Distinct regions of the granulocyte colony-stimulating factor receptor are required for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK.
The protein tyrosine kinases JAK1 and JAK2 are phosphorylated tyrosine after the interaction of granulocyte colony-stimulating factor (G-CSF) with its transmembrane receptor. So too is Stat3, a member of the STAT family of transcriptional activators thought to be activated by the JAK kinases. Truncated G-CSF receptor (G-CSF-R) mutants were used to determine the different regions of the cytoplasmic domain necessary for tyrosine phosphorylation of the signaling molecules JAK2, Stat3, and p42, p44MAPK. We have shown that G-CSF-induced tyrosine phosphorylation and kinase activation of JAK2 requires the membrane proximal 57 amino acids of the cytoplasmic domain. In contrast, maximal Stat3 tyrosine phosphorylation required amino acids 96 to 183 of the G-CSF-R cytoplasmic domain, Stat3 DNA binding could occur with a receptor truncated 96 amino acids from the transmembrane domain and containing a single tyrosine residue, but was reduced in comparison with the full-length receptor. Together with the tyrosine phosphorylation of Stat3, this finding suggests that additional Stat3 does not appear to be required for proliferation. MAP kinase tyrosine phosphorylation correlated with both the proliferative response and JAK2 activation.
Nicholson
S E
SE
Melbourne Tumour Biology Branch, Ludwig Institute for Cancer Research, Victoria Australia.
Novak
U
U
Ziegler
S F
SF
Layton
J E
JE
D000595:Amino Acid Sequence; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D053614:Janus Kinase 2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000737:chemistry* / Q000502:physiology; D050796:STAT3 Transcription Factor; D015398:Signal Transduction / Q000502:physiology*; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000235:genetics*
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D016179:Granulocyte Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; D053614:Janus Kinase 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases