LC-MS analysis of estradiol in human serum and endometrial tissue: Comparison of electrospray ionization, atmospheric pressure chemical ionization and atmospheric pressure photoionization

Accurate measurement of estradiol (E2) is important in clinical diagnostics and research. High sensitivity methods are critical for specimens with E2 concentrations at low picomolar levels, such as serum of men, postmenopausal women and children. Achieving the required assay performance with LC-MS is challenging due to the non-polar structure and low proton affinity of E2. Previous studies suggest that ionization has a major role for the performance of E2 measurement, but comparisons of different ionization techniques for the analysis of clinical samples are not available. In this study, female serum and endometrium tissue samples were used to compare electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) in both polarities. APPI was found to have the most potential for E2 analysis, with a quantification limit of 1 fmol on-column. APCI and ESI could be employed in negative polarity, although being slightly less sensitive than APPI. In the presence of biological background, ESI was found to be highly susceptible to ion suppression, while APCI and APPI were largely unaffected by the sample matrix. Irrespective of the ionization technique, background interferences were observed when using the multiple reaction monitoring transitions commonly employed for E2 (m/z 271 > 159; m/z 255 > 145). These unidentified interferences were most severe in serum samples, varied in intensity between ionization techniques and required efficient chromatographic separation in order to achieve specificity for E2.

FELASA guidelines for the refinement of methods for genotyping genetically-modified rodents

The use of genetically-modified (GM) animals as research models continues to grow. The completion of the mouse genome sequence, together with the high-throughput international effort to introduce mutations across the mouse genome in the embryonic stem (ES) cells ( www.knockoutmouse.org ) facilitates an efficient way to obtain mutated mouse strains as research models. The increasing number of available mutated mouse strains and their combinations, together with the increasing complexity in the targeting approaches used, reinforces the need for guidelines that will provide information about the mouse strains and the robust and reliable methods used for their genotyping. This information, however, should be obtained with a method causing minimal discomfort to the experimental animals. We have, therefore, compiled the present document which summarizes the currently available methods for obtaining genotype information. It provides updated guidelines concerning animal identification, DNA sampling and genotyping, and the information to be kept and distributed for any mutated rodent strain.

The transcriptional co-factor RIP140 regulates mammary gland development by promoting the generation of key mitogenic signals

Nuclear receptor interacting protein (Nrip1), also known as RIP140, is a co-regulator for nuclear receptors that plays an essential role in ovulation by regulating the expression of the epidermal growth factor-like family of growth factors. Although several studies indicate a role for RIP140 in breast cancer, its role in the development of the mammary gland is unclear. By using RIP140-null and RIP140 transgenic mice, we demonstrate that RIP140 is an essential factor for normal mammary gland development and that it functions by mediating oestrogen signalling. RIP140-null mice exhibit minimal ductal elongation with no side-branching, whereas RIP140-overexpressing mice show increased cell proliferation and ductal branching with age. Tissue recombination experiments demonstrate that RIP140 expression is required in both the mammary epithelial and stromal compartments for ductal elongation during puberty and that loss of RIP140 leads to a catastrophic loss of the mammary epithelium, whereas RIP140 overexpression augments the mammary basal cell population and shifts the progenitor/differentiated cell balance within the luminal cell compartment towards the progenitors. For the first time, we present a genome-wide global view of oestrogen receptor-α (ERα) binding events in the developing mammary gland, which unravels 881 ERα binding sites. Unbiased evaluation of several ERα binding sites for RIP140 co-occupancy reveals selectivity and demonstrates that RIP140 acts as a co-regulator with ERα to regulate directly the expression of amphiregulin (Areg), the progesterone receptor (Pgr) and signal transducer and activator of transcription 5a (Stat5a), factors that influence key mitogenic pathways that regulate normal mammary gland development.

Interactions between inflammatory signals and the progesterone receptor in regulating gene expression in pregnant human uterine myocytes

The absence of a fall in circulating progesterone levels has led to the concept that human labour is associated with 'functional progesterone withdrawal' caused through changes in the expression or function of progesterone receptor (PR). At the time of labour, the human uterus is heavily infiltrated with inflammatory cells, which release cytokines to create a 'myometrial inflammation' via NF-κB activation. The negative interaction between NF-κB and PR, may represent a mechanism to account for 'functional progesterone withdrawal' at term. Conversely, PR may act to inhibit NF-κB function and so play a role in inhibition of myometrial inflammation during pregnancy. To model this inter-relationship, we have used small interfering (si) RNA-mediated knock-down of PR in human pregnant myocytes and whole genome microarray analysis to identify genes regulated through PR. We then activated myometrial inflammation using IL-1β stimulation to determine the role of PR in myometrial inflammation regulation. Through PR-knock-down, we found that PR regulates gene networks involved in myometrial quiescence and extracellular matrix integrity. Activation of myometrial inflammation was found to antagonize PR-induced gene expression, of genes normally upregulated via PR. We found that PR does not play a role in repression of pro-inflammatory gene networks induced by IL-1β and that only MMP10 was significantly regulated in opposite directions by IL-1β and PR. We conclude that progesterone acting through PR does not generally inhibit myometrial inflammation. Activation of myometrial inflammation does cause 'functional progesterone withdrawal' but only in the context of genes normally upregulated via PR.

Inbred wild type mouse strains have distinct spontaneous morphological phenotypes

The mouse is the most commonly used animal for modelling human disease. New approaches for generating genetically manipulated mouse models to represent human disease, as well as target the function of specific genes, has increased the importance of mice in biomedical science. For the correct interpretation of alterations in mouse phenotype the basic morphology of background mouse strains must be known. Despite on-going efforts to create publicly available baseline phenotypic data, the information concerning spontaneous lesions in wild-type mice is incomplete and scattered so far, and further studies are needed. We addressed this problem by screening haematoxylin-eosin stained sections of brain, reproductive organs, urinary bladder, kidney, thyroid, parathyroid, heart, lung, spleen, thymus, lymph nodes, adrenal glands, stomach, intestine, liver, skin and pancreas of six commonly used inbred mouse strains (C57BL6/J, C57BL6/NTac, C3HeB/FeJ, BALB/cByJ, 129P2/OlaHsd and FVB/N) for inherent spontaneous morphological lesions. Interesting spontaneous phenotypes were seen in morphology of the liver, pancreas, adrenal glands, lungs, intestines and heart. In conclusion, care should be taken when choosing the background mouse strain for genetic manipulations, since different mouse strains harbour different inherent lesions that can affect the function of targeted genes, interpretation of results and translation of results to model human disease.

Short-term pharmacological suppression of the hyperprolactinemia of infertile hCG-overproducing female mice persistently restores their fertility

Female infertility is often associated with deregulation of hormonal networks, and hyperprolactinemia is one of the most common endocrine disorders of the hypothalamic-pituitary axis affecting the reproductive functions. We have shown previously that transgenic female mice overexpressing human chorionic gonadotropin β-subunit (hCGβ+ mice), and producing elevated levels of bioactive LH/hCG, exhibit increased production of testosterone and progesterone, are overweight and infertile, and develop hyperprolactinemia associated with pituitary lactotrope adenomas in adult age. In the present study, we analyzed the influence of the hyperprolactinemia of hCGβ+ females on their reproductive phenotype by treating them with the dopamine agonists, bromocriptine and cabergoline. Long-term bromocriptine treatment of adult mice was effective in the control of obesity, pituitary growth, and disturbances in the hormone profile, demonstrating that hyperprolactinemia was the main cause of the hCGβ+ female phenotype. Interestingly, short-term treatment (1 wk) with cabergoline applied on 5-wk-old mice corrected hyperprolactinemia, hyperandrogenism, and hyperprogesteronemia, prevented pituitary overgrowth, normalized gonadal function, and recovered fertility of adult hCGβ+ females after hormone-induced and natural ovulation. The same cabergoline treatment in the short term applied on 3-month-old hCGβ+ females failed to recover their reproductive function. Hence, we demonstrated that the short-term cabergoline treatment applied at a critical early stage of the phenotype progression effectively prevented the hyperprolactinemia-associated reproductive dysfunction of hCG-overproducing females.

Endometrial and endometriotic concentrations of estrone and estradiol are determined by local metabolism rather than circulating levels

CONTEXT

Aberrant estrogen synthesis and metabolism have been suggested to increase local estradiol (E2) concentration in endometriosis and thus to promote the growth of the lesions. However, tissue estrogen concentrations within the endometrium and different types of endometriosis lesions have not been described.

OBJECTIVE

The aim of the study was to evaluate local E2 and estrone (E1) concentrations in the endometrium and different types of endometriosis lesions, and to correlate them with the expression of estrogen-metabolizing enzymes.

PATIENTS

Patients with endometriosis (n = 60) and healthy controls (n = 16) participated in the study.

MAIN OUTCOME MEASURES

We measured serum and tissue concentrations of E2 and E1 as well as mRNA expression of the estrogen-metabolizing enzymes.

RESULTS

Endometrial or endometriotic intratissue E2 concentrations did not reflect the corresponding serum levels. In the proliferative phase, endometrial E2 concentration was five to eight times higher than in the serum, whereas in the secretory phase the E2 concentration was about half of that in the serum. Accordingly, a markedly higher E2/E1 ratio was observed in the endometrium at the proliferative phase compared with the secretory phase. In the endometriosis lesions, E2 levels were predominating over those of E1 throughout the menstrual cycle. Among the hydroxysteroid (17β) dehydrogenase (HSD17B) enzymes analyzed, HSD17B2 negatively correlated with the E2 concentration in the endometrium, and HSD17B6 was strongly expressed, especially in the deep lesions.

CONCLUSIONS

Endometrial or endometriotic tissue E2 concentrations are actively regulated by local estrogen metabolism in the tissue. Thus, the inhibition of local E2 synthesis is a valid, novel approach to reduce local E2-dependent growth of endometriotic tissue.

Loss of Bmyc results in increased apoptosis associated with upregulation of Myc expression in juvenile murine testis

Bmyc is a member of the Myc family of transcriptional regulators in the mouse and the rat. It is predominantly expressed in hormonally controlled tissues, with highest level of expression in the epididymis. The BMYC protein has been shown to function as a transcription factor in vitro and to inhibit MYC. To study the significance of BMYC in vivo, a Bmyc knockout (KO) mouse model was generated by homologous recombination. The KO mice were viable and fertile and did not display gross morphological or histological changes compared to the WT mice. However, the testes and the epididymides of the KO mice were smaller than those of the WT mice. Correspondingly, a tendency for a lower sperm concentration in the cauda epididymides of the KO mice was detected. The testosterone produced/testis was significantly reduced, and accordingly, the LH levels were increased in the KO mice. Also, the expression levels of Myc and several of its target genes were elevated in the testes of prepubertal KO mice, whereas no differences in gene expression levels were detected in adult mice. Associated with the increased Myc expression, more apoptotic spermatogenic cells were detected in the seminiferous tubules of the KO mice. In conclusion, our data suggest that Bmyc is a regulator of Myc in vivo and that overexpression of Myc in the developing testis leads to increased apoptosis of spermatogenic cells.

Estrogen biosynthesis and signaling in endometriosis

Endometriosis is an estrogen-dependent gynecological disease where endometrium-like tissue grows outside uterine cavity. Endometriotic cell proliferation is stimulated by estrogens acting predominantly via their nuclear receptors. Estrogen receptors (ESR1, ESR2) are ligand activated transcription factors whose activation is dependent on the cell-specific dynamic expression of the receptors, on the interacting proteins and on the ligand availability. The different types of endometriotic lesions, peritoneal, deep, and ovarian endometriosis, may respond to estrogens differentially due to differences in the expression of the receptors and interacting proteins, and due to potential differences in the ligand availability regulated by the local estrogen synthesis. This review summarizes the current knowledge of estrogen synthesizing enzymes and estrogen receptors in different types of endometriosis lesions. Further studies are still needed to define the possible differences in steroid metabolism in different types of endometriotic lesions.

Epididymal protein Rnase10 is required for post-testicular sperm maturation and male fertility

Eutherian spermatozoa are dependent on the environment of the proximal epididymis to complete their maturation; however, no specific epididymal factors that mediate this process have so far been identified. Here, we show that targeted disruption of the novel gene Rnase10 encoding a secreted proximal epididymal protein in the mouse results in a binding defect in spermatozoa and their inability to pass through the uterotubal junction in the female. The failure to gain the site of fertilization in the knockout spermatozoa is associated with a gradual loss of ADAM3 and ADAM6 proteins during epididymal transit. In the distal epididymis, these spermatozoa appear to lack calcium-dependent associations with the immobilizing glutinous extracellular material and are released as single, vigorously motile cells that display no tendency for head-to-head agglutination and lack affinity to the oviductal epithelium. In sperm-egg binding assay, they are unable to establish a tenacious association with the zona pellucida, yet they are capable of fertilization. Furthermore, these sperm show accelerated capacitation resulting in an overall in vitro fertilizing ability superior to that of wild-type sperm. We conclude that the physiological role of sperm adhesiveness is in the mechanism of restricted sperm entry into the oviduct rather than in sperm-egg interaction.—Krutskikh, A., Poliandri, A., Cabrera-Sharp, V., Dacheux, J. L., Poutanen, M., Huhtaniemi, I. Epididymal protein Rnase10 is required for post-testicular sperm maturation and male fertility.

Improved statistical modeling of tumor growth and treatment effect in preclinical animal studies with highly heterogeneous responses in vivo

PURPOSE

Preclinical tumor growth experiments often result in heterogeneous datasets that include growing, regressing, or stable growth profiles in the treatment and control groups. Such confounding intertumor variability may mask the true treatment effects especially when less aggressive treatment alternatives are being evaluated.

EXPERIMENTAL DESIGN

We developed a statistical modeling approach in which the growing and poorly growing tumor categories were automatically detected by means of an expectation-maximization algorithm coupled within a mixed-effects modeling framework. The framework is implemented and distributed as an R package, which enables model estimation and statistical inference, as well as statistical power and precision analyses.

RESULTS

When applied to four tumor growth experiments, the modeling framework was shown to (i) improve the detection of subtle treatment effects in the presence of high within-group tumor variability; (ii) reveal hidden tumor subgroups associated with established or novel biomarkers, such as ERβ expression in a MCF-7 breast cancer model, which remained undetected with standard statistical analysis; (iii) provide guidance on the selection of sufficient sample sizes and most informative treatment periods; and (iv) offer flexibility to various cancer models, experimental designs, and treatment options. Model-based testing of treatment effect on the tumor growth rate (or slope) was shown as particularly informative in the preclinical assessment of treatment alternatives based on dietary interventions.

CONCLUSIONS

In general, the modeling framework enables identification of such biologically significant differences in tumor growth profiles that would have gone undetected or had required considerably higher number of animals when using traditional statistical methods.

Dicer1 ablation in the mouse epididymis causes dedifferentiation of the epithelium and imbalance in sex steroid signaling

Background

The postnatal development of the epididymis is a complex process that results in a highly differentiated epithelium, divided into several segments. Recent studies indicate a role for RNA interference (RNAi) in the development of the epididymis, however, the actual requirement for RNAi has remained elusive. Here, we present the first evidence of a direct need for RNAi in the differentiation of the epididymal epithelium.

Methodology/Principal Findings

By utilizing the Cre-LoxP system we have generated a conditional knock-out of Dicer1 in the two most proximal segments of the mouse epididymis. Recombination of Dicer1, catalyzed by Defb41^iCre/wt, took place before puberty, starting from 12 days postpartum. Shortly thereafter, downregulation of the expression of two genes specific for the most proximal epididymis (lipocalin 8 and cystatin 8) was observed. Following this, segment development continued until week 5 at which age the epithelium started to regress back to an undifferentiated state. The dedifferentiated epithelium also showed an increase in estrogen receptor 1 expression while the expression of androgen receptor and its target genes; glutathione peroxidase 5, lipocalin 5 and cysteine-rich secretory protein 1 was downregulated, indicating imbalanced sex steroid signaling.

Conclusions/Significance

At the time of the final epididymal development, Dicer1 acts as a regulator of signaling pathways essential for maintaining epithelial cell differentiation.

Loss of cysteine-rich secretory protein 4 (Crisp4) leads to deficiency in sperm-zona pellucida interaction in mice

Mammalian sperm gain their ability to fertilize the egg during transit through the epididymis and by interacting with proteins secreted by the epididymal epithelial cells. Certain members of the CRISP (cysteine-rich secretory protein) family form the major protein constituent of the luminal fluid in the mammalian epididymis. CRISP4 is the newest member of the CRISP family expressed predominantly in the epididymis. Its structure and expression pattern suggest a role in sperm maturation and/or sperm-egg interaction. To study the relevance of CRISP4 in reproduction, we have generated a Crisp4 iCre knock-in mouse model through insertion of the iCre recombinase coding cDNA into the Crisp4 locus. This allows using the mouse line both as a Crisp4 deficient model and as an epididymis-specific iCre-expressing mouse line applicable for the generation of conditional, epididymis-specific knockout mice. We show that the loss of CRISP4 leads to a deficiency of the spermatozoa to undergo progesterone-induced acrosome reaction and to a decreased fertilizing ability of the sperm in the in vitro fertilization conditions, although the mice remain fully fertile in normal mating. However, removal of the egg zona pellucida returned the fertilization potential of the CRISP4-deficient spermatozoa, and accordingly we detected a reduced number of Crisp4-deficient spermatozoa bound to oocytes as compared with the wild-type spermatozoa. We also demonstrate that iCre recombinase is expressed in a pattern similar to endogenous Crisp4 and is able to initiate the recombination event with its target sequences in vivo.

The diversity of sex steroid action: novel functions of hydroxysteroid (17β) dehydrogenases as revealed by genetically modified mouse models

Disturbed action of sex steroid hormones, i.e. androgens and estrogens, is involved in the pathogenesis of various severe diseases in humans. Interestingly, recent studies have provided data further supporting the hypothesis that the circulating hormone concentrations do not explain all physiological and pathological processes observed in hormone-dependent tissues, while the intratissue sex steroid concentrations are determined by the expression of steroid metabolising enzymes in the neighbouring cells (paracrine action) and/or by target cells themselves (intracrine action). This local sex steroid production is also a valuable treatment option for developing novel therapies against hormonal diseases. Hydroxysteroid (17β) dehydrogenases (HSD17Bs) compose a family of 14 enzymes that catalyse the conversion between the low-active 17-keto steroids and the highly active 17β-hydroxy steroids. The enzymes frequently expressed in sex steroid target tissues are, thus, potential drug targets in order to lower the local sex steroid concentrations. The present review summarises the recent data obtained for the role of HSD17B1, HSD17B2, HSD17B7 and HSD17B12 enzymes in various metabolic pathways and their physiological and pathophysiological roles as revealed by the recently generated genetically modified mouse models. Our data, together with that provided by others, show that, in addition to having a role in sex steroid metabolism, several of these HSD17B enzymes possess key roles in other metabolic processes: for example, HD17B7 is essential for cholesterol biosynthesis and HSD17B12 is involved in elongation of fatty acids. Additional studies in vitro and in vivo are to be carried out in order to fully define the metabolic role of the HSD17B enzymes and to evaluate their value as drug targets.

High levels of the extracellular matrix proteoglycan decorin are associated with inhibition of testicular function

Decorin (DCN), a component of the extracellular matrix of the peritubular wall and the interstitial areas of the human testis, can interact with growth factor (GF) signalling, thereby blocking downstream actions of GFs. In the present study the expression and regulation of DCN using both human testes and two experimental animal models, namely the rhesus monkey and mouse, were examined. DCN protein was present in peritubular and interstitial areas of adult human and monkey testes, while it was almost undetectable in adult wild type mice. Interestingly, the levels and sites of testicular DCN expression in the monkeys were inversely correlated with testicular maturation markers. A strong DCN expression associated with the abundant connective tissue of the interstitial areas in the postnatal through pre-pubertal phases was observed. In adult and old monkeys the DCN pattern was similar to the one in normal human testes, presenting strong expression at the peritubular region. In the testes of both infertile men and in a mouse model of inflammation associated infertility (aromatase-overexpressing transgenic mice), the fibrotic changes and increased numbers of tumour necrosis factor (TNF)-α-producing immune cells were shown to be associated with increased production of DCN. Furthermore, studies with human testicular peritubular cells isolated from fibrotic testis indicated that TNF-α significantly increased DCN production. The data, thus, show that an increased DCN level is associated with impaired testicular function, supporting our hypothesis that DCN interferes with paracrine signalling of the testis in health and disease.

Fast and sensitive liquid chromatography-mass spectrometry assay for seven androgenic and progestagenic steroids in human serum

A fast and sensitive LC-MS/MS method for the quantitative analysis of seven steroid hormones in 150 μl of human serum was developed and validated. The following compounds were included: 17α-hydroxypregnenolone, 17α-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, testosterone, pregnenolone, and progesterone. Individual stable isotope-labeled analogues were used as internal standards. Sample preparation was performed by liquid-liquid extraction, followed by oxime derivatization to improve the ionization efficiency of the analytes. In contrast to the common derivatization-based methods, the reaction was incorporated into the sample preparation process and the only additional step due to the derivatization was a short heating of the autosampler vials before the sample injection. Chromatographic separation was achieved on a reversed-phase column using a methanol-water gradient. For the analyte detection, a triple quadrupole instrument with electrospray ionization was used. Total run time was 7.0 min and the lower limits of quantification were in the range of 0.03-0.34 nM (0.01-0.10 ng/ml), depending on the analyte. The method was validated using human serum samples from both sexes and applied for the serum steroid profiling of endometriosis patients.

Members of the murine Pate family are predominantly expressed in the epididymis in a segment-specific fashion and regulated by androgens and other testicular factors

BACKGROUND

Spermatozoa leaving the testis are not able to fertilize the egg in vivo. They must undergo further maturation in the epididymis. Proteins secreted to the epididymal lumen by the epithelial cells interact with the spermatozoa and enable these maturational changes, and are responsible for proper storage conditions before ejaculation. The present study was carried out in order to characterize the expression of a novel Pate (prostate and testis expression) gene family, coding for secreted cysteine-rich proteins, in the epididymis.

METHODS

Murine genome databases were searched and sequence comparisons were performed to identify members of the Pate gene family, and their expression profiles in several mouse tissues were characterized by RT-PCR. Alternate transcripts were identified by RT-PCR, sequencing and Northern hybridization. Also, to study the regulation of expression of Pate family genes by the testis, quantitative (q) RT-PCR analyses were performed to compare gene expression levels in the epididymides of intact mice, gonadectomized mice, and gonadectomized mice under testosterone replacement treatment.

RESULTS

A revised family tree of Pate genes is presented, including a previously uncharacterized Pate gene named Pate-X, and the data revealed that Acrv1 and Sslp1 should also be considered as members of the Pate family. Alternate splicing was observed for Pate-X, Pate-C and Pate-M. All the Pate genes studied are predominantly expressed in the epididymis, whereas expression in the testis and prostate is notably lower. Loss of androgens and/or testicular luminal factors was observed to affect the epididymal expression of several Pate genes.

CONCLUSIONS

We have characterized a gene cluster consisting of at least 14 expressed Pate gene members, including Acrv1, Sslp1 and a previously uncharacterized gene which we named Pate-X. The genes code for putatively secreted, cysteine-rich proteins with a TFP/Ly-6/uPAR domain. Members of the Pate gene cluster characterized are predominantly expressed in the murine epididymis, not in the testis or prostate, and are regulated by testicular factors. Similar proteins are present in venoms of several reptiles, and they are thought to mediate their effects by regulating certain ion channels, and are thus expected to have a clinical relevance in sperm maturation and epididymal infections.

Down-regulation of the histone methyltransferase EZH2 contributes to the epigenetic programming of decidualizing human endometrial stromal cells

Differentiation of human endometrial stromal cells (HESC) into decidual cells represents a highly coordinated process essential for embryo implantation. We show that decidualizing HESC down-regulate the histone methyltransferase enhancer of Zeste homolog 2 (EZH2), resulting in declining levels of trimethylation of histone 3 on lysine 27 (H3K27me3) at the proximal promoters of key decidual marker genes PRL and IGFBP1. Loss of H3K27me3 was associated with a reciprocal enrichment in acetylation of the same lysine residue, indicating active remodeling from repressive to transcriptionally permissive chromatin. Chromatin immunoprecipitation coupled with DNA microarray analysis demonstrated that decidualization triggers genome-wide changes in H3K27me3 distribution that only partly overlap those observed upon EZH2 knockdown in undifferentiated HESC. Gene ontology revealed that gain of the repressive H3K27me3 mark in response to decidualization and upon EZH2 knockdown in undifferentiated cells was enriched at the promoter regions of genes involved in transcriptional regulation and growth/cell proliferation, respectively. However, loss of the H3K27me3 mark (indicating increased chromatin accessibility) in decidualizing cells and upon EZH2 knockdown occurred at selective loci enriched for genes functionally implicated in responses to stimulus. In agreement, EZH2 knockdown in undifferentiated HESC was sufficient to augment the induction of decidual marker genes in response to cyclic AMP and progesterone signaling. Thus, loss of EZH2-dependent methyltransferase activity in the endometrium is integral to the process of chromatin remodeling that enables the transition from a proliferative to a decidual phenotype in response to differentiation cues.

A single dose of enterolactone activates estrogen signaling and regulates expression of circadian clock genes in mice

Enterolactone (EL) is an enterolignan produced by gut microbiota from dietary plant lignans. Epidemiological and experimental studies suggest that EL and plant lignans may reduce the risk of breast and prostate cancer as well as cardiovascular disease. These effects are thought to at least in part involve modulation of estrogen receptor activity. Surprisingly little is known about the in vivo estrogenicity of EL. In the present study, we investigated the target tissues of EL, the genes affected by EL treatment, and the response kinetics. Following a single dose of EL, luciferase was significantly induced in reproductive and nonreproductive tissues of male and female 3xERE-luciferase mice, indicating estrogen-like activity. Microarray analysis revealed that EL regulated the expression of only 1% of 17β-estradiol target genes in the uterus. The majority of these genes were traditional estrogen target genes, but also members of the circadian signaling pathway were affected. Kinetic analyses showed that EL undergoes rapid phase II metabolism and is efficiently excreted. In vivo imaging demonstrated that the estrogen response followed similar, fast kinetics. We conclude that EL activates estrogen signaling in both male and female mice and that the transient responses may be due to the fast metabolism of the compound. Lastly, EL may represent a link among diet, gut microbiota, and circadian signaling.