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

Dietary flavonoids prevent diabetes through epigenetic regulation: advance and challenge

The pathophysiology of diabetes has been studied extensively in various countries, but effective prevention and treatment methods are still insufficient. In recent years, epigenetics has received increasing attention from researchers in exploring the etiology and treatment of diabetes. DNA methylation, histone modifications, and non-coding RNAs play critical roles in the occurrence, maintenance, and progression of diabetes and its complications. Therefore, preventing or reversing the epigenetic alterations that occur during the development of diabetes may reduce the individual and societal burden of the disease. Dietary flavonoids serve as natural epigenetic modulators for the discovery of biomarkers for diabetes prevention and the development of alternative therapies. However, there is limited knowledge about the potential beneficial effects of flavonoids on the epigenetics of diabetes. In this review, the multidimensional epigenetic effects of different flavonoid subtypes in diabetes were summarized. Furthermore, it was discussed that parental flavonoid diets might reduce diabetes incidence in offspring, which represent a promising opportunity to prevent diabetes in the future. Future work will depend on exploring anti-diabetic effects of different flavonoids with different epigenetic regulation mechanisms and clinical trials.Highlights• "Epigenetic therapy" could reduce the burden of diabetic patients• "Epigenetic diet" ameliorates diabetes• Targeting epigenetic regulations by dietary flavonoids in the diabetes prevention• Dietary flavonoids prevent diabetes via transgenerational epigenetic inheritance.

Paternal high-fat diet altered SETD2 gene methylation in sperm of F0 and F1 mice

Paternal high-fat diet (HFD) can alter the epigenetics of sperm DNA, resulting in the transmission of obesity-related traits to the offspring. Previous studies have mainly focused on the HFD-induced changes in DNA methylation of imprinted genes, overlooking the potential involvement of non-imprinted genes in this process. SETD2, an important epigenetically-regulated gene known for its response to environmental stress, remains poorly understood in the context of high-fat diet-induced epigenetic changes. Here we examined the effect of obesity from a HFD on paternal SETD2 expression and methylation in sperm, and embryos at the blastocyst stage and during subsequent development, to determine the alteration of SETD2 in paternal intergenerational and transgenerational inheritance. The result showed that mice fed with HFD for two months had significantly increased SETD2 expression in testis and sperm. The paternal HFD significantly altered the DNA methylation level with 20 of the 26 CpG sites being changed in sperm from F0 mice. Paternal high-fat diet increased apoptotic index and decreased total cell number of blastocysts, which were closely correlated with DNA methylation level of sperm. Out of the 26 CpG sites, we also found three CpG sites that were significantly changed in the sperm from F1 mice, which meant that the methylation changes at these three CpG sites were maintained.In conclusion, we found that paternal exposure to an HFD disrupted the methylation pattern of SETD2 in the sperm of F0 mice and resulted in perturbed SETD2 expression. Furthermore, the paternal high-fat diet influenced embryo apoptosis and development, possibly through the SETD2 pathway. The altered methylation of SETD2 in sperm induced by paternal HFD partially persisted in the sperm of the F1 generation, highlighting the role of SETD2 as an epigenetic carrier for paternal intergenerational and transgenerational inheritance.

Convergent actions of stress and stimulants via epigenetic regulation of neural circuitry

The dorsal striatum integrates prior and current information to guide appropriate decision-making. Chronic stress and stimulant exposure interferes with decision-making, and can confer similar cognitive and behavioral inflexibilities. This review examines the literature on acute and chronic regulation of the epigenome by stress and stimulants. Recent evidence suggests that exposures to stress and stimulants share similarities in the manners in which they regulate the dorsal striatum epigenome through DNA methylation, transposable element activity, and histone post-translational modifications. These findings suggest that chronic stress and stimulant exposure leads to the accumulation of epigenetic modifications that impair immediate and future neuron function and activity. Such epigenetic mechanisms represent potential therapeutic targets for ameliorating convergent symptoms of stress and addiction.

Non-coding RNAs and chromatin: key epigenetic factors from spermatogenesis to transgenerational inheritance

Cellular fate and gene expression patterns are modulated by different epigenetic factors including non-coding RNAs (ncRNAs) and chromatin organization. Both factors are dynamic throughout male germ cell differentiation on the seminiferous tubule, despite the transcriptional inactivation in the last stages of spermatogenesis. Sperm maturation during the caput-to-cauda transit on the epididymis involves changes in chromatin organization and the soma-to-germ line transference of ncRNAs that are essential to obtain a functional sperm for fertilization and embryo development. Here, the male environment (diseases, drugs, mental stress) is crucial to modulate these epigenetic factors throughout sperm maturation, affecting the corresponding offspring. Paternal transgenerational inheritance has been directly related to sperm epigenetic changes, most of them associated with variations in the ncRNA content and chromatin marks. Our aim is to give an overview about how epigenetics, focused on ncRNAs and chromatin, is pivotal to understand spermatogenesis and sperm maturation, and how the male environment impacts the sperm epigenome modulating the offspring gene expression pattern.

Mapping the past, present and future research landscape of paternal effects

BACKGROUND

Although in all sexually reproducing organisms an individual has a mother and a father, non-genetic inheritance has been predominantly studied in mothers. Paternal effects have been far less frequently studied, until recently. In the last 5 years, research on environmentally induced paternal effects has grown rapidly in the number of publications and diversity of topics. Here, we provide an overview of this field using synthesis of evidence (systematic map) and influence (bibliometric analyses).

RESULTS

We find that motivations for studies into paternal effects are diverse. For example, from the ecological and evolutionary perspective, paternal effects are of interest as facilitators of response to environmental change and mediators of extended heredity. Medical researchers track how paternal pre-fertilization exposures to factors, such as diet or trauma, influence offspring health. Toxicologists look at the effects of toxins. We compare how these three research guilds design experiments in relation to objects of their studies: fathers, mothers and offspring. We highlight examples of research gaps, which, in turn, lead to future avenues of research.

CONCLUSIONS

The literature on paternal effects is large and disparate. Our study helps in fostering connections between areas of knowledge that develop in parallel, but which could benefit from the lateral transfer of concepts and methods.

DNA Methylation Heterogeneity Induced by Collaborations Between Enhancers

During mammalian embryo development, reprogramming of DNA methylation plays important roles in the erasure of parental epigenetic memory and the establishment of naive pluripotent cells. Multiple enzymes that regulate the processes of methylation and demethylation work together to shape the pattern of genome-scale DNA methylation and guide the process of cell differentiation. Recent availability of methylome information from single-cell whole genome bisulfite sequencing (scBS-seq) provides an opportunity to study DNA methylation dynamics in the whole genome in individual cells, which reveal the heterogeneous methylation distributions of enhancers in embryo stem cells. In this study, we developed a computational model of enhancer methylation inheritance to study the dynamics of genome-scale DNA methylation reprogramming during exit from pluripotency. The model enables us to track genome-scale DNA methylation reprogramming at single-cell level during the embryo development process and reproduce the DNA methylation heterogeneity reported by scBS-seq. Model simulations show that DNA methylation heterogeneity is an intrinsic property driven by cell division along the development process, and the collaboration between neighboring enhancers is required for heterogeneous methylation. Our study suggests that the mechanism of genome-scale oscillation might not be necessary for the DNA methylation heterogeneity during exit from pluripotency.

Epigenetics and human reproduction: the primary prevention of the noncommunicable diseases

Epigenetic regulation of gene expression plays a key role in affecting human health and diseases with particular regard to human reproduction. The major concern in this field is represented by the epigenetic modifications in the embryo and the increased risk of long-life disorders induced by the use of assisted reproduction techniques, able to affect the epigenetic assessment in the first steps of embryo development. In this review, we analyze the correlation between epigenetic modifications and human reproduction, suggesting that the reversibility of the epigenetic processes could represent a novel resource for the treatment of the couple's infertility and that parental lifestyle in periconceptional period could be considered as an important issue of primary prevention.