STRUCTURE AND PROTEINS OF THE TRANSVERSE TUBULAR SYSTEM AND

横管系统的结构和蛋白质以及

• 批准号: 8169364
• 负责人: Frank Bernd Sachse
• 金额: $ 3.35万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8169364
• 关键词: Affect; Algorithms; Architecture; Area; Brain; Calcium; Calcium Signaling; Caliber; Cardiac Myocytes; Cell model; Cells; Cleaved cell; Computer Retrieval of Information on Scientific Projects Database; Computer Simulation; Coupling; Diffusion; Environment; Exhibits; Funding; Grant; Human; Image; Institution; Ion Transport; Ions; Length; Mechanics; Methods; Minor; Modeling; Muscle Cells; Neurons; Nutrient; Oryctolagus cuniculus; Proteins; Research; Research Personnel; Resources; Ryanodine Receptor Calcium Release Channel; Ryanodine Receptors; Simulate; Sodium; Sodium Channel; Sodium-Calcium Exchanger; Source; Structure-Activity Relationship; System; Testing; Tubular formation; United States National Institutes of Health; Variant; Ventricular; Ventricular Function; Work; computer studies; constriction; design; digital imaging; image processing; protein structure; research study; tool

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. (A) OBJECTIVES The architecture of the transverse tubular system (t-system) and the arrangement of associated proteins are central to the function of ventricular cardiomyocytes. The objective of our research is to study structure-function relationships of the t-system and its associated proteins. In our experimental studies, we apply confocal imaging of ventricular myocytes and methods of digital image processing to characterize the geometry of the t-system in rabbit and human cells. This allows us to quantify the distribution of t-system associated proteins such as ryanodine receptors (RyRs), neuronal (brain-type) sodium channels, and sodium-calcium exchangers (NCX), and to study the involvement of these t-system associated proteins in excitation-contraction (EC) coupling. Some of the issues we want to investigate with our experimental studies are the effects of t-tubular geometry on the diffusion of ions and nutrients in the t-system as well as the contribution of NCX and neuronal sodium channels to EC coupling. To test our experimental hypotheses we will use the NBCR tools and algorithms for the computational simulations of biomedical systems designed, developed and implemented by Dr. Holst and colleagues. Our specific aims in the proposed computational studies are: Specific Aim 1: to characterize the effects of t-tubular constrictions on calcium signaling in rabbit ventricular myocytes. In previous work, we found that constrictions occur with a spacing of 1.87¿1.09 mm along t-tubules (Savio-Galimberti et al., 2008). We speculated that this local variation in t-tubular cross-sectional area may contribute to significant local inhomogeneities of calcium and sodium concentrations in the t-system. With the UCSD sub-cellular modeling environment, we will simulate these local inhomogeneities of ionic concentrations and test our hypotheses that these inhomogeneities affect EC coupling. Specific Aim 2: to determine whether mechanical straining of t-tubules can contribute to ion transport into and out of the t-system. In previous work, we showed that t-tubules exhibit significant flattening. The ratio of the major to the minor diameters of t-tubular cross-sections was 0.73¿0.14 (Savio et al., 2007). The minor axes of t-tubular cross-sections were approximately parallel to the long axis of myocytes. The flattening of t-tubules may be related to the cells being at slack length. If this is the case it suggests that when cells shorten or lengthen a local volume change within the t-system could take place. Currently, it is unknown if and to what extent such a volume change can contribute to ion transport, which is currently thought to be only by diffusion. The UCSD sub-cellular modeling environment is an ideal platform to characterize the effects of these volume changes. Specific Aim 3: to use the UCSD modeling environment to study the effects of sodium fluxes on EC coupling. Our experimental hypotheses are that sodium flux through neuronal sodium channels can influence EC coupling presumably by reversing NCX. Reverse NCX could have a significant effect on EC coupling by priming the dyadic cleft with calcium (Sobie et al., 2008) and increasing the gain for triggered sarcoplasmic calcium release (i.e. the ratio of calcium release flux to trigger flux). An important question is how these sodium fluxes affect EC coupling.

该副本是使用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这是调查员的机构。 （a）目标 横向管状系统（T-System）的结构和相关蛋白的排列对于心室心肌细胞的功能至关重要。我们研究的目的是研究T系统及其相关蛋白质的结构功能关系。 在我们的实验研究中，我们应用了心室肌细胞和数字图像处理方法的共聚焦成像来表征兔和人类细胞中T-System的几何形状。这使我们能够量化T系统相关蛋白的分布，例如Ryanodine受体（RYRS），神经元（脑型）钠通道和钠 - 钙库交换剂（NCX），并研究这些T-系统相关蛋白在兴奋（Ectraction（Ec）中的参与。我们要通过实验研究进行研究的一些问题是T管状几何形状对离子和养分在T系统中的扩散以及NCX和神经元钠通道对EC偶联的贡献的影响。 为了检验我们的实验假设，我们将使用NBCR工具和算法来用于由Holst及其同事设计，开发和实施的生物医学系统的计算模拟。我们在拟议的计算研究中的具体目的是： 具体目标1：表征T管缩影对兔心室心肌细胞钙信号传导的影响。在以前的工作中，我们发现沿T管的间距为1.87毫米（Savio-Galimberti等，2008）。我们猜测，T尺寸横截面区域中的这种局部变化可能导致T-System中钙和钠浓度的局部不均匀性。使用UCSD亚细胞建模环境，我们将模拟这些离子浓度的这些局部不均匀性，并测试我们的假设，即这些不均匀性会影响EC耦合。 特定目的2：确定T型毛细血管的机械过力是否可以导致离子传输到T-System中。在先前的工作中，我们表明t型tubles暴露了显着的扁平化。主要t-tubulles的小直径比为0.73¿0.14（Savio等，2007）。 T型细胞的次要轴与肌细胞的长轴大致平行。 T型细胞的变平可能与细胞的长度松弛有关。如果是这种情况，则表明当细胞缩短或长度时，局部体积可能会发生T系统内的变化。目前，尚不清楚这种体积变化是否会导致离子运输，目前认为这仅是由于扩散而导致的。 UCSD亚细胞建模环境是表征这些体积变化效果的理想平台。 特定目标3：使用UCSD建模环境来研究钠通量对EC耦合的影响。我们的实验假设是，通过神经钠通道的钠通量可能会通过反向NCX来影响EC耦合。反向NCX可能通过启动二元裂缝与钙（Sobie等，2008），并增加触发的肌浆钙释放的增益（即钙释放液的比率与弹性磁通量的比率），对EC耦合产生重大影响。一个重要的问题是这些钠通量如何影响EC耦合。