The Correlation Between HOXA10and MMP-9in Embryo Implantation,and The Implantation-related Signaling Pathways

The homeobox gene HOXA10is one of transcriptional regulatory genes in multigene families. It is involved in reproductive tract development, regulation of embryo development and implantation, decision of cell differentiation and proliferation. It can induce endometrium to mature and direct embryo to implant through activating and inhibiting the transcription of its downstream genes. It plays a crucial role in endometrial receptivity. Matrix metalloproteinase-9is one of zinc-dependent proteolytic enzymes with the function of degrading a variety of extracellular matrix protein. It can degrade type IV collagen, type V collagen and fibronectin specifically, and play a significant role in the process of embryo implantation and trophoblastic cell infiltrating endometrium. Till now, the relationship between HOXA10and MMP-9expression in embryo implantation, and the transcription regulation of MMP-9by HOXA10have not been reported in the literature. This study focuses on the relationship between HOXA10and MMP-9expression in the early pregnancy decidua, the binding sites distribution of the transcription factor in the promoter region of MMP-9by bioinformatics analysis, and the regulation of MMP-9by the related transcription factor HOXA10and NF-κB.In vitro experiments, we confirmed that there is HOXA10and MMP-9mRNA and protein expression in early pregnancy decidua, and are highly correlated, which suggests that there may be a synergistic or regulatory mechanism between HOXA10and MMP-9in the embryo implantation process, HOXA10may be the upstream gene of MMP-9that regulates the expression of MMP-9. For further confirm, we used TFSITESCAN software to analyze0～-3000bp base sequence in the translation initiation codon ATG upstream of MMP-9. We found one HOXA10binding conservative repetitive sequence:TT ATT ATT ATT AT, in the MMP-9promoter upstream-1985bp position, which is four TTAT core base sequence repeated order, suggesting that MMP-9has high-affinity binding ability to HOXA10. Also, we found five NF-κB binding sites in the promoter region of MMP-9. These results indicate that MMP-9may be regulated by HOXA10and NF-κB. This bioinformatics evidence is also a strong theoretical support for further study in regulation of MMP-9by HOXA10and NF-κB. Then, we used siRNA to interfere the expression of HOXA10gene in Hela cell lines and used NF-κB inhibitor and agonist to induce Hela cells. The results show that HOXA10and NF-κB positively regulate the expression of MMP-9.The above research suggests that the expression of HOXA10and MMP-9in early pregnancy decidua is highly related. We also have confirmed that MMP-9is the downstream target gene of HOXA10and positively regulated by HOXA10in the level of molecular mechanism. These findings are helpful for us to further understand the mechanism of embryo implantation. They also indicate that we maybe provide a stronger theoretical basis for reproductive regulation and infertility treatment through further research on HOXA10downstream genes and related signaling pathways to find more key factors that regulate embryo implantation.