The activation of neuronal NO synthase is mediated by G‐protein βγ subunit and the tyrosine phosphatase SHP‐2

In CHO cells we had found that CCK positively regulated cell proliferation via the activation of a soluble guanylate cyclase. Here we demonstrate that CCK stimulated a nitric oxide synthase (NOS) activity. The production of NO was involved in the proliferative response elicited by CCK regarding the inhibitory effect of NOS inhibitors L‐NAME and α‐guanidinoglutaric acid. We identified the NOS activated by the peptide as the neuronal isoform: the expression of the C415A neuronal NOS mutant inhibited both CCK‐induced stimulation of NOS activity and cell proliferation. These two effects were also inhibited after expression of the C459S tyrosine phosphatase SHP‐2 mutant and the βARKl (495–689) sequestrant peptide, indicating the requirement of activated SHP‐2 and G‐βγ subunit. Kinetic analysis (Western blot after coimmunoprecipitation and specific SHP‐2 activity) revealed that in response to CCK‐treatment, SHP‐2 associated to G‐β1 subunit, became activated, and then dephosphorylated the neuronal NOS through a direct association. These data demonstrate that the neuronal NOS is implicated in proliferative effect evoked by CCK. A novel growth signaling pathway is described, involving the activation of neuronal NOS by dephosphorylation of tyrosyl residues.—Cordelier, P., Estève, J.‐P., Rivard, N., Marletta, M., Vaysse, N., Susini, C., Buscail, L. The activation of neuronal no synthase is mediated by G‐protein βγ subunit and the tyrosine phosphatase SHP‐2. FASEB J. 13, 2037–2050 (1999)