Inhibition of miR-140-5p attenuates OGD/R-induced neuronal injury by targeting IL1RAPL1

Abstract

Cerebral ischemia–reperfusion (I/R) injury is a major contributor to neuronal damage and long-term neurological dysfunction after stroke. Our previous studies demonstrated that miR-140-5p expression is markedly upregulated following cerebral ischemia and that in vivo overexpression of miR-140-5p exacerbates cognitive impairment, suppresses neurogenesis, and promotes neuronal death in ischemic mouse models; however, its molecular mechanisms remain unclear. This study aimed to investigate the downstream molecular targets of miR-140-5p and to elucidate the mechanisms by which miR-140-5p regulates neuronal injury after I/R. We established an oxygen–glucose deprivation/reoxygenation (OGD/R) model in primary cortical neurons and assessed viability via Cell Counting Kit-8 (CCK-8). miR-140-5p expression after OGD/R was examined, and loss-of-function experiments evaluated the effects of miR-140-5p inhibition. Synaptic integrity was assessed by immunofluorescence, and inflammatory cytokines by enzyme-linked immunosorbent assay (ELISA). Proteomic analysis identified potential downstream targets, which were validated via Western blotting and dual-luciferase reporter assays. We found that miR-140-5p expression was significantly upregulated in mouse cortical neurons after OGD/R. Functional inhibition of miR-140-5p markedly enhanced neuronal survival, promoted synaptic remodeling, and attenuated inflammatory responses following OGD/R injury. Mechanistically, miR-140-5p was shown to directly target Il1rapl1 and modulate downstream c-Jun N-terminal kinase (JNK) signaling, thereby regulating neuronal viability, inflammation, and synaptic plasticity under ischemia–reperfusion conditions. This study reveals a novel miR-140-5p–mediated regulatory mechanism in neuronal injury following cerebral ischemia–reperfusion and suggests a potential therapeutic target for ischemic brain injury.