Metformin protects lens epithelial cells against senescence in a naturally aged mouse model

AbstractThe senescence of lens epithelial cells (LECs) is a major factor leading to age-related cataract (ARC). ARC results in visual impairment and severe vision loss in elderly patients. However, the specific mechanism of ARC remains unclear, and there are no effective therapeutic agents to halt the formation of ARC. This study aimed to assess the underlying mechanism of the formation of ARC and investigate the potential anti-ageing effect of metformin (MET) on ARC. Male C57BL/6 mice were divided into three groups: the control group having young mice (3 months old, n = 40), the naturally aged group (aged 20 months, n = 60) and the MET group (MET, 20 months, n = 60). Mice in the control and the naturally aged groups were fed a standard purified mouse diet ad libitum and water, whereas those in the MET group were fed chows supplemented with 0.1% MET for 10 months. The transparency of the lens and age-associated proteins p21 and p53 were analysed in the LECs of these three groups. Furthermore, we determined the expressions of the adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway and the effect of MET on this pathway in LECs during the ageing process of ARC. In addition, the relationship between autophagy and the senescence of LECs and the role of MET in the autophagy of LECs during the ageing process of ARC were examined. Our results indicated that age-related inactivation of the AMPK pathway and impairment of autophagy might contribute to the senescence of LECs and the occurrence of ARC. More importantly, these results demonstrated that MET effectively alleviated the senescence of LECs and the formation of ARC probably via inactivation of the AMPK pathway and augmentation of autophagy. These findings revealed that MET can be exploited as a potentially useful drug for ARC prevention. Our study will help in enlightening the development of innovative strategies for the clinical treatment of ARC.

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Metformin Protects Lens Epithelial Cells Against Senescence in Naturally Aged Model of Mouse

10.21203/rs.3.rs-414664/v1 ◽

2021 ◽

Author(s):

Mengmeng Chen ◽

Yushan Fu ◽

Xu Wang ◽

Ruitong Wu ◽

Dongmei Su ◽

...

Keyword(s):

Epithelial Cells ◽

Aging Process ◽

Vision Loss ◽

Aging Effect ◽

Lens Epithelial Cells ◽

Control Group ◽

Young Control ◽

Aged Group ◽

Ampk Pathway ◽

Age Related

Abstract Background: The senescence of lens epithelial cells (LECs) is a major factor of age-related cataract (ARC). ARC results in visual impairment and severe vision loss in elderly. However, the specific mechanism of ARC is not yet clear and there are no effective therapeutic agents to halt the formation of ARC. The current study aimed to further explore the underlying mechanism of formation of ARC and investigate the potential anti-aging effect of metformin (MET) on ARC. Methods: Male C57BL/6 mice were divided into three groups: the young control group (Young, 3 months, n=40), the naturally aged group (Aged, 20months, n=60) and MET group (MET, 20 months, n=60). The young control group (Young, 3 months, n=40) and the naturally aged group (Aged, 20months, n=60) mice received ad libitum standard purified mouse diet and water, while the MET group mice were fed on chows supplied with 0.1% MET for 10 months. The transparency of lens and age-associated proteins P21, P53 were assessed in LECs in three groups. Furthermore, we determined the expressions of AMPK pathway and the effect of MET on AMPK pathway in LECs during the aging process of ARC. Besides, the relationship of autophagy and the senescence of in LECs and the role of MET in the autophagy in in LECs during the aging process of ARC were examined. Results: Our results indicated that age-related inactivation of AMPK pathway and age-related impairment of autophagy might contribute to the senescence of in LECs and occurrence of ARC. Importantly, these results demonstrated that MET effectively alleviated the senescence of in LECs and the formation of ARC probably via inactivation of AMPK pathway and augmentation of autophagy. Conclusion: These findings reveal that MET can be exploited as a potentially useful drug for ARC prevention. Our study will be informative for development of innovative strategies to the clinical treatment of ARC.

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Ultrastructure changes and expression of NLRP3 inflammasome in lens anterior capsule of patient with cataracts associated with uveitis

10.21203/rs.2.16181/v1 ◽

2019 ◽

Author(s):

Chu Zhang ◽

Chong-Hui Ying ◽

siqin Sun ◽

yuechun Wen ◽

Zicheng Zhu

Keyword(s):

Epithelial Cells ◽

Ultrastructural Changes ◽

Lens Epithelial Cells ◽

Control Group ◽

Anterior Capsule ◽

Caspase 1 ◽

Pyrin Domain ◽

Age Related ◽

The Difference ◽

Domain 3

Abstract ● AIM : T o investigate the expression of nod-like receptor pyrin domain 3 (NLRP3) in lens anterior capsule of Uveitis associated with cataract and observe the ultrastructural changes of them . ● Methods: 17(22 eyes) cases of uveitis associated with cataract were selected a s experimental group and 1 0 (18 eyes) cases of age-related cataract were selected a s contro l group. The expressions of NLRP3, apoptosis-related speckle protein （ASC） and caspase-1 protein were tested by immunohistochemical and the ultrastructural changes of anterior capsul e was observed under electron microscope. ● Results: The expression of NLRP3 、 caspase-1 and ASC in the anterior capsu le of cataracts associated with uveitis was significantly higher than that of the control group, the difference was statistically significant (p ＜ 0.05). The apoptotic changes of lens epithelial cells in uveitis associated with cataract were obvious, and the apoptotic changes of lens epithelial cells were mild in age-related cataract patients. ● Conclusion: Strongly postive expressed NLRP3 inflamma some and obvious apoptotic changes are founded in the lens epithelial cells of patients with uveitis associat ed with cataract, suggesting that NLRP3 inflamma some and the apoptosis of lens epithelial cells may play a role in the progress of uveitis associat ed with cataract.

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Osteogenic Effects of Naringenin Are Mediated Through the Activation of AMPK Pathway

Current Developments in Nutrition ◽

10.1093/cdn/nzaa040_012 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 12-12

Author(s):

Savion Carswell ◽

Tanzim Mridha ◽

Cynthia E Francis ◽

Shashidharamurthy Taval ◽

Srujana Rayalam

Keyword(s):

Bone Marrow ◽

Adenosine Monophosphate ◽

Calcium Deposition ◽

Alizarin Red ◽

Ampk Pathway ◽

Funding Sources ◽

Osteogenic Markers ◽

Age Related ◽

Marrow Mesenchymal Stem Cells ◽

Post Hoc

Abstract Objectives Bone marrow mesenchymal stem cells are the precursor cells for adipocytes and osteoblasts. The accumulation of adipocytes in bone marrow at the expense of osteoblastogenesis is a major factor contributing to age-related bone loss. Grapefruit flavonoid naringenin (NAR) was shown to promote osteogenesis but the mechanism behind these effects is not clear. In this study, we propose to demonstrate that the osteogenic effects of NAR are mediated through the activation of adenosine monophosphate-activated kinase (AMPK) pathway. Methods MC3T3-E1 pre-osteoblast cells were cultured using alpha MEM medium (Invitrogen) supplemented with 10% fetal bovine serum and 1% penicillin/streptomycin. Osteogenic differentiation was induced by using differentiation medium purchased from Stem Cell Technologies. Western blotting, ELISA and alizarin red assays were conducted to test our hypothesis. Results NAR increased calcium deposition in MC3T3 cells compared to DMSO control after 21-day differentiation period. Additionally, in the presence of AMPK inhibitor Ara-A, NAR-induced calcium deposition was suppressed compared to NAR alone. Furthermore, while NAR increased phosphorylation of AMPK, the combination of NAR and Ara-A significantly decreased AMPK phosphorylation. Finally, Ara-A suppressed NAR-induced expression of osteogenic markers including Runx2, osteoprotegerin and osteocalcin suggesting that NAR-induced osteogenesis is partly mediated through AMPK pathway. All data were expressed as the mean ± SEM, minimum n = 3. Comparisons were made by using one-way analysis of variance (ANOVA) followed by Tukey's post hoc tests. Conclusions The suppression of osteogenic markers and calcium deposition in the presence of NAR plus Ara-A, an AMPK inhibitor, compared to NAR alone provide evidence that the observed osteogenic effects of NAR are in part mediated through the activation of AMPK pathway. These data combined with our previous reports of anti-adipogenic effects of NAR suggest that NAR may have potential therapeutic applications for osteoporosis by not only promoting osteogenesis but also inhibiting adipogenesis in the bone marrow. Funding Sources Division of Research, PCOM and NIH-1R03 AI128254–01A1.

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The Histone Deacetylase Inhibitor AN7, Attenuates Choroidal Neovascularization in a Mouse Model

International Journal of Molecular Sciences ◽

10.3390/ijms20030714 ◽

2019 ◽

Vol 20 (3) ◽

pp. 714

Author(s):

Mor Dahbash ◽

Ruti Sella ◽

Elinor Megiddo-Barnir ◽

Yael Nisgav ◽

Nataly Tarasenko ◽

...

Keyword(s):

Growth Factor ◽

Mouse Model ◽

Histone Deacetylase ◽

Choroidal Neovascularization ◽

Histone Deacetylase Inhibitor ◽

Vision Loss ◽

Age Related Macular Degeneration ◽

Control Group ◽

Age Related ◽

Deacetylase Inhibitor

: Choroidal neovascularization (CNV) is a complication of age-related macular degeneration and a major contributing factor to vision loss. In this paper, we show that in a mouse model of laser-induced CNV, systemic administration of Butyroyloxymethyl-diethyl phosphate (AN7), a histone deacetylase inhibitor (HDACi), significantly reduced CNV area and vascular leakage, as measured by choroidal flatmounts and fluorescein angiography. CNV area reduction by systemic AN7 treatment was similar to that achieved by intravitreal bevacizumab treatment. The expression of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF-2), and the endothelial cells marker CD31, was lower in the AN7 treated group in comparison to the control group at the laser lesion site. In vitro, AN7 facilitated retinal pigmented epithelium (RPE) cells tight junctions’ integrity during hypoxia, by protecting the hexagonal pattern of ZO-1 protein in the cell borders, hence reducing RPE permeability. In conclusion, systemic AN7 should be further investigated as a possible effective treatment for CNV.

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Thioredoxin Binding Protein-2 Regulates Autophagy of Human Lens Epithelial Cells under Oxidative Stress via Inhibition of Akt Phosphorylation

Oxidative Medicine and Cellular Longevity ◽

10.1155/2016/4856431 ◽

2016 ◽

Vol 2016 ◽

pp. 1-17 ◽

Cited By ~ 5

Author(s):

Jiaojie Zhou ◽

Ke Yao ◽

Yidong Zhang ◽

Guangdi Chen ◽

Kairan Lai ◽

...

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Cell Viability ◽

Binding Protein ◽

Negative Regulator ◽

Human Lens ◽

Lens Epithelial Cells ◽

Human Lens Epithelial Cells ◽

Age Related

Oxidative stress plays an essential role in the development of age-related cataract. Thioredoxin binding protein-2 (TBP-2) is a negative regulator of thioredoxin (Trx), which deteriorates cellular antioxidant system. Our study focused on the autophagy-regulating effect of TBP-2 under oxidative stress in human lens epithelial cells (LECs). Human lens epithelial cells were used for cell culture and treatment. Lentiviral-based transfection system was used for overexpression of TBP-2. Cytotoxicity assay, western blot analysis, GFP/mCherry-fused LC3 plasmid, immunofluorescence, and transmission electronic microscopy were performed. The results showed that autophagic response of LECs with increased LC3-II, p62, and GFP/mCherry-LC3 puncta (P<0.01) was induced by oxidative stress. Overexpression of TBP-2 further strengthens this response and worsens the cell viability (P<0.01). Knockdown of TBP-2 attenuates the autophagic response and cell viability loss induced by oxidative stress. TBP-2 mainly regulates autophagy in the initiation stage, which is mTOR-independent and probably caused by the dephosphorylation of Akt under oxidative stress. These findings suggest a novel role of TBP-2 in human LECs under oxidative stress. Oxidative stress can cause cell injury and autophagy in LECs, and TBP-2 regulates this response. Hence, this study provides evidence regarding the role of TBP-2 in lens and the possible mechanism of cataract development.

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Synchrotron-based FTIR microspectroscopy of protein aggregation and lipids peroxidation changes in human cataractous lens epithelial cells

Scientific Reports ◽

10.1038/s41598-020-72413-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Martin Kreuzer ◽

Tanja Dučić ◽

Marko Hawlina ◽

Sofija Andjelic

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Protein Aggregation ◽

Photon Flux ◽

Lens Epithelial Cells ◽

Ftir Microspectroscopy ◽

Age Related ◽

Cataractous Lens ◽

Synchrotron Light ◽

Common Environmental Factor

Abstract Cataract is the leading cause of blindness worldwide but the mechanisms involved in the process of cataractogenesis are not yet fully understood. Two most prevalent types of age-related cataracts are nuclear (N) and cortical (C) cataracts. A common environmental factor in most age-related cataracts is believed to be oxidative stress. The lens epithelium, the first physical and biological barrier in the lens, is build from lens epithelial cells (LECs). LECs are important for the maintenance of lens transparency as they control energy production, antioxidative mechanisms and biochemical transport for the whole lens. The purpose of this study is to characterize compounds in LECs originated from N and C cataracts, by using the synchrotron radiation-based Fourier Transform Infrared (SR-FTIR) microspectroscopy, in order to understand the functional importance of their different bio-macromolecules in cataractogenesis. We used the SR-FTIR microspectroscopy setup installed on the beamline MIRAS at the Spanish synchrotron light source ALBA, where measurements were set to achieve single cell resolution, with high spectral stability and high photon flux. The results showed that protein aggregation in form of fibrils was notably pronounced in LECs of N cataracts, while oxidative stress and the lipids peroxidation were more pronounced in LECs of C cataracts.

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

BioMed Research International ◽

10.1155/2020/6069390 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Ting Li ◽

Yanhong Huang ◽

Wenkai Zhou ◽

Qichang Yan

Keyword(s):

Oxidative Stress ◽

Epithelial Cells ◽

Western Blot ◽

Molecular Mechanisms ◽

Luciferase Reporter ◽

Human Lens ◽

Lens Epithelial Cells ◽

Age Related ◽

Spot Number ◽

Gene Assay

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

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