Regulation of Platelet Glycoprotein (GP) Ib-IX Complex Function by Membrane Lipid

膜脂对血小板糖蛋白 (GP) Ib-IX 复合物功能的调节

基本信息

批准号：
8210830
负责人：
Yuandong Peng
金额：
$ 29.99万
依托单位：
BAYLOR COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-03-05 至 2014-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8210830
关键词：
1-Phosphatidylinositol 3-Kinase Adhesions Bernard-Soulier Syndrome Binding Blood Platelets Cardiovascular Diseases Cell Communication Cell membrane Chinese Hamster Ovary Cell Cholesterol Complex Cytoplasmic Tail Data Disease Dissociation Disulfide Linkage Elements Event Excision Glycoprotein Ib Glycoproteins Glycosphingolipids Hemorrhage Hemostatic function In Vitro Individual Integrins Ligands Lipids Liquid substance Mediating Membrane Membrane Lipids Oxidation-Reduction Physiological Platelet Activation Platelet Glycoprotein GPIb-IX Complex Platelet Glycoproteins Play Process Protein Disulfide Isomerase Proteins Pseudo von Willebrand disease Regulation Reporting Role Signal Transduction Signaling Molecule Specific qualifier value Structure Surface Testing Thrombosis Thrombus Transgenic Mice Vision base combat in vivo injured insight novel novel therapeutics polypeptide public health relevance receptor research study shear stress src-Family Kinases von Willebrand Factor

项目摘要

DESCRIPTION (provided by applicant): The formation of platelet thrombi at shear stress is initiated by the binding of the platelet receptor, glycoprotein (GP) Ib-IX complex, to its ligand, von Willebrand factor (VWF). This receptor-ligand interaction is essential for tethering platelets to the injured vessel wall as a prerequisite for integrin-mediated firm arrest.Amalfunction in this interaction causes either Bernard-Soulier Syndrome (BSS) or platelet-type von Willebrand disease (VWD). It has long been thought that the GP Ib-IX complex/VWF interaction only provided the physical force to decelerate the flowing platelets. Recently, however, we have begun to realize that upon interacting with VWF, the GP Ib- IX complex can initiate transmembrane signaling events for integrin activation, leading to platelet firm adhesion and aggregation. Signaling molecules, such as Src family kinase, 14-3-3> and PI-3-Kinase, through association with the cytoplasmic domains of individual polypeptides, mediate these events. Lipid domains, also known as glycosphingolipid-enriched membranes (GEMs), can act as a platform for the assembly of downstream signaling molecules of the GP Ib-IX complex. Dissociation of the GP Ib-IX complex from the GEMs by membrane cholesterol depletion abolishes platelet activation and adhesion to VWF. Nevertheless, basic inquiries as to what the structural elements of the GP Ib-IX complex for GEMs association are, how such interaction is regulated, and what the physiological relevance of GEMs association in the GP Ib-IX function is, have never been answered. Our preliminary data demonstrate that GP Ib1 association with the GEMs domain is primarily mediated by GP Ib2/GP IX. Removal of disulfide linkage between GP Ib1 and GP Ib2/GP IX not only inhibits GP Ib1 association with GEMs domain, but also inhibits GP Ib-IX complex-expressing CHO (Chinese Hamster Ovary) cells interaction with VWF under high shear. In addition, we found that protein disulfide isomerase (PDI) associates with the GP Ib-IX complex in both platelets and the GP Ib-IX complex-expressing CHO cells, an interaction only being seen in GEMs domain. Furthermore, we demonstrated that alteration of platelet membrane lipid composition inhibits both GP Ib-IX complex association with GEMs domain and complex- mediated platelet interaction with VWF. Based on these results and previously reported evidence, we hypothesize that 1) GP Ib2/GP IX contains the structural determinants to mediate the GEMs interaction with the GP Ib-IX complex; 2) redox regulation by protein disulfide isomerase plays a role in the formation of disulfide linkage between GP Ib1 and GP Ib2/GP IX for GP Ib1 association with GEMs domain; 3) specific GEMs lipid composition is critical for complex association; and 4) specific disruption of GP Ib1 association with GEMs domain abolishes GP Ib-IX complex function. Overall, this proposed study will help to elucidate the structural basis for the proper localization of the GP Ib-IX complex on platelet surface, explore a novel mechanism for GP Ib-IX complex function regulation, and finally, to provide a mechanistic guide for developing novel therapeutic strategies to combat various complex related bleeding disorders and cardiovascular disease. PUBLIC HEALTH RELEVANCE: Platelet membrane lipid domain is important for platelet function in thrombosis and haemostasis. The platelet glycoprotein GP Ib-IX complex is one of the proteins regulated by membrane lipid domain. In this project, we sight to investigate this regulatory mechanism.

描述（由申请人提供）：剪切应力下血小板血栓的形成是由血小板受体、糖蛋白（GP）Ib-IX复合物与其配体、冯维勒布兰德因子（VWF）的结合引发的。这种受体-配体相互作用对于将血小板束缚在受损的血管壁上至关重要，是整合素介导的牢固停滞的先决条件。这种相互作用的功能障碍会导致伯纳德-苏利埃综合征 (BSS) 或血小板型血管性血友病 (VWD)。长期以来，人们一直认为 GP Ib-IX 复合物/VWF 相互作用仅提供物理力来减缓血小板的流动。然而，最近我们开始意识到，在与 VWF 相互作用时，GP Ib-IX 复合物可以启动整合素激活的跨膜信号传导事件，导致血小板牢固粘附和聚集。信号分子，例如Src家族激酶、14-3-3和PI-3-激酶，通过与单个多肽的细胞质结构域结合来介导这些事件。脂质结构域，也称为富含鞘糖脂的膜 (GEM)，可以充当 GP Ib-IX 复合物下游信号分子组装的平台。通过膜胆固醇消耗将 GP Ib-IX 复合物从 GEM 上解离，从而消除血小板活化和对 VWF 的粘附。然而，关于 GEM 关联的 GP Ib-IX 复合物的结构元件是什么、如何调节这种相互作用以及 GEM 关联在 GP Ib-IX 功能中的生理相关性是什么等基本问题尚未得到解答。我们的初步数据表明，GP Ib1 与 GEM 结构域的关联主要由 GP Ib2/GP IX 介导。去除GP Ib1和GP Ib2/GP IX之间的二硫键不仅抑制GP Ib1与GEM结构域的结合，而且抑制表达GP Ib-IX复合物的CHO（中国仓鼠卵巢）细胞在高剪切下与VWF的相互作用。此外，我们发现蛋白质二硫键异构酶（PDI）与血小板和表达 GP Ib-IX 复合物的 CHO 细胞中的 GP Ib-IX 复合物相关，这种相互作用仅在 GEMs 结构域中可见。此外，我们证明血小板膜脂质组成的改变抑制GP Ib-IX复合物与GEM结构域的结合以及复合物介导的血小板与VWF的相互作用。基于这些结果和之前报道的证据，我们假设 1) GP Ib2/GP IX 包含介导 GEM 与 GP Ib-IX 复合物相互作用的结构决定因素； 2) 蛋白质二硫键异构酶的氧化还原调节在 GP Ib1 和 GP Ib2/GP IX 之间二硫键的形成中发挥作用，从而使 GP Ib1 与 GEMs 结构域结合； 3) 特定的 GEM 脂质成分对于复杂的关联至关重要； 4) GP Ib1 与 GEM 结构域关联的特异性破坏消除了 GP Ib-IX 复合体功能。总的来说，本研究将有助于阐明GP Ib-IX复合物在血小板表面正确定位的结构基础，探索GP Ib-IX复合物功能调节的新机制，并最终为开发GP Ib-IX复合物提供机制指导。对抗各种复杂的相关出血性疾病和心血管疾病的新治疗策略。公众健康相关性：血小板膜脂质结构域对于血小板在血栓形成和止血中的功能很重要。血小板糖蛋白GP Ib-IX复合物是受膜脂结构域调节的蛋白质之一。在这个项目中，我们的目标是研究这种监管机制。