Down-regulation of S100A11, a calcium-binding protein, in human endometrium may cause reproductive failure

Rapid generation of functional nanovesicles from human trophectodermal cells for embryo attachment and outgrowth

Extracellular vesicles (EVs) are important mediators of embryo attachment and outgrowth critical for successful implantation. While EVs have garnered immense interest in their therapeutic potential in assisted reproductive technology by improving implantation success, their large-scale generation remains a major challenge. Here, we report a rapid and scalable production of nanovesicles (NVs) directly from human trophectoderm cells (hTSCs) via serial mechanical extrusion of cells; these NVs can be generated in approximately 6 h with a 20-fold higher yield than EVs isolated from culture medium of the same number of cells. NVs display similar biophysical traits (morphologically intact, spherical, 90-130 nm) to EVs, and are laden with hallmark players of implantation that include cell-matrix adhesion and extracellular matrix organisation proteins (ITGA2/V, ITGB1, MFGE8) and antioxidative regulators (PRDX1, SOD2). Functionally, NVs are readily taken up by low-receptive endometrial HEC1A cells and reprogram their proteome towards a receptive phenotype that support hTSC spheroid attachment. Moreover, a single dose treatment with NVs significantly enhanced adhesion and spreading of mouse embryo trophoblast on fibronectin matrix. Thus, we demonstrate the functional potential of NVs in enhancing embryo implantation and highlight their rapid and scalable generation, amenable to clinical utility.

Endometrial proteomic profile of patients with repeated implantation failure

Introduction

Successful embryo implantation, is the initiating step of pregnancy, relies on not only the high quality of the embryo but also the synergistic development of a healthy endometrium. Characterization and identification of biomarkers for the receptive endometrium is an effective method for increasing the probability of successful embryo implantation.

Methods

Endometrial tissues from 22 women with a history of recurrent implantation failure (RIF) and 19 fertile controls were collected using biopsy catheters on 7-9 days after the peak of luteinizing hormone. Differentially expressed proteins (DEPs) were identified in six patients with RIF and six fertile controls using isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics analysis.

Results

Two hundred and sixty-three DEPs, including proteins with multiple bioactivities, such as protein translation, mitochondrial function, oxidoreductase activity, fatty acid and amino acid metabolism, were identified from iTRAQ. Four potential biomarkers for receptive endometrium named tubulin polymerization-promoting protein family member 3 TPPP3, S100 Calcium Binding Protein A13 (S100A13), 17b-hydroxysteroid dehydrogenase 2 (HSD17B2), and alpha-2-glycoprotein 1, zinc binding (AZGP1) were further verified using ProteinSimple Wes and immunohistochemical staining in all included samples (n=22 for RIF and n=19 for controls). Of the four proteins, the protein levels of TPPP3 and HSD17B2 were significantly downregulated in the endometrium of patients with RIF.

Discussion

Poor endometrial receptivity is considered the main reason for the decrease in pregnancy success rates in patients suffering from RIF. iTRAQ techniques based on isotope markers can identify and quantify low abundance proteomics, and may be suitable for identifying differentially expressed proteins in RIF. This study provides novel evidence that TPPP3 and HSD17B2 may be effective targets for the diagnosis and treatment of non-receptive endometrium and RIF.

Lysosomal Ion Channels and Lysosome-Organelle Interactions

Intracellular organelles exchange their luminal contents with each other via both vesicular and non-vesicular mechanisms. By forming membrane contact sites (MCSs) with ER and mitochondria, lysosomes mediate bidirectional transport of metabolites and ions between lysosomes and organelles that regulate lysosomal physiology, movement, membrane remodeling, and membrane repair. In this chapter, we will first summarize the current knowledge of lysosomal ion channels and then discuss the molecular and physiological mechanisms that regulate lysosome-organelle MCS formation and dynamics. We will also discuss the roles of lysosome-ER and lysosome-mitochondria MCSs in signal transduction, lipid transport, Ca ²⁺ transfer, membrane trafficking, and membrane repair, as well as their roles in lysosome-related pathologies.

ER as master regulator of membrane trafficking and organelle function

The endoplasmic reticulum (ER), which occupies a large portion of the cytoplasm, is the cell’s main site for the biosynthesis of lipids and carbohydrate conjugates, and it is essential for folding, assembly, and biosynthetic transport of secreted proteins and integral membrane proteins. The discovery of abundant membrane contact sites (MCSs) between the ER and other membrane compartments has revealed that, in addition to its biosynthetic and secretory functions, the ER plays key roles in the regulation of organelle dynamics and functions. In this review, we will discuss how the ER regulates endosomes, lysosomes, autophagosomes, mitochondria, peroxisomes, and the Golgi apparatus via MCSs. Such regulation occurs via lipid and Ca2+ transfer and also via control of in trans dephosphorylation reactions and organelle motility, positioning, fusion, and fission. The diverse controls of other organelles via MCSs manifest the ER as master regulator of organelle biology.

Intrauterine hyperglycemia impairs endometrial receptivity via up-regulating SGK1 in diabetes

Diabetes is a complex metabolic disorder which can adversely affect reproductive function. SGK1 is found to be up-regulated in multiple tissues of diabetic patients. However, the effects of diabetes on endometrial SGK1 expression and endometrial receptivity remain unknown. In this study, we established a streptozotocin-induced diabetic mouse model and observed reduced implantation sites, retarded development of pinopodes, increased SGK1, and aberrant expression of LIF and MUC1 in the endometrial epithelium. We injected the uterine lumen of normal mice with high-glucose solution and cultured endometrial cells in high-glucose medium to mimic intrauterine hyperglycemia. Both studies provided compelling evidence that hyperglycemia could lead to diminished embryo implantation and dysregulated SGK1, LIF and MUC1. Additionally, through over-expression of SGK1 in vivo and in vitro, we found that enhanced SGK1 also decreased LIF expression, increased MUC1 expression, and attenuated embryo implantation rate. We further identified that hyperglycemia-activated SMAD2/3 might be responsible for the enhancement of SGK1 and verified directly the interaction between SMAD3 and corresponding SMAD binding elements within SGK1 promoter. Taken together, our study confirmed the association between diabetes-related hyperglycemia and endometrial receptivity defects. Hyperglycemia-induced SGK1 has a tremendous role in this pathological process, rendering it as an attractive therapeutic target for diabetes-related reproductive disorders.

Role of Nucleolin in Endometrial Precancerous Hyperplasia and Carcinogenesis: Ex Vivo and In Silico Study

Endometrial cancer (EC) is the most common gynaecological malignancy. Nucleolin (NCL) is involved in rDNA transcription, cell proliferation, and apoptosis, with high expression associated with worse overall survival (OS) in other adenocarcinomas. Our aims were to assess NCL gene and protein expression and explore the differential expression of NCL-associated genes (NAGs) in endometrial carcinogenesis. Endometrial samples were obtained from 157 women to include healthy, hyperplastic (EH), EC, and metastatic groups. RT-qPCR and immunohistochemistry were employed to assess NCL gene and protein levels. In silico analysis of NAGs in TCGA and GEO datasets was performed, with the prognostic value determined via Human Protein Atlas. NCL mRNA level of EC was lower than in healthy post-menopausal endometrium (p < 0.01). EH samples had lower NCL immuno-expression scores than healthy pre-menopausal (p < 0.001), benign post-menopausal (p < 0.01), and EC (p < 0.0001) samples. Metastatic lesions demonstrated higher NCL quick scores than primary tissue (p = 0.04). Higher NCL Immuno quick scores carried a worse OS in high-grade EC (p = 0.01). Interrogating Uterine Corpus Endometrial Carcinoma (TCGA-UCEC) and Uterine Carcinosarcoma (TCGA-UCS) cohorts revealed NCL to be the most highly upregulated gene in carcinosarcoma, with S100A11, LMNB2, RERG, E2F1 and CCNA2 representing key dysregulated NAGs in EC. Since NCL is implicated in transforming hyperplastic glands into cancer, with further involvement in metastasis, it is suggested to be a promising target for better-informed diagnosis, risk stratification, and management of EC.

The Eutopic Endometrium Proteome in Endometriosis Reveals Candidate Markers and Molecular Mechanisms of Physiopathology

Endometriosis is a common chronic gynaecological disease causing various symptoms, such as infertility and chronic pain. The gold standard for its diagnosis is still laparoscopy and the biopsy of endometriotic lesions. Here, we aimed to compare the eutopic endometrium from women with or without endometriosis to identify proteins that may be considered as potential biomarker candidates. Eutopic endometrium was collected from patients with endometriosis (n = 4) and women without endometriosis (n = 5) during a laparoscopy surgery during the mid-secretory phase of their menstrual cycle. Total proteins from tissues were extracted and digested before LC-MS-MS analysis. Among the 5301 proteins identified, 543 were differentially expressed and enriched in two specific KEGG pathways: focal adhesion and PI3K/AKT signaling. Integration of our data with a large-scale proteomics dataset allowed us to highlight 11 proteins that share the same trend of dysregulation in eutopic endometrium, regardless of the phase of the menstrual cycle. Our results constitute the first step towards the identification of potential promising endometrial diagnostic biomarkers. They provide new insights into the mechanisms underlying endometriosis and its etiology. Our results await further confirmation on a larger sample cohort.

Phosphate, Calcium, and Vitamin D: Key Regulators of Fetal and Placental Development in Mammals

Normal calcium and bone homeostasis in the adult is virtually fully explained by the interactions of several key regulatory hormones, including parathyroid hormone, 1,25 dihydroxy vitamin D3, fibroblast growth factor-23, calcitonin, and sex steroids (estradiol and testosterone). In utero, bone and mineral metabolism is regulated differently from the adult. During development, it is the placenta and not the fetal kidneys, intestines, or skeleton that is the primary source of minerals for the fetus. The placenta is able to meet the almost inexhaustible needs of the fetus for minerals by actively driving the transport of calcium and phosphorus from the maternal circulation to the growing fetus. These fundamentally important minerals are maintained in the fetal circulation at higher concentrations than those in maternal blood. Maintenance of these inordinately higher fetal levels is necessary for the developing skeleton to accrue sufficient minerals by term. Importantly, in livestock species, prenatal mineralization of the skeleton is crucial for the high levels of offspring activity soon after birth. Calcium is required for mineralization, as well as a plethora of other physiological functions. Placental calcium and phosphate transport are regulated by several mechanisms that are discussed in this review. It is clear that phosphate and calcium metabolism is intimately interrelated and, therefore, placental transport of these minerals cannot be considered in isolation.

S100A11/ANXA2 belongs to a tumour suppressor/oncogene network deregulated early with steatosis and involved in inflammation and hepatocellular carcinoma development

OBJECTIVE

Hepatocellular carcinoma (HCC) development occurs with non-alcoholic fatty liver disease (NAFLD) in the absence of cirrhosis and with an increasing incidence due to the obesity pandemic. Mutations of tumour suppressor (TS) genes and oncogenes (ONC) have been widely characterised in HCC. However, mounting evidence indicates that non-genomic alterations of TS/ONC occur early with NAFLD, thereby potentially promoting hepatocarcinogenesis in an inflammatory/fibrotic context. The aim of this study was to identify and characterise these alterations.

DESIGN

The proteome of steatotic liver tissues from mice spontaneously developing HCC was analysed. Alterations of TSs/ONCs were further investigated in various mouse models of NAFLD/HCC and in human samples. The inflammatory, fibrogenic and oncogenic functions of S100A11 were assessed through in vivo, in vitro and ex-vivo analyses.

RESULTS

A whole set of TSs/ONCs, respectively, downregulated or upregulated was uncovered in mice and human with NAFLD. Alterations of these TSs/ONCs were preserved or even exacerbated in HCC. Among them, overexpression of S100A11 was associated with high-grade HCC and poor prognosis. S100A11 downregulation in vivo significantly restrains the development of inflammation and fibrosis in mice fed a choline/methionine-deficient diet. Finally, in vitro and ex-vivo analyses revealed that S100A11 is a marker of hepatocyte de-differentiation, secreted by cancer cells, and promoting cell proliferation and migration.

CONCLUSION

Cellular stress associated with NAFLD triggers non-genomic alterations of a whole network of TSs/ONCs fostering hepatocarcinogenesis. Among those, overexpression of the oncogenic factor S100A11 promotes inflammation/fibrosis in vivo and is significantly associated with high-grade HCC with poor prognosis.

The endometrial proteomic profile around the time of embryo implantation†

Embryo implantation is an intricate process which requires competent embryo and receptive endometrium. The failure of endometrium to achieve receptivity is a recognized cause of infertility. However, due to multiplicity of events involved, the molecular mechanisms governing endometrial receptivity are still not fully understood. Traditional one-by-one approaches, including western blotting and histochemistry, are insufficient to examine the extensive changes of endometrial proteome. Although genomics and transcriptomics studies have identified several significant genes, the underlying mechanism remains to be uncovered owing to post-transcriptional and post-translational modifications. Proteomic technologies are high throughput in protein identification, and they are now intensively used to identify diagnostic and prognostic markers in the field of reproductive medicine. There is a series of studies analyzing endometrial proteomic profile, which has provided a mechanistic insight into implantation failure. These published studies mainly focused on the difference between pre-receptive and receptive stages of endometrium, as well as on the alternation of endometrial proteomics in women with reproductive failure. Here, we review recent data from proteomic analyses regarding endometrium around the time of embryo implantation and propose possible future research directions.

Identification of Differentially Expressed Gene Transcripts in Porcine Endometrium during Early Stages of Pregnancy

During the early stages of pregnancy, the uterine endometrium undergoes dramatic morphologic and functional changes accompanied with dynamic variation in gene expression. Pregnancy-stage specific differentially expressed gene (DEG)-transcript-probes were investigated and identified by comparing endometrium transcriptome at 9th day (9D), 12th day (12D) and 16th day (16D) of early pregnancy in Polish large-white (PLW) gilts. Endometrium comparisons between 9D-vs-12D, 9D-vs-16D and 12D-vs-16D of early pregnancy identified 6049, 374 and 6034 highly significant DEG-transcript-probes (p < 0.001; >2 FC). GO term enrichment analysis identified commonly shared upregulated endometrial DEG-transcript-probes (p < 0.001; >2 FC), that were regulating the gene functions of anatomic structure development and transport (TG), DNA-binding and methyltransferase activity (ZBTB2), ion-binding and kinase activity (CKM), cell proliferation and apoptosis activity (IL1B). Downregulated DEG-transcript-probes (p < 0.001; >2 FC) were involved in regulating the gene functions of phosphatase activity (PTPN11), TC616413 gene-transcript and Sus-scrofa LOC100525539. Moreover, blastn comparison of microarray-probes sequences against sus-scrofa11 assembly identified commonly shared upregulated endometrial DEG-transcript-probes (E < 0.06; >2 FC), that were regulating the gene functions of reproduction and growth (SELENOP), cytoskeleton organization and kinase activity (CDC42BPA), phosphatase activity (MINPP1), enzyme-binding and cell-population proliferation (VAV3), cancer-susceptibility candidate gene (CASC4), cytoskeletal protein-binding (COBLL1), ion-binding, enzyme regulator activity (ACAP2) Downregulated endometrial DEG-transcript-probes (E < 0.06; >2FC) were involved in regulating the gene functions of signal-transduction (TMEM33), catabolic and metabolic processes (KLHL15). Microarray validation experiment on selected candidate genes showed complementarity to significant endometrial DEG-transcript-probes responsible for the regulation of immune response (IL1B, S100A11), lipid metabolism (FABP3, PPARG), cell-adhesion (ITGAV), angiogenesis (IL1B), intercellular transmission (NMB), cell-adhesion (OPN) and response to stimuli (RBP4) was confirmed by RT-PCR. This study provides a clue that identified pregnancy-stage specific microarray transcript probes could be considered as candidate genes for recognition and establishment of early pregnancy in the pig.

S100 proteins: An emerging cynosure in pregnancy & adverse reproductive outcome

S100 proteins are calcium (Ca²⁺)-binding proteins and these have an important function in progression, manifestation and therapeutic aspects of various inflammatory, metabolic and neurodegenerative disorders. Based on their involvement in intracellular or extracellular regulatory effects, S100 proteins are classified into three subgroups: one subgroup is specialized in exerting only intracellular effects, other performs both intracellular and extracellular functions and the third subgroup members only display extracellular regulatory effects. S100 proteins are expressed particularly in vertebrates and have cell-specific expression. Functionally, S100 proteins act through their surface receptors and regulate cell functions in autocrine or paracrine mode. Receptor for advanced glycation end products (RAGEs) and toll-like receptor 4 are the main surface receptors. S100 proteins participate in the regulation of cellular differentiation, proliferation, apoptosis and inflammation along with Ca²⁺ homeostasis, energy metabolism and cellular migration, and perform the respective functions through their interaction with transcription factors, nucleic acids, enzymes, receptors, cytoskeleton system, etc. Currently, their role in adverse pregnancy outcomes and compromised reproductive health is being explored. These proteins are present in amniotic fluid, endometrium tissue and foetal brain; therefore, it is quite likely that alterations in the expression levels of S100 family members will be affecting the particular function they are involved in and ultimately affecting the pregnancy in adverse manner. The current review discusses about an association of S100 proteins in pregnancy disorders such as endometriosis, intrauterine growth retardation and miscarriage.

Proteomic analysis of the effects of cell culture density on the metastasis of breast cancer cells

Cancer cell progression and proliferation increase cell density, resulting in changes to the tumour site, including the microenvironment. What is not known is if increased cell density influences the aggressiveness of cancer cells, especially their proliferation, migration, and invasion capabilities. In this study, we found that dense cell culture enhances the aggressiveness of the metastatic cancer cell lines, 4T1 and ZR-75-30, by increasing their proliferation, migration, and invasion capabilities. However, a less metastatic cell line, MCF-7, did not show an increase in aggressiveness, following dense cell culture conditions. We conducted a differential proteomic analysis on 4T1 cells cultured under dense or sparse conditions and identified an increase in expression for proteins involved in migration, including focal adhesion, cytoskeletal reorganization, and transendothelial migration. In contrast, 4T1 cells grown under sparse conditions had higher expression levels for proteins involved in metabolism, including lipid and phospholipid binding, lipid and cholesterol transporter activity, and protein binding. These results suggest that the high-density tumour microenvironment can cause a change in cellular behaviour, leading towards more aggressive cancers. SIGNIFICANCE OF THE STUDY: Metastasis of cancer cells is an obstacle to the clinical treatment of cancer. We found that dense cultures made metastatic cancer cells more potent in terms of proliferation, migration, and invasion. The proteomic and bioinformatic analyses provided some valuable clues for further intensive studies about the effects of cell density on cancer cell aggressiveness, which were associated with events such as pre-mRNA splicing and RNA transport, focal adhesion and cytoskeleton reorganization, ribosome biogenesis, and transendothelial migration, or associated with proteins, such as JAM-1 and S100A11. This investigation gives us new perspectives to investigate the metastasis mechanisms related to the microenvironment of tumour sites.

Establishing life is a calcium-dependent TRiP: Transient receptor potential channels in reproduction

Calcium plays a key role in many different steps of the reproduction process, from germ cell maturation to placental development. However, the exact function and regulation of calcium throughout subsequent reproductive events remains rather enigmatic. Successful pregnancy requires the establishment of a complex dialogue between the implanting embryo and the endometrium. On the one hand, endometrial cell will undergo massive changes to support an implanting embryo, including stromal cell decidualization. On the other hand, trophoblast cells from the trophectoderm surrounding the inner cell mass will differentiate and acquire new functions such as hormone secretion, invasion and migration. The need for calcium in the different gestational processes implicates the presence of specialized ion channels to regulate calcium homeostasis. The superfamily of transient receptor potential (TRP) channels is a class of calcium permeable ion channels that is involved in the transformation of extracellular stimuli into the influx of calcium, inducing and coordinating underlying signaling pathways. Although the necessity of calcium throughout reproduction cannot be negated, the expression and functionality of TRP channels throughout gestation remains elusive. This review provides an overview of the current evidence regarding the expression and function of TRP channels in reproduction.

S100P enhances the motility and invasion of human trophoblast cell lines

S100P has been shown to be a marker for carcinogenesis where its expression in solid tumours correlates with metastasis and a poor patient prognosis. This protein's role in any physiological process is, however, unknown. Here we first show that S100P is expressed both in trophoblasts in vivo as well as in some corresponding cell lines in culture. We demonstrate that S100P is predominantly expressed during the early stage of placental formation with its highest expression levels occurring during the first trimester of gestation, particularly in the invading columns and anchoring villi. Using gain or loss of function studies through overexpression or knockdown of S100P expression respectively, our work shows that S100P stimulates both cell motility and cellular invasion in different trophoblastic and first trimester EVT cell lines. Interestingly, cell invasion was seen to be more dramatically affected than cell migration. Our results suggest that S100P may be acting as an important regulator of trophoblast invasion during placentation. This finding sheds new light on a hitherto uncharacterized molecular mechanism which may, in turn, lead to the identification of novel targets that may explain why significant numbers of confirmed human pregnancies suffer complications through poor placental implantation.

Pregnancy-induced changes in metabolome and proteome in ovine uterine flushings

Mass spectrometry (MS) approaches were used herein to identify metabolites and proteins in uterine flushings (UF) that may contribute to nourishing the conceptus. Ovine uteri collected on Day 12 of the estrous cycle (n = 5 ewes exposed to vasectomized ram) or Days 12 (n = 4), 14 (n = 5), or 16 (n = 5) of pregnancy (bred with fertile ram) were flushed using buffered saline. Metabolites were extracted using 80% methanol and profiled using ultraperformance liquid chromatography (LC) tandem mass spectrometry. The proteome was examined by digestion with trypsin, followed by the analysis of peptides with LC-MS/MS. Metabolite profiling detected 8510 molecular features of which 9 were detected only in UF from Day 14-16 pregnant ewes that function in fatty acid transport (carnitines), hormone synthesis (androstenedione like), and availability of nutrients (valine). Proteome analysis detected 783 proteins present by Days 14-16 of pregnancy in UF, 7 of which are as follows: annexin (ANX) A1, A2, and A5; calcium-binding protein (S100A11); profilin 1; trophoblast kunitz domain protein 1 (TKDP); and interferon tau (IFNT). These proteins function in endocytosis, exocytosis, calcium signaling, and inhibition of prostaglandins (annexins and S100A11); protecting against maternal proteases (TKDP); remodeling cytoskeleton (profilin 1); and altering uterine release of prostaglandin F2 alpha as well as inducing IFNT-stimulated genes in the endometrium and the corpus luteum (IFNT). Identifying metabolites and proteins produced by the uterus and conceptus advances our understanding of embryo/maternal signaling and provides insights into possible the causes of reproductive failure.

Effects of Levonorgestrel and progesterone on Oviductal physiology in mammals

BACKGROUND

Our previous study indicated that emergency contraception, including levonorgestrel and progesterone, could lead to ectopic pregnancy following contraception failure. However, our understanding of the effects of levonorgestrel and progesterone on oviductal physiology is limited.

METHODS

The receptivity of the fallopian tubal epithelium after levonorgestrel and progesterone treatment was examined through western blots for receptivity markers and JAr-spheroid-fallopian tubal epithelial cell attachment assays. The ciliary beat frequency was analyzed using an inverted bright-field microscope. Furthermore, an in vivo animal model of embryo-tubal transplantation was also studied to determine the effects of levonorgestrel- and progesterone-induced ciliary beat reduction.

RESULTS

Our results showed that levonorgestrel and progesterone did not change the levels of fallopian tubal epithelial cell receptive markers, including LIF, STAT3, IGFBP1, ITGB3, MUC1, and ACVR1B, or affect JAr-spheroid implantation. However, levonorgestrel and progesterone reduced the ciliary beat frequency in fallopian tubes in a dose-dependent manner. An in vivo model also showed that levonorgestrel and progesterone could lead to embryo retention in the oviducts.

CONCLUSIONS

These findings show that levonorgestrel and progesterone can reduce the ciliary beat frequency without altering receptivity, indicating a possible mechanism for progesterone- or levonorgestrel-induced tubal pregnancy.

Environmentally relevant levels of bisphenol A affect uterine decidualization and embryo implantation through the estrogen receptor/serum and glucocorticoid-regulated kinase 1/epithelial sodium ion channel α-subunit pathway in a mouse model

OBJECTIVE

To investigate whether bisphenol A (BPA) exposure is associated with uterine decidualization and embryo implantation failure in mice.

DESIGN

Experimental animal study and in vitro study.

SETTING

University-based infertility center.

ANIMAL(S)

ICR mice.

INTERVENTION(S)

Mice treated with different doses of BPA; Ishikawa cells cultured in medium of different concentrations of BPA.

MAIN OUTCOME MEASURE(S)

Embryo implantation sites, uterine weight, quantitative real-time reverse transcriptase-polymerase chain reaction, Western blot analysis, hematoxylin and eosin staining, and immunohistochemical, cell proliferation, and statistical analyses.

RESULT(S)

In the experiment of mouse model, administration of 1-100 μg/kg/day of BPA by gavage led to reduction of the number of embryo implantation sites in a dose-dependent manner; 100 μg/kg/day of BPA statistically significantly reduced the number of implantation sites compared with the control group. The uterine weight change (the wet weight of the decidualized uterine horn divided by the wet weight of the undecidualized uterine horn of the mouse) in groups exposed to BPA (100-10,000 μg/kg/day) were statistically significantly lower compared with the control group. Immunohistochemical analysis demonstrated that administration of 100, 1,000, or 10,000 μg/kg/day of BPA by gavage statistically significantly down-regulated the expression of epithelial Na⁺ channel α-subunit (ENaCα) in the luminal epithelial cells and desmin in decidual cells of the oil-induced decidualized uterine horns. Administration of 100 μg/kg/day BPA on embryo days 0.5-3.5 by gavage statistically significantly decreased the level of uterine serum and glucocorticoid-regulated kinase 1 (SGK1) protein expression on embryo days 4 and 6. After treatment with 0.001, 0.01, 0.1, or 1.0 μg/mL of BPA for 48 hours, the SGK1, ENaCα, and phospho-SGK1 protein expression of Ishikawa cells was down-regulated, and the effect of BPA on SGK1 could be abrogated by fulvestrant.

CONCLUSION(S)

Our study provides the first indication that BPA exposure at levels as low as 100 μg/kg/day can impair embryo implantation in mice and BPA can affect decidualization of the uterus in mouse model. Our results suggest that BPA can down-regulate SGK1 and ENaCα protein expression through estrogen receptors in Ishikawa cells.

Sorcin is involved during embryo implantation via activating VEGF/PI3K/Akt pathway in mice

Our earlier studies have demonstrated the cyclic variation and also the altered expression of sorcin in endometrium during early-to-mid-secretory phase transition in women with unexplained infertility. The current study was undertaken to establish the functional role of sorcin in endometrial receptivity in mice. Results indicated that sorcin was highly expressed during the window of implantation in mice and functional blockage of sorcin caused significant reduction in number of implanted blastocyst. The receptivity markers (i.e.Integrin β3, HBEGF, IGFBP1, WNT4 and Cyclin E)) were found to be downregulated in sorcin knocked down uterine horn on day 5 as compared to untreated horn. The reduced attachment and expansion of BeWo spheroids on RL95-2 endometrial cells with sorcin knock down, in in vitro model of endometrium-trophoblast interaction further supported these findings. Uterine sorcin expression pattern during estrous cycle and in delayed implantation mice model suggested the upregulation of sorcin by estrogen. The functional blockade of sorcin induced the intracellular Ca⁺² levels in endometrial epithelial cells (EECs), which indicated that altered Ca⁺² homeostasis might be responsible for implantation failure. Sorcin silencing led to significant reduction in the expression of angiogenic factor VEGF and its downstream effector molecules i.e. PI3K, Akt and NOS. The migratory and invasive properties of HUVECs were abrogated by anti-VEGF or by adding culture media from sorcin blocked EECs, which indicated that sorcin might mediate angiogenesis during implantation. Taken together, sorcin is involved in the regulation of Ca⁺²-mediated angiogenesis via VEGF/PI3K/Akt pathway in endometrial cells and plays a crucial role in preparing the endometrium for implantation.

S100A11 regulates renal carcinoma cell proliferation, invasion, and migration via the EGFR/Akt signaling pathway and E-cadherin

S100A11 is a S100 protein family member that contributes to cancer progression. Upregulated in human renal cancer tissues, S100A11 may be a prognostic marker for clear cell renal cell carcinoma, but how it functions in cancer is uncertain. Thus, we studied S100A11 and noted knockdown of S100A11 using short hairpin RNA, which inhibited proliferation, invasion, and migration of renal carcinoma cells as well as increased expression of E-cadherin and decreased expression of epidermal growth factor receptor/Akt in renal carcinoma cells. Therefore, S100A11 may be a key molecular target for treating renal carcinoma.

Roles of Grp78 in Female Mammalian Reproduction

The glucose-regulated protein (GRP78) also referred to as immunoglobulin heavy chain binding protein (Bip) is one of the best characterized endoplasmic reticulum (ER) chaperone proteins, which belongs to the heat-shock protein (HSP) family. GRP78 as a central regulator of ER stress (ERS) plays many important roles in cell survival and apoptosis through controlling the activation of transmembrane ERS sensors: PKR-like ER-associated kinase (PERK), inositol requiring kinase 1 (IRE1), and activating transcription factor 6 (ATF6). Many studies have reported that GRP78 is involved in the physiological and pathological process in female reproduction, including follicular development, corpus luteum (CL), oviduct, uterus, embryo, preimplantation development, implantation/decidualization, and the placenta. The present review summarizes the biological or pathological roles and signaling mechanisms of GRP78 during the reproductive processes. Further study on the functions and mechanisms of GRP78 may provide new insight into mammalian reproduction, which not only enhance the understanding of the physiological roles but also support therapy target against infertility.

Integrative Analyses of Uterine Transcriptome and MicroRNAome Reveal Compromised LIF-STAT3 Signaling and Progesterone Response in the Endometrium of Patients with Recurrent/Repeated Implantation Failure (RIF)

Intimate two-way interactions between the implantation-competent blastocyst and receptive uterus are prerequisite for successful embryo implantation. In humans, recurrent/repeated implantation failure (RIF) may occur due to altered uterine receptivity with aberrant gene expression in the endometrium as well as genetic defects in embryos. Several studies have been performed to understand dynamic changes of uterine transcriptome during menstrual cycles in humans. However, uterine transcriptome of the patients with RIF has not been clearly investigated yet. Here we show that several signaling pathways as well as many genes and microRNAs are dysregulated in the endometrium of patients with RIF (RIFE). Whereas unsupervised hierarchical clustering showed that overall mRNA and microRNA profiles of RIFE were similar to those of endometria of healthy women, many genes were significantly dysregulated in RIFE (cut off at 1.5 fold change). The majority (~75%) of differentially expressed genes in RIFE including S100 calcium binding protein P (S100P), Chemokine (C-X-C motif) ligand 13 (CXCL13) and SIX homeobox 1 (SIX1) were down-regulated, suggesting that reduced uterine expression of these genes is associated with RIF. Gene Set Enrichment analyses (GSEA) for mRNA microarrays revealed that various signaling pathways including Leukemia inhibitory factor (LIF) signaling and a P4 response were dysregulated in RIFE although expression levels of Estrogen receptor α (ERα) and Progesterone receptor (PR) were not significantly altered in RIFE. Furthermore, expression and phosphorylation of Signal transducer and activator of transcription 3 (STAT3) are reduced and a gene set associated with Janus kinase (JAK)-STAT signaling pathway is systemically down-regulated in these patients. Pairwise analyses of microRNA arrays with prediction of dysregulated microRNAs based on mRNA expression datasets demonstrated that 6 microRNAs are aberrantly regulated in RIFE. Collectively, we here suggest that dysregulation of several major signaling pathways and genes critical for uterine biology and embryo implantation may lead to uterine abnormalities in patients with RIF.

Human S100A10 plays a crucial role in the acquisition of the endometrial receptivity phenotype

In assisted reproduction, about 30% of embryo implantation failures are related to inadequate endometrial receptivity. To identify molecules involved in endometrial receptivity acquisition, we investigated, using a SELDI-TOF approach, the protein expression profile of early-secretory and mid-secretory endometrium samples. Among the proteins upregulated in mid-secretory endometrium, we investigated the function of S100A10 in endometrial receptivity and implantation process. S100A10 was expressed in epithelial and stromal cells of the endometrium of fertile patients during the implantation windows. Conversely, it was downregulated in the mid-secretory endometrium of infertile patients diagnosed as non-receptive. Transcriptome analysis of human endometrial epithelial and stromal cells where S100A10 was silenced by shRNA revealed the deregulation of 37 and 256 genes, respectively, related to components of the extracellular matrix and intercellular connections. Functional annotations of these deregulated genes highlighted alterations of the leukocyte extravasation signaling and angiogenesis pathways that play a crucial role during implantation. S100A10 silencing also affected the migration of primary endometrial epithelial and stromal cells, decidualization and secretory transformation of primary endometrial stromal cells and epithelial cells respectively, and promoted apoptosis in serum-starved endometrial epithelial cells. Our findings identify S100A10 as a player in endometrial receptivity acquisition.

Decreased expression of aquaporin 2 is associated with impaired endometrial receptivity in controlled ovarian stimulation

Recently, there has been evidence of decreased implantation rates with in vitro fertilisation and embryo transfer due to controlled ovarian stimulation (COS). The aim of this study was to investigate the effect of COS on embryo implantation and the role of aquaporin 2 (AQP2). We recruited eight patients who underwent COS and 40 matched controls. Endometrial samples were collected on Day 4~8 after injection of human chorionic gonadotrophin in the COS group and in the mid-secretory phase in the control group. Human endometrial morphological changes after COS were examined and expression of AQP2, leukaemia inhibitory factor (LIF) and integrin B3 (ITGB3) were determined by quantitative polymerase chain reaction, western blotting and immunohistochemistry in human endometrium and Ishikawa cells. Attachment rates were obtained using the embryo attachment test. The results showed that endometrial epithelial cells from the COS group were disrupted and lacked pinopodes. Messenger RNA and protein levels of AQP2, LIF and ITGB3 decreased in endometrial samples from the COS group. Knockdown of AQP2 resulted in reduced expression of LIF and ITGB3 and reduced embryo attachment rates. In conclusion, impaired endometrial receptivity in patients who underwent COS is correlated with a decreased expression of AQP2.

Annexin A2 Acts as an Adhesion Molecule on the Endometrial Epithelium during Implantation in Mice

To determine the function of Annexin A2 (Axna2) in mouse embryo implantation in vivo, experimental manipulation of Axna2 activities was performed in mouse endometrial tissue in vivo and in vitro. Histological examination of endometrial tissues was performed throughout the reproduction cycle and after steroid treatment. Embryo implantation was determined after blockage of the Axna2 activities by siRNA or anti-Axna2 antibody. The expression of Axna2 immunoreactivies in the endometrial luminal epithelium changed cyclically in the estrus cycle and was upregulated by estrogen. After nidatory estrogen surge, there was a concentration of Axna2 immunoreactivities at the interface between the implanting embryo and the luminal epithelium. The phenomenon was likely to be induced by the implanting embryos as no such concentration of signal was observed in the inter-implantation sites and in pseudopregnancy. Knockdown of Axna2 by siRNA reduced attachment of mouse blastocysts onto endometrial tissues in vitro. Consistently, the number of implantation sites was significantly reduced after infusion of anti-Axna2 antibody into the uterine cavity. Steroids and embryos modulate the expression of Axna2 in the endometrial epithelium. Axna2 may function as an adhesion molecule during embryo implantation in mice.

Characterization of the Transcriptional Complexity of the Receptive and Pre-receptive Endometria of Dairy Goats

Endometrium receptivity is essential for successful embryo implantation in mammals. However, the lack of genetic information remains an obstacle to understanding the mechanisms underlying the development of a receptive endometrium from the pre-receptive phase in dairy goats. In this study, more than 4 billion high-quality reads were generated and de novo assembled into 102,441 unigenes; these unigenes were annotated using published databases. A total of 3,255 unigenes that were differentially expressed (DEGs) between the PE and RE were discovered in this study (P-values < 0.05). In addition, 76,729–77,102 putative SNPs and 12,837 SSRs were discovered in this study. Bioinformatics analysis of the DEGs revealed a number of biological processes and pathways that are potentially involved in the establishment of the RE, notably including the GO terms proteolysis, apoptosis, and cell adhesion and the KEGG pathways Cell cycle and extracellular matrix (ECM)-receptor interaction. We speculated that ADCY8, VCAN, SPOCK1, THBS1, and THBS2 may play important roles in the development of endometrial receptivity. The de novo assembly provided a good starting point and will serve as a valuable resource for further investigations into endometrium receptivity in dairy goats and future studies on the genomes of goats and other related mammals.

Regulatory Action of Calcium Ion on Cyclic AMP-Enhanced Expression of Implantation-Related Factors in Human Endometrial Cells

Decidualization of human endometrial stroma and gland development is mediated through cyclic AMP (cAMP), but the role of intracellular calcium ion (Ca2+) on cAMP mediated-signaling in human endometrial stroma and glandular epithelia has not been well-characterized. The present study was designed to investigate the role of intracellular Ca2+ on cAMP mediated-decidualization and gland maturation events, which can be identified by the up-regulation of prolactin and IGF-binding protein (IGFBP)1 in human endometrial stromal cells (ESCs), and cyclooxygenase 2 (COX2) and prostaglandin E2 (PGE2) and glandular epithelial EM-1 cells. Increases in decidual prolactin and IGFBP-1 transcript levels, induced by cAMP-elevating agents forskolin or dibutyryl cyclic AMP, were inhibited by Ca2+ influx into ESCs with Ca2+ ionophores (alamethicin, ionomycin) in a dose-dependent manner. Conversely, inhibitors of Ca2+ influx through L-type voltage-dependent Ca2+ channel (VDCC), nifedipine and verapamil, enhanced the decidual gene expression. Furthermore, dantrolene, an inhibitor of Ca2+ release from the intracellular Ca2+ store, up-regulated prolactin and IGFBP-1 expression. Ca2+ ionophores decreased intracellular cAMP concentrations, whereas nifedipine, verapamil or dantrolene increased cAMP concentrations in ESCs. In glandular epithelial cells, similar responses in COX2 expression and PGE2 production were found when intracellular cAMP levels were up-regulated by decreases in Ca2+ concentrations. Thus, a marked decrease in cytosolic Ca2+ levels caused the elevation of cAMP concentrations, resulting in enhanced expression of implantation-related factors including decidual markers. These findings suggest that fluctuation in cytosolic Ca2+ concentrations alters intracellular cAMP levels, which then regulate differentiation of endometrial stromal and glandular epithelial cells.

The roles of endoplasmic reticulum stress response in female mammalian reproduction

Endoplasmic reticulum stress (ERS) activates a protective pathway, called the unfold protein response, for maintaining cellular homeostasis, but cellular apoptosis is triggered by excessive or persistent ERS. Several recent studies imply that the ERS response might have broader physiological roles in the various reproductive processes of female mammals, including embryo implantation, decidualization, preimplantation embryonic development, follicle atresia, and the development of the placenta. This review summarizes the existing data concerning the molecular and biological roles of the ERS response. The study of the functions of the ERS response in mammalian reproduction might provide novel insights into and an understanding of reproductive cell survival and apoptosis under physiological and pathological conditions. The ERS response is a novel signaling pathway for reproductive cell survival and apoptosis. Infertility might be a result of disturbing the ERS response during the process of female reproduction.

Neurodevelopment and phenotype-modulating functions of S100B protein: a pilot study

The importance of certain neurotrophic proteins found in maternal blood and milk for breastfed infants has remained ambiguous. This study was conducted to present evidence of the impact of an induced deficit of active S100B protein on neonate development. Newborn mice from two groups of mothers, immunized or sham-immunized against S100B, were subjected to various behavioral tests, and the development of their morphological characteristics was recorded from birth until weaning. Morphological problems, including weight gain and fur coating, a delay in the maturation of neurobehavioral systems and a deficit in neuromotor functions, including visual abilities, somato-sensory and posture reactions, muscular strength, locomotion, and fear/orienting processes, were observed in pups of immunized mothers. The S100B protein of external or internal origin in infants may be considered to be a specific factor that determines neuro- and morphological development and a risk-avoidance ('homeward-bent' or fearful) phenotype. The suppression of activity of the S100B protein results in a slower neonatal development and the formation of a risk-tolerant (fearless) phenotype of the offspring. This study thus considers the mechanism of neuroplastic regulation on the extent of sensation-seeking or risk-taking (homeless-like or fearless) and sensation- or risk-avoidance (home-bound or fearful) features in individual phenotypes.

Endometrial CRISP3 is regulated throughout the mouse estrous and human menstrual cycle and facilitates adhesion and proliferation of endometrial epithelial cells

The endometrium (the mucosal lining of the uterus) is a dynamic tissue that undergoes extensive remodeling, secretory transformation in preparation for implantation of an embryo, inflammatory and proteolytic activity during menstruation, and rapid postmenstrual repair. A plethora of local factors influence these processes. Recently, a cysteine-rich protein, CRISP3, a clade of the CRISP, antigen 5, pathogenesis-related (CAP) protein superfamily, has been implicated in uterine function. The localization, regulation, and potential function of CRISP3 in both the human and mouse endometrium is described. CRISP3 localizes to the luminal and glandular epithelium of the endometrium within both species, with increased immunoreactivity during the proliferative phase of the human cycle. CRISP3 also localizes to neutrophils, particularly within the premenstrual human endometrium and during the postbreakdown repair phase of a mouse model of endometrial breakdown and repair. Endometrial CRISP3 is produced by primary human endometrial epithelial cells and secreted in vivo to accumulate in the uterine cavity. Secreted CRISP3 is more abundant in uterine lavage fluid during the proliferative phase of the menstrual cycle. Human endometrial epithelial CRISP3 is present in both a glycosylated and a nonglycosylated form in vitro and in vivo. Treatment of endometrial epithelial cells in vitro with recombinant CRISP3 enhances both adhesion and proliferation. These data suggest roles for epithelial and neutrophil-derived CRISP3 in postmenstrual endometrial repair and regeneration.

EPAC2-mediated calreticulin regulates LIF and COX2 expression in human endometrial glandular cells

The proper production of the implantation-related factors, leukemia inhibitory factor (LIF), cyclooxygenase 2 (COX2, PTGS2), and prostaglandin E2 (PGE2) in the uterine glands is essential for embryo implantation and the establishment of endometrial receptivity. It has been shown that cAMP-mediated protein kinase A (PKA) signaling regulates the production of these factors. We have previously reported that exchange protein directly activated by cAMP 2 (EPAC2, RAPGEF4), another cAMP mediator, is involved in the differentiation of endometrial stromal cells through the regulation of the expression of calreticulin (CALR). To address whether EPAC2-CALR signaling is involved in the expression of implantation-related factors, we examined the effect of EPAC2 and CALR knockdown on their expression in cultured human endometrial glandular epithelial EM1 cells, treated with forskolin, an adenylyl cyclase activator, an EPAC-selective cAMP analog (8-(4-chlorophenylthio)-2'-O-methyl cAMP (CPT)), or a PKA-selective cAMP analog (N(6)-phenyl-cAMP (Phe)). In addition, the status of cell senescence was examined. EPAC2 knockdown suppressed the expression of CALR protein and mRNA in EM1 cells. Forskolin- or Phe-, but not CPT-, induced expression of LIF or PTGS2 and secretion of PGE2 was inhibited in EPAC2- or CALR-silenced EM1 cells. In addition, knockdown of EPAC2 or CALR increased senescence-associated beta galactosidase activity and expression of p21 but decreased expression of p53. These findings indicate that expression of CALR regulated by EPAC2 in endometrial glandular epithelial cells is critical for the expression of LIF and PTGS2-mediated production of PGE2 through cAMP signaling. Furthermore, EPAC2 and CALR could play a role in the maintenance of gland function.

Leptin down-regulates γ-ENaC expression: a novel mechanism involved in low endometrial receptivity

OBJECTIVE

To examine epithelial Na(+) channel (ENaC) expression in endometrium of overweight/obese women with polycystic ovary syndrome (PCOS) during the window of implantation, and to explore the mechanism linking leptin-mediated reduction of γ-ENaC to low endometrial receptivity.

DESIGN

Controlled, prospective, clinical, experimental study.

SETTING

University-based infertility center.

PATIENT(S)

Blood and endometrium samples were collected from 12 control women and 12 overweight/obese PCOS patients. Pregnancy outcomes were obtained from 245 women with male-factor infertility (533 cycles) and 57 infertile women with PCOS (120 cycles) who underwent intrauterine insemination.

INTERVENTION(S)

Human endometrial biopsies.

MAIN OUTCOME MEASURE(S)

Expression of ENaC mRNA and protein in endometrium.

RESULT(S)

The expression of γ-ENaC decreased in the secretory phase endometrium of PCOS patients who showed increased serum leptin levels. In cultured endometrial cells (Ishikawa cells), leptin dose-dependently down-regulated the expression of γ-ENaC and reduced the JAr spheroid attachment rate, which could be blocked by knockdown of STAT3, a signal in the pathway of leptin receptor activation. The overweight/obese PCOS patients with increased serum leptin levels showed a significantly increased biochemical pregnancy rate, suggesting that high leptin might attenuate endometrial receptivity and increase very early pregnancy loss.

CONCLUSION(S)

High serum leptin may reduce endometrial receptivity by activating the STAT3 signal pathway and down-regulating γ-ENaC expression in the endometrium. These results provide valuable new insights into the molecular mechanisms linking abnormal ENaC gene expression to early pregnancy loss in overweight/obese PCOS patients.

Ion/Water Channels for Embryo Implantation Barrier

Successful implantation involves three distinct processes, namely the embryo apposition, attachment, and penetration through the luminal epithelium of the endometrium to establish a vascular link to the mother. After penetration, stromal cells underlying the epithelium differentiate and surround the embryo to form the embryo implantation barrier, which blocks the passage of harmful substances to the embryo. Many ion/water channel proteins were found to be involved in the process of embryo implantation. First, ion/water channel proteins play their classical role in establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane. Second, most of ion/water channel proteins are regulated by steroid hormone (estrogen or progesterone), which may have important implications to the embryo implantation. Last but not least, these proteins do not limit themselves as pure channels but also function as an initiator of a series of consequences once activated by their ligand/stimulator. Herein, we discuss these new insights in recent years about the contribution of ion/water channels to the embryo implantation barrier construction during early pregnancy.

Ion channels in the endometrium: regulation of endometrial receptivity and embryo implantation

BACKGROUND

Although embryo implantation is a prerequisite for human reproduction, it remains a poorly understood process. The molecular mechanisms regulating endometrial receptivity and/or embryo implantation are still largely unclear.

METHODS

Pubmed and Medline literature databases were searched for articles in English published up to December 2013 with relevant keywords including 'endometrium', 'Na(+), Cl(-), K(+), or Ca(2+) channels', 'ion channels', 'endometrial receptivity', 'blastocyst implantation' and 'embryo implantation'.

RESULTS

At the time of writing, more than 14 types of ion channels, including the cystic fibrosis transmembrane conductance regulator, epithelial sodium channel and various Ca(2+) and K(+) channels, had been reported to be expressed in the endometrium or cells of endometrial origin. In vitro and/or in vivo studies conducted on different species, including rodents, pigs and humans, demonstrated the involvement of various ion channels in the process of embryo implantation by regulating: (i) uterine luminal fluid volume; (ii) decidualization; and (iii) the expression of the genes associated with implantation. Importantly, abnormal ion channel expression was found to be associated with implantation failure in IVF patients.

CONCLUSIONS

Ion channels in the endometrium are emerging as important players in regulating endometrial receptivity and embryo implantation. Abnormal expression or function of ion channels in the endometrium may lead to impaired endometrial receptivity and/or implantation failure. Further investigation into the roles of endometrial ion channels may provide a better understanding of the complex process of embryo implantation and thus reveal novel targets for diagnosis and treatment of implantation failure.