Regulation of PAF Acetylhydrolase Expression by Oxidized Phospholipids

氧化磷脂对 PAF 乙酰水解酶表达的调节

• 批准号: 7659497
• 负责人: SUZANNE E BARBOUR
• 金额: $ 18.08万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7659497
• 关键词: 5' Flanking Region; Arterial Fatty Streak; Atherosclerosis; Binding; Biological Assay; Boxing; CD14 Antigen; CD14 gene; Calcium; Cardiovascular Diseases; Cellular biology; Complex; Dendritic Cells; Disease; Enzymes; Event; Genes; Genetic Transcription; Incidence; Interleukin-6; Modeling; Molecular; Pathogenesis; Phospholipids; Phosphorylation; Phosphorylcholine; Physiological; Platelet Activating Factor; Principal Investigator; Prostaglandin Receptor; Prostaglandins; Regulation; Research Personnel; Role; STAT3 gene; Severities; TLR4 gene; Testing; Universities; Vascular Diseases; Virginia; cytokine; dinitroaminophenol; insight; lipid mediator; lipoprotein-associated phospholipase A(2); novel; oxidized low density lipoprotein; particle; prevent; prostaglandin EP2 receptor; transcription factor

DESCRIPTION (provided by applicant): Platelet-activating factor acetylhydrolase (PAFAH) also known as the lipoprotein-associated phospholipase A2 is a calcium-independent acylhydrolase that catabolizes oxidized phospholipids (oxPL) in the oxidized LDL (oxLDL) particle as well as the lipid mediator platelet-activating factor (PAF). Many recent studies have correlated PAFAH activity with severity of vascular disease and atherosclerosis. Despite the unquestioned importance of this enzyme in the pathogenesis of atherosclerosis and other vascular disease, very little is known about mechanisms regulating its expression and activity. Our preliminary studies indicate that PAFAH expression is induced by oxidized phospholipids (oxPL), derivatives of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine, a component of oxLDL. This provides us with a unique model that we will use to delineate the molecular mechanisms controlling PAFAH expression in the atherosclerotic lesion. We hypothesize that long chain, prostaglandin-like oxPL induce PAFAH by binding to the CD14/ TLR4 complex and the EP2 prostaglandin receptor on dendritic cells in the developing atherosclerotic lesion. These interactions are proposed to induce interleukin 6 (IL6) and the phosphorylation and activation of key transcription factors, events essential for optimal transcription of the PAFAH gene. To test this hypothesis, we propose the following specific aims: 1) Investigate Roles of EP2, IL6, and CD14/ TLR4 in oxPL Induction of PAFAH and 2) Investigate Molecular Mechanisms of oxPL Induction of PAFAH. In Aim 1, we will test the hypothesis that oxPL binding to EP2 and/ or the TLR4-CD14 receptor complex induces IL6 and that this cytokine is essential for optimal PAFAH induction. In Aim 2, we will investigate role of a GC-box, Sp1, and Sp3 in induction of PAFAH by oxPL and determine whether PAFAH induction is dependent on phosphorylation of Sp1/ Sp3 and/ or the association of Sp1 with activated STAT3. We have assembled a unique team of investigators for this purpose, including Dr. Norbert Leitinger (University of Virginia), a pioneer in the study of oxPL, Dr. Zendra Zehner (VCU), and expert in the transcriptional assays, DNAP, and ChIP analyses required for determination of the molecular mechanism of PAFAH induction by oxPL, and the Principal Investigator, Dr. Suzanne Barbour, an expert in the PAFAH enzyme and dendritic cell (DC) biology. Together, the proposed studies should provide insights into the physiological mechanisms that control PAFAH expression in vascular disease. We anticipate that our studies may uncover novel mechanisms to control PAFAH that could eventually result in treatments to prevent initiation or slow progression of atherosclerosis and other vascular diseases. Project Narrative: Platelet-activating Factor Acetylhydrolase (PAFAH) is the lipoprotein-associated phospholipase A2 that has been correlated with the incidence and severity of cardiovascular disease. Preliminary studies from this group of investigators indicate that PAFAH is induced by oxidized phospholipids (oxPL) in the oxidized low density lipoprotein (LDL) particle. The objective of this study is to delineate the molecular mechanisms of PAFAH induction by oxPL in hopes that this will uncover novel mechanisms for regulating the enzyme and thereby controlling cardiovascular disease.

描述（由申请人提供）：血小板激活因子乙酰水解酶（PAFAH）也称为脂蛋白相关磷脂酶 A2，是一种不依赖于钙的酰基水解酶，它分解代谢氧化低密度脂蛋白（oxLDL）颗粒中的氧化磷脂（oxPL）以及脂质介质血小板激活因子（PAF）。最近的许多研究将 PAFAH 活性与血管疾病和动脉粥样硬化的严重程度相关联。尽管这种酶在动脉粥样硬化和其他血管疾病的发病机制中的重要性毋庸置疑，但人们对调节其表达和活性的机制知之甚少。我们的初步研究表明，PAFAH 表达是由氧化磷脂 (oxPL) 诱导的，oxPL 是 1-棕榈酰-2-花生四烯酰-sn-甘油-3-磷酸胆碱（oxLDL 的组成部分）的衍生物。这为我们提供了一个独特的模型，我们将用它来描述控制动脉粥样硬化病变中 PAFAH 表达的分子机制。我们假设长链前列腺素样 oxPL 通过与正在形成的动脉粥样硬化病变中的树突状细胞上的 CD14/TLR4 复合物和 EP2 前列腺素受体结合而诱导 PAFAH。这些相互作用被认为可以诱导白细胞介素 6 (IL6) 以及关键转录因子的磷酸化和激活，这些事件对于 PAFAH 基因的最佳转录至关重要。为了检验这一假设，我们提出以下具体目标：1) 研究 EP2、IL6 和 CD14/TLR4 在 oxPL 诱导 PAFAH 中的作用；2) 研究 oxPL 诱导 PAFAH 的分子机制。在目标 1 中，我们将测试以下假设：oxPL 与 EP2 和/或 TLR4-CD14 受体复合物结合诱导 IL6，并且该细胞因子对于最佳 PAFAH 诱导至关重要。在目标 2 中，我们将研究 GC-box、Sp1 和 Sp3 在 oxPL 诱导 PAFAH 中的作用，并确定 PAFAH 诱导是否依赖于 Sp1/Sp3 的磷酸化和/或 Sp1 与激活的 STAT3 的关联。为此，我们组建了一个独特的研究团队，包括 oxPL 研究先驱 Norbert Leitinger 博士（弗吉尼亚大学）、转录测定、DNAP 和 ChIP 专家 Zendra Zehner 博士（VCU） oxPL 确定 PAFAH 诱导分子机制所需的分析，以及首席研究员 Suzanne Barbour 博士（PAFAH 酶和树突状细胞 (DC) 生物学专家）。总之，拟议的研究应该提供对血管疾病中控制 PAFAH 表达的生理机制的见解。我们预计我们的研究可能会发现控制 PAFAH 的新机制，最终可能导致预防动脉粥样硬化和其他血管疾病发生或减缓进展的治疗方法。项目叙述：血小板激活因子乙酰水解酶 (PAFAH) 是一种脂蛋白相关磷脂酶 A2，与心血管疾病的发病率和严重程度相关。这组研究人员的初步研究表明，PAFAH 是由氧化低密度脂蛋白 (LDL) 颗粒中的氧化磷脂 (oxPL) 诱导的。本研究的目的是阐明 oxPL 诱导 PAFAH 的分子机制，希望能够揭示调节该酶从而控制心血管疾病的新机制。