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

• DOI: 10.1021/acs.jafc.0c07831
• Publication Date: 2021-02-02T08:34:56Z
• Authors: Khushwant S. Bhullar; Myoungjin Son; Evan Kerek; Christopher R. Cr...; Bentley M. Wingert; Kaiyu Wu; Juan Jovel; Carlos J. Camacho; Basil P. Hubbard; Jianping Wu
• Keywords: Male; 0301 basic medicine; Tripeptide IRW Upregulates NAMPT Pr.; Chemical Sciences not elsewhere classified; Physiology; Mice, Obese; SIRT 1 KO cells; Biochemistry; Cell Line; Mice; 03 medical and health sciences; Genetics; Animals; Humans; Obesity; Nicotinamide Phosphoribosyltransferase; Molecular Biology; Obese C 57BL Mice Nicotinamide aden.; C 57BL mice; NAMPT levels; Computational Biology; Cell Biology; NAD; D-NAAM; 3. Good health; Mice, Inbred C57BL; Drosophila melanogaster; SIRT 1 dependency; Medicine; Cytokines; HFD; Peptides

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.