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Frema Amanfo A, Kyei S, Duah Boakye Y, Osei Akoto C, Kwaku Addo J, Oduro Yeboah K, Osafo N. Anticataract Effect of the Aqueous Extract of the Flowers of Aspilia africana in Murine Model of Diabetic and Age-Related Cataracts. Adv Pharmacol Pharm Sci 2023; 2023:7867497. [PMID: 37152635 PMCID: PMC10159747 DOI: 10.1155/2023/7867497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 03/31/2023] [Accepted: 04/05/2023] [Indexed: 05/09/2023] Open
Abstract
Background The use of Aspilia africana in traditional medicine for the management of ocular diseases has been reported in India and some indigenous communities of Africa. The aim of this study was to investigate the aqueous extract of the flowers of A. africana (AAE) as an anticataract remedy using murine models of diabetic and senile cataracts. Methods Preliminary phytochemical screening of the extract, in vitro antioxidant assays, and in vitro aldose reductase inhibitory activity were performed. For anticataract investigations of the extracts, diabetic cataract was induced by galactose administration in 3-week-old Sprague Dawley rats. The evaluation of experimentally induced age-related cataract was performed by administering sodium selenite to 10-day-old rat pups. Results The phytochemical analysis revealed the presence of alkaloids, tannins, flavonoids, glycosides, and saponins. In vitro aldose reductase inhibitory property of the extract on rat lenses revealed that the AAE inhibited the enzyme activity with IC50 of 12.12 µg/ml. For the anticataract investigations, 30, 100, and 300 mg·kg-1AAE-treated rats recorded significantly low (p ≤ 0.0001) cataract scores compared to the negative control rats, indicating a delay in cataractogenesis from the second week of treatment in the galactose-induced cataractogenesis. Similarly, the treatment with AAE caused a significant reduction (p ≤ 0.0001) in cataract scores compared to the negative control rats in the selenite-induced cataractogenesis. Markers of lens transparency, such as aquaporin 0, alpha-A crystallin, and total lens proteins and lens glutathione levels, were significantly preserved (p ≤ 0.05-0.0001) in each cataract model after AAE treatment. Conclusion The study established the anticataract potential of the aqueous extract of flowers of A. africana in murine models, hence giving scientific credence to its folkloric use in the management of cataract.
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Affiliation(s)
- Adwoa Frema Amanfo
- Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Samuel Kyei
- Department of Optometry and Vision Science, University of Cape Coast, Cape Coast, Ghana
| | - Yaw Duah Boakye
- Department of Pharmaceutics, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Clement Osei Akoto
- Department of Chemistry, College of Science, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | | | - Kofi Oduro Yeboah
- Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Newman Osafo
- Department of Pharmacology, Faculty of Pharmacy and Pharmaceutical Sciences, College of Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
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Hou W, Pande A, Pande J. Oxidation of active cysteines mediates protein aggregation of S10R, the cataract-associated mutant of mouse GammaB-crystallin. Proteins 2022; 90:1987-2000. [PMID: 35726360 PMCID: PMC9561057 DOI: 10.1002/prot.26391] [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: 03/14/2022] [Revised: 05/15/2022] [Accepted: 06/01/2022] [Indexed: 11/09/2022]
Abstract
The Ser10 to Arg mutation in mouse γB-crystallin (MGB) has been associated with protein aggregation, dense nuclear opacity, and the degeneration of fiber cells in the lens core. Overexpression of the gap junction protein, connexin 46 (Cx46), was found to suppress the nuclear opacity and restore normal cell-cell contact. However, the molecular basis for the protein aggregation and related downstream effects were not evident from these studies. Here, we provide a comparison of the structures and solution properties of wild type MGB and the S10R mutant in vitro and show that, even though the mutation does not directly involve cysteine residues, some cysteines in the mutant protein are activated, leading to the enhanced formation of intermolecular disulfide-crosslinked protein aggregates relative to the wild-type. This occurs even as the protein structure is essentially unaltered. Thus, the primary event is enhanced protein aggregation due to the disulfide crosslinking of the mutant protein. We suggest that these aggregates eventually get deposited on fiber cell membranes. Since the gap junction protein, Cx46 is involved in the transport of reduced glutathione, we posit that these deposits interfere in Cx46-mediated glutathione transport and facilitate the oxidative stress-mediated downstream changes. Overexpression of Cx46 suppresses such oxidative aggregation. These studies provide a plausible explanation for the protein aggregation and other changes that accompany this mutation. If indeed cysteine oxidation is the primary event for protein aggregation also in vivo, then the S10R mutant mouse, which is currently available, could serve as a viable animal model for human age-onset cataract.
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Affiliation(s)
- Wenjuan Hou
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
- Current address: BioLegend Inc., 8999 BioLegend Way, San
Diego, CA 92121, United States
| | - Ajay Pande
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
| | - Jayanti Pande
- Department of Chemistry, Life Sciences, University at
Albany, State University of New York, Albany, NY, USA
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3
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Quinlan RA, Clark JI. Insights into the biochemical and biophysical mechanisms mediating the longevity of the transparent optics of the eye lens. J Biol Chem 2022; 298:102537. [PMID: 36174677 PMCID: PMC9638808 DOI: 10.1016/j.jbc.2022.102537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/20/2022] [Accepted: 09/22/2022] [Indexed: 11/18/2022] Open
Abstract
In the human eye, a transparent cornea and lens combine to form the "refracton" to focus images on the retina. This requires the refracton to have a high refractive index "n," mediated largely by extracellular collagen fibrils in the corneal stroma and the highly concentrated crystallin proteins in the cytoplasm of the lens fiber cells. Transparency is a result of short-range order in the spatial arrangement of corneal collagen fibrils and lens crystallins, generated in part by post-translational modifications (PTMs). However, while corneal collagen is remodeled continuously and replaced, lens crystallins are very long-lived and are not replaced and so accumulate PTMs over a lifetime. Eventually, a tipping point is reached when protein aggregation results in increased light scatter, inevitably leading to the iconic protein condensation-based disease, age-related cataract (ARC). Cataracts account for 50% of vision impairment worldwide, affecting far more people than other well-known protein aggregation-based diseases. However, because accumulation of crystallin PTMs begins before birth and long before ARC presents, we postulate that the lens protein PTMs contribute to a "cataractogenic load" that not only increases with age but also has protective effects on optical function by stabilizing lens crystallins until a tipping point is reached. In this review, we highlight decades of experimental findings that support the potential for PTMs to be protective during normal development. We hypothesize that ARC is preventable by protecting the biochemical and biophysical properties of lens proteins needed to maintain transparency, refraction, and optical function.
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Affiliation(s)
- Roy A Quinlan
- Department of Biosciences, Durham University, South Road Science Site, Durham, United Kingdom; Department of Biological Structure, University of Washington, Seattle, Washington, USA.
| | - John I Clark
- Department of Biological Structure, University of Washington, Seattle, Washington, USA.
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Rivelli Antonelli JF, Santander VS, Nigra AD, Monesterolo NE, Previtali G, Primo E, Otero LH, Casale CH. Prevention of tubulin/aldose reductase association delays the development of pathological complications in diabetic rats. J Physiol Biochem 2021; 77:565-576. [PMID: 34097242 DOI: 10.1007/s13105-021-00820-1] [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: 12/18/2020] [Accepted: 05/12/2021] [Indexed: 11/26/2022]
Abstract
In recent studies, we found that compounds derived from phenolic acids (CAFs) prevent the formation of the tubulin/aldose reductase complex and, consequently, may decrease the occurrence or delay the development of secondary pathologies associated with aldose reductase activation in diabetes mellitus. To verify this hypothesis, we determined the effect of CAFs on Na+,K+-ATPase tubulin-dependent activity in COS cells, ex vivo cataract formation in rat lenses and finally, to evaluate the antidiabetic effect of CAFs, diabetes mellitus was induced in Wistar rats, they were treated with different CAFs and four parameters were determinates: cataract formation, erythrocyte deformability, nephropathy and blood pressure. After confirming that CAFs are able to prevent the association between aldose reductase and tubulin, we found that treatment of diabetic rats with these compounds decreased membrane-associated acetylated tubulin, increased NKA activity, and thus reversed the development of four AR-activated complications of diabetes mellitus determined in this work. Based on these results, the existence of a new physiological mechanism is proposed, in which tubulin is a key regulator of aldose reductase activity. This mechanism can explain the incorrect functioning of aldose reductase and Na+,K+-ATPase, two key enzymes in the pathogenesis of diabetes mellitus. Moreover, we found that such alterations can be prevented by CAFs, which are able to dissociate tubulin/aldose reductase complex.
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Affiliation(s)
- Juan F Rivelli Antonelli
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Verónica S Santander
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Ayelen D Nigra
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Noelia E Monesterolo
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Gabriela Previtali
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Emilianao Primo
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina
| | - Lisandro H Otero
- Instituto de Investigaciones Bioquímicas de Buenos Aires, IIBBA, CONICET - Fundación Instituto Leloir, Av Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina
| | - César H Casale
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, 5800, Córdoba, CP, Argentina.
- INBIAS CONICET-UNRC, Instituto de Biotecnología Ambiental y Salud, Campus UNRC, Río Cuarto, 5800, Córdoba, CP, Argentina.
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Liu S, Hu C, Luo Y, Yao K. Genome-wide DNA methylation profiles may reveal new possible epigenetic pathogenesis of sporadic congenital cataract. Epigenomics 2020; 12:771-788. [PMID: 32516005 DOI: 10.2217/epi-2019-0254] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Aim: To investigate the possible epigenetic pathogenesis of sporadic congenital cataract. Materials & methods: We conducted whole genome bisulfite sequencing on peripheral blood from sporadic binocular or monocular congenital cataract patients and cataract-free participants. Results: We found massive differentially methylated regions within the whole genomes between any two groups. Meanwhile, we identified five genes (ACTN4, ACTG1, TUBA1A, TUBA1C, TUBB4B) for the binocular and control groups and TUBA1A for the monocular and control groups as the core differentially methylated region-related genes. The proteins encoded by these core genes are involved in building cytoskeleton and intercellular junctions. Conclusion: Changes in the methylation levels of core genes may disturb the function of cytoskeleton and intercellular junctions, eventually leading to sporadic congenital cataract.
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Affiliation(s)
- Siyu Liu
- Eye Center of The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310031, PR China.,Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, Zhejiang Province 310031, PR China
| | - Chenyang Hu
- Eye Center of The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310031, PR China.,Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, Zhejiang Province 310031, PR China
| | - Yueqiu Luo
- Eye Center of The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310031, PR China.,Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, Zhejiang Province 310031, PR China
| | - Ke Yao
- Eye Center of The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310031, PR China.,Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou, Zhejiang Province 310031, PR China
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Anbukkarasi M, Thomas PA, Teresa PA, Anand T, Geraldine P. Comparison of the efficacy of a Tabernaemontana divaricata extract and of biosynthesized silver nanoparticles in preventing cataract formation in an in-vivo system of selenite-induced cataractogenesis. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2020. [DOI: 10.1016/j.bcab.2019.101475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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7
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Yuan C, Han T, Su P, Liu M, Zhou X, Zhang D, Jia W, Wang A, Yue M, Xiang Z, Chen L, Zhang X. A novel MIP mutation in a Chinese family with congenital cataract. Ophthalmic Genet 2019; 39:473-476. [PMID: 29947569 DOI: 10.1080/13816810.2018.1484930] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE To identify the disease-causing gene of a four-generation Chinese family with congenital cataract. METHODS To screen the disease-causing gene of the family, six disease genes of congenital cataract are screened by direct DNA sequencing, the cDNA of wild-type (WT) MIP gene, and P191R mutant MIP gene (MT) were constructed into pEGFP-C1 vector and pGH19 vector. The recombinant plasmids of pEGFP-C1, WT, and mutant MIP were transfected into Hela cell to check the localization and HEK293T cells to detect expression level of protein. The cRNA of WT and MT MIP gene were injected into Xenopus oocytes to measure the swelling rate. RESULTS A novel missense mutation c.572C>G(p.P191R)at exon 3 of the MIP gene was identified and co-segregated with disease in the Chinese family. The same amount of pEGFP-WT MIP and pEGFP- P191R MIP plasmids were transfected in Hela cells. Confocal microscopy imaging showed that WT MIP protein predominantly localized on the plasma membrane, the mutant protein was rich in the cytoplasm in Hela cells. Western blot results show that the expression level of P191R mutant MIP was significantly lower than WT MIPincell membrane enriched lysates in HEK293T cells. Xenopus oocytes swelling assay showed that the P191R mutation reduces the swelling rate of Xenopus oocytes. CONCLUSIONS The novel missense mutation c.572C>G(p.P191R)at exon 3 of the MIP gene was identified in a Chinese family of congenital cataract. The mutation affects the traffic of MIP protein in the cells and reduces the expression level of MIP protein in the cell membrane. The mutation of MIP gene reduces the swelling ratio of Xenopus oocytes.
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Affiliation(s)
- Chao Yuan
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China.,b Hubei Key Laboratory for Kidney Disease Pathogenesis and Intervention, Huangshi Cental Hospital of Edong Healthcare Group , Hubei Polytechnic University School of Medicine , Huangshi , Hubei , China
| | - Tiantian Han
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Pan Su
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Min Liu
- c Department of Ophthalmology , NO 457 Hospital of Chinese PLA , Wuhan , China
| | - Xiaopei Zhou
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Dazhi Zhang
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Weimin Jia
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Ali Wang
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Min Yue
- c Department of Ophthalmology , NO 457 Hospital of Chinese PLA , Wuhan , China
| | - Zibing Xiang
- c Department of Ophthalmology , NO 457 Hospital of Chinese PLA , Wuhan , China
| | - Liming Chen
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
| | - Xianqin Zhang
- a Key Laboratory of Molecular Biophysics, College of Life Science and Technology , Huazhong University of Science and Technology , Wuhan , China
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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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Makarov V, Zueva L, Golubeva T, Korneeva E, Khmelinskii I, Inyushin M. Quantum mechanism of light transmission by the intermediate filaments in some specialized optically transparent cells. NEUROPHOTONICS 2017; 4:011005. [PMID: 27570792 PMCID: PMC4985621 DOI: 10.1117/1.nph.4.1.011005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/20/2016] [Indexed: 06/02/2023]
Abstract
Some very transparent cells in the optical tract of vertebrates, such as the lens fiber cells, possess certain types of specialized intermediate filaments (IFs) that have essential significance for their transparency. The exact mechanism describing why the IFs are so important for transparency is unknown. Recently, transparency was described also in the retinal Müller cells (MCs). We report that the main processes of the MCs contain bundles of long specialized IFs, each about 10 nm in diameter; most likely, these filaments are the channels providing light transmission to the photoreceptor cells in mammalian and avian retinas. We interpret the transmission of light in such channels using the notions of quantum confinement, describing energy transport in structures with electroconductive walls and diameter much smaller than the wavelength of the respective photons. Model calculations produce photon transmission efficiency in such channels exceeding 0.8, in optimized geometry. We infer that protein molecules make up the channels, proposing a qualitative mechanism of light transmission by such structures. The developed model may be used to describe light transmission by the IFs in any transparent cells.
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Affiliation(s)
- Vladimir Makarov
- University of Puerto Rico, Department of Physics, Rio Piedras Campus, P.O. Box 23343, San Juan 00931-3343, Puerto Rico
| | - Lidia Zueva
- Russian Academy of Sciences, Sechenov Institute of Evolutionary Physiology and Biochemistry, St. Petersburg, Russia
| | - Tatiana Golubeva
- Lomonosov State University, Department of Vertebrate Zoology, Moscow 119992, Russia
| | - Elena Korneeva
- Russian Academy of Sciences, Institute of Higher Nervous Activity and Neurophysiology, Butlerova Street 5a, Moscow 117485, Russia
| | - Igor Khmelinskii
- Universidade do Algarve, Centro de Investigação em Química do Algarve (CIQA), Faro 8005-139, Portugal
| | - Mikhail Inyushin
- Universidad Central del Caribe, School of Medicine, Department of Physiology, Bayamón 00960-6032, Puerto Rico
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10
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Zueva L, Golubeva T, Korneeva E, Makarov V, Khmelinskii I, Inyushin M. Foveolar Müller Cells of the Pied Flycatcher: Morphology and Distribution of Intermediate Filaments Regarding Cell Transparency. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:379-386. [PMID: 26926795 PMCID: PMC4940978 DOI: 10.1017/s1431927616000507] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Specialized intermediate filaments (IFs) have critical importance for the clearness and uncommon transparency of vertebrate lens fiber cells, although the physical mechanisms involved are poorly understood. Recently, an unusual low-scattering light transport was also described in retinal Müller cells. Exploring the function of IFs in Müller cells, we have studied the morphology and distribution pattern of IFs and other cytoskeletal filaments inside the Müller cell main processes in the foveolar part of the avian (pied flycatcher) retina. We found that some IFs surrounded by globular nanoparticles (that we suggest are crystallines) are present in almost every part of the Müller cells that span the retina, including the microvilli. Unlike IFs implicated in the mechanical architecture of the cell, these IFs are not connected to any specific cellular membranes. Instead, they are organized into bundles, passing inside the cell from the endfeet to the photoreceptor, following the geometry of the processes, and repeatedly circumventing numerous obstacles. We believe that the presently reported data effectively confirm that the model of nanooptical channels built of the IFs may provide a viable explanation of Müller cell transparency.
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Affiliation(s)
- Lidia Zueva
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223, St-Petersburg, Russia,
| | - Tatiana Golubeva
- Lomonosov Moscow State University, Department of Vertebrate Zoology, 119992, Moscow, Russia,
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 117485, Moscow, Russia,
| | - Elena Korneeva
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 117485, Moscow, Russia,
| | - Vladimir Makarov
- University of Puerto Rico, Department of Physics, San Juan, PR 00931, USA,
| | - Igor Khmelinskii
- University of the Algarve, Faculty of Sciences and Technology, Faro 8005-139, Algarve, Portugal,
| | - Mikhail Inyushin
- Central University of the Caribbean, Department of Physiology, Bayamon, PR 00956, USA,
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Khmelinskii I, Zueva L, Inyushin M, Makarov V. Model of Polarization Selectivity of the Intermediate Filament Optical Channels. PHOTONICS AND NANOSTRUCTURES : FUNDAMENTALS AND APPLICATIONS 2015; 16:24-33. [PMID: 26435707 PMCID: PMC4587907 DOI: 10.1016/j.photonics.2015.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Recently we have analyzed light transmission and spectral selectivity by optical channels in Müller cells and other transparent cells, proposing a model of their structure, formed by specialized intermediate filaments [1,2]. Our model represents each optical channel by an axially symmetric tube with conductive walls. Presently, we analyze the planar polarization selectivity in long nanostructures, using the previously developed approach extended to structures of the elliptic cross-section. We find that the output light polarization angle depends on the a/b ratio, with a and b the semiaxes of the ellipse. Experimental tests used a Cr nano-strip device to evaluate the transmitted light polarization. The model adapted to the experimental geometry provided an accurate fit of the experimental results.
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Affiliation(s)
- Igor Khmelinskii
- Universidade do Algarve, FCT, DQB and CIQA, 8005-139, Faro, Portugal
| | - Lidia Zueva
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
| | - Michael Inyushin
- Universidad Central del Caribe, School of Medicine, Bayamón, PR 00960-6032, USA
| | - Vladimir Makarov
- University of Puerto Rico, Rio Piedras Campus, PO Box 23343, San Juan, PR 00931-3343, USA
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Selenite cataracts: activation of endoplasmic reticulum stress and loss of Nrf2/Keap1-dependent stress protection. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1794-805. [PMID: 24997453 DOI: 10.1016/j.bbadis.2014.06.028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 06/19/2014] [Accepted: 06/24/2014] [Indexed: 12/21/2022]
Abstract
Cataract-induced by sodium selenite in suckling rats is one of the suitable animal models to study the basic mechanism of human cataract formation. The aim of this present investigation is to study the endoplasmic reticulum (ER) stress-mediated activation of unfolded protein response (UPR), overproduction of reactive oxygen species (ROS), and suppression of Nrf2/Keap1-dependent antioxidant protection through endoplasmic reticulum-associated degradation (ERAD) pathway and Keap1 promoter DNA demethylation in human lens epithelial cells (HLECs) treated with sodium selenite. Lenses enucleated from sodium selenite injected rats generated overproduction of ROS in lens epithelial cells and newly formed lens fiber cells resulting in massive lens epithelial cells death after 1-5days. All these lenses developed nuclear cataracts after 4-5days. Sodium selenite treated HLECs induced ER stress and activated the UPR leading to release of Ca(2+) from ER, ROS overproduction and finally HLECs death. Sodium selenite also activated the mRNA expressions of passive DNA demethylation pathway enzymes such as Dnmt1, Dnmt3a, and Dnmt3b, and active DNA demethylation pathway enzyme, Tet1 leading to DNA demethylation in the Keap1 promoter of HLECs. This demethylated Keap1 promoter results in overexpression of Keap1 mRNA and protein. Overexpression Keap1 protein suppresses the Nrf2 protein through ERAD leading to suppression of Nrf2/Keap1 dependent antioxidant protection in the HLECs treated with sodium selenite. As an outcome, the cellular redox status is altered towards lens oxidation and results in cataract formation.
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Rutin ameliorates free radical mediated cataract by enhancing the chaperone activity of α-crystallin. Graefes Arch Clin Exp Ophthalmol 2013; 251:1747-55. [PMID: 23412395 DOI: 10.1007/s00417-013-2281-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 11/24/2012] [Accepted: 01/29/2013] [Indexed: 10/27/2022] Open
Abstract
BACKGROUND Cataract, the leading cause of blindness, is associated with oxidative damage and protein modification in the lens. The present study was carried out to assess the efficacy of rutin on rat-lens crystallins in selenite-induced in-vivo cataract models. METHODS Eight-day-old Sprague-Dawley rat pups were grouped as control (G I), experimental (G II) and rutin-treated (G III). The rat pups in G II, and G III received a single subcutaneous injection of sodium selenite (4 μg/g body weight) and G I received a single subcutaneous injection of sterile water on the 10th day. The treatment groups (G III) were administered with rutin (1 μg/g body weight) respectively from the 8th to 15th day. Cataract was visualized from the 16th day. Lens crystallins (α, β, and γ) were isolated by size exclusion chromatography. Chaperone activity of isolated crystallins was measured by heat, DTT, and oxidation-induced aggregation and refolding assays. Concentration of total protein (soluble and insoluble) and SDS-PAGE analysis of soluble proteins were also done. RESULTS Treatment with rutin prevented the loss of α crystallin chaperone property, and protein insolubilization prevailed during selenite-induced cataract. CONCLUSIONS These results suggest the therapeutic potential of rutin, a bioflavonoid, against selenite-induced cataract, which has been reported in this paper for the first time. The work assumes significance, as this is a novel approach in modulating the chaperone activity of lens crystallins in selenite-induced cataract by a natural product.
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Nakajima E, Hammond KB, Rosales JL, Shearer TR, Azuma M. Calpain, not caspase, is the causative protease for hypoxic damage in cultured monkey retinal cells. Invest Ophthalmol Vis Sci 2011; 52:7059-67. [PMID: 21757584 DOI: 10.1167/iovs.11-7497] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
PURPOSE Cell death occurring in human retina during AMD, high IOP, and diabetic retinopathy could be caused by activation of calpain or caspase proteolytic enzymes. The purpose of the present study was to determine whether calpains and/or caspase-3 were involved in cell death during retinal hypoxia in a monkey model. METHODS Dissociated monkey retinal cells were cultured for two weeks and subjected to 24-hour hypoxia/24-hour reoxygenation. TUNEL staining and immunostaining for Müller and photoreceptor markers were used to detect which retinal cell types were damaged. RESULTS Culturing dissociated monkey retina cells for two weeks resulted in proliferation of Müller cells and maintenance of some rod and cone photoreceptor cells, as identified by vimentin, recoverin, and rhodopsin immunocytochemical staining. Hypoxia/reoxygenation increased the number of cells staining positive for TUNEL. Immunoblotting showed that the calpain-specific 145 kDa α-spectrin breakdown product (SBDP) increased in hypoxic cells, but no caspase-specific 120 kDa α-spectrin breakdown product was detected. TUNEL staining and proteolysis were significantly reduced in the retinal cells treated with 10 and 100 μM calpain inhibitor SNJ-1945. Caspase inhibitor, z-VAD, did not inhibit cell damage from hypoxia/reoxygenation. Intact pro-caspase-3 was in fact cleaved by activated calpain during hypoxia/reoxygenation to pre 29 kDa caspase-3 and 24 kDa inactive fragments. No 17 and 12 kDa fragments, which form the active caspase-3 hetero-dimer, were detected. Calpain-induced cleavage of caspase was inhibited by SNJ-1945. CONCLUSIONS Calpain, not caspase-3, was involved in hypoxic damage in cultured monkey retinal cells.
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Affiliation(s)
- Emi Nakajima
- Senju Laboratory of Ocular Sciences, Senju Pharmaceutical Corporation Limited, Beaverton, Oregon 97006, USA
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Li N, Zhu Y, Deng X, Gao Y, Zhu Y, He M. Protective effects and mechanism of tetramethylpyrazine against lens opacification induced by sodium selenite in rats. Exp Eye Res 2011; 93:98-102. [PMID: 21635889 DOI: 10.1016/j.exer.2011.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 05/05/2011] [Accepted: 05/09/2011] [Indexed: 10/18/2022]
Abstract
Tetramethylpyrazine (TMP), extracted from the Chinese herbal medicine Ligusticum wallichii franchat (chuan xiong in Chinese), is a potent anti-free radical and calcium antagonist. Correspondingly, two important hypotheses in the causation of cataracts are free radical toxicity and calcium ion overload. In this study we investigated the effect of TMP on lens opacification induced by sodium selenite in rats, addressing the potential of TMP eye drops to prevent and treat cataracts. Results showed that the extent of lens opacification in the untreated Normal Control group (NC group) was significantly less than that of selenite-injected untreated rats (MC group) on days 3, 5, 7 and 10 (p < 0.001), while TMP treated selenite-injected rats (TMP group) had less lens opacification than the MC group on days 3, 5, 7 and 10 (p < 0.05). Compared with the NC group, the MC group had significantly decreased activity of super-oxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) and significantly elevated malondialdehyde (MDA) and calcium ion content (p < 0.001). Compared with the MC group, the activity of (SOD), (GSH-PX) and (CAT) were significantly higher while (MDA) and calcium ion levels were significantly lower in the TMP group at all time points (p < 0.01). The findings demonstrate that the selenite-induced cataract rat models were successfully built and the TMP eye drops can delay lens opacification induced by sodium selenite in rats. The mechanism by which TMP preserves lens transparency from selenite treated animals is associated with the lenses' ability to maintain normal levels of activity of SOD, GSH-PX and CAT and normal concentrations of MDA and calcium ion.
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Affiliation(s)
- Na Li
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, 54 Xianlie Road South, Guangzhou 510060, China
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Su SP, McArthur JD, Truscott RJW, Aquilina JA. Truncation, cross-linking and interaction of crystallins and intermediate filament proteins in the aging human lens. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:647-56. [PMID: 21447408 DOI: 10.1016/j.bbapap.2011.03.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 02/14/2011] [Accepted: 03/22/2011] [Indexed: 11/30/2022]
Abstract
The optical properties of the lens are dependent upon the integrity of proteins within the fiber cells. During aging, crystallins, the major intra-cellular structural proteins of the lens, aggregate and become water-insoluble. Modifications to crystallins and the lens intermediate filaments have been implicated in this phenomenon. In this study, we examined changes to, and interactions between, human lens crystallins and intermediate filament proteins in lenses from a variety of age groups (0-86years). Among the lens-specific intermediate filament proteins, filensin was extensively cleaved in all postnatal lenses, with truncated products of various sizes being found in both the lens cortical and nuclear extracts. Phakinin was also truncated and was not detected in the lens nucleus. The third major intermediate filament protein, vimentin, remained intact in lens cortical fiber cells across the age range except for an 86year lens, where a single ~49kDa breakdown product was observed. An αB-crystallin fusion protein (maltose-binding protein-αB-crystallin) was found to readily exchange subunits with endogenous α-crystallin, and following mild heat stress, to bind to filensin, phakinin and vimentin and to several of their truncated products. Tryptic digestion of a truncated form of filensin suggested that the binding site for α-crystallin may be in the N-terminal region. The presence of significant amounts of small peptides derived from γS- and βB1-crystallins in the water-insoluble fraction of the lens indicates that these interact tightly with cytoskeletal or membrane components. Interestingly, water-soluble complexes (~40kDa) contained predominantly γS- and βB1-crystallins, suggesting that cross-linking is an alternative pathway for modified β- and γ-crystallins in the lens.
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Affiliation(s)
- Shih-Ping Su
- School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.
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Sakthivel M, Geraldine P, Thomas PA. Alterations in the lenticular protein profile in experimental selenite-induced cataractogenesis and prevention by ellagic acid. Graefes Arch Clin Exp Ophthalmol 2011; 249:1201-10. [PMID: 21455778 DOI: 10.1007/s00417-011-1644-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 01/13/2011] [Accepted: 02/01/2011] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Accumulating evidence suggests that oxidative stress underlies age-related formation of cataract, and that antioxidants retard cataractogenesis. This study aimed to evaluate whether ellagic acid, a natural polyphenol with antioxidant properties, prevents alterations in the lenticular protein profile in an experimental model of selenite cataract. METHODS Alterations in lenticular protein were determined by two-dimensional electrophoresis (2DE) and image analysis. Eluted αA-crystallin spots were analyzed by mass spectrometry. Western blot analysis was also performed to confirm the differential expression of certain crystallins and cytoskeletal proteins. RESULTS In cataractous lenses, 2DE and image analysis revealed approximately 45 and 60 prominent spots in soluble and insoluble protein fractions respectively. Analysis of the pI and molecular weight of protein spots revealed differences in the expression of crystallin proteins in soluble and insoluble fractions. Western blot analysis confirmed changes in the expression of αA- and βB1- crystallins in both soluble and insoluble protein fractions, while mass spectrometry confirmed the degradation of αA-crystallin in selenite cataractous lenses. Western blot analysis also confirmed the occurrence of altered expression of certain cytoskeletal proteins in insoluble fractions. However, the lenticular protein profile in lenses from selenite-challenged, ellagic acid-treated rats was essentially similar to that noted in lenses from normal rats. CONCLUSIONS The present study confirms the importance of structural and cytoskeletal proteins in the maintenance of lenticular transparency; the results also suggest that ellagic acid prevents lenticular protein alterations induced by selenite in an experimental setting.
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Affiliation(s)
- Muniyan Sakthivel
- Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli, 620 024 Tamil Nadu, India
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Manikandan R, Thiagarajan R, Beulaja S, Chindhu S, Mariammal K, Sudhandiran G, Arumugam M. Anti-cataractogenic effect of curcumin and aminoguanidine against selenium-induced oxidative stress in the eye lens of Wistar rat pups: An in vitro study using isolated lens. Chem Biol Interact 2009; 181:202-9. [PMID: 19481068 DOI: 10.1016/j.cbi.2009.05.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 05/03/2009] [Accepted: 05/20/2009] [Indexed: 12/12/2022]
Abstract
The aim of this study was to investigate whether curcumin and aminoguanidine (AG) prevent selenium-induced cataractogenesis in vitro. On postpartum day 8, transparent isolated lens were incubated in 24 well plates containing Dulbecco's Modified Eagle Medium (DMEM). Isolated lens of group I were incubated with DMEM medium alone. Group II: lenses incubated in DMEM containing 100microM sodium selenite; group III: lenses incubated in DMEM containing 100microM sodium selenite and 100microM curcumin; group IV: lenses incubated in DMEM containing 100microM sodium selenite and 200microM curcumin; group V: lenses incubated in DMEM containing 100microM sodium selenite and 100microM AG; group V: lenses incubated in DMEM containing 100microM sodium selenite and 200microM AG. On day 12, cataract development was graded using an inverted microscope and the lenses were analyzed for enzymic as well as non-enzymic antioxidants, lipid peroxidation (LPO), nitric oxide (NO), superoxide anion (O(2)(-)) and hydroxyl radical generation (OH) and inducible nitric oxide synthase (iNOS) activity by Western blotting and RT-PCR. All control lenses in group I were clear (0). In groups II and III, all isolated lenses developed cataract with variation in levels (+++ or ++), whereas isolated lenses from groups IV, V and VI were clear (0). In agreement to this, a decrease in antioxidants and increased free radical generation and also iNOS expression were observed in selenium exposed lenses when compared to other groups. AG (100microM) was found to be more effective in anti-cataractogenic effect than curcumin (200microM). Curcumin and AG suppressed selenium-induced oxidative stress and cataract formation in isolated lens from Wistar rat pups, possibly by inhibiting depletion of enzymic as well as non-enzymic antioxidants, and preventing uncontrolled generation of free radicals and also by inhibiting iNOS expression. Our results implicate a major role for curcumin and AG in preventing cataractogenesis in selenite-exposed lenses, wherein AG was found to be more potent.
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Affiliation(s)
- R Manikandan
- Department of Zoology, University of Madras, Chennai, India.
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Isai M, Elanchezhian R, Sakthivel M, Chinnakkaruppan A, Rajamohan M, Jesudasan CN, Thomas PA, Geraldine P. Anticataractogenic effect of an extract of the oyster mushroom, Pleurotus ostreatus, in an experimental animal model. Curr Eye Res 2009; 34:264-73. [PMID: 19373574 DOI: 10.1080/02713680902774069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
PURPOSE To evaluate the efficacy of Pleurotus ostreatus extract in preventing selenite-induced cataractogenesis. METHODS In vitro, enucleated rat lenses, divided into one control and three experimental groups (selenite only, simultaneous selenite and extract, initial extract and subsequent selenite), underwent morphological and biochemical evaluation. The anti-cataractogenic effect was also evaluated in vivo. RESULTS In vitro, simultaneous incubation of extract with selenite-challenged lenses caused a decrease in lens opacification by maintaining antioxidant components at near normal levels. In vivo, P.ostreatus (300 mg/kg body weight) prevented cataract in 75% of rats. CONCLUSION Extract of P. ostreatus prevents experimental selenite-induced cataractogenesis.
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Affiliation(s)
- M Isai
- Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu, India
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The effect of acetyl-L-carnitine on lenticular calpain activity in prevention of selenite-induced cataractogenesis. Exp Eye Res 2008; 88:938-44. [PMID: 19150348 DOI: 10.1016/j.exer.2008.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/30/2008] [Accepted: 12/08/2008] [Indexed: 11/23/2022]
Abstract
The present study sought to determine whether acetyl-L-carnitine (ALCAR) prevents selenite cataractogenesis by mechanisms involving lenticular calpain activity, Wistar rat pups were divided into 3 groups of 15 each. Group I (normal) rats received an intraperitoneal (i.p.) injection of normal saline on postpartum day 10; Group II (cataract-untreated) rats received a single subcutaneous (s.c.) injection of sodium selenite (19micromol/kg body weight) on postpartum day 10; Group III (cataract-treated) pups received a single s.c. injection of sodium selenite on postpartum day 10 and intraperitoneal injections of acetyl-L-carnitine (200mg/kg body weight) on postpartum days 9-14. At the end of the study period (postpartum day 16), both eyes of each rat pup were examined by slit-lamp biomicroscopy. There was dense lenticular opacification in all Group II rats, minimal lenticular opacification in 33% of Group III rats, and no lenticular opacification in 67% of Group III and in all Group I rats. Group II lenses exhibited significantly lower mean values of calpain activity and Lp82 (lens-specific calpain) protein expression, decreases in relative transcript level of m-calpain mRNA and significantly higher mean Ca(2+) concentrations than Group I or Group III lenses; the values of these parameters in Group III rat lenses (ALCAR-treated) approximated those in Group I rat lenses. The results suggest that, in addition to its already-described antioxidant potential, ALCAR prevents selenite cataractogenesis by maintaining calpain activity at near normal levels. These findings may stimulate further efforts to develop ALCAR as a novel drug for prevention of cataract.
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Srivastava K, Chaves JM, Srivastava OP, Kirk M. Multi-crystallin complexes exist in the water-soluble high molecular weight protein fractions of aging normal and cataractous human lenses. Exp Eye Res 2008; 87:356-66. [PMID: 18662688 DOI: 10.1016/j.exer.2008.07.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 06/30/2008] [Accepted: 07/01/2008] [Indexed: 11/19/2022]
Abstract
The purpose of the study was to identify non-covalently held complexes that exist in the water-soluble high molecular weight (WS-HMW) protein fractions of normal human lenses of 20-year-old and 60- to 70-year-old, and in the age-matched 60- to 70-year-old cataractous lenses. The WS protein fractions were prepared from five pooled normal lenses of 20-year-old donors or five pooled lenses of 60- to 70-year-old donors or four pooled cataractous lenses (with nuclear opacity) of 60- to 70-year-old donors. Each WS protein fraction was subjected to size-exclusion chromatography using an Agarose A 5m column to recover the void volume WS-HMW protein fraction. A method known as blue-native polyacrylamide gel electrophoresis (BN-PAGE), which allows the isolation of large multi-protein complexes (MPCs) in their native state for further characterization, was used to separate such complexes from individual WS-HMW protein fractions. The protein species that existed as a complex were excised from a gel and trypsin-digested, and the amino acid sequences of the tryptic fragments analyzed by electrospray tandem mass spectrometry (ES-MS/MS). After the second-dimensional sodium dodecyl sulfate-PAGE during BN-PAGE, protein complexes containing a total of 16, 12, and 24 species with M(r) between 10 and 90 kDa were identified in the HMW protein fractions of normal lenses of 20-year-old, 60- to 70-year-old and cataractous lenses of 60- to 70-year-old donors, respectively. Based on the amino acid sequences of tryptic peptides of individual protein species in the complexes by the ES-MS/MS method, the presence of alpha-, beta-, and gamma-crystallin species along with beaded filament proteins (filensin and phakinin) was observed in the 20-year-old normal lenses. The 60- to 70-year-old normal lenses contained filensin and aldehyde dehydrogenase in addition to the above crystallins. Similarly, the age-matched cataractous lenses also contained the above crystallins and aldehyde dehydrogenase but lacked beaded filament proteins. Protein complexes, held mostly via non-covalent bonding, were seen in the WS-HMW proteins of 20-year-old normal, 60- to 70-year-old normal, and 60- to 70-year-old cataractous lenses. The complexes in the normal lenses were made of alpha-, beta-, and gamma-crystallin species, beaded filament proteins (filensin and/or phakinin), and aldehyde dehydrogenase. The complexes in the age-matched cataractous lenses also contained these crystallins, and aldehyde dehydrogenase, but not the beaded filament proteins. Further, the crystallin fragments were greater in number in the cataractous lenses compared to the age-matched normal lenses. During multi-angle light scattering (MALS), the HMW proteins from cataractous lenses exhibited species with lower molecular weight range than age-matched normal lenses. The HMW protein preparations from both normal and cataractous lenses showed spherical structures on electron microscopic analysis.
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Affiliation(s)
- K Srivastava
- Department of Vision Sciences, University of Alabama at Birmingham, Worrell Bldg., 924 S-18th Street, Birmingham, AL 35294, USA
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Elanchezhian R, Ramesh E, Sakthivel M, Isai M, Geraldine P, Rajamohan M, Jesudasan CN, Thomas PA. Acetyl-L-carnitine prevents selenite-induced cataractogenesis in an experimental animal model. Curr Eye Res 2008; 32:961-71. [PMID: 18027172 DOI: 10.1080/02713680701673470] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
PURPOSE To investigate whether acetyl-L-carnitine (ALCAR) retards selenite-induced cataractogenesis in vivo. METHODS On postpartum day 10, group I pups received intraperitoneal saline and group II and group III pups received subcutaneous sodium selenite; Group III pups also received intraperitoneal ALCAR once daily on postpartum days 9-14. Both eyes of each pup were examined up to postpartum day 30. After sacrifice, extricated pup lenses were analyzed for antioxidant and redox system components. RESULTS There was dense lenticular opacification in all group II pups, minimal opacification in 33% of group III pups, and no opacification in 67% of group III and in all group I pups. Group II lenses exhibited significantly lower values of antioxidant and redox system components and higher malondialdehyde concentrations than group I or group III lenses. CONCLUSION ALCAR prevents selenite-induced cataractogenesis in Wistar rat pups, possibly by inhibiting depletion of antioxidant enzyme and redox system components and inhibiting lipid peroxidation.
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Affiliation(s)
- R Elanchezhian
- Department of Animal Science, School of Life Sciences, Bharathidasan University, Tamil Nadu, India
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Verdugo-Gazdik ME, Simic D, Opsahl AC, Tengowski MW. Investigating cytoskeletal alterations as a potential marker of retinal and lens drug-related toxicity. Assay Drug Dev Technol 2007; 4:695-707. [PMID: 17199508 DOI: 10.1089/adt.2006.4.695] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Actin filaments play a critical role in the normal physiology of lenticular and retinal cells in the eye. Disruption of the actin cytoskeleton has been associated with retinal pathology and lens cataract formation. Ocular toxicity is an infrequent observation in drug safety studies, yet its impact to the drug development process is significant. Recognizing compounds through screening with a potential ocular safety liability is one way to prioritize development candidates while reducing development attrition. Lens epithelial cells from human, dog, and rat origins and retinal pigmented epithelium cells from human, monkey, and rat origins were cultured and investigated with immunocytochemical techniques. Cells were treated using noncytotoxic doses of the compound, fixed, stained for actin with rhodamine phalloidin, and counterstained for nuclei with TOTO-3, followed by confocal imaging. Tamoxifen and several experimental compounds known to be in vivo lens and retinal toxicants caused a reduction in F-actin fluorescence at noncytotoxic concentrations in all cells tested as observed by confocal microscopy. Developing an assay that predicts ocular toxicity helps the development process by prioritizing compounds for further investigation. Drug-induced cytoskeletal alterations may be useful as a potential safety-screening marker of retinal and lens toxicity. The knowledge of actin molecular biology and the application of other mechanistic screens to toxicology are discussed. Reducing this work to a high-throughput platform will enable chemists to select compounds with a reduced risk of ocular toxicity.
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Geraldine P, Sneha BB, Elanchezhian R, Ramesh E, Kalavathy CM, Kaliamurthy J, Thomas PA. Prevention of selenite-induced cataractogenesis by acetyl-l-carnitine: An experimental study. Exp Eye Res 2006; 83:1340-9. [PMID: 16962580 DOI: 10.1016/j.exer.2006.07.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2006] [Revised: 06/04/2006] [Accepted: 07/17/2006] [Indexed: 10/24/2022]
Abstract
Several studies have suggested that antioxidants retard the process of cataractogenesis by scavenging free oxygen radicals. The present study sought to assess the efficacy of the antioxidant acetyl-L-carnitine (ALCAR) in preventing selenite-induced cataractogenesis in an experimental setting. The first, in vitro phase of the study was performed on lenses from Wistar rats incubated for 24 h at 37 degrees C in Dulbecco's Modified Eagle Medium (DMEM) alone (control, Group I), or in DMEM containing 100 microM of selenite (Group II) or in DMEM containing 100 microM of selenite and 200 microM/ml ALCAR added at the same time as selenite (Group IIIa) or 30 min, 1 h or 2 h later (Groups IIIb, IIIc and IIId, respectively). Gross morphological examination of these lenses revealed dense opacification (cataract formation) in Group II, minimal opacification in some Group IIIa lenses and no opacification in Group I. The mean activities of the antioxidant enzymes catalase and glutathione peroxidase were significantly lower in Group II than in Group I or Group IIIa lenses, while malondialdehyde concentration (an indicator of lipid peroxidation) was significantly higher in Group II lenses than that in Group I or Group IIIa lenses. The second, in vivo phase of the study revealed dense opacification (cataract formation) in 100% of Wistar rat pups receiving subcutaneous sodium selenite alone (19 microM/kg body weight) but in only 37.5% of those receiving subcutaneous selenite and intraperitoneal ALCAR. These data suggest that ALCAR is able to significantly retard experimental selenite-induced cataractogenesis.
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Affiliation(s)
- P Geraldine
- Department of Animal Science, Bharathidasan University, Tiruchirapalli, India.
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25
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Nakajima E, Walkup RD, Ma H, Shearer TR, Azuma M. Low activity by the calpain system in primate lenses causes resistance to calcium-induced proteolysis. Exp Eye Res 2006; 83:593-601. [PMID: 16684519 DOI: 10.1016/j.exer.2006.02.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 02/15/2006] [Accepted: 02/16/2006] [Indexed: 11/25/2022]
Abstract
The human genome contains 14 genes for 80 kDa catalytic subunit of the calcium-activated protease calpain (EC 34.22.17), yet no calpain-like cleavage sites have been detected on human lens crystallins in vivo. The purpose of the present study was to provide a comprehensive study of calpain activation in human and macaque lenses developing experimental cataract due to lens culture in ionophore A23187. Zymography was used to measure calpain activity; SDS-PAGE and immunoblotting were used to detect hydrolysis of potential lens protein substrates. Quantitative PCR was used to measure transcripts for calpains and the endogenous inhibitor calpastatin. We found that the lack of appreciable calpain-induced proteolysis in primate lenses is most likely due to relatively low levels of endogenous calpain activity compared to the high levels of endogenous calpain inhibitor, calpastatin.
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Affiliation(s)
- E Nakajima
- Department of Integrative Biosciences, Oregon Health and Science University, 611 SW Campus Drive, Portland, OR 97239-3097, USA
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Fleschner CR. Connexin 46 and connexin 50 in selenite cataract. Ophthalmic Res 2005; 38:24-8. [PMID: 16192745 DOI: 10.1159/000088527] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Accepted: 04/12/2005] [Indexed: 11/19/2022]
Abstract
The purpose of this work was to determine if the lens gap junction proteins connexin 46 (Cx46) and connexin 50 (Cx50) were altered with the development of selenite-induced cataract. Cataracts were induced in young Sprague-Dawley rats with a single subcutaneous injection of sodium selenite; age-matched uninjected rats served as controls. Membrane fractions were isolated from homogenates of cortex and nucleus of normal and cataractous lenses by differential and discontinuous sucrose gradient centrifugation. Aliquots of urea-insoluble protein from membrane fractions were analyzed by quantitative densitometry of Western blots probed with antibodies to Cx46 and Cx50. A significant decrease in the more slowly migrating Cx46-reactive band, which represents phosphorylated Cx46, was found in the major membrane fraction of the cortex of cataractous lenses. There was no significant difference in the amounts of either Cx46 or Cx50 associated with selenite cataract in any of the membrane fractions examined. These results suggest that alteration of gap junction function (as evidenced by the change in phosphorylation of Cx46) may be associated with the development of the selenite cataract, but that neither Cx46 nor Cx50 is subject to the well-characterized proteolysis associated with the selenite cataract model.
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Affiliation(s)
- C R Fleschner
- A.T. Still University of Health Sciences, Kirksville College of Osteopathic Medicine, MO 63501-1443, USA.
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Shih M, Ma H, Nakajima E, David LL, Azuma M, Shearer TR. Biochemical properties of lens-specific calpain Lp85. Exp Eye Res 2005; 82:146-52. [PMID: 16054132 DOI: 10.1016/j.exer.2005.06.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Revised: 04/25/2005] [Accepted: 06/03/2005] [Indexed: 10/25/2022]
Abstract
Lens-specific Lp82 and ubiquitous m-calpain are neutral, calcium-activated, cysteine proteases. Both calpains are activated during rodent lens maturation and cataract formation. Lp85 calpain (Lens protein with MW=85 kDa) is a slightly larger splice variant of Lp82. Lp85 contains a 28 amino acid insert peptide (IS3) in calcium binding domain IV. Theoretically, the insert could alter the properties of Lp85 and influence proteolytic activity. The purpose of the present experiment was to compare the biochemical properties of Lp85 to Lp82 and m-calpain. Recombinant Lp85 and Lp82 were separately expressed using the baculovirus system and partially purified using Co2+ affinity and DEAE chromatographies. Calcium activation, pH dependency, and susceptibility to calpain inhibitors were assessed in a protease assay using BODIPY fluorescence-labeled casein substrate. Hydrolysis of lens proteins was assessed by SDS-PAGE and immunoblotting. Cleavage site analysis was performed by mass spectroscopy and Edman sequencing. Computer-based homology modeling was used to predict the influence of the IS3 region on the 3-dimensional structure of Lp85. Compared to m-calpain, Lp85 showed a lower calcium-activation requirement (K(50%act)=20 microM), marked insensitivity to, and cleavage of, the endogenous tissue inhibitor of calpains-calpastatin, and different preferred cleavage sites on alphaA-crystallin (five amino acid C-terminal truncation) and on aquaporin 0 (G239 and N246). Although the IS3 insert was predicted to form a loop protruding from the calcium binding region of Lp85, the biochemical properties of Lp85 studied were nearly identical to those of Lp82. Lp85 and Lp82 did not catalyze hydrolysis of each other, but both hydrolyzed m-calpain. Lp85 seems to be the enzymatic equivalent of Lp82. Both calpains could become active at lower cellular calcium levels than m-calpain. Lp85/Lp82 may have different functions than m-calpain since they cleave substrates at different sites. Lp85/Lp82 may regulate m-calpain activity by catalyzing the hydrolysis of calpastatin. The function of the IS3 insert on Lp85 remains unknown but is speculated to control subcellular distribution.
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Affiliation(s)
- M Shih
- Department of Integrative Biosciences, Oral Molecular Biology, Oregon Health & Science University, 611 SW Campus Drive, Portland, OR 97201-3097, USA
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Gao L, Qin W, Cui H, Feng G, Liu P, Gao W, Ma L, Li P, He L, Fu S. A novel locus of coralliform cataract mapped to chromosome 2p24-pter. J Hum Genet 2005; 50:305-310. [PMID: 15933805 DOI: 10.1007/s10038-005-0251-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Accepted: 03/23/2005] [Indexed: 11/28/2022]
Abstract
Congenital cataract is a common major abnormality of the eye, which can result in significant visual impairment or blindness in childhood. In this work, we studied four generations of a Chinese family that exhibited autosomal dominant coralliform cataract but no other ocular or systemic abnormalities. Members of the family were firstly genotyped with microsatellite markers at loci associated with congenital cataract on the reported regions of chromosomes 1, 2, 3, 10, 11, 12, 13, 15, 16, 17, 20, 21, and 22, but negative LOD scores were obtained. Following exclusion of these loci, a genome-wide scan was performed, and significant evidence of linkage was obtained for marker D2S2211 (Z = 2.69, theta = 0.00). In multipoint analysis, a maximum LOD score 4.87 (theta = 0.00) was reached between markers D2S2211 and D2S2164. Haplotype data indicated a coralliform cataract disease gene in a 26-cM interval at a novel disease locus 2p24-pter between D2S297 and D2S2268. No genes related to cataract in this region have been reported so far.
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Affiliation(s)
- Linghan Gao
- Laboratory of Medical Genetics, Harbin Medical University, 194 Xuefu Road, Harbin, 150086, P.R. China
| | - Wei Qin
- Bio-X Life Science Research Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai, 200030, P.R. China
- Institute for Nutritional Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 319 Yueyang Road, Shanghai, 200031, P.R. China
| | - Hao Cui
- Eye Hospital of the First affiliated Hospital, Harbin medical University, 23 Youzheng Street, Harbin, 150001, P.R. China
| | - Guoyin Feng
- Bio-X Life Science Research Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai, 200030, P.R. China
- Institute for Nutritional Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 319 Yueyang Road, Shanghai, 200031, P.R. China
| | - Ping Liu
- Eye Hospital of the First affiliated Hospital, Harbin medical University, 23 Youzheng Street, Harbin, 150001, P.R. China
| | - Weiqi Gao
- Eye Hospital of the First affiliated Hospital, Harbin medical University, 23 Youzheng Street, Harbin, 150001, P.R. China
| | - Lin Ma
- Eye Hospital of the First affiliated Hospital, Harbin medical University, 23 Youzheng Street, Harbin, 150001, P.R. China
| | - Pu Li
- Laboratory of Medical Genetics, Harbin Medical University, 194 Xuefu Road, Harbin, 150086, P.R. China
| | - Lin He
- Bio-X Life Science Research Center, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai, 200030, P.R. China
- Institute for Nutritional Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences, 319 Yueyang Road, Shanghai, 200031, P.R. China
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, 194 Xuefu Road, Harbin, 150086, P.R. China.
- Bio-pharmaceutical Key Laboratory of Heilongjiang Province, 194 Xuefu Road, Harbin, 150086, P.R. China.
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Abstract
Cataract, a leading cause of blindness worldwide, is a multifactorial eye disease. In developing countries the incidence of cataract among young generations is not uncommon due to malnutrition, excess exposure to ultraviolet radiation and so on. In developed countries, age-related cataract affecting the population over 65 years of age is a major concern. Oxidative stress was suggested to inflict damage to the lens and induce opacification, and a variety of antioxidant nutrients were tested for the prevention or delay of cataract development. Although promising results were obtained in animal studies of various antioxidants, epidemiological studies on human populations do not seem to support their protective effects unequivocally. It is unlikely that age-related cataract in man, similar to the ageing process itself, will be prevented or delayed by therapeutic drugs in the foreseeable future. At present, keeping a health-conscious life style (i.e., no smoking) may be the most effective and least expensive strategy to prevent the onset of age-related cataract.
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Affiliation(s)
- Hitoshi Shichi
- Kresge Eye Institute, Department of Ophthalmology, Wayne State University School of Medicine, 4717 St. Antoine, Detroit, MI 48201, USA.
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Seeberger TM, Matsumoto Y, Alizadeh A, Fitzgerald PG, Clark JI. Digital image capture and quantification of subtle lens opacities in rodents. JOURNAL OF BIOMEDICAL OPTICS 2004; 9:116-120. [PMID: 14715062 DOI: 10.1117/1.1630034] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A rapid, sensitive, and cost-effective method is reported for the subjective and objective documentation of subtle opacities in lenses of unanesthetized transgenic mice or selenite-injected rat pups as models for cataract formation. Animal eyes were dilated with eye drops and the animal was positioned in front of a Nikon FS2 photo slit lamp. Slit-lamp observations were recorded using a Canon Optura Pi digital video recorder. High-quality images of opacifying lenses were captured from the video and quantified using densitometry at progressive stages of opacification. In mice, targeted genomic deletion of the proteins CP49 (a lens-specific filament) or Six5 (a model for myotonic dystrophy) resulted in subtle cataracts that were easily recorded and quantified using this instrumentation. In rats, the early progressive changes leading to a dense nuclear opacity caused by selenite injection were easily documented using this instrumentation. Low-cost components combined with a conventional slit-lamp ophthalmoscope were used to capture high-quality images of selected stages of cataract formation for quantitative analysis using commercial software.
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Affiliation(s)
- T M Seeberger
- Department of Biological Structure, University of Washington School of Medicine, Seattle, WA 98195, USA
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Matsushima H, Mukai K, Obara Y, Yoshida S, Clark JI. Analysis of cytoskeletal proteins in posterior capsule opacification after implantation of acrylic and hydrogel intraocular lenses. J Cataract Refract Surg 2004; 30:187-94. [PMID: 14967289 DOI: 10.1016/s0886-3350(03)00497-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2003] [Indexed: 10/26/2022]
Abstract
PURPOSE To analyze selected lens cytoskeletal proteins in posterior capsule opacification (PCO) 2 weeks after intraocular lens (IOL) implantation in rabbits. SETTING Department of Ophthalmology, Dokkyo University School of Medicine, Tochigi, Japan. METHOD Eight 10-week-old albino rabbits were prepared and anesthetized for phacoemulsification and aspiration of the crystalline lens and implantation of an acrylic or a hydrogel IOL. Two weeks postoperatively, the rabbits were killed and the IOLs removed for immunohistochemistry. Deparaffinized tissue sections were processed with antibodies against alpha-smooth muscle actin (alpha-SMA) and beta-crystallin to observe the types of PCO with the 2 IOL types. The proteins in the PCO tissue and the normal lens were homogenized, centrifuged, and analyzed using SDS-polyacrylamide gel electrophoresis (SDS-PAGE) densitometric analysis and Western immunoblotting for actin and vimentin. RESULTS Immunohistochemistry demonstrated a fibroblastic cell type expressing alpha-SMA and partial regeneration of epithelial cells, resulting in a lenticular structure that stained irregularly for beta-crystallin. The immunoreactivity of fibroblast-like cells to beta-crystallin appeared weaker than that of the regenerated lenticular structure. SDS-PAGE showed variability in the content of cytoskeletal proteins in the insoluble fractions of the PCO. Degradation of the cytoskeletal components was greater with the acrylic IOL than with the hydrogel IOL. CONCLUSION Cytoskeletal proteins expressed during the formation of PCO and IOL implantation may have potential as therapeutic target proteins to improve the biocompatibility of IOLs.
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Affiliation(s)
- Hiroyuki Matsushima
- Department of Ophthalmology, Dokkyo University School of Medicine, Tokyo, Japan.
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32
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Yan H, Harding JJ, Hui YN, Li MY. Decreased chaperone activity of alpha-crystallin in selenite cataract may result from selenite-induced aggregation. Eye (Lond) 2003; 17:637-45. [PMID: 12855974 DOI: 10.1038/sj.eye.6700419] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To investigate the role of chaperone activity of alpha-crystallin in selenite-induced cataract formation. METHODS Selenite cataract was induced in Sprague-Dawley rats by five subcutaneous injections of sodium selenite over a 20-day period starting at 8-10 days postpartum. alpha-Crystallin was separated from the rat lenses by size-exclusion chromatography. Bovine alpha(L)-crystallin and beta(L)-crystallin were isolated for studies in vitro, and for the chaperone assays. The protective effects of both alpha(H)- and alpha(L)-crystallin were measured spectrophotometrically in four different assay procedures including the thermally induced aggregation of catalase and beta(L)-crystallin, and the fructation- and heat-induced inactivation of catalase. The bovine alpha(L)-crystallin was incubated with different concentrations of sodium selenite for 72 h and then its chaperone activity against heat-induced beta(L)-crystallin aggregation was assayed. The aggregation of selenite-treated alpha(L)-crystallin was analysed by molecular sieve high-performance liquid chromatography (HPLC). RESULTS The protection of alpha(H)-crystallin was less than that of alpha(L)-crystallin in both normal and cataractous lenses. The chaperone activities of both alpha(H)- and alpha(L)-crystallin in selenite cataract were decreased compared with normal lenses. The protection provided by both alpha(H)-crystallin and alpha(L)-crystallin against the thermal aggregation of catalase was much greater than their protection against thermally and chemically induced inactivation. HPLC analysis demonstrated aggregation of alpha-crystallin by sodium selenite after 24 h incubation in a dose-dependent fashion. CONCLUSION The chaperone activity of alpha-crystallin presented parallel patterns of activity with different methods, further supporting the view that the different assays measure essentially the same property. The decreased chaperone activity of alpha-crystallin in selenite cataract may result from selenite-induced aggregation.
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Affiliation(s)
- H Yan
- Department of Ophthalmology, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
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33
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Brooks J, Fleschner CR. Identification of a vimentin-reactive Peptide associated with ocular lens membranes as cytokeratin. Ophthalmic Res 2003; 35:8-11. [PMID: 12566857 DOI: 10.1159/000068194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Indexed: 11/19/2022]
Abstract
We wished to identify a 44-kD peptide isolated from lens membrane fractions which has apparent immunoreactivity to antivimentin and to antiphakinin. Urea-soluble proteins from rat lens membrane fractions were separated by two-dimensional electrophoresis, transferred to polyvinylidene fluoride membranes and probed with monoclonal antibodies to vimentin or cytokeratins, or a polyclonal antibody to phakinin. The monoclonal antibody to vimentin recognized the expected protein (M(r) = 56 kD, pI = 5.1) and several smaller and more acidic peptides including a 44-kD spot with a pI of 4.9. A similar pattern of immunoreactivity was found with commercially available purified vimentin. The polyclonal antibody to phakinin recognized the expected protein (M(r) = 52 kD, pI = 5.0) and several smaller and more acidic peptides, including a 44-kD spot with a pI of 4.9. Matrix-assisted laser desorption ionization mass spectroscopy analysis of the tryptic digest of the spot corresponding to 44 kD and pI of 4.9 identified neither vimentin nor phakinin but did identify peptides derived from ovalbumin (added to samples as an internal standard) and cytokeratin 1. Antibodies which recognize cytokeratin 1 reacted weakly with a 44-kD peptide which comigrated with the 44-kD vimentin-immunoreactive peptide in adjacent lanes of single-dimension SDS polyacrylamide gels. The 44-kD acidic (pI = 4.9) peptide which reacts with a monoclonal antibody to vimentin may be derived from cytokeratin 1.
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Affiliation(s)
- J Brooks
- Truman State University, Kirksville College of Osteopathic Medicine, Kirksville, Mo., USA
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34
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Abstract
PURPOSE To describe the intermediate filament proteins vimentin, filensin and phakinin associated with different fractions isolated from neonatal, 10 day old and 20 day old rat lenses. METHODS Fractions were isolated by differential and density gradient centrifugation of lens homogenates from neonatal, 10 day old and 20 day old rats. Aliquots of the 8 M urea soluble proteins of each fraction were separated by SDS PAGE, transferred to PVDF membranes, the membranes were probed with antibodies to vimentin, filensin or phakinin, and analyzed by computer. RESULTS Over the 20 day growth period, the water soluble fraction increased and the most abundant membrane fraction was characterized by a significant increase in its urea insoluble protein and a significant decrease in its urea soluble protein. There were no significant quantitative changes in any of the other fractions. The concentration of each intermediate filament protein was greatest in the cytoskeletal fraction and over the 20 day period, the amount of vimentin associated with this fraction dramatically decreased, and the amounts of filensin and phakinin dramatically increased. Among the membrane fractions, the greatest concentration of each intermediate filament protein was found in the non sedimenting membrane fraction (NSMF) which was the least abundant fraction recovered. Filensin and phakinin associated with the other three major membrane fractions increased over the 20 day growth period, but the level of vimentin did not significantly change. CONCLUSIONS The NSMF may represent a domain of the lens plasma membrane particularly important in interaction between plasma membrane and cytoskeleton and as the membrane-cytoskeleton protein architecture of rat lens changes over the first 20 days of life, the changes are readily detected in the different membrane fractions.
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Affiliation(s)
- Charles Ricky Fleschner
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501, USA.
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35
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Abstract
Cataract is the major cause of blindness and of visual impairment worldwide, so its prevention is of the greatest importance. At present no drug therapy is licensed for use in the UK or the US, so the only treatment for cataract is by surgery, which is expensive and has adverse effects. This article reviews research on prevention of cataract by a variety of agents, including micronutrients as well as drugs. Benefits have been claimed for many compounds or mixtures and this review concentrates on those most extensively studied. Information on possible benefits of putative anticataract agents comes from a variety of approaches, from laboratory experiments, both in vitro and in vivo, to epidemiological studies in patients. Sorbitol-lowering drugs were the first to be examined systematically and progressed to clinical trials which were disappointing, and now the entire rationale for their use in prevention of cataract is questionable. Micronutrients showed little promise in animals but came to clinical trial in patients with cataract without the publication of any major benefit. Pantethine showed more promise in animal studies but the only clinical trial was abandoned early. A variety of laboratory and epidemiological evidence supports the benefits of aspirin-like drugs but there has been no trial specifically in patients with cataract. Add-on studies to trials of aspirin for other indications have not been encouraging. Research into other compounds is interesting but less advanced.
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Affiliation(s)
- J J Harding
- Nuffield Laboratory of Ophthalmology, University of Oxford, England.
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36
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Thiagarajan G, Chandani S, Sundari CS, Rao SH, Kulkarni AV, Balasubramanian D. Antioxidant properties of green and black tea, and their potential ability to retard the progression of eye lens cataract. Exp Eye Res 2001; 73:393-401. [PMID: 11520114 DOI: 10.1006/exer.2001.1049] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aqueous extracts of green and black tea are shown to quench reactive oxygen species such as singlet oxygen, superoxide and hydroxyl radicals, prevent the oxidative cross-linking of test proteins and inhibit single strand breakage of DNA in whole cells. They are also seen to be able to counteract the oxidative insult mounted by cigarette smoke. In rats in which cataract was induced by subcutaneous injection of selenite, administration of green or black tea extracts led to a retardation of the progression of lens opacity, suggesting the potential cataracto-static ability of tea.
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Affiliation(s)
- G Thiagarajan
- Hyderabad Eye Research Foundation, L. V. Prasad Eye Institute, Hyderabad 500 034, India
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37
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Abstract
The ordered pattern of type I collagen fibrils in the transparent cornea is an example of specialization in the formation of functional ultrastructure. In contrast, the disordered and amorphous distribution of cytoplasmic proteins in the transparent lens resembles the structure of most cells. While the organization of cytoplasmic proteins is often considered to be random, the compartmentalization of functional proteins in biological cells and the organization provided by cytoskeletal elements suggests that non-random patterns of organization are common. Attempts to quantify disordered, amorphous patterns of ultrastructure in cells and tissues have been unsuccessful, in part, because the cellular organization of structural proteins including collagen, keratin, cytoskeletal and crystallin proteins is complex. Characterization of the complex patterns observed in electron micrographs is a fundamental problem in structural biology. This paper reviews the use of Fourier and power law analyses of electron micrographs of cornea and lens as models for ordered and disordered ultrastructure of cells and tissues.
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Affiliation(s)
- J I Clark
- Departments of Biological Structure and Ophthalmology, 357420 Biological Structure, University of Washington, Seattle, WA 98195-7420, USA
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38
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Qian W, Shichi H. Cataract formation by a semiquinone metabolite of acetaminophen in mice: possible involvement of Ca(2+)and calpain activation. Exp Eye Res 2000; 71:567-74. [PMID: 11095908 DOI: 10.1006/exer.2000.0914] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Acetaminophen, an analgesic/antipyretic, is metabolized by hepatic cytochrome P450 to N -acetyl- p -benzoquinone imine (NAPQI), which is transported by blood circulation to the eye and induces anterior cortical cataract in mice. In this study we injected NAPQI into the anterior chamber of mouse eye and investigated time-dependent cellular responses in the lens. After a lag period of about 2 hr following NAPQI injection, lens opacification as determined by measurement of light scattering by the lens became evident and progressively increased thereafter. There was no difference in the profile of opacity development between a P450-inducer responsive mouse strain and a non-responsive strain. During the lag period, a marked increase in free intracellular Ca(2+)in the lens epithelium was observed at 1 hr by confocal fluorescence microscopy with a Ca(2+)probe. Concurrent with the free Ca(2+)increase, there was a 300% rise in the activity of the non-lysosomal neutral protease calpain in the lens at 1 hr after NAPQI injection. Evidence indicated degradation of vimentin in the lens in which calpain activity was enhanced. Co-injection of calpain inhibitors (N-Ac-Leu-Leu-norleucinol and N-Ac-Leu-Leu-methioninal) with NAPQI protected animals completely from cataract development, although a rise in free intracellular Ca(2+)in the lens epithelium was still observed. Lenses from the protected mice did not exhibit enhanced calpain activity. These results suggest the following sequence of events as a possible mechanism of NAPQI-induced cataract. NAPQI introduced in the anterior chamber of the eye enters the lens epithelial cells and disturbs Ca(2+)homeostasis with a resultant rise in free intracellular Ca(2+)which in turn activates calpain in the epithelium. The neutral protease then degrades cellular proteins (e.g. cytoskeletal proteins) and initiates anterior cortical cataract formation.
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Affiliation(s)
- W Qian
- Kresge Eye Institute, Department of Ophthalmology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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39
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Lo WK, Wen XJ, Zhou C. Regional differences in actin stability in the rat lens as visualized by immunofluorescence labeling under the influence of pH. Exp Eye Res 2000; 71:323-7. [PMID: 10973741 DOI: 10.1006/exer.2000.0881] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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Abstract
The elevated expression of stress proteins is considered to be a universal response to adverse conditions, representing a potential mechanism of cellular defense against disease and a potential target for novel therapeutics, including gene therapy and chaperone-modulating reagents. Recently, a single mutation in the small heat-shock protein human alphaB-crystallin was linked to desmin-related myopathy, which is characterized by abnormal intracellular aggregates of intermediate filaments in human muscle. New findings demonstrate that the high level of expression of stress proteins can contribute to an autoimmune response and can protect proteins that contribute to disease processes.
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Affiliation(s)
- J I Clark
- 357420 Biological Structure and Ophthalmology, University of Washington, Seattle, WA 98195-7420, USA.
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41
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Abstract
Cytoplasmic transparency is a unique feature of lens cells. The cytoplasm is a concentrated solution of crystallin proteins with minor constituents that include cytoskeletal proteins and lens specific intermediate filaments. Under normal physiological conditions, the proteins exist as a single transparent phase. With normal aging, progressive modification of the interactions between lens proteins occurs so that conditions within the lens become favorable for phase separation. These conditions produce intracellular inhomogeneities that approach or exceed the dimensions of the wavelength of visible light (400 to 700 nm) and light scattering from lens cells increases. The resulting opacification is the primary factor in the visual loss experienced in cataract, the leading cause of blindness in the world. We study biochemical factors that regulate the cytoplasmic phase separation and maintain normal cellular transparency.
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Affiliation(s)
- J I Clark
- University of Washington, School of Medicine, Seattle 98195, USA
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42
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Clark JI, Matsushima H, David LL, Clark JM. Lens cytoskeleton and transparency: a model. Eye (Lond) 1999; 13 ( Pt 3b):417-24. [PMID: 10627819 DOI: 10.1038/eye.1999.116] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The function of the cytoskeleton in lens was first considered when cytoplasmic microtubules were observed in elongating fibre cells of the chick lens nearly 40 years ago. Since that time, tubulin, actin, vimentin and intermediate filaments have been identified and found to function in mitosis, motility and cellular morphology during lens cell differentiation. A role for the cytoskeleton in accommodation has been proposed and modification of the cytoskeletal proteins has been observed in several cataract models. Recently, a progressive increase in protein aggregation and lens opacification was found to correspond with the loss of cytoskeletal protein in the selenite model for cataract. In the present report a model is proposed for the role of tubulin, actin, vimentin, spectrin and the lens-specific filaments, filensin and CP49, in the establishment and maintenance of transparent lens cell structure.
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Affiliation(s)
- J I Clark
- Department of Biological Structure, University of Washington, School of Medicine, Seattle 98195-7420, USA.
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43
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Fleschner CR. Intermediate filament cytoskeletal proteins associated with bovine lens native membrane fractions. Curr Eye Res 1998; 17:409-18. [PMID: 9561833 DOI: 10.1080/02713689808951222] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE To examine the intermediate filament cytoskeletal proteins associated with native membrane fractions isolated from bovine lenses. METHODS Decapsulated bovine lenses were divided into cortex and nucleus. The lens regions were homogenized and separated into water-soluble and water-insoluble fractions by centrifugation. Sedimenting membrane fractions were isolated from the water-insoluble fraction by discontinuous sucrose-density-gradient centrifugation and the non-sedimenting membrane fractions were isolated from the Kbr high-density water-soluble fractions by flotation, during overnight centrifugation. The intermediate filament peptides of the membrane fractions were examined by Western blot analysis, using monoclonal antibodies to filensin, cytoskeletal protein 49 (CP49) and vimentin. RESULTS Filensin immunoreactive peptides were found in all membrane fractions of both cortex and nucleus. The parent 115 kDa filensin was found almost exclusively in the urea-soluble protein of cortical membrane fractions, and was the predominant filensin immunoreactive peptide only in the urea-soluble protein of the cortical sedimenting membrane fraction isolated from the 25%/45% sucrose density interface. The predominant filensin immunoreactive peptide of all other samples migrated with a M(r) of 53 kDa. CP49 immunoreactive peptides were found almost exclusively in the urea-soluble protein of all membrane fractions from both the cortex and nucleus. The cortical non-sedimenting membrane fraction and the nuclear membrane fraction of the 25%/45% sucrose density interface were notably deficient in CP49. Vimentin immunoreactive peptides were found in both urea-soluble and urea-insoluble proteins of membrane fractions from the cortex only. Vimentin was particularly enriched in the cortical non-sedimenting membrane fraction. The urea-insoluble filensin immunoreactive peptides were only partially removed by alkali extraction, indicating a very avid association with the membrane. Two dimensional electrophoresis revealed that the urea-soluble protein of the major cortical membrane fraction contained two different filensin-derived 53 kDa fragments. CONCLUSIONS The non-sedimenting membrane fraction, which may reflect a distinct domain of the lens plasma membrane, possesses a membrane-associated cytoskeletal composition different from that of the major sedimenting membrane fractions.
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Affiliation(s)
- C R Fleschner
- Department of Biochemistry, Kirksville College of Osteopathic Medicine, MO 63501, USA.
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