Saint-Pol Agnès, Yélamos Belén, Amessou Mohamed, Mills Ian G, Dugast Marc, Tenza Danièle, Schu Peter, Antony Claude, McMahon Harvey T, Lamaze Christophe, Johannes Ludger
Laboratoire Trafic et Signalisation, 75248 Paris Cedex 05, France.
Dev Cell. 2004 Apr;6(4):525-38. doi: 10.1016/s1534-5807(04)00100-5.
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.
逆向运输将早期/循环内体与反式高尔基体网络（TGN）相连，从而连接内吞途径和生物合成/分泌途径。为了确定内化分子如何靶向逆向途径，我们干扰了网格蛋白以及与它相互作用的两种蛋白质AP1和epsinR的功能。我们发现，当网格蛋白表达受到抑制时，结合糖鞘脂的细菌志贺毒素能高效进入细胞。然而，志贺毒素向TGN的逆向运输受到强烈抑制。这使我们能够证明，对于志贺毒素而言，早期/循环内体上的逆向分选依赖于网格蛋白和epsinR，而不依赖于AP1。EpsinR也参与了两种内源性蛋白质TGN38/46和甘露糖6-磷酸受体的逆向运输。总之，我们的工作揭示了逆向途径中存在不依赖和依赖网格蛋白的运输步骤，并确立了网格蛋白和epsinR在内体-TGN界面的功能。
