The inhibition of WIP1 phosphatase accelerates the depletion of primordial follicles.

RESEARCH QUESTION: What role does wild-type p53-induced phosphatase 1 (WIP1) play in the regulation of primordial follicle development? DESIGN: WIP1 expression was detected in the ovaries of mice of different ages by western blotting and immunohistochemical staining. Three-day-old neonatal mouse ovaries were cultured in vitro with or without the WIP1 inhibitor GSK2830371 (10 µM) for 4 days. Ovarian morphology, follicle growth and follicle classification were analysed and the PI3K-AKT-mTOR signal pathway and the WIP1-p53-related mitochondrial apoptosis pathway evaluated. RESULTS: WIP1 expression was downregulated with age. Primordial follicles were significantly decreased in the GSK2830371-treated group, without a significant increase in growing follicles. The ratio of growing follicles to primordial follicles was not significantly different between the control and GSK2830371 groups, and no significant variation was observed in the PI3K-AKT-mTOR signal pathway. The inhibition of WIP1 phosphatase accelerated primordial follicle atresia by activating the p53-BAX-caspase-3 pathway. CONCLUSIONS: These findings reveal that WIP1 participates in regulating primordial follicle development and that inhibiting WIP1 phosphatase leads to massive primordial follicle loss via interaction with the p53-BAX-caspase-3 pathway. This might also provide valuable information for understanding decreased ovarian reserve during ovarian ageing.

Ovarian Dysfunction Induced by Chronic Whole-Body PM2.5 Exposure.

Fine particulate matter (PM2.5) pollution arouses public health concerns over the world. Increasing epidemiologic evidence suggests that exposure to ambient airborne PM2.5 increases the risk of female infertility. However, relatively few studies have systematically explored the harmful effect of chronic PM2.5 exposure on ovarian function and the underlying mechanisms. In this study, female C57BL/6J mice are exposed to filtered air or urban airborne PM2.5 for 4 months through a whole-body exposure system. It is found that PM2.5 exposure significantly caused the alteration of estrus cycles, reproductivity, hormone levels, and ovarian reserve. The granulosa cell apoptosis via the mitochondria dependent pathway contributes to the follicle atresia. With RNA-sequencing technique, the differentially expressed genes induced by PM2.5 exposure are mainly enriched in ovarian steroidogenesis, reactive oxygen species and oxidative phosphorylation pathways. Furthermore, it is found that increased PM2.5 profoundly exacerbated ovarian oxidative stress and inflammation in mice through the NF-κB/IL-6 signaling pathway. Notably, dietary polydatin (PD) supplement has protective effect in mice against PM2.5-induced ovarian dysfunction.These striking findings demonstrate that PM2.5 and/or air pollution is a critical factor for ovarian dysfunction through mitochondria-dependent and NF-κB/IL-6-mediated pathway, and PD may serve as a pharmaceutic candidate for air pollution-associated ovarian dysfunction.

Low expression of SEMA6C accelerates the primordial follicle activation in the neonatal mouse ovary.

The primordial follicle assembly, activation and the subsequent development are critical processes for female reproduction. A limited number of primordial follicles are activated to enter the growing follicle pool each wave, and the primordial follicle pool progressively diminishes over a woman's life-time. The number of remaining primordial follicles represents the ovarian reserve. Identification and functional investigation of the factors involved in follicular initial recruitment will be of great significance to the understanding of the female reproduction process and ovarian ageing. In this study, we aimed to study whether and how semaphorin 6C (Sema6c) regulated the primordial follicle activation in the neonatal mouse ovary. The attenuation of SEMA6C expression by SiRNA accelerated the primordial follicle activation in the in vitro ovary culture system. PI3K-AKT-rpS6 pathway was activated when SEMA6C expression was down-regulated. And the LY294002 could reverse the effect of low SEMA6C expression on primordial follicle activation. Our findings revealed that Sema6c was involved in the activation of primordial follicles, and the down-regulation of SEMA6C led to massive primordial follicle activation by interacting with the PI3K-AKT-rpS6 pathway, which might also provide valuable information for understanding premature ovarian failure and ovarian ageing.

[Design, synthesis and biological evaluation of novel diaryl ethers bearing a pyrimidine motif as human Pin1 inhibitors].

Pin1 (peptidyl-prolyl cis-trans isomerase NIMA-interacting 1) belongs to peptidyl-prolyl cis-trans isomerase (PPIase) and is a novel promising anticancer target. Based on the lead structure of benzophenone, a series of novel diarylether derivatives containing a pyrimidine ring were designed and synthesized. The inhibitory activities on Pin1 of compounds 5a-5d and 6a-6i were evaluated by a protease-coupled enzyme assay. Of all the evaluated compounds, 6 compounds displayed inhibitory activities. Molecular docking was performed using FlexX algorithm to explore the binding mode of the active molecules.

Low WIP1 Expression Accelerates Ovarian Aging by Promoting Follicular Atresia and Primordial Follicle Activation.

Our previous study demonstrated that ovarian wild-type P53-induced phosphatase 1 (WIP1) expression decreased with age. We hypothesized that WIP1 activity was related to ovarian aging. The role of WIP1 in regulating ovarian aging and its mechanisms remain to be elucidated. Adult female mice with or without WIP1 inhibitor (GSK2830371) treatment were divided into three groups (Veh, GSK-7.5, GSK-15) to evaluate the effect of WIP1 on ovarian endocrine and reproductive function and the ovarian reserve. In vitro follicle culture and primary granulosa cell culture were applied to explore the mechanisms of WIP1 in regulating follicular development. This study revealed that WIP1 expression in atretic follicle granulosa cells is significantly lower than that in healthy follicles. Inhibiting WIP1 phosphatase activity in mice induced irregular estrous cycles, caused fertility declines, and decreased the ovarian reserve through triggering excessive follicular atresia and primordial follicle activation. Primordial follicle depletion was accelerated via PI3K-AKT-rpS6 signaling pathway activation. In vitro follicle culture experiments revealed that inhibiting WIP1 activity impaired follicular development and oocyte quality. In vitro granulosa cell experiments further indicated that downregulating WIP1 expression promoted granulosa cell death via WIP1-p53-BAX signaling pathway-mediated apoptosis. These findings suggest that appropriate WIP1 expression is essential for healthy follicular development, and decreased WIP1 expression accelerates ovarian aging by promoting follicular atresia and primordial follicle activation.

Maternal exposure to PM2.5 decreases ovarian reserve in neonatal offspring mice through activating PI3K/AKT/FoxO3a pathway and ROS-dependent NF-κB pathway.

There is evidence of an association between exposure to ambient fine particulate matter (PM2.5) and female ovarian dysfunction in adults. However, it is not fully clear whether maternal exposure to PM2.5 negatively affects the ovarian function in offspring. The size of primordial follicle pool, definitely assembled during fetal life, determines ovarian reserve and ovarian function. In this study, female C57BL/6 mice were exposed to either ambient PM2.5 (mean daily concentration 49 µg/m3) or filtered air through a whole-body exposure system for 4 weeks before mating, and remained exposed until postpartum. We found that maternal exposure to PM2.5 reduces the initial size of primordial follicle pool and impairs its development in offspring mice. The number of primordial follicles and total follicles was decreased in PM2.5-exposed offspring mice on postnatal day 3 (PND3) and postnatal day 7 (PND7). Maternal PM2.5 exposure promoted the activation of primordial follicles and upregulated the level of p-AKT in offspring mice, accelerating the depletion of primordial follicle pool. While LY294002, a specific inhibitor of PI3K, reversed the overactivation of primordial follicles induced by PM2.5. Besides, maternal PM2.5 exposure induced follicular atresia and granulosa cell apoptosis, increased the accumulation of lipid peroxidation products 4-HNE, and elevated the expression of oxidative stress-related genes and p-p65, p-IκBα in offspring mice. While N-acetylcysteine (NAC) pretreatment abolished the increases of apoptosis, reactive oxygen species (ROS), p-p65 and p-IκBα levels in ovarian granulosa COV434 cells induced by PM2.5 exposure. These findings reveal that maternal exposure to PM2.5 decreases the initial size of primordial follicle pool, and impairs ovarian follicular development in offspring mice. Our data suggest that this involves the activation of the PI3K/AKT/FoxO3a pathway and the ROS-dependent NF-κB pathway. Our study implicates a link between maternal PM2.5 exposure and ovarian reserve in offspring, and improves our understanding of the effects of PM2.5 on reproductive health.

Prenatal exposure to propylparaben at human-relevant doses accelerates ovarian aging in adult mice.

Embryonic exposure to environmental chemicals may result in specific chronic diseases in adulthood. Parabens, a type of environmental endocrine disruptors widely used in pharmaceuticals and cosmetics, have been shown to cause a decline in women's reproductive function. However, whether exposure to parabens during pregnancy also negatively affect the ovarian function of the female offspring in adulthood remains unclear. This study aims to investigate the effects of prenatal propylparaben (PrP) exposure on the ovarian function of adult mice aged 46 weeks, which is equivalent to the age of 40 years in women. Pregnant ICR mice were intraperitoneally injected with human-relevant doses of PrP (i.e., 0, 7.5, 90, and 450 mg/kg/day) during the fetal sex determination period-from embryonic day E7.5 to E13.5. Our results revealed that ovarian aging was accelerated in PrP-exposed mice at 46 weeks, with altered regularity of the estrous cycle, decreased serum estrogen (E2) and progesterone (P4) levels, reduced size of the primordial follicle pool, and increased number of atretic follicles. It was found that prenatal exposure to human-relevant doses of PrP exacerbated ovarian oxidative stress, inflammation, and fibrosis, which promoted follicular atresia by activating the mitochondrial apoptosis pathway. To compensate, the depletion of primordial follicles was also accelerated by activating the PI3K/AKT/mTOR signaling pathway in PrP-exposed mice. Moreover, PrP induced hypermethylation of CpG sites in the promoter region of Cyp11a1 (a 17.16-64.28% increase) partly led to the disrupted steroidogenesis, and the altered methylation levels of imprinted genes H19 and Peg3 may also contribute to the phenotypes observed. These remarkable findings highlight the embryonic origin of ovarian aging and suggest that a reduced use of PrP during pregnancy should be advocated.