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© The Rockefeller University Press,
0021-9525/2000//1207 $5.00
The Journal of Cell Biology, Volume 151, Number 6,
, 2000 1207-1220
Original Article |
Rab11 Regulates the Compartmentalization of Early Endosomes Required for Efficient Transport from Early Endosomes to the Trans-Golgi Network
mona.wilcke{at}eu.pnu.com
Several GTPases of the Rab family, known to be regulators of membrane traffic between organelles, have been described and localized to various intracellular compartments. Rab11 has previously been reported to be associated with the pericentriolar recycling compartment, post-Golgi vesicles, and the trans-Golgi network (TGN). We compared the effect of overexpression of wild-type and mutant forms of Rab11 on the different intracellular transport steps in the endocytic/degradative and the biosynthetic/exocytic pathways in HeLa cells. We also studied transport from endosomes to the Golgi apparatus using the Shiga toxin B subunit (STxB) and TGN38 as reporter molecules. Overexpression of both Rab11 wild-type (Rab11wt) and mutants altered the localization of the transferrrin receptor (TfR), internalized Tf, the STxB, and TGN38. In cells overexpressing Rab11wt and in a GTPase-deficient Rab11 mutant (Rab11Q70L), these proteins were found in vesicles showing characteristics of sorting endosomes lacking cellubrevin (Cb). In contrast, they were redistributed into an extended tubular network, together with Cb, in cells overexpressing a dominant negative mutant of Rab11 (Rab11S25N). This tubularized compartment was not accessible to Tf internalized at temperatures <20°C, suggesting that it is of recycling endosomal origin. Overexpression of Rab11wt, Rab11Q70L, and Rab11S25N also inhibited STxB and TGN38 transport from endosomes to the TGN. These results suggest that Rab11 influences endosome to TGN trafficking primarily by regulating membrane distribution inside the early endosomal pathway.
Key Words: Rab11 • intracellular trafficking • endosomes • Shiga toxin • TGN38
© 2000 The Rockefeller University Press
T. Galli's present address is UMR CNSR 144, Membrane Traffic and Neuronal Plasticity, Institut Curie, F-75248 Paris Cedex 05, France.Abbreviations used in this paper: CI-M6P, cation-independent M6P; Cb, human cellubrevin; HA, hemagglutinin; Ii, MHC class II–associated invariant chain; M6P, mannose-6-phosphate; MHC, major histocompatibility complex; SEAP, secreted alkalin phosphatase; STxB, Shiga toxin B subunit; STxB-sulf, STxB with sulfation sites; Tf, transferrin; TfR, Tf receptor; TRITC, tetramethyl rhodamine isothiocyanate; VSV, vesicular stomatis virus.
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