Dynamics of Signaling Pathways: Mechanism and Function

描述（由申请人提供）：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。本研究的重点是p53信号网络的基本细胞机制。p53系统协调细胞对环境损伤和自发损伤的反应，特别是对DNA的损伤。p53系统的缺失或突变使人类细胞易患癌症，并在大部分癌症中观察到。虽然p53通路的分子功能和调控已被广泛研究，但野生型或突变型p53究竟是如何决定单个细胞的命运的，以及为什么受到相同损伤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（癌细胞和非癌细胞）、p53状态（野生型或突变型）、p53动态和细胞结果（生长、停滞或死亡）之间的因果关系有定量的理解。我们假设p53的时间动态（即p53水平随时间的变化）在细胞命运决定中起作用：我们最近表明，不同的压力会导致不同的p53动态，p53动态的调节会改变细胞结果。在这项资助中，我们建议将单个细胞中p53和细胞结果的定量动态测量（使用活细胞成像）与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网络突变对p53动力学和细胞命运决定的影响，以及p53动力学和下游决策如何对代表性基因毒性化疗药物作出反应。我们的结果将为p53通路的控制和操作提供新的见解，p53通路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p53回路（控制单个细胞生长或死亡的关键回路）的详细定量了解，将有助于我们理解为什么一些细胞在化疗药物的作用下死亡，而另一些细胞却存活下来，并可能提出有选择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作用，并将为分析、描述和理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.