The Role of Inositol Polyphosphate 4 Phosphatase in Platelet Functions

肌醇多磷酸 4 磷酸酶在血小板功能中的作用

• 批准号: 8689369
• 负责人: Jasna Marjanovic
• 金额: $ 35.5万
• 依托单位: ST. LOUIS COLLEGE OF PHARMACY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-05 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8689369
• 关键词: 1-Phosphatidylinositol 3-Kinase; Adhesions; Agonist; Atherosclerosis; Basic Science; Biochemical; Biological Assay; Bleeding time procedure; Blood Platelets; Blood coagulation; Cardiovascular Diseases; Carotid Artery Injuries; Cells; Cleaved cell; Clot retraction; Complex; Development; Disease; Enzymes; Excision; Exhibits; Generations; Hematopoietic; Hemostatic function; Hydrolysis; Injury; Inositol; Inositol Phosphates; Integrins; Knockout Mice; Lasers; Lead; Link; Lipids; Measures; Modeling; Monitor; Monomeric GTP-Binding Proteins; Mus; Mutate; Pathogenesis; Pharmacy Students; Phenotype; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Phosphorylation; Physiological; Platelet Activation; Platelet aggregation; Play; Polyphosphates; Positioning Attribute; Process; Protein Isoforms; Radiation; Radiation Chimera; Reaction; Recruitment Activity; Regulation; Role; Route; Schools; Signal Pathway; Signal Transduction; Signaling Molecule; Students; Tail; Thrombin; Thrombosis; Thrombus; Time; Water; Work; human disease; in vivo; inorganic phosphate; intravital microscopy; kinase inhibitor; mouse model; myo-inositol-1 (or 4)-monophosphatase; null mutation; phosphatidylinositol 3,4-diphosphate; platelet typing; public health relevance; response

DESCRIPTION (provided by applicant): Platelet activation plays an important role in the development and course of cardiovascular disease. Platelet levels of phosphatidylinositol(3,4)bisphosphate (PtdIns(3,4)P2) are known to increase dramatically upon agonist stimulation in platelet aggregation-dependent manner. However, little is known about the regulation of PtdIns(3,4)P2 in platelets and its possible roles in platelet functions. We propose that the enzyme that cleaves D4 position of PtdIns(3,4)P2, inositol polyphosphate 4- phosphatase type I (INPP4A) regulates PtdIns(3,4)P2 levels and platelet function and will study this using a mouse model. We will employ radiation chimeric mice harboring a null mutation (weeble) in INPP4A restricted to cells of hematopoietic lineage to determine the role of INPP4A in platelet function. Our preliminary results indicate that platelets deficient in INPP4A generate higher levels of its substrate PtdIns(3,4)P2 after agonist stimulation, compared to the levels seen in wild type platelets. INPP4A deficient platelets also show increased platelet aggregation in response to thrombin. Radiation chimeras exhibited a prothrombotic phenotype in a mouse carotid artery injury model. We will extend these findings and study the role of INPP4A deficiency on platelet functions ex vivo (platelet aggregation, secretion, clot retraction, procoagulant activity) and in vivo utilizing hemostasis and thrombosis mouse models, while at the same time exposing pharmacy students to basic research. Two students per year will be recruited to work with Dr. Marjanovic on the projects outlined in this proposal. They will work part time during the academic school year (5-8 hrs/week) and full time during summer breaks. Our study should define the role of INPP4A and its substrate PtdIns(3,4)P2 in platelet functions, which is of importance for better understanding of mechanisms that regulate hemostasis and thrombosis.

描述（申请人提供）：血小板活化在心血管疾病的发生和病程中起着重要作用。已知磷脂酰肌醇（3,4）二磷酸（PtdIns(3,4)P2）的血小板水平在激动剂刺激下以血小板聚集依赖性方式急剧增加。然而，人们对 PtdIns(3,4)P2 在血小板中的调节及其在血小板功能中的可能作用知之甚少。我们提出，裂解 PtdIns(3,4)P2 D4 位置的酶、肌醇多磷酸 4-磷酸酶 I 型 (INPP4A) 可调节 PtdIns(3,4)P2 水平和血小板功能，并将使用小鼠模型对此进行研究。我们将使用限制于造血谱系细胞的 INPP4A 无效突变（weeble）的辐射嵌合小鼠来确定 INPP4A 在血小板功能中的作用。我们的初步结果表明，与野生型血小板中观察到的水平相比，INPP4A 缺陷的血小板在激动剂刺激后产生更高水平的底物 PtdIns(3,4)P2。 INPP4A 缺陷的血小板还表现出响应凝血酶的血小板聚集增加。放射嵌合体在小鼠颈动脉损伤模型中表现出促血栓表型。我们将扩展这些发现，并利用止血和血栓形成小鼠模型研究 INPP4A 缺陷对离体血小板功能（血小板聚集、分泌、凝块回缩、促凝血活性）和体内血小板功能的作用，同时让药学学生接触基础研究。每年将招募两名学生与 Marjanovic 博士一起参与本提案中概述的项目。他们将在学年期间兼职工作（每周 5-8 小时），并在暑假期间全职工作。我们的研究应该明确INPP4A及其底物PtdIns(3,4)P2在血小板功能中的作用，这对于更好地理解调节止血和血栓形成的机制具有重要意义。