Nutrient-gene interactions within one-carbon metabolism and effects on epigenetic regulation through dna methylation in peripheral blood mononuclear cells

Epigenetics is a field of molecular biology that copes with the study of gene function regulation without variations in DNA structure or nucleotide sequences. Among the main epigenetic phenomema in eukaryotic cells there are DNA methylation and post-traslational mechanisms among which the major are histone methylation and acetylation. Epigenetic changes are potentially reversible phenomena that are controlled also by nutritional factors as the methyl-donors involved in the folate cycle. Plasma levels of B vitamins, among which “in primis” plasma folate concentrations, are implicated in epigenetic modulation so that it can be hypothesized that they may affect the modulation of gene expression through epigenetic mechanisms. Epigenetic modifications represent one of the earliest events in the genesis of some complex pathologies, therefore the study of the interaction between epigenetics and nutritional status is of great interest either to define the physiopathological mechanisms of development of some illnesses, and for possible personalized strategies of prevention. The present work has been articulated, at first, on the analysis of gene-nutritional interaction mechanisms within the folate cycle through the study of polymorphisms of enzymes involved in the metabolism of methyl-group donors; the aim was to study their possible role on the modulation of genomic DNA methylation in relationship to different plasma levels of idrosoluble B vitamins. In this regard, the most important functional polymorfisms known on the genes of one-carbon metabolism and their relationship with methylation status of polymorphonuclear cells DNA have been analyzed from a cohort of around 800 subjects within a clinical study, underlining the role of the key folate-related enzymes in the modulation of DNA methylation. Besides the function of genomic DNA methylation, the methylation status at specific sites has been also approached with the specific intent of considering a possible interrelationship between the role of promoter methylation and the co-presence of functional polymorphisms in the same genic site for a gene for which a precise functional effect is well-known. To address this issue the promoter region of coagulation factor VII gene was evaluated for both genetic and epigenetic modifications as a possible model of genetic-epigenetic interaction in the modulation of gene product regulation. The results showed the key importance of genetic-epigenetic interactions, so far unknowm, in modulating gene-expression at promoter gene sites. The role of other vitamins involved in one-carbon metabolism in major chronic diseases, and specifically the emerging role of B6 vitamin, have been also studied. Furthermore, a clinical study is now in progress to evaluate the function of gene-specific methylation in liver tissue where most of the folate cycle functions take place. The aim of this project is the evaluation of both genome-wide and gene-specific methylation status in the liver in comparison to that observed in peripheral blood mononuclear cells DNA to define whether methylation status of peripheral blood DNA may be regarded as a good systemic biomarker for this epigenetic feature of DNA in relation to B vitamins nutritional status in cancer disease. Results from this study may help to define possible functional markers of gene-nutrients interactions with effects on epigenetic modulation for future preventive or therapeutic strategies. With that purpose, a novel high-throughput array-based technique for the detection of gene-specific methylation at promoter sites has been optimized in our laboratory.