What the hell is epigenetics?
Some of you may have recently heard the term “epigenetics” in the mainstream media and thought what is that and how does that impact my health. Should I be concerned about this new scientific trend or will we figure out it has virtually no impact on the human body? Epigenetics has recently become one of the hottest fields in the biological sciences, and I think it will undoubtedly help explain some of the odd trends in public health. There are many, and often unexplainable, scary trends in human health. Certain cancers are on the rise, autism is on the rise, girls are menstruating earlier than they used to, and babies are born larger than they used to be. A common theme for all of these phenomena, including our high obesity rate, is likely epigenetics, and I think this will eventually be the focus of preventative medicine.
You may be wondering, what the hell is epigenetics? Epigenetics means “above the genome” and controls how our genes are regulated without changing the actual genes. Allow me to provide some necessary background. Everyone contains thousands of genes that are used to make individual proteins, each having a specific function. The central dogma of molecular biology is that genes encode the instructions for making proteins. Deoxyribonucleic acid (DNA) stores the genes, which are then transcribed into a molecule called ribonucleic acid (RNA), which is then used to produce a protein. We have thousands of different proteins in our cells, and each one of them has a specific purpose. Some proteins provide structural support for our cells, some aid in cell movement, some are required for cell repair and division, some help make or destroy other proteins, some help create DNA and RNA, and some help in metabolism. The list of functions that our proteins perform is overwhelming and lengthy and would not fit into this blog. What is key to know, is that individual cells need to make the right proteins for them at the right time in order to perform its required functions. All cells except sperm and egg cells contain the same DNA, but each cell type has different proteins and different protein levels in them. For example, a heart cell will contain different amounts of certain proteins than a skin cell or a bone cell. The term “expressed” is used to refer to whether a protein encoded by a particular gene has been produced. When gene expression control is not regulated properly, disease states can begin to develop. A classic example of this is that if your cells start producing too many proteins that promote cell division, cancer could eventually develop.
The reason that individuals have unique characteristics, or traits, is because our DNA sequences are not the same. Slight variations in gene sequences can produce different protein products, which can have an immense impact on the function or behavior of a cell. Some of us contain gene variants that promote great distaste for cilantro while other people like myself fortunately do not contain these variants, some contain variants that make us bald, some contain variants that make us tall, and unfortunately some of us contain variants that make us sick. Gene sequences alone though cannot explain all of the traits we observe in the human population. If this were the case then identical twins would appear identical their entire lives, but over time they begin to look different from their sibling. I’m sure we all know a set of identical twins. When they are younger they are harder to distinguish from one another, but as they age it is sometimes difficult to tell that they are even related. What accounts for the characteristic differences between identical twins are epigenetic changes, changes that bridge the environment with genetics. In my opinion, this is an exciting time to be talking about biology, as the field of epigenetics will help us figure out if and how certain environmental factors influence our characteristics, whether that is our BMI, list of allergies or overall health.
How do epigenetic changes work and why am I going on and on about this on the Monroe Real Training website? I’m getting there. Gene expression control plays a paramount role in everything our body does. The right genes need to be turned on and the right genes need to be turned off at the right times to keep our cells functioning normally. Gene expression is regulated in part by small chemical “tags”, which are referred to as epigenetic modifications. These tags either directly modify the DNA (without changing the DNA sequence) or modify proteins associated with the DNA (again without changing the DNA sequence), to either promote or suppress transcription of DNA into RNA. Although this is not well understood, mounting evidence demonstrates that these chemical modifications are influenced by environmental factors. Many studies have shown that an animal’s diet and certain chemicals found in the environment or in food can regulate where the epigenetic tags are placed, thereby influencing the expression of certain genes, including some that are involved in processes such as metabolism or cancer prevention. Scientists are examining the roles of specific chemicals such as pesticides and BPA and different types of diets in epigenetic changes and have found that environmental factors influence where the tags are placed. More and more studies are showing that misplaced tags are found more often in individuals with cancer or type 2 diabetes, for example. The take home message is that what we put into our bodies can immensely impact our cells’ behavior, but significantly more work needs to be done to determine how different chemicals and foods work to promote positive or negative epigenetic changes.
An interesting aspect of epigenetics that I have not mentioned is that it appears some epigenetic tags, particularly the ones directly attached to the DNA, can be inherited by your children. Thus, what this means, particularly in the context of obesity, is that eating an unhealthy diet can increase your child’s susceptibility to becoming overweight. Geneticists have figured out that obesity is partially heritable, but it has been difficult to explain its heredity through DNA sequences alone. Thus, undoubtedly epigenetic changes are a major contributing factor. Studies examining the health of children born to parents and grandparents from the same part of the world who grew up during periods of famine or availability of excess food have demonstrated that the children have different health outcomes depending upon their parents’ food availability. Thus, what your parents and grandparents have been exposed to can impact your health. I personally think this is one reason why it is difficult for many people to lose weight. If epigenetic tags have been placed in the wrong spots for the countless genes that regulate metabolism, you have been predisposed to becoming overweight and need to work even harder to counteract a less than ideal metabolism. Many people who seem to eat well and exercise still do not always lose weight. I don’t think anyone should feel discouraged by this information but instead be encouraged by the fact that epigenetic modifications are not permanent – we just need to figure out how to change them. Some studies have shown that exercise and eating less and healthier can change the tags. I think what research will show is that a consistent and continuous healthy lifestyle will be required to reverse a bad epigenome that we may have inherited from our parents. Thus, unfortunately some of us have to try harder but it’s worth the effort.
In conclusion, the environment influences our health, in part, through epigenetics. We do not control what genes we are inherited with, but we can control our epigenome. How we live our lives not only influences our own quality of life, but our lifestyle decisions will be passed along to the next generation. The next time you’re training (hopefully with Kevin), think about the idea that your efforts are creating a healthy epigenome and a healthier life.
References
Kaati, G., Bygren L.O. & S. Edvinsson. (2002) Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period. Eur. J. Hum. Genet. 10:682-8.
Tollefsbol, T.O. (2014) Dietary epigenetics in cancer and aging. Cancer Treat. Res. 159:257-67.
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