Differences in signaling pathways and expression level of the phosphoinositide phosphatase SHIP1 between two oncogenic mutants of the receptor tyrosine kinase KIT.
Oncogenic mutations of the receptor tyrosine kinase KIT are encountered in myeloid leukemia and various solid tumors, including gastrointestinal stromal tumors. We previously identified the human oncogenic germ line mutant KIT(K642E), a substitution in the tyrosine kinase 1 domain (TK1D) in a familial form of gastrointestinal stromal tumors. The effects of oncogenic KIT mutants on cell signaling and regulation are complex. Cellular models are valuable basic tools to tailor novel strategies on specific cellular and molecular bases for tumors expressing KIT oncogenic mutants. Murine KIT(WT) and the murine homologues of human KIT oncogenic mutants, further referred to as KIT(K641E) and KIT(del559), a point deletion in the juxtamembrane domain (JMD), were stably expressed in IL-3-dependent Ba/F3 cells. Major differences in the constitutively activation of Akt/PKB, MAP kinases and STATs pathways were observed between KIT(K641E) and KIT(del559), whereas KIT ligand elicited responses in both mutants. Noteworthy, the protein level of the phosphoinositide phosphatase SHIP1, but not SHIP2 and PTEN, was reduced in KIT(K641E) only while inhibition of KIT phosphorylation reversibly raised SHIP1 level in both JMD and TK1D oncogenic mutants, unraveling the control of SHIP protein level by KIT phosphorylation.
Laboratoire de Neurophysiologie, Faculté de Médecine, Campus Erasme, CP 601, Université Libre de Bruxelles, 808 route de Lennik, B-1070 Brussels, Belgium. jmvdwin@ulb.ac.be
J M
JM
Vanderwinden
D
D
Wang
N
N
Paternotte
S
S
Mignon
K
K
Isozaki
C
C
Erneux
D000818:Animals; D002460:Cell Line; D006801:Humans; D000072181:Inositol Polyphosphate 5-Phosphatases; D051379:Mice; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*
D019009:Proto-Oncogene Proteins c-kit; D051057:Proto-Oncogene Proteins c-akt; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C000606430:INPP5D protein, human; C000606433:Inpp5d protein, mouse; C000606435:Inppl1 protein, mouse; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases