Leptin gene expression in human preadipocytes is switched on by maturation-induced demethylation of distinct CpGs in its proximal promoter

A negative feedback loop between TET2 and leptin in adipocyte regulates body weight

Ten-eleven translocation (TET) 2 is an enzyme that catalyzes DNA demethylation to regulate gene expression by oxidizing 5-methylcytosine to 5-hydroxymethylcytosine, functioning as an essential epigenetic regulator in various biological processes. However, the regulation and function of TET2 in adipocytes during obesity are poorly understood. In this study, we demonstrate that leptin, a key adipokine in mammalian energy homeostasis regulation, suppresses adipocyte TET2 levels via JAK2-STAT3 signaling. Adipocyte Tet2 deficiency protects against high-fat diet-induced weight gain by reducing leptin levels and further improving leptin sensitivity in obese male mice. By interacting with C/EBPα, adipocyte TET2 increases the hydroxymethylcytosine levels of the leptin gene promoter, thereby promoting leptin gene expression. A decrease in adipose TET2 is associated with obesity-related hyperleptinemia in humans. Inhibition of TET2 suppresses the production of leptin in mature human adipocytes. Our findings support the existence of a negative feedback loop between TET2 and leptin in adipocytes and reveal a compensatory mechanism for the body to counteract the metabolic dysfunction caused by obesity.

Emerging Trends in Atherosclerosis: Time to Address Atherosclerosis From a Younger Age

Over the past two decades, research efforts into cardiovascular disease (CVD) have uncovered findings that fundamentally challenge our understanding of CVD, particularly atherosclerosis. Atherosclerosis was primarily attributed to the well-described abnormal lipid accumulation theory, involving plaque growth with subsequent plaque hemorrhage resulting in acute vessel thrombosis that may or may not rupture. This perspective has now evolved to encompass more complex pathways, wherein the accumulation of abnormal products of oxidation and inflammation is the most likely factor mediating atherosclerotic plaque growth. Furthermore, atherosclerosis was traditionally thought of as a disease in patients aged 40 and older. However, mounting evidence has demonstrated that significant atherosclerosis and CVD events are more prevalent in younger patients than previously realized and accelerating in incidence. With this alarming trend among younger individuals, our review sought to explore why this trend may be happening and what can be done about this developing problem.

Transcriptional and epigenetic changes after dietary and surgical weight loss interventions in an animal model of obesity

BACKGROUND

Identifying determinants that can predict response to weight loss interventions is imperative for optimizing therapeutic benefit. We aimed to identify changes in DNA methylation and mRNA expression of a subset of target genes following dietary and surgical interventions in high-fat-diet (HFD)-induced obese rats.

METHODS

Forty-two adult Wistar Han male rats were divided into two groups: control rats (n = 7) and obese rats (n = 28), fed a HFD for 10 weeks (t10). Obese rats were randomly subdivided into five intervention groups (seven animals per group): (i) HFD; (ii) very-low-calorie diet (VLCD); (iii) sham surgery, and (iv) sleeve gastrectomy (SG). At week sixteen (t16), animals were sacrificed and tissue samples were collected to analyze changes in DNA methylation and mRNA expression of the selected genes.

RESULTS

By type of intervention, the surgical procedures led to the greatest weight loss. Changes in methylation and/or expression of candidate genes occurred proportionally to the effectiveness of the weight loss interventions. Leptin expression, increased sixfold in the visceral fat of the obese rats, was partially normalized after all interventions. The expression of fatty acid synthase (FASN) and monocyte chemoattractant protein 1 (MCP-1) genes, which was reduced 0.5- and 0.15-fold, respectively, in the liver tissue of obese rats, were completely normalized after weight loss interventions, particularly after surgical interventions. The upregulation of FASN and MCP-1 gene expression was accompanied by a significant reduction in promoter methylation, up to 0.5-fold decrease in the case of the FASN (all intervention groups) and a 0.8-fold decrease in the case of the MCP-1 (SG group).

CONCLUSIONS

Changes in tissue expression of specific genes involved in the pathophysiological mechanisms of obesity can be significantly attenuated following weight loss interventions, particularly surgery. Some of these genes are regulated by epigenetic mechanisms.

Anti-Obesity Effects of Chitosan and Its Derivatives

The number of obese people in the world is rising, leading to an increase in the prevalence of type 2 diabetes and other metabolic disorders. The search for medications including natural compounds for the prevention of obesity is an urgent task. Chitosan polysaccharide obtained through the deacetylation of chitin, and its derivatives, including short-chain oligosaccharides (COS), have hypolipidemic, anti-inflammatory, anti-diabetic, and antioxidant properties. Chemical modifications of chitosan can produce derivatives with increased solubility under neutral conditions, making them potential therapeutic substances for use in the treatment of metabolic disorders. Multiple studies both in animals and clinical trials have demonstrated that chitosan improves the gut microbiota, restores intestinal barrier dysfunction, and regulates thermogenesis and lipid metabolism. However, the effect of chitosan is rather mild, especially if used for a short periods, and is mostly independent of chitosan's physical characteristics. We hypothesized that the major mechanism of chitosan's anti-obesity effect is its flocculant properties, enabling it to collect the chyme in the gastrointestinal tract and facilitating the removal of extra food. This review summarizes the results of the use of COS, chitosan, and its derivatives in obesity control in terms of pathways of action and structural activity.

Placenta DNA methylation levels of the promoter region of the leptin receptor gene are associated with infant cortisol

The intrauterine environment and early life stress regulation are widely recognized as an early foundation for lifelong physical and mental health. Methylation of CpG sites in the placenta represents an epigenetic modification that can potentially affect placental function, influence fetal development, and ultimately impact the health of offspring by programming the hypothalamic-pituitary-adrenal (HPA) axis stress response during prenatal development. Leptin, an adipokine produced by the placenta, is essential for energy homeostasis. It is also epigenetically regulated by promoter DNA methylation. Mounting evidence suggests that leptin also affects the stress response system. Though heterogeneity in the early stress response system may influence life-long mental and physical health, few studies explicitly examine the heterogeneity in the newborn stress response system. Less is known about leptin's association with the human hypothalamic-pituitary-adrenocortical (HPA) axis early in life. This study sought to serve as a proof of concept study investigating the relationship between newborn cortisol output trajectories and placental leptin DNA methylation in 117 healthy newborns from socioeconomically and racially- and ethnically-diverse families. We characterized heterogeneity in newborn cortisol output during the NICU Network Neurobehavioral Scales exam in the first week of life with latent growth mixture models. We then evaluated whether leptin promoter (LEP) methylation in placental samples was associated with newborn cortisol trajectories. Our findings suggest that increased placental LEP methylation, which corresponds to decreased leptin production, is associated with infant cortisol trajectories marked by increased cortisol output in the NNNS exam. These results provide important insights into the role of placental leptin DNA methylation in human newborn HPA axis development and subsequent developmental origins of health and disease processes.

Epigenetic Regulation and its Effects on Aging and Cardiovascular Disease

Cardiovascular disease (CVD), specifically coronary atherosclerosis, is regulated by an interplay between genetic and lifestyle factors. Most recently, a factor getting much attention is the role epigenetics play in atherosclerosis; particularly the development of coronary artery disease. Furthermore, it is important to understand the intricate interaction between the environment and each individual genetic material and how this interaction affects gene expression and consequently influences the development of atherosclerosis. Our main goal is to discuss epigenetic regulations; particularly, the factors contributing to coronary atherosclerosis and their role in aging and longevity. We reviewed the current literature and provided a simplified yet structured and reasonable appraisal of this topic. This role has also been recently linked to longevity and aging. Epigenetic regulations (modifications) whether through histone modifications or DNA or RNA methylation have been shown to be regulated by environmental factors such as social stress, smoking, chemical contaminants, and diet. These sensitive interactions are further aggravated by racial health disparities that ultimately impact cardiovascular disease outcomes through epigenetic interactions. Certainly, limiting our exposure to such causative events at younger ages seems our "golden opportunity" to tackle the incidence of coronary atherosclerosis and probably the answer to longevity.

Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies

Excess body weight is frequently associated with low-grade inflammation. Evidence indicates a relationship between obesity and cancer, as well as with other diseases, such as diabetes and non-alcoholic fatty liver disease, in which inflammation and the actions of various adipokines play a role in the pathological mechanisms involved in these disorders. Leptin is mainly produced by adipose tissue in proportion to fat stores, but it is also synthesized in other organs, where leptin receptors are expressed. This hormone performs numerous actions in the brain, mainly related to the control of energy homeostasis. It is also involved in neurogenesis and neuroprotection, and central leptin resistance is related to some neurological disorders, e.g., Parkinson's and Alzheimer's diseases. In peripheral tissues, leptin is implicated in the regulation of metabolism, as well as of bone density and muscle mass. All these actions can be affected by changes in leptin levels and the mechanisms associated with resistance to this hormone. This review will present recent advances in the molecular mechanisms of leptin action and their underlying roles in pathological situations, which may be of interest for revealing new approaches for the treatment of diseases where the actions of this adipokine might be compromised.

The epigenetic aging, obesity, and lifestyle

The prevalence of obesity has dramatically increased worldwide over the past decades. Aging-related chronic conditions, such as type 2 diabetes and cardiovascular disease, are more prevalent in individuals with obesity, thus reducing their lifespan. Epigenetic clocks, the new metrics of biological age based on DNA methylation patterns, could be considered a reflection of the state of one's health. Several environmental exposures and lifestyle factors can induce epigenetic aging accelerations, including obesity, thus leading to an increased risk of age-related diseases. The insight into the complex link between obesity and aging might have significant implications for the promotion of health and the mitigation of future disease risk. The present narrative review takes into account the interaction between epigenetic aging and obesity, suggesting that epigenome may be an intriguing target for age-related physiological changes and that its modification could influence aging and prolong a healthy lifespan. Therefore, we have focused on DNA methylation age as a clinical biomarker, as well as on the potential reversal of epigenetic age using a personalized diet- and lifestyle-based intervention.

Sexual dimorphism of leptin and adiposity in children between 0 and 10 years: a systematic review and meta-analysis

BACKGROUND

Differences in adolescents and adults by sex in blood levels of leptin and adiposity have been described; however, it is not yet clear if these differences arise from the prepubertal stage in subjects with a normal-weight. Therefore, we examine whether there are differences by sex in levels of blood leptin and adiposity in children with a normal-weight between 0 and 10 years old.

METHODS

Search strategy: eligible studies were obtained from three electronic databases (Ovid, Embase and LILACS) and contact with experts.

SELECTION CRITERIA

healthy children up to 10 years of age with normal-weight according to age.

DATA COLLECTION AND ANALYSES

data were extracted by four independent reviewers using a predesigned data collection form. For the analysis, we stratified according to age groups (newborns, 0.25-0.5 years, 3-5.9 years, 6-7.9 years, 8-10 years). The statistical analysis was performed in the R program.

RESULTS

Of the initially identified 13,712 records, 21 were selected in the systematic review and meta-analysis. The sex was associated with the overall effect on blood leptin (pooled MD = 1.72 ng/mL, 95% CI: 1.25-2.19) and body fat percentage (pooled MD = 3.43%, 95% CI: 2.53-4.33), being both higher in girls. This finding was consistent in the majority of age groups.

CONCLUSION

The results of our meta-analyses support the sexual dimorphism in circulating blood leptin and body fat percentage between girls and boys with normal-weight from prepuberty.

Alteration of serum leptin and LEP/LEPR promoter methylation in Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a rare neurodevelopmental disorder based on a loss of paternally expressed but maternally imprinted genes in chromosome region 15q11-13. PWS individuals typically show insatiable appetite with subsequent obesity representing the major mortality factor unless food intake is inhibited. The neurobiological basis of PWS-typical hyperphagia has remained poorly understood. Many PWS-typical abnormalities are based on hypothalamic dysregulation, a region in which hunger and satiety are hormonally regulated, with the hormone leptin being a main long-term regulator of satiety. Previous studies in PWS have inconsistently shown leptin alterations solely in early childhood, without investigating the leptin system on an epigenetic level. The present study investigates serum leptin levels (S-leptin) and DNA methylation of the leptin (LEP) and leptin receptor gene (LEPR) promoter in 24 individuals with PWS compared to 13 healthy controls matched for sex, age, and body mass index (BMI) and relates the results to the extent of hyperphagia in PWS. S-Leptin levels were obtained by Enzyme-linked Immunosorbent Assay. LEP/LEPR-promoter DNA methylation was assessed by bisulfite-sequencing, hyperphagia by Hyperphagia Questionnaire for Clinical Trials (HQ-CT). PWS and control groups differed significantly in S-leptin levels with higher S-leptin in PWS. Methylation analysis showed significant differences in mean promoter methylation rate both for LEP and LEPR with a lower methylation rate in PWS. LEPR, but not LEP methylation correlated significantly with S-leptin levels. S-leptin and both LEP and LEPR methylation did not correlate with HQ-CT scores in PWS. The present study is the first to show significantly elevated S-leptin levels in an adult PWS cohort combined with an altered, downregulated LEP and LEPR promoter methylation status compared to sex-, age- and BMI-matched controls. Analogous to previous studies, no link to the behavioral dimension could be drawn. Overall, the results suggest an increased leptin dysregulation in PWS, whereby the findings partly mirror those seen in non-syndromic obesity.

Effects of DNA methylation on cardiometabolic risk factors: a systematic review and meta-analysis

Background

Epigenetic changes, especially DNA methylation have a main role in regulating cardiometabolic disorders and their risk factors. This study provides a review of the current evidence on the association between methylation of some genes (LINE1, ABCG1, SREBF1, PHOSPHO1, ADRB3, and LEP) and cardiometabolic risk factors.

Methods

A systematic literature search was conducted in electronic databases including Web of Science, PubMed, EMBASE, Google Scholar and Scopus up to end of 2020. All observational human studies (cross-sectional, case–control, and cohort) were included. Studies that assessed the effect of DNA methylation on cardiometabolic risk factors were selected.

Results

Among 1398 articles, eight studies and twenty-one studies were included in the meta-analysis and the systematic review, respectively. Our study showed ABCG1 and LINE1 methylation were positively associated with blood pressure (Fisher’s zr = 0.07 (0.06, 0.09), 95% CI: 0.05 to 0.08). Methylation in LINE1, ABCG1, SREBF1, PHOSPHO1 and ADRB3 had no significant association with HDL levels (Fisher’s zr = − 0.05 (− 0.13, 0.03), 95% CI:-0.12 to 0.02). Positive association was existed between LINE1, ABCG1 and LEP methylation and LDL levels (Fisher’s zr = 0.13 (0.04, 0.23), 95% CI: 0.03 to 0.23). Moreover, positive association was found between HbA1C and ABCG1 methylation (Fisher’s zr = 0.11 (0.09, 0.13), 95% CI: 0.09 to 0.12). DNA methylation of LINE1, ABCG1 and SREBF1 genes had no significant association with glucose levels (Fisher’s zr = 0.01 (− 0.12, 0.14), 95% CI:-0.12 to 0.14).

Conclusion

This meta-analysis showed that DNA methylation was associated with some cardiometabolic risk factors including LDL-C, HbA1C, and blood pressure.

Registration

Registration ID of the protocol on PROSPERO is CRD42020207677.

Promoter Methylation of LEP and LEPR before and after Bariatric Surgery: A Cross-Sectional Study

INTRODUCTION

DNA methylation constitutes one important epigenetic mechanism that regulates gene expression in human cells. With regard to obesity, bariatric surgery-induced weight loss has been associated with promoter methylation changes in several genes. Hyperleptinemia is a characteristic feature of obesity. The underlying regulating mechanisms have not yet been completely elucidated.

METHODS

We investigated the methylation of the promoters of the leptin gene (LEP) and the leptin receptor gene (LEPR) as well as leptin expression in pre- and postbariatric surgery patients using a comparative cross-sectional design.

RESULTS

Our results revealed significantly higher LEP promoter methylation patterns in prebariatric surgery patients compared to postoperatively. DNA methylation of the LEPR promoter was significantly higher in the postoperative group. Moreover, we found significantly higher leptin serum levels in patients before the bariatric surgery than afterwards.

DISCUSSION

These findings strengthen the suggestion that there is an association between LEP expression and LEP methylation in obesity. We suggest that the epigenetic profile of LEP might be influenced by leptin serum levels in the form of a regulating feedback mechanism.

Maternal Glucose and LDL-Cholesterol Levels Are Related to Placental Leptin Gene Methylation, and, Together With Nutritional Factors, Largely Explain a Higher Methylation Level Among Ethnic South Asians

BACKGROUND

Leptin, mainly secreted by fat cells, plays a core role in the regulation of appetite and body weight, and has been proposed as a mediator of metabolic programming. During pregnancy leptin is also secreted by the placenta, as well as being a key regulatory cytokine for the development, homeostatic regulation and nutrient transport within the placenta. South Asians have a high burden of type 2 diabetes, partly attributed to a "thin-fat-phenotype".

OBJECTIVE

Our aim was to investigate how maternal ethnicity, adiposity and glucose- and lipid/cholesterol levels in pregnancy are related to placental leptin gene (LEP) DNA methylation.

METHODS

We performed DNA methylation analyses of 13 placental LEP CpG sites in 40 ethnic Europeans and 40 ethnic South Asians participating in the STORK-Groruddalen cohort.

RESULTS

South Asian ethnicity and gestational diabetes (GDM) were associated with higher placental LEP methylation. The largest ethnic difference was found for CpG11 [5.8% (95% CI: 2.4, 9.2), p<0.001], and the strongest associations with GDM was seen for CpG5 [5.2% (1.4, 9.0), p=0.008]. Higher maternal LDL-cholesterol was associated with lower placental LEP methylation, in particular for CpG11 [-3.6% (-5.5, -1.4) per one mmol/L increase in LDL, p<0.001]. After adjustments, including for nutritional factors involved in the one-carbon-metabolism cycle (vitamin D, B12 and folate levels), ethnic differences in placental LEP methylation were strongly attenuated, while associations with glucose and LDL-cholesterol persisted.

CONCLUSIONS

Maternal glucose and lipid metabolism is related to placental LEP methylation, whilst metabolic and nutritional factors largely explain a higher methylation level among ethnic South Asians.

Leptin production capacity determines food intake and susceptibility to obesity-induced diabetes in Oikawa-Nagao Diabetes-Prone and Diabetes-Resistant mice

AIMS/HYPOTHESIS

Obesity caused by overeating plays a pivotal role in the development of type 2 diabetes. However, it remains poorly understood how individual meal size differences are determined before the development of obesity. Here, we investigated the underlying mechanisms in determining spontaneous food intake in newly established Oikawa-Nagao Diabetes-Prone (ON-DP) and Diabetes-Resistant (ON-DR) mice.

METHODS

Food intake and metabolic phenotypes of ON-DP and ON-DR mice under high-fat-diet feeding were compared from 5 weeks to 10 weeks of age. Differences in leptin status at 5 weeks of age were assessed between the two mouse lines. Adipose tissue explant culture was also performed to evaluate leptin production capacity in vitro.

RESULTS

ON-DP mice showed spontaneous overfeeding compared with ON-DR mice. Excessive body weight gain and fat accumulation in ON-DP mice were completely suppressed to the levels seen in ON-DR mice by pair-feeding with ON-DR mice. Deterioration of glucose tolerance in ON-DP mice was also ameliorated under the pair-feeding conditions. While no differences were seen in body weight and adipose tissue mass when comparing the two mouse lines at 5 weeks of age, the ON-DP mice had lower plasma leptin concentrations and adipose tissue leptin gene expression levels. In accordance with peripheral leptin status, ON-DP mice displayed lower anorexigenic leptin signalling in the hypothalamic arcuate nucleus when compared with ON-DR mice without apparent leptin resistance. Explant culture studies revealed that ON-DP mice had lower leptin production capacity in adipose tissue. ON-DP mice also displayed higher DNA methylation levels in the leptin gene promoter region of adipocytes when compared with ON-DR mice.

CONCLUSIONS/INTERPRETATION

The results suggest that heritable lower leptin production capacity plays a critical role in overfeeding-induced obesity and subsequent deterioration of glucose tolerance in ON-DP mice. Leptin production capacity in adipocytes, especially before the development of obesity, may have diagnostic potential for predicting individual risk of obesity caused by overeating and future onset of type 2 diabetes. Graphical abstract.

DNA methylation and demethylation link the properties of mesenchymal stem cells: Regeneration and immunomodulation

Mesenchymal stem cells (MSCs) are a heterogeneous population that can be isolated from various tissues, including bone marrow, adipose tissue, umbilical cord blood, and craniofacial tissue. MSCs have attracted increasingly more attention over the years due to their regenerative capacity and function in immunomodulation. The foundation of tissue regeneration is the potential of cells to differentiate into multiple cell lineages and give rise to multiple tissue types. In addition,the immunoregulatory function of MSCs has provided insights into therapeutic treatments for immune-mediated diseases. DNA methylation and demethylation are important epigenetic mechanisms that have been shown to modulate embryonic stem cell maintenance, proliferation, differentiation and apoptosis by activating or suppressing a number of genes. In most studies, DNA hypermethylation is associated with gene suppression, while hypomethylation or demethylation is associated with gene activation. The dynamic balance of DNA methylation and demethylation is required for normal mammalian development and inhibits the onset of abnormal phenotypes. However, the exact role of DNA methylation and demethylation in MSC-based tissue regeneration and immunomodulation requires further investigation. In this review, we discuss how DNA methylation and demethylation function in multi-lineage cell differentiation and immunomodulation of MSCs based on previously published work. Furthermore, we discuss the implications of the role of DNA methylation and demethylation in MSCs for the treatment of metabolic or immune-related diseases.

Regulation of Adipocyte Differentiation by METTL4, a 6 mA Methylase

As one of the most abundant DNA methylation form in prokaryotes, N⁶-methyladenine nucleotide (6 mA) was however only recently identified in eukaryotic genomes. To explore the implications of N⁶-adenine methylation in adipogenesis, genomic N⁶-adenine methylation was examined across adipocyte differentiation stages of 3T3-L1 cells. When the N⁶-adenine methylation profiles were analyzed and compared with the levels of gene expression, a positive correlation between the density of promoter 6 mA and gene expression level was uncovered. By means of in vitro methylation and gene knockdown assay, METTL4, a homologue of Drosophila methylase CG14906 and C. elegans methylase DAMT-1, was demonstrated to be a mammalian N⁶-adenine methylase that functions in adipogenesis. Knockdown of Mettl4 led to altered adipocyte differentiation, shown by defective gene regulation and impaired lipid production. We also found that the effects of N⁶-adenine methylation on lipid production involved the regulation of INSR signaling pathway, which promotes glucose up-taking and lipid production in the terminal differentiation stage.

Placental expression of leptin: fetal sex-independent relation with human placental growth

OBJECTIVES

Leptin (LEP) is a vital placental hormone that is known to affect different aspects of placental function and fetal development. The present study aimed to determine the association of placental LEP transcript abundance with maternal, placental, and newborn parameters.

SUBJECTS/METHODS

In this retrospective case-control study, placental samples (n = 105) were collected from small (SGA) and appropriate (AGA) for gestational age full-term singleton pregnancies (n = 44 SGA and n = 61 AGA). Placental transcript abundance of LEP was assessed by real-time quantitative PCR after normalization to a reference gene panel. LEP methylation was measured using a quantitative MethyLight assay in a subset of samples (n = 54).

RESULTS

Placental LEP transcript abundance was negatively and significantly associated with placental weight (β = -3.883, P = 0.015). This association continued to be significant in the SGA group (β = -10.332, P = 0.001), both in female (β = -15.423, P = 0.021) and male births (β = -10.029, P = 0.007). LEP transcript abundance was not associated with LEP methylation levels (Spearman's ρ = 0.148, P = 0.287).

CONCLUSION

We conclude that placental upregulation of LEP is an integral and fetal sex-independent component of placental growth restriction, which can be potentially targeted through maternal dietary modifications to improve fetoplacental growth.

DNA methylation in promoter regions of genes involved in the reproductive and metabolic function of children born to women with PCOS

Clinical and experimental evidences indicate that epigenetic modifications induced by the prenatal environment are related to metabolic and reproductive derangements in polycystic ovary syndrome (PCOS). Alterations in the leptin and adiponectin systems, androgen signalling and antimüllerian hormone (AMH) levels have been observed in PCOS women and in their offspring. Using a targeted Next-Generation Sequencing (NGS), we studied DNA methylation in promoter regions of the leptin (LEP), leptin receptor (LEPR), adiponectin (ADIPOQ), adiponectin receptor 1 and 2 (ADIPOR1 and ADIPOR2), AMH and androgen receptor (AR) genes in 24 sons and daughters of women with PCOS (12 treated with metformin during pregnancy) and 24 children born to non-PCOS women during early infancy (2-3 months of age). Genomic DNA was extracted from whole blood, bisulphite converted and sequenced by NGS. Girls showed differences between groups in 1 CpG site of LEPR, 2 of LEP, 1 of ADIPOR2 and 2 of AR. Boys showed differences in 5 CpG sites of LEP, 3 of AMH and 9 of AR. Maternal metformin treatment prevented some of these changes in LEP, ADIPOR2 and partially in AR in girls, and in LEP and AMH in boys. Maternal BMI at early pregnancy was inversely correlated with the methylation levels of the ChrX-67544981 site in the whole group of girls (r = -0.530, p = 0.008) and with the global Z-score in all boys (r = -0.539, p = 0.007). These data indicate that the intrauterine PCOS environment predisposes the offspring to acquire certain sex-dependent DNA methylation patterns in the promoter regions of metabolic and reproductive genes.

Associations of maternal diet and placenta leptin methylation

BACKGROUND

Maternal diet is an important factor in prenatal development that also has implications for disease risk later in life. The adipokine leptin is a key regulator of energy homeostasis and may be involved in the association between maternal nutrition, maternal obesity, and infant outcomes. DNA methylation of placenta genes may occur in response to exposures and may program subsequent infant development. This study examined maternal diet, placenta leptin gene DNA methylation, and neonatal growth in a sample of healthy neonates and their mothers.

METHODS

Mothers and their healthy neonates (N = 135) were recruited within 1-2 days following delivery at Women and Infants Hospital in Providence, RI. A structured interview was conducted to assess maternal dietary intake. Maternal pre-pregnancy weight, weight gain during pregnancy, maternal health, medications, and vitamin use were obtained from medical records. Bisulfite pyrosequencing was used to measure methylation of CpG sites in the promoter region of the placenta leptin gene and determine genotype of the leptin single nucleotide polymorphism (SNP) rs2167270, which is known to influence leptin methylation. Bivariate analyses and linear regression models were used to evaluate associations of demographics, diet, and mean leptin methylation.

RESULTS

Genotype was a significant predictor of placenta leptin DNA methylation (p < .01), and after controlling for this and other relevant maternal and infant covariates, lower levels of leptin methylation were significantly associated with greater intake of carbohydrates (p < .05), in particular added sugars (p < .05) and white/refined carbohydrates (p < .05). Total caloric intake was also associated with placenta leptin methylation (p < .05), however after controlling for relevant covariates, significance diminished to trend-level. There were no significant associations of placenta leptin methylation and intake of protein (p > .05) or fat (p > .05).

CONCLUSION

These findings underline the importance of intake of carbohydrate consumption for methylation of the placenta leptin gene. Because methylation reduces gene transcription, lower methylation may indicate a placenta response to high caloric intake and carbohydrate food that would result in higher levels of this hormone during fetal development. Further investigation of the developmental ramifications of epigenetic changes to placenta leptin methylation should be pursued.

Effects of gut microbiota on leptin expression and body weight are lessened by high-fat diet in mice

Aberration in leptin expression is one of the most frequent features in the onset and progression of obesity, but the underlying mechanisms are still unclear and need to be clarified. This study investigated the effects of the absence of gut microbiota on body weight and the expression and promoter methylation of the leptin. Male C57 BL/6 J germ-free (GF) and conventional (CV) mice (aged 4-5 weeks) were fed either a normal-fat diet (NFD) or a high-fat diet (HFD) for 16 weeks. Six to eight mice from each group, at 15 weeks, were administered exogenous leptin for 7 d. Leptin expression and body weight gain in GF mice were increased by NFD with more CpG sites hypermethylated at the leptin promoter, whereas there was no change with HFD, compared with CV mice. Adipose or hepatic expression of genes associated with fat synthesis (Acc1, Fas and Srebp-1c), hydrolysis and oxidation (Atgl, Cpt1a, Cpt1c, Ppar-α and Pgc-1α) was lower, and hypothalamus expression of Pomc and Socs3 was higher in GF mice than levels in CV mice, particularly with NFD feeding. Exogenous leptin reduced body weight in both types of mice, with a greater effect on CV mice with NFD. Adipose Lep-R expression was up-regulated, and hepatic Fas and hypothalamic Socs3 were down-regulated in both types of mice. Expression of fat hydrolysis and oxidative genes (Atgl, Hsl, Cpt1a, Cpt1c, Ppar-α and Pgc-1α) was up-regulated in CV mice. Therefore, the effects of gut microbiota on the leptin expression and body weight were affected by dietary fat intake.

Methylation of the LEP gene promoter in blood at 12 months and BMI at 4 years of age-a population-based cohort study

Increasing evidence links epigenetic variation to anthropometric and metabolic measures. Leptin signalling regulates appetite and energy expenditure, and in pregnancy is important for nutrient supply to the foetus. Maternal metabolic health and foetal growth are linked to infant blood leptin gene (LEP) methylation, which has been cross-sectionally associated with adolescent obesity. Despite this, few studies have explored the relationship between infant LEP methylation and childhood anthropometry, or the impact of genetic variation on these relationships. Using a prospective birth cohort, we investigated whether blood LEP promoter methylation at birth and 12 months predicts weight and adiposity at 4-years. Locus-specific methylation data was analysed by partial correlation tests and multivariable linear regression. There was weak evidence of an association of birth LEP methylation with anthropometry measures at 4 years. Methylation at a specific site (cg19594666) at 12 months was inversely associated with 4-year weight (r = -0.11, p = 0.02) and body-mass index (BMI) (r = -0.13, p = 0.007), which persisted following adjustment for weight at birth and at 12 months. Neither association was influenced by genotype. We report the first evidence of an association between LEP methylation in infancy and childhood weight. Replication in additional cohorts is required to determine if this relationship persists.

Genetic variation, intrauterine growth, and adverse pregnancy conditions predict leptin gene DNA methylation in blood at birth and 12 months of age

BACKGROUND

Leptin regulates satiety and energy homoeostasis, and plays a key role in placentation in pregnancy. Previous studies have demonstrated regulation of leptin gene (LEP) expression and/or methylation in placenta and cord blood in association with early life exposures, but most have been small and have not considered the influence of genetic variation. Here, we investigated the relationship between maternal factors in pregnancy, infant anthropometry and LEP genetic variation with LEP promoter methylation at birth and 12 months of age.

METHODS

LEP methylation was measured in cord (n = 877) and 12-month (n = 734) blood in the Barwon Infant Study, a population-based pre-birth cohort. Infant adiposity at birth and 12-months was measured as triceps and subscapular skinfold thickness. Cross-sectional regression tested associations of methylation with pregnancy and anthropometry measures, while longitudinal regression tested if birth anthropometry predicted 12-month LEP methylation levels.

RESULTS

Male infants had lower LEP methylation in cord blood (-2.07% average methylation, 95% CI (-2.92, -1.22), p < 0.001). Genetic variation strongly influenced DNA methylation at a single CpG site, which was also negatively associated with birth weight (r = -0.10, p = 0.003). Pre-eclampsia was associated with lower cord blood methylation at another CpG site (-6.06%, 95% CI (-10.70, -1.42), p = 0.01). Gestational diabetes was more modestly associated with methylation at two other CpG units. Adiposity at birth was associated with 12-month LEP methylation, modified by rs41457646 genotype. There was no association of LEP methylation with 12-month anthropometric measures.

CONCLUSIONS

Infant sex, weight, genetic variation, and exposure to pre-eclampsia and gestational diabetes, are associated with LEP methylation in cord blood. Infant adiposity at birth predicts 12-month blood LEP methylation in a genotype-dependent manner. These findings are consistent with genetics and anthropometry driving altered LEP epigenetic profile and expression in infancy. Further work is required to confirm this and to determine the long-term impact of altered LEP methylation on health.

Insights into the Role of DNA Methylation and Protein Misfolding in Diabetes Mellitus

Background:

Diabetes mellitus is a metabolic disorder that is characterized by impaired glucose tolerance resulting from defects in insulin secretion, insulin action, or both. Epigenetic modifications, which are defined as inherited changes in gene expression that occur without changes in gene sequence, are involved in the etiology of diabetes.

Methods:

In this review, we focused on the role of DNA methylation and protein misfolding and their contribution to the development of both type 1 and type 2 diabetes mellitus.

Results:

Changes in DNA methylation in particular are highly associated with the development of diabetes. Protein function is dependent on their proper folding in the endoplasmic reticulum. Defective protein folding and consequently their functions have also been reported to play a role. Early treatment of diabetes has proven to be of great benefit, as even transient hyperglycemia may lead to pathological effects and complications later on. This has been explained by the theory of the development of a metabolic memory in diabetes. The basis for this metabolic memory was attributed to oxidative stress, chronic inflammation, non-enzymatic glycation of proteins and importantly, epigenetic changes. This highlights the importance of linking new therapeutics targeting epigenetic mechanisms with traditional antidiabetic drugs.

Conclusion:

Although new data is evolving on the relation between DNA methylation, protein misfolding, and the etiology of diabetes, more studies are required for developing new relevant diagnostics and therapeutics.

Differential placental DNA methylation of VEGFA and LEP in small-for-gestational age fetuses with an abnormal cerebroplacental ratio

Background

In Fetal Growth Restriction ‘fetal programming’ may take place via DNA methylation, which has implications for short-term and long-term health outcomes. Small-for-gestational age fetuses are considered fetal growth restricted, characterized by brain-sparing when fetal Doppler hemodynamics are abnormal, expressed as a cerebroplacental ratio (CPR) <1. We aimed to determine whether brain-sparing is associated with altered DNA methylation of selected genes.

Methods

We compared DNA methylation of six genes in 41 small-for-gestational age placentas with a normal or abnormal CPR. We selected EPO, HIF1A, VEGFA, LEP, PHLDA2, and DHCR24 for their role in angiogenesis, immunomodulation, and placental and fetal growth. DNA methylation was analyzed by pyrosequencing.

Results

Growth restricted fetuses with an abnormal CPR showed hypermethylation of the VEGFA gene at one CpG (VEGFA-309, p = .001) and an overall hypomethylation of the LEP gene, being significant at two CpGs (LEP-123, p = .049; LEP-51, p = .020). No differences in methylation were observed for the other genes.

Conclusions

VEGFA and LEP genes are differentially methylated in placentas of small-for-gestational age fetuses with brain-sparing. Hypermethylation of VEGFA-309 in abnormal CPR-placentas could indicate successful compensatory mechanisms. Methylation of LEP-51 is known to suppress LEP expression. Hypomethylation in small-for-gestational age placentas with abnormal CPR may result in hyperleptinemia and predispose to leptin-resistance later in life.

Molecular Insight into the Interaction between Epigenetics and Leptin in Metabolic Disorders

Nowadays, it is well-known that the deregulation of epigenetic machinery is a common biological event leading to the development and progression of metabolic disorders. Moreover, the expression level and actions of leptin, a vast adipocytokine regulating energy metabolism, appear to be strongly associated with epigenetics. Therefore, the aim of this review was to summarize the current knowledge of the epigenetic regulation of leptin as well as the leptin-induced epigenetic modifications in metabolic disorders and associated phenomena. The collected data indicated that the deregulation of leptin expression and secretion that occurs during the course of metabolic diseases is underlain by a variation in the level of promoter methylation, the occurrence of histone modifications, along with miRNA interference. Furthermore, leptin was proven to epigenetically regulate several miRNAs and affect the activity of the histone deacetylases. These epigenetic modifications were observed in obesity, gestational diabetes, metabolic syndrome and concerned various molecular processes like glucose metabolism, insulin sensitivity, liver fibrosis, obesity-related carcinogenesis, adipogenesis or fetal/early postnatal programming. Moreover, the circulating miRNA profiles were associated with the plasma leptin level in metabolic syndrome, and miRNAs were found to be involved in hypothalamic leptin sensitivity. In summary, the evidence suggests that leptin is both a target and a mediator of epigenetic changes that develop in numerous tissues during metabolic disorders.

The Influence of the Duration of Breastfeeding on the Infant's Metabolic Epigenome

Nutrition in the postnatal period is associated with metabolic programming. One of the presumed underlying mechanisms involves epigenetic modifications (e.g., DNA methylation). Breastfeeding has an unknown impact on DNA methylation at a young age. Within the Maternal Nutrition and Offspring's Epigenome (MANOE) study, we assessed the effect of breastfeeding duration on infant growth and buccal methylation in obesity-related genes (n = 101). A significant difference was found between infant growth and buccal RXRA and LEP methylation at 12 months of breastfeeding. For RXRA CpG2 methylation, a positive association was found with duration of breastfeeding (slope = 0.217; 95% confidence interval (CI) 1.03, 0.330; p < 0.001). For RXRA CpG3 and CpG, mean methylation levels were significantly lower when children were breastfed for 4-6 months compared to non-breastfed children (only CpG3), and those breastfed for 7-9 months, 10-12 months, or 1-3 months. On the other hand, higher LEP CpG3 methylation was observed when mothers breastfed 7-9 months (6.1%) as compared to breastfeeding for 1-3 months (4.3%; p = 0.007) and 10-12 months (4.6%; p = 0.04). In addition, we observed that infant weight was significantly lower when children were breastfed for 10-12 months. Breastfeeding duration was associated with epigenetic variations in RXRA and LEP at 12 months and with infant biometry/growth. Our results support the hypothesis that breastfeeding could induce epigenetic changes in infants.

Functional Implications of DNA Methylation in Adipose Biology

The twin epidemics of obesity and type 2 diabetes (T2D) are a serious health, social, and economic issue. The dysregulation of adipose tissue biology is central to the development of these two metabolic disorders, as adipose tissue plays a pivotal role in regulating whole-body metabolism and energy homeostasis (1). Accumulating evidence indicates that multiple aspects of adipose biology are regulated, in part, by epigenetic mechanisms. The precise and comprehensive understanding of the epigenetic control of adipose tissue biology is crucial to identifying novel therapeutic interventions that target epigenetic issues. Here, we review the recent findings on DNA methylation events and machinery in regulating the developmental processes and metabolic function of adipocytes. We highlight the following points: 1) DNA methylation is a key epigenetic regulator of adipose development and gene regulation, 2) emerging evidence suggests that DNA methylation is involved in the transgenerational passage of obesity and other metabolic disorders, 3) DNA methylation is involved in regulating the altered transcriptional landscape of dysfunctional adipose tissue, 4) genome-wide studies reveal specific DNA methylation events that associate with obesity and T2D, and 5) the enzymatic effectors of DNA methylation have physiological functions in adipose development and metabolic function.

Effects of Cyclocarya paliurus polysaccharide on lipid metabolism-related genes DNA methylation in rats

The present study was conducted to evaluate the effect of CPP on the DNA methylation and expressions of lipid metabolism-related genes (leptin and MTTP) in hyperlipidemic rats. After 8 weeks intervention of CPP, the abdominal wall fat index, liver weight, the serum concentrations of TC, TG and LDL-C were significantly decreased, while HDL was increased. In addition, DNA methylation was analyzed by bisulfite sequencing method, and the mRNA expression levels of leptin and MTTP were detected by Q-PCR. The results showed that CPP could considerably decrease DNA methylation levels of leptin (regions from -694 ~ -370 bp contains 14 CpGs and -324 ~ -29 bp contains 18 CpGs) and MTTP (region from -350 ~ -1 bp contains 11 CpGs) promoters in the liver with the maximum decrease rate of 43.2%, 40.2% and 7.7%, respectively. In parallel, the mRNA contents of leptin and MTTP were dramatically down-regulated. In conclusion, the present findings demonstrated that CPP can regulate the level of mRNA by controlling DNA methylation levels in the liver, thereby reducing blood lipids.

Maternal obesity influences expression and DNA methylation of the adiponectin and leptin systems in human third-trimester placenta

BACKGROUND

It is well established that obesity is associated with dysregulation of the ratio between the two major adipokines leptin and adiponectin. Furthermore, it was recently reported that maternal obesity has a significant impact on placental development. Leptin and adiponectin are present at the fetal-maternal interface and are involved in the development of a functional placenta. However, less is known about leptin and adiponectin's involvement in the placental alterations described in obese women. Hence, the objective of the present study was to characterize the placental expression and DNA methylation of these two adipokine systems (ligands and receptors) in obese women.

RESULTS

Biopsies were collected from the fetal and maternal sides of third-trimester placenta in obese and non-obese (control) women. In both groups, leptin levels were higher on the fetal side than the maternal side, suggesting that this cytokine has a pivotal role in fetal growth. Secondly, maternal obesity (in the absence of gestational diabetes) was associated with (i) elevated DNA methylation of the leptin promoter on fetal side only, (ii) hypomethylation of the adiponectin promoter on the maternal side only, (iii) significantly low levels of leptin receptor protein (albeit in the absence of differences in mRNA levels and promoter DNA methylation), (iv) significantly low levels of adiponectin receptor 1 mRNA expression on the maternal side only, and (v) elevated DNA methylation of the adiponectin receptor 2 promoter on the maternal side only.

CONCLUSION

Our present results showed that maternal obesity is associated with the downregulation of both leptin/adiponectin systems in term placenta, and thus a loss of the beneficial effects of these two adipokines on placental development. Maternal obesity was also associated with epigenetic changes in leptin and adiponectin systems; this highlighted the molecular mechanisms involved in the placenta's adaptation to a harmful maternal environment.

Smoking-induced changes in leptin serum levels and c/EBPalpha-related methylation status of the leptin core promotor during smoking cessation

Previous studies have provided evidence of an association between serum leptin levels and smoking as well as craving during smoking cessation. As promoter methylation also regulates leptin expression, we investigated the leptin gene promoter region of smokers before and after smoking cessation. Since leptin's core promoter region contains an essential c/EBPalpha transcription binding site, we narrowed our investigation to C-300 (-300 base pairs from the transcription start site) of that binding site. Female smokers showed hypermethylation of C-300 compared to non-smokers. Global methylation status is associated with higher craving and the degree of dependence in female smokers. Serum leptin levels in female smokers were significantly higher than in non-smokers. These findings support previous results and, for the first time, point to a pathophysiological role of c/EBPalpha-related C-300 methylation in tobacco dependence.

Plausible relationship between homocysteine and obesity risk via MTHFR gene: a meta-analysis of 38,317 individuals implementing Mendelian randomization

OBJECTIVE

Numerous studies have explored the role of methylenetetrahydrofolate reductase gene (MTHFR) C677T polymorphism and homocysteine (Hcy) concentration in obesity, but the results are inconsistent. Hence, we performed a meta-analysis implementing Mendelian randomization approach to test the assumption that the increased Hcy concentration is plausibly related to the elevated risk of obesity.

METHODS

Eligible studies were selected based on several inclusion and exclusion criteria. Correlations between MTHFR C677T and obesity risk, MTHFR C677T and Hcy concentration in obesity, Hcy concentration, and obesity were estimated by ORs, effect size and standard mean difference with their corresponding 95% CIs, respectively. Furthermore, Mendelian randomization analysis was performed to estimate the relationship between Hcy level and obesity.

RESULTS

Consequently, this meta-analysis implemented with Mendelian randomization approach was conducted among 8,622 cases and 29,695 controls. The results indicated that MTHFR C677T is associated with an increased risk of obesity (for T vs C: OR=1.06, 95% CI=1.02-1.10; for TT vs CC: OR=1.13, 95% CI=1.03-1.24). Moreover, in obese subjects, the pooled Hcy concentration in individuals of TT genotype was 2.91 mmol/L (95% CI: 0.27-5.55) higher than that in individuals of CC genotype. Furthermore, the pooled Hcy concentration in subjects with obesity was 0.74 mmol/L (95% CI: 0.36-1.12) higher than that in controls. The evaluated plausible OR associated with obesity was 1.23 for 5 μmol/L Hcy level increase.

CONCLUSIONS

Through this meta-analysis, we emphasize a strong relationship between Hcy level and obesity by virtue of MTHFR C677T polymorphism.

Association of Leptin Gene DNA Methylation With Diagnosis and Treatment Outcome of Anorexia Nervosa

Epigenetic alterations are increasingly implicated in the pathophysiology of anorexia nervosa (AN) but are as yet poorly understood. We investigated possible associations between the leptin gene (LEP) and the leptin receptor gene (LEPR) DNA promoter methylation and (1) a diagnosis of AN and (2) outcome after a 10 months psychotherapeutic outpatient treatment. 129 (LEPR: n = 135) patients with AN were investigated during the large scale psychotherapeutic Anorexia Nervosa Treatment Outpatient Study (ANTOP) trial, compared to 117 (LEPR: n = 119) age and height matched, normal-weight healthy controls. Blood samples were taken at baseline, the end of therapy (40 weeks) and the 12-months follow-up and compared to controls. Methylation was measured in whole blood via bisulfite sequencing. Within the promoter region 32 (LEP) and 39 CpG sites (LEPR) were analyzed. Two key findings were observed. First, LEP and LEPR methylation at baseline were lower in patients compared to controls (LEP: [%] AN: 30.94 ± 13.2 vs. controls: 34.53 ± 14.6); LEPR ([%] AN: 3.73 ± 5.4 vs. controls: 5.22 ± 8.3, mixed linear models: both P < 0.001). Second, lower DNA methylation of the LEP promoter, with a dynamic upregulation during treatment, was associated with a full recovery in AN patients (% change from baseline to follow-up in full recovery patients: +35.13% (SD: 47.56); mixed linear model: P < 0.0001). To test for potential predictive properties of mean LEP DNA methylation a LEP DNA methylation cut-off (31.25% DNA methylation) was calculated, which significantly discriminated full recovery vs. full syndrome AN patients. This cut-off was then tested in a group of previously unclassified patients (missing follow-up data of the Structured Interview for Anorexic and Bulimic disorders; n = 33). Patients below the cut-off (31.25% LEP DNA methylation) showed an increase in BMI over time, while those above the cut-off had a decrease in BMI (ANOVA at the 12-months follow-up: P = 0.0142). To our knowledge, this is the first study investigating epigenetic alterations in AN over time. Our findings indicate that LEP DNA methylation might be involved in the disease course of AN.

Maternal corticotropin-releasing hormone is associated with LEP DNA methylation at birth and in childhood: an epigenome-wide study in Project Viva

Background:

Corticotropin-releasing hormone (CRH) plays a central role in regulating the secretion of cortisol which controls a wide range of biological processes. Fetuses overexposed to cortisol have increased risks of disease in later life. DNA methylation may be the underlying association between prenatal cortisol exposure and health effects. We investigated associations between maternal CRH levels and epigenome-wide DNA methylation of cord blood in offsprings and evaluated whether these associations persisted into mid-childhood.

Methods:

We investigated mother-child pairs enrolled in the prospective Project Viva pre-birth cohort. We measured DNA methylation in 257 umbilical cord blood samples using the HumanMethylation450 Bead Chip. We tested associations of maternal CRH concentration with cord blood cells DNA methylation, adjusting the model for maternal age at enrollment, education, maternal race/ethnicity, pre-pregnancy body mass index, parity, gestational age at delivery, child sex, and cell-type composition in cord blood. We further examined the persistence of associations between maternal CRH levels and DNA methylation in children’s blood cells collected at mid-childhood (N = 239, age: 6.7–10.3 years) additionally adjusting for the children’s age at blood drawn.

Results:

Maternal CRH levels are associated with DNA methylation variability in cord blood cells at 96 individual CpG sites (False Discovery Rate < 0.05). Among the 96 CpG sites, we identified 3 CpGs located near the LEP gene. Regional analyses confirmed the association between maternal CRH and DNA methylation near LEP. Moreover, higher maternal CRH levels were associated with higher blood-cell DNA methylation of the promoter region of LEP in mid-childhood (P < 0.05, β = 0.64, SE = 0.30).

Conclusion:

In our cohort, maternal CRH was associated with DNA methylation levels in newborns at multiple loci, notably in the LEP gene promoter. The association between maternal CRH and LEP DNA methylation levels persisted into mid-childhood.

Gene-gene interactions and associations of six hypertension related single nucleotide polymorphisms with obesity risk in a Chinese children population

Obesity is a major risk for hypertension. However, the associations between hypertension susceptibility loci and the risk of obesity as well as the effects of gene-gene interactions are unclear, especially in the Chinese children population. Six single nucleotide polymorphisms (SNPs) (ATP2B1 rs17249754, CSK rs1378942, MTHFR rs1801133, CYP17A1 rs1004467, STK39 rs3754777, FGF5 rs16998073) were genotyped for 3503 Chinese children, aged 6-18 years. Of them, 758 obese cases and 2745 controls were identified based on the International Obesity Task Force age- and sex-specific BMI references. Among the six SNPs, three were associated with obesity risk (CSK rs1378942: odds ratio (OR) = 1.20, 95% confidence interval (CI) 1.01-1.43, P = 0.042; MTHFR rs1801133: OR = 1.19, 95% CI 1.05-1.34, P = 0.006; FGF5 rs16998073: OR = 1.14, 95% CI 1.00-1.29, P = 0.047). The genetic risk score (GRS), based on these three SNPs (CSK rs1378942, MTHFR rs1801133, FGF5 rs16998073), showed a positive association with risk of obesity (OR = 1.18, 95% CI 1.09-1.28, P = 7.60 × 10^-5). The same association signals were also detected in the subgroups of puberty and inactivity. In addition, interaction analyses among these loci implied a potential gene-gene interaction between MTHFR and FGF5. These findings show a significant association of hypertension susceptibility loci in Chinese children, suggesting a likely influence of genetic and environmental factors on the risk of obesity.

Maternal obesity programs increased leptin gene expression in rat male offspring via epigenetic modifications in a depot-specific manner

Objective

According to the Developmental Origin of Health and Disease (DOHaD) concept, maternal obesity and accelerated growth in neonates predispose offspring to white adipose tissue (WAT) accumulation. In rodents, adipogenesis mainly develops during lactation. The mechanisms underlying the phenomenon known as developmental programming remain elusive. We previously reported that adult rat offspring from high-fat diet-fed dams (called HF) exhibited hypertrophic adipocyte, hyperleptinemia and increased leptin mRNA levels in a depot-specific manner. We hypothesized that leptin upregulation occurs via epigenetic malprogramming, which takes place early during development of WAT.

Methods

As a first step, we identified in silico two potential enhancers located upstream and downstream of the leptin transcription start site that exhibit strong dynamic epigenomic remodeling during adipocyte differentiation. We then focused on epigenetic modifications (methylation, hydroxymethylation, and histone modifications) of the promoter and the two potential enhancers regulating leptin gene expression in perirenal (pWAT) and inguinal (iWAT) fat pads of HF offspring during lactation (postnatal days 12 (PND12) and 21 (PND21)) and in adulthood.

Results

PND12 is an active period for epigenomic remodeling in both deposits especially in the upstream enhancer, consistent with leptin gene induction during adipogenesis. Unlike iWAT, some of these epigenetic marks were still observable in pWAT of weaned HF offspring. Retained marks were only visible in pWAT of 9-month-old HF rats that showed a persistent “expandable” phenotype.

Conclusions

Consistent with the DOHaD hypothesis, persistent epigenetic remodeling occurs at regulatory regions especially within intergenic sequences, linked to higher leptin gene expression in adult HF offspring in a depot-specific manner.

•

The white adipose tissue is an important target of developmental programming.

•

Higher leptin gene expression occurs in offspring from obese dams in a depot-specific manner.

•

Leptin upregulation occurs via epigenetic malprogramming during development of adipose tissue.

•

Persistent genomic epigenetic remodeling occurs in adipose tissue of offspring from obese dams.

•

Intergenic regions were more affected than the leptin promoter region in offspring of obese dams.

MECHANISMS IN ENDOCRINOLOGY: Epigenetic modifications and gestational diabetes: a systematic review of published literature

OBJECTIVE

To summarize the current knowledge on epigenetic alterations in mother and offspring subjected to gestational diabetes (GDM) and indicate future topics for research.

DESIGN

Systematic review.

METHODS

We performed extensive searches in PubMed, EMBASE and Google scholar, using a combination of the search terms: GDM, gestational diabetes, epigenetic(s), methylation, histone modification, histone methylation, histone acetylation, microRNA and miRNA. Studies that compared women diagnosed with GDM and healthy controls were included. Two authors independently scanned the abstracts, and all included papers were read by at least two authors. The searches were completed on October 31st, 2016.

RESULTS

We identified 236 articles, of which 43 were considered relevant for this systematic review. Studies published showed that epigenetic alterations could be found in both mothers with GDM and their offspring. However, differences in methodology, diagnostic criteria for GDM and populations studied, together with a limited number of published studies and small sample sizes, preclude clear conclusions about the role of epigenetic modifications in transmitting risk from GDM mothers to their offspring.

CONCLUSION

The current research literature suggests that GDM may have impact on epigenetic modifications in the mother and offspring. However, larger studies that include multiple cohorts of GDM patients and their offspring are needed.

36 h fasting of young men influences adipose tissue DNA methylation of LEP and ADIPOQ in a birth weight-dependent manner

Background

Subjects born with low birth weight (LBW) display a more energy-conserving response to fasting compared with normal birth weight (NBW) subjects. However, the molecular mechanisms explaining these metabolic differences remain unknown. Environmental influences may dynamically affect epigenetic marks, also in postnatal life. Here, we aimed to study the effects of short-term fasting on leptin (LEP) and adiponectin (ADIPOQ) DNA methylation and gene expression in subcutaneous adipose tissue (SAT) from subjects with LBW and NBW.

Methods

Twenty-one young LBW men and 18 matched NBW controls were studied during 36 h fasting. Eight subjects from each group completed a control study (overnight fast). We analyzed SAT LEP and ADIPOQ methylation (Epityper MassARRAY), gene expression (q-PCR), and adipokine plasma levels.

Results

After overnight fast (control study), LEP and ADIPOQ DNA methylation levels were higher in LBW compared to those in NBW subjects (p ≤ 0.03) and increased with 36 h fasting in NBW subjects only (p ≤ 0.06). Both LEP and ADIPOQ methylation levels were positively associated with total body fat percentage (p ≤ 0.05). Plasma leptin levels were higher in LBW versus NBW subjects after overnight fasting (p = 0.04) and decreased more than threefold in both groups after 36 h fasting (p ≤ 0.0001).

Conclusions

This is the first study to demonstrate that fasting induces changes in DNA methylation. This was shown in LEP and ADIPOQ promoters in SAT among NBW but not LBW subjects. The altered epigenetic flexibility in LBW subjects might contribute to their differential response to fasting, adipokine levels, and increased risk of metabolic disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-017-0340-8) contains supplementary material, which is available to authorized users.

Differential adipokine DNA methylation and gene expression in subcutaneous adipose tissue from adult offspring of women with diabetes in pregnancy

BACKGROUND

Offspring of women with diabetes in pregnancy are at increased risk of type 2 diabetes mellitus (T2DM), potentially mediated by epigenetic mechanisms. The adipokines leptin, adiponectin, and resistin (genes: LEP, ADIPOQ, RETN) play key roles in the pathophysiology of T2DM. We hypothesized that offspring exposed to maternal diabetes exhibit alterations in epigenetic regulation of subcutaneous adipose tissue (SAT) adipokine transcription. We studied adipokine plasma levels, SAT gene expression, and DNA methylation of LEP, ADIPOQ, and RETN in adult offspring of women with gestational diabetes (O-GDM, N = 82) or type 1 diabetes (O-T1DM, N = 67) in pregnancy, compared to offspring of women from the background population (O-BP, N = 57).

RESULTS

Compared to O-BP, we found elevated plasma leptin and resistin levels in O-T1DM, decreased gene expression of all adipokines in O-GDM, decreased RETN expression in O-T1DM, and increased LEP and ADIPOQ methylation in O-GDM. In multivariate regression analysis, O-GDM remained associated with increased ADIPOQ methylation and decreased ADIPOQ and RETN gene expression and O-T1DM remained associated with decreased RETN expression after adjustment for potential confounders and mediators.

CONCLUSIONS

In conclusion, offspring of women with diabetes in pregnancy exhibit increased ADIPOQ DNA methylation and decreased ADIPOQ and RETN gene expression in SAT. However, altered methylation and expression levels were not reflected in plasma protein levels, and the functional implications of these findings remain uncertain.

Dynamic changes of epigenetic signatures during chondrogenic and adipogenic differentiation of mesenchymal stem cells

Extensive studies have been performed to clarify the processes during which mesenchymal stem cells (MSCs) differentiate into their lineage fates. In vitro differentiation of MSCs into distinct lineages have attracted the focus of a large number of clinical investigations. Although the gene expression profiling during differentiation of MSC toward bone, cartilage, and adipocytes is well established, the master regulators by which MSC fate can be controlled are not entirely determined. During differentiation of MSCs into a special cell fate, epigenetic mechanisms considered as the primary mediators that suppress the irrelevant genes and activate the genes required for a specific cell lineage. This review dedicated to addressing the changes of various epigenetic mechanisms, including DNA methylation, histone modifications, and micro-RNAs during chondrogenic and adipogenic differentiation of MSC.

Lower Placental Leptin Promoter Methylation in Association with Fine Particulate Matter Air Pollution during Pregnancy and Placental Nitrosative Stress at Birth in the ENVIRONAGE Cohort

BACKGROUND

Particulate matter with a diameter ≤ 2.5 μm (PM2.5) affects human fetal development during pregnancy. Oxidative stress is a putative mechanism by which PM2.5 may exert its effects. Leptin (LEP) is an energy-regulating hormone involved in fetal growth and development.

OBJECTIVES

We investigated in placental tissue whether DNA methylation of the LEP promoter is associated with PM2.5 and whether the oxidative/nitrosative stress biomarker 3-nitrotyrosine (3-NTp) is involved.

METHODS

LEP DNA methylation status of 361 placentas from the ENVIRONAGE birth cohort was assessed using bisulfite-PCR-pyrosequencing. Placental 3-NTp (n = 313) was determined with an ELISA assay. Daily PM2.5 exposure levels were estimated for each mother's residence, accounting for residential mobility during pregnancy, using a spatiotemporal interpolation model.

RESULTS

After adjustment for a priori chosen covariates, placental LEP methylation was 1.4% lower (95% CI: -2.7, -0.19%) in association with an interquartile range increment (7.5 μg/m3) in second-trimester PM2.5 exposure and 0.43% lower (95% CI: -0.85, -0.02%) in association with a doubling of placental 3-NTp content.

CONCLUSIONS

LEP methylation status in the placenta was negatively associated with PM2.5 exposure during the second trimester, and with placental 3-NTp, a marker of oxidative/nitrosative stress. Additional research is needed to confirm our findings and to assess whether oxidative/nitrosative stress might contribute to associations between PM2.5 and placental epigenetic events. Potential consequences for health during the neonatal period and later in life warrant further exploration. Citation: Saenen ND, Vrijens K, Janssen BG, Roels HA, Neven KY, Vanden Berghe W, Gyselaers W, Vanpoucke C, Lefebvre W, De Boever P, Nawrot TS. 2017. Lower placental leptin promoter methylation in association with fine particulate matter air pollution during pregnancy and placental nitrosative stress at birth in the ENVIRONAGE cohort. Environ Health Perspect 125:262-268; http://dx.doi.org/10.1289/EHP38.

Epigenetic Regulation of the Thermogenic Adipose Program

In contrast to white adipose tissue (WAT), which stores energy in the form of triglycerides, brown adipose tissue (BAT) dissipates energy by producing heat to maintain body temperature by burning glucose and fatty acids in a process called adaptive thermogenesis. The presence of an inducible thermogenic adipose tissue, and its beneficial effects for maintaining body weight and glucose and lipid homeostasis, has raised intense interest in understanding the regulation of thermogenesis. Elucidating the regulatory mechanisms underlying the thermogenic adipose program may provide excellent targets for therapeutics against obesity and diabetes. Here we review recent research on the role of epigenetics in the thermogenic gene program, focusing on DNA methylation and histone modifications.

Gender Differences in Adipocyte Metabolism and Liver Cancer Progression

Liver cancer is the third most common cancer type and the second leading cause of deaths in men. Large population studies have demonstrated remarkable gender disparities in the incidence and the cumulative risk of liver cancer. A number of emerging risk factors regarding metabolic alterations associated with obesity, diabetes and dyslipidemia have been ascribed to the progression of non-alcoholic fatty liver diseases (NAFLD) and ultimately liver cancer. The deregulation of fat metabolism derived from excessive insulin, glucose, and lipid promotes cancer-causing inflammatory signaling and oxidative stress, which eventually triggers the uncontrolled hepatocellular proliferation. This review presents the current standing on the gender differences in body fat compositions and their mechanistic linkage with the development of NAFLD-related liver cancer, with an emphasis on genetic, epigenetic and microRNA control. The potential roles of sex hormones in instructing adipocyte metabolic programs may help unravel the mechanisms underlying gender dimorphism in liver cancer and identify the metabolic targets for disease management.

Construction and Analysis of an Adipose Tissue-Specific and Methylation-Sensitive Promoter of Leptin Gene

DNA methylation plays a very important role in the regulation of gene expression. Under general situations, methylation in a gene promoter region is frequently accompanied by transcriptional suppression, and those genes that are highly methylated display the phenomenon of low expression. In contrast, those genes whose methylation level is low display the phenomenon of active expression. In this study, we conducted DNA methylation analysis on the CpG sites within the promoter regions of five adipose tissue-specific transcriptional factors-Adiponectin, Chemerin, Leptin, Smaf-1, and Vaspin-and examined their messenger RNA (mRNA) expression levels in different mouse tissues. We also performed analyses on the correlation between the DNA methylation levels of these genes and their mRNA expression levels in these tissues. The correlation coefficient for Leptin was the highest, and it displayed a high expression in an adipose tissue-specific manner. Thus, we cloned the regulatory region of Leptin gene and incorporated its promoter into the eukaryotic expression vector pEGFP-N1 and constructed a recombinant plasmid named pEGFP-N1-(p-Lep). This recombinant plasmid was first verified by DNA sequencing and then transfected into mouse pre-adipocytes via electroporation. Measurement of the activity of luciferase (reporter) indicated that p-Lep was capable of driving the expression of the reporter gene. This study has paved a solid basis for subsequent studies on generating transgenic animals.

Comprehensive DNA Methylation and Gene Expression Profiling in Differentiating Human Adipocytes

Insight into the processes controlling adipogenesis is important in the battle against the obesity epidemic and its related disorders. The transcriptional regulatory cascade involved in adipocyte differentiation has been extensively studied, however, the mechanisms driving the transcription activation are still poorly understood. In this study, we explored the involvement of DNA methylation in transcriptional regulation during adipocyte differentiation of primary human mesenchymal stem cells (hMSCs). Genome-wide changes in DNA methylation were measured using the Illumina 450K BeadChip. In addition, expression of 84 adipogenic genes was determined, of which 43 genes showed significant expression changes during the differentiation process. Among these 43 differentially expressed genes, differentially methylated regions (DMRs) were detected in only three genes. By comparing genome-wide DNA methylation profiles in undifferentiated and differentiated adipocytes 793 significant DMRs were detected. Pathway analysis revealed the adipogenesis pathway as the most statistically significant, although only a small number of genes were differentially methylated. Genome-wide DNA methylation changes for single probes were most often located in intergenic regions, and underrepresented close to the transcription start site. In conclusion, DNA methylation remained relatively stable during adipocyte differentiation, implying that changes in DNA methylation are not the underlying mechanism regulating gene expression during adipocyte differentiation. J. Cell. Biochem. 117: 2707-2718, 2016. © 2016 Wiley Periodicals, Inc.

Effects of Gestational Magnetic Resonance Imaging on Methylation Status of Leptin Promoter in the Placenta and Cord Blood

Over the past two decades, magnetic resonance imaging (MRI) has been widely used for diagnosis in gestational women. Though it has several advantages, animal and human studies on the safety of MRI for the fetus remain inconclusive. Epigenetic modifications, which are crucial for cellular functioning, are prone to being affected by environmental changes. Therefore, we hypothesized that MRI during gestation may cause epigenetic modification alterations. Here, we investigated DNA methylation patterns of leptin promoter in the placenta and cord blood of women exposed to MRI during gestation. Results showed that average methylation levels of leptin in the placenta and cord blood were not affected by MRI. We also found that the methylation levels in the placenta and cord blood were not affected by different magnetic fields (1.5T and 3.0T MRI). However, if pregnant women were exposed to MRI at 15 to 20 weeks of gestation, the methylation level of leptin in cord blood was visibly lower than that of pregnant women exposed to MRI after 20-weeks of gestation (P = 0.037). mRNA expression level of leptin in cord blood was also altered, though mRNA expression of leptin in the placenta was not significantly affected. Therefore, we concluded that gestational MRI may not have major effects on the methylation level of leptin in cord blood and the placenta except for MRI applied before 20 weeks of gestation.