ABSTRACT: Studying spermatogenesis is the key to understanding the development mechanism of the yak reproductive system. Although N6-methyladenosine (m6A) RNA modification has been reported to regulate spermatogenesis and reproductive function in mammals, the molecular mechanism of m6A in yak testis development and spermatogenesis remains largely unknown. Therefore, we collected testicular tissue from junile and adult yaks, and found that the m6A level significantly increased after sexual maturity in yak. In MeRIP-seq, 1,702 hypermethylated peaks and 724 hypomethylated peaks were identified. The hypermethylated differentially methylated RNAs (DMRs) (CIB2, AK1, FOXJ2, PKDREJ, SLC9A3, and TOPAZ1) mainly regulated spermatogenesis, while the hypomethylated DMRs (BCL6, USP25, CD96, EPHA2, and TAF12) mainly participated in immune response. Functional enrichment analysis showed that DMRs were significantly enriched in the adherens junction, gap junction, and Wnt, PI3K, and mTOR signaling pathways, regulating cell development, spermatogenesis, and testicular endocrine function. The functional analysis of differentially expressed genes showed that they were involved in the biological processes of mitosis, meiosis, and flagellated sperm motility during sexual maturity of yak testis. We also screened the key regulatory factors of testis development and spermatogenesis by combined analysis, which included BRCA1, CREBBP, STAT3, and SMAD4. This study has important research value and practical guiding significance for yak genetic improvement, particularly in understanding the molecular mechanism and evolutionary dynamics of the progression of testis developmental stages in yaks.
