Phospholipases and retinal angiogenesis

磷脂酶和视网膜血管生成

• 批准号: 7714791
• 负责人: GADIPARTHI N RAO
• 金额: $ 31.14万
• 依托单位: UNIVERSITY OF TENNESSEE HEALTH SCI CTR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7714791
• 关键词: Abbreviations; Acids; Address; Applications Grants; Arachidonic Acids; Attenuated; Cell Proliferation; Cytochrome P450; DNA biosynthesis; Data; Development; Diabetic Retinopathy; Disease; Dominant-Negative Mutation; Endothelial Cells; Event; Fibroblast Growth Factor 2; Growth Factor; Homeostasis; Human; Hydroxyeicosatetraenoic Acids; Hyperbaric Oxygen; Isoenzymes; Knockout Mice; Lesion; Loa; Maintenance; Malignant Neoplasms; Mediating; Metabolism; Modeling; Pathogenesis; Pathway interactions; Phosphatidate Phosphatase; Phospholipase; Phospholipase A2; Phospholipase C; Phospholipase D; Play; Process; Prostaglandin-Endoperoxide Synthase; Protein Kinase C; Regulation; Research Proposals; Retinal; Retinal Diseases; Role; Signal Transduction; Small Interfering RNA; Stimulus; Substrate Specificity; Testing; Therapeutic Agents; Tube; Vascular Endothelial Growth Factors; Wound Healing; angiogenesis; atypical protein kinase C; base; citrate carrier; in vivo; indium arsenide; inhibitor/antagonist; lipoprotein lipase; migration; mouse model; novel; public health relevance; research study; response; retinal angiogenesis; vascular bed

DESCRIPTION (provided by applicant): Arachidonic acid (AA) alone or via its metabolism through the cyclooxygenase (COX), lipooxygenase (LOX) and cytochrome P450 monooxygease (CYP) pathways plays an important role in the regulation of cell signaling events that are either crucial in the maintenance of homeostasis or disease pathogenesis. Phospholipase A2 (PLA2), phospholipase D (PLD) and phospholipase C (PLC) mediate AA release in response to stimulus. Among these three phospholipases, PLA2 plays a rate- limiting role in stimulus-induced AA release. During the previous period of the present grant proposal, we demonstrated a potent role for the LOX metabolites of AA in the regulation of angiogenesis using microvascular endothelial cells from different vascular beds, including retinal vascular bed. While angiogenesis is essential for the development and wound healing, it also plays a progressive role in various disease processes including cancer and diabetic retinopathy. A large body of data showed that angiogenic growth factors, particularly vascular endothelial growth factor (VEGF) plays a determinant role in the pathogenesis of diabetic retinopathy. Although the signaling mechanisms underlying VEGF-induced angiogenesis are fairly well studied, the involvement of AA in its angiogenic signaling events is not explored. Towards filling this gap, we accidentally discovered that VEGF- induced AA release depends on PLD activation in human retinal microvascular endothelial cells (HRMVEC). Since inhibition of PLA2 but not diacylglycerol (DAG) lipase suppressed VEGF-induced AA release, it is likely that VEGF-induced AA release is mediated by PLD-dependent PLA2 activation. Surprisingly, inhibition of PLD or PLA2 also attenuated VEGF-induced HRMVEC DNA synthesis, migration and tube formation. Based on these novel findings, we hypothesize that PLD-dependent PLA2 activation plays a determinant role in VEGF-induced retinal angiogenesis. To test this hypothesis, we will propose and address the following three specific aims. Aim 1. To test the hypothesis that PLD mediates VEGF-induced angiogenesis. Aim 2. To test the hypothesis that PLD- dependent PLA2 activation is required for VEGF-induced angiogenesis. Aim 3. To test the hypothesis that PLD-dependent PLA2 activation plays a determinant role in retinal angiogenesis. The results of the experiments proposed in the above-listed three specific aims will provide novel information in regard to the role of PLD-PLA2 axis in the regulation of retinal angiogenesis and thereby in retinal diseases. PUBLIC HEALTH RELEVANCE: Angiogenesis plays a major role in retinal diseases such as diabetic retinopathy. Understanding the mechanisms underlying retinal angiogenesis is, therefore, crucial in the development of therapeutic agents against these ocular lesions. The present research proposal seeks to study the role of PLD- PLA2 axis in VEGF-induced retinal angiogenesis and thereby in retinopathies.

描述（由申请人提供）：花生四烯酸（AA）单独或通过其通过环氧合酶（COX）、脂氧合酶（LOX）和细胞色素P450单加氧酶（CYP）途径的代谢在细胞信号转导事件的调节中发挥重要作用，这些信号转导事件是对于维持体内平衡或疾病发病机制至关重要。磷脂酶 A2 (PLA2)、磷脂酶 D (PLD) 和磷脂酶 C (PLC) 介导 AA 因刺激而释放。在这三种磷脂酶中，PLA2 在刺激诱导的 AA 释放中发挥限速作用。在本拨款提案的前一阶段，我们利用来自不同血管床（包括视网膜血管床）的微血管内皮细胞证明了 AA 的 LOX 代谢物在调节血管生成中的有效作用。虽然血管生成对于发育和伤口愈合至关重要，但它也在包括癌症和糖尿病视网膜病变在内的各种疾病过程中发挥着渐进的作用。大量数据表明，血管生成生长因子，特别是血管内皮生长因子（VEGF）在糖尿病视网膜病变的发病机制中起着决定性作用。尽管 VEGF 诱导的血管生成的信号机制已得到相当深入的研究，但 AA 参与其血管生成信号事件的情况尚未得到探讨。为了填补这一空白，我们意外地发现 VEGF 诱导的 AA 释放依赖于人视网膜微血管内皮细胞 (HRMVEC) 中 PLD 的激活。由于抑制 PLA2 而不是二酰甘油 (DAG) 脂肪酶会抑制 VEGF 诱导的 AA 释放，因此 VEGF 诱导的 AA 释放很可能是由 PLD 依赖性 PLA2 激活介导的。令人惊讶的是，抑制 PLD 或 PLA2 也减弱了 VEGF 诱导的 HRMVEC DNA 合成、迁移和管形成。基于这些新发现，我们假设 PLD 依赖性 PLA2 激活在 VEGF 诱导的视网膜血管生成中起决定性作用。为了检验这一假设，我们将提出并解决以下三个具体目标。目的 1. 检验 PLD 介导 VEGF 诱导的血管生成的假设。目标 2. 检验以下假设：VEGF 诱导的血管生成需要 PLD 依赖性 PLA2 激活。目标 3. 检验 PLD 依赖性 PLA2 激活在视网膜血管生成中起决定性作用的假设。上述三个具体目标中提出的实验结果将提供有关 PLD-PLA2 轴在视网膜血管生成调节以及视网膜疾病中的作用的新信息。公众健康相关性：血管生成在糖尿病视网膜病变等视网膜疾病中发挥着重要作用。因此，了解视网膜血管生成的机制对于开发针对这些眼部病变的治疗剂至关重要。本研究计划旨在研究 PLD-PLA2 轴在 VEGF 诱导的视网膜血管生成中的作用，从而在视网膜病变中发挥作用。