In vivo and in vitro analysis on the effect of LRP/LR on alzheimer's disease related proteins, TERT expression and telomerase activity in alzheimer's disease models
Date
2018
Authors
Bignoux, Monique
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Abstract
Alzheimer’s disease (AD) is the most common form of progressive neurodegenerative disorders afflicting more than 47 million people worldwide. This poses a significant economic cost and highlights the need to develop disease-modifying therapeutic strategies. AD is characterised by the formation of extracellular amyloid beta (Aβ) plaques and intracellular neurofibrillary tangles. It has been shown that the 37kDa/67kDa laminin receptor (LRP/LR) and telomerase are implicated in the pathogenesis of AD through their respective interactions with Aβ and the AD-associated proteins: the amyloid precursor protein (APP), β- and γ-secretase. Aβ inhibits telomerase activity and LRP/LR has a function in regulating telomerase activity as well as in the internalisation and shedding of Aβ. We have previously shown in vitro, that blockade of the 37kDa/67kDa Laminin Receptor (LRP/LR) with the anti-LRP/LR specific antibody, IgG1-iS18, resulted in reduced Aβ-induced cytotoxicity and Aβ accumulation. The current study consisted of two parts, in vivo analysis to determine the effect of blocking LRP/LR with IgG1-iS18 and in vitro analysis on the overexpression of LRP intracellularly. To test the effect of blocking LRP/LR on Aβ formation and AD associated symptoms, 5XFAD AD transgenic mice received IgG1-iS18 through intranasal administration. The 5XFAD mice harbour three mutant human APP (695) and two PS1 Familial AD mutations to induce amyloid pathology through overexpression of APP. Furthermore, the resultant effects on the expression of the AD-related proteins, mTERT and γH2AX expression were investigated. We show that this treatment resulted in an improvement in memory, decreased vacuolization and Aβ plaque formation. Moreover, a significant decrease in Aβ42 protein expression with a concomitant increase in APP and telomerase reverse transcriptase (mTERT) levels was observed. These data indicate IgG1-iS18 as a potentially powerful therapeutic tool for AD. To investigate the effect of overexpressing LRP in in vitro AD models, the SH-SY5Y neuronal and HEK293 AD cell culture models were stably transfected with pCIneo-moLRP::FLAG, to induce overexpression of LRP. This treatment resulted in increased LRP and hTERT levels, with co-localisation between the LRP and hTERT, together with a concomitant decrease in Aβ levels. Additionally, this treatment increased telomerase activity and rescued cells from Aβ-mediated cytotoxicity. These data suggest that overexpression of LRP intracellularly might represent a potential therapeutic strategy for treatment of AD. Taken altogether, targeting LRP/LR in an AD context has provided insight into the disease and simultaneously provided alternative therapeutic options for halting AD progression.
Description
Dissertation submitted in fulfillment of the degree
Master of Science (MSc)
in Biochemistry and cell Biology in the Faculty of Science
May 2018
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Citation
Bignoux, Monique Jeanette (2018) In vivo and in vitro analysis on the effect of LRP/LR on Alzheimer's disease related proteins, TERT expression and telomerase activity in Alzheimer's disease models, University of the Witwatersrand, Johannesburg, <http://hdl.handle.net/10539/26182>