Ting Ding

Expression Patterns and Regulatory Functions of MicroRNAs During the Initiation of Primordial Follicle Development in the Neonatal Mouse Ovary

ABSTRACT The initiation of primordial follicle development is essential for female fertility, but the signals that trigger this process are poorly understood. Given the potentially important roles of microRNAs (miRNAs) in the ovary, we aimed to study the expression patterns and regulatory functions of miRNAs during the initiation of primordial follicle development. Expression patterns of miRNA in the neonatal mouse ovary were profiled by microarray, and 24 miRNAs whose abundances differed significantly between ovaries from 3- and 5-day-old mice were identified. Pathway enrichment analysis revealed that 48 signal transduction pathways are modulated by the up-regulated miRNAs and 29 pathways are modulated by the down-regulated miRNAs (P-value and false discovery rate < 0.001). A miRNA-mRNA regulatory network was established for TGF-beta signaling pathway-related genes. Among the miRNAs involved in this pathway, miR-145 was chosen for further analysis. Down-regulation of miR-145 using an antagomir (AT) decreased the proportion and number of the primordial follicles and increased that of the growing follicles in the cultured ovaries (P < 0.05). The mean oocyte diameter in the primordial follicles was significantly greater in the AT group relative to the AT-negative control group (P < 0.05), whereas the mean oocyte diameter in growing follicles was smaller in the AT group than in the AT-negative control group. In addition, we confirmed that miR-145 targets Tgfbr2. The miR-145 AT caused an increase in TGFBR2 expression and activation of Smad signaling but did not affect the p38 MAPK or JNK pathway. These data suggest that miRNAs and the signaling pathways they modulate are involved in the initiation of primordial follicle development, and miR-145 targets Tgfbr2 to regulate the initiation of primordial follicle development and maintain primordial follicle quiescence.

Peroxiredoxin 2 Inhibits Granulosa Cell Apoptosis During Follicle Atresia Through the NFKB Pathway in Mice

Peroxiredoxin 2 (PRDX2) has been known to act as an antioxidant enzyme whose main function is H2O2 reduction in cells. We aimed to study the expression patterns of PRDX2 in mouse ovaries and explore the function of this protein in apoptosis of granulosa cells (GCs). We found that the expression of the PRDX2 protein in atretic follicle GCs was markedly higher than in healthy follicle GCs. In vitro, the transfection of siRNA targeting the Prdx2 gene inhibited the proliferation and induced the apoptosis of primary cultured GCs. Furthermore, suppression of PRDX2 resulted in the augmentation of endogenous H2O2, and the ability to eliminate the exogenous H2O2 was attenuated. The expression of PRDX2 and nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB), whose activity was inhibited by binding to IKB, increased in GCs treated with various concentrations of H2O2 for 30 min. However, no significant change in cytoplasmic IKB expression was observed. At 2 h after treatment with H2O2, nuclear NFKB expression level was reduced, cytoplasmic IKB expression was increased, and PRDX2 expression was unchanged. Silencing of the Prdx2 gene caused early changes in NFKB and IKB expression in the primary cultured GCs compared to that in control cells. Taken together, these data suggest that PRDX2 plays an important role in inhibiting apoptosis in GCs and that PRDX2 actions may be related to the expression of NFKB and IKB.

Age-Specific Normal Reference Range for Serum Anti-Müllerian Hormone in Healthy Chinese Han Women: A nationwide Population-Based Study.

Background: The increasing use of anti-Müllerian hormone (AMH) in clinic has raised concerns regarding the reliable reference range for this test. However, the reference range for AMH in normal Chinese female population has not been established. Furthermore, relationship between AMH and other clinical markers such as body mass index (BMI) and antral follicle counts (AFCs) and other sex-related hormones have not been examined in normal population-based women. Objective: We aimed to determine the age-specific reference range for serum AMH in healthy Chinese women throughout reproductive age to menopause and to estimate relationship between AMH and other clinical markers in healthy women. Study Design: In this multicenter and nationwide study, advertisements were used to recruit 2055 women, aged 20 to 55 years, from 6 different regions in China; 1590 (77.37%) women met the inclusion criteria for the reference range population. We measured the baseline serum AMH levels using new Beckman Coulter Gen II assay. Serum concentration of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), testosterone (T), prolactin (PRL), progesterone (PRG), and AFCs were also determined in the follicular phase. Main Outcome Measures: The AMH-Age nomogram and AMH levels of different age-groups and the relationship between AMH and other clinical markers. Results: Serum AMH concentrations declined progressively with age. A quadratic model defined as log (AMH) = (−1.970 + 0.296 × Age − 0.006 × Age2) fitted best the decline of AMH with age. The median AMH levels were 6.23, 5.65, 4.55, 3.74, 2.78, and 1.09 ng/mL for the 20 ≤ age < 25, 25 ≤ age < 30, 30 ≤ age < 33, 33 ≤ age < 37, 37 ≤ age < 40, and 40 ≤ age < 55 groups, respectively. The 5th to 95th percentiles of the AMH levels, as the reference range, were 2.06 to 12.66, 1.77 to 13.83, 1.48 to 11.45, 0.87 to 9.76, 0.56 to 9.49, and 0.08 to 5.70 ng/mL for each age-group. The AMH levels were positively correlated with AFCs and T, LH, PRL and PRG levels and negatively correlated with BMI and FSH levels and were not significantly correlated with E2 levels. The relationship between AMH and other variables remain unchanged except for PRL, which was not significantly correlated with AMH levels after controlling for both age and BMI. Conclusions: This study determined the normal reference ranges for serum AMH levels in a large population-based sample of healthy Chinese women.

ERβ expression in the endothelium ameliorates ischemia/reperfusion-mediated oxidative burst and vascular injury.

Estrogen and estrogen receptors (ERs) have been reported to play protective roles in ischemia/reperfusion (I/R)-mediated injury, but the detailed mechanism remains to be fully understood. Nitric oxide (NO) and reactive oxygen species (ROS) also play important roles in the I/R process; however, due to the lack of sensitive and reproducible in vivo monitoring systems, we still do not have direct evidence for the effect of NO and ROS in vivo. In this study, we have established reliable in vivo monitoring systems to measure the variations in circulating ROS and NO during the I/R. We found that during the first few minutes of post-ischemia reperfusion, an oxidative burst occurred concurrent with a rapid loss of NO. Expression of ERβ in the endothelium reduced these effects that accompanied an attenuation in myocardial infarction and vascular damage. Further investigation showed that Tie2-driven lentivirus delivery of ERβ to the vascular wall in rats increased the expression of its target genes in the endothelium, including ERRα, SOD2 and eNOS. These changes modulate ROS generation, DNA damage, and mitochondrial function in rat endothelial cells. We also found that ERβ expression in the endothelium reduced ROS generation and restored mitochondrial function in cardiomyocytes; this may be due to ERβ-mediated NO formation and its high diffusibility to cardiomyocytes. We conclude that ERβ expression in the endothelium ameliorates ischemia/reperfusion-mediated oxidative burst and vascular injury.

SIRT1-mediated ERβ suppression in the endothelium contributes to vascular aging.

SIRT1 has many important molecular functions in aging, and the estrogen receptors (ERs) have a vasculoprotective effect, although the detailed mechanism for the roles of SIRT1 and ERs in vascular aging remains unclear. We found that ERβ expression in the endothelium was reduced in aging mice, and the expression of ERα and SIRT1 did not change, while SIRT1 activity declined. Further investigation showed that the ERβ expression was regulated by SIRT1 through complexes of SIRT1‐PPARγ/RXR‐p300 that bind to a PPRE (PPAR response element) site on the ERβ promoter, and the declined SIRT1 function in aging mice was due to compromised phosphorylation at S154. A single‐mutant SIRT1‐C152(D) restored the reduced ERβ expression in the endothelium with minimized reactive oxygen species generation and DNA damage and increased mitochondrial function and fatty acid metabolism. In high‐fat diet aging mice, the endothelium‐specific delivery of ERβ or SIRT1‐C152(D) on the vascular wall reduced the circulating lipids with ameliorated vascular damage, including the restored vessel tension and blood pressure. We conclude that SIRT1‐mediated ERβ suppression in the endothelium contributes to vascular aging, and the modulation of SIRT1 phosphorylation through a single‐mutant SIRT1‐C152(D) restores this effect.

Effects of culture and transplantation on follicle activation and early follicular growth in neonatal mouse ovaries

Mouse models have been widely utilized to elucidate the basic principles and regulatory mechanisms of primordial follicle activation. Outside their natural environment, the growth of follicles might be affected by unknown factors in vitro and the elimination of regulation in vivo. Currently, in vitro culture and transplantation of ovaries under the kidney capsule are two commonly used incubation methods. However, the limited number of studies that have been published compare various incubation systems and reveal differences between ovaries that are incubated and grown in vivo. We compare the number of primordial, primary and secondary follicles in cultured, transplanted and in-vivo-grown ovaries. We investigate the expression levels of four genes, including zona pellucida 3 (ZP3), growth and differentiation factor-9 (GDF-9), proliferating cell nuclear antigen (PCNA) and anti-Müllerian hormone (AMH). Our results suggest that in vitro culture accelerates follicle activation, delays the transition from primary to secondary follicles and affects the expression patterns of ZP3, GDF-9, PCNA and AMH. A larger number of secondary follicles in ovaries cultured in alpha-minimal essential medium (α-MEM) had intact zona pellucida compared with those grown in Dulbecco’s modified Eagle medium containing Ham’s F-12 nutrient mixture (D/F12), suggesting that α-MEM is a better basal medium. The transplanted ovaries demonstrated the most similar characteristics to the in-vivo-grown ovaries, indicating that transplantation provided an optimal environment for ovarian incubation. This study has thus established the similarities and differences between in-vivo-grown and incubated ovaries, demonstrated that transplantation can mostly mimic the environment of ovarian growth in vivo and determined the optimal basal culture medium between α-MEM and D/F12.

Isolation and identification of ovarian theca‐interstitial cells and granulose cells of immature female mice

Theca‐interstitial cells (TICs) and granulosa cells (GCs) are important components of follicles that support follicle development and hormone secretion, and are considered to be important cell models for basic research. However, no method currently exists for simultaneously isolating TICs and GCs from a single ovary of the immature mouse. Here, we sought to develop such a protocol using mechanical dissection combined with brief collagenase‐DNase digestion. Morphological characteristics and molecular markers were detected to identify TICs and GCs. In isolated TICs, cholesterol side chain cleavage cytochrome P450 (P450scc) was expressed abundantly, but anti‐Mullerian hormone (AMH) was expressed only at very low levels. This expression profile was reversed in GCs. In addition, TICs secreted large amounts of testosterone (T) and minimal amounts of estradiol (E2), while the converse was found in GCs. T concentrations rose gradually in TIC culture media as the concentration of added luteinizing hormone (LH) was increased. In GCs, E2 secretion increased as the follicle‐stimulating hormone (FSH) concentration increased. Thus, mechanical dissection combined with collagenase‐DNase digestion is a simple, effective and reproducible method for obtaining large numbers of highly purified and hormonally stimulated TICs and GCs from one ovary.

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 womans 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.

Early response to neoadjuvant chemotherapy can help predict long-term survival in patients with cervical cancer

It is still controversial whether cervical cancer patients with clinical responses after neoadjuvant chemotherapy (NACT) have a better long-term survival or not. This study was designed to investigate the effect of the clinical response on the disease-free survival (DFS) of cervical cancer patients undergoing NACT. A total of 853 patients from a retrospective study were used to evaluate whether the clinical response was an indicator for the long-term response, and 493 patients from a prospective cohort study were used for further evaluation. The survival difference was detected by log-rank test, univariate and multivariate Cox regression and a pooled analysis. The log-rank test revealed that compared with non-responders, the DFS of responders was significantly higher in the retrospective data (P = 0.007). Univariate Cox regression showed that the clinical response was an indicator of long-term survival in the retrospective study (HR 1.83, 95% CI 1.18-2.85, P = 0.007). In a multivariate Cox model, the clinical response was still retained as an independent significant prognostic factor in the retrospective study (HR 1.59, 95% CI 1.01-2.50, P = 0.046). The result was also validated in the prospective data with similar results. These findings implied that the clinical response can be regarded as an independent predictor of DFS.

Comparison of surgical indications for hysterectomy by age and approach in 4653 Chinese women.

Approximately one million hysterectomies are performed each year in China. However, national data regarding the indications and the surgical approaches for hysterectomy are lacking. The aim of this study was to examine the surgical indications for hysterectomy in different age groups and the relative merits of different surgical approaches for hysterectomy in Chinese women. Clinical data from 4653 cases of hysterectomy performed in Tongji Hospital from 2004 to 2009 were analysed. Hysterectomy was most commonly performed among women aged 40–49 years (2299; 49.4%). Overall, colporrhagia and abdominal pain were the two most common indications for hysterectomy. The most common indications by age groups were as follows: malignant ovarian tumour, < 20 years; malignant uterine tumour, 20–29 and 30–39 years; uterine myoma, 40–49 and 50–59 years; and uterine prolapse, 60–69 and > 70 years. The proportion of malignant aetiology also varied by age, being the highest in women aged < 20 years (75.0%) and the lowest in those aged 40–49 years (19.9%). Approximately 35% women who had hysterectomies also had concomitant bilateral oophorectomy. The lowest rate of oophorectomy occurred in women aged 30–39 years (15.8%), whereas the highest rate was in those aged 50–59 years (75.9%). The abdominal surgical approach was used in 84% of all hysterectomies. Surgeries using the vaginal approach required a significantly shorter operating time (118 min average) than all other approaches (P < 0.05). Both the amount of bleeding and the blood transfusion volume required were smaller in vaginal approaches, with no significant differences between the others. The surgical approaches used were also related to the scope of surgery. Both the surgical indications and the rates of bilateral oophorectomy varied by age. In terms of both operating time and the amount of bleeding and blood transfusion volume required, the vaginal approach was superior to all other surgical approaches.