Baker’s yeast is one of the most studied and best understood organisms at the molecular and genetic level. Despite its genetic simplicity, yeast has led to the discovery of important genes and pathways regulating aging and diseases in some mammals.
A research group at the University of Southern California, led by Professor Walter Longo, has genetically engineered baker’s yeast capable of living 10-times longer than normal yeast, without apparent side effects. This accomplishment was achieved through a combination of dietary and genetic changes, as Longo’s group put the yeast on a calorie-restricted diet and knocked out two of its genes. The two genes, RAS2 and SCH9, are known to promote aging in yeast and cancer in humans.
In a related research project, Longo’s team managed to develop a yeast model for human Werner/Bloom syndromes, incurable diseases that cause premature aging, increase cancer incidence, and eventually kill their victims. This study showed that the genetic changes that play a central role in the 10-fold life span extension in yeast also reverse the course of the accelerated aging syndromes. Therefore, Longo suggested that existing drugs, which target analogous anti-aging pathways in humans, should be considered for testing on Werner/Bloom patients.
The scientists plan to investigate life span extension in mice and are also studying a human population in Ecuador with mutations analogous to those described in yeast. Professor Longo cautions that these longevity mutations tend to be accompanied by severe growth deficits and health problems, so that the main challenge is to find drugs that extend the human life span without side effects. “People with two copies of the mutations have very small stature and other defects. We are now identifying the relatives with only one copy of the mutation, who are apparently normal. We hope that they will show a reduced incidence of diseases and an extended lifespan.”, he says.
In another research project, scientists recently demonstrated that a mouse with a gene mutation first identified by Longo’s team lived 30 percent longer than the average mouse. The mouse was also protected against heart and bone diseases without any apparent side effects.
Although the baker’s yeast used in Longo’s experiments is a very simple system, these studies have brought science closer to controlling the survival and health of the basic unit of all living organisms: the cell. The NIA (part of the U.S. National Institutes of Health) funds research projects of this kind, with the intent of extending humans’ health and life spans through the development of drugs that mimic natural life-prolonging techniques.
More information about Professor Longo and his team’s research studies is available at the USC news webpage.