title: Rab8 regulates the actin-based movement of melanosomes.
abstract: Rab GTPases have been implicated in the regulation of specific microtubule- and actin-based motor proteins. We devised an in vitro motility assay reconstituting the movement of melanosomes on actin bundles in the presence of ATP to investigate the role of Rab proteins in the actin-dependent movement of melanosomes. Using this assay, we confirmed that Rab27 is required for the actin-dependent movement of melanosomes, and we showed that a second Rab protein, Rab8, also regulates this movement. Rab8 was partially associated with mature melanosomes. Expression of Rab8Q67L perturbed the cellular distribution and increased the frequency of microtubule-independent movement of melanosomes in vivo. Furthermore, anti-Rab8 antibodies decreased the number of melanosomes moving in vitro on actin bundles, whereas melanosomes isolated from cells expressing Rab8Q67L exhibited 70% more movements than wild-type melanosomes. Together, our observations suggest that Rab8 is involved in regulating the actin-dependent movement of melanosomes.
authors.affiliation: Unité de Morphogenèse et Signalisation Cellulaires, Institut Curie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 144, Paris Cedex, France.
authors.forename: Marion L
authors.initials: ML
authors.lastname: Chabrillat
authors.forename: Claire
authors.initials: C
authors.lastname: Wilhelm
authors.forename: Christina
authors.initials: C
authors.lastname: Wasmeier
authors.forename: Elena V
authors.initials: EV
authors.lastname: Sviderskaya
authors.forename: Daniel
authors.initials: D
authors.lastname: Louvard
authors.forename: Evelyne
authors.initials: E
authors.lastname: Coudrier
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D006801:Humans; D020460:Melanosomes / Q000378:metabolism*; D051379:Mice; D009154:Mutation / Q000235:genetics; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000075745:rab27 GTP-Binding Proteins
chemical_list: D000199:Actins; D000075745:rab27 GTP-Binding Proteins; C066694:RAB27A protein, human; C082377:RAB8A protein, human; C512962:Rab27a protein, mouse; D020691:rab GTP-Binding Proteins