The Wingless transduction pathway in synapse development

描述（由申请人提供）：该项目的长期目标是阐明果蝇新突触形成的信号机制。我们最近发现，分泌的糖蛋白Wingless （Wg）在果蝇的早期形态发生和模式形成中起着至关重要的作用，也是谷氨酸突触的基本组织者。在这个项目中，我们将使用遗传、分子和电生理策略来研究Wg通路促进突触形成的方式。在Aim 1中，我们将重点关注Wg受体dzzzzled2，以了解Wg转导如何影响成熟末端，以及突变体中突触两边的结构破坏是独立的还是需要前/逆行信号。在Aim 2中，电生理记录和染料摄取实验将探讨突触传递中的基本问题，如活跃区在胞外分泌中的作用，内腔/胞外分泌之间的关系，以及突触强度的补偿机制。最后，在Aim 3中，我们将使用遗传和酵母双杂交方法来确定突触发育过程中Wg激活的特定信号转导途径。特别是，我们将验证在突触处Wg激活非规范通路的假设。我们还将发现直接与Dfrizzled2结合的新蛋白，并可能将其靶向并聚集到突触位点。该实验将从根本上推进突触发育领域，通过表征分泌蛋白，这是建立活跃区和突触后特化所必需的。我们的发现也可能带来对哺乳动物突触发育的见解，因为这些苍蝇突触与哺乳动物中枢突触表现出令人着迷的分子保守程度。因此，我们通过操纵Wg通路的组成部分的结果对于破译许多神经病理学的潜在机制以及设计中风、创伤或疾病后修复神经系统损伤的策略可能是重要的。一个值得注意的例子是双相情感障碍，长期以来一直用锂治疗。最近的研究表明，锂的靶标之一是GSK3-8，这是Wg途径中的一个关键酶。我们发现Wg通路对突触发育至关重要，这可能为这种疾病提供新的见解。

DESCRIPTION (provided by applicant): The long-term goal of this project is to elucidate the signaling mechanisms underlying new synapse formation in the fruit fly Drosophila. We have recently discovered that the secreted glycoprotein Wingless (Wg), best known for its crucial role in early morphogenesis and pattern formation, is also a fundamental organizer of glutamatergic synapses in the fruit fly. In this project we will use genetic, molecular, and electrophysiological strategies to investigate the ways in which the Wg pathway promotes synapse formation. In Aim 1 we will focus on the Wg receptor - Dfrizzled2 - to discern how Wg transduction affects maturing terminals, and if the structural disruptions found on both sides of the synapse in mutants are independent or require antero/retrograde signaling. In Aim 2, Electrophysiological recordings and dye uptake experiments will probe fundamental questions in synaptic transmission such as the role of the active zone in exocytosis, the relationship between endo/exocytosis, and mechanisms for compensation of synaptic strength. Finally, in Aim 3 we will use genetic and yeast two-hybrid approaches to determine the specific signal transduction pathway activated by Wg during synapse development. In particular, we will test the hypothesis that at synapses Wg activated a non-canonical pathway. We will also uncover new proteins that bind directly to Dfrizzled2 and that may function to target and cluster it to synaptic sites. The proposed experiments will fundamentally advance the field of synapse development by characterizing a secreted protein, which is essential for setting up active zones and postsynaptic specializations. Our findings may also bring insights into mammalian synapse development, as these fly synapses show a tantalizing degree of molecular conservation with mammalian central synapses. Therefore our results with manipulating components of the Wg pathway could be important for deciphering the mechanisms underlying a number of neuropathologies, as well as to design strategies to repair nervous system damage after stroke, trauma, or disease. A notable example is the case of bipolar disorder, which has long been treated with lithium. Recent studies show that one of the targets for lithium is GSK3-8, a crucial enzyme in the Wg pathway. Our finding that the Wg pathway is essential for synapse development might provide new insights into this disease.