Molecular Mechanisms of Morphogen Gradient Formation

描述（由申请人提供）：形态发生素是在不同浓度和信号阈值下指定不同细胞命运的分子。这些“形状生成”分子提供了在组织组装期间生成图案的基本机制。骨形态发生蛋白（BMP）、Wnt和Hedgehog生长因子家族的成员，长期以来被认为是发育模式所必需的，并参与许多疾病过程，也表现为形态发生素。因此，深入了解组织是如何组装和修复的，需要深入了解形态发生梯度建立和维持的分子机制。 虽然已经确定硫酸乙酰肝素蛋白聚糖（HSPG）影响由形态发生素指定的图案化事件，但直到最近才认识到HSPG控制形态发生素梯度本身。磷脂酰肌醇蛋白聚糖是已知影响从人类到线虫的生长控制和模式的完整膜蛋白聚糖家族。果蝇蛋白聚糖Dally和Dally-like（Dlp）在翅膀发育过程中控制着形态发生因子Decapentaplegic（Dpp）（一种BMP 4同源物）和Wingless（Wg）的分布。我们提出了一个详细的生物物理和分子遗传学分析Dally和Dlp如何控制形态梯度。这些研究包括平行实验测量这些蛋白聚糖与形态发生素和形态发生素受体的分子相互作用，沿着体内分析它们对发育中的翅膀中的形态发生素分布、信号传导和周转的影响。Dally和Dlp在影响Dpp和Wg分布的能力方面表现出定性和定量差异，我们希望了解这些差异的分子基础。总之，我们提出了以下目标：目标1：使用提供动力学和亲和力数据的各种生物物理测量来确定Dally和Dlp与形态发生素和形态发生素受体的物理相互作用;目标2：比较Dally和Dlp在体内影响形态发生素信号传导和分布的差异活性以及这些活性的结构基础;目标3：测量Dally和Dlp对体内形态发生运动和转换的影响。

DESCRIPTION (provided by applicant): Morphogens are molecules that specify different cell fates at distinct concentration and signaling thresholds. These "form generating" molecules provide a fundamental mechanism of generating pattern during tissue assembly. Members of the bone morphogenetic protein (BMP), Wnt, and Hedgehog families of growth factors, long known to be essential for developmental patterning and involved in many disease processes, also behave as morphogens. An in depth understanding of how tissues are assembled and repaired, therefore, requires insight into the molecular mechanism of morphogen gradient establishment and maintenance. While it has established that heparan sulfate proteoglycans (HSPGs) affect patterning events specified by morphogens, only recently has it been appreciated that HSPGs control morphogen gradients per se. Glypicans are a family of integral membrane proteoglycans known to affect growth control and patterning from humans to nematodes. Two Drosophila proteoglycans, Dally and Dally-like (Dlp), have been shown to control the disposition of the morphogens, Decapentaplegic (Dpp), a BMP4 homolog, and Wingless (Wg), during wing development. We propose a detailed biophysical and molecular genetic analysis of how Dally and Dlp control morphogen gradients. These studies include parallel experiments measuring the molecular interactions of these proteoglycans with morphogens and morphogen receptors, along with in vivo analysis of their effects on morphogen distributions, signaling and turnover in the developing wing. Dally and Dlp show qualitative and quantitative differences in their capacity to affect Dpp and Wg distribution and we wish to understand the molecular basis of these differences. In sum, we propose the following objectives: Aim 1: Determine the physical interaction of Dally and Dlp with morphogens and morphogen receptors using a variety of biophysical measures that provide kinetic and affinity data; Aim 2: Compare the differential activities of Dally and Dlp in affecting morphogen signaling and distribution in vivo and the structural basis of those activities; Aim 3: Measure the effects of Dally and Dlp on morphogen movement and turnover in vivo.