STK/RON receptor tyrosine kinase mediates both apoptotic and growth signals via the multifunctional docking site conserved among the HGF receptor family.
STK/RON tyrosine kinase, a member of the hepatocyte growth factor (HGF) receptor family, is a receptor for macrophage-stimulating protein (MSP). To examine the STK/RON signalling pathway, we generated STK/ RON transfectants showing opposite features in growth. STK/RON-expressing Ba/F3 pro-B cells (BaF/STK) exhibited MSP-dependent growth, whereas STK/ RON-expressing mouse erythroleukaemia cells (MEL/ STK) displayed MSP-induced apoptosis. This apoptosis was accompanied by the prolonged activation of c-Jun N-terminal kinase (JNK), which has recently been implicated in the initiation of apoptosis. Co-immunoprecipitation analyses showed that autophosphorylated STK/RON associated with PLC-gamma, P13-kinase, Shc and Grb2 in both transfectants. However, major tyrosine-phosphorylated proteins, p61 and p65, specifically associated with STK/RON in MEL/STK cells. Mutations at two C-terminal tyrosine residues, Y1330 and Y1337, in the counterpart of the multifunctional docking site of the HGF receptor abolished both MSP-induced growth and apoptosis. Analyses of these mutants and in vitro association revealed that signalling proteins including p61 and p65 directly bound to the phosphotyrosines in the multifunctional docking site. These results demonstrate that positive or negative signals toward cell growth are generated through the multifunctional docking site and suggest the involvement of p61 and p65 as well as JNK in apoptosis. Our findings provide the first evidence for apoptosis via a receptor tyrosine kinase.
Iwama
A
A
Department of Cell Differentiation, Kumamoto University School of Medicine, Japan.
Yamaguchi
N
N
Suda
T
T
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002455:Cell Division / Q000502:physiology*; D002460:Cell Line; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation; D006133:Growth Substances / Q000494:pharmacology / Q000502:physiology; D017228:Hepatocyte Growth Factor; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
D017931:DNA Primers; D006133:Growth Substances; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; C082332:macrophage stimulating protein; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases