ABSTRACT: The testis is an important reproductive organ in male mammals, serving as the site for spermatogenesis, androgen synthesis, and secretion. Non-coding RNAs (ncRNAs) plays an important regulatory role in various biological processes. However, the regulatory role of ncRNAs on yak testicular development and spermatogenesis is still largely unclear. In this study, the expression profiles of circRNA, miRNA, and mRNA in testicular tissues were compared between 6 months (Y6M), 18 months (Y18M), and 4 years old (Y4Y), with a significant difference in testicular development using RNA-seq. A total of 22 differentially expressed circRNAs (DE circRNAs), 69 differentially expressed miRNAs (DE miRNAs), and 64 differentially expressed mRNA (DE mRNAs) were detected in testicular samples of Y6M, Y18M, and Y4Y, respectively. Furthermore, GO and KEGG analysis results showed that the source genes of DE circRNAs, predicted target genes of DE miRNAs, and DE mRNAs concentrated on signaling pathways and GO terms that were related to sperm synthesis, vitality, and testicular development, such as cell cycle, Wnt signaling pathway, MAPK signaling pathway, GnRH signaling pathway, and spermatogenesis process. A circRNA-miRNA-mRNA network analysis revealed that some differentially expressed non-coding RNAs (DE ncRNAs) may be involved in testicular spermatogenesis, including miR-574, miR-449a, CDC42, CYP11A1 and et al. At the same time, there are various circRNA-miRNA interaction pairs. This study provides a deep understanding of the regulatory network of ncRNA regulation in yak testicular development, providing data support for further elucidating the molecular mechanisms of yak testicular development.
