The Orphan Nuclear Receptor Nur77 Interacts With FOXO1A To Regulate The Expression Of PRL And IGFBP1 In Human Endometrial Stromal Cells In Vitro

Orphan nuclear receptor Nur77 is a novel transcription factor that contributes significantly to the regulation of prolactin and IGFBP1 expression in human endometrial stromal cells.But the mechanism is unclear.Using yeast two-hybrid screen with Nur77 as bait from human universal cDNA library,we identified that FOXO1A is a new Nur77-interacting protein.In this study,we attempt to explore the role of the interaction of Nur77 with FOXO1A in human endometrium.Co-immunoprecipitation indicated that Nur77 and FOXOIA can immunoprecipitation with each other.Moreover,domain mapping assay indicated that it was Nur77 LBD/DBD that mediated the binding of Nur77 in FOXOIA,and it was FOXOIA DBD that mediated the binding of FOXOIA in Nur77.To testify whether Nur77 LBD/DBD interacted with FOXO1A in vivo,we found that endogenous FOXO1A formed a physical complex with Nur77 LBD/DBD in HESCs induced by 8-Br-cAMP and MPA.Luciferase reporter gene assays showed that overexpression of Nur77 LBD/DBD markedly downregulated the promoter activity of FOXO1A-mediated IRS in HEK293 cells and the promoter activity of PRL and IGFBP1 in HESCs induced by 8-Br-cAMP and MPA.Besides,adenovirus mediated overexpression of Nur77 LBD/DBD inhibited FOXO1A-mediated the expression and secretion of PRL and IGFBP1 in HESCs during decidualization in vitro.All these results indicated that Nur77 LBD/DBD mediated the interaction with FOXOIA and downregulated the expression of PRL and IGFBP1in HESCs.Real-Time PCR?ELISA and ELIFA indicated that overexpression of Nur77 LBD/DBD markedly inhibited the expression and secretion of PRL and IGFBP1 in HESCs induced by 8-Br-cAMP and MPA.Immunofluorescence microscopy further indicated that Nur77 LBD/DBD treated decidualizing HESCs retained an undifferentiated fibroblastic phenotype and displayed a poorly formed,diffuse network of actin cytoskeleton.Infect mice uteri with Ad-Flag-Nur77 LBD/DBD and Ad-CTL,then subject to artificial decidual stimulation.Histomorphology analysis showed that Nur77 LBD/DBD inhibit embryo implantation and endometrial decidualization in mice.In summary,all these results above demonstrated that Nur77 LBD and DBD mediates the physically interaction of Nur77 and FOXO1A,and the interaction of Nur77 LBD/DBD and FOXO1A repress the expression and secretion of FOXO1A-meidated PRL and IGFBP1 in HESC induced by 8-Br-cAMP and MPA.