Project description: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.
Project description:In the present study, we developed a chemical method to produce dihydro nicotinamide mononucleotide (NMNH), which is the reduced-form of nicotinamide mononucleotide (NMN). We demonstrated that NMNH was a better nicotinamide adenine dinucleotide (NAD+) enhancer compared to NMN both in vitro and in vivo mediated by mononucleotide adenylyltransferase (NMNAT). Additionally, NMNH increased the reduced NAD (NADH) levels in cells and in mouse liver. Metabolomic analysis revealed that NMNH inhibited glycolysis and TCA cycle. In vitro experiments demonstrated that NMNH induced cell cycle arrest and suppressed cell growth. Nevertheless, NMNH treatment did not cause observable difference in mice. Taken together, our work demonstrates that NMNH is a potent NAD+ enhancer, and suppresses glycometabolism and cell growth.
Project description:Type 2 diabetes (T2D) has become an epidemic in our modern lifestyle, likely due to calorie-rich diets overwhelming our adaptive metabolic pathways. One such pathway is mediated by nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in mammalian NAD+ biosynthesis, and the NAD+-dependent protein deacetylase SIRT1. Here we show that NAMPT-mediated NAD+ biosynthesis is severely compromised in metabolic organs by high-fat diet (HFD). Strikingly, nicotinamide mononucleotide (NMN), a product of the NAMPT reaction and a key NAD+ intermediate, ameliorates glucose intolerance by restoring NAD+ levels in HFD-induced T2D mice. NMN also enhances hepatic insulin sensitivity and restores gene expression related to oxidative stress, inflammatory response, and circadian rhythm, partly through SIRT1 activation. Furthermore, NAD+ and NAMPT levels show significant decreases in multiple organs during aging, and NMN improves glucose intolerance and lipid profiles in age-induced T2D mice. These findings provide critical insights into a novel intervention against diet- and age-induced T2D. 4 regular chow fed mice (RC1-4) vs 4 high-fat diet fed (HFD) (HFD1a-4a) mice were analyzed on one chip (Chip-A). 4 HFD mice (HFD1b-4b) vs 4 HFD-NMN treated mice (NMN1-4) were examined on the other chip (Chip-B).
Project description:Studies in rodents have shown obesity and aging impair tissue nicotinamide adenine dinucleotide (NAD+) biosynthesis, which contributes to metabolic dysfunction. The availability of nicotinamide mononucleotide (NMN) is an important rate-limiting factor in mammalian NAD+ biosynthesis. We conducted a 10-week, randomized, placebo-controlled, double-blind trial to evaluate the effect of NMN supplementation on metabolic function in 25 postmenopausal women with prediabetes who were overweight/obese. Insulin-stimulated glucose disposal, assessed by using the hyperinsulinemic-euglycemic-clamp procedure, increased by 25±7% (P<0.01) in the NMN group, which was accompanied by an increase in insulin-stimulated phosphorylation of muscle AKT (P<0.01), whereas neither outcome changed after placebo treatment. Body composition (fat mass, fat-free mass, intra-abdominal fat, intrahepatic triglyceride content) and muscle mitochondrial respiratory capacity did not change after treatment with placebo or NMN. These results demonstrate NMN improves muscle insulin sensitivity in women with prediabetes who are overweight/obese, independent of changes in body composition or mitochondrial function.
Project description:Doxorubicin (DOX) is the cornerstone of chemotherapy regimens for many malignancies, but its clinical usage is limited by severe cardiotoxicity. Accumulating evidence suggest that nicotinamide adenine dinucleotide (NAD+) depletion contributes to DOX-induced cardiotoxicity, making NAD+ boosting an appealing strategy. Nicotinamide mononucleotide (NMN) is an NAD+ precursor that shows promising therapeutic effects in various diseases. To understand the impact of NMN on gene expression in myocardial tissue of DOX-exposed mice, a RNA-seq assay was carried out.
Project description:NAD+ availability decreases with age and in certain disease conditions. Nicotinamide mononucleotide (NMN), a key NAD+ intermediate, has been shown to enhance NAD+ biosynthesis and ameliorate various pathologies in mouse disease models. In this study, we conducted a 12 month-long NMN administration to regular chow-fed wild-type C57BL/6N mice during their normal aging. Orally administered NMN was quickly utilized to synthesize NAD+ in tissues. Remarkably, NMN effectively mitigates age-associated physiological decline in mice. Without any obvious toxicity or deleterious effects, NMN suppressed age-associated body weight gain, enhanced energy metabolism, promoted physical activity, improved insulin sensitivity and plasma lipid profile, and ameliorated eye function and other pathophysiologies. Consistent with these phenotypes, NMN prevented age-associated gene expression changes in key metabolic organs and enhanced mitochondrial oxidative metabolism and mitonuclear protein imbalance in skeletal muscle. These effects of NMN highlight the preventive and therapeutic potential of NAD+ intermediates as effective anti-aging interventions in humans.
Project description:Type 2 diabetes (T2D) has become an epidemic in our modern lifestyle, likely due to calorie-rich diets overwhelming our adaptive metabolic pathways. One such pathway is mediated by nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in mammalian NAD+ biosynthesis, and the NAD+-dependent protein deacetylase SIRT1. Here we show that NAMPT-mediated NAD+ biosynthesis is severely compromised in metabolic organs by high-fat diet (HFD). Strikingly, nicotinamide mononucleotide (NMN), a product of the NAMPT reaction and a key NAD+ intermediate, ameliorates glucose intolerance by restoring NAD+ levels in HFD-induced T2D mice. NMN also enhances hepatic insulin sensitivity and restores gene expression related to oxidative stress, inflammatory response, and circadian rhythm, partly through SIRT1 activation. Furthermore, NAD+ and NAMPT levels show significant decreases in multiple organs during aging, and NMN improves glucose intolerance and lipid profiles in age-induced T2D mice. These findings provide critical insights into a novel intervention against diet- and age-induced T2D.
Project description:To investigate the effect of nicotinamide mononucleotide (NMN) on CD4+ T cells, primary human CD4+ T cells purified from peripheral blood mononuclear cells of healthy donors were treated without or with NMN. Expression profiling analysis on either host gene or viral gene was performed using data obtained from bulk RNA-seq of NMN-treated and untreated (control) CD4+ T cells at 48 hours post treatment and/or post infection.