title: Nerve growth factor stimulates the tyrosine phosphorylation of a 38-kDa protein that specifically associates with the src homology domain of phospholipase C-gamma 1.
abstract: The cellular actions of nerve growth factor (NGF) involve changes in protein phosphorylation, initiated by the binding and subsequent activation of its tyrosine kinase receptor, the trk protooncogene (pp140c-trk). Upon exposure to NGF, a 38-kDa tyrosine-phosphorylated protein (pp38) is identified in both PC-12 pheochromocytoma cells and NIH3T3 cells transfected with the full-length human pp140c-trk cDNA (3T3-c-trk) that is specifically coimmunoprecipitated with pp140c-trk or phosphatidylinositol-phospholipase C (PLC)-gamma 1. In both PC-12 and 3T3-c-trk cells, NGF rapidly stimulates the association of pp140c-trk and pp38 with a fusion protein containing the src homology (SH) domains of PLC gamma 1. This phosphorylation and subsequent association are specific for NGF, since epidermal growth factor, platelet-derived growth factor, and insulin do not stimulate the tyrosine phosphorylation of these proteins or their association with the PLC gamma 1 SH domains, although the receptors for these growth factors do undergo tyrosine phosphorylation and association with the PLC-gamma 1 fusion protein under these conditions. Furthermore, the NGF-dependent pp38-SH binding is specific for the SH2 domains of PLC-gamma 1, since the phosphoprotein does not bind to fusion proteins containing SH domains of ras GTPase-activating protein or the p85 subunit of phosphatidylinositol 3 kinase. Both amino- and carboxyl-terminal SH2 domains of PLC-gamma 1 are necessary for the association of pp38 with PLC-gamma 1, although each SH2 domain is sufficient for the association of pp140c-trk with PLC-gamma 1. In both PC-12 and 3T3-c-trk cells, the phosphorylation and association of pp38 with PLC gamma 1 is rapid, occurring maximally at 1 min and declining thereafter. Moreover, this effect of NGF is dose-dependent over a physiological concentration of the growth factor. The specificity and rapidity of pp38 phosphorylation and its association with PLC-gamma 1 suggest that it may be an important component in signal transduction for NGF.
authors.affiliation: Department of Physiology, University of Michigan School of Medicine, Ann Arbor 48109.
authors.forename: M
authors.initials: M
authors.lastname: Ohmichi
authors.forename: S J
authors.initials: SJ
authors.lastname: Decker
authors.forename: A R
authors.initials: AR
authors.lastname: Saltiel
mesh_terms: D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D004247:DNA; D004591:Electrophoresis, Polyacrylamide Gel; D020690:GTPase-Activating Proteins; D016391:Genes, src; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016716:PC12 Cells; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000187:drug effects / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D007527:Isoenzymes; D009414:Nerve Growth Factors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D020703:ras GTPase-Activating Proteins; D014443:Tyrosine; D004247:DNA; D011505:Protein-Tyrosine Kinases; D020917:Receptor, trkA; D010738:Type C Phospholipases