Stage- and Subfield-Associated Hippocampal miRNA Expression Patterns after Pilocarpine-Induced Status Epilepticus

Abstract

Objective: To investigate microRNA (miRNA) expression profiles before and after pilocarpine-induced status epilepticus (SE) in the cornu ammonis (CA) and dentated gyrus (DG) areas of the mouse hippocampus, and to predict the downstream proteins and related pathways based on bioinformatic analysis. Methods: An epileptic mouse model was established using a pilocarpine injection. Brain tissues from the CA and DG were collected separately for miRNA analysis. The miRNAs were extracted using a kit, and the expression profiles were generated using the SurePrint G3 Mouse miRNA microarray and validated. The intersecting genes of TargetScan and miRanda were selected to predict the target genes of each miRNA. For gene ontology (GO) studies, the parent-child-intersection (pci) method was used for enrichment analysis, and Benjamini-Hochberg was used for multiple test correction. The Kyoto Encyclopedia of Genes and Genomes (KEGG) was used to detect disease-related pathways among the large list of miRNA-targeted genes. All analyses mentioned above were performed at the time points of control, days 3, 14, and 60 post-SE. Results: Control versus days 3, 14, and 60 post-SE: in the CA area, a total of 131 miRNAs were differentially expressed; 53, 49, and 26 miRNAs were upregulated and 54, 10, and 22 were downregulated, respectively. In the DG area, a total of 171 miRNAs were differentially expressed; furthermore, 36, 32, and 28 miRNAs were upregulated and 78, 58, and 44 were downregulated, respectively. Of these, 92 changed in both the CA and DG, 39 only in the CA, and 79 only in the DG area. The differentially expressed miRNAs target 11–1630 genes. Most of these proteins have multiple functions in epileptogenesis. There were 15 common pathways related to altered miRNAs: nine different pathways in the CA and seven in the DG area. Conclusions: Stage- and subfield-associated hippocampal miRNA expression patterns are closely related to epileptogenesis, although the detailed mechanisms need to be explored in the future.

Temporal changes in mouse hippocampus transcriptome after pilocarpine-induced seizures

“…MiR-5106, which has been implicated in the healing process ( Xiong et al, 2020 ), was downregulated at both 1 and 8 h. MiR-7654-3p was downregulated at both 8 and 24 h, while miR-431-5 p exhibited upregulation at 24 h followed by downregulation at 120 h ( Xie et al, 2022 ). MiR-34b-5p , which has been linked to inflammation, apoptosis, and Parkinson’s disease in previous studies ( Liu et al, 2016 ; Xie et al, 2018 ; Li et al, 2020 ; Xie et al, 2022 ) showed changes in expression levels at all stages, with upregulation at early stages and downregulation at 120 h ( Figure 5B ), similar to another recent SE study ( Li et al, 2022 ). It will be interesting to investigate specific biological significance of miR-34b-5p in this mouse model of TLE and this could be fruitful future direction for study.…”