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A Vail and J Wilkinson

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Katerina Menelaou, Malwina Prater, Simon J Tunster, Georgina E T Blake, Colleen Geary Joo, James C Cross, Russell S Hamilton and Erica D Watson

Assisted reproduction technologies (ARTs) are becoming increasingly common. Therefore, how these procedures influence gene regulation and foeto-placental development are important to explore. Here, we assess the effects of blastocyst transfer on mouse placental growth and transcriptome. C57Bl/6 blastocysts were transferred into uteri of B6D2F1 pseudopregnant females and dissected at embryonic day 10.5 for analysis. Compared to non-transferred controls, placentas from transferred conceptuses weighed less even though the embryos were larger on average. This suggested a compensatory increase in placental efficiency. RNA sequencing of whole male placentas revealed 543 differentially expressed genes (DEGs) after blastocyst transfer: 188 and 355 genes were downregulated and upregulated, respectively. DEGs were independently validated in male and female placentas. Bioinformatic analyses revealed that DEGs represented expression in all major placental cell types and included genes that are critical for placenta development and/or function. Furthermore, the direction of transcriptional change in response to blastocyst transfer implied an adaptive response to improve placental function to maintain foetal growth. Our analysis revealed that CpG methylation at regulatory regions of two DEGs was unchanged in female transferred placentas and that DEGs had fewer gene-associated CpG islands (within ~20 kb region) compared to the larger genome. These data suggested that altered methylation at proximal promoter regions might not lead to transcriptional disruption in transferred placentas. Genomic clustering of some DEGs warrants further investigation of long-range, cis-acting epigenetic mechanisms including histone modifications together with DNA methylation. We conclude that embryo transfer, a protocol required for ART, significantly impacts the placental transcriptome and growth.

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Mian Liu, Xia Chen, Qing-Xian Chang, Rui Hua, Yan-Xing Wei, Li-Ping Huang, Yi-xin Liao, Xiao-Jing Yue, Hao-Yue Hu, Fei Sun, Si-Jia Jiang, Song Quan and Yan-Hong Yu

Small extracellular vesicles (sEVs) are important mediators of cell-to-cell communication involved in the successful establishment of a pregnancy. Human decidual stromal cells play a key role in regulating trophoblast invasion. Nevertheless, the regulatory functions of decidual stromal cells-derived sEVs in human trophoblast cells are still unclear. In this study, primary human decidual stromal cells were isolated, and immortalized human endometrial stromal cell line (HESCs) were decidualized into human decidual stromal cells (HDSCs) using hormonal cocktail containing medroxy progesterone 17-acetate (MPA), estrogen and cAMP analog. HDSC-sEVs were isolated from both primary human decidual stromal cells and immortal HDSCs, respectively, and identified by transmission electron microscopy and western blotting. EV uptake assay indicated that HDSC-sEVs could be uptaken by trophoblast cells. HDSC-sEVs could increase the invasiveness and the expression level of N-cadherin of trophoblast cells with elevated phosphorylation of SMAD2 and SMAD3 in the cells. Silencing of N-cadherin could block cell invasion induced by HDSC-sEVs, while knockdown of SMAD2 and SMAD3 could inhibit the upregulation of N-cadherin in trophoblast cells. Taken together, our results suggested a regulatory effect of HDSC-sEVs in the invasion of trophoblast cells, and HDSC-sEVs may be important mediators of trophoblasts during embryo implantation and placentation.

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Alissa Richmond Armstrong

Observed in a wide variety of organism, from invertebrates to mammals, nutritional status modulates the energetically costly effort of producing female gametes. Despite this long-standing link between nutrition and ovarian function, relatively little is known about the cellular and molecular mechanisms that underlie how dietary components modulate egg production. Drosophila melanogaster, with its powerful and extensive genetic tools as well as its well-characterized ovarian response to diet, has proven to be instrumental in addressing this issue. This review covers what we currently know about the dietary control of oogenesis in Drosophila and the salient features of the fruit fly that make it a model for nutritional control of ovarian function.

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Shengxian Li, Jia Qi, Yongzhen Tao, Qinling Zhu, Rong Huang, Yu Liao, Jiang Yue, Wei Liu, Hanting Zhao, Huiyong Yin and Yun Sun

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women usually accompanied by lipid metabolic disorders. However, it remains unknown whether arachidonic acid (AA) and its metabolites in follicular fluid (FF) were altered in PCOS patients. This study was intended to measure the levels of AA and its metabolites in the FF of non-obese PCOS patients that underwent in vitro fertilization (IVF) and to explore the possible causes of the alterations. Thirty-nine non-obese women with PCOS and 30 non-obese women without PCOS were enrolled. AA and its metabolites were measured by liquid chromatography-mass spectrometry. The levels of AA metabolites generated via cyclooxygenase-2 (COX-2) pathway and cytochrome P450 epoxygenase pathway but not lipoxygenase (LOX) pathway were significantly higher in the FF of PCOS patients. The metabolites generated via COX-2 pathway were significantly correlated with levels of testosterone and fasting insulin in serum. The in vitro study further demonstrated that insulin but not testosterone could promote the IL-1β and hCG-induced COX-2 expression and prostaglandin E2 (PGE2) secretion in primary human granulosa cells. In conclusion, there was an elevation in AA metabolites in FF of PCOS patients. Insulin played a pivotal role in the increased AA metabolites generated via COX-2, which could be interpreted as another novel molecular pathophysiological mechanism of PCOS.

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Xihua Chen, Bin Wu, Shufang Wang, Jianbing Liu, Haijun Gao, Fang Zhou, Nan Nan, Bonan Zhang, Jiedong Wang, Xiangbo Xu and Bin He

Menstruation is a specific physiological phenomenon that occurs in women. However, molecular mechanisms underlying this phenomenon are still unclear. According to the classical theory, tissue hypoxia resulting from vasoconstriction of the spiral arteries after progesterone (P4) withdrawal initiates the breakdown of the endometrium at the earliest stage of menstruation. However, this theory has been challenged by previous studies that have questioned the function and even the existence of hypoxia during menstruation. In this study, we not only provide convincing evidence that hypoxia exists during endometrial breakdown, but also further explore the role of hypoxia and hypoxia-inducible factor 1 (HIF1) in this process. Based on mouse menstrual-like model and experiments with human decidual stromal cells, we observed that P4 withdrawal induced both hypoxia and HIF1 activation; however, endometrial breakdown was triggered only by P4 withdrawal. Hypoxia significantly enhanced the mRNA expression of specific matrix metalloproteinases (MMPs) under the conditions of P4 withdrawal. In conclusion, hypoxia is involved but not an essential component of endometrial breakdown during menstruation.

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Xiaoli Qin, Yan Chen, Jiangjing Yuan, Xiaorui Liu, Weihong Zeng and Yi Lin

Abnormal growth and migration of trophoblast cells is one of the main causes of spontaneous abortion. Eukaryotic translation initiation factor 5A (eIF5A) plays an important role in trophoblast cell growth and migration; however, its underlying mechanism remains largely unknown. Here, we first confirmed that eIF5A knockdown reduced human chorionic trophoblast HTR8 cells viability, proliferation, and migration. Next, we sought to systematically identify the genes regulated by eIF5A and observed changes in the transcriptome profile of eIF5A-knockdown HTR8 cells by RNA-seq analysis. Especially, we found that inhibition of eIF5A reduced both the mRNA and protein levels of methyltransferase-like protein 14 (METTL14). Furthermore, inhibition of METTL14 expression resulted in the reduction of viability, proliferation, and migration of HTR8 cells. In addition, we showed that overexpression of METTL14 rescued the effects of eIF5A knockdown in HTR8 cells. Finally, we revealed that eIF5A and METTL14 expression was decreased in spontaneous abortion samples compared to that in elective-induced abortion samples. Collectively, our study demonstrated that eIF5A plays a crucial role in HTR8 cells via modulation of METTL14 expression and may serve as a novel potential target for spontaneous abortion diagnosis and treatment.

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Hu Gao, Bin Chen, Hui Luo, Bo Weng, Xiangwei Tang, Yao Chen, Anqi Yang and Maoliang Ran

Sertoli cells are indispensable for normal spermatogenesis, and increasing evidence has shown that miRNAs participate in the regulation of Sertoli cell growth. However, the functions and regulatory mechanisms of miRNAs in Sertoli cells of domestic animals have not been fully investigated. In the present study, we mainly investigated the regulatory roles of miR-499 in immature porcine Sertoli cells. The results showed that miR-499 was mainly located in the basement section of seminiferous tubules of prepubertal porcine testicular tissue. Overexpression of miR-499 promoted cell proliferation and inhibited apoptosis, whereas miR-499 inhibition resulted in the opposite effect. The PTEN gene was directly targeted by miR-499, and the expression of mRNA and protein was also negatively regulated by miR-499 in immature porcine Sertoli cells. siRNA-induced PTEN knockdown resulted in a similar effect as an overexpression of miR-499 and abolished the effects of miR-499 inhibition on immature porcine Sertoli cells. Moreover, both miR-499 overexpression and the PTEN knockdown activated the PI3K/AKT signaling pathway, whereas inhibition of the PI3K/AKT signaling pathway caused immature porcine Sertoli cell apoptosis and inhibited cell proliferation. Overall, miR-499 promotes proliferation and inhibits apoptosis in immature porcine Sertoli cells through the PI3K/AKT pathway by targeting the PTEN gene. This study provides novel insights into the effects of miR-499 in spermatogenesis through the regulation of immature Sertoli cell proliferation and apoptosis.

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Jessica Stringer, Ella Groenewegen, Seng H Liew and Karla Hutt

Primordial follicle oocytes are extremely vulnerable to DNA damage caused by exogenous agents, such as those commonly used to treat cancer. Consequently, female cancer patients often have diminished ovarian reserve, which if severe enough, can cause premature ovarian failure and early menopause. Advances in cancer therapies have resulted in significantly improved cancer survival rates; therefore, it is becoming increasingly important to devise strategies to protect the ovarian reserve from cancer treatments, to avoid loss of fertility and endocrine dysfunction. In this study, we aimed to determine whether supplementation with nicotinamide mononucleotide (NMN) could preserve the ovarian reserve following exposure to DNA-damaging cancer treatments. Adult female mice (n = 5–6/group) received saline or NMN (500 mg/kg/day) for 8 days. Mice were left untreated or exposed to γ-irradiation (0.1 Gy) or cyclophosphamide (150 mg/kg) on day 7 and ovaries and serum collected for analysis on day 12. We report that γ-irradiation treatment significantly reduced the number of primordial follicles, but supplementation with NMN did not prevent the observed follicle loss. Similarly, cyclophosphamide treatment significantly reduced primordial follicle numbers, but these losses were not prevented by NMN supplementation. In conclusion, depletion of the ovarian reserve following γ-irradiation or cyclophosphamide was not protected by NMN supplementation under the conditions employed in this study.

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Jimena S Beltrame, Vanesa A Cañumil, Micaela S Sordelli and María L Ribeiro

Lysophosphatidic acid (LPA) belongs to the group of phosphorylated lipids reported as crucial mediators in the physiology of reproduction. LPA binds to G-protein-coupled receptors and regulates a wide range of female reproductive functions. This bioactive lipid has also been implicated in vascular functions during physiological and pathological conditions. In this regard, the establishment of a successful pregnancy requires proper coordination of vascular processes and remodeling of maternal blood vessels during early gestation. During this process, first trimester cytotrophoblast changes from an invasive to an endovascular phenotype and transforms uterine spiral arteries which are the nutrient supply for placenta and fetus. Here we present an overview of LPA participation in vascular remodeling and highlight the importance of LPA–LPA3 signaling during early gestation at the maternal–fetal interface.