Comparative transcriptome analysis reveals involvement of FOXL2 in regulation of ovulation cycle in chicken

The egg-laying performance is closely related to ovulation of chicken. Ovulation is very complex and highly coordinated physiological process. However, little is known about the ovulation-related synergistic actions of molecules and their signaling. Here, we performed a comparative transcriptome analysis based on preovulatory, ovulatory, and post-ovulatory follicle data of thirty-week-old Lohmann Pink laying hens. Gene set enrichment analysis (GSEA) indicated that the ovulating follicles exhibited the significant changes in plasma membrane structure and cell morphology, and the immune response mediators and T-cells were activated in response to ovulation, and meanwhile multiple biological processes (such as oxidative phosphorylation and steroidogenesis) and biological functions of ribosomes and lysosomes were inhibited. The analyses of our ovulation RNA-seq data and previously reported forkhead box L2 (FOXL2) ChIP-seq and FOXL2 RNA-seq data revealed that FOXL2 gene might directly regulate extracellular matrix (ECM) structure-related genes, thus modulating the expression levels of genes related to DNA replication and cell cycle, ultimately affecting ovulation. FOXL2 was involved in the regulation of DNA replication and cell cycle at 22 h before ovulation, oocyte meiosis and actin cytoskeleton regulation at 3 h before ovulation, and ECM structure change and cell senescence after ovulation. Overall, this study reveals regulatory mechanism of FOXL2 on chicken ovulation at transcriptomic level. Our findings lay a foundation for further identifying key nodes regulating ovulation.