Cardiac function and PIP2

心脏功能和 PIP2

• 批准号: 6828274
• 负责人: DONALD W HILGEMANN
• 金额: $ 39万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-15 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6828274
• 关键词: Golgi apparatus; alcohol phosphotransferase; cardiac myocytes; cytokine; enzyme mechanism; guinea pigs; heart contraction; heart function; high performance liquid chromatography; laboratory mouse; laboratory rabbit; laboratory rat; membrane activity; membrane transport proteins; phosphatidylinositols; phospholipids; protein kinase A; protein kinase C; sarcolemma; tissue /cell culture; voltage /patch clamp

EXCEED THE SPACE PROVIDED. Phosphatidylinositol-4,5,-bis-phosphate (PIP2) is the precursor of inositol-trisphosphate (IP3), diacylglycerol (DAG), and phosphatidylinositol-trisphosphate (PIP3). It also anchors cytoskeleton and numerous signaling molecules at the plasmalemma, and its metabolism is closely coupled to membrane trafficking. In addition, it modulates profoundly the function of several cardiac ion transporters and channels. This application addresses how PIP2 is regulated in heart and how PIP2 metabolism is related to membrane turnover at the cardiac sarcolemma. As suggested by Preliminary Data, we will test whether PI4-kinases are regulated by serine/threonine phosphorylation and whether lipid phosphatases are regulated by surface membrane insertion and oxygen-dependent proteolysis. As a new experimental model, we have generated transgenic mice with cardiac-specific over-expression of the type2c_ PI4-kinase (PI4K2a). This kinase localizes primarily to Golgi and internal membranes, and its over-expression is associated with high-grade cardiac hypertrophy and up-regulation of ECC. We will now test how membrane trafficking to and away from the cardiac sarcolemma is affected using (1) fluorescent membrane dyes, (2) a new amperometric method to monitor surface membrane fusion events, and (3) high resolution capacitance measurements in on-cell patch clamp configuration. Preliminary Data suggests that PKC's may activate PI4K2Gt on internal membranes, thereby initiating movement of vesicles containing lipid phosphatases to the sarcolemma. Insertion at the sarcolemma appears to be activated directly by DAG, whereby subsequent depletion of sarcolemmal PIP2 would prevent endocytosis and favor the expansion of the sarcolemma. Complementary to studies of PI4K2(x, we will test whether the type 21_ PI4-kinase (PI4K213) is the major sarcolemmal PI4-kinase and whether its regulation may be tied to the regulation of cardiac transporters and channels. Finally, the hypothesis will be tested that PIP2 metabolism is inherently sensitive to membrane tension and curvature, as well as to myocyte stretch (i.e. the cardiac preload). PERFORMANCE SITE ========================================Section End===========================================

超过提供的空间。磷脂酰肌醇-4,5，-BIS-磷酸（PIP2）是肌醇 - 三磷酸（IP3），二酰基甘油（DAG）和磷脂酰Nyolinositol-三磷酸（PIP3）的前体。它还锚定细胞骨架和静脉内的许多信号分子，其代谢与膜运输紧密耦合。此外，它深刻调节了几种心脏离子转运蛋白和通道的功能。该应用程序介绍了PIP2在心脏中的调节以及PIP2代谢与心脏肌膜上的膜转换的关系。正如初步数据所建议的那样，我们将测试PI4-激酶是否受丝氨酸/苏氨酸磷酸化调节，以及脂质磷酸酶是否受表面膜插入和氧依赖性蛋白水解调节。作为一种新的实验模型，我们已经生成了型2C_ PI4-激酶（PI4K2A）的心脏特异性过表达的转基因小鼠。这种激酶主要定位于高尔基体和内膜，其过表达与高级心脏肥大和ECC上调有关。现在，我们将测试如何使用（1）使用（1）荧光膜染料来影响心脏肌膜的膜运输，（2）一种新的安培方法来监测表面膜融合事件，以及（3）高分辨率电容测量值。初步数据表明，PKC可能会激活内部膜上的PI4K2GT，从而引发含有脂质磷酸酶向肌膜的囊泡的运动。肌膜上的插入似乎直接通过DAG激活，随后肌膜PIP2的耗竭将阻止内吞作用并有利于肌膜扩张的扩张。对PI4K2的研究（X，我们将测试21_ PI4-激酶（PI4K213）的互补性研究是否是主要的肌膜PI4-激酶，以及其调节是否可能与心脏转运蛋白和频道的调节有关。 （即心脏序列）。