Pessin M S, Raben D M
Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Biol Chem. 1989 May 25;264(15):8729-38.
Diglycerides derived from the phospholipase C-mediated hydrolysis of phosphoinositides are implicated as important mediators of agonist-induced responses, including the stimulation of cell division. alpha-Thrombin-stimulated proliferation of fibroblasts is associated with a sustained increase in cellular diglycerides, while the hydrolysis of phosphoinositides is transient (Wright, T. M., Rangan, L. A., Shin, H. S., and Raben, D. M. (1988) J. Biol. Chem. 263, 9374-9380). A rigorous assessment of this apparent discrepancy requires an analysis of the molecular species of the lipids involved. In this report, we have analyzed the molecular species of 1,2-diglycerides present in quiescent and alpha-thrombin-stimulated IIC9 Chinese hamster embryo fibroblasts. The molecular species profiles of the stimulated diglycerides were compared to the profiles of molecular species contained in cellular phospholipids. We demonstrate that 1) stimulation of IIC9 cells by alpha-thrombin results in an increase in the levels of diglyceride molecular species already present in control, quiescent cultures, without the addition of new species or the complete loss of existing species; 2) the diglycerides present in control cultures as well as in cultures stimulated with alpha-thrombin are all ester-linked; and 3) while the phosphoinositides contribute a significant proportion of the diglycerides generated 15 s following alpha-thrombin addition, phosphatidylcholine contributes most of the diglycerides generated after 5 min and 1 h.
由磷脂酶C介导的磷酸肌醇水解产生的甘油二酯被认为是激动剂诱导反应的重要介质，包括刺激细胞分裂。α-凝血酶刺激的成纤维细胞增殖与细胞内甘油二酯的持续增加有关，而磷酸肌醇的水解是短暂的（Wright, T. M., Rangan, L. A., Shin, H. S., and Raben, D. M. (1988) J. Biol. Chem. 263, 9374 - 9380）。要对这一明显差异进行严格评估，需要分析所涉及脂质的分子种类。在本报告中，我们分析了静止的和α-凝血酶刺激的IIC9中国仓鼠胚胎成纤维细胞中存在的1,2 - 甘油二酯的分子种类。将刺激后的甘油二酯的分子种类谱与细胞磷脂中所含分子种类的谱进行了比较。我们证明：1）α-凝血酶对IIC9细胞的刺激导致对照静止培养物中已存在的甘油二酯分子种类水平增加，既没有添加新的种类，也没有现有种类的完全丧失；2）对照培养物以及用α-凝血酶刺激的培养物中存在的甘油二酯都是酯键连接的；3）虽然磷酸肌醇在添加α-凝血酶后15秒产生的甘油二酯中占很大比例，但磷脂酰胆碱在5分钟和1小时后产生的甘油二酯中占大部分。
