Neuronal nitric oxide synthase: a substrate for SHP-1 involved in sst2 somatostatin receptor growth inhibitory signaling.
Somatostatin receptor sst2 is an inhibitory G protein-coupled receptor, which inhibits normal and tumor cell growth by a mechanism involving the tyrosine phosphatase SHP-1. We reported previously that SHP-1 associates transiently with and is activated by sst2 and is a critical component for sst2 growth inhibitory signaling. Here, we demonstrate that in Chinese hamster ovary cells expressing sst2, SHP-1 is associated at the basal level with the neuronal nitric oxide synthase (nNOS). Following sst2 activation by the somatostatin analog RC-160, SHP-1 rapidly recruits nNOS tyrosine dephosphorylates and activates it. The resulting NO activates guanylate cyclase and inhibits cell proliferation. Coexpression of a catalytically inactive SHP-1 mutant with sst2 blocks RC-160-induced nNOS dephosphorylation and activation, as well as guanylate cyclase activation. In mouse pancreatic acini, RC-160 treatment reduces nNOS tyrosine phosphorylation accompanied by an increase of its activity. By opposition, in acini from viable motheaten (mev/mev) mice, which express a markedly inactive SHP-1, RC-160 has no effect on nNOS activity. Finally, expression of a dominant-negative form of nNOS prevents both RC-160-induced p27 up-regulation and cell proliferation inhibition. We therefore identified nNOS as a novel SHP-1 substrate critical for sst2-induced cell-growth arrest.
Lopez
F
F
INSERM U 531, IFR 31, CHU Rangueil, 31403 Toulouse Cedex 4, France.
Ferjoux
G
G
Cordelier
P
P
Saint-Laurent
N
N
Estève
J P
JP
Vaysse
N
N
Buscail
L
L
Susini
C
C
D000818:Animals; D016466:CHO Cells; D002455:Cell Division; D006224:Cricetinae; D006152:Cyclic GMP / Q000096:biosynthesis; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008954:Models, Biological; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism* / Q000502:physiology*; D052248:Nitric Oxide Synthase Type I; D010766:Phosphorylation; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism* / Q000502:physiology; D017481:Receptors, Somatostatin / Q000502:physiology*; D015398:Signal Transduction; D013004:Somatostatin / Q000494:pharmacology
D047908:Intracellular Signaling Peptides and Proteins; D017481:Receptors, Somatostatin; D009569:Nitric Oxide; D013004:Somatostatin; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C509248:Ptpn6 protein, mouse; D006152:Cyclic GMP