miR-486-5p inhibits eNOS and angiogenesis in cultured endothelial cells by targeting MAML3

Kidney ischemia-reperfusion injury (IR) is associated with endothelial injury. Administration of miR-486-5p protects against rat kidney IR injury, with localization to capillary endothelial cells, although it inhibits IR-induced endothelial nitric oxide synthase (eNOS) protein expression. We studied the effects of miR-486-5p on eNOS and endothelial cell function and determined its mRNA targets. Methods: Human umbilical vein endothelial cells (HUVECs) were transfected with miR-486-5p and assayed for proliferation, migrartion, and network formation. Biotinylated miR-486-5p was transfected for pull-down of bound mRNA, followed by RNA sequencing. Results: miR-486-5p markedly decreased eNOS mRNA and protein in HUVECs, although eNOS mRNA was not found to be a direct target of miR-486-5p. miR-486-5p inhibited angiogenesis, which was rescued with eNOS plasmid transfection. RNA sequencing of biotinylated miR-486-5p pull-down RNA revealed highly significant enrichmenet in predicted targets FOXO1, FOXP1, TNFSF4, MAML3, and CELSR3, and in the non-predicted target SPCS2. RT-qPCR validated these transcripts as inhibited miR-486-5p. While silencing of FOXO1 had no impact on eNOS protein, MAML3 silencing inhibited eNOS levels. Conclusion: miR-486-5p inhibits angiogenesis in endothelial cells via down-regulation of eNOS, which involves selective targeting of MAML3. These data support a novel pathway regulating endothelial cell function. Overall design: To identify direct miR-486-5p targets in endothelial cells, HUVECs were transfected with either biotinylated miR-486-5p or biotinylated cel-miR-67 (negative control), followed by cell lysis after 24 hr and pull-down of bound RNA with streptavidin beads. The bound RNA was purified and analyzed by RNA-seq to screen for mRNA bound to biotinylated miR-486-5p (compared to the biotinylated cel-miR negative control).