Hayashi Y, Kashiwagi K, Yoshikawa K
Biochemical Research Institute, Morinaga Milk Ind. Co. Ltd., Kanagawa, Japan.
Biochem Biophys Res Commun. 1992 Sep 30;187(3):1249-55. doi: 10.1016/0006-291x(92)90437-p.
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.
