You Are Your DNA – or Are You???

Posted on | April 10, 2018 | Comments Off on You Are Your DNA – or Are You???

Source:
U. of Utah Epigenetics

Mike Magee

Early in my career, embryology and physiology competed for my affection.

What they had in common was functionality – one developmental with time dependent triggers and the other driven by feedback loops with humoral packets of information traveling through blood channels or along neurons.

I viewed both processes as eloquent, intricate, and genomically dependent. But what appeared so concrete to me then, is being challenged by modern science in the name of epigenetics.

The epigenome is nuclear information and is inheritable, but it’s also plastic. It contributes to cellular development and differentiation during embryogenesis, but its’ messaging can be modified by random chance changes or by environmental exposures.

All cells of the body have the same DNA, but they evolve during development assuming specialized functions. How is that possible? The answer is in part that the cells add epigenetic genomic information to their own genes.

The University of Utah’s Epigenetic training site says “The genome is just the A,G,T,C bases that encode proteins and other mRNAmolecules. The “epi”genome are various modifications to the DNA – such as methylation (at C residues) – and acetylation of histone proteins. These changes help the DNA form various secondary and tertiary structures that can facilitate or block the interaction of DNA with the transcriptional machinery.”

Conrad Waddington first described the “epigenetic landscape” in 1950 as the evolving specialized development of pluripotential stem cells. The instigators were presumed to be imbedded somehow in the DNA. But a more modern construct suggests that there are modifications and/or additions to the DNA, some driven by environmental factors, and that these modifiers are maintained in future cell divisions.

This not only modifies our view of embryology, but also of the aging process, the dietary impact on health, and the pathogensis of cancer and its metastatic spread.

For example, nicotine instigates epigentic changes in smokers and in cord blood and the placenta.

Almost all tumors have documented gains and losses in their cellular DNA. Where in the past cancer was viewed as many diseases, scientists are now beginning to believe they have more in common than previously thought, and that the essential common feature is a “disrupted and unstable epigenome.”

With wholesale availability of genetic testing, citizens are putting down their money to identify their genetic predisposition to disease. The problem is that this picks up only a very small fraction of ones vulnerability, failing to capture the role of the environment which scientists are now saying may account for 80% of ones disease risk.
Inflammation, diet, toxins and more deliver their destructive punch through an interaction between genes and the environment, and epigenetics – whose chemistry is now being structurally defined – likely mediates these destructive changes, as well as potential new therapies.

U.Utah Epigenetics

Finally the issue of epigentics and inheritabilty. The Utah experts suggest, “The sketch … tries to explain why epigenetic effects can, in practice, be difficult to disentangle from true (changes in the A,G,T,C sequence) genetic effects. This is because – for one reason – a mother’s experience (extreme stress, malnutrition, chemical toxins) can – based on some evidence – exert an effect on the methylation of her child’s genome… if the daughter’s behavior or physiology were to be influenced by such methylation, then she could, in theory, when reaching reproductive age, expose her developing child to an environment that leads to altered methylation (shown here of the grandaughter’s genome). Thus, an epigenetic change would look much like there is a genetic variant being passed from one generation to the next, but such a genetic variant need not exist – as it is an epigenetic phenomenon.”

So, are you really your DNA, or something more? Stay tuned!