Outside-in signaling mechanisms of platelet integrin alpha-IIb-beta3

血小板整合素α-IIb-β3由外而内的信号传导机制

• 批准号: 9241429
• 负责人: Xiaoping Du
• 金额: $ 40.35万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-15 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9241429
• 关键词: Adhesions; Adhesives; Adverse effects; Affect; Agonist; Alpha Granule; Arteries; Binding; Binding Sites; Blood Platelets; Blood Vessels; Clot retraction; Coagulation Process; Cytoplasmic Granules; Cytoplasmic Tail; Data; Development; Disease; Dissociation; Fibrin; Fibrinogen; Fibrinolytic Agents; Funding; Future; GTP-Binding Proteins; Generations; Hemorrhage; Hemostatic function; Injury; Integrin Inhibition; Integrin beta Chains; Integrin beta3; Integrins; Life; Ligand Binding; Ligands; Mediating; Myocardial Infarction; Outcome; Pathologic; Pharmaceutical Preparations; Phase; Physiological; Platelet Activation; Platelet Membrane Glycoprotein IIb; Play; Protein Subunits; Regulation; Role; SRC gene; Signal Pathway; Signal Transduction; Site; Stroke; Talin; Testing; Thrombosis; Thrombus; Time; Tyrosine Phosphorylation; adhesion receptor; base; extracellular; improved; inhibitor/antagonist; new therapeutic target; prevent; public health relevance; response

 DESCRIPTION (provided by applicant): The platelet adhesion receptor, integrin αIIbβ3, plays a critical physiological role in hemostasis and also a critical pathological role in thrombosis and in the development of thrombotic diseases such as heart attack and stroke. The integrin antagonists are effective anti-thrombotics but also have significant adverse effect of hemorrhage, which can be life-threatening. Thus, it is important to develop a new generation of anti-thrombotics that minimally cause adverse effect of bleeding. Integrin αIIbβ3 not only mediates platelet adhesion and aggregation but also transmits signals bidirectionally: Agonist-induced intracellular signals from within platelets activate the extracellular ligand binding function of integrin αIIbβ3 ("inside-out" signaling). The binding of extracellular ligand to αIIβ3 then induces "outside-in" signals, which elicit cellular responses such as platelet spreading, granule secretion, and platelet-dependent clot retraction. The "outside-in signaling" response is critical in amplifying and stabilizing thrombi, which is critically important in occlusive thromboss. During the current funding period, we have shown that the G protein subunit, Gα13, directly interacts with a highly conserved ExE motif in the cytoplasmic domain of several integrin β subunits between talin binding sites, and "time-share" the binding region with talin in opposing waves. Talin binding occurs during inside-out signaling and late phase outside-in signaling, whereas the Gα13 binding occurs during early phase outside-in signaling. We further show that Gα13 is selectively important in the early phase outside-in signaling leading to platelet spreading and amplification of platelet thrombus formation. Importantly, we have developed selective inhibitors of Gα13-integrin interaction that potently inhibited integrin outside-in signaling and arterial thrombosis without causing adverse effect of bleeding. Based on these data, we propose the overall hypothesis that the opposing waves of talin and Gα13 binding to integrin cytoplasmic domain switch the direction of integrin signaling and also control outcomes of integrin outside-in signaling. To test this hypothesis, we propose the following specific aims: (1) To investigate the switch between talin and Gα13 binding to β3 during integrin signaling and its regulatory mechanisms. (2)To further investigate the roles of Gα13-integrin interaction in mediating integrin outside-in signaling, amplification of platelet activation, and thrombosis. These studies will facilitate the development of new generations of anti-thrombotic drugs for treating thrombosis without causing excessive bleeding.

 描述（申请人提供）：血小板粘附受体，整合素αIIbβ3，在止血中发挥着关键的生理作用，在血栓形成和血栓形成中也发挥着关键的病理作用。 心脏病和中风等血栓性疾病的发展。整合素拮抗剂是有效的抗血栓药物，但也具有显着的出血副作用，可能危及生命。因此，开发新一代抗血栓药物，将出血的不良影响降到最低程度，具有重要意义。整合素αIIbβ3不仅介导血小板粘附和聚集，而且还双向传递信号：来自血小板内的激动剂诱导的细胞内信号激活整合素αIIbβ3的细胞外配体结合功能（“由内而外”信号传导）。然后细胞外配体与 αIIβ3 的结合诱导“由外向内”信号，从而引发细胞反应，例如血小板扩散、颗粒分泌和血小板依赖性血块收缩。 “由外向内信号传导”反应对于放大和稳定血栓至关重要，这对于闭塞性血栓至关重要。在当前资助期间，我们已经证明G蛋白亚基Gα13直接与talin结合位点之间的几个整合素β亚基的细胞质结构域中高度保守的ExE基序相互作用，并与talin以相反的波“分时”结合区域。 Talin 结合发生在由内向外信号传导和晚期由外向内信号传导期间，而 Gα13 结合发生在早期由外向内信号传导期间。我们进一步表明，Gα13 在导致血小板扩散和血小板血栓形成放大的早期由外向内信号传导中选择性重要。重要的是，我们开发了 Gα13-整合素相互作用的选择性抑制剂，可有效抑制整合素由外而内的信号传导和动脉血栓形成，而不会引起出血的不良影响。基于这些数据，我们提出总体假设：talin 和 Gα13 与整合素胞质结构域结合的相反波改变整合素信号传导的方向，并控制整合素由外向内信号传导的结果。为了检验这一假设，我们提出以下具体目标：（1）研究整合素信号传导过程中talin和Gα13与β3结合之间的转换及其调控机制。 (2)进一步研究Gα13-整合素相互作用在介导整合素由外向内信号传导、血小板活化放大和血栓形成中的作用。这些研究将促进新一代抗血栓药物的开发，用于治疗血栓而不引起过度出血。