Figure 10.

Aβ-immunoreactive species in PBS-insoluble fractions of brain from APPsi:tTA mice. A–C, Immunoblots of PBS-insoluble fractions with mAb 6E10 (see diagram in Fig. 7 for antibody specificity), which detects APP derivatives produced by the transgene (does not recognize endogenous APP or its derivatives). Suspensions of PBS-insoluble fractions from brain were mixed with 4× Laemmli buffer, boiled before loading (A, C) or loaded directly (B), transferred to membrane, and analyzed by immunoblot. A–C, Lane 1, NTg brain homogenate. A, B, Lanes 2–9, APPsi:tTA mice. Animals receiving DOX diets for 1 week are noted above A (same in B). C, Lanes 2–10, APPsi:tTA mice. Animals receiving DOX diets for 1 or 4 weeks are noted above panel. C, The blot is overexposed to reveal lower molecular weight bands. A band that migrates to the size expected for full-length APP was observed in APPsi:tTA mice Off-DOX; this band was absent in mice On-DOX for 1 week (A). In the samples that were not boiled from mice Off-DOX, we detected a band of ∼10 kDa (arrowhead) that was absent in mice On-DOX. This band was also seen in blots with the CT-20 antibody (data not shown) and likely represents an APP C-terminal fragment. Discrete bands that could represent stable oligomeric assemblies of Aβ are noted by asterisks.