REGULATION OF MYOCARDIAL FATTY ACID METABOLISM

本申请中提出的工作的目标是确定 心肌脂肪酸代谢的整体调控。 因为辅酶A(CoA)和肉碱是 近年来，这项工作针对的是脂肪酸新陈代谢 确定组织水平和细胞水平的调节 这些辅因子的分布。辅酶A在胞浆中合成 从泛酸通过活性-Na+-进入细胞 从属符号系统。辅酶A合成的调节发生在 泛酸酪氨酸激酶的水平。但是，关于 95%的细胞辅酶A位于线粒体内。大部分 建议的工作与理解本CoA的控制有关 人工合成的细胞分布途径。1.泛酸盐类 运输系统的特点很差。我们建议研究 使用灌流的心脏调节这一转运体 肌细胞，纯化的肌膜囊泡和分离的， 重组运输机。泛酸在心肌中的转运 减少80%-90%，而肝脏转运蛋白增加 在糖尿病动物身上有好几倍。我们计划调查 这些影响的机制。2.泛酸盐类的下降 转运导致细胞内泛酸浓度 降低慢性糖尿病患者的泛酸浓度 可能成为限制心肌CoA合成的因素。我们计划 确定减少泛酸的生理后果 转运对辅酶A合成、辅酶A水平和细胞代谢的影响。 3.CoA降解的功能途径尚不清楚。我们计划 来定义该通路并确定其在完整的 组织、纯化的膜和分离的线粒体。4.我们会 描述并确定新发现的规则 辅酶A转运到线粒体的系统。5.肉碱不是 在心肌中合成，但由血液中的Na+-摄取 与泛酸类似的标志体系。我们计划 开展Na~+-符号蛋白的分离纯化研究 一次开发的泛酸和肉碱体系 使用以下两种特定结合的转运蛋白的检测 重组脂蛋白中的纯化蛋白或转运活性 水泡。

The goal of the work proposed in this application is to determine the overall regulation of fatty acid metabolism in cardiac muscle. Because Coenzyme A (CoA) and carnitine are essential cofactors of fatty acid metabolism, the work has, in recent years, been directed toward determining the regulation of tissue levels and cellular distribution of these cofactors. CoA is synthesized in the cytosol from pantothenic acid which enters the cells by an active-Na+- dependent symport system. Regulation of CoA synthesis occurs at the level of the cystoloic pantothenate kinase. However, about 95% of the total cellular CoA is located in mitochondria. Much of the proposed work relates to understanding the control of this CoA synthetic, cellular distribution pathway. 1. The pantothenate transport system is poorly characterized. We propose to study the regulation of this transporter using perfused hearts, isolated myocytes, purified sarcolemmal membrane vesicles and isolated, reconstituted transporter. Pantothenate transport in heart muscle is decreased by 80-90% while transporter in liver is increased several fold in diabetic animals. We plan to investigate the mechanism of these effects. 2. The decline in pantothenate transport causes intracellular pantothenic acid concentration to decrease and, in chronic diabetes, pantothenic acid concentration may become limiting for CoA synthesis in heart muscle. We plan to determine the physiological consequences of decreased pantothenate transport on CoA synthesis, CoA levels and cellular metabolism. 3. The functional pathway of CoA degradation is not known. We plan to define the pathway and determine its regulation in intact tissue, purified membranes and isolated mitochondria. 4. We will characterize and determine the regulation of the newly discovered system for CoA transport into mitochondria. 5. Carnitine is not synthesized in heart muscle, but is taken up from blood by a Na+- symport system similar to that for pantothenic acid. We plan to begin studies on the isolation and purification of the Na+-symport systems for pantothenic acid and carnitine by first developing assays for the transporters using either specific binding to purified proteins or transport activity in reconstituted lipid vesicles.