G proteins coupled to phospholipase C: molecular targets of long-term ethanol exposure.
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.
Simonsson
P
P
Department of Psychiatry and Neurochemistry, Lund University, Sweden.
Rodriguez
F D
FD
Loman
N
N
Alling
C
C
D000535:Aluminum / Q000494:pharmacology; D000077410:Aluminum Chloride; D017607:Aluminum Compounds; D001920:Bradykinin / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006822:Hybrid Cells; D009423:Nervous System Neoplasms / Q000378:metabolism / Q000473:pathology; D010539:Permeability; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*
D017607:Aluminum Compounds; D002712:Chlorides; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000077410:Aluminum Chloride; D000431:Ethanol; D012969:Sodium Fluoride; D000535:Aluminum; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D001920:Bradykinin