Regulation of the Src homology 2-containing inositol 5-phosphatase SHIP1 in HIP1/PDGFbeta R-transformed cells.
It has been shown previously that the Huntingtin interacting protein 1 gene (HIP1) was fused to the platelet-derived growth factor beta receptor gene (PDGFbetaR) in leukemic cells of a patient with chronic myelomonocytic leukemia. This resulted in the expression of the chimeric HIP1/PDGFbetaR protein, which oligomerizes, is constitutively tyrosine-phosphorylated, and transforms the Ba/F3 murine hematopoietic cell line to interleukin-3-independent growth. Tyrosine phosphorylation of a 130-kDa protein (p130) correlates with transformation by HIP1/PDGFbetaR and related transforming mutants. We report here that the p130 band is immunologically related to the 125-kDa isoform of the Src homology 2-containing inositol 5-phosphatase, SHIP1. We have found that SHIP1 associates and colocalizes with the HIP1/PDGFbetaR fusion protein and related transforming mutants. These mutants include a mutant that has eight Src homology 2-binding phosphotyrosines mutated to phenylalanine. In contrast, SHIP1 does not associate with H/P(KI), the kinase-dead form of HIP1/PDGFbetaR. We also report that phosphorylation of SHIP1 by HIP1/PDGFbetaR does not change its 5-phosphatase-specific activity. This suggests that phosphorylation and possible PDGFbetaR-mediated sequestration of SHIP1 from its substrates (PtdIns(3,4,5)P(3) and Ins(1,3,4,5)P(4)) might alter the levels of these inositol-containing signal transduction molecules, resulting in activation of downstream effectors of cellular proliferation and/or survival.
Saint-Dic
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Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
Chang
S C
SC
Taylor
G S
GS
Provot
M M
MM
Ross
T S
TS
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D002461:Cell Line, Transformed; D004268:DNA-Binding Proteins; D006801:Humans; D006816:Huntington Disease / Q000235:genetics; D007668:Kidney; D007700:Kinetics; D008970:Molecular Weight; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D019000:Phosphotyrosine / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D014162:Transfection; D018909:src Homology Domains
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C073368:HIP1 protein, human; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D019000:Phosphotyrosine; D020797:Receptor, Platelet-Derived Growth Factor beta; D010744:Phosphoric Monoester Hydrolases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases