Discoveries of nicotinamide riboside as a nutrient and conserved NRK genes establish a Preiss-Handler independent route to NAD+ in fungi and humans.
Cell
confidence
Key findings
Identified nicotinamide riboside as an NAD+ precursor and conserved NRK genes establishing a Preiss-Handler independent route to NAD+ in fungi and humans.
View source on PubMed (PMID 15137942) ↗
- Sample size
- Not applicable
- Population
- Yeast and humans (basic biochemistry/genetics study)
- Dosing
- Not applicable
- Duration
- Not applicable
- Route
- Not applicable
- Blinding
- not_reported
- Controls
- none
- Drug class
- coenzyme
Full abstract
NAD+ is essential for life in all organisms, both as a coenzyme for oxidoreductases and as a source of ADPribosyl groups used in various reactions, including those that retard aging in experimental systems. Nicotinic acid and nicotinamide were defined as the vitamin precursors of NAD+ in Elvehjem's classic discoveries of the 1930s. The accepted view of eukaryotic NAD+ biosynthesis, that all anabolism flows through nicotinic acid mononucleotide, was challenged experimentally and revealed that nicotinamide riboside is an unanticipated NAD+ precursor in yeast. Nicotinamide riboside kinases from yeast and humans essential for this pathway were identified and found to be highly specific for phosphorylation of nicotinamide riboside and the cancer drug tiazofurin. Nicotinamide riboside was discovered as a nutrient in milk, suggesting that nicotinamide riboside is a useful compound for elevation of NAD+ levels in humans.