Progressive, transgenerational changes in offspring phenotype and epigenotype following nutritional transition

DNA methylation profiles in bovine sperm are associated with daughter fertility

The current decline in dairy cattle fertility has resulted in significant financial losses for dairy farmers. In the past, most efforts to improve dairy cattle fertility have been focused on either management or genetics, while epigenetics have received less attention. In this study, 12 bulls were selected from a provided 100 bull list and studied (High daughter fertility = 6, Low daughter fertility = 6) for Enzymatic methylation sequencing in the Illumina HiSeq platform according to the Canadian daughter fertility index (DFI), sires with high and low daughter fertility have average DFI of 92 and 112.6, respectively. And the bull list provided shows a mean DFI of 103.4. 252 CpGs with methylation differences greater than 20% (q < 0.01) were identified, as well as the top 10 promising DMRs with a 15% methylation difference (q < 1.1e-26). Interestingly, the DMCs and DMRs were found to be distributed more on the X chromosome than on the autosome, and they were covered by gene clusters linked to germ cell formation and development. In conclusion, these findings could enhance our ability to make informed decisions when deciding on superior bulls and advance our understanding of paternal epigenetic inheritance.

Biological methylation: redefining the link between genotype and phenotype

The central dogma of molecular biology is responsible for the crucial flow of genetic information from DNA to protein through the transcription and translation process. Although the sequence of DNA is constant in all organs, the difference in protein and variation in the phenotype is mainly due to the quality and quantity of tissue-specific gene expression and methylation pattern. The term methylation has been defined and redefined by various scientists in the last fifty years. There is always huge excitement around this field because the inheritance of something is beyond its DNA sequence. Advanced gene methylation studies have redefined molecular genetics and these tools are considered de novo in alleviating challenges of animal disease and production. Recent emerging evidence has shown that the impact of DNA, RNA, and protein methylation is crucial for embryonic development, cell proliferation, cell differentiation, and phenotype production. Currently, many researchers are focusing their work on methylation to understand its significant role in expression, disease-resistant traits, productivity, and longevity. The main aim of the present review is to provide an overview of DNA, RNA, and protein methylation, current research output from different sources, methodologies, factors responsible for methylation of genes, and future prospects in animal genetics.

Epigenetic regulations as drivers of insecticide resistance and resilience to climate change in arthropod pests

Arthropod pests are remarkably capable of rapidly adapting to novel forms of environmental stress, including insecticides and climate change. The dynamic interplay between epigenetics and genetics explains the largely unexplored reality underlying rapid climatic adaptation and the development of insecticide resistance in insects. Epigenetic regulation modulates gene expression by methylating DNA and acetylating histones that play an essential role in governing insecticide resistance and adaptation to climate change. This review summarises and discusses the significance of recent advances in epigenetic regulation that facilitate phenotypic plasticity in insects and their symbiotic microbes to cope with selection pressure implied by extensive insecticide applications and climate change. We also discuss how epigenetic changes are passed on to multiple generations through sexual recombination, which remains enigmatic. Finally, we explain how these epigenetic signatures can be utilized to manage insecticide resistance and pest resilience to climate change in Anthropocene.

Epigenetic regulation by metabolites from the gut microbiome

The gut microbiome can metabolise food components, such as dietary fibres and various phytochemicals; and the microbiome can also synthesise some nutrients, for example B vitamins. The metabolites produced by bacteria and other micro-organisms in the colon can have implications for health and disease risk. Some of these metabolites are epigenetically active, and can contribute to changes in the chemical modification and structure of chromatin by affecting the activity and expression of epigenetically-active enzymes, for example histone deacetylases and DNA methyltransferases. The epigenetic activity of such gut microbiome metabolites is reviewed herein.

Cumulative Metabolic and Epigenetic Effects of Paternal and/or Maternal Supplementation with Arachidonic Acid across Three Consecutive Generations in Mice

Apart from the known associations between arachidonic acid (AA), weight gain, and neurological and immune function, AA exposure leads to alterations in global and gene-specific DNA methylation (DNAm) and fatty acid (FA) content in human cultured cells. However, it is unknown as to whether the latter effects occur in vivo and are maintained over extended periods of time and across generations. To address this issue, we asked whether AA supplementation for three consecutive generations (prior to coitus in sires or in utero in dams) affected offspring growth phenotypes, in addition to liver DNAm and FA profiles in mice. Twelve-week-old BALB/c mice were exposed daily to AA dissolved in soybean oil (vehicle, VH), or VH only, for 10 days prior to mating or during the entire pregnancy (20 days). On average, 15 mice were supplemented per generation, followed by analysis of offspring body weight and liver traits (x average = 36 and 10 per generation, respectively). Body weight cumulatively increased in F2 and F3 offspring generations and positively correlated with milligrams of paternal or maternal offspring AA exposure. A concomitant increase in liver weight was observed. Notably, akin to AA-challenged cultured cells, global DNAm and cis-7-hexadecenoic acid (16:1n-9), an anti-inflammatory FA that is dependent on stearoyl-CoA desaturase 1 (SCD1) activity, increased with milligrams of AA exposure. In accordance, liver Scd1 promoter methylation decreased with milligrams of germline AA exposure and was negatively correlated with liver weight. Our results show that mice retain cellular memories of AA exposure across generations that could potentially be beneficial to the innate immune system.

ADSA Foundation Scholar Award: Early-life exposure to hyperthermia: Productive and physiological outcomes, costs, and opportunities

Global rising temperature is a considerable threat to livestock production and an impediment to animal welfare. In fact, the 5 warmest years on record have occurred since 2016. Although the effect of heat stress on lactating cattle is well recognized and extensively studied, it is increasingly evident that rising temperatures will affect dairy cattle of all ages and lactation states. However, the extent and consequences of this effect are less understood and often overlooked in the literature and dairy industry. Early-life experiences, such as exposure to hyperthermia, can have life-long implications for health and productivity. This review highlights the body of work surrounding the effects of heat-stress exposure in young dairy cattle, including the prenatal fetus (in utero), postnatal calves (preweaning), and growing heifers, which are all categories that are typically not considered for heat-stress abatement on farm. Insights into the physiological and molecular mechanisms that might explain the adverse phenotypic outcomes of heat-stress exposure at different stages of development are also discussed. The estimated economic loss of in utero hyperthermia is addressed, and the ties between biological findings and opportunities for the application of cooling management interventions on farm are also presented. Our research highlights the importance of heat-stress abatement strategies for dry-pregnant cows to ensure optimal multigenerational productivity and showcases the benefits of cooling neonatal calves and growing heifers. Understanding the implications of heat stress at all life stages from a physiological, molecular, economic, and welfare perspective will lead to the development of novel and refined practices and interventions to help overcome the long-lasting effects of climate change in the dairy industry.

Effects of maternal obesity in an ovine model on metabolic outcomes in F2 adults and F3 neonates

Accumulating evidence suggests that indications of metabolic syndrome can be inherited through the germline as a result of maternal obesity. We hypothesized that diet-induced maternal obesity during gestation would program metabolic consequences for multiple generations of offspring, even when first, second, and third generation offspring (F1, F2, F3, respectively) were fed only to requirements. Control (CON) and obese (OB) ewes (generation 0; F0) were bred to a single ram to produce the first generation of offspring (F1). From 60 d prior to conception through term, CONF0 ate 100% National Research Council recommendations (NRC), while OBF0 ewes ate 150% NRC. All F1, F2, and F3 ate 100% NRC after weaning. All mature F1 ewes were bred to a single ram to generate CONF2 (n = 6) and OBF2 (n = 10). All mature F2 ewes were bred to a single ram to produce CONF3 (n = 6) and OBF3 (n = 10). OBF2 ewes exhibited greater (P < 0.0001) plasma cortisol than CONF2 throughout gestation. A glucose tolerance test at 90% gestation revealed OBF2 ewes had higher (P < 0.05) insulin response with similar glucose, resulting in greater (P < 0.05) insulin resistance. OBF3 neonates had similar weight, lean mass, and body fat mass to CONF3 neonates. These data suggest that multigenerational programming of adverse metabolic phenotypes occur in association with F0 maternal obesity, yet adiposity may return to CON levels in F3 neonates.

Global climate change, diet, and the complex relationship between human host and microbiome: Towards an integrated picture

Dietary changes can alter the human microbiome with potential detrimental consequences for health. Given that environment, health, and evolution are interconnected, we ask: Could diet-driven microbiome perturbations have consequences that extend beyond their immediate impact on human health? We address this question in the context of the urgent health challenges posed by global climate change. Drawing on recent studies, we propose that not only can diet-driven microbiome changes lead to dysbiosis, they can also shape life-history traits and fuel human evolution. We posit that dietary shifts prompt mismatched microbiome-host genetics configurations that modulate human longevity and reproductive success. These mismatches can also induce a heritable intra-holobiont stress response, which encourages the holobiont to re-establish equilibrium within the changed nutritional environment. Thus, while mismatches between climate change-related genetic and epigenetic configurations within the holobiont increase the risk and severity of diseases, they may also affect life-history traits and facilitate adaptive responses. These propositions form a framework that can help systematize and address climate-related dietary challenges for policy and health interventions.

Role of environmentally induced epigenetic transgenerational inheritance in evolutionary biology: Unified Evolution Theory

The current evolutionary biology theory primarily involves genetic alterations and random DNA sequence mutations to generate the phenotypic variation required for Darwinian natural selection to act. This neo-Darwinian evolution is termed the Modern Evolution Synthesis and has been the primary paradigm for nearly 100 years. Although environmental factors have a role in neo-Darwinian natural selection, Modern Evolution Synthesis does not consider environment to impact the basic molecular processes involved in evolution. An Extended Evolutionary Synthesis has recently developed that extends the modern synthesis to consider non-genetic processes. Over the past few decades, environmental epigenetics research has been demonstrated to regulate genetic processes and directly generate phenotypic variation independent of genetic sequence alterations. Therefore, the environment can on a molecular level through non-genetic (i.e. epigenetic) mechanisms directly influence phenotypic variation, genetic variation, inheritance and adaptation. This direct action of the environment to alter phenotype that is heritable is a neo-Lamarckian concept that can facilitate neo-Darwinian (i.e. Modern Synthesis) evolution. The integration of genetics, epigenetics, Darwinian theory, Lamarckian concepts, environment, and epigenetic inheritance provides a paradigm shift in evolution theory. The role of environmental-induced epigenetic transgenerational inheritance in evolution is presented to describe a more unified theory of evolutionary biology.

Maternal cholesterol levels during gestation: boon or bane for the offspring?

An increase in cholesterol levels is perceived during pregnancy and is considered as a normal adaptive response to the development of the fetus. In some pregnancies, excessive increase in total cholesterol with high levels of Low-Density Lipoprotein leads to maladaptation by the fetus to cholesterol demands, resulting in a pathological condition termed as maternal hypercholesterolemia (MH). MH is considered clinically irrelevant and therefore cholesterol levels are not routinely checked during pregnancy, as a consequence of which there is scarce information on its global prevalence in pregnant women. Studies have reported that MH during pregnancy can cause atherogenesis in adults emphasizing the concept of in utero programming of fetus. Moreover, Gestational Diabetes Mellitus, obesity and Polycystic Ovary Syndrome are potential risk factors which strengthen combined pathologies in placenta and fetuses of mothers with MH. However, lack of conclusive evidence on cholesterol transport and underlying programming demand substantial research to develop population-based life style strategies for women in their childbearing years. The current review focuses on the mechanisms and outcomes of MH from existing epidemiological as well as experimental data and presents a detailed insight on this novel risk factor of cardiovascular diseases.

Early leucine programming on protein utilization and mTOR signaling by DNA methylation in zebrafish (Danio rerio)

Background

Early nutritional programming affects a series of metabolism, growth and development in mammals. Fish also exhibit the developmental plasticity by early nutritional programming. However, little is known about the effect of early amino acid programming on growth and metabolism.

Methods

In the present study, zebrafish (Danio rerio) was used as the experimental animal to study whether early leucine stimulation can programmatically affect the mechanistic target of rapamycin (mTOR) signaling pathway, growth and metabolism in the later life, and to undercover the mechanism of epigenetic regulation. Zebrafish larvas at 3 days post hatching (dph) were raised with 1.0% leucine from 3 to 13 dph during the critical developmental stage, then back to normal water for 70 days (83 dph).

Results

The growth performance and crude protein content of zebrafish in the early leucine programming group were increased, and consistent with the activation of the mTOR signaling pathway and the high expression of genes involved in the metabolism of amino acid and glycolipid. Furthermore, we compared the DNA methylation profiles between the control and leucine-stimulated zebrafish, and found that the methylation levels of CG-differentially methylated regions (DMGs) and CHH-DMGs of genes involved in mTOR signaling pathway were different between the two groups. With quantitative PCR analysis, the decreased methylation levels of CG type of Growth factor receptor-bound protein 10 (Grb10), eukaryotic translation initiation factor 4E (eIF4E) and mTOR genes of mTOR signaling pathway in the leucine programming group, might contribute to the enhanced gene expression.

Conclusions

The early leucine programming could improve the protein synthesis and growth, which might be attributed to the methylation of genes in mTOR pathway and the expression of genes involved in protein synthesis and glycolipid metabolism in zebrafish. These results could be beneficial for better understanding of the epigenetic regulatory mechanism of early nutritional programming.

A single-cell epigenetic model for paternal psychological stress-induced transgenerational reprogramming in offspring

Experimental evidence shows that parental psychological stress affects the long-term health of offspring in an inheritable fashion. Although epigenetic mechanisms, including DNA methylation, miRNA, and histone modifications, are involved in transgenerational programming, the underlining mechanisms of transgenerational inheritance remain unsolved. Here, we present a single-cell-based computational model for transgenerational inheritance for investigating the long-term dynamics of phenotype changes in response to parental stress. The model is based on a recent study that has identified the imprinted sperm gene Sfmbt2 as a key target, and incorporates crosstalks among drastically different time scales in mammalian development, including DNA methylation, transcription, cell division, and population dynamics. Computational analysis of the model suggests a positive feedback to DNA methylation in the promoter region of sperm Sfmbt2 gene that provides a possible mechanism to mediate the parental psychological stress reprogramming in offspring. This approach provides a modeling framework for the understanding of the roles that epigenetics play in transgenerational inheritance.

Primers on nutrigenetics and nutri(epi)genomics: Origins and development of precision nutrition

Understanding the relationship between genotype and phenotype is a central goal not just for genetics but also for medicine and biological sciences. Despite outstanding technological progresses, genetics alone is not able to completely explain phenotypes, in particular for complex diseases. Given the existence of a "missing heritability", growing attention has been given to non-mendelian mechanisms of inheritance and to the role of the environment. The study of interaction between gene and environment represents a challenging but also a promising field with high potential for health prevention, and epigenetics has been suggested as one of the best candidate to mediate environmental effects on the genome. Among environmental factors able to interact with both genome and epigenome, nutrition is one of the most impacting. Not just our genome influences the responsiveness to food and nutrients, but vice versa, nutrition can also modify gene expression through epigenetic mechanisms. In this complex picture, nutrigenetics and nutrigenomics represent appealing disciplines aimed to define new prospectives of personalized nutrition. This review introduces to the study of gene-environment interactions and describes how nutrigenetics and nutrigenomics modulate health, promoting or affecting healthiness through life-style, thus playing a pivotal role in modulating the effect of genetic predispositions.

Increased stress and altered expression of histone modifying enzymes in brain are associated with aberrant behaviour in vitamin B12 deficient female mice

A sub-optimal nutritional environment from early life can be envisaged as a stressor that translates into mental health problems in adulthood. After considering (a) the widespread prevalence of vitamin B12 deficiency especially amongst women in developing countries and (b) the importance of vitamin B12 in normal brain function, in this study we have elucidated the behavioural correlates of chronic severe and moderate vitamin B12 deficiency in C57BL/6 mice. Female weanling mice were assigned to three dietary groups: (a) control AIN-76A diet with cellulose as dietary fibre (b) vitamin B12 restricted AIN-76A diet with pectin as dietary fibre (severe deficiency group) and (c) vitamin B12 restricted AIN-76A diet with cellulose as dietary fibre (moderate deficiency group). The mice received these diets throughout pregnancy, lactation and thereafter. Nest-building, maternal care, anxiety and depressive behaviours were evaluated. Oxidative stress, activities of antioxidant enzymes and expression of various histone modifying enzymes in brain were investigated to unravel the probable underlying mechanisms. Our data suggests that both severe and moderate vitamin B12 deficiency induced anxiety and impaired maternal care. However, only severe vitamin B12 deficiency induced depression. Oxidative stress and poor antioxidant defense underlie the deleterious effects of both severe and moderate vitamin B12 deficiency. Altered expression of histone modifying enzymes in the brain of severely deficient mice is suggestive of epigenetic reprogramming. This study suggests that chronic vitamin B12 deficiency leads to behavioural anomalies in female C57BL/6 mice and the severity of these outcomes can be correlated to the level of deficiency.

DNA methylation of the promoter region of bnip3 and bnip3l genes induced by metabolic programming

BACKGROUND

Environmental changes of biotic or abiotic nature during critical periods of early development may exert a profound influence on physiological functions later in life. This process, named developmental programming can also be driven through parental nutrition. At molecular level, epigenetic modifications are the most likely candidate for persistent modulation of genes expression in later life.

RESULTS

In order to investigate epigenetic modifications induced by programming in rainbow trout, we focused on bnip3 and bnip3l paralogous genes known to be sensitive to environmental changes but also regulated by epigenetic modifications. Two specific stimuli were used: (i) early acute hypoxia applied at embryo stage and (ii) broodstock and fry methionine deficient diet, considering methionine as one of the main methyl-group donor needed for DNA methylation. We observed a programming effect of hypoxia with an increase of bnip3a and the four paralogs of bnip3l expression level in fry. In addition, parental methionine nutrition was correlated to bnip3a and bnip3lb1 expression showing evidence for early fry programming. We highlighted that both stimuli modified DNA methylation levels at some specific loci of bnip3a and bnip3lb1.

CONCLUSION

Overall, these data demonstrate that methionine level and hypoxia stimulus can be of critical importance in metabolic programming. Both stimuli affected DNA methylation of specific loci, among them, an interesting CpG site have been identified, namely - 884 bp site of bnip3a, and may be positively related with mRNA levels.

The investigations of genetic determinants of the metabolic syndrome

Metabolic syndrome is the aggregation of cardiovascular risk factors that increases the risk of type 2 diabetes and cardiovascular diseases. Family and twin studies, heritability spectrum for its components and different prevalence among ethnicities, have provided genetic susceptibility to the metabolic syndrome. The investigations of genetic base for the disorder have recognized numerous chromosomes, various DNA polymorphisms in candidate genes and many gene variants, that are associated with metabolic syndrome as an entity or its traits, which mostly are related to lipid metabolism. In addition, recent finding of the role of rare variants, epigenetic mechanisms, non-coding RNAs and evaluating the function of genes in molecular networks have improved our knowledge. However, a common genetic basis explaining the co-occurrence of its components has not been identified and more researches are essential.

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.

Alterations in sperm DNA methylation, non-coding RNA and histone retention associate with DDT-induced epigenetic transgenerational inheritance of disease

BACKGROUND

Environmental toxicants such as DDT have been shown to induce the epigenetic transgenerational inheritance of disease (e.g., obesity) through the germline. The current study was designed to investigate the DDT-induced concurrent alterations of a number of different epigenetic processes including DNA methylation, non-coding RNA (ncRNA) and histone retention in sperm.

METHODS

Gestating females were exposed transiently to DDT during fetal gonadal development, and then, the directly exposed F1 generation, the directly exposed germline F2 generation and the transgenerational F3 generation sperm were investigated.

RESULTS

DNA methylation and ncRNA were altered in each generation sperm with the direct exposure F1 and F2 generations being predominantly distinct from the F3 generation epimutations. The piRNA and small tRNA were the most predominant classes of ncRNA altered. A highly conserved set of histone retention sites were found in the control lineage generations which was not significantly altered between generations, but a large number of new histone retention sites were found only in the transgenerational generation DDT lineage sperm.

CONCLUSIONS

Therefore, all three different epigenetic processes were concurrently altered as DDT induced the epigenetic transgenerational inheritance of sperm epimutations. The direct exposure generations sperm epigenetic alterations were distinct from the transgenerational sperm epimutations. The genomic features and gene associations with the epimutations were investigated to help elucidate the integration of these different epigenetic processes. Observations demonstrate all three epigenetic processes are involved in transgenerational inheritance. The different epigenetic processes appear to be integrated in mediating the epigenetic transgenerational inheritance phenomenon.

Differential vulnerability to adverse nutritional conditions in male and female rats: Modulatory role of estradiol during development

Many studies have shown the importance of an adequate nutritional environment during development to optimally establish the neurohormonal circuits that regulate feeding behavior. Under- or over-nutrition during early stages of life can lead to alterations in the physiology and brain networks that control food intake, resulting in a greater vulnerability to suffer maladjustments in energy metabolism in adulthood. These alterations produced by under- or over-nourishment during development differ between males and females, as does the modulatory action that estradiol exerts on the alterations produced by malnutrition. Estradiol regulates metabolism and brain metabolic circuits through the same transcription factor pathway, STAT3, that leptin and ghrelin use to program feeding circuits. Although more research is needed to disentangle the actual role of estradiol during development on the programming of feeding circuits, a synergistic role together with leptin and/or ghrelin might be hypothesized.

Review article: next-generation transformative advances in the pathogenesis and management of autoimmune hepatitis

BACKGROUND

Advances in autoimmune hepatitis that transform current concepts of pathogenesis and management can be anticipated as products of ongoing investigations driven by unmet clinical needs and an evolving biotechnology.

AIM

To describe the advances that are likely to become transformative in autoimmune hepatitis, based on the direction of current investigations.

METHODS

Pertinent abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and a secondary bibliography was developed. The discovery process was repeated, and a tertiary bibliography was identified. The number of abstracts reviewed was 2830, and the number of full-length articles reviewed exceeded 150.

RESULTS

Risk-laden allelic variants outside the major histocompatibility complex (rs3184504, r36000782) are being identified by genome-wide association studies, and their gene products are potential therapeutic targets. Epigenetic changes associated with environmental cues can enhance the transcriptional activity of genes, and chromatin re-structuring and antagonists of noncoding molecules of ribonucleic acid are feasible interventions. The intestinal microbiome is a discovery field for microbial products and activated immune cells that may translocate to the periphery and respond to manipulation. Epidemiological studies and controlled interview-based surveys may implicate environmental and xenobiotic factors that warrant evidence-based changes in lifestyle, and site-directed molecular and cellular interventions promise to change the paradigm of treatment from one of blanket immunosuppression.

CONCLUSIONS

Advances in genetics, epigenetics, pathophysiology, epidemiology, and site-directed molecular and cellular interventions constitute the next generation of transformative advances in autoimmune hepatitis.

Connecting the Dots Between Fatty Acids, Mitochondrial Function, and DNA Methylation in Atherosclerosis

PURPOSE OF REVIEW

The quest for factors and mechanisms responsible for aberrant DNA methylation in human disease-including atherosclerosis-is a promising area of research. This review focuses on the role of fatty acids (FAs) as modulators of DNA methylation-in particular the role of mitochondrial beta-oxidation in FA-induced changes in DNA methylation during the progression of atherosclerosis.

RECENT FINDINGS

Recent publications have advanced the knowledge in all areas touched by this review: the causal role of lipids in shaping the DNA methylome, the associations between chronic degenerative disease and mitochondrial function, the lipid composition of the atheroma, and the relevance of DNA hypermethylation in atherosclerosis. Evidence is beginning to emerge, linking the dynamics of FA type abundance, mitochondrial function, and DNA methylation in the atheroma and systemically. In particular, this review highlights mitochondrial beta-oxidation as an important regulator of DNA methylation in metabolic disease. Despite the many questions still unanswered, this area of research promises to identify mechanisms and molecular factors that establish a pathological gene expression pattern in atherosclerosis.

Remodelling of the hepatic epigenetic landscape of glucose-intolerant rainbow trout (Oncorhynchus mykiss) by nutritional status and dietary carbohydrates

The rainbow trout, a carnivorous fish, displays a 'glucose-intolerant' phenotype revealed by persistent hyperglycaemia when fed a high carbohydrate diet (HighCHO). Epigenetics refers to heritable changes in gene activity and is closely related to environmental changes and thus to metabolism adjustments governed by nutrition. In this study we first assessed in the trout liver whether and how nutritional status affects global epigenome modifications by targeting DNA methylation and histone marks previously reported to be affected in metabolic diseases. We then examined whether dietary carbohydrates could affect the epigenetic landscape of duplicated gluconeogenic genes previously reported to display changes in mRNA levels in trout fed a high carbohydrate diet. We specifically highlighted global hypomethylation of DNA and hypoacetylation of H3K9 in trout fed a HighCHO diet, a well-described phenotype in diabetes. g6pcb2 ohnologs were also hypomethylated at specific CpG sites in these animals according to their up-regulation. Our findings demonstrated that the hepatic epigenetic landscape can be affected by both nutritional status and dietary carbohydrates in trout. The mechanism underlying the setting up of these epigenetic modifications has now to be explored in order to improve understanding of its impact on the glucose intolerant phenotype in carnivorous teleosts.

Bisphenol-A and metabolic diseases: epigenetic, developmental and transgenerational basis

Exposure to environmental toxicants is now accepted as a factor contributing to the increasing incidence of obesity and metabolic diseases around the world. Such environmental compounds are known as 'obesogens'. Among them, bisphenol-A (BPA) is the most widespread and ubiquitous compound affecting humans and animals. Laboratory animal work has provided conclusive evidence that early-life exposure to BPA is particularly effective in predisposing individuals to weight gain. Embryonic exposure to BPA is reported to generate metabolic disturbances later in life, such as obesity and diabetes. When BPA administration is combined with a high-fat diet, there is an exacerbation in the development of metabolic disorders. Remarkably, upon BPA exposure of gestating females, metabolic disturbances have been found both in the offspring and later in life in the mothers themselves. When considering the metabolic effects generated by an early developmental exposure to BPA, one of the questions that arises is the role of precursor cells in the etiology of metabolic disorders. Current evidence shows that BPA and other endocrine disruptors have the ability to alter fat tissue development and growth by affecting the capacity to generate functional adipocytes, as well as their rate of differentiation to specific cell types. Epigenetic mechanisms seem to be involved in the BPA-induced effects related to obesity, as they have been described in both in vitro and in vivo models. Moreover, recent reports also show that developmental exposure to BPA generates abnormalities that can be transmitted to future generations, in a process called as transgenerational epigenetic inheritance.

Epigenomic maintenance through dietary intervention can facilitate DNA repair process to slow down the progress of premature aging

DNA damage caused by various sources remains one of the most researched topics in the area of aging and neurodegeneration. Increased DNA damage causes premature aging. Aging is plastic and is characterised by the decline in the ability of a cell/organism to maintain genomic stability. Lifespan can be modulated by various interventions like calorie restriction, a balanced diet of macro and micronutrients or supplementation with nutrients/nutrient formulations such as Amalaki rasayana, docosahexaenoic acid, resveratrol, curcumin, etc. Increased levels of DNA damage in the form of double stranded and single stranded breaks are associated with decreased longevity in animal models like WNIN/Ob obese rats. Erroneous DNA repair can result in accumulation of DNA damage products, which in turn result in premature aging disorders such as Hutchinson-Gilford progeria syndrome. Epigenomic studies of the aging process have opened a completely new arena for research and development of drugs and therapeutic agents. We propose here that agents or interventions that can maintain epigenomic stability and facilitate the DNA repair process can slow down the progress of premature aging, if not completely prevent it. © 2016 IUBMB Life, 68(9):717-721, 2016.

Transgenerational effects of maternal diet on metabolic and reproductive ageing

The early-life environment, in particular maternal diet during pregnancy, influences a wide range of organs and systems in adult offspring. Mounting evidence suggests that developmental programming can also influence health and disease in grand-offspring. Transgenerational effects can be defined as those persisting into an F2 generation, where the F0 mother experiences suboptimal diet during her pregnancy. In this review, we critically examine evidence for transgenerational developmental programming effects in human populations, focusing on metabolic and reproductive outcomes. We discuss evidence from historical cohorts suggesting that grandchildren of women exposed to famine and other dietary alterations during pregnancy may experience increased rates of later health complications than their control counterparts. The methodological difficulties with transgenerational studies in human cohorts are explored. In particular, the problems with assessing reproductive outcomes in human populations are discussed. In light of the relative paucity of evidence available from human cohorts, we consider key insights from transgenerational experimental animal models of developmental programming by maternal diet; data are drawn from a range of rodent models, as well as the guinea-pig and the sheep. The evidence for different potential mechanisms of transgenerational inheritance or re-propagation of developmental programming effects is evaluated. Transgenerational effects could be transmitted through methylation of the gametes via the paternal and maternal lineage, as well as other possible mechanisms via the maternal lineage. Finally, future directions for exploring these underlying mechanisms further are proposed, including utilizing large, well-characterized, prospective pregnancy cohorts that include biobanks, which have been established in various populations during the last few decades.

Developmental origins of epigenetic transgenerational inheritance

Environmental factors can induce epigenetic alterations in the germ cells that can potentially be transmitted transgenerationally. This non-genetic form of inheritance is termed epigenetic transgenerational inheritance and has been shown in a variety of species including plants, flies, worms, fish, rodents, pigs, and humans. This phenomenon operates during specific critical windows of exposure, linked to the developmental biology of the germ cells (sperm and eggs). Therefore, concepts of the developmental origins of transgenerational inheritance of phenotypic variation and subsequent disease risk need to include epigenetic processes affecting the developmental biology of the germ cell. These developmental impacts on epigenetic transgenerational inheritance, in contrast to multigenerational exposures, are the focus of this Perspective.

Obesity: epigenetic regulation – recent observations

Genetic and environmental factors, especially nutrition and lifestyle, have been discussed in the literature for their relevance to epidemic obesity. Gene-environment interactions may need to be understood for an improved understanding of the causes of obesity, and epigenetic mechanisms are of special importance. Consequences of epigenetic mechanisms seem to be particularly important during certain periods of life: prenatal, postnatal and intergenerational, transgenerational inheritance are discussed with relevance to obesity. This review focuses on nutrients, diet and habits influencing intergenerational, transgenerational, prenatal and postnatal epigenetics; on evidence of epigenetic modifiers in adulthood; and on animal models for the study of obesity.

Environmentally Induced Epigenetic Transgenerational Inheritance of Reproductive Disease

Reproductive disease and fertility issues have dramatically increased in the human population over the last several decades, suggesting environmental impacts. Epigenetics provides a mechanistic link by which an organism can respond to environmental factors. Interestingly, environmentally induced epigenetic alterations in the germ line can promote aberrant gene expression and disease generationally. Environmentally induced epigenetic transgenerational inheritance is defined as germ-line transmission of altered epigenetic information between generations in the absence of continued environmental exposures. This form of nongenetic inheritance has been shown to directly influence fertility and reproductive disease. This review describes the studies in a variety of species that impact reproductive disease and abnormalities. Observations suggest serious attention be paid to the possibility that ancestral exposures to environmental insults promotes transgenerational inheritance of reproductive disease susceptibility. Environmentally induced epigenetic transgenerational inheritance appears to be an important contributing factor to reproductive disease in many organisms, including humans.

Transgenerational epigenetic inheritance of diabetes risk as a consequence of early nutritional imbalances

In today's world, there is an unprecedented rise in the prevalence of chronic metabolic diseases, including obesity, insulin resistance and type 2 diabetes (T2D). The pathogenesis of T2D includes both genetic and environmental factors, such as excessive energy intake and physical inactivity. It has recently been suggested that environmental factors experienced during early stages of development, including the intrauterine and neonatal periods, might play a major role in predisposing individuals to T2D. Furthermore, several studies have shown that such early environmental conditions might even contribute to disease risk in further generations. In this review, we summarise recent data describing how parental nutrition during development increases the risk of diabetes in the offspring. We also discuss the potential mechanisms underlying transgenerational inheritance of metabolic disease, with particular emphasis on epigenetic mechanisms.

Impact of Maternal Diet on the Epigenome during In Utero Life and the Developmental Programming of Diseases in Childhood and Adulthood

Exposure to environmental factors in early life can influence developmental processes and long-term health in humans. Early life nutrition and maternal diet are well-known examples of conditions shown to influence the risk of developing metabolic diseases, including type 2 diabetes mellitus and cardiovascular diseases, in adulthood. It is increasingly accepted that environmental compounds, including nutrients, can produce changes in the genome activity that, in spite of not altering the DNA sequence, can produce important, stable and, in some instances, transgenerational alterations in the phenotype. Epigenetics refers to changes in gene function that cannot be explained by changes in the DNA sequence, with DNA methylation patterns/histone modifications that can make important contributions to epigenetic memory. The epigenome can be considered as an interface between the genome and the environment that is central to the generation of phenotypes and their stability throughout the life course. To better understand the role of maternal health and nutrition in the initiation and progression of diseases in childhood and adulthood, it is necessary to identify the physiological and/or pathological roles of specific nutrients on the epigenome and how dietary interventions in utero and early life could modulate disease risk through epigenomic alteration.

Genome-Wide Locations of Potential Epimutations Associated with Environmentally Induced Epigenetic Transgenerational Inheritance of Disease Using a Sequential Machine Learning Prediction Approach

Environmentally induced epigenetic transgenerational inheritance of disease and phenotypic variation involves germline transmitted epimutations. The primary epimutations identified involve altered differential DNA methylation regions (DMRs). Different environmental toxicants have been shown to promote exposure (i.e., toxicant) specific signatures of germline epimutations. Analysis of genomic features associated with these epimutations identified low-density CpG regions (<3 CpG / 100bp) termed CpG deserts and a number of unique DNA sequence motifs. The rat genome was annotated for these and additional relevant features. The objective of the current study was to use a machine learning computational approach to predict all potential epimutations in the genome. A number of previously identified sperm epimutations were used as training sets. A novel machine learning approach using a sequential combination of Active Learning and Imbalance Class Learner analysis was developed. The transgenerational sperm epimutation analysis identified approximately 50K individual sites with a 1 kb mean size and 3,233 regions that had a minimum of three adjacent sites with a mean size of 3.5 kb. A select number of the most relevant genomic features were identified with the low density CpG deserts being a critical genomic feature of the features selected. A similar independent analysis with transgenerational somatic cell epimutation training sets identified a smaller number of 1,503 regions of genome-wide predicted sites and differences in genomic feature contributions. The predicted genome-wide germline (sperm) epimutations were found to be distinct from the predicted somatic cell epimutations. Validation of the genome-wide germline predicted sites used two recently identified transgenerational sperm epimutation signature sets from the pesticides dichlorodiphenyltrichloroethane (DDT) and methoxychlor (MXC) exposure lineage F3 generation. Analysis of this positive validation data set showed a 100% prediction accuracy for all the DDT-MXC sperm epimutations. Observations further elucidate the genomic features associated with transgenerational germline epimutations and identify a genome-wide set of potential epimutations that can be used to facilitate identification of epigenetic diagnostics for ancestral environmental exposures and disease susceptibility.

Transgenerational Developmental Programming of Ovarian Reserve

Exposure to an adverse early-life environment leads to long-term health problems, many of which are recapitulated in subsequent generations. The female reproductive tract is particularly sensitive to early-life influences, and plays a pivotal role in programming the conceptus. We examine the influence of suboptimal grandmaternal diet on reproductive potential of granddaughters in the absence of any further dietary manipulations in the daughters in a rat low-protein diet model. Exposure to low-protein grand-maternal diet leads to decreased ovarian reserve and increased intra-abdominal fat mass in granddaughters, accompanied by accelerated accumulation of oxidative stress and mtDNA copy number instability in the ovaries. Ovarian telomere length declines more rapidly in the exposed granddaughters, indicating accelerated ageing in the reproductive tract. Thus, we demonstrate that suboptimal grandmaternal diet during pregnancy accelerates reproductive ageing across subsequent generations. These findings have important implications for understanding both individual rates of decline in fertility with age, and the clinical impact of current global trends towards delayed childbearing.

Past, present, and future of epigenetics applied to livestock breeding

This article reviews the concept of Lamarckian inheritance and the use of the term epigenetics in the field of animal genetics. Epigenetics was first coined by Conrad Hal Waddington (1905–1975), who derived the term from the Aristotelian word epigenesis. There exists some controversy around the word epigenetics and its broad definition. It includes any modification of the expression of genes due to factors other than mutation in the DNA sequence. This involves DNA methylation, post-translational modification of histones, but also linked to regulation of gene expression by non-coding RNAs, genome instabilities or any other force that could modify a phenotype. There is little evidence of the existence of transgenerational epigenetic inheritance in mammals, which may commonly be confounded with environmental forces acting simultaneously on an individual, her developing fetus and the germ cell lines of the latter, although it could have an important role in the cellular energetic status of cells. Finally, we review some of the scarce literature on the use of epigenetics in animal breeding programs.

Environmental challenge, epigenetic plasticity and the induction of altered phenotypes in mammals

The level of transcriptional activity of a gene is regulated by epigenetic processes. There is compelling evidence that environmental challenges throughout the life course can induce phenotypic change. In this review, we summarize the current evidence, focusing specifically on the effects of nutrition and of environmental pollutants, that epigenetic processes underpin the induction by environmental change of altered phenotypic traits, emphasizing the implications for health outcomes. We also discuss whether epigenetic processes may be involved in the passage of induced traits between generations. Overall, current findings indicate that epigenetic processes may play an important role in determining disease risk, but there is a lack of studies that demonstrate causal links between epigenetic change and tissue function.

Fat and carbohydrate intake over three generations modify growth, metabolism and cardiovascular phenotype in female mice in an age-related manner

Environmental challenges such as a high fat diet during pregnancy can induce changes in offspring growth, metabolism and cardiovascular function. However, challenges that are sustained over several generations can induce progressive compensatory metabolic adjustments in young adults. It is not known if such effects persist during ageing. We investigated whether diets with different fat and carbohydrate contents over three generations modifies markers of ageing. Female C57BL/6 F0 mice were fed diets containing 5% or 21% fat (w/w) throughout pregnancy and lactation. Female offspring were fed the same diet as their dams until the F3 generation. In each generation, body weight, 24-hour food intake were recorded weekly, and plasma metabolites were measured by colorimetric assays, blood pressure by tail cuff plethysmography and vasoconstriction by myography on postnatal day 90 or 456. There was little effect of diet or generation on phenotypic markers in day 90 adults. There was a significant increase in whole body, liver and heart weight with ageing (d456) in the F3 21% fat group compared to the F1 and F3 5% groups. Fasting plasma glucose concentration was significantly increased with ageing in the 5% group in the F3 generation and in the 21% group in both generations. There was a significant effect of diet and generation on ex-vivo vasoconstriction in ageing females. Differences in dietary fat may induce metabolic compensation in young adults that persist over three generations. However, such compensatory effects decline during ageing.

Long-term metabolic alterations in a febrile seizure model

OBJECTIVE

Febrile seizures (FS) are the most common neurological disease in infancy and early childhood, it can lead to metabolic changes and have long-term health implications. Aim of this study was to investigate the long-term effects of FS on metabolism.

METHODS

We measured certain metabolic parameters in hyperthermia-prone (HP) rats, which were developed using a selective breeding process and showed a lower seizure threshold than wild-type (WT) rats. Body weight, body length, abdominal circumference and the levels of fasting blood glucose, serum triglyceride, and total cholesterol concentrations were analyzed. The mRNA expression of genes involved in glucose and lipid metabolism was determined by qPCR and the histone methylation level in the liver was determined by western blot.

RESULTS

We found that the body weight of the HP rats was significantly lower than that of the WT rats. Similarly, the fasting blood glucose and serum triglyceride levels were lower in the HP group compared with the WT group. These changes were accompanied by increased mRNA expression of genes such as phosphoenolpyruvate carboxykinase (PEPCK) and carnitine palmitoyl transferase-1 (CPT-1), but not peroxisome proliferator-activated receptor α (PPARα). We also found tri-methylation of histone 3 at Lys9 and Lys27 was decreased in the HP group.

CONCLUSIONS

These data may suggest an underlying mechanism by which FS have a long-term effect on energy metabolism via histone methylation.

Environmental Epigenetics and a Unified Theory of the Molecular Aspects of Evolution: A Neo-Lamarckian Concept that Facilitates Neo-Darwinian Evolution

Environment has a critical role in the natural selection process for Darwinian evolution. The primary molecular component currently considered for neo-Darwinian evolution involves genetic alterations and random mutations that generate the phenotypic variation required for natural selection to act. The vast majority of environmental factors cannot directly alter DNA sequence. Epigenetic mechanisms directly regulate genetic processes and can be dramatically altered by environmental factors. Therefore, environmental epigenetics provides a molecular mechanism to directly alter phenotypic variation generationally. Lamarck proposed in 1802 the concept that environment can directly alter phenotype in a heritable manner. Environmental epigenetics and epigenetic transgenerational inheritance provide molecular mechanisms for this process. Therefore, environment can on a molecular level influence the phenotypic variation directly. The ability of environmental epigenetics to alter phenotypic and genotypic variation directly can significantly impact natural selection. Neo-Lamarckian concept can facilitate neo-Darwinian evolution. A unified theory of evolution is presented to describe the integration of environmental epigenetic and genetic aspects of evolution.

Endocrine disruptor induction of epigenetic transgenerational inheritance of disease

Environmental exposures such as toxicants, nutrition and stress have been shown to promote the epigenetic transgenerational inheritance of disease susceptibility. Endocrine disruptors are one of the largest groups of specific toxicants shown to promote this form of epigenetic inheritance. These environmental compounds that interfere with normal endocrine signaling are one of the largest classes of toxicants we are exposed to on a daily level. The ability of ancestral exposures to promote disease susceptibility significantly increases the potential biohazards of these toxicants. Therefore, what your great-grandmother was exposed to during pregnancy may influence your disease development, even in the absence of any exposure, and you are going to pass this on to your grandchildren. This non-genetic form of inheritance significantly impacts our understanding of biology from the origins of disease to evolutionary biology. The current review will describe the previous studies and endocrine disruptors shown to promote the epigenetic transgenerational inheritance of disease.

Potential roles of noncoding RNAs in environmental epigenetic transgenerational inheritance

"Epigenetic transgenerational inheritance" (ETI) has been defined as germline (sperm or egg) transmission of epigenetic information between generations in the absence of direct exposures or genetic manipulations. Among reported cases of ETI in mammals, the majority are induced by environmental factors, including environmental toxicants [e.g. agricultural fungicide vinclozolin, plastic additive bisphenol A, pesticide methoxychlor, dioxin, di-(2-ethylhexyl) phthalate, dichlorodiphenyltrichloroethane, and hydrocarbons] and poor nutritional conditions. Although the ETI phenomenon is well established, the underlying mechanism remains elusive. Putative epimutations, including changes in DNA methylation and histone modification patterns, have been reported, but it remains unclear how these epimutations are formed in the first place, and how they are memorized in the germline and then get transmitted to subsequent generations. Based on recent advances in our understanding of regulatory noncoding RNAs (ncRNAs), I propose that ncRNAs are involved in ETI, during both the initial epimutation formation and the subsequent germline transmission of epimutations. ncRNAs can function at epigenetic levels by affecting DNA methylation and histone modifications, thereby changing gene transcriptional activities, which can lead to an altered mRNA transcriptome associated with a disease phenotype. Alternatively, novel or altered ncRNA expression can cause dysregulated post-transcriptional regulation, thus directly affecting the mRNA transcriptome and inducing a disease phenotype. Sperm-borne ncRNAs are potential mediators for epigenetic memory across generations, but they alone may not be sufficient for stable transmission of epimutations across generations. Overall, research on ncRNAs in the context of ETI is urgently needed to shed light on the underlying mechanism of ETI.

Customized nutritional enhancement for pregnant women appears to lower incidence of certain common maternal and neonatal complications: an observational study

A retrospective chart review analyzed the effect of customized nutrition on the incidence of pregnancy-induced hypertension (PIH), gestational diabetes (GDM), and small- and large-for-gestational-age (SGA, LGA) neonates, examining consecutive deliveries between January 1, 2011, and Decem ber 31, 2012, at a low-risk community hospital. The population was divided into 3 groups: (1) study group (SG), (2) private practice (PP), and (3) community healthcare clinic (CHCC). All groups received standard perinatal management, but additionally the study group was analyzed for serum zinc, carnitine, total 25-hydroxy cholecalciferol (25 OH-D), methylene tetrahydrofolate reductase, and catechol-O-methyl transferase polymorphisms in the first trimester prior to intervention, with subsequent second trimester and postpartum assessment of zinc, carnitine, and 25 OH-D after intervention. Intervention consisted of trimesterby-trimester nutrition and lifestyle education, supplementation of L-methyl folate, magnesium, essential fatty acids, and probiotics for all SG patients, with targeted supplementation of zinc, carnitine, and 25 OH-D. Because of small case occurrence rates of individual conditions in the study group, unreportable reductions were found, except GDM (SG vs CHCC, P value .046 with 95.38% confidence interval [CI]), and PIH (SG vs PP, P value .0505 with 94.95% CIl). The aggregated occurrence rate of the four conditions, however, was significantly lower in the study population than in either comparison population (PP P value .0154 with 98.46% CI, and CHCC P value .0265 with 97.35% CI). Customized nutritional intervention appears to have significantly reduced adverse perinatal outcomes. Prospective study within larger, at-risk populations is needed to determine whether customized nutrition improves conditions individually.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Epigenetics across the human lifespan

Epigenetics has the potential to explain various biological phenomena that have heretofore defied complete explication. This review describes the various types of endogenous human developmental milestones such as birth, puberty, and menopause, as well as the diverse exogenous environmental factors that influence human health, in a chronological epigenetic context. We describe the entire course of human life from periconception to death and chronologically note all of the potential internal timepoints and external factors that influence the human epigenome. Ultimately, the environment presents these various factors to the individual that influence the epigenome, and the unique epigenetic and genetic profile of each individual also modulates the specific response to these factors. During the course of human life, we are exposed to an environment that abounds with a potent and dynamic milieu capable of triggering chemical changes that activate or silence genes. There is constant interaction between the external and internal environments that is required for normal development and health maintenance as well as for influencing disease load and resistance. For example, exposure to pharmaceutical and toxic chemicals, diet, stress, exercise, and other environmental factors are capable of eliciting positive or negative epigenetic modifications with lasting effects on development, metabolism and health. These can impact the body so profoundly as to permanently alter the epigenetic profile of an individual. We also present a comprehensive new hypothesis of how these diverse environmental factors cause both direct and indirect epigenetic changes and how this knowledge can ultimately be used to improve personalized medicine.

Maternal life course socio-economic position and offspring body composition at birth in a multi-ethnic population

BACKGROUND

Size and body composition at birth may affect long-term health. Mean birthweight and body composition differ between ethnic groups living in Europe. We wanted to explore if this relates to differences in socio-economic conditions in country of origin and over the maternal life course.

METHODS

This is a population-based cohort study of healthy pregnant women living in Oslo, Norway. Data on maternal early life and present socio-economic position (SEP) were collected in early gestation, and SEP scores were extracted through two separate principal components analyses. The associations between maternal present SEP and four different offspring anthropometric measures at birth were assessed separately, stratified by maternal early life SEP (dichotomised score) and Human Development Index (HDI, a country-level socio-economic indicator) in the country of origin [high HDI (Reference), n = 287 and low HDI, n = 250].

RESULTS

A strong positive association between maternal present SEP and offspring birthweight was observed if maternal early life SEP was high, but not if maternal early life SEP was low (P < 0.001 for the interaction term). This interactional effect was observed in both HDI groups. Maternal life course SEP affected offspring birthweight mainly through an effect on length and sum of skin folds. Offspring of mothers with origin from low HDI countries had smaller abdominal circumference, possibly indicating less fat-free mass, regardless of maternal life course SEP.

CONCLUSION

Our results suggest that there are transgenerational effects of maternal past socio-economic conditions on offspring size and body composition at birth that modify the associations with present socio-economic factors.

Betaine supplementation in maternal diet modulates the epigenetic regulation of hepatic gluconeogenic genes in neonatal piglets

In this study, gestational sows were fed control or betaine-supplemented diets (3 g/kg) throughout the pregnancy, and the newborn piglets were used to elucidate whether maternal dietary betaine affected offspring hepatic gluconeogenic genes through epigenetic mechanisms. Neonatal piglets born to betaine-supplemented sows had significantly higher serum and hepatic betaine contents, together with significantly greater expression of methionine metabolic enzymes in the liver. Interestingly, significantly higher serum concentrations of lactic acid and glucogenic amino acids, including serine, glutamate, methionine and histidine, were detected in the piglets born to betaine-supplemented sows, which were coincident with higher hepatic glycogen content and PEPCK1 enzyme activity, as well as greater protein expression of gluconeogenic enzymes, pyruvate carboxylase (PC), cytoplasmic phosphoenolpyruvate carboxykinase (PEPCK1), mitochondrional phosphoenolpyruvate carboxykinase (PEPCK2) and fructose-1, 6-bisphosphatase (FBP1). Moreover, maternal betaine significantly changed the methylation status of both CpGs and histones on the promoter of gluconeogenic genes. The lower PEPCK1 mRNA was associated with DNA hypermethylation and more enriched repression histone mark H3K27me3, while the up-regulated PEPCK2 and FBP1 mRNA was associated with DNA hypomethylation and more enriched activation histone mark H3K4me3. Furthermore, the expression of two miRNAs predicted to target PC and 6 miRNAs predicted to target PEPCK1 was dramatically suppressed in the liver of piglets born to betaine-supplemented sows. Our results provide the first evidence that maternal betaine supplementation affects hepatic gluconeogenic genes expression in newborn piglets through enhanced hepatic methionine metabolism and epigenetic regulations, which involve DNA and histone methylations, and possibly miRNAs-mediated post-transcriptional mechanism.

Pesticide methoxychlor promotes the epigenetic transgenerational inheritance of adult-onset disease through the female germline

Environmental compounds including fungicides, plastics, pesticides, dioxin and hydrocarbons can promote the epigenetic transgenerational inheritance of adult-onset disease in future generation progeny following ancestral exposure during the critical period of fetal gonadal sex determination. This study examined the actions of the pesticide methoxychlor to promote the epigenetic transgenerational inheritance of adult-onset disease and associated differential DNA methylation regions (i.e. epimutations) in sperm. Gestating F0 generation female rats were transiently exposed to methoxychlor during fetal gonadal development (gestation days 8 to 14) and then adult-onset disease was evaluated in adult F1 and F3 (great-grand offspring) generation progeny for control (vehicle exposed) and methoxychlor lineage offspring. There were increases in the incidence of kidney disease, ovary disease, and obesity in the methoxychlor lineage animals. In females and males the incidence of disease increased in both the F1 and the F3 generations and the incidence of multiple disease increased in the F3 generation. There was increased disease incidence in F4 generation reverse outcross (female) offspring indicating disease transmission was primarily transmitted through the female germline. Analysis of the F3 generation sperm epigenome of the methoxychlor lineage males identified differentially DNA methylated regions (DMR) termed epimutations in a genome-wide gene promoters analysis. These epimutations were found to be methoxychlor exposure specific in comparison with other exposure specific sperm epimutation signatures. Observations indicate that the pesticide methoxychlor has the potential to promote the epigenetic transgenerational inheritance of disease and the sperm epimutations appear to provide exposure specific epigenetic biomarkers for transgenerational disease and ancestral environmental exposures.