CircUBR1 knockdown relieves ventilator-induced lung injury through regulating miR-20a-5p/GGPPS1 pathway

Objective: To assess the influences and underlying mechanism of circular RNA UBR1 (circUBR1) in ventilator induced lung injury (VILI).Methods: In mice and mouse alveolar epithelial cells, VILI model was established. CircUBR1 and miR-20a-5p expression was assessed via quantitative real time polymerase chain reaction. Western blot and immunohistochemistry were applied to assess geranylgeranyl diphosphate synthase 1 (GGPPS1) protein expression. In lung tissues, the histopathological changes were utilized using hematoxylin and eosin staining. Cell counting kit-8 assay and flow cytometer were applied to detect cell proliferation and apoptosis. The levels of inflammatory cytokines [interleukin (IL)-1 beta, IL-18, IL-6, and tumor necrosis factor (TNF)-alpha] were measured by western blot and enzyme-linked immunosorbent assay.Results: In lung tissues of VILI mice, circUBR1 and GGPPS1 expression were upregulated, while miR-20a-5p expression was downregulated. In vivo, circUBR1 knockdown alleviated lung injury, inhibited cell apoptosis, and decreased the levels of inflammatory cytokines. In cells treated with cyclic stretch (CS), circUBR1 knockdown promoted cell viability, inhibited cell apoptosis, and reduced inflammatory cytokines. CircUBR1 could sponge miR-20a-5p, and GGPPS1 was the target gene of miR-20a-5p. In addition, in cells treated with CS, downregulation of miR-20a-5p or the overexpression of GGPPS1 reversed the promotive effect of circUBR1 knockdown on cell viability and the inhibitive effect of circUBR1 knockdown on cell apoptosis and inflammation production.Conclusions: In VILI, knockdown of circUBR1 attenuated lung injury and inflammation via regulating the miR20a-5p/GGPPS1 pathway. Our study may provide a potential therapeutic target for treatment of VILI.