Cell-type and amyloid precursor protein-type specific inhibition of A beta release by bafilomycin A1, a selective inhibitor of vacuolar ATPases.
Treatment of human 293 cells transfected with amyloid precursor protein (APP)K595N,M596L (the "Swedish" mutation) with a specific inhibitor of the vacuolar H(+)-ATPases, bafilomycin A1 (baf A), leads to a potent inhibition of the release of the A beta peptide. This is accompanied by a selective inhibition of beta-secretase activity. Surprisingly, baf A did not inhibit the production of A beta from either wild-type APP (WT APP) or from APPv7171 (the "Hardy" mutation), expressed in the same cell type. In contrast, the robust production of A beta from a human neuroglioma-derived cell line (HS683) transfected with WT APP, or from primary human mixed brain cultures (HMBC) expressing genomic WT APP, were also effectively inhibited by baf A. The inhibition of A beta production from the HMBC was also accompanied by the inhibition of beta-s-APP release. No inhibition of alpha-s-APP release was seen in any of the cell types tested. These results indicate that intracellular acidic processes are rate-limiting for beta-secretase cleavage and A beta production from SW APP, but not WT APP, in the peripheral 293 cell line. Furthermore, such acidic processes also play a rate-limiting role in A beta release from human central nervous system-derived cells, including HMBC. Differential trafficking of the SW APP into an acidic compartment conducive to beta-secretase cleavage and A beta release could be one explanation for the increased production of A beta observed on expression of this mutation.
Athena Neurosciences, Inc., South San Francisco, California 94080.
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J
Knops
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Suomensaari
M
M
Lee
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McConlogue
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P
Seubert
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S
Sinha
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000682:Amyloid / Q000378:metabolism*; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006801:Humans; D018942:Macrolides; D000072002:Prion Proteins; D011328:Prions; D011498:Protein Precursors / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014617:Vacuoles / Q000201:enzymology*
D000682:Amyloid; D016229:Amyloid beta-Peptides; D000900:Anti-Bacterial Agents; D018942:Macrolides; C512656:PRNP protein, human; D000072002:Prion Proteins; D011328:Prions; D011498:Protein Precursors; C040929:bafilomycin A1; D000251:Adenosine Triphosphatases