Fig. 5: Youthful-like hepatic TCA cycle, GNG, and redox metabolite levels in old SIRT6-tg.

a Lists of statistically significant metabolites from each of the four comparisons shown were used to create Venn diagram. The number of significant metabolites in each comparison is shown in parentheses. b PCA of significantly changed metabolites. Each dot represents one biological replicate. c Heatmap of significantly changed metabolites. Each square represents average metabolite abundance of n = 5 mice per genotype. TSP, transsulfuration pathway; Y, young; O, old; WT, wild type; TG, transgenic. d–f Scatterplots showing metabolite levels of hepatic glycolysis/GNG (d), TCA cycle (e), and redox metabolism (f) pathways. n = 5 mice per genotype, each dot represents one mouse. g Expression of key NAD⁺ de novo synthesis genes in the liver of young and old WT and SIRT6-tg mice. Asterisks indicate values significantly different between WT and SIRT6-tg at the same age. n = 8 mice for young WT, young SIRT6, and old SIRT6 (for Haao in young SIRT6, n = 7); and n = 7 mice for old WT (for Nmnat1, n = 8), males. RQ, relative quantity. h Protein levels of NMNAT1 (n = 5 mice) and TDO2 (n = 7 mice) in livers of old WT and SIRT6-tg littermates. ImageJ quantification of NMNAT1 normalized to α-tubulin and TDO2 normalized to ponceau is shown in the right. For all panels, mice were at the ages of 5–7 months (young) and 20–24 months (old). Bars represent mean ± SEM. For (d–g) data were analyzed using two-way ANOVA, for (h) using two-tailed Student’s t-test. Exact p-values are reported in the Source Data file. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001.