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Insertion of Lysosomal Targeting Sequences to the Amyloid Precursor Protein Reduces Secretion of βA4
Author(s) -
SchraderFischer Gesine,
Staufenbiel Matthias,
Paganetti Paolo A.
Publication year - 1997
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1997.68041571.x
Subject(s) - secretion , amyloid precursor protein , amyloid (mycology) , microbiology and biotechnology , chemistry , biochemistry , neuroscience , alzheimer's disease , biology , medicine , disease , inorganic chemistry
The processing of the amyloid precursor protein (APP) was investigated in cells stably expressing different APP hybrid proteins. The cytoplasmic domain of APP was either deleted or replaced by the corresponding domain of the membrane protein TGN38, lamp‐1, or LIMPII. The cytosolic domain of TGN38 in the APP molecule did not alter the secretion of βA4 when compared with the wild‐type APP; however, APP associated with the cell surface and the nonamyloidogenic processing of APP were reduced. With the APP molecules carrying the lysosomal targeting signals of lamp‐1 or LIMPII, a decrease in the secretion of βA4 was observed. Cell surface association and nonamyloidogenic processing were also impaired. This suggests increased degradation of APP and thus efficient targeting to the lysosomal system. Cells expressing the Swedish APP variant generated intracellular βA4 that accumulated after treatment with chloroquine. This effect was more dramatic with APP mutants carrying lysosomal targeting signals than with full‐length APP. Our data suggest the existence of an intracellular site of βA4 generation from where βA4 is degraded rather than secreted.