor 1a (HIF1a) that regulates hypoxia-responsive genes. To identify a potential role for hypoxia and HIF1a in the elimination of organelles during lens fiber cell maturation, we tested the requirement for hypoxia in the degradation of non-nuclear organelles in ex vivo cultured embryonic chick lenses by monitoring the degradation of mitochondria (MT), Golgi apparatus (GA) and endoplasmic reticulum (ER) under conditions of low (1% O2) and high (21% O2) oxygen. We also examined the requirement for HIF1a activation for elimination of these organelles under the same conditions using a specific HIF1a activator (DMOG) and a specific HIF1a inhibitor (chetomin) and examined the requirements for hypoxia and HIF1a for regulating transcription of BNIP3L that we previously showed to be required for elimination of non-nuclear lens organelles. We used ChIP-qPCR to confirm direct binding of HIF1a to the 5' untranslated region of the BNIP3L gene. Finally, we examined the effects of expressing an oxygen insensitive mutant form of HIF1a (P402A/P565A) and BNIP3L on non-nuclear organelle degradation. Our data demonstrate that hypoxia and HIF1a are required for the degradation of non-nuclear organelles during lens fiber cell formation and that they regulate this process by governing BNIP3L transcription. Our results also provide evidence that hypoxia and HIF1a are essential for achieving mature lens structure.
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Zhuravleva YS, Morozova OB, Tsentalovich YP, Sherin PS. Proton-coupled electron transfer as the mechanism of reaction between triplet state of kynurenic acid and tryptophan. J Photochem Photobiol A Chem 2020. [DOI: 10.1016/j.jphotochem.2020.112522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Savina ED, Tsentalovich YP, Sherin PS. UV-A induced damage to lysozyme via Type I photochemical reactions sensitized by kynurenic acid. Free Radic Biol Med 2020; 152:482-493. [PMID: 31751763 DOI: 10.1016/j.freeradbiomed.2019.11.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 11/12/2019] [Accepted: 11/13/2019] [Indexed: 02/06/2023]
Abstract
In this work we studied the mechanisms of Type I photodamage to a model protein, hen egg white lysozyme (HEWL), sensitized by kynurenic acid (KNA) - one of the most efficient photosensitizers of the human eye lens present in trace amounts within tissue. The kynurenic acid radical, KNA•-, formed in the quenching of triplet KNA by HEWL, can be readily oxidized by molecular oxygen with the formation of superoxide anion radical O2•-. This leads to two ways of damage to proteins: either via the direct reactions between KNA•- and HEWL• radicals (Type Ia) or via the reactions between superoxide anion O2•- and HEWL• radicals (Type Ib). Our results demonstrate significant degradation of the protein during Type Ia photolysis with the formation of various oligomeric and oxygenated forms of HEWL and several deoxygenated products of KNA. Liquid chromatography-mass spectrometry analysis revealed the cross-linking of HEWL via tryptophan (Trp62) and tyrosine (Tyr23) residues and, for the first time, the covalent binding of KNA to protein via tryptophan (Trp62 and Trp123) residues. It was found that Type Ib reactions lead to substantially smaller damage to HEWL; the degradation quantum yields (Φdeg) of HEWL are 1.3 ± 0.3% and 0.12 ± 0.03% for Type Ia and Ib photolyses, respectively. Low Φdeg values for both types of photolysis indicate the Back Electron Transfer (BET) with the restoration of initial reagents as the main radical decay path with significantly higher BET efficiency in the case of Type Ib reactions. Therefore, in essentially oxygen-free tissues like the eye lens, the direct radical reactions via Type Ia mechanism could induce significantly larger damage to proteins, leading to their cross-linking and oxidation. The accumulation of these modifications can cause the development of various diseases, in particular, cataracts in the eye lens.
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Affiliation(s)
- Ekaterina D Savina
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090, Novosibirsk, Russia; Novosibirsk State University, Pirogova str. 2, 630090, Novosibirsk, Russia.
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Truscott RJW, Friedrich MG. Molecular Processes Implicated in Human Age-Related Nuclear Cataract. Invest Ophthalmol Vis Sci 2020; 60:5007-5021. [PMID: 31791064 PMCID: PMC7043214 DOI: 10.1167/iovs.19-27535] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Human age-related nuclear cataract is commonly characterized by four biochemical features that involve modifications to the structural proteins that constitute the bulk of the lens: coloration, oxidation, insolubility, and covalent cross-linking. Each of these is progressive and increases as the cataract worsens. Significant progress has been made in understanding the origin of the factors that underpin the loss of lens transparency. Of these four hallmarks of cataract, it is protein-protein cross-linking that has been the most intransigent, and it is only recently, with the advent of proteomic methodology, that mechanisms are being elucidated. A diverse range of cross-linking processes involving several amino acids have been uncovered. Although other hypotheses for the etiology of cataract have been advanced, it is likely that spontaneous decomposition of the structural proteins of the lens, which do not turn over, is responsible for the age-related changes to the properties of the lens and, ultimately, for cataract. Cataract may represent the first and best characterized of a number of human age-related diseases where spontaneous protein modification leads to ongoing deterioration and, ultimately, a loss of tissue function.
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Affiliation(s)
- Roger J W Truscott
- Illawarra Health and Medical Research Institute, University of Wollongong, Australia
| | - Michael G Friedrich
- Illawarra Health and Medical Research Institute, University of Wollongong, Australia
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Heruye SH, Maffofou Nkenyi LN, Singh NU, Yalzadeh D, Ngele KK, Njie-Mbye YF, Ohia SE, Opere CA. Current Trends in the Pharmacotherapy of Cataracts. Pharmaceuticals (Basel) 2020; 13:E15. [PMID: 31963166 PMCID: PMC7168925 DOI: 10.3390/ph13010015] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/09/2020] [Accepted: 01/10/2020] [Indexed: 12/23/2022] Open
Abstract
Cataracts, one of the leading causes of preventable blindness worldwide, refers to lens degradation that is characterized by clouding, with consequent blurry vision. As life expectancies improve, the number of people affected with cataracts is predicted to increase worldwide, especially in low-income nations with limited access to surgery. Although cataract surgery is considered safe, it is associated with some complications such as retinal detachment, warranting a search for cheap, pharmacological alternatives to the management of this ocular disease. The lens is richly endowed with a complex system of non-enzymatic and enzymatic antioxidants which scavenge reactive oxygen species to preserve lens proteins. Depletion and/or failure in this primary antioxidant defense system contributes to the damage observed in lenticular molecules and their repair mechanisms, ultimately causing cataracts. Several attempts have been made to counteract experimentally induced cataract using in vitro, ex vivo, and in vivo techniques. The majority of the anti-cataract compounds tested, including plant extracts and naturally-occurring compounds, lies in their antioxidant and/or free radical scavenging and/or anti-inflammatory propensity. In addition to providing an overview of the pathophysiology of cataracts, this review focuses on the role of various categories of natural and synthetic compounds on experimentally-induced cataracts.
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Affiliation(s)
- Segewkal H. Heruye
- Department of Pharmacology & Neuroscience, School of Medicine, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | - Leonce N. Maffofou Nkenyi
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | - Neetu U. Singh
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
| | | | - Kalu K. Ngele
- Department of Biology/Microbiology/Biotechnology, Federal University Ndufu Alike Ikwo, Abakaliki, Nigeria
| | - Ya-Fatou Njie-Mbye
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA
| | - Sunny E. Ohia
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX 77004, USA
| | - Catherine A. Opere
- Department of Pharmacy Sciences, School of Pharmacy and Health Professions, Creighton University, 2500 California Plaza, Omaha, NE 68178, USA
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Tsentalovich YP, Yanshole VV, Yanshole LV, Zelentsova EA, Melnikov AD, Sagdeev RZ. Seasonal Variations and Interspecific Differences in Metabolomes of Freshwater Fish Tissues: Quantitative Metabolomic Profiles of Lenses and Gills. Metabolites 2019; 9:E264. [PMID: 31684114 PMCID: PMC6918250 DOI: 10.3390/metabo9110264] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 10/30/2019] [Accepted: 10/31/2019] [Indexed: 02/07/2023] Open
Abstract
This work represents the first comprehensive report on quantitative metabolomic composition of tissues of pike-perch (Sander lucioperca) and Siberian roach (Rutilus rutilus lacustris). The total of 68 most abundant metabolites are identified and quantified in the fish lenses and gills by the combination of LC-MS and NMR. It is shown that the concentrations of some compounds in the lens are much higher than that in the gills; that indicates the importance of these metabolites for the adaptation to the specific living conditions and maintaining the homeostasis of the fish lens. The lens metabolome undergoes significant seasonal changes due to the variations of dissolved oxygen level and fish feeding activity. The most season-affected metabolites are osmolytes and antioxidants, and the most affected metabolic pathway is the histidine pathway. In late autumn, the major lens osmolytes are N-acetyl-histidine and threonine phosphoethanolamine (Thr-PETA), while in winter the highest concentrations were observed for serine phosphoethanolamine (Ser-PETA) and myo-inositol. The presence of Thr-PETA and Ser-PETA in fish tissues and their role in cell osmotic protection are reported for the first time. The obtained concentrations can be used as baseline levels for studying the influence of environmental factors on fish health.
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Affiliation(s)
- Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Vadim V Yanshole
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Lyudmila V Yanshole
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Ekaterina A Zelentsova
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Arsenty D Melnikov
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
| | - Renad Z Sagdeev
- International Tomography Center SB RAS, Institutskaya 3a, Novosibirsk 630090, Russia.
- Novosibirsk State University, Pirogova 2, Novosibirsk 630090, Russia.
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Muranov KO, Poliansky NB, Chebotareva NA, Kleimenov SY, Bugrova AE, Indeykina MI, Kononikhin AS, Nikolaev EN, Ostrovsky MA. The mechanism of the interaction of α-crystallin and UV-damaged β L-crystallin. Int J Biol Macromol 2019; 140:736-748. [PMID: 31445149 DOI: 10.1016/j.ijbiomac.2019.08.178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 08/18/2019] [Accepted: 08/20/2019] [Indexed: 12/24/2022]
Abstract
α-Crystallin maintains the transparency of the lens by preventing the aggregation of damaged proteins. The aim of our work was to study the chaperone-like activity of native α-crystallin in near physiological conditions (temperature, ionic power, pH) using UV-damaged βL-crystallin as the target protein. α-Crystallin in concentration depended manner inhibits the aggregation of UV-damaged βL-crystallin. DSC investigation has shown that refolding of denatured UV-damaged βL-crystallin was not observed under incubation with α-crystallin. α-Crystallin and UV-damaged βL-crystallin form dynamic complexes with masses from 75 to several thousand kDa. The content of UV-damaged βL-crystallin in such complexes increases with the mass of the complex. Complexes containing >10% of UV-damaged βL-crystallin are prone to precipitation whereas those containing <10% of the target protein are relatively stable. Formation of a stable 75 kDa complex is indicative of α-crystallin dissociation. We suppose that α-crystallin dissociation is the result of an interaction of comparable amounts of the chaperone-like protein and the target protein. In the lens simultaneous damage of such amounts of protein, mainly β and gamma-crystallins, is impossible. The authors suggest that in the lens rare molecules of the damaged protein interact with undissociated oligomers of α-crystallin, and thus preventing aggregation.
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Affiliation(s)
- K O Muranov
- Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia.
| | - N B Poliansky
- Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia
| | - N A Chebotareva
- Bach Institute of Biochemistry, Federal State Institution "Federal Research Centre "Fundamentals of Biotechnology"of the Russian Academy of Sciences", Moscow, Russia
| | - S Yu Kleimenov
- Koltzov Institute of Developmental Biology of the Russian Academy of Sciences, Russia
| | - A E Bugrova
- Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia
| | - M I Indeykina
- Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia; Talrose Institute for Energy Problems of Chemical Physics, Semenov Federal Center of Chemical Physic, Russian Academy of Sciences, Moscow, Russia
| | - A S Kononikhin
- Talrose Institute for Energy Problems of Chemical Physics, Semenov Federal Center of Chemical Physic, Russian Academy of Sciences, Moscow, Russia; Skolkovo Institute of Science and Technology, Skolkovo, Russia
| | - E N Nikolaev
- Talrose Institute for Energy Problems of Chemical Physics, Semenov Federal Center of Chemical Physic, Russian Academy of Sciences, Moscow, Russia; Skolkovo Institute of Science and Technology, Skolkovo, Russia
| | - M A Ostrovsky
- Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Moscow, Russia
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Siegfried CJ, Shui YB. Intraocular Oxygen and Antioxidant Status: New Insights on the Effect of Vitrectomy and Glaucoma Pathogenesis. Am J Ophthalmol 2019; 203:12-25. [PMID: 30772349 DOI: 10.1016/j.ajo.2019.02.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 02/03/2019] [Accepted: 02/06/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE The purpose of this study was to investigate correlations of partial pressure of oxygen (pO2) in the ocular anterior segment of human eyes and aqueous humor antioxidant levels of ascorbate (AsA) and total reactive antioxidant potential (TRAP) with glaucoma and vitreous status. METHODS This prospective, cross-sectional study stratified patients (n = 288 eyes) by lens and vitreous status and the presence of primary open-angle glaucoma for statistical analyses. Intraocular pO2 concentrations were measured using a fiberoptic probe in patients at the beginning of planned glaucoma and/or cataract surgery. Aqueous humor specimens were obtained for antioxidant analysis of AsA and TRAP. RESULTS Following prior pars plana vitrectomy, pO2 levels were significantly higher than in the reference group of cataract surgery in the anterior chamber angle (16.2 ± 5.0 vs. 13.0 ± 3.9 mm Hg; P = .0171) and in the posterior chamber (7.6 ± 3.1 vs. 3.9 ± 2.7 mm Hg; P < .0001). AsA and TRAP levels were significantly lower (1.1 ± 0.4 vs. 1.4 ± 0.5 mM, respectively; 403.3 ±116.5 vs. 479.0 ± 146.7 Trolox units, respectively; P = .004 and P = .024, respectively) in patients after vitrectomy. In patients with an intact vitreous, neither pO2 nor antioxidant status correlated with lens status or glaucoma. CONCLUSIONS Increased pO2 and antioxidant depletion following vitrectomy suggests an alteration of the intraocular oxidant-antioxidant balance. Our study links physiologic factors such as increased pO2 in the anterior chamber angle and the posterior chamber to decreased antioxidant levels in aqueous humor following vitrectomy. Oxidative stress/damage to the trabecular meshwork in such post-vitrectomy cases may contribute to intraocular pressure elevation and increased risk of glaucoma. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.
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Affiliation(s)
- Carla J Siegfried
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri.
| | - Ying-Bo Shui
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri
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Rats deficient in α-galactosidase A develop ocular manifestations of Fabry disease. Sci Rep 2019; 9:9392. [PMID: 31253878 PMCID: PMC6599056 DOI: 10.1038/s41598-019-45837-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/12/2019] [Indexed: 12/17/2022] Open
Abstract
Fabry disease is an X-linked lysosomal storage disease caused by deficiency of α-galactosidase A. Ocular findings, such as cornea verticillata, cataracts, and retinal vascular tortuosity, serve as important diagnostic markers. We aimed to evaluate ocular phenotypes in α-galactosidase A-deficient (Fabry) rats and hypothesized that these rats would manifest ocular signs similar to those observed in patients. Slit lamp biomicroscopy was used to evaluate the cornea and lens, and retinal vasculature was examined by fluorescein angiography in WT and Fabry rats. Mass spectrometry was used to characterize and quantify ocular glycosphingolipids, and histology and electron microscopy revealed the location of the glycosphingolipid storage. We found that Fabry rats developed corneal and lenticular opacities to a statistically greater degree than WT rats. Retinal vascular morphology did not appear grossly different, but there was vascular leakage in at least one Fabry rat. Fabry rat eyes accumulated substrates of α-galactosidase A, and these α-galactosyl glycoconjugates were found in corneal keratocytes, lens fibers, and retinal vascular endothelial cells. Electron-dense lamellar inclusions were observed in keratocytes. Because Fabry rats recapitulate many ocular phenotypes observed in patients, they can be used to study disease pathogenesis and determine whether ocular findings serve as noninvasive indicators of therapeutic efficacy.
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Why Is Very High Cholesterol Content Beneficial for the Eye Lens but Negative for Other Organs? Nutrients 2019; 11:nu11051083. [PMID: 31096723 PMCID: PMC6566707 DOI: 10.3390/nu11051083] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 12/13/2022] Open
Abstract
The plasma membranes of the human lens fiber cell are overloaded with cholesterol that not only saturates the phospholipid bilayer of these membranes but also leads to the formation of pure cholesterol bilayer domains. Cholesterol level increases with age, and for older persons, it exceeds the cholesterol solubility threshold, leading to the formation of cholesterol crystals. All these changes occur in the normal lens without too much compromise to lens transparency. If the cholesterol content in the cell membranes of other organs increases to extent where cholesterol crystals forma, a pathological condition begins. In arterial cells, minute cholesterol crystals activate inflammasomes, induce inflammation, and cause atherosclerosis development. In this review, we will indicate possible factors that distinguish between beneficial and negative cholesterol action, limiting cholesterol actions to those performed through cholesterol in cell membranes and by cholesterol crystals.
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Zhu Y, Xu S, Eisenberg RS, Huang H. A Bidomain Model for Lens Microcirculation. Biophys J 2019; 116:1171-1184. [PMID: 30850115 DOI: 10.1016/j.bpj.2019.02.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 12/03/2018] [Accepted: 02/13/2019] [Indexed: 10/27/2022] Open
Abstract
There exists a large body of research on the lens of the mammalian eye over the past several decades. The objective of this work is to provide a link between the most recent computational models and some of the pioneering work in the 1970s and 80s. We introduce a general nonelectroneutral model to study the microcirculation in the lens of the eye. It describes the steady-state relationships among ion fluxes, between water flow and electric field inside cells, and in the narrow extracellular spaces between cells in the lens. Using asymptotic analysis, we derive a simplified model based on physiological data and compare our results with those in the literature. We show that our simplified model can be reduced further to the first-generation models, whereas our full model is consistent with the most recent computational models. In addition, our simplified model captures in its equations the main features of the full computational models. Our results serve as a useful link intermediate between the computational models and the first-generation analytical models. Simplified models of this sort may be particularly helpful as the roles of similar osmotic pumps of microcirculation are examined in other tissues with narrow extracellular spaces, such as cardiac and skeletal muscle, liver, kidney, epithelia in general, and the narrow extracellular spaces of the central nervous system, the "brain." Simplified models may reveal the general functional plan of these systems before full computational models become feasible and specific.
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Affiliation(s)
- Yi Zhu
- Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada
| | - Shixin Xu
- Centre for Quantitative Analysis and Modelling, Fields Institute for Research in Mathematical Sciences, Toronto, Ontario, Canada.
| | - Robert S Eisenberg
- Department of Applied Mathematics, Illinois Institute of Technology, Chicago, Illinois; Department of Physiology and Biophysics, Rush University, Chicago, Illinois
| | - Huaxiong Huang
- Department of Mathematics and Statistics, York University, Toronto, Ontario, Canada; Centre for Quantitative Analysis and Modelling, Fields Institute for Research in Mathematical Sciences, Toronto, Ontario, Canada
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Ficarrotta KR, Bello SA, Mohamed YH, Passaglia CL. Aqueous Humor Dynamics of the Brown-Norway Rat. Invest Ophthalmol Vis Sci 2019; 59:2529-2537. [PMID: 29847660 PMCID: PMC5967599 DOI: 10.1167/iovs.17-22915] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The study aimed to provide a quantitative description of aqueous humor dynamics in healthy rat eyes. Methods One eye of 26 anesthetized adult Brown-Norway rats was cannulated with a needle connected to a perfusion pump and pressure transducer. Pressure-flow data were measured in live and dead eyes by varying pump rate (constant-flow technique) or by modulating pump duty cycle to hold intraocular pressure (IOP) at set levels (modified constant-pressure technique). Data were fit by the Goldmann equation to estimate conventional outflow facility (\begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document}) and unconventional outflow rate (\begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document}). Parameter estimates were respectively checked by inserting a shunt of similar conductance into the eye and by varying eye hydration methodology. Results Rat IOP averaged 14.6 ± 1.9 mm Hg at rest. Pressure-flow data were repeatable and indistinguishable for the two perfusion techniques, yielding \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} = 0.023 ± 0.002 μL/min/mm Hg and \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} = 0.096 ± 0.024 μL/min. \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} was similar for live and dead eyes and increased upon shunt insertion by an amount equal to shunt conductance, validating measurement accuracy. At 100% humidity \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} dropped to 0.003 ± 0.030 μL/min. Physiological washout was not observed (−0.35 ± 0.65%/h), and trabecular anatomy looked normal. Conclusions Rat aqueous humor dynamics are intermediate in magnitude compared to those in mice and humans, consistent with species differences in eye size. \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}C\end{document} does not change with time or death. Evaporation complicates measurement of \begin{document}\newcommand{\bialpha}{\boldsymbol{\alpha}}\newcommand{\bibeta}{\boldsymbol{\beta}}\newcommand{\bigamma}{\boldsymbol{\gamma}}\newcommand{\bidelta}{\boldsymbol{\delta}}\newcommand{\bivarepsilon}{\boldsymbol{\varepsilon}}\newcommand{\bizeta}{\boldsymbol{\zeta}}\newcommand{\bieta}{\boldsymbol{\eta}}\newcommand{\bitheta}{\boldsymbol{\theta}}\newcommand{\biiota}{\boldsymbol{\iota}}\newcommand{\bikappa}{\boldsymbol{\kappa}}\newcommand{\bilambda}{\boldsymbol{\lambda}}\newcommand{\bimu}{\boldsymbol{\mu}}\newcommand{\binu}{\boldsymbol{\nu}}\newcommand{\bixi}{\boldsymbol{\xi}}\newcommand{\biomicron}{\boldsymbol{\micron}}\newcommand{\bipi}{\boldsymbol{\pi}}\newcommand{\birho}{\boldsymbol{\rho}}\newcommand{\bisigma}{\boldsymbol{\sigma}}\newcommand{\bitau}{\boldsymbol{\tau}}\newcommand{\biupsilon}{\boldsymbol{\upsilon}}\newcommand{\biphi}{\boldsymbol{\phi}}\newcommand{\bichi}{\boldsymbol{\chi}}\newcommand{\bipsi}{\boldsymbol{\psi}}\newcommand{\biomega}{\boldsymbol{\omega}}{F_{un}}\end{document} even when eyes are not enucleated. Absence of washout is a notable finding seen only in mouse and human eyes to date.
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Affiliation(s)
- Kayla R Ficarrotta
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Simon A Bello
- Electrical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Youssef H Mohamed
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States
| | - Christopher L Passaglia
- Chemical and Biomedical Engineering Department, University of South Florida, Tampa, Florida, United States.,Ophthalmology Department, University of South Florida, Tampa, Florida, United States
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36
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Kozłowski TM, Kröger RHH. Visualization of adult fish lens fiber cells. Exp Eye Res 2018; 181:1-4. [PMID: 30579924 DOI: 10.1016/j.exer.2018.12.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/09/2018] [Accepted: 12/19/2018] [Indexed: 11/30/2022]
Abstract
The crystalline lens of a vertebrate eye is a gradient-index lens and grows throughout life by addition of new lens fiber cells in the periphery. In fish, the growing ball-shaped lens maintains sophisticated optical properties throughout life by maintaining the distribution of refractive index relative to the increasing radius of the lens. During this process, the central fibers must increase refractive index by increasing the cytosolic concentration of crystallin proteins. However, only the youngest, most peripheral lens fiber cells have the ability to synthesize proteins. Unfortunately, the hardness of fish lenses makes investigation of the cellular anatomy impossible with traditional histological methods. We have developed a method for visualizing lens fiber cells across the diameter of the lens in adult fish. The method relies on sectioning embedded lenses with a high-speed power saw and observing the cut surface with a scanning electron microscope (SEM). The combination of SEM and image analysis allowed for precise tracking of the positions of individual cell fiber cells. As an application of the method, we present a cell thickness profile, i.e. the distribution of cells thicknesses and their relative positions along the lens's radius. Combined with detailed optical studies, which by mathematical reasons only are possible on ball-shaped lenses, our method can lead to new insights into the mechanism governing the functional and cellular development of vertebrate lenses.
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Affiliation(s)
- Tomasz M Kozłowski
- Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, 22362, Lund, Sweden.
| | - Ronald H H Kröger
- Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, 22362, Lund, Sweden
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37
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Lee JH, Lee JY, Bae JH, Kim JM. Positional Intraocular Pressure of Vitrectomized and Normal Fellow Eyes. KOREAN JOURNAL OF OPHTHALMOLOGY 2018; 32:409-416. [PMID: 30311464 PMCID: PMC6182206 DOI: 10.3341/kjo.2017.0136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 01/09/2018] [Indexed: 11/23/2022] Open
Abstract
Purpose To compare posture-induced intraocular pressure (IOP) changes in vitrectomized eyes and normal eyes of patients who had vitrectomy in one eye. Methods A total of 31 patients older than 20 years of age who underwent vitrectomy were enrolled in the study. At least six months after vitrectomy, we measured IOP in both eyes using a rebound tonometer 10 minutes after the patient assumed sitting, supine, right lateral decubitus, and left lateral decubitus positions. Patients with a history of ocular surgery (not including vitrectomy) or recent medication use associated with IOP were excluded. IOP and ocular parameters of vitrectomized and normal fellow eyes were compared. For the decubitus position, IOP values of dependent and nondependent eyes were compared. Results No significant difference was observed in IOP between vitrectomized and normal eyes in the sitting and supine positions. The IOP for dependent eyes (on the lower side in the lateral decubitus position) was significantly higher than the IOP for nondependent eyes in both right lateral decubitus (right vitrectomized eye 19.31 ± 4.20 vs. 16.71 ± 4.02 mmHg, p < 0.001; left vitrectomized eye 18.35 ± 1.75 vs. 16.04 ± 3.02 mmHg, p = 0.003) and left lateral decubitus (right vitrectomized eye 17.32 ± 4.63 vs. 19.15 ± 3.83 mmHg, p = 0.004; left vitrectomized eye 16.19 ± 1.81 vs. 18.12 ± 2.29 mmHg, p < 0.001) positions. Conclusions IOP was higher in the dependent than the nondependent eye in the lateral decubitus position, for both vitrectomized and nonoperated eyes.
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Affiliation(s)
- Jae Hyuck Lee
- Department of Ophthalmology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jae Yeun Lee
- Department of Ophthalmology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jeong Hun Bae
- Department of Ophthalmology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Joon Mo Kim
- Department of Ophthalmology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
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38
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Wang S, Guo C, Yu M, Ning X, Yan B, Zhao J, Yang A, Yan H. Identification of H 2O 2 induced oxidative stress associated microRNAs in HLE-B3 cells and their clinical relevance to the progression of age-related nuclear cataract. BMC Ophthalmol 2018; 18:93. [PMID: 29653565 PMCID: PMC5899325 DOI: 10.1186/s12886-018-0766-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 04/03/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND This study is aimed to screen out the microRNAs (miRNAs) associated with H2O2 induced oxidative stress in human lens epithelial B3 (HLE-B3) cell lines and investigate their relations with the progression of age-related nuclear cataract. METHODS H2O2 was used to induce oxidative stress in HLE-B3 cells. A genome-wide expression profiling of miRNAs in HLE-B3 cells was performed to select the differentially expressed miRNAs before and after H2O2 treatment. The selected miRNAs were validated by RT-PCR and fluorescence in situ hybridization (FISH). Clinical specimens were divided into three groups according to the Lens Opacities Classification System III (LOCSIII) and the expression levels of the selected miRNAs were tested by RT-PCR in the three groups. Bioinformatics analyses were applied to predict the target genes of the miRNA hits and construct the miRNA regulatory network. The expression level of MAPK14 was analyzed by Western blot. RESULTS The H2O2 induced oxidative stress model of HLE-B3 cells was established. Nineteen upregulated and 30 downregulated miRNAs were identified as differentially expressed miRNAs. Seven of the total 49 were validated in the cell model. RT-PCR of the clinical samples showed that the expression levels of miR-34a-5p, miR-630 and miR-335-3p were closely related with the severity of nuclear opacity. The images taken from FISH confirmed the results of RT-PCR. There were 172 target genes of the three miRNAs clustered in the category of response to stress. The regulatory network demonstrated that 23 target genes were co-regulated by multiple miRNAs. MAPK14 was the target gene of three miRNAs and the result were verified by Western blot. CONCLUSION Up-regulation of miR-34a-5p and miR-630 and down-regulation of miR-335-3p are related with the progression of age-related nuclear cataract and the underlying mechanism awaits further functional research to reveal.
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Affiliation(s)
- Song Wang
- Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, 1 Xinsi Road, Xi'an, Shaanxi, 710038, People's Republic of China
| | - Chenjun Guo
- Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, 1 Xinsi Road, Xi'an, Shaanxi, 710038, People's Republic of China
| | - Mengsi Yu
- Department of Dermatology, Xijing Hospital, Fourth Military Medical University, 169 West Changle Road, Xi'an, Shaanxi, 710032, People's Republic of China
| | - Xiaona Ning
- Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, 1 Xinsi Road, Xi'an, Shaanxi, 710038, People's Republic of China
| | - Bo Yan
- The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, 169 West Changle Road, Xi'an, Shaanxi, 710032, People's Republic of China
| | - Jing Zhao
- The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, 169 West Changle Road, Xi'an, Shaanxi, 710032, People's Republic of China
| | - Angang Yang
- The State Key Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Fourth Military Medical University, 169 West Changle Road, Xi'an, Shaanxi, 710032, People's Republic of China
| | - Hong Yan
- Department of Ophthalmology, Tangdu Hospital, Fourth Military Medical University, 1 Xinsi Road, Xi'an, Shaanxi, 710038, People's Republic of China. .,Chongqing Key Laboratory of Ophthalmology and Chongqing Eye Institute, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Chongqing, 400016, People's Republic of China.
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39
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Sormacheva ED, Sherin PS, Tsentalovich YP. Dimerization and oxidation of tryptophan in UV-A photolysis sensitized by kynurenic acid. Free Radic Biol Med 2017; 113:372-384. [PMID: 29024806 DOI: 10.1016/j.freeradbiomed.2017.10.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 11/24/2022]
Abstract
Photoinduced generation of radicals in the eye lens may play an important role in the modification of proteins leading to their coloration, aggregation, and insolubilization. The radicals can be formed via the reactions of photoexcited endogenous chromophores of the human lens with lens proteins, in particular with tryptophan residues. In the present work we studied the reactions induced by UV-A (315-400nm) light between kynurenic acid (KNA), an effective photosensitizer present in the human lens, and N-acetyl-L-tryptophan (NTrpH) under aerobic and anaerobic conditions. Our results show that the reaction mechanism strongly depends on the presence of oxygen in solution. Under aerobic conditions, the generation of singlet oxygen is the major channel of the effective NTrpH oxidation. In argon-bubbled solutions, the quenching of triplet KNA by NTrpH results in the formation of KNA•- and NTrp• radicals. Under laser pulse irradiation, when the radical concentration is high, the main pathway of the radical decay is the back electron transfer with the restoration of initial reagents. Other reactions include (i) the radical combination yielding NTrp dimers and (ii) the oxygen atom transfer from KNA•- to NTrp• with the formation of oxidized NTrp species and deoxygenated KNA products. In continuous-wave photolysis, even trace amounts of molecular oxygen are sufficient to oxidize the majority of KNA•- radicals with the rate constant of (2.0 ± 0.2) × 109M-1s-1, leading to the restoration of KNA and the formation of superoxide radical O2•-. The latter reacts with NTrp• via either the radical combination to form oxidized NTrp (minor pathway), or the electron transfer to restore NTrpH in the ground state (major pathway). As the result, the quantum yields of the starting compound decomposition under continuous-wave anaerobic photolysis are rather low: 1.6% for NTrpH and 0.02% for KNA. The photolysis of KNA with alpha-crystallin yields the same deoxygenated KNA products as the photolysis of KNA with NTrpH, indicating the similarity of the photolysis mechanisms. Thus, inside the eye lens KNA can sensitize both protein photooxidation and protein covalent cross-linking with the minor self-degradation. This may play an important role in the lens protein modifications during the normal aging and cataract development.
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Affiliation(s)
- Ekaterina D Sormacheva
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia
| | - Peter S Sherin
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia.
| | - Yuri P Tsentalovich
- International Tomography Center SB RAS, Institutskaya str. 3A, 630090 Novosibisrk, Russia; Novosibirsk State University, Pirogova str. 2, 630090 Novosibisrk, Russia
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40
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Kubo E, Chhunchha B, Singh P, Sasaki H, Singh DP. Sulforaphane reactivates cellular antioxidant defense by inducing Nrf2/ARE/Prdx6 activity during aging and oxidative stress. Sci Rep 2017; 7:14130. [PMID: 29074861 PMCID: PMC5658327 DOI: 10.1038/s41598-017-14520-8] [Citation(s) in RCA: 139] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/11/2017] [Indexed: 12/21/2022] Open
Abstract
Upon oxidative stress and aging, Nrf2 (NFE2-related factor2) triggers antioxidant defense genes to defends against homeostatic failure. Using human(h) or rat(r) lens epithelial cells (LECs) and aging human lenses, we showed that a progressive increase in oxidative load during aging was linked to a decline in Prdx6 expression. DNA binding experiments using gel-shift and ChIP assays demonstrated a progressive reduction in Nrf2/ARE binding (-357/-349) of Prdx6 promoter. The promoter (-918) with ARE showed a marked reduction in young vs aged hLECs, which was directly correlated to decreased Nrf2/ARE binding. A Nrf2 activator, Sulforaphane (SFN), augmented Prdx6, catalase and GSTπ expression in dose-dependent fashion, and halted Nrf2 dysregulation of these antioxidants. SFN reinforced Nrf2/DNA binding and increased promoter activities by enhancing expression and facilitating Nrf2 translocalization in nucleus. Conversely, promoter mutated at ARE site did not respond to SFN, validating the SFN-mediated restoration of Nrf2/ARE signaling. Furthermore, SFN rescued cells from UVB-induced toxicity in dose-dependent fashion, which was consistent with SFN's dose-dependent activation of Nrf2/ARE interaction. Importantly, knockdown of Prdx6 revealed that Prdx6 expression was prerequisite for SFN-mediated cytoprotection. Collectively, our results suggest that loss of Prdx6 caused by dysregulation of ARE/Nrf2 can be attenuated through a SFN, to combat diseases associated with aging.
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Affiliation(s)
- Eri Kubo
- Department of Ophthalmology, Kanazawa Medical University, Kanazawa, Japan.
| | - Bhavana Chhunchha
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, NE, Omaha, USA
| | - Prerna Singh
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, NE, Omaha, USA
| | - Hiroshi Sasaki
- Department of Ophthalmology, Kanazawa Medical University, Kanazawa, Japan
| | - Dhirendra P Singh
- Department of Ophthalmology and Visual Science, University of Nebraska Medical Center, NE, Omaha, USA.
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Plesnar E, Szczelina R, Subczynski WK, Pasenkiewicz-Gierula M. Is the cholesterol bilayer domain a barrier to oxygen transport into the eye lens? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:434-441. [PMID: 29079282 DOI: 10.1016/j.bbamem.2017.10.020] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/20/2017] [Accepted: 10/23/2017] [Indexed: 11/16/2022]
Abstract
In the eye lens, the oxygen partial pressure is very low and the cholesterol (Chol) content in cell membranes is very high. Disturbance of these quantities results in cataract development. In human lens membranes, both bulk phospholipid-Chol domains and the pure Chol bilayer domains (CBDs) were experimentally detected. It is hypothesized that the CBD constitutes a significant barrier to oxygen transport into the lens. Transmembrane profiles of the oxygen diffusion-concentration product, obtained with electron paramagnetic resonance spin-labeling methods, allow evaluation of the oxygen permeability (PM) of phospholipid membranes but not the CBD. Molecular dynamics simulation can independently provide components of the product across any bilayer domain, thus allowing evaluation of the PM across the CBD. Therefore, to test the hypothesis, MD simulation was used. Three bilayers containing palmitoyl-oleoyl-phosphorylcholine (POPC) and Chol were built. The pure Chol bilayer modeled the CBD, the 1:1 POPC-Chol bilayer modeled the bulk membrane in which the CBD is embedded, and the POPC bilayer was a reference. To each model, 200 oxygen molecules were added. After equilibration, the oxygen concentration and diffusion profiles were calculated for each model and multiplied by each other. From the respective product profiles, the PM of each bilayer was calculated. Favorable comparison with experimental data available only for the POPC and POPC-Chol bilayers validated these bilayer models and allowed the conclusion that oxygen permeation across the CBD is ~10 smaller than across the bulk membrane, supporting the hypothesis that the CBD is a barrier to oxygen transport into the eye lens.
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Affiliation(s)
- Elzbieta Plesnar
- Department of Computational Biophysics and Bioinformatics, WBBiB, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland.
| | - Robert Szczelina
- Department of Bioinformatics, MCB, Jagiellonian University, Gronostajowa 7A, 30-387 Krakow, Poland.
| | - Witold K Subczynski
- Department of Biophysics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
| | - Marta Pasenkiewicz-Gierula
- Department of Computational Biophysics and Bioinformatics, WBBiB, Jagiellonian University, Gronostajowa 7, 30-387 Krakow, Poland.
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Borchman D, Stimmelmayr R, George JC. Whales, lifespan, phospholipids, and cataracts. J Lipid Res 2017; 58:2289-2298. [PMID: 29038122 DOI: 10.1194/jlr.m079368] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/04/2017] [Indexed: 12/18/2022] Open
Abstract
This study addresses the question: why do rats get cataracts at 2 years, dogs at 8 years, and whales do not develop cataracts for 200 years? Whale lens lipid phase transitions were compared with the phase transitions of other species that were recalculated. The major phospholipids of the whale lens were sphingolipids, mostly dihydrosphingomyelins with an average molar cholesterol/phospholipid ratio of 10. There was a linear correlation between the percentage of lens sphingolipid and lens lipid hydrocarbon chain order until about 60% sphingolipid. The percentage of lens sphingolipid correlated with the lens lipid phase transition temperature. The lifespan of the bowhead whale was the longest of the species measured and the percentage of whale lens sphingolipid fit well in the correlation between the percentage of lens sphingolipid and lifespan for many species. In conclusion, bowhead whale lens membranes have a high sphingolipid content that confers resistance to oxidation, allowing these lenses to stay clear relatively longer than many other species. The strong correlation between sphingolipid and lifespan may form a basis for future studies, which are needed because correlations do not infer cause. One could hope that if human lenses could be made to have a lipid composition similar to whales, like the bowhead, humans would not develop age-related cataracts for over 100 years.
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Affiliation(s)
- Douglas Borchman
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY
| | - Raphaela Stimmelmayr
- Department of Wildlife Management, North Slope Borough, Utqiagvik, AK.,Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK
| | - J Craig George
- Department of Wildlife Management, North Slope Borough, Utqiagvik, AK
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Periyasamy P, Shinohara T. Age-related cataracts: Role of unfolded protein response, Ca 2+ mobilization, epigenetic DNA modifications, and loss of Nrf2/Keap1 dependent cytoprotection. Prog Retin Eye Res 2017; 60:1-19. [PMID: 28864287 PMCID: PMC5600869 DOI: 10.1016/j.preteyeres.2017.08.003] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/26/2017] [Accepted: 08/28/2017] [Indexed: 12/11/2022]
Abstract
Age-related cataracts are closely associated with lens chronological aging, oxidation, calcium imbalance, hydration and crystallin modifications. Accumulating evidence indicates that misfolded proteins are generated in the endoplasmic reticulum (ER) by most cataractogenic stresses. To eliminate misfolded proteins from cells before they can induce senescence, the cells activate a clean-up machinery called the ER stress/unfolded protein response (UPR). The UPR also activates the nuclear factor-erythroid-2-related factor 2 (Nrf2), a central transcriptional factor for cytoprotection against stress. Nrf2 activates nearly 600 cytoprotective target genes. However, if ER stress reaches critically high levels, the UPR activates destructive outputs to trigger programmed cell death. The UPR activates mobilization of ER-Ca2+ to the cytoplasm and results in activation of Ca2+-dependent proteases to cleave various enzymes and proteins which cause the loss of normal lens function. The UPR also enhances the overproduction of reactive oxygen species (ROS), which damage lens constituents and induce failure of the Nrf2 dependent cytoprotection. Kelch-like ECH-associated protein 1 (Keap1) is an oxygen sensor protein and regulates the levels of Nrf2 by the proteasomal degradation. A significant loss of DNA methylation in diabetic cataracts was found in the Keap1 promoter, which overexpresses the Keap1 protein. Overexpressed Keap1 significantly decreases the levels of Nrf2. Lower levels of Nrf2 induces loss of the redox balance toward to oxidative stress thereby leading to failure of lens cytoprotection. Here, this review summarizes the overall view of ER stress, increases in Ca2+ levels, protein cleavage, and loss of the well-established stress protection in somatic lens cells.
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Affiliation(s)
- Palsamy Periyasamy
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA; Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Toshimichi Shinohara
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA
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Influence of Cholesterol on the Oxygen Permeability of Membranes: Insight from Atomistic Simulations. Biophys J 2017; 112:2336-2347. [PMID: 28591606 PMCID: PMC5474842 DOI: 10.1016/j.bpj.2017.04.046] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 04/26/2017] [Accepted: 04/28/2017] [Indexed: 12/31/2022] Open
Abstract
Cholesterol is widely known to alter the physical properties and permeability of membranes. Several prior works have implicated cell membrane cholesterol as a barrier to tissue oxygenation, yet a good deal remains to be explained with regard to the mechanism and magnitude of the effect. We use molecular dynamics simulations to provide atomic-resolution insight into the influence of cholesterol on oxygen diffusion across and within the membrane. Our simulations show strong overall agreement with published experimental data, reproducing the shapes of experimental oximetry curves with high accuracy. We calculate the upper-limit transmembrane oxygen permeability of a 1-palmitoyl,2-oleoylphosphatidylcholine phospholipid bilayer to be 52 ± 2 cm/s, close to the permeability of a water layer of the same thickness. With addition of cholesterol, the permeability decreases somewhat, reaching 40 ± 2 cm/s at the near-saturating level of 62.5 mol % cholesterol and 10 ± 2 cm/s in a 100% cholesterol mimic of the experimentally observed noncrystalline cholesterol bilayer domain. These reductions in permeability can only be biologically consequential in contexts where the diffusional path of oxygen is not water dominated. In our simulations, cholesterol reduces the overall solubility of oxygen within the membrane but enhances the oxygen transport parameter (solubility-diffusion product) near the membrane center. Given relatively low barriers to passing from membrane to membrane, our findings support hydrophobic channeling within membranes as a means of cellular and tissue-level oxygen transport. In such a membrane-dominated diffusional scheme, the influence of cholesterol on oxygen permeability is large enough to warrant further attention.
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Cholesterol Bilayer Domains in the Eye Lens Health: A Review. Cell Biochem Biophys 2017; 75:387-398. [PMID: 28660427 PMCID: PMC5691107 DOI: 10.1007/s12013-017-0812-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/15/2017] [Indexed: 11/06/2022]
Abstract
The most unique biochemical characteristic of the eye lens fiber cell plasma membrane is its extremely high cholesterol content, the need for which is still unclear. It is evident, however, that the disturbance of Chol homeostasis may result in damages associated with cataracts. Electron paramagnetic resonance methods allow discrimination of two types of lipid domains in model membranes overloaded with Chol, namely, phospholipid-cholesterol domains and pure Chol bilayer domains. These domains are also detected in human lens lipid membranes prepared from the total lipids extracted from lens cortices and nuclei of donors from different age groups. Independent of the age-related changes in phospholipid composition, the physical properties of phospholipid-Chol domains remain the same for all age groups and are practically identical for cortical and nuclear membranes. The presence of Chol bilayer domains in these membranes provides a buffering capacity for cholesterol concentration in the surrounding phospholipid-Chol domains, keeping it at a constant saturating level and thus keeping the physical properties of the membrane consistent with and independent of changes in phospholipid composition. It seems that the presence of Chol bilayer domains plays an integral role in the regulation of cholesterol-dependent processes in fiber cell plasm membranes and in the maintenance of fiber cell membrane homeostasis.
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Bello SA, Malavade S, Passaglia CL. Development of a Smart Pump for Monitoring and Controlling Intraocular Pressure. Ann Biomed Eng 2017; 45:990-1002. [PMID: 27679446 PMCID: PMC5364042 DOI: 10.1007/s10439-016-1735-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 09/12/2016] [Indexed: 10/20/2022]
Abstract
Animal models of ocular hypertension are important for glaucoma research but come with experimental costs. Available methods of intraocular pressure (IOP) elevation are not always successful, the amplitude and time course of IOP changes are unpredictable and irreversible, and IOP measurement by tonometry is laborious. Here we present a novel system for monitoring and controlling IOP without these limitations. It consists of a cannula implanted in the anterior chamber of the eye, a pressure sensor that continually measures IOP, and a bidirectional pump driven by control circuitry that can infuse or withdraw fluid to hold IOP at user-desired levels. A portable version was developed for tethered use on rats. We show that rat eyes can be cannulated for months without causing significant anatomical or physiological damage although the animal and its eyes freely move. We show that the system measures IOP with <0.7 mmHg resolution and <0.3 mmHg/month drift and can maintain IOP within a user-specified window of desired levels for any duration necessary. We conclude that the system is ready for cage- or bench-side applications. The results lay the foundation for an implantable version that would give glaucoma researchers unprecedented knowledge and control of IOP in rats and potentially larger animals.
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Affiliation(s)
- Simon A Bello
- Department of Chemical & Biomedical Engineering, University of South Florida, 4202 E Fowler Ave, Tampa, FL, 33620, USA
| | - Sharad Malavade
- Department of Ophthalmology, University of South Florida, Tampa, FL, 33620, USA
| | - Christopher L Passaglia
- Department of Chemical & Biomedical Engineering, University of South Florida, 4202 E Fowler Ave, Tampa, FL, 33620, USA.
- Department of Ophthalmology, University of South Florida, Tampa, FL, 33620, USA.
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Srivastava OP, Srivastava K, Chaves JM, Gill AK. Post-translationally modified human lens crystallin fragments show aggregation in vitro. Biochem Biophys Rep 2017; 10:94-131. [PMID: 28955739 PMCID: PMC5614626 DOI: 10.1016/j.bbrep.2017.01.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/23/2016] [Accepted: 01/26/2017] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND Crystallin fragments are known to aggregate and cross-link that lead to cataract development. This study has been focused on determination of post-translational modifications (PTMs) of human lens crystallin fragments, and their aggregation properties. METHODS Four crystallin fragments-containing fractions (Fraction I [∼3.5 kDa species], Fraction II [∼3.5-7 kDa species], Fraction III [∼7-10 kDa species] and Fraction IV [>10-18 kDa species]), and water soluble high molecular weight (WS-HMW) protein fraction were isolated from water soluble (WS) protein fraction of human lenses of 50-70 year old-donors. The crystallin fragments of the Fractions I-IV were separated by two-dimensional (2D)-gel electrophoresis followed by analysis of their gel-spots by mass spectrometry. The Fractions I-IV were examined for their molecular mass, particle-diameters, amyloid fibril formation, and for their aggregation by themselves and with WS-HMW proteins. RESULTS Crystallin fragments in Fractions I-IV were derived from α-, β- and γ-crystallins, and their 2D-gel separated spots contained multiple crystallins with PTMs such as oxidation, deamidation, methylation and acetylation. Crystallin fragments from all the four fractions exhibited self-aggregated complexes ranging in Mr from 5.5×105 to 1.0×108 Da, with diameters of 10-28 nm, and amyloid fibril-like formation, and aggregation with WS-HMW proteins. CONCLUSION The crystallin fragments exhibited several PTMs, and were capable of forming aggregated species by themselves and with WS-HMW proteins, suggesting their potential role in aggregation process during cataract development. GENERAL SIGNIFICANCE Crystallin fragments play a major role in human cataract development.
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Affiliation(s)
- O P Srivastava
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - K Srivastava
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - J M Chaves
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - A K Gill
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL 35294, United States
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Raju M, Santhoshkumar P, Sharma KK. Lens Endogenous Peptide αA66-80 Generates Hydrogen Peroxide and Induces Cell Apoptosis. Aging Dis 2017; 8:57-70. [PMID: 28203481 PMCID: PMC5287387 DOI: 10.14336/ad.2016.0805] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/05/2016] [Indexed: 01/27/2023] Open
Abstract
In previous studies, we reported the presence of a large number of low-molecular-weight (LMW) peptides in aged and cataract human lens tissues. Among the LMW peptides, a peptide derived from αA-crystallin, αA66-80, was found in higher concentration in aged and cataract lenses. Additional characterization of the αA66-80 peptide showed beta sheet signature, and it formed well-defined unbranched fibrils. Further experimental data showed that αA66-80 peptide binds α-crystallin, impairs its chaperone function, and attracts additional crystallin proteins to the peptide α-crystallin complex, leading to the formation of larger light scattering aggregates. It is well established that Aβ peptide exhibits cell toxicity by the generation of hydrogen peroxide. The αA66-80 peptide shares the principal properties of Aβ peptide. Therefore, the present study was undertaken to determine whether the fibril-forming peptide αA66-80 has the ability to generate hydrogen peroxide. The results show that the αA66-80 peptide generates hydrogen peroxide, in the amount of 1.2 nM H2O2 per µg of αA66-80 peptide by incubation at 37°C for 4h. We also observed cytotoxicity and apoptotic cell death in αA66-80 peptide-transduced Cos7 cells. As evident, we found more TUNEL-positive cells in αA66-80 peptide transduced Cos7 cells than in control cells, suggesting peptide-mediated cell apoptosis. Additional immunohistochemistry analysis showed the active form of caspase-3, suggesting activation of the caspase-dependent pathway during peptide-induced cell apoptosis. These results confirm that the αA66-80 peptide generates hydrogen peroxide and promotes hydrogen peroxide-mediated cell apoptosis.
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Affiliation(s)
| | | | - K Krishna Sharma
- 1Departments of Ophthalmology and; 2Biochemistry, University of Missouri School of Medicine, Columbia, MO65212, USA
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Ainsbury EA, Barnard S, Bright S, Dalke C, Jarrin M, Kunze S, Tanner R, Dynlacht JR, Quinlan RA, Graw J, Kadhim M, Hamada N. Ionizing radiation induced cataracts: Recent biological and mechanistic developments and perspectives for future research. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2016; 770:238-261. [DOI: 10.1016/j.mrrev.2016.07.010] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 07/27/2016] [Accepted: 07/28/2016] [Indexed: 02/06/2023]
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Tweeddale HJ, Hawkins CL, Janmie JF, Truscott RJW, Davies MJ. Cross-linking of lens crystallin proteins induced by tryptophan metabolites and metal ions: implications for cataract development. Free Radic Res 2016; 50:1116-1130. [PMID: 27383194 DOI: 10.1080/10715762.2016.1210802] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Long-wavelength solar UV radiation is implicated in photodamage to the human eye. The human lens contains multiple tryptophan-derived compounds that have significant absorbance bands in the UVA region (λ 315-400 nm) that act as efficient physical filters for these wavelengths. The concentrations of many of these UV filter compounds decrease with increase in age, resulting in diminished protection, increased oxidative damage and the accumulation of modified proteins implicated in nuclear cataract formation. This damage may arise via the formation of α,β-unsaturated carbonyls from the UV filter compounds, adduction to lens proteins and subsequent action as photosensitizers, and/or via the reactions of redox-active transition metal ions that accumulate in aged human lenses. The latter may promote the oxidation of free, or protein-bound, o-aminophenols, such as the UV filter compounds 3-hydroxykynurenine (3OHKyn) and 3-hydroxyanthranilic acid (3OHAA). It is shown here that Cu(II), and to a lesser extent Fe(III), enhance oxidation of free 3OHKyn, 3OHAA and 3OHKyn bound to specific amino acids and lens proteins, with this resulting in increased cross-linking of lens proteins. These data indicate that elevated levels of transition metal ions in aging lenses can enhance the loss of protective UV filter compounds, and contribute to the formation of high-molecular-mass dysfunctional crystallin proteins in a light-independent manner. These reactions may contribute to the formation of lens cataracts in humans.
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Affiliation(s)
- Helen J Tweeddale
- a Department of Chemistry and Biomolecular Sciences , Macquarie University , Sydney , NSW , Australia
| | - Clare L Hawkins
- b The Heart Research Institute , Sydney , NSW , Australia.,c Sydney Medical School, University of Sydney , Sydney , NSW , Australia
| | - Joane F Janmie
- a Department of Chemistry and Biomolecular Sciences , Macquarie University , Sydney , NSW , Australia
| | - Roger J W Truscott
- d Illawarra Health and Medical Research Institute, University of Wollongong , Wollongong , NSW , Australia
| | - Michael J Davies
- b The Heart Research Institute , Sydney , NSW , Australia.,c Sydney Medical School, University of Sydney , Sydney , NSW , Australia.,e Department of Biomedical Sciences , Panum Institute, University of Copenhagen , Copenhagen , Denmark
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