Setty B N, Graeber J E, Stuart M J
Department of Pediatrics, State University of New York, Syracuse 13210.
J Biol Chem. 1987 Dec 25;262(36):17613-22.
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.
15-羟基二十碳四烯酸（15-HETE）是胎牛主动脉内皮细胞中花生四烯酸的主要脂氧合酶代谢产物，对这些细胞是一种促有丝分裂原，在有血清和血清饥饿的细胞中均能刺激细胞增殖和DNA合成。在[14C]花生四烯酸标记的汇合内皮细胞单层中，15-HETE（30微摩尔）导致[14C]二酰基甘油（DAG）升高，同时未刺激和刺激的细胞中细胞[14C]磷脂酰肌醇（PI）均减少。1-油酰基-2-乙酰甘油，一种合成的DAG类似物，以浓度依赖的方式刺激内皮细胞DNA合成。在[3H]肌醇标记的细胞中，15-HETE在基础和刺激条件下也导致细胞PI含量降低。然而，15-HETE对氯化锂处理的细胞中分离的磷脂酶C活性或磷酸肌醇周转率均无影响。在完整细胞中，15-HETE（30微摩尔）抑制[3H]肌醇合成[3H]PI（抑制率80%，p<0.001）。在人红细胞膜中，15-HETE以浓度依赖的方式抑制内源性DAG产生磷脂酸，IC50为41微摩尔。虽然12-HETE具有与15-HETE相似的作用，但母体化合物花生四烯酸不影响DNA合成或DAG激酶活性。因此，我们的研究表明，15-HETE和12-HETE对内皮细胞的促有丝分裂活性可能通过抑制DAG激酶并伴随细胞DAG积累来介导。
