Effect of cholesterol sequestration on γ-secretase level and activity. (A and B) Immunoblots and histograms showing amounts of presenilin 1 (PS1-NTF ∼27 kDa; A) and nicastrin (∼110 kDa; B) in the cerebellum of 4- and 10-week-old WT, APP-Tg, Dhet and ANPC mice (n = 4 for 4 weeks/genotype, n = 6 for 10 weeks/genotype). (C) Immunoblots and histograms showing levels of PS1 and mature nicastrin in N2a-ANPC and N2a-APP cells (n = 3). (D) γ-Secretase activity in cerebellar homogenates of age-matched WT, APP-Tg, Dhet and ANPC mice (n = 6 per genotype). (E) γ-Secretase activity in N2a-ANPC and N2a-APP cells from five independent experiments. (F and G) Immunoblots and quantitation of amounts of APP-CTFs (α-CTF and β-CTF, F) and intracellular Aβ1–40 as well as Aβ1–42 (G) in N2a-ANPC and N2a-APP cells following treatment with 1 μm DAPT for 24 h (n = 3 independent experiments). All blots were re-probed with β-actin antibody to monitor protein loading. *P < 0.05; **P < 0.01.