Continuous expression and functional prediction of circular RNA in mouse lung development

OBJECTIVE To study the continuous expression and potential function of circular RNA (circRNA), circ4:150439343|150477468 and circ15:73330849|73343359, in mouse lung development. METHODS According to the stage of lung development, lung tissue samples were collected from mice on embryonic day 16.5 (E16.5), embryonic day 18.5 (E18.5), and postnatal day 2 (P2). Hematoxylin and eosin staining was performed to observe the morphology of lung tissue. Quantitative real-time PCR (qRT-PCR) was used to measure the mRNA expression of circ4:150439343|150477468 and circ15:73330849|73343359 during late lung development; miRanda and TargetScan were used to predict the target miRNAs of circRNAs, and then GO and KEGG analysis was performed for the target genes to predict the potential function of circRNAs. RESULTS Type II alveolar epithelial cells were observed in the lung slices of E16.5 mice, with a gradual increase in number. On P2, the pulmonary alveoli expanded rapidly, the pulmonary interstitium became thinner, and the alveolar structure gradually became mature. The results of qRT-PCR showed that the relative expression of circ4:150439343|150477468 was continuously upregulated over time and the relative expression of circ15:73330849|73343359 was first downregulated and then upregulated (P<0.05). The KEGG and GO analysis showed that circRNAs were involved in the Notch, PI3K-Akt, and NF-κB signaling pathways. CONCLUSIONS Circ4:150439343|150477468 and circ15:73330849|73343359 can participate in lung development through the Notch signaling pathway.