Epigenetic changes in gene expression: focus on "The liver X-receptor gene promoter is hypermethylated in a mouse model of prenatal protein restriction"

DNA methylation as a regulator of intestinal gene expression

The intestinal tract is the entry gate for nutrients and symbiotic organisms, being in constant contact with external environment. DNA methylation is one of the keys to how environmental conditions, diet and nutritional status included, shape functionality in the gut and systemically. This review aims to summarise findings on the importance of methylation to gut development, differentiation and function. Evidence to date on how external factors such as diet, dietary supplements, nutritional status and microbiota modifications modulate intestinal function through DNA methylation is also presented.

Perinatal high methyl donor alters gene expression in IGF system in male offspring without altering DNA methylation

Aim:

To investigate the effect of a protein restriction and a supplementation with methyl donor nutrients during fetal and early postnatal life on the expression and epigenetic state of imprinted genes from the IGF system.

Materials & methods:

Pregnant female rats were fed a protein-restricted diet supplemented or not with methyl donor.

Results:

Gene expression of the Igf2, H19, Igf1, Igf2r and Plagl1 genes in the liver of male offspring at birth and weaning was strongly influenced by maternal diet. Whereas the methylation profiles of the Igf2, H19 and Igf2r genes were remarkably stable, DNA methylation of Plagl1 promoter was slightly modified.

Conclusion:

DNA methylation of most, but not all, imprinted gene regulatory regions was resistant to methyl group nutritional supply.

Fetal environment influences fetal growth and may confer a risk to develop metabolic diseases, possibly through alterations in the epigenetic state of the genome. Imprinted genes constitute a special class of genes that are crucial for the control of fetal and postnatal growth and are closely associated with energy metabolism. In addition, these genes are finely regulated by epigenetic mechanisms that are themselves influenced by environmental factors. This study showed that methyl donor nutrients in maternal diet strongly influenced the expression level of imprinted genes in the liver of rat offspring, despite a mild effect on epigenetic regulation.

Regulation of early human growth: impact on long-term health

Growth and development are central characteristics of childhood. Deviations from normal growth can indicate serious health challenges. The adverse impact of early growth faltering and malnutrition on later health has long been known. In contrast, the impact of rapid early weight and body fat gain on programming of later disease risk have only recently received increased attention. Numerous observational studies related diet in early childhood and rapid early growth to the risk of later obesity and associated disorders. Causality was confirmed in a large, double-blind randomised trial testing the 'Early Protein Hypothesis'. In this trial we found that attenuation of protein supply in infancy normalized early growth and markedly reduced obesity prevalence in early school age. These results indicate the need to describe and analyse growth patterns and their regulation through diet in more detail and to characterize the underlying metabolic and epigenetic mechanisms, given the potential major relevance for public health and policy. Better understanding of growth patterns and their regulation could have major benefits for the promotion of public health, consumer-orientated nutrition recommendations, and the development of improved food products for specific target populations.

Sugared water consumption by adult offspring of mothers fed a protein-restricted diet during pregnancy results in increased offspring adiposity: the second hit effect

Poor maternal nutrition predisposes offspring to metabolic disease. This predisposition is modified by various postnatal factors. We hypothesised that coupled to the initial effects of developmental programming due to a maternal low-protein diet, a second hit resulting from increased offspring postnatal sugar consumption would lead to additional changes in metabolism and adipose tissue function. The objective of the present study was to determine the effects of sugared water consumption (5% sucrose in the drinking-water) on adult offspring adiposity as a 'second hit' following exposure to maternal protein restriction during pregnancy. We studied four offspring groups: (1) offspring of mothers fed the control diet (C); (2) offspring of mothers fed the restricted protein diet (R); (3) offspring of control mothers that drank sugared water (C-S); (4) offspring of restricted mothers that drank sugared water (R-S). Maternal diet in pregnancy was considered the first factor and sugared water consumption as the second factor - the second hit. Body weight and total energy consumption, before and after sugared water consumption, were similar in all the groups. Sugared water consumption increased TAG, insulin and cholesterol concentrations in both the sexes of the C-S and R-S offspring. Sugared water consumption increased leptin concentrations in the R-S females and males but not in the R offspring. There was also an interaction between sugared water and maternal diet in males. Sugared water consumption increased adipocyte size and adiposity index in both females and males, but the interaction with maternal diet was observed only in females. Adiposity index and plasma leptin concentrations were positively correlated in both the sexes. The present study shows that a second hit during adulthood can amplify the effects of higher adiposity arising due to poor maternal pregnancy diet in an offspring sex dependent fashion.