title: Rab35 Functions in Axon Elongation Are Regulated by P53-Related Protein Kinase in a Mechanism That Involves Rab35 Protein Degradation and the Microtubule-Associated Protein 1B.
abstract: Rab35 is a key protein for cargo loading in the recycling endosome. In neuronal immortalized cells, Rab35 promotes neurite differentiation. Here we describe that Rab35 favors axon elongation in rat primary neurons in an activity-dependent manner. In addition, we show that the p53-related protein kinase (PRPK) negatively regulates axonal elongation by reducing Rab35 protein levels through the ubiquitin-proteasome degradation pathway. PRPK-induced Rab35 degradation is regulated by its interaction with microtubule-associated protein 1B (MAP1B), a microtubule stabilizing binding protein essential for axon elongation. Consistently, axon defects found in MAP1B knock-out neurons were reversed by Rab35 overexpression or PRPK inactivation suggesting an epistatic relationship among these proteins. These results define a novel mechanism to support axonal elongation, by which MAP1B prevents PRPK-induced Rab35 degradation. Such a mechanism allows Rab35-mediated axonal elongation and connects the regulation of actin dynamics with membrane trafficking. In addition, our study reveals for the first time that the ubiquitin-proteasome degradation pathway regulates a Rab GTPase.
  
  
  
  Rab35 is required for axonal outgrowth. We define that its protein levels are negatively regulated by p53-related protein kinase (PRPK). We show that microtubule-associated protein 1B (MAP1B) interacts with PRPK, preventing PRPK-dependent Rab35 proteasome degradation. We demonstrate that Rab35 regulates Cdc42 activity in neurons. This is the first evidence showing that a Rab protein is regulated by degradation dependent on the ubiquitin-proteasome system.
authors.affiliation: Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de Chile, 7800024 Santiago, Chile, Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
authors.forename: David
authors.initials: D
authors.lastname: Villarroel-Campos
authors.affiliation: Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de Chile, 7800024 Santiago, Chile.
authors.forename: Daniel R
authors.identifier: 0000-0002-1761-1217
authors.initials: DR
authors.lastname: Henríquez
authors.affiliation: Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de Chile, 7800024 Santiago, Chile, Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
authors.forename: Felipe J
authors.identifier: 0000-0002-6700-2225
authors.initials: FJ
authors.lastname: Bodaleo
authors.affiliation: Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Mai E
authors.identifier: 0000-0003-1876-9187
authors.initials: ME
authors.lastname: Oguchi
authors.affiliation: MINREB and CARE Center, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile, and.
authors.forename: Francisca C
authors.initials: FC
authors.lastname: Bronfman
authors.affiliation: Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Tohoku University, Sendai 980-8577, Japan.
authors.forename: Mitsunori
authors.identifier: 0000-0002-8620-5853
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: Laboratory of Cell and Neuronal Dynamics, Department of Biology, Faculty of Sciences, Universidad de Chile, 7800024 Santiago, Chile, Center for Geroscience, Brain Health and Metabolism, Santiago, Chile, The Buck Institute for Research on Aging, Novato, California 94945, chrgonza@uchile.cl.
authors.forename: Christian
authors.initials: C
authors.lastname: Gonzalez-Billault
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology*; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004622:Embryo, Mammalian; D005786:Gene Expression Regulation / Q000235:genetics; D006624:Hippocampus / Q000166:cytology; D051379:Mice; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009474:Neurons / Q000166:cytology*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis / Q000187:drug effects; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D034741:RNA, Small Interfering; C085284:microtubule-associated protein 1B; D017346:Protein Serine-Threonine Kinases; C543587:Rab35 protein, mouse; D020764:cdc42 GTP-Binding Protein; D020691:rab GTP-Binding Proteins
keywords: MAP1B; Rab35; axon development; p53-related protein kinase; ubiquitin proteosome