FATTY ACID METABOLISM IN CARDIAC ISCHEMIA

心肌缺血时的脂肪酸代谢

• 批准号: 2745631
• 负责人: Jeanie B. MC MILLIN
• 金额: $ 21.22万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-08-15 至 2002-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2745631
• 关键词: DNA footprinting; acetyl coA carboxylase; acyltransferase; bioenergetics; cardiac myocytes; carnitine; fatty acid metabolism; heart contraction; heart metabolism; isozymes; laboratory rat; lipid metabolism; malonyl coA; mitochondria; myocardial ischemia /hypoxia; palmitates; tissue /cell culture

A role of palmitoylcarnitine in the onset of arrhythmias and deterioration of mechanical function in the postischemic heart is suggested. Patients with genetic carnitine palmitoyltransferase (CPT) deficiencies die in cardiac arrhythmia. Morbidity due to these deficiencies is likely underestimated. The hear contains two isoforms of CPT-I, both of which produce palmitoylcarnitine for beta-oxidation. In adults, the liver isoform constitutes 2-3% of heart activity and is 100-fold less sensitive than the muscle isoform to its inhibitor, malonyl-CoA. Liver CPT-I fluctuates in activity with inhibitor sensitivity depending on diet or hormones. Liver CPT-I contributes 25% to neonatal CPT-I. Electrical stimulation of neonatal cardiac myocytes produces cellular maturation that is accompanied by proliferation and differentiation of mitochondria, the latter exemplified by isoform switching from the liver CPT-I to adult muscle CPT-I. The ability to follow sequential gene activation is a unique feature of this cardiac myocyte system and will allow us to elucidate the pathway(s) involved in the differentiation response. To understand the mechanism of CPT-I switching, [we have determined the rat muscle CPT-I gene structure and identified the minimal promoter by sequential deletion analysis.] The role of transcriptional activity in the increased muscle CPT-mRNA will be tested using 5 'flanking sequences and mutational analysis of transfected pCPT-I.Luc constructs, DNase footprinting and gel band shift assay. Novel proteins involved in isoform switching will be characterized by cloning and/or purification. [To follow the cellular integration involved in the switch to the highly malonyl-CoA sensitive isoform, the model of electrical stimulation will be used to follow maturation of the malonyl-CoA sensitive isoform, the model of electrical stimulation will be used to follow maturation of the malonyl-CoA synthetic pathway. The role of contractile activity) and fatty acids in the control of malonyl-CoA production and beta-oxidation [during mitochondrial differentiation] will be examined by measuring the effects of glucose and fatty acids on the AMP/kinase/acetyl-CoA carboxylase phosphorylation cascade. We will test the hypothesis that [as the mitochondria increase and mature, greater proportions of] myocyte malonyl-CoA is present in the mitochondrial compartment as a result of intramitochondrial synthesis of malonyl-CoA by propionyl-CoA carboxylase using acetyl-CoA as a substrate. Location of a malonyl-CoA compartment that is inaccessible to CPT-I will shed light on the inconsistency between the high malonyl CoA content in heart and reliance on beta-oxidation.

棕榈酰卡尼汀在心律失常发生和恶化中的作用 的机械功能在缺血后的心脏建议。患者 遗传性肉毒碱棕榈酰转移酶（CPT）缺乏症患者死亡， 心律不齐由于这些缺陷， 低估心脏含有CPT-I的两种同种型， 生产棕榈酰肉毒碱用于β-氧化。在成年人中，肝脏 同种型占心脏活动的2-3%，敏感性低100倍 比肌肉同种型的抑制剂，丙二酰辅酶A。肝CPT-I 活性波动，抑制剂敏感性取决于饮食或 荷尔蒙肝CPT-I占新生儿CPT-I的25%。电 刺激新生心肌细胞产生细胞成熟， 伴随着线粒体的增殖和分化， 后者的例子是从肝脏CPT-I到成人的同种型转换 肌肉CPT-I跟踪基因顺序激活的能力是一种独特的 这种心肌细胞系统的特点，并将使我们能够阐明 参与分化反应的途径。了解 CPT-I转换的机制，[我们已经确定了大鼠肌肉CPT-I 基因结构，并通过序列缺失鉴定了最小启动子 分析]。转录活性在增加肌肉中的作用 CPT-mRNA将使用5 '侧翼序列和突变序列进行测试。 转染的pCPT-I.Luc构建体的分析、DNA酶足迹和凝胶电泳 谱带移动分析参与同种型转换的新型蛋白质将被 其特征在于克隆和/或纯化。[To跟随细胞 整合参与转换到高度丙二酰辅酶A敏感的 同种型，电刺激的模型将被用于遵循 成熟的丙二酰辅酶A敏感的亚型，模型的电 将使用刺激来跟踪丙二酰-CoA合成酶的成熟。 通路收缩活动）和脂肪酸在控制中的作用 丙二酰辅酶A的产生和β-氧化[在线粒体 将通过测量葡萄糖的影响来检查分化]， 脂肪酸对AMP/激酶/乙酰辅酶A羧化酶磷酸化的影响 级联。我们将检验这样一个假设， 成熟的，更大比例的]肌细胞丙二酰辅酶A存在于 线粒体隔室作为线粒体内合成的结果， 丙二酰辅酶A通过丙酰辅酶A羧化酶使用乙酰辅酶A作为底物。 CPT-I无法接近的丙二酰辅酶A隔室的位置将 揭示了高丙二酰辅酶A含量之间的矛盾， 心脏和对β-氧化的依赖