NRK1 controls nicotinamide mononucleotide and nicotinamide riboside metabolism in mammalian cells

Raising cellular levels of the metabolic cofactor NAD+ reverses key indicators of aging. Here, Ratajczak et al. show that cellular levels of NAD+ depend on the extracellular catalytic activity of NRK1, which processes two NAD+ precursors, nicotinamide mononucleotide and nicotinamide riboside, in mice.