Tripeptide IRW Upregulates NAMPT Protein Levels in Cells and Obese C57BL/6J Mice

• Published in: Journal of agricultural and food chemistry Vol. 69; no. 5; pp. 1555 - 1566
• Main Authors: Bhullar, Khushwant S, Son, Myoungjin, Kerek, Evan, Cromwell, Christopher R, Wingert, Bentley M, Wu, Kaiyu, Jovel, Juan, Camacho, Carlos J, Hubbard, Basil P, Wu, Jianping
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10.02.2021
• Subjects: Animals; Bioactive Constituents, Metabolites, and Functions; Cell Line; Cytokines - genetics; Cytokines - metabolism; Drosophila melanogaster; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Obese; NAD - metabolism; Nicotinamide Phosphoribosyltransferase - genetics; Nicotinamide Phosphoribosyltransferase - metabolism; Obesity - drug therapy; Obesity - genetics; Obesity - metabolism; Peptides - administration & dosage; NAD; peptides; metabolism; NAMPT; IRW
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.0c07831

Nicotinamide adenine dinucleotide (NAD+) plays a vital role in cellular processes that govern human health and disease. Nicotinamide phosphoribosyltransferase (NAMPT) is a rate-limiting enzyme in NAD+ biosynthesis. Thus, boosting NAD+ level via an increase in NAMPT levels is an attractive approach for countering the effects of aging and metabolic disease. This study aimed to establish IRW (Ile-Arg-Trp), a small tripeptide derived from ovotransferrin, as a booster of NAMPT levels. Treatment of muscle (L6) cells with IRW increased intracellular NAMPT protein levels (2.2-fold, p < 0.05) and boosted NAD+ (p < 0.01). Both immunoprecipitation and recombinant NAMPT assays indicated the possible NAMPT-activating ability of IRW (p < 0.01). Similarly, IRW increased NAMPT mRNA and protein levels in the liver (2.6-fold, p < 0.01) and muscle tissues (2.3-fold, p < 0.05) of C57BL/6J mice fed with a high-fat diet (HFD). A significantly increased level of circulating NAD+ was also observed following IRW treatment (4.7 fold, p < 0.0001). Dosing of Drosophila melanogaster with IRW elevated both D-NAAM (fly NAMPT) and NAD+ in vivo (p < 0.05). However, IRW treatment did not boost NAMPT levels in SIRT1 KO cells, indicating a possible SIRT1 dependency for the pharmacological effect. Overall, these data indicate that IRW is a novel small peptide booster of the NAMPT pool.