Exploring the effects of squalene in the PERK/ATF4/eIF2?/CHOP signalling pathway in an in vitro Alzheimer Disease model and insilico approach

Abstract

Recent studies emphasize the pivotal role of endoplasmic reticulum (ER) stress in Alzheimer's disease (AD), highlighting the need for further investigation into this critical link. In response to ER stress, cells increase reactive oxygen species (ROS) production, leading to heightened oxidative stress. This interplay has sparked interest in antioxidant molecules such as squalene (SQ) as potential therapeutic agents. The primary objective of this study was to examine the impact of SQ on the unfolded protein response (UPR) pathway triggered by ER stress in an in vitro AD model. Herein, molecular docking analysis was performed to evaluate SQ interactions with target proteins, followed by in vitro assays. Human bone marrow-derived mesenchymal stem cells were differentiated into neuronal-like cells and characterized via immunostaining. The cells were then exposed to A beta 1-42 toxicity to establish an in vitro AD model. To assess the effects of SQ treatment following A beta 1-42 exposure, UPR-related proteins (BIP, p-PERK, PERK, eIF2 alpha, p-eIF2 alpha, ATF4, CHOP) were analysed by Western blotting; ROS levels were quantified to evaluate oxidative stress, and a TUNEL assay was performed to assess apoptosis. Our findings indicate that SQ alters protein expression within the UPR pathway in the AD experimental model. Notably, amyloid-beta levels were significantly reduced in the SQ-treated group (p<0.001). Furthermore, SQ reduced ROS levels. These results suggest that SQ holds potential as a therapeutic agent for mitigating amyloid-beta toxicity.Graphical abstractEffects of Squalene (SQ) on UPR-related protein expression in neuronal cells. Results illustrate the expression levels of UPR-associated proteins (BIP, p-PERK, PERK, eIF2 alpha, p-eIF2 alpha, ATF4, CHOP) in neuronal cells with and without SQ treatment. SQ administration notably reduces p-PERK, p-eIF2 alpha, ATF4, and CHOP levels, suggesting a regulatory effect on the UPR pathway. The downregulation of these proteins indicates that SQ may alleviate ER stress, potentially contributing to improved cellular homeostasis.