The controversial links among calorie restriction, SIRT1, and resveratrol

It has been widely known that slow metabolism induced by calorie restriction (CR) can extend the life span of model organisms though the underlying mechanism remains poorly understood. Accumulated evidence suggests that SIRT1 may be actively involved in CR-induced signaling pathways. As a putative activator of SIRT1, resveratrol, known for the French paradox, can partially mimic the physiological effects of CR. While the deacetylase activity of SIRT1 is important for the beneficial effects of resveratrol, resveratrol-induced SIRT1 activation has recently been challenged by the observations that resveratrol could not induce SIRT1-mediated deacetylation of native substrates in vitro. To resolve the discrepancy of resveratrol-induced activation of SIRT1 deacetylase activity between the in vitro and in vivo assays, a model of indirect SIRT1 activation by resveratrol is proposed. In this review, we will discuss the emerging roles of SIRT1 and resveratrol in CR and focus on debate over the links between SIRT1 and resveratrol.