Syringin Prevents Aβ25-35-Induced Neurotoxicity in SK-N-SH and SK-N-BE Cells by Modulating miR-124-3p/BID Pathway.

Alzheimer's disease (AD) is a neurodegenerative disorder disease, disturbing people's normal life. Syringin was mentioned to antagonize Amyloid-β (Aβ)-induced neurotoxicity. However, the action mechanism is still not fully elucidated. This study aimed to explore a molecular mechanism of syringin in defending Aβ-induced neurotoxicity. SK-N-SH and SK-N-BE cells were treated with amyloid β-protein fragment 25-35 (Aβ25-35) to induce cell neurotoxicity. The injury effects were distinguished by assessing cell viability and cell apoptosis using cell counting kit-8 (CCK-8) assay and flow cytometry assay, respectively. The expression of Cleaved-caspase3 (Cleaved-casp3), B cell lymphoma/leukemia-2 (Bcl-2), Bcl-2 associated X protein (Bax) and BH3 interacting domain death agonist (BID) at the protein level was determined by western blot. The expression of miR-124-3p and BID was detected using quantitative real-time polymerase chain reaction (qRT-PCR). The interaction between miR-124-3p and BID was predicted by the online database starBase and confirmed by dual-luciferase reporter assay plus RNA pull-down assay. Aβ25-35 treatment inhibited cell viability and induced cell apoptosis, while the addition of syringin recovered cell viability and suppressed cell apoptosis. MiR-124-3p was significantly downregulated in Aβ25-35-treated SK-N-SH and SK-N-BE cells, and BID was upregulated. Nevertheless, the addition of syringin reversed their expression. BID was a target of miR-124-3p, and its downregulation partly prevented Aβ25-35-induced injuries. Syringin protected against Aβ25-35-induced neurotoxicity by enhancing miR-124-3p expression and weakening BID expression, and syringin strengthened the expression of miR-124-3p to diminish BID level. Syringin ameliorated Aβ25-35-induced neurotoxicity in SK-N-SH and SK-N-BE cells by regulating miR-124-3p/BID pathway, which could be a novel theoretical basis for syringin to treat AD.