Epigenetics

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton and Chelsea Mclene  

Introduction

Epigenetics is the study of heritable and stable changes in gene expression that occur through adjustments in the chromosome rather than in the DNA sequence. They do not directly altering the DNA sequence rather epigenetic mechanisms are able to regulate gene expression through chemical modifications of DNA bases and changes to the chromosomal superstructure in which DNA is packaged.

Epigenetics affects how genes are read by cells, and subsequently whether the cells should produce relevant proteins, in effect controlling our genes. e.g determining a cell’s specialization (e.g., skin cell, blood cell, hair cell, liver cells, etc.) as a fetus develops into a baby through gene expression (active) or silencing (dormant); and also through nurture with environmental stimuli having the ability to cause genes to be turned off or turned on.

The different combinations of genes that are turned on or off is what makes each one of us unique. Eg if we have brown or black hair, how sociable you are, how a oyster tastes to us. Additionally there have been indications that some epigenetic changes can even be inherited.

Epigenetic mechanisms are affected by several factors and processes including development in utero and in childhood, environmental chemicals, drugs and pharmaceuticals, aging, and diet. DNA methylation is what occurs when methyl groups, an epigenetic factor found in some dietary sources, can tag DNA and activate or repress genes. Histones are proteins around which DNA can wind for compaction and gene regulation. Histone modification occurs when the binding of epigenetic factors to histone “tails” alters the extent to which DNA is wrapped around histones and the availability of genes in the DNA to be activated. All of these factors and processes can have an effect on people’s health and influence their health possibly resulting in cancer, autoimmune disease, mental disorders, or diabetes among other illnesses.

Epigenetics began over 60 years ago. During the 1970s it started becoming more prominent with the arrival of molecular biology and during the last 10–15 years, has emerged as a stand-alone discipline complementary to genetics.

Epigenetics and Exercise Effects

It is now established that exercise is an important “medicine”. Examples of the role exercise can play in epigenetics include:

Lifelong physical activity is associated with promoter hypomethylation of genes involved in metabolism, myogenesis, contractile properties and oxidative stress resistance in aged human skeletal muscle.

Exercise is able to attenuate or reverse some of the high‐fat diet associated methylation patterns. Many of the genes found to be differentially methylated are implicated in metabolic functions, such as regulation of oxidative metabolism and glucose transportation, which have obvious significance for offspring.

Exercise has also been shown to impact cognitive development, as hippocampal DNA methylation was found to be lower in exercise‐offspring. This shows that epigenetic intergenerational outcomes appear to be consistent with epigenetic alterations in people who regularly exercise.

Studies show that acute and chronic exercise interventions induce a number of epigenetic modifications within the person exercising. In human skeletal muscle, both whole genome methylation and methylation of promoter regions of key metabolic genes decreased after completing a single‐session of cycling at 80% of VO2peak. Similarly, three months of regular single‐knee extension exercise showed genome‐wide DNA methylation alterations that were not observed in the untrained leg. Promoter regions are regions of DNA where transcription of a gene is initiated.

Lifestyle Factors

In utero epigenetic changes are very sensitive as the epigenetic profile of the foetus as it is forming and developing. Teratogens like cigarette smoke, alcohol, and specific minerals having the ability to induce utero epigenetic changes.

As people age, the most significant influence on the epigenome is the environment. These include diet, smoking, physical activity and psychological stress.

The field of nutriepigenomics looks into how food and epigenetics work together to influence health and wellbeing. eg studies have found that certain compounds within the foods we consume could protect again cancer by adjusting methyl marks on oncogenes or tumor suppressor genes.