Aminopeptidase N expression in the endometrium could affect endometrial receptivity

Aminopeptidase N (ANPEP) is a membrane-bound zinc-dependent peptidase. Although it is widely believed that ANPEP acts as an important angiogenesis regulatory factor, there are few studies about its function in the female reproductive system. In our previous research, we applied Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) to analyze the influence of different controlled superovulation treatments for Assisted Reproductive Technology, In Vitro Fertilization and Embryo Transfer (IVF-ET)) patients from a global proteomic perspective to search for potential biomarkers associated with endometrium receptivity and embryo implantation. ANPEP is one of the proteins that demonstrated differential expression between different treatment groups and may be closely associated with endometrial receptivity. In this study, we assessed the expression of ANPEP in the endometrium of mice at different ages and found it to be highest in the mature period. We also detected ANPEP expression in the endometrium of IVF-ET patients in the proliferative, preimplantation and implantation stages, and the highest expression level of ANPEP was found in the last group. Human primary endometrial stromal cells were infected with an adenovirus expression vector containing the ANPEP gene and a green fluorescent protein (GFP) fusion protein; the mRNA levels of HOXA-10, LIF, and integrin β3 were found to be increased. Therefore, we conclude that ANPEP could be involved in the regulation of endometrial receptivity.