Integrated Multi-scale Adhesive Dynamics Modeling of T-lymphocyte Homing

描述（由申请人提供）：免疫系统的正常功能依赖于t淋巴细胞在全身和特定组织中传播分子信息。细胞间密切的分子通讯对免疫细胞的成熟和激活至关重要。已经确定淋巴细胞从血流和淋巴管进入组织是由分子“邮编”控制的，这些分子“邮编”确定了淋巴细胞需要附着的位置。邮政编码是淋巴细胞和宿主组织上的粘附分子和趋化因子/趋化因子受体对的精确定量组合，因此当有“匹配”时，淋巴细胞以粘附迅速作出反应。本提案的目标是开发新的计算工具，以了解淋巴细胞如何整合并将分子信号转化为白细胞整合素的激活，以介导流动下的特异性粘附。这些工具的基础是信号转导网络的整合，包括g蛋白网络的趋化因子激活或SLP-76依赖性“信号体”的组装，以及细胞粘附模拟器Adhesive Dynamics。这种集成的方法，称为集成信号粘附动力学（ISAD），可以很容易地预测淋巴细胞在流动下的牢固粘附率。这项工作的目的是：1)将我们对淋巴细胞信号转导网络的建模扩展到趋化因子信号和信号体；2)将这些模型整合到ISAD模拟中，模拟淋巴细胞在特定分子底物上的渐进滚动和停止；3)将我们的模拟与工程T淋巴细胞的粘附行为进行比较，包括Jurkat细胞和敲除小鼠的T细胞，其中SLP-76被删除或改变，或二酰基甘油激酶（DGK）被删除。初步结果表明，SLP-76缺陷导致黏附性降低，DGK缺陷导致黏附性增加。通过仿真再现了DGK突变体的功能增益，验证了模型的有效性。我们还将测量和模拟多种趋化因子信号如何在单个细胞内整合以产生粘附，以及t细胞和永生化t细胞（Jurkat细胞）中关键信号成分的敲除如何导致粘附的定量改变。我们对模拟和实验的比较，以及广泛的敏感性分析，将使我们能够确定与实验观察结果一致的参数值范围，并阐明淋巴细胞粘附和归巢的关键控制途径。

DESCRIPTION (provided by applicant): The proper functioning of the immune system relies on T-lymphocytes to travel throughout the body and home to specialized tissues to transfer molecular information. Intimate molecular communication between cells is crucial to immune cells' maturation and activation. It has been established that lymphocyte trafficking from the blood stream and the lymphatic vessels into tissues is controlled by molecular "zip-codes" that identify the location where lymphocytes need to adhere. The zip-codes are precise, quantitative combinations of adhesion molecules and chemokines/chemokine receptor pairs on the lymphocyte and host tissue, such that when there is a "match", the lymphocyte responds by adhering rapidly. The goal of this proposal is to develop novel computational tools to understand how lymphocytes integrate and convert molecular signals into the activation of leukocyte integrins to mediate specific adhesion under flow. The basis of these tools is the integration of signal transduction networks, either involving chemokine activation of G-proteins networks or the assembly of the SLP-76 dependent "signalosome', into Adhesive Dynamics, a simulator of cell adhesion. This integrated method, called Integrated Signaling Adhesive Dynamics (ISAD) can readily predict the rate of lymphocyte firm adhesion under flow. The aims of this proposed work are to 1) extend our modeling of lymphocyte signal transduction networks to both chemokine signaling and the signalosome; 2) to integrate these models into ISAD simulations to simulate the progressive rolling and stopping of lymphocytes on defined molecular substrates; and 3) to compare our simulations with the adhesive behavior of engineered T- lymphocytes, including Jurkat cells and T cells from knock-out mice in which SLP-76 is deleted or altered, or in which diacylglycerol kinases (DGK) have been deleted. We show preliminary results that SLP-76 defects lead to a decrease in adhesiveness, and DGK defects lead to an increase in adhesiveness. The gain of function of DGK mutants is recapitulated by simulations, confirming the validity of our modeling. We will also measure and simulate how multiple chemokine signals are integrated within a single cell to give rise to adhesion, and how knock-downs of key signaling components both in T-cells and immortalized T-cells (Jurkat cells) lead to quantitative alterations in adhesion. Our comparison between simulation and experiment, and extensive sensitivity analysis, will allow us to identify ranges of parameter values consistent with experimental observations and to elucidate the key controlling pathways in lymphocyte adhesion and homing.