Background: Recent studies have revealed that noncoding RNAs play important regulatory roles in the formation of endometrial receptivity. Circular RNAs (circRNAs) are a universally expressed noncoding RNA species that have been recently proposed to act as miRNA sponges that directly regulate expression of target genes or parental genes.
Results: We used Illumina Solexa technology to analyze the expression profiles of circRNAs in the endometrium from three goats at gestational day 5 (pre-receptive endometrium, PE) and three goats at gestational day 15 (receptive endometrium, RE). Overall, 21,813 circRNAs were identified, of which 5,925 circRNAs were specific to the RE and 9,078 were specific to the PE, which suggested high stage-specificity. Further analysis found 334 differentially expressed circRNAs in the RE compared with PE (P < 0.05). The analysis of the circRNA-miRNA interaction network further supported the idea that circRNAs act as miRNA sponges to regulate gene expression. Moreover, some circRNAs were regulated by estrogen (E2)/progesterone (P4) in endometrial epithelium cell lines (EECs) and endometrial stromal cell line (ESCs), and each circRNA molecule exhibited unique regulation characteristics with respect to E2 and P4.
Conclusions: These data provide an endometrium circRNA expression atlas corresponding to the biology of the goat receptive endometrium during embryo implantation.
Keywords: CircRNAs; Dairy goat; Endometrial epithelium cells; Endometrial stromal cells; Receptive endometrium.