Association of a common variant of the PPAP2B gene with cardiovascular disease.

描述(由申请人提供)： 缺血性心脏病是由冠状动脉粥样硬化引起的，尽管对其病理生物学进行了广泛的研究，识别了许多危险因素，并开发了新的治疗策略，但仍是退伍军人中最常见的死亡原因。血管内皮细胞损伤、脂质沉积、平滑肌细胞增殖和血管炎症是动脉粥样硬化发展和并发症的重要因素。具有生物活性的溶血磷脂-1-磷酸(S1P)和溶血磷脂酸(LPA)作用于许多血管细胞表达的细胞表面受体。这些脂质被定位为促进动脉粥样硬化的细胞事件的中介，它们的作用得到了来自实验模型的新证据的支持。磷脂磷酸酶3(PPAP2B基因编码)是一种细胞表面完整的膜蛋白，通过催化S1P和LPA的去磷酸化产生非受体活性的脂质产物来调节S1P和LPA的生物利用度。对一系列全基因组关联研究数据的分析将注意力集中在PPAP2B基因座的单核苷酸多态(SNP)与冠状动脉疾病之间的显著关联上。这个rs17114036 SNP位于基因的内含子非编码区，可以影响基因表达。PPAP2B基因变异如何增加冠状动脉疾病的风险尚不清楚，这在很大程度上是因为缺乏对血管细胞中LPP3功能的了解。在这一应用中，我们提出了血管细胞LPP3作为血管炎症的内在负性调节因子，抑制血管平滑肌细胞增殖，促进内皮屏障功能的证据。LPP3的这些保护作用表明，与基因表达减少相关的PPAP2B多态可能会加剧动脉粥样硬化潜在的细胞事件，增加心肌梗死的可能性。这项研究项目的长期目标是解释人类PPAP2B基因变异如何改变心肌梗死的风险，并将这一知识应用于改善缺血性心脏病的诊断和治疗。我们已经组建了一个专家团队，他们的知识涵盖了拟议研究的所有方面，以验证PPAP2B基因座在动脉粥样硬化中的功能。在这个提案中，我们将检验我们的中心假设，即PPAP2B中rs17114036的次要等位基因减少基因表达，较低水平的LPP3促进动脉粥样硬化。我们将应用我们开发的独特工具来研究LPP3，并应用我们丰富的专业知识来测试我们的中心假设。首先，我们将确定PPAP2B中rs17114036 SNP对LPP3表达和活性的影响机制。我们预测rs17114036影响U1剪接体结合部位，从而降低基因表达。我们将通过确定rs17114036的微小等位基因是否与白细胞和动脉组织中LPP3转录本和蛋白质水平的变化相关联，并通过检查多态对RNA剪接和稳定性的影响来检验这一工作假说。其次，我们将确定LPP3在实验性动脉粥样硬化中的机制作用。基于我们对具有组织特异性平滑肌和内皮LPP3缺陷的小鼠血管病理学的初步研究，这一部分的工作假设是LPP3可以预防血管炎症，因此表达减少将加速动脉粥样硬化。我们将通过确定血管组织特异性LPP3缺陷对小鼠动脉粥样硬化发展的影响来检验这一工作假说。本申请中提出的实验是从功能上验证PPAP2B中的一个常见基因变体作为人类心血管风险预测因子的重要一步。建立PPAP2B及其产物LPP3和该酶的脂质底物作为CAD的风险预测和中介有望为开发新的生物标记物和/或治疗药物确定重要的创新靶点。

DESCRIPTION (provided by applicant): Ischemic heart disease, caused by atherosclerosis of the coronary arteries, remains the most frequent cause of mortality among Veterans despite extensive investigation into its pathobiology, the identification of many risk factors, and development of new therapeutic strategies. The hallmark features of endothelial damage, lipid deposition, smooth muscle cell proliferation and vascular inflammation contribute to the development and complications of atherosclerosis. The bioactive lysophospholipids, sphingosphine-1-phosphate (S1P) and lysophosphatidic acid (LPA), act on cell surface receptors expressed by many vascular cells. These lipids are positioned to serve as mediators of the cellular events contributing to atherosclerosis, and their role is supported by emerging evidence from experimental models. The lipid phosphate phosphatase 3 (encoded by the PPAP2B gene) is a cell surface integral membrane protein that regulates the bioavailability of S1P and LPA by catalyzing their dephosphorylation to generate lipid products that are not receptor active. Analysis of data from a series of genome-wide association studies (GWAS) focuses attention on a striking association between a single nucleotide polymorphism (SNP) in the PPAP2B locus and coronary artery disease. This rs17114036 SNP lies in an intronic, non-coding region of the gene that could affect gene expression. How genetic variation in PPAP2B confers risk of coronary artery disease is unknown, in large part because of a lack of understanding of LPP3 function in vascular cells. In this application, we present evidence that vascular cell LPP3 serves as an intrinsic negative regulator of vascular inflammation, suppresses smooth muscle cell proliferation, and promotes endothelial barrier function. These protective effects of LPP3 suggest that PPAP2B polymorphisms associated with reduced gene expression could aggravate cellular events underlying atherosclerosis and increase the likelihood of myocardial infarction. The broad long-term goal of this research project is to explain how human genetic variation at the PPAP2B locus alters the risk of myocardial infarction and apply that knowledge to improve the diagnosis and therapy of ischemic heart disease. We have assembled a team of experts whose knowledge spans all aspects of the proposed research to position ourselves to validate the function of the PPAP2B locus in atherosclerosis. In this proposal, we will test our central hypothesis, which is that the minor allele of rs17114036 in PPAP2B reduces gene expression and that lower levels of LPP3 promote atherosclerosis. We will apply unique tools that we have developed to study LPP3 and our considerable expertise to test our central hypothesis. Firstly, we will identify the mechanism by which in the rs17114036 SNP in PPAP2B affects LPP3 expression and activity. We predict that rs17114036 affects a U1 splisome binding site and thereby reduces gene expression. We will test this working hypothesis by determining if the minor allele of rs17114036 associates with altered LPP3 transcript and protein levels in white blood cells and arterial tissue and by examining the consequences, of the polymorphism on RNA splicing and stability. Secondly, we will establish a mechanistic role for LPP3 in experimental atherosclerosis. Based on our Preliminary Studies of vascular pathology in mice with tissue-specific defects in smooth muscle and endothelial LPP3, the working hypothesis of this section is that LPP3 protects against vascular inflammation and that reduced expression will therefore accelerate atherosclerosis. We will test this working hypothesis by determining the consequences of vascular tissue specific deficiency of LPP3 on the development of atherosclerosis in mice. The experiments proposed in this application are an important step in functionally validating a common genetic variant in PPAP2B as a cardiovascular risk predictor in humans. Establishing PPAP2B, its product LPP3 and the lipid substrates of this enzyme as risk predictors and mediators of CAD promises to identify important and innovative targets for the development of new biomarkers and/or therapeutics.