Differential expression of circRNAs during rat lung development.

At present, thousands of circular RNAs (circRNAs) have been found in cancer and various tissues from different species. However, the expression of circRNAs during rat lung development remains largely unknown. In the present study, circRNA expression profiles were screened in three mixed rat lung tissues at 3 time‑points [embryonic day (E) 19, E21 and post‑natal (P) day 3] during fetal rat development with circRNA high‑throughput sequencing. Preliminary results were verified by reverse transcription‑PCR (RT‑PCR) at 4 time‑points (E16, E19, E21 and P3). A total of 375 circRNAs were differently expressed in E19 vs. E21 (fold change ≥1.5; P<0.05). At the same time, a total of 358 circRNAs were differently expressed in E21 vs. P3 (fold change ≥1.5; P<0.05). A total of 3 circRNAs (rno_circ:chr7:24777879‑24784993, rno_circ:chr14:14620910‑14624933 and rno_circ:chr3:1988750‑​1998592) were characterized by having consistent fold changes (≥1.5) between 3 time‑points (E19, E21 and P3) and were selected for RT‑PCR at 4 time‑points (E16, E19, E21 and P3). Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of parent genes of the differentially expressed circRNAs revealed that these circRNAs may serve important roles in lung development. The present results support that these new found circRNAs participate in lung development. Furthermore, these findings may help to clarify the physiopathological mechanism of normal rat lung development, and may further provide a physiopathological basis of lung developmental diseases.