Abstract TP117: MiR-15a/16-1 Cluster Inhibits Angiogenesis In Mouse After Ischemic Stroke

Angiogenesis may occur as a natural defense response against neurological diseases. Accumulating studies have shown that post-ischemic angiogenesis promotes functional recovery after ischemic stroke and is related to longer survival time in ischemic stroke patients. MicroRNAs (miRs) have been documented as a novel family of noncoding small RNAs that negatively modulate protein expression in various organisms. Recent studies have revealed important roles for miRs in regulating angiogenesis. However, the function of miRs in the angiogenic processes after ischemic stroke is unknown. We have previously demonstrated that the miR-15a/16-1 cluster has an anti-survival role in ischemia-induced endothelial cell death. Here we further investigate the role of the miR-15a/16-1 cluster in the regulation of post-ischemic angiogenesis. We have shown that expression of the miR-15a/16-1 cluster is significantly increased in the cerebral vasculature at the penumbral area 7 days after mouse middle cerebral artery occlusion (MCAO). Accordingly, in comparison with the wild-type animals, endothelial cell (EC)-selective miR-15a/16-1 transgenic overexpression leads to reduced cerebral blood vessel formation, increased brain infarction and neurological deficits in mice 7 days post-MCAO. Mechanistically, lentivirus-mediated miR-15a/16-1 gain- or loss-of-function reduces or increases FGFR1 and VEGF mRNA or protein levels in mouse cerebral vascular endothelial cell cultures, respectively. Through the bioinformatics analysis, 3’UTR luciferase reporter assays, and immunoassays, we further found that miR-15a and miR-16-1 bind to the 3’UTR of FGFR1 or VEGF mRNA, and directly inhibit FGFR1 and VEGF activities. Our findings suggest the miR-15a/16-1 cluster can suppress post-ischemic cerebral angiogenesis through direct inhibition of endothelial FGFR1 and VEGF activities. Elucidating the molecular mechanism of miR-15a/16-1 cluster-mediated angiogenesis will provide new insights into the understanding of miR function in the post-ischemic neurovascular remodeling and neurological recovery and open a new area with potential promise for further development of neurorestorative therapies after ischemic stroke.