title: AGAP2 regulates retrograde transport between early endosomes and the TGN.
abstract: The retrograde transport route links early endosomes and the TGN. Several endogenous and exogenous cargo proteins use this pathway, one of which is the well-explored bacterial Shiga toxin. ADP-ribosylation factors (Arfs) are approximately 20 kDa GTP-binding proteins that are required for protein traffic at the level of the Golgi complex and early endosomes. In this study, we expressed mutants and protein fragments that bind to Arf-GTP to show that Arf1, but not Arf6 is required for transport of Shiga toxin from early endosomes to the TGN. We depleted six Arf1-specific ARF-GTPase-activating proteins and identified AGAP2 as a crucial regulator of retrograde transport for Shiga toxin, cholera toxin and the endogenous proteins TGN46 and mannose 6-phosphate receptor. In AGAP2-depleted cells, Shiga toxin accumulates in transferrin-receptor-positive early endosomes, suggesting that AGAP2 functions in the very early steps of retrograde sorting. A number of other intracellular trafficking pathways are not affected under these conditions. These results establish that Arf1 and AGAP2 have key trafficking functions at the interface between early endosomes and the TGN.
authors.affiliation: Institut Curie - Centre de Recherche, Traffic, Signaling and Delivery Laboratory, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shiba
authors.forename: Winfried
authors.initials: W
authors.lastname: Römer
authors.forename: Gonzalo A
authors.initials: GA
authors.lastname: Mardones
authors.forename: Patricia V
authors.initials: PV
authors.lastname: Burgos
authors.forename: Christophe
authors.initials: C
authors.lastname: Lamaze
authors.forename: Ludger
authors.initials: L
authors.lastname: Johannes
mesh_terms: D020823:ADP-Ribosylation Factor 1 / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D050505:Mutant Proteins / Q000235:genetics; D010446:Peptide Fragments / Q000235:genetics; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics; D011990:Receptors, Transferrin / Q000096:biosynthesis; D022621:Shiga Toxin / Q000378:metabolism*; D012762:Shigella dysenteriae / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: C446512:ARAP3 protein, human; D048868:Adaptor Proteins, Signal Transducing; D020690:GTPase-Activating Proteins; D050505:Mutant Proteins; D010446:Peptide Fragments; D034741:RNA, Small Interfering; D011990:Receptors, Transferrin; D022621:Shiga Toxin; C485997:AGAP2 protein, human; D019204:GTP-Binding Proteins; D020823:ADP-Ribosylation Factor 1