Inhibition of 37/67kDa Laminin-1 Receptor Restores APP Maturation and Reduces Amyloid-β in Human Skin Fibroblasts from Familial Alzheimer's Disease.

Antaripa Bhattacharya,Nunzia Montuori,Valeria D’Argenio,Antonio Lavecchia,Filomena Napolitano,Alessandra Lo Bianco,Nunzia Mollo,Daniela Sarnataro,Francesca Margheri,Adriana Limone,Giuseppina Minopoli,Antonella Izzo,Alessandra Mocali,Federica Di Maggio

doi:10.3390/jpm10040232

Abstract

Alzheimer’s disease (AD) is a fatal neurodegenerative disorder caused by protein misfolding and aggregation, affecting brain function and causing dementia. Amyloid beta (Aβ), a peptide deriving from amyloid precursor protein (APP) cleavage by-and γ-secretases, is considered a pathological hallmark of AD. Our previous study, together with several lines of evidence, identified a strict link between APP, Aβ and 37/67kDa laminin receptor (LR), finding the possibility to regulate intracellular APP localization and maturation through modulation of the receptor. Here, we report that in fibroblasts from familial AD (fAD), APP was prevalently expressed as an immature isoform and accumulated preferentially in the transferrin-positive recycling compartment rather than in the Golgi apparatus. Moreover, besides the altered mitochondrial network exhibited by fAD patient cells, the levels of pAkt and pGSK3 were reduced in respect to healthy control fibroblasts and were accompanied by an increased amount of secreted Aβ in conditioned medium from cell cultures. Interestingly, these features were reversed by inhibition of 37/67kDa LR by NSC47924 a small molecule that was able to rescue the “typical” APP localization in the Golgi apparatus, with consequences on the Aβ level and mitochondrial network. Altogether, these findings suggest that 37/67kDa LR modulation may represent a useful tool to control APP trafficking and Aβ levels with implications in Alzheimer’s disease.

Highlights

Extracellular amyloid plaques formed by deposits of Aβ peptide and intracellular neurofibrillary tangles, composed of hyperphosphorylated tau protein, represent the major neuropathologic event characterizing Alzheimer’s disease (AD) [1].Aβ derives from a sequential proteolytic cleavage of amyloid precursor protein (APP) by β- and γ-secretases
Contrary to control fibroblasts where APP was localized in the Golgi apparatus, we found that in familial AD (fAD) fibroblast cell lines, APP lost its Golgi localization resulting mainly distributed in transferrin-positive recycling endosomes
We investigated the effects of a specific inhibitor of 37/67kDa laminin receptor (LR) [33] on APP maturation and Aβ generation in fibroblasts from patients affected by familial Alzheimer’s disease, compared with healthy unaffected controls

Summary

Introduction

Extracellular amyloid plaques formed by deposits of Aβ peptide and intracellular neurofibrillary tangles, composed of hyperphosphorylated tau protein, represent the major neuropathologic event characterizing Alzheimer’s disease (AD) [1]. Aβ derives from a sequential proteolytic cleavage of amyloid precursor protein (APP) by β- and γ-secretases. The overwhelming majority of dominant mutations causing familial AD occurs in three genes: APP, PSEN1 (Presenilin-1), and PSEN2 (Presenilin-2). Mutations in PSEN-1 and -2 have been described to increase the Aβ42/Aβ40 ratio [4,5]. 19 different AD causing mutations in the γ-secretase enzyme PSEN-2 have been reported and were shown to alter the APP processing by increasing both the total level of Aβ and the Aβ42/40 ratio [6,7], suggesting that the dysregulation of Aβ production from APP can be considered a common effect of these mutations

Methods

Results

Conclusion