Building a Systems-Level View of Cell Cycle Checkpoints

描述(申请人提供)：由于细胞周期是所有真核生物生长和发育的基础，而细胞周期的失调是癌症的典型，因此在系统水平上了解细胞周期是如何控制的是现代细胞生物学最重要的目标之一。在高度互动的协作中，将实验生物学与数学建模相结合，创建了一种强大的方法，以发展对细胞周期控制的全面理解。这种方法被用来发现有丝分裂的转变是由滞后和双稳态调节的。下一个目标是通过解决一个关键问题来建立这个基础：细胞周期引擎如何受到外部事件的影响，特别是那些威胁基因组完整性的事件。当存在对基因组稳定性的威胁时，如未复制或受损的DMA，检查点就会阻止细胞周期。几乎所有的癌细胞都会失去对检查点的控制。检查点将在实验上容易处理的非洲爪哇卵无细胞提取物和非洲爪哇胚胎中进行研究，在非洲爪哇胚胎中，细胞周期在早期发育期间广泛重塑。为了建立这种理解，将构建DNA复制检查点的数学模型，并进行严格的实验测试。这个模型应该揭示潜在的动态控制，并作为一个强大的工具来预测病理和药物扰动对细胞周期检查点的影响。为了实现构建DNA复制检查点的系统级视图的目标，将完成以下具体目标：1)构建表示未复制DNA对核心细胞周期引擎影响的数学模型，优化参数，并将该模型在万维网上提供给公众使用。2)同时，将进行关于核浓度和细胞周期酶如何影响DNA复制检查点的关键定量实验，并使用数据为模型提供信息。3)一旦掌握了未复制DNA如何影响细胞周期引擎的基本观点，该模型将扩展到包括Chk1激酶信号通路，这是癌症化疗药物的关键潜在靶点。4)最后，模型将面临挑战，以准确地表示早期开发过程中DNA复制检查点的三种不同行为，为模型提供生理测试用例，并告知哪里需要额外的数据。

DESCRIPTION (provided by applicant): Because the cell cycle underlies the growth and development of all eukaryotes, and misregulation of the cell cycle typifies cancers, achieving a systems-level understanding of how the cell cycle is controlled ranks among the most important goals in modern cell biology. Pairing experimental biology with mathematical modeling in a highly interactive collaboration creates a powerful approach to develop a comprehensive understanding of cell cycle control. This approach was used to discover that mitotic transitions are regulated by hysteresis and bistability. The next goal is to build on this foundation by addressing a critical issue: how the cell cycle engine is affected by external events, in particular, those events that threaten the integrity of the genome. Checkpoints arrest the cell cycle when a threat to genomic stability, such as unreplicated or damaged DMA, exists. Loss of checkpoint control characterizes nearly all cancer cells. Checkpoints will be investigated in the experimentally tractable cell-free extracts derived from eggs of Xenopus laevis and in Xenopus embryos, where the cell cycle extensively remodels during early development. To build this understanding, a mathematical model of the DNA replication checkpoint will be constructed and subjected to rigorous experimental testing. This model should reveal underlying dynamical controls and serve as a powerful tool for predicting the effect of pathologic and pharmacologic perturbations upon cell cycle checkpoints. To reach the goal of constructing a systems-level view of the DNA replication checkpoint, the following specific aims will be completed: 1) A mathematical model representing the effect of unreplicated DNA on the core cell cycle engine will be constructed, parameters will be optimized, and the model will be made available for public use on the World Wide Web. 2) Concurrently, key quantitative experiments concerning how nuclear concentration and cell cycle enzymes impact the DNA replication checkpoint will be conducted and data used to inform the model. 3) Once this fundamental view of how unreplicated DNA affects the cell cycle engine is in hand, the model will be extended to include the Chk1 kinase signaling pathway, a key potential target for cancer chemotherapeutics. 4) Finally, the model will be challenged to accurately represent three distinct behaviors of the DNA replication checkpoint during early development, providing a physiologic test case for the model and informing where additional data are needed.