Objective: Alzheimer's disease (AD) is a neurodegenerative disorder with limited success in the prognosis of patients worldwide. The microRNA (miRNA) technology shows an encouraging trend in the therapeutics of AD. The study aimed to investigate the role of miR-132 and its underlying mechanism involving neuronal apoptosis and Tau phosphorylation in the pathophysiology of AD.
Materials and methods: Frozen human postmortem brain samples and neurons cells were used as the specimens. The expression of miR-132 was assessed in AD and mild-cognitive (MCI) group by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Then, miR-132 mimic, ASO-miR-132, and corresponding controls were transfected into necrotic cells. Flow cytometry was used to detected cell apoptosis in necrotic cells. qRT-PCR, Western blot, and immunoprecipitation were used to quantify and identify apoptosis-related factors (Bax and Bcl-2), Tau phosphorylation, CDK-5, GTDC-1 levels in necrotic cells. Furthermore, Dual-Luciferase reporter assay was used to predict a direct target of miR-132.
Results: The expression of miR-132 was significantly higher in patients with MCI and AD compared to the normal group. Overexpression of miR-132 induced neuronal apoptosis by increasing Bax and decreasing Bcl-2 and also up-regulated phosphorylation of Tau, Rb, Histone H1, and CDK-5 expressions. Besides, GTDC-1 was identified as a direct target gene of miR-132. However, GTDC-1 markedly reversed the promoting effect of miR-132 on cell apoptosis and Tau phosphorylation.
Conclusions: MiR-132 plays an important role in the pathogenesis of AD via regulation of cell apoptosis and GTDC-1/CDK-5/Tau phosphorylation signaling mechanism. It may be a potential therapeutic target in patients with AD.