Gestational diabetes mellitus (GDM) has been shown to be associated with high risk of diabetes in offspring. However, the mechanisms involved and the possibilities of transgenerational transmission are still unclear. We intercrossed male and female adult control and first-generation offspring of GDM (F1-GDM) mice to obtain the second-generation (F2) offspring in four groups: C♂-C♀, C♂-GDM♀, GDM♂-C♀, and GDM♂-GDM♀. We found that birth weight significantly increased in F2 offspring through the paternal line with impaired glucose tolerance (IGT). Regardless of birth from F1-GDM with or without IGT, high risk of IGT appeared as early as 3 weeks in F2 offspring and progressed through both parental lineages, especial the paternal line. IGT in male offspring was more obvious than that in females, with parental characteristics and sex-specific transmission. In both F1 and F2 offspring of GDM, the expression of imprinted genes Igf2 and H19 was downregulated in pancreatic islets, caused by abnormal methylation status of the differentially methylated region, which may be one of the mechanisms for impaired islet ultrastructure and function. Furthermore, altered Igf2 and H19 gene expression was found in sperm of adult F1-GDM, regardless of the presence of IGT, indicating that changes of epigenetics in germ cells contributed to transgenerational transmission.

Increased fat mass and fat redistribution are commonly observed in aging populations worldwide. Although decreased circulating levels of sex hormones, androgens and oestrogens have been observed, the exact mechanism of fat accumulation and redistribution during aging remains obscure. In this study, the receptor of follicle-stimulating hormone (FSH), a gonadotropin that increases sharply and persistently with aging in both males and females, is functionally expressed in human and mouse fat tissues and adipocytes. Follicle-stimulating hormone was found to promote lipid biosynthesis and lipid droplet formation; FSH could also alter the secretion of leptin and adiponectin, but not hyperplasia, in vitro and in vivo. The effects of FSH are mediated by FSH receptors coupled to the Gαi protein; as a result, Ca2+ influx is stimulated, cAMP-response-element-binding protein is phosphorylated, and an array of genes involved in lipid biosynthesis is activated. The present findings depict the potential of FSH receptor-mediated lipodystrophy of adipose tissues in aging. Our results also reveal the mechanism of fat accumulation and redistribution during aging of males and females.

Type 2 diabetes (T2D) and insulin resistance are associated with reduced glucose utilization in the muscle and poor exercise performance. Here we find that depletion of an epigenome modifier, histone deacetylase 3 (HDAC3), specifically in skeletal muscle causes severe systemic insulin resistance in mice, but markedly enhances exercise endurance and muscle fatigue resistance, despite reducing muscle force. This seemingly paradoxical phenotype is due to lower glucose utilization and greater lipid oxidation in HDAC3-depleted muscles, a fuel switch caused by the activation of anaplerotic reactions driven by AMP deaminase 3 (Ampd3) and branched-chain amino acid catabolism. These findings highlight the pivotal role of amino acid catabolism in muscle fatigue and T2D pathogenesis. Further, as genome occupancy of HDAC3 in skeletal muscle is controlled by the circadian clock, these results delineate an epigenomic regulatory mechanism through which the circadian clock governs skeletal muscle bioenergetics. These findings suggest that physical exercise at certain times of the day or pharmacological targeting of HDAC3 could potentially be harnessed to alter systemic fuel metabolism and exercise performance.

The objective of this study was to explore whether hyperandrogenism induces epigenetic alterations of peroxisome proliferator-activated receptor gamma 1 (PPARG1), nuclear corepressor 1 (NCOR1), and histone deacetylase 3 (HDAC3) genes in granulosa cells (GCs) of polycystic ovary syndrome (PCOS) women and whether these alterations are involved in the ovarian dysfunction induced by hyperandrogenism. Thirty-two infertile PCOS women and 147 infertile women with tubal blockage were recruited. PCOS women were divided into the hyperandrogenism (HA) PCOS group (n = 13) and nonhyperandrogenism (N-HA) PCOS group (n = 19). Sixty female Sprague-Dawley rats were used for PCOS model establishment. In GCs of HA PCOS women, PPARG1 mRNA expression was lower, whereas NCOR1 and HDAC3 mRNA expression were higher than N-HA PCOS women and controls (P < 0.05). When all women were divided into successful and failed pregnancy subgroups according to the following clinical pregnancy outcome, we found lower PPARG1 mRNA levels and higher NCOR1 and HDAC3 mRNA levels in the failed subgroup of HA PCOS (P < 0.05). Two hypermethylated CpG sites in the PPARG1 promoter and five hypomethylated CpG sites in the NCOR1 promoter were observed only in HA PCOS women (P < 0.01 to P < 0.0005). The acetylation levels of histone H3 at lysine 9 and p21 mRNA expression were decreased in human GCs treated with dihydrotestosterone in vitro (P < 0.05). PCOS rat models also showed alterations of PPARG1, NCOR1, and HDAC3 mRNA expression and methylation changes of PPARG1 and NCOR1, consistent with the results from humans. Hyperandrogenism induces the epigenetic alterations of PPARG1, NCOR1, and HDAC3 in GCs, which are involved in the ovarian dysfunction of HA PCOS.

Nuclear receptor corepressor 1 (NCOR1) and NCOR2 (also known as SMRT) regulate gene expression by activating histone deacetylase 3 through their Deacetylase Activation Domain (DAD). We show that mice with DAD knock-in mutations have memory deficits, reduced anxiety levels, and reduced social interactions. Mice with NCOR1/2 depletion specifically in GABAergic neurons (NS-V mice) recapitulated the memory deficits and had reduced GABRA2 expression in lateral hypothalamus GABAergic neurons (LH GABA ). This was associated with LH GABA neuron hyperexcitability and impaired hippocampal long-term potentiation, through a monosynaptic LH GABA to CA3 GABA projection. Optogenetic activation of this projection caused memory deficits, while targeted manipulation of LH GABA or CA3 GABA neuron activity reversed memory deficits in NS-V mice. We describe de novo variants in NCOR1, NCOR2 or HDAC3 in patients with intellectual disability or neurodevelopmental defects. These findings identify a hypothalamus–hippocampus projection that may link endocrine signals with synaptic plasticity through NCOR-mediated regulation of GABA signaling.

Overweight and obesity are related with impared ovarian response, and negatively affect the outcomes of IVF.

The effects of diabetes mellitus include long-term damages, dysfunctions, and failures of various organs. An important complication of diabetes is the disturbance in the male reproductive system. Glucose metabolism is an important event in spermatogenesis. Moreover, glucose metabolism is also important for maintaining basic cell activity, as well as specific functions, such as motility and fertilization ability in mature sperm. Diabetic disease and experimentally induced diabetes both demonstrated that either type 1 diabetes or type 2 diabetes could have detrimental effects on male fertility, especially on sperm quality, such as sperm motility, sperm DNA integrity, and ingredients of seminal plasma. Epigenetic modifications are essential during spermatogenesis. The epigenetic regulation represents chromatin modifications including DNA methylation, histone modifications, remodeling of nucleosomes and the higher-order chromatin reorganization and noncoding RNAs. If spermatogenesis is affected during the critical developmental window, embryonic gonadal development, and germline differentiation, environmentally-induced epigenetic modifications may become permanent in the germ line epigenome and have a potential impact on subsequent generations through epigenetic transgenerational inheritance. Diabetes may influence the epigenetic modification during sperm spermatogenesis and that these epigenetic dysregulation may be inherited through the male germ line and passed onto more than one generation, which in turn may increase the risk of diabetes in offspring.

BackgroundEarly pregnancy loss (EPL) is a frustrating clinical problem, whose mechanisms are not completely understood. DNA methylation, which includes maintenance methylation and de novo methylation directed by DNA methyltransferases (DNMTs), is important for embryo development. Abnormal function of these DNMTs may have serious consequences for embryonic development.MethodsTo evaluate the possible involvement of DNA methylation in human EPL, the expression of DNMT proteins and global methylation of DNA were assessed in villous or decidua from EPL patients. The association of maintenance methylation with embryo implantation and development was also examined.ResultsWe found that DNMT1 and DNMT3A were both expressed in normal human villous and decidua. DNMT1 expression and DNA global methylation levels were significantly down-regulated in villous of EPL. DNMT3A expression was not significantly changed in the EPL group compared to controls in either villous or decidua. We also found that disturbance of maintenance methylation with a DNMT1 inhibitor may result in a decreased global DNA methylation level and impaired embryonic development in the mouse model, and inhibit in vitro embryo attachment to endometrial cells.ConclusionsOur results demonstrate that defects in DNA maintenance methylation in the embryo, not in the mother, are associated with abnormal embryonic implantation and development. The findings of the current study provide new insights into the etiology of EPL.