Balsinde J, Fernández B, Solís-Herruzo J A, Diez E
Centro de Investigación del Hospital Universitario Doce de Octubre, Madrid, Spain.
Biochim Biophys Acta. 1992 Jul 22;1136(1):75-82. doi: 10.1016/0167-4889(92)90087-r.
Resident peritoneal macrophages release arachidonic acid when challenged by zymosan, a phagocytosable particle. The present study was designed to investigate the pathways for arachidonic acid mobilization in zymosan-stimulated macrophages. Experiments were conducted with [3H]arachidonic acid-labeled macrophages to establish the relative contribution of acyltransferases, phospholipase A2, and diacylglycerol lipase to overall arachidonic acid release. Upon zymosan stimulation, [3H]arachidonic acid incorporation into phospholipids was significantly enhanced. Stimulus-induced activation of arachidonic acid incorporated was not observed immediately, but was found 5 min after cell challenge. On the other hand, the results indicated a rapid accumulation of intracellular free [3H]arachidonic acid that paralleled the appearance of both [3H]glycerol-labeled lysophosphatidylcholine and [3H]glycerol-labeled lysophosphatidylinositol, the by-products of phospholipase A2 action on phosphatidylcholine and phosphatidylinositol, respectively. A transient accumulation of [3H]arachidonate-carrying diacylglycerol was also observed. However, no appreciable alterations in the levels of [3H]monoacylglycerol were found. The phospholipase A2 inhibitor nordihydroguaiaretic acid substantially prevented the zymosan-induced arachidonic acid release. In contrast, RHC 80267, a diacylglycerol lipase inhibitor, though preventing diacylglycerol breakdown, did not have any effect on [3H]arachidonic acid release From these results, it is concluded that: (1) the phospholipase A2 pathway controls arachidonic acid release upon zymosan stimulation; (2) the diacylglycerol lipase pathway appears not to be involved in arachidonic acid release by stimulated cells; (3) the acyltransferases play a remarkable role in controlling free arachidonic acid levels, but they do not participate in the increase of free fatty acid levels observed upon cell stimulation.
当受到可吞噬颗粒酵母聚糖的刺激时，驻留腹膜巨噬细胞会释放花生四烯酸。本研究旨在探究酵母聚糖刺激的巨噬细胞中花生四烯酸动员的途径。实验使用[3H]花生四烯酸标记的巨噬细胞来确定酰基转移酶、磷脂酶A2和二酰甘油脂肪酶对总体花生四烯酸释放的相对贡献。在酵母聚糖刺激后，[3H]花生四烯酸掺入磷脂的量显著增加。刺激诱导的花生四烯酸掺入激活并非立即观察到，而是在细胞受到刺激5分钟后才发现。另一方面，结果表明细胞内游离[3H]花生四烯酸迅速积累，这与[3H]甘油标记的溶血磷脂酰胆碱和[3H]甘油标记的溶血磷脂酰肌醇的出现平行，它们分别是磷脂酶A2作用于磷脂酰胆碱和磷脂酰肌醇的副产物。还观察到携带[3H]花生四烯酸的二酰甘油有短暂积累。然而，未发现[3H]单酰甘油水平有明显变化。磷脂酶A2抑制剂去甲二氢愈创木酸基本上阻止了酵母聚糖诱导的花生四烯酸释放。相比之下，二酰甘油脂肪酶抑制剂RHC 80267虽然阻止了二酰甘油的分解，但对[3H]花生四烯酸的释放没有任何影响。从这些结果可以得出结论：（1）磷脂酶A2途径控制酵母聚糖刺激时的花生四烯酸释放；（2）二酰甘油脂肪酶途径似乎不参与受刺激细胞的花生四烯酸释放；（3）酰基转移酶在控制游离花生四烯酸水平方面发挥显著作用，但它们不参与细胞刺激时观察到的游离脂肪酸水平的增加。
