title: An incomplete program of cellular tyrosine phosphorylations induced by kinase-defective epidermal growth factor receptors.
abstract: Although signaling by the epidermal growth factor (EGF) receptor is thought to be dependent on receptor tyrosine kinase activity, it is clear that mitogen-activated protein (MAP) kinase can be activated by receptors lacking kinase activity. Since analysis of the signaling pathways used by kinase-defective receptors could reveal otherwise masked capabilities, we examined in detail the tyrosine phosphorylations and enzymes of the MAP kinase pathway induced by kinase-defective EGF receptors. Following EGF stimulation of B82L cells expressing a kinase-defective EGF receptor mutant (K721M), we found that ERK2 and ERK1 MAP kinases, as well as MEK1 and MEK2 were all activated, and SHC became prominently tyrosine-phosphorylated. By contrast, kinase-defective receptors failed to induce detectable phosphorylations of GAP (GTPase-activating protein), p62, JAK1, or p91STAT1, all of which were robustly phosphorylated by wild-type receptors. These data demonstrate that kinase-defective receptors induce several protein tyrosine phosphorylations, but that these represent only a subset of those seen with wild-type receptors. This suggests that kinase-defective receptors activate a heterologous tyrosine kinase with a specificity different from the EGF receptor. We found that kinase-defective receptors induced ErbB2/c-Neu enzymatic activation and ErbB2/c-Neu binding to SHC at a level even greater than that induced by wild-type receptors. Thus, heterodimerization with and activation of endogenous ErbB2/c-Neu is a possible mechanism by which kinase-defective receptors stimulate the MAP kinase pathway.
authors.affiliation: Department of Microbiology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Wright
authors.forename: C W
authors.initials: CW
authors.lastname: Reuter
authors.forename: M J
authors.initials: MJ
authors.lastname: Weber
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D051380:GRB2 Adaptor Protein; D020690:GTPase-Activating Proteins; D006801:Humans; D053614:Janus Kinase 2; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D019000:Phosphotyrosine; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004268:DNA-Binding Proteins; D066246:ErbB Receptors; D051380:GRB2 Adaptor Protein; D020690:GTPase-Activating Proteins; D053614:Janus Kinase 2; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D019000:Phosphotyrosine; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D050794:STAT1 Transcription Factor; D015534:Trans-Activators; D014443:Tyrosine; C495948:GRB2 protein, human; C495949:Grb2 protein, mouse; C494079:STAT1 protein, human; C494080:Stat1 protein, mouse; C482128:MAP2K2 protein, human; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse