Genetic Predisposition for Intimal Hyperplasia in Mice

描述(申请人提供)：血管内膜中的平滑肌细胞(SMC)堆积和细胞外基质沉积是新生内膜增生症(IH)的主要特征，常发生在所有形式的血管重建后，包括支架植入、血管成形术、动脉内膜切除术和静脉移植。IH的一个常见结果是血管管腔直径减小，导致重要的临床问题，如心绞痛、中风、血栓形成和心肌梗死。我们的目标是识别生物标记物以评估发生高血压的风险，并确定分子介体以开发治疗易感血管的疗法。 在小鼠品系中，对结扎、慢流或内皮剥离引起的颈动脉损伤有广泛的反应，从完全耐受的小鼠到发生大的新内膜病变的小鼠。在这里，我们利用这些表型差异，通过遗传连锁和关联研究来识别颈动脉中调节血管病理的基因。 自上次提交以来，我们已经改变了我们优秀研究团队的重点，纳入了家庭联系和协会研究的专业知识。FVB(敏感株)和C57BL/6(抗性株)之间的F2群体几乎增加了一倍，并确定了6个数量性状基因座(QTL)。对10个自交系进行了下降同源性分析，缩小了QTL区间，得到了8个值得进一步研究的候选基因。我们还筛选了9个近交系小鼠品系，以期将它们纳入大型关联研究。我们提供了一个候选基因的验证数据，并展示了它与IH过程的相关性。总体而言，我们希望使用这个无偏见的系统来发现控制IH的新基因。 工作将按照三个具体目标进行：(1)确定包含调控损伤诱导的新生内膜增生(IH)易感性和抵抗力的基因的染色体间隔。我们将使用经典的连锁研究来确定F2小鼠之间的QTL和单倍型分析，以消除因血统而相同的区域。(2)利用全基因组关联研究确定介导颈动脉损伤反应性的基因和分子通路。我们将使用一个由大约100个已知基因类型的近交系菌株组成的小鼠多样性小组，并获得用于关联研究的IH表型。(3)验证和确定控制IH的潜在候选基因的功能。在AIMS 1和AIMS 2中发现的候选基因将在这里进一步研究。这些研究将包括鉴定参与表达的细胞类型(S)，鉴定培养细胞的分子功能，以及培育合适的基因工程小鼠。总体而言，这一建议的优势包括：(A)主题的新颖性；(B)杰出的研究团队；(C)目前存在的IH的QTL；以及(D)强大的初步数据，确定了具有潜在IH调节活性的候选基因，这证明了我们方法的实用性。此外，由于每年有数以万计的人受到血管损伤的影响，健康话题具有重要意义。 公共卫生相关性：新生内膜增生症(IH)的主要特征是内膜中的平滑肌细胞(SMC)积聚和细胞外基质沉积，这种疾病在各种形式的血管重建后经常发生，包括支架置入术、血管成形术、动脉内膜切除术和静脉移植。我们的目标是识别生物标记物以评估发生高血压的风险，并确定分子介体以开发治疗易感血管的疗法。这将使用遗传方法来完成。

DESCRIPTION (provided by applicant): Smooth muscle cell (SMC) accumulation and extracellular matrix deposition in the intima are major characteristics of neointimal hyperplasia (IH) which occurs frequently following all forms of vascular reconstruction, including stenting, angioplasty, endarterectomy and vein grafts. A common result of IH is the reduction of the vessel lumen diameter leading to important clinical problems such as angina, stroke, thrombosis and myocardial infarction. It is our goal to identify biomarkers to assess risk of developing IH and molecular mediators for the development of therapies to treat susceptible vessels. Among mouse strains, there is a wide range of responses to carotid artery injury as induced by ligature, slow flow or endothelial denudation ranging from mice that are completely resistant those which develop large neointimal lesions. Here, we exploit these phenotypic differences by using genetic linkage and association studies to identify genes modulating vascular pathology in carotid arteries. Since the last submission, we have altered the emphasis of our outstanding research team to include family linkage and association study expertise. We also nearly doubled an F2 population between FVB (susceptible) and C57BL/6 (resistant) strains and identified 6 quantitative trait loci (QTL). An identity by descent analysis was performed across 10 inbred strains to reduce QTL intervals which yielded 8 candidate genes worthy of further study. We also screened 9 inbred mouse strains in anticipation of entering them into a large association study. We present validation data for one candidate gene and show its relevance to the IH process. Overall, we expect to use this unbiased system for the discovery of novel genes controlling IH. Work will be conducted as described in three Specific Aims: (1) Identify chromosomal intervals containing genes modulating susceptibility and resistance to injury-induced neointimal hyperplasia (IH). We will use classic linkage studies to identify QTL and haplotype analysis across F2 mice to eliminate regions that are shared identical by descent. (2) Identify genes and molecular pathways mediating responsiveness to carotid artery injury using genome wide association studies. We will use a mouse diversity panel of ~100 inbred strains for which genotypes are already known and obtain IH phenotypes for association studies. (3) Validate and determine functions for potential candidate genes controlling IH. Candidate genes discovered in Aims 1 and 2 will be studied further here. Such studies will include identification of cell type(s) involved in expression, characterization of molecular functions in cultured cells, and development of appropriate genetically engineered mice. Overall, the strengths of this proposal include: (a) the novelty of the topic; (b) outstanding research team; (c) currently existing QTL for IH; and (d) strong preliminary data identifying a candidate gene with potential IH-modulating activity which demonstrates the utility of our approach. Further, the health topic is of high significance as tens of thousands of individuals are affected by vascular injury each year. PUBLIC HEALTH RELEVANCE: Smooth muscle cell (SMC) accumulation and extracellular matrix deposition in the intima are major characteristics of neointimal hyperplasia (IH) which occurs frequently following all forms of vascular reconstruction, including stenting, angioplasty, endarterectomy and vein grafts. It is our goal to identify biomarkers to assess risk of developing IH and molecular mediators for the development of therapies to treat susceptible vessels. This will be done using genetic approaches.