Mechanical regulation of selectin-ligand binding kinetics

项目摘要 这个建议的目的是阐明分子间相互作用的机械调节 在选择素和糖缀合物配体之间，其介导多步粘附的第一步， 循环白细胞粘附并迁移通过血管内皮的信号级联 组织损伤或感染。这些相互作用是至关重要的，因为它们的故障可能导致许多 炎性和血栓性疾病。选择素-配体相互作用是机械调节的， 在循环的水动力环境中。我们的假设是， 选择素-配体结合动力学是由特定的原子水平的相互作用引起的， 这些分子的结构。力通过改变这些分子的能量分布来调节键的解离 在力诱导的配合和/或构象变化期间， 引发滑动和捕获键。运输通过影响碰撞频率调节键的形成， 相互作用分子之间的相遇时间，调节缔合动力学对 内禀对接由于选择素-配体结合动力学决定了流动下的细胞功能，包括细胞 束缚，滚动和聚合，相对较小的结构差异，改变了原子级的相互作用 可能会对生理和病理产生重大影响。结合实验，计算， 和理论方法，这一假设将在三个综合的具体目标进行测试：1）发展 用于研究选择素-配体动力学的机械调节的分析工具，2）定义结构的影响， 选择素和配体在它们相互作用上的变化，和3）定义选择素-配体相互作用， 原子水平上的分子动力学模拟。这项系统的研究将阐明机械 选择素-配体结合动力学的调节使白细胞能够粘附到血管壁， 环流的水动力环境。解码分子结构如何决定这种调节 将为血管生理学和病理学提供重要见解。因此，这些数据可能会提供新的 抑制炎症和血栓形成过程中病理性细胞粘附的治疗方法。

PROJECT SUMMARY The objective of this proposal is to elucidate the mechanical regulation of molecular interactions between selectins and glycoconjugate ligands, which mediate the first step of a multistep adhesion and signaling cascade for circulating leukocytes to attach to and migrate across vascular endothelium at sites of tissue injury or infection. These interactions are crucial, because their malfunction can result in a number of inflammatory and thrombotic disorders. Selectin-ligand interactions are regulated mechanically as they take place in the hydrodynamic environment of the circulation. Our hypothesis is that mechanical regulation of selectin-ligand binding kinetics results from specific atomic-level interactions that are dictated by the structures of these molecules. Force regulates bond dissociation by changing the energy landscape of these interactions and/or forming new interactions during force-induced fit and/or conformational changes, thereby eliciting slip and catch bonds. Transport regulates bond formation by influencing collision frequency and encounter time between interacting molecules, modulating the dependence of association kinetics on intrinsic docking. Since selectin-ligand binding kinetics determine cellular function under flow, including cell tethering, rolling and aggregation, relatively minor structural differences that alter atomic-level interactions may have major consequences for physiology and pathology. Using combined experimental, computational, and theoretical approaches, this hypothesis will be tested in three integrated specific aims: 1) Develop analytical tools for studying mechanical regulation of selectin-ligand kinetics, 2) Define impact of structural variations in selectins and ligands on their interactions, and 3) Define selectin-ligand interactions at the atomic level by molecular dynamics simulations. This systematic study will clarify how the mechanical regulation of selectin-ligand binding kinetics enables leukocytes to adhere to blood vessel wall in the hydrodynamic environment of the circulation. Decoding how molecular structure determines this regulation will provide key insights into vascular physiology and pathology. As a result, the data may offer new therapeutic approaches to inhibiting pathological cell adhesion during inflammation and thrombosis.