Regulation of Wingless (Wg) Signaling and Morphogen Gradient Formation

描述（由申请人提供）：本提案的长期目标是阐明在发育过程中调节无翼（Wg）形态素梯度和信号传导的分子机制。果蝇Wg编码Wnt家族的进化保守糖蛋白。异常的Wg/Wnt信号活动是许多人类发育障碍和多种癌症的基础。因此，阐明Wg/Wnt信号通路将为人类相关疾病的发病机制提供新的认识。Wg在许多发育过程中起着关键的调节作用。在多种发育环境下，Wg可以作为一种短距离组织者和远距离形态形成因子，以浓度依赖的方式作用于几个细胞直径之外的组织场。虽然在过去的15年中，Wg/Wnt信号通路在其接收细胞中的成分已经被很好地表征，但对于成熟形式的Wg是如何合成、分泌并传输到其接收细胞以形成浓度梯度的仍然知之甚少。本应用的主要焦点是确定控制Wg蛋白分泌、运动及其随后分布的分子机制。这是一个持续支持的申请。在之前的资助期内，我们在果蝇中采用遗传和细胞生物学方法来研究硫酸肝素蛋白聚糖（HSPG）在Wg梯度形成及其信号传导活性中的作用。我们的研究结果确定了果蝇HSPGs Dally和Dally样（Dip）在Wg形态因子梯度形成中的重要作用。HSPGs Dally和Dip通过限制扩散机制控制了Wg形态原的运动。在下一个资助期内，我们将集中研究四个相关课题。首先，我们将确定孔隙在Wg分泌和棕榈酰化（Aim1）中的双重作用。其次，我们将研究逆转录物在Wg分泌和分布中的分子机制（目的2）。第三，我们将确定棕榈酰化控制Wg信号传导和分布（Aim3）的机制。最后，我们将剖析Notum调节Wg信号和分布（Aim4）的机制。总之，我们对HSPGs的遗传和生化分析将阐明HSPGs在调节Wg蛋白的形态梯度形成和信号传导中的作用，而Wg蛋白在发育过程和肿瘤发生中都起着重要作用。由于Wg信号转导途径在果蝇和人类之间是保守的，本项目的结果将为研究包括癌症在内的与Wg信号和HSPGs相关的疾病过程的机制提供新的见解。

DESCRIPTION (provided by applicant): The long-term goal of this proposal is to elucidate molecular mechanism(s) by which Wingless (Wg) morphogen gradient and signaling is regulated during development. Drosophila Wg encodes an evolutionary conserved glycoprotein of the Wnt family. Aberrant Wg/Wnt signaling activity underlies a number of human developmental disorders and contributes to a variety of cancers. Thus, elucidation of Wg/Wnt signaling pathway will provide new insights into the mechanisms of related human diseases. Wg acts as a critical regulator in many developmental processes. In a variety of developmental contexts, Wg can function as a short-range organizer and long-range morphogen that acts several cell diameters away to pattern a field of tissue in a concentration dependent manner. Although the components of Wg/Wnt signaling pathway in its receiving cells have been well characterized over the past 15 years, it remains poorly understood how the mature form of Wg is synthesized, secreted and travels to its receiving cells to form concentration gradient. The main focus of this application is to define the molecular mechanisms controlling Wg protein secretion, movement and its subsequent distributions. This is an application for continuing support. In the previous grant period, we have taken genetic and cell biology approaches in Drosophila to address the roles of heparan sulfate proteoglycans (HSPG) in Wg gradient formation and its signaling activity. Our results have established the essential roles of Drosophila HSPGs Dally and Dally-like (Dip) in Wg morphogen gradient formation. The HSPGs Dally and Dip controls Wg morphogen movement by a restrict diffusion mechanism. In the next grant period, we will focus our studies to address four related issues. First, we will determine the dual roles of Pore in Wg secretion and palmitoylation (Aim1). Second, we will examine the molecular mechanisms of retromer in Wg secretion and distribution (Aim 2). Third, we will determine the mechanisms by which palmitoylation controls Wg signaling and distribution (Aim3). Finally, we will dissect the mechanisms by which Notum modulates the Wg signaling and distribution (Aim4). Altogether, our genetic and biochemical analyses of HSPGs will elucidate the role of HSPGs in regulating morphogen gradient formation and signaling of Wg proteins that play major roles in both developmental processes and oncogenesis. Since Wg signaling transduction pathway is conserved between Drosophila and human, the outcomes of this project will clearly provide new insights into the mechanisms of the disease processes including cancers, which are associated with Wg signaling and HSPGs.