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

描述（由申请人提供）： 由冠状动脉粥样硬化引起的缺血性心脏病仍然是退伍军人死亡的最常见原因，尽管对其病理生物学进行了广泛的研究，确定了许多危险因素，并开发了新的治疗策略。内皮损伤、脂质沉积、平滑肌细胞增殖和血管炎症的标志性特征有助于动脉粥样硬化的发展和并发症。具有生物活性的溶血磷脂，鞘氨醇-1-磷酸（S1 P）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。这些脂质被定位为有助于动脉粥样硬化的细胞事件的介质，并且它们的作用得到来自实验模型的新证据的支持。脂质磷酸磷酸酶3（由PPAP 2B基因编码）是一种细胞表面整合膜蛋白，通过催化S1 P和LPA的去磷酸化产生无受体活性的脂质产物来调节它们的生物利用度。对一系列全基因组关联研究（GWAS）数据的分析将注意力集中在PPAP 2B基因座单核苷酸多态性（SNP）与冠状动脉疾病之间的显著关联上。该rs 17114036 SNP位于基因的内含子非编码区，可能影响基因表达。PPAP 2B的遗传变异如何赋予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LPP 3在血管细胞中功能的了解。在本申请中，我们提出的证据表明，血管细胞LPP 3作为一个内在的负调节血管炎症，抑制平滑肌细胞增殖，并促进内皮屏障功能。LPP 3的这些保护作用表明，与基因表达减少相关的PPAP 2B多态性可加重动脉粥样硬化相关的细胞事件，并增加心肌梗死的可能性。 该研究项目的广泛长期目标是解释PPAP 2B位点的人类遗传变异如何改变心肌梗死的风险，并将这些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各个方面，以验证PPAP 2B基因座在动脉粥样硬化中的功能。在这个提议中，我们将测试我们的中心假设，即PPAP 2B中rs 17114036的次要等位基因降低基因表达，低水平的LPP 3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LPP 3，并利用我们丰富的专业知识来验证我们的中心假设。首先，我们将确定PPAP 2B中rs 17114036 SNP影响LPP 3表达和活性的机制。我们预测rs 17114036影响U1剪接体结合位点，从而降低基因表达。 我们将通过确定rs 17114036的次要等位基因是否与白色血细胞和动脉组织中改变的LPP 3转录物和蛋白质水平相关，并通过检查多态性对RNA剪接和稳定性的影响来检验这一工作假设。其次，我们将建立LPP 3在实验性动脉粥样硬化中的机制作用。基于我们对平滑肌和内皮LPP 3组织特异性缺陷小鼠血管病理学的初步研究，本节的工作假设是LPP 3可防止血管炎症，因此表达减少会加速动脉粥样硬化。 我们将通过确定血管组织特异性LPP 3缺乏对小鼠动脉粥样硬化发展的影响来验证这一工作假设。 本申请中提出的实验是在功能上验证PPAP 2B中的常见遗传变异作为人类心血管风险预测因子的重要一步。将PPAP 2B、其产物LPP 3和这种酶的脂质底物确定为CAD的风险预测因子和介导因子，有望为开发新的生物标志物和/或治疗方法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.