Genetics and Aging

With all the talk of the telomere aging effect, have there been further studies and what have they learned ? Biology Class, Cambridge Academy

Everything ages with time, including the human body. Why does the aging process occur? Is it pre-programmed into our genetic make-up, or does our external environment play a large role in the natural aging process ? Although these are questions that have eluded answer for centuries, there are a few scientific arguments on the drawing board.

Many scientists believe that our bodies age due to the accumulation of environmental pollutants (oxidants) within our cells, which can damage the genetic material and other cellular components. This "free radical" theory can be extended into the basis of cancer, Parkinson and Alzheimer disease. In these diseases, the role of increasing mutations within our genetic material and/or accumulation of cell damage, leads to disease progression and cell death. A more recent and compelling argument is based on the role of the telomere (tel-o-meer) in the cellular aging process. This theory holds that our bodies are pre-programmed from birth with a "biological clock" that controls cell growth, and cell death.

Our bodies normally grow and develop through repeated divisions of our cells. Human cells undergo a limited number of cell divisions and ultimately enter into a state of decline, leading to cell death. Chromosomes, found within each of our cells, may have an important role in determining how many of these cell divisions occur. Scientists are now looking at the presence and length of markers called telomeres, which are repeated stretches of DNA found at the ends of chromosomes. In normal body cells, telomeres become increasingly shorter in length each time the cell divides, and the body ages. The opposite is true in our germ or sex cells, where telomere length generally remains stable, even as the rest of the body ages. Scientists believe that this cell stability is due to the presence of a special enzyme called telomerase. Telomerase acts in these germs cell to replenish the repeated segments of DNA at the tips of the chromosomes.

Recent studies indicate that one can increase the telomere length, and thus the cell life span considerably, by also adding the telomerase enzyme into normal body cells. Therefore telomere length, and the presence or absence of this enzyme, may be the natural "biological clock" determining when and how many times our body cells should divide, to control the aging process. Interestingly cancer cells also often produce telomerase, which makes them "immortal." More research into this area may lead to practical cancer therapies. One can learn more at the Aging Research Center at http://www.arclab.org