Characteristic analysis of N-methyladenine in different parts of yak epididymis.

Background: The epididymis is essential for sperm maturation. During sperm maturation, markable alterations of the payload of small noncoding RNAs are observed in the epididymis, which indicated the role of epigenetic alterations in sperm maturation. However, the N-Methyladenosine (mA) modification profile of the epididymis remains unelucidated. Therefore, in this study, we assessed the mA modification levels in the caput, corpus, and cauda of the yak epididymis using a combination of methylated RNA immunoprecipitation and RNA sequencing.

Results: The mA levels were significantly increased in the corpus of the epididymis. Functional enrichment analysis of differentially methylated RNA (DMR) between the corpus and caput group revealed the significant enrichment of DMRs in the gap junction, ErbB signaling pathway, and mTOR signaling pathway, which participate in cell communication and sperm maturation. In addition, the DMRs of cauda-vs-corpus group were enriched in apoptosis, the FoxO signaling pathway, the PI3K-Akt signaling pathway, and the tumor necrosis factor signaling pathway that were associated with sperm autophagy, oxidative stress, and sperm maturation. Furthermore, we identified the key genes exhibiting significant changes in mA levels but with no differences in RNA levels, including YY1-associated factor 2, forkhead box J2, and forkhead box O1. This finding indicated that mA modifications affect these genes during translation, thereby participating in sperm maturation.

Conclusions: In summary, we generated the mA profile of the yak epididymis, which will aid in further elucidating the maturation process of sperm and reveal more information related to male infertility.