Analysis and Modeling of Ca2+ Signaling Spines

描述(由申请人提供) 神经和精神疾病的部分原因是突触传递调节的紊乱。在谷氨酸能脊髓中，通过NMDA受体的钙内流是突触可塑性的主要调节因素。脊椎含有许多可受钙离子调节的信号蛋白。不同的调节通路在不同的实验条件下被激活，因此，钙内流可以导致突触强度的增加或减少，持续时间不同。本课题研究的目的是对脊椎中钙离子调控的信号转导有一个定量的了解，并应用计算方法来模拟脊椎中钙离子信号传导过程中初始事件的动态变化。该计划包括四个项目和一个将提供新计算机软件的核心。项目一将利用计算机程序Mcell开发和测试基于真实突触几何形状和测量的相关信号分子的空间分布和动力学特性的脊椎钙动力学模型。这些模型将使用将在核心中开发的简化程序接口来构建，并将纳入项目2和项目4中产生的数据。项目2将在光学和电子显微镜水平上使用定量免疫细胞化学来研究脊椎中钙源和钙汇的组织，以及钙离子靶标CaM Kinase II的分布。这些数据将与项目4中的测量结果进行比较，并用于约束项目1和3产生的模拟。项目3将开发和测试准确的CaMKII激活动力学模型，该模型将被纳入项目1中构建的脊椎中的钙动力学模型。模拟CaMKII激活的预测将与项目4一起进行实验测试。项目4将使用双光子荧光显微镜来测量单个脊椎中的[Ca2+]信号及其调节。这些数据将与项目2中的数据集成，并用于构建和测试项目1和项目3中制作的模型。该计划解决了NINDS的通道、突触和电路计划的两个目标：1.促进分子和细胞水平的研究人员之间的合作，为通道和突触的分析开发多学科方法；2.促进神经科学家、计算机科学家和物理学家之间的合作，开发用于数据分析和建模的计算工具。这些模型和模拟的目的将是量化关于脊椎中钙功能的假设，以便用实验严格地检验它们。我们将尝试预测突触结构和分子组成的测量变化对其信号功能的相对重要性。这些预测将通过与实验的比较来检验。因此，我们认为我们提议生成的模型和模拟是用于研究突触信号动力学的强大的量化工具，而不是其本身的目的。

DESCRIPTION (provided by applicant) Neurological and mental diseases result, in part, from derangements in regulation of synaptic transmission. In glutamatergic spines, calcium influx through NMDA receptors is a principal regulator of synaptic plasticity. Spines contain many signaling proteins that can be regulated by Ca2+. Different regulatory pathways are activated under different experimental conditions; and, thus, calcium influx can lead to increases or decreases, of varying durations, in synaptic strength. The objectives of the work proposed in this Program Project are to gain a quantitative understanding of Ca2+-regulated signal transduction triggered by Ca2+ in spines, and to apply computational methods to stimulate the dynamics of initial events during Ca2+ signaling in spines. The program includes four projects and a core that will provide new computer software. Project 1 will make use of the computer program Mcell to develop and test models of calcium dynamics in spines based on realistic synaptic geometries and measured spatial distributions and kinetic properties of relevant signaling molecules. The models will be constructed with the use of a streamlined program interface to be developed in the core, and will incorporate data generated in Projects 2 and 4. Project 2 will use quantitative immunocytochemistry at the light and electron microscope levels to study the organization of calcium sources and sinks in spines, as well as the distribution of the Ca2+ target, CaM kinase II. The data will be compared with measurements made in Project 4, and used to constrain simulations arising from Projects 1 and 3. Project 3 will develop and test accurate kinetic models of activation of CaMKII that will be incorporated into the models of Ca2+ dynamics in spines constructed in Project 1. Predictions of simulations of activation of CaMKII will be tested experimentally in conjunction with project 4. Project 4 will use 2-photon fluorescence microscopy to measure [Ca2+] signals and their regulation in individual spines. The data will be integrated with that from project 2, and used to construct and test models made in projects 1 and 3. The program addresses two goals of the Channels, Synapses, and Circuits program of NINDS: 1. To facilitate collaborations among researchers working at molecular and cellular levels to develop multidisciplinary approaches for analysis of channels and synapses and 2. To facilitate collaborations among neuroscientists, computer scientists, and physicists to develop computational tools for data analysis and modeling. The purpose of the models and simulations will be to quantify hypotheses about Ca+ function in spines in order to test them rigorously with experiments. We will attempt to predict the relative importance of measured variations in the structure and molecular composition of synapses for their signaling capabilities. The predictions will be tested by comparison to experiments. Thus, we view the models and the simulations we propose to generate as powerful quantitative tools with which to study the dynamics of synaptic signaling, and not as an end in themselves.