Paternal high-fat diet alters triglyceride metabolism-related gene expression in liver and white adipose tissue of male mouse offspring

Obesity is a major public health problem, and its prevalence is progressively increasing worldwide. In addition, accumulating evidence suggests that diverse nutritional and metabolic disturbances including obesity can be transmitted from parents to offspring via transgenerational epigenetic inheritance. The previous reports have shown that paternal obesity has profound impacts on the development and metabolic health of their progeny. However, little information is available concerning the effects of paternal high-fat diet (HFD) exposure on triglyceride metabolism in the offspring. Therefore, we investigated the effects of paternal HFD on triglyceride metabolism and related gene expression in male mouse offspring. We found that paternal HFD exposure significantly increased the body weight, liver and epididymal white adipose tissue (eWAT) weights, and liver triglyceride content in male offspring, despite consuming control diet. In addition, paternal HFD exposure had induced changes in the mRNA expression of genes involved in lipid and triglyceride metabolism in the liver and eWAT. These findings indicate transgenerational inheritance from the paternal metabolic disturbance of triglyceride and support the effects of paternal lifestyle choices on offspring development and health later in life.     

Paternal B Vitamin Intake Is a Determinant of Growth,Hepatic Lipid Metabolism and Intestinal Tumor Volume in Female Apc1638N Mouse Offspring

Background

The importance of maternal nutrition to offspring health and risk of disease is well established. Emerging evidence suggests paternal diet may affect offspring health as well.

Objective

In the current study we sought to determine whether modulating pre-conception paternal B vitamin intake alters intestinal tumor formation in offspring. Additionally, we sought to identify potential mechanisms for the observed weight differential among offspring by profiling hepatic gene expression and lipid content.

Methods

Male Apc^1638N mice (prone to intestinal tumor formation) were fed diets containing replete (control, CTRL), mildly deficient (DEF), or supplemental (SUPP) quantities of vitamins B₂, B₆, B₁₂, and folate for 8 weeks before mating with control-fed wild type females. Wild type offspring were euthanized at weaning and hepatic gene expression profiled. Apc^1638N offspring were fed a replete diet and euthanized at 28 weeks of age to assess tumor burden.

Results

No differences in intestinal tumor incidence or burden were found between male Apc^1638N offspring of different paternal diet groups. Although in female Apc^1638N offspring there were no differences in tumor incidence or multiplicity, a stepwise increase in tumor volume with increasing paternal B vitamin intake was observed. Interestingly, female offspring of SUPP and DEF fathers had a significantly lower body weight than those of CTRL fed fathers. Moreover, hepatic trigylcerides and cholesterol were elevated 3-fold in adult female offspring of SUPP fathers. Weanling offspring of the same fathers displayed altered expression of several key lipid-metabolism genes. Hundreds of differentially methylated regions were identified in the paternal sperm in response to DEF and SUPP diets. Aside from a few genes including Igf2, there was a striking lack of overlap between these genes differentially methylated in sperm and differentially expressed in offspring.

Conclusions

In this animal model, modulation of paternal B vitamin intake prior to mating alters offspring weight gain, lipid metabolism and tumor growth in a sex-specific fashion. These results highlight the need to better define how paternal nutrition affects the health of offspring.     

Enriched Environment-induced Maternal Weight Loss Reprograms Metabolic Gene Expression in Mouse Offspring

The global prevalence of weight loss is increasing, especially in young women. However, the extent and mechanisms by which maternal weight loss affects the offspring is still poorly understood. Here, using an enriched environment (EE)-induced weight loss model, we show that maternal weight loss improves general health and reprograms metabolic gene expression in mouse offspring, and the epigenetic alterations can be inherited for at least two generations. EE in mothers induced weight loss and its associated physiological and metabolic changes such as decreased adiposity and improved glucose tolerance and insulin sensitivity. Relative to controls, their offspring exhibited improved general health such as reduced fat accumulation, decreased plasma and hepatic lipid levels, and improved glucose tolerance and insulin sensitivity. Maternal weight loss altered gene expression patterns in the liver of offspring with coherent down-regulation of genes involved in lipid and cholesterol biosynthesis. Epigenomic profiling of offspring livers revealed numerous changes in cytosine methylation depending on maternal weight loss, including reproducible changes in promoter methylation over several key lipid biosynthesis genes, correlated with their expression patterns. Embryo transfer studies indicated that oocyte alteration in response to maternal metabolic conditions is a strong factor in determining metabolic and epigenetic changes in offspring. Several important lipid metabolism-related genes have been identified to partially inherit methylated alleles from oocytes. Our study reveals a molecular and mechanistic basis of how maternal lifestyle modification affects metabolic changes in the offspring.     

Investigations on transgenerational epigenetic response down the male line in F2 pigs

We investigated the nutritional effects on carcass traits, gene expression and DNA methylation in a three generation Large White pig feeding experiment. A group of experimental (E) F0 boars were fed a standard diet supplemented with high amounts of methylating micronutrients whereas a control group (C) of F0 boars received a standard diet. These differentially fed F0 boars sired F1 boars which then sired 60 F2 pigs. Carcass traits were compared between 36 F2 descendants of E F0 boars and 24 F2 descendants of C F0 boars. The two F2 offspring groups differed with respect to backfat percentage (P = 0.03) and tended to differ with respect to adipose tissue (P = 0.09), fat thickness at the 10^th rib (P = 0.08) and at the croup (P = 0.09) as well as percentages of shoulder (P = 0.07). Offspring from the experimental F0 boars had a higher percentage of shoulder and were leaner compared to the control group. Gene expression profiles showed significant twofold differences in mRNA level between 8 C F2 offspring and 8 E F2 offspring for 79, 64 and 53 genes for muscle, liver and kidney RNA, respectively. We found that in liver and muscle respective pathways of lipid metabolism and metabolic pathway were over-represented for the differentially expressed genes between these groups. A DNA methylation analysis in promoters of differentially expressed genes indicated a significant difference in DNA methylation at the IYD gene. If these responses on carcass traits, gene expression and DNA methylation withstand verification and can indeed be attributed to transgenerational epigenetic inheritance, it would open up pioneering application in pork production and would have implications for human health.     

Transgenerational effects of stress exposure on offspring phenotypes in apomictic dandelion

Heritable epigenetic modulation of gene expression is a candidate mechanism to explain parental environmental effects on offspring phenotypes, but current evidence for environment-induced epigenetic changes that persist in offspring generations is scarce. In apomictic dandelions, exposure to various stresses was previously shown to heritably alter DNA methylation patterns. In this study we explore whether these induced changes are accompanied by heritable effects on offspring phenotypes. We observed effects of parental jasmonic acid treatment on offspring specific leaf area and on offspring interaction with a generalist herbivore; and of parental nutrient stress on offspring root-shoot biomass ratio, tissue P-content and leaf morphology. Some of the effects appeared to enhance offspring ability to cope with the same stresses that their parents experienced. Effects differed between apomictic genotypes and were not always consistently observed between different experiments, especially in the case of parental nutrient stress. While this context-dependency of the effects remains to be further clarified, the total set of results provides evidence for the existence of transgenerational effects in apomictic dandelions. Zebularine treatment affected the within-generation response to nutrient stress, pointing at a role of DNA methylation in phenotypic plasticity to nutrient environments. This study shows that stress exposure in apomictic dandelions can cause transgenerational phenotypic effects, in addition to previously demonstrated transgenerational DNA methylation effects.     

A paternal environmental legacy: Evidence for epigenetic inheritance through the male germ line

Literature on maternal exposures and the risk of epigenetic changes or diseases in the offspring is growing. Paternal contributions are often not considered. However, some animal and epidemiologic studies on various contaminants, nutrition, and lifestyle‐related conditions suggest a paternal influence on the offspring's future health. The phenotypic outcomes may have been attributed to DNA damage or mutations, but increasing evidence shows that the inheritance of environmentally induced functional changes of the genome, and related disorders, are (also) driven by epigenetic components. In this essay we suggest the existence of epigenetic windows of susceptibility to environmental insults during sperm development. Changes in DNA methylation, histone modification, and non‐coding RNAs are viable mechanistic candidates for a non‐genetic transfer of paternal environmental information, from maturing germ cell to zygote. Inclusion of paternal factors in future research will ultimately improve the understanding of transgenerational epigenetic plasticity and health‐related effects in future generations.     

Paternal epigenetic effects of population density on locust phase‐related characteristics associated with heat‐shock protein expression

Many species exhibit transgenerational plasticity by which environmental cues experienced by either parent can be transmitted to their offspring, resulting in phenotypic variants in offspring to match ancestral environments. However, the manner by which paternal experiences affect offspring plasticity through epigenetic inheritance in animals generally remains unclear. In this study, we examined the transgenerational effects of population density on phase‐related traits in the migratory locust Locusta migratoria. Using an experimental design that explicitly controls genetic background, we found that the effects of crowd or isolation rearing on phase plasticity could be inherited to the offspring. The isolation of gregarious locusts resulted in reduced weight in offspring eggs and altered morphometric traits in hatchlings, whereas crowding of solitarious locusts exhibited opposite effects. The consequences of density changes were transmitted by both maternal and paternal inheritance, although the expression of paternal effects was not as pronounced as that of maternal effects. Prominent expression of heat‐shock proteins (Hsps), such as Hsp90, Hsp70 and Hsp20.6, could be triggered by density changes. Hsps were significantly upregulated upon crowding but downregulated upon isolation. The variation in parental Hsp expression was also transmitted to the offspring, in which the pattern of inheritance was consistent with that of phase characteristics. These results revealed a paternal effect on phase polyphenism and Hsp expression induced by population density, and defined a model system that could be used to study the paternal epigenetic inheritance of environmental changes.     

Paternal Effects on Offspring Fitness Reflect Father’s Social Environment

In many species, males influence phenotypic traits in their offspring through non-genetic paternal effects. Such effects can represent a form of paternal investment, and males may benefit by adjusting the effects depending on environmental parameters, such as operational sex ratio, so as to maximize offspring fitness. In the neriid fly Telostylinus angusticollis, fathers reared on a nutrient-rich larval diet produce larger offspring, independent of the rearing environment of the offspring. Here we asked whether this paternal effect was influenced by the social environment to which fathers were exposed. We found significant interactions of the effects of paternal larval diet quality and social environment (same-sex vs. mixed-sex groups) on offspring fitness-related traits. Fathers reared on a nutrient-rich diet produced larger male offspring when housed in mixed-sex groups. However, fathers reared on a nutrient-rich diet produced more viable offspring (or more viable sperm) when housed in same-sex groups prior to mating. These results suggest that fitness-enhancing paternal effects can trade off, consistent with parental investment theory on the offspring size-number trade-off, which suggests that these traits represent alternative investment options and parents are selected to optimize the balance based on a range of environmental variables. This is the first study to show that males can facultatively modulate paternal effects based on the social environment.     

母代高脂饮食诱导子代在小鼠生命早期出现糖脂代谢紊乱且具有雄性易感性

目的：探讨孕期和哺乳期的高脂饮食能否导致子代在生命早期出现糖脂代谢紊乱。方法成年雌性C57BL/6J小鼠与正常饮食雄性小鼠进行交配,孕鼠随机分为高脂饮食组和正常饮食组,在孕期和哺乳期喂养高脂饲料或正常饲料,至交配后第一代鼠断乳时（3周龄）观察其糖脂代谢相关性指标以及肝脏病理表现。结果较正常饮食组子鼠相比,高脂饮食子鼠出生体重更低（ P＜0.05）。在断乳时,高脂饮食组雄性子鼠体重较重（ P ＝0.038）,腹腔糖耐量实验30 min和60 min血糖明显升高（P值分别为＜0.001和＜0.01）,糖耐量曲线下面积较大（P＝0.0016）,HOMA-IR值较大（P＜0.05）,雌性子鼠腹腔糖耐量实验在30 min血糖高于正常组（P＜0.01）,而糖耐量曲线下面积和HOMA-IR值在两组之间无明显统计学意义。雄性和雌性子代小鼠空腹胆固醇水平高脂饮食组均高于正常饮食组（ P值分别为＜0.0001和0.0004）,而两组雄性和雌性子代小鼠空腹胰岛素和甘油三酯水平差异均无显著性（ P均＞0.05）。另外,在断乳时高脂饮食子鼠出现肝脏脂肪变性,雌性和雄性子鼠无明显差异。结论母鼠孕期和哺乳期高脂饮食能够诱导子代在生命早期就能出现糖脂代谢紊乱并且雄性子鼠更易出现肥胖、糖耐量异常、胰岛素抵抗。     

Increased transgenerational epigenetic variation,but not predictable epigenetic variants,after environmental exposure in two apomictic dandelion lineages

DNA methylation is one of the mechanisms underlying epigenetic modifications. DNA methylations can be environmentally induced and such induced modifications can at times be transmitted to successive generations. However, it remains speculative how common such environmentally induced transgenerational DNA methylation changes are and if they persist for more than one offspring generation. We exposed multiple accessions of two different apomictic dandelion lineages of the Taraxacum officinale group (Taraxacum alatum and T. hemicyclum) to drought and salicylic acid (SA) treatment. Using methylation‐sensitive amplified fragment length polymorphism markers (MS‐AFLPs) we screened anonymous methylation changes at CCGG restriction sites throughout the genome after stress treatments and assessed the heritability of induced changes for two subsequent unexposed offspring generations. Irrespective of the initial stress treatment, a clear buildup of heritable DNA methylation variation was observed across three generations, indicating a considerable background rate of heritable epimutations. Less evidence was detected for environmental effects. Drought stress showed some evidence for accession‐specific methylation changes, but only in the exposed generation and not in their offspring. By contrast, SA treatment caused an increased rate of methylation change in offspring of treated plants. These changes were seemingly undirected resulting in increased transgenerational epigenetic variation between offspring individuals, but not in predictable epigenetic variants. While the functional consequences of these MS‐AFLP‐detected DNA methylation changes remain to be demonstrated, our study shows that (1) stress‐induced transgenerational DNA methylation modification in dandelions is genotype and context‐specific; and (2) inherited environmental DNA methylation effects are mostly undirected and not targeted to specific loci.     

Transgenerational inheritance of chronic adolescent stress: Effects of stress response and the amygdala transcriptome

Adolescent stress can impact health and well‐being not only during adulthood of the exposed individual but even in future generations. To investigate the molecular mechanisms underlying these long‐term effects, we exposed adolescent males to stress and measured anxiety behaviors and gene expression in the amygdala—a critical region in the control of emotional states—in their progeny for two generations, offspring and grandoffspring. Male C57BL/6 mice underwent chronic unpredictable stress (CUS) for 2 weeks during adolescence and were used to produce two generations of offspring. Male and female offspring and grandoffspring were tested in behavioral assays to measure affective behavior and stress reactivity. Remarkably, transgenerational inheritance of paternal stress exposure produced a protective phenotype in the male, but not the female lineage. RNA‐seq analysis of the amygdala from male offspring and grandoffspring identified differentially expressed genes (DEGs) in mice derived from fathers exposed to CUS. The DEGSs clustered into numerous pathways, and the “notch signaling” pathway was the most significantly altered in male grandoffspring. Therefore, we show that paternal stress exposure impacts future generations which manifest in behavioral changes and molecular adaptations.     

Paternal age affects offspring via an epigenetic mechanism involving REST/NRSF

Advanced paternal age can have deleterious effects on various traits in the next generation. Here, we establish a paternal‐aging model in mice to understand the molecular mechanisms of transgenerational epigenetics. Whole‐genome target DNA methylome analyses of sperm from aged mice reveal more hypo‐methylated genomic regions enriched in REST/NRSF binding motifs. Gene set enrichment analyses also reveal the upregulation of REST/NRSF target genes in the forebrain of embryos from aged fathers. Offspring derived from young mice administrated with a DNA de‐methylation drug phenocopy the abnormal vocal communication of pups derived from aged fathers. In conclusion, hypo‐methylation of sperm DNA can be a key molecular feature modulating neurodevelopmental programs in offspring by causing fluctuations in the expression of REST/NRSF target genes.     

Paternal high-fat diet and exercise regulate sperm miRNA and histone methylation to modify placental inflammation,nutrient transporter mRNA expression and fetal weight in a sex-dependent manner

We previously have shown that male offspring (F1) of fathers (F0) fed a high-fat (HF) diet and that exercised had greater skeletal muscle insulin signaling and reduced type 2 diabetes mellitus (T2DM) risk compared to fathers fed HF diet and that remained sedentary. The current study extends this work by hypothesizing that F0 HF diet and exercise regulate F1 T2DM risk by alterations in placental tissue growth via changes in sperm miRNA expression. To test these hypotheses, 3-week-old male C57BL/6 mice were fed a normal-fat diet (16% fat) or an HF diet (45% fat) and assigned to either voluntary wheel running exercise or cage activity for 3 months. Results showed that F0 sperm miRNA 193b expression was decreased while miRNA 204 was increased by paternal exercise. Protein expression of dimethylated histone 3 lysine 9 was decreased with F0 HF diet. Placental and fetal tissue weights were decreased by F0 HF diet in F1 males. Placental interleukin-1β and tumor necrosis factor (TNF)-α mRNA expression was reduced by paternal exercise, while nutrient transporter mRNA expression was decreased by paternal HF diet only in the placentae of F1 females. Treatment of primary placental cell with miRNA 193b inhibited TNF-α mRNA expression, and treatment of TNF-α decreased SLC38a2 mRNA expression. Moreover, paternal exercise increased body weight at weaning in a female offspring. These results demonstrate that placental tissue weight, placental nutrient transporter gene expression and fetal weights are altered by paternal exercise, while placental inflammatory gene expression is influenced by paternal exercise in offspring in a sex-specific manner.     

Transgenerational effects of parental larval diet on offspring development time, adult body size and pathogen resistance in Drosophila melanogaster

Environmental conditions experienced by parents are increasingly recognized to affect offspring performance. We set out to investigate the effect of parental larval diet on offspring development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. Flies for the parental generation were raised on either poor or standard diet and then mated in the four possible sex-by-parental diet crosses. Females that were raised on poor food produced larger offspring than females that were raised on standard food. Furthermore, male progeny sired by fathers that were raised on poor food were larger than male progeny sired by males raised on standard food. Development times were shortest for offspring whose one parent (mother or the father) was raised on standard and the other parent on poor food and longest for offspring whose parents both were raised on poor food. No evidence for transgenerational effects of parental diet on offspring disease resistance was found. Although paternal effects have been previously demonstrated in D. melanogaster, no earlier studies have investigated male-mediated transgenerational effects of diet in this species. The results highlight the importance of not only considering the relative contribution each parental sex has on progeny performance but also the combined effects that the two sexes may have on offspring performance.     

Paternal exercise protects mouse offspring from high-fat-diet-induced type 2 diabetes risk by increasing skeletal muscle insulin signaling

Paternal obesity increases, while paternal exercise decreases, offspring obesity and type 2 diabetes (T2D) risk; however, no studies have determined whether a paternal high-fat (HF) diet and exercise interact to alter offspring body weight (BW), adiposity and T2D risk. Three-week-old male C57BL/6 mice were fed a normal-fat (NF) diet (16% fat) or an HF diet (45% fat) and assigned to either voluntary wheel running exercise or cage activity for 3 months prior to mating with NF-diet-fed dams. After weaning, male offspring were fed an NF or HF diet for an additional 3 months. F1 male mice whose fathers ate an HF diet had decreased % body fat accompanied by decreased gene expression of beige adipocyte marker FGF21. However, paternal HF-diet-induced reductions in F1 offspring % body fat normalized but did not reduce T2D risk. Exercise was protective against paternal HF-diet-induced insulin resistance by increasing the expression of insulin signaling (GLUT4, IRS1 and PI3K) markers in skeletal muscle resulting in normal T2D risk. When fathers were fed an HF diet and exercised, a postnatal HF diet increased beiging (PPARγ). Thus, these findings show that increases in T2D risk in male offspring when the father consumes an HF diet can be normalized when the father also exercises preconception and that this protection may occur by increases in insulin signaling potential within offspring skeletal muscle. Future studies should further determine the physiological mechanism(s) underlying the beneficial effects of exercise through the paternal lineage.     

Adaptive responses by mouse fetus to a maternal HLE diet by downregulating SREBP1: a microarray- and bio-analytic-based study

Maternal diet has long been recognized as a significant factor affecting offspring development and health, but the target genes affected by a maternal high-lipid diet are currently unknown. In this study, the gene expression profile of neonatal mouse liver was analyzed using gene chips to identify genes with significant up- or downregulated expression levels due to maternal high-fat diet during gestation. Real-time PCR and Western blotting were used to measure key genes selected using microarray. Serum lipid, glucose, and insulin levels in adult offspring from dams fed with chow or a high-lipid diet were measured using commercial kits. Results indicate that the expression of genes involved in cholesterol and fatty acid synthesis were significantly inhibited, while the expression of genes involved in glycolysis were significantly decreased by maternal high-lipid diet during gestation. SREBP1 might be the key gene regulating genes involved in fatty acid, glucose, and cholesterol metabolism in response to a maternal high-fat diet.