Epigenetics Video

The PBS video uses identical twins to illustrate how people with the identical DNA may still have differences. Those differences result from epigenetics, according to the narrator. To illustrate how epigenetics work, the video visits a scientist at Duke University. One mouse is hugely obese and yellowish, and the other mouse with identical DNA is brown and thin. The reason why is because while both mice have the same gene that controls weight gain, in the yellow fat mouse that gene (agouti gene) "stays on all the time," the narrator explains.

Both mice have that gene (the "agouti gene") but for the thin mouse, a "tiny chemical tag of carbon and hydrogen" called the "methyl group" has attached itself to the agouti gene basically shutting it down. So the brown thin mouse is normal size but the yellow fat mouse, much larger than normal, has had its agouti gene shut off and hence there is no control over how much it eats to satisfy itself because the gene that controls this function is immobilized.

The narrator explains that the certain materials like the methyl group (through "methylation") and the histones, through histone patterns, are in every cell in the human body, and they make up what is known as a "sort of second genome, the epigenome." In attempting to explain how the genome and epigenome work, the scientist at Duke University (Randy Jirtle) uses the computer as an example. The genome is the hardware of a computer, and the epigenome would be the software that directs the computer as to how to work, when it should work, and how much work should it be responsible for.

In other words, the epigenome also is responsible for what color hair a person has, how dark the skin should be. As the narrator says, every cell has the same genes, but the software (epigenome) tells the cell how it should act; and in fact the epigenome that is attached to the cell makes one cell...

The "instructions" from this epigenetic process are passed along while the cells are dividing, and meanwhile humans can have an effect on the epigenetic process, the narrator continues.
How does this happen? In the mice scenario the researchers can manipulate the epigenomes (by feeding the pregnant mother mouse food that is "rich in methyl groups" which will eventually turn the genes off; the fat mouse had epigenomes that wouldn't let the gene responsible for hunger shut down.

Why is understanding the epigenomes work important to medical researchers? Much of this research was conducted using identical twins, so that the scientists can witness (and prove) that as twins move on in age, there are epigenetic differences that occur, in particular when the lifestyle of one identical twin is different from the lifestyle of the other. But when a person has cancer, in the past researchers would tend to believe that cells were broken and it is very hard to repair damaged genes.

But instead of trying to repair broken genes in a person that has cancer -- or killing the cells which radiation therapy (and "chemo") attempts to do -- with epigenetic therapy the researcher is actually trying to "change the instructions of the cancer cells"; this is done by reactivating genes, the narrator says. If this process can be proved and can be used on not only cancer patients but others suffering from serious disease in which the cells are being negatively impacted somehow, it could be an enormous medical breakthrough.

The video used the example of a woman who was given six months to live (because she had cancer of the bone marrow) but with epigenetic therapy she said the results were "incredible," and more than that, she gets to live out her life. The video was very interesting and the production made understanding what was going on quite easy, although some of the science was…