Mechanotransduction of platelet receptors GPIb and GPIIb-IIIa

血小板受体 GPIb 和 GPIIb-IIIa 的机械转导

• 批准号: 10298451
• 负责人: Cheng Zhu
• 金额: $ 52.19万
• 依托单位: GEORGIA INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10298451
• 关键词: Address; Adhesions; Affinity; Agonist; Antiplatelet Drugs; Arteries; Binding; Biochemical; Biomechanics; Blood Coagulation Disorders; Blood Platelets; Blood Vessels; Blood flow; Clinical; Cues; Cytoplasmic Tail; Data; Fibrinogen; Functional disorder; G13 Protein; Glycoprotein Ib; Grant; Hemorrhage; Hemostatic Agents; Hemostatic function; Impairment; Integrins; Knock-in Mouse; Knowledge; Ligand Binding; Ligands; Mechanics; Mechanoreceptors; Mediating; Membrane; Molecular Conformation; Mutation; Participant; Pathology; Physiology; Platelet Activation; Process; Proteins; Regulation; Reporting; Role; Side; Signal Pathway; Signal Transduction; Surface; Talin; Testing; Therapeutic; Thrombosis; Thrombus; Work; adhesion receptor; design; filamin; in vivo; insight; mechanotransduction; receptor; side effect; synergism; thrombotic; von Willebrand Factor

Project Summary/Abstract Platelets are arguably the most important cellular participant in hemostasis and thrombosis. Many therapeutic strategies target platelet molecules to inhibit their functions in thrombosis. In particular, two membrane adhesion receptors, glycoprotein (GP) Ib-IX and GPIIb-IIIa (integrin IIb3), cooperatively mediate platelet adhesion and thrombus formation under high shear flow, and thus are ideal targets for inhibiting thrombosis in stenotic arteries as well as in microvasculature. Also, all anti-platelet drugs currently being used to treat thrombosis clinically have adverse hemorrhagic side effects, because the platelet plug formation required to stop bleeding is also inhibited. Under the support of this grant in its past period, we and others showed that both GPIbα and IIb3 are mechanoreceptors capable of receiving mechanical cues. We found that GPIb mechano-signaling leads to integrin inside-out signaling, which activates IIb3 from the inactive state having a bent conformation and a closed headpiece (BC) with a low affinity and short bond lifetime for ligand to an intermediate state having an extended conformation but a closed headpiece (EC) with an intermediate affinity and intermediate bond lifetime for ligand, which is distinct from the fully active state of IIb3 often seen in platelets stimulated by soluble agonists that has an extended conformation and an open headpiece (EO) with a high affinity and long bond lifetime for ligand. Significantly, the intermediate state of IIb3 mediates the formation of “biomechanical thrombi”, consisting of transient and unstable platelet aggregates resembling the dynamic outer layer of an in vivo thrombus formed under high shear blood flow, which is distinct from platelet aggregates underneath the outer layer that are further stimulated by released soluble agonists and where IIb3 are further activated to the fully active EO state. Further activation from the intermediate state to the fully active state can also be induced by IIb3 outside-in mechano- signaling, which also induces further activation of platelets. These data highlight the role of force-induced signaling – mechano-signaling – of, by, and between GPIb-IX and IIb3, and their unique importance in thrombus formation. Our overarching hypothesis is that a balanced regulation of mechano-signals of GPIbα and IIb3, and their synergy with biochemical signals induced by soluble platelet agonists, holds the promise to control thrombosis without unsetting hemostasis. The specific aims are to elucidate 1) the roles of 14-3-3ζ and filamin A on GPIbα ligand-binding, unfolding and mechano-signaling, 2) the mechanism of GPIb-IX mechanosensing- induced intracellular signaling pathway leading to integrin activation, and 3) the roles of G13, talin1 and Rap1 on GPIIb-IIIa binding, conformation and mechano-signaling. These studies will characterize the ligand-binding and signaling of of two major platelet mechanoreceptors, GPIb and GPIIb-IIIa, as related to hemostasis and thrombosis. The results will provide insights into vascular physiology and pathology and help develop therapeutic strategies to treat thrombus formation with minimal adverse bleeding side effects.

项目摘要/摘要 血小板可以说是止血和血栓形成中最重要的细胞参与者。许多疗法 策略靶向血小板分子以抑制其在血栓形成中的功能。特别是两个膜粘附 受体，糖蛋白（GP）IB-IX和GPIIB-IIIA（整合素IIB3），合作介导了血小板粘合剂和 高剪切流下的血栓形成，因此是抑制狭窄动脉血栓形成的理想靶标 以及微脉管系统。此外，目前用于治疗血栓形成的所有抗血清药物在临床上都有 不良出血的副作用，因为也抑制了停止出血所需的血小板塞形成。 在过去时期的这笔赠款的支持下，我们和其他人都表明GPIBα和IIB3均为 能够接收机械提示的机理感受器。我们发现GPIB机械信号导致 整合素内外信号传导，该信号传导从非活性状态激活IIB3，具有弯曲的考虑和A 闭合头饰（BC）具有低亲和力，配体的短键寿命短于中间状态 扩展会议，但封闭的头饰（EC）具有中间亲和力和中间债券寿命 对于配体，它与经常在血小板中经常看到的完全活性状态的配体刺激了可溶性激动剂 该会议的延长会议和一个开放的头饰（EO），具有高亲和力和长期持续的寿命 配体。值得注意的是，IIB3的中间状态介导了“生物力学血栓”的形成 瞬态和不稳定的血小板聚集体重新组合形成的体内血栓的动态外层 在高剪切的血流下，这与外层下面的血小板聚集体不同 被释放的固体激动剂刺激，其中IIB3进一步激活到完全活跃的EO状态。 从中间状态到完全活跃状态的激活也可以由IIB3外部机械诱导 信号传导，也影响血小板的进一步激活。这些数据突出了力诱导的作用 信号传导 - 机械信号 - 由GPIB-IX和IIB3之间的信号传导，以及它们在血栓上的独特重要性 形成。我们的总体假设是，GPIBα和IIB3的机械信号的平衡调节 它们与固体血小板激动剂引起的生化信号的协同作用，有望控制 血栓形成而不抑制止血。具体目的是阐明1）14-3-3ζ和丝蛋白的作用 A上的GPIBα配体结合，展开和机械信号，2）GPIB-IX机制的机理 - 诱导细胞内信号传导途径导致整联蛋白激活，3）G13，talin1和rap1的作用 关于GPIIB-IIIA结合，会议和机械信号。这些研究将表征配体结合 与止血和血栓形成有关的两个主要血小板机制受体的信号传导GPIB和GPIIB-IIIA。 结果将为血管生理和病理学提供见解，并帮助制定治疗策略 以最小的不良出血副作用处理血栓形成。