Fig. 6

Comparative immunoblot assessment of sortilin relative to human β-amyloid precursor protein (APP) and phosphorylated tau (p-tau) protein products in transgenic mouse cortical extracts. Transgenic tissue homogenates are from the same age groups of amyloid precursor protein and presenilin 1 double-transgenic (APP/PS1), five familial Alzheimer’s disease mutations transgenic (5×FAD), and triple-transgenic Alzheimer’s disease (3×Tg-AD) mice used in histological studies, with lysates from adult C57BL/6 mice and from human patients with AD serving as controls. a and b Western blot images from one batch-processed set of samples. c1–c4 Quantitative summaries of the protein levels relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as an internal control, expressed as a percentage of GAPDH optical density (o.d.) for the groups (n = 4/group). Levels of the ~ 100 kDa sortilin band representing the full-length protein are comparable between the groups (a, c1). The ~ 15 kDa sortilin band is not readily seen in all mouse brain lysates, in contrast to the human tissue as positive control (a, c2). The human APP protein bands (~ 100 kDa) detected by the 6E10 antibody are distinct in the lysates from the three transgenic models and human cortex, but not in that of the C57BL/6 control (b, c3). Immunoblotted p-tau products migrate as a smear of bands (20–70 kDa), mostly abundant in the human lysates but clearly present in the 3×Tg-AD samples, with minimal amounts in the C57BL/6, APP/PS1, and 5×FAD samples (b, c4). Hash marks to the right of the immunoblot images indicate the band(s) used for densitometry. Statistical results (Kruskal–Wallis nonparametric test with Dunn’s multiple post hoc comparison) are shown in the bar graphs, with the asterisks indicating significant intergroup differences