Fig 2: Cell-based assay in heterologous COS7 cell. Confocal imaging of COS7 cells transfected with rat GluA3-GFP (green) and incubated with a GluA3 commercial antibody (upper panels), CSF+ (middle panels) or CSF- (lower panels) for the staining of GluA3 (red). Dapi was used to recognize cell nuclei (blue). Merge panels are shown on the right. Scale bar, 10 µm.

Fig 3: Brain atrophy in FTD patients with GluA3 antibodies. MRI scans were available in 18 FTD patients with anti-GluA3 antibodies (age: 62.4 ± 6.7, gender F: 38.9%) and were compared to 42 healthy controls (age: 61.0 ± 9.1, gender F: 66.7%) (SPM12 software package Wellcome Department of Imaging Neuroscience, London; http://www.fil.ion.ucl.ac.uk/spm). Statistical threshold was set at p < 0.05, Family Wise Error (FWE) corrected, with a minimum cluster size of 50 voxels.

Fig 4: Neurobiological effect of GluA3 antibodies in neurons differentiated from human iPSCs. (A) WB analysis from homogenates and triton-insoluble postsynaptic fractions (TIF) of neurons differentiated from human iPSC and incubated for 24 hours with CSF with (CSF+) or without (CSF-) anti-GluA3 antibodies (dilution 1:100). (B,C) The histogram shows the quantification of the expression levels of GluA3, GluA1 and PSD-95 in homogenate (B) and TIF (C), normalized on tubulin and expressed as % of CSF-. N = 5 ***p < 0.001, unpaired Student’s t-test.

Fig 5: Neurobiological effect of GluA3 antibodies in primary rat neurons. (A) Fluorescence immunocytochemistry of GluA3 (green), PSD-95 (red) and MAP2 (blue) in DIV14 neurons treated with CSF with (CSF+) or without (CSF-) anti-GluA3 antibodies at two different dilutions (1:20 and 1:100) for 24 hours. Scale bar, 5 µm. (B) Bar graph representing the percentage of co-localization of GluA3 with PSD-95. Data are presented as mean ± s.e.m, n = 14, one-way ANOVA followed by Tukey as post hoc test; *p < 0.05, **p < 0.01, ***p < 0.001. (C) Bar graph representing the density of GluA3 positive cluster along dendrites. Data are presented as mean ± s.e.m., n = 14, one-way ANOVA followed by Tukey as post hoc test. (D) Confocal images of rat primary hippocampal neurons transfected at DIV8 with GFP and immunolabeled at DIV14 for GFP (green). Scale bar: 5 µm. (E), Bar graph showing the quantification of dendritic spine density. Data are presented as mean ± s.e.m., n = 6–8, one-way ANOVA followed by Tukey as post hoc test; *p < 0.05, **p < 0.01, ***p < 0.001.