Fig. 7

Reducing SynGAP1 levels in tau^−/− mice reinstates susceptibility to seizures and ERK activation. a Neonatal (P1-3) wild-type C57Bl/6 mice were injected intracranially with AAVs expressing either shRNA to knockdown SynGAP1 (AAV-SG1-shR) or control shRNA (AAV-ctr-shR). Western blotting of cortical extracts from 2-month-old naive (ctr) and AAV-injected mice showed marked reduction of SynGAP1 levels in AAV-SG1-shR-injected mice. Quantification of band intensities confirmed significant SynGAP1 reduction by AAV-SG1-shR (**p < 0.01; N = 9; one-way ANOVA (Tukey post hoc)). b Example of GFP reporter expression in neurons throughout the cortex of AAV-SG1-shR-injected mice. Double labeling with a SynGAP1 antibody (red) revealed SynGAP1 expression in areas with no GFP expression and marked reduction of SynGAP1 in GFP-positive areas, suggesting efficient knockdown. Higher magnification of areas with neuronal and synaptic SynGAP1, but no GFP expression (middle), or neuronal GFP reporter expression with reduced SynGAP1 (right). Scale bars, 100 µm. c AAV-SG1-shR, but not AAV-ctr-shR injection increased the mean seizure severity in tau^−/− mice after administration of 50 mg/kg PTZ (*p < 0.05; ***p < 0.001; N = 11 (tau^−/−), N = 13 (AAV injected tau^−/−); one-way ANOVA (Tukey post hoc)). d More tau^−/− mice injected with AAV-SG1-shR developed higher degree seizures after administration of 50 mg/kg PTZ, compared with naive (ctr) or AAV-ctr-shR-injected tau^−/− mice. The latency of seizure progression was comparable. e Strong ERK1/2 phosphorylation 10 min after 50 mg/kg PTZ administration in AAV-SG1-shR-injected, but not AAV-ctr-shR-injected or naive (ctr) tau^−/− mice, together with reduction of SynGAP1 levels. Detection of ERK1/2 and Gapdh confirmed equal loading. All error bars are s.e.m