Genome-wide differential expression of genes and small RNAs in testis of two different porcine breeds and at two different ages

Lu Chuan (LC, a Chinese local pig breed) and Yorkshire boars were generally considered as being pretty different in the time point and process of sexual maturation. Some documented evidences proved small RNAs (sRNA) and targeted genes are involved in mammalian testicular development and spermatogenesis. However, the detailed molecular regulation mechanisms of them remain largely unknown so far. We used the deep sequencing technology to characterize and identify the similarities and diversities of the expression and regulation of mRNAs, miRNAs and piRNAs which are possibly related to spermatogenesis and testicular development in different pig breeds at different stages of sexual maturity. In this study, we obtained a total of 10,716 mRNAs, 67 miRNAs and 16,953 piRNAs which were differentially expressed between LC and LW pig breeds or between the two sexual maturity stages. Of which, we identified 16 miRNAs and 28 targeted genes possibly related to spermatogenesis; 14 miRNAs and 18 targeted genes probably associated with cell adhesion related testis development. We also annotated 579 piRNAs which could potentially regulate cell death, nucleosome organization and other basic biology process, which implied that those piRNAs might be involved in sexual maturation difference. The integrated network analysis results suggested that some differentially expressed genes were involved in spermatogenesis through the ECM–receptor interaction, focal adhesion, Wnt and PI3K–Akt signaling pathways, some particular miRNAs have the negative regulation roles and some special piRNAs have the positive and negative regulation roles in testicular development. Our data provide novel insights into the molecular expression and regulation similarities and diversities of spermatogenesis and testicular development in different pig breeds at different stages of sexual maturity.