title: Distinct requirements for the Sprouty domain for functional activity of Spred proteins.
abstract: Sprouty and Spred {Sprouty-related EVH1 [Ena/VASP (vasodilator-stimulated phosphoprotein) homology 1] domain} proteins have been identified as antagonists of growth factor signalling pathways. We show here that Spred-1 and Spred-2 appear to have distinct mechanisms whereby they induce their effects, as the Sprouty domain of Spred-1 is not required to block MAPK (mitogen-activated protein kinase) activation, while that of Spred-2 is required. Similarly, deletion of the C-terminal Sprouty domain of Spred-1 does not affect cell-cycle progression of G(0)-synchronized cells through to S-phase following growth factor stimulation, while the Sprouty domain is required for Spred-2 function. We also demonstrate that the inhibitory function of Spred proteins is restricted to the Ras/MAPK pathway, that tyrosine phosphorylation is not required for this function, and that the Sprouty domain mediates heterodimer formation of Spred proteins. Growth-factor-mediated activation of the small GTPases, Ras and Rap1, was able to be regulated by Spred-1 and Spred-2, without affecting receptor activation. Taken together, these results highlight the potential for different functional roles of the Sprouty domain within the Spred family of proteins, suggesting that Spred proteins may use different mechanisms to induce inhibition of the MAPK pathway.
authors.affiliation: Department of Surgery, 5th Floor Clinical Sciences Building, University of Melbourne, Royal Melbourne Hospital, Parkville, VIC 3050, Australia.
authors.forename: James A J
authors.initials: JA
authors.lastname: King
authors.forename: Andrew F L
authors.initials: AF
authors.lastname: Straffon
authors.forename: Giovanna M
authors.initials: GM
authors.lastname: D'Abaco
authors.forename: Carole L C
authors.initials: CL
authors.lastname: Poon
authors.forename: Stacey T T
authors.initials: ST
authors.lastname: I
authors.forename: Craig M
authors.initials: CM
authors.lastname: Smith
authors.forename: Michael
authors.initials: M
authors.lastname: Buchert
authors.forename: Niall M
authors.initials: NM
authors.lastname: Corcoran
authors.forename: Nathan E
authors.initials: NE
authors.lastname: Hall
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Callus
authors.forename: Boris
authors.initials: B
authors.lastname: Sarcevic
authors.forename: Daniel
authors.initials: D
authors.lastname: Martin
authors.forename: Peter
authors.initials: P
authors.lastname: Lock
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Hovens
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000818:Animals; D002460:Cell Line; D019281:Dimerization; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000502:physiology; D008565:Membrane Proteins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry* / Q000502:physiology; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D012097:Repressor Proteins; C504812:SPRED1 protein, human; C500760:SPRED2 protein, human; C433763:Spred1 protein, mouse; C433764:Spred2 protein, mouse; D020928:Mitogen-Activated Protein Kinases; D020559:Monomeric GTP-Binding Proteins