Every living cell in our bodies has the whole set of genes that it took to grow us from a one cell embryo to the beautiful blogging people that we are now. It’s just that the whole set is never working at any one time. Our growth, development, abilities and repair depend on whether a certain gene or set of genes is turned on or off by (what I think of as) the addition of keys and locks and cushions.
We constantly hear about the embryonic stem cell’s ability to “develop into every cell in the body” (and all those pesky tumors when they’re used in animals), as well as the trouble getting adult stem cells to work fast enough to repair damage. There’s also the problem of aging, which is really just when our body can’t replace dying cells as fast as we lose them, added to the fact that the cells themselves seem to die sooner and more often.
Epigenetics are the influences in the cell that turn certain genes on and others off. And they are the hot topic in the serious study of stem cells, embryology and medicine.
Stem cells rely heavily on epigenetic signals. As a stem cell develops, chemical tags on the DNA or its surrounding histone proteins switch genes on or off, controlling a cell’s fate.
You may hear of “methylation” or “imprinting” of genes. These chemical processes are how the DNA program within the nucleus of the cell – the blueprint and instructions for what the cell will do today or for the rest of its life – is set. They are the “epigenetic” conditions that fold away some genes and expose some others so they can be read.
One of the cushions is the telomere. After Dolly the sheep was cloned, we heard about telomeres – the repeating tags on genes that make the difference between a gene being young or old. I think of the string of telomeres as a roll of postage stamps. Each time you send a letter, you use a stamp, and eventually you don’t have any.
In the same way, genes lose telomere segments when they are copied. Eventually, there are not enough telomeres to make the gene copying system kick in. But, sometimes, telomeres can be added by the cell’s system and sometimes they aren’t lost at all during copying.
What if you could go to the telomere office and buy a new roll or, better yet, if you could just make the ones you need in your own cells, when and where you need them?