Fyn kinase-directed activation of SH2 domain-containing protein-tyrosine phosphatase SHP-2 by G(i) protein-coupled receptors in Madin-Darby canine kidney cells

SHP-2, an SH2 domain-containing protein-tyrosine phosphatase, plays an impo rtant role in receptor tyrosine kinase-regulated cell proliferation and dif ferentiation, Little is known about the activation mechanisms and the parti cipation of SHP-2 in the activity of G protein-coupled receptors lacking in trinsic tyrosine kinase activity. We show that the activity of SHP-2 (but n ot SHP-1) is specifically stimulated by the selective alpha(2A)-adrenergic receptor agonist UK14304 and by lysophosphatidic acid (LPA) in Madin-Darby canine kidney (MDCK) cells. UK14304 and LPA promote the tyrosine phosphoryl ation of SHP-2 and its association with Grb2, The agonist-induced direct in teraction of Grb2 with SHP-2 is mediated by the SH2 domain of Grb2 and the tyrosine phosphorylation of SHP-2. Rapid activation of Src family kinase by UK14304 preceded the SHP-2 activation. Among the Src family members (Src, Fyn, Lck, Yes, and Lyn) present in MDCK cells, Fyn was the only one specifi cally associated with SHP-2, and the physical interaction between them, whi ch requires the Src family kinase activity, was increased in response to th e agonists, Pertussis toxin, PP1 (a selective Src family kinase inhibitor), or overexpression of a catalytically inactive mutant of Fyn blocked the UK 14304- or LPA-stimulated activity of SHP-2, SHP-2 tyrosine phosphorylation, and SHP-2 association with Grb2. Therefore, we have demonstrated for the f irst time that the activation of SHP-2 by these G(i) protein-coupled recept ors requires Fyn kinase and that there is a specific physical interaction o f Fyn kinase with SHP-2 in MDCK cells.