title: Ligand-independent activation of c-kit receptor tyrosine kinase in a murine mastocytoma cell line P-815 generated by a point mutation.
abstract: The c-kit proto-oncogene encodes a receptor tyrosine kinase that is known to play a crucial role in hematopoiesis, especially in mast cell growth and differentiation. Although a number of dominant loss-of-function mutations of c-kit gene have been well characterized in mice, rats, and humans, little is known about the c-kit mutations contributing to ligand-independent activation of the c-kit receptor tyrosine kinase (KIT). In a murine mastocytoma cell line, P-815, KIT has been found to be constitutively phosphorylated on tyrosine and activated in a ligand-independent manner. Sequencing of the whole coding region of c-kit cDNA showed that c-kit cDNA of P-815 cells carries a point mutation in codon 814, resulting in amino acid substitution of Tyr for Asp. Murine wild-type c-kit cDNA and mutant-type c-kit cDNA encoding Tyr in codon 814 were expressed in cells of a human embryonic kidney cell line, 293T. In the transfected cells, mutant-form KITTyr814 was strikingly phosphorylated on tyrosine and activated in immune complex kinase reaction regardless of stimulation with a ligand for KIT (stem cell factor), whereas tyrosine phosphorylation and activation was barely detectable in wild-form KIT. The data presented here provide evidence for a novel activating mutation of c-kit gene that might be involved in neoplastic growth or oncogenesis of some cell types, including mast cells.
authors.affiliation: Department of Pathology, Osaka University Medical School, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsujimura
authors.forename: T
authors.initials: T
authors.lastname: Furitsu
authors.forename: M
authors.initials: M
authors.lastname: Morimoto
authors.forename: K
authors.initials: K
authors.lastname: Isozaki
authors.forename: S
authors.initials: S
authors.lastname: Nomura
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuzawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Y
authors.initials: Y
authors.lastname: Kanakura
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D018076:DNA, Complementary / Q000737:chemistry; D004789:Enzyme Activation; D012515:Mast-Cell Sarcoma / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D019000:Phosphotyrosine; D017354:Point Mutation; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D016184:Receptors, Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases