The Cbl protooncoprotein stimulates CSF-1 receptor multiubiquitination and endocytosis, and attenuates macrophage proliferation.
Colony-stimulating factor-1 (CSF-1) activation of the CSF-1 receptor (CSF-1R) causes Cbl protooncoprotein tyrosine phosphorylation, Cbl-CSF-1R association and their simultaneous multiubiquitination at the plasma membrane. The CSF-1R is then rapidly internalized and degraded, whereas Cbl is deubiquitinated in the cytoplasm without being degraded. We have used primary macrophages from gene-targeted mice to study the role of Cbl. Cbl-/- macrophages form denser colonies and, at limiting CSF-1 concentrations, proliferate faster than Cbl+/+ macrophages. Their CSF-1Rs fail to exhibit multiubiquitination and a second wave of tyrosine phosphorylation previously suggested to be involved in preparation of the CSF-1-CSF-1R complex for endocytosis. Consistent with this result, Cbl-/- macrophage cell surface CSF-1-CSF-1R complexes are internalized more slowly, yet are still lysosomally degraded, and the CSF-1 utilization by Cbl-/- macrophages is reduced approximately 2-fold. Thus, attenuation of proliferation by Cbl is associated with its positive regulation of the coordinated multiubiquitination and endocytosis of the activated CSF-1R, and a reduction in the time that the CSF-1R signals from the cell surface. The results provide a paradigm for studies of the mechanisms underlying Cbl attenuation of proliferative responses induced by ligation of receptor tyrosine kinases.
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
P S
PS
Lee
Y
Y
Wang
M G
MG
Dominguez
Y G
YG
Yeung
M A
MA
Murphy
D D
DD
Bowtell
E R
ER
Stanley
D000818:Animals; D002455:Cell Division; D048429:Cell Size; D002470:Cell Survival; D002471:Cell Transformation, Neoplastic; D015536:Down-Regulation / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects; D017353:Gene Deletion; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D010447:Peptide Hydrolases / Q000502:physiology; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D011518:Proto-Oncogene Proteins; D014452:Ubiquitins; D014443:Tyrosine; D016173:Macrophage Colony-Stimulating Factor; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D016186:Receptor, Macrophage Colony-Stimulating Factor; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D018631:ras Proteins; C493849:Cbl protein, mouse