The NAD World: a new systemic regulatory network for metabolism and aging--Sirt1, systemic NAD biosynthesis, and their importance

Cell Biochem Biophys. 2009;53(2):65-74. doi: 10.1007/s12013-008-9041-4.


For the past several years, it has been demonstrated that the NAD-dependent protein deacetylase Sirt1 and nicotinamide phosphoribosyltransferase (Nampt)-mediated systemic NAD biosynthesis together play a critical role in the regulation of metabolism and possibly aging in mammals. Based on our recent studies on these two critical components, we have developed a hypothesis of a novel systemic regulatory network, named "NAD World", for mammalian aging. Conceptually, in the NAD World, systemic NAD biosynthesis mediated by intra- and extracellular Nampt functions as a driver that keeps up the pace of metabolism in multiple tissues/organs, and the NAD-dependent deacetylase Sirt1 serves as a universal mediator that executes metabolic effects in a tissue-dependent manner in response to changes in systemic NAD biosynthesis. This new concept of the NAD World provides important insights into a systemic regulatory mechanism that fundamentally connects metabolism and aging and also conveys the ideas of functional hierarchy and frailty for the regulation of metabolic robustness and aging in mammals.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Aging / metabolism*
  • Animals
  • Humans
  • NAD / biosynthesis*
  • NAD / metabolism*
  • Nicotinamide Phosphoribosyltransferase / metabolism
  • Sirtuins / metabolism*


  • NAD
  • Nicotinamide Phosphoribosyltransferase
  • Sirtuins