The beginning
A common question that may come to mind when you hear the word "epigenetics" for the first time is: Where does this word actually come from? The history of epigenetics is closely linked to the study of evolution and development [1]. The term was originally coined in 1942 by embryologist Dr. Waddington and is derived from the Greek word "epigenesis", which originally described the influence of genetic processes on development [2]. Although the term only emerged in the 1940s, the "epi" in "epigenetics" can be traced back to the 19th century - the idea that genes are influenced by factors beyond the genome [3].
Late 20th century
Until the 1950s, the word "epigenetics" was used inaccurately to include all developmental events from the fertilized zygote to the adult organism [1]. Around this time, Waddington proposed the famous "epigenetic landscape." He described the cell as a sphere that could follow different paths due to the unevenness of the surface, symbolizing intra- and extracellular environmental influences [4].
In the period from 1970 to 1980, the identification of high mobility group (HMG) proteins allowed scientists to realize that, in addition to histones (discovered in the early 20th century), there are also other proteins that play a role in phenotype expression and chromatin architecture [5]. This was followed by the discovery of the phenomenon of imprinted genes and their regulation according to maternal and paternal inheritance [6].
Nonetheless, DNA methylation (5mC) and post-translational histone modifications were identified shortly after the elucidation of the DNA double helix structure. DNA methylation was discovered early, in 1965. Other modifications such as histone methylation, acetylation, phosphorylation, ubiquitylation, sumoylation and ADP-ribosylation were discovered between 1962 and 1977 [8,9].
Early 21st century
Despite the fact that much was understood about DNA and its general organization by the middle of the last century, it was not until the 1990s and 2000s that epigenetics began to be intensively studied. Advances in the field of cloning (e.g. Dolly the Sheep) helped answer several unanswered questions [7]. The development of toolkits and biochemical techniques allowed researchers to identify specific enzymes, readers, writers, and erasers of epigenetic marks.
present
To date, DNA methylation is one of the most studied and best characterized epigenetic modifications. An example of the importance of this process and its biological relevance is X inactivation. This is a process in which one of the two X chromosomes in female mammals is inactivated. The inactive X chromosome is silenced and packaged into heterochromatin, a structure that is transcriptionally inactive [10]. Silencing therefore occurs due to high levels of DNA methylation accompanied by other histone modifications [11].
The road to a full understanding of the importance of epigenetics is long. However, there is still much to discover in this relatively new and exciting field of study. At MoleQlar Analytics, our goal is to help deepen the knowledge of our epigenetic code, validate biomarkers of various diseases, and identify new epigenetic drugs. In the near future, MoleQlar Analytics aims to leave a notable footprint in this space.
