Distinct requirements for the Sprouty domain for functional activity of Spred proteins.
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.
King
James A J
JA
Department of Surgery, 5th Floor Clinical Sciences Building, University of Melbourne, Royal Melbourne Hospital, Parkville, VIC 3050, Australia.
Straffon
Andrew F L
AF
D'Abaco
Giovanna M
GM
Poon
Carole L C
CL
I
Stacey T T
ST
Smith
Craig M
CM
Buchert
Michael
M
Corcoran
Niall M
NM
Hall
Nathan E
NE
Callus
Bernard A
BA
Sarcevic
Boris
B
Martin
Daniel
D
Lock
Peter
P
Hovens
Christopher M
CM
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
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