Cao Y Z, Reddy P V, Sordillo L M, Hildenbrandt G R, Reddy C C
Environmental Resources Research Institute, Pennsylvania State University, University Park 16802, USA.
Biochem Biophys Res Commun. 1996 Dec 13;229(2):630-4. doi: 10.1006/bbrc.1996.1855.
Previously we reported that tumor-promoting phorbol esters stimulate phospholipase D (PLD) independent of protein kinase C (PKC) activation in bovine lymph node lymphocytes. (Cao et al., Biochem. Biophys. Res. Commun. 171, 955-962, 1990; 217, 908-915, 1995). In the present study, we examined the effects of prostagladins (PGs), E2, F2 alpha, D2, and H2 on PLD activity as measured by conversion of [1-14C] arachidonic acid-labeled phospholipids into phosphatidylethanol (PEt) in bovine lymph node lymphocytes. Prostaglandins stimulated the formation of PEt at an optimal concentration of 10 microM with relative stimulatory effect on the order of PGE2 > PGF2 alpha > PGH2 > PGD2. The PGE2-stimulated formation of PEt was dose-dependent in the range of 0.1 to 10 microM and was not inhibited by PKC inhibitors staurosporine and K252a. When both PGE2 and 12-0-tetradecanoylphorbol-13-acetate (TPA) were included, their effect on the PLD activation was additive. Furthermore, NaF, a G-protein activator, stimulated the PEt formation. Interestingly, the stimulatory effects of PGE2 and NaF were not additive; however, the formation of PEt by NaF and TPA was additive. These results suggest that similar to TPA, PGs increase PLD activity independent of PKC and the stimulation by PGs and TPA in lymphocytes may involve both G-protein-dependent and G-protein-independent signaling pathways.
此前我们报道，促肿瘤佛波酯可在不依赖蛋白激酶C（PKC）激活的情况下刺激牛淋巴结淋巴细胞中的磷脂酶D（PLD）（曹等人，《生物化学与生物物理研究通讯》，171卷，955 - 962页，1990年；217卷，908 - 915页，1995年）。在本研究中，我们检测了前列腺素（PGs）E2、F2α、D2和H2对PLD活性的影响，通过测量牛淋巴结淋巴细胞中[1 - 14C]花生四烯酸标记的磷脂转化为磷脂酰乙醇（PEt）来评估。前列腺素在最佳浓度10微摩尔时刺激了PEt的形成，对其相对刺激作用的顺序为PGE2 > PGF2α > PGH2 > PGD2。PGE2刺激的PEt形成在0.1至10微摩尔范围内呈剂量依赖性，且不受PKC抑制剂星形孢菌素和K252a的抑制。当同时加入PGE2和12 - 0 - 十四酰佛波醇 - 13 - 乙酸酯（TPA）时，它们对PLD激活的作用是相加的。此外，G蛋白激活剂氟化钠（NaF）刺激了PEt的形成。有趣的是，PGE2和NaF的刺激作用不是相加的；然而，NaF和TPA对PEt的形成作用是相加的。这些结果表明，与TPA类似，PGs可在不依赖PKC情况下增加PLD活性，并且PGs和TPA在淋巴细胞中的刺激作用可能涉及G蛋白依赖性和G蛋白非依赖性信号通路。
