Sperm in most mammalian species including rat, mice and human are kept completely quiescent (motionless) and viable for up to a few weeks in the cauda epididymis before ejaculation. Vigorous motility is initiated almost instantly upon sperm release from cauda during ejaculation. The molecular mechanisms that suppress sperm motility but increase cell survival during storage in cauda epididymis are not known. Intracellular signaling via phosphorylation cascades is quick events that may regulate motility and survival of transcriptionally inactive sperm. Pathscan intracellular signaling array provided the preliminary picture of cell signaling in quiescent and motile rat sperm, indicating upregulation of cell-survival pathways in quiescent sperm, which were downregulated during motility activation. Interactome of signaling proteins involved in motility activation was constructed by Search Tool for the Retrieval of Interacting Genes (STRING) software, which identified mitogen activated protein kinase-p38 (MAPK-p38), AKT, mTOR and their downstream target p70S6K as the key kinases regulating sperm function. Further validation was achieved by western blotting and pathway activators/inhibitors. Immunofluorescence localized the kinase proteins in the sperm mid-piece region (mitochondria), a known extra-nuclear target for these signaling pathways. Activators of these kinases inhibited sperm motility but increased viability, and vice versa was true for inhibitors, in most of the cases. Activators and inhibitors also affected sperm mitochondrial membrane potential, ATP content and reactive oxygen species (ROS) levels. Data suggest that sperm motility and survival are inversely complementary and critically regulated by intracellular cell signaling. Aberrant cell signaling in caudal sperm may affect cell survival (sperm concentration) and motility of ejaculated sperm.
Archana Devi, Bhavana Kushwaha, Jagdamba P Maikhuri, Rajender Singh, and Gopal Gupta
Chen Yang, Yue Li, Hai-Yang Pan, Meng-Yuan Li, Ji-Min Pan, Si-Ting Chen, Hai-Yi Zhang, Zhen-Shan Yang, Hai-Ting Dou, and Zeng-Ming Yang
There are around 300 million adolescent pregnancies worldwide, accounting for 11% of all births worldwide. Accumulating evidence demonstrates that many adverse perinatal outcomes are associated with adolescent pregnancies. However, how and why these abnormalities occur remain to be defined. In this study, pregnancy at different stages was compared between 25- and 30- day-old and mature female mice. We found that the litter size of adolescent pregnancy is significantly decreased from F1 to F3 generations compared to mature pregnancy. On days 8 and 12 of pregnancy, multiple abnormalities in decidual and placental development appear in F3 adolescent pregnancy. On days 5 and 8, uterine endoplasmic reticulum stress is dysregulated in F3 adolescent pregnancy. Embryo implantation and decidualization are also compromised in adolescent pregnancy. Many genes are abnormally expressed in adolescent estrous uteri. The abnormal endocrine environment and abnormal implantation from uterine immaturity may result in multiple pregnancy failures in adolescent pregnancy. The aim of this study is to shed light on human adolescent pregnancy.
Lanlan Fang, Zhen Wang, Ze Wu, Yang Yan, Yibo Gao, Yuxi Li, Jung-Chien Cheng, and Ying-Pu Sun
Matrix metalloproteinases (MMPs) play a pivotal role in the regulation of cell invasion. Placental trophoblast cell invasion is a precisely regulated event. Dysregulation of MMPs has been linked to various placental diseases. Growth differentiation factor-8 (GDF-8), also known as myostatin, is a member of the transforming growth factor-beta (TGF-β) superfamily. GDF-8 and its putative receptors are expressed in human extravillous cytotrophoblast cells (EVTs). Although the pro-invasive effect of GDF-8 in human EVT cells has been recently reported, the underlying molecular mechanism remains largely unknown. In this study, we investigate the effects of GDF-8 on the expression of the two most important MMPs, MMP2 and MMP9, in the HTR-8/SVneo human EVT cell line. Our results show that GDF-8 significantly upregulates the expression of MMP2. The expression of MMP9 is not affected by GDF-8. Using a siRNA-mediated knockdown approach, we reveal that the stimulatory effect of GDF-8 on MMP2 expression is mediated by the ALK5-SMAD2/3 signaling pathway. Additionally, the knockdown of MMP2 attenuates the GDF-8-induced cell invasiveness. These findings deepen our understanding of the biological roles of GDF-8 in the regulation of human trophoblast cell invasion.
Chen Geng, Hao-ran Liu, Yue Zhao, Yang Yang, and Lan Chao
The epithelial-to-mesenchymal transition may play a role in adenomyosis. GRIM19 expression is downregulated in adenomyotic lesions, and the effects of this downregulation in adenomyosis remain relatively unclear. In this study, we aimed to explore whether aberrant GRIM19 expression is associated with the epithelial-to-mesenchymal transition in adenomyosis and found that the expression of both GRIM19 and WT1 was low, and epithelial-to-mesenchymal transition, which included significant changes in CDH1, CDH2 and KRT8 expression, occurred in adenomyotic lesions, as confirmed by Western blotting and quantitative real-time PCR. We provided novel insights into WT1 expression in adenomyosis, revealing that WT1 expression was increased in the endometrial glands of adenomyotic lesions by immunohistochemistry. In vitro, knockdown of GRIM19 expression by small interfering RNA (siRNA) promoted the proliferation, migration and invasion of Ishikawa cells, as measured by Cell Counting Kit-8, wound healing assay and Transwell assays. Western blotting and quantitative real-time PCR confirmed that WT1 expression increased and epithelial-to-mesenchymal transition was induced, including the upregulation of CDH2 and downregulation of CDH1 and KRT8after transfecting the GRIM19 siRNA to Ishikawa cells. Furthermore, Wt1 expression was upregulated and epithelial-to-mesenchymal transition was observed, including downregulation of Cdh1 and Krt8 in Grim19 gene-knockdown mice. Upregulation of Wt1 expression in the endometrial glands of Grim19 knockdown mice was also verified by immunohistochemistry. Taken together, these results reveal that low expression of GRIM19 in adenomyosis may upregulate WT1 expression and induce epithelial-to-mesenchymal transition in the endometria, providing new insights into the pathogenesis of adenomyosis.
Saije K Morosin, Sarah J Delforce, Richard G S Kahl, Celine Corbisier de Meaultsart, Eugenie R Lumbers, and Kirsty G Pringle
This study aimed to determine if the (pro)renin receptor (ATP6AP2) changes the cellular profile of choriocarcinomas from cytotrophoblast cells to terminally syncytialised cells and ascertain whether this impacts the invasive potential of choriocarcinoma cells. Additionally, we aimed to confirm that FURIN and/or site 1 protease (MBTPS1) cleave soluble ATP6AP2 (sATP6AP2) in BeWo choriocarcinoma cells and determine whether sATP6AP2 levels reflect the cellular profile of choriocarcinomas. BeWo choriocarcinoma cells were treated with ATP6AP2 siRNA, FURIN siRNA, DEC-RVKR-CMK (to inhibit FURIN activity), or PF 429242 (to inhibit MBTPS1 activity). Cells were also treated with forskolin, to induce syncytialisation, or vehicle and incubated for 48 h before collection of cells and supernatants. Syncytialisation was assessed by measuring hCG secretion (by ELISA) and E-cadherin protein levels (by immunoblot and immunocytochemistry). Cellular invasion was measured using the xCELLigence real-time cell analysis system and secreted sATP6AP2 levels measured by ELISA. Forskolin successfully induced syncytialisation and significantly increased both BeWo choriocarcinoma cell invasion (P < 0.0001) and sATP6AP2 levels (P = 0.02). Treatment with ATP6AP2 siRNA significantly inhibited syncytialisation (decreased hCG secretion (P = 0.005), the percent of nuclei in syncytia (P = 0.05)), forskolin-induced invasion (P = 0.046), and sATP6AP2 levels (P < 0.0001). FURIN siRNA and DEC-RVKR-CMK significantly decreased sATP6AP2 levels (both P < 0.0001). In conclusion, ATP6AP2 is important for syncytialisation of choriocarcinoma cells and thereby limits choriocarcinoma cell invasion. We postulate that sATP6AP2 could be used as a biomarker measuring the invasive potential of choriocarcinomas. Additionally, we confirmed that FURIN, not MBTPS1, cleaves sATP6AP2 in BeWo cells, but other proteases (inhibited by DEC-RVKR-CMK) may also be involved.
Lauriane Relav and Christopher A Price
Controling the duration and amplitude of mitogen-activated protein kinase (MAPK) signaling is an important element in deciding cell fate. One group of intracellular negative regulators of MAPK activity is a subfamily of the dual specificity phosphatase (DUSP) superfamily, of which up to 16 members have been described in the ovarian granulosa cells. Growth factors stimulate proliferation of granulosa cells through MAPK, protein kinase C (PKC), and AKT pathways, although it is not known which pathways control DUSP expression in these cells. The aim of the present study was to identify which pathways were involved in the regulation of DUSP expression using a well-established serum-free culture system for bovine granulosa cells. Stimulation of cells with FGF2 increased DUSP1, DUSP5, and DUSP6 mRNA abundance in a time- and dose-dependent manner, and increased DUSP5 and DUSP6 protein accumulation. None of the other eleven DUSP measured were regulated by FGF2. Pharmacological inhibition of MAPK3/1 signaling decreased FGF2-stimulated DUSP1, DUSP5, and DUSP6 mRNA levels (P < 0.05), whereas inhibition of PKC did not affect the expression of these three DUSPs. Abundance of FGF2-dependent DUSP6 mRNA was reduced by inhibition of phospholipase C (PLC) or by chelating calcium, but DUSP5 mRNA abundance was not affected. Abundance of basal DUSP1 and DUSP6, but not DUSP5 mRNA was increased by the addition of the calcium ionophore A23187. We conclude that FGF2 stimulation of DUSP5 abundance requires MAPK3/1 whereas DUSP6 mRNA accumulation is dependent on calcium signaling as well as MAPK3/1 activation, suggesting complex regulation of physiologically important DUSPs in the follicle.
Vasiliki E Mourikes and Jodi A Flaws
The ovaries play a critical role in female reproductive health because they are the site of oocyte maturation and sex steroid hormone production. The unique cellular processes that take place within the ovary make it a susceptible target for chemical mixtures. Herein, we review the available data regarding the effects of chemical mixtures on the ovary, focusing on development, folliculogenesis, and steroidogenesis. The chemical mixtures discussed include those to which women are exposed to environmentally, occupationally, and medically. Following a brief introduction to chemical mixture components, we describe the effects of chemical mixtures on ovarian development, folliculogenesis, and steroidogenesis. Further, we discuss the effects of chemical mixtures on corpora lutea and transgenerational outcomes. Identifying the effects of chemical mixtures on the ovaries is paramount to preventing and treating mixture-inducing toxicity of the ovary that has long-term consequences such as infertility and ovarian disease.
Heather B Patisaul
We are all living with hundreds of anthropogenic chemicals in our bodies every day, a situation that threatens the reproductive health of present and future generations. This review focuses on endocrine-disrupting compounds (EDCs), both naturally occurring and man-made, and summarizes how they interfere with the neuroendocrine system to adversely impact pregnancy outcomes, semen quality, age at puberty, and other aspects of human reproductive health. While obvious malformations of the genitals and other reproductive organs are a clear sign of adverse reproductive health outcomes and injury to brain sexual differentiation, the hypothalamic-pituitary-gonadal (HPG) axis can be much more difficult to discern, particularly in humans. It is well-established that, over the course of development, gonadal hormones shape the vertebrate brain such that sex-specific reproductive physiology and behaviors emerge. Decades of work in neuroendocrinology have elucidated many of the discrete and often very short developmental windows across pre- and postnatal development in which this occurs. This has allowed toxicologists to probe how EDC exposures in these critical windows can permanently alter the structure and function of the HPG axis. This review includes a discussion of key EDC principles including how latency between exposure and the emergence of consequential health effects can be long, along with a summary of the most common and less well-understood EDC modes of action. Extensive examples of how EDCs are impacting human reproductive health, and evidence that they have the potential for multi-generational physiological and behavioral effects are also provided.
Hui Li and Daniel J Spade
Fetal development of the mammalian testis relies on a series of interrelated cellular processes: commitment of somatic progenitor cells to Sertoli and Leydig cell fate, migration of endothelial cells and Sertoli cells, differentiation of germ cells, deposition of the basement membrane, and establishment of cell–cell contacts, including Sertoli–Sertoli and Sertoli–germ cell contacts. These processes are orchestrated by intracellular, endocrine, and paracrine signaling processes. Because of this complexity, testis development can be disrupted by a variety of environmental toxicants. The toxicity of phthalic acid esters (phthalates) on the fetal testis has been the subject of extensive research for two decades, and phthalates have become an archetypal fetal testis toxicant. Phthalates disrupt the seminiferous cord formation and maturation, Sertoli cell function, biosynthesis of testosterone in Leydig cells, and impair germ cell survival and development, producing characteristic multinucleated germ cells. However, the mechanisms responsible for these effects are not fully understood. This review describes current knowledge of the adverse effects of phthalates on the fetal testis and their associated windows of sensitivity, and compares and contrasts the mechanisms by which toxicants of current interest, bisphenol A and its replacements, analgesics, and perfluorinated alkyl substances, alter testicular developmental processes. Working toward a better understanding of the molecular mechanisms responsible for phthalate toxicity will be critical for understanding the long-term impacts of environmental chemicals and pharmaceuticals on human reproductive health.
Troy A Roepke and Nicole C Sadlier
Reproduction is a complex process that is controlled centrally via a network of hypothalamic neurons to modulate the pulsatile release of gonadotropin-releasing hormone (GnRH) and subsequently pituitary gonadotropins. The gonadotropins, luteinizing hormone, and follicle-stimulating hormone, drive gametogenesis and hormone production from the gonads. The hypothalamic-pituitary exchange is controlled by gonadal steroids through negative and positive feedback mechanisms via steroid receptors. Due to the expression of these receptors, GnRH neurons, the hypothalamic neurons that control them, and pituitary gonadotropes are sensitive to exogenous compounds that interact with steroid and nuclear receptors or alter hormone production and metabolism. The compounds, called endocrine-disrupting compounds (EDCs), are ubiquitous and persistent in human environments and could bioaccumulate in the body. EDCs include plasticizers (like bisphenol A), dioxin, polychlorinated biphenyls (PCBs), organochlorine pesticides, flame retardants, and perfluorinated alkyl substances (PFAS). Numerous studies have reported that perinatal, juvenile, or adult exposure to these EDCs, primarily in rats, disrupt the hypothalamic control of pituitary gonadotropin production leading to disruption of gonadal steroid production and estrous cyclicity. The purpose of this review is to evaluate these studies primarily focusing on GnRH and kisspeptin neurons and anterior pituitary gonadotropins and to discuss the need for deeper investigations into the hypothalamic-pituitary-gonadal axis.