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Uterine stromal cell decidualization is a dynamic physiological process in which cell proliferation, differentiation and apoptosis are orchestrated and occur in a temporal and cell-specific manner. This process is important for successful embryo implantation. Many cell-cycle regulators are involved in decidualization. The protein cyclin G1 is a unique regulator of the cell cycle with dual functions in cell proliferation. It was reported that cyclin G1 is expressed in mouse uterine stromal cells during the period of peri-implantation. To prove the function of cyclin G1 in mouse uterine stromal cells during this period, immunohistochemistry was used to stain mouse uterine tissues on days 4-8 of pregnancy. The results showed obvious spatial and temporal expression of cyclin G1 in uterine stromal cells, and that it is expressed in the cells of the primary decidual zone (PDZ) on day 5 and secondary decidual zone (SDZ) on days 6 and 7, when the stromal cells experienced active proliferation and differentiation was initiated. Applying the decidualization model of cultured primary stromal cells in vitro, we further revealed that the expression of cyclin G1 is associated with decidualization of stromal cells induced by medroxyprogesterone acetate (MPA) and estradiol-17β (E2). RNA interference was used for the knockdown of cyclin G1 in the induced decidual cells. Flow cytometry analysis indicated that the proportion of cells in the S stage was increased, and decreased in the G2/M phase. Our study indicates that cyclin G1, as a negative regulator of the cell cycle, plays an important role in the process of decidualization in mouse uterine stromal cells by inhibiting cell-cycle progression.

Diabetes-induced hyperglycemia has a direct damaging effect on ovarian function. Despite its deadly impact on ovaries, the mechanism of this condition has not been fully elucidated. Glucose transporters are involved in glucose uptake and utilization. Many transporters have been detected in the ovaries, but their roles in diabetes-induced ovarian impairment are still unclear. In this study, the goal is to analyze glucose transporter expression in the ovarian follicles of type 1 diabetes mellitus patients and determine their roles within ovarian function impairment. The ovarian function of a mouse model of type 1 diabetes mellitus was evaluated by observing its estrus cycle, follicular development, and ovulation. Subtypes of the glucose transporter (GLUT2, GLUT3, GLUT4, SGLT1, and SGLT2), adenosine monophosphate-activated protein kinase (AMPK), and phosphorylated AMPK (Thr172) were found to be simultaneously present in follicle cells. Compared with nondiabetic control mice, the diabetic mice showed a dysregulated estrus cycle and a significantly higher number of abnormal ova. Furthermore, the expression of multiple glucose transporters was lower than that of phosphorylated AMPK. Phosphorylated AMPK possessed more follicular granulosa cells and oocytes of diabetic mice than in those of the control mice. These results suggest that diabetes-induced hyperglycemia reduces the capability of ovarian follicle cells by downregulating glucose transporter expression, causing decreased glucose uptake and energy deprivation. This impact can potentially impair egg maturation and ovulation., (© 2019 by the Association of Clinical Scientists, Inc.)

To investigate the role of progesterone-induced micro-RNA (miR)-152 in early embryonic development and implantation by regulating GLUT3 in endometrial epithelium, qRT-PCR was used to detect the expression of miR-152, GLUT1, and GLUT3 in the endometrial epithelial cells of female mice. GLUT1 and GLUT3 proteins were detected by immunohistochemical staining in the mouse endometrial epithelium. Bioinformatics prediction associated with a luciferase assay was performed to determine whether GLUT1 and GLUT3 are target genes of miR-152. Specific miR-152 mimics or inhibitors were transfected into the endometrial epithelial cells to, respectively, overexpress or downregulate miR-152. Next, the glucose concentration of uterine fluid was measured by conducting high-performance liquid chromatography in vivo, and the glucose uptake of the endometrial epithelial cells was observed using a fluorometric assay in vitro. Early embryonic development and implantation were also observed after the miR-152 mimics or inhibitors had been transfected. Embryo transfer was observed after the miR-152 mimic transfection. miR-152 was found to directly target and thereby downregulate GLUT3 expression. The expressions of both miR-152 and GLUT3 in the mouse endometrial epithelium had spatiotemporal characteristics on days 1-4 of pregnancy. miR-152 affected the glucose concentration of uterine fluid and the glucose uptake of endometrial epithelial cells. The transfection of specific miR-152 mimics led to impaired embryonic development and implantation. To conclude, in endometrial epithelial cells, progesterone-induced miR-152 downregulates GLUT3 at the posttranscriptional level to maintain a proper glucose concentration in the uterine fluid, which is necessary for early embryonic development and implantation.

The aim of the present study was to investigate the effects of progesterone (P4)-induced microRNA-1a (miR-1a) on the proliferation of endometrial epithelial cells (EECs) and the underlying mechanism. In vivo, following subcutaneous injection of estradiol (E2) alone (E2 group) or combined injections of E2 and P4 (E2P4 group) in ovariectomized mice, quantitative real-time PCR (qPCR) was used to check the expression of miR-1a-3p in the directly isolated mouse EECs. The agomir or antagomir specific for miR-1a-3p was injected into one side of the uterine horns of ovariectomized mice pretreated with E2 alone or in combination with P4, and the non-specific control agomir or antagomir was injected into their contralateral horns. Flow cytometry was used to analyze the cell cycle of EECs. Immunohistochemistry (IHC) was used to examine the location and expression of cyclin D2, cyclin E1, and cyclin E2 in the uterine tissue sections. In vitro, primary cultured mouse EECs were pretreated with E2 alone (E2 group) or in combination with P4 (E2P4 group). qPCR was used to detect the expression of miR-1a-3p. Exogenous mimic of miR-1a-3p was transfected into E2-pretreated EECs, and EdU incorporation analysis was used to test the proliferation activity of the EECs. The result of in vivo experiment showed that the expression of miR-1a-3p in E2P4 group was significantly higher than that in E2 group (P < 0.05). The miR-1a-3p agomir arrested cell cycle at G1 to S transition in the mice injected subcutaneously with E2 alone (P < 0.05). Conversely, silencing of miR-1a-3p with transfection of miR-1a-3p antagomir promoted the entry of cells into S phase in the mice injected subcutaneously with both E2 and P4 (P < 0.05). The expressions of cyclin E1 and cyclin E2, except for cyclin D2, in uterine sections were also dramatically reduced by miR-1a-3p overexpression in the uterine epithelium (P < 0.05). In vitro, miR-1a-3p was not expressed in the cells of both E2 and E2P4 groups. The mimic of miR-1a-3p decreased EECs proliferation activity (P < 0.05). These results indicate that P4-induced miR-1a can inhibit the expression of cyclin E1 and cyclin E2, consequently suppressing the proliferation of mouse EECs by arresting cells at G1/S phase.

Estrogen is one of the steroid hormones. Besides the genomic action mediated by its intracellular receptor on target cells, there is now increasing body of evidence indicating that estrogen also has non-genomic action. For the non-genomic action, estrogen binds to its receptor on cell membrane, subsequently rapidly activates various intracellular signaling pathways, such as PLC/Ca(2+), ERK/MAPK, cAMP-PKA, PI3K-AKT-NOS, and finally induces biological effects. The non-genomic effects of estrogen on physiologic and pathologic processes have been found in many tissues within the reproductive, nervous and cardiovascular systems and bone etc. In reproductive system, it has been demonstrated that estrogen plays important roles in follicle development, fertilization and embryo implantation, and it is involved in the genesis and development of genital tract tumors and breast cancer. In this review, we focus on the general characteristics of non-genomic action of estrogen, its main nonnuclear signaling pathways and physiological and pathological significance, especially its influences in female reproductive functions.

Objective: To determine the expression of microRNA-152 induced by progesterone and its effect on the proliferation of endometrial epithelial cells (EECs)., Methods: Cultured EECs, Ishikawa were divided into four groups: control group (C group), 10(-8) mol/L estrogen treated group (E group), 10(-6) mol/L progesterone group (P group) and estrogen plus progesterone treated group (E&P group). The expression of mature microRNA-152 (microRNA-152-3p) of was detected by qRT-PCR. The estrogen treated cells were transfected with mimic-microRNA-152-3p. The estrogen and progesterone treated cells were transfected with inhibitor-microRNA-152-3p. Cell proliferations were detected by CCK-8 assay. The target gene of microRNA-152-3p proteins was predicted using microRNA target databases and validated by Western blot., Results: qRT-PCR showed no difference between C and E groups (P > 0.05) in the expression of microRNA-152-3p. P group had higher expressions of microRNA-152-3p than C group (P < 0.05). E&P group had higher expressions of microRNA-152-3p than C group and P group. MicroRNA target protein prediction suggested that CDC14A is one of direct target proteins of microRNA-152-3p. The results of CCK-8 assay showed that mimic-microRNA-152-3p transfection blocked proliferations of estrogen treated cells and lowered expressions of CDC14A in these cells; while inhibitor-microRNA-152-3p promotes proliferations of estrogen and progesterone treated cells and increased expressions of CDC14A in these cells., Conclusion: Progesterone may suppress proliferations of EECs through inducing expressions of microRNA-152-3p. CDC14A is probably one target protein of microRNA-152-3p for its action on EECs.

Integrins are the dominant and final adhesion molecules in the attachment process between the blastocysts and endometrium. It is necessary for oestrogen to rapidly activate mouse blastocysts so that they attach to the endometrial epithelium. Our previous study suggested that oestrogen can rapidly induce an increase in intracellular calcium in mouse blastocysts via G-protein-coupled receptor 30 (GPR30). Thus, we deduced that integrins may be involved in GPR30 mediation of the fast effect of oestrogen on mouse blastocysts in implantation. To prove our hypothesis, we used immunofluorescence staining and in vitro coculture of mouse blastocysts and endometrial epithelial cell line (EECs), Ishikawa cells, in the present study. We found that αv and β1 integrin clustered in mouse blastocysts, and that β3 integrin was relocalised to the apical membrane of blastocyst cells when embryos were treated with 1 μM 17β-estradiol (E2), 1 μM E2 conjugated to bovine serum albumin (E2-BSA) and 1 μM G-1, a specific GPR30 agonist, for 30 min respectively, whereas pretreatment with 1 μM G15, a specific GPR30 antagonist, and 5 μM 1,2-Bis(2-aminophenoxy)ethane-N,N,N'',N''-tetraacetic acid tetrakis (acetoxymethyl ester)(BAPTA/AM), a cellular Ca2+ chelator, blocked the localisation of integrins induced by oestrogen via GPR30 in mouse blastocyst cells. E2, E2-BSA and G-1 increased the fibronectin (FN)-binding activity of integrins in blastocysts, whereas G15 and BAPTA/AM blocked the activation of integrins induced by oestrogen via GPR30 in mouse blastocysts. Inhibition of integrins by Arg-Gly-Asp peptide in blastocysts resulted in their failure to adhere to EECs in vitro, even if oestrogen or G-1 was provided. Together, the results indicate the fast effect of oestrogen via the GPR30 membrane receptor further induces relocalisation and activation of integrins in mouse blastocysts, which play important roles in the adhesion of blastocysts to EECs.

Objective: To study the roles of the increased intracellular calcium induced rapidly by estrogen in the implantation of mouse blastocysts., Methods: The mouse blastocysts were collected from the female mice on the pregnant day 4, divided into 3 groups: control, E2-BSA and BAPTA +E2-BSA. Immunofluorescence staining, confocal microscopy, embryo and endometrial epithenial cells co-culture and embryo transfer were used to investigate the effect of increased intracellular calcium induced by E2-BSA on the expression and localization of integrins in blastocysts and their adhesion to endometrial epithenial calls (EECs) and implantation into the endometrium., Results: The increase of intracellular calcium induced rapidly by estrogen could cause the cluster and relocation of integrin av and beta3, and BAPTA might block this effect, the adhesion rate of blastocysts in contol group was 35.5%, BAPTA +E2-BSA group was 26.7% and significantly lower than 65.6% of E2-BSA group (P<0.05), and the implantation rate in BAPTA+E2-BSA group was 11.8%, which was significantly lower than 52.9% of E2-BSA group (P<0.05)., Conclusion: The rapid increase of intracellular calcium induced by estrogen may cause the relocalization of integrin in blastocysts and their adhesion to ECCs, which is important in the process of implantation.

Objective: To study the effect of protein phosphatase 2A (PP2A) in the negative regulation of progesterone on the proliferation of mouse endometrial epithelial cells (EECs)., Methods: Mouse EECs were isolated and cultured in vitro, which were divided into four groups when they grown to confluence: control group (P4) was treated with 1 micromol/L progesterone only, group A, B and C were treated respectively with 1 micromol/L progesterone and different concentrations of okadaic acid (5 nmol/L, 10 nmol/L and 20 nmol/L). After 24 h, the numbers of cells in different phases of the cell cycle were counted with flow cytometry., Results: The effect of OA on mouse EECs was concentration-dependent. Compared with control group of P4, the change of cell cycle procession in group A was not obvious. Lower proportion of cells in G1 and G2/M phase and higher proportion of cells in S phase in group B, higher proportion of cells in G1 and S phase and lower proportion of cells in G2/M phase in group C were observed., Conclusion: Adequate dose OA inhibiting PP2A could release the inhibitory effect of progesterone on proliferation of mouse EECs obviously, this suggested that PP2A was involved in the inhibitory effect of progesterone on proliferation of EECs by influencing the process of cell cycle.