Rafikul Islam, Manamu Takenouchi, Amir Salama, Takeshi Hayashi, Yoshinori Katakura, Kei Miyamoto, Nobuhiko Yamauchi
The present study aimed to identify and characterize bovine endometrial miRNAs at different stages of the estrous cycle. Total RNA was extracted from endometrial tissue and subjected to small RNA sequencing. A total of 334 miRNAs were expressed in bovine endometrial tissue during the estrous cycle. Among them, 11 were differentially expressed miRNAs (DEMs) at the follicular stage (F-DEMs) and four at the luteal stage (L-DEMs) in comparison between F and L stages. Bioinformatic analysis of the target genes of these DEMs revealed that miR-2411-3p and miR-320a were the top-ranked hub miRNAs in F- and L-DEMs, respectively. These two miRNAs demonstrated the highest functional coverage in GO annotation. The analysis using cultured bovine endometrial cells showed that the expression level of miR-2411-3p was significantly high in the E2-treated group compared to the control (p < 0.05), whereas the expression level of miR-320a was significantly high in the P4-treated group (p < 0.05). The present study identified the endometrial DEMs during the estrous cycle and predicted their functions based on their target genes. The results demonstrated that miR-2411-3p and miR-320a were identified as characteristic endometrial miRNAs regulated by ovarian steroid hormones in bovine.