Direct interaction of Cbl with pTyr 1045 of the EGF receptor (EGFR) is required to sort the EGFR to lysosomes for degradation.
Mutation of the binding site for Cbl (Tyr1045) in the EGF receptor (EGFR) results in impaired ubiquitination but does not affect EGFR internalization. However, the Y1045F mutation resulted in strongly decreased degradation of the EGFR, as well as efficient recycling of EGFR to the plasma membrane. Significantly, more wild-type EGFR than Y1045F EGFR was found localizing to multivesicular late endosomes. Ubiquitination of the EGFR was in HeLa cells inhibited both upon overexpressing the N-terminal part of Cbl and upon overexpressing a double mutant Grb2 incapable of interacting with Cbl and thereby being incapable of indirectly recruiting Cbl to the EGFR. Collectively, these data suggest that the ubiquitination resulting from direct binding of Cbl to pTyr1045 of the EGFR is critical for lysosomal sorting of the EGFR in contrast to ubiquitination resulting from Grb2-mediated binding of Cbl to the EGFR.
Institute of Pathology, University of Oslo, Rikshospitalet, N-0027 Oslo, Norway.
Lene Melsaether
LM
Grøvdal
Espen
E
Stang
Alexander
A
Sorkin
Inger Helene
IH
Madshus
D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D004815:Epidermal Growth Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D066246:ErbB Receptors; C067419:CBL protein, human