Flies that are being fed an "anti-Atkins" low protein diet live more because their mitochondria work better, a recent study suggests. The project, completed at the Buck Institute for Age Research, reveals that the molecular mechanisms that control longevity in flies can be useful for understanding the human aging process as well as diseases like cancer, obesity, and diabetes.
Mitochondria, known as the "powerhouse" of cells, is the place where enery is produced. It is known that mitochondrial function weakens as people get older but also in conditions such as obesity and Type II diabetes. "Our study shows that dietary restriction can enhance mitochondrial function hence offsetting the age-related decline in its performance," said Buck faculty member Pankaj Kapahi, PhD, principal investigator of the project.
The study shows how dietary restriction influences protein expression in organisms. The authors reveal the surprising discovery that while there is a decrease in protein synthesis all around in the body with a low protein diet, the activity of genes responsible for creating energy in the mitochondria is elevated. That process, which happens at the point of transcription of RNA to protein, can explain the protective effects of dietary restriction.
The study describes a novel mechanism for how mitochondrial genes are translated from RNA to protein by a specific protein (d4EBP). Insect fed a low protein diet revealed an increase in activity of d4EBP, which is part of a signaling cascade that controls cell growth in reaction to nutrient supply known as TOR (target of rapamycin). The research stated that d4EBP is required for lifespan increase upon dietary restriction. When researchers eliminated the activity of the protein genetically they noticed that the insects lived less, even when given the low protein diet. When, in contrast, they increased the activity of d4EBP, longevity was increased, even when the insects had a protein-rich diet.
The point is that the study raises concerns about the health benefits of high-protein diets that are often used by people who want to reduce their weight. The long-term effects of these high protein diets have not been investigated in people and they could be harmful. Kapahi explained: "In flies, we see that the long-lived diet is a low protein diet and what we have found here is a mechanism for how that may be working"