Circ-HUWE1 Knockdown Alleviates Amyloid-β-Induced Neuronal Injury in SK-N-SH Cells via miR-433-3p Release-Mediated FGF7 Downregulation

Alzheimer’s disease (AD) is a progressive neurodegenerative disease, characterized by Amyloid-β accumulation-induced neuronal injury. Emerging evidence shows that circular RNA (circRNA) is involved in AD development. The aim of this study was to illustrate the role of circ-HUWE1 in Amyloid-β accumulation-induced neuronal injury. Quantitative real-time PCR (qPCR) or western blot was conducted for the expression analysis of circ-HUWE1, miR-433-3p, and fibroblast growth factor 7 (FGF7). In functional assays, cell viability was determined by CCK-8 assay, and cell apoptosis was examined by flow cytometry assay, the protein levels of apoptosis-related markers, and caspase1 or caspase3 activity. The release of pro-inflammatory factors was monitored by ELISA. The predicted binding relationship between miR-433-3p and circ-HUWE1 or FGF7 was validated by dual-luciferase reporter assay. We discovered that circ-HUWE1 absence alleviated Amyloid-β-induced cell viability degradation, cell apoptosis, and inflammatory responses in SK-N-SH cells. MiR-433-3p was a target of circ-HUWE1, and miR-433-3p inhibition reversed the effects of circ-HUWE1 knockdown. In addition, FGF7 was a downstream target of miR-433-3p whose function could be abolished by FGF7 reintroduction. Circ-HUWE1 positively regulated FGF7 expression via competitively targeting miR-433-3p. Moreover, circ-HUWE1 knockdown activated the WNT signaling pathway in Amyloid-β-treated SK-N-SH cells by targeting the miR-433-3p/FGF7 axis. In conclusion, circ-HUWE1 knockdown alleviates Amyloid-β-induced neuronal injury in SK-N-SH cells via miR-433-3p release-mediated FGF7 depletion.