Study On The Role Of The Nuclear Receptor Nor1in Vitro Decidualization Of Human Endometrial Stromal Cells

During early pregnancy, the uterine stromal cells undergo extensive proliferation,differentiation and remodeling, known as decidualization. This hormonally inducedcellular transformation is a complex process regulated by the steroid hormones estrogenand progesterone, which is an essential prerequisite for embryo implantation. However, theprecise regulation mechanisms of this process are not known. Our studies demonstratedthat the nuclear receptor NR4A3(namely NOR1) persisted expression duringpreimplantation and reached the maximal at the3.5th day of copulation, the expression ofNOR1mRNA at the3.5th day of copulation was significantly increased by4-fold comparewith the expression of un-pregnancy mouse uterus; In addition, the expression of NOR1mRNA was significantly increased by6-fold at2h in hESCs after a decidualizationstimulus of0.5mM8-Br-cAMP plus1μM medroxyprogesterone acetate (MPA). Theseresults implicate that NOR1may involved in the regulation of decidualization.Approximately1.9kb of harboring the Flag-tagged human full-length NOR1gene wasamplified by reverse transcription PCR (RT-PCR) and PCR from human endometrialstromal cells total mRNA; We successfully obtained1×1011ifu/mL adenovirus-Flag-NOR1which could dramatically increased NOR1expression in human endometrialstromal cells. Adenovirus-mediated overexpression of NOR1(MOI=50) in hESCsmarkedly enhanced decidualization marked genes decidual prolactin (dPRL) promoter(dPRL/-332Luc) and Insulin-like growth factor binding protein-1promoter(IGFBP-1/-1012Luc) activity; Moreover, overexpression of NOR1in hESCs markedlyincreased both dPRL mRNA and IGFBP-1mRNA expression and protein secretion (P <0.01). Furthermore, knockdown of endogenous NOR1expression in hESCs significantly decreased decidual PRL release （day4:27.02±4.08ng/mL vs47.65±6.05ng/mL, andday8:61.32±17.27ng/mL vs177.96±12.02ng/mL, P <0.01, vs control siRNA group, n=4）and IGFBP-1protein secretion（day8:30±1.27μg/mL vs19.64±3.52μg/mL, P <0.01, vs control siRNA group, n=4）in the culture medium of hESC cells induced by8-Br-cAMP and MPA.In summary, all these results above demonstrate that NOR1is considered to regulatedecidual PRL and IGFBP-1gene expression during8Br-cAMP plus MPA-induceddecidualization in human endomentiral stromal cells. Our study suggests that NOR1is apotential target for treatment of infertility.