Dynamics of Signaling Pathways: Mechanism and Function

描述(申请人提供)：我们的长期目标是了解生物信号的动态行为是如何被控制的，以及这些动态是如何影响细胞反应的。这项建议侧重于p53信号网络的基本细胞机制。P53系统协调细胞对环境侮辱和自发损伤的反应，特别是那些破坏DNA的损伤。P53系统的丢失或突变极易使人类细胞患上癌症，并在很大一部分癌症中观察到。虽然P53途径的分子功能和调控已经被广泛研究，但究竟野生型或突变型P53如何决定单个细胞的命运，以及为什么暴露在相同侮辱下的细胞最终会有不同的命运，人们知之甚少。回答这些问题需要对单个细胞中事件的顺序以及细胞背景(癌症和非癌症细胞)、P53状态(野生型或突变)、P53动态和细胞结果(生长、停滞或死亡)之间的因果关系进行定量了解。我们假设P53的时间动态(即P53水平随时间的变化)在细胞命运决定中发挥作用：我们最近表明，不同的应激导致不同的P53动态，并且P53动态的调节改变了细胞结果。在这项资助中，我们建议将对单细胞中P53和细胞结果的定量动态测量(使用活细胞成像)与对P53电路的数学建模和操作相结合，以确定将P53动态与特定表型结果联系起来的分子机制。我们还将研究P53网络中的突变对P53动态和细胞命运决定的影响，以及P53动态和下游决策如何对典型的遗传毒性化疗药物做出反应。我们的结果将为控制和操纵P53途径提供新的见解，P53途径可能是保护人类细胞免受癌症发展的最重要途径。我们预计，对控制单细胞生长或死亡决定的关键电路--p53电路的详细定量了解，将有助于理解为什么一些细胞因化疗药物而死亡，而另一些细胞存活，并可能提出选择性地将癌细胞推向永久停滞或死亡的新策略。此外，我们的研究将有助于预测特定药物对特定基因型肿瘤的影响，并将为分析、描述和了解人类细胞中其他信号通路的动力学提供一个原型。

DESCRIPTION (provided by applicant): Our long-term goal is to understand how the dynamic behavior of biological signals is controlled and how these dynamics affect cellular responses. This proposal focuses on fundamental cellular mechanisms of the p53 signaling network. The p53 system orchestrates cellular responses to environmental insult and spontaneous damage, particularly those that damage DNA. Loss or mutation of the p53 system strongly predisposes human cells to cancer, and is observed in a large fraction of cancers. While the molecular function and regulation of the p53 pathway has been extensively investigated, exactly how wild-type or mutant p53 determines the fate of individual cells, and why cells exposed to the same insult end up having different fates, is poorly understood. Answering these questions requires a quantitative understanding of the order of events in single cells and the causal relationships between cellular background (cancer and non-cancerous cells), p53 status (wild-type or mutated), p53 dynamics and cellular outcomes (growth, arrest or death). We hypothesize that the temporal dynamics of p53 (i.e. changes in the levels of p53 over time) plays a role in cell fate decisions: we have recently shown that different stresses lead to different p53 dynamics and that modulation of p53 dynamics alters cellular outcomes. In this grant we propose to combine quantitative dynamic measurements of p53 and cellular outcomes in single cells (using live cell imaging) with mathematical modeling and manipulation of the p53 circuit to determine the molecular mechanisms that link p53 dynamics to specific phenotypic outcomes. We will also investigate the effect of mutations in the p53 network on p53 dynamics and on cell fate decisions and how p53 dynamics and downstream decision-making respond to representative genotoxic chemotherapy drugs. Our results will provide new insights into the control and manipulation of the p53 pathway, perhaps the most important pathway protecting human cells against the development of cancer. We anticipate that a detailed quantitative understanding of the p53 circuit, the key circuit controlling the decision to grow or die in single cells, will helpus understand why some cells die in response to chemotherapeutic drugs while others survive, and may suggest novel strategies to selectively push cancer cells toward permanent arrest or death. It addition, our study will be help predict the effects of specific drugs on tumors with specific genotypes and will provide a prototype for the analysis, description, and understanding of the dynamics of other signaling pathways in human cells.