What Are The Applications Of Epigenetics?

Since its inception, epigenetics has gained a lot of research because of its applications and implications in development, aging, and health.

Development

Development is a well-orchestrated and crucial process, where the choreographed expression and repression of genes is crucial.  Unsurprisingly, the epigenome plays an integral role in the proper development of an organism. After the fertilization of an egg, the first cell that is produced is known as a zygote. Within this zygote, global demethylation (removal of methylation marks, more information here) of its genome occurs, to a certain extent, in places of the epigenome of the zygote in a ‘blank state’. The epigenome then quickly reboots and re-establishes itself, as the zygote begins to divide and produce daughter cells. A series of differing modulations to the epigenome within all the daughter cells produced by the subsequent cell divisions, then determine what type of cells each becomes, and the cells commit to their final fate.

Age

As organisms age, our epigenome changes. One study compared the methylation patterns within the genomes of newborns and centenarians, and found that methylation decreases with age [1]. This might be one contributing factor as to why the cells of young and old individuals behave differently.

Health

Health has also benefited greatly from work in epigenetics. Epigenetics changes such as decreases in DNA methylation or imbalances of certain histone modifications, have been shown to be present in cancer cells [2], and can serve as additional diagnostic tools. Whether these changes are a cause or a consequence of cancer is still being studied. In addition infections from pathogens such as Mycobacterium tuberculosis cause changes to histones in some immune cells, consequently leading to a key gene within these cells being turned off, which in turn further weakens the immune system of its host [3]. 

Interestingly, it was also shown that people whose mothers experienced famine during their pregnancies were predisposed to schizophrenia, heart disease, and type 2 diabetes [4]. It was further seen that this predisposition could be partially explained by changes in their methylation pattern in some genes. Moreover, these changes were not seen in siblings who did not experience famine before their birth. This further supports the notion that these changes in the epigenome are likely or contributing causes of the diseases later in life [5-7]. 

Overall, epigenetics is one of the more exciting frontiers of biology that continues to grow and blossom with every new discovery. As more resources are being funneled into it, and more tools are currently being developed to answer the major questions in the field, it is primed to evolve even further. Whenever you marvel at the diversity of cell types within an organism, just remember this is simply the epigenome at work.

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Written by: Renard

Edited by: María and Natasha

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References:

1. Heyn, H. et al. (2012) “Distinct DNA methylomes of newborns and centenarians”, Proceedings of the National Academy of Sciences, 109(26), pp. 10522-10527. Available at: https://pubmed.ncbi.nlm.nih.gov/22689993/

2. Baylin, S. and Jones, P. (2016) “Epigenetics determinants of cancer”, Cold Spring Harbor Perspectives in Biology 8(9): a019505. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008069/

3. Chandran, A. et al. (2015) “Mycobacterium tuberculosis Infection Induces HDAC1-Mediated Suppression of IL-12B Gene Expression in Macrophages”, Frontiers in Cellular and Infection Microbiology, 5. Available at: https://pubmed.ncbi.nlm.nih.gov/26697414/

4. Roseboom, T. (2019) “Epidemiological evidence for the developmental origins of health and disease: effects of prenatal undernutrition in humans”, Journal of Endocrinology, 242(1), pp. T135-T144. Available at: https://pubmed.ncbi.nlm.nih.gov/31207580/

5. Heijmans, B. et al. (2008) “Persistent epigenetic differences associated with prenatal exposure to famine in humans”, Proceedings of the National Academy of Sciences, 105(44), pp. 17046-17049. Available at: https://pubmed.ncbi.nlm.nih.gov/18955703/

6. Tobi, E. et al. (2009) “DNA methylation differences after exposure to prenatal famine are common and timing- and sex-specific”, Human Molecular Genetics, 18(21), pp. 4046-4053. Available at: https://pubmed.ncbi.nlm.nih.gov/19656776/

7. Tobi, E. et al. (2018) “DNA methylation as a mediator of the association between prenatal adversity and risk factors for metabolic disease in adulthood”, Science Advances, 4(1). Available at: https://pubmed.ncbi.nlm.nih.gov/29399631/