Rab6A and Rab6A' GTPases play non-overlapping roles in membrane trafficking.
The closely related Rab6 isoforms, Rab6A and Rab6A', have been shown to regulate vesicular trafficking within the Golgi and post-Golgi compartments, but studies using dominant active or negative mutant suggested conflicting models. Here, we report that reduction in the expression of Rab6 isoform using specific small interfering RNA reveals noticeable differences in the Rab6A and Rab6A' biological functions. Surprisingly, Rab6A seems to be largely dispensable in membrane trafficking events, whereas knocking down the expression of Rab6A' hampers the intracellular transport of the retrograde cargo marker, the Shiga Toxin B-subunit along the endocytic pathway, and causes defects in Golgi- associated protein recycling through the endoplasmic reticulum. We also showed that Rab6A' is required for cell cycle progression through mitosis and identify Ile(62) as a key residue for uncoupling Rab6A' functions in mitosis and retrograde trafficking. Thus, our work shows that Rab6A and Rab6A' perform different functions within the cell and suggests a novel role for Rab6A' as the major Rab6 isoform regulating previously described Rab6-dependent transport pathways.
Molecular Mechanisms of Intracellular Transport, UMR CNRS 144, Institut Curie, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
Elaine
E
Del Nery
Stéphanie
S
Miserey-Lenkei
Thomas
T
Falguières
Clément
C
Nizak
Ludger
L
Johannes
Franck
F
Perez
Bruno
B
Goud
D017398:Alternative Splicing; D001483:Base Sequence; D001692:Biological Transport / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D037241:Mannose-Binding Lectins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008938:Mitosis / Q000502:physiology; D008969:Molecular Sequence Data; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D022603:Shiga Toxins / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
C084004:LMAN1 protein, human; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C094135:Rab6 protein; D022603:Shiga Toxins; C077239:stxB toxin; D020691:rab GTP-Binding Proteins