Genetic and functional analyses of a novel locus associated with LDL-C and MI

描述（由申请人提供）：项目摘要本提案将促进主要研究者的职业目标，即促进对脂质性状和心肌梗死（MI）遗传基础的理解，并将这种理解应用于患者疾病的预防。基于他丰富的研究经验，该提案将训练他使用互补方法-复杂心血管性状的人类遗传学，以及使用小鼠模型和胚胎干细胞对与这些性状相关的基因进行功能验证-以实现对全基因组关联研究（GWAS）结果的生物学理解。它还将为他提供统计遗传学，遗传学和基因组学方法，实验生物学和研究伦理学方面的教学培训。最后，它将促进他向独立研究职位的过渡，并为他申请R 01级资助提供坚实的科学基础。主要研究者将能够利用一个绝对独特的环境与不同的优势，在动物模型的心血管疾病（马萨诸塞州总医院心血管研究中心），心血管遗传学和基因组学（麻省理工学院和哈佛布罗德研究所，马萨诸塞州总医院人类遗传研究中心），以及干细胞生物学（马萨诸塞州总医院心血管研究中心、哈佛干细胞研究所）完成拟定工作。拟议研究计划的基本原理是，发现新的有效治疗人类心血管疾病的方法需要在人类中识别和验证新的疾病机制。最近，基因组变异的研究进入了一个新的阶段，在这个阶段中，无偏见的GWAS研究可以识别常见疾病的新遗传因素。在过去的两年中，发现了50多个新的和可重复的基因组位点，这些位点与血脂水平、MI和2型糖尿病有关。尽管这些观察结果可能很有希望，但要将新的关联转化为治疗方法还需要做很多工作。关键的一步是确定定位基因座中的致病DNA变异。许多基因座包含多个基因;其他基因座不包含已知基因，这表明它们可能反式作用于基因座外的基因。因此，需要明确地鉴定由每个基因座调控的致病基因。最后，需要解决基因座中的DNA变异影响致病基因的机制。简而言之，必须开辟一条从基因组定位到新的机制见解的道路。这项提议探索了这样一条新的低密度脂蛋白胆固醇（LDL-C）和MI的遗传位点的途径。在初步研究中，GWAS对LDL-C和MI进行了研究，并在染色体1p13.3上的一个基因座中发现了单核苷酸多态性（SNP），该基因座与LDL-C的相关性强于基因组中的任何其他基因座-非常小的LDL（vsLDL）颗粒浓度和MI。携带这些SNP的主要等位基因的两个拷贝的个体与次要等位基因的纯合子相比，LDL-C高16 mg/dl，vsLDL水平高40%，MI风险高18%。1p13.3上的相关基因组间隔跨越约100个内切酶（kb），包含4个基因-CELSR 2、PSRC 1、MYBPHL、SORT 1-与LDL-C调节无既定联系。该提案的核心问题是：（1）哪些1p13.3 DNA变异有助于LDL-C，vsLDL和MI，（2）哪些1p13.3基因有助于LDL-C，vsLDL和MI，以及（3）DNA变异通过什么机制影响基因功能？基因精细定位、基因重测序、小鼠基因敲减和过表达以及人类胚胎干细胞实验将用于回答这些问题。成功应导致新的致病基因和调控机制的精确定义，从而为治疗血脂异常和预防MI提供潜在的新靶点。 公共卫生相关性：心血管疾病新的有效治疗方法的发现需要识别新的疾病机制。这项提案的重点是人类1号染色体上一个与高胆固醇和心脏病发作有关的新区域。成功鉴定该区域的相关基因或基因将为预防心脏病发作提供潜在的新靶点。

DESCRIPTION (provided by applicant): PROJECT SUMMARY This proposal will facilitate the principal investigator's career goals of advancing the understanding of the inherited basis for lipid traits and myocardial infarction (MI) and applying this understanding to the prevention of disease in patients. Building on his extensive research experience, the proposal will train him in the use of complementary approaches-human genetics of complex cardiovascular traits, and the use of mouse models and embryonic stem cells for functional validation of genes associated with these traits-to achieve a biological understanding of the results of genome-wide association studies (GWAS). It will also provide him with didactic training in statistical genetics, genetic and genomic methods, experimental biology, and research ethics. Finally, it will promote his transition to an independent research position and provide him a robust scientific foundation from which to apply for R01-level funding. The principal investigator will be able to take advantage of an absolutely unique environment with diverse strengths in animal models of cardiovascular disease (Massachusetts General Hospital Cardiovascular Research Center), cardiovascular genetics and genomics (Broad Institute of MIT and Harvard, Massachusetts General Hospital Center for Human Genetic Research), and stem cell biology (Massachusetts General Hospital Cardiovascular Research Center, Harvard Stem Cell Institute) to complete the proposed work. The rationale for the proposed research plan is that the discovery of new and effective treatments for human cardiovascular diseases requires the identification and validation in humans of novel disease mechanisms. Recently, studies of genomic variation entered a new phase, in which unbiased GWAS studies can identify novel genetic contributors to common diseases. In the last two years, more than fifty new and reproducible genomic loci were discovered contributing to lipid levels, MI, and type 2 diabetes. As promising as these observations may be, much work will be needed to convert novel associations into therapies. A key step is to identify the causal DNA variants in the mapped loci. Many loci contain multiple genes; other loci contain no known genes, suggesting that they may act in trans on genes outside of the loci. Thus, there is a need to unambiguously identify the causal gene(s) regulated by each locus. Finally, there is a need to address the mechanisms by which DNA variants in loci affect the causal genes. In short, a path must be blazed from genomic localization to new mechanistic insights. This proposal explores such a path for new genetic loci identified for low-density lipoprotein cholesterol (LDL- C) and MI. In preliminary studies, GWAS for LDL-C and MI and have identified single nucleotide polymorphisms (SNPs) in a locus on chromosome 1p13.3 that is robustly associated with LDL-C-more strongly than any other locus in the genome-very small LDL (vsLDL) particle concentration, and MI. Individuals who carry two copies of the major alleles of these SNPs have 16 mg/dl higher LDL-C, 40% higher vsLDL levels, and 18% greater risk of MI when compared with homozygotes for the minor alleles. The associated genomic interval on 1p13.3 spans ~100 kilobases (kb) and harbors four genes-CELSR2, PSRC1, MYBPHL, SORT1-with no established links to LDL-C regulation. The proposal's core questions are: (1) which 1p13.3 DNA variants contribute to LDL-C, vsLDL, and MI, (2) which 1p13.3 genes contribute to LDL-C, vsLDL, and MI, and (3) by what mechanisms do the DNA variants affect gene function? Genetic fine-mapping, gene resequencing, gene knockdown and overexpression in mice, and experiments in human embryonic stem cells will be used to answer these questions. Success should result in precise definition of a novel causal gene(s) and regulatory mechanism and thereby provide a potential new target for the treatment of dyslipidemia and prevention of MI. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE The discovery of new and effective treatments for cardiovascular diseases requires the identification of novel disease mechanisms. This proposal focuses on a novel region of human chromosome 1 that is associated with high cholesterol and heart attacks. Success in identifying the responsible gene or genes in this region would provide a potential new target for the prevention of heart attacks.