Regulation of retromer recruitment to endosomes by sequential action of Rab5 and Rab7.
The retromer complex mediates retrograde transport of transmembrane cargo from endosomes to the trans-Golgi network (TGN). Mammalian retromer is composed of a sorting nexin (SNX) dimer that binds to phosphatidylinositol 3-phosphate-enriched endosomal membranes and a vacuolar protein sorting (Vps) 26/29/35 trimer that participates in cargo recognition. The mammalian SNX dimer is necessary but not sufficient for recruitment of the Vps26/29/35 trimer to membranes. In this study, we demonstrate that the guanosine triphosphatase Rab7 contributes to this recruitment. The Vps26/29/35 trimer specifically binds to Rab7-guanosine triphosphate (GTP) and localizes to Rab7-containing endosomal domains. Interference with Rab7 function causes dissociation of the Vps26/29/35 trimer but not the SNX dimer from membranes. This blocks retrieval of mannose 6-phosphate receptors to the TGN and impairs cathepsin D sorting. Rab5-GTP does not bind to the Vps26/29/35 trimer, but perturbation of Rab5 function causes dissociation of both the SNX and Vps26/29/35 components from membranes through inhibition of a pathway involving phosphatidylinositol 3-kinase. These findings demonstrate that Rab5 and Rab7 act in concert to regulate retromer recruitment to endosomes.
Rojas
Raul
R
Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
van Vlijmen
Thijs
T
Mardones
Gonzalo A
GA
Prabhu
Yogikala
Y
Rojas
Adriana L
AL
Mohammed
Shabaz
S
Heck
Albert J R
AJ
Raposo
Graça
G
van der Sluijs
Peter
P
Bonifacino
Juan S
JS
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D019281:Dimerization; D011992:Endosomes / Q000502:physiology*; D005982:Glutathione Transferase / Q000502:physiology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006706:Homeostasis; D006867:Hydrolases / Q000378:metabolism; D008322:Mammals; D008565:Membrane Proteins / Q000502:physiology; D014617:Vacuoles / Q000502:physiology; D020691:rab GTP-Binding Proteins / Q000502:physiology*; D020696:rab5 GTP-Binding Proteins / Q000502:physiology*; D000090802:rab7 GTP-Binding Proteins; D021601:trans-Golgi Network / Q000502:physiology
D008565:Membrane Proteins; D000090802:rab7 GTP-Binding Proteins; C000716463:rab7 GTP-binding proteins, human; D006160:Guanosine Triphosphate; D005982:Glutathione Transferase; D006867:Hydrolases; D020691:rab GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins