High incidence of decidualization failure in infertile women.

Purpose: Decidualization is an important event for embryo implantation and successful pregnancy. Impaired decidualization leads to implantation failure and miscarriage. However, it is unclear how often decidualization failure occurs in infertile women. By analyzing the endometrium at late-secretory phase, we investigated the incidence and pathogenesis of decidualization failure among infertile women. Methods: Endometrial dating was performed on the endometria obtained in the late-secretory phase from 33 infertile women. Endometrial dating of more than 2 days delay was taken as an indication of decidualization failure. The expression of essential transcription factors for decidualization (FOXO1, WT1, and C/EBPß) was examined by immunohistochemistry. Results: Among 32 cases, 20 cases (62.5%) showed decidualization failure. These patients tended to have a history of more frequent miscarriages than those without decidualization failure. The percentage of cells that immunostained positive for the expression of three transcription factors was significantly lower in the patients with decidualization failure than in those without decidualization failure. Serum progesterone levels measured in the mid- and late-secretory phase were not significantly different between the cases with and without decidualization failure. Conclusions: The incidence of decidualization failure is high in infertile women.

Transcriptional coactivator PGC-1α contributes to decidualization by forming a histone-modifying complex with C/EBPß and p300.

We previously reported that CCAAT/enhancer-binding protein beta (C/EBPß) is the pioneer factor inducing transcription enhancer mark H3K27 acetylation (H3K27ac) in the promoter and enhancer regions of genes encoding insulin-like growth factor-binding protein-1 (IGFBP-1) and prolactin (PRL) and that this contributes to decidualization of human endometrial stromal cells (ESCs). Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α; PPARGC1A) is a transcriptional coactivator known to regulate H3K27ac. However, although PGC-1α is expressed in ESCs, the potential role of PGC-1α in mediating decidualization is unclear. Here, we investigated the involvement of PGC-1α in the regulation of decidualization. We incubated ESCs with cAMP to induce decidualization and knocked down PPARGC1A to inhibit cAMP-induced expression of IGFBP-1 and PRL. We found cAMP increased the recruitment of PGC-1α and p300 to C/EBPß-binding sites in the promoter and enhancer regions of IGFBP-1 and PRL, corresponding with increases in H3K27ac. Moreover, PGC-1α knockdown inhibited these increases, suggesting PGC-1α forms a histone-modifying complex with C/EBPß and p300 at these regions. To further investigate the regulation of PGC-1α, we focused on C/EBPß upstream of PGC-1α. We found cAMP increased C/EBPß recruitment to the novel enhancer regions of PPARGC1A. Deletion of these enhancers decreased PGC-1α expression, indicating that C/EBPß upregulates PGC-1α expression by binding to novel enhancer regions. In conclusion, PGC-1α is upregulated by C/EBPß recruitment to novel enhancers and contributes to decidualization by forming a histone-modifying complex with C/EBPß and p300, thereby inducing epigenomic changes in the promoters and enhancers of IGFBP-1 and PRL.

The essential glucose transporter GLUT1 is epigenetically upregulated by C/EBPß and WT1 during decidualization of the endometrium.

Human endometrial stromal cells (ESCs) differentiate into decidual cells by the action of progesterone, which is essential for implantation and maintenance of pregnancy. We previously reported that glucose uptake by human ESCs increases during decidualization and that glucose is indispensable for decidualization. Although glucose transporter 1 (GLUT1) is upregulated during decidualization, it remains unclear whether it is involved in glucose uptake. Here, we attempted to determine the role of GLUT1 during decidualization as well as the factors underlying its upregulation. ESCs were incubated with cAMP to induce decidualization. Knockdown of GLUT1 suppressed cAMP-increased glucose uptake and the expressions of specific markers of decidualization, IGF-binding protein-1 (IGFBP-1), and prolactin (PRL). To investigate the regulation of GLUT1 expression, we focused on CCAAT enhancer-binding protein ß (C/EBPß) and Wilms' tumor 1 (WT1) as the upstream transcription factors regulating GLUT1 expression. Knockdown of either C/EBPß or WT1 suppressed cAMP-increased GLUT1 expression and glucose uptake. cAMP treatment also increased the recruitment of C/EBPß and WT1 to the GLUT1 promoter region. Interestingly, cAMP increased the H3K27 acetylation (H3K27ac) and p300 recruitment in the GLUT1 promoter region. Knockdown of C/EBPß or WT1 inhibited these events, indicating that both C/EBPß and WT1 contribute to the increase of H3K27ac by recruiting p300 to the GLUT1 promoter region during decidualization. These findings indicate that GLUT1 is involved in glucose uptake in ESCs during decidualization, thus facilitating the establishment of pregnancy.

Effects of Melatonin on the Transcriptome of Human Granulosa Cells, Fertilization and Blastocyst Formation.

Melatonin is a promising reagent that can improve assisted reproductive technology (ART) outcomes in infertility patients. However, melatonin is not effective for all infertile patients, and it remains unclear for which patients melatonin would be effective. This study examined the effects of melatonin on ART outcomes and examined its mechanisms. Melatonin increased the fertilization rate in patients whose fertilization rates in the previous cycle were less than 50%, but not in patients whose fertilization rates were more than 50% in the previous cycle. Melatonin increased the blastocyst formation rate in patients whose embryo development rates in the previous cycle were less than 50%, but not in patients whose embryo development rates were more than 50% in the previous cycle. To clarify its mechanisms, transcriptome changes by melatonin treatment in granulosa cells (GCs) of the patients were examined by RNA-sequence. Melatonin treatment altered the transcriptomes of GCs of patients with poor ART outcomes so that they were similar to the transcriptomes of patients with good ART outcomes. The altered genes were associated with the inhibition of cell death and T-cell activity, and the activation of steroidogenesis and angiogenesis. Melatonin treatment was effective for patients with poor fertilization rates and poor embryo development rates in the previous ART cycle. Melatonin alters the GCs transcriptome and, thus, their functions, and this could improve the oocyte quality, leading to good ART outcomes.

Wilms tumor 1 regulates lipid accumulation in human endometrial stromal cells during decidualization.

We previously reported that the transcription factor Wilms tumor 1 (WT1) regulates the expression of insulin-like growth factor-binding protein-1 (IGFBP-1) and prolactin (PRL) during decidualization of human endometrial stromal cells (ESCs). However, other roles of WT1 in decidualization remain to be fully clarified. Here, we investigated how WT1 regulates the physiological functions of human ESCs during decidualization. We incubated ESCs isolated from proliferative-phase endometrium with cAMP to induce decidualization, knocked down WT1 with siRNA, and generated three types of treatments (nontreated cells, cAMP-treated cells, and cAMP-treated + WT1-knockdown cells). To identify WT1-regulated genes, we used gene microarrays and compared the transcriptome data obtained among these three treatments. We observed that WT1 up-regulates 121 genes during decidualization, including several genes involved in lipid transport. The WT1 knockdown inhibited lipid accumulation (LA) in the cAMP-induced ESCs. To examine the mechanisms by which WT1 regulates LA, we focused on very low-density lipoprotein receptor (VLDLR), which is involved in lipoprotein uptake. We found that cAMP up-regulates VLDLR and that the WT1 knockdown inhibits it. Results of ChIP assays revealed that cAMP increases the recruitment of WT1 to the promoter region of the VLDLR gene, indicating that WT1 regulates VLDLR expression. Moreover, VLDLR knockdown inhibited cAMP-induced LA, and VLDLR overexpression reverted the suppression of LA caused by the WT1 knockdown. Taken together, our results indicate that WT1 enhances lipid storage by up-regulating VLDLR expression in human ESCs during decidualization.

Relationship between follicular size and developmental capacity of oocytes under controlled ovarian hyperstimulation in assisted reproductive technologies.

PURPOSE: We investigate the relationships between oocyte developmental capacity and follicular size of its origin in Japanese women: those undergoing conventional IVF (cIVF) and ICSI, respectively. METHODS: A total of 3377 follicles were punctured separately and were classified into three groups (large, medium, and small) by their diameters. A total of 1482 retrieved oocytes were individually cultured and received cIVF or ICSI. The oocytes receiving ICSI were denuded and the number of mature (MII) oocytes was counted. RESULTS: The oocyte retrieval rates and the proportion of MII oocytes were significantly lower in small follicles than in large follicles. Under cIVF, the fertilization rate was significantly lower in oocytes from small follicles than large follicles. Under ICSI, the fertilization rate for MII oocytes was not significantly related to follicular size. Follicular size was not significantly related to the development potential to blastocyst and pregnancy rate for either the cIVF oocytes or the ICSI oocytes. CONCLUSIONS: Although the fertilization rate by cIVF is low in oocytes from small follicles due to the lower proportion of mature oocytes, their development potential is comparable to that of oocytes from larger follicles if they could be fertilized. Under ICSI using mature oocytes, their development potential is not related to follicular size.

Differential gene expression in decidualized human endometrial stromal cells induced by different stimuli.

Decidualization can be induced by culturing human endometrial stromal cells (ESCs) with several decidualization stimuli, such as cAMP, medroxyprogesterone acetate (MPA) or Estradiol (E2). However, it has been unclear how decidualized cells induced by different stimuli are different. We compared transcriptomes and cellular functions of decidualized ESCs induced by different stimuli (MPA, E2 + MPA, cAMP, and cAMP + MPA). We also investigated which decidualization stimulus induces a closer in vivo decidualization. Differentially expressed genes (DEGs) and altered cellular functions by each decidualization stimuli were identified by RNA-sequence and gene-ontology analysis. DEGs was about two times higher for stimuli that use cAMP (cAMP and cAMP + MPA) than for stimuli that did not use cAMP (MPA and E2 + MPA). cAMP-using stimuli altered the cellular functions including angiogenesis, inflammation, immune system, and embryo implantation whereas MPA-using stimuli (MPA, E2 + MPA, and cAMP + MPA) altered the cellular functions associated with insulin signaling. A public single-cell RNA-sequence data of the human endometrium was utilized to analyze in vivo decidualization. The altered cellular functions by in vivo decidualization were close to those observed by cAMP + MPA-induced decidualization. In conclusion, decidualized cells induced by different stimuli have different transcriptome and cellular functions. cAMP + MPA may induce a decidualization most closely to in vivo decidualization.

Long-term melatonin treatment attenuates body weight gain with aging in female mice.

Women usually experience body weight gain with aging, which can put them at risk for many chronic diseases. Previous studies indicated that melatonin treatment attenuates body weight gain and abdominal fat deposition in several male animals. However, it is unclear whether melatonin affects female animals in the same way. This study investigated whether long-term melatonin treatment can attenuate body weight gain with aging and, if it does, what the mechanism is. Ten-week-old female ICR mice were given melatonin-containing water (100 µg/mL) or only water until 43 weeks. Melatonin treatment significantly attenuated body weight gain at 23 weeks (control; 57.2 ± 2.0 g vs melatonin; 44.4 ± 3.1 g), 33 weeks (control; 65.4 ± 2.6 g vs melatonin; 52.2 ± 4.2 g) and 43 weeks (control; 66.1 ± 3.2 g vs melatonin; 54.4 ± 2.5 g) without decreasing the amount of food intake. Micro-CT analyses showed that melatonin significantly decreased the deposition of visceral and s.c. fat. These results suggested that melatonin attenuates body weight gain by inhibiting abdominal fat deposition. Metabolome analysis of the liver revealed that melatonin treatment induced a drastic change in the metabolome with the downregulation of 149 metabolites, including the metabolites of glucose and amino acids. Citrate, which serves as a source of de novo lipogenesis, was one of the downregulated metabolites. These results show that long-term melatonin treatment induces drastic changes in metabolism and attenuates body weight gain and fat deposition with aging in female mice.

Integrated Analysis of Transcriptome and Histone Modifications in Granulosa Cells During Ovulation in Female Mice.

The ovulatory luteinizing hormone (LH) surge induces rapid changes of gene expression and cellular functions in granulosa cells (GCs) undergoing luteinization. However, it remains unclear how the changes in genome-wide gene expression are regulated. H3K4me3 histone modifications are involved in the rapid alteration of gene expression. In this study, we investigated genome-wide changes of transcriptome and H3K4me3 status in mouse GCs undergoing luteinization. GCs were obtained from mice treated with equine chorionic gonadotropin (hCG) before, 4 hours, and 12 hours after human chorionic gonadotropin injection. RNA-sequencing identified a number of upregulated and downregulated genes, which could be classified into 8 patterns according to the time-course changes of gene expression. Many genes were transiently upregulated or downregulated at 4 hours after hCG stimulation. Gene Ontology terms associated with these genes included steroidogenesis, ovulation, cumulus-oocyte complex (COC) expansion, angiogenesis, immune system, reactive oxygen species (ROS) metabolism, inflammatory response, metabolism, and autophagy. The cellular functions of DNA repair and cell growth were newly identified as being activated during ovulation. Chromatin immunoprecipitation-sequencing revealed a genome-wide and rapid change in H3K4me3 during ovulation. Integration of transcriptome and H3K4me3 data identified many H3K4me3-associated genes that are involved in steroidogenesis, ovulation, COC expansion, angiogenesis, inflammatory response, immune system, ROS metabolism, lipid and glucose metabolism, autophagy, and regulation of cell size. The present results suggest that genome-wide changes in H3K4me3 after the LH surge are associated with rapid changes in gene expression in GCs, which enables GCs to acquire a lot of cellular functions within a short time that are required for ovulation and luteinization.

Transcription factor C/EBPß induces genome-wide H3K27ac and upregulates gene expression during decidualization of human endometrial stromal cells.

We previously reported that H3K27 acetylation (H3K27ac) increases throughout the genome during decidualization of human endometrial stromal cells (ESCs). However, its mechanisms have not been clarified. We also reported that C/EBPß acts as a pioneer factor initiating chromatin remodeling by increasing H3K27ac of IGFBP-1 and PRL promoters. Therefore, C/EBPß may be involved in the genome-wide increase of H3K27ac during decidualization. In this study, we investigated whether C/EBPß causes genome-wide H3K27ac modifications and regulates gene expressions during decidualization. cAMP was used to induce decidualization. Three types of cells (control cells, cAMP-treated cells, and cAMP-treated + C/EBPß-knockdowned cells by siRNA) were generated. Of 4190 genes that were upregulated by cAMP, C/EBPß knockdown inhibited these upregulation in 2239 genes (53.4%), indicating that they are under the regulation of C/EBPß. cAMP increased H3K27ac in 1272 of the 2239 genes. C/EBPß knockdown abolished the increase of H3K27ac in almost all genes (1263 genes, 99.3%), suggesting that C/EBPß can upregulate gene expression by increasing H3K27ac. To investigate how C/EBPß regulates H3K27ac throughout the genome, we tested the hypothesis that C/EBPß binds to its binding regions and recruits cofactors with histone acetyltransferase activities. To do this, we collated our ChIP-sequence data with public ChIP-sequence database of transcription factors, and found that p300 is the most likely cofactor that binds to the H3K27ac-increased-regions with C/EBPß. ChIP-qPCR of several genes confirmed that C/EBPß binds to the target regions, recruits p300, and increases H3K27ac. Our genome-wide analysis revealed that C/EBPß induces H3K27ac throughout the genome and upregulates gene expressions during decidualization by recruiting p300 to the promoters.

An Integrated Genomic Approach Identifies HOXC8 as an Upstream Regulator in Ovarian Endometrioma.

PURPOSE: To identify the upstream regulators (URs) involved in the onset and pathogenesis of ovarian endometrioma. METHODS: Recently, a method called Significance-based Modules Integrating the Transcriptome and Epigenome (SMITE) that uses transcriptome data in combination with publicly available data for identifying URs of cellular processes has been developed. Here, we used SMITE with transcriptome data from ovarian endometrioma stromal cells (ovESCs) and eutopic endometrium stromal cells (euESCs) in combination with publicly available gene regulatory network data. To confirm the URs identified by SMITE, we developed a Boolean network simulation to see if correcting aberrant expressions of the identified genes could restore the entire gene expression profile of ovESCs to a profile similar to that of euESCs. We then established euESCs overexpressing the identified gene and characterized them by cell function assays and transcriptome analysis. RESULTS: SMITE identified 12 potential URs in ovarian endometrioma that were confirmed by the Boolean simulation. One of the URs, HOXC8, was confirmed to be overexpressed in ovESCs. HOXC8 overexpression significantly enhanced cell proliferation, migration, adhesion, and fibrotic activities, and altered expression statuses of the genes involved in transforming growth factor (TGF)-ß signaling. HOXC8 overexpression also increased the expression levels of phosphorylated SMAD2/SMAD3. The increased adhesion and fibrosis activities by HOXC8 were significantly inhibited by E-616452, a selective inhibitor of TGF-ß receptor type I kinases. MAIN CONCLUSIONS: Integrated genomic approaches identified HOXC8 as an UR in ovarian endometrioma. The pathological features of ovarian endometrioma including cell proliferation, adhesion, and fibrosis were induced by HOXC8 and its subsequent activation of TGF-ß signaling.