title: p75 nerve growth factor receptor modulates p140trkA kinase activity, but not ligand internalization, in PC12 cells.
abstract: The biological activity of nerve growth factor (NGF) has been shown to be mediated by the p140trkA receptor tyrosine kinase, while the role of the p75 NGF receptor (p75NGFR) is still unresolved. Here we have investigated the relative contribution of p140trkA and p75NGFR to early consequences of NGF binding: ligand internalization, p140trkA autophosphorylation, and tyrosine phosphorylation of Shc, phospholipase C gamma-1 (PLC gamma-1), and extracellular signal-regulated kinases (ERKs). It was found that NGF internalization was neither prevented by blocking p140trkA activity using the protein kinase inhibitors methylthioadenosine, staurosporine, and K-252a, nor by inhibiting NGF binding to p75NGFR with antibodies. However, when NGF binding to p140trkA was reduced by the use of a synthetic peptide corresponding to amino acids 36-53 of human p140trkA, internalization of NGF was decreased. Thus, at least in PC12 cells, internalization appears to require binding of NGF to p140trkA, but occurs irrespective of p140trkA kinase activity and ligand occupancy of p75NGFR. The NGF triple mutant Lys-32/Lys-34/Glu-35 to Ala, which has been demonstrated to bind to p140trkA, but not to p75NGFR, induced tyrosine phosphorylation more rapidly than wild-type NGF. Likewise, NGF-induced tyrosine phosphorylation was accelerated when NGF binding to p75NGFR was prevented with REX-IgG. These findings indicate that NGF bindign by p75NGFR may modulate NGF-induced p140trkA kinase activity.
authors: F. Hoffmann-La Roche Ltd., Pharma Division, Basel, Switzerland.
authors: P
authors: P
authors: Kahle
authors: P A
authors: PA
authors: Barker
authors: E M
authors: EM
authors: Shooter
authors: C
authors: C
authors: Hertel
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology*; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins / Q000276:immunology / Q000502:physiology*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases; D009363:Neoplasm Proteins / Q000378:metabolism; D009414:Nerve Growth Factors / Q000235:genetics / Q000378:metabolism*; D016716:PC12 Cells / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000037:antagonists & inhibitors / Q000276:immunology / Q000502:physiology*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000502:physiology*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000911:Antibodies, Monoclonal; D008024:Ligands; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D011506:Proteins; D011518:Proto-Oncogene Proteins; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048053:Mitogen-Activated Protein Kinase 6; D020928:Mitogen-Activated Protein Kinases