As if the multi-factorial plague of obesity were not complicated enough already, it seems that epigenetics must be counted in the equation. WhatIsEpigenetics.com has two sections, one for actual researchers in the field and the other, described as “educationally entertaining,” for the general interested population. In this section, sober facts are mixed with more expressive descriptions.
We are made of cells, which need to be told what to do, and they are told it by DNA (deoxyribonucleic acid) which supports more than 20,000 genes. An introductory article says:
Genes are specific sequences of bases that provide instructions on how to make important proteins — complex molecules that trigger various biological actions to carry out life functions.
A gene can be either dormant/silent or active/expressed. What makes the decision? Epigenetics. Apparently, anything that enacts chemical changes in the body has the power to turn certain genes on or off. This matters a lot, because turning on a gene that makes dementia or cancer is not such a great idea.
Any number of things have the power to change the inner chemistry. Food, obviously, is a major influence, along with other substances like medications, and toxins that are inadvertently brought into the body. Exercise, stress, sleep, age, and many other variables play their parts in gene expression and, as the old saying goes, “That’s what makes you you, and me me.”
Here is where the entertainment part comes in. The writer of the “basic explanation” page encourages us to think of the human life span as a movie, in which the cells are the actors. When the film hits the theater, attention is naturally focused on the photogenic thespians who are moving around and talking, and so on. They are necessary, but not sufficient.
That movie would not exist without the script, which tells the actors how to move and what to say:
The DNA sequence would be the words on the script, and certain blocks of these words that instruct key actions or events to take place would be the genes. The concept of genetics would be like screenwriting…
The concept of epigenetics, then, would be like directing. The script can be the same, but the director can choose to eliminate certain scenes or dialogue, altering the movie for better or worse.
Now, here it is in more technical (but still intended for the non-professional audience) language:
Epigenetics is the study of potentially heritable changes in gene expression (active versus inactive genes) that does not involve changes to the underlying DNA sequence — a change in phenotype without a change in genotype — which in turn affects how cells read the genes.
At least three systems including DNA methylation, histone modification and non-coding RNA (ncRNA)-associated gene silencing are currently considered to initiate and sustain epigenetic change.
The prefix epi- comes from ancient Greek, and can mean in addition to, near, above, over, besides, outer, among, toward, on, or attached to. In modern parlance, we might say genetics-adjacent. Biological mechanisms put chemical tags on DNA that in turn have the ability to switch genes on or off.
In another post, Natalie Crowley phrases the same idea in slightly different words:
Epigenetics is the study of changes in gene expression, heritable during cell division that does not involve changes to the underlying DNA sequence. These changes are also influenced by age, the environment, lifestyle, and health.
This is another almost brand-new field of research where there are, of course, many more questions than answers. Crowley also notes that epigenetic mechanisms are dynamic and — here is the best part — “potentially reversible with therapeutic intervention.”
Your responses and feedback are welcome!
Source: “A Super Brief and Basic Explanation of Epigenetics for Total Beginners,” WhatIsEpigenetics.com, 07/30/13
Source: “Epigenetics: Fundamentals,” WhatIsEpigenetics.com, undated
Source: “The Epigenetics Behind the Flu,” WhatIsEpigenetics.com, 11/17/15
Source: “Could Epigenetics Explain the Origins of Allergic Disease?,” WhatIsEpigenetics.com, 03/24/15
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