Identification of microRNAs with Dysregulated Expression in Status Epilepticus Induced Epileptogenesis

Abstract

The involvement of miRNA in mesial temporal lobe epilepsy (MTLE) pathogenesis has increasingly become a focus of epigenetic studies. Despite advances, the number of known miRNAs with a consistent expression response during epileptogenesis is still small. Addressing this situation requires additional miRNA profiling studies coupled to detailed individual expression analyses. Here, we perform a miRNA microarray analysis of the hippocampus of Wistar rats 24 hours after intra-hippocampal pilocarpine-induced Status Epilepticus (H-PILO SE). We identified 73 miRNAs that undergo significant changes, of which 36 were up-regulated and 37 were down-regulated. To validate, we selected 5 of these (10a-5p, 128a-3p, 196b-5p, 352 and 324-3p) for RT-qPCR analysis. Our results confirmed that miR-352 and 196b-5p levels were significantly higher and miR-128a-3p levels were significantly lower in the hippocampus of H-PILO SE rats. We also evaluated whether the 3 miRNAs show a dysregulated hippocampal expression at three time periods (0h, 24h and chronic phase) after systemic pilocarpine-induced status epilepticus (S-PILO SE). We demonstrate that miR-128a-3p transcripts are significantly reduced at all time points compared to the naïve group. Moreover, miR-196b-5p was significantly higher only at 24h post-SE, while miR-352 transcripts were significantly up-regulated after 24h and in chronic phase (epileptic) rats. Finally, when we compared hippocampi of epileptic and non-epileptic humans, we observed that transcript levels of miRNAs show similar trends to the animal models. In summary, we successfully identified two novel dysregulated miRNAs (196b-5p and 352) and confirmed miR-128a-3p downregulation in SE-induced epileptogenesis. Further functional assays are required to understand the role of these miRNAs in MTLE pathogenesis.

Using Postmortem hippocampi tissue can interfere with differential gene expression analysis of the epileptogenic process

“…Brain tissue collected after death is typically used for comparison in case-control gene expression studies. Indeed, most studies are based on differences in gene expression between biopsies from MTLE patients and autopsy samples from non-epileptic individuals [ 21 , 22 ]. However, human postmortem tissue shows a high degree of biological variance [ 23 , 24 ] which may influence the results obtained by quantitative gene expression analysis.…”

Translational Genomics in Neurocritical Care: a Review

“…Specifically, upregulation of genes regulating synaptic physiology and transcription, homeostasis and metabolism and, cell excitability and morphogenesis occur at immediate, early, and delayed timepoints. In addition, related studies have demonstrated changes in expression of microRNAs related to epileptogenesis, including miRNA-124 and mi-RNA-128 following SE (80,81). Selective RNA editing post-transcription is yet another potential source of proteomic diversity in preclinical models of SE, and merits further investigation as a modulator of protein levels that may be less closely tethered to gene expression (82).…”

Pathophysiology and Clinical Utility of Non-coding RNAs in Epilepsy

“…Araujo et al ( 2016 ) performed a miRNA microarray of the hippocampi of Wistar rats 24 h after intra-hippocampal pilocarpine-induced SE. A total of 73 miRNAs were found to be significantly dysregulated, of which 36 were up-regulated and 37 were down-regulated.…”