Threshold‐controlled ubiquitination of the EGFR directs receptor fate

S Sigismund, V Algisi, G Nappo, A Conte… - The EMBO …, 2013 - embopress.org
S Sigismund, V Algisi, G Nappo, A Conte, R Pascolutti, A Cuomo, T Bonaldi, E Argenzio…
The EMBO journal, 2013embopress.org
How the cell converts graded signals into threshold‐activated responses is a question of
great biological relevance. Here, we uncover a nonlinear modality of epidermal growth
factor receptor (EGFR)‐activated signal transduction, by demonstrating that the
ubiquitination of the EGFR at the PM is threshold controlled. The ubiquitination threshold is
mechanistically determined by the cooperative recruitment of the E3 ligase Cbl, in complex
with Grb2, to the EGFR. This, in turn, is dependent on the simultaneous presence of two …
How the cell converts graded signals into threshold‐activated responses is a question of great biological relevance. Here, we uncover a nonlinear modality of epidermal growth factor receptor (EGFR)‐activated signal transduction, by demonstrating that the ubiquitination of the EGFR at the PM is threshold controlled. The ubiquitination threshold is mechanistically determined by the cooperative recruitment of the E3 ligase Cbl, in complex with Grb2, to the EGFR. This, in turn, is dependent on the simultaneous presence of two phosphotyrosines, pY1045 and either one of pY1068 or pY1086, on the same EGFR moiety. The dose–response curve of EGFR ubiquitination correlate precisely with the non‐clathrin endocytosis (NCE) mode of EGFR internalization. Finally, EGFR‐NCE mechanistically depends on EGFR ubiquitination, as the two events can be simultaneously re‐engineered on a phosphorylation/ubiquitination‐incompetent EGFR backbone. Since NCE controls the degradation of the EGFR, our findings have implications for how the cell responds to increasing levels of EGFR signalling, by varying the balance of receptor signalling and degradation/attenuation.
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