Tuesday, June 15, 2010

Telomere Size Matters

A telomere is a repeating sequence of DNA that is located at the ends of chromosomes in most eukaryotic organisms, and they are usually composed of arrays of guanine-rich, six-to-eight base-pair-long repeats (ex: TTAGGG in vertebrates). They function kind of like buffers or endcaps, they prevent chromosomes from losing their base pair sequences and from fusing to each other. They can reach about 15,000 base pairs long but a little bit of that length is lost each time a cell divides. When the telomere becomes too short the cell cannot replicate and undergoes apoptosis (cell death).

A new study at the University of Leicester is looking at telomeres and how their length, particularly shortening, is controlled. Espcially as it relates to ageing and the development of cancer.
Telomere shortening can be reversed in two ways:
(1) Telomerase, also called telomere terminal transferase, is an enzyme made of protein and RNA subunits that elongates chromosomes by adding TTAGGG sequences to the ends.
(2) A method in which information is copied from one telomere to another (not well understood)

The scientists in this study say that one of these methods must be activated during cancer development, and they are studying the ways that changes in the structure of DNA may control this shortening process.

This is a study that is in its early stages and so I don't have a reference for you, just a write-up in Science Daily, but its an interesting story that should get you thinking about understanding this relatively mysterious part of our DNA.

Here's the story:
http://www.sciencedaily.com/releases/2010/06/100609102056.htm
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