title: C. elegans RPM-1 regulates axon termination and synaptogenesis through the Rab GEF GLO-4 and the Rab GTPase GLO-1.
abstract: C. elegans RPM-1 (for Regulator of Presynaptic Morphology) is a member of a conserved protein family that includes Drosophila Highwire and mammalian Pam and Phr1. These are large proteins recently shown to regulate synaptogenesis through E3 ubiquitin ligase activities. Here, we report the identification of an RCC1-like guanine nucleotide exchange factor, GLO-4, from mass spectrometry analysis of RPM-1-associated proteins. GLO-4 colocalizes with RPM-1 at presynaptic terminals. Loss of function in glo-4 or in its target Rab GTPase, glo-1, causes neuronal defects resembling those in rpm-1 mutants. We show that the glo pathway functions downstream of rpm-1 and acts in parallel to fsn-1, a partner of RPM-1 E3 ligase function. We find that late endosomes are specifically disorganized at the presynaptic terminals of glo-4 mutants. Our data suggest that RPM-1 positively regulates a Rab GTPase pathway to promote vesicular trafficking via late endosomes.
authors: Department of Molecular, Cell and Developmental Biology, Sinsheimer Laboratories, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
authors: Brock
authors: B
authors: Grill
authors: Willy V
authors: WV
authors: Bienvenut
authors: Heather M
authors: HM
authors: Brown
authors: Brian D
authors: BD
authors: Ackley
authors: Manfredo
authors: M
authors: Quadroni
authors: Yishi
authors: Y
authors: Jin
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000032:analysis / Q000378:metabolism* / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000032:analysis / Q000378:metabolism* / Q000502:physiology*; D047468:Immunoprecipitation / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D009154:Mutation / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000166:cytology* / Q000378:metabolism; D017729:Presynaptic Terminals / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D013347:Subcellular Fractions / Q000378:metabolism; D013569:Synapses / Q000502:physiology*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; C505597:Glo-4 protein, C elegans; D020662:Guanine Nucleotide Exchange Factors; C409634:RPM-1 protein, C elegans; D049452:Green Fluorescent Proteins; C505598:Glo-1 protein, C elegans; D020691:rab GTP-Binding Proteins