Written by Henry Chang
It is no coincidence that my father and I share the common trait of black hair and brown eyes. Scientists who have investigated this phenomenon have long explained inherited traits with genetics, or the study of genes and their variability. Half of the genes, which are made of different sequences of nucleotides or DNA building blocks, from each parent are passed down to and visible in the child. Describing further how traits such as hair and eye color come to be is incredibly complex. In addition to the involvement of multiple genes, the regulation of gene expression plays a crucial role as well.
Epigenetics refers to the activation and inhibition of gene expression by heritable, reversible modifications rather than changes in gene sequences themselves. For example, DNA methylation involves the methyl group chemical compound that binds to nucleotides, physically preventing enzymes from attaching and consequently disrupting gene transcription (in which DNA is copied into RNA) to be expressed [1]. Another major mechanism is histone modification. Histones, protein components wrapped by DNA, have nucleotide sequences susceptible to binding from a plethora of chemical compounds, including methyl, acetyl, and ubiquitin groups [2]. Each addition leads to a change in gene expression by either tightening or loosening the DNA strand, thereby impeding or welcoming enzymatic activity accordingly.
What makes epigenetics exciting is that it provides another approach to combat cancer. Cancer involves the abnormal growth of cells because of changes in gene expression. From genetic mutations, certain individuals have dysfunctional regulators of cell proliferation, the increase in cell number by further cell division, and cell death. One research team has exploited known epigenetic mechanisms to restore health by using bioactive dietary components present in common foods such as green tea and soybeans [3]. The team found that the selected chemicals proved to be effective in utilizing DNA methylation and histone modifications to inhibit cancer cell growth. Another team used the relationship between metabolites, the products of chemical reactions, and epigenetics as a cancer response tool [4]. The act of continuously proliferating requires a large amount of energy, obtained by increased metabolism. By epigenetically inhibiting key enzymes, there is now a means of controlling cancer cell growth.
Outside of cancer research applications, epigenetics also encompasses biological inheritance. The perspective from epigenetics “that environment and lifestyle can alter health brings with it awareness that habits, social environment, diet and other factors shape health beyond [an individual’s] acquired genetic traits” [5]. This can be both discouraging and invigorating because, for example, a family history of smoking actually puts a child at risk of pediatric disease [6]. On the other hand, it now stands viable to customize an optimized exercise and diet routine that minimizes the risk of developing any naturally predisposed disease [5]. Therefore, making positive changes now will be an investment not only for one’s future but also for generations to come.
Exploring epigenetics has offered an insight into what can be done for individual health. Whether it be eating smarter or relaxing more, look forward to learning how to supplement your lifestyle.
References:
1. Zlotorynski, E. 2017. Epigenetics: DNA methylation prevents intragenic transcription. Nature Reviews Molecular Cell Biology. 18:212-213.
2. McCarthy, N. 2013. Epigenetics: histone modification. Nature Reviews Cancer. 13:379-379.
3. Meeran, S.M., Ahmed, A. and Tollefsbol, T.O. 2010. Epigenetic targets of bioactive dietary components for cancer prevention and therapy. Clinical epigenetics. 1:101.
4. Wong, C.C., Qian, Y. and Yu, J. 2017. Interplay between epigenetics and metabolism in oncogenesis: mechanisms and therapeutic approaches. Oncogene.
5. Kanherkar, R.R., Bhatia-Dey, N. and Csoka, A.B. 2014. Epigenetics across the human lifespan. Frontiers in cell and developmental biology. 2:49.
6. Leslie, F.M. 2013. Multigenerational epigenetic effects of nicotine on lung function. BMC medicine. 11:27.