15-hydroxy-5-8-11-13-eicosatetraenoic-acid and 1-oleoyl-2-acetylglycerol

Modulation of renin synthesis by lipoxygenase products has been studied in cultured human mesangial cells under basal conditions and in the presence of prostaglandin (PG) E2. Total renin and cyclic AMP productions were stimulated in a dose-dependent manner (0.1-10 microM) by PGE2. The stimulatory effect of PGE2 on renin production was inhibited by 12-hydroxyeicosatetraenoic acid (12-HETE) between 0.1 and 100 nM. Extracellular and intracellular renin were affected similarly. Neither basal and PGE2-dependent cyclic AMP nor basal cyclic GMP productions were modified. 15-Hydroxyeicosatetraenoic acid (15-HPETE), 12-hydroperoxyeicosatetraenoic acid (12-HPETE) and 15-hydroperoxyeicosatetraenoic acid (15-HPETE) had the same effects as 12-HETE. Intracellular calcium concentration was not modified in the presence of 12-HETE. Since oleyl-2-acetylglycerol (OAG), an analog of diacylglycerol, also inhibited PGE2-stimulated renin production, it is hypothesized that the effect of the lipoxygenase products is mediated via protein kinase C stimulation.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Angiotensin II; Calcium; Cyclic AMP; Cyclic GMP; Diglycerides; Dinoprostone; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Kidney Cortex; Leukotrienes; Lipid Peroxides; Lipoxygenase; Renin

15-Hydroxyeicosatetraenoic acid (15-HETE), a major lipoxygenase metabolite of arachidonic acid in fetal bovine aortic endothelial cells, was a mitogen for these cells, stimulating both cell proliferation and DNA synthesis in the presence of serum and serum-deprived cells. In [14C]arachidonic acid-labeled confluent endothelial cell monolayers, 15-HETE (30 microM) caused an elevation of [14C]diacylglycerol (DAG) with a concomitant decrease in cellular [14C]phosphatidylinositol (PI) in both unstimulated and stimulated cells. 1-Oleoyl-2-acetylglycerol, a synthetic DAG analog, stimulated endothelial cell DNA synthesis in a concentration-dependent manner. In [3H]inositol-labeled cells, 15-HETE also caused a decrease in cellular PI content under both basal and stimulated conditions. 15-HETE, however, had no effect on either isolated phospholipase C activity or phosphoinositide turnover in lithium chloride-treated cells. In intact cells, 15-HETE (30 microM) inhibited the synthesis of [3H]PI from [3H]inositol (80% inhibition, p less than 0.001). In human red cell membranes, the production of phosphatidic acid from endogenous DAG was inhibited by 15-HETE in a concentration-dependent manner with an IC50 of 41 microM. Although 12-HETE had effects similar to those of 15-HETE, the parent compound arachidonic acid did not affect DNA synthesis or DAG kinase activity. Our study thus demonstrates that the mitogenic activity of 15- and 12-HETE on endothelial cells may be mediated via DAG kinase inhibition with the concomitant accumulation of cellular DAG.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; 5,8,11,14-Eicosatetraynoic Acid; Animals; Arachidonic Acid; Arachidonic Acids; Cattle; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Diacylglycerol Kinase; Diglycerides; Dose-Response Relationship, Drug; Endothelium, Vascular; Hydroxyeicosatetraenoic Acids; Indomethacin; Mitosis; Phosphotransferases; Thymidine