Mechanism of down-regulation of c-kit receptor. Roles of receptor tyrosine kinase, phosphatidylinositol 3'-kinase, and protein kinase C.
The receptor tyrosine kinase Kit and Kit ligand (KL), encoded at the murine white spotting (W) and steel (Sl) loci, respectively, function in hematopoiesis, melanogenesis, and gametogenesis. To understand the mechanism of turnover of Kit in mast cells, mutant receptors generated in vitro were heterologously expressed in Wsb/Wsh mast cells lacking endogenous c-kit expression, and the effects of mutations on KL-induced internalization and ubiquitination/degradation of Kit were studied. Upon binding of KL, KL.Kit receptor complexes were rapidly internalized, and the turnover was accelerated by ubiquitin-mediated degradation. Inactivation of the Kit kinase resulted in a reduced rate of internalization of KL.Kit complexes, degradation of kinase-inactive receptor complexes was relatively slow, and receptor ubiquitination was absent. But abolishment of KL-induced receptor association and activation of phosphatidylinositol 3'-kinase and of tyrosine 821 autophosphorylation did not affect KL-induced internalization and ubiquitination/degradation of Kit. Furthermore, Kit receptors can be down-regulated by proteolytic cleavage induced by either activation of protein kinase C or by isopropyl alcohol. In summary, KL-induced internalization of KL.Kit complexes and ubiquitination/degradation require an active kinase. By contrast, proteolytic cleavage of Kit mediated by protein kinase C activation is independent of kinase activity.
Yee
N S
NS
Molecular Biology Program, Sloan-Kettering Institute, New York, New York 10021.
Hsiau
C W
CW
Serve
H
H
Vosseller
K
K
Besmer
P
P
D000818:Animals; D004252:DNA Mutational Analysis; D015536:Down-Regulation; D010450:Endopeptidases / Q000378:metabolism; D016298:Hematopoietic Cell Growth Factors / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D019000:Phosphotyrosine; D011493:Protein Kinase C / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D016184:Receptors, Colony-Stimulating Factor / Q000378:metabolism*; D019089:Stem Cell Factor; D013329:Structure-Activity Relationship; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism
D016298:Hematopoietic Cell Growth Factors; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019089:Stem Cell Factor; D014452:Ubiquitins; D019000:Phosphotyrosine; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010450:Endopeptidases; D013755:Tetradecanoylphorbol Acetate