Fig. 2: NAD⁺ supplement slashes hyperphosphorylated tau and Aβ peptide in vitro.

NMN restores Aβ expression in N2a APPswe cells and inhibits tau hyperphosphorylation in HEK293 cells Tau P301L after supplementing with either VEH or 500 μm NMN for 24 h. a Cell viability results of N2a mouse neuroblastoma cells and overexpressing Swedish K595N and M596L mutations cells depicting a dose-dependent NMN effect. Data were analyzed by one-way ANOVA followed by Sidak’s multiple comparisons test. b Representative confocal images showing the APP level of the NMN-treated N2s cells. Data were analyzed by a two-sided unpaired t-test. Scale bar, 25 μm. c, e–i SDS-PAGE, and corresponding quantification of APP and its indicated protein expressions indicating NMN effects. Data were analyzed by two-sided one-way ANOVA followed by Tukey’s multiple comparisons test. d, j, k, m Representative 3D reconstruction images and corresponding quantification of colocalization of Tau5, tau-Thr²¹⁷ and CTSD. Scale bar, 10 μm. l, n–r Effects of NMN on the expression levels of different p-Tau sites (Thr181, Thr231, Thr217, AT8, and Ser396) in HEK293 cells Tau P301L. s The total Tau level change between NMN-treated and non-treated group. Data were analyzed by two-sided one-way ANOVA followed by Tukey’s multiple comparisons test. At least three experiments were repeated independently with similar results. Full scans of all the blots are in the Supplementary Data. All experiments were performed independently with at least three biological replicates. Data are shown as mean ± s.e.m. The p-values are indicated on the graphs. ns not significant.