Critical role of Src and SHP-2 in sst2 somatostatin receptor-mediated activation of SHP-1 and inhibition of cell proliferation.
The G protein-coupled sst2 somatostatin receptor acts as a negative cell growth regulator. Sst2 transmits antimitogenic signaling by recruiting and activating the tyrosine phosphatase SHP-1. We now identified Src and SHP-2 as sst2-associated molecules and demonstrated their role in sst2 signaling. Surface plasmon resonance and mutation analyses revealed that SHP-2 directly associated with phosphorylated tyrosine 228 and 312, which are located in sst2 ITIMs (immunoreceptor tyrosine-based inhibitory motifs). This interaction was required for somatostatin-induced SHP-1 recruitment and activation and consequent inhibition of cell proliferation. Src interacted with sst2 and somatostatin promoted a transient Gbetagamma-dependent Src activation concomitant with sst2 tyrosine hyperphosphorylation and SHP-2 activation. These steps were abrogated with catalytically inactive Src. Both catalytically inactive Src and SHP-2 mutants abolished somatostatin-induced SHP-1 activation and cell growth inhibition. Sst2-Src-SHP-2 complex formation was dynamic. Somatostatin further induced sst2 tyrosine dephosphorylation and complex dissociation accompanied by Src and SHP-2 inhibition. These steps were defective in cells expressing a catalytically inactive Src mutant. All these data suggest that Src acts upstream of SHP-2 in sst2 signaling and provide evidence for a functional role for Src and SHP-2 downstream of an inhibitory G protein-coupled receptor.
Ferjoux
Geraldine
G
Institut National de la Santé et de la Recherche Médicale U531, IFR31, CHU Rangueil, 31403 Toulouse, France.
Lopez
Frederic
F
Esteve
Jean-Pierre
JP
Ferrand
Audrey
A
Vivier
Eric
E
Vely
Frederic
F
Saint-Laurent
Nathalie
N
Pradayrol
Lucien
L
Buscail
Louis
L
Susini
Christiane
C
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols; D019556:COS Cells; D002455:Cell Division / Q000502:physiology; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003520:Cyclophosphamide; D004252:DNA Mutational Analysis; D004317:Doxorubicin; D047908:Intracellular Signaling Peptides and Proteins; D008958:Models, Molecular; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D051381:Rats; D017481:Receptors, Somatostatin / Q000032:analysis / Q000378:metabolism*; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D020349:Surface Plasmon Resonance; D014750:Vincristine; D019061:src-Family Kinases / Q000378:metabolism*
D047908:Intracellular Signaling Peptides and Proteins; D017481:Receptors, Somatostatin; C051458:vapreotide; D013004:Somatostatin; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; C093733:somatostatin receptor 2; D019061:src-Family Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516727:Ptpn11 protein, rat; C509250:Ptpn6 protein, rat