title: ADP-ribosylation factor 6 and a functional PIX/p95-APP1 complex are required for Rac1B-mediated neurite outgrowth.
abstract: The mechanisms coordinating adhesion, actin organization, and membrane traffic during growth cone migration are poorly understood. Neuritogenesis and branching from retinal neurons are regulated by the Rac1B/Rac3 GTPase. We have identified a functional connection between ADP-ribosylation factor (Arf) 6 and p95-APP1 during the regulation of Rac1B-mediated neuritogenesis. P95-APP1 is an ADP-ribosylation factor GTPase-activating protein (ArfGAP) of the GIT family expressed in the developing nervous system. We show that Arf6 has a predominant role in neurite extension compared with Arf1 and Arf5. Cotransfection experiments indicate a specific and cooperative potentiation of neurite extension by Arf6 and the carboxy-terminal portion of p95-APP1. Localization studies in neurons expressing different p95-derived constructs show a codistribution of p95-APP1 with Arf6, but not Arf1. Moreover, p95-APP1-derived proteins with a mutated or deleted ArfGAP domain prevent Rac1B-induced neuritogenesis, leading to PIX-mediated accumulation at large Rab11-positive endocytic vesicles. Our data support a role of p95-APP1 as a specific regulator of Arf6 in the control of membrane trafficking during neuritogenesis.
authors.affiliation: Cell Adhesion Unit, Department of Molecular Biology and Functional Genomics, S Raffaele Scientific Institute, 20132 Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Albertinazzi
authors.forename: Lorena
authors.initials: L
authors.lastname: Za
authors.forename: Simona
authors.initials: S
authors.lastname: Paris
authors.forename: Ivan
authors.initials: I
authors.lastname: de Curtis
mesh_terms: D000089982:ADP-Ribosylation Factor 6; D020727:ADP-Ribosylation Factors / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002642:Chick Embryo; D011992:Endosomes / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D046911:Macromolecular Substances; D009154:Mutation; D009420:Nervous System / Q000196:embryology / Q000378:metabolism; D016501:Neurites / Q000378:metabolism* / Q000648:ultrastructure*; D009479:Neuropeptides / Q000378:metabolism*; D010750:Phosphoproteins; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000378:metabolism; D064067:Rho Guanine Nucleotide Exchange Factors; D014162:Transfection; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein
chemical_list: D000089982:ADP-Ribosylation Factor 6; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D046911:Macromolecular Substances; D009479:Neuropeptides; D010750:Phosphoproteins; C107953:RAC1 protein, human; D011994:Recombinant Proteins; D064067:Rho Guanine Nucleotide Exchange Factors; D020727:ADP-Ribosylation Factors; C000715348:ARF6 protein, human; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein