Dr. Guarente and his collaborator Dr. Cynthia Kenyon at the Department of Biochemistry and Biophysics, University of California San Francisco, have been tinkering with the SIR2 gene in yeast cells (which we use to make bread and wine) and in the roundworm. It turned out that the manipulated SIR2 gene controls lifespan in both species.
"They could add one extra copy of the gene and the yeast cells lived longer and the most amazing thing was that exactly the same thing was true in roundworms," says Guarente "Its important to us because the evolutionary difference between yeast and roundworms is vast. So if this same gene is regulating the longevity in these two very different organisms, chances are that it is universal and its effects would include us."
The P53 gene
The scientists have also found "a relationship between the mouse SIR2 gene, that is most similar to the yeast SIR2 gene and another gene known as the P53 gene." P53 is a well-known cancer suppressor gene. When cells get damaged, rather than develop into mutations and become tumors, P53 simply calls these cells to commit suicide.
The problem, Guarente says, is that P53 activity remains turned on later in life and it is possible that unwanted cell death later in life causes the degeneration of organs. But if SIR2 modulates and fine-tunes that cell death as we age, " its possible that SIR2 will be able to ultra-regulate the survivability of organs and the whole animal," he says.
By manipulating SIR2 to modulate the activities of P53, could cancer cells end up living and mutating when they would normally die? Guarente says there need not be a trade-off. He is hopeful that they can develop a drug that can slow down aging and yet not promote cancer.