Ligand-induced ubiquitination of the epidermal growth factor receptor involves the interaction of the c-Cbl RING finger and UbcH7

Masahiro Yokouchi, Takeshi Kondo, Adam Houghton, Marcjanna Bartkiewicz, William C. Horne, Hui Zhang, Akihiko Yoshimura, Roland Baron

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275 Citations (Scopus)

Abstract

c-Cbl plays a negative regulatory role in tyrosine kinase signaling by an as yet undefined mechanism. We demonstrate here, using the yeast two- hybrid system and an in vitro binding assay, that the c-Cbl RING finger domain interacts with UbcH7, a ubiquitin-conjugating enzyme (E2). UbcH7 interacted with the wild-type c-Cbl RING finger domain but not with a RING finger domain that lacks the amino acids that are deleted in 70Z-Cbl, an oncogenic mutant of c-Cbl. The in vitro interaction was enhanced by sequences on both the N- and C-terminal sides of the RING finger. In vivo and in vitro experiments revealed that c-Cbl and UbcH7 synergistically promote the ligand- induced ubiquitination of the epidermal growth factor receptor (EGFR). In contrast, 70Z-Cbl markedly reduced the ligand-induced, UbcH7-mediated ubiquitination of the EGFR. MG132, a proteasome inhibitor, significantly prolonged the ligand-induced phosphorylation of both the EGFR and c-Cbl. Thus, c-Cbl plays an essential role in the ligand-induced ubiquitination of the EGFR by a mechanism that involves an interaction of the RING finger domain with UbcH7. This mechanism participates in the down-regulation of tyrosine kinase receptors and loss of this function, as occurs in the naturally occurring 70Z-Cbl isoform, probably contributes to oncogenic transformation.

Original languageEnglish
Pages (from-to)31707-31712
Number of pages6
JournalJournal of Biological Chemistry
Volume274
Issue number44
DOIs
Publication statusPublished - 1999 Oct 29
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

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