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SUMMARYObjective: MicroRNAs (miRNAs) are noncoding small RNAs that control gene expression at the posttranscriptional level. Some dysregulated miRNAs have been shown to play important roles in epileptogenesis. The aim of this study was to determine if miR199a-5p regulates seizures and seizure damage by targeting the antiapoptotic protein silent information regulator 1 (SIRT1). Methods: Hippocampal expression levels of miR-199a-5p, SIRT1, and acetylated p53 were quantified by quantitative real-time polymerase chain reaction (RT-PCR) and Western blotting in the acute, latent, and chronic stages of epilepsy in a rat lithiumpilocarpine epilepsy model. Silencing of miR-199a-5p expression in vivo was achieved by intracerebroventricular injection of antagomirs. The effects of targeting miR-199a-5p and SIRT1 protein on seizure and epileptic damage post-status epilepticus were assessed by electroencephalography (EEG) and immunohistochemistry, respectively. Results: miR-199a-5p expression was up-regulated, SIRT1 levels were decreased, and neuron loss and apoptosis were induced in epilepsy model rats compared with normal controls, as determined by up-regulation of acetylated p53 and cleaved caspase-3 expression. In vivo knockdown of miR-199a-5p by an antagomir alleviated the seizurelike EEG findings and protected against neuron damage, in accordance with up-regulation of SIRT1 and subsequent deacetylation of p53. Furthermore, the seizure-suppressing effect of the antagomir was partly SIRT1 dependent. Significance: The results of this study suggest that silencing of miR-199a-5p exerts a seizure-suppressing effect in rats, and that SIRT1 is a direct target of miR-199a-5p in the hippocampus. The effect of miR-199a-5p on seizures and seizure damage is mediated via down-regulation of SIRT1. The miR-199a-5p/SIRT1 pathway may thus represent a potential target for the prevention and treatment of epilepsy and epileptic damage.

Early biomarker-based diagnosis of focal cortical dysplasia (FCD) represents a major clinical challenge. The aim of this study was to identify novel brain microRNAs (miRNAs) in patients with refractory epilepsy and FCD as potential biomarkers. We evaluated serum hsa-miR-4521 as a promising novel biomarker in patients with FCD. Tissue for microarray was obtained from nine patients with temporal lobe refractory epilepsy who underwent surgery to remove epileptic foci identified by cortical video electroencephalogram monitoring. Control tissue was collected from eight patients with hypertension who required emergency surgery to remove an intracranial hematoma. The Affymetrix® GeneChip® Command Console® Software (Affymetrix miRNA 4.0) was used to compare miRNA expression in the cerebral cortex of experimental and control patients. Temporal cortex tissue and serum samples were taken from the same patients for verification of hsa-miR-4521 expression by real-time quantitative polymerase chain reaction (RT-qPCR). The experimental and control patients did not differ significantly in terms of age and gender. 19.4 % (148/764) of the total miRNAs were differentially expressed in experimental and control tissue, which is in agreement with the existing literature. We selected miRNA-4521 for further analysis; the fold-change in expression was 14.4707 and the q value was almost 0, which confirmed up-regulation. Significant up-regulation of hsa-miR-4521 was further validated by RT-qPCR. miRNA microarrays can efficiently and conveniently identify differentially expressed miRNAs in epilepsy brain tissue. This is the first study to identify differential expression of hsa-miR-4521 in brain tissue and serum of refractory epilepsy patients and suggests that serum hsa-miR-4521 may represent a potential diagnostic biomarker for FCD with refractory epilepsy.

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