Originally published December 3 2005
USC study reverses earlier thinking about the role one gene plays in the aging process
by Mike Adams, the Health Ranger, NaturalNews Editor
Molecular geneticists at the University of Southern California have disproved earlier findings that a gene known as SIR2 promotes longevity by removing the gene from cells, which resulted in a significant lifespan extension.
That finding was covered widely and incorporated into anti-aging drug development programs at several biotechnology companies.
Now, molecular geneticists at the University of Southern California suggest that SIR2 instead promotes aging.
Rather than adding copies of SIR2 to yeast, Longo's research group deleted the gene altogether.
The result was a dramatically extended life span - up to six times longer than normal - when the SIR2 deletion was combined with caloric restriction and/or a mutation in one or two genes, RAS2 and SCH9, that control the storage of nutrients and resistance to cell damage.
Human cells with reduced SIR2 activity also appear to confirm that SIR2 has a pro-aging effect, Longo said, although those results are not included in the Cell paper.
Longo proposes that SIR2 and possibly its counterpart in mammals, SIRT1, may block the organism from entering an extreme survival mode characterized by the absence of reproduction, improved DNA repair and increased protection against cell damage.
The long-lived organisms in Longo's experiment showed extraordinary resilience under stress.
Longo predicted that as molecular geneticists master the levers of aging, they will be able to design drugs that coax the body into entering chosen aspects of a starvation-response mode, such as stress resistance, even when food is plentiful.
All organisms have the ability to repair harmful mutations in their DNA, whether caused by age, radiation, diet or other environmental factors.
Joining with researchers at the USC Norris Comprehensive Cancer Center, Longo is studying the feasibility of reducing or preventing the age-dependent DNA mutations that cause cancer.
Guarente was the first to show that over-expression of the SIR2 gene could extend life span beyond its natural limit.
However, Longo said, "We were convinced that SIR2 had the potential to be a more potent pro-aging than an anti-aging gene.
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