Silencing miR-20a-5p inhibits axonal growth and neuronal branching and prevents epileptogenesis through RGMa-RhoA-mediated synaptic plasticity.

Epileptogenesis is a potential process. Mossy fibre sprouting (MFS) and synaptic plasticity promote epileptogenesis. Overexpression of repulsive guidance molecule a (RGMa) prevents epileptogenesis by inhibiting MFS. However, other aspects underlying the RGMa regulatory process of epileptogenesis have not been elucidated. We studied whether RGMa could be modulated by microRNAs and regulated RhoA in epileptogenesis. Using microRNA databases, we selected four miRNAs as potential candidates. We further experimentally confirmed miR-20a-5p as a RGMa upstream regulator. Then, in vitro, by manipulating miR-20a-5p and RGMa, we investigated the regulatory relationship between miR-20a-5p, RGMa and RhoA, and the effects of this pathway on neuronal morphology. Finally, in the epilepsy animal model, we determined whether the miR-20a-5p-RGMa-RhoA pathway influenced MFS and synaptic plasticity and then modified epileptogenesis. Our results showed that miR-20a-5p regulated RGMa and that RGMa regulated RhoA in vitro. Furthermore, in primary hippocampal neurons, the miR-20a-5p-RGMa-RhoA pathway regulated axonal growth and neuronal branching; in the PTZ-induced epilepsy model, silencing miR-20a-5p prevented epileptogenesis through RGMa-RhoA-mediated synaptic plasticity but did not change MFS. Overall, we concluded that silencing miR-20a-5p inhibits axonal growth and neuronal branching and prevents epileptogenesis through RGMa-RhoA-mediated synaptic plasticity in the PTZ-induced epilepsy model, thereby providing a possible strategy to prevent epileptogenesis.