Link: http://www.usnews.co.../next040607.htm
6/7/04
Living longer by fixing power outages in our cells
Here's a recent study which ties into my recent posts on extending the human lifespan. Scientists from the Karolinska Institute in Sweden have found that changes in mice mitochondria—the energy plants inside cells—play a key role in aging. The findings, as reported in Nature, show that "mice with a deficient capacity to correct mutations in mitochondrial DNA acquired an increased number of mutations and proved to age considerably earlier than normal. They lived an average of 10 to 12 months compared with the normal 2 or 3 years. These mice also developed several typical signs of premature aging, such as osteoporosis, weight loss, hair loss, anemia, reduced fertility, and heart muscle disorders." Now, it's the job of mitochondria to break down sugars to produce energy. They also have their own DNA separate from the DNA in the nucleus of a cell. So why does mitochondria-gone-bad promote aging? Perhaps the cells begin to malfunction when their mitochondria power plants aren't working properly. Another possibility, suggested by the work of gerontologist Aubrey de Grey and noted by the fine science blog Futurepundit, is that "the cells that have defective mitochondria become toxic, free radical generators for all the cells around them. In essence, a fairly small number of cells become mini-toxic waste sites." (More explanation on free radicals and mitochondria).
As de Grey has pointed out, mitochondria DNA only encodes 13 proteins. So rather than try to fix the mutations in the mitochondria, he's proposed making copies of those 13 genes and putting them into the nucleus of our cells. The idea is that "when the mitochondrial DNA gets mutated, so that one or more of the 13 proteins are no longer being synthesised inside the mitochondria, it won't matter–the mitochondria will be getting the same proteins from outside. Since genes in our chromosomes are very, very much better protected from mutations than the mitochondrial DNA is, we can rely on the chromosomal copies carrying on working in very nearly all our cells for much longer than a currently normal lifetime."
De Grey's work and analysis has been getting an increasing amount of attention, and this study figures to up his profile even more
