title: A two-tiered mechanism of EGFR inhibition by RALT/MIG6 via kinase suppression and receptor degradation.
abstract: Signaling by epidermal growth factor receptor (EGFR) must be controlled tightly because aberrant EGFR activity may cause cell transformation. Receptor-associated late transducer (RALT) is a feedback inhibitor of EGFR whose genetic ablation in the mouse causes phenotypes due to EGFR-driven excess cell proliferation. RALT inhibits EGFR catalytic activation by docking onto EGFR kinase domain. We report here an additional mechanism of EGFR suppression mediated by RALT, demonstrating that RALT-bound EGF receptors undergo endocytosis and eventual degradation into lysosomes. Moreover, RALT rescues the endocytic deficit of EGFR mutants unable to undergo either endocytosis (Dc214) or degradation (Y1045F) and mediates endocytosis via a domain distinct from that responsible for EGFR catalytic suppression. Consistent with providing a scaffolding function for endocytic proteins, RALT drives EGFR endocytosis by binding to AP-2 and Intersectins. These data suggest a model in which binding of RALT to EGFR integrates suppression of EGFR kinase with receptor endocytosis and degradation, leading to durable repression of EGFR signaling.
authors.affiliation: Istituto Regina Elena, Rome, Italy.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Frosi
authors.forename: Sergio
authors.initials: S
authors.lastname: Anastasi
authors.forename: Costanza
authors.initials: C
authors.lastname: Ballarò
authors.forename: Giulia
authors.initials: G
authors.lastname: Varsano
authors.forename: Loriana
authors.initials: L
authors.lastname: Castellani
authors.forename: Elena
authors.initials: E
authors.lastname: Maspero
authors.forename: Simona
authors.initials: S
authors.lastname: Polo
authors.forename: Stefano
authors.initials: S
authors.lastname: Alemà
authors.forename: Oreste
authors.initials: O
authors.lastname: Segatto
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C475819:Errfi1 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D010770:Phosphotransferases; D066246:ErbB Receptors