Human Endometrial Decidualization Research Articles

Metabolic reprogramming and heterogeneity during the decidualization process of endometrial stromal cells

The human endometrial decidualization is a transformative event in the pregnant uterus that involves the differentiation of stromal cells into decidual cells. While crucial to the establishment of a successful pregnancy, the metabolic characteristics of decidual cells in vivo remain largely unexplored. Here, we integrated the single-cell RNA sequencing (scRNA-seq) datasets on the endometrium of the menstrual cycle and the maternal-fetal interface in the first trimester to comprehensively decrypt the metabolic characteristics of stromal fibroblast cells. Our results revealed that the differentiation of stromal cells into decidual cells is accompanied by increased amino acid and sphingolipid metabolism. Furthermore, metabolic heterogeneity exists in decidual cells with differentiation maturity disparities. Decidual cells with high metabolism exhibit higher cellular activity and show a strong propensity for signaling. In addition, significant metabolic reprogramming in amino acids and lipids also occurs during the transition from non-pregnancy to pregnancy in the uteri of pigs, cattle, and mice. Our analysis provides comprehensive insights into the dynamic landscape of stromal fibroblast cell metabolism, contributing to our understanding of the metabolism at the molecular dynamics underlying the decidualization process in the human endometrium.

Dysregulation of endometrial stromal serotonin homeostasis leading to abnormal phosphatidylcholine metabolism impairs decidualization in patients with recurrent implantation failure.

Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased monoamine oxidase (MAO) expression, affects the decidualization of endometrial stromal cells and leads to embryo implantation failure. Previous studies have indicated that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and, if so, the mechanism involved, remains unclear. Endometrial samples from 25 patients with RIF and 25 fertile patients were used to investigate the expression levels of monoamine oxidase A (MAOA), monoamine oxidase B (MAOB), and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB, and serotonin in inducing decidualization in vitro and further explored the underlying mechanism using RNA-sequencing (RNA-seq) and liquid chromatography-mass spectrometry (LC/MS) analyses. The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes involved in abnormal serotonin metabolism were analyzed via combination with single-cell sequencing data. The effects of MAOA or MAOB on the decidualization of stromal cells were investigated using an in vitro human endometrial stromal cell-induced decidualization model and a mouse artificially induced decidualization model. The potential mechanisms by which MAOA and MAOB regulate decidualization were explored by RNA-seq and LC/MS analysis. We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. However attenuated MAO caused an increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in the defective decidualization caused by MAO deficiency. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. RNA-seq information and raw data can be found at NCBI Bioproject number PRJNA892255. This study revealed that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were among the reasons for RIF. However, the source and other potential functions of serotonin in the endometrium remain to be further explored. This study provides new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and new biomarkers or targets for the treatment of patients with RIF. X. Sheng is supported by grants from the National Natural Science Foundation of China (82001629), the Wenzhou Basic Public Welfare Research Project (Y20240030), the Youth Program of Natural Science Foundation of Jiangsu Province (BK20200116), and Jiangsu Province Postdoctoral Research Funding (2021K277B). H.S. is supported by grants from the National Natural Science Foundation of China (82030040). G.Y. is supported by grants from the National Natural Science Foundation of China (82171653). The authors declare no conflicts of interest.

Progesterone-induced progesterone receptor membrane component 1 rise-to-decline changes are essential for decidualization.

Decidualization of endometrial cells is the prerequisite for embryo implantation and subsequent placenta formation and is induced by rising progesterone levels following ovulation. One of the hormone receptors contributing to endometrial homeostasis is Progesterone Receptor Membrane Component 1 (PGRMC1), a non-classical membrane-bound progesterone receptor with yet unclear function. In this study, we aimed to investigate how PGRMC1 contributes to human decidualization. We first analyzed PGRMC1 expression profile during a regular menstrual cycle in RNA-sequencing datasets. To further explore the function of PGRMC1 in human decidualization, we implemented an inducible decidualization system, which is achieved by culturing two human endometrial stromal cell lines in decidualization-inducing medium containing medroxyprogesterone acetate and 8-Br-cAMP. In our system, we measured PGRMC1 expression during hormone induction as well as decidualization status upon PGRMC1 knockdown at different time points. We further conferred proximity ligation assay to identify PGRMC1 interaction partners. In a regular menstrual cycle, PGRMC1 mRNA expression is gradually decreased from the proliferative phase to the secretory phase. In in vitro experiments, we observed that PGRMC1 expression follows a rise-to-decline pattern, in which its expression level initially increased during the first 6days after induction (PGRMC1 increasing phase) and decreased in the following days (PGRMC1 decreasing phase). Knockdown of PGRMC1 expression before the induction led to a failed decidualization, while its knockdown after induction did not inhibit decidualization, suggesting that the progestin-induced 'PGRMC1 increasing phase' is essential for normal decidualization. Furthermore, we found that the interactions of prohibitin 1 and prohibitin 2 with PGRMC1 were induced upon progestin treatment. Knocking down each of the prohibitins slowed down the decidualization process compared to the control, suggesting that PGRMC1 cooperates with prohibitins to regulate decidualization. According to our findings, PGRMC1 expression followed a progestin-induced rise-to-decline expression pattern during human endometrial decidualization process; and the correct execution of this expression program was crucial for successful decidualization. Thereby, the results of our in vitro model explained how PGRMC1 dysregulation during decidualization may present a new perspective on infertility-related diseases.

ATOH8 Expression Is Regulated by BMP2 and Plays a Key Role in Human Endometrial Stromal Cell Decidualization.

During the secretory phase of the menstrual cycle, elongated fibroblast-like mesenchymal cells in the uterine endometrium begin to transdifferentiate into polygonal epithelioid-like (decidual) cells. This decidualization process continues more broadly during early pregnancy, and the resulting decidual tissue supports successful embryo implantation and placental development. This study was carried out to determine if atonal basic helix-loop-helix transcription factor 8 (ATOH8) plays a role in human endometrial stromal fibroblast (ESF) decidualization. ATOH8 messenger RNA and protein expression levels significantly increased in human ESF cells undergoing in vitro decidualization, with the protein primarily localized to the nucleus. When ATOH8 expression was silenced, the ability of the cells to undergo decidualization was significantly diminished. Overexpression of ATOH8 enhanced the expression of many decidualization markers. Silencing the expression of ATOH8 reduced the expression of FZD4, FOXO1, and several known FOXO1-downstream targets during human ESF cell decidualization. Therefore, ATOH8 may be a major upstream regulator of the WNT/FZD-FOXO1 pathway, previously shown to be critical for human endometrial decidualization. Finally, we explored possible regulators of ATOH8 expression during human ESF decidualization. BMP2 significantly enhanced ATOH8 expression when cells were stimulated to undergo decidualization, while an ALK2/3 inhibitor reduced ATOH8 expression. Finally, although the steroids progesterone plus estradiol did not affect ATOH8 expression, the addition of cyclic adenosine monophosphate (cAMP) analogue alone represented the major effect of ATOH8 expression when cells were stimulated to undergo decidualization. Our results suggest that ATOH8 plays a crucial role in human ESF decidualization and that BMP2 plus cAMP are major regulators of ATOH8 expression.

P-313 Dysregulation of endometrial stromal serotonin homeostasis impairs decidualization in patients with recurrent implantation failure via phosphatidylcholine metabolism

Abstract Study question Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Summary answer Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased expression of monoamine oxidase (MAO), affects decidualization of endometrial stromal cells. What is known already Previous studies have found that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and the mechanism remains unclear. Study design, size, duration Endometrial samples from 31 patients with RIF and 31 fertile patients were used to investigate the expression levels of MAOA, MAOB, and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB and serotonin in inducing decidualization in vitro and further explored the mechanism using RNA-seq and LC/MS analyses. Participants/materials, setting, methods The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes of abnormal serotonin metabolism were analyzed combined with single-cell sequencing data. The effects of MAO on the decidualization of stromal cells were investigated using human endometrial stromal cells in vitro induced decidualization model and mouse artificially induced decidualization model. The potential mechanisms of MAO regulating decidualization were explored by RNA-seq and LC/MS analysis. Main results and the role of chance We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. Attenuated MAO caused increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in MAO-deficiency induced defective decidualization. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. Limitations, reasons for caution This study found that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were one of the reasons for repeated implantation failure. However, the source and other potential function of serotonin in the endometrium remain to be further explored. Wider implications of the findings This study shows new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and provides new biomarkers or targets for the treatment of patients with RIF. Trial registration number not applicable

P-313 Dysregulation of endometrial stromal serotonin homeostasis impairs decidualization in patients with recurrent implantation failure via phosphatidylcholine metabolism

Abstract Study question Does abnormal serotonin homeostasis contribute to impaired endometrial decidualization in patients with recurrent implantation failure (RIF)? Summary answer Abnormal serotonin homeostasis in patients with RIF, which is accompanied by decreased expression of monoamine oxidase (MAO), affects decidualization of endometrial stromal cells. What is known already Previous studies have found that the expression of MAO, which metabolizes serotonin, is reduced in the endometrium of patients with RIF, and serotonin can induce disruption of implantation in rats. However, whether abnormal serotonin homeostasis leads to impaired decidualization in patients with RIF and the mechanism remains unclear. Study design, size, duration Endometrial samples from 31 patients with RIF and 31 fertile patients were used to investigate the expression levels of MAOA, MAOB, and serotonin. We isolated human endometrial stromal cells to investigate the role of MAOA, MAOB and serotonin in inducing decidualization in vitro and further explored the mechanism using RNA-seq and LC/MS analyses. Participants/materials, setting, methods The levels of serotonin in the endometrium of patients with RIF were detected by ELISA and immunohistofluorescence, and the key genes of abnormal serotonin metabolism were analyzed combined with single-cell sequencing data. The effects of MAO on the decidualization of stromal cells were investigated using human endometrial stromal cells in vitro induced decidualization model and mouse artificially induced decidualization model. The potential mechanisms of MAO regulating decidualization were explored by RNA-seq and LC/MS analysis. Main results and the role of chance We found that women with RIF have abnormal serotonin metabolism in the endometrium and attenuated MAO in endometrial stromal cells. Endometrial decidualization was accompanied by increased MAO in vivo and in vitro. Attenuated MAO caused increased local serotonin content in the endometrium, impairing stromal cell decidualization. RNA-seq and LC/MS analyses showed that abnormal lipid metabolism, especially phosphatidylcholine metabolism, was involved in MAO-deficiency induced defective decidualization. Furthermore, decidualization defects were rescued by phosphatidylcholine supplementation. Limitations, reasons for caution This study found that impaired serotonin metabolic homeostasis and abnormally reduced MAO expression were one of the reasons for repeated implantation failure. However, the source and other potential function of serotonin in the endometrium remain to be further explored. Wider implications of the findings This study shows new insights into the mechanisms of serotonin homeostasis in human endometrial decidualization and provides new biomarkers or targets for the treatment of patients with RIF. Trial registration number not applicable Study funding No Funding source Funding by national/international organization(s)

ENDOMETRIAL ADHESION G-PROTEIN COUPLED RECEPTOR EXPRESSION IS ALTERED BY OVARIAN STIMULATION

Ovarian stimulation (OS) is associated with altered endometrial histological development and gene expression which may impact receptivity in fresh embryo transfers. We sought to determine the effect of OS on the expression of endometrial genes encoding adhesion G protein-coupled receptors (ADGRs). While ADGRG2 has been identified as a regulator of human endometrial decidualization and receptivity, less is known regarding the roles of other ADGRs in the human endometrium. We hypothesized that in a natural cycle (NC) ADGRs are expressed in the secretory endometrium but following OS their expression is altered.

SOX4 facilitates PGR protein stability and FOXO1 expression conducive for human endometrial decidualization.

The establishment of pregnancy in human necessitates appropriate decidualization of stromal cells, which involves steroids regulated periodic transformation of endometrial stromal cells during the menstrual cycle. However, the potential molecular regulatory mechanism underlying the initiation and maintenance of decidualization in humans is yet to be fully elucidated. In this investigation, we document that SOX4 is a key regulator of human endometrial stromal cells decidualization by directly regulating FOXO1 expression as revealed by whole genomic binding of SOX4 assay and RNA sequencing. Besides, our immunoprecipitation and mass spectrometry results unravel that SOX4 modulates progesterone receptor (PGR) stability through repressing E3 ubiquitin ligase HERC4-mediated degradation. More importantly, we provide evidence that dysregulated SOX4-HERC4-PGR axis is a potential cause of defective decidualization and recurrent implantation failure in in-vitro fertilization (IVF) patients. In summary, this study evidences that SOX4 is a new and critical regulator for human endometrial decidualization, and provides insightful information for the pathology of decidualization-related infertility and will pave the way for pregnancy improvement.

MAX deficiency impairs human endometrial decidualization through down-regulating OSR2 in women with recurrent spontaneous abortion

Human uterine stromal cell undergoes decidualization for pregnancy establishment and maintenance, which involved extensive proliferation and differentiation. Increasing studies have suggested that recurrent spontaneous abortion (RSA) may result from defective endometrial stromal decidualization. However, the critical molecular mechanisms underlying impaired decidualization during RSA are still elusive. By using our recently published single-cell RNA sequencing (scRNA-seq) atlas, we found that MYC-associated factor X (MAX) was significantly downregulated in the stromal cells derived from decidual tissues of women with RSA, followed by verification with immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). MAX knockdown significantly impairs human endometrial stromal cells (HESCs) proliferation as determined by MTS assay and Ki67 immunostaining, and decidualization determined by F-actin, and decidualization markers. RNA-seq together with chromatin immunoprecipitation sequencing (ChIP-seq) and cleavage under targets and release using nuclease sequencing (CUT&RUN-seq) analysis were applied to explore the molecular mechanisms of MAX in regulation of decidualization, followed by dual-luciferase reporter assay to verify that MAX targets to (odd-skipped related transcription factor 2) OSR2 directly. Reduced expression of OSR2 was also confirmed in decidual tissues in women with RSA by IHC and qRT-PCR. OSR2 knockdown also significantly impairs HESCs decidualization. OSR2-overexpression could at least partly rescue the downregulated insulin-like growth factor binding protein 1 (IGFBP1) expression level in response to MAX knockdown. Collectively, MAX deficiency observed in RSA stromal cells not only attenuates HESCs proliferation but also impairs HESCs decidualization by downregulating OSR2 expression at transcriptional level directly.

CircSTK40 contributes to recurrent implantation failure via modulating the HSP90/AKT/FOXO1 axis

Increasing evidence has revealed a close relationship between non-coding RNAs and recurrent implantation failure (RIF). However, the role of circular RNAs (circRNAs) in RIF pathogenesis remains largely unknown. Microarray analyses were used to identify the differentially expressed circRNA-circSTK40. Functional experiments, including decidualization induction and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay, were performed to determine the effects of circSTK40 on human endometrial stromal cells (ESCs). The interactions between circSTK40 and proteins were investigated by RNA pull-down, RNA immunoprecipitation, and co-immunoprecipitation (coIP) assays. We observed that circSTK40 expression was upregulated in the RIF midluteal-phase endometrial samples. circSTK40 overexpression in ESCs inhibited the decidualization process but concurrently enhanced cell survival during stress. Mechanistically, circSTK40 directly bound to HSP90 and CLU, thus functioning as a scaffold to block their interactions and hinder the proteasomal degradation of HSP90. The resulting high levels of HSP90 led to the activation of the AKT pathway and downregulation of FOXO1 expression. Inhibitors of AKT (MK-2206) and HSP90 (17AAG) both abolished the effects of circSTK40 overexpression in ESCs and increased the decidualization levels in a dose-dependent manner. Our findings indicate a novel epigenetic mechanism for RIF pathogenesis involving circSTK40 activity and provide a foundation for targeted treatments in patients with low endometrial receptivity.

Melatonin Advances Human Decidualization Through Epithelial-Stromal Crosstalk

Background: Embryo implantation and decidualization are essential to the establishment and maintenance of successful pregnancy in both rodents and primates. Receptive endometrium synergism with well-developed blastocyst is prerequisite for successful embryo implantation. Melatonin, which is mainly synthesized by the pineal gland in vertebrates, promotes human blastocyst development and increases pregnancy rate. However, the role and underlying mechanism of melatonin on human endometrial receptivity and decidualization still remains poorly defined. Methods: Trophoblast JEG-3 spheroids were cocultured with endometrial epithelial cells. Real-time PCR, Western blot, siRNA transfection, epithelial-stromal cell coculture system, and assay of Ishikawa cell-conditioned medium were used to explore the effects of melatonin on human endometrial decidualization and the underlying molecular pathways. Findings: In this study, we showed that melatonin induces the expression of the endometrial receptive markers, integrin β3 and HOXA10 in the less-receptive endometrial epithelial cell line AN3 CA and increased the attachment rate of trophoblast JEG-3 spheroids on endometrial epithelial AN3 CA cells. In an epithelial-stromal coculture system, we further proved that melatonin-stimulated IFN-γ secretion from Ishikawa cells promotes in vitro decidualization of stromal cells through regulating progesterone receptor B (PRB). Under in vitro decidualization, IFN-γ significantly increases the levels IGFBP1 and PRL, which is abrogated by suppressing PRB. Under in vitro decidualization of endometrial stromal cells, the expression of the decidualization markers, IGFBP1 and PRL, is significantly stimulated by melatonin treatment. Melatonin obviously increases phosphorylated STAT3 level and decreases p-Akt level. Interpretation: Melatonin may play crucial roles in human endometrial receptivity and decidualization. The dialogue between endometrial epithelial and stromal cell mediated by melatonin should be beneficial for decidual process. Funding: National Key R&D Program of China (2018YFC1004403) and National Natural Science Foundation of China (31671563, 31871511). Declaration of Interests: The authors declare that there is no conflict of interest. Ethics Approval Statement: All human procedures were approved by the Institutional Committee on the Use of Human Subjects in Medical Research of Southern Medical University with written consent.

The Autophagy Gene Atg16L1 is Necessary for Endometrial Decidualization.

Uterine receptivity is critical for establishing and maintaining pregnancy. For the endometrium to become receptive, stromal cells must differentiate into decidual cells capable of secreting factors necessary for embryo survival and placental development. Although there are multiple reports of autophagy induction correlated with endometrial stromal cell (ESC) decidualization, the role of autophagy in decidualization has remained elusive. To determine the role of autophagy in decidualization, we utilized 2 genetic models carrying mutations to the autophagy gene Atg16L1. Although the hypomorphic Atg16L1 mouse was fertile and displayed proper decidualization, conditional knockout in the reproductive tract of female mice reduced fertility by decreasing the implantation rate. In the absence of Atg16L1, ESCs failed to properly decidualize and fewer blastocysts were able to implant. Additionally, small interfering RNA knock down of Atg16L1 was detrimental to the decidualization response of human ESCs. We conclude that Atg16L1 is necessary for decidualization, implantation, and overall fertility in mice. Furthermore, considering its requirement for human endometrial decidualization, these data suggest Atg16L1 may be a potential mediator of implantation success in women.

Circadian gene PER1 senses progesterone signal during human endometrial decidualization.

Progesterone is an important hormone for female reproduction, however, how the fluctuation of progesterone acts upon reproductive processes remains largely unknown. Mounting evidence indicates a pivotal role of the circadian clock in sensing hormone dynamics for homeostatic regulation of physiological functions. Therefore, we sought to determine whether clock genes respond to progesterone signaling in female reproductive system. In this study, we tested the hypothesis that the circadian system could respond to progesterone signaling during human endometrial decidual transformation. The expression of the circadian gene PER1 increased immediately and remained elevated during human endometrial decidualization. The progesterone receptor activated PER1 transcription by directly binding to its promoter from the onset of the stromal proliferation-differentiation transition. PER1 knockout significantly downregulated the expression of some PGR target genes, and attenuated human endometrial decidual transformation by expediting FOXO1 protein degradation. In conclusion, progesterone could control the female reproductive process through sustained feedback from the circadian gene PER1, which is probably involved to P4-PR signaling responsiveness in the initiation and maintenance of decidualization.

Granulocyte colony stimulating factor (GCSF) treatment augments human endometrial decidualization: mechanism of a therapeutic effect

Granulocyte colony stimulating factor (GCSF) treatment augments human endometrial decidualization: mechanism of a therapeutic effect

Increased expression of integrin-linked kinase during decidualization regulates the morphological transformation of endometrial stromal cells

To study the impact of integrin-linked kinase (ILK) in endometrial stromal cells (ESCs) during decidualization. Laboratory study with the use of human endometrium. University hospital. Fertile reproductive-age women who had not received hormonal treatment for 3months before tissue collection. Endometrium tissue collection, invitro decidualization of isolated ESCs, and small interfering (si) RNA transfection. Immunohistochemistry, ELISA, Western blot analysis, methylthiazolyl tetrazolium assay, and immunofluorescence staining. Invivo expression of ILK is significantly increased in distended-fusiform stromal cells of late secretory endometrium and in cobblestone-shaped decidual cells of early pregnancy. During invitro decidualization for up to 8days, confluent cultures of isolated ESCs consistently displayed increased ILK expression and morphologic transformation from fibroblast-like to polygonal cells. Subsequent ILK knockdown by siRNA transfection reversed this transformation, accompanied by decreased phosphorylation of glycogen synthase kinase (GSK) 3β and decreased viable cell numbers. Immunofluorescence staining of the decidualized ESCs demonstrated linkage of increased levels of ILK at the tips of the fan-shaped organization of actin stress fibers located in the submembranous area, which expanded the decidual cells into a typical polygonal appearance. Knock-down of ILK abrogated the polymerization and organization of actin fibers, which reverted the cells to their undecidualized morphology. During human endometrial decidualization, ILK is essential for morphologic transformation of ESCs through organization of the actin cytoskeleton; it may also function through subsequent GSK3β signaling, which requires further studies.

Roles of Estrogen Receptor-α and the Coactivator MED1 During Human Endometrial Decidualization.

The steroid hormones 17β-estradiol and progesterone are critical regulators of endometrial stromal cell differentiation, known as decidualization, which is a prerequisite for successful establishment of pregnancy. The present study using primary human endometrial stromal cells (HESCs) addressed the role of estrogen receptor-α (ESR1) in decidualization. Knockdown of ESR1 transcripts by RNA interference led to a marked reduction in decidualization of HESCs. Gene expression profiling at an early stage of decidualization indicated that ESR1 negatively regulates several cell cycle regulatory factors, thereby suppressing the proliferation of HESCs as these cells enter the differentiation program. ESR1 also controls the expression of WNT4, FOXO1, and progesterone receptor (PGR), well-known mediators of decidualization. Whereas ESR1 knockdown strongly inhibited the expression of FOXO1 and WNT4 transcripts within 24 hours of the initiation of decidualization, PGR expression remained unaffected at this early time point. Our study also revealed a major role of cAMP signaling in influencing the function of ESR1 during decidualization. Using a proteomic approach, we discovered that the cAMP-dependent protein kinase A (PKA) phosphorylates Mediator 1 (MED1), a subunit of the mediator coactivator complex, during HESC differentiation. Using immunoprecipitation, we demonstrated that PKA-phosphorylated MED1 interacts with ESR1. The PKA-dependent phosphorylation of MED1 was also correlated with its enhanced recruitment to estrogen-responsive elements in the WNT4 gene. Knockdown of MED1 transcripts impaired the expression of ESR1-induced WNT4 and FOXO1 transcripts and blocked decidualization. Based on these findings, we conclude that modulation of ESR1-MED1 interactions by cAMP signaling plays a critical role in human decidualization.

Molecular Mechanisms of Human Endometrial Decidualization Activated by Cyclic Adenosine Monophosphate Signaling Pathways

Abstract During the menstrual cycle, the human endometrium undergoes dramatic changes, including cyclical proliferation, differentiation and menstruation, under the stringent control of ovarian steroid hormones. Endometrial stromal cells (ESCs) spontaneously differentiate into decidual cells in response to increased progesterone and intracellular cyclic adenosine monophosphate (cAMP) levels during the mid-secretory phase of the cycle. This process, termed decidualization, is strictly defined as the morphological and biochemical reprograming of the ESCs and is required for successful pregnancy. In pregnancy, the decidua functions as a critical barrier between the mother and fetus by modulating trophoblast invasion and the immune response. We recently demonstrated the involvement of a novel cAMP target, an exchange protein directly activated by cAMP (EPAC), in the process of decidualization. This review presents the molecular mechanisms of decidualization regulated by progesterone and the cAMP signaling pat...

FoxM1 Directs STAT3 Expression Essential for Human Endometrial Stromal Decidualization.

Human endometrium decidualization, which involves endometrial stromal proliferation and differentiation, is a prerequisite for embryo implantation, thus successful pregnancy. The Forkhead Box M1 (FoxM1), previously known as HNF-3, HFH-11, MPP2, Win, and Trident, is a transcriptional factor that plays crucial roles in cell proliferation and cell cycle progression. However, the molecular mechanism of FoxM1 during human endometrial decidualization remains unexplored. In this study, we first found FoxM1 is dynamically expressed in human endometrium during menstrual cycle. Employing a human endometrial stromal cell (HESC) line, we then demonstrated that FoxM1 inhibition downregulates cyclin B1 expression, delaying G2/M phase transition during HESC proliferation. Additionally, loss of FoxM1 expression blocks the differentiation of HESCs in response to estrogen, progesterone, and dbcAMP. Applying chromatin immunoprecipitation (ChIP) technique and luciferase assay, we further approved that FoxM1 can transcriptionally active signal transducer and activator of transcription 3 (STAT3), ensuring normal HESC differentiation. Besides enriching our knowledge on molecular basis underlying stromal decidualization, these findings help to shed light on the potential molecular causes for the endometrial disorders in humans.

Roles of progesterone receptor A and B isoforms during human endometrial decidualization.

Progesterone, acting through the progesterone receptors (PGRs), is one of the most critical regulators of endometrial differentiation, known as decidualization, which is a key step toward the establishment of pregnancy. Yet a long-standing unresolved issue in uterine biology is the precise roles played by the major PGR isoforms, PGR-A and PGR-B, during decidualization in the human. Our approach, expressing PGR-A and PGR-B individually after silencing endogenous PGRs in human endometrial stromal cells (HESCs), enabled the analysis of the roles of these isoforms separately as well as jointly. Chromatin immunoprecipitation-sequencing in combination with gene expression profiling revealed that PGR-B controls a substantially larger cistrome and transcriptome than PGR-A during HESC differentiation. Interestingly, PGR-B directly regulates the expression of PGR-A. De novo motif analysis indicated that, although the 2 isoforms bind to the same DNA sequence motif, there are both common and unique neighboring motifs where other transcription factors, such as FOSL1/2, JUN, C/EBPβ, and STAT3, bind and dictate the transcriptional activities of these isoforms. We found that PGR-A and PGR-B regulate overlapping as well as distinct sets of genes, many of which are known to be critical for decidualization and establishment of pregnancy. When PGR-A and PGR-B were coexpressed during HESC differentiation, PGR-B played a predominant role, although both isoforms influenced each other's transcriptional activity. This study revealed the gene networks that operate downstream of each PGR isoform to mediate critical functions, such as regulation of the cell cycle, angiogenesis, lysosomal activation, insulin receptor signaling, and apoptosis, during decidualization in the human.

The expression of WNT/β-catenin pathway factors on endometrium cells of in-vitro model of embryo implantation

ObjectiveTo explore the role of Wnt/β-catenin pathway in the procedure of embryo implantation.DesignProspective experimental study.Materials and MethodsAfter established in-vitro model of embryo implantation by co-culturing human blastocysts with human endometrial decidualization cell monolayers, β-catenin was detected by immunofluorescence analysis on endometrial cells at pre-, peri- and post-implantation stages. β-catenin,Wnt4,Frz6 were detected by real time fluorescent quantitative PCR analysis on endometrial cells at pre-,peri- and post-implantation stages.ResultsThe blastocysts adhered to the decidualization cell layer within 5-10h, attached and invasion into the decidualization cell layer after 48h of coculture. The expression of β-catenin protein was observed on endometrial cells and mainly located at the cellular membrane at pre-implantation stage; more β-catenin protein was observed at the membrane and cytoplasm on decidualization cells at peri-implantation stage; the expression of β-catenin was detected in cellular nucleus after 48 h of implantation. The expression of β-catenin,Wnt4,Frz6 mRNA was significantly increased on decidualization cells at peri -implantation stage compared with pre-implantation stage (P<0.05), and significantly increased at post-implantation stages compared with peri-implantation stage (P<0.05).ConclusionHuman blastocysts co-cultured with human endometrial decidualization cell monolayers could be used to study the mechanism of embryo implantation. Wnt/β-catenin pathway was activated and played an important role in the procedure of embryo implantation. ObjectiveTo explore the role of Wnt/β-catenin pathway in the procedure of embryo implantation. To explore the role of Wnt/β-catenin pathway in the procedure of embryo implantation. DesignProspective experimental study. Prospective experimental study. Materials and MethodsAfter established in-vitro model of embryo implantation by co-culturing human blastocysts with human endometrial decidualization cell monolayers, β-catenin was detected by immunofluorescence analysis on endometrial cells at pre-, peri- and post-implantation stages. β-catenin,Wnt4,Frz6 were detected by real time fluorescent quantitative PCR analysis on endometrial cells at pre-,peri- and post-implantation stages. After established in-vitro model of embryo implantation by co-culturing human blastocysts with human endometrial decidualization cell monolayers, β-catenin was detected by immunofluorescence analysis on endometrial cells at pre-, peri- and post-implantation stages. β-catenin,Wnt4,Frz6 were detected by real time fluorescent quantitative PCR analysis on endometrial cells at pre-,peri- and post-implantation stages. ResultsThe blastocysts adhered to the decidualization cell layer within 5-10h, attached and invasion into the decidualization cell layer after 48h of coculture. The expression of β-catenin protein was observed on endometrial cells and mainly located at the cellular membrane at pre-implantation stage; more β-catenin protein was observed at the membrane and cytoplasm on decidualization cells at peri-implantation stage; the expression of β-catenin was detected in cellular nucleus after 48 h of implantation. The expression of β-catenin,Wnt4,Frz6 mRNA was significantly increased on decidualization cells at peri -implantation stage compared with pre-implantation stage (P<0.05), and significantly increased at post-implantation stages compared with peri-implantation stage (P<0.05). The blastocysts adhered to the decidualization cell layer within 5-10h, attached and invasion into the decidualization cell layer after 48h of coculture. The expression of β-catenin protein was observed on endometrial cells and mainly located at the cellular membrane at pre-implantation stage; more β-catenin protein was observed at the membrane and cytoplasm on decidualization cells at peri-implantation stage; the expression of β-catenin was detected in cellular nucleus after 48 h of implantation. The expression of β-catenin,Wnt4,Frz6 mRNA was significantly increased on decidualization cells at peri -implantation stage compared with pre-implantation stage (P<0.05), and significantly increased at post-implantation stages compared with peri-implantation stage (P<0.05). ConclusionHuman blastocysts co-cultured with human endometrial decidualization cell monolayers could be used to study the mechanism of embryo implantation. Wnt/β-catenin pathway was activated and played an important role in the procedure of embryo implantation. Human blastocysts co-cultured with human endometrial decidualization cell monolayers could be used to study the mechanism of embryo implantation. Wnt/β-catenin pathway was activated and played an important role in the procedure of embryo implantation.