Integrated mRNA and miRNA transcriptome analysis provides novel insights into the molecular mechanisms underlying goose pituitary development during the embryo-to-hatchling transition

It is well established that the endocrine system plays a pivotal role in preparing the avian embryos for the abrupt switch from chorioallantoic to pulmonary respiration during the critical embryo-tohatchling transition. However, as the master gland of the endocrine system, there has been little research focusing on the molecular mechanisms controlling the development and function of the pituitary gland during the peri-hatch period in birds. In the present study, we aimed to determine the genome-wide mRNA and miRNA transcriptome profiles of the pituitary during the embryo-to-hatchling transition period from embryonic day 22 (E22) to post-hatching day 6 (P6) in the goose (Anser cygnoides). Of note, expression of Anser_cygnoides_newGene_32456 and LOC106031011 were significantly different among these 4 stages (i.e., E22, E26, P2, and P6). Meanwhile, the neuroactive ligandreceptor interaction pathway was significantly enriched by the DEGs commonly identified among three pairwise comparisons. At the miRNA transcriptome level, there were not commonly identified DE miRNAs among these 4 stages, while the 418 of their predicted target genes were mutually shared. Both the target genes of DE miRNAs in each comparison and these 418 shared target genes were significantly enriched in the ECM-receptor interaction and focal adhesion pathways. In the predicted miRNA-mRNA interaction networks of these 2 pathways, novel_miRNA_467, novel_miRNA_154, and novel_miRNA_340 were the hub miRNAs. In addition, multiple DE miRNAs also showed predicted target relationships with the DEGs associated with extracellular matrix (ECM) components. Among them, expression of novel_miR_120, tgu-miR-92-3p, and novel_miR_398 was significantly negatively correlated with that of LAMC3 (laminin subunit gamma3), suggesting that these miRNAs may regulate pituitary tissue remodeling and functional changes through targeting LAMC3 during development. These identified DE mRNAs and miRNAs as well as their predicted interaction networks involved in regulation of tissue remodeling and cellular functions were most likely to play critical roles in facilitating the embryoto-hatchling transition. These results provide novel insights into the early developmental process of avian pituitary gland and will help better understand the underlying molecular mechanisms.