Activation of Syk tyrosine kinase is required for c-Cbl-mediated ubiquitination of FcεRI and Syk in RBL cells

Rossella Paolini, Rosa Molfetta, Laurie O. Beitz, Juan Zhang, Andrew M. Scharenberg, Mario Piccoli, Luigi Frati, Reuben Siraganian, Angela Santoni

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Abstract

Engagement of the high affinity receptor for IgE (FcεRI) on mast cells and basophils results in FcεRI β and γ subunits ubiquitination by an as yet undefined mechanism. Here we show that, upon FcεRI engagement on RBL-2H3 cells Syk undergoes ubiquitination and Syk kinase activity is required for its own ubiquitination and that of FcεRI β and γ chains. This requirement was demonstrated by overexpression of Syk wild-type or its kinase-dead mutant in RBL cells or using an Syk-deficient RBL-derived cell line transfected with wild-type or a kinase inactive form of Syk. We also identify c-Cbl as the E3 ligase responsible for both Syk and receptor ubiquitination. Furthermore, we demonstrate that Syk controls tyrosine phosphorylation of Syk-associated Cbl induced after receptor engagement. These data suggest a mutual regulation between Syk and Cbl activities. Finally, we show that a selective inhibitor of proteasome degradation induces persistence of tyrosine-phosphorylated receptor complexes, of activated Syk, and of FcεRI-triggered degranulation. Our results provide a molecular mechanism for down-regulation of engaged receptor complexes by targeting ubiquitinated FcεRI and activated Syk to the proteasome for degradation.

Original languageEnglish
Pages (from-to)36940-36947
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number40
DOIs
Publication statusPublished - Oct 4 2002

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ASJC Scopus subject areas

  • Biochemistry

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Paolini, R., Molfetta, R., Beitz, L. O., Zhang, J., Scharenberg, A. M., Piccoli, M., Frati, L., Siraganian, R., & Santoni, A. (2002). Activation of Syk tyrosine kinase is required for c-Cbl-mediated ubiquitination of FcεRI and Syk in RBL cells. Journal of Biological Chemistry, 277(40), 36940-36947. https://doi.org/10.1074/jbc.M204948200