PHOSPHATIDYLCHOLINE--SOURCE OF DIGLYCERIDE MEDIATORS

我们最近发现磷脂酰胆碱是一种新的甘油三酯来源 (D)调解人；拟议项目的长期目标是界定 这些DG在正常和非DG刺激-反应偶联中的作用 肿瘤细胞。拟议的调查将集中在特殊性上。 以及对降解胆碱的磷脂酶C的调节 磷酸甘油酯(PC)及其衍生的DG物种作为 细胞内的第二信使。我们将鉴定其分子种类 DG由这一途径形成，并决定不同分子的能力 在相关研究中，我们将 探讨磷脂酶C在磷脂酶C周转中的作用 细胞磷脂。 这项提案的具体目的是：1)确定 不同亚类和不同分子种类的磷脂酶C。这个 许多细胞类型的PC组分含有烷基-PC和酰基-PC的混合物。 我们已经证明，PC的降解会导致酰基-DG和 烷基-DG。这些DG亚类的相对数量将被确定 在细胞刺激后。2)继续研究其活性 磷脂酶C的体外测定。这些研究将确定 底物专一性、辅因子要求和亚细胞定位 PC降解磷脂酶C.3)以确定其结构 DG激活或抑制蛋白激酶C的要求。我们有 结果表明，烷基-DG是酰基-DG激活PKC的抑制剂。我们会 使用观察到的DG的分子物种继续这些研究 细胞刺激并分离PKC同工酶以检测其作用 每个同工酶上都有烷基和酰基-DG。4)确定 磷脂酶C在PC转化为乙醇胺磷酸甘油中的作用 (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；将进行进一步的研究 以确定-转换的途径并研究其作用 磷脂酶C. 拟议中的实验组合将进一步定义 PC衍生DG在细胞调节中的作用。这些实验还将提供 佛波二酯肿瘤作用机制的进一步研究 启动子和细胞对生长因子的反应。这是意料之中的 这些研究将使人们更好地理解个人计算机的作用 在增长控制方面的营业额。

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.