What is epigenetics, and how is it related to longevity?
Humanity has long been interested in longevity and how to live longer and healthier. The term epigenetics has been associated with this topic. But what is epigenetics?
Epigenetics offers insight into the rate of ageing. It is a branch of molecular biology that deals with gene expression change unrelated to changes in DNA sequence. It recognises that environmental factors can also influence an individual's gene expression.
The term epigenetics was coined in the 1940s. Literally, epigenome means "above the genome."
Epigenetics studies how the environment affects the function and activity of genes in cells - whether in humans, animals, or plants - and how these environmental influences can be passed on to our offspring. The idea is that we are defined by the genes we inherit. But what about the environment? Epigenetics studies how diet, obesity, physical activity, tobacco smoking, alcohol consumption, environmental pollutants, psychological stress, working night shifts, etc., affect us and our genes.
Undoubtedly, a large part of who we are depends on the genes inherited from our parents. Our daily life can change our epigenome, which means that our environment influences us greatly.
Switching genes on and off.
Epigenetic modification of heredity does not change the DNA sequence that contains the record of how our body functions and looks, but the activity of the genes. It is constantly adapting to the environment.
For example, researchers found that the mother's diet during pregnancy significantly affects the child's DNA and may increase the risk of childhood obesity. Suppose the mother is on a low-carbohydrate diet. In this case, this causes epigenetic changes in the child, leading to obesity problems in later years. The researchers confirmed this is an epigenetic effect. These people better use food energy to ensure survival in times of food shortage. Well, they were also better at storing it when there was no shortage.
In a study published in Nature Neuroscience, scientists trained mice to associate a particular smell with danger or discomfort. The mice passed their aversion to the smell to their offspring and grandchildren.
Epigenetic patterns - a reaction to the environment and a consequence of lifestyle
Nature uses this mechanism to help our bodies remember certain things from our environment so that we can adapt. It can pass on these environmental messages to our descendants if it feels it is necessary.
Environmental influences can cause more methyl groups to clump together in the area of DNA that regulates the activity of a gene, making that gene less active. The opposite is also possible: environmental influences can cause methyl groups to disappear from the DNA region that regulates the activity of a particular gene, making that gene more active.
Scientists have also found that these changes enable a species to survive but are not permanent changes to the DNA. They can be passed on from generation to generation. Nevertheless, they can also be removed from the genome if this is necessary to return our genome to its original state.
Lifestyle from mother to offspring
It is important to see that the body's 'adaptation' to various harmful environmental factors such as obesity, smoking and stressful situations does not only affect us as individuals but can be passed on by mothers or fathers to their offspring in the form of inherited epigenetic instructions.
Or as Nicola Iovina, one of the authors of the study published in Science, explains: "Our study shows that we inherit more than just genes from our parents. We also receive finely tuned and important genetic regulatory mechanisms, which our environment and individual lifestyle can influence. Our results support the thesis that, at least in some cases, acquired environmental adaptations can be passed on to our descendants via the family line."
Epigenetics plays an important role throughout life, from the embryo to old age. These changes also accumulate in the body.
Who is Steve Horvath? And what is an epigenetic clock?
Ten years ago (2011), Steve Horvath, professor of genetics and biostatistics at the University of California, studied how age affects methylation from birth to age 101 by analysing 8000 samples of 51 tissues and cell types from different parts of the body.
He correlated the state of epigenetic markers associated with ageing. He compared them with what one would expect to see at a certain age. He concluded that biological age could differ from the actual age (chronological age). This allowed him to define the test parameters (hundreds of age-related changes) and thus develop the so-called first epigenetic "clock". This research (published in 2013) and the UCLA results provided valuable advances for current cancer and stem cell studies. The findings are also crucial for research into human phobias, post-traumatic stress, and anxiety.
The age of various human organs, tissues and cells can be estimated accurately. The biological clock has shown that not all body parts have the same biological age.
Epigenetics has progressed over the years and is well-developed to date. A whole range of commercial tests on the market already assess biological age. However, it is important to note that commercial epigenetic tests are still in their infancy. As consumers, we must be cautious when purchasing, interpreting the results and protecting sensitive personal health information.
The effect of exercise on fat cells
Research at Lund University in Sweden has revealed that leisure or sporting activities change our fat cells. "Our study showed that sport has a positive effect because it changes the epigenetic markers of genes that influence fat storage in the body," explains Professor Charlotte Ling.
In the study, the researchers observed what was happening in the fat cells of 23 healthy, slightly obese 35-year-old men who had not exercised before the survey. During the study, they were asked to take regular spinning and aerobics classes for six months. "They were supposed to exercise three times a week, but on average, they only exercised 1.8 times," said one of the women in the study.
Using technology that analyses 480,000 positions in the genome, they found that epigenetic changes occurred in up to 7,000 genes (a human has between 20,000 and 25,000 genes).
They then studied the methylation of genes concerning type 2 diabetes and obesity. They found that the changes in the genes are due to exercise and that these genes influence whether we develop a particular disease. This was the first study to look specifically at fat cells. It showed that our lifestyle can impact our health and how we feel and look and confirmed that many diseases - or lack of them - are our fault.