Intracellular Signaling in Thoracic Aortic Aneurysms

描述(由申请人提供)：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是一个不变的特征，直接与主动脉扩张和动脉瘤的发展有关。ATAA有多种病因。最近的数据表明，这些AtaA亚型在主动脉壁内的蛋白分解平衡方面存在差异，最显著的是基质金属蛋白酶(MMPs)。然而，调控这些差异的上游信号媒介的特征仍然未知。主动脉壁内的细胞内信号事件导致细胞外基质蛋白成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和转化生长因子-2信号家族参与了蛋白水解酶的激活和细胞外基质重塑。此外，关键的细胞中间体，如蛋白激酶C(PKC)和核因子：B(NF：B)，可能作为这些和其他细胞内信号通路的整合因子，在ATAA发育过程中发挥作用。因此，利用从多个机构获得的大量独特的人主动脉组织标本(n=274)，该项目提案的主要目标是产生原理证据，即激活关键的细胞内信号通路是诱导异常血管重塑和随后的ATA发展的基本前提。这将通过使用路径聚焦的聚合酶链式反应阵列技术测量Ataa样本子集中关键信号中间产物的相对mRNA表达水平来实现。这些研究将确定在两个关键的信号转导途径(转化生长因子-2，肿瘤坏死因子-1)以及围绕两个关键信号中间体(PKC，NF：B)的两个关键信号转导途径中长期表达变化的基因。然后利用定量免疫印迹技术，在全库的人类ATA样本和对照(n=274)中，从PCR阵列分析中确定表达上调的基因的相对蛋白量。总而言之，这些研究将确定在Ataa发育过程中可能起作用的慢性升高的信号分子。这些数据将为随后的R01拨款申请奠定基础，这些申请以假说驱动的研究为中心，旨在阐明这些信号通路/分子在Ataa发育中的功能作用。通过促进我们对Ataa形成和发展的信号事件的理解，识别这些关键信号通路中的治疗靶点可能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破坏性的疾病过程，由于缺乏动脉瘤的特异性症状而导致死亡。目前还没有有效的、非手术的临床治疗方案来治疗胸主动脉瘤疾病。目前的提案定义了一些研究，这些研究将确定慢性升高的信号分子，这些分子可能作为动脉瘤的特异性靶点，用于开发新的诊断和治疗策略。

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.