Musculoskeletal growth and homeostasis: does extracellular fibrillin matrix regulate Notch signaling components?

项目摘要 FBN 1（原纤蛋白-1基因）的常染色体显性突变会导致马凡氏综合症以及 肢端发育不良如Weill-Marchesani综合征、胶状体发育不良和肢端微 发育不良这些遗传性疾病提供了证据表明，Escherin-1控制肌肉骨骼生长， 体内平衡然而，目前还不清楚为什么FBN 1中的大多数突变会导致高身材，蜘蛛状指， 关节活动过度，肌肉组织差（马凡氏综合征的典型特征），而其他突变， FBN 1导致身材矮小、短指、关节僵硬和肌肉发达（典型）的相反特征。 肢端发育不良）。由于纤维蛋白靶向并隔离生长因子， 形态发生蛋白（BMP）和大的潜在TGFβ复合物，阴阳肌肉骨骼特征 在原纤维蛋白病被认为反映了不同的影响突变的生长因子。在这方面， 在时间和空间上仍有多种机制有待阐明。这项工作的长期目标是 为了了解在出生后，细胞与生长因子-1的相互作用如何协调生长因子信号传导， 肌肉骨骼生长和疾病的发病机制。 本申请的短期目标是检验以下假设： 和Notch信号传导组分是出生后肌肉骨骼生长和体内平衡所必需的。 生物化学数据表明，Notch蛋白-1与Notch信号传导组分结合的亲和力与那些与Notch信号传导组分结合的亲和力相似。 针对缺口-锯齿相互作用进行测量。因为Notch信令的传统概念是基于 一个细胞上的Notch受体和一个细胞上的Notch配体（如Jagged或Delta）之间的细胞-细胞相互作用 我们的研究结果显示了Notch信号成分和Notch蛋白之间的相互作用， 细胞外基质分子，是真正的突破性的。为了确定这些相互作用的体内影响， 我们将使用Fbn 1靶向小鼠，其中Notch信号传导组分的结合位点已被删除。 该R21应用是“探索性/开发性”的，因为它将探索/开发我们令人兴奋的体外 Notch和Notch信号成分之间相互作用的发现。这些相互作用将在 在一种新的小鼠模型中体内，该模型可用于未来的进一步优势。我们期待成功 完成我们提出的研究将为Notch的细胞外控制打开一扇新的大门 发信号。此外，我们期望产生具有肌肉骨骼表型的纯合子小鼠模型 与在杂合子人类中发现的那些相关（例如，缩短的长骨，脊柱后凸/脊柱侧凸， 异常肌肉组织），但以夸张的形式，特别是有用的开始调查的分子 导致这些表型的相互作用。在未来，科学界的其他人将拥有 有机会阐明在各种宿主中，Notch基质如何参与Notch信号传导的控制。 空间和时间背景。

PROJECT SUMMARY Autosomal dominant mutations in FBN1, the gene for fibrillin-1, cause the Marfan syndrome as well as the acromelic dysplasias such as Weill-Marchesani syndrome, geleophysic dysplasia, and acromicric dysplasia. These genetic disorders provide evidence that fibrillin-1 controls musculoskeletal growth and homeostasis. However, it is unknown why most of the mutations in FBN1 cause tall stature, arachnodactyly, hypermobile joints, and poor musculature (typical features of the Marfan syndrome) while other mutations in FBN1 result in the opposite features of short stature, brachydactyly, stiff joints, and hypermusculature (typical of the acromelic dysplasias). Because fibrillins target and sequester growth factors such as Bone Morphogenetic Proteins (BMPs) and the large latent TGFβ complexes, the yin yang musculoskeletal features in the fibrillinopathies are thought to reflect different effects of mutations on growth factors. Within this context, there remain multiple mechanisms to be elucidated in both time and space. The long-term goal of this work is to learn how cellular interactions with fibrillin-1 coordinate growth factor signaling during postnatal musculoskeletal growth and pathogenesis of disease. The short-term goal of this application is to test the hypothesis that novel interactions between fibrillin-1 and Notch signaling components are required for postnatal musculoskeletal growth and homeostasis. Biochemical data indicate that fibrillin-1 binds to Notch signaling components with affinities similar to those measured for Notch-Jagged interactions. Because conventional concepts of Notch signaling are based on cell-cell interactions between Notch receptors on one cell and Notch ligands (like Jagged or Delta) on an adjacent cell, our results showing interactions between Notch signaling components and fibrillin, an extracellular matrix molecule, are truly ground-breaking. To determine the in vivo impact of these interactions, we will use Fbn1 targeted mice in which the binding site for Notch signaling components has been deleted. This R21 application is “exploratory/developmental” in that it will explore/develop our exciting in vitro findings of interactions between fibrillin and Notch signaling components. These interactions will be tested in vivo in a novel mouse model which can be used to further advantage in the future. We expect that successful completion of our proposed studies will open the door to a new paradigm for extracellular control of Notch signaling. In addition, we expect to generate homozygous mouse models with musculoskeletal phenotypes related to those found in heterozygous humans (for example, shortened long bones, kyphosis/scoliosis, abnormal musculature), but in exaggerated form, and especially useful to begin investigations of molecular interactions that cause these phenotypes. In the future, others in the scientific community will have the opportunity to elucidate how fibrillin matrix participates in the control of Notch signaling in a host of various spatial and temporal contexts.