Protease inhibitors generate cytotoxic fragments from Alzheimer amyloid protein precursor in cDNA-transfected glioma cells.
A human glioma cell line (Bu-17) was stably transfected with full-length cDNA encoding beta/A4 amyloid protein precursor (APP). When the transfectants were treated with protease inhibitors (leupeptin, E-64, and antipain) and the lysosomotropic agent chloroquine, aberrantly processed fragments of APP having molecular sizes of 8-30 kDa were detected with an antibody against the carboxyl-terminal sequence of APP. Immunocytochemistry revealed that these fragments were localized in the lysosome-like organelles. Treatment of the APP cDNA transfectants with chloroquine for 3 days caused cellular degeneration, and leupeptin and E-64 enhanced chloroquine-induced cytotoxicity. These results suggest that inhibition of lysosomal hydrolases impairs intracellular APP metabolism to generate aberrantly processed fragments that induce cytotoxicity.
Hayashi
Y
Y
Biochemical Research Institute, Morinaga Milk Ind. Co. Ltd., Kanagawa, Japan.
Kashiwagi
K
K
Yoshikawa
K
K
D016564:Amyloid beta-Protein Precursor / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D002738:Chloroquine / Q000494:pharmacology; D003603:Cytotoxins / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005910:Glioma; D006801:Humans; D066298:In Vitro Techniques; D008970:Molecular Weight; D011480:Protease Inhibitors / Q000494:pharmacology*; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D016564:Amyloid beta-Protein Precursor; D003603:Cytotoxins; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D002738:Chloroquine