microRNA transcriptome analysis of granulosa cells predicts that the Notch and insulin pathways affect follicular development in chickens

MicroRNAs (miRNAs) have been documented to play critical roles in chicken reproduction. Granulosa cell (GC) development of the follicle is closely related to hierarchical follicle ordering, making it an important factor in determining laying performance. Thus, it is meaningful to mine follicular development-related miRNAs. To identify regulatory miRNAs and the biological mechanisms by which they control follicular development, we conducted small RNA sequencing of GCs isolated from prehierarchical follicles named small yellow follicle (SYFG), the smallest hierarchical follicle (F6G), and the largest hierarchical follicle (F1G). A total of 99, 196, and 110 differentially expressed miRNAs (DEMs) were identified in SYFG.vs.F6G, SYFG.vs.F1G, and F6G.vs.F1G, respectively. Of these, 22 miRNAs, including miR-223, miR-103a, miR-449c-3p, and miR-203a, were ubiqui-tously identified as DEMs in three stages. Target gene prediction suggested that these miRNAs are associated with the MAPK, TGF-beta, and Wnt signaling pathways, which are all associated with follicular development. The Notch and insulin signaling pathways were commonly enriched in all three comparisons. RT-qPCR analysis further indicated that the expression levels of PSEN2, which encodes an essential factor regulating Notch and insulin signaling, was significantly changed in SYFG, F6G, and F1G. The current study provides basic data and offers a new foundation for further exploration of the roles of miRNAs in follicular development in chickens.

Automated summary

The study identified miRNAs associated with follicular development in chickens through small RNA sequencing of granulosa cells, and analyzed their target genes and their relationships with signaling pathways, providing basic data and a new theoretical foundation for further research on the role of miRNAs in follicular development in chickens.