Transmembrane Proteolytic Induction and Thoracic Aneurysms

摘要 心血管内细胞外基质破坏的一个戏剧性的临床例子 系统导致的毁灭性疾病过程是胸主动脉瘤(TAAs)。外科手术 重建/血管内介入治疗对TAA是可能的，但本身就很高。 风险和不影响驱动这一毁灭性疾病的潜在途径。这个实验室 和其他人已经证明了一种特定的蛋白水解酶，基质 金属蛋白酶(MMPs)在TAAs患者中升高。利用小鼠TAA模型 由该实验室开发的TAA进展之间的因果关系被证明 和基质金属蛋白酶的诱导/激活状态。然而，目前仍不清楚基质金属蛋白酶的类型和类型。 导致这些ECM改变，并有助于TAA的进展。我们最近发现， 一种独特的基质金属蛋白酶，膜型1(MT1-MMP)随着TAA的进展而上调，并且是 伴随着细胞外基质结构的丧失、间质血管纤维化和胸廓转位 主动脉成纤维细胞转化为肌成纤维细胞表型。我们的新结果证实了MT1-MMPs 切割潜伏的转化生长因子-β(TGF)结合蛋白-1(LTBP-1)，它将在 转而增强这一潜在的促纤维化信号通路的信号。因此，这一点的中心假设 研究表明，MT1-MMPs的诱导对TAAS的自然发展具有双相作用。 方式-由增强的ECM蛋白分解引起的启动-以及通过改变的成纤维细胞进行 表型和异常胶原沉积，这是一个MT1-基质金属蛋白酶/转化生长因子驱动的过程。这 假说将通过以下具体目标来解决：(1)通过转基因减少 和MT1-基质金属蛋白酶的扩增，证实早期诱导MT1-基质金属蛋白酶主要引起 定位和放大的基质金属蛋白酶的蛋白水解性反应，并启动TAA，而延长的MT1- 基质金属蛋白酶的诱导通过LTBP-转化生长因子机制导致促纤维化信号的增强 维持ECM重塑和TAA进展。(2)使用RNA干扰(SiRNA)，演示 在TAA进展中MT1-基质金属蛋白酶启动子活性的早期诱导导致净扩增 基质金属蛋白酶的蛋白降解活性和细胞外基质结构完整性的丧失。(3)建立延长的MT1-MMPs 诱导引起主动脉成纤维细胞表型转换，从而选择性靶向成纤维细胞 特异性的MT1-MMP会直接延缓TAA的进展。这些研究将确定 跨膜蛋白分解途径有助于TAA的繁殖，从而提供新的见解 为这种潜伏的和临床的疾病开发诊断和治疗策略 毁灭性的疾病。

Abstract A dramatic clinical example of where disruption of the extracellular matrix within the cardiovascular system leads to a devastating disease process is thoracic aortic aneurysms (TAAs). Surgical reconstruction/endovascular interventions are possible for TAAs, but are in and of themselves high risk and do not affect the underlying pathways which drive this devastating disease. This laboratory and others have demonstrated that a specific cassette of proteolytic enzymes, the matrix metalloproteinases (MMPs), are increased in patients with TAAs.Using a murine TAA model developed by this laboratory, a cause-effect relationship was demonstrated between TAA progression and MMP induction/activational states. However, it remains unclear how and which MMP types are causative to these ECM changes and contribute to TAA progression. We have recently identified that a unique MMP, membrane type-1 (MT1-MMP) was upregulated with TAA progression and was accompanied by a loss in ECM architecture, interstitial vascular fibrosis, and a switch of thoracic aortic fibroblasts to a myofibroblast phenotype. Our new results have established that MT1-MMP cleaves the latent transforming growth factor-beta (TGF) binding protein-1 (LTBP-1), which would in turn enhance signaling of this potent profibrotic signaling pathway. Thus, the central hypothesis of this study is that the induction of MT1-MMP contributes to the natural history of TAAs in a bi-phasic manner- initiation due to enhanced ECM proteolysis, - and progression through an altered fibroblast phenotype and abnormal collagen accumulation which is an MT1-MMP/TGF driven process. This hypothesis will be addressed through the following specific aims: (1) Through transgenic reduction and amplification of MT1-MMP, establish that early induction of MT1-MMP primarily causes a localized and amplified MMP proteolytic response and initiates the TAA, whereas prolonged MT1- MMP induction causes heightened profibrotic signaling through an LTBP-TGF mechanism thereby sustaining ECM remodeling and TAA progression. (2) Using RNA interference (siRNA), demonstrate the early induction of MT1-MMP promoter activity in TAA progression results in a net amplification of MMP proteolytic activity and a loss of ECM structural integrity. (3) Establish that prolonged MT1-MMP induction causes a phenotypic switch in aortic fibroblasts, whereby selective targeting of fibroblast specific MT1-MMP will directly attenuate TAA progression. These studies will establish how a transmembrane proteolytic pathway contributes to TAA propagation and thereby provide new insights for the development of diagnostic and therapeutic strategies for this insidious and clinically devastating disease.