Screening and identification of growth-related differentially expressed microRNAs in the pituitary gland of piglets

<p indent="0mm">In order to compare and analyze the reasons for the differences of growth rate between piglets, in this study, twelve 40-day-old (Duroc × (Large White × Landrace)) piglets with great health status and consistent genetic background were selected as experimental materials. Based on the differences in body weight, they were divided into two groups: group A was the low growth rate group, and Group B was the normal growth rate group. Serum, liver and muscle samples of piglets were collected to measure the levels of growth hormone and insulin-like growth factor-1 (IGF-1). The pituitary tissue samples of piglets were collected, and the differentially expressed miRNAs were obtained by miRNA sequencing in the pituitary tissue of the two groups. Target genes of miRNAs were predicted to perform Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis. The results showed that (i) compared with group A, the level of growth hormone in serum, liver and muscle of group B were significantly increased (<italic>P</italic>​&lt;0.05); the levels of IGF-1 in serum and liver of group B were higher (<italic>P</italic>​&lt;0.05); (ii) a total of 103 miRNAs were significantly differentially expressed between the two groups; compared with group B, 60 miRNAs were up-regulated and 43 miRNAs were down-regulated in group A (<italic>Q</italic>-value&lt;0.05); a total of 40 miRNAs were significantly different between the two groups, of which 22 miRNAs were up-regulated and 18 miRNAs were down-regulated (<italic>Q</italic>-value&lt;0.01); (iii) the target genes mainly enriched in pathways such as the protein phosphorylation, protein kinase activity and protein kinase combined with biological control process; (iv) through KEGG pathway analysis, the target genes mainly enriched in the PI3/AKT pathway and the synthesis, secretion and action of growth hormone pathways; (v) in this study, ssc-miR-21-3p, ssc-miR-19a, ssc-miR-15b, ssc-miR-185, ssc-miR-885-3p, ssc-mir-125a-p3, ssc-mir-185-p3, ssc-mir-204-p3, ssc-mir-2483-p5 and their paired target genes <italic>HGF</italic>, <italic>SOCS2</italic>, <italic>JAK2</italic>, <italic>GHR</italic>, <italic>IGFBP3</italic>, <italic>AKT3</italic>, <italic>IGF1R</italic>, <italic>SSTR3</italic>, <italic>SST</italic>, <italic>STAT3</italic>, <italic>JAK2</italic>, <italic>POU1F1</italic> and <italic>GPR101</italic> may be the key target spots affecting the growth and development of piglets, which can be used as priorities for future research of functional regulation in piglet growth and development.