Participation of Tom1L1 in EGF-stimulated endocytosis of EGF receptor.
Although many proteins have been shown to participate in ligand-stimulated endocytosis of EGF receptor (EGFR), the adaptor protein responsible for interaction of activated EGFR with endocytic machinery remains elusive. We show here that EGF stimulates transient tyrosine phosphorylation of Tom1L1 by the Src family kinases, resulting in transient interaction of Tom1L1 with the activated EGFR bridged by Grb2 and Shc. Cytosolic Tom1L1 is recruited onto the plasma membrane and subsequently redistributes into the early endosome. Mutant forms of Tom1L1 defective in Tyr-phosphorylation or interaction with Grb2 are incapable of interaction with EGFR. These mutants behave as dominant-negative mutants to inhibit endocytosis of EGFR. RNAi-mediated knockdown of Tom1L1 inhibits endocytosis of EGFR. The C-terminal tail of Tom1L1 contains a novel clathrin-interacting motif responsible for interaction with the C-terminal region of clathrin heavy chain, which is important for exogenous Tom1L1 to rescue endocytosis of EGFR in Tom1L1 knocked-down cells. These results suggest that EGF triggers a transient Grb2/Shc-mediated association of EGFR with Tyr-phosphorylated Tom1L1 to engage the endocytic machinery for endocytosis of the ligand-receptor complex.
Cancer and Developmental Cell Biology Division, Institute of Molecular and Cell Biology, Singapore.
Ning Sheng
NS
Liu
Li Shen
LS
Loo
Eva
E
Loh
Li-Fong
LF
Seet
Wanjin
W
Hong
D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D004705:Endocytosis / Q000187:drug effects* / Q000235:genetics*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008954:Models, Biological; D050505:Mutant Proteins / Q000378:metabolism / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
D048868:Adaptor Proteins, Signal Transducing; D050505:Mutant Proteins; D034741:RNA, Small Interfering; C499446:TOM1L1 protein, human; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors