Evidence for direct interaction between Sprouty and Cbl.
Sprouty (SPRY) was first identified in a genetic screen in Drosophila as an antagonist of fibroblast and epidermal growth factor receptors and Sevenless signaling, seemingly by inhibiting the receptor tyrosine kinase (RTK)/Ras/MAPK pathway. To date, four mammalian Sprouty genes have been identified; the primary sequences of the gene products share a well conserved cysteine-rich C-terminal domain with their Drosophila counterpart. The N-terminal regions do not, however, exhibit a large degree of homology. This study was aimed at identifying proteins with which human SPRY2 (hSPRY2) interacts in an attempt to understand the mechanism by which Sprouty proteins exert their down-regulatory effects. Here, we demonstrate that hSPRY2 associates directly with c-Cbl, a known down-regulator of RTK signaling. A short sequence in the N terminus of hSPRY2 was found to bind directly to the Ring finger domain of c-Cbl. Parallel binding was apparent between the Drosophila homologs of Sprouty and Cbl, with cross-species associations occurring at least in vitro. Coexpression of hSPRY2 abrogated an increase in the rate of epidermal growth factor receptor internalization induced by c-Cbl, whereas a mutant hSPRY2 protein unable to bind c-Cbl showed no such effect. Our results suggest that one function of hSPRY2 in signaling processes downstream of RTKs may be to modulate c-Cbl physiological function such as that seen with receptor-mediated endocytosis.
Wong
E S
ES
Signal Transduction Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, Singapore 117609, Singapore.
Lim
J
J
Low
B C
BC
Chen
Q
Q
Guy
G R
GR
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015536:Down-Regulation; D004330:Drosophila; D029721:Drosophila Proteins; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D005136:Eye Proteins / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors; D006801:Humans; D019476:Insect Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D020794:Receptor Protein-Tyrosine Kinases; D015398:Signal Transduction; D013045:Species Specificity; D044767:Ubiquitin-Protein Ligases
D029721:Drosophila Proteins; D005136:Eye Proteins; D019476:Insect Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; C404992:Spry2 protein, rat; C110486:sty protein, Drosophila; D005346:Fibroblast Growth Factors; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D066246:ErbB Receptors; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila; C067419:CBL protein, human