Altered expression of long noncoding RNA MEG3 in the offspring of gestational diabetes mellitus induces impaired glucose tolerance in adulthood.

AIM: Gestational diabetes mellitus (GDM) affects a significant number of women worldwide and has been associated with lifelong health consequences for their offspring, including increased susceptibility to obesity, insulin resistance, and type II diabetes. Recent studies have suggested that aberrant expression of the long non-coding RNA Meg3 in the liver may contribute to impaired glucose metabolism in individuals. In this study, we aimed to investigate whether intrauterine exposure to hyperglycemia affects glucose intolerance in puberty by mediating the overexpression of LncMeg3 in the liver. METHODS: To test our hypothesis, we established an animal model of intrauterine hyperglycemia to mimic GDM. The progeny was observed for phenotypic changes, and intraperitoneal glucose tolerance tests, insulin tolerance tests, and pyruvate tolerance tests were conducted to assess glucose and insulin tolerance. We also measured LncMeg3 expression in the liver using real-time quantitative PCR and examined differential methylation areas (DMRs) in the Meg3 gene using pyrophosphoric sequencing. To investigate the role of LncMeg3 in glucose tolerance, we conducted Meg3 intervention by vein tail and analyzed the changes in the phenotype and transcriptome of the progeny using bioinformatics analysis. RESULTS: We found that intrauterine exposure to hyperglycemia led to impaired glucose and insulin tolerance in the progeny, with a tendency toward increased fasting blood glucose in fat offspring at 16 weeks (P = 0.0004). LncMeg3 expression was significantly upregulated (P = 0.0061), DNMT3B expression downregulated (P = 0.0226), and DNMT3A (P = 0.0026), TET2 (P = 0.0180) expression upregulated in the liver. Pyrophosphoric sequencing showed hypomethylation in Meg3-DMRs (P = 0.0005). Meg3 intervention by vein tail led to a decrease in the percentage of obese and emaciated offspring (emaciation: 44% vs. 23%; obesity: 25% vs. 15%) and attenuated glucose intolerance. Bioinformatics analysis revealed significant differences in the transcriptome of the progeny, particularly in circadian rhythm and PPAR signaling pathways. CONCLUSION: In conclusion, our study suggests that hypomethylation of Meg3-DMRs increases the expression of the imprinted gene Meg3 in the liver of males, which is associated with impaired glucose tolerance in GDM-F1. MEG3 interference may attenuate glucose intolerance, which may be related to transcriptional changes. Our findings provide new insights into the mechanisms underlying the long-term effects of intrauterine hyperglycemia on progeny health and highlight the potential of Meg3 as an intervention target for glucose intolerance.

Long-term outcomes and potential mechanisms of offspring exposed to intrauterine hyperglycemia.

Diabetes mellitus during pregnancy, which can be classified into pregestational diabetes and gestational diabetes, has become much more prevalent worldwide. Maternal diabetes fosters an intrauterine abnormal environment for fetus, which not only influences pregnancy outcomes, but also leads to fetal anomaly and development of diseases in later life, such as metabolic and cardiovascular diseases, neuropsychiatric outcomes, reproduction malformation, and immune dysfunction. The underlying mechanisms are comprehensive and ambiguous, which mainly focus on microbiota, inflammation, reactive oxygen species, cell viability, and epigenetics. This review concluded with the influence of intrauterine hyperglycemia on fetal structure development and organ function on later life and outlined potential mechanisms that underpin the development of diseases in adulthood. Maternal diabetes leaves an effect that continues generations after generations through gametes, thus more attention should be paid to the prevention and treatment of diabetes to rescue the pathological attacks of maternal diabetes from the offspring.

Gestational diabetes mellitus suppresses fetal testis development in mice†.

The prevalence of gestational diabetes mellitus (GDM) is increasing rapidly. In addition to the metabolic disease risks, GDM might increase the risks of cryptorchidism in children. However, its mechanism involved in abnormalities of the male reproductive system is still unclear. The purpose of this study was to study the effects of GDM on the development of mouse fetal Leydig cells (FLCs) and Sertoli cells (SCs). Pregnant mice were treated on gestational days 6.5 and 12.5 with streptozotocin (100 mg/kg) or vehicle (sodium citrate buffer). Leydig cell and SC development and functions were evaluated by investigating serum testosterone levels, cell number and distribution, genes, and protein expression. GDM decreased serum testosterone levels, the anogenital distance, and the level of desert hedgehog in SCs of testes of male offspring. FLC number was also decreased in testes of GDM offspring by delaying the commitment of stem Leydig cells into the Leydig cell lineage. RNA-seq showed that FOXL2, RSPO1/ß-catenin signaling was activated and Gsk3ß signaling was inhibited in GDM offspring testis. In conclusion, GDM disrupted reproductive tract and testis development in mouse male offspring via altering genes related to development.

Integrated Multi-Omics Analysis Reveals the Effect of Maternal Gestational Diabetes on Fetal Mouse Hippocampi.

Growing evidence suggests that adverse intrauterine environments could affect the long-term health of offspring. Recent evidence indicates that gestational diabetes mellitus (GDM) is associated with neurocognitive changes in offspring. However, the mechanism remains unclear. Using a GDM mouse model, we collected hippocampi, the structure critical to cognitive processes, for electron microscopy, methylome and transcriptome analyses. Reduced representation bisulfite sequencing (RRBS) and RNA-seq in the GDM fetal hippocampi showed altered methylated modification and differentially expressed genes enriched in common pathways involved in neural synapse organization and signal transmission. We further collected fetal mice brains for metabolome analysis and found that in GDM fetal brains, the metabolites displayed significant changes, in addition to directly inducing cognitive dysfunction, some of which are important to methylation status such as betaine, fumaric acid, L-methionine, succinic acid, 5-methyltetrahydrofolic acid, and S-adenosylmethionine (SAM). These results suggest that GDM affects metabolites in fetal mice brains and further affects hippocampal DNA methylation and gene regulation involved in cognition, which is a potential mechanism for the adverse neurocognitive effects of GDM in offspring.

Pediatric and adult obesity concerns in female health: a Mendelian randomization study.

PURPOSE: Adulthood and childhood obesity are both associated with reproductive diseases and gynecological cancers in females. However, the causal factors associated with these observations have yet to be identified. Mendelian randomization is a process that is independent of inverse bias and confounding and can act as a random control trial in which genetic groups are settled during meiosis, thus representing an effective tool with which to investigate causality. METHODS: We carried out several Mendelian randomization trials based on the combined genetic scores of 75 adult-associated and 15 childhood-associated body mass index (BMI) single nucleotide polymorphisms (SNPs), databases for several gynecological cancers and reproductive diseases from the UK Biobank (with 194,153 participants), using the traditional inverse-variance weighted (IVW) method as the main method. RESULTS: Elevated adult-associated BMI scores (odds ratio [OR] = 1.003; 95% confidence interval [CI]: 1.001-1.004) and childhood-associated BMI scores (OR = 1.003; 95% CI: 1.001-1.004) were related to a higher risk of the polycystic ovarian syndrome (PCOS), as determined by the traditional IVW method. The random IVW method further revealed a nominal negative causal association between childhood-associated BMI and subsequent endometriosis (OR = 0.995; 95% CI: 0.991-0.999). CONCLUSIONS: Consistent with observational consequences, our findings indicated that adulthood obesity may play role in the development of PCOS and that childhood obesity can increase the risk of PCOS but may reduce the incidence of endometriosis in later life. Further research is now needed to validate our findings and identify the precise mechanisms involved.

Intrauterine Hyperglycemia Alters the Metabolomic Profile in Fetal Mouse Pancreas in a Gender-Specific Manner.

Mounting evidence has shown that intrauterine hyperglycemia exposure during critical stages of development may be contributing to the increasing prevalence of diabetes. However, little is known about the mechanisms responsible for offspring metabolic disorder. In this present study, we explored intrauterine hyperglycemia exposure on fetal pancreatic metabolome, and its potential link to impaired glucose tolerance in adult offspring. Here, using a GDM mouse model, we found the metabolome profiling of pancreas from male and female fetus showing altered metabolites in several important pathways, including 5-methylcytosine, α-KG, branched-chain amino acids, and cystine, which are associated with epigenetic modification, insulin secretion, and intracellular redox status, respectively. This finding suggests that intrauterine exposure to hyperglycemia could cause altered metabolome in pancreas, which might be a metabolism-mediated mechanism for GDM-induced intergenerational diabetes predisposition.

Sex Steroids and Osteoarthritis: A Mendelian Randomization Study.

Objective: Sex steroids are thought to contribute to the pathogenesis of osteoarthritis (OA). This study investigated the causal role of sex steroids in site- and sex-specific OA and risk of joint replacement surgery using the Mendelian randomization (MR) method. Methods: Instrumental variables for estradiol, dehydroepiandrosterone sulfate, testosterone (T), and dihydrotestosterone (DHT) were selected. We used the inverse variance weighting (IVW) approach as the main MR method to estimate causal effects based on the summary-level data for OA and joint replacement surgery from genome-wide association studies (GWAS). Results: A positive causal association was observed between serum T level and risks of hip OA (odds ratio [OR]=1.558, 95% confidence interval [CI]: 1.193-2.034; P=0.001) and hip replacement (OR=1.013, 95% CI: 1.008-1.018; P=2.15×10-8). Serum DHT level was also positively associated with the risk of hip replacement (OR=1.011, 95% CI: 1.006-1.015; P=4.03×10-7) and had potential causality with hip OA (OR=1.398, 95% CI: 1.054-1.855; P=0.020). Conclusions: Serum T and DHT levels may play causal roles in the development of hip OA and contribute to the risk of hip replacement, although the underlying mechanisms require further investigation.

Paternal obesity impairs hepatic gluconeogenesis of offspring by altering Igf2/H19 DNA methylation.

Over the past four decades, the global prevalence of obesity has increased rapidly in all age ranges. Emerging evidence suggests that paternal lifestyle and environmental exposure have a crucial role in the health of offspring. Therefore, the current study investigated the impact of paternal obesity on the metabolic profile of offspring in a male mouse model of obesity. Female offspring of obese fathers fed a high-fat diet (HFD) (60% kcal fat) showed hyperglycemia because of enhanced gluconeogenesis and elevated expression of phosphoenolpyruvate carboxykinase (PEPCK), which is a key enzyme involved in the regulation of gluconeogenesis. Methylation of the Igf2/H19 imprinting control region (ICR) was dysregulated in the liver of offspring, and the sperm, of HFD fathers, suggesting that epigenetic changes in germ cells contribute to this father-offspring transmission. In addition, we explored whether H19 might regulate hepatic gluconeogenesis. Our results showed that overexpression of H19 in Hepa1-6 cells enhanced the expression of PEPCK and gluconeogenesis by promoting nuclear retention of forkhead box O1 (FOXO1), which is involved in the transcriptional regulation of Pepck. Thus, the current study suggests that paternal exposure to HFD impairs the gluconeogenesis of offspring via altered Igf2/H19 DNA methylation.

Intrauterine exposure to hyperglycemia retards the development of brown adipose tissue.

Brown adipose tissue (BAT) is an exclusive tissue of nonshivering thermogenesis. It is fueled by lipids and glucose and involved in energy and metabolic homeostasis. Intrauterine exposure to hyperglycemia during gestational diabetes mellitus may result in abnormal fetal development and metabolic phenotypes in adulthood. However, whether intrauterine hyperglycemia influences the development of BAT is unknown. In this study, mouse embryos were exposed to the intrauterine hyperglycemia environment by injecting streptozocin into pregnant mice at 1 d post coitum (dpc). The structure of BAT was examined by hematoxylin and eosin staining and immunohistochemical analysis. The glucose uptake in BAT was measured in vivo by [18F]-fluoro-2-deoxyglucose-micro-positron emission tomography. The gene expression in BAT was determined by real-time PCR, and the 5'-C-phosphate-G-3' site-specific methylation was quantitatively analyzed. Intrauterine hyperglycemia exposure resulted in the impaired structure of BAT and decreased glucose uptake function in BAT in adulthood. The expressions of the genes involved in thermogenesis and mitochondrial respiratory chain in BAT, such as Ucp1, Cox5b, and Elovl3, were down-regulated by intrauterine hyperglycemia exposure at 18.5 dpc and at 16 wk of age. Furthermore, higher methylation levels of Ucp1, Cox5b, and Elovl3 were found in offspring of mothers with streptozotocin-induced diabetes. Our results provide the evidence for enduring inhibitory effects of intrauterine hyperglycemia on BAT development in offspring. Intrauterine hyperglycemia is associated with increased DNA methylation of the BAT specific genes in offspring, which support an epigenetic involvement.-Yu, D.-Q., Lv, P.-P., Yan, Y.-S., Xu, G.-X., Sadhukhan, A., Dong, S., Shen, Y., Ren, J., Zhang, X.-Y., Feng, C., Huang, Y.-T., Tian, S., Zhou, Y., Cai, Y.-T., Ming, Z.-H., Ding, G.-L., Zhu, H., Sheng, J.-Z., Jin, M., Huang, H.-F. Intrauterine exposure to hyperglycemia retards the development of brown adipose tissue.

Insulin Therapy for Gestational Diabetes Mellitus Does Not Fully Protect Offspring From Diet-Induced Metabolic Disorders.

Gestational diabetes mellitus (GDM) is associated with an increased risk of metabolic disorders in offspring in later life. Although mounting evidence suggests that therapy for GDM could improve neonatal health, whether the therapy confers long-term metabolic benefits to offspring in their later adult lives is not known. Here, using a mouse model of diabetes in the latter half of pregnancy to mimic human GDM, we find that the efficient insulin therapy for GDM confers significant protection against glucose intolerance and obesity in offspring fed a normal chow diet. However, the therapy fails to protect offspring when challenged with a high-fat diet, especially for male offspring. Genome-wide DNA methylation profiling of pancreatic islets from male offspring identified hypermethylated regions in several genes that regulate insulin secretion, including Abcc8, Cav1.2, and Cav2.3 that encode KATP or Ca2+ channels, which are associated with reduced gene expression and impaired insulin secretion. This finding suggests a methylation-mediated epigenetic mechanism for GDM-induced intergenerational glucose intolerance. It highlights that even efficient insulin therapy for GDM is insufficient to fully protect adult offspring from diet-induced metabolic disorders.