Mammalian cells that express Bacillus cereus phosphatidylinositol-specific phospholipase C have increased levels of inositol cyclic 1:2-phosphate, inositol 1-phosphate, and inositol 2-phosphate.
Phosphatidylinositol-specific phospholipase C (PtdIns-PLC) of Bacillus cereus catalyzes the conversion of PtdIns to inositol cyclic 1:2-phosphate and diacylglycerol. NIH 3T3, Swiss mouse 3T3, CV-1, and Cos-7 cells were transfected with a cDNA encoding this enzyme, and the metabolic and cellular consequences were investigated. Overexpression of PtdIns-PLC enzyme activity was associated with elevated levels of inositol cyclic 1:2-phosphate (2.5-70-fold), inositol 1-phosphate (2-20-fold), and inositol 2-phosphate (3-20-fold). The increases correlated with the levels of enzyme expression obtained in each cell type. The turnover of phosphatidylinositol (PtdIns) was also increased in transfected CV-1 cells by 13-fold 20 h after transfection. The levels of PtdIns, phosphatidic acid, diacylglycerol, or other inositol phosphates were not detectably altered. Expression of bacterial PtdIns-PLC decreased rapidly after 20 h implying that either the increased PtdIns turnover or the accumulation of inositol phosphates was detrimental to cells and that by some adaptive mechanism enzyme expression was suppressed.
Ross
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Division of Hematology/Oncology, Washington University, St. Louis, Missouri 63110-1093.
Wang
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Majerus
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D016475:3T3 Cells; D000818:Animals; D001409:Bacillus cereus / Q000201:enzymology*; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004247:DNA; D007295:Inositol Phosphates / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010716:Phosphatidylinositols / Q000378:metabolism; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000235:genetics*; D014162:Transfection
D007295:Inositol Phosphates; D009841:Oligonucleotides; D010716:Phosphatidylinositols; C002647:inositol 1-phosphate; C010199:inositol cyclic phosphate; C047872:inositol 2-monophosphate; D004247:DNA; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase