A CSF-1 receptor phosphotyrosine 559 signaling pathway regulates receptor ubiquitination and tyrosine phosphorylation.
Receptor tyrosine kinase (RTK) activation involves ligand-induced receptor dimerization and transphosphorylation on tyrosine residues. Colony-stimulating factor-1 (CSF-1)-induced CSF-1 receptor (CSF-1R) tyrosine phosphorylation and ubiquitination were studied in mouse macrophages. Phosphorylation of CSF-1R Tyr-559, required for the binding of Src family kinases (SFKs), was both necessary and sufficient for these responses and for c-Cbl tyrosine phosphorylation and all three responses were inhibited by SFK inhibitors. In c-Cbl-deficient macrophages, CSF-1R ubiquitination and tyrosine phosphorylation were substantially inhibited. Reconstitution with wild-type, but not ubiquitin ligase-defective C381A c-Cbl rescued these responses, while expression of C381A c-Cbl in wild-type macrophages suppressed them. Analysis of site-directed mutations in the CSF-1R further suggests that activated c-Cbl-mediated CSF-1R ubiquitination is required for a conformational change in the major kinase domain that allows amplification of receptor tyrosine phosphorylation and full receptor activation. Thus the results indicate that CSF-1-mediated receptor dimerization leads to a Tyr-559/SFK/c-Cbl pathway resulting in receptor ubiquitination that permits full receptor tyrosine phosphorylation of this class III RTK in macrophages.
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
Ying
Y
Xiong
Da
D
Song
Yunfei
Y
Cai
Wenfeng
W
Yu
Yee-Guide
YG
Yeung
E Richard
ER
Stanley
D057809:HEK293 Cells; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation / Q000502:physiology; D019000:Phosphotyrosine / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology*; D019061:src-Family Kinases / Q000378:metabolism
D019000:Phosphotyrosine; D014443:Tyrosine; D016173:Macrophage Colony-Stimulating Factor; D044767:Ubiquitin-Protein Ligases; D016186:Receptor, Macrophage Colony-Stimulating Factor; D019061:src-Family Kinases