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. Author manuscript; available in PMC: 2019 Mar 6.
Published in final edited form as: Cell Metab. 2018 Mar 6;27(3):667–676.e4. doi: 10.1016/j.cmet.2018.02.001

Figure 4. Impact of NAM supplementation on hepatic NAD+ metabolome and the NAMPT-NAD-SIRT1 pathway.

Figure 4

(A) Scatter plots depicting densitometric analysis after normalization of SIRT1 and NAMPT immunoblots to Ponceau S staining of the membrane, n=4/group. (B) Scatter plot displaying the association between NAMPT and SIRT1 protein expression. (C) Densitometric analysis after normalization of IDO, NMNAT1 and NADS immunoblots to Ponceau S staining of the membrane. Bars represent the average ± SEM (n=6). (D) Histograms show the relative tryptophan levels in serum metabolome. *, p<0.05; **, p<0.01; ***, p<0.001. (E) Heatmap illustrates the log2(fold change) values of 13 metabolites from the NAD-related pathway analysis that was evaluated after data normalization with median fold change in each group. (F) Diagram depicting the effect of dietary supplementation of NAM on the liver NAD+ biosynthetic, salvage, and catabolic pathways. Abbreviations: AOX, aldehyde oxidase 1; IDO, indoleamine-pyrrole 2,3-dioxygenase 1; Me-2-py, N-methyl-2-pyridone-5-carboxamide; Me-4-py, N-methyl-4-pyridone-5-carboxamide; MeNAM, methylnicotinamide; NAAD, nicotinic acid adenine dinucleotide; NAD+/NADH, oxidized/reduced nicotinamide adenine dinucleotide; NADP+/NADPH, oxidized/reduced nicotinamide adenine dinucleotide phosphate; NADS, nicotinamide adenine dinucleotide synthase; NAM, nicotinamide; NAMN, nicotinic acid mononucleotide; NAMPT, nicotinamide phosphoribosyltransferase; NMN, nicotinamide mononucleotide; NMNAT, nicotinamide/nicotinic acid mononucleotide adenyltransferase; NNMT, NAM N-methyltransferase; NR, nicotinamide riboside; QA, quinolinic acid; SIRT1, sirtuin 1; Trp, tryptophan. (See also Figures S3, S4).