Signal Initiation from the T-cell Antigen Receptor by Mechanical Force

T 细胞抗原受体通过机械力启动信号

• 批准号: 7634397
• 负责人: TERRI H FINKEL
• 金额: $ 21.02万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-10 至 2012-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7634397
• 关键词: Adhesiveness; Adhesives; Affinity; Agonist; Antibodies; Antigen Presentation; Antigen-Presenting Cells; Antigens; Atomic Force Microscopy; Binding; Biology; CD3 Antigens; Cell Adhesion; Cell Adhesion Molecules; Cell Communication; Cytoskeleton; DNA Sequence Rearrangement; Data; Dimensions; Event; Evolution; Goals; Hydrogels; Immune response; Immunologic Receptors; Kinetics; Ligands; Lipid Bilayers; Liquid substance; Measures; Mechanical Stress; Mechanics; Membrane; Methods; Modeling; Nature; Peptide/MHC Complex; Property; Receptor Signaling; Research; Research Design; Resistance; Role; Rupture; Sensitivity and Specificity; Signal Transduction; Solutions; Speed; Stress; Structure; Surface; Surface Properties; System; T-Cell Receptor; T-Lymphocyte; TCR Activation; Testing; Time; Work; crosslink; fluidity; human disease; innovation; insight; magnetic field; micromanipulator; novel; novel strategies; receptor; receptor binding; single molecule; theories; transmission process

DESCRIPTION (provided by applicant): This innovative proposal focuses on the fundamental question of T-cell receptor (TCR) signal initiation by peptide-MHC ligands (pMHCs). A unique feature of TCR triggering is that while soluble pMHC is incapable of triggering in solution even at very high concentrations, pMHCs on antigen presenting cells (APCs) trigger TCR and activate T-cells with high potency. Using artificial antigen presentation systems with defined components, we determined that TCR can be triggered by very few (1 to 10) monomeric agonist pMHCs anchored on a surface, independent of endogenous pMHCs or other molecules on the surface of real APCs. In addition to surface-anchoring, the triggering also critically depends upon active T-cell adhesion and intact cytoskeletal function. Considering the sufficiency of these three components in TCR triggering, the dynamic nature of T cell-APC interaction, and the constant mechanical stresses on pMHC-TCR interaction, we propose a new model for TCR triggering, the receptor deformation model. We hypothesize that TCR signaling is initiated by conformational change of the TCR/CD3 complex induced by a pulling force originating from the dynamic T-cell cytoskeleton, and transmitted through pMHC-TCR interactions with sufficient resistance to rupture under force. This model not only offers a straightforward mechanism for TCR signal initiation, but also explains the extraordinary sensitivity and specificity of TCR triggering. We will test our hypothesis from two perspectives. In Specific Aim 1, we will define the physical and mechanical properties of a surface that confers pMHC with potent TCR triggering capacity. We hypothesize that a relatively immobile, stiff, and moderately adhesive surface for pMHC anchoring will enable transmission of cytoskeletal force to TCR through pMHC-TCR binding most efficiently. In Specific Aim 2, we will directly test the role of mechanical force in TCR triggering using single molecule research design. External mechanical forces will be exerted on the TCR to test their effect on triggering. The extensibility (conformational change under force) of TCR will be determined using atomic force microscopy (AFM). Finally, the rupture force (a parameter of binding strength under force) of pMHC-TCR binding will be measured using AFM, to test our hypothesis that this determines pMHC potency. In our view, by incorporating the omitted dynamic aspect of the 2D interaction between TCR and pMHC, this model represents a new step in the evolution of TCR triggering theory, from the focus on affinity to 3D kinetics, to 2D kinetics, to our dynamic 2D kinetics. The introduction of an external force to pMHC-TCR binding provides a new dimension to research on immune receptor biology. PROJECT NARRATIVE: As the very first step of antigen recognition by T-cells, TCR triggering is a critical event in the adaptive immune response. Here, we propose a new model for TCR triggering, the receptor deformation model, which explains the extraordinary sensitivity and specificity of TCR triggering, and test this model using biophysical methods and single molecule research design. An understanding of the mechanism of TCR triggering has profound implications in developing new approaches for enhancing or subduing immune responses to treat human disease.

描述（由申请人提供）：该创新提案侧重于肽-MHC配体（pMHC）引发T细胞受体（TCR）信号的基本问题。TCR触发的一个独特特征是，尽管可溶性pMHC即使在非常高的浓度下也不能在溶液中触发，但抗原呈递细胞（APC）上的pMHC触发TCR并以高效力激活T细胞。使用具有确定组分的人工抗原呈递系统，我们确定TCR可以由锚定在表面上的非常少的（1至10个）单体激动剂pMHC触发，而不依赖于真实的APC表面上的内源性pMHC或其他分子。除了表面锚定之外，触发还关键地取决于活跃的T细胞粘附和完整的细胞骨架功能。考虑到这三种成分在TCR触发中的充分性、T细胞-APC相互作用的动态性质以及pMHC-TCR相互作用的恒定机械应力，我们提出了一种新的TCR触发模型-受体变形模型。我们假设TCR信号传导是由TCR/CD 3复合物的构象变化引发的，TCR/CD 3复合物的构象变化由源自动态T细胞细胞骨架的拉力诱导，并通过pMHC-TCR相互作用传递，具有足够的抵抗力以在力下破裂。该模型不仅提供了TCR信号启动的直接机制，而且还解释了TCR触发的非凡敏感性和特异性。我们将从两个角度来检验我们的假设。在具体目标1中，我们将定义赋予pMHC有效TCR触发能力的表面的物理和机械性质。我们假设，一个相对固定的，僵硬的，和适度的粘附表面的pMHC锚定将使传输的细胞骨架力TCR通过pMHC-TCR结合最有效的。在特定目标2中，我们将使用单分子研究设计直接测试机械力在TCR触发中的作用。将在TCR上施加外部机械力，以测试其对触发的影响。将使用原子力显微镜（AFM）测定TCR的可延伸性（力作用下的构象变化）。最后，将使用AFM测量pMHC-TCR结合的断裂力（力下结合强度的参数），以检验我们的假设，即这决定了pMHC效力。在我们看来，通过结合TCR和pMHC之间的2D相互作用的省略的动态方面，该模型代表了TCR触发理论的演变中的新步骤，从关注亲和力到3D动力学，到2D动力学，再到我们的动态2D动力学。外力对pMHC-TCR结合的引入为免疫受体生物学的研究提供了新的维度。项目叙述：作为T细胞识别抗原的第一步，TCR触发是适应性免疫应答中的关键事件。在这里，我们提出了一种新的TCR触发模型，受体变形模型，它解释了TCR触发的非凡敏感性和特异性，并使用生物物理方法和单分子研究设计来测试这个模型。对TCR触发机制的理解对于开发用于增强或抑制免疫应答以治疗人类疾病的新方法具有深远意义。