Modeling Dynamics of Salivary Gland Branching Morphogenesis

描述（由申请人提供）：该申请是一个实验生物学家和理论数学家之间的合作项目，目的是开发一个模拟框架来模拟唾液腺分支形态发生的早期阶段，并创建一个可用于预测这种情况下细胞行为的交互式工具。现有的唾液腺工程策略无法创建复杂的分支结构或成功地产生分泌唾液的腺泡细胞，这可能与这些模型中缺乏适当的3D结构有关。虽然目前临床上需要人工唾液腺来代替患有格林综合征或头颈部肿瘤放射治疗副作用的患者受损的分泌唾液的组织，但很少有预测工具可用于模拟细胞行为。为了设计分支组织，我们需要了解分支在发育过程中是如何发生的，以及信号通路是如何转化为物理变化的。虽然已经确定了许多信号通路和结构成分在分支中起作用，但到目前为止，它们还没有被纳入一个全面的综合模型来解释分支形态发生。这种高度动态的结构过程很难单独使用传统的分子生物学方法来理解。只有实验和数学建模之间的紧密联系，才能对分支形态发生过程有一个综合的、系统级的理解。我们之前生成了一个模拟框架来模拟基于局部增殖的肺分支。这个模型是有限的，因为基膜动力学是分支的关键。我们的假设是由Rho激酶（ROCK）介导的信号控制的基底膜动力学是唾液腺分支形态发生的关键组成部分。为了解决这一假设，并为理解基底膜动力学在分支形态发生中的作用建立一个框架，我们提出了五个具体目标：具体目标1基于水平集方法开发唾液腺分支形态发生的模拟框架；具体目标2开发实验模型系统，并将实验结果与新数学模型和模拟框架的预测结果进行比较；具体目标3研究细胞骨架抑制剂对分支形态发生的作用，并使用这些数据来训练模型；确定ROCK抑制剂是否在分支形态发生过程中影响细胞骨架张力，以及确定ROCK影响分支形态发生的细胞机制。稳健的模拟框架和该项目开发的数学模型将构成唾液腺分支形态发生综合模型发展的关键的第一步。重要的是，它将通过揭示缺失的环节并为未来的研究指明方向来指导实验人员。此外，随着获得更多数据，数学模型和仿真框架可以进行修改，并将为我们提供一种工具来预测并最终控制细胞在不同基质基质上的行为，从而实现功能性唾液腺的智能工程。项目描述：从本基金获得的数据将推进有关基底膜在控制唾液腺分支形态发生中的作用的基础科学知识。此外，我们将创建一个数学模型，结合生化和物理控制的实验分析。该模型将在适当的数值框架中实施。该软件工具将通过前端用户友好界面进行访问，以便其他实验生物学家可以在对活组织进行实验之前将其作为研究工具在计算机上测试假设。最后，在生成这个允许我们在这种情况下描述和预测细胞行为的模型时，我们将深入了解需要预测细胞行为的组织工程控制细胞的新方法。这项工作将导致组织工程新模型的产生。

DESCRIPTION (provided by applicant): This application is a collaborative project between an experimental biologist and a theoretical mathematician in order to develop a simulation framework to model the early stages of salivary gland branching morphogenesis and create an interactive tool that can be used to predict cell behavior within this context. Existing strategies for engineering salivary glands have been unable to create a complex branched structure or successfully produce saliva-secreting acinar cells, which may relate to the lack of appropriate 3D structure in these models. Although there is currently a clinical need for artificial salivary glands to replace the damaged saliva-producing tissue in patients suffering from Sj"gren's Syndrome or from side effects of radiation therapy for head and neck tumors, few predictive tools are available to model cell behavior. To engineer branched tissues, we need to understand how the branching occurs during development and how signaling pathways translate into physical changes. While many signaling pathways and structural components have been identified that play a role in branching, they so far have not been incorporated into a comprehensive integrated model that explains branching morphogenesis. This highly dynamic structural process can hardly be understood using conventional molecular biology methods alone. Only a close association between experiments and mathematical modeling will allow an integrated, systems level understanding of the process of branching morphogenesis. We previously generated a simulation framework to model lung branching based on localized proliferation. This model is limited since basement membrane dynamics are critical for branching. Our hypothesis is that basement membrane dynamics controlled by Rho kinase (ROCK)-mediated signaling is a critical component of salivary gland branching morphogenesis. To address this hypothesis and to create a framework for understanding the role of basement membrane dynamics during branching morphogenesis, we propose five specific aims: Specific Aim 1 Develop a simulation framework for salivary gland branching morphogenesis based on Level Set Methods, Specific Aim 2 Develop the experimental model system and compare experimental results with predictions of the new mathematical model and simulation framework, Specific Aim 3 Investigate the function of cytoskeletal inhibitors on branching morphogenesis and use this data to train the model, Specific Aim 4 Determine if ROCK inhibitors affect cytoskeletal tension during branching morphogenesis, and Specific Aim 5 Identify the cellular mechanism by which ROCK affects branching morphogenesis. The robust simulation framework and the mathematical models developed as a result of this project will constitute the first crucial step towards development of a comprehensive model of salivary gland branching morphogenesis. Significantly, it will guide experimentalists by revealing missing links and suggesting directions for future research. Further, the mathematical model and simulation framework can be modified as more data is obtained and will provide us with a tool to predict, and eventually, control cell behavior on different matrix substrates for intelligent engineering of a functional salivary gland. Project Narrative: The data obtained from this grant will advance basic scientific knowledge regarding the role of the basement membrane in control of branching morphogenesis in the salivary gland. In addition, we will create a mathematical model that incorporates experimental analysis of both biochemical and physical control. The model will be implemented in an appropriate numerical framework. This software tool will be accessible by a front end user-friendly interface, such that it will be available for other experimental biologists to use as a research tool for testing hypothesis in silico before experimenting with live tissue. Finally, in generating this model that allows us to describe and predict cell behavior within this context, we will gain insights into new methods for controlling cells for engineering of tissues which require prediction of cell behavior. This work will lead to generation of new models for tissue engineering.