Fig. 1.

The morphology of early endosomes is altered in AβPP overexpressing transgenic mice. (A) Neurons from the frontoparietal cortex of APP23 (middle panel) and APPLd2 (right panel) mice labeled with rab5b (top row) and rabaptin-5 (bottom row) show enlarged endosomes and increased immunoreactivity compared to age-matched wt controls (left panel). As described in the Materials and Methods section, quantitation of average rab5b-positive early endosome size in APP23 and APPLd2 compared with wt mice is shown in (B). Measurements were made from 10–12 neurons per section, 3 sections per mouse, and 4 mice per genotype. Labeling conditions and exposure times were identical throughout. (C) Western blot of proteins from hemibrains lacking cerebella of wt, APP23, and APPLd2 mice probed with an anti-AβPP C-terminal monoclonal antibody (C1/6.1), which detects both murine and human AβPP and CTFs (upper and middle panels). β-tubulin reactivity is shown as a loading control (lower panel). Quantification of AβPP (D) and CTF (E) band density (arbitrary units normalized to the β-tubulin bands, mean ± SEM). Scale bars, top row 10 μm, bottom row 100 μm. Differences from wt were significant at *p < 0.05, **p < 0.01, and ***p < 0.001.