The mmu_circ_0000335 inhibits M1 microglial-induced hippocampal neuronal apoptosis via the miR-19b-3p/SOCS1 axis in a mouse epilepsy model

Abstract

Background : Increasing evidence has demonstrated that circular RNAs (circRNAs) participate in epileptogenesis, but the expression profile and role of circRNAs in epilepsy remain unknown. A circRNA microarray was performed to examine epilepsy-related circRNAs. Bioinformatics analyses, luciferin reporter experiments and real-time quantitative PCR (Rt-qPCR) in vitro experiments were performed to demonstrate the mechanism of circRNA-mediated gene regulation of the microglial phenotype under epileptic conditions. Then, to further confirm the effect of circRNAs on nerve damage in the hippocampus, a mouse model of epilepsy was established by intraperitoneal injection of lithium chloride and pilocarpine. Results: The data indicated that 364 circRNAs were differentially expressed comparing epilepsy and control tissues. In particular, mmu_circ_0000335 expression was significantly downregulated in epileptic mice which was confirmed by Rt-qPCR. Overexpression of mmu_circ_0000335 promoted BV2 cell transformation into the M2 macrophage phenotype by increasing expression of CD206, Arg1, Ym1 and IL-10 while decreasing M1 macrophage markers IL-1β, IL-6, TNF-α and IFN-γ expressions under epileptic conditions. mmu_circ_0000335 expression triggered upregulation of Suppressor of Cytokine Signaling 1 (SOCS1) by decreasing miR-19b-3p levels, as determined by luciferase reporter assay. In vivo studies found that mmu_circ_0000335 overexpression decreased epilepsy-induced neural cell apoptosis in the hippocampus by reducing inflammatory cytokine expression. Immunofluorescence detection showed that mmu_circ_0000335 overexpression promoted microglial transformation into the M2 phenotype which had an anti-inflammatory effect. Conclusions: These results collectively indicated that mmu_circ_0000335 was involved in epilepsy progression by functioning as a miR-19b-3p sponge to enhance SOCS1 expression. Thus, mmu_circ_0000335 may be a candidate therapeutic target for epilepsy patients.

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

“…Mmu_circ_0000335 promoted SOCS1 expression, according to the findings of the present investigation, which under epileptic circumstances changed the balance between microglia and macrophages in favor of M2 polarization. The current study's findings showed that mmu_circ_0000335 promoted SOCS1 expression 58 . Additionally, findings from in vivo studies indicated that the upregulation of mmu_circ_0000335 shifted the equilibrium of macrophages and microglia toward M2 polarization in the context of epilepsy.…”

“…The current study's findings showed that mmu_circ_0000335 promoted SOCS1 expression. 58 Additionally, findings from in vivo studies indicated that the upregulation of mmu_circ_0000335 shifted the equilibrium of macrophages and microglia toward M2 polarization in the context of epilepsy. This resulted in a mitigation of epilepsy-induced neuronal damage in the hippocampus, as well as a reduction in the production of inflammatory factors mediated by microglia.…”