Caloric restriction augments ROS defense in S. cerevisiae, by a Sir2p independent mechanism.

Aging is associated with increased production of reactive oxygen species (ROS) and oxidation-induced damage to intracellular structures and membranes. Caloric restriction (CR) has been demonstrated to delay aging in a variety of species. Although the mechanisms of CR remain to be clearly elucidated, reductions in oxidative damage have been shown to increase lifespan in several model systems. Contrary to the general belief that ROS production is reduced in CR, this article provides evidence that not only oxygen consumption but ROS production is enhanced in the calorie restricted condition. To understand the biological mechanism underlying the anti aging action of CR, the role of scavenging enzymes was studied. It was found that super oxide dismutase (SOD1 and SOD2), catalase and glutathione peroxidase (GPx) all are over expressed in CR. We further investigated the role of Sir2, a potential effector of CR response in the activation of scavenging enzymes. No marked difference was found in CR mediated activation of SOD and catalase in the absence of Sir2. Our results suggest that in CR scavenging enzymes are activated by a Sir2 independent manner.