Dynamic expression pattern and regulatory network of circRNAs during chicken ovarian development.

Circular RNAs (circRNAs) exert crucial functions in mammalian reproduction; however, their regulation underlying chicken reproduction remains unclear. Here, time-course transcriptome profiles of circRNAs were constructed in chicken ovarian tissues across the entire egg-laying cycle (15 W, 20 W, 30 W, 70 W, 90 W). A total of 6551 circRNAs were identified, and most were derived from exon-exon backsplicing with 400-600 nt. Of these, 1556 circRNAs harbour translation potential in both IRES- and m6A modification-dependent manners. The 1894 differentially expressed circRNAs (DE-circRNAs) exhibited stage-specific expression patterns, and were clustered into 6 significantly co-expressed subclusters and enriched in multiple signaling pathways involving follicular development. Weighted gene co-expression network analysis detected 1016 hub circRNAs, of which 136 circRNAs were co-expressed DE-circRNAs and considered as key candidates regulating chicken ovarian development. These key circRNAs may post-transcriptionally regulate folliculogenesis-related gene via competitive endogenous RNA mechanism. This study reveals potential regulatory roles of circRNAs in chicken ovarian development and egg-laying performance.