MicroRNA-27a-3p Downregulation Inhibits Inflammatory Response and Hippocampal Neuronal Cell Apoptosis by Upregulating Mitogen-Activated Protein Kinase 4 (MAP2K4) Expression in Epilepsy: In Vivo and In Vitro Studies
Jun Lu, Nina Zhou, Ping Yang, Lanqiuzi Deng, Ganzhe Liu
Department of Neurosurgery, The Brain Hospital of Hunan Province, Changsha, Hunan, China (mainland)
Med Sci Monit 2019; 25:8499-8508
This study aimed to discover the effect and mechanism of microRNA-27a-3p (miR-27a-3p) in epilepsy.
MATERIAL AND METHODS: To perform our investigation, in vivo and in vitro models of epilepsy were induced using kainic acid (KA). Expression of miR-27a-3p in the hippocampus of epileptic rats or normal rats or neuronal cells was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Racine score was used to assess seizures in epileptic rats. Cell viability and cell apoptosis were analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was performed to detect inflammatory factors expression.
RESULTS: Significantly higher expression of miR-27a-3p in the hippocampus of epileptic rats and in KA-induced neurons was observed. We found that miR-27a-3p inhibitor alleviated seizures in epileptic rats. miR-27a-3p inhibitor also inhibited apoptosis of hippocampal neurons in epileptic rats, promoted Bcl2 expression, and decreased Bax and Caspase3 expression. The results showed that miR-27a-3p inhibitor effectively reduced the expression levels of interleukin-1ß (IL-1ß), IL-6, and tumor necrosis factor-alpha (TNF-alpha) in hippocampal tissues of epileptic rats. Dual luciferase reporter assay showed that mitogen-activated protein kinase 4 (MAP2K4) was a direct target of miR-27a-3p. miR-27a-3p inhibitor significantly promoted the cell viability of KA-induced neurons, inhibited cell apoptosis, promoted the expression of Bcl-2, and decreased Bax and Caspase3 expression, and all these changes were abolished by MAP2K4-siRNA co-transfection.
CONCLUSIONS: Our preliminary findings indicated that miR-27a-3p inhibitor protected against epilepsy-induced inflammatory response and hippocampal neuronal apoptosis by targeting MAP2K4.
Keywords: Apoptosis, Epilepsy, MicroRNAs, Neurons