title: Tyrosine 763 of the murine granulocyte colony-stimulating factor receptor mediates Ras-dependent activation of the JNK/SAPK mitogen-activated protein kinase pathway.
abstract: The receptor for granulocyte colony-stimulating factor (G-CSF) can mediate differentiation and proliferation of hemopoietic cells. A proliferative signal is associated with activation of the ERK mitogen-activated protein kinase (MAPK) pathway. To determine whether other MAPK pathways are activated by G-CSF signalling, we have investigated activation of JNK/SAPK in cells proliferating in response to G-CSF. Here we show that G-CSF and interleukin-3 activate JNK/SAPK in two hemopoietic cell lines. The region of the G-CSF receptor required for G-CSF-induced JNK/SAPK activation is located within the C-terminal 68 amino acids of the cytoplasmic domain, which contains Tyr 763. Mutation of Tyr 763 to Phe completely blocks JNK/SAPK activation. However, the C-terminal 68 amino acids are not required for ERK2 activation. We show that activation of JNK/SAPK, like that of ERK2, is dependent on Ras but that higher levels of Ras-GTP are associated with activation of JNK/SAPK than with activation of ERK2. Two separate functional regions of the G-CSF receptor contribute to activation of Ras. The Y763F mutation reduces G-CSF-induced Ras activation from 30 to 35% Ras-GTP to 10 to 13% Ras-GTP. Low levels of Ras activation (10 to 13% Ras-GTP), which are sufficient for ERK2 activation, require only the 100 membrane-proximal amino acids. High levels of Ras-GTP provided by expression of oncogenic Ras are not sufficient to activate JNK/SAPK. An additional signal, also mediated by Tyr 763, is required for activation of JNK/SAPK.
authors.affiliation: CRC Center for Cell and Molecular Biology, Institute of Cancer Research, Chester Beatty Laboratories, London, United Kingdom.
authors.forename: O
authors.initials: O
authors.lastname: Rausch
authors.forename: C J
authors.initials: CJ
authors.lastname: Marshall
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells; D007377:Interleukin-3 / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000378:metabolism*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000502:physiology*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014443:Tyrosine / Q000378:metabolism*; D018631:ras Proteins / Q000502:physiology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D007377:Interleukin-3; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D016179:Granulocyte Colony-Stimulating Factor; D014443:Tyrosine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D018631:ras Proteins