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pubmedcentral.nih.gov
pubmedcentral.nih.gov
Flurbiprofen and its enantiomers directly target ã-secretase. ã-Secretase refers to the enzymatic activity that carries out the final cleavage to release Aâ from APP carboxy-terminal fragments (CTFs) (1). ã-Secretase activity resides in a high-molecular-weight complex that consists of four proteins, either PS1 or PS2 coupled with nicastrin, APH-1, and PEN-2 (26, 27). Although the precise role of each member of the complex is not definitively proven, it appears that the PSs are the catalytic subunits (28). Because NSAIDs appear to shift ã-secretase cleavage independently of known cellular targets, we used a well-characterized broken cell ã-secretase assay to determine whether flurbiprofen and its enantiomers directly target ã-secretase (21, 22). This assay uses partially purified carbonate-stripped membranes that are enriched for ã-secretase activity and contain endogenous APP CTFs as substrate. Importantly, no detergents are used in this assay, since we find that solublization of ã-secretase with detergents can alter the response to various inhibitors and Aâ42 lowering NSAIDs (data not shown). Flurbiprofen and its enantiomers lower Aâ42 levels in the broken cell ã-secretase assay with a dose response similar to what was observed for cell culture without significantly affecting either Aâ40 production (Figure 3) or CTFã production (data not shown). |
