Figure 7.

APP-PSEN1-SREBF2 mice show an enlarged endosomal-lysosomal system with high cholesterol levels but preserved functionality. (A) Expression levels of the indicated proteins in brain homogenates from 7-mo-old WT and mutant mice. Densitometric values of the bands representing specific protein immunoreactivity were normalized with the values of the corresponding ACTB bands and expressed as relative intensity values. *P < 0.05 and **P < 0.01; n = 3. (B) Cholesterol levels of endosomes-lysosomes isolated from brain homogenates of the indicated mice at 7 mo of age and expressed as μg of product per ACP (acid phosphatase) activity. *P< 0.05; n=3. (C and D) Hippocampal slices from 7-mo-old WT and transgenic mice. Shown are confocal photomicrographs of CTSD and LAMP2 immunoreactivity (C) or IGF2R and LAMP2 immunoreactivity (D). Scale bar: 50 μm. (G) Embryonic cortical and hyppocampal neurons isolated from WT and APP-PSEN1-SREBF2 mice. Shown are representative confocal images of  double immunolabeling with antibodies against LAMP2 (green) and CTSD (red) or IGF2R (red), as indicated. Nuclei were stained with DRAQ5 (blue). Scale bar: 50 μm. The Pearson correlation coefficient was calculated in all the confocal microscopy analysis for quantifying colocalization (15 to 20 cells were analyzed per genotype and experimental condition from a pool of at least 3 images).