Nobel Prize for scientists who shed light on chromosome protection

In collaboration with the Press Association

Three scientists who discovered the important role that the structures at the ends of chromosomes play in protecting genetic information have been awarded this year's Nobel Prize in Physiology or Medicine.

The prestigious award has gone to Elizabeth Blackburn, professor of biology and physiology at the University of California, San Francisco, Jack Szostak from Harvard Medical School and Carol Greider from Johns Hopkins University School of Medicine.

Elizabeth Blackburn and Jack Szostak discovered that chromosomes - the DNA-containing structures in cells that hold the human genome - are protected thanks to a unique DNA sequence in the telomeres - the 'caps' on the ends of chromosomes.

Professor Blackburn also worked with Carol Greider to identify telomerase, the enzyme that makes telomere DNA.

The discoveries solved a major problem in biology as the shortening of the telomeres speeds up cellular ageing. The reason for this cellular aging is that telomerase activity is absent from many human cells.

On the other hand, cells in which telomerase is very active maintain the length of their telomeres, meaning that the natural process of cell death is delayed, as is the case in cancer cells.

By shedding light on this fundamental cellular mechanism, the Nobel Prize winners opened up new avenues of research towards the development of new therapies for cancers and other aging-related diseases.

Early on in her research career, Professor Blackburn analysed DNA sequences and noticed a specific DNA sequence was repeated several times at the ends of chromosomes.

She then studied this sequence - now known as the telomere DNA sequence - with Professor Szostak, who became interested after seeing her presentation at a conference in 1980.

The pair's experiments revealed that the DNA sequence protects against chromosome degradation. Their studies were performed in single-celled organisms. However, the mechanisms they discovered are now known to occur in most plants and animals.

Professors Greider and Blackburn then started to search for the specialised enzyme that makes telomere DNA - leading to the discovery of telomerase, which extends telomere DNA and delays cellular ageing.

These studies led to further research showing that the telomere DNA sequence attracts proteins that form a protective cap around the ends of chromosomes.

A number of studies are now underway to find out whether it might be possible to treat cancer by removing telomerase or blocking its action.

Dr Julia Cooper, head of Cancer Research UK's Telomere Biology Laboratory at its London Research Institute, commented: "These scientists solved a fundamental mystery of how chromosomes ensure their own full replication - keeping the genetic information they contain intact.

"We know that a high proportion of human cancer tumours contain elevated levels of the telomerase enzyme.

"This groundbreaking work has led to the possibility of scientists one day being able to reset our cells' internal clocks to alleviate the effects of both ageing and cancer. If scientists could one day use drugs to manipulate this, it could have a significant impact on treating many cancers."