The Cbl proto-oncogene product negatively regulates the Src-family tyrosine kinase Fyn by enhancing its degradation

Christopher E. Andoniou, Nancy L. Lill, Christine B. Thien, Mark L. Lupher, Satoshi Ota, David D.L. Bowtell, Robin M. Scaife, Wallace Y. Langdon, Hamid Band

Research output: Contribution to journalArticle

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Abstract

Fyn is a prototype Src-family tyrosine kinase that plays specific roles in neural development, keratinocyte differentiation, and lymphocyte activation, as well as roles redundant with other Src-family kinases. Similar to other Src-family kinases, efficient regulation of Fyn is achieved through intramolecular binding of its SH3 and SH2 domains to conserved regulatory regions. We have investigated the possibility that the tyrosine kinase regulatory protein Cbl provides a complementary mechanism of Fyn regulation. We show that Cbl overexpression in 293T embryonic kidney and Jurkat T- lymphocyte cells led to a dramatic reduction in the active pool of Fyn; this was seen as a reduction in Fyn autophosphorylation, reduced phosphorylation of in vivo substrates, and inhibition of transcription from a Src-family kinase response element linked to a luciferase reporter. Importantly, a Fyn mutant (FynY528F) relieved of intramolecular repression was still negatively regulated by Cbl. The Cbl-dependent negative regulation of Fyn did not appear to be mediated by inhibition of Fyn kinase activity but was correlated with enhanced protein turnover. Consistent with such a mechanism, elevated levels of Fyn protein were observed in cell lines derived from Cbl(-/-) mice compared to those in wild-type controls. The effects of Cbl on Fyn were not observed when the 70ZCbl mutant protein was analyzed. Taken together, these observations implicate Cbl as a component in the negative regulation of Fyn and potentially other Src-family kinases, especially following kinase activation. These results also suggest that protein degradation may be a general mechanism for Cbl-mediated negative regulation of activated tyrosine kinases.

Original languageEnglish (US)
Pages (from-to)851-867
Number of pages17
JournalMolecular and cellular biology
Volume20
Issue number3
DOIs
StatePublished - Feb 1 2000

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Proto-Oncogenes
src-Family Kinases
Oncogene Proteins
src Homology Domains
Protein-Tyrosine Kinases
Phosphotransferases
Nucleic Acid Regulatory Sequences
Response Elements
Mutant Proteins
Lymphocyte Activation
Luciferases
Keratinocytes
Proteolysis
Proteins
Phosphorylation
T-Lymphocytes
Kidney
Cell Line

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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The Cbl proto-oncogene product negatively regulates the Src-family tyrosine kinase Fyn by enhancing its degradation. / Andoniou, Christopher E.; Lill, Nancy L.; Thien, Christine B.; Lupher, Mark L.; Ota, Satoshi; Bowtell, David D.L.; Scaife, Robin M.; Langdon, Wallace Y.; Band, Hamid.

In: Molecular and cellular biology, Vol. 20, No. 3, 01.02.2000, p. 851-867.

Research output: Contribution to journalArticle

Andoniou, CE, Lill, NL, Thien, CB, Lupher, ML, Ota, S, Bowtell, DDL, Scaife, RM, Langdon, WY & Band, H 2000, 'The Cbl proto-oncogene product negatively regulates the Src-family tyrosine kinase Fyn by enhancing its degradation', Molecular and cellular biology, vol. 20, no. 3, pp. 851-867. https://doi.org/10.1128/MCB.20.3.851-867.2000
Andoniou, Christopher E. ; Lill, Nancy L. ; Thien, Christine B. ; Lupher, Mark L. ; Ota, Satoshi ; Bowtell, David D.L. ; Scaife, Robin M. ; Langdon, Wallace Y. ; Band, Hamid. / The Cbl proto-oncogene product negatively regulates the Src-family tyrosine kinase Fyn by enhancing its degradation. In: Molecular and cellular biology. 2000 ; Vol. 20, No. 3. pp. 851-867.
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