Fig. 6.

Phosphorylation of mTau at Y18 is required for tau to modulate glutamate-induced excitotoxicity. a-d Neurons from Mapt ^−/− mice were transduced with lentiviral vectors expressing GFP-P2A or GFP-P2A-mTau constructs encoding a mTau^WT, b mTau^Y18F, c mTau^Y18E, or d mTau^AxxA7 on DIV7. Glutamate-induced neurotoxicity was assessed as in Figs. 1 and 2. Numbers of independent experiments (n) with cumulative well numbers per condition in parentheses: a 10 (71–80), b 7 (47–56), c 4 (29–32), and d 5 (29–40). When comparing mean differences across all doses within any given panel, a one-sided, one-sample t-test revealed significant differences between experimental and control conditions in (a, P < 0.01), (c, P < 0.01) and (d, P < 0.01), but not (b, P = 0.12). e Relative tau levels in vehicle-treated cultures from a–d were determined by western blot analysis with the pan-tau antibody EP2456Y. Mean tau levels in GFP-P2A-mTau^WT-expressing Mapt ^−/− cultures were arbitrarily defined as 1.0. One-way ANOVA revealed no significant differences in tau expression levels across cultures. Data are means ± SEM. f Mapt ^−/− neurons were transduced with lentiviruses encoding GFP-P2A-mTau^WT or GFP-P2A-mTau^Y18F on DIV7 and analyzed for NMDA-induced increases in intracellular Ca²⁺ in the presence of VGCC blocker cocktail on DIV 14 as in Fig. 3. Numbers of independent experiments (n) with cumulative well numbers per condition in parentheses: 4 (12). When comparing mean differences across all doses, a one-sided, one-sample t-test revealed significant differences between mTau^Y18F and mTau^WT (P < 0.01)