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Kulkarni T, Angom RS, Das P, Bhattacharya S, Mukhopadhyay D. Nanomechanical insights: Amyloid beta oligomer-induced senescent brain endothelial cells. Biochim Biophys Acta Biomembr 2019; 1861:183061. [PMID: 31513781 DOI: 10.1016/j.bbamem.2019.183061] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 09/06/2019] [Indexed: 12/16/2022]
Abstract
Senescent cells accumulate in various peripheral tissues during aging and have been shown to exacerbate age-related inflammatory responses. We recently showed that exposure to neurotoxic amyloid β (Aβ1-42) oligomers can readily induce a senescence phenotype in human brain microvascular endothelial cells (HBMECs). In the present work, we used atomic force microscopy (AFM) to further characterize the morphological properties such as cell membrane roughness and cell height and nanomechanical properties such as Young's modulus of the membrane (membrane stiffness) and adhesion resulting from the interaction between AFM tip and cell membrane in Aβ1-42 oligomer-induced senescent human brain microvascular endothelial cells. Morphological imaging studies showed a flatter and spread-out nucleus in the senescent HBMECs, both characteristic features of a senescent phenotype. Furthermore, the mean cell body roughness and mean cell height were lower in senescent HBMECs compared to untreated normal HBMECs. We also observed increased stiffness and alterations in the adhesion properties in Aβ1-42 oligomer-induced senescent endothelial cells compared to the untreated normal HBMECs suggesting dynamic reorganization of cell membrane. We then show that vascular endothelial growth factor receptor 1 (VEGFR-1) knockdown or overexpression of Rho GTPase Rac 1 in the endothelial cells inhibited senescence and reversed these nanomechanical alterations, confirming a direct role of these pathways in the senescent brain endothelial cells. These results illustrate that nanoindentation and topographic analysis of live senescent brain endothelial cells can provide insights into cerebrovascular dysfunction in neurodegenerative diseases such as Alzheimer's disease.
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Kam MK, Lee DG, Kim B, Lee HS, Lee SR, Bae YC, Lee DS. Peroxiredoxin 4 ameliorates amyloid beta oligomer-mediated apoptosis by inhibiting ER-stress in HT-22 hippocampal neuron cells. Cell Biol Toxicol 2019; 35:573-588. [PMID: 31147869 DOI: 10.1007/s10565-019-09477-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 04/25/2019] [Accepted: 05/06/2019] [Indexed: 10/26/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder caused by amyloid beta oligomers (AβO), which induce cell death by triggering oxidative stress and endoplasmic reticulum (ER) stress. Oxidative stress is regulated by antioxidant enzymes, including peroxiredoxins. Peroxiredoxins (Prx) are classified into six subtypes, based on their localization and cysteine residues, and protect cells by scavenging hydrogen peroxide (H2O2). Peroxiredoxin 4 (Prx4) is unique in being localized to the ER; however, whether Prx4 protects neuronal cells from AβO-induced toxicity remains unclear, although Prx4 expression is upregulated in AβO-induced oxidative stress and ER stress. In this study, we established HT-22 cells in which Prx4 was either overexpressed or silenced to investigate its role in AβO-induced toxicity. AβO-stimulation of HT-22 cells with overexpressed Prx4 caused decreases in both AβO-induced ROS and ER stress (followed by ER expansion). In contrast, AβO stimulation caused increases in both ROS and ER stress that were notably higher in HT-22 cells with silenced Prx4 expression than in HT-22 cells. Consequently, Prx4 overexpression decreased apoptotic cell death and ameliorated the AβO-induced increase in intracellular Ca2+. Therefore, we conclude that Prx4 has a protective effect against AβO-mediated oxidative stress, ER stress, and neuronal cell death. Furthermore, these results suggest that Prx4 may be a target for preventing AβO toxicity in AD. Graphical abstract .
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Affiliation(s)
- Min Kyoung Kam
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
| | - Dong Gil Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
| | - Bokyung Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea.,Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children/UC Davis School of Medicine, Sacramento, CA, 95817, USA.,Department of Neurology, School of Medicine, UC Davis, Davis, CA, 95817, USA
| | - Hyun-Shik Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea
| | - Sang-Rae Lee
- National Primate Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Chungcheonbuk-do, Republic of Korea
| | - Yong Chul Bae
- Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea
| | - Dong-Seok Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Republic of Korea.
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Ngo ST, Truong DT, Tam NM, Nguyen MT. EGCG inhibits the oligomerization of amyloid beta (16-22) hexamer: Theoretical studies. J Mol Graph Model 2017; 76:1-10. [PMID: 28658644 DOI: 10.1016/j.jmgm.2017.06.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 06/16/2017] [Accepted: 06/19/2017] [Indexed: 11/21/2022]
Abstract
An extensive replica exchange molecular dynamics (REMD) simulation was performed to investigate the progress patterns of the inhibition of (-)-epigallocatechin-3-gallate (EGCG) on the Aβ16-22 hexamer. Structural variations of the oligomers without and with EGCG were monitored and analyzed in detail. It has been found that EGCG prevents the formation of Aβ oligomer through two different ways by either accelerating the Aβ oligomerization or reducing the β-content of the hexamer. It also decreases the potential "highly toxic" conformations of Aβ oligomer, which is related to the conformations having high order β-sheet sizes. Both electrostatic and van der Waals interaction energies are found to be involved to the binding process. Computed results using quantum chemical methods show that the π-π stacking is a critical factor of the interaction between EGCG and the peptides. As a result, the binding free energy of the EGCG to the Aβ peptides is slightly larger than that of the curcumin.
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