Amyloidogenic processing of human amyloid precursor protein in hippocampal neurons devoid of cathepsin D.
betaA4-Amyloid peptide, the main component of the amyloid plaques in the brain of Alzheimer's disease patients is produced from amyloid precursor protein (APP) by proteolytical processing. Several lines of evidence suggest a direct role for cathepsin D, the major endosomal/lysosomal aspartic endopeptidase, in betaA4-amyloid peptide generation. Here we tested this hypothesis using primary cultures of hippocampal neurons derived from cathepsin D-deficient (knock out) mice and expressing wild-type human APP and two clinical APP variants via recombinant Semliki Forest virus. We demonstrate APP secretory processing, production of carboxyl-terminal amyloid fragments, and secretion of the betaA4-amyloid peptide in the complete absence of cathepsin D. The results rule out cathepsin D as a critical component of alpha-, beta-, or gamma-secretase and therefore as a primary target for drugs aimed at decreasing the betaA4-amyloid peptide burden in Alzheimer's disease.
Zentrum Biochemie und Molekular Zellbiologie, Abteilung Biochemie II, Universität Göttingen, Gosslerstrasse 12D, 37073 Göttingen, Germany.Bart.Destrooper@med.kuleuven.ac.de
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Peters
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von Figura
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Craessaerts
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Van Leuven
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De Strooper
D000595:Amino Acid Sequence; D016229:Amyloid beta-Peptides / Q000096:biosynthesis* / Q000737:chemistry; D016564:Amyloid beta-Protein Precursor / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002402:Cathepsin D / Q000172:deficiency*; D002478:Cells, Cultured; D003433:Crosses, Genetic; D017931:DNA Primers; D014644:Genetic Variation; D006579:Heterozygote; D006624:Hippocampus / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011499:Protein Processing, Post-Translational; D012672:Semliki forest virus; D014162:Transfection
D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D017931:DNA Primers; D002402:Cathepsin D