Transcriptional effects of progesterone receptor antagonist in rat granulosa cells

Nuclear receptors: Key regulators of somatic cell functions in the ovulatory process

The development of the ovarian follicle to its culmination by ovulation is an essential element of fertility. The final stages of ovarian follicular growth are characterized by granulosa cell proliferation and differentiation, and steroid synthesis under the influence of follicle-stimulating hormone (FSH). The result is a population of granulosa cells poised to respond to the ovulatory surge of luteinizing hormone (LH). Members of the nuclear receptor superfamily of transcription factors play indispensable roles in the regulation of these events. The key regulators of the final stages of follicular growth that precede ovulation from this family include the estrogen receptor beta (ESR2) and the androgen receptor (AR), with additional roles for others, including steroidogenic factor-1 (SF-1) and liver receptor homolog-1 (LRH-1). Following the LH surge, the mural and cumulus granulosa cells undergo rapid changes that result in expansion of the cumulus layer, and a shift in ovarian steroid hormone biosynthesis from estradiol to progesterone production. The nuclear receptor best associated with these events is LRH-1. Inadequate cumulus expansion is also observed in the absence of AR and ESR2, but not the progesterone receptor (PGR). The terminal stages of ovulation are regulated by PGR, which increases the abundance of the proteases that are directly responsible for rupture. It further regulates the prostaglandins and cytokines associated with the inflammatory-like characteristics of ovulation. LRH-1 regulates PGR, and is also a key regulator of steroidogenesis, cellular proliferation, and cellular migration, and cytoskeletal remodeling. In summary, nuclear receptors are among the panoply of transcriptional regulators with roles in ovulation, and several are necessary for normal ovarian function.

Intraovarian influence of bovine corpus luteum on oocyte morphometry and developmental competence, embryo production and cryotolerance

Three experiments were conducted to determine influence of the bovine corpus luteum (CL) on morphometric and functional characteristics of oocytes, and subsequent embryonic development. Cumulus-oocyte complexes were aspirated from two types of cows: 1) with a CL in one ovary (CL+) and without a CL in the contralateral ovary (CL-), 2) and from cows without CL in either ovary (C). Intracellular activity of the enzyme glucose-6-phosphate dehydrogenase (G6PDH), oocyte diameter and thickness of the zona pellucida were determined (Experiment 1). Then, the rate of in vitro oocyte maturation for each ovarian category was evaluated and oocyte diameter and zona pellucida thickness were measured after maturation (Experiment 2). In Experiment 3, in vitro embryo production and cryotolerance were assessed. The oocyte diameter was greater (P < 0.01) and the zona pellucida was thinner in CL+ than in CL- (P > 0.05) or C (P = 0.0131) ovaries. Activity of G6PDH was lower in oocytes from CL+ than CL- (P < 0.01) and C (P = 0.0148) ovaries. Rate of oocyte maturation, oocyte diameter and thickness of the zona pellucida after maturation did not differ among groups. Rate of cleavage was greater in zygotes from CL+ than from CL- or C (P < 0.01); and CL+ ovaries produced more total embryos on day 7 (P < 0.05) and more blastocysts (P < 0.01) than CL- and C ovaries. Rate of expansion and hatching of day-7 vitrified-warmed blastocysts at 24 and 48 h of culture did not differ among groups. In conclusion, oocytes collected from CL+ ovaries were larger and metabolically more prepared to continue maturation than those from ovaries lacking a CL. Also, rates of cleavage and yield of blastocysts were greater for oocytes from CL+ ovaries than from CL- and C ovaries. These findings indicate that a CL influenced oocyte developmental competence and embryonic development, presumably through intraovarian interactions.

Progestin-primed ovarian stimulation vs mild stimulation in women with advanced age above 40: a retrospective cohort study

BACKGROUND

Previous studies have demonstrated that progestin-primed ovarian stimulation (PPOS) protocol was a feasible and efficient method in in vitro fertilization (IVF) cycle. However, its application in women with advanced age has not been determined yet. The purpose of this study was to investigate its efficacy in women aged ≥40 years old.

METHODS

This retrospective cohort study included patients with ages of ≥40 years old at the time of ovarian stimulation. The embryonic and clinical outcome of mild stimulation and PPOS were compared. Primary outcome was top-quality embryo rate on day 3, and secondary outcome was clinical pregnancy rate.

RESULTS

Baseline characteristics of patients was similar in mild stimulation (122 cycles) and PPOS (47 cycles). No significant difference was found in the number of retrieved and mature oocytes and the fertilization and cleavage rates. Of interest, the rate of top-quality embryos was significantly higher in PPOS group (50.08% vs 33.29%, p = 0.015), with an increasing trend of viable embryo rate (73.55% vs 61.16%). A greater amount of gonadotropin was observed in PPOS group (2061.17 ± 1254.63 IU vs 1518.14 ± 547.25 IU, p < 0.05) in spite of comparable duration of stimulation. After FET cycle, no significant difference was found in the clinical pregnancy rates between mild stimulation (12.5%) and PPOS group (16.7%).

CONCLUSIONS

Higher percentage of top-quality embryos on Day 3 and comparable clinical pregnancy rate was obtained in PPOS protocol, which could be considered as a feasible ovarian stimulation protocol in women aged above 40 years old.

Effect of Frozen Embryo Transfer and Progestin-primed Ovary Stimulation on IVF outcomes in women with high body mass index

Among women undergoing IVF, high BMI negatively affects pregnancy outcomes when using the conventional ovary stimulating protocols combined with fresh embryo transfer. Therefore, finding a proper treatment for these high BMI women is more important and urgent when obesity is prevalent. In our study, we reported a retrospective study of 4457 women who were divided into normal BMI group (18.5 kg/m²–24.9 kg/m²) and high BMI group (≥25 kg/m²) undergoing 4611 IVF treatment cycles with frozen embryo transfer (FET). We found the high BMI group originally had the poor oocytes performance, but after FET they got the similar pregnancy outcomes as the normal BMI group. Then under FET we analyzed the IVF outcomes of our new progestin-primed ovary stimulation (PPOS) protocol, indicating that the hMG + MPA (4 or 10 mg/d) groups had the obvious better pregnancy results than the conventional short group in the high BMI group, and binary logistic regression analysis showed the hMG + MPA (10 mg/d) group was associated with better pregnancy outcomes than the hMG + MPA (4 mg/d) group. These results indicate PPOS - hMG + MPA (10 mg/d) combined with FET might be a new potential treatment choice for the high BMI women undergoing IVF treatments.

Identification of new biomarker candidates for glucocorticoid induced insulin resistance using literature mining

BACKGROUND

Glucocorticoids are potent anti-inflammatory agents used for the treatment of diseases such as rheumatoid arthritis, asthma, inflammatory bowel disease and psoriasis. Unfortunately, usage is limited because of metabolic side-effects, e.g. insulin resistance, glucose intolerance and diabetes. To gain more insight into the mechanisms behind glucocorticoid induced insulin resistance, it is important to understand which genes play a role in the development of insulin resistance and which genes are affected by glucocorticoids.Medline abstracts contain many studies about insulin resistance and the molecular effects of glucocorticoids and thus are a good resource to study these effects.

RESULTS

We developed CoPubGene a method to automatically identify gene-disease associations in Medline abstracts. We used this method to create a literature network of genes related to insulin resistance and to evaluate the importance of the genes in this network for glucocorticoid induced metabolic side effects and anti-inflammatory processes.With this approach we found several genes that already are considered markers of GC induced IR, such as phosphoenolpyruvate carboxykinase (PCK) and glucose-6-phosphatase, catalytic subunit (G6PC). In addition, we found genes involved in steroid synthesis that have not yet been recognized as mediators of GC induced IR.

CONCLUSIONS

With this approach we are able to construct a robust informative literature network of insulin resistance related genes that gave new insights to better understand the mechanisms behind GC induced IR. The method has been set up in a generic way so it can be applied to a wide variety of disease networks.

Luman recruiting factor regulates endoplasmic reticulum stress in mouse ovarian granulosa cell apoptosis

Follicular atresia is primarily induced by granulosa cell apoptosis; however, the molecular mechanisms that control apoptotic cell death in granulosa cells remain poorly understood. The present studies were undertaken to investigate the role of a novel endoplasmic reticulum stress-regulated gene Luman recruiting factor (LRF) in granulosa cell apoptosis during mouse follicular atresia. Based on immunohistochemistry and confocal laser scanning microscope analysis, LRF protein was localized in the cytoplasm of apoptotic granulosa cells, similar to localization of the LRF, Luman, CCAAT/enhancer-binding protein homologous protein and caspase-12 proteins were localized in apoptotic granulosa cells. However, glucose-regulated protein 78 protein was only present in healthy cells of the mural granulosa cell layers. A spontaneous onset of apoptotic cell death of granulosa cells was induced by thapsigargin or tunicamycin treatment in vitro, which was closely related to the increase of LRF, Luman, CCAAT/enhancer-binding protein homologous protein, and caspase-12 mRNA. Taken together, LRF might be involved in inducing apoptosis of granulosa cells through the endoplasmic reticulum stress pathway and might have a key role in mouse follicular selection.

An early single dose of progesterone agonist attenuates endogenous progesterone surge and reduces ovulation rate in immature rat model of induced ovulation

Inhibition of preovulatory synthesis and action of progesterone impairs ovulation in rodents. We evaluated effects of supplementation of exogenous progesterone on human chorionic gonadotropin (hCG)-induced ovulatory response in immature rats. Equine CG-primed mature follicles responded to hCG with induction of immunoreactive steroidogenic acute regulatory protein (StAR) mainly in thecal layers and a transient enhancement in progesterone synthesis peaking at 6h after hCG (hCG6h). A single dose of natural progesterone or a synthetic agonist (MP) at hCG0h both decreased ovulation rates in dose-dependent manners. MP was still effective when treated at hCG4h. Treatment with these agents at hCG0h reduced circulating progesterone and thecal expression of StAR at hCG6h. The treatments further attenuated induction of cyclooxygenase (COX)-2 in mural granulosa cells and ovarian prostaglandin (PG) E(2) level at hCG8h. We also found a significant reduction in bromo-deoxyuridine incorporation by mural granulosa cells. Obtained results show that the early treatment with exogenous progesterone agonist caused attenuated amplitude of endogenous progesterone surge, reduced COX-2/PGE(2) system, dysregulated mitosis of granulosa cells, and decreased oocytes release. We suggest that optimal progesterone synthesis and action are an early critical component of hCG-initiated ovulatory cascade that regulates biochemical function of granulosa cells.

CoPub update: CoPub 5.0 a text mining system to answer biological questions

In this article, we present CoPub 5.0, a publicly available text mining system, which uses Medline abstracts to calculate robust statistics for keyword co-occurrences. CoPub was initially developed for the analysis of microarray data, but we broadened the scope by implementing new technology and new thesauri. In CoPub 5.0, we integrated existing CoPub technology with new features, and provided a new advanced interface, which can be used to answer a variety of biological questions. CoPub 5.0 allows searching for keywords of interest and its relations to curated thesauri and provides highlighting and sorting mechanisms, using its statistics, to retrieve the most important abstracts in which the terms co-occur. It also provides a way to search for indirect relations between genes, drugs, pathways and diseases, following an ABC principle, in which A and C have no direct connection but are connected via shared B intermediates. With CoPub 5.0, it is possible to create, annotate and analyze networks using the layout and highlight options of Cytoscape web, allowing for literature based systems biology. Finally, operations of the CoPub 5.0 Web service enable to implement the CoPub technology in bioinformatics workflows. CoPub 5.0 can be accessed through the CoPub portal http://www.copub.org.