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淋巴细胞在全身和体内的特殊组织中传递分子信息。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。已经证实，淋巴细胞从血流和淋巴管到组织的运输是由分子“邮政编码”控制的，分子“邮政编码”识别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黏附分子和趋化因子/趋化因子受体对的精确、定量组合，因此，当存在匹配时，淋巴细胞通过黏附快速做出反应。这项建议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，以调节流动下的特异性黏附。这些工具的基础是将信号转导网络整合到黏附动力学中，黏附动力学是细胞黏附的模拟器，其中包括G蛋白网络的趋化因子激活或依赖SLP-76的“信号体”的组装。这种集成的方法，称为集成信号黏附动力学(ISAD)，可以很容易地预测流动下淋巴细胞牢固黏附的速度。这项拟议工作的目的是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)将这些模型集成到iSAD模拟中，以模拟淋巴细胞在定义的分子底物上的渐进滚动和停止；以及3)将我们的模拟与工程T淋巴细胞的黏附行为进行比较，包括在SLP-76缺失或改变的基因敲除小鼠中的Jurkat细胞和T细胞，或者在其中二酰基甘油激酶(DGK)被缺失的基因敲除小鼠中。我们的初步结果表明，SLP-76缺陷导致粘附性下降，DGK缺陷导致粘附性增加。通过模拟再现了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整合到单个细胞内以引起黏附，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黏附的数量变化。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一致的参数值范围，并阐明淋巴细胞黏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.