A Novel Pathway Involving Progesterone Receptor, 12/15-Lipoxygenase-derived Eicosanoids, and Peroxisome Proliferator-activated Receptor γ Regulates Implantation in Mice

Ribosomal protein control of hematopoietic stem cell transformation through direct, non-canonical regulation of metabolism

We report here that expression of the ribosomal protein, RPL22, is frequently reduced in human myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML); reduced RPL22 expression is associated with worse outcomes. Mice null for Rpl22 display characteristics of an MDS-like syndrome and develop leukemia at an accelerated rate. Rpl22-deficient mice also display enhanced hematopoietic stem cell (HSC) self-renewal and obstructed differentiation potential, which arises not from reduced protein synthesis but from increased expression of the Rpl22 target, ALOX12, an upstream regulator of fatty acid oxidation (FAO). The increased FAO mediated by Rpl22-deficiency also persists in leukemia cells and promotes their survival. Altogether, these findings reveal that Rpl22 insufficiency enhances the leukemia potential of HSC via non-canonical de-repression of its target, ALOX12, which enhances FAO, a process that may serve as a therapeutic vulnerability of Rpl22 low MDS and AML leukemia cells.

Highlights

RPL22 insufficiency is observed in MDS/AML and is associated with reduced survivalRpl22-deficiency produces an MDS-like syndrome and facilitates leukemogenesisRpl22-deficiency does not impair global protein synthesis by HSCRpl22 controls leukemia cell survival by non-canonical regulation of lipid oxidation eTOC: Rpl22 controls the function and transformation potential of hematopoietic stem cells through effects on ALOX12 expression, a regulator of fatty acid oxidation.

Gut Microbial Succession Patterns and Metabolic Profiling during Pregnancy and Lactation in a Goat Model

The maternal gut microbiome affects the duration of pregnancy, delivery, and lactation. It also coordinates the stability of maternal metabolism by regulating and modulating inflammatory cytokines and reproductive hormones. This has been shown in several species; however, the situation in ruminants remains a black box. Here, we aimed to elucidate the relationship between the hindgut microbiota, metabolism, and reproductive hormones in domestic goats (Capra hircus) during nonpregnancy, pregnancy, and lactation stages. The hindgut microbiota was altered during these three stages, with a drastic decrease in the abundance of Family_XIII_AD3011_group in the second and third trimesters of pregnancy. Additionally, a decline in the abundance of Christensenellaceae_R-7_group and Turicibacter was observed from the nonpregnancy stage to late gestation. Family_XIII_AD3011_group and Paeniclostridium were strongly correlated with decreased fecal estradiol and progesterone. Furthermore, we generated a metabolome atlas of the gut and serum from nonpregnancy to lactation to reveal the specific metabolic fingerprints of each physiological stage. Several specific gut metabolites, including carnitine C8:1, γ-aminobutyric acid, and indole-3-carboxylic acid, were negatively correlated with the fecal and serum estradiol concentrations. In contrast, 2'-deoxyinosine, deoxyadenosine, and 5'-deoxyadenosine were positively correlated with the fecal and serum estradiol concentrations. The levels of 2'-deoxyinosine, deoxyadenosine, and 5'-deoxyadenosine in fecal samples were positively correlated with Family_XIII_AD3011_group. Other serum metabolites, such as (±)12-HEPE (hydroxy eicosapentaenoic acid), (±)15-HEPE, (±)18-HEPE, cytidine, uracil, and 5-hydroxyindole-3-acetic acid, were negatively correlated with the serum concentrations of estradiol and progesterone. Finally, Corynebacterium and Clostridium_sensu_stricto_1 in the fecal samples were positively correlated with the abundance of 11,12-EET (epoxy-eicosatrienoic acid), (±)18-HEPE, (±)15-HEPE, and (±)12-HEPE in the serum. IMPORTANCE Our findings revealed that the activity of Family_XIII_AD3011_group and Corynebacterium is strongly correlated with the beneficial regulation of physiological hormones and metabolic changes during pregnancy and lactation. These findings are key for guiding targeted microbial therapeutic approaches to modulate microbiomes in gestating and lactating mammals.

Something Smells Fishy: How Lipid Mediators Impact the Maternal-Fetal Interface and Neonatal Development

Normal pregnancy relies on inflammation for implantation, placentation, and parturition, but uncontrolled inflammation can lead to poor maternal and infant outcomes. Maternal diet is one modifiable factor that can impact inflammation. Omega-3 and -6 fatty acids obtained through the diet are metabolized into bioactive compounds that effect inflammation. Recent evidence has shown that the downstream products of omega-3 and -6 fatty acids may influence physiology during pregnancy. In this review, the current knowledge relating to omega-3 and omega-6 metabolites during pregnancy will be summarized.

Lipolysis-derived linoleic acid drives beige fat progenitor cell proliferation

De novo beige adipocyte biogenesis involves the proliferation of progenitor cells in white adipose tissue (WAT); however, what regulates this process remains unclear. Here, we report that in mouse models but also in human tissues, WAT lipolysis-derived linoleic acid triggers beige progenitor cell proliferation following cold acclimation, β3-adrenoceptor activation, and burn injury. A subset of adipocyte progenitors, as marked by cell surface markers PDGFRα or Sca1 and CD81, harbored cristae-rich mitochondria and actively imported linoleic acid via a fatty acid transporter CD36. Linoleic acid not only was oxidized as fuel in the mitochondria but also was utilized for the synthesis of arachidonic acid-derived signaling entities such as prostaglandin D2. Oral supplementation of linoleic acid was sufficient to stimulate beige progenitor cell proliferation, even under thermoneutral conditions, in a CD36-dependent manner. Together, this study provides mechanistic insights into how diverse pathophysiological stimuli, such as cold and burn injury, promote de novo beige fat biogenesis.

Inflammation with the participation of arachidonic (AA) and linoleic acid (LA) derivatives (HETEs and HODEs) is necessary in the course of a normal reproductive cycle and pregnancy

Data on arachidonic (AA) and linoleic (LA) acid derivatives and their role in the reproductive cycle are limited. In order to systematize these reports, 54 scientific investigations were analyzed, which revealed the important role of AA and LA in the planning and course of pregnancy. Ovulation, menstruation, pregnancy, and childbirth are strongly related to the occurrence of physiological inflammatory reactions. Ovulation and menstruation are cyclic tissue remodeling processes that cause changes in the synthesis of inflammation mediators, such as prostaglandins and leukotrienes. Thus, the cyclooxygenase (COX) and lipoxygenase-5 (5-LOX) pathway for AA transformation is activated. Only the absence of neutrophils during this process differentiates an embryo implantation from a standard inflammatory response. It has been found that in COX-2 deficiency conditions, incorrect embryo implantation and decidual reaction occur; therefore, the mechanism associated with the activation of the nuclear factor (NF)-κB pathway seems to play an important role in the course of embryo implantation. In addition, 12/15-LOX may be key modulators of uterine activity during the implantation process. According to the current state of knowledge, AA derivatives synthesized throughout the cytochrome P450 (CYP) and LOX pathways play a special role in the late pregnancy period. Decreased 5-HETE levels have been related to slowing down the progression of labor, while 11-HETE and 15-HETrE to its acceleration. It has been also proven that renal 20-HETE contents undergo significant changes in the late pregnancy period, which are caused by an increase in their adrenal medulla and vascular synthesis, leading to decrease of blood pressure and an increase of sodium excretion, finally conditioning a normal course of labor.

Automated mass spectrometry imaging of over 2000 proteins from tissue sections at 100-μm spatial resolution

Biological tissues exhibit complex spatial heterogeneity that directs the functions of multicellular organisms. Quantifying protein expression is essential for elucidating processes within complex biological assemblies. Imaging mass spectrometry (IMS) is a powerful emerging tool for mapping the spatial distribution of metabolites and lipids across tissue surfaces, but technical challenges have limited the application of IMS to the analysis of proteomes. Methods for probing the spatial distribution of the proteome have generally relied on the use of labels and/or antibodies, which limits multiplexing and requires a priori knowledge of protein targets. Past efforts to make spatially resolved proteome measurements across tissues have had limited spatial resolution and proteome coverage and have relied on manual workflows. Here, we demonstrate an automated approach to imaging that utilizes label-free nanoproteomics to analyze tissue voxels, generating quantitative cell-type-specific images for >2000 proteins with 100-µm spatial resolution across mouse uterine tissue sections preparing for blastocyst implantation.

Imaging mass spectrometry is a powerful emerging tool for mapping the spatial distribution of biomolecules across tissue surfaces. Here the authors showcase an automated technology for deep proteome imaging that utilizes ultrasensitive microfluidics and a mass spectrometry workflow to analyze tissue voxels, generating quantitative cell-type-specific images.

Prediction and associations of preterm birth and its subtypes with eicosanoid enzymatic pathways and inflammatory markers

Endogenous signaling molecules derived from lipids, peptides, and DNA, are important regulators of physiological processes during pregnancy. The effect of their collective impact on preterm birth (delivery < 37 weeks gestation) is understudied. We aimed to characterize the associations and predictive capacity of an extensive panel of eicosanoids, immune biomarkers, oxidative stress markers, and growth factors towards preterm birth and its subtypes. We conducted a cross-sectional study of pregnant women (recruited < 15 weeks gestation) in the LIFECODES birth cohort, which included 58 cases of preterm birth and 115 controls that delivered term. Among the cases there were 31 cases who had a spontaneous preterm birth (cases who had spontaneous preterm labor and/or preterm premature rupture of membranes) and 25 that had preterm birth associated with aberrant placentation (cases who had preeclampsia and/or intrauterine growth restriction) and 2 cases that could not be sufficiently categorized as either. We analyzed single biomarker associations with each preterm birth outcome using multiple logistic regression. Adaptive elastic-net was implemented to perform a penalized multiple logistic regression on all biomarkers simultaneously to identify the most predictive biomarkers. We then organized biomarkers into biological groups and by enzymatic pathways and applied adaptive elastic-net and random forest to evaluate the accuracy of each group for predicting preterm birth cases. The majority of associations we observed were for spontaneous preterm birth, and adaptive elastic-net identified 5-oxoeicosatetraenoic acid, resolvin D1, 5,6-epoxy-eicsatrienoic acid, and 15-deoxy-12,14-prostaglandin J2 as most predictive. Overall, lipid biomarkers performed the best at separating cases from controls compared to other biomarker categories (adaptive elastic-net AUC = 0.78 [0.62, 0.94], random forest AUC = 0.84 [0.72, 0.96]). Among the enzymatic pathways that differentiate eicosanoid metabolites, we observed the highest prediction of overall preterm birth by lipoxygenase metabolites using random forest (AUC = 0.83 [0.69, 0.96]), followed by cytochrome p450 metabolites using adaptive elastic-net (AUC = 0.74 [0.52, 0.96]). In this study we translate biological hypothesis into the language of modern machine learning. Many lipid biomarkers were highly associated with overall and spontaneous preterm birth. Among eicosanoids, lipoxygenase and cytochrome p450 products performed best in identifying overall and spontaneous preterm birth. The combination of lipid biomarkers may have good utility in clinical settings to predict preterm birth.

Endometrial expression of various genes (ISGs, PPARs, RXRs and MUC1) on day 16 post-ovulation in repeat breeder cows, with or without subclinical endometritis

Our objective was to elucidate differences in endometrial mRNA expressions of interferon-stimulated genes (ISG15, CTSL1, RSAD2, SLC2A1, CXCL10, and SLC27A6), peroxisome proliferator activated receptors (PPARA, PPARD, and PPARG), retinoic acid receptors (RXRA, RXRB, and RXRG), and mucin 1 (MUC1) in repeat breeder cows, with or without subclinical endometritis (RB + SE and RB, respectively) and normal cows on day 16 post-ovulation (n = 4 cows per group). The CXCL10 and SLC27A6 mRNA abundances were greater for normal cows compared to RB and RB + SE cows (P < 0.05 and P < 0.01 respectively) whereas ISG15 and SLC2A1 mRNA abundances were greater for normal cows compared to RB + SE (P < 0.05). The SLC27A6 mRNA abundances were greater for RB versus RB + SE (P < 0.01). Similarly, PPARD, PPARG, RXRA and RXRG mRNA abundances were greater for normal cows compared to RB and RB + SE (P < 0.01 and P < 0.05, respectively). Abundances of PPARD, PPARG, RXRA and RXRG mRNA were greater for RB versus RB + SE (P < 0.05) and MUC1 was lower in abundance in normal cows compared to RB or RB + SE (P < 0.05). Key predicted molecular functions were binding, signal transducer and transporter; key biological processes were cellular, localization and metabolic; key cellular components were cell part, membrane and organelle components; and key protein classes were nucleic acid binding, receptor, and transcription factors. Gene networking analysis highlighted interactions and pathways involving PAPRs, RXRs, and MUC1, notably among PPARD, PPARG, and MUC1. In conclusion, endometrial mRNA expressions of ISGs (CXCL10 and SLC27A6), PPAR isomers (PPARD and PPARG), and RXRs (RXRA and RXRG) were in lower abundances, whereas MUC1 expression was more abundant in RB or RB + SE compared to normal cows on day 16. In addition, ISG15 and SLC2A1 genes were less abundant in RB + SE versus RB or normal cows. Altered expression of these uterine genes and associated potential impairment in embryo elongation and implantation may promote embryonic loss in repeat breeder cows. Furthermore, interactions among PPARD, PPARG and MUC1 may be therapeutically exploitable.

Differential microRNA Expression in Porcine Endometrium Involved in Remodeling and Angiogenesis That Contributes to Embryonic Implantation

Background: In western swine breeds, up to 30% of embryonic losses occur during early pregnancy, and the majority of embryonic losses happens during implantation. In this period, maternal recognition of pregnancy begins to occur and blastocysts undergo dramatic morphologic changes. As with other species, changes in the uterine environment plays an important role in the process of embryo implantation in pigs. Erhualian (ER) pigs, one of the Chinese Taihu swine breeds, are known to have the highest litter size in the world. Experiments demonstrated that the greater embryonic survival on gestation day (GD) 12 in Chinese Taihu pigs is one important factor that contributes to enhanced litter size. This is largely controlled by maternal genes. In this study, endometrial samples were collected from pregnant Landrace×Large Yorkshire (LL) sows (parity 3) and ER sows (parity 3) on GD12 and the expression profiles of microRNAs (miRNAs) in the endometrium were compared between ER and LL using miRNA-seq technology. Results: A total of 288 miRNAs were identified in the pig endometrium, including 202 previously known and 86 novel miRNAs. The Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that highly abundant miRNAs might affect endometrial remodeling. Comparison between LL and ER sows revealed that 96 known miRNAs were differentially expressed between the two groups (including 78 up-regulated and 18 down-regulated miRNAs in ER compared to LL). Bioinformatics analysis showed that the target genes of some differentially expressed miRNAs were involved in pathways related to angiogenesis, proliferation, apoptosis, and tissue remodeling, which play critical roles in implantation by regulating endometrial structural changes and secretions of hormones, growth factors, and nutrients. Furthermore, the results demonstrated that insulin-like growth factor-1 protein expression was directly inhibited by miR-206. The lower expression of miR-206 in ER compared to LL might facilitate the angiogenesis of the endometrium during embryo implantation. Conclusions: The identified miRNAs that are differentially expressed in the endometrium of ER and LL pigs will contribute to the understanding of the role of miRNAs in embryonic implantation and the molecular mechanisms of the highest embryonic survival in Chinese ER pigs.

Msx Homeobox Genes Act Downstream of BMP2 to Regulate Endometrial Decidualization in Mice and in Humans

Endometrial stromal cells differentiate to form decidual cells in a process known as decidualization, which is critical for embryo implantation and successful establishment of pregnancy. We previously reported that bone morphogenetic protein 2 (BMP2) mediates uterine stromal cell differentiation in mice and in humans. To identify the downstream target(s) of BMP2 signaling during decidualization, we performed gene-expression profiling of mouse uterine stromal cells, treated or not treated with recombinant BMP2. Our studies revealed that expression of Msx2, a member of the mammalian Msx homeobox gene family, was markedly upregulated in response to exogenous BMP2. Interestingly, conditional ablation of Msx2 in the uterus failed to prevent a decidual phenotype, presumably because of functional compensation of Msx2 by Msx1, a closely related member of the Msx family. Indeed, in Msx2-null uteri, the level of Msx1 expression in the stromal cells was markedly elevated. When conditional, tissue-specific ablation of both Msx1 and Msx2 was accomplished in the mouse uterus, a dramatically impaired decidual response was observed. In the absence of both Msx1 and Msx2, uterine stromal cells were able to proliferate, but they failed to undergo terminal differentiation. In parallel experiments, addition of BMP2 to human endometrial stromal cell cultures led to a robust enhancement of MSX1 and MSX2 expression and stimulated the differentiation process. Attenuation of MSX1 and MSX2 expression by small interfering RNAs greatly reduced human stromal differentiation in vitro, indicating a conservation of their roles as key mediators of BMP2-induced decidualization in mice and women.

The pre-hatching bovine embryo transforms the uterine luminal metabolite composition in vivo

In cattle, conceptus development after elongation relies on well-characterized, paracrine interactions with the hosting maternal reproductive tract. However, it was unrecognized previously that the pre-hatching, pre-implantation bovine embryo also engages in biochemical signalling with the maternal uterus. Our recent work showed that the embryo modified the endometrial transcriptome in vivo. Here, we hypothesized that the embryo modulates the biochemical composition of the uterine luminal fluid (ULF) in the most cranial portion of the uterine horn ipsilateral to the corpus luteum. Endometrial samples and ULF were collected post-mortem from sham-inseminated cows and from cows inseminated and detected pregnant 7 days after oestrus. We used quantitative mass spectrometry to demonstrate that the pre-hatching embryo changes ULF composition in vivo. Embryo-induced modulation included an increase in concentrations of lipoxygenase-derived metabolites [12(S)-HETE, 15(S)-HETE] and a decrease in the concentrations of amino acids (glycine), biogenic amines (sarcosine), acylcarnitines and phospholipids. The changed composition of the ULF could be due to secretion or depletion of specific molecules, executed by either the embryo or the endometrium, but initiated by signals coming from the embryo. This study provides the basis for further understanding embryo-initiated modulation of the uterine milieu. Early embryonic signalling may be necessary to guarantee optimal development and successful establishment of pregnancy in cattle.

Progesterone alters the bovine uterine fluid lipidome during the period of elongation

Successful bovine pregnancy establishment hinges on conceptus elongation, a key reproductive phenomenon coinciding with the period during which most pregnancies fail. Elongation is yet to be recapitulated in vitro, whereas in vivo it is directly driven by uterine secretions and indirectly influenced by prior circulating progesterone levels. To better understand the microenvironment evolved to facilitate this fundamental developmental event, uterine fluid was recovered on Days 12–14 of the oestrous cycle – the window of conceptus elongation initiation – from cycling heifers supplemented, or not, with progesterone. Subsequent lipidomic profiling of uterine luminal fluid by advanced high-throughput metabolomics revealed the consistent presence of 75 metabolites, of which 47% were intricately linked to membrane biogenesis, and with seven displaying a day by progesterone interaction (P ≤ 0.05). Four metabolic pathways were correspondingly enriched according to day and P4 – i.e. comprised metabolites whose concentrations differed between groups (normal vs high P4) at different times (Days 12 vs 13 vs 14). These were inositol, phospholipid, glycerolipid and primary bile acid metabolism. Moreover, P4 elevated total uterine luminal fluid lipid content on Day 14 (P < 0.0001) relative to all other comparisons. The data combined suggest that maternal lipid supply during the elongation-initiation window is primarily geared towards conceptus membrane biogenesis. In summary, progesterone supplementation alters the lipidomic profile of bovine uterine fluid during the period of conceptus elongation initiation.

The role of the 12(S)-HETE/GPR31/12-HETER axis in cancer and ischemia-reperfusion injury

The G protein-coupled receptors (GPCRs) constitute a large superfamily of seven transmembrane-spanning receptors that are activated by several classes of ligands, including bioactive lipids. GPCRs are attractive therapeutic targets for the treatment of human diseases, as they finely regulate a wide array of cellular functions. In this minireview, we summarized what is currently known about the G protein-coupled receptor GPR31/12-HETER. We highlighted, in particular, its structural similarity with human homologs, the biological functions of its recognized ligand 12(S)-hydroxyeicosatetraenoic acid (HETE), an arachidonic acid metabolite, and the role that GPR31/12-HETER-mediated signals play in cancer cell growth, invasion and metastasis, and in liver ischemia-reperfusion (IR) injury. Recent studies shed light and interest on the 12(S)-HETE/GPR31/12-HETER-activated signaling pathways and functions. The full spectrum of GPR31/12-HETER-mediated biological functions has yet to be characterized. Further studies are needed to identify other potential ligands, i.e. other than 12(S)-HETE. Another important remaining question is whether the multiple 12(S)-HETE-induced biological activities, including its role in diabetes, neurodegeneration, neuroprotection, and platelet function, occur via GPR31/12-HETER and/or involve the activation of other receptor molecules and pathways.

Aberrantly high expression of the CUB and zona pellucida-like domain-containing protein 1 (CUZD1) in mammary epithelium leads to breast tumorigenesis

The peptide hormone prolactin (PRL) and certain members of the epidermal growth factor (EGF) family play central roles in mammary gland development and physiology, and their dysregulation has been implicated in mammary tumorigenesis. Our recent studies have revealed that the CUB and zona pellucida-like domain-containing protein 1 (CUZD1) is a critical factor for PRL-mediated activation of the transcription factor STAT5 in mouse mammary epithelium. Of note, CUZD1 controls production of a specific subset of the EGF family growth factors and consequent activation of their receptors. Here, we found that consistent with this finding, CUZD1 overexpression in non-transformed mammary epithelial HC11 cells increases their proliferation and induces tumorigenic characteristics in these cells. When introduced orthotopically in mouse mammary glands, these cells formed adenocarcinomas, exhibiting elevated levels of STAT5 phosphorylation and activation of the EGF signaling pathway. Selective blockade of STAT5 phosphorylation by pimozide, a small-molecule inhibitor, markedly reduced the production of the EGF family growth factors and inhibited PRL-induced tumor cell proliferation in vitro Pimozide administration to mice also suppressed CUZD1-driven mammary tumorigenesis in vivo Analysis of human MCF7 breast cancer cells indicated that CUZD1 controls the production of the same subset of EGF family members in these cells as in the mouse. Moreover, pimozide treatment reduced the proliferation of these cancer cells. Collectively, these findings indicate that overexpression of CUZD1, a regulator of growth factor pathways controlled by PRL and STAT5, promotes mammary tumorigenesis. Blockade of the STAT5 signaling pathway downstream of CUZD1 may offer a therapeutic strategy for managing these breast tumors.

CUZD1 is a critical mediator of the JAK/STAT5 signaling pathway that controls mammary gland development during pregnancy

In the mammary gland, genetic circuits controlled by estrogen, progesterone, and prolactin, act in concert with pathways regulated by members of the epidermal growth factor family to orchestrate growth and morphogenesis during puberty, pregnancy and lactation. However, the precise mechanisms underlying the crosstalk between the hormonal and growth factor pathways remain poorly understood. We have identified the CUB and zona pellucida-like domain-containing protein 1 (CUZD1), expressed in mammary ductal and alveolar epithelium, as a novel mediator of mammary gland proliferation and differentiation during pregnancy and lactation. Cuzd1-null mice exhibited a striking impairment in mammary ductal branching and alveolar development during pregnancy, resulting in a subsequent defect in lactation. Gene expression profiling of mammary epithelium revealed that CUZD1 regulates the expression of a subset of the EGF family growth factors, epiregulin, neuregulin-1, and epigen, which act in an autocrine fashion to activate ErbB1 and ErbB4 receptors. Proteomic studies further revealed that CUZD1 interacts with a complex containing JAK1/JAK2 and STAT5, downstream transducers of prolactin signaling in the mammary gland. In the absence of CUZD1, STAT5 phosphorylation in the mammary epithelium during alveologenesis was abolished. Conversely, elevated expression of Cuzd1 in mammary epithelial cells stimulated prolactin-induced phosphorylation and nuclear translocation of STAT5. Chromatin immunoprecipitation confirmed co-occupancy of phosphorylated STAT5 and CUZD1 in the regulatory regions of epiregulin, a potential regulator of epithelial proliferation, and whey acidic protein, a marker of epithelial differentiation. Collectively, these findings suggest that CUZD1 plays a critical role in prolactin-induced JAK/STAT5 signaling that controls the expression of key STAT5 target genes involved in mammary epithelial proliferation and differentiation during alveolar development.

In the mammary gland, genetic circuits controlled by the hormones, estrogen, progesterone and prolactin, act in concert with pathways regulated by members of the epidermal growth factor family to orchestrate growth and morphogenesis during puberty, pregnancy and lactation. We have identified CUZD1 as a novel mediator of prolactin signaling in the steroid hormone-primed mouse mammary gland during pregnancy and lactation. Cuzd1-null mice exhibited a striking impairment in ductal branching and alveolar development during pregnancy, resulting in a subsequent defect in lactation. Administration of prolactin failed to induce proliferation of the mammary epithelium in Cuzd1-null mice. Protein binding studies revealed that CUZD1 interacts with downstream transducers of prolactin signaling, JAK1/JAK2 and STAT5. Additionally, elevated expression of Cuzd1 in mammary epithelial cells stimulated phosphorylation and nuclear translocation of STAT5. CUZD1, therefore, is a critical mediator of prolactin that controls mammary alveolar development.

Activation of peroxisome proliferator-activated receptor-γ by a 12/15-lipoxygenase product of arachidonic acid: a possible neuroprotective effect in the brain after experimental intracerebral hemorrhage

OBJECTIVE In this study, the authors investigated the involvement of 15( S)-hydroxyeicosatetraenoic acid (15(S)-HETE) in the regulation of peroxisome proliferator-activated receptor-γ (PPARγ) after intracerebral hemorrhage (ICH) and its effects on hemorrhage-induced inflammatory response and oxidative stress in an experimental rodent model. METHODS To simulate ICH in a rat model, the authors injected autologous whole blood into the right striatum of male Sprague-Dawley rats. The distribution and expression of 12/15-lipoxygenase (12/15-LOX) were determined by immunohistochemistry and Western blot analysis, respectively. Immunofluorescent double labeling was used to study the cellular localization of 12/15-LOX, and 15(S)-HETE was measured with a 15(S)-HETE enzyme immunoassay kit. Neurological deficits in the animals were assessed through behavioral testing, and apoptotic cell death was determined with terminal deoxynucleotidyl transferase-mediated biotinylated dUTP nick-end labeling. RESULTS Rats with ICH had increased expression of 12/15-LOX predominantly in neurons and also in oligodendrocytes, astrocytes, and microglia. Moreover, ICH elevated production of 15(S)-HETE in the brain area ipsilateral to the blood injection. The PPARγ agonist, exogenous 15(S)-HETE, significantly increased PPARγ protein levels and increased PPARγ-regulated gene (i.e., catalase) expression in the ICH rats. Reduced expression of the gene for the proinflammatory protein nuclear factor κB coincided with decreased neuron damage and improved functional recovery from ICH. A PPARγ antagonist, GW9662, reversed the effects of exogenous 15(S)-HETE on the PPARγ-regulated genes. CONCLUSIONS The induction of 15(S)-HETE during simulated ICH suggests generation of endogenous signals of neuroprotection. The effects of exogenous 15(S)-HETE on brain hemorrhage-induced inflammatory responses and oxidative stress might be mediated via PPARγ.

Chronic Exposure to Bisphenol A Affects Uterine Function During Early Pregnancy in Mice

Environmental and occupational exposure to bisphenol A (BPA), a chemical widely used in polycarbonate plastics and epoxy resins, has received much attention in female reproductive health due to its widespread toxic effects. Although BPA has been linked to infertility and recurrent miscarriage in women, the impact of its exposure on uterine function during early pregnancy remains unclear. In this study, we addressed the effect of prolonged exposure to an environmental relevant dose of BPA on embryo implantation and establishment of pregnancy. Our studies revealed that treatment of mice with BPA led to improper endometrial epithelial and stromal functions thus affecting embryo implantation and establishment of pregnancy. Upon further analyses, we found that the expression of progesterone receptor (PGR) and its downstream target gene, HAND2 (heart and neural crest derivatives expressed 2), was markedly suppressed in BPA-exposed uterine tissues. Previous studies have shown that HAND2 controls embryo implantation by repressing fibroblast growth factor and the MAPK signaling pathways and inhibiting epithelial proliferation. Interestingly, we observed that down-regulation of PGR and HAND2 expression in uterine stroma upon BPA exposure was associated with enhanced activation of fibroblast growth factor and MAPK signaling in the epithelium, thus contributing to aberrant proliferation and lack of uterine receptivity. Further, the differentiation of endometrial stromal cells to decidual cells, an event critical for the establishment and maintenance of pregnancy, was severely compromised in response to BPA. In summary, our studies revealed that chronic exposure to BPA impairs PGR-HAND2 pathway and adversely affects implantation and the establishment of pregnancy.

Progesterone rapidly down-regulates the biosynthesis of 5-lipoxygenase products in human primary monocytes

5-Lipoxygenase (5-LO), the key enzyme in the biosynthesis of pro-inflammatory leukotrienes (LTs) from arachidonic acid, is regulated by androgens in human neutrophils and monocytes accounting for sex differences in LT formation. Here we show that progesterone suppresses the synthesis of 5-LO metabolites in human primary monocytes. 5-LO product formation in monocytes stimulated with Ca(2+)-ionophore A23187 or with lipopolysaccharide/formyl peptide was suppressed by progesterone at concentrations of 10-100 nM in cells from females and at 1 μM in cells from males. Progesterone down-regulated 5-LO product formation in a rapid and reversible manner, but did not significantly inhibit 5-LO activity in cell-free assays using monocyte homogenates. Also, arachidonic acid release and its metabolism to other eicosanoids in monocytes were not significantly reduced by progesterone. The inhibitory effect of progesterone on LTs was still observed when mitogen-activated protein kinases were pharmacologically blocked, stimulatory 1-oleoyl-2-acetyl-sn-glycerol was exogenously supplied, or extracellular Ca(2+) was removed by chelation. Instead, suppression of PKA by means of two different pharmacological approaches (i.e. H89 and a cell-permeable PKA inhibitor peptide) prevented inhibition of 5-LO product generation by progesterone, to a similar extent as observed for the PKA activators prostaglandin E2 and 8-Br-cAMP, suggesting the involvement of PKA. In summary, progesterone affects the capacity of human primary monocytes to generate 5-LO products and, in addition to androgens, may account for sex-specific effects on pro-inflammatory LTs.

12/15-Lipoxygenase metabolites of arachidonic acid activate PPARγ: a possible neuroprotective effect in ischemic brain

The enzyme 12/15-lipoxygenase (LOX) oxidizes various free fatty acids, including arachidonic acid (AA). In the brain, the principal 12/15-LOX metabolites of AA are 12(S)-HETE and 15(S)-HETE. PPARγ is a nuclear receptor whose activation is neuroprotective through its anti-inflammatory properties. In this study, we investigate the involvement of 12(S)- and 15(S)-HETE in the regulation of PPARγ following cerebral ischemia and their effects on ischemia-induced inflammatory response. We show here the increased expression of 12/15-LOX, predominantly in neurons, and elevated production of 12(S)-HETE and 15(S)-HETE in ischemic brain. The exogenous 12(S)- and 15(S)-HETE increase PPARγ protein level, nuclear translocation, and DNA-binding activity in ischemic rats, suggesting the activation of PPARγ. This effect was further confirmed by showing the increased PPARγ transcriptional activity in primary cortical neurons when incubated with 12(S)- or 15(S)-HETE. Moreover, both 12(S)- and 15(S)-HETE potently inhibited the induction of nuclear factor-κB, inducible NO synthase, and cyclooxygenase-2 in ischemic rats, and elicited neuroprotection. The reversal of the effects of 12(S)- and 15(S)-HETE on pro-inflammatory factors by PPARγ antagonist GW9662 indicated their actions were mediated via PPARγ. Thus, the induction of 12(S)- and 15(S)-HETE during brain ischemia suggests that endogenous signals of neuroprotection may be generated.

Activation of PPARγ by 12/15-lipoxygenase during cerebral ischemia-reperfusion injury

Peroxisome proliferator-activated receptor γ (PPARγ) expression and activity are increased in brain ischemic injury and its agonists have shown potential for brain injury protection. The influence of 12/15-lipoxygenase (12/15-LOX) on the activity of PPARγ in oxygen-glucose deprivation (OGD) and ischemia-reperfusion (I/R) was investigated. A middle cerebral artery occlusion/reperfusion model with Sprague Dawley (SD) rats was established. For I/R intervention, the rats were treated with the 12/15-LOX-derived product 12-hydroxyeicosatetraenoic acid (12-HETE) for 30 min before cerebral artery occlusion. Primary cortical neurons from SD rats were used to establish an OGD cell model. 12-HETE or a 12/15-LOX antisense oligonucleotide (asON-12/15-LOX) was added to OGD-treated neurons. Western blots, immunofluorescence and enzyme-linked immunosorbent assays detected protein. Reverse transcription-polymerase chain reaction analyzed the expression of the PPARγ target genes. PPARγ-DNA binding activity was determined by peroxisome proliferator responsive element luciferase reporter vectors. 12/15-LOX total protein increased significantly with I/R, and expression of 12-HETE was also upregulated. 12-HETE treatment increased PPARγ protein expression and inhibited inducible nitric oxide synthase protein expression, which was upregulated with I/R. PPARγ nuclear protein and 12/15-LOX total protein expression in OGD-treated neurons increased significantly. 12-HETE treatment increased the expression of PPARγ nuclear protein, upregulated the mRNA levels of PPARγ target genes (lipoprotein lipase and acyl-CoA oxidase) and enhanced PPARγ-DNA binding activity. asON-12/15-LOX treatment inhibited 12/15-LOX and PPARγ protein expression and lipoprotein lipase mRNA. Cerebral I/R injury in rats and OGD treatment in neurons promoted 12/15-LOX expression, and 12-HETE activated PPARγ. Therefore, PPARγ can be activated by the 12/15-LOX pathway during cerebral I/R injury.

Dysregulated estrogen receptor signaling in the hypothalamic-pituitary-ovarian axis leads to ovarian epithelial tumorigenesis in mice

The etiology of ovarian epithelial cancer is poorly understood, mainly due to the lack of an appropriate experimental model for studying the onset and progression of this disease. We have created a mutant mouse model in which aberrant estrogen receptor alpha (ERα) signaling in the hypothalamic-pituitary-ovarian axis leads to ovarian epithelial tumorigenesis. In these mice, termed ERα^d/d, the ERα gene was conditionally deleted in the anterior pituitary, but remained intact in the hypothalamus and the ovary. The loss of negative-feedback regulation by estrogen (E) at the level of the pituitary led to increased production of luteinizing hormone (LH) by this tissue. Hyperstimulation of the ovarian cells by LH resulted in elevated steroidogenesis, producing high circulating levels of steroid hormones, including E. The ERα^d/d mice exhibited formation of palpable ovarian epithelial tumors starting at 5 months of age with 100% penetrance. By 15 months of age, 80% of ERα^d/d mice die. Besides proliferating epithelial cells, these tumors also contained an expanded population of luteinized stromal cells, which acquire the ability to express P450 aromatase and synthesize E locally. In response to the elevated levels of E, the ERα signaling was accentuated in the ovarian epithelial cells of ERα^d/d mice, triggering increased ERα-dependent gene expression, abnormal cell proliferation, and tumorigenesis. Consistent with these findings, treatment of ERα^d/d mice with letrozole, an aromatase inhibitor, markedly reduced circulating E and ovarian tumor volume. We have, therefore, developed a unique animal model, which serves as a useful tool for exploring the involvement of E-dependent signaling pathways in ovarian epithelial tumorigenesis.

Ovarian cancer is currently the most lethal gynecological cancer in the United States. Multiple epidemiological studies indicate that women who take hormone replacement therapy, estrogen or estrogen with progesterone, peri- or postmenopause will have an increased chance of developing ovarian cancer. Unfortunately, the five-year survival rate after diagnosis is very low indicating that better tools are needed to diagnose and treat ovarian cancer. The models that would allow investigation of this disease are severely limited. In this article we introduce a mouse model that develops epithelial ovarian tumors, and by employing inhibitors of estrogen synthesis, we show that ovarian tumorigenesis in this model is dependent on estrogen production within the ovarian tumor. These studies suggest that estrogen may play a role in promoting ovarian tumor growth.

Interactions between α-tocopherol, polyunsaturated fatty acids, and lipoxygenases during embryogenesis

α-Tocopherol is a lipid-soluble antioxidant that is specifically required for reproduction and embryogenesis. However, since its discovery, α-tocopherol's specific biologic functions, other than as an antioxidant, and the mechanism(s) mediating its requirement for embryogenesis remain unknown. As an antioxidant, α-tocopherol protects polyunsaturated fatty acids (PUFAs) from lipid peroxidation. α-Tocopherol is probably required during embryonic development to protect PUFAs that are crucial to development, specifically arachidonic (ARA) and docosahexaenoic (DHA) acids. Additionally, ARA and DHA are metabolized to bioactive lipid mediators via lipoxygenase enzymes, and α-tocopherol may directly protect, or it may mediate the production and/or actions of, these lipid mediators. In this review, we discuss how α-tocopherol (1) prevents the nonspecific, radical-mediated peroxidation of PUFAs, (2) functions within a greater antioxidant network to modulate the production and/or function of lipid mediators derived from 12- and 12/15-lipoxygenases, and (3) modulates 5-lipoxygenase activity. The application and implication of such interactions are discussed in the context of α-tocopherol requirements during embryogenesis.

The effect of embryo presence on the expression of peroxisome proliferator activated receptor (PPAR) genes in the porcine reproductive system during periimplantation

This study was undertaken to determine the effect of the presence of embryos in the uterine horn on peroxisome proliferator activated receptors (PPARs; A, D, G) gene expression in the reproductive tissues of gilts subjected to a surgical procedure. The uterus consisted of one intact horn connected to the uterine corpus and the second horn detached from the uterine corpus but connected with the contiguous ovary. The gilts were hormonally stimulated and divided into two groups: the first group, inseminated (pregnant) and the second group (cyclic), with surgical procedure but not inseminated. The animals of both groups were slaughtered on day 14 of pregnancy or on day 14 of the oestrous cycle, respectively. PPARs mRNA abundance in the endometrium and the corpus luteum (CL) was analysed by quantitative real-time PCR. During pregnancy, PPARA and PPARD μmRNA abundance in the porcine endometrium was significantly higher in the horn containing embryos than in the contralateral horn, where embryos were absent. The endometrial PPARG1 mRNA abundance did not differ between the two horns during pregnancy and the oestrous cycle, but a higher level of the transcript was observed during pregnancy when compared to the oestrous cycle. In the CL, there were no significant differences in PPARA and PPARDμ mRNA abundance between horns in pregnant or cyclic sows. However, there was a significant increase of PPARA and PPARD transcript level in the CL from cyclic compared with pregnant sows. The results of our study suggest that PPARA and PPARD have regulatory functions in early pregnancy, and they indicate that increased levels of endometrial gene expression are correlated with the presence of embryos in the uterine horn. Higher levels of PPARA and PPARD expression in the porcine CL on day 14 of the oestrous cycle than on day 14 of pregnancy suggest that both forms are involved in the regulation of CL functions.

The role of lipoxin A4 in endometrial biology and endometriosis

Lipoxin A4 (LXA4), an endogenous anti-inflammatory and immunomodulatory mediator studied in many disease states, is recently appreciated as a potentially significant player in the endometrium. This eicosanoid, synthesized from arachidonic acid via the action of lipoxygenase enzymes, is likely regulated in endometrial tissue during the menstrual cycle. Recent studies revealed that LXA4 acts as an estrogen receptor agonist in endometrial epithelial cells, antagonizing some estrogen-mediated activities in a manner similar to the weak estrogen estriol, with which it shares structural similarity. LXA4 may also be an anti-inflammatory molecule in the endometrium, though its precise function in various physiological and pathological scenarios remains to be determined. The expression patterns for LXA4 and its receptor in the female reproductive tract suggest a role in pregnancy. The present review provides an oversight of its known and putative roles in the context of immuno-endocrine crosstalk. Endometriosis, a common inflammatory condition and a major cause of infertility and pain, is currently treated by surgery or anti-hormone therapies that are contraceptive and associated with undesirable side effects. LXA4 may represent a potential therapeutic and further research to elucidate its function in endometrial tissue and the peritoneal cavity will undoubtedly provide valuable insights.

Baicalein reduces airway injury in allergen and IL-13 induced airway inflammation

Background

Baicalein, a bioflavone present in the dry roots of Scutellaria baicalensis Georgi, is known to reduce eotaxin production in human fibroblasts. However, there are no reports of its anti-asthma activity or its effect on airway injury.

Methodology/Principal Findings

In a standard experimental asthma model, male Balb/c mice that were sensitized with ovalbumin (OVA), treated with baicalein (10 mg/kg, ip) or a vehicle control, either during (preventive use) or after OVA challenge (therapeutic use). In an alternate model, baicalein was administered to male Balb/c mice which were given either IL-4 or IL-13 intranasally. Features of asthma were determined by estimating airway hyperresponsiveness (AHR), histopathological changes and biochemical assays of key inflammatory molecules. Airway injury was determined with apoptotic assays, transmission electron microscopy and assessing key mitochondrial functions. Baicalein treatment reduced AHR and inflammation in both experimental models. TGF-β₁, sub-epithelial fibrosis and goblet cell metaplasia, were also reduced. Furthermore, baicalein treatment significantly reduced 12/15-LOX activity, features of mitochondrial dysfunctions, and apoptosis of bronchial epithelia.

Conclusion/Significance

Our findings demonstrate that baicalein can attenuate important features of asthma, possibly through the reduction of airway injury and restoration of mitochondrial function.

Neonatal diethylstilbestrol exposure alters the metabolic profile of uterine epithelial cells

Developmental exposure to diethylstilbestrol (DES) causes reproductive tract malformations, affects fertility and increases the risk of clear cell carcinoma of the vagina and cervix in humans. Previous studies on a well-established mouse DES model demonstrated that it recapitulates many features of the human syndrome, yet the underlying molecular mechanism is far from clear. Using the neonatal DES mouse model, the present study uses global transcript profiling to systematically explore early gene expression changes in individual epithelial and mesenchymal compartments of the neonatal uterus. Over 900 genes show differential expression upon DES treatment in either one or both tissue layers. Interestingly, multiple components of peroxisome proliferator-activated receptor-γ (PPARγ)-mediated adipogenesis and lipid metabolism, including PPARγ itself, are targets of DES in the neonatal uterus. Transmission electron microscopy and Oil-Red O staining further demonstrate a dramatic increase in lipid deposition in uterine epithelial cells upon DES exposure. Neonatal DES exposure also perturbs glucose homeostasis in the uterine epithelium. Some of these neonatal DES-induced metabolic changes appear to last into adulthood, suggesting a permanent effect of DES on energy metabolism in uterine epithelial cells. This study extends the list of biological processes that can be regulated by estrogen or DES, and provides a novel perspective for endocrine disruptor-induced reproductive abnormalities.

Estrogen-induced expression of Fos-related antigen 1 (FRA-1) regulates uterine stromal differentiation and remodeling

Concerted actions of estrogen and progesterone via their cognate receptors orchestrate changes in the uterine tissue, regulating implantation during early pregnancy. The uterine stromal cells undergo steroid-dependent differentiation into morphologically and functionally distinct decidual cells, which support embryonic growth and survival. The hormone-regulated pathways underlying this unique cellular transformation are not fully understood. Previous studies in the mouse revealed that, following embryo attachment, de novo synthesis of estrogen by the decidual cells is critical for stromal differentiation. In this study we report that Fos-related antigen 1 (FRA-1), a member of the Fos family of transcription factors, is a downstream target of regulation by intrauterine estrogen. FRA-1 expression was localized in the differentiating uterine stromal cells surrounding the implanted embryo. Attenuation of estrogen receptor α (Esr1) expression by siRNA mediated silencing in primary uterine stromal cells suppressed FRA-1 expression. Furthermore, chromatin immunoprecipitation demonstrated direct recruitment of ESR1 to an estrogen response element in the Fra-1 promoter. Down-regulation of Fra-1 expression during in vitro decidualization blocked stromal differentiation and resulted in a marked decrease in stromal cell migration. Interestingly, FRA-1 controls the expression of matrix metalloproteinases MMP9 and MMP13, which are critical modulators of stromal extracellular matrix remodeling. Collectively, these results suggest that FRA-1, induced in response to estrogen signaling via ESR1, is a key regulator of stromal differentiation and remodeling during early pregnancy.

Estrogen stimulates Th2 cytokine production and regulates the compartmentalisation of eosinophils during allergen challenge in a mouse model of asthma

BACKGROUND

The observation that asthma becomes more prevalent following puberty in females suggests estrogen potentiates the development of this disease. However, most studies examining the role of estrogen in rodent models of asthma are complicated by their reliance on ovariectomised mice in which hormones other than estrogen are also attenuated.

METHODS

We aimed to understand the influence of estrogen on allergic airway disease by using type I (tamoxifen) or type II (ICI 182,780) antagonists in female mice or delivering estradiol to male mice during aeroallergen challenge.

RESULTS

The antagonists showed that estrogen promoted both the mobilisation of bone marrow eosinophils and egression of eosinophils to the airway lumen. These findings were corroborated in male mice treated with estradiol, which increased eosinophil numbers in both blood and airways. Estrogen stimulated goblet cell hyperplasia and baseline lung resistance, but had little effect on the number of eosinophils in the bronchial submucosa or methacholine-induced airway hyperreactivity. Estrogen receptor α was expressed by CD4+ T cells from allergic mice, and estrogen promoted the production of IL-5 and IL-13, and suppressed the production of the eicosanoid 12-HETE by mediastinal lymph node cells.

CONCLUSIONS

These data show that during aeroallergen challenge, estrogen stimulates Th2 cytokine production, which may be linked to its ability to suppress 12-HETE. Lung resistance at baseline, goblet cell hyperplasia and the compartmentalisation of eosinophils was also influenced by estrogen. However, estrogen does not play a major role in stimulating enhanced sensitivity to methacholine-induced lung resistance.

Msx homeobox genes critically regulate embryo implantation by controlling paracrine signaling between uterine stroma and epithelium

The mammalian Msx homeobox genes, Msx1 and Msx2, encode transcription factors that control organogenesis and tissue interactions during embryonic development. We observed overlapping expression of these factors in uterine epithelial and stromal compartments of pregnant mice prior to embryo implantation. Conditional ablation of both Msx1 and Msx2 in the uterus resulted in female infertility due to a failure in implantation. In these mutant mice (Msx1/2^d/d), the uterine epithelium exhibited persistent proliferative activity and failed to attach to the embryos. Gene expression profiling of uterine epithelium and stroma of Msx1/2^d/d mice revealed an elevated expression of several members of the Wnt gene family in the preimplantation uterus. Increased canonical Wnt signaling in the stromal cells activated β-catenin, stimulating the production of a subset of fibroblast growth factors (FGFs) in these cells. The secreted FGFs acted in a paracrine manner via the FGF receptors in the epithelium to promote epithelial proliferation, thereby preventing differentiation of this tissue and creating a non-receptive uterus refractory to implantation. Collectively, these findings delineate a unique signaling network, involving Msx1/2, Wnts, and FGFs, which operate in the uterus at the time of implantation to control the mesenchymal-epithelial dialogue critical for successful establishment of pregnancy.

During implantation, various tissue compartments within the uterus, including epithelium and stroma, undergo sequential proliferation and differentiation as the embryo attaches to the uterus and invades into the maternal tissue. There is only limited understanding of the molecular signaling pathways that interconnect these tissue compartments to achieve a functional state of the uterus conducive to implantation. This study reveals that a unique signaling network regulated by the homeobox transcription factors MSX1 and MSX2 in the mouse uterus critically controls female fertility. Targeted mutation of Msx1 and Msx2 genes in female mice, which results in infertility, established that these factors suppress signaling by the morphogenic ligands, WNTS, in the uterus. In the absence of Msx1 and Msx2, the WNT signaling is elevated, leading to the production of a subset of fibroblast growth factors (FGFs) in uterine stroma. These FGFs act in a paracrine manner on the uterine epithelium to promote epithelial proliferation, which results in lack of uterine receptivity and implantation failure. This work, therefore, uncovers an important mechanism in mammalian reproduction and development by identifying key paracrine signals that arise from the uterine stroma to control epithelial function during implantation.

Lipoxin A4 is a novel estrogen receptor modulator

Inflammation is intimately linked with naturally occurring remodeling events in the endometrium. Lipoxins comprise a group of short-lived, nonclassic eicosanoids possessing potent anti-inflammatory and proresolution properties. In the present study, we investigated the role of lipoxin A(4) (LXA(4)) in the endometrium and demonstrated that 15-LOX-2, an enzyme necessary for LX biosynthesis, is expressed in this tissue. Our results establish that LXA(4) possesses robust estrogenic activity through its capacity to alter ERE transcriptional activity, as well as expression of estrogen-regulated genes, alkaline phosphatase activity, and proliferation in human endometrial epithelial cells. Interestingly, LXA(4) also demonstrated antiestrogenic potential, significantly attenuating E2-induced activity. This estrogenic activity was directly mediated through estrogen receptors (ERs). Subsequent investigations determined that the actions of LXA(4) are exclusively mediated through ERα and closely mimic those of the potent estrogen 17β-estradiol (E2). In binding assays, LXA(4) competed with E2 for ER binding, with an IC(50) of 46 nM. Furthermore, LXA(4) exhibited estrogenic activity in vivo, increasing uterine wet weight and modulating E2-regulated gene expression. These findings reveal a previously unappreciated facet of LXA(4) bioactions, implicating this lipid mediator in novel immunoendocrine crosstalk mechanisms.

Molecular regulators of resolution of inflammation: potential therapeutic targets in the reproductive system

Inflammatory processes are central to reproductive events including ovulation, menstruation, implantation and labour, while inflammatory dysregulation is a feature of numerous reproductive pathologies. In recent years, there has been much research into the endogenous mechanisms by which inflammatory reactions are terminated and tissue homoeostasis is restored, a process termed resolution. The identification and characterisation of naturally occurring pro-resolution mediators including lipoxins and annexin A1 has prompted a shift in the field of anti-inflammation whereby resolution is now observed as an active process, triggered as part of a normal inflammatory response. This review will address the process of resolution, discuss available evidence for expression of pro-resolution factors in the reproductive tract and explore possible roles for resolution in physiological reproductive processes and associated pathologies.

Zebrafish (Danio rerio) fed vitamin E-deficient diets produce embryos with increased morphologic abnormalities and mortality

Vitamin E (α-tocopherol) is required to prevent fetal resorption in rodents. To study α-tocopherol's role in fetal development, a nonplacental model is required. Therefore, the zebrafish, an established developmental model organism, was studied by feeding the fish a defined diet with or without added α-tocopherol. Zebrafish (age, 4-6 weeks) were fed the deficient (E-), sufficient (E+) or lab diet up to 1 years. All groups showed similar growth rates. The exponential rate of α-tocopherol depletion up to ~80 day in E- zebrafish was 0.029±0.006 nmol/g, equivalent to a depletion half-life of 25±5 days. From age ~80 days, the E- fish (5±3 nmol/g) contained ~50 times less α-tocopherol than the E+ or lab diet fish (369±131 or 362±107, respectively; P<.05). E-depleted adults demonstrated decreased startle response suggesting neurologic deficits. Expression of selected oxidative stress and apoptosis genes from livers isolated from the zebrafish fed the three diets were evaluated by quantitative polymerase chain reaction and were not found to vary with vitamin E status. When E-depleted adults were spawned, they produced viable embryos with depleted α-tocopherol concentrations. The E- embryos exhibited a higher mortality (P<.05) at 24 h post-fertillization and a higher combination of malformations and mortality (P<.05) at 120 h post-fertillization than embryos from parents fed E+ or lab diets. This study documents for the first time that vitamin E is essential for normal zebrafish embryonic development.

The CCAAT/enhancer binding protein beta is a critical regulator of steroid-induced mitotic expansion of uterine stromal cells during decidualization

During early pregnancy, the concerted actions of the maternal steroid hormones, estrogen and progesterone, promote a unique process known as decidualization, which involves extensive proliferation and differentiation of uterine stromal cells. The molecular pathways underlying this hormonally induced cellular transformation, an essential prerequisite for embryo implantation, remain poorly understood. We previously identified CCAAT/enhancer binding protein beta (C/EBPbeta) as a target of steroid regulation in the uterus. Uteri of mice lacking C/EBPbeta failed to undergo decidualization. In the present study, analyses of C/EBPbeta-null uteri indicated that loss of this factor leads to a block in stromal cell proliferation in response to a decidual stimulation. The mutant stromal cells entered S phase of the cell cycle and completed DNA synthesis but were unable to execute mitosis. Further analysis revealed that C/EBPbeta facilitates the transition of these cells into mitosis by binding directly to the cyclin B2 promoter to regulate its expression. The expression of cdc25C, a phosphatase that maintains the active state of the cyclin B-cyclin-dependent kinase complex during mitosis, is also strongly suppressed in C/EBPbeta-null stromal cells. Furthermore, the expression of the tumor suppressor p53 and the cell cycle inhibitors p21 and p27 was markedly elevated in C/EBPbeta-null stromal cells before the mitotic phase, uncovering additional mechanisms by which C/EBPbeta controls G2 to M transition. Collectively, these results revealed that C/EBPbeta mediates the effects of steroid hormones during decidualization by modulating the expression of multiple key cell cycle regulatory factors that control the G2 to M transition of the proliferating uterine stromal cells.

Peroxisome proliferator-activated receptor gamma activation inhibits progesterone-stimulated human MUC1 expression

Mucin 1 (MUC1) is a type I transmembrane glycoprotein abundantly expressed on nearly all epithelial tissues and overexpressed by many cancer cells. Previous studies from our lab showed that progesterone receptor (PR)B is a strong stimulator of MUC1 gene expression. It is reported that liganded peroxisome proliferator-activated receptor gamma (PPARgamma) stimulates Muc1 expression in murine trophoblast. Here, we demonstrate that although the PPARgamma ligand, rosiglitazone, stimulates the murine Muc1 promoter in HEC1A, a human uterine epithelial cell line, rosiglitazone alone, has no significant effect on basal human MUC1 promoter activity. In fact, rosiglitazone treatment antagonizes progesterone-stimulated human MUC1 promoter activity and protein expression in two human uterine epithelial cell lines and T47D human breast cancer cells. This response is antagonized by the PPARgamma antagonist, GW9662, as well as a dominant-negative form of PPARgamma, demonstrating the response is mediated by PPARgamma. Additional studies indicate that PPARgamma activation does not change PR binding to the MUC1 promoter but generally antagonizes progesterone activity by stimulating PRB degradation and inhibiting progesterone-induced PRB phosphorylation. Collectively, these studies indicate that PPARgamma activation inhibits PRB activity through both acute (phosphorylation) and long-term (PRB degradation) pathways.

The transcription factor C/EBPβ is a marker of uterine receptivity and expressed at the implantation site in the primate

During early pregnancy, the endometrium undergoes pronounced hormone-dependent functional changes in preparation for embryo implantation. Local autocrine-paracrine signaling at the fetal-maternal interface is crucial for the establishment of pregnancy. We previously reported that the transcription factor C/ EBPbeta, which is expressed at the implantation sites (ISs) in pregnant mice, acts as a key mediator of steroid hormone responsiveness in the endometrium. Mice lacking C/EBPbeta fail to support implantation due to defects in epithelial proliferation and stromal cell differentiation. In the current study, C/EBPbeta expression was dramatically stimulated in the endometrium of baboons (Papio anubis) during the window of uterine receptivity in response to a local infusion of chorionic gonadotropin, an embryonic signal. A robust induction of C/EBPbeta expression was also seen at the IS in the baboon and the human. Collectively, our results indicate that C/EBPbeta is a biomarker of endometrial receptivity and plays a conserved functional role during implantation in the primate.

Human transcriptional coactivator with PDZ-binding motif (TAZ) is downregulated during decidualization

Transcriptional coactivator with PDZ-binding motif (TAZ) is known to bind to a variety of transcription factors to control cell differentiation and organ development. However, its role in uterine physiology has not yet been described. To study its regulation during the unique process of differentiation of fibroblasts into decidual cells (decidualization), we utilized the human uterine fibroblast (HuF) in vitro cell model. Immunocytochemistry data demonstrated that the majority of the TAZ protein is localized in the nucleus. Treatment of HuF cells with the embryonic stimulus cytokine interleukin 1 beta in the presence of steroid hormones (estradiol-17 beta and medroxyprogesterone acetate) for 13 days did not cause any apparent TAZ mRNA changes but resulted in a significant TAZ protein decline (approximately 62%) in total cell lysates. Analysis of cytosolic and nuclear extracts revealed that the decline of total TAZ was caused primarily by a drop of TAZ protein levels in the nucleus. TAZ was localized on the peroxisome proliferator-activated receptor response element site (located at position -1200 bp relative to the transcription start site) of the genomic region of decidualization marker insulin-like growth factor-binding protein 1 (IGFBP1) in HuF cells as detected by chromatin immunoprecipitation. TAZ is also present in human endometrium tissue as confirmed by immunohistochemistry. During the secretory phase of the menstrual cycle, specific TAZ staining particularly diminishes in the stroma, suggesting its participation during the decidualization process, as well as implantation. During early baboon pregnancy, TAZ protein expression remains minimal in the endometrium close to the implantation site. In summary, the presented evidence shows for the first time to date TAZ protein in the human uterine tract, its downregulation during in vitro decidualization, and its localization on the IGFBP1 promoter region, all of which indicate its presence in the uterine differentiation program during pregnancy.

12/15-Lipoxygenase inhibitor baicalein suppresses PPAR gamma expression and nuclear translocation induced by cerebral ischemia/reperfusion

Accumulating evidences have demonstrated the beneficial actions of peroxisome proliferator-activated receptor gamma (PPAR gamma) in a variety of animal stroke models. Following middle cerebral artery occlusion (60 min) and 2-24 hr reperfusion in rats, we observed cerebral ischemia/reperfusion (I/R) induced up-regulation of PPAR gamma protein expression and translocation from the cytoplasm into the nucleus in a time-dependent manner. We also found that PPAR gamma agonist rosiglitazone enhanced whereas PPAR gamma antagonist GW9662 inhibited the alteration of PPAR gamma stimulated by I/R, suggesting that the changes of PPAR gamma may result from the activation by endogenous ligands. Moreover, the link between the 12/15-lipoxygenase and the production of activating ligands for PPAR gamma has been proved in various tissues. However, the relation of them in brain tissue has not been identified. We demonstrated that the I/R-induced PPAR gamma alteration was reversed by baicalein, the specific inhibitor of 12/15-lipoxygenase. Baicalein treatment significantly inhibited the up-regulation of PPAR gamma expression and, furthermore, suppressed PPAR gamma nuclear accumulation as well as maintained PPAR gamma cytoplasmic retention. Together, these results suggest that I/R induces both PPAR gamma expression and translocation, probably through the activation by endogenous ligands in a 12/15-lipoxygenase inhibitor-sensitive way.

Ym1/2 promotes Th2 cytokine expression by inhibiting 12/15(S)-lipoxygenase: identification of a novel pathway for regulating allergic inflammation

The Ym1/2 lectin is expressed abundantly in the allergic mouse lung in an IL-13-dependent manner. However, the role of Ym1/2 in the development of allergic airways disease is largely unknown. In this investigation, we show that treatment of mice with anti-Ym1/2 Ab during induction of allergic airways disease attenuated mediastinal lymph node production of IL-5 and IL-13. Ym1/2 was found to be expressed by dendritic cells (DCs) in an IL-13-dependent manner and supplementation of DC/CD4(+) T cell cocultures with Ym1/2 enhanced the ability of IL-13(-/-) DCs to stimulate the secretion of IL-5 and IL-13. Affinity chromatography identified 12/15(S)-lipoxygenase (12/15-LOX) as a Ym1/2-interacting protein and functional studies suggested that Ym1/2 promoted the ability of DCs to stimulate cytokine production by inhibiting 12/15-LOX-mediated catalysis of 12-hydroxyeicosatetraenoic acid (12(S)-HETE). Treatment of DC/CD4(+) T cell cultures with the 12/15-LOX inhibitor baicalein enhanced, whereas 12(S)-HETE inhibited the production of Th2 cytokines. Notably, delivery of 12(S)-HETE to the airways of mice significantly attenuated the development of allergic airways inflammation and the production of IL-5 and IL-13. In summary, our results suggest that production of Ym1/2 in response to IL-13 promotes Th2 cytokine production and allergic airways inflammation by inhibiting the production of 12(S)-HETE by 12/15-LOX.

12/15-Lipoxygenase deficiency protects mice from allergic airways inflammation and increases secretory IgA levels

BACKGROUND

Induction of 15-lipoxygenase-1 (15-LO-1) has been observed in the airways of subjects with asthma, although its physiologic role in the airways has remained largely undefined.

OBJECTIVES

We sought to test the hypothesis that the mouse 15-LO-1 ortholog 12/15-LO contributes to the development of allergic airways inflammation.

METHODS

Two models were used to evaluate wild-type and 12/15-LO-deficient mice. The systemic model involved intraperitoneal injections of allergen, and the mucosal model involved allergen exposures occurring exclusively in the airways. The systemic and mucosal-specific contributions of 12/15-LO to allergic sensitization and airways inflammation were determined by comparing the results obtained in the 2 models.

RESULTS

In the mucosal model 12/15-LO knockout mice were protected from the development of allergic sensitization and airways inflammation, as evidenced by circulating levels of allergen-specific IgE, IgG1, and IgG2a; the profile of inflammatory cells in bronchoalveolar lavage fluid; and the expression of cytokines and mediators in lung tissue. In the systemic model 12/15-LO knockout mice were not protected. This suggested the presence of a lung-restricted protective role for 12/15-LO deficiency that was potentially accounted for by increased activation of mucosal B cells and increased production of the known mucosal-specific protective mediator secretory IgA.

CONCLUSIONS

Induction of 15-LO-1 in asthma might contribute to allergic sensitization and airways inflammation, potentially by causing suppression of secretory IgA.

Transcriptional control of the expression of MUC1

MUC1 is a multifunctional cell surface glycoprotein that modulates cell adhesion, protects mucosa from infection and enzymatic attack, lubricates cell surfaces, participates in multiple signal-transduction pathways and is overexpressed by many tumors. MUC1 levels change dynamically in various cellular contexts. The primary mechanism for controlling MUC1 expression appears to be transcriptional through a complex combination of often overlapping regulatory motifs that control both tissue specificity and overall rate of transcription. This review will summarize the current knowledge of the factors known to control MUC1 transcriptional regulation, including cytokines, steroid hormones and the growth factors they stimulate, as well as suggest how this information may be exploited in the future to control MUC1 expression in specific biological contexts.

Peroxisome proliferator-activated receptor gamma is a target of progesterone regulation in the preovulatory follicles and controls ovulation in mice

The progesterone receptor (PR) plays a critical role during ovulation. Mice lacking the PR gene are anovulatory due to a failure in the rupture of the preovulatory follicles. The pathways that operate downstream of PR to control ovulation are poorly understood. Using gene expression profiling, we identified peroxisome proliferator-activated receptor gamma (PPARgamma) as a target of regulation by PR in the granulosa cells of the preovulatory follicles during the ovulatory process. To investigate the function of PPARgamma during ovulation, we created a conditional knockout mouse in which this gene was deleted via Cre-Lox-mediated excision in granulosa cells. When these mutant mice were subjected to gonadotropin-induced superovulation, the preovulatory follicles failed to rupture and the number of eggs released from the mutant ovaries declined drastically. Gene expression analysis identified endothelin-2, interleukin-6, and cyclic GMP-dependent protein kinase II as novel targets of regulation by PPARgamma in the ovary. Our studies also suggested that cycloxygenase 2-derived metabolites of long-chain fatty acids function as endogenous activating ligands of PPARgamma in the preovulatory follicles. Collectively, these studies revealed that PPARgamma is a key mediator of the biological actions of PR in the granulosa cells and activation of its downstream pathways critically controls ovulation.

The hamster as a model for embryo implantation: insights into a multifaceted process

Defects in preimplantation embryonic development, uterine receptivity, and implantation are the leading cause of infertility, pregnancy problems and birth defects. Significant progress has been made in our basic understanding of these processes using the mouse model, where implantation is ovarian estrogen-dependent in the presence of progesterone. However, an animal model where implantation is progesterone-dependent must also be studied to gain a full understanding of the embryo and uterine events that are required for implantation. In this regard, the hamster is a useful model and this review summarizes the information currently available regarding mechanisms involved in synchronous preimplantation embryo and uterine development for implantation in this species.

Redox features of the cell: a gender perspective

Reactive oxygen and nitrogen species have been implicated in diverse subcellular activities, including cell proliferation,differentiation and, in some instances, cell injury and death. The implications of reactive species inhuman pathology have also been studied in detail. However, although the role of free radicals in the pathogenesis of human diseases has been extensively analyzed in different systems (i.e., in vitro, ex vivo, and in vivo),it is still far from elucidated. In particular, the possible role of gender 4 differences in human pathophysiology associated with reactive species is a promising new field of investigation. Although the complex scenario this presents is still incomplete, important gender-associated "redox features" of cells have already been described in the literature. Here we summarize the different aspects of redox-associated molecules and enzymes in regard to gender differences in terms of the intracellular production and biochemical activity of reactive species. These are often associated with the pathogenetic mechanisms underlying several human morbidities(e.g., degenerative diseases) and can represent a specific target for new pharmacologic strategies. Gender differences may thus pose an important challenge for future studies aimed at the clinical management of diseases characterized by a redox imbalance.

Maternal and Embryonic Control of Uterine Sphingolipid-Metabolizing Enzymes During Murine Embryo Implantation1

During early gestation in invasively implanting species, the uterine stromal compartment undergoes dramatic remodeling, defined by the differentiation of stromal fibroblast cells into decidual cells. Lipid signaling molecules from a number of pathways are well-established functional components of this decidualization reaction. Because of a correlation in the events that transpire in the uterus during early implantation with known functions of bioactive sphingolipid metabolites established from studies in other organ systems, we hypothesized that uterine sphingolipid metabolism would change during implantation. By a combination of Northern blot, Western blot, and immunohistochemical analyses, we establish that enzymes at each of the major catalytic steps in the sphingolipid cascade become transcriptionally up-regulated in the uterus during decidualization. Each of the enzymes analyzed was up-regulated from Days of Pregnancy (DOP) 4.5-7.5. When comparing embryo-induced decidualization (decidual) with mechanically induced decidualization (deciduomal), sphingomyelin phosphodiesterase 1 (Smpd1) mRNA and sphingosine kinase 1 (SPHK1) protein were shown to be dually regulated in the endometrium by both maternal and embryonic factors. As measured by the diacyl glycerol kinase assay, ceramide levels rose in parallel with Smpd1 gene expression, suggesting that elevated transcription of sphingolipid enzymes results in heightened catalytic activity of the pathway. Altogether, these findings place sphingolipids on a growing list of lipid signaling molecules that become increasingly present at the maternal-embryonic interface.

Bone morphogenetic protein 2 functions via a conserved signaling pathway involving Wnt4 to regulate uterine decidualization in the mouse and the human

A critical role of progesterone (P) during early pregnancy is to induce differentiation of the endometrial stromal cells into specialized decidual cells that support the development of the implanting embryo. The P-induced signaling pathways that participate in the formation and function of the decidual cells remain poorly understood. We report here that the expression of the bone morphogenetic protein 2 (BMP2), a morphogen belonging to the TGFbeta superfamily, is induced downstream of P action in the mouse uterine stroma during decidualization. To determine the function of BMP2 during this differentiation process, we employed a primary culture system in which undifferentiated stromal cells isolated from pregnant mouse uterus undergo decidualization. When recombinant BMP2 was added to these stromal cultures, it markedly advanced the differentiation program. We also found that siRNA-mediated silencing of BMP2 expression in these cells efficiently blocked the differentiation process. Gene expression profiling experiments identified Wnt4 as a downstream target of BMP2 regulation in stromal cells undergoing decidualization. Attenuation of Wnt4 expression by siRNAs greatly reduced stromal differentiation in vitro, indicating that it is a key mediator of BMP2-induced decidualization. We also observed a remarkable induction in the expression of BMP2 in human endometrial stromal cells during decidualization in vitro in response to steroids and cAMP. Addition of BMP2 to these cultures led to a robust enhancement of Wnt4 expression and stimulated the differentiation process. Collectively, our studies uncovered a unique conserved pathway involving BMP2 and Wnt4 that mediates P-induced stromal decidualization in the mouse and the human.