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. 2015 Jun 8;10(6):e0129047. doi: 10.1371/journal.pone.0129047

Fig 4. Deletion of GGA GAT and GAE but not VHS domain increases secretion of APP β-cleavage products.

Fig 4

N2A cells were co-transfected with APP-GFP and BACE1-HA and either GGA1, 2, or 3_wt-myc or domain deletion mutants. After 24 h, sAPP and Aβ levels were measured in the conditioned media by using sAPP and Aβ ELISA kits (MesoscaleDiscovery). As shown previously, secretion of sAPPα and β were reduced in cells overexpressing GGA1, 2, or 3 _wt or-ΔVHS compared with controls (left panels). Additionally, Aβ40 and Aβ42 levels were also reduced in cells co-expressing GGA_wt or-ΔVHS. Deletion of the GGA-GAT domain completely abolished the effect of sAPPs as well as Aβ secretion. Deletion of the GGA1 GAE domain but not GGA2 or 3 significantly increased sAPPβ levels compared with that of GGA_wt. Likewise, Aβ levels were increased for all three GGA GAE mutants, indicating altered APP processing due to altered BACE1-GGA interaction. Experiments were carried out in triplicate; shown are the results of n = 3 independent experiments. Statistical analysis was performed by using Kruskal-Wallis ANOVA on ranks and multiple comparison (Dunn’s method) (*p<0.05).