Phosphatidylinositol 3,4,5-trisphosphate modulation in SHIP2-deficient mouse embryonic fibroblasts.
SHIP2, the ubiquitous SH2 domain containing inositol 5-phosphatase, includes a series of protein interacting domains and has the ability to dephosphorylate phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P(3)]in vitro. The present study, which was undertaken to evaluate the impact of SHIP2 on PtdIns(3,4,5)P(3) levels, was performed in a mouse embryonic fibroblast (MEF) model using SHIP2 deficient (-/-) MEF cells derived from knockout mice. PtdIns(3,4,5)P(3) was upregulated in serum stimulated -/- MEF cells as compared to +/+ MEF cells. Although the absence of SHIP2 had no effect on basal PtdIns(3,4,5)P(3) levels, we show here that this lipid was significantly upregulated in SHIP2 -/- cells but only after short-term (i.e. 5-10 min) incubation with serum. The difference in PtdIns(3,4,5)P(3) levels in heterozygous fibroblast cells was intermediate between the +/+ and the -/- cells. In our model, insulin-like growth factor-1 stimulation did not show this upregulation. Serum stimulated phosphoinositide 3-kinase (PI 3-kinase) activity appeared to be comparable between +/+ and -/- cells. Moreover, protein kinase B, but not mitogen activated protein kinase activity, was also potentiated in SHIP2 deficient cells stimulated by serum. The upregulation of protein kinase B activity in serum stimulated cells was totally reversed in the presence of the PI 3-kinase inhibitor LY-294002, in both +/+ and -/- cells. Altogether, these data establish a link between SHIP2 and the acute control of PtdIns(3,4,5)P(3) levels in intact cells.
Blero
Daniel
D
Interdisciplinary Research Institute (IRIBHM), Université Libre de Bruxelles, Belgium.
Zhang
Jing
J
Pesesse
Xavier
X
Payrastre
Bernard
B
Dumont
Jacques E
JE
Schurmans
Stéphane
S
Erneux
Christophe
C
D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology*; D006133:Growth Substances / Q000378:metabolism; D000072181:Inositol Polyphosphate 5-Phosphatases; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
D003470:Culture Media; D006133:Growth Substances; D018129:Phosphatidylinositol Phosphates; D025521:Tumor Suppressor Proteins; C060974:phosphatidylinositol 3,4,5-triphosphate; D019869:Phosphatidylinositol 3-Kinases; D017526:Receptor, IGF Type 1; D010744:Phosphoric Monoester Hydrolases; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D000072181:Inositol Polyphosphate 5-Phosphatases; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse; C000606435:Inppl1 protein, mouse; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases