NUTRITIONAL EPIGENOMICS OF MICRONUTRIENTS IN RUMINANTS: FROM ONE-CARBON METABOLISM TO GENE REGULATION AND PHENOTYPIC PROGRAMMING- A REVIEW

Abstract

Nutritional epigenomics provides the mechanistic basis of how dietary nutrients can modulate gene expression without any permanent change in the genomic DNA sequence. In ruminants, this is particularly complicated and involves a unique sequence of events, in that nutrients are first transformed by rumen microbes, then metabolized by maternal and fetal tissues, and ultimately into molecular signals that impact chromatin configuration and gene expression. Micronutrients involved in one-carbon metabolism, antioxidant defense, mitochondrial function, and enzymatic activity may influence DNA methylation, histone modifications, chromatin structure, as well as expression of non-coding RNAs. These molecular reactions may bring about long-lasting alterations in growth, immunity, reproduction, metabolism, lactation and environmental response, particularly when nutritional exposure takes place in critical developmental stages. This review summarizes the current knowledge on folate, vitamin B12, and choline-related methyl metabolism, and the associated vitamins B2 and B6, as well as zinc, selenium, iron, copper, manganese, iodine, and related micronutrients in the context of epigenetic regulation in the ruminant. In this context, there is a particular emphasis on one-carbon metabolism, methyl groups availability, oxidative stress, mitochondria, rumen microbial activity, and developmental programming. The effects of micronutrients are known to depend on dose, chemical type, bioavailability, physiological state, tissue, sex, genotype, and the underlying nutritional status. Nutritional epigenomics thus has great potential for precision feeding and improved health of the future animal, but translation will require additional causal evidence, standardized biomarkers, longitudinal phenotyping, and careful dissociation of adaptive programming from potentially deleterious molecular perturbance.