FIG. 2.

Spatial distribution of APP_V717I-CT100 and tau_V337M transgene protein products. Free-floating sagittal sections (each, 30 μm; 6-month-old mice) were immunohistochemically stained with an anti-APP (C-terminal) antibody (A) or human-specific anti-tau T14 antibody (B). The sections shown from the various brain areas (as labeled) are from APP_V717I-CT100 (A) or tau_V337M (B) mice. The level of staining did not differ between APP_V717I-CT100 or tau_V337M and the combined mice (not shown). A section from the prefrontal cortex (wild-type littermate) is representative of the level of staining throughout wild type littermate brains. Scale bar, 100 μm. The data are representative of four independent samples per group. (C) The levels of exogenous human APP-CT100 and tau protein relative to mouse APP and tau were assessed by Western blotting. Protein from forebrain tissue extracts of wild-type (WT) mice and transgenic mice expressing human APP_V717I-CT100 alone (CT100), human tau_V337M alone (Tau), or both transgenes (COM) was separated on a 15% polyacrylamide gel and transferred onto nitrocellulose. The blot was probed with an antibody which recognizes both mouse and human APP within the C terminus. The running position of molecular mass marker proteins is shown (left panel). To establish that the CT100 fragment was localized to the plasma membrane, samples of cytosolic and membrane proteins were analyzed by SDS-15% polyacrylamide gel electrophoresis. Either β-actin or Gα_o was used to assess protein loading, and detection was made with an anti-APP (C-terminal) antibody. Whole-tissue extracts were also analyzed with antibodies to β-actin to show consistency of protein loading and antibodies which recognize either human tau or both human and mouse tau (BR133) (center panel). Quantification of the levels of human and mouse tau was undertaken with the GeneGnome detection system (right panel).