Molecular Dissecfion of NF1 Vasoocclusive and Aneurysm Disease

神经纤维瘤病是由NFL肿瘤抑制基因突变引起的，NFL肿瘤抑制基因编码神经纤维蛋白。血管疾病是NF1患者发病率和死亡率的一个未得到充分认识的来源。NFL患者会出现血管病变，包括动脉闭塞和动脉瘤。尽管有这些观察，但神经纤维蛋白在体内协调内皮细胞(ECs)、血管平滑肌细胞(VSMCs)和骨髓来源细胞(BMDCs)之间复杂的相互作用以维持血管壁稳态的功能尚不完全清楚。本申请中概述的研究将直接解决这种缺乏知识的问题，对于了解NF1血管疾病的发病机制、合理设计实验疗法以及开发在心血管突然失代偿之前预测NF1患者早期血管疾病的新生物标记物是必不可少的。我们开发了动脉闭塞和动脉瘤形成的新型基因工程小鼠模型，它概括了人类NFL的表型。利用谱系限制性转基因小鼠去除内皮细胞、VSMCs和BMDCs中的NFL，我们提供了初步的数据支持Nf1+/-巨噬细胞和细胞外基质蛋白骨桥蛋白上调是NFL动脉闭塞的主要效应因素的假说。在建立了第一个NFL动脉瘤的动物模型后，我们还初步支持了神经纤维蛋白缺乏的VSMCs、ECs或BMDCs以及骨桥蛋白上调导致NFL动脉瘤形成的假说。因此，具体目标是：(1)利用谱系受限转基因小鼠，我们将特异性地去除髓系细胞中的NFL，以验证NFL在单核/巨噬细胞中的杂合失活直接导致Nf1+/-小鼠新生内膜形成的假说(2)通过使用谱系受限转基因小鼠和骨髓移植，我们将确定哪种特定细胞系在体内导致动脉瘤形成增加的关键因素。(3)为了验证骨桥蛋白上调促进Nf1+/-小鼠体内新生内膜和动脉瘤形成的假说，我们将OPN-/-和Nf1+/-小鼠杂交，产生复合突变体。

Neurofibromatosis results from mutations in the NFl tumor suppressor gene, which encodes the protein neurofibromin. Vasculopathies constitute an under-recognized source of morbidity and mortality in NF1 patients. NFl patients develop vascular lesions including arterial occlusions and aneurysms. Despite these observations, the function of neurofibromin in coordinating the complex interactions between endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and bone marrow derived cells (BMDCs) for maintainance of blood vessel wall homeostasis in vivo is incompletely understood. Studies outlined in this application will directly address this lack of knowledge and are imperative for understanding the pathogenesis of NF1 vascular disease, rational design of experimental therapeutics, and development of novel biomarkers to predict early vascular disease in NF1 patients prior to sudden cardiovascular decompensation. We developed novel genetically engineered mouse models of both arterial occlusion and aneurysm formation, which recapitulates the human NFl phenotype. Utilizing lineage restricted transgenic mice to ablate Nfl in ECs, VSMCs and BMDCs, we provide preliminary data to support that hypothesis that Nf1 +/- macrophages and upregulation of extracellular matrix protein osteoponfin are the primary effectors of NFl arterial occlusion. Having established the first animal model of NFl aneurysms, we also provide preliminary to support the hypothesis that either neurofibromin deficient VSMCs, ECs or BMDCs and upregulation of osteoponfin orchestrate NFl aneurysm formation. Therefore the specific aims are: (1) Using lineage-restricted transgenic mice, we will specifically ablate Nfl in myeloid cells to test the hypothesis that heterozygous inactivation of Nfl in monocyte/macrophages directly leads to increased neointima formation in Nf1 +/- mice (2) Using both lineage-restricted transgenic mice and bone marrow transplantation to specifically delete one allele of Nf1 in either the VSMCs, ECs or BMDCs, we will determine which specific cell lineage is critical for increased aneurysm formation in vivo. (3) To test the hypothesis that upregulation of osteoponfin accelerates neointima and aneurysm formation in Nf1 +/- mice in vivo, we will intercross OPN -/- and Nf1 +/- mice to generate compound mutants.