Multi-scale observation and modeling of IP3/Ca signaling

描述(由申请人提供)：这个项目的总体目标包括多尺度建模和实验观察的协同方法，以阐明细胞钙信号的基本机制。细胞内钙瞬变是一种无处不在的信号机制，调节细胞的各种功能，如分泌、收缩和增殖。信息由细胞内钙信号的时空模式编码，尺度从纳米和微秒到毫米和分钟，涉及通过单个通道的活动分层构建的钙“音素”；集群内的多个通道；以及集群之间的相互作用。这些能级不能用任何单一的实验技术同时观测到，较短的标度低于实验分辨率。因此，我们采用数据驱动的数学建模与实验测量相结合的双重、紧密集成和迭代的方法，包括电生理单通道记录和高分辨率细胞钙成像，以阐明涉及单个通道和簇的基本钙事件是如何被触发和耦合以产生全局细胞钙信号的。具体目标是：(I)表征IP3R的门控和钙渗透特性，并开发一个预测的数学模型来解释IP3和钙离子对其复杂的调节；(Ii)观察和模拟簇内单个通道之间随机的、钙离子介导的功能耦合；以及(Iii)确定允许全局信号传播的簇-簇相互作用的机制，以及不同动力学的钙离子缓冲器对这一过程的强大差异化调制。我们专注于单个实验易处理的系统(人SH-SY5Y神经母细胞瘤细胞)中的IP3信号，但我们开发的实验和理论工具将广泛适用，新出现的原理将阐明许多细胞类型中钙信号的基本机制。我们的小组包括五名首席调查人员，他们的专业知识和职责如下：约翰·皮尔逊。洛斯阿拉莫斯。理论家-提供全面的指导和数据合成；构建低维IP3受体模型和全面的多尺度细胞模型。凯文·福斯基特和丹尼尔·麦·U·潘。实验者-电生理单通道记录和IP3受体/通道建模。伊恩·帕克。加州大学欧文分校。实验者-细胞内钙离子成像和建模。健卫帅。厦门大学。理论家。钙离子信号的计算机模拟。我们的结果将有助于阐明复杂的钙信号背后的机制，这些信号调节身体几乎所有细胞的正常功能，其中断与阿尔茨海默氏症、双相情感障碍和心力衰竭等各种疾病有关。与公共健康相关：这种发现细胞内钙信号产生的基本机制的独特综合方法将从根本上增强我们对它们正常功能的理解，并提供对它们的干扰如何影响从胰腺炎和阿尔茨海默氏症等多种疾病的见解。

DESCRIPTION (provided by applicant): The overall goal of this project involves a synergistic approach of multi-scale modeling and experimental observation to elucidate the fundamental mechanisms underlying cellular calcium signaling. Cytosolic Ca2+ transients serve as a ubiquitous signaling mechanism that regulates cellular functions as diverse as secretion, contraction and proliferation. Information is encoded by spatio-temporal patterns of cytosolic Ca2+ signals at scales ranging from nanometers and microseconds to millimeters and minutes, involving `phonemes' of Ca2+ constructed hierarchically through the activity of individual channels; multiple channels within clusters; and interactions between clusters. These levels cannot simultaneously be observed by any single experimental technique and the shorter scales are below experimental resolution. We therefore employ a dual, tightly integrated and iterative approach of data-driven mathematical modeling together with experimental measurements involving electrophysiological single-channel recording and high-resolution cellular Ca2+ imaging to elucidate how 'elementary' Ca2+ events involving individual channels and clusters are triggered and coupled to produce global cellular calcium signals. Specific aims are to: (i) characterize the gating and Ca2+ permeation properties of IP3R, and develop a predictive mathematical model to account for its complex regulation by IP3 and Ca2+; (ii) observe and model the stochastic, Ca2+-mediated functional coupling between individual channels within a cluster, and; (iii) determine the mechanisms underlying cluster-cluster interactions that allow for propagation of global signals and the powerful differential modulation of this process by Ca2+ buffers of differing kinetics. We focus on IP3 signaling in a single experimentally-tractable system (human SH- SY5Y neuroblastoma cells), but the experimental and theoretical tools we develop will be widely applicable, and the emergent principles will illuminate fundamental mechanisms of Ca2+ signaling in many cell types. Our group involves five Lead Investigators, with expertise and responsibilities as follows: John Pearson. Los Alamos. Theoretician - provides overall direction and synthesis of data; construction of low-dimensional IP3 receptor model and comprehensive multi-scale cellular models. Kevin Foskett and Daniel Mak U. Penn. Experimentalists - electrophysiological single-channel recording and IP3 receptor/channel modeling. Ian Parker. U.C. Irvine. Experimentalist - cytosolic Ca2+ imaging and modeling. Jianwei Shuai. Xiamen University. Theoretician. Computer modeling of Ca2+ signals. Our results will help elucidate the mechanisms underlying complex calcium signals that regulate the normal functioning of almost all cells in the body, and whose disruption is implicated in diseases as diverse as Alzheimers, bipolar disorder, and heart failure. PUBLIC HEALTH RELEVANCE: This unique integrative approach to discover the fundamental mechanisms by which intracellular Ca2+ signals are generated will fundamentally enhance our understanding of their normal functioning and provide insights into how their disruption affects numerous diseases as varied as pancreatitis and Alzheimer's.