The function of the intermediate compartment in pre-Golgi trafficking involves its stable connection with the centrosome.
Because the functional borders of the intermediate compartment (IC) are not well defined, the spatial map of the transport machineries operating between the endoplasmic reticulum (ER) and the Golgi apparatus remains incomplete. Our previous studies showed that the IC consists of interconnected vacuolar and tubular parts with specific roles in pre-Golgi trafficking. Here, using live cell imaging, we demonstrate that the tubules containing the GTPase Rab1A create a long-lived membrane compartment around the centrosome. Separation of this pericentrosomal domain of the IC from the Golgi ribbon, due to centrosome motility, revealed that it contains a distinct pool of COPI coats and acts as a temperature-sensitive way station in post-ER trafficking. However, unlike the Golgi, the pericentrosomal IC resists the disassembly of COPI coats by brefeldin A, maintaining its juxtaposition with the endocytic recycling compartment, and operation as the focal point of a dynamic tubular network that extends to the cell periphery. These results provide novel insight into the compartmental organization of the secretory pathway and Golgi biogenesis. Moreover, they reveal a direct functional connection between the IC and the endosomal system, which evidently contributes to unconventional transport of the cystic fibrosis transmembrane conductance regulator to the cell surface.
Marie
Michaël
M
Department of Biomedicine and Molecular Imaging Center, University of Bergen, N-5009 Bergen, Norway.
Dale
Hege A
HA
Sannerud
Ragna
R
Saraste
Jaakko
J
D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D022181:COP-Coated Vesicles / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D002460:Cell Line / Q000821:virology; D018385:Centrosome / Q000502:physiology* / Q000648:ultrastructure; D020755:Coat Protein Complex I / Q000502:physiology*; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000378:metabolism; D004705:Endocytosis; D006056:Golgi Apparatus / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000502:physiology / Q000648:ultrastructure; D007668:Kidney / Q000166:cytology; D008647:Mesocricetus; D018715:Microscopy, Video; D021381:Protein Transport / Q000502:physiology*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012672:Semliki forest virus / Q000502:physiology; D014760:Viral Fusion Proteins / Q000378:metabolism; D020761:rab1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000502:physiology* / Q000648:ultrastructure
C505032:CFTR protein, human; D020755:Coat Protein Complex I; D011993:Recombinant Fusion Proteins; D014760:Viral Fusion Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D020126:Brefeldin A; D020761:rab1 GTP-Binding Proteins