Determining the Role of Extracellular Matrix Compliance and Composition on Facial Morphogenesis

项目摘要 面部形态发生涉及面部原基的定向生长，直到它们并置并融合在一起 另目前，原基的生长被认为主要是由大量组织移位驱动的 由间充质组织中的增殖梯度引起。然而，我们的实验室和其他人发现， 诸如定向细胞迁移和上皮引导生长的机制也可能起作用。在 肢芽，由外胚层产生的张力已经显示出指导细胞定向和生长， 并且如果不结合 定向的细胞行为。我们的实验室先前已经表明，面部的间充质细胞是极化的， 成纤维细胞生长因子（FGF）信号传导的激活会破坏这种极性，同时导致异常生长 原基的一部分细胞周围的细胞外基质（ECM）提供了细胞生长所需的结构支架， 产生并引导力通过组织，并且上皮中的ECM可以引导或限制区域性生长。 我假设ECM通过成分的区域差异指导面部的形态发生， 合规我将以两个主要目标来检验这个假设。在第一个目标中，我将研究FGF信号如何影响 面部原基中ECM的物理性质和细胞组织。我将定量地绘制 用共聚焦显微镜和原子力测量整个面部的ECM蛋白组成和ECM顺应性 显微镜，然后将这些措施的区域差异与面部形状变化联系起来。这一目标将阐明 成纤维细胞生长因子的分子信号通过ECM控制形态发生的机制 和细胞组织。在第二个目标中，我将直接通过改变组织的顺应性来增加或减少组织的顺应性。 胶原交联，然后重复与第一个目的相同的分析。第二个目标将决定是否ECM 刚性直接引导生长，而间充质被动地顺应其周围，或者如果存在反馈， ECM和积极重塑环境以指导生长的细胞之间的关系。面部原基的破坏 导致面部裂开了解ECM在定向增长中的作用对于以下方面很重要： 了解面部出生缺陷的病因。

PROJECT SUMMARY Facial morphogenesis involves directed outgrowth of the facial primordia until they appose and fuse with one another. Currently, outgrowth of primordia is considered to be driven primarily by bulk tissue displacement caused by proliferation gradients in the mesenchymal tissue. However, our lab and others have found that other mechanisms, such as directed cellular migration and epithelium guided growth, likely contribute as well. In the limb bud, tensile forces generated by the ectoderm have been shown to direct cellular orientation and growth, and proliferation gradients across the limb bud cannot accurately model morphogenesis without incorporating directed cellular behaviors. Our lab has previously shown that mesenchymal cells in the face are polarized and that activation of fibroblastic growth factor (FGF) signaling disrupts this polarity while causing aberrant outgrowth of the primordium. The extracellular matrix (ECM) around cells provides the structural scaffolding required to generate and guide force through tissue, and the ECM in the epithelium may guide or constrain growth regionally. I hypothesize that the ECM directs morphogenesis in the face via regional differences in composition and compliance. I will test this hypothesis with two main aims. In the first aim I will examine how FGF signaling affects ECM physical properties and cellular organization in the facial primordium. I will quantitatively map the composition of ECM proteins and ECM compliance across the face with confocal microscopy and atomic force microscopy, then relate regional differences in these measures to facial shape change. This aim will elucidate mechanisms by which molecular signaling of fibroblastic growth factor controls morphogenesis through the ECM and cellular organization. In the second aim, I will increase or decrease tissue compliance directly by altering collagen crosslinking, then repeat the same analyses as the first aim. The second aim will determine if ECM stiffness directs outgrowth directly while the mesenchyme passively conforms around it, or if there is feedback between ECM and cells that actively remodel the environment to direct growth. Failure of the facial primordium to appose and fuse leads to facial clefting. Understanding the role of ECM in directional growth is important for understanding the etiology of birth defects in the face.