FIGURE 7.

Aβ-(1–42) peptide is the APP derivative responsible for the up-regulation of BACE1. A, primary neurons, obtained from a 17.5 pregnant FVB mouse, and cultured for 21 days (similar data for 14 days in vitro neurons not shown) were treated for 1 h with freshly dissolved 1 μm Aβ peptides or with medium alone. BACE1 transcription levels were determined. Nine wells for each condition from three different neuronal cultures were analyzed as single experimental points. B, a series of neuronal cell lines (SKNBE(2c) and SH-SY5Y) were treated similarly at least 18 h after plating with 1 μm Aβ peptides or with medium alone for 1 h. mRNA was extracted as described, and TaqMan Real Time PCR for BACE1 was performed. Data are a pool of several experimental repeats, performed at least in three repeats for each different cell line, which yielded analogous results; they represent the mean and S.E. C and E, HEK-293 APPwt cells were transfected with empty vector, wild type PS1, and mutant PS1 constructs. Aβ species were quantified in conditioned media by enzyme-linked immunosorbent assay. D and F, BACE1 activity was also measured in these cells and correlated to the levels of Aβ40 and Aβ42. Statistical analysis was performed with ANOVA and the Bonferroni post-test and the study of linear correlation (D and F). CTR, control.