Homeostasis and Repair in the Marfan Aorta

该计划项目的总体目标是贡献新的知识，这将导致马凡氏综合症未来疗法的发展。拟议的研究将导致更好地理解生长因子信号在MFS中的作用，以及将影响未来治疗的细胞和时间靶向的新知识。项目3将使用Fbn1突变的主动脉疾病小鼠模型来研究三个特定的目标。在目标1中，我们将测试不适当地隔离大的潜在的转化生长因子β复合体是否是导致马凡综合征主动脉疾病发生和发展的主要机制。为了测试这种疾病的机制，我们建立了一个新的小鼠模型，在该模型中，纤毛素-1中介导与潜在的转化生长因子β结合蛋白-1和-4结合的位置已经被删除。在目标2中，我们将测试主动脉疾病的主要机制是否发生在主动脉的平滑肌中层，以及出生后突变的纤维蛋白-1的合成是否足以导致主动脉疾病。为了研究这些假说，我们在小鼠体内产生了一种新的“条件性”截断突变。拟议的研究将导致关于涉及主动脉VSMC对突变的纤维蛋白-1反应的关键细胞过程的新信息。对于ECM在体内对器官特定细胞间隔的局部影响，以及局部ECM环境是否以及如何促进器官间隔之间的细胞信号传递，人们知之甚少。AIM 2中提出的研究将剖析局部突变的ECM环境对主动脉VSMC病理生理学行为的影响。纤维蛋白-1在主动脉内稳态中的作用，虽然很重要，但还不是很清楚。一种可能性是，在发育过程中产生的纤维蛋白-1在动态平衡期间是必需的。另一种可能性是在动态平衡过程中需要纤维蛋白-1的合成。Aim 2的研究将确定突变的纤维蛋白-1在出生后的表达是否以及在多大程度上与主动脉疾病有关。这些研究将更好地确定有效治疗方案的机会之窗。在目标3中，我们将测试BMP信号是否在主动脉疾病的小鼠模型中异常激活，这种激活何时发生，以及阻断异常的BMP信号是否可以预防小鼠模型的主动脉疾病。这些机制的拟议研究将包括主动脉根部的形态和超微结构检查、定量RT-PCR、免疫化学研究、细胞培养研究和体内治疗试验。

The overall goal of the Program Project is to contribute new knowledge that will lead to the development of future therapies for the Marfan syndrome. Proposed investigations will result in a better understanding of the roles of growth factor signaling in MFS and new knowledge that will impact cellular and temporal targeting of future therapies. Project 3 will use Fbn1 mutant mouse models of aortic disease in order to investigate three specific aims. In Aim 1, we will test whether inappropriate sequestration of the large latent TGF beta complex is the major mechanism responsible for the initiation and progression of aortic disease in the Marfan syndrome. In order to test this mechanism of disease, we have generated a new mouse model in which the site in fibrillin-1 that mediates binding to the latent TGF beta binding proteins -1 and -4 has been deleted. In Aim 2, we will test whether the major mechanisms of aortic disease take place in the smooth muscle media of the aorta and whether postnatal synthesis of mutant fibrillin-1 is sufficient to cause aortic disease. To investigate these hypotheses, we have generated a new "conditional" truncating mutation in fibrillin-1 in mice. Proposed investigations will lead to new information on key cellular processes involved in aortic VSMC responses to mutant fibrillin-1. Little is known about the in vivo local effects of ECM on specific cellular compartments of an organ and whether and how the local ECM environment contributes to cellular signaling between compartments in an organ. Studies proposed in Aim 2 will dissect the effects of the local mutant ECM environment on VSMC behavior in aortic pathophysiology. The role of fibrillin-1 during aortic homeostasis, while clearly important, is not well understood. One possibility is that fibrillin-1, produced during development, is required during homeostasis. Another possibility is that fibrillin-1 synthesis is required during homeostasis. Studies in Aim 2 will determine whether and to what extent postnatal expression of mutant fibrillin-1 contributes to aortic disease. These studies will better define the window of opportunity for effective therapeutic protocols. In Aim 3, we will test whether BMP signaling is abnormally activated in mouse models of aortic disease, when this activation occurs, and whether blocking abnormal BMP signaling will prevent aortic disease in mouse models. Proposed investigations of these mechanisms will include morphological and ultrastructural examinations of the aortic root, quantitative RT-PCR, immunochemical studies, cell culture studies, and in vivo therapeutic trials