Abstract
Despite intense interest in the proteolysis of the β-Amyloid Precursor Protein (APP) in Alzheimer's disease, how the normal processing of this type I receptor-like glycoprotein is physiologically regulated remains ill-defined. In recent years, several candidate protein ligands for APP, including F-spondin, Reelin, β1 Integrin, Contactins, Lingo-1, and Pancortin, have been reported. However, a cognate ligand for APP that regulates its processing by α- or β-secretase has yet to be widely confirmed in multiple laboratories. Here, we developed new assays in an effort to confirm a role for one or more of these candidate ligands in regulating APP ectodomain shedding in a biologically relevant context. A comprehensive quantification of APPsα and APPsβ, the immediate products of secretase processing, in both non-neuronal cell lines and primary neuronal cultures expressing endogenous APP yielded no evidence that any of these published candidate ligands stimulate ectodomain shedding. Rather, Reelin, Lingo-1, and Pancortin-1 emerged as the most consistent ligands for significantly inhibiting ectodomain shedding. These findings led us to conduct further detailed analyses of the interactions of Reelin and Lingo-1 with APP.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Alzheimer Disease / metabolism
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Amyloid Precursor Protein Secretases / metabolism
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Amyloid beta-Protein Precursor / genetics
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Amyloid beta-Protein Precursor / metabolism*
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Animals
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Cell Adhesion Molecules, Neuronal / genetics
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Cell Adhesion Molecules, Neuronal / metabolism
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Cells, Cultured
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Extracellular Matrix Proteins / genetics
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Extracellular Matrix Proteins / metabolism
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Glycoproteins / genetics
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Glycoproteins / metabolism
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HEK293 Cells
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Humans
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Ligands
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Nerve Tissue Proteins / genetics
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Nerve Tissue Proteins / metabolism
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Neurons / metabolism
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Protein Processing, Post-Translational
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Proteolysis
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Rats
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Reelin Protein
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Serine Endopeptidases / genetics
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Serine Endopeptidases / metabolism
Substances
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Amyloid beta-Protein Precursor
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Cell Adhesion Molecules, Neuronal
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Extracellular Matrix Proteins
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Glycoproteins
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LINGO1 protein, human
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Ligands
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Membrane Proteins
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Nerve Tissue Proteins
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Recombinant Proteins
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Reelin Protein
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Reln protein, rat
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olfactomedin
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Amyloid Precursor Protein Secretases
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RELN protein, human
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Reln protein, mouse
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Serine Endopeptidases