title: The amyloid precursor protein and its regulatory protein, FE65, in growth cones and synapses in vitro and in vivo.
abstract: Although the Alzheimer amyloid protein precursor (APP) has been studied intensely for more than a decade, its function in neurons is unresolved. Much less is known about its binding partner FE65. We have shown recently that APP and FE65 synergistically regulate the movement of transfected cells. It remained to be shown whether endogenous APP and FE65 could play a similar role in vivo. Here, we show that FE65, like APP, is expressed at high levels in neurons. Using a combination of immunofluorescence, live imaging, and subcellular fractionation, we find that FE65 and APP localize in vitro and in vivo to the most motile regions of neurons, the growth cones. Within growth cones, APP and FE65 concentrate in actin-rich lamellipodia. Finally, APP and FE65 interact in nerve terminals, where they associate with Rab5-containing synaptic organelles but not with synaptic vesicles. Our data are consistent with a role for the APP/FE65 complex in regulation of actin-based membrane motility in neurons, which could be important for highly dynamic processes such as neurite growth and synapse modification.
authors.affiliation: Laboratory of Molecular and Cellular Neuroscience and the Zachary and Elizabeth M. Fisher Center, The Rockefeller University, New York, New York 10021, USA. slsabo@ucdavis.edu
authors.forename: Shasta L
authors.initials: SL
authors.lastname: Sabo
authors.forename: Annat F
authors.initials: AF
authors.lastname: Ikin
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Buxbaum
authors.forename: Paul
authors.initials: P
authors.lastname: Greengard
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002478:Cells, Cultured; D020439:Growth Cones / Q000378:metabolism*; D006801:Humans; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D015388:Organelles / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism; D051381:Rats; D013569:Synapses / Q000378:metabolism*; D013572:Synaptic Vesicles / Q000378:metabolism; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: C091042:APBB1 protein, human; D016564:Amyloid beta-Protein Precursor; C486242:Apbb1 protein, rat; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D020696:rab5 GTP-Binding Proteins