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GLYCEROLIPIDS AND PROSTAGLANDIN BIOSYNTHESIS

甘油脂和前列腺素生物合成

基本信息

批准号：
6384450
负责人：
ATA A ABDEL-LATIF
金额：
$ 20.52万
依托单位：
AUGUSTA UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1981
资助国家：
美国
起止时间：
1981-12-01 至 2003-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (Investigator's Abstract): The long-term goal of this research is to elucidate the regulatory mechanisms involved in arachidonic acid (AA) liberation and eicosanoid biosynthesis in the iris-ciliary body (ICB) and other ocular tissues. The central hypothesis to be tested is that phospholipase A2 (PLA2) activation is a major source for AA release in the ICB. This represents a logical pursuit of the findings obtained during the current budget period. ICB is the major source of eicosanoid synthesis in the eye. The investigators and others have reported that activation of the ICB with various agonists, including carbachol, PGE2alpha, substance P, endothelin-1, and PAF results in the rapid hydrolysis of polyphosphoinositides into IP3 and DAG, the two second messengers, and the concomitant liberation from membrane phospholipids of AA for eicosanoid biosynthesis. The investigators have found that the generation of these phospholipid-derived second messengers and the formation of cAMP and their physiological consequences to be species dependent. While the involvement of phospholipases (A2,C,D) in AA release has been documented in several tissues, including ICB, the precise mechanism underlying the stimulated release of this polyunsaturated fatty acid remains undefined. This is also true of the phospholipid source of AA. There is strong evidence from the investigators own laboratory on the ICB and from other investigators working with different tissues that PLA2, which acts on phospholipids to liberate AA and lysophospholipid, plays a central role in the control of AA required for eicosanoid biosynthesis. Based on these findings the investigators now propose to address the following specific aims: (1) Investigate the AA content of the major membrane phospholipids, phospholipases (A2,C,D) activities, and the effects of various agonists on AA release and eicosanoid biosynthesis in ICB and trabecular meshwork of different mammalian species. (2) Investigate the mechanisms involved in agonist-induced AA release and phospholipid source of AA in the iris sphincter, and AA release from phospholipids in membranes isolated from iris sphincters. Endogenous release of AA will be monitored with GLC. (3) Investigate the regulatory role of protein kinase C in AA release and PG synthesis in the iris sphincter. Both PKC inhibitors and down-regulation of PKC with PDBu will be employed. (4) Purify and characterize phospholipase(s) A2 from rabbit ICB. Activators and inhibitors of PLA2 will be employed. An attempt will be made to reconstitute the purified PLA2 with G-proteins. (5) Investigate the mechanism of the effects of in vitro and in vivo PG receptor desensitization on basal and on agonist-induced AA release and PG synthesis, IP3 production, cAMP formation, and on contraction in the iris sphincter. The proposed studies will yield important basic information about the physiological regulation of AA release from membrane phospholipids, the link between receptor activation and AA release, the profile of PGs produced in response to each agonist, the mechanism of PG receptor desensitization and its cross desensitization of other receptors, and the role of phospholipases (A2,C,D) in stimulus- dependent release of AA in ocular tissues. Understanding the biochemical basis for the regulation of AA liberation and PG synthesis will make their pharmacological manipulation more plausible, and will lead to the development of more effective anti-glaucoma and anti-inflammatory drugs.

描述（研究者摘要）：本研究的长期目标阐明花生四烯酸（AA）的调控机制虹膜睫状体（ICB）中的类二十烷酸释放和生物合成，其他眼组织。有待检验的中心假设是，磷脂酶A2（PLA 2）激活是AA释放的主要来源。 ICB。这代表了对调查期间获得的调查结果的合乎逻辑的追求。本预算期。 ICB是类花生酸合成的主要来源， the eye. 调查人员和其他人报告说， ICB与各种激动剂，包括卡巴胆碱，PGE 2 α，P物质，内皮素-1和PAF导致将多磷酸肌醇转化为IP 3和DAG，这两个第二信使，类花生酸AA从膜磷脂中的伴随释放生物合成研究人员发现，这些基因的产生磷脂衍生的第二信使和cAMP的形成及其生理后果取决于物种。虽然参与磷脂酶（A2，C，D）在AA释放中的作用已经在几个文献中被证明。组织，包括ICB，刺激的确切机制这种多不饱和脂肪酸的释放仍然不确定。这也是 AA的磷脂来源。有强有力的证据表明，研究者在ICB上拥有实验室，并从其他研究者处获得 PLA 2作用于不同的组织，作用于磷脂，释放AA和溶血磷脂，在AA的控制中起核心作用类花生酸生物合成所必需的。根据这些发现，研究人员现在提出了以下具体目标：（1）研究主要膜磷脂的AA含量，磷脂酶（A2，C，D）的活性，以及各种激动剂对白内障患者ICB和小梁网中AA释放和类花生酸生物合成不同的哺乳动物物种。 (2)调查涉及的机制激动剂诱导的虹膜中AA释放和AA的磷脂来源括约肌，和AA释放的磷脂在膜分离，虹膜括约肌将使用GLC监测AA的内源性释放。（三）研究蛋白激酶C在AA释放和PG中的调节作用虹膜括约肌的合成 PKC抑制剂和下调将使用PKC与PDBu的组合。 (4)纯化和表征来自兔ICB的磷脂酶A2。 PLA 2的激活剂和抑制剂将被雇用。将尝试重构纯化的PLA 2 G蛋白。 (5)探讨其作用机制和体内PG受体对基础和激动剂诱导的AA脱敏释放和PG合成、IP 3产生、cAMP形成等虹膜括约肌收缩拟议的研究将产生关于AA生理调节的重要基础信息从膜释放磷脂，受体激活之间的联系和AA释放，响应于每种激动剂产生的PG的分布， PG受体脱敏及其交叉脱敏机制其他受体的作用，以及磷脂酶（A2，C，D）在刺激- 眼组织中AA的依赖性释放。了解生物化学调节AA释放和PG合成的基础将使其药理学操作更合理，并将导致开发更有效的抗青光眼和抗炎药物。