SIRT1: regulation of longevity via autophagy.

Recent studies have emphasized the importance of SIRT1, a mammalian homolog of Sir2 longevity factor, in the regulation of metabolism, cellular survival, and organismal lifespan. The signaling network interacting with SIRT1 continues to expand as does the number of functions known to be regulated by SIRT1. Autophagy is also an emerging field in longevity studies. Autophagocytosis is a housekeeping mechanism cleaning cells from aberrant and dysfunctional molecules and organelles. The extension of lifespan has been linked to the efficient maintenance of autophagic degradation, a process which declines during aging. Interestingly, recent observations have demonstrated that SIRT1 regulates the formation of autophagic vacuoles, either directly or indirectly through a downstream signaling network. We will examine the signaling pathways linking SIRT1 to the regulation of autophagic degradation. The interactions of SIRT1 with the FoxO and p53 signaling can also regulate both the autophagic degradation and lifespan extension emphasizing the key role of autophagy in the regulation of lifespan.