Membrane Phospholipids: The Key Regulators of Tissue Factor Encryption/Decryption

膜磷脂：组织因子加密/解密的关键调节剂

• 批准号: 10153855
• 负责人: Vijaya Mohan Rao Lella
• 金额: $ 45.7万
• 依托单位: UNIVERSITY OF TEXAS HLTH CTR AT TYLER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10153855
• 关键词: Acute; Acute myocardial infarction; Address; Antigens; Atherosclerosis; Biology; Blood; Blood Cells; Blood Coagulation Disorders; Blood Coagulation Factor; Blood Coagulation Factor VII; Blood coagulation; Cell membrane; Cell surface; Cells; Coagulants; Coagulation Process; Complex; Data; Development; Diabetes Mellitus; Disease; Down-Regulation; Endothelial Cells; Ensure; Enzyme Inhibitor Drugs; Enzymes; Epithelial Cells; Equilibrium; Event; Factor IX; Factor VIIa; Factor X; Generations; Glycoproteins; Health; Hemorrhage; Hemostatic Agents; Hemostatic function; Hydrolysis; Infection; Inflammation; Inflammatory; Interphase Cell; Intervention; Ischemic Stroke; Kinetics; Knockout Mice; Knowledge; Lead; Lipoxygenase; Maintenance; Malignant Neoplasms; Mediating; Membrane; Membrane Microdomains; Metabolism; Molecular Conformation; Morbidity - disease rate; Mus; Pathogenesis; Pathway interactions; Pericytes; Pharmacology; Phospholipids; Plasma; Play; Preventive; Process; Proteins; Publishing; Regulation; Research; Role; Sepsis; Sphingomyelinase; Sphingomyelins; Stimulus; Structure; Testing; Thromboplastin; Thrombosis; Thrombus; Transgenic Mice; Unstable angina; Vascular Endothelial Cell; Wild Type Mouse; acid sphingomyelinase; atherogenesis; cell injury; cell type; cofactor; cohesion; encryption; experimental study; in vivo; inhibitor/antagonist; insight; macrophage; microvesicles; monocyte; mortality; mouse model; novel; novel therapeutics; overexpression; prevent; response; sphingomyelin synthase; systemic inflammatory response; thrombotic; transcription factor; vascular injury

Upon vascular injury, plasma clotting factor VII (FVII) along with traces of activated FVII (FVIIa) come into contact with the cofactor tissue factor (TF), which is expressed constitutively in cells within the vessel wall. Complex formation of FVIIa with TF results in a marked enhancement of the catalytic activity of FVIIa and triggers TF-mediated blood coagulation. Certain disease conditions induce TF expression in circulating blood cells and vascular endothelial cells and thus allow direct contact between circulating blood and TF that leads to thrombosis. While TF-mediated blood coagulation is essential to maintain hemostasis, the aberrant activation of TF-mediated blood coagulation leads to thrombosis, the precipitating event in acute myocardial infarction, ischemic stroke, and sepsis. Therefore, the proper regulation of TF expression and the activity is critical for not only to the maintenance of the hemostatic balance but also for health in general. Typically, most of the TF expressed in cells stays encrypted with very little procoagulant activity that is sufficient to achieve hemostasis but not to cause intravascular coagulation. Cellular injury enhances TF procoagulant activity greatly without altering TF antigen levels, i.e., transforming cryptic TF to prothrombotic TF. TF procoagulant activity in cells is controlled dynamically by a variety of post-translational mechanisms. Our recent studies revealed that sphingomyelin (SM) in the outer leaflet of the plasma membrane is responsible for maintaining TF in an encrypted state and that hydrolysis of SM activates TF and releases TF+ microvesicles (MVs). SM metabolism is altered in many disease settings, including atherosclerosis, diabetes, sepsis, and cancer, the same disease settings that induce aberrant activation of TF. The current proposal is built on the above novel findings and proposes to investigate the pathophysiologic relevance of SM metabolism in regulation of TF- mediated hemostasis, thrombosis, and inflammation. Aim 1 focuses on elucidating mechanisms by which SM metabolism regulates TF procoagulant activity, whereas Aim 2 investigates whether SM metabolism influences hemostasis and thrombosis. Experiments proposed in Aim 3 will test the hypothesis that acute inflammation-induced alterations in SM metabolism play a key role in TF activation and TF-mediated coagulopathy. Aim 4 focuses on investigating whether altered SM metabolism contributes to inflammation via the regulation of TF activity. In the proposed studies, we will manipulate SM levels in macrophages, endothelial cells, and other cell types by the overexpression or down regulation of various enzymes involved in the SM metabolism or using specific pharmacological inhibitors of these enzymes. We will employ various knock-out mice with altered SM metabolism and murine models of hemostasis and thrombosis to investigate the pathophysiologic relevance of the newly identified mechanism. Our proposed studies will lead to a paradigm shift in our understanding of how TF-mediated coagulation is activated in various disease settings. They may also lead to the development of novel, targeted interventions to prevent thrombosis.

血管损伤后，血浆凝血因子VII（FVII）以及激活的FVII（FVIIA）进入 与辅因子组织因子（TF）接触，该因子（TF）在容器壁中的细胞中组成型表达。 FVIIA与TF的复杂形成导致FVIIA和FVIIA催化活性的显着增强 触发TF介导的血液凝血。某些疾病状况诱导循环血液中的TF表达 细胞和血管内皮细胞，因此可以直接接触循环的血液和TF 进行血栓形成。尽管TF介导的血液凝结对于维持止血至关重要，但异常 TF介导的血液凝结的激活导致血栓形成，这是急性心肌的沉淀事件 梗塞，缺血性中风和败血症。因此，适当的TF表达和活性的调节是 不仅对维持止血平衡至关重要，而且对整个健康至关重要。通常，大多数 在细胞中表达的TF的存放量很少，几乎没有Procagulant活性，足以实现 止血，但不会引起血管内凝血。细胞损伤增强了TF Procagulant活性 极大地没有改变TF抗原水平，即将隐性TF转化为促血栓形成TF。 TF procogulant 细胞中的活性通过多种翻译后机制动态控制。我们最近的研究 揭示了质膜外部小叶中的鞘磷脂（SM）负责维持 TF处于加密状态，SM的水解激活TF并释放TF+微泡（MVS）。 SM 在许多疾病环境中，代谢有所改变，包括动脉粥样硬化，糖尿病，败血症和癌症， 相同诱导TF异常激活的疾病环境。当前的提议建立在上述小说上 发现和提议研究SM代谢在调节TF-的病理生理相关性 介导的止血，血栓形成和炎症。 AIM 1专注于阐明SM的机制 代谢调节TF Procagulant活性，而AIM 2研究了SM代谢是否是否代谢 影响止血和血栓形成。 AIM 3中提出的实验将检验急性的假设 炎症诱导的SM代谢改变在TF激活中起关键作用，而TF介导 凝血病。 AIM 4专注于研究改变的SM代谢是否导致炎症 TF活性的调节。在拟议的研究中，我们将操纵巨噬细胞中的SM水平， 内皮细胞和其他细胞类型通过涉及的各种酶的过表达或调节 在SM代谢或使用这些酶的特定药理抑制剂中。我们将雇用各种 用改变的SM代谢和止血和血栓形成的鼠模型的淘汰小鼠进行调查 新确定的机制的病理生理相关性。我们提出的研究将导致 我们对在各种疾病环境中如何激活TF介导的凝血的理解的范例转移。 它们还可能导致开发新颖的有针对性干预措施以防止血栓形成。