MicroRNA-204 suppresses epileptiform discharges through regulating TrkB-ERK1/2-CREB signaling in cultured hippocampal neurons

Abstract

MicroRNAs (miRs) have been increasingly recognized as post-transcriptional regulators involved in the pathogenesis of epilepsy. Extensive evidence suggests that inhibition of tropomyosin related kinase type B (TrkB) signaling limits epileptogenesis. It has been reported that miR-204 directly targeted and downregulated TrkB protein in a variety of cancers to suppress tumorigenesis, but its effect on epileptogenesis is unknown. Here we showed that miR-204 was downregulated in cultured hippocampal neurons following status epilepticus (SE) induced by Mg2+-free treatment. Overexpression of miR-204 using a transfection technique negatively regulated the expression of TrkB mRNA. Insight into the downstream signaling pathway activated by TrkB may provide valuable clues to the underlying mechanisms of epileptogenesis. Biochemical measures revealed activation of phospholipase Cγ1 (PLCγ1), extracellular signal-regulated kinase1/2 (ERK1/2) and cAMP response-element binding protein (CREB) signaling molecules in the Mg2+-free model in hippocampal neurons, of which ERK1/2-CREB but not PLCγ1 signaling pathway was able to be inhibited by miR-204. Epileptiform discharges assessed using whole-cell current–clamp techniques were suppressed by miR-204 in cultured hippocampus neurons of SE. These results suggest that miR-204 exerts an antiepileptogenic effect in the Mg2+-free model in hippocampal neurons through regulating TrkB and downstream ERK1/2-CREB signaling pathway.