Figure 3: Mitochondria and associated ER membranes reveal potent β-amyloid inducing activity in vivo.
From: Highly potent intracellular membrane-associated Aβ seeds
(a–f) Bilateral intra-hippocampal (i.h.) injection of 3-month-old APP23 mice (n = 4–5/group) with 3000 × g supernatant (pool from 5 APP23 brain extracts; SE) or with P10,000 × g fraction 6 (pool of 3 independent preparations from 3 APP23 brains) described in Fig. 1. (a–c) The Aβ concentration in fraction 6 had been adjusted to 5,000 pg/ml. Brains were analyzed 7 months after injection. (d–f) In a second experiment mice were injected with SE (n = 5) or fraction 6 (n = 4) adjusted to a 10-fold higher Aβ concentration (50,000 pg/mL) and brains were analyzed already 6 months after injection. (g–i) Three-month-old APP23 mice (n = 5/group) were injected with a mix of 3 independent Tom22-immunoisolated mitochondria preparations from APP23 brain (Aβ concentration 50,000 pg/mL) and correspondingly diluted WT brains and analyzed already 4 months post-inoculation. (a,b,d,e) Aβ staining combined with Congo red shows amyloid deposits in hippocampus of fraction 6 (a,d) as well as in SE injected brains (b,e) Scale bar, 200 μm. (c,f) Quantification of the percentage of Aβ-immunostained hippocampal area. Seeding activity in P10,000 × g fraction 6 was enriched compared to SE ((c); *p < 0.05; unpaired t test, two-tailed, p = 0.0416, t = 2.424, df = 8) ((f): *p < 0.05; unpaired t test, two-tailed, p = 0.0136, t = 3.273, df = 7). (g,h,i) Histological analysis of Aβ deposits after brain injection with APP23 mitochondria (n = 3) (g) or SE (n = 5) (h) or WT mitochondria (n = 5) (i) Scale bar, 200 μm.
