Analysis of articulation between clathrin and retromer in retrograde sorting on early endosomes.
Clathrin and retromer have key functions for retrograde trafficking between early endosomes and the trans-Golgi network (TGN). Previous studies on Shiga toxin suggested that these two coat complexes operate in a sequential manner. Here, we show that the curvature recognition subunit component sorting nexin 1 (SNX1) of retromer interacts with receptor-mediated endocytosis-8 (RME-8) protein, and that RME-8 and SNX1 colocalize on early endosomes together with a model cargo of the retrograde route, the receptor-binding B-subunit of Shiga toxin (STxB). RME-8 has previously been found to bind to the clathrin uncoating adenosine triphosphatase (ATPase) Hsc70, and we now report that depletion of RME-8 or Hsc70 affects retrograde trafficking at the early endosomes-TGN interface of STxB and the cation-independent mannose 6-phosphate receptor, an endogenous retrograde cargo protein. We also provide evidence that retromer interacts with the clathrin-binding protein hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) not only via SNX1, as previously published (Chin Raynor MC, Wei X, Chen HQ, Li L. Hrs interacts with sorting nexin 1 and regulates degradation of epidermal growth factor receptor. J Biol Chem 2001;276:7069-7078), but also via the core complex component Vps35. Hrs codistributes at the ultrastructural level with STxB on early endosomes, and interfering with Hrs function using antibodies or mild overexpression inhibits retrograde transport. Our combined data suggest a model according to which the functions in retrograde sorting on early endosomes of SNX1/retromer and clathrin are articulated by RME-8, and possibly also by Hrs.
Popoff
Vincent
V
Institut Curie - Centre de Recherche, Traffic, Signaling and Delivery Laboratory, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
Mardones
Gonzalo A
GA
Bai
Siau-Kun
SK
Chambon
Valérie
V
Tenza
Danièle
D
Burgos
Patricia V
PV
Shi
Anbing
A
Benaroch
Philippe
P
Urbé
Sylvie
S
Lamaze
Christophe
C
Grant
Barth D
BD
Raposo
Graça
G
Johannes
Ludger
L
D002966:Clathrin / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D021381:Protein Transport; D022621:Shiga Toxin / Q000378:metabolism; D058305:Sorting Nexins; D033921:Vesicular Transport Proteins / Q000378:metabolism
D002966:Clathrin; D050883:HSC70 Heat-Shock Proteins; C513978:SNX1 protein, human; D058305:Sorting Nexins; D033921:Vesicular Transport Proteins; D022621:Shiga Toxin