PHOSPHATIDYLCHOLINE - A SOURCE OF DIGLYCERIDE MEDIATORS

我们最近发现磷脂酰胆碱是甘油二酯的新来源 (DG)调解员;拟议项目的长期目标是确定 这些种类的DG在正常和 肿瘤细胞拟议的调查将集中在具体的 以及调节降解胆碱的磷脂酶C 磷酸甘油酯（PC）和PC衍生的DG物种的作用， 第二信使。我们将鉴定出 DG通过这一途径形成，并决定了不同分子的能力 激活蛋白激酶C。在相关研究中，我们将 研究PC-特异性磷脂酶C在 细胞磷脂 该提案的具体目标是：1）确定 磷脂酶C用于PC的不同亚类和分子种类。的 许多细胞类型的PC组分含有烷基-PC和酰基-PC的混合物。 我们已经表明，PC的降解导致酰基-DG和 烷基-DG。将确定这些DG亚类的相对量 细胞刺激后。2)继续研究 磷脂酶C通过体外测定。这些研究将决定 底物特异性、辅因子需求和亚细胞定位 PC降解磷脂酶C。3)为了确定结构 DG激活或抑制蛋白激酶C的需要。我们有 表明烷基-DG是酰基-DG激活PKC的抑制剂。我们将 继续这些研究使用DG的分子物种观察后， 细胞刺激，分离PKC同工酶，检测 烷基-和酰基-DG上的每个同工酶。4)确定的作用 磷脂酶C在PC转化为乙醇胺磷酸甘油酯中的作用 （PE）。 在初步研究中，我们发现烷基PC可以转化为 烯基-PE通过以前未定义的途径;进一步的研究将 进行，以确定转换的途径，并调查的作用， 磷脂酶C 拟议实验的结合将进一步确定 PC衍生的DG在细胞调节中的作用。实验还将提供 进一步深入了解佛波醇二酯肿瘤的作用机制 启动子和细胞对生长因子的反应。预计 这些研究将有助于更好地了解PC的作用， 在增长控制中的转变。

We recently identified phosphatidylcholine as a novel source of diglyceride (DG) mediators; the long-term goal of the proposed project is to define the role of these species of DG in the stimulus-response coupling of normal and neoplastic cells. The proposed investigations will focus on the specificity and regulation of the phospholipase C that degrades choline phosphoglycerides (PC) and on the role of PC-derived DG species as intracellular second-messengers. We will identify the molecular species of DG formed by this pathway and determine the ability of different molecular species to activate protein kinase C. In related studies we will investigate the role of the PC-specific phospholipase C in the turnover of cellular phospholipids. The specific aims of this proposal are: 1) To determine the specificity of phospholipase C for different subclasses and molecular species of PC. The PC fraction of many cell types contains a mixture of alkyl-PC and acyl-PC. We have shown that degradation of PC results in a mixture of acyl-DG and alkyl-DG. The relative amounts of these subclasses of DG will be determined after cell stimulation. 2) To continue studies on the activity of phospholipase C by in vitro assay. These studies will determine the substrate specificity, cofactor requirements and subcellular localization of the PC degrading phospholipase C. 3) To determine the structural requirements for protein kinase C activation or inhibition by DG. We have shown that alkyl-DGs are inhibitors of PKC activation by, acyl-DG. We will continue these studies using the molecular species of DG observed after cell stimulation and separate the isozymes of PKC to test the effects of alkyl- and acyl-DG on each isoenzyme. 4) To determine the role of phospholipase C in the conversion of PC to ethanolamine phosphoglycerides (PE). In preliminary studies we found that alkyl-PC can be converted to alkenyl-PE by a previously undefined pathway; further studies will be performed to determine the pathway of-conversion and investigate the role of phospholipase C. The combination of the proposed experiments will further define the role of PC-derived DG in cellular regulation. The experiments will also provide further insight into the mechanism of action of phorbol diester tumor promoters and the cellular response to growth factors. It is anticipated that these studies will lead to a better understanding of the role of PC turnover in growth control.