The Protective Effect Of Caspr Against Ab-Induced Neurotoxicity Via Activation Of The Akt/Bad Pathway

Objective: Abnormal beta-amyloid (A beta 42) deposition induced neuronal injury is a key pathological feature of the Alzheimer's disease (AD). Contactin-associated protein (Caspr) is reported to be involved in the regulation of A beta 42 production and neuronal function, but the underlying mechanism remains unknown. The aim of this study was to elucidate the neuro-protective effects of Caspr against A beta 42-induced neurotoxicity in human embryonic kidney (HEK) 293 cells, a cell line with many neuronal properties.Methods: HEK 293 cell lines were seeded in 96-well plates at 2x104 cells/well in RPMI 1640 media, and allowed to attach for 24 hours, and subsequently incubated for 24 hours with new media containing a different concentration of Caspr. MTT assay was used to test cell viability. Western blot and RNA extraction and Reverse Transcription Polymerase Chain Reaction (RT-PCR) were used to test the expression of the proteins and mRNAs. Human Caspr small interfering RNA (siRNA) was synthesized by Invitrogen. Apoptosis was detected with the Annexin-V-Fluos Staining Kit, which consists of Annexin-V and propidium iodide (PI) by Flow cytometry.Results: The results showed that the overexpression of Caspr can significantly reverse A beta 42-induced cell toxicity and decrease A beta 42-induced HEK 293 cell apoptosis. Furthermore, our results demonstrated that Caspr can attenuate the Bax/Bcl-2 expression ratio and inhibit the cleavage of caspase-9 and caspase-3 by activating Akt and inhibiting Bad. Our data suggest that Caspr may exhibit a neuro-protective effect against A beta 42-induced neurotoxicity via activation of the Akt/Bad signaling pathway.Conclusion: Caspr is a potential therapeutic agent for prevention and treatment of AD.