Without you even knowing, the environment is getting under your skin. Every food choice you make, every all-nighter you pull, every stressful situation in your life works to change who you are, one DNA-regulating change at a time. Epigenetics, the study of heritable changes to your genetic sequence, addresses the modifications that are caused by how you live your life, modifications which lead to differences in your appearance and behaviors without fundamentally changing your DNA.
DNA is the genetic code of our body. Similar to the 1s and 0s that make up the basis of computer science, the As, Ts, Cs, and Gs construct a genomic fingerprint that make you who you are. Every single cell in your body contains this same collection of DNA bases that guide the body in its every aspect of function. For a time, science believed that genetics were set in stone. The zygote that initially developed with your DNA maintained the same genetic code throughout your life, dictating your growth, development, behaviors, and the totality of your personality that makes you an individual. In most biological cases, this holds true. Every cell contains the same DNA, but it’s the expression of that DNA that leads to the differences between cells, between people, and even between you now and years ago.
Overview of Epigenetics
Epigenetic research has revealed three main methods of determining the genes that are expressed: DNA methylation, histone modification, and non-coding RNA mechanisms.
In DNA methylation, a class of enzyme proteins known as DNA methyltransferases attach a methyl group to a C nucleotide, called a CpG site. On the DNA, CpG islands, many of these CpG sites next to each other, are placed near genes that need to be regulated. When methyl groups are attached to these methylation sites, the cell is prevented from expressing this gene because the enzymes that copy this gene are blocked from attaching to it.
In a similar fashion to how twine is turned into rope, cells wrap their long strands of DNA around histone proteins to compact the strands into tightly-wrapped chromosome structures. When the DNA is tightly packed in this way, genes cannot be accessed, preventing their expression. Through histone modification, the DNA can be loosened or tightened through chemical reactions performed on the histone proteins. Acetyltransferase enzymes add a chemical acetyl group to receptors on the histones which spread them out along the DNA, allowing the cell to access the DNA and translate it into proteins.
Non-coding RNA molecules silence any RNA molecules (the molecule coded from DNA) that have a similar sequence. Short non-coding RNA mechanisms in the cell are combined with other proteins to help the RNA molecule bind to other RNA molecules of similar sequence and cut up these RNAs, preventing their expression. Long non-coding RNA, instead of cutting up the molecule it binds to, seeks out specific genes and binds to them, preventing the cell from expressing them.
Body cells ultimately use these main methods to decide which genes are expressed and which ones are turned off. This concept allows the same cell from the original zygote to eventually become a neuron and a skin cell, two types of cells with completely distinct functions and structures.
Environmental Influence on Genetics
The lifestyle you live has an even greater effect on these cell processes than you may think. Epigenetics research has established clear links between environmental factors and DNA regulation, leading to gene suppression which can result in disease or rapid aging.
With an intense workload and an incessant feeling of perfection, many students opt to neglect their own health in favor of higher quality work. Many believe they can suffer through four years of poor health decisions and make up for it after they survived the orange and black turmoil brought on by Princeton classes. Without even realizing the implications of these actions, students are transforming their health for years to come, even having the potential to pass these poor health effects on to their children.
In the realm of diet choices, an Uppsala University research team discovered that a greater consumption of tea led to higher DNA methylation in women, especially in genes associated with proteins that operate in cancer and the digestion of estrogen, a hormone commonly involved with cancers. “Previous studies have shown that tea consumption reduces estrogen levels which highlights a potential difference between the biological response to tea in men and women,” says Dr. Weronica Ek, the lead researcher for the project.
Without even realizing the implications of these actions, students are transforming their health for years to come, even having the potential to pass these poor health effects on to their children.
The methylation process prevents these genes from being expressed, giving tea the potential to either exacerbate or alleviate cancer, necessitating further investigation into the true role of these genes. Seeing the strong impact of diet choice on which genes are turned on and off, students need to take seriously the food choices they make in the dining halls. Whether it be long-term consumption of tea, sugar, or protein, the body adjusts over time to these decisions and can change your propensity for disease.
Princeton students are especially guilty of the 24-hour-eye-opening period of binge working, caffeinated drinks, sugary snacks, and self-pity known as the all-nighter. Yet, after you survive the night and make it through the next day’s classes, is it possible for you to fully reset and be prepared for the all-nighter you pursue the next week, or even within the next few days?
Unfortunately, a Princeton research team led by doctoral student Sarah James established a connection between lower sleep times earlier in a student’s life and shorter telomere length throughout life. Telomeres at the end of DNA shorten every time the cell replicates its DNA, which occurs with every cellular division. These structures act as protective ends for DNA that codes for proteins and are thus linked to aging, as a cell cannot divide further if the telomere is shortened to the point where it can no longer protect the main parts of DNA. The results of shortened telomeres could lead to impaired health and physiological stress later in life as well. While this research is preliminary and has not demonstrated a purely epigenetic cause to the telomere shortening, there is a high probability that DNA methylation in combination with oxidative stress is leading to these detrimental changes.
Epigenetic Inheritance across Generations
Following these epigenetics studies, additional research was published by the Max Planck Institute of Immunobiology and Epigenetics suggesting that these epigenetic effects on health could be passed down to offspring as well. “We saw indications of intergenerational inheritance of epigenetic information since the rise of the epigenetics in the early nineties… Since then, various reports suggested epigenetic inheritance in different organisms, but the molecular mechanisms were unknown,” says Dr. Nicola Iovino, the study’s lead researcher. With this research aim in mind, Iovino and his team used chemically-tracked chromosomes in fruit flies to follow the transfer of methyl groups from parents to offspring, thereby showing that the same epigenetic edits seen in parents were also clearly present in their children. As a result, these changes in DNA regulation linked to the environment are not only long-term, but can survive the stretch of a lineage as well.
We think our bodies are more resistant than they truly are. But, no matter how tough we are, the environment still finds a way to have long-term effects on the genes that are turned on and off, resulting in noticeable changes to health and behavior. Students believe they can tough out their studies while neglecting their health, expecting a reset to their bodily functions after they survive it all. In reality, these strains on physical and mental health have far-reaching implications, even leaving future children at a disadvantage health-wise due to the transfer of these epigenetic changes across generations. Since your environment and the choices you make will likely continue to follow you throughout life, it is important to care for yourself here and now.