Molecular Basis of Tissue Interactions that Regulate Craniofacial Development

描述(由申请者提供)：我们第一轮资助的目标是研究调节颅面发育的组织相互作用的分子介质。我们专注于大脑在建立信号中心额鼻外胚层区(FEZ)中所起的作用，因为FEZ调节着上颌的花纹生长。我们的研究表明，大脑控制着FEZ的空间组织，然后FEZ产生独特的面部形态，包括沿着连续形态谱的疾病表型。我们的初步数据表明，大脑控制FEZ的空间组织是一种新的机制。这些数据还表明，FEZ是动态的，在面部发育过程中通过改变表达边界来调节多种形态发生过程。最后，面部发育过程中细胞对成纤维细胞生长因子信号的反应在很大程度上是未知的，我们的初步研究表明，基本的细胞过程是由成纤维细胞生长因子信号控制的。作为对成纤维细胞生长因子信号的响应，这些细胞行为参与调节面部的形态发生。总而言之，这些数据表明了面部原基的发育、整合和融合的机制。基于这些数据，我们假设来自大脑的SHH通过microRNAs在FEZ中诱导负反馈环路来控制面部形态发生，这有助于确定FEZ中ShH的结构域。然后，FEZ协调自己不断变化的表达结构域来控制形态发生过程，如间充质细胞的增殖、迁移和极化，这些过程驱动形成上颌的面部原基的生长和融合。我们将在三个具体目标上检验这一假设。首先，我们将检查这些微小RNA在多大程度上调节FEZ中Shh表达的空间组织，并验证可能的靶基因。其次，FEZ的形状随着时间的推移而变化，我们将确定Shh的新表达结构域在正中鼻突、鼻侧突和上颌突的生长和融合中所起的作用。第三，我们将研究成纤维细胞生长因子信号的下游靶标在通过这一途径调节细胞对信号的反应中所起的作用，我们还将研究Crouzon综合征的小鼠模型。这项研究的结果将有助于更全面地了解控制面部发育的机制，并将确定与唇腭裂等结构性疾病有关的可能致病机制。

DESCRIPTION (provided by applicant): The goal of our first cycle of funding was to examine the molecular mediators of tissue interactions that regulate craniofacial development. We focused on the role that the brain plays in establishing a signaling center, the Frontonasal Ectodermal Zone (FEZ), because the FEZ regulates patterned growth of the upper jaw. Our research revealed that the brain controls the spatial organization of the FEZ, which then produces unique facial morphologies including disease phenotypes that fall along a continuous spectrum of morphologies. Our preliminary data suggest a novel mechanism by which the brain controls the spatial organization of the FEZ. These data also indicate that the FEZ is dynamic and shifts expression boundaries to regulate multiple morphogenetic processes during facial development. Finally, cellular responses to Fgf signaling during facial development have been largely unknown, and our preliminary studies suggest that basic cellular processes are controlled by FGF signaling. In response to FGF signaling these cellular behaviors participate in regulating facial morphogenesis. Collectively, these data suggest mechanisms that are used for development, integration, and fusion of facial primordia. Based on these data, we hypothesize that SHH from the brain controls facial morphogenesis by inducing a negative feedback loop in the FEZ via microRNAs and this helps to define the domain of Shh in the FEZ. The FEZ then orchestrates its own changing expression domain to control morphogenetic processes such as proliferation, migration, and polarization of mesenchymal cells that drive growth and fusion of the facial primordia that form the upper jaw. We will test this hypothesis in three Specific Aims. First, we will examine the extent to which these micro RNAs regulate the spatial organization of Shh expression in the FEZ and validate putative target genes. Second, the FEZ changes shape over time, and we will determine the role that novel expression domains of Shh play during growth and fusion of the median nasal, lateral nasal, and maxillary processes. Third, we will examine the role that downstream targets of FGF signaling have in mediating the cellular response to signaling by this pathway, and we will examine a mouse model of Crouzon Syndrome. The results from this research will lead to a more comprehensive understanding of mechanisms that control facial development and will identify putative disease causing mechanisms related to cleft lip and palate among other structural disease.