title: The EARP Complex and Its Interactor EIPR-1 Are Required for Cargo Sorting to Dense-Core Vesicles.
abstract: The dense-core vesicle is a secretory organelle that mediates the regulated release of peptide hormones, growth factors, and biogenic amines. Dense-core vesicles originate from the trans-Golgi of neurons and neuroendocrine cells, but it is unclear how this specialized organelle is formed and acquires its specific cargos. To identify proteins that act in dense-core vesicle biogenesis, we performed a forward genetic screen in Caenorhabditis elegans for mutants defective in dense-core vesicle function. We previously reported the identification of two conserved proteins that interact with the small GTPase RAB-2 to control normal dense-core vesicle cargo-sorting. Here we identify several additional conserved factors important for dense-core vesicle cargo sorting: the WD40 domain protein EIPR-1 and the endosome-associated recycling protein (EARP) complex. By assaying behavior and the trafficking of dense-core vesicle cargos, we show that mutants that lack EIPR-1 or EARP have defects in dense-core vesicle cargo-sorting similar to those of mutants in the RAB-2 pathway. Genetic epistasis data indicate that RAB-2, EIPR-1 and EARP function in a common pathway. In addition, using a proteomic approach in rat insulinoma cells, we show that EIPR-1 physically interacts with the EARP complex. Our data suggest that EIPR-1 is a new interactor of the EARP complex and that dense-core vesicle cargo sorting depends on the EARP-dependent trafficking of cargo through an endosomal sorting compartment.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, Washington, United States of America.
authors.forename: Irini
authors.initials: I
authors.lastname: Topalidou
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, Washington, United States of America.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Cattin-Ortolá
authors.affiliation: Department of Neurobiology, Duke University School of Medicine, Durham, North Carolina, United States of America.
authors.forename: Andrea L
authors.identifier: 0000-0002-6802-2105
authors.initials: AL
authors.lastname: Pappas
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, Washington, United States of America.
authors.forename: Kirsten
authors.identifier: 0000-0002-0711-2713
authors.initials: K
authors.lastname: Cooper
authors.affiliation: Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Gennifer E
authors.identifier: 0000-0003-4903-0318
authors.initials: GE
authors.lastname: Merrihew
authors.affiliation: Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: MacCoss
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, Washington, United States of America.
authors.forename: Michael
authors.identifier: 0000-0002-8070-1362
authors.initials: M
authors.lastname: Ailion
mesh_terms: D000818:Animals; D001679:Biogenic Amines / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics*; D011992:Endosomes / Q000235:genetics / Q000378:metabolism; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D046912:Multiprotein Complexes / Q000235:genetics; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D036361:Peptide Hormones / Q000235:genetics; D040901:Proteomics; D022142:Secretory Vesicles / Q000235:genetics* / Q000378:metabolism; D013572:Synaptic Vesicles / Q000235:genetics* / Q000378:metabolism; D020693:rab2 GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism
chemical_list: D001679:Biogenic Amines; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; C000619115:EIPR-1 protein, C elegans; D036341:Intercellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D036361:Peptide Hormones; D020693:rab2 GTP-Binding Protein