The expression changes of circular RNAs between LH + 2 and LH + 7 human endometrium

The expression changes of circular RNAs between LH + 2 and LH + 7 human endometrium: Compatible endometrial receptivity is essential for successful implantation. The underlying molecular mechanisms are continuously explored in assisted reproduction field, focusing on the protein-encoding genes and microRNAs (miRNAs) [1,2]. However, the effects of circular RNAs (circRNAs) on endometrial receptivity, as well as the regulatory mechanisms, are poorly understood. circRNAs are a special class of non-coding endogenous RNAs that have covalently closed continuous loops without a 5′ cap or a 3′ poly A tail [3]. Interestingly, circRNAs are abundant, evolutionally conserved, and relatively stable in the cytoplasm, exhibiting tissue-, cell-, and developmental-stage-specific expression patterns [4]. Growing evidence has confirmed that circRNAs are involved in a variety of biologic processes and play a role in the development of some diseases by acting as miRNA sponges or by modulating the expression of parental genes [5]. Liu et al. [6] screened the differentially expressed circRNAs in endometrium from patients with repeated implantation failure and identified hsa_circRNA_103716 and hsa-circRNA070616 as potential therapeutic agents for this condition [6]. However, circRNAs involved in the establishment of endometrial receptivity remain arcane. In this study, we used circRNA microarrays to characterize the circRNA expressions in LH + 2 and LH + 7 endometrium and identified the differentially expressed circRNAs that may be potential biomarkers for endometrial receptivity.