Decreased miR-146a expression in acute ischemic stroke directly targets the Fbxl10 mRNA and is involved in modulating apoptosis.

BACKGROUND: miR-146a, a strong pro-apoptotic factor in some pathophysiological processes, is reported to be involved in ischemic stroke (IS), though its role remains unclear. Fbxl10 is an active anti-apoptotic factor and a predicted target of miR-146a. We hypothesized that dysregulation of miR-146a contributes to ischemic injury by targeting Fbxl10.
METHODS: Circulating miRNAs were detected by miRNA microarray and qRT-PCR. miR-146a targets were predicted using bioinformatics and confirmed with a dual luciferase reporter assay. We used an in vitro ischemic model of oxygen-glucose deprivation and reperfusion (OGD/R) to mimic cerebral ischemia/reperfusion (I/R) conditions. Expression of miR-146a, Fbxl10 and Bcl2l2 mRNAs, and Fbxl10 and Bcl2l2 proteins was verified by qRT-PCR and Western blotting. The effects of miR-146a on neuronal cell apoptosis were evaluated by flow cytometry.
RESULTS: A significant reduction in miR-146a expression was observed in acute ischemic stroke (AIS). A dual-luciferase reporter assay showed that Fbxl10, but not Bcl2l2, is a target of miR-146a. Transfection with miR-146a mimics promoted apoptosis in SK-N-SH cells and significantly reduced expression of Fbxl10. Conversely, miR-146a inhibition attenuated OGD/R-induced neuronal cell death and significantly up-regulated Fbxl10 expression.
CONCLUSIONS: miR-146a expression was significantly down-regulated in AIS, and Fbxl10 was identified as a target of miR-146a. Moreover, up-regulation of Fbxl10, a miR-146a target, likely protects neurons from ischemic death.