In-depth characterization of the pituitary transcriptome in Simmental and Chinese native cattle.

The pituitary gland is a key endocrine organ responsible for growth and development. To get closer to understanding important molecular mechanisms at work in the bovine pituitary and identifying the core genes controlling growth, in the present study we have analyzed the transcriptome profiling of the pituitary glands of two cattle breeds (Wenshan and Simmental cattle) with extreme growth differences using high-throughput RNA sequencing. Our study revealed that the overall gene expression levels are quite similar between the two breeds. A total of 18,065 annotated genes were identified, which accounted for 85% of the annotated genes in cattle. The five most abundant hormone genes (GH, PRL, POMC, CGA, and LHB) were relatively stable in both breeds, indicating their pivotal roles in maintaining the basic functions of the pituitary. In addition, 105 genes were identified as differentially expressed between Wenshan and Simmental pituitary glands, including 83 known and 22 novel genes. Functional association analyses of the differentially expressed genes between the breeds revealed 60 enriched gene ontology terms and 3 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Interestingly, the most enriched KEGG pathway, cell adhesion molecules, can modulate pituitary hormone secretion by cell-cell contact. Our findings demonstrated that SYTL2, SLC38A4, and NCAM2 are new candidates for crucial functions in the secretory pathways of the pituitary gland. These results will further understanding of the important molecular mechanisms at work in the bovine pituitary.