title: beta-Amyloid precursor protein fragments and lysosomal dense bodies are found in rat brain neurons after ventricular infusion of leupeptin.
abstract: Infusion of the serine and thiol protease inhibitor, leupeptin, is known to cause a reduction of fast axoplasmic transport, and accumulation of lysosomal dense bodies in neuronal perikarya. We have found these dense bodies in hippocampal and cerebellar neurons contain ubiquitin conjugated proteins. We now demonstrate that these accumulated neuronal lysosomes are labeled by antisera to the cytoplasmic, transmembrane and extracellular domains of beta-amyloid precursor protein (APP) and also that lysosomal APP is fragmented. This in vivo model confirms that neurons can process APP via a lysosomal pathway and that neuronal lysosomes in vivo contain both N-terminal and potentially amyloidogenic C-terminal fragments of APP. We also show that increased APP immunoreactivity after leupeptin treatment is seen first in neurons and later in astrocytes. On recovery from infusion, APP N-terminal immunoreactivity diminishes whilst C-terminal reactivity remains in neurons. These findings are consistent with production in whole brain of potentially amyloidogenic fragments of APP within neuronal lysosomes in perikarya and dendrites implying that neurons may play a role in forming the beta-amyloid of plaques.
authors.affiliation: University Department of Neurology, Institute of Psychiatry, London, UK.
authors.forename: I
authors.initials: I
authors.lastname: Hajimohammadreza
authors.forename: V E
authors.initials: VE
authors.lastname: Anderson
authors.forename: J B
authors.initials: JB
authors.lastname: Cavanagh
authors.forename: M P
authors.initials: MP
authors.lastname: Seville
authors.forename: C C
authors.initials: CC
authors.lastname: Nolan
authors.forename: B H
authors.initials: BH
authors.lastname: Anderton
authors.forename: P N
authors.initials: PN
authors.lastname: Leigh
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001369:Axons / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000276:immunology / Q000378:metabolism; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D007976:Leupeptins / Q000008:administration & dosage / Q000494:pharmacology*; D008247:Lysosomes / Q000378:metabolism*; D009474:Neurons / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D010446:Peptide Fragments / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D016564:Amyloid beta-Protein Precursor; D000911:Antibodies, Monoclonal; D007976:Leupeptins; D010446:Peptide Fragments; C032854:leupeptin