miR-200b-3p antagomir inhibits neuronal apoptosis in oxygen-glucose deprivation (OGD) model through regulating β-TrCP

Background: Hypoxia-ischemic brain damage (HIBD) is a primary cause of morbidity and disability in survivors of preterm infants. We previously discovered that miR-200b-3p plays an important role in HIBD via targeting Slit2. This study was designed to identify novel targets of miR-200b-3p and investigate the relationship between miR-200b-3p and its downstream effectors.Methods and results: Cultured primary rat hippocampal neurons were used in the model of oxygen-glucose deprivation (OGD) and RT-qPCR was utilized to detect the alterations of miR-200b-3p in these cells following the OGD. Our study found that the expression of miR-200b-3p was up-regulated in neurons post OGD. Bioin-formatics analysis identified that beta transducin repeat-containing protein (beta-TrCP) is a target gene of miR-200b-3p, and our luciferase reporter gene assay confirmed that miR-200b-3p can interact with beta-TrCP mRNA. Hypoxia-ischemic brain damage was induced in three-day-old SD rats and inhibition of miR-200b-3p by injection of antagomir into bilateral lateral ventricles enhanced beta-TrCP expression at both the mRNA and protein levels in rats' brains. TUNEL staining and CCK-8 assays found that the survival of hippocampal neurons in the miR-200b-3p antagomir group was improved significantly (p<0.05), whereas apoptosis of neurons in the miR-200b-3p antagomir group was significantly decreased (p<0.05), as compared with the OGD group. However, silencing of beta-TrCP by beta-TrCP siRNA impaired the neuroprotective effect of miR-200b-3p antagomir. H&E staining showed that miR-200b-3p attenuated the pathological changes in the hippocampal region of rats with HIBD.Conclusion: Our study has demonstrated that beta-TrCP is a target gene of miR-200b-3p and that inhibition of miR-200b-3p by antagomir attenuates hypoxia-ischemic brain damage via beta-TrCP.