STEROL DEPENDENT REGULATION OF MEVALONATE SYNTHESIS

人们已经认识到，冠心病的一个主要危险因素 疾病是血清胆固醇水平升高。这一发现 强调达成基本认识的重要性，请访问 异戊烯类化合物代谢调控的分子水平 总体而言，特别是胆固醇。这样做的主要目的是 建议评估氧固醇合成和/或其他 血清中异戊烯类化合物(低密度脂蛋白)胆固醇介导的下降 细胞甲氧丙戊酸合成的直接调控和 间接的。 我们将使用一个突变的CHO细胞系，不能去甲基化4 α-甲基甾醇，作为我们的实验模型。变种人 CHO细胞的代谢损伤消除了代谢的复杂性 由20多个4，4-二甲基间的中间体生成 类固醇和胆固醇。因此，我们要检测、隔离、 并鉴定了可能的调节氧固醇(S)合成 (3 H)甲氧戊酸或预制(14 C/3 H)胆固醇升高。 我们将推行一项工作计划，将协调、 血清介导的氧化甾醇合成的动力学评价 3-羟基，3-甲基戊二酰下调的开始 辅酶A还原酶/辅酶A合成酶 活动及其各自的营业额。此外，我们还将 评估细胞色素P450依赖的过程在 血清介导的，下调级联反应。 潜在的生物合成调节性甾醇将由 放射-高效液相色谱分离、纯化、GC/MS鉴定。 放射免疫化学技术将用于评估特定的 酶的周转率。 我们希望我们立即进行的研究能为我们提供有关 发生在血清远端的强制性促性腺激素事件 脂蛋白摄取和分解代谢。这样的信息应该有助于 作为新一代基本问题的框架 以完整的动物为主题，受到单一挑战 胆固醇餐。最终，我们希望一个根本的 将生成知识库以提供必要的洞察力 了解血清对甲氧戊酸的调节作用 综合。

It has been recognized that a major risk factor for coronary heart disease is increased serum cholesterol levels. This finding highlights the importance of achieving a basic understanding, at the molecular level, of the metabolic regulation of isopentenoids in general and cholesterol specifically. The broad aim of this proposal is to assess the role of oxysterol synthesis and/or other isopentenoids in serum (LDL) cholesterol mediated down- regulation of cellular mevalonate synthesis directly and indirectly. We will use a mutant CHO cell line, unable to demethylate 4 alpha-methyl sterols, as our experimental model. The mutant CHO cells' metabolic lesion eliminates the metabolic complexity generated by greater than 20 intermediates between 4,4-dimethyl sterols and cholesterol. As such our changes to detect, isolate, and identify potential regulatory oxysterol(s) synthesized from (3H)mevalonate or preformed (14C/3H)cholesterol are increased. We will pursue a work plan which incorporates the coordinated, kinetic assessment of serum mediated oxysterol synthesis with the onset of the down-regulation for 3-hydroxy, 3-methyl glutaryl coenzyme A (HMG-CoA) reductase/HMG-CoA synthetase activities, and their respective turnover. In addition, we will assess the role of cytochrome P450 dependent processes on the serum mediated, down-regulation cascade. Potential biosynthesized regulatory sterols will be monitored by radio-HPLC, isolated, purified and identified by GC/MS. Radioimmunochemical techniques will be used to assess specific enzyme turnover. We expect our immediate study to yield new information about the obligatory sterologenic events which occur distal to serum lipoprotein uptake and catabolism. Such information should serve as a framework for a new generation of fundamental questions to be addressed with intact animals challenged by a single cholesterol meal. Ultimately we hope that a fundamental knowledge base will be generated to provide the necessary insight for understanding serum mediated control of mevalonate synthesis.