c-kit ligand stimulates tyrosine phosphorylation of the c-Cbl protein in human hematopoietic cells.
c-kit ligand (KL) is a hematopoietic growth factor that plays a major role in the survival, expansion and differentiation of hematopoietic progenitor cells of various lineages. The biological actions elicited by KL are initiated by binding to its cognate receptor, c-kit, which is a transmembrane tyrosine kinase. The resulting ligand/receptor complex rapidly activates the intrinsic kit receptor tyrosine kinase and subsequent phosphorylation of specific intracellular substrates that are involved in downstream signaling events. In the present studies, we demonstrate that KL stimulates the rapid tyrosine phosphorylation of the proto-oncogene, c-Cbl, in two KL-responsive human hematopoietic cell lines, MO7e and TF-1. In both these cell lines we found a constitutive in vivo association between c-Cbl and the adaptor protein Grb2 and demonstrate (in vitro) that c-Cbl binds primarily to the N-terminal SH3 domain of Grb2. Furthermore, the stoichiometry of this association was not significantly affected upon c-kit receptor activation. We also provide evidence that c-Cbl is not stably associated with the kit receptor either prior to or following KL stimulation. Our findings suggest that c-Cbl is an important component in the KL signaling pathway in human hematopoietic progenitor cells.
Wisniewski
D
D
Sloan-Kettering Institute for Cancer Research, Molecular Pharmacology and Therapeutics Program, New York, NY, USA.
Strife
A
A
Clarkson
B
B
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007947:Leukemia, Megakaryoblastic, Acute; D015470:Leukemia, Myeloid, Acute; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D019089:Stem Cell Factor / Q000378:metabolism / Q000494:pharmacology*; D013268:Stimulation, Chemical; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D018909:src Homology Domains / Q000502:physiology
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D014443:Tyrosine; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D019009:Proto-Oncogene Proteins c-kit; C067419:CBL protein, human