High-throughput sequencing revealed the expression profile and potential key molecules of the circular RNAs involved in the process of hypoxic adaptation in Tibetan chickens

The Tibetan chicken ( Gallus gallus ) provides high quality protein and iron for humans, which shows many phenotypic adaptations to the low oxygen. Study of the genetic mechanisms of circular RNAs (circRNAs) in hypoxia adaptation has not been reported. Four embryonic heart tissue samples from Tibetan chickens and Daheng broilers were collected. Differentially expressed circRNAs (DEcircRNAs) were identified via high-throughput sequencing. Bioinformatic analysis was used to indicate the functions and pathways of the DEcircRNAs. A total of 29 DEcircRNAs were identified between 4 Tibetan chickens and 4 Daheng broilers, including 15 upregulated and 14 downregulated DEcircRNAs in Tibetan chickens. GO analysis revealed that the DEcircRNAs were mainly involved in lung development or oxygen metabolism, such as ubiqunegative regulation of mesenchymal cell proliferation involved in lung development, oxidoreductase activity, and peroxisome. Pathway analysis showed that DEcircRNAs were mainly enriched in oxidative phosphorylation, tight junction, VEGF/MAPK/PPAR/Ras/PI3K-Akt signaling pathway. We also constructed a circRNA-miRNA-mRNA-pathway network to visualize the regulatory relationship associated with hypoxia adaptation of the tight junction pathways. The circRNA expression profile was obtained to complement the current Tibetan chicken circRNA database and provides new information for future studies into biological adaptation to hypoxic stress in the Tibetan chicken.