The exploration of miRNAs and mRNAs profiles revealed the molecular mechanisms of cattle-yak male infertility

Background: Cattle-yak, the first-generation offspring of cattle and yak, inherited many excellent characteristics from their parents. However, F1 male hybrid infertility restricts the utilization of heterosis greatly. The coding genes can transcript into such mRNAs and further translate into proteins to maintain the activities of organisms. MiRNAs are endogenous small noncoding RNA that silenced their target mRNA expression by high complementary binding sites. In recent years, mRNA and miRNA profiles produced by high-throughput sequencer had interpreted the molecular mechanisms of numerous biological phenomena. However, based on the cattle-yak male sterility, the comprehensive comparison of testicular tissue RNA profiles of cattle, yak and cattle-yak have not been conducted. Results: Testicular histology indicated that the seminiferous tubules became vacuolated and there are few active germs cells can be seen. With the RNA-seq analysis we finally identified 47 up-regulated miRNAs and 34 down-regulated miRNAs in cattle, 16 up-regulated miRNAs and 21 down-regulated miRNAs in cattle and yaks compared with cattle-yak, respectively. Furthermore, we found that the known miRNA bta-miR-7 was commonly down-regulated in cattle-yak group, revealed the vital role of miR-7 in the regulation of reproductive processes. With the target prediction, the coding genes MYRFL, FANCA, INSL3, USP9X, SHF became the regulated candidates. The network analysis of GO to GO and pathway to pathway annotated such hub terms and genes related to many regulatory functions. We also performed GSE GO and GSE KEGG to display the function of DE gene sets authenticated in our previous study and found that the gene sets most enriched in ATP binding, DNA binding, reproduction process and MAPK signaling pathway, uncovered the relevance between the DE genes and cattle-yak male infertility. Conclusions: We first obtained the compared miRNAs profiles of testicular tissue samples among cattle, yak and cattle-yak and analyzed the fundamental functions of their target genes. As a complement, GSEA of mRNA profiles identified in our previous study was also be conducted. This study preliminarily revealed some miRNAs related to reproductive processes such as bta-miR-7 and such critical regulatory pathways. Our research is of great significance to explore the molecular mechanism of cattle-yak infertility and look for strategies to resolve this difficult problem.