Maternal genistein alters coat color and protects Avy mouse offspring from obesity by modifying the fetal epigenome

Nutritional Factors, DNA Methylation, and Risk of Type 2 Diabetes and Obesity: Perspectives and Challenges

A healthy diet improves life expectancy and helps to prevent common chronic diseases such as type 2 diabetes (T2D) and obesity. The mechanisms driving these effects are not fully understood, but are likely to involve epigenetics. Epigenetic mechanisms control gene expression, maintaining the DNA sequence, and therefore the full genomic information inherited from our parents, unchanged. An interesting feature of epigenetic changes lies in their dynamic nature and reversibility. Accordingly, they are susceptible to correction through targeted interventions. Here we will review the evidence supporting a role for nutritional factors in mediating metabolic disease risk through DNA methylation changes. Special emphasis will be placed on the potential of using DNA methylation traits as biomarkers to predict risk of obesity and T2D as well as on their response to dietary and pharmacological (epi-drug) interventions.

Slowing Down Ageing: The Role of Nutrients and Microbiota in Modulation of the Epigenome

The human population is getting ageing. Both ageing and age-related diseases are correlated with an increased number of senescent cells in the organism. Senescent cells do not divide but are metabolically active and influence their environment by secreting many proteins due to a phenomenon known as senescence associated secretory phenotype (SASP). Senescent cells differ from young cells by several features. They possess more damaged DNA, more impaired mitochondria and an increased level of free radicals that cause the oxidation of macromolecules. However, not only biochemical and structural changes are related to senescence. Senescent cells have an altered chromatin structure, and in consequence, altered gene expression. With age, the level of heterochromatin decreases, and less condensed chromatin is more prone to DNA damage. On the one hand, some gene promoters are easily available for the transcriptional machinery; on the other hand, some genes are more protected (locally increased level of heterochromatin). The structure of chromatin is precisely regulated by the epigenetic modification of DNA and posttranslational modification of histones. The methylation of DNA inhibits transcription, histone methylation mostly leads to a more condensed chromatin structure (with some exceptions) and acetylation plays an opposing role. The modification of both DNA and histones is regulated by factors present in the diet. This means that compounds contained in daily food can alter gene expression and protect cells from senescence, and therefore protect the organism from ageing. An opinion prevailed for some time that compounds from the diet do not act through direct regulation of the processes in the organism but through modification of the physiology of the microbiome. In this review we try to explain the role of some food compounds, which by acting on the epigenetic level might protect the organism from age-related diseases and slow down ageing. We also try to shed some light on the role of microbiome in this process.

Prenatal epigenetics diets play protective roles against environmental pollution

It is thought that germ cells and preimplantation embryos during development are most susceptible to endogenous and exogenous environmental factors because the epigenome in those cells is undergoing dramatic elimination and reconstruction. Exposure to environmental factors such as nutrition, climate, stress, pathogens, toxins, and even social behavior during gametogenesis and early embryogenesis has been shown to influence disease susceptibility in the offspring. Early-life epigenetic modifications, which determine the expression of genetic information stored in the genome, are viewed as one of the general mechanisms linking prenatal exposure and phenotypic changes later in life. From atmospheric pollution, endocrine-disrupting chemicals to heavy metals, research increasingly suggests that environmental pollutions have already produced significant consequences on human health. Moreover, mounting evidence now links such pollution to relevant modification in the epigenome. The epigenetics diet, referring to a class of bioactive dietary compounds such as isothiocyanates in broccoli, genistein in soybean, resveratrol in grape, epigallocatechin-3-gallate in green tea, and ascorbic acid in fruits, has been shown to modify the epigenome leading to beneficial health outcomes. This review will primarily focus on the causes and consequences of prenatal environment pollution exposure on the epigenome, and the potential protective role of the epigenetics diet, which could play a central role in neutralizing epigenomic aberrations against environmental pollutions.

The Suv420h histone methyltransferases regulate PPAR-γ and energy expenditure in response to environmental stimuli

Obesity and its associated metabolic abnormalities have become a global emergency with considerable morbidity and mortality. Epidemiologic and animal model data suggest an epigenetic contribution to obesity. Nevertheless, the cellular and molecular mechanisms through which epigenetics contributes to the development of obesity remain to be elucidated. Suv420h1 and Suv420h2 are histone methyltransferases responsible for chromatin compaction and gene repression. Through in vivo, ex vivo, and in vitro studies, we found that Suv420h1 and Suv420h2 respond to environmental stimuli and regulate metabolism by down-regulating peroxisome proliferator-activated receptor gamma (PPAR-γ), a master transcriptional regulator of lipid storage and glucose metabolism. Accordingly, mice lacking Suv420h proteins activate PPAR-γ target genes in brown adipose tissue to increase mitochondria respiration, improve glucose tolerance, and reduce adipose tissue to fight obesity. We conclude that Suv420h proteins are key epigenetic regulators of PPAR-γ and the pathways controlling metabolism and weight balance in response to environmental stimuli.

Maternal pre-pregnancy obesity, offspring cord blood DNA methylation, and offspring cardiometabolic health in early childhood: an epigenome-wide association study

Pre-pregnancy obesity is an established risk factor for adverse sex-specific cardiometabolic health in offspring. Epigenetic alterations, such as in DNA methylation (DNAm), are a hypothesized link; however, sex-specific epigenomic targets remain unclear. Leveraging data from the Newborn Epigenetics Study (NEST) cohort, linear regression models were used to identify CpG sites in cord blood leukocytes associated with pre-pregnancy obesity in 187 mother-female and 173 mother-male offsprings. DNAm in cord blood was measured using the Illumina HumanMethylation450k BeadChip. Replication analysis was conducted among the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Associations between pre-pregnancy obesity-associated CpG sites and offspring BMI z-score (BMIz) and blood pressure (BP) percentiles at 4-5-years of age were also examined. Maternal pre-pregnacy obesity was associated with 876 CpGs in female and 293 CpGs in male offspring (false discovery rate <5%). Among female offspring, 57 CpG sites, including the top 18, mapped to the TAPBP gene (range of effect estimates: -0.83% decrease to 4.02% increase in methylation). CpG methylation differences in the TAPBP gene were also observed among males (range of effect estimates: -0.30% decrease to 2.59% increase in methylation). While technically validated, none of the TAPBP CpG sites were replicated in ALSPAC. In NEST, methylation differences at CpG sites of the TAPBP gene were associated with BMI z-score (cg23922433 and cg17621507) and systolic BP percentile (cg06230948) in female and systolic (cg06230948) and diastolic (cg03780271) BP percentile in male offspring. Together, these findings suggest sex-specific effects, which, if causal, may explain observed sex-specific effects of maternal obesity.

Supplementing Genistein for Breeder Hens Alters the Fatty Acid Metabolism and Growth Performance of Offsprings by Epigenetic Modification

The experiment was designed to clarify the effect and molecular mechanism of maternal genistein (GEN) on the lipid metabolism and developmental growth of offspring chicks. Laying broiler breeder (LBB) hens were supplemented with 40 mg/kg genistein (GEN), while the control group was fed with the low-soybean meal diet. The offspring chicks were grouped according to the mother generation with 8 replicates each. Hepatic transcriptome data revealed 3915 differentially expressed genes (DEGs, P adjusted < 0.05, fold change > 1.5 or fold change < 0.67) between chicks in the two groups. Maternal GEN activated the GH-IGF1-PI3K/Akt signaling pathway, which promoted the developmental processes and cellular amino acid metabolic processes, as well as inhibited the apoptotic process. GEN treatment significantly increased the weight gain, breast muscle percentage, and liver index in chicks. PANTHER clustering analysis suggested that maternal GEN enhanced the antioxidant activity of chicks by the upregulation of gene (SOD3, MT1, and MT4) expression. Accordingly, the activities of T-AOC and T-SOD in the liver were increased after GEN treatment. The overrepresentation tests revealed that maternal GEN influenced the glycolysis, unsaturated fatty acid biosynthesis, acyl-coenzyme A metabolism, lipid transport, and cholesterol metabolism in the chick livers. Hepatic cholesterol and long-chain fatty acid were significantly decreased after GEN treatment. However, the level of arachidonic acid was higher in the livers of the GEN-treated group compared with the CON group. Moreover, GEN treatment enhanced fatty acid β-oxidation and upregulated PPARδ expression in the chick liver. ChIP-qPCR analysis indicated that maternal GEN might induce histone H3-K36 trimethylation in the promoter region of PPARδ gene (PPARD) through Iws1, methyltransferases. It also induced histone H4-K12 acetylation at the PPARD promoter through MYST2, which activated the PPAR signaling pathways in the chick livers. In summary, supplementing LBB hens with GEN can alter lipid metabolism in the offspring chicks through epigenetic modification and improve the antioxidative capability as well as growth performance.

Outbreak of Murine Infection with Clostridium difficile Associated with the Administration of a Pre- and Perinatal Methyl Donor Diet

Between October 2016 and June 2017, a C57BL/6J mouse colony that was undergoing a pre- and perinatal methyl donor supplementation diet intervention to study the impact of parental nutrition on offspring susceptibility to disease was found to suffer from an epizootic of unexpected deaths. Necropsy revealed the presence of severe colitis, and further investigation linked these outbreak deaths to a Clostridium difficile strain of ribotype 027 that we term 16N203. C. difficile infection (CDI) is associated with antibiotic use in humans. Current murine models of CDI rely on antibiotic pretreatment to establish clinical phenotypes. In this report, the C. difficile outbreak occurs in F1 mice linked to alterations in the parental diet. The diagnosis of CDI in the affected mice was confirmed by cecal/colonic histopathology, the presence of C. difficile bacteria in fecal/colonic culture, and detection of C. difficile toxins. F1 mice from parents fed the methyl supplementation diet also had significantly reduced survival (P < 0.0001) compared with F1 mice from parents fed the control diet. When we tested the 16N203 outbreak strain in an established mouse model of antibiotic-induced CDI, we confirmed that this strain is pathogenic. Our serendipitous observations from this spontaneous outbreak of C. difficile in association with a pre- and perinatal methyl donor diet suggest the important role that diet may play in host defense and CDI risk factors.IMPORTANCEClostridium difficile infection (CDI) has become the leading cause of infectious diarrhea in hospitals worldwide, owing its preeminence to the emergence of hyperendemic strains, such as ribotype 027 (RT027). A major CDI risk factor is antibiotic exposure, which alters gut microbiota, resulting in the loss of colonization resistance. Current murine models of CDI also depend on pretreatment of animals with antibiotics to establish disease. The outbreak that we report here is unique in that the CDI occurred in mice with no antibiotic exposure and is associated with a pre- and perinatal methyl supplementation donor diet intervention study. Our investigation subsequently reveals that the outbreak strain that we term 16N203 is an RT027 strain, and this isolated strain is also pathogenic in an established murine model of CDI (with antibiotics). Our report of this spontaneous outbreak offers additional insight into the importance of environmental factors, such as diet, and CDI susceptibility.

A Conceptual Framework for Studying and Investing in Precision Nutrition

Nutrients and food-derived bioactive molecules must transit complex metabolic pathways, and these pathways vary between people. Metabolic heterogeneity is caused by genetic variation, epigenetic variation, differences in microbiome composition and function, lifestyle differences and by variation in environmental exposures. This review discusses a number of these sources of metabolic heterogeneity and presents some of the research investments that will be needed to make applications of precision nutrition practical.

From Genotype to Phenotype: Through Chromatin

Advances in sequencing technologies have enabled the exploration of the genetic basis for several clinical disorders by allowing identification of causal mutations in rare genetic diseases. Sequencing technology has also facilitated genome-wide association studies to gather single nucleotide polymorphisms in common diseases including cancer and diabetes. Sequencing has therefore become common in the clinic for both prognostics and diagnostics. The success in follow-up steps, i.e., mapping mutations to causal genes and therapeutic targets to further the development of novel therapies, has nevertheless been very limited. This is because most mutations associated with diseases lie in inter-genic regions including the so-called regulatory genome. Additionally, no genetic causes are apparent for many diseases including neurodegenerative disorders. A complementary approach is therefore gaining interest, namely to focus on epigenetic control of the disease to generate more complete functional genomic maps. To this end, several recent studies have generated large-scale epigenetic datasets in a disease context to form a link between genotype and phenotype. We focus DNA methylation and important histone marks, where recent advances have been made thanks to technology improvements, cost effectiveness, and large meta-scale epigenome consortia efforts. We summarize recent studies unravelling the mechanistic understanding of epigenetic processes in disease development and progression. Moreover, we show how methodology advancements enable causal relationships to be established, and we pinpoint the most important issues to be addressed by future research.

Biomarker Identification of Maternal Genistein Exposure Induced Obesity by Metabonomics Analysis

The objective of this study was to confirm the effect of maternal genistein exposure on body weight of male offspring and the metabolic alterations associated with maternal genistein-induced obesity. Pregnant female Sprague-Dawley (SD) rats were supplemented with 300 mg/kg diet of genistein (GEN) or no genistein (CON) throughout pregnancy and lactation. The growth of male offspring was investigated until 12 week age and the mechanism of obesity was studied using metabonomics by ultra performance liquid chromatography and quadrupole time-of-flight (UPLC Q-TOF) MS with electrospray ionization in positive ESI mode (ESI+). Compared with the CON group, body weight, fat pad and food intake of male offspring in GEN group were increased significantly at the age of weeks 10 to 12 (p<0.05). Ten urine principal metabolites contributing to the clusters were identified, including increased 8-Isoprostaglandin F2a, and decreased L-Proline, Betaine, L-Acetylcarnitine, Norsalsolinol, Indoleacrylic acid, L-Tryptophan, Lysophosphatidylcholines (LysoPC) (20 : 4), Lysophosphatidylethanolamines (LysoPE) (18 : 1) and LysoPC (O-18 : 0). Our results confirmed weight-increasing effects of maternal genistein exposure, accompanied by favorable changes in metabolites in the male offspring' urine. Therefore, this research enables us to better understand obesity and predict risk of obesity-related disease by studying metabolites present in the urine.

Preconceptional, Gestational, and Lactational Exposure to an Unconventional Oil and Gas Chemical Mixture Alters Energy Expenditure in Adult Female Mice

Previous studies conducted in our laboratory have found altered adult health outcomes in animals with prenatal exposure to environmentally relevant levels of unconventional oil and gas (UOG) chemicals with endocrine-disrupting activity. This study aimed to examine potential metabolic health outcomes following a preconception, prenatal and postnatal exposure to a mixture of 23 UOG chemicals. Prior to mating and from gestation day 1 to postnatal day 21, C57BL/6J mice were developmentally exposed to a laboratory-created mixture of 23 UOG chemicals in maternal drinking water. Body composition, spontaneous activity, energy expenditure, and glucose tolerance were evaluated in 7-month-old female offspring. Neither body weight nor body composition differed in 7-month female mice. However, females exposed to 1.5 and 150 μg/kg/day UOG mix had lower total and resting energy expenditure within the dark cycle. In the light cycle, the 1,500 μg//kg/day group had lower total energy expenditure and the 1.5 μg/kg/day group had lower resting energy expenditure. Females exposed to the 150 μg/kg/day group had lower spontaneous activity in the dark cycle, and females exposed to the 1,500 μg/kg/day group had lower activity in the light cycle. This study reports for the first time that developmental exposure to a mixture of 23 UOG chemicals alters energy expenditure and spontaneous activity in adult female mice.

Environmental Change-Dependent Inherited Epigenetic Response

Epigenetic modifications are a mechanism conveying environmental information to subsequent generations via parental germ lines. Research on epigenetic responses to environmental changes in wild mammals has been widely neglected, as well as studies that compare responses to changes in different environmental factors. Here, we focused on the transmission of DNA methylation changes to naive male offspring after paternal exposure to either diet (~40% less protein) or temperature increase (10 °C increased temperature). Because both experiments focused on the liver as the main metabolic and thermoregulation organ, we were able to decipher if epigenetic changes differed in response to different environmental changes. Reduced representation bisulfite sequencing (RRBS) revealed differentially methylated regions (DMRs) in annotated genomic regions in sons sired before (control) and after the fathers’ treatments. We detected both a highly specific epigenetic response dependent on the environmental factor that had changed that was reflected in genes involved in specific metabolic pathways, and a more general response to changes in outer stimuli reflected by epigenetic modifications in a small subset of genes shared between both responses. Our results indicated that fathers prepared their offspring for specific environmental changes by paternally inherited epigenetic modifications, suggesting a strong paternal contribution to adaptive processes.

Genistein Improves Liver Damage in Male Mice Exposed to Morphine

Background:

Morphine is commonly used to treat severe pain. This substance is significantly metabolized in the liver and causes disturbing effects. Genistein is an isoflavone and has antioxidant properties. The aim of this study was to evaluate the effects of genistein against morphine damages on mouse liver.

Methods:

Between May 2017 and March 2018, 48 male mice were divided into six groups (n = 8 in each group). Various doses of genistein (25 and 50 mg/kg) and morphine plus genistein (25 and 50 mg/kg) were administered intraperitoneally to 48 male mice for 20 consequent days. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), serum nitric oxide (NO) levels, liver weight, and the diameter of hepatocytes and central hepatic vein were studied and compared using one-way analysis of variance.

Results:

Morphine administration significantly increased the mean diameter of the central hepatic vein (22.76 ± 1.9 μm vs. 15.04 ± 0.60 μm, χ² = 21.814, P = 0.001) and hepatocytes (3.03 ± 0.10 μm vs. 1.10 ± 0.05 μm, χ² = 9.873, P = 0.001) respectively, blood serum NO level (38.00% ± 2.09% vs. 18.72% ± 4.40%, χ² = 20.404, P < 0.001), liver enzyme level (AST: 111.80 ± 5.10 ng/ml vs. 81.93 ± 2.20 ng/ml, χ² = 32.201, P < 0.0001; ALT: 45.14 ± 4.10 ng/ml vs. 35.49 ± 2.50 ng/ml, χ² = 18.203, P < 0.0001; and ALP: 3.28 ± 0.20 ng/ml vs. 2.14 ± 0.10, χ² = 5.04, P < 0.0001, respectively), and decreased liver weight (18.50 ± 0.90 g vs. 27.15 ± 0.50 g, χ² = 22.415, P = 0.001) compared to saline group (0.535–0.750, P < 0.0001). However, administration of genistein plus morphine significantly enhanced liver weight (25 mg/kg: 21.15 ± 2.13 g vs. 18.50 ± 0.90 g, χ² = 19.251, P < 0.0001; 50 mg/kg: 21.20 ± 1.00 g vs. 18.5 ± 0.9 g, χ² = 19.502, P < 0.0001, respectively) and reduced the mean diameter of hepatocyte (25 mg/kg: 2.17 ± 0.30 μm vs. 3.03 ± 0.10 μm, χ² = 22.780, P = 0.001; 50 mg/kg: 2.01 ± 0.20 μm vs. 3.03 ± 0.10 μm χ² = 7.120, P = 0.001, respectively), central hepatic vein (25 mg/kg: 19.53 ± 1.00 μm vs. 22.76 ± 1.90 μm, χ² = 20.681, P = 0.001; 50 mg/kg: 19.44 ± 1.20 μm vs. 22.76 ± 1.90 μm, χ² = 18.451, P = 0.001, respectively), AST (25 mg/kg: 95.40 ± 5.20 ng/ml vs. 111.80 ± 5.010 ng/ml, P < 0.0001; 50 mg/kg: 90.78 ± 6.00 ng/ml vs. 111.80 ± 5.10 ng/ml, χ² = 17.112, P < 0.0001, respectively), ALT (25 mg/kg: 35.78 ± 5.01 ng/ml vs. 45.14 ± 4.10 ng/ml, χ² = 15.320, P < 0.0001; 50 mg/kg: 33.78 ± 2.60 ng/ml vs. 45.14 ± 4.10 ng/ml, χ² = 14.023, P < 0.0001, respectively), ALP (25 mg/kg: 2.35 ± 0.30 ng/ml vs. 3.28 ± 0.20 ng/ml, χ² = 4.101, P < 0.0001; 50 mg/kg: 2.34 ± 0.10 ng/ml vs. 3.28 ± 0.20 ng/ml, χ² = 2.033, P < 0.0001, respectively), and NO levels (25 mg/kg: 25.92% ± 2.30% vs. 38% ± 2.09%, χ² = 17.103, P < 0.0001; 50 mg/kg: 24.74% ± 4.10% vs. 38% ± 2.09%, χ² = 25.050, P = 0.001, respectively) compared to morphine group.

Conclusion:

It seems that genistein administration might improve liver damages induced by morphine in mice.

Reprint of "The interaction between environmental triggers and epigenetics in autoimmunity"

Systemic lupus erythematosus flares when genetically predisposed people encounter environmental agents that cause oxidative stress, such as infections and sunlight. How these modify the immune system to initiate flares is unclear. Drug induced lupus models demonstrate that CD4+ T cells epigenetically altered with DNA methylation inhibitors cause lupus in animal models, and similar T cells are found in patients with active lupus. How infections and sun exposure inhibit T cell DNA methylation is unclear. DNA methylation patterns are replicated each time a cell divides in a process that requires DNA methyltransferase one (Dnmt1), which is upregulated as cells enter mitosis, as well as the methyl donor S-adenosylmethionine, created from dietary sources. Reactive oxygen species that inhibit Dnmt1 upregulation, and a diet poor in methyl donors, combine to cause lupus in animal models. Similar changes are found in patients with active lupus, indicating a mechanism contributing to lupus flares.

Environmentally Induced Epigenetic Plasticity in Development: Epigenetic Toxicity and Epigenetic Adaptation

PURPOSE OF REVIEW

Epigenetic processes represent important mechanisms underlying developmental plasticity in response to environmental exposures. The current review discusses three classes of environmentally-induced epigenetic changes reflecting two aspects of that plasticity, toxicity effects as well as adaptation in the process of development.

RECENT FINDINGS

Due to innate resilience, epigenetic changes caused by environmental exposures may not always lead impairments but may allow the organisms to achieve positive developmental outcomes through appropriate adaptation and a buffering response. Thus, some epigenetic adaptive responses to an immediate stimulus or exposure early in life would be expected to have a survival advantage but these same responses may also result in adverse developmental outcomes as they persists into later life stage. Although accumulating literature has identified environmentally induced epigenetic changes and linked them to health outcomes, we currently face challenges in the interpretation of the functional impact of their epigenetic plasticity.

SUMMARY

Current environmental epigenetic research suggest that epigenetic processes may serve as a mechanism for resilience, and that they can be considered in terms of their impact on toxicity as a negative outcome, but also on adaptation for improved survival or health. This review encourages epigenetic environmental studies to move deeper inside into the functional meaning of epigenetic plasticity in the development.

Protective effect of tea against lead and cadmium-induced oxidative stress-a review

Exposure to Cd and Pb reduces the activity of antioxidant enzymes, which points to a decrease in the antioxidant potential of the body as a result of supplying factors which enhance cellular oxidation processes. Man is exposed to the effects of toxic metals because they are present in the environment, including in food. Since no effective ways to reduce the concentrations of Cd an Pb in food exist, studies are undertaken to develop methods of reducing their toxic effect on the body through chelating these metals using nutrients (which reduces their absorption by tissues) or increasing the oxidative capacity of the body (which decreases the possibility of inducing oxidative damage to internal organs). Studies performed on laboratory animals have shown that the use of tea infusions fulfil both functions.

Identification, Characterization, and Heritability of Murine Metastable Epialleles: Implications for Non-genetic Inheritance

Generally repressed by epigenetic mechanisms, retrotransposons represent around 40% of the murine genome. At the Agouti viable yellow (Avy) locus, an endogenous retrovirus (ERV) of the intracisternal A particle (IAP) class retrotransposed upstream of the agouti coat-color locus, providing an alternative promoter that is variably DNA methylated in genetically identical individuals. This results in variable expressivity of coat color that is inherited transgenerationally. Here, a systematic genome-wide screen identifies multiple C57BL/6J murine IAPs with Avy epigenetic properties. Each exhibits a stable methylation state within an individual but varies between individuals. Only in rare instances do they act as promoters controlling adjacent gene expression. Their methylation state is locus-specific within an individual, and their flanking regions are enriched for CTCF. Variably methylated IAPs are reprogrammed after fertilization and re-established as variable loci in the next generation, indicating reconstruction of metastable epigenetic states and challenging the generalizability of non-genetic inheritance at these regions.

Characterization of Genetic and Epigenetic Variation in Sperm and Red Blood Cells from Adult Hatchery and Natural-Origin Steelhead, Oncorhynchus mykiss

While the goal of most conservation hatchery programs is to produce fish that are genetically and phenotypically indistinguishable from the wild stocks they aim to restore, there is considerable evidence that salmon and steelhead reared in hatcheries differ from wild fish in phenotypic traits related to fitness. Some evidence suggests that these phenotypic differences have a genetic basis (e.g., domestication selection) but another likely mechanism that remains largely unexplored is that differences between hatchery and wild populations arise as a result of environmentally-induced heritable epigenetic change. As a first step toward understanding the potential contribution of these two possible mechanisms, we describe genetic and epigenetic variation in hatchery and natural-origin adult steelhead, Oncorhynchus mykiss, from the Methow River, WA. Our main objectives were to determine if hatchery and natural-origin fish could be distinguished genetically and whether differences in epigenetic programming (DNA methylation) in somatic and germ cells could be detected between the two groups. Genetic analysis of 72 fish using 936 SNPs generated by Restriction Site Associated DNA Sequencing (RAD-Seq) did not reveal differentiation between hatchery and natural-origin fish at a population level. We performed Reduced Representation Bisulfite Sequencing (RRBS) on a subset of 10 hatchery and 10 natural-origin fish and report the first genome-wide characterization of somatic (red blood cells (RBCs)) and germ line (sperm) derived DNA methylomes in a salmonid, from which we identified considerable tissue-specific methylation. We identified 85 differentially methylated regions (DMRs) in RBCs and 108 DMRs in sperm of steelhead reared for their first year in a hatchery environment compared to those reared in the wild. This work provides support that epigenetic mechanisms may serve as a link between hatchery rearing and adult phenotype in steelhead; furthermore, DMRs identified in germ cells (sperm) highlight the potential for these changes to be passed on to future generations.

Dietary Modulation of the Epigenome

Epigenetics is the study of heritable mechanisms that can modify gene activity and phenotype without modifying the genetic code. The basis for the concept of epigenetics originated more than 2,000 yr ago as a theory to explain organismal development. However, the definition of epigenetics continues to evolve as we identify more of the components that make up the epigenome and dissect the complex manner by which they regulate and are regulated by cellular functions. A substantial and growing body of research shows that nutrition plays a significant role in regulating the epigenome. Here, we critically assess this diverse body of evidence elucidating the role of nutrition in modulating the epigenome and summarize the impact such changes have on molecular and physiological outcomes with regards to human health.

Targeting cancer stem cells with dietary phytochemical - Repositioned drug combinations

The tumor microenvironment is complex with the cancer stem cell (CSC) as a member within its community. This population possesses the capacity to self-renew and to cause cellular heterogeneity of the tumor. CSCs are resistant to conventional anti-proliferative drugs. In order to be curative, it is imperative that CSCs must be eliminated by cancer therapy. A variety of dietary phytochemicals and repositioned drugs can act synergistically with conventional anti-cancer agents. In this review, we advocate the development of a novel approach, namely combination therapy by incorporating both phytochemicals and repositioned drugs to target CSCs. We cover select dietary phytochemicals (curcumin, resveratrol, EGCG, genistein) and repurposed drugs (metformin, niclosamide, thioridazine, chloroquine). Five of the eight (curcumin, resveratrol, EGCG, genistein, metformin) are listed in "The Halifax Project", that explores "the concept of a low-toxicity 'broad-spectrum' therapeutic approach that could simultaneously target many key pathways and mechanisms" [1]. For these compounds, we discuss their mechanisms of action, in which models their anti-CSC activities were identified, as well as advantages, challenges and potentials of combination therapy.

Intrauterine Programming of Glucocorticoid-Insulin-Like Growth Factor-1 Axis-Mediated Developmental Origin of Osteoporosis Susceptibility in Female Offspring Rats with Prenatal Caffeine Exposure

Epidemiologic investigations suggest that excessive intake of caffeine during pregnancy is one of the risk factors for osteoporosis in adult offspring. However, the phenomena and mechanisms have remained obscure. This study found that prenatal caffeine exposure (PCE) leads to persistent bone dysplasia in gestational day 20 and postnatal week 12 offspring rats and increases the susceptibility to osteoporosis in postnatal week 28 offspring rats. In the embryonic period, PCE increases the concentration of serum corticosterone and inhibits the expression of insulin-like growth factor-1 (IGF1) and osteogenic differentiation genes. After birth, the recovery of IGF1 expression in PCE offspring is unable to completely compensate osteogenic function, and chronic stress can lead to a further decrease in IGF1 expression. In vitro experiments found that corticosterone instead of caffeine restrains mineralized nodule formation and osteoblast differentiation by inhibiting IGF1 expression. The corticosterone inhibits H3K9 and H3K14 histone acetylation of IGF1 in osteoblasts through glucocorticoid receptor and CCAAT and enhancer binding protein α, respectively. In conclusion, glucocorticoid instead of caffeine inhibits bone IGF1 expression via glucocorticoid receptor and CCAAT and enhancer binding protein α and mediates the PCE-induced bone dysplasia and bone mass reduction in offspring fetal rats, which may contribute to osteoporosis susceptibility in adulthood.

Epigenetic Mechanisms Link Maternal Diets and Gut Microbiome to Obesity in the Offspring

Nutrition is the most important environmental factor that can influence early developmental processes through regulation of epigenetic mechanisms during pregnancy and neonatal periods. Maternal diets or nutritional compositions contribute to the establishment of the epigenetic profiles in the fetus that have a profound impact on individual susceptibility to certain diseases or disorders in the offspring later in life. Obesity is considered a global epidemic that impairs human life quality and also increases risk of development of many human diseases such as diabetes and cardiovascular diseases. Studies have shown that maternal nutrition status is closely associated with obesity in progenies indicating obesity has a developmental origin. Maternal diets may also impact the early establishment of the fetal and neonatal microbiome leading to specific epigenetic signatures that may potentially predispose to the development of late-life obesity. This article will review the association of different maternal dietary statuses including essential nutritional quantity and specific dietary components with gut microbiome in determining epigenetic impacts on offspring susceptibility to obesity.

Cumulative lifetime maternal stress and epigenome-wide placental DNA methylation in the PRISM cohort

Evolving evidence links maternal stress exposure to changes in placental DNA methylation of specific genes regulating placental function that may have implications for the programming of a host of chronic disorders. Few studies have implemented an epigenome-wide approach. Using the Infinium HumanMethylation450 BeadChip (450K), we investigated epigenome-wide placental DNA methylation in relation to maternal experiences of traumatic and non-traumatic stressors over her lifetime assessed using the Life Stressor Checklist-Revised (LSC-R) survey (n = 207). We found differential DNA methylation at epigenome-wide statistical significance (FDR = 0.05) for 112 CpGs. Additionally, we observed three clusters that exhibited differential methylation in response to high maternal lifetime stress. Enrichment analyses, conducted at an FDR = 0.20, revealed lysine degradation to be the most significant pathway associated with maternal lifetimes stress exposure. Targeted enrichment analyses of the three largest clusters of probes, identified using the gap statistic, were enriched for genes associated with endocytosis (i.e., SMAP1, ANKFY1), tight junctions (i.e., EPB41L4B), and metabolic pathways (i.e., INPP5E, EEF1B2). These pathways, also identified in the top 10 KEGG pathways associated with maternal lifetime stress exposure, play important roles in multiple physiological functions necessary for proper fetal development. Further, two genes were identified to exhibit multiple probes associated with maternal lifetime stress (i.e., ANKFY1, TM6SF1). The methylation status of the probes belonging to each cluster and/or genes exhibiting multiple hits, may play a role in the pathogenesis of adverse health outcomes in children born to mothers with increased lifetime stress exposure.

Body weight regulation, socioeconomic status and epigenetic alterations

Obesity is a complex disease which has reached epidemic dimensions. Thus, prevention of excessive weight gain and associated metabolic and cardiovascular diseases has to start as early in life as possible. The impact of epigenetic mechanisms on the regulation of genes involved in obesity is increasingly recognized. On the other hand, it is well known that socioeconomic factors influence the risk for obesity. These factors can also have an impact on epigenetic gene regulation. There is increasing body of evidence that several factors and interventions addressing extragenetic causes of obesity may not only improve individual health, but also the health of future generations by epigenetic alterations. Our current understanding of epigenetic changes has shown that many of them are potentially reversible, i.e. by physical exercise, by pharmacological treatment, by environmental factors or nutrition, or even by influencing socioeconomic factors, which might have impact on improving health in future generations by avoiding epigenetic dysregulation. In this review we present the current state of the art with regard to the interplay between social determinants, weight status and epigenetic alterations.

Soy-Derived Phytochemical Genistein Modifies Chromatome Topology to Restrict Cancer Cell Proliferation

Epidemiological data indicate that human cancer risk is significantly reduced by the consumption of soy-based foods containing the "phytoestrogen" genistein, which can signal via host cell estrogen receptors. While additional chemoprotective effects of genistein induced by epigenetic factors have also been reported, the key molecules and mechanisms involved are poorly defined. We therefore investigated genistein effects on chromatin-bound proteins in the estrogen receptor-deficient cell line MDA-MB-231 which is insensitive to phytoestrogen signaling. After exposure to low-dose genistein for >1 month, MDA-MB-231 cells exhibited stable epigenetic alterations that are analyzed via partial MNase digestion and TMT-based quantitative proteomics. 3177 chromatin-bound proteins are identified with high confidence, including 882 molecules that displayed altered binding topology after cell conditioning with genistein. Prolonged phytochemical exposure conferred heritable changes in the binding topology of key epigenetic regulators including ATRX, SUV39H1/H2, and HP1BP3 that are preserved in untreated progeny, resulting in sustained downregulation of proliferation genes and reduced cell growth. These data indicate that soy derivative genistein exerts complex estrogen receptor-independent effects on the epigenome likely to influence tumorigenesis by restricting cell growth.

Darwin's Pangenesis and the Lamarckian Inheritance of Acquired Characters

Since the earliest days of evolutionary thought, the problem of the inheritance of acquired characters has been a central debate. Darwin accepted the inheritance of acquired characters as an established fact and gave many instances. His Pangenesis was more than anything else an attempt to provide a theory for its explanation. Over the past several decades, there has been increasing evidence for the inheritance of acquired habit and immunity, and for heritable changes induced by food and fertilizer, stress, chemicals, temperature, light and other environmental factors. Many studies also suggest that parental age has certain influences on the characters of offspring. The current explanations include environmentally induced DNA changes (mainly DNA rearrangements and DNA methylation), RNA-mediated inheritance, and horizontal gene transfer. These mechanistic explanations are consistent with Darwin's Pangenesis.

Enhancing and Extending Biological Performance and Resilience

Human performance, endurance, and resilience have biological limits that are genetically and epigenetically predetermined but perhaps not yet optimized. There are few systematic, rigorous studies on how to raise these limits and reach the true maxima. Achieving this goal might accelerate translation of the theoretical concepts of conditioning, hormesis, and stress adaptation into technological advancements. In 2017, an Air Force-sponsored conference was held at the University of Massachusetts for discipline experts to display data showing that the amplitude and duration of biological performance might be magnified and to discuss whether there might be harmful consequences of exceeding typical maxima. The charge of the workshop was "to examine and discuss and, if possible, recommend approaches to control and exploit endogenous defense mechanisms to enhance the structure and function of biological tissues." The goal of this white paper is to fulfill and extend this workshop charge. First, a few of the established methods to exploit endogenous defense mechanisms are described, based on workshop presentations. Next, the white paper accomplishes the following goals to provide: (1) synthesis and critical analysis of concepts across some of the published work on endogenous defenses, (2) generation of new ideas on augmenting biological performance and resilience, and (3) specific recommendations for researchers to not only examine a wider range of stimulus doses but to also systematically modify the temporal dimension in stimulus inputs (timing, number, frequency, and duration of exposures) and in measurement outputs (interval until assay end point, and lifespan). Thus, a path forward is proposed for researchers hoping to optimize protocols that support human health and longevity, whether in civilians, soldiers, athletes, or the elderly patients. The long-term goal of these specific recommendations is to accelerate the discovery of practical methods to conquer what were once considered intractable constraints on performance maxima.

Prenatal caffeine exprosure increases adult female offspring rat's susceptibility to osteoarthritis via low-functional programming of cartilage IGF-1 with histone acetylation

Our previous in vivo studies showed that prenatal caffeine exposure (PCE) could restrain the development of chondrogenesis, which may delay fetal articular cartilage development and increase susceptibility to osteoarthritis in adults. So, the goal of the current study is to clarify theincreasing susceptibility to adult osteoarthritis in caffeine-exposed female offspring and its'mechanism. Pregnant rats were treated with 120 mg/kg·d caffeine or equal volumes of saline from gestational day (GD) 9 to 20. knee joints were collected from GD20 female fetuses and 18-week old female offspring which was treated with strenuous running for 6 weeks (55 min/day at 20 m/min) load to induce osteoarthritis. Knee joints from GD20 fetuses and adult offspring were collected for histochemistry and immunohistochemistry. Next, chondrocytes were isolated from 1-day-old newborn rats and in vitro studies were conducted where the cells in primary culture were exposed to 1, 10, and 100 μM caffeine and 250, 500, and 1,250 nM corticosterone. Insulin-like growth factor 1 (IGF-1) signal pathway genes' expression levels in fetal chondrocytes were studied, and IGF-1 histone acetylation was detected in vitro. Immunohistochemical results showed low expression levels of IGF-1 signaling genes (IGF-1, IRS-1, AKT, and COL2A1) both in fetal and adult cartilage with PCE. For adult offspring, histological results and Mankin score revealed increased cartilage destruction and accelerated osteoarthritis progression in PCE group with strenuous running exercise. Analysis in vitro revealed that caffeine and corticosterone impeded the expression of IGF-1 signaling pathway aggrecan and COL2A1 genes, but only corticosterone decreased H3K9 and H3K27 acetylation in the IGF-1 promoter region. In concluson, PCE low functional programmed cartilage IGF-1 by histone acetylation modification via overexposure to corticosterone and delayed articular cartilage development from fetus to adults. Then, the delayed cartilage development increased susceptibility to osteoarthritis in offsprings.

DNA methylation of imprinted genes at birth is associated with child weight status at birth, 1 year, and 3 years

Background

This study assessed the associations between nine differentially methylated regions (DMRs) of imprinted genes in DNA derived from umbilical cord blood leukocytes in males and females and (1) birth weight for gestational age z score, (2) weight-for-length (WFL) z score at 1 year, and (3) body mass index (BMI) z score at 3 years.

Methods

We conducted multiple linear regression in n = 567 infants at birth, n = 288 children at 1 year, and n = 294 children at 3 years from the Newborn Epigenetics Study (NEST). We stratified by sex and adjusted for race/ethnicity, maternal education, maternal pre-pregnancy BMI, prenatal smoking, maternal age, gestational age, and paternal race. We also conducted analysis restricting to infants not born small for gestational age.

Results

We found an association between higher methylation of the sequences regulating paternally expressed gene 10 (PEG10) and anthropometric z scores at 1 year (β = 0.84; 95% CI = 0.34, 1.33; p = 0.001) and 3 years (β = 1.03; 95% CI = 0.37, 1.69; p value = 0.003) in males only. Higher methylation of the DMR regulating mesoderm-specific transcript (MEST) was associated with lower anthropometric z scores in females at 1 year (β = - 1.03; 95% CI - 1.60, - 0.45; p value = 0.001) and 3 years (β = - 1.11; 95% CI - 1.98, - 0.24; p value = 0.01). These associations persisted when we restricted to infants not born small for gestational age.

Conclusion

Our data support a sex-specific association between altered methylation and weight status in early life. These methylation marks can contribute to the compendium of epigenetically regulated regions detectable at birth, influencing obesity in childhood. Larger studies are required to confirm these findings.

Epigenetic regulation of mammalian sex determination

Regulation of gene expression without changing the DNA sequence is governed by epigenetic mechanisms. Epigenetic regulation is important for changing chromatin structure in response to environmental cues as well as maintaining chromatin structure after cell division. The epigenetic machinery can reversibly change chromatin function, allowing a wide variety of biological processes in multicellular organisms to be controlled. Epigenetic regulation ensures spatial and temporal accuracy of the expression of developmentally regulated genes. So far, few studies have focused on the relationship between epigenetic regulation and mammalian sex development, despite this being an interesting area of research. Sex development consists of three sequential stages: the undifferentiated stage, gonadal differentiation into testes or ovaries, and differentiation of internal and external genitalia. Some genetic studies have revealed that epigenetic regulation is required for proper gonadal differentiation in mice. Particularly, the epigenetic machinery plays an integral part in sex determination, which is the first step of gonadal differentiation. Mammalian sex determination is triggered by activation of the mammalian sex-determining gene, Sry, in a spatially and temporally accurate manner. Several studies have demonstrated that expression of Sry is controlled not only by specific transcription factors but also by the epigenetic machinery. Here, we focus on the epigenetic regulation of Sry expression.

Temporal Efficacy of a Sulforaphane-Based Broccoli Sprout Diet in Prevention of Breast Cancer through Modulation of Epigenetic Mechanisms

Breast cancer is the most common cancer and the second leading cause of cancer-related death among women. An important risk factor for breast cancer is individual genetic background, which is initially generated early in human life, for example, during the processes of embryogenesis and fetal development in utero Bioactive dietary components such as sulforaphane (SFN), an isothiocyanate from cruciferous vegetables including broccoli sprouts (BSp), cabbage, and kale, has been shown to reduce the risk of developing many common cancers through regulation of epigenetic mechanisms. Our study indicates a prenatal/maternal BSp dietary treatment exhibited maximal preventive effects in inhibiting breast cancer development compared with postnatal early-life and adult BSp treatments in two transgenic mouse models that can develop breast cancer. Postnatal early-life BSp treatment starting prior to puberty onset showed protective effects in prevention of breast cancer but was not as effective as the prenatal/maternal BSp treatment. However, adulthood-administered BSp diet did not reduce mammary tumorigenesis. Our results suggest that the prenatal/maternal BSp bioactive natural plant product may impact early embryonic development by regulating global differential gene expression through affecting epigenetic profiles resulting in differential susceptibility to breast cancer later in life. These results suggest that a temporal exposure to epigenetic-modulating dietary components such as cruciferous vegetables could be a key factor for maximizing chemopreventive effects on human breast cancer. This study may lead to translational breast cancer chemopreventive potential by appropriate administration of key dietary components leading to early breast cancer prevention in humans. Cancer Prev Res; 11(8); 451-64. ©2018 AACR.

The Effects of Trauma, with or without PTSD, on the Transgenerational DNA Methylation Alterations in Human Offsprings

Exposure to psychological trauma is a strong risk factor for several debilitating disorders including post-traumatic stress disorder (PTSD) and depression. Besides the impact on mental well-being and behavior in the exposed individuals, it has been suggested that psychological trauma can affect the biology of the individuals, and even have biological and behavioral consequences on the offspring of exposed individuals. While knowledge of possible epigenetic underpinnings of the association between exposure to trauma and risk of PTSD has been discussed in several reviews, it remains to be established whether trauma-induced epigenetic modifications can be passed from traumatized individuals to subsequent generations of offspring. The aim of this paper is to review the emerging literature on evidence of transgenerational inheritance due to trauma exposure on the epigenetic mechanism of DNA methylation in humans. Our review found an accumulating amount of evidence of an enduring effect of trauma exposure to be passed to offspring transgenerationally via the epigenetic inheritance mechanism of DNA methylation alterations and has the capacity to change the expression of genes and the metabolome. This manuscript summarizes and critically reviews the relevant original human studies in this area. Thus, it provides an overview of where we stand, and a clearer vision of where we should go in terms of future research directions.

Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring

Clinical and animal studies have indicated that hypercholesterolemia and its associated diseases have intrauterine developmental origins. Our previous studies showed that prenatal caffeine exposure (PCE) led to fetal overexposure to maternal glucocorticoids (GCs) and increased serum total cholesterol levels in adult rat offspring. This study further confirms the intrauterine programming of PCE-induced hypercholesterolemia in female adult rat offspring. Pregnant Wistar rats were intragastrically administered caffeine (30, 60, and 120 mg/kg/d) from gestational day (GD)9 to 20. Female rat offspring were euthanized at GD20 and postnatal wk 12; several adult rat offspring were additionally subjected to ice-water swimming stimulation to induce chronic stress prior to death. The effects of GCs on cholesterol metabolism and epigenetic regulation were verified using the L02 cell line. The results showed that PCE induced hypercholesterolemia in adult offspring, which manifested as significantly higher levels of serum total cholesterol and LDL cholesterol (LDL-C) as well as higher ratios of LDL-C/HDL cholesterol. We further found that the cholesterol levels were increased in fetal livers but were decreased in fetal blood, accompanied by increased maternal blood cholesterol levels and reduced placental cholesterol transport. Furthermore, analysis of PCE offspring in the uterus and in a postnatal basal/chronic stress state and the results of in vitro experiments showed that hepatic cholesterol metabolism underwent GC-dependent changes and was associated with cholesterol synthase via abnormalities in 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) histone acetylation. We concluded that, to compensate for intrauterine placentally derived decreases in fetal blood cholesterol levels, high intrauterine GC levels activated fetal hepatic CCAAT enhancer binding protein α signaling and down-regulated Sirtuin1 expression, which mediated the high levels of histone acetylation ( via H3K9ac and H3K14ac) and expression of HMGCR. This GC-dependent cholesterol metabolism programming effect was sustained through adulthood, leading to the occurrence of hypercholesterolemia.-Xu, D., Luo, H. W., Hu, W., Hu, S. W., Yuan, C., Wang, G. H., Zhang, L., Yu, H., Magdalou, J., Chen, L. B., Wang, H. Intrauterine programming mechanism for hypercholesterolemia in prenatal caffeine-exposed female adult rat offspring.

The interaction between environmental triggers and epigenetics in autoimmunity

Systemic lupus erythematosus flares when genetically predisposed people encounter environmental agents that cause oxidative stress, such as infections and sunlight. How these modify the immune system to initiate flares is unclear. Drug induced lupus models demonstrate that CD4+ T cells epigenetically altered with DNA methylation inhibitors cause lupus in animal models, and similar T cells are found in patients with active lupus. How infections and sun exposure inhibit T cell DNA methylation is unclear. DNA methylation patterns are replicated each time a cell divides in a process that requires DNA methyltransferase one (Dnmt1), which is upregulated as cells enter mitosis, as well as the methyl donor S-adenosylmethionine, created from dietary sources. Reactive oxygen species that inhibit Dnmt1 upregulation, and a diet poor in methyl donors, combine to cause lupus in animal models. Similar changes are found in patients with active lupus, indicating a mechanism contributing to lupus flares.

Epigenetic changes and their implications in autoimmune hepatitis

BACKGROUND

The genetic risk of autoimmune hepatitis is insufficient to explain the observed risk, and epigenetic changes may explain disparities in disease occurrence in different populations within and between countries. The goal of this review was to examine how epigenetic changes induced by the environment or inherited as a phenotypic trait may affect autoimmune hepatitis and be amenable to therapeutic intervention.

MATERIALS AND METHODS

Pertinent abstracts were identified in PubMed by multiple search terms. The number of abstracts reviewed was 1689, and the number of full-length articles reviewed exceeded 150.

RESULTS

Activation of pro-inflammatory genes in autoimmune disease is associated with hypomethylation of deoxyribonucleic acid and modification of histones within chromatin. Organ-specific microribonucleic acids can silence genes by marking messenger ribonucleic acids for degradation, and they can promote inflammatory activity or immunosuppression. High circulating levels of the microribonucleic acids 21 and 122 have been demonstrated in autoimmune hepatitis, and they may increase production of pro-inflammatory cytokines. Microribonucleic acids are also essential for maintaining regulatory T cells. Drugs, pollutants, infections, diet and ageing can induce inheritable epigenetic changes favouring autoimmunity. Reversal is feasible by manipulating enzymes, transcription factors, gene-silencing molecules and toxic exposures or by administering methyl donors and correcting vitamin D deficiency. Gene targets, site specificity, efficacy and consequences are uncertain.

CONCLUSIONS

Potentially reversible epigenetic changes may affect the occurrence and outcome of autoimmune hepatitis, and investigations are warranted to determine the nature of these changes, key genomic targets, and feasible interventions and their consequences.

Dietary supplement intake during pregnancy; better safe than sorry?

Consumption of dietary supplements and specifically niche products such as supplements targeting pregnant women is increasing. The advantages of dietary supplementation during pregnancy with folic acid have been established, but health effects of many other supplements have not been confirmed. EU and US legislation on dietary supplements requires the product to be safe for the direct consumer, the mother. Long-term health effects for the fetus due to fetal programming (in utero adaptation of the fetal epigenome due to environmental stimuli such as supplementation) are not taken into account. Such epigenetic alterations can, however, influence the response to health challenges in adulthood. We therefore call for both conducting research in birth cohorts and animal studies to identify potential health effects in progeny of supplement consuming mothers as well as the establishment of a nutrivigilance scheme to identify favorable and adverse effects post-marketing. The acquired knowledge can be used to create more effective legislation on dietary supplement intake during pregnancy for safety of the child. Increasing knowledge on the effects of consuming supplements will create a safer environment for future mothers and their offspring to optimize their health before, during and after pregnancy.

Maternal high-fat diet associated with altered gene expression, DNA methylation, and obesity risk in mouse offspring

We investigated maternal obesity in inbred SM/J mice by assigning females to a high-fat diet or a low-fat diet at weaning, mating them to low-fat-fed males, cross-fostering the offspring to low-fat-fed SM/J nurses at birth, and weaning the offspring onto a high-fat or low-fat diet. A maternal high-fat diet exacerbated obesity in the high-fat-fed daughters, causing them to weigh more, have more fat, and have higher serum levels of leptin as adults, accompanied by dozens of gene expression changes and thousands of DNA methylation changes in their livers and hearts. Maternal diet particularly affected genes involved in RNA processing, immune response, and mitochondria. Between one-quarter and one-third of differentially expressed genes contained a differentially methylated region associated with maternal diet. An offspring high-fat diet reduced overall variation in DNA methylation, increased body weight and organ weights, increased long bone lengths and weights, decreased insulin sensitivity, and changed the expression of 3,908 genes in the liver. Although the offspring were more affected by their own diet, their maternal diet had epigenetic effects lasting through adulthood, and in the daughters these effects were accompanied by phenotypic changes relevant to obesity and diabetes.

Safety of folic acid

There is a large body of literature demonstrating the efficacy of maternal folic acid intake in preventing birth defects, as well as investigations into potential adverse consequences of consuming folic acid above the upper intake level (UL). Recently, two authoritative bodies convened expert panels to assess risks from high intakes of folic acid: the U.S. National Toxicology Program and the UK Scientific Advisory Committee on Nutrition. Overall, the totality of the evidence examined by these panels, as well as studies published since the release of their reports, have not established risks for adverse consequences resulting from existing mandatory folic acid fortification programs that have been implemented in many countries. Current folic acid fortification programs have been shown to support public health in populations, and the exposure levels are informed by and adherent to the precautionary principle. Additional research is needed to assess the health effects of folic acid supplement use when the current upper limit for folic acid is exceeded.

Epigenetic supersimilarity of monozygotic twin pairs

BACKGROUND

Monozygotic twins have long been studied to estimate heritability and explore epigenetic influences on phenotypic variation. The phenotypic and epigenetic similarities of monozygotic twins have been assumed to be largely due to their genetic identity.

RESULTS

Here, by analyzing data from a genome-scale study of DNA methylation in monozygotic and dizygotic twins, we identified genomic regions at which the epigenetic similarity of monozygotic twins is substantially greater than can be explained by their genetic identity. This "epigenetic supersimilarity" apparently results from locus-specific establishment of epigenotype prior to embryo cleavage during twinning. Epigenetically supersimilar loci exhibit systemic interindividual epigenetic variation and plasticity to periconceptional environment and are enriched in sub-telomeric regions. In case-control studies nested in a prospective cohort, blood DNA methylation at these loci years before diagnosis is associated with risk of developing several types of cancer.

CONCLUSIONS

These results establish a link between early embryonic epigenetic development and adult disease. More broadly, epigenetic supersimilarity is a previously unrecognized phenomenon that may contribute to the phenotypic similarity of monozygotic twins.