Integrins and the proinflammatory phospholipase A2

整合素和促炎磷脂酶 A2

• 批准号: 7282664
• 负责人: YOSHIKAZU TAKADA
• 金额: $ 21.18万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-15 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7282664
• 关键词: Acute-Phase Proteins; Address; Affinity; Arachidonic Acids; Atherosclerosis; Binding; Biological; Biological Assay; Cardiovascular system; Cell membrane; Cells; Condition; Coronary Arteriosclerosis; Disease; Docking; Endothelial Cells; Enzymes; Esters; Event; Family member; Human; Hydrolysis; In Vitro; Individual; Inflammation; Inflammation Mediators; Inflammatory; Integrin Binding; Integrins; Interleukin-6; Intracellular Second Messenger; Ligands; Lipoproteins; Lysophospholipids; Mediating; Molecular; Mus; Mutation; Nonesterified Fatty Acids; Nuclear; Object Attachment; Pathway interactions; Phospholipase A2; Phospholipids; Plasma; Play; Production; Purpose; Reporting; Risk Marker; Role; Second Messenger Systems; Signal Transduction; Site-Directed Mutagenesis; Small Interfering RNA; Surface Plasmon Resonance; Transgenic Mice; cell type; cytokine; keratinocyte; knock-down; monocyte; mutant; novel therapeutics; receptor; research study; simulation; therapeutic target; tool

DESCRIPTION (provided by applicant): The secretory phospholipase A2 group MA (sPLA2-IIA), one of the PLA2 family members, is an acute-phase reactant and its plasma levels are markedly increased during systemic inflammatory conditions by inflammatory cytokines. Further circulating sPLA2-IIA levels constitute an independent risk marker for coronary artery disease and predict cardiovascular events. SPLA2-IIA induces proliferation, differentiation, and cytokine production, and nuclear factor (NF)-kB activation in monocytes, keratinocytes, and endothelial cells. This enzyme hydrolyzes the sn-2 ester bond in the glyceroacyl phospholipids present in lipoproteins and cell membranes, forming nonesterified fatty acids (e.g., arachidonic acid) and lysophospholipids, which act as intracellular second messengers or are further metabolized into potent mediators for inflammation. Indeed, transgenic mice expressing human sPLA2-IIA have hyperproliferation of keratinocytes and more atherosclerosis. However, some biological effects of sPLA2-IIA are independent of its catalytic function, suggesting that they are mediated by sPLA2-IIA binding to specific receptors. A high-affinity receptor for sPLA2-IIA (the M-type receptor) was identified in mice. However, the human sPLA2-IIA does not bind to the human M-type receptor, and the sPLA2-IIA receptor in human was unknown. We recently discovered that human SPLA2-IIA specifically binds to integrin alphaVbetaS. We generated sPLA2 mutants that do not bind to integrins by molecular docking simulation and site-directed mutagenesis. We hypothesize that 1) integrins serve as receptors for sPLA2-IIA, 2) integrins transduce pro-inflammatory intracellular signals from sPLA2- IIA through integrin pathways, and 3) blocking sPLA2-IIA-integrin interaction blocks pro-inflammatory functions of SPLA2-IIA. The integrin-binding defective sPLA2-IIA mutants are powerful tool to study the role of integrins in sPLA2-IIA signaling. To address this hypothesis, we propose to 1) characterize the SPLA2-IIA- integrin interaction and identify integrins that specifically bind to sPLA2-IIA in different cell types (e.g., monocytes). 2) Identify the integrin-mediated SPLA2-IIA intracellular signals using integrin-binding defective sPLA2 mutants in different cell types involved in inflammation. The proposed experiments will determine the roles of integrins in signaling and pro-inflammatory activity of sPLA2-IIA in monocytes and endothelial cells, and will establish integrin-sPLA2-IIA interaction as a novel therapeutic target for inflammatory diseases.

描述（由申请人提供）：分泌型磷脂酶A2 MA组（sPLA 2-IIA）是PLA 2家族成员之一，是一种急性期反应物，其血浆水平在全身炎症条件下通过炎性细胞因子显著升高。进一步循环sPLA 2-IIA水平构成冠状动脉疾病的独立风险标志物并预测心血管事件。SPLA 2-IIA诱导单核细胞、角质形成细胞和内皮细胞的增殖、分化和细胞因子产生以及核因子（NF）-kB活化。这种酶水解存在于脂蛋白和细胞膜中的甘油酰基磷脂中的sn-2酯键，形成非酯化脂肪酸（例如，花生四烯酸）和溶血磷脂，其充当细胞内第二信使或进一步代谢成用于炎症的有效介质。事实上，表达人sPLA 2-IIA的转基因小鼠具有角质形成细胞的过度增殖和更多的动脉粥样硬化。然而，sPLA 2-IIA的某些生物学效应不依赖于其催化功能，这表明它们是由sPLA 2-IIA与特异性受体结合介导的。在小鼠中鉴定了sPLA 2-IIA的高亲和力受体（M型受体）。然而，人sPLA 2-IIA不与人M型受体结合，并且人中的sPLA 2-IIA受体未知。我们最近发现人SPLA 2-IIA特异性结合整合素α V β S。我们通过分子对接模拟和定点突变产生了不与整合素结合的sPLA 2突变体。我们假设1）整联蛋白作为sPLA 2-IIA的受体，2）整联蛋白通过整联蛋白途径阻断来自sPLA 2- IIA的促炎细胞内信号，和3）阻断sPLA 2-IIA-整联蛋白相互作用阻断SPLA 2-IIA的促炎功能。整合素结合缺陷型sPLA 2-IIA突变体是研究整合素在sPLA 2-IIA信号转导中作用的有力工具。为了解决这一假设，我们提出1）表征SPLA 2-IIA-整联蛋白相互作用并鉴定在不同细胞类型中特异性结合sPLA 2-IIA的整联蛋白（例如，单核细胞）。2)在参与炎症的不同细胞类型中使用整合素结合缺陷型sPLA 2突变体鉴定整合素介导的SPLA 2-IIA细胞内信号。所提出的实验将确定整合素在单核细胞和内皮细胞中sPLA 2-IIA的信号传导和促炎活性中的作用，并将建立整合素-sPLA 2-IIA相互作用作为炎性疾病的新治疗靶点。