Many have heard the phrase “You are what you eat and what you do.” I believe that at first, the idea of a balanced diet linked to physical exercise resulting in a healthy life comes to mind. Macroscopically thinking, this is correct; however, something more intriguing is happening inside our cells.
Delving into cellular biology, we are much more than a combination of maternal and paternal genes. Humans are not just the result of the balance between a reading of the sequence of nitrogenous bases present in their genome associated with environmental interventions. The phenotype is determined by a range of more complex molecular interventions. These modifications occur during gene expression, under the influence of exogenous factors, which, however, do not alter the DNA sequence. Thus, these modifications regulate the interpretation of genetic information and have the ability to generate different phenotypes from the same genotype.
The investigation of these modifications, which are reversible and heritable (to daughter cells during the cell division cycle), that can functionally alter the genome, is called epigenetics.
There are at least two types of epigenetic information that can be inherited with chromosomes and that contribute to the development of diseases, as well as aging: covalent modifications on histones of chromatin and the methylation of cytosine residues in DNA. The modification of histones (proteins present in the structure of DNA) is basically given by acetylation, methylation, phosphorylation, glycosylation, and ubiquitination, determining changes in chromatin conformation. Methylation occurs in CpG dinucleotide islands and is generally associated with gene silencing, in addition to playing an important role in maintaining genome integrity.
During the various stages of cellular development, these epigenetic patterns are reprogrammed and can affect the differentiation of cell lineages as well as the action of transcription factors and cellular aging. It is worth noting that the accumulation of these patterns is proportional to the DNA repair capacity, as well as the interaction with environmental factors such as diet, medications, and toxins, in addition to stochastic factors.
Elke Grönniger and collaborators, in 2010, using a genome-wide methylation analysis technology, showed that aging and skin exposure to sunlight are related to small but significant changes in the DNA methylation pattern of skin samples. Considering the layers of the dermis and epidermis, each tissue has a specific methylation pattern, with little interindividual variation. Thus, it was possible to determine that aging was related to a point variation in only 1% of the studied molecules, while sun exposure was associated with a pattern of hypomethylation.
These highlighted points lead to a reflection where the study of these complex epigenetic modifications resulting from genome-environment interaction will allow the development of new diagnostic methods as well as more targeted therapeutic and aesthetic interventions that culminate in living and aging more healthily.
Reference:
Grönniger E, Weber B, Heil O, Peters N, Stäb F, et al. (2010) Aging and Chronic Sun Exposure Cause Distinct Epigenetic Changes in Human Skin. PLoS Genet 6(5): e1000971. doi:10.1371/journal.pgen.1000971
