miR-146a/KLF4 axis in epileptic mice: A novel regulator of synaptic plasticity involving STAT3 signaling

Abstract

Objective: This study is aimed to investigate the mechanism of miR-146a/KLF4 axis regarding epilepsy seizure and synaptic plasticity.

Methods: Pentylenetetrazol (PTZ)-kindling mouse model of epilepsy was established and evaluated by Racine's scale. PTZ-treated mice were subjected to stereotactic injection of miR-146a antagomir and pre-KLF4 to verify the role of miR-146a and KLF4 in mice. Primary hippocampal neurons from fetal mouse were isolated and identified through immunofluorescence for microtubule-associated protein (MAP)-2. Cellular models of epilepsy were prepared using magnesium-free extracellular fluid and then the neurons were transfected with miR-146a antagomir, miR-146a agomir, miR-146a agomir + pre-KLF4, AG490 (an inhibitor of STAT3 signal pathway) or miR-146a agomir + AG490. The binding site between miR-146a and KLF4 was predicted and identified. The expression levels of miR-146a, KLF4, CREB, Synaptotagmin-11 (SYT11), and STAT3-related proteins were measured in addition to the morphology of neurons and length of neurite. The severity of synaptic plasticity was assessed according to the levels of CREB and SYT11.

Results: The expression of miR-146a was elevated and KLF4 expression was decreased in epileptic mice. Stereotactic injection of miR-146a antagomir and pre-KLF4 reduced the seizure scores of epileptic mice. Transfection of miR-146a antagomir or pre-KLF4 could attenuate synaptic plasticity in epileptic mice and epileptic cellular models. miR-146a can negatively regulate KLF4 in epileptic cellular models to mediate synaptic plasticity. Epilepsy was attenuated in AG490 and miR-146a agomir + AG490 groups compared with that in Model group.

Conclusion: miR-146a inhibits KLF4 to activate STAT3, thus promoting synaptic plasticity in epileptic mice.

Keywords: Epilepsy; KLF4; STAT3; Synaptic plasticity; miR-146a.