Slc12a8 is a nicotinamide mononucleotide transporter that counteracts aging. Slc12a8 is a nicotinamide mononucleotide transporter that counteracts aging

NAD+ levels decline in multiple tissues over age, causing various age-associated pathophysiologies. Nicotinamide mononucleotide (NMN) is a key NAD+ intermediate that promotes NAD+biosynthesis and counteracts age-associated physiological decline. However, how NMN transport is regulated remains unknown. Here we report a novel NMN transporter encoded by the Slc12a8 gene. Slc12a8 is highly expressed and regulated by NAD+ in the small intestine. Knocking down this gene abrogates the transport of NMN in vitro and in vivo. Slc12a8 exhibits specificity to NMN and dependency on the sodium ion. Slc12a8 deficiency significantly decreases NAD+ levels in the jejunum and ileum, due to decreases in NMN uptake traced by doubly labeled isotopic NMN. Slc12a8 expression is upregulated in the aged ileum, contributing to the maintenance of NAD in aged mice. Thus, this newly identified NMN transporter plays a critical role in counteracting NAD+ decline during aging. Overall design: To evaluate the effects of NAD depletion induced by FK866 treatment, we conducted microarray analyses and compared global gene expression profiles in control (DMSO 0.1%) and FK866-treated primary hepatocytes/islets.