Differentially expressed circRNA and functional pathways in the hippocampus of epileptic mice based on next‐generation sequencing

Abstract

Epilepsy is a clinical syndrome caused by the highly synchronized abnormal discharge of brain neurons. It has the characteristics of paroxysmal, transient, repetitive, and stereotyped. Circular RNAs (circRNAs) are a recently discovered type of noncoding RNA with diverse cellular functions related to their excellent stability; additionally, some circRNAs can bind and regulate microRNAs (miRNAs). The present study was designed to screen the differentially expressed circRNA in an acute seizure model of epilepsy in mice, analyze the related miRNA and mRNA, and study their participating functions and enrichment pathways. In order to obtain the differential expression of circRNA in epilepsy and infer their function, we used next-generation sequencing and found significantly different transcripts. CIRI (circRNA identifier) software was used to predict circRNA from the hippocampus cDNA, EdgeR was applied for the differential circRNA analysis between samples, and Cytoscape 3.7.2 software was used to draw the network diagram. A total of 10,388 differentially expressed circRNAs were identified, of which 34 were upregulated and 66 were downregulated. Among them, mm9_circ_008777 and mm9_circ_004424 were the key upregulated genes, and their expression in the epilepsy group was verified using Quantitative real-time PCR (QPCR). The analysis indicated that the extracted gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways were closely related to several epilepsy-associated processes. This study determined that mm9_circ_008777 and mm9_circ_004424 are potential biomarkers of epilepsy, which play important roles in epilepsy-related pathways. These results could help improve the understanding of the biological mechanisms of circRNAs and epilepsy treatments.

CircRNA‐associated ceRNA regulatory networks as emerging mechanisms governing the development and biophysiopathology of epilepsy

“…In this way, they found that mm9_circ_008777 and mm9_circ_004424 may carry out GO functions via biological regulation, metabolic processes, catalytic activity, and cellular processes, and may contribute to epilepsy through signaling pathways such as VEGF, GnRH, chemokine, and ErbB. The identification of MM9_circ_004424 and MM9_circ_008777 as potential biomarkers for epilepsy diagnosis suggests that clinical interventions targeting these circRNAs could be beneficial in the management of epilepsy 52 …”

“…A prior investigation identified circUBQLN1 as being downregulated in epilepsy samples and located at chr9: 86274695-86284242. 20,52 The discovery of Y-box 7 (SOX7), a sex-determining region in epilepsy's hippocampal neurons, revealed its ability to suppress cell death. 24 Based on this data, circUBQLN1 lacked the 3′ poly(A) tail, which prevented its binding to oligo (dT) 18 primers during reverse transcription.…”

“…Overexpression of circUBQLN1 mitigated Mg 2+ ‐free‐induced nerve injury, and the protective effects of circUBQLN1 and miR‐155 in human neurons‐hippocampal (HN‐h) cells exposed to Mg 2+ ‐free conditions were reversed upon knockdown of SOX7. A prior investigation identified circUBQLN1 as being downregulated in epilepsy samples and located at chr9: 86274695–86284242 20,52 . The discovery of Y‐box 7 (SOX7), a sex‐determining region in epilepsy's hippocampal neurons, revealed its ability to suppress cell death 24 .…”

RNA therapeutics for epilepsy: An emerging modality for drug discovery

“…Dysregulation of circRNAs in epilepsy patients and animal models of epilepsy is well documented, especially in TLE, and is primarily associated with subsequent miRNA dysregulation. [59][60][61] As with miRNA-targeted RNA drugs, therapeutic modulation of circRNAs is based on either upregulation using synthetic circRNAs or downregulation using either siRNAs or ASOs, 53 but so far only two studies have reported on circRNA interference in epilepsy (Table 1). In the first study, an siRNA against circIgf1r was injected ICV into mice, 2 days prior to SE induced by 4-aminopyridine.…”

Circulating miRNAs as Novel Clinical Biomarkers in Temporal Lobe Epilepsy

“…Therefore, dysregulated miRNA profiles in biofluids may be potentially useful biomarkers in people with drug-resistant TLE [ 11 , 12 ]. Regarding circulating microRNAs (c-miRNAs), altered levels have also been found in epilepsy patients [ 13 , 14 ] and in animal models of epilepsy, especially in TLE [ 15 , 16 ]. Through this literature review, the authors aim to provide a comprehensive synthesis of the current understanding of dysregulated c-miRNAs in TLE, with a focus on their potential capability of providing disease modification and counteracting drug resistance in TLE.…”