CpG Methylation across the adipogenic PPARγ gene and its relationship with birthweight and child BMI at 9 years

Prenatal airborne polycyclic aromatic hydrocarbon exposure, altered regulation of peroxisome proliferator-activated receptor gamma (Ppar)γ, and links with mammary cancer

Environmental exposure to polycyclic aromatic hydrocarbons (PAH) has been shown to be associated with chronic disease outcomes through multiple mechanisms including altered regulation of the transcription factor peroxisome proliferator-activated receptor gamma (Ppar) γ. Because PAH exposure and Pparγ each have been associated with mammary cancer, we asked whether PAH would induce altered regulation of Pparγ in mammary tissue, and whether this association may underlie the association between PAH and mammary cancer. Pregnant mice were exposed to aerosolized PAH at proportions that mimic equivalent human exposures in New York City air. We hypothesized that prenatal PAH exposure would alter Pparγ DNA methylation and gene expression and induce the epithelial to mesenchymal transition (EMT) in mammary tissue of offspring (F1) and grandoffspring (F2) mice. We also hypothesized that altered regulation of Pparγ in mammary tissue would associate with biomarkers of EMT, and examined associations with whole body weight. We found that prenatal PAH exposure lowered Pparγ mammary tissue methylation among grandoffspring mice at postnatal day (PND) 28. However, PAH exposure did not associate with altered Pparγ gene expression or consistently with biomarkers of EMT. Finally, lower Pparγ methylation, but not gene expression, was associated with higher body weight among offspring and grandoffspring mice at PND28 and PND60. Findings suggest additional evidence of multi-generational adverse epigenetic effects of prenatal PAH exposure among grandoffspring mice.

Role of DNA methylation in diabetes and obesity

Due to the fact that the upward trend of several metabolic disorders such as diabetes and obesity, in individuals especially monozygotic twins, who are under the same effects from the environment, are not similar, the role of epigenetic elements like DNA methylation needs taking into account. In this chapter, emerging scientific evidence supporting the strong relationship between changes in DNA methylation and those diseases' development was summarized. Changing in the expression level of diabetes/obesity-related genes through being silenced by methylation can be the underlying mechanism of this phenomenon. Genes with abnormal methylation status are potential biomarkers for early prediction and diagnosis. Moreover, methylation-based molecular targets should be investigated as a new treatment for both T2D and obesity.

Decabromodiphenyl ether-induced PRKACA hypermethylation contributed to glycolipid metabolism disorder via regulating PKA/AMPK pathway in rat and L-02 cells

BDE-209 is the most prevalent congener of polybrominated diphenyl ethers and has high bioaccumulation in humans and animals. BDE-209 has been reported to disrupt glycolipid metabolism, but the mechanisms are still unclear. In this study, we found that BDE-209 induced liver tissue injury and hepatotoxicity, increased the glucose and total cholesterol levels in the serum of rats, and increased glucose and triglyceride levels in L-02 cells. BDE-209 exposure changed the PKA, p-PKA, AMPK, p-AMPK, ACC, and FAS expression in rats' liver and L-02 cells. Moreover, BDE-209 induced PRKACA-1 hypermethylation in L-02 cells. AMPK activator (AICAR) inhibited the changes of p-AMPK, ACC, and FAS expression and elevation of glucose and triglyceride levels induced by BDE-209. DNA methylation inhibitor (5-Aza-CdR) reversed BDE-209 induced alters of PKA/AMPK/ACC/FAS signaling pathway. These results demonstrated that BDE-209 could disrupt the glycolipid metabolism by causing PRKACA-1 hypermethylation to regulate the PKA/AMPK signaling pathway in hepatocytes.

Prenatal chlorpyrifos exposure in association with PPARγ H3K4me3 and DNA methylation levels and child development

BACKGROUND

Chlorpyrifos, one of the most widely used pesticides, can penetrate the placenta and affect fetal growth and neurodevelopment. Epigenetic regulation of peroxisome proliferator-activated receptor gamma (PPARγ), such as DNA methylation and trimethylation of lysine 4 of H3 (H3K4me3), may provide a potential mechanism for how fetal growth and development are impacted by chlorpyrifos exposure. The aims of the study were to investigate whether prenatal chlorpyrifos exposure was associated with H3K4me3 and DNA methylation levels of the PPARγ gene in the placenta and the related effects on birth outcomes and neurodevelopment.

METHODS

Among 425 mother-infant pairs from the Taiwan Birth Panel Study, chlorpyrifos levels were measured in cord blood by using online SPE-LC/HESI/MS/MS; placental PPARγ H3K4me3 and DNA methylation levels were measured by ChIP-qPCR and pyrosequencing, respectively; the neonates' health outcomes were extracted from the medical records; and childhood neurodevelopment was evaluated by using the Comprehensive Developmental Inventory for Infants and Toddlers in 2-year-old children. Multivariable regression models were used to adjust for potential confounders.

RESULTS

After controlling for potential confounders, each unit increase in the natural log-transformed prenatal chlorpyrifos exposure level was associated with an increase in the PPARγ DNA methylation level (adjusted β (aβ) = 0.77, p = 0.032) and poorer performance in the cognitive and language domains at 2 years old, especially in boys (aβ = -1.66, p = 0.016, and aβ = -1.79, p = 0.023, respectively). PPARγ H3K4me3 levels were positively associated with gestational age (aβ = 0.16, p = 0.011), birth weight (aβ = 30.52, p = 0.013), birth length (aβ = 0.18, p = 0.003 and aβ = 0.15, p = 0.042), and gross-motor performance (aβ = 1.67, p = 0.036).

CONCLUSIONS

Our findings suggested that prenatal chlorpyrifos exposure affected PPARγ DNA methylation levels and performance in the cognitive and language domains.

Potential role of aryl hydrocarbon receptor signaling in childhood obesity

BACKGROUND

There is a growing concern that junk food has contributed to the childhood obesity epidemic. Recently, experimental studies suggested that the aryl hydrocarbon receptor (AHR) gene is strongly linked to western diet-induced obesity.

AIM

This study investigated the potential role of AHR signaling in childhood obesity and the possible associations of the AHR-aryl hydrocarbon receptor repressor (AHRR)-cytochrome P450 1B1 (CYP1B1) axis with fatty acid homeostasis and the appetite-related hormones, leptin and ghrelin.

SUBJECTS AND METHODS

The study included 80 children; 54 obese and 26 non-obese of matched age and sex. Demographic data, anthropometric measurements, and lipid profile were assessed. Expression of AHR signaling genes was analyzed in blood cells by qRT-PCR. Serum insulin, leptin and ghrelin levels were measured using ELISA.

RESULTS

The statistical power of this study, calculated using G*Power version 3.1.9.2, was 90% (α = 0.05). AHR and CYP1B1 gene expression levels were upregulated in the obese group compared to controls, whereas AHRR, stearoyl-CoA desaturase 1 (SCD1), and peroxisome proliferator-activated receptor-γ₂ (PPARγ₂) were downregulated. Serum leptin correlated positively, while serum ghrelin correlated negatively with both AHR and CYP1B1. Stratification of obese children by age revealed more activated AHR signaling in younger than in older children. Receiver-operating-characteristic (ROC) analysis revealed that AHR, AHRR and CYP1B1 could discriminate between obese and normal weight children. Multivariate analysis showed that AHRR, CYP1B1 and ghrelin could be significant independent predictors of obesity.

CONCLUSION

This study provides new insights into the molecular mechanisms contributing to childhood obesity by revealing alterations in the AHR-AHRR-CYP1B1 axis, which could serve as a promising therapeutic target for childhood obesity.

Genome-wide association study identifies the PLAG1-OXR1 region on BTA14 for carcass meat yield in cattle

Carcass meat yield is an important carcass trait that contributes to the production efficiency and economic benefits in beef cattle. It is therefore critical to identify quantitative trait loci associated with carcass traits to enable selection. Our previous studies have identified several causal variants within the pleomorphic adenoma gene 1 ( PLAG1) and coiled-coil-helix-coiled-coil-helix domain-containing 7 ( CHCHD7) genes on BTA14 for carcass traits in Chinese Simmental. In the current study, we carried out a genome-wide association study for carcass meat yield in 472 Wagyu cattle with Bovine HD SNP array. Our results showed that 27 single nucleotide polymorphisms (SNPs) were identified for tenderloin weight (TDW), striploin weight (SPW), chuck roll weight (CRW), bicep weight (BPW), knuckle weight (KCW), and flank steak weight (FSW) in Wagyu cattle. Of these SNPs, 10 distinct SNPs were detected within the oxidation resistance 1 ( OXR1), fatty acid binding protein 5 ( FABP5), TNF receptor superfamily member 11b ( TNFRSF11B), and zinc finger CCCH-type containing 3 ( ZC3H3) genes on BTA14. Notably, three significant SNPs, BovineHD1400016738, BovineHD1400016743, and BovineHD1400016665 within OXR1, were shown strong linkage disequilibrium (r2 > 0.8) and significantly associated with CRW ( P = 1.37 × 10−8 ~ 1.94 × 10−8). Moreover, Ingenuity Pathway Analysis showed that OXR1, FABP5, and CAP1A genes were involved in a single network and FABP5 may regulate the expression of OXR1 gene via node gene, peroxisome proliferator-activated receptor gamma ( PPARG). Overall, this study suggests that OXR1 and FABP5 are candidate genes affecting carcass traits in Wagyu and the PLAG1-OXR1 region on BTA14 as a putative susceptibility locus for carcass meat yield for both Chinese Simmental and Wagyu.

DNA methylation markers in obesity, metabolic syndrome, and weight loss

The fact that not all individuals exposed to the same environmental risk factors develop obesity supports the hypothesis of the existence of underlying genetic and epigenetic elements. There is suggestive evidence that environmental stimuli, such as dietary pattern, particularly during pregnancy and early life, but also in adult life, can induce changes in DNA methylation predisposing to obesity and related comorbidities. In this context, the DNA methylation marks of each individual have emerged not only as a promising tool for the prediction, screening, diagnosis, and prognosis of obesity and metabolic syndrome features, but also for the improvement of weight loss therapies in the context of precision nutrition. The main objectives in this field are to understand the mechanisms involved in transgenerational epigenetic inheritance, and featuring the nutritional and lifestyle factors implicated in the epigenetic modifications. Likewise, DNA methylation modulation caused by diet and environment may be a target for newer therapeutic strategies concerning the prevention and treatment of metabolic diseases.

Thy1 (CD90) expression is regulated by DNA methylation during adipogenesis

The obesity epidemic is developing into the most costly health problem facing the world. Obesity, characterized by excessive adipogenesis and enlarged adipocytes, promotes morbidities, such as diabetes, cardiovascular disease, and cancer. Regulation of adipogenesis is critical to our understanding of how fat cell formation causes obesity and associated health problems. Thy1 (also called CD90), a widely used stem cell marker, blocks adipogenesis and reduces lipid accumulation. Thy1-knockout mice are prone to diet-induced obesity. Although the importance of Thy1 in adipogenesis and obesity is now evident, how its expression is regulated is not. We hypothesized that DNA methylation has a role in promoting adipogenesis and affects Thy1 expression. Using the methylation inhibitor 5-aza-2'-deoxycytidine (5-aza-dC), we investigated whether DNA methylation alters Thy1 expression during adipogenesis in both mouse 3T3-L1 preadipocytes and mouse mesenchymal stem cells. Thy1 protein and mRNA levels were decreased dramatically during adipogenesis. However, 5-aza-dC treatment prevented that phenomenon. Methylation-sensitive pyrosequencing analysis showed that CpG sites at the Thy1 locus have increased methylation during adipogenesis, as well as increased methylation in adipose tissue from diet-induced obese mice. These new findings highlight the potential role of Thy1 and DNA methylation in adipogenesis and obesity.-Flores, E. M., Woeller, C. F., Falsetta, M. L., Susiarjo, M., Phipps, R. P. Thy1 (CD90) expression is regulated by DNA methylation during adipogenesis.

Methyl-Donor and Cofactor Nutrient Intakes in the First 2-3 Years and Global DNA Methylation at Age 4: A Prospective Cohort Study

BACKGROUND

During the early postnatal period, the impact of nutrition on DNA methylation has not been well studied in humans. The aim was to quantify the relationship between one-carbon metabolism nutrient intake during the first three years of life and global DNA methylation levels at four years.

DESIGN

Childhood dietary intake was assessed using infant feeding questionnaires, food frequency questionnaires, 4-day weighed food records and 24-h food records. The dietary records were used to estimate the intake of methionine, folate, vitamins B2, B6 and B12 and choline. The accumulative nutrient intake specific rank from three months to three years of age was used for analysis. Global DNA methylation (%5-methyl cytosines (%5-mC)) was measured in buccal cells at four years of age, using an enzyme-linked immunosorbent assay (ELISA) commercial kit. Linear regression models were used to quantify the statistical relationships.

RESULTS

Data were collected from 73 children recruited from the Women and their Children's Health (WATCH) study. No association was found between one-carbon metabolism nutrient intake and global DNA methylation levels (P > 0.05). Global DNA methylation levels in males were significantly higher than in females (median %5-mC: 1.82 vs. 1.03, males and females respectively, (P < 0.05)).

CONCLUSION

No association was found between the intake of one-carbon metabolism nutrients during the early postnatal period and global DNA methylation levels at age four years. Higher global DNA methylation levels in males warrants further investigation.

Mechanistic Insights Into the Interaction Between Transcription Factors and Epigenetic Modifications and the Contribution to the Development of Obesity

Objective: The development of obesity is inseparable from genetic and epigenetic factors, and transcription factors (TFs) play an essential role in these two mechanisms. This review analyzes the interaction of TFs with epigenetic modifications and the epigenetic mechanisms underlying peroxisome proliferator-activated receptor (PPAR)γ, an important transcription factor, in the development of obesity. Methods: We describe the relationship between TFs and different epigenetic modifications and illustrate the several mechanisms described. Next, we summarize the epigenetic mechanisms of PPARs, an important class of transcription factors involved in obesity, that induce obesity with different triggering factors. Finally, we discuss the mechanisms of epigenetic modification of PPAR-related ligands in lipid metabolism and propose future avenues of research. Results: TFs participate in epigenetic modifications in different forms, causing changes in gene expression. The interactions between the different epigenetic modifications and PPARs are important biological developments that affect fat tissue differentiation, lipogenesis, and lipid metabolism, thereby inducing or inhibiting the development of obesity. We then highlight the need for more research to understand the role of epigenetic modifications and PPARs. Conclusions: Epigenetic mechanisms involved in the regulation of PPARs may be excellent therapeutic targets for obesity treatment. However, there is a need for a deeper understanding of how PPARs and other obesity-related transcription factors interact with epigenetic modifications.

Applying behavior change techniques to weight management during pregnancy: Impact on perinatal outcomes

Unhealthy behaviors and lifestyle choices are contributing to the obesity epidemic and associated morbidities. Among reproductive aged women, obesity adversely affects perinatal outcomes and longer term maternal and child health. Interventions utilizing strategies of behavior change have the potential to improve outcomes, especially during pregnancy. Antenatal interventions to improve adherence to gestational weight gain guidelines are one such example. Although behaviorally-based intervention trials have been associated with modest decreases in gestational weight gain, the effect on short term perinatal outcomes has thus far been minimal. This commentary aims to discuss possible reasons behind the failure to improve perinatal outcomes as well as to encourage future areas of study.