A novel juxtamembrane deletion in rat TrkA blocks differentiative but not mitogenic cell signaling in response to nerve growth factor.
We have generated a novel rat TrkA receptor mutant (TrkAS3) by deletion of five conserved residues (493IMENP497) in the juxtamembrane domain. TrkAS3 receptors cannot support nerve growth factor (NGF)-induced cell cycle arrest or neuronal differentiation but retain cell survival responses as well as Ras-dependent mitogenic signaling. Cells of the nnr5 line stably expressing TrkAS3 induce NGF-dependent SHC phosphorylation and phosphatidylinositol 3-kinase, phospholipase Cgamma-1, and prolonged mitogen-activated protein kinase activation to absolute levels comparable to those in PC12 cells. Although the stoichiometry of TrkAS3-SHC binding is reduced, cells overexpressing TrkAS3 exhibit NGF-dependent SHC-Grb-2/Sos binding, essential for Ras activation, as well as NGF-dependent SNT phosphorylation to absolute levels comparable to those in PC12 cells. Collectively, these data suggest that the TrkAS3 deletion either directly affects a novel Ras-independent TrkA binding protein or that the decrease in TrkAS3-SHC association affects a Ras-independent SHC binding protein essential for cell cycle arrest and/or neurite outgrowth.
Meakin
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John P. Robarts Research Institute, Department of Biochemistry, University of Western Ontario, London, Canada.
MacDonald
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D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000502:physiology; D017781:Genes, Immediate-Early / Q000235:genetics; D008938:Mitosis / Q000502:physiology*; D009414:Nerve Growth Factors / Q000493:pharmacokinetics / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016716:PC12 Cells; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000502:physiology*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D009414:Nerve Growth Factors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017475:Receptors, Nerve Growth Factor; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA