Initially, when scientists were beginning to grasp the concept of DNA and its storage genes, they believed certain genes present in the DNA sequence would be expressed and those who were not originally expressed would remain hidden throughout that organisms’ lifetime. The discovery of epigenetics challenged that. Scientists have now discovered there are certain genes that are present in the DNA sequence that at first, are not being expressed but then, by other mechanisms, are “turned on”.
This discovery was a breakthrough in science because it brought along the possibility of manipulating genes to suppress the undesired genes and display those that could be beneficial. If our society is successful in understanding what exterior mechanisms could turn a gene “on” or “off”, we could potentially live healthier lifestyles, giving us control over our gene manifestation. This study of heritable changes in the DNA was named epigenetics because of “epi” is the Greek root meaning above, over, or outer. C. H. Waddington coined this term in 1942.
He was the first attempt to describe the differential of cells from there initial state in embryonic development. Not to be mistaken for a mutation, epigenetics does not tamper DNA sequence but rather modify the activation of certain genes. Epigenetic changes are preserved when cells divide. Most epigenetic changes only occur within the course of one individual organism’s lifetime, but, if gene deactivation occurs in a sperm or egg cell that results in fertilization, then some epigenetic changes can be transferred to the next generation.
This is where hereditary factors take role. How genes might interact with their surroundings is surely important when it comes to producing a phenotype. One experiment that supports this statement is the shape of Combs on Chickens. In the first decade of the twentieth century, British geneticists William Bateson and R. C. Punnett conducted research showing that the shape of the comb in chickens was caused by the interaction between two different genes.
Altering a gene’s surroundings is what contributes to the act of epistasis, the phenomenon where the effects of one gene are modified by one or several other genes. One known mechanism that directly affects “epi” genes is DNA Methylation. DNA Methylation is one of the several epigenetic mechanism that cells use to control gene expression. Other mechanisms include RNA Transcript differations, Prions, and Histone Methylation. DNA Methylation, specifically, is a common epigenetic signaling tool that cells use to lock genes in the “off” position.
Scientists have discovered that DNA Methylation plays a huge role in genomic imprinting, development, the X- chromosome inactivation, and even the preservation of chromosome stability. For many years, methylation was believed to play a crucial role in repressing gene expression, perhaps by blocking the promoters at which activating transcription factors should bind. Presently, the exact role of methylation in gene expression is unknown, but it appears that proper DNA methylation is essential for cell differentiation and embryonic development.
Moreover, in some cases, methylation has observed to play a role in mediating gene expression. Evidence of this has been found in studies that show that methylation near gene promoters varies considerably depending on cell type, with more methylation of promoters correlating with low or no transcription. Histone Methylation, often confused with DNA Methylation, involves more of the modification of certain amino acids in a histone protein by the addition of one, two, or three methyl groups.
Organisms require an appropriate balance of stability and reversibility in gene expression programs to maintain cell identity or to enable responses to stimuli. Epigenetic regulation is integral to this dynamic control. Post-translational modification of histones by methylation is an important and widespread type of chromatin modification that is known to influence biological processes in the context of development and cellular responses. It is because of this why Histone Methylation is directly correlational with disease and health in organisms. Cancer is often talked about when the term epigenetics is voiced.
Although cancer has been reposted to be more of an environmental (brought upon habits such as smoking tobacco, eating unhealthy, or merely pollution), it has also been reported that 5-10% of all cancer patients receive this deadly disease by genetics. Because of the common encounter with cancer, researchers have dug deep into identifying genetic mutations in cancer. Mutations early in the genesis of common cancers have been identified early on and have been reported to most likely be the tumor initiation. Other genetic mutations, though, have been labeled to be more of tumor progression, suggesting epigenetic variations in play.
Overall, because DNA Methylation plays such a vital role in gene expression, abnormalities in pattern can cause disease. A common abnormality during methylation has been noted to be the tumor suppressor genes that are often silenced in cancer cells and prohibit the ability to seize any tumor creation, allowing the tumor to commence growth and consequently, cause cancer. As more research is put upon this subject, better forms of stopping cancer could be discovered, making further research on epigenetics that much more essential. Twins have been often chosen as the perfect candidates to test on the issue of epigenetics.
Because identical twins develop from a single zygote, they have the same genome. Therefore, twins’ identical DNA, Identical twins are most ideal for testing. What supports the belief that there are certain mechanisms that contribute to a gene to be either turned “on” or “off” was supported by how identical twins suffered from different diseases. Because their genes are identical, scientist questioned as to why one twin might express a certain gene activity that might not have been too desirable while the other twin was perfectly healthy.
One big support would be the difference in lifestyles each one participated in, but is shown earlier in life, when they both lived under similar circumstances, what made one twin more prone to encounter a disease, more so than the other one. This is here epigenetics takes part. Because they are genetically the same but their environments become more unique as they age, identical twins are an excellent model for studying how environment and genes interact. Ultimately, they can easily pinpoint which mechanisms in our environment affect twins further in time.
As a twin ages and moves away from its sibling, living conditions differ. One twin may be a chain smoker, while the other one has not smoked a single cigarette, resulting with the smoker twin to develop lung cancer. That is somewhat expected. What through scientists in a loop is mainly when a set of twin live in similar conditions, but their gene expression differs, in how one can contain a disease when the other won’t? Excluding factors, such as mutations, one investigates through epigenetics.
Because of this, twins have become vital in the research of epigenetics. In conclusion, epigenetics can contribute great findings into our society in the hope of manipulating genes to enhance desired genes and oppress those that could cause harm. One issue that looks promising is the treatment of cancer. With more familiarity of epigenetics, we can have epigenetic control of those tumor suppresser genes. We, now, know that by conformational changes in the histones can directly affect the configuration and advancement of cancer.
Medicine looks promising as well. Apart from providing better medicine to patients, doctors can now examine previous medicine and their effectiveness. Knowing which mechanisms can manipulate genes directly can be put into place if needed and previous medicine prescriptions that have been distributed in the past, can finally be put into check, verifying if certain patients have spend plenty of money on a medicine that didn’t necessarily make a difference at all. Epigenetics, though, has been associated with other controversial concepts.
Understanding the concept of epigenetics further can really aid researchers and how to properly use stem cells. Stem cells have been a keen interest to epigenetics because may eventually become possible to dictate what tissue type a stem cell will develop into by studying the epigenetic changes that determine how cells develop. Generally, epigenetics can be a step to a future where we, as a society, can have control over our hereditary genes. By us having control of something we once believed was just fate, we can finally expand the percentages of people living a gratifying life.
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