Nicotinamide mononucleotide (NMN) is a biosynthetic precursor of NAD+.
NAD+ tissue levels are associate with age – as we age NAD+ decreases.
It has been understood that supplementation with NMN increases NAD+.
However the route by which NMN is taken up by cells had not been clearly identified.
It has been generally considered that NMN could not directly enter a cell and that it had to be converted to NR first.
The Slc12a8 gene encodes for a specific NMN transporter, and this gene was highly expressed and regulated by NAD+ in the mouse small intestine.
Experiments have shown that Slc12a8 knockdown suppresses NMN uptake in vivo and in vitro.
It has also been identified that this specific transporter does not transport NR.Slc12a8 expression is 100-fold times higher in the small intestine than the brain of the mouse.
This also suggests that different cells and organs may use different amounts and types of NAD+ precursors.
This ground-breaking study is another interesting development in the NAD+ world.
It clarifies that NMN supplementation may also be highly effective in rejuvenation therapy.