Tian-Tian Yu

Bisphenol A Exposure May Induce Hepatic Lipid Accumulation via Reprogramming the DNA Methylation Patterns of Genes Involved in Lipid Metabolism.

Accumulating evidence suggests a role of bisphenol A (BPA) in metabolic disorders. However, the underlying mechanism is still unclear. Using a mouse BPA exposure model, we investigated the effects of long-term BPA exposure on lipid metabolism and the underlying mechanisms. The male mice exposed to BPA (0.5 μg BPA /kg/day, a human relevant dose) for 10 months exhibited significant hepatic accumulation of triglycerides and cholesterol. The liver cells from the BPA-exposed mice showed significantly increased expression levels of the genes related to lipid synthesis. These liver cells showed decreased DNA methylation levels of Srebf1 and Srebf2, and increased expression levels of Srebf1 and Srebf2 that may upregulate the genes related to lipid synthesis. The expression levels of DNA methyltransferases were decreased in BPA-exposed mouse liver. Hepa1-6 cell line treated with BPA showed decreased expression levels of DNA methyltransferases and increased expression levels of genes involved in lipid synthesis. DNA methyltransferase knockdown in Hepa1-6 led to hypo-methylation and increased expression levels of genes involved in lipid synthesis. Our results suggest that long-term BPA exposure could induce hepatic lipid accumulation, which may be due to the epigenetic reprogramming of the genes involved in lipid metabolism, such as the alterations of DNA methylation patterns.

Cardiovascular Dysfunction in Offspring of Ovarian-Hyperstimulated Women and Effects of Estradiol and Progesterone: A Retrospective Cohort Study and Proteomics Analysis

CONTEXT The cardiovascular dysfunction in children born with assisted reproductive technologies has been of great concern. However, the association of ovarian hyperstimulation syndrome (OHSS), a complication of assisted reproductive technologies, with worse cardiovascular functions and underlying mechanism remains unknown. OBJECTIVES The objective of the study was to assess the cardiovascular functions of children born to mothers with OHSS and investigate the underlying regulator(s). DESIGN AND SETTING This was a retrospective cohort recruited in a university hospital. PARTICIPANTS AND METHODS We assessed the cardiovascular functions by Doppler echography in 42 children born to OHSS women, 34 children of mothers with non-OHSS in vitro fertilization, and 48 spontaneously conceived (SC) children (mean age ∼ 4.5 y). Groups were matched for gestational age at delivery and birth weight. An isobaric tag for relative and absolute quantitation-labeled proteomics analysis was performed with another set of umbilical arteries from OHSS and SC pregnancies (n = 3 for both groups). RESULTS Children of OHSS mothers showed a significantly decreased mitral ratio of early to late mitral peak velocities, reduced systolic and diastolic diameters of common carotid arteries, and impaired flow-mediated dilation compared with non-OHSS in vitro fertilization and SC children. Intima-media thickness and arterial stiffness indices were similar in the three groups. In the proteomics study, 1640 proteins were identified from OHSS and SC umbilical arteries, and 40 differentially expressed proteins were selected for further analysis. Estradiol and progesterone were identified as activated upstream regulators. CONCLUSIONS Children born to ovarian-hyperstimulated women displayed cardiovascular dysfunctions. The underlying mechanisms may involve the effects of supraphysiological estradiol and progesterone levels.

High Maternal Serum Estradiol Levels Induce Dyslipidemia in Human Newborns via a Hepatic HMGCR Estrogen Response Element

While the intrauterine environment is essential for the health of offspring, the impact of high maternal serum estradiol (E2) on lipid metabolism in offspring and the mechanisms are unknown. We found that ovarian stimulation (OS) could result in high E2 levels in women throughout pregnancy. Strikingly, their newborns showed elevated total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels that were positively related with E2 in newborns. In vitro, E2 dose-dependently stimulated TC and LDL-C secretion, and increased expression of the cholesterol synthesis rate-limiting enzyme 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) in HepG2 cells and mouse fetal hepatocytes. In vivo, high maternal E2 was detected and fetal livers also showed significantly higher HMGCR expression in an OS mouse model. Notably, an estrogen response element (ERE) was identified in the HMGCR promoter, indicating that high maternal serum E2 could up-regulate HMGCR expression in fetal hepatocytes via an ERE that in turn induces elevated levels of TC and LDL-C in offspring. Conclusion: OS can induce a high maternal E2 environment, which up-regulates HMGCR expression in fetal hepatocytes via an ERE in the promoter, and induces elevated levels of TC and LDL-C in newborns that may be related to increased risk of metabolic disease in adulthood.

The Association between Polymorphism of INSR and Polycystic Ovary Syndrome: A Meta-Analysis

Polycystic ovary syndrome (PCOS) is the most common gynecological endocrine disorder. The genetic background is believed to play a crucial role in the pathogenesis of PCOS. In recent years, the role of insulin receptor (INSR) polymorphisms in PCOS predisposition has attracted much attention. We performed a meta-analysis to investigate the association between the single nucleotide polymorphisms (SNPs) of INSR and PCOS. Published literature from Pubmed, Embase, and Cochrane CENTRAL was retrieved up until 7 August 2014. A total of 20 case-control studies including 23,845 controls and 17,460 PCOS cases with an average Newcastle-Ottawa quality assessment scale (NOS) score of 6.75 were analyzed. Ninety-eight SNPs distributed in 23 exons and the flanking regions of INSR were investigated, among which 17 SNPs were found to be associated with PCOS. Three SNPs detected in more than three studies were selected for further analyses. Twelve studies including 1158 controls and 1264 PCOS cases entered the analysis of rs1799817, but no significant association was found for every genotype (p > 0.05). Further subgroup stratification by ethnicity and weight did not lead to discovery of significant correlation (p > 0.05). For rs2059806, four studies including 442 controls and 524 PCOS cases were qualified for meta-analysis, and no significant association with PCOS was found for any genotype (p > 0.05). Four studies including 12,830 controls and 11,683 PCOS cases investigated the correlation between rs2059807 and PCOS, and five of the six cohorts indicated a significant impact. Our current meta-analysis suggests no significant correlation between rs1799817/rs2059806 SNPs and susceptibility of PCOS, while rs2059807 could be a promising candidate SNP that might be involved in the susceptibility of PCOS.

Maternal High Estradiol Exposure is Associated with Elevated Thyroxine and Pax8 in Mouse Offspring

Our previous studies have shown that maternal high estradiol (E2) environment increased the risk of thyroid dysfunction in offspring. However, the mechanism involved remains unexplored. To evaluate the thyroid function of offspring after high E2 exposure and to explore the underlying mechanism, we established a high E2 mouse model of early pregnancy, and detected thyroid hormones of their offspring. In thyroids of offspring, the expressions of Tg, Nis, Tpo, Pax8, and Titf1 and CpG island methylation status of Pax8 and genes involved in methylation were analyzed. We found that thyroxine (T4) and FT4 levels of offspring were obviously increased in the high-E2 group, especially in females. In both 3- and 8-week-old offspring of the high-E2 group, Pax8 was significantly up-regulated in thyroid glands, accompanied by the abnormal CpG island methylation status in the promoter region. Furthermore, Dnmt3a and Mbd1 were obviously down-regulated in thyroids of the high E2 group. Besides, the disturbance of thyroid function in females was more severe than that in males, implying that the effects were related to gender. In summary, our study indicated that maternal high E2 exposure disturbed the thyroid function of offspring through the dysregulation and abnormal DNA methylation of Pax8.

XCI-escaping gene KDM5C contributes to ovarian development via downregulating miR-320a

Mechanisms underlying female gonadal dysgenesis remain unclarified and relatively unstudied. Whether X-chromosome inactivation (XCI)-escaping genes and microRNAs (miRNAs) contribute to this condition is currently unknown. We compared 45,X Turner Syndrome women with 46,XX normal women, and investigated differentially expressed miRNAs in Turner Syndrome through plasma miRNA sequencing. We found that miR-320a was consistently upregulated not only in 45,X plasma and peripheral blood mononuclear cells (PBMCs), but also in 45,X fetal gonadal tissues. The levels of miR-320a in PBMCs from 45,X, 46,XX, 46,XY, and 47,XXY human subjects were inversely related to the expression levels of XCI-escaping gene KDM5C in PBMCs. In vitro models indicated that KDM5C suppressed miR-320a transcription by directly binding to the promoter of miR-320a to prevent histone methylation. In addition, we demonstrated that KITLG, an essential gene for ovarian development and primordial germ cell survival, was a direct target of miR-320a and that it was downregulated in 45,X fetal gonadal tissues. In conclusion, we demonstrated that downregulation of miR-320a by the XCI-escaping gene KDM5C contributed to ovarian development by targeting KITLG.

High Leptin Level Attenuates Embryo Development in Overweight/Obese Infertile Women by Inhibiting Proliferation and Promotes Apoptosis in Granule Cell

Obesity appears to be associated with female reproductive dysfunction and infertility. Women with obesity undergoing in vitro fertilization (IVF) had poor oocyte quality, decreased embryo development, and poor pregnancy outcome. However, the mechanism linking obesity to poor reproductive outcomes is still unclear. Obesity is frequently accompanied with elevated leptin levels. Here we aimed to evaluate the effect of high leptin level in follicular fluid (FF) on the proliferation and apoptosis in granule cells and correlate these findings with poor reproductive outcomes in infertile women with overweight or obesity who underwent IVF treatment. We investigated clinical and ongoing pregnancy rates in 189 infertile women who underwent IVF. Leptin levels were quantified in peripheral blood and FF as well. In vitro cell model was used to explore the potential effect of high leptin on the proliferation and apoptosis in granulosa cells. Results showed reduced clinical and ongoing pregnancy rates in overweight/obesity women who underwent IVF compared to control with normal BMI. On the other hand, leptin levels presented significant increase in peripheral blood and FF in overweight/obese women. Leptin level in FF was negatively correlated to good quality embryo rate. Importantly, in vitro study showed that leptin inhibited cells proliferation and promoted apoptosis by upregulation of caspase-3 and downregulation of Bcl-2 in granulosa cells in a dose dependent manner. These observations suggest that leptin may acts as a local mediator to attenuate embryo development and reduce fertility in obese patients.

Improving the effectiveness of lifestyle interventions for gestational diabetes prevention: a meta‐analysis and meta‐regression

Diet and exercise during pregnancy have been used to prevent gestational diabetes mellitus (GDM) with some success.

Reduced alternative splicing of estrogen receptor alpha in the endometrium of women with endometriosis

Endometriosis is a condition which involves the presence of uterine stroma and glands outside of the uterine cavity and represents one of the most prevalent disorders of the female reproductive tract. The key symptom of endometriosis is pain, including dysmenorrhea, deep dyspareunia, and chronic pelvic pain. As such, endometriosis has significant economic consequences within the healthcare system and can influence the daily quality of life in affected patients. However, the pathophysiology of this disease and the mechanisms in which this condition generates pain are very unclear. This study, involving 30 women with endometriosis and 28 controls without endometriosis, aimed to investigate relative levels of estrogen receptor alpha (ERα) splice variants in the endometrium of women with and without endometriosis and investigate potential links to the severity of pain. Wild type (wt)-ERα was dominantly expressed in human endometrium while the expression of ERα-del.4, ERα-del.7, and ERα-del.3,4 was significantly reduced in endometriosis patients compared with healthy patients (p < 0.05). Furthermore, the relative ratios of wtERα:ERα-del.4, and wtERα:ERα-del.3,4 were associated with the severity of pain in endometriosis patients (p < 0.05). Consequently, analyzing differences in the relative levels of four types of ERα splice variant in the endometrium of patients with endometriosis may help in the development of endometriosis-targeted treatment and the development of appropriate therapies.

Reduced Intellectual Ability in Offspring of Ovarian Hyperstimulation Syndrome: A Cohort Study

Background Ovarian hyperstimulation syndrome (OHSS), a complication of ovarian stimulation, has various adverse effects on both pregnant women and their offspring. However, whether OHSS will affect intellectual ability in offspring is still unknown. Methods We recruited 86 Chinese children born to OHSS women and 172 children conceived with non-OHSS In Vitro Fertilization (IVF) in this cohort study. Their intellectual ability was assessed according to the Revised Chinese Version of the Wechsler Intelligence Scale for Children (C-WISC). Verbal Intelligence Quotient (VIQ), Performance Intelligence Quotient (PIQ), and Full Intelligence Quotient (FIQ) were calculated. The investigation was registered in Chinese Clinical Trial Registry (ChiCTR-SOC-16009555). Findings OHSS offspring scored less on C-WISC (mean (standard deviation [SD]): (VIQ = 92.7 (14.7), PIQ = 108.9 (13.1), FIQ = 100.6 (13.4)) compared with non-OHSS IVF offspring (VIQ = 100.1 (13.2), PIQ = 113.7 (10.8), FIQ = 107.4 (11.5)). The prevalence of low IQ (< 80) children was 4.7 times higher in OHSS offspring compared with non-OHSS offspring. Maternal estradiol level on hCG administration day was negatively associated with FIQ in offspring. Interpretation OHSS offspring displayed reduced intellectual ability. Prenatal estradiol exposure might be involved in underlying mechanism.