title: Activation of endosomal dynein motors by stepwise assembly of Rab7-RILP-p150Glued, ORP1L, and the receptor betalll spectrin.
abstract: The small GTPase Rab7 controls late endocytic transport by the minus end-directed motor protein complex dynein-dynactin, but how it does this is unclear. Rab7-interacting lysosomal protein (RILP) and oxysterol-binding protein-related protein 1L (ORP1L) are two effectors of Rab7. We show that GTP-bound Rab7 simultaneously binds RILP and ORP1L to form a RILP-Rab7-ORP1L complex. RILP interacts directly with the C-terminal 25-kD region of the dynactin projecting arm p150(Glued), which is required for dynein motor recruitment to late endocytic compartments (LEs). Still, p150(Glued) recruitment by Rab7-RILP does not suffice to induce dynein-driven minus-end transport of LEs. ORP1L, as well as betaIII spectrin, which is the general receptor for dynactin on vesicles, are essential for dynein motor activity. Our results illustrate that the assembly of microtubule motors on endosomes involves a cascade of linked events. First, Rab7 recruits two effectors, RILP and ORP1L, to form a tripartite complex. Next, RILP directly binds to the p150(Glued) dynactin subunit to recruit the dynein motor. Finally, the specific dynein motor receptor Rab7-RILP is transferred by ORP1L to betaIII spectrin. Dynein will initiate translocation of late endosomes to microtubule minus ends only after interacting with betaIII spectrin, which requires the activities of Rab7-RILP and ORP1L.
authors.affiliation: Department of Molecular Medicine, National Public Health Institute, Biomedicum, FI-00251 Helsinki, Finland.
authors.forename: Marie
authors.initials: M
authors.lastname: Johansson
authors.forename: Nuno
authors.initials: N
authors.lastname: Rocha
authors.forename: Wilbert
authors.initials: W
authors.lastname: Zwart
authors.forename: Ingrid
authors.initials: I
authors.lastname: Jordens
authors.forename: Lennert
authors.initials: L
authors.lastname: Janssen
authors.forename: Coenraad
authors.initials: C
authors.lastname: Kuijl
authors.forename: Vesa M
authors.initials: VM
authors.lastname: Olkkonen
authors.forename: Jacques
authors.initials: J
authors.lastname: Neefjes
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D011987:Receptors, Steroid; D015398:Signal Transduction / Q000502:physiology; D013049:Spectrin / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000378:metabolism*; D000090802:rab7 GTP-Binding Proteins; D000098825:Oxysterol Binding Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C000606360:DCTN1 protein, human; D000072159:Dynactin Complex; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; D020409:Molecular Motor Proteins; C423317:RILP protein, human; D011987:Receptors, Steroid; D000098825:Oxysterol Binding Proteins; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D013049:Spectrin; D004398:Dyneins; D020691:rab GTP-Binding Proteins