The Novel microRNA Rno-miR-686-3p Is Associated with the Ischaemic Penumbra

Abstract

<b><i>Introduction:</i></b> We explored microRNA (miRNA) profiles correlated with the penumbra in three different phases of ischaemic stroke, using a permanent middle cerebral artery occlusion (p-MCAO) rat model. <b><i>Materials and Methods:</i></b> A 2-mm coronal section was cut from the optic chiasma in the caudal direction, and the penumbra was located in the area between a longitudinal line approximately 2 mm from the midline and a transverse diagonal line at the “2-o’clock” position. Total RNA was extracted from tissue specimens and peripheral blood samples, followed by deep sequencing analysis. <b><i>Results:</i></b> We identified nine novel miRNA candidates in tissues and evaluated their expression levels using real-time quantitative polymerase chain reaction. In situ hybridization was conducted to assess miRNA localization in the brain. Of these nine candidates, we identified and characterized a novel miRNA, rno-miR-686-3p, which was localized in cell nuclei of the cortex, and associated with the penumbra. rno-miR-686-3p was downregulated at 1 (<i>p =</i> 0.042), 3 (<i>p =</i> 0.032), and 4 h (<i>p =</i> 0.007) post-p-MCAO in the penumbra. A total of 297 potential target genes were predicted. Moreover, functional annotation clustering and pathway enrichment analysis predicted that rno-miR-686-3p participates in transcriptional regulation and the Wnt and cyclic adenosine monophosphate (cAMP) signalling pathways. <b><i>Conclusion:</i></b> rno-miR-686-3p is a novel miRNA associated with the ischaemic penumbra that is implicated in transcriptional regulation and modulation of the Wnt and cAMP signalling pathways. Furthermore, it may serve as a possible new biomarker with potential value for detecting the existence of the penumbra.