Fig. 3: MITOL deletion elevates the seeding activity of Aβ plaques.

a–c MITOL deletion did not alter APP processing. mRNA was extracted from the hippocampus of indicated mice at 15 months of age and then analyzed by qRT-PCR (a). The hippocampal lysates of indicated 15-months old mice were immunoblotted with indicated antibodies (b, c). Error bars indicate ±SE (a: n = 4–5, c: n = 7). n.s.: not significant (Student’s t test). d–h MITOL deletion induced the formation of high-dense Aβ plaques with extended fibrillized core. Brain sections from indicated mice at 15 months of age were immunostained with anti-Aβ antibody 6E10 and Thioflavin S (ThS) (d). The lower panels show high-magnification images of the boxed regions. Scale bar represents 50 µm. The number and area of the overall region (Aβ-positive area), in addition to the size of the ThS-positive area, were calculated using ImageJ (e–g). Error bars indicate ±SE (e–g: n = 4–5). ***p < 0.001, n.s.: not significant (Student’s t test). h The fibrillized region in Aβ plaque was extended by MITOL deletion. The anti-Aβ antibody 6E10-stained area and ThS-stained area of each Aβ plaque were plotted in the scatter plot. Spearman’s rank correlation coefficient (R) indicates the strength of a relationship between the total area and the cored area of Aβ plaque (n = over 300). The rate of core region in Aβ plaques was represented by the slope of the best-fitting line for the scatter plot. i Aβ fibrils containing the plaques from the MITOL-deleted APP/PS1 brain exhibited a dramatic seeding effect on the polymerization of free Aβ monomers. Aβ fibrils in indicated 15-months old mice were isolated and purified as described in “Method” . The fibrils were co-incubated with seed-free Aβ40 monomers as aggregation seeds for indicated periods, as described in “Method”, and the polymerization was monitored by ThT. As a control, TBS solution was used (no seeds). Error bars indicate ±SE (n = 4). **p < 0.01, *p < 0.05 (Student’s t test).