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（IP 3）介导的细胞Ca 2+信号转导的基本机制。胞质Ca 2+瞬变普遍调节细胞功能，如分泌、收缩和增殖。信息编码的时空模式的胞质Ca 2+信号的尺度范围从纳米和微秒到微米和分钟，涉及的层次结构的“音素”的Ca 2+产生的个别通道，通道集群，集群之间的相互作用。这些水平不能同时观察到任何单一的实验技术，和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”Ca 2+事件是如何被触发和耦合以产生全局细胞Ca 2+信号的。具体目标是：（i）表征IP 3受体（IP 3R）的门控和Ca渗透性质，并且2+开发预测性马尔可夫模型以解释其通过IP 3和Ca的复杂调节;（ii）实验性地2+确定IP 3R之间的空间分布和功能相互作用，并且应用IP 3R模型以开发基于细胞观察的随机簇模型;（iii）确定作为全局细胞信号基础的簇-簇相互作用和IP 3扩散的机制。我们专注于IP 3信号在单一的实验易处理的系统（人1型IP 3R在DT 40细胞和天然的SH-SY 5 Y神经母细胞瘤细胞中表达），并进一步研究由阿尔茨海默氏症引起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，新兴的原则将阐明许多细胞类型中Ca 2+信号传导的基本机制。我们的团队包括三名首席研究员，其专业知识和职责如下：John E.皮尔森洛斯阿拉莫斯理论家-提供项目的总体方向和数据合成;构建InsP 3R门控的最小马尔可夫模型和综合多尺度细胞模型。 唐安湾麦友宾夕法尼亚州单通道电生理记录与建模。 伊恩帕克。U.C.欧文实验学家-胞质钙成像和建模。我们的研究结果将有助于阐明复杂钙信号的机制，这些信号调节体内几乎所有细胞的正常功能，并且其破坏与阿尔茨海默氏症，双相情感障碍和心力衰竭等多种疾病有关。

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.