G Proteins Coupled to Phospholipase C: Molecular Targets of Long-Term Ethanol Exposure |
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Authors: | Per Simonsson F David Rodriguez Niklas Loman Christer Alling |
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Institution: | Department of Psychiatry and Neurochemistry, Lund University, Sweden. |
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Abstract: | Long-term ethanol exposure is known to inhibit bradykinin-stimulated phosphoinositide hydrolysis in cultures of neuroblastoma x glioma 108-15 cells. In the present study, 3H]bradykinin binding, GTP-binding protein function, and phospholipase C activity were assayed in cells grown for 4 days in 100 mM ethanol with the aim of elucidating the molecular target of ethanol on signal transduction coupled to inositol trisphosphate and diacylglycerol formation. Ethanol exposure reduced guanosine 5'-O-(3-thiotriphosphate) GTP(S)]- and, to a lesser extent, NaF/AlCl3-stimulated phosphoinositide hydrolysis, whereas it had no effect on the enzymatic activity of a phosphatidylinositol 4,5-bisphosphate-specific phospholipase C. 3H]Bradykinin binding in the absence of GTP(S) was not influenced by ethanol exposure. However, the reduction in 3H]bradykinin binding seen in control cells after addition of GTP analogue was inhibited in cells grown in ethanol-containing medium. The results indicate that long-term ethanol exposure exerts its effects on receptor-stimulated phosphoinositide hydrolysis primarily at the level of the GTP-binding protein. |
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Keywords: | Ethanol Bradykinin Phosphatidylinositol 4 5-bisphosphate Phospholipase C GTP-binding protein NG 108–15 cell line |
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