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Wan-Ning Li, Meng-Hsing Wu, and Shaw-Jenq Tsai

Endometriosis is a benign gynecological disease that affects about 10% of women of reproductive age. Patients with endometriosis suffer from long-term coexistence with dysmenorrhea, dyspareunia, and even infertility, which severely reduces quality of life. So far, surgical removal and hormonal medication are the major treatment options; however, high recurrence and severe adverse effects hamper the therapeutic efficacy. Hypoxia is an inevitable cellular stress in many diseases that regulates the expression of a significant subset of genes involved in pathophysiological processes. A growing body of evidence demonstrates that hypoxia plays critical role in controlling the disease phenotypes of endometriosis, such as increasing adhesion ability, causing dysregulation of estrogen biosynthesis, aberrant production of proinflammatory cytokines, increasing angiogenic ability, and suppression of immune functions. In this review, we summarize the findings of the most recent studies in exploring the underlying mechanisms of hypoxia involved in endometriosis. Potential therapeutic options for targeting HIF and downstream effectors will also be discussed.

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Hsiu-Chi Lee, Shih-Chieh Lin, Meng-Hsing Wu, and Shaw-Jenq Tsai

Endometriosis is a common gynecological disease in reproductive-age women. Although the hormone-dependent therapy is the first line treatment for endometriosis, it is not a curative regimen and associated with severe side-effects, which significantly decrease the life quality of affected individuals. To seek a target for treatment of endometriosis, we focused on plasma membrane proteins that are elevated in ectopic cells and exert beneficial effects in cell growth and survival. We performed bioinformatics analysis and identified the neurotrophic receptor tyrosine kinase 2 (NTRK2) as a potential candidate for treatment. The expression levels of NTRK2 were markedly upregulated in the lesions of clinical specimen as well as in the mouse endometriotic-like lesion. Mechanistic investigation demonstrated that upregulation of NTRK2 is induced by hypoxia in a hypoxia-inducible factor 1 alpha-dependent manner. Knockdown of NTRK2 or administration of ANA-12, a selective antagonist of NTRK2, significantly induced endometriotic stromal cells death, suggesting it may be a potential therapeutic agent. In vivo study using surgery-induced endometriosis mice model showed ANA-12 (1.5 mg/kg body weight) treatment induced apoptosis of endometriotic cells and caused the regression of ectopic lesions. Taken together, our findings suggest a possible mechanism responsible for the aberrant expression of NTRK2 in endometriotic lesions and this may be involved in the pathogenesis of endometriosis.

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Gillian K. Szabo and Laura N. Vandenberg

In the past several decades, the incidence of two male breast diseases, gynecomastia and male breast cancer, have increased in human populations. Whereas male breast cancer remains a rare disease, gynecomastia, a condition that arises due to abnormal development and growth of the male breast epithelium, is fairly common. In this review, we present the male mouse mammary gland as a potential model to understand human male breast diseases. Even though the male mouse typically lacks nipples, the male retains a small mammary rudiment with epithelium that is highly sensitive to estrogenic chemicals during the perinatal and peripubertal periods. In just the last few years, our understanding of the biology of the male mouse mammary gland has expanded. Researchers have characterized the complexity and size of the male mammary epithelium across the life course. Studies have documented that the male mouse mammary gland has left-right asymmetric morphologies, as well as asymmetries in the responsiveness of the left and right glands to estrogens. Recent studies have also revealed that the effect of xenoestrogens on the male mammary gland can differ based on the timing of evaluation (prior to puberty, in puberty, and in adulthood) and the administered dose. Based on the available evidence, we argue that there is a strong case that estrogenic chemicals promote the growth of the male mouse epithelium, consistent with human gynecomastia. We also argue that these outcomes should be characterized as adverse effects and should be considered in regulatory decision-making.

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Lidia M Zúñiga, Juan-Carlos Andrade, Francisca Fábrega-Guerén, Pedro A Orihuela, Ethel V Velásquez, Elena A Vidal, Rodrigo A Gutiérrez, Patricio Morales, Benito Gómez-Silva, and Horacio B Croxatto

During mating, males provide not only the spermatozoa to fertilize the oocyte but also other stimuli that are essential for initiating and maintaining the reproductive programme in females. In the mammalian oviduct, mating regulates sperm storage, egg transport, fertilization, early embryonic development, and oestradiol metabolism. However, the main molecules underlying these processes are poorly understood. Using microarray analyses, we identified 58 genes that were either induced or repressed by mating in the endosalpinx at 3 h post-stimulus. RT-qPCR confirmed that mating downregulated the expression of the Oas1h and Prim1 genes and upregulated the expression of the Ceacam1, Chad, Chst10, Slc5a3 and Slc26a4 genes. The functional category ‘cell-to-cell signalling and interaction’ was over-represented in this gene list. Network modelling identified TNF and all-trans retinoic acid (RA) as upstream regulators of the mating-induced transcriptional response, which was confirmed by intraoviductal injection of TNF or RA in unmated rats. It partially mimicked the transcriptional effect of mating in the rat endosalpinx. Furthermore, mating decreased RA levels in oviductal fluid, and RA-receptor-gamma (RARG) exhibited a nuclear location in oviductal epithelium in both unmated and mated rats, indicating RA-RARG transcriptional activity. In conclusion, the early transcriptional response regulated by mating in the rat endosalpinx is mediated by TNF and RA. These signalling molecules regulate a cohort of genes involved in ‘cell-to-cell signalling and interactions’ and merit further studies to understand the specific processes activated in the endosalpinx to sustain the events that occur in the mammalian oviduct early after mating.

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Griselda Irusta

Although ovarian cancer mortality rates have slightly declined in the last 40 years, ovarian cancer continues to be the eighth cause of cancer death in women. Ovarian cancer is characterized by its high response to treatments but also by its high rate of recurrence. Although treatments are limited to cytoreductive surgery and platinum-based chemotherapy, other therapies using antiangiogenic agents and poly (ADP-ribose) polymerase inhibitors are being tested. Nevertheless, these therapeutic strategies have had poor results and new potential targets and approaches are thus needed. The present review focuses on the recent evidence on antiangiogenic strategies in ovarian cancer cells and on the mechanisms governed by Notch and β-catenin proteins. It also describes the concept of ‘vascular normalization’ by using the platelet-derived growth factor, PDGFB, molecule as a tool to regulate ovarian tumor angiogenesis and thus improve ovarian tumor treatment. It has been reported that alterations in the Notch system components and changes in the canonical Wnt/β-catenin signaling, the other pathway of our interest, are relevant to molecular events that contribute to ovarian cancer development. Thus, in this review, we consider these aspects of the ovarian tumor biology as potential new therapeutic strategies for the treatment of this disease.

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Fabiola Zambrano, Liliana Silva, Pamela Uribe, Ulrich Gärtner, Anja Taubert, Mabel Schulz, Raúl Sánchez, and Carlos Hermosilla

Human spermatozoa activate neutrophil extracellular traps (NETs) in vitro. NETosis is an efficient mechanism through which polymorphonuclear neutrophils (PMN) capture sperm in vitro. The objective of this study was to establish the role of store-operated Ca+2 entry (SOCE) in human sperm-triggered NETs and its impact on sperm integrity and oocyte binding capacity. PMN isolated from donors were exposed to spermatozoa isolated from normozoospermic donors using the swim-up technique and were divided into the following groups: (1) sperm, (2) PMN, (3) PMN + sperm, (4) PMN (pretreated with 2-APB, SOCE inhibitor) + sperm, (5) (PMN + DNase) + sperm, and (6) (PMN + PMA) + sperm (positive control). NETs were quantified using PicoGreen® and visualised by scanning electron microscopy and immunofluorescence of extracellular DNA and neutrophil elastase. Plasma membrane, acrosome, and DNA integrity were analysed by flow cytometry, and oocyte binding was evaluated using the hemizona pellucida assay. Sperm-triggered NETosis negatively affected the sperm membrane and acrosome integrity and decreased the oocyte binding capacity. These effects were negated by an SOCE inhibitor, thus improving sperm function and achieving high oocyte binding capacity. The SOCE inhibitor significantly reduced NET formation compared with that in control PMN/sperm (P < 0.05). Collectively, these results advance the knowledge about the role of PMN in reproduction and will allow the development of strategies to block NET formation in situations of reduced fertilisation success.

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Zachary J W Easton, Flavien Delhaes, Katherine Mathers, Lin Zhao, Christina M G Vanderboor, and Timothy R H Regnault

Placental villous trophoblast mitochondrial respiratory function is critical for a successful pregnancy and environmental influences such as maternal obesity have been associated with respiratory impairment at term. More recently, a gestational high fat diet independent of maternal body composition, has been highlighted as a potential independent regulator of placental mitochondrial metabolism. The current study aimed to characterize the direct impact of a prolonged and isolated exposure to the dietary fatty acids Palmitate (PA) and Oleate (OA) upon placental cell mitochondrial respiratory function. BeWo cytotrophoblast (CT) and syncytiotrophoblast (SCT) cells were treated for 72 h with 100 µM PA, OA or PA+OA (P/O). Live-cell metabolic function was analyzed via the Seahorse XF Mito and Glycolysis Stress tests. Immunoblots and spectrophotometric activity assays were utilized to examine the protein expression and function of electron transport chain (ETC) complexes and key mitochondrial regulatory enzymes. Syncytialization of BeWo cells resulted reduced respiratory activity in conjunction with altered complex I and II activity and decreased pyruvate dehydrogenase (PDH) protein expression and activity. PA and P/O treatments were associated with increased basal and maximal respiratory activities in BeWo CT cells without alterations in protein expression or activity of individual ETC complexes and mitochondrial substrate regulators. The metabolic suppression in BeWo SCTs was consistent with that previously observed in primary human trophoblast cell cultures, while the observed increases in respiratory activity in PA-treated BeWo CTs may be indicative of an early timepoint of specific dietary saturated fat-mediated placental cell mitochondrial dysfunction.

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Liselot J W Thunnissen, Cindy G J Cleypool, and Bernadette S de Bakker

Summary

Although it is commonly accepted that fertilisation in humans occurs in the ampulla of the fallopian tube, the peritoneal cavity might represent an alternative fertilisation site. Studies substantiating both fertilisation sites were reviewed and new insights on the fertilisation site in humans are discussed, including their implications for reproductive medicine.

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Anthony M Carter

The mouse is often criticized as a model for pregnancy research as gestation is short, with much of organ development completed postnatally. There are also differences in the structure and physiology of the placenta between mouse and human. This review considers eight alternative models that recently have been proposed and two established ones that seem underutilized. A promising newcomer among rodents is the spiny mouse, which has a longer gestation than the mouse with organogenesis complete at birth. The guinea pig is also recommended both because it has well-developed neonates and because there is a wealth of information on pregnancy and placentation in the literature. Several smaller primates are considered. The mouse lemur has its advocates yet is less suited as a model for human pregnancy as its young are altricial, placentation very different from that of humans, and husbandry requirements not fully assessed. In contrast, the common marmoset, a New World monkey, has well-developed neonates and is kept at many primate centres. Marmoset placenta has some features that closely resemble human placentation, such as the interhaemal barrier, although it is uncertain if invasion of the uterine arteries occurs in this species. In conclusion, pregnancy research would benefit greatly from increased use of alternative models such as the spiny mouse and common marmoset.

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Yufen Zhao, Boyang Yu, Xinyu Liu, Jitu Hu, Yanyan Yang, Erge Namei, Bingxue Yang, Yue Bai, Yinghong Qian, and Haijun Li

Although urokinase-type plasminogen activator (PLAU) and urokinase-type plasminogen activator receptor (PLAUR) have been reported to play key roles in ovarian function, their precise contribution to mammalian follicular development remains unclear. In this study, we first observed that PLAU and PLAUR were present in bovine granulosa cells (GCs). Following culture of granulosa cells with PLAU (0.5 ng/mL) and PLAUR antibody (10 µg/mL) separately and together for 24 or 48 h, a proliferation assay showed that interaction between PLAU and PLAUR contributes to bovine GC proliferation. To study the potential pathways involved in PLAU/PLAUR-induced cell proliferation, ELISA and Western blotting were performed. We found that PLAU significantly increased the ratio of phosphorylated to non-phosphorylated ERK1/2 through PLAUR signaling. Further treatment with U0126, a specific ERK1/2 phosphorylation inhibitor, markedly suppressed PLAU/PLAUR-induced ERK1/2 phosphorylation and cell proliferation. In addition, we found that PLAU and PLAUR significantly increased the intracellular cAMP level and the use of Rp-cAMP, a specific PKA inhibitor, prevented PLAU/PLAUR from promoting activation of the ERK1/2 pathway and GC proliferation. Therefore, the interaction between PLAU and PLAUR may be involved in accumulating cAMP signals and enabling MAPK/ERK1/2 activation, affecting GC proliferation. Here, we provide new mechanistic insights into the roles of PLAU and PLAUR on promoting bovine GC proliferation. The finding that potential cross-points between PLAU/PLAUR-induced intracellular signals affect GC proliferation will help in understanding the mechanisms regulating early follicular development.