Multi-scale observation and modeling of IP3/Ca signaling

描述(申请人提供)：钙离子从 胞内存储到胞浆中作为一种信号机制，通过 几乎所有类型的细胞都能调节各种功能，就像分泌一样， 收缩、增殖和细胞死亡。观测技术的进展 技术揭示了细胞内钙离子的复杂模式，这些模式有助于 选择性地调节特定的细胞反应，并被构建 通过单个离子通道的活动分层，多个 集群内的频道，以及集群之间的交互。这是不可能的 在一次实验中同时分辨所有这些标度 更短的时间和距离刻度无法通过任何可用的 实验方法。因此，我们建议使用紧密集成的 模拟、电生理学和高分辨率细胞钙的方法 成像以阐明“基本”钙离子事件发生的机制 触发和耦合以产生全球细胞钙信号。 具体目的是描述(I)钙流动的动力学机制 通过单一渠道，(Ii)个体之间的功能耦合 集群内的频道，以及(Iii)集群之间的协调，允许 全局信号的传播以及缓冲区对这一过程的影响。 将根据假设和参数值构建数值模型 来自膜片钳和共聚焦细胞成像实验，并将 通过与观察结果的比较和他们的预测进行迭代测试 权力。我们的总体目标是开发一个全面的细胞内模型 与大量观察一致的Ca2+信号，具有 预测价值，并扩展到至关重要的-但在实验中无法访问 -空间和时间尺度(纳米和微秒)。我们将重点关注肌醇 三磷酸介导的钙信号转导，利用非洲爪哇卵母细胞作为 很有特色的模式系统，但涌现的原则将广泛 适用于多种细胞类型和物种，以及钙信号传导 由兰尼定受体介导。

DESCRIPTION (provided by applicant): The liberation of calcium ions from intracellular stores into the cytosol is used as a signaling mechanism by virtually all cell types to regulate functions as diverse as secretion, contraction, proliferation, and cell death. Advances in observational techniques have revealed complex patterns of intracellular Ca2+ that serve to selectively regulate specific cellular responses, and are constructed hierarchically through the activity of individual ion channels, multiple channels within clusters, and interactions between clusters. It is impossible to resolve all these scales simultaneously in a single experiment and the shorter time and distance scales cannot be resolved by any available experimental approaches. We therefore propose to use a tightly integrated approach of modeling, electrophysiology, and high-resolution cellular calcium imaging to illuminate the mechanisms by which "elementary" Ca2+ events are triggered and coupled to produce global cellular calcium signals. Specific aims are to describe (i) the kinetic mechanisms underlying the flux of calcium through single channels, (ii) the functional coupling between individual channels within a cluster, and (iii) the coordination between clusters allowing the propagation of global signals and the effects of buffers on this process. Numerical models will be constructed based on hypotheses and parameter values derived from patch-clamp and confocal cellular imaging experiments, and will be iteratively tested by comparison with observations and by their predictive power. Our overall goal is to develop a comprehensive model of intracellular Ca2+ signaling that is consistent with a multitude of observations, has predictive value, and extends to crucial - but experimentally inaccessible -space and time scales (nanometers and microseconds). We will focus on inositol trisphosphate-mediated Ca2+ signaling, utilizing Xenopus oocytes as a well-characterized model system, but the emergent principles will be widely applicable across many cell types and species, as well as to calcium signalling mediated by ryanodine receptors.