Thursday, August 21, 2014

Who Wants to Live Forever?

In 1986, the rock band Queen asked a simple question, "Who wants to live forever?"  Everyone has asked that question, and Dr. Elizabeth Blackburn and her team won a Noble Prize in pursuit of that discovery.  They found an answer the the biological cause of aging: telomeres.  Jalees Rehman wrote an extensive piece on the topic on SciAm's blog page.

Telomeres protect the ends of our chromosomes
Not long after the discovery of telomeres and their enzyme, telomerase, people began dreaming of a magical elixir of life to reverse aging.  Aging is, unfortunately, a very natural process.  As cells live, they because damaged due to various forms of stress and attack.  To survive, they must reproduce to make more cells.  This requires the replication of the genome.  DNA synthesis splits open the double helix and copies the unpaired nucleotides to produce an identical strand.  Well, almost identical.  The ends of the chromosomes get a little bit difficult and some parts of the ends don't get copied.  The best analogy is the ends of a string.  The ends fray the longer it gets used.  So how do you protect the ends?  Shoe laces have plastic covers called aglets, and your DNA has a telomere.  The telomere is noncoding DNA at the end of a chromosome.  A little bit of the telomere frays away every time the cell divides.  This determines the lifespan of the cell.  Once the telomere erodes away, important coding genes become damaged and the cell must die.  The accumulation of this type of death is called aging.

Dr. Blackburn learned that a sample of DNA can provide enough information to learn about a person's health.  People with longer telomeres were biologically younger, even if not chronologically.  Those with short telomeres were three times more likely to have cancer.  Cancer cells have activated telomerase that repairs the vanishing telomeres producing a cell that never dies.  Cancers cause problems because they have too much telomerase.  Every cell has telomeres, but not every cell has telomerase.  This is so that cells can naturally die out of the way, but cancer messes that system up.

So having too little telomeres can cause the problems of aging.  Too much telomerase can cause the problems of cancer.  Then the healthiest has to be right in the middle.  So their might not be a magic potion to reverse aging and rebuild our telomeres.  At least not without significant risks.  Instead, have have to protect the telomeres we have.  Reduce the stress we put on our cells and let them live out their full potential.  You won't live forever, but you might make it a long time.  Besides, who wants to live forever?

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