title: Flotillin-dependent clustering of the amyloid precursor protein regulates its endocytosis and amyloidogenic processing in neurons.
abstract: The flotillins/reggie proteins are associated with noncaveolar membrane microdomains and have been implicated in the regulation of a clathrin- and caveolin-independent endocytosis pathway. Endocytosis is required for the amyloidogenic processing of the amyloid precursor protein (APP) and thus to initiate the release of the neurotoxic beta-amyloid peptide (Abeta), the major component of extracellular plaques found in the brains of Alzheimer's disease patients. Here, we report that small interference RNA-mediated downregulation of flotillin-2 impairs the endocytosis of APP, in both neuroblastoma cells and primary cultures of hippocampal neurons, and reduces the production of Abeta. Similar to tetanus neurotoxin endocytosis, but unlike the internalization of transferrin, clathrin-dependent endocytosis of APP requires cholesterol and adaptor protein-2 but is independent of epsin1 function. Moreover, on a nanoscale resolution using stimulated emission depletion microscopy and by Förster resonance energy transfer with fluorescence lifetime imaging microscopy, we provide evidence that flotillin-2 promotes the clustering of APP at the cell surface. We show that the interaction of flotillin-2 with APP is dependent on cholesterol and that clustering of APP enhances its endocytosis rate. Together, our data suggest that cholesterol/flotillin-dependent clustering of APP may stimulate the internalization into a specialized clathrin-dependent endocytosis pathway to promote amyloidogenic processing.
authors.affiliation: Centre for Biochemistry and Molecular Cell Biology, Department of Psychiatry and Psychotherapy, University of Göttingen, 37073 Göttingen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Schneider
authors.forename: Lawrence
authors.initials: L
authors.lastname: Rajendran
authors.forename: Masanori
authors.initials: M
authors.lastname: Honsho
authors.forename: Matthias
authors.initials: M
authors.lastname: Gralle
authors.forename: Gerald
authors.initials: G
authors.lastname: Donnert
authors.forename: Fred
authors.initials: F
authors.lastname: Wouters
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Hell
authors.forename: Mikael
authors.initials: M
authors.lastname: Simons
mesh_terms: D016229:Amyloid beta-Peptides / Q000235:genetics / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism*
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor; D008565:Membrane Proteins; C106354:flotillins