Endocytosis of receptor tyrosine kinases is driven by monoubiquitylation, not polyubiquitylation.
Growth factors stimulate specific receptor tyrosine kinases, but subsequent receptor endocytosis terminates signaling. The ubiquitin ligase c-Cbl targets epidermal growth factor receptors (EGFRs) to endocytosis by tagging them with multiple ubiquitin molecules. However, the type of ubiquitylation is unknown; whereas polyubiquitin chains signal proteasomal degradation, ubiquitin monomers control other processes. We report that in isolation c-Cbl mediates monoubiquitylation rather than polyubiquitylation of EGFRs. Consistent with the sufficiency of monoubiquitylation, when fused to the tail of EGFR, a single ubiquitin induces receptor endocytosis and degradation in cells. By using receptor and ubiquitin mutants, we infer that c-Cbl attaches a founder monoubiquitin to the kinase domain of EGFR and this is complemented by the conjugation of additional monoubiquitins. Hence, receptor tyrosine kinases are desensitized through conjugation of multiple monoubiquitins, which is distinct from polyubiquitin-dependent proteasomal degradation.
Mosesson
Yaron
Y
Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.
Shtiegman
Keren
K
Katz
Menachem
M
Zwang
Yaara
Y
Vereb
Gyorgi
G
Szollosi
Janos
J
Yarden
Yosef
Y
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis; D005822:Genetic Vectors; D015151:Immunoblotting; D051379:Mice; D008856:Microscopy, Fluorescence; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D025801:Ubiquitin / Q000737:chemistry / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases
D011518:Proto-Oncogene Proteins; D025801:Ubiquitin; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; C493849:Cbl protein, mouse