Circular RNA circGSE1 promotes angiogenesis in ageing mice by targeting the miR-323-5p/NRP1 axis

Age is an important factor in many cardiovascular diseases, in which endothelial cells (ECs) play an important role. Circular RNA5 (circRNAs) have been reported in many cardiovascular diseases, but their role in ageing EC-related angiogenesis is unclear. We aimed to identify a functional circRNA that regulates angiogenesis during ageing and explore its specific mechanism. In this study, we searched for differentially expressed circRNAs in old endothelial cells (OEC5) and young endothelial cells (YECs) by circRNA sequencing and found that circGSE1 was significantly downregulated in OEC5. Our study showed that circGSE1 could promote the proliferation, migration and tube formation of OEC5 in vitro. In a mouse model of femoral artery ligation and ischemia, circGSE1 promoted blood flow recovery and angiogenesis in the ischemic limbs of ageing mice. Mechanistically, we found that overexpressing circGSE1 reduced miR-323-5p expression, increased neuropilin-1 (NRP1) expression, and promoted proliferation, migration, and tube formation in OEC5, while knocking down circGSE1 increased miR-323-5p expression, reduced NRP1 expression, and inhibited proliferation, migration, and tube formation in YECs. During EC ageing, circGSE1 may act through the miR-323-5p/NRP1 axis and promote endothelial angiogenesis in mice. Finally, the circGSE1/miR-323-5p/NRP1 axis could serve as a potential and promising therapeutic target for angiogenesis during ageing.