Clathrin adaptor epsinR is required for retrograde sorting on early endosomal membranes.
Retrograde transport links early/recycling endosomes to the trans-Golgi network (TGN), thereby connecting the endocytic and the biosynthetic/secretory pathways. To determine how internalized molecules are targeted to the retrograde route, we have interfered with the function of clathrin and that of two proteins that interact with it, AP1 and epsinR. We found that the glycosphingolipid binding bacterial Shiga toxin entered cells efficiently when clathrin expression was inhibited. However, retrograde transport of Shiga toxin to the TGN was strongly inhibited. This allowed us to show that for Shiga toxin, retrograde sorting on early/recycling endosomes depends on clathrin and epsinR, but not AP1. EpsinR was also involved in retrograde transport of two endogenous proteins, TGN38/46 and mannose 6-phosphate receptor. In conclusion, our work reveals the existence of clathrin-independent and -dependent transport steps in the retrograde route, and establishes a function for clathrin and epsinR at the endosome-TGN interface.
Saint-Pol
Agnès
A
Laboratoire Trafic et Signalisation, 75248 Paris Cedex 05, France.
Yélamos
Belén
B
Amessou
Mohamed
M
Mills
Ian G
IG
Dugast
Marc
M
Tenza
Danièle
D
Schu
Peter
P
Antony
Claude
C
McMahon
Harvey T
HT
Lamaze
Christophe
C
Johannes
Ludger
L
D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D002966:Clathrin / Q000037:antagonists & inhibitors / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism* / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000378:metabolism; D008854:Microscopy, Electron; D021381:Protein Transport / Q000502:physiology; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D022622:Shiga Toxin 1 / Q000378:metabolism / Q000494:pharmacology; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism* / Q000648:ultrastructure
D033942:Adaptor Proteins, Vesicular Transport; C475910:CLINT1 protein, human; D002352:Carrier Proteins; D002966:Clathrin; D004791:Enzyme Inhibitors; D008562:Membrane Glycoproteins; D017527:Receptor, IGF Type 2; D022622:Shiga Toxin 1; C072237:TGOLN2 protein, human; D018808:Transcription Factor AP-1