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Decreased myo ‐lnositol Uptake Is Associated with Reduced Bradykinin‐Stimulated Phosphatidylinositol Synthesis and Diacylglycerol Content in Cultured Neuroblastoma Cells Exposed to L‐Fucose
Author(s) -
Yorek Mark A.,
Dunlap Joyce A.,
Stefani Mark R.,
Davidson Eric P.,
Zhu Xi,
Eichberg Joseph
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.62010147.x
Subject(s) - phosphatidylinositol , diacylglycerol kinase , inositol , fucose , bradykinin , biochemistry , inositol phosphate , chemistry , biology , medicine , endocrinology , microbiology and biotechnology , protein kinase c , signal transduction , receptor , glycoprotein
L‐Fucose is a potent, competitive inhibitor of myo‐inositol transport by cultured mammalian cells. Chronic exposure of neuroblastoma cells to L‐fucose causes a concentration‐dependent decrease in myo‐inositol content, accumulation, and incorporation into phosphoinositides. In these studies, L‐fucose supplementation of culture medium was used to assess the effect of decreased myo‐inositol metabolism and content on bradykinin‐stimulated phosphatidylinositol synthesis and diacylglycerol production. Chronic exposure of cells to 30 m M L‐fucose caused a sustained decrease in bradykinin‐stimulated, but not basal, 3 H‐inositol phosphate release and 32 P incorporation into phosphatidylinositol in cells incubated in serum‐free, unsupplemented medium. In addition, 32 P incorporation into phosphatidylinositol 4‐phosphate and phosphatidylinositol 4, 5‐bisphosphate was not altered in L‐fucose‐conditioned cells. Acute exposure of cells to serum‐free medium containing 30 m M L‐fucose did not affect either basal or bradykinin‐stimulated 32 P incorporation into phosphatidylinositol. Basal diacylglycerol content was decreased by 20% in cells chronically exposed to 30 m M L‐fucose, although analysis of the molecular species profile revealed no compositional change. Bradykinin stimulated diacylglycerol production in neuroblastoma cells by increasing the hydrolysis of both phosphoinositides and phosphatidylcholine. Bradykinin‐stimulated production of total diacylglycerol was similar for control and L‐fucose‐conditioned cells. However, there was a decrease in the bradykinin‐induced generation of the 1 ‐stearoyl‐2‐arachidonoyl diacylglycerol molecular species in the cells chronically exposed to 30 m M L‐fucose. This molecular species accounts for about 70% of the composition of phosphoinositides, but only 10% of phosphatidylcholine. The results suggest that a decrease in myo‐inositol uptake results in diminished agonist‐induced phosphatidylinositol synthesis and phosphoinositide hydrolysis in cultured neuroblastoma cells grown in L‐fucose‐containing medium.