Sodium fluoride induces phosphoinositide hydrolysis, Ca2+ mobilization, and prostacyclin synthesis in cultured human endothelium: further evidence for regulation by a pertussis toxin-insensitive guanine nucleotide-binding protein.
The role of guanine nucleotide-binding proteins in the induction of prostacyclin synthesis by stimulated endothelial cells is incompletely understood. We report that sodium fluoride (NaF), a potent activator of cellular guanine nucleotide-binding proteins, affected time- and concentration-dependent generation of prostacyclin (PGI2) by cultured human umbilical vein endothelial cells without evidence of cellular toxicity detected by 51Cr or lactate dehydrogenase release. PGI2 synthesis by NaF-stimulated endothelial cells was associated with increases in arachidonate release, phosphoinositide hydrolysis, generation of inositol phosphates, and accumulation of diacylglycerol. These responses to NaF, as well as alpha-thrombin-mediated responses, were not dependent upon the availability of extracellular free Ca2+ but were associated with the mobilization of stored intracellular Ca2+ detected by the luminescence of the photoprotein aequorin. Neither PGI2 synthesis nor Ca2+ responses following alpha-thrombin or NaF stimulation were inhibited by pretreatment of cells with the islet activating protein from Bordetella pertussis but were significantly attenuated by the G protein inhibitor GDP beta S in permeabilized cells. Our results are compatible with a model wherein NaF directly activates a phosphoinositidase-linked guanine nucleotide regulatory protein, Gp, in human umbilical vein endothelial cell monolayers. This activation results in phosphoinositide hydrolysis, Ca2+ mobilization, arachidonate release, and subsequent functional activation, assessed by PGI2 release. Biologically relevant agonists such as alpha-thrombin may exert their influence on arachidonate metabolism, in part, by promoting receptor-dependent activation of this G protein.
Garcia
J G
JG
Department of Medicine, Indiana University School of Medicine, Indianapolis 46202.
Dominguez
J
J
English
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D
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004075:Diglycerides / Q000378:metabolism; D004730:Endothelium, Vascular / Q000502:physiology*; D011464:Epoprostenol / Q000096:biosynthesis*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism; D015398:Signal Transduction; D012969:Sodium Fluoride / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology; D013997:Time Factors; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D001095:Arachidonic Acids; D004075:Diglycerides; D007295:Inositol Phosphates; D010716:Phosphatidylinositols; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D016718:Arachidonic Acid; D012969:Sodium Fluoride; D011464:Epoprostenol; D037342:Pertussis Toxin; D013917:Thrombin; D019204:GTP-Binding Proteins; D002118:Calcium