Intracellular Signaling in Thoracic Aortic Aneurysms

描述（由申请方提供）：胸升主动脉瘤（ATAA）的形成是一个受细胞和细胞外机制影响的多因素过程。这些机制通过细胞外基质（ECM）的重塑导致血管环境的改变; ECM是直接涉及主动脉扩张和动脉瘤发展的不变特征。ATAA有许多病因。最近的数据表明，这些ATAA亚型之间存在差异，主动脉壁内的蛋白水解平衡，最显着的基质金属蛋白酶（MMP）。然而，调控这些差异的上游信号介质的概况仍然未知。主动脉血管壁内的细胞内信号传导事件导致细胞外基质蛋白组分的产生和分泌的动态变化，包括驱动重塑过程的修饰酶。其中，肿瘤坏死因子-1（TNF-1）和转化生长因子-2（TGF-2）信号传导家族与蛋白酶活化和ECM重塑有关。此外，关键的细胞中间体如蛋白激酶C（PKC）和核因子：B（NF：B）可作为这些和其他在ATAA发育期间起作用的细胞内信号传导途径的整合剂。因此，使用从多个机构获得的切除的人主动脉组织标本（n=274）的大型独特库，本项目提案的主要目标旨在生成原理证明，即关键细胞内信号传导通路的激活是诱导异常血管重塑和随后ATAA发展的基本先决条件。这将通过使用路径聚焦PCR阵列技术测量ATAA样本子集中关键信号中间体的相对mRNA表达水平来实现。这些研究将鉴定在两个关键信号转导途径（TGF-2、TNF-1）和围绕两个关键信号中间体（PKC、NF：B）中表达长期改变的基因。然后，使用定量免疫印迹技术，在人ATAA标本和对照品的完整库（n=274）中测定PCR阵列分析中表达升高的基因的相对蛋白量。总之，这些研究将确定在ATAA发展过程中可能起作用的长期升高的信号分子。这些数据将为随后的R 01资助提交奠定基础，这些资助提交集中在假设驱动的研究上，旨在阐明这些信号通路/分子在ATAA发展中的功能作用。通过推进我们对ATAA形成和进展的信号事件的理解，在这些关键信号通路中识别治疗靶点可能会导致新的诊断和治疗策略。公共卫生相关性胸主动脉瘤疾病是一种毁灭性的疾病过程，由于缺乏动脉瘤特异性血管病学，通常会导致死亡。目前没有有效的非手术临床治疗方案可用于治疗胸动脉瘤疾病。本提案定义了将鉴定慢性升高的信号分子的研究，这些信号分子可作为开发新的诊断和治疗策略的特异性靶点。

DESCRIPTION (provided by applicant): The formation of ascending thoracic aortic aneurysms (ATAA) is a multifactorial process influenced by both cellular and extracellular mechanisms. These mechanisms lead to alterations in the vascular environment through remodeling of the extracellular matrix (ECM); an invariant feature directly implicated in aortic dilatation and aneurysm development. ATAAs have numerous etiologies. Recent data suggests that dissimilarities exist between these ATAA subtypes with regard to the proteolytic balance within the aortic wall, most notably for the matrix metalloproteinases (MMPs). However, the profiles of the upstream signaling mediators regulating these differences remain unknown. Intracellular signaling events within the aortic vascular wall result in dynamic changes in the production and secretion of extracellular matrix protein components, including the modifying enzymes that drive the remodeling process. Of these, the tumor necrosis factor-1 (TNF-1) and transforming growth factor-2 (TGF-2) signaling families are implicated in protease activation and ECM remodeling. Furthermore, critical cellular intermediates like protein kinase C (PKC) and nuclear factor :B (NF:B) may function as integrators of these and other intracellular signaling pathways which are operative during ATAA development. Therefore, using a large unique bank of resected human aortic tissue specimens (n=274), obtained from multiple institutions, the primary objectives of this project proposal are designed to generate proof of principle that the activation of key intracellular signaling pathways is a fundamental prerequisite for the induction of aberrant vascular remodeling and the consequent development of ATAA. This will be accomplished by measuring relative mRNA expression levels of key signaling intermediates in a subset of ATAA specimens using pathway-focused PCR array technology. These studies will identify genes that are chronically altered in expression, in two key signal transduction pathways (TGF-2, TNF-1), and surrounding two key signaling intermediates (PKC, NF:B). Then using quantitative immunoblotting techniques, relative protein amounts of the genes with elevated expression, from the PCR array analysis, will be determined in the full bank of human ATAA specimens and controls (n=274). Together, these studies will determine chronically elevated signaling molecules that are likely to be operative during ATAA development. These data will formulate the basis for subsequent R01 grant submissions centered on hypothesis-driven studies aimed at elucidating the functional role of these signaling pathways/molecules in ATAA development. By advancing our understanding of the signaling events contributing to ATAA formation and progression, identification of therapeutic targets within these key signaling pathways could result in novel diagnostic and therapeutic strategies. PUBLIC HEALTH RELEVANCE Thoracic aortic aneurysm disease is a devastating disease process which often results in death because of a lack of aneurysm specific symptomology. There are currently no effective, non-surgical clinical treatment protocols available to treat thoracic aneurysm disease. The present proposal defines studies that will identify chronically elevated signaling molecules which may serve as aneurysm-specific targets for the development of novel diagnostic and therapeutic strategies.