title: Maturation of late Golgi cisternae into RabE(RAB11) exocytic post-Golgi carriers visualized in vivo.
abstract: The mechanism(s) by which proteins traverse and exit the Golgi are incompletely understood. Using Aspergillus nidulans hyphae, we show that late Golgi cisternae undergo changes in composition to gradually lose Golgi identity while acquiring post-Golgi RabE(RAB11) identity. This behavior of late Golgi cisternae is consistent with the cisternal maturation model. Post-Golgi RabE(RAB11) carriers travel to, and accumulate at, the apex, indicating that fusion is rate limiting for exocytosis. These carriers, which are loaded with kinesin, dynein, and MyoE(MYO5), move on a microtubule-based bidirectional conveyor belt relaying them to actin, which ultimately focuses exocytosis at the apex. Dynein drags RabE(RAB11) carriers away if engagement of MyoE(MYO5) to actin cables fails. Microtubules seemingly cooperating with F-actin capture can sustain secretion if MyoE(MYO5) is absent. Thus, filamentous fungal secretion involving post-Golgi carriers is remarkably similar, mechanistically, to the transport of melanosomes in melanocyte dendrites, even though melanosome biogenesis involves lysosomes rather than Golgi.
authors.affiliation: Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain apantazopoulou@cib.csic.es penalva@cib.csic.es.
authors.forename: Areti
authors.initials: A
authors.lastname: Pantazopoulou
authors.affiliation: Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain.
authors.forename: Mario
authors.initials: M
authors.lastname: Pinar
authors.affiliation: Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814.
authors.forename: Xin
authors.initials: X
authors.lastname: Xiang
authors.affiliation: Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid 28040, Spain apantazopoulou@cib.csic.es penalva@cib.csic.es.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Peñalva
mesh_terms: D000199:Actins / Q000378:metabolism*; D001233:Aspergillus nidulans / Q000166:cytology*; D001692:Biological Transport; D004398:Dyneins / Q000378:metabolism*; D005089:Exocytosis; D005656:Fungal Proteins / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism*; D006579:Heterozygote; D025301:Hyphae / Q000166:cytology; D016547:Kinesins / Q000378:metabolism*; D020460:Melanosomes / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D005656:Fungal Proteins; D004398:Dyneins; D016547:Kinesins; D020691:rab GTP-Binding Proteins