REGULATION OF CARDIAC CONTRACTILITY BY DIACYLGLYCEROL

抽象的。这项研究的长期目标是阐明二酰甘油和蛋白激酶C调节心肌收缩的机制。许多细胞外化学信号，如激素、神经递质、细胞因子、生长因子、机械应激和氧应激，可能通过动员脂质第二信使(包括二酰甘油和顺式不饱和脂肪酸)来调节心肌收缩能力。至少有四个酶系统参与产生这些脂类信使，它们分别是PLA2、PLC-β、PLC-γ和PLD，它们以系统的方式产生在脂类中编码的潜在信息丰富的信号，从而产生在脂类、时间和位置中编码的潜在信息丰富的信号，以便确定这些参数对收缩调节的影响。顺式不饱和脂肪酸和钙将作为假定的与二酰甘油的共同信使进行研究，它可能选择性地激活蛋白激酶C亚型α、β或Delta。我们将探讨蛋白激酶C锚定在横管和肌丝上的机制，以及它们各自在调节收缩期钙水平和肌丝钙敏感性中的作用。蛋白激酶C介导的心肌肌钙蛋白I的磷酸化是否是心室肌细胞正性或负性变力反应的主要机制也将得到证实。其目标是利用细胞生物物理学、成像和分子生物学中的现代和创新方法的组合，为心脏中二酰甘油信号的基本问题提供明确的答案。这项研究将进一步加深我们对脂质信使改变心脏生理的基本机制以及蛋白激酶C调节心肌肌钙蛋白I功能的机制的理解，以便能够识别和纠正这些通路在不同疾病状态下的缺陷。拟议的研究将与其他次级项目高度互动，并将在很大程度上依赖方案中其他调查人员的专门知识。总体而言，这项研究解决了该计划的一个主要主题，涉及阐明心肌中膜受体拮抗剂引起的信号转导机制。

Abstract. The broad, long-term objectives of the proposed research are to elucidate mechanisms underlying the regulation of myocardial contraction by diacylglycerol and protein kinase C. Many extracellular chemical signals such as hormones, neurotransmitters, cytokines, growth factors, mechanical stress and oxygen stress may regulate cardiac contractility by mobilizing lipid second messengers including diacylglycerol and cis- unsaturated fatty acids. There are at least four enzyme systems, PLA2, PLC-beta, PLC-gamma and PLD involved in generating these lipid messengers giving rise to a potentially information-rich signal encoded in lipid species generating these lipid messengers giving rise to a potentially information-rich signal encoded in lipid species, timing and location in a systematic way in order to establish the influence of these parameters on contractile regulation. cis-Unsaturated fatty acids and Ca will be investigated as putative co-messengers with diacylglycerol that may selectively activate protein kinase C isoforms alpha, epsilon or delta. The mechanisms of protein kinase C anchoring to sites on the transverse tubules and to sites on the myofilament will be examined and their respective roles in regulating systolic Ca levels and myofilament Ca sensitivity will be established. Whether protein kinase C mediated phosphorylation of cardiac troponin I is a major mechanism underlying positive or negative inotropic responses in ventricular myocytes will also be established. The goal is to use a combination of modern and innovative methodologies in cell biophysics, imaging and molecular biology to provide unambiguous answers to fundamental questions about diacylglycerol signaling in the heart. This research will further our understanding of basic mechanisms by which lipid messengers alter cardiac physiology, and mechanisms of protein kinase C regulation of cardiac troponin I function, so that defects in these pathways in various diseased states can be identified and corrected. The proposed research will be highly interactive with other subprojects and will rely to a significant extent on the expertise of other investigators in the Program. Overall, this research addresses a major theme of the Program involving elucidation of signal transduction mechanisms evoked by membrane receptor antagonists in myocardium.