Telomerase is an enzyme that maintains the DNA at the ends of our chromosomes, known as telomeres. In the absence of telomerase activity, every time our cells divide, our telomeres get shorter. This is part of the natural aging process, as most cells in the human body do not have much active telomerase. Eventually, these DNA-containing telomeres, which act as protective caps at the ends of chromosomes, become so short that the cells die.
But in some cells, such as cancer cells, telomerase, which is composed of RNA and proteins, is highly active and adds telomere DNA, preventing telomere shortening and extending the life of the cell.
UCLA biochemists have now produced a three-dimensional structural model of the RNA "core domain" of the telomerase enzyme. Because telomerase plays a surprisingly important role in cancer and aging, understanding its structure could lead to new approaches for treating disease, the researchers say.
"We still do not know how the RNA and the proteins cooperate to do this magical thing -- extend the ends of our telomeres -- but we are now one step closer to understanding that," said Juli Feigon, a UCLA professor of chemistry and biochemistry and senior author of the research, which was published Nov. 2 in the print edition of the Proceedings of the National Academy of Sciences (PNAS).
The critical telomerase RNA core domain is essential for telomerase to add telomere repeats onto the ends of chromosomes, the structures that hold our genes. The core domain contains the template that is used to code for the ends of the chromosomes.
"Telomerase is the most amazing complex," said Feigon, who began studying telomere DNA structure in the early 1990s, which led to her interest in telomerase. "Some people think if we activate telomerase, we can live forever. However, we don't want our cells to be able to divide indefinitely. As they get older and older, they accumulate all k
|Contact: Stuart Wolpert|
University of California - Los Angeles