title: Amyloid-beta peptide oligomers disrupt axonal transport through an NMDA receptor-dependent mechanism that is mediated by glycogen synthase kinase 3beta in primary cultured hippocampal neurons.
abstract: Disruption of axonal transport is a hallmark of several neurodegenerative diseases, including Alzheimer's disease (AD). Even though defective transport is considered an early pathologic event, the mechanisms by which neurodegenerative insults impact transport are poorly understood. We show that soluble oligomers of the amyloid-beta peptide (AbetaOs), increasingly recognized as the proximal neurotoxins in AD pathology, induce disruption of organelle transport in primary hippocampal neurons in culture. Live imaging of fluorescent protein-tagged organelles revealed a marked decrease in axonal trafficking of dense-core vesicles and mitochondria in the presence of 0.5 microm AbetaOs. NMDA receptor (NMDAR) antagonists, including d-AP5, MK-801, and memantine, prevented the disruption of trafficking, thereby identifying signals for AbetaO action at the cell membrane. Significantly, both pharmacological inhibition of glycogen synthase kinase-3beta (GSK-3beta) and transfection of neurons with a kinase-dead form of GSK-3beta prevented the transport defect. Finally, we demonstrate by biochemical and immunocytochemical means that AbetaOs do not affect microtubule stability, indicating that disruption of transport involves a more subtle mechanism than microtubule destabilization, likely the dysregulation of intracellular signaling cascades. Results demonstrate that AbetaOs negatively impact axonal transport by a mechanism that is initiated by NMDARs and mediated by GSK-3beta and establish a new connection between toxic Abeta oligomers and AD pathology.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
authors.forename: Helena
authors.initials: H
authors.lastname: Decker
authors.forename: Karen Y
authors.initials: KY
authors.lastname: Lo
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Unger
authors.forename: Sergio T
authors.initials: ST
authors.lastname: Ferreira
authors.forename: Michael A
authors.initials: MA
authors.lastname: Silverman
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D001370:Axonal Transport / Q000187:drug effects*; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D049452:Green Fluorescent Proteins / Q000235:genetics; D006624:Hippocampus / Q000166:cytology*; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000502:physiology*; D014162:Transfection / Q000379:methods; D014404:Tubulin / Q000378:metabolism
chemical_list: D016229:Amyloid beta-Peptides; D019208:Brain-Derived Neurotrophic Factor; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D008164:Luminescent Proteins; D016194:Receptors, N-Methyl-D-Aspartate; D014404:Tubulin; D049452:Green Fluorescent Proteins; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D038362:Glycogen Synthase Kinase 3