2. Academic Validation
  3. Spred-2 steady-state levels are regulated by phosphorylation and Cbl-mediated ubiquitination

Spred-2 steady-state levels are regulated by phosphorylation and Cbl-mediated ubiquitination

  • Biochem Biophys Res Commun. 2006 Dec 29;351(4):1018-23. doi: 10.1016/j.bbrc.2006.10.150.
Peter Lock 1,  Stacey T T I,  Andrew F L Straffon,  Heinke Schieb,  Christopher M Hovens,  Stanley S Stylli
Affiliations

Affiliation

  • 1 Cell Signaling Laboratory, Department of Surgery, University of Melbourne, Royal Melbourne Hospital, Parkville 3050, Australia. [email protected]
PMID: 17094949 DOI: 10.1016/j.bbrc.2006.10.150
Abstract

Spred proteins modulate growth factor receptor signaling by inhibiting the Ras-MAPK cascade. Here, we show that Spred-1, Spred-2, and Spred-3 are ubiquitinated in HEK293T cells stimulated with epidermal growth factor (EGF) or pervanadate. Spred-2 tyrosines Y228 and/or Y231 in the Kit binding domain were identified as putative phosphorylation site(s) critical for Spred-2 ubiquitination. Depletion of Cbl and Cbl-b E3 ubiquitin ligases by RNA interference, or overexpression of a Cbl dominant inhibitory mutant (Cbl-N), inhibited Spred-2 ubiquitination, while conversely, wild type Cbl enhanced Spred-2 ubiquitination. Interaction of Spred-2 with Cbl-N was detectable by co-immunoprecipitation and required the Cbl SH2 domain and Spred-2 Y228 and Y231 residues. Studies on endogenous Spred-2 in ME4405 melanoma cells showed that pervanadate induced Spred-2 ubiquitination and a marked reduction in Spred-2 steady-state levels that was partially blocked by the proteasomal inhibitor, MG-132. These results suggest a role for Spred-2 tyrosine phosphorylation and ubiquitination in controlling Spred-2 expression levels.

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