Intracellular Signaling in Thoracic Aortic Aneurysms

描述（由申请人提供）：升胸主动脉瘤（ATAA）的形成是一个多因素的过程，受细胞和细胞外机制的影响。这些机制通过细胞外基质（ECM）的重塑导致血管环境的改变；一个与主动脉扩张和动脉瘤发展直接相关的不变特征。ATAAs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水解平衡方面存在差异，最明显的是基质金属蛋白酶（MMPs）。然而，调节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 （TNF-1）和转化生长因子-2 （TGF-2）信号家族与蛋白酶激活和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）可能作为这些和其他在ATAA发育过程中起作用的细胞内信号通路的整合者。因此，使用从多个机构获得的大量独特的切除的人主动脉组织标本（n=274），本项目提案的主要目标旨在产生原理证明，即关键细胞内信号通路的激活是诱导异常血管重构和随后的ATAA发展的基本先决条件。这将通过使用途径聚焦PCR阵列技术测量ATAA标本子集中关键信号中间体的相对mRNA表达水平来完成。这些研究将确定在两个关键信号转导通路（TGF-2, TNF-1）和周围两个关键信号中间体（PKC, NF:B）中表达慢性改变的基因。然后使用定量免疫印迹技术，从PCR阵列分析中确定全库人类ATAA标本和对照（n=274）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慢性升高的信号分子。这些数据将为后续的R01基金申请奠定基础，这些研究以假设驱动的研究为中心，旨在阐明这些信号通路/分子在ATAA发展中的功能作用。通过加深我们对ATAA形成和进展的信号事件的理解，在这些关键信号通路中确定治疗靶点可能会导致新的诊断和治疗策略。胸主动脉瘤疾病是一种毁灭性的疾病，由于缺乏动脉瘤特异性的症状，常常导致死亡。目前还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。本提案定义了将识别慢性升高的信号分子的研究，这些信号分子可能作为开发新的诊断和治疗策略的动脉瘤特异性靶点。

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.