A two-tiered mechanism of EGFR inhibition by RALT/MIG6 via kinase suppression and receptor degradation.
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.
Frosi
Yuri
Y
Istituto Regina Elena, Rome, Italy.
Anastasi
Sergio
S
Ballarò
Costanza
C
Varsano
Giulia
G
Castellani
Loriana
L
Maspero
Elena
E
Polo
Simona
S
Alemà
Stefano
S
Segatto
Oreste
O
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
D048868:Adaptor Proteins, Signal Transducing; C475819:Errfi1 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D010770:Phosphotransferases; D066246:ErbB Receptors