Insulin promotes amyloid precursor protein metabolism in an Alzheimer's disease cell model

Abstract

Objective To investigate how insulin affects the metabolism of amyloid precursor protein (APP) in a cell model of Alzheimer's disease (AD). Methods Human neuroblastoma SH-SY5Y cells and the nonneural cell lines HEK293 and 2EB2 were treated with different concentrations of insulin for 48 h, and the changes in cell viability were evaluated with CCK-8 assay. The expression levels of APP, C-terminal fragment of APP (CTF), β-site APP cleaving enzyme 1 (BACE1), the α-secretase ADAM10 (a disintegrin and metalloproteinase 10) and γ-secretase presenilin 1 (PS1) in the cells were detected using Western blotting. ELISA was used to determine the cellular expression levels of Aβ40 and Aβ42. The key signaling pathways mediated by insulin were screened using a protein chip. The effect of insulin on protein phosphorylation levels of AKT and GSK3β pathways was examined by detecting p-AKT and p-GSK3β expression in the cells with Western blotting. Results Treatment with insulin below 10 μmol/L did not obviously affect the viability of the cells (P>0.05). Western blotting showed that treatment with 1.00 and 10.00 μmol/L insulin significantly increased the protein expression of APP and CTF (P 0.05). Conclusion Insulin promotes the metabolism of APP into CTF and Aβ42, which play certain rolesin pathogenesis of AD.

Keywords

• alzheimer's disease
• insulin
• amyloid precursor protein
• β-amyloid
• akt/gsk3β