title: The endophilin-CIN85-Cbl complex mediates ligand-dependent downregulation of c-Met.
abstract: Ligand-dependent downregulation of tyrosine kinase receptors is a critical step for modulating their activity. Upon ligand binding, hepatocyte growth factor (HGF) receptor (Met) is polyubiquitinated and degraded; however, the mechanisms underlying HGF receptor endocytosis are not yet known. Here we demonstrate that a complex involving endophilins, CIN85 and Cbl controls this process. Endophilins are regulatory components of clathrin-coated vesicle formation. Through their acyl-transferase activity they are thought to modify the membrane phospholipids and induce negative curvature and invagination of the plasma membrane during the early steps of endocytosis. Furthermore, by means of their Src-homology 3 domains, endophilins are able to bind CIN85, a recently identified protein that interacts with the Cbl proto-oncogene. Cbl, in turn, binds and ubiquitinates activated HGF receptor, and by recruiting the endophilin-CIN85 complex, it regulates receptor internalization. Inhibition of complex formation is sufficient to block HGF receptor internalization and to enhance HGF-induced signal transduction and biological responses. These data provide further evidence of a relationship between receptor-mediated signalling and endocytosis, and disclose a novel functional role for Cbl in HGF receptor signalling.
authors.affiliation: CNR-CIOS and Department of Genetics, Biology and Biochemistry, University of Torino, 10126 Torino, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Petrelli
authors.forename: Giorgio F
authors.initials: GF
authors.lastname: Gilestro
authors.forename: Stefania
authors.initials: S
authors.lastname: Lanzardo
authors.forename: Paolo M
authors.initials: PM
authors.lastname: Comoglio
authors.forename: Nicola
authors.initials: N
authors.lastname: Migone
authors.forename: Silvia
authors.initials: S
authors.lastname: Giordano
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects*; D004705:Endocytosis / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D008024:Ligands; D046911:Macromolecular Substances; D009154:Mutation / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D008024:Ligands; C000715470:MAS1 protein, human; D046911:Macromolecular Substances; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; C107640:SH3GL2 protein, human; C433810:SH3KBP1 protein, human; D025801:Ubiquitin; D004815:Epidermal Growth Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D019859:Proto-Oncogene Proteins c-met; C067419:CBL protein, human