Post-translationally modified human lens crystallin fragments show aggregation in vitro

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

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Increased Association of Deamidated αA-N101D with Lens Membrane of Transgenic αAN101D vs. Wild Type αA Mice: Potential Effects on Intracellular Ionic Imbalance and Membrane Disorganization

10.21203/rs.2.17769/v4 ◽

2020 ◽

Author(s):

Om Srivast ◽

Kiran Srivast ◽

Roy Joseph ◽

Landon Wilson

Keyword(s):

Epithelial Cells ◽

Western Blot ◽

Immunogold Labeling ◽

Human Lens ◽

Membrane Association ◽

Related Protein ◽

Wild Type ◽

Age Related ◽

Ionic Imbalance

Abstract We have generated two mouse models, in one by inserting the human lens αAN101D transgene in CRYαAN101D mice, and in the other by inserting human wild-type αA-transgene in CRYαAWT mice. The CRYαAN101D mice developed cortical cataract at about 7-months of age relative to CRYαAWT mice. The objective of the study was to determine the following relative changes in the lenses of CRYαAN101D- vs. CRYαAWT mice: age-related changes with specific emphasis on protein insolubilization, relative membrane-association of αAN101D vs. WTαA proteins, and changes in intracellular ionic imbalance and membrane organization. Methods: Lenses of varying ages from CRYαAWT and CRYαAN101D mice were compared for an age-related protein insolubilization. The relative lens membrane-association of the αAN101D- and WTαA proteins in the two types of mice was determined by immunohistochemical-, immunogold-labeling-, and western blot analyses. The relative levels of membrane-binding of recombinant αAN101D- and WTαA proteins was determined by an in vitro assay, and the levels of intracellular Ca2+ uptake and Na, K-ATPase mRNA were determined in the cultured epithelial cells from lenses of the two types of mice.Results: Compared to the lenses of CRYαAWT, the lenses of CRYαAN101D mice exhibited: (A) An increase in age-related protein insolubilization beginning at about 4-months of age. (B) A greater lens membrane-association of αAN101D- relative to WTαA protein during immunogold-labeling- and western blot analyses, including relatively a greater membrane swelling in the CRYαAN101D lenses. (C) During in vitro assay, the greater levels of binding αAN101D- relative to WTαA protein to membranes was observed. (D) The 75% lower level of Na, K-ATPase mRNA but 1.5X greater Ca2+ uptake were observed in cultured lens epithelial cells of CRYαAN101D- than those of CRYαAWT mice. Conclusions: The results show that an increased lens membrane association of αAN101D--relative WTαA protein in CRYαAN101D mice than CRYαAWT mice occurs, which causes intracellular ionic imbalance, and in turn, membrane swelling that potentially leads to cortical opacity.

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On the Anticataractogenic Effects of L-Carnosine: Is It Best Described as an Antioxidant, Metal-Chelating Agent or Glycation Inhibitor?

Oxidative Medicine and Cellular Longevity ◽

10.1155/2016/3240261 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Hamdy Abdelkader ◽

Michael Longman ◽

Raid G. Alany ◽

Barbara Pierscionek

Keyword(s):

Epithelial Cells ◽

Antioxidant Activities ◽

Ex Vivo ◽

Antioxidant Properties ◽

Radical Scavenging ◽

Human Lens ◽

Lens Epithelial Cells ◽

Metal Chelating ◽

Human Lens Epithelial Cells

Purpose.L-Carnosine is a naturally occurring dipeptide which recently gained popularity as an anticataractogenic agent due to its purported antioxidant activities. There is a paucity of research and conclusive evidence to support such claims. This work offers compelling data that help clarify the mechanism(s) behind the anticataract properties of L-carnosine.Methods.Direct in vitro antioxidant free radical scavenging properties were assayed using three different antioxidant (TEAC, CUPRAC, and DPPH) assays. Indirect in vitro and ex vivo antioxidant assays were studied by measuring glutathione bleaching capacity and total sulfhydryl (SH) capacity of bovine lens homogenates as well as hydrogen-peroxide-stress assay using human lens epithelial cells. Whole porcine lenses were incubated in high galactose media to study the anticataract effects of L-carnosine. MTT cytotoxicity assays were conducted on human lens epithelial cells.Results.The results showed that L-carnosine is a highly potent antiglycating agent but with weak metal chelating and antioxidant properties. There were no significant decreases in lens epithelial cell viability compared to negative controls. Whole porcine lenses incubated in high galactose media and treated with 20 mM L-carnosine showed a dramatic inhibition of advanced glycation end product formation as evidenced by NBT and boronate affinity chromatography assays.Conclusion.L-Carnosine offers prospects for investigating new methods of treatment for diabetic cataract and any diseases that are caused by glycation.

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p-Coumaric Acid Protects Human Lens Epithelial Cells against Oxidative Stress-Induced Apoptosis by MAPK Signaling

Oxidative Medicine and Cellular Longevity ◽

10.1155/2018/8549052 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7 ◽

Cited By ~ 13

Author(s):

Jiao Peng ◽

Ting-ting Zheng ◽

Yue Liang ◽

Li-fang Duan ◽

Yao-dong Zhang ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Mapk Signaling ◽

Human Lens ◽

Lens Epithelial Cells ◽

Dependent Manner ◽

Coumaric Acid ◽

Underlying Mechanisms ◽

Induced Apoptosis

To protect against oxidative stress-induced apoptosis in lens epithelial cells is a potential strategy in preventing cataract formation. The present study aimed at studying the protective effect and underlying mechanisms of p-coumaric acid (p-CA) on hydrogen peroxide- (H2O2-) induced apoptosis in human lens epithelial (HLE) cells (SRA 01–04). Cells were pretreated with p-CA at a concentration of 3, 10, and 30 μM before the treatment of H2O2 (275 μM). Results showed that pretreatment with p-CA significantly protected against H2O2-induced cell death in a dose-dependent manner, as well as downregulating the expressions of both cleaved caspase-3 and cleaved caspase-9 in HLE cells. Moreover, p-CA also greatly suppressed H2O2-induced intracellular ROS production and mitochondrial membrane potential loss and elevated the activities of T-SOD, CAT, and GSH-Px of H2O2-treated cells. As well, in vitro study showed that p-CA also suppressed H2O2-induced phosphorylation of p-38, ERK, and JNK in HLE cells. These findings demonstrate that p-CA suppresses H2O2-induced HLE cell apoptosis through modulating MAPK signaling pathways and suggest that p-CA has a potential therapeutic role in the prevention of cataract.

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Growth of human lens epithelial cells on the anterior lens capsule in vitro

Vision Research ◽

10.1016/0042-6989(95)98768-5 ◽

1995 ◽

Vol 35 (1) ◽

pp. S199

Author(s):

J Meyer

Keyword(s):

Epithelial Cells ◽

Lens Capsule ◽

Human Lens ◽

Lens Epithelial Cells ◽

Human Lens Epithelial Cells ◽

Anterior Lens Capsule

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P 207 Bendazac decreases in vitro glycation of human lens crystallins

Vision Research ◽

10.1016/0042-6989(95)90523-5 ◽

1995 ◽

Vol 35 ◽

pp. S194

Author(s):

C. Marques ◽

J.S. Ramalho ◽

P. Pereira ◽

M.C. Mota

Keyword(s):

Human Lens ◽

Lens Crystallins

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In Vivo Quasi-Elastic Light Scattering Eye Scanner Detects Molecular Aging in Humans

The Journals of Gerontology Series A ◽

10.1093/gerona/glaa121 ◽

2020 ◽

Vol 75 (9) ◽

pp. e53-e62

Author(s):

Olga Minaeva ◽

Srikant Sarangi ◽

Danielle M Ledoux ◽

Juliet A Moncaster ◽

Douglas S Parsons ◽

...

Keyword(s):

Light Scattering ◽

Human Lens ◽

Fetal Life ◽

Healthy Human ◽

Elastic Light Scattering ◽

Lens Proteins ◽

Age Dependent ◽

Molecular Aging

Abstract The absence of clinical tools to evaluate individual variation in the pace of aging represents a major impediment to understanding aging and maximizing health throughout life. The human lens is an ideal tissue for quantitative assessment of molecular aging in vivo. Long-lived proteins in lens fiber cells are expressed during fetal life, do not undergo turnover, accumulate molecular alterations throughout life, and are optically accessible in vivo. We used quasi-elastic light scattering (QLS) to measure age-dependent signals in lenses of healthy human subjects. Age-dependent QLS signal changes detected in vivo recapitulated time-dependent changes in hydrodynamic radius, protein polydispersity, and supramolecular order of human lens proteins during long-term incubation (~1 year) and in response to sustained oxidation (~2.5 months) in vitro. Our findings demonstrate that QLS analysis of human lens proteins provides a practical technique for noninvasive assessment of molecular aging in vivo.

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