Fig. 1

The p110β-selective inhibitor GSK2702926A reduces elevated protein synthesis and Akt phosphorylation in Fmr1^KO mice. a, b Structures of GSK2636771 and GSK2702926A (a), and drug metabolism and pharmacokinetic properties of GSK2702926A (b), a highly selective and potent p110β antagonist. See Fig. S1 and Supplementary Materials and Methods for further details. c, d Intraperitoneal injection of 5 mg/kg GSK6A significantly reduces Akt phosphorylation at threonine 308 1.5 h after injection in hippocampal (c: two-way ANOVA with Tukey’s post hoc tests: p(drug) <0.0001, F(1,59) = 55.4; p(genotype) = 0.0015, F(1,59) = 11.0; p(interaction) = 0.059, F(1,59) = 3.7; *p = 0.002, ^#p < 0.0001) and cortical lysates (d: two-way ANOVA with Tukey’s post hoc tests: p(drug) = 0.0042, F(1,51) = 9.0; p(genotype) = 0.902, F(1,51) = 0.02; p(interaction) = 0.059, F(1,51) = 3.7; p(wt/veh-ko/veh) = 0.47, *p = 0.007). Phospho-Akt-specific signals were normalized to Akt; representative western blots are shown on top. Akt levels did not differ between groups (Fig. S2c, d). e A dose–response curve assessing the effect of a 30 min bath application of GSK6A on Akt phosphorylation in hippocampal slices from naïve WT and Fmr1^KO mice indicates that p110β-selective inhibition has a significantly stronger effect on Akt phosphorylation in Fmr1^KO hippocampus compared to WT (two-way ANOVA with repeated measures with Tukey’s post hoc tests: p(drug) < 0.0001, F(5,45) = 14.1; p(genotype) = 0.054, F(1,9) = 4.9; p(interaction) = 0.012, F(5,45) = 3.3; ^$p = 0.079). Phospho-Akt was normalized to Akt; representative western blots are shown on top. Further analysis of drug and genotype effects on Akt and S6 phosphorylation are shown in Figs. S2 and S3. f Treatment of hippocampal brain slices with 1 µM GSK6A for 30 min significantly reduced protein synthesis rates in Fmr1^KO, but not WT mice (two-way ANOVA with Tukey’s post hoc tests: p(drug) = 0.035, F(1,16) = 5.3; p(genotype) = 0.404, F(1,16) = 0.7; p(interaction) = 0.041, F(1,16) = 5.0; p(wt/veh-ko/veh) = 0.27, *p = 0.033). Puromycin-specific signal was normalized to β-tubulin and “no puromycin” background signal was subtracted. Representative western blots are shown at right and in Fig. S4a. FMRP-specific blots in c, d, and f (run on separate gels) confirm the genotype