The 2009 Nobel Prize for Physiology or Medicine was awarded to three researchers in the U.S. "for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase" (for more information, see: http://nobelprize.org/nobel_prizes/medicine/laureates/2009/).
The research conducted by these scientists, is explained here from a recent scientific review of the current literature in this field (Shore and Bianchi EMBO J, 2009):
"The conventional DNA polymerase machinery is unable to fully replicate the ends of linear chromosomes. To surmount this problem, nearly all eukaryotes use the telomerase enzyme, a specialized reverse transcriptase that utilizes its own RNA template to add short TG-rich repeats to chromosome ends, thus reversing their gradual erosion occurring at each round of replication."
So, what does this mean??
The nuclei of each of our cells has an identical set of 26 pairs of chromosomes, or the tightly wound double-helices of our DNA (containing our genetic code). These chromosomes look like a 3-dimensional X when viewed under a powerful microscope. The tips of each arm of the X contain areas called the telomere.
When our cells divide, to create new cells for tissue growth or repair (a process called mitosis), the DNA contained in these chromosomes needs to be precisely replicated so each daughter cell contains an identical copy. The DNA is made of chemical 'bases' called nucleotides, referred to as their one-letter abbreviations (A, C, G, T). This annotation system allows the genetic code in our DNA to be read as a long sequence of these letters in various combinations (ie: ACTGCATGCAGT).
The telomere is a repeating sequence of TTAGGG, up to around 15,000 bases long. The telomere caps at the ends of the chromosomes prevent base pairs from being lost at the ends. These protective telomeres become shorter with each replication of our DNA when the cell divides, until the telomere disappears completely and the cell can no longer replicates, so it dies.
Telomerase (-ase being the common suffix for enzymes) is an enzyme which can elongate those telomeres, thereby increasing the life of a cell. Only certain cells, like in a growing fetus or in cancer cells, contain telomerase. Throughout development, our cells lose telomerase abilities.
From the Nobel committee press release: Elizabeth Blackburn and Jack Szostak discovered that a unique DNA sequence in the telomeres protects the chromosomes from degradation. Carol Greider and Elizabeth Blackburn identified telomerase, the enzyme that makes telomere DNA.
Some inherited disesases are due to telomerase defects, making research in this area important for developing potential therapies, and understanding cancer biology.
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Michael Steinberg
doctorwascher
Paul Hinrichs
Mary Elizabeth Williams
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Comments
Anyhoo, there's a lot of good science fiction out there that uses telomeres as a basis for creating 'immortal humans.' I wonder what your take is on that. Could these little discussed aspects of our genes be the key to immortality (barring death from social darwinist causes?)
Seriously, though - my understanding about telomeres and aging is that shorter telomeres are associated with people who live shorter lives - correlation but no causation yet. Its uncertain if extending telomeres with telomerase could extend a human life span (or life quality).
I did a little digging, and this site seems to give a good overview of some current aging/telomere research: http://learn.genetics.utah.edu/content/begin/traits/telomeres/
Its a hot area right now, which is usually the case for something that gets picked for a Nobel - sexy science with mass appeal and lots of promise for future work. (same for miRNAs, as you point out, too!)
I am not well read in science fiction, but I do find it fascinating how those writers cull from the current scientific literature to weave their stories...thanks for sharing!
Thank you for the link, btw, I'm going to check that out. As for the sexy science, that's always the way it goes, isn't it? I mean look at the stem cell thing. We have equally cool and well worth researching "organ manufacuring" printers out there, but no one pays attention to mechanical organ engineering because stem cell research is sexier.
MicroRNA will be hot for a while, then fade into obscurity, until we build a neural processing AI powerfull enough to simulate the human genome and come up with cures for every disease including the 'disease' of aging.
Again, thanks for the link and the reply. As for science fiction authors, we're all whores for new knowledge we can use to either whip people into a frenzy, scare the crap out of them or get them drooling over the impossible by leveraging the average persons general ignorance. Even the really good nuts-and-bolts sci-fi authors do it to an extent.
Then you've got guys like me that write sci-fi with just a sprinkle or two of truth on top of whole heaps of garbage science because in the end it's the story that is important. Real scientists will know the truth, johnny down the street doesn't really care, he just wants to see the hero win.