Figure 1.

Aβ induces extracellular secretion of functional IDE from primary astrocytes. (A, B) Increased IDE levels secreted from the primary astrocytes with Aβ treatment, in a concentration-(A) and time-(B) dependent manner. Treatments were 0.5, 1 or 2 μM of Aβ for 24 h (A), and 1 µM of Aβ for 1, 3, 12 or 24 h (B). Blots are representative of at least 3 independent experiments. (C) Measurement of IDE levels in the media from primary astrocytes by ELISA. (D) IDE enzymatic activity in media containing 1 µM Aβ and/or several inhibitors (Thiorphan [10 µM], Bacitracin A [10 µM]) for 24 h. Baci. A, Bacitracin A. (E) Cell-free Aβ degradation assay. rIDE, recombinant IDE protein (0.3 ng/μL). The arrowhead indicates remaining Aβ levels. Data were obtained from at least 3 replicates for each group (N = 3 experiments). (F) Aβ degradation assay with several drugs. Ins, insulin (0.5 μM); Baci. A, bacitracin A (10 µM). Data were obtained from at least 3 replicates for each group (N = 3 experiments). Values are mean ± SEM *, P < 0.05; **, P < 0.01; and ***, P < 0.001 vs. vehicle-treated cells; #, P < 0.05 vs. cells treated with Aβ.