| Background: The ultimate goal of in vitro fertilization-embryo transfer(IVF-ET)and its derivative technology is to make infertile patients pregnant successfully,and the key link is embryo implantation.Recurrent implantation failure(RIF)is a clinical phenomenon,which is only applicable to patients treated with assisted reproductive technology(ART).RIF refers only to patients undergoing ART and describes a lack of successful implantation after repeated transfers of morphologically goodquality embryos into a normal uterus.RIF is a challenge for clinicians,which can be devastating for infertile patients.Successful implantation is a complex process that is influenced by embryo quality,endometrial receptivity,immune factors,and the specific type of in vitro fertilization protocol used,among which endometrial receptivity is the key factor.Endometrial receptivity provides the best environment for embryonic development and placenta formation.Improving endometrial receptivity is the key to improve pregnancy rate.Therefore,endometrial receptivity has been the focus of extensive research in the field of reproductive medicine.At present,RIF remains a critical problem and challenge in IVF-ET.Although a series of advances has been made in this field,endometrial receptivity still cannot be accurately evaluated to improve the pregnancy rate.In our previous study,DNA topoisomerase IIα(TOP2A)was found to be the key gene for RIF.TOP2 A is a nuclear protein required for DNA replication and cell division.It is highly expressed during mitosis,essential for cell division and is a biomarker of cell proliferation.However,its involvement in recurrent implantation failure has not been reported.Purpose: The present study sought to screen the key proteins associated with endometrial receptivity to clarify their roles and possible mechanisms in the pathogenesis of RIF.This study aims to clarify the effect of TOP2 A on endometrium and explore the feasibility of using TOP2 A as the target to regulate endometrial receptivity in RIF.This study sought to provide new ideas and theoretical basis for the prevention and treatment of RIF.Methods: The human endometrial tissues of normal controls and RIF patients were collected.A proteomic analysis was performed to evaluate the differentially expressed proteins between the RIF group and control group.The expression patterns of TOP2 A in human pre-implantation endometrium of RIF patients were determined by IHC staining,Western Blot and q RT-PCR.TOP2A-knockdown(sh-TOP2A)of T-HESCs were generated using lentiviruses.The expression of TOP2 A in T-HESCs was manipulated to investigate its role in decidualization.The TOP2A-related changes in decidualization were firstly screened by m RNA sequencing in decidualized TOP2A-knockdown and control T-HESCs,then confirmed by Western Blot and Immunofluorescence staining.TOP2A-deficient mice were generated by injection of TOP2 A interfering adenovirus through tail vein on GD2.5 and GD3.5.Results: Based on our previous findings,we performed a proteomic analysis of endometrial tissues to investigate the potential pathogenesis of RIF by comparing RIF patients and matched controls and found that DNA topoisomerase IIα(TOP2A)might be a key protein in RIF.TOP2 A is ubiquitously expressed in both stromal and glandular epithelial cells of the endometrium.The data indicate that TOP2 A expression dynamically changes during the menstrual cycle and is significantly lower in the midsecretory endometrium of women with RIF.TOP2 A expression is downregulated under stimulation by 8-bromo-c AMP and MPA.Ablation of TOP2 A resulted in enhanced decidualization,and coincidence with upregulation of decidual biomarkers and morphological changes of the cells.The mechanistic analysis revealed the TOP2 A regulates the NF-κB signaling pathway in decidualized T-HESCs.TOP2A-deficient mice exhibited lower weight of fetuses.Lack of TOP2 A predisposed mice to impaired fertility.Our results suggest that decreased TOP2A-mediated NF-κB expression plays an important role in RIF.Conclusions: We demonstrated for the first time that the expression of TOP2 A changes dynamically during the menstrual cycle,and the expression level of TOP2 A is significantly reduced in the endometrium of RIF patients.We analyzed the role of TOP2 A in the pathogenesis of RIF.Abnormal expression of TOP2 A affects decidualization and changes the“window of implantation”,leading to RIF.TOP2 A participates in the processes of decidualization and embryo implantation,functioning at least in part through the NF-κB pathway.Our results suggest that decreased TOP2A-mediated NF-κB expression plays an important role in RIF.Regulating the expression of TOP2 A in endometrium may become a new strategy for the prevention and treatment of RIF. |
