Multi-scale observation and modeling of IP3/Ca signaling

描述(由申请人提供)：本项目的总体目标涉及多尺度建模和实验观察的协同方法，以阐明三磷酸肌醇(IP3)介导的细胞钙信号的基本机制。细胞内钙离子瞬变无处不在地调节着细胞的各种功能，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微米和分钟，涉及由单个通道、通道集群和集群之间的相互作用产生的钙音素的层次结构。这些能级不能被任何单一的实验技术同时观测到，较短的尺度低于实验分辨率。因此，我们将数据驱动的数学建模与实验电生理和成像测量相结合，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的，以产生全局细胞钙信号。具体目的是：(I)表征IP3受体(IP3R)的门控和钙渗透特性，并建立一个预测的马尔可夫模型来解释IP3和钙对其复杂的调控；(Ii)通过实验确定IP3R之间的空间分布和功能相互作用，并应用IP3R模型建立基于细胞观察的随机簇模型；(Iii)确定作为全球细胞信号基础的簇-簇相互作用和IP3扩散的机制。我们专注于单个实验易处理系统中的IP3信号转导(人1型IP3R在DT40细胞中表达，在SH-SY5Y神经母细胞瘤细胞中自然表达)，并进一步研究阿尔茨海默病导致的早老素突变引起的扰动。此外，我们开发的实验和理论工具将被广泛应用，新出现的原理将阐明许多细胞类型中钙信号的基本机制。我们的小组由三名首席调查人员组成，他们的专业知识和职责如下：约翰·E·皮尔逊。洛斯阿拉莫斯。理论家-提供项目的总体指导和数据合成；构建InsP3R门控的最小马尔可夫模型和全面的多尺度细胞模型。唐恩·D·麦晋桁宾夕法尼亚大学。实验者-单通道电生理记录和建模。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。我们的结果将有助于阐明复杂的钙信号背后的机制，这些信号调节体内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。

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 inositol trisphosphate (IP3)-mediated cellular Ca2+ signaling. Cytosolic Ca2+ transients ubiquitously regulate 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 micrometers and minutes, involving a hierarchy of 'phonemes' of Ca2+ generated by individual channels, channels 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 integrate data-driven mathematical modeling together with experimental electrophysiological and imaging measurements to elucidate how 'elementary' Ca2+ events involving individual channels and clusters are triggered and coupled to produce global cellular Ca2+ signals. Specific aims are to: (i) characterize the gating and Ca permeation properties of the IP3 receptor (IP3R), and 2+ develop a predictive Markov model to account for its complex regulation by IP3 and Ca ; (ii) experimentally 2+ determine the spatial distribution and functional interactions between IP3R and apply the IP3R model to develop a stochastic cluster model based on cellular observations; (iii) determine the mechanisms underlying cluster-cluster interactions and IP3 diffusion that underlie global cellular signals. We focus on IP3 signaling in single experimentally-tractable system (human type 1 IP3R expressed in DT40 cells and native in SH-SY5Y neuroblastoma cells), and further investigate perturbations induced by Alzheimer's-causing presenilin mutations. Moreover, 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 three Lead Investigators, with expertise and responsibilities as follows: John E. Pearson. Los Alamos. Theoretician - provide overall direction of the project and synthesis of data; construct minimal Markov model for InsP3R gating and comprehensive multi-scale cellular models. Don-On D. Mak U. Penn. Experimentalist - single-channel electrophysiological recording and modeling. Ian Parker. U.C. Irvine. Experimentalist - cytosolic Ca2+ imaging and modeling. 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 Alzheimer's, bipolar disorder, and heart failure.