title: Regulation of Sprouty2 stability by mammalian Seven-in-Absentia homolog 2.
abstract: Mammalian Sprouty (Spry) gene expression is rapidly induced upon activation of the FGF receptor signaling pathway in multiple cell types including cells of mesenchymal and epithelial origin. Spry2 inhibits FGF-dependent ERK activation and thus Spry acts as a feedback inhibitor of FGF-mediated proliferation. In addition, Spry2 interacts with the ring-finger-containing E3 ubiquitin ligase, c-Cbl, in a manner that is dependent upon phosphorylation of Tyr55 of Spry2. This interaction results in the poly-ubiquitination and subsequent degradation of Spry2 by the proteasome. Here, we describe the identification of another E3 ubiquitin ligase, human Seven-in-Absentia homolog-2 (SIAH2), as a Spry2 interacting protein. We show by yeast two-hybrid analysis that the N-terminal domain of Spry2 and the ring finger domain of SIAH2 mediated this interaction. Co-expression of SIAH2 resulted in proteasomal degradation of Spry1, 2, and to a lesser extent Spry4. The related E3 ubiquitin-ligase, SIAH1, had little effect on Spry2 protein stability when co-expressed. Unlike c-Cbl-mediated degradation of Spry2, SIAH2-mediated degradation was independent of phosphorylation of Spry2 on Tyr55. Spry2 was also phosphorylated on Tyr227, and phosphorylation of this residue was also dispensable for SIAH2-mediated degradation of Spry2. Finally, co-expression of SIAH2 with Spry2 resulted in a rescue of FGF2-mediated ERK phosphorylation. These data suggest a novel mechanism whereby Spry2 stability is regulated in a manner that is independent of tyrosine phosphorylation, and provides an addition level of control of Spry2 protein levels.
authors.affiliation: Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine 04074-7205, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Nadeau
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Toher
authors.forename: Xuehui
authors.initials: X
authors.lastname: Yang
authors.forename: Dmitry
authors.initials: D
authors.lastname: Kovalenko
authors.forename: Robert
authors.initials: R
authors.lastname: Friesel
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D000098563:Seven in Absentia Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011506:Proteins; C485561:SPRY2 protein, human; D029867:Xenopus Proteins; D016222:Fibroblast Growth Factor 2; D014443:Tyrosine; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins; D017346:Protein Serine-Threonine Kinases; C118389:Spry2 protein, mouse; D048049:Extracellular Signal-Regulated MAP Kinases; D046988:Proteasome Endopeptidase Complex