Discovery and analysis of genes that govern axon guidance in the developing nervous system

神经系统的功能依赖于神经元的模式发育和突触连接的控制建立。发育中的神经元的轴突被指导性线索引导到合适的目标区域，然后在那里选择正确的突触伙伴。发生这种情况的分子和细胞机制尚不完全清楚。在这个发现基金中，我们将利用果蝇的遗传研究来了解轴突是如何被这些线索引导的，以及它们如何区分合适的目标和不合适的目标。这是发育神经生物学的核心问题，也是果蝇作为模型系统的理想选择。尽管过去取得了成功，但果蝇的前向基因筛查可能受到技术挑战和基因冗余的限制，这些冗余模糊了突变表型的检测。这些限制无疑留下了许多有待描述的基因和分子途径。在另一种创新的方法中，我们使用基因错误表达系统来识别影响轴突引导的基因和分子途径。我们最近报道了一项筛选结果，其中我们确定了42种能够影响轴突引导的候选基因，这些候选基因会导致一系列影响，从轴突亚群的错误投射到严重的神经系统紊乱。在这个发现基金中，我们的总体假设是，在我们的筛选中发现的基因特征将揭示控制轴突引导的新分子途径。我们提出了三个主要的研究目标。首先，我们将明确确定导致所观察到的错误表达表型的基因，从而发现可能在轴突引导中起作用的分子（目的1）。其次，我们将确定这些基因是否在发育中的神经元中表达，我们将在体内使用功能丧失方法来确定这些基因是否需要轴突引导（目的2）。最后，我们将研究选择的基因影响轴突引导的机制（目的3）。我们的总体目标是在分子水平上解释神经系统在发育过程中组织的原理，并为神经科学研究生提供世界一流的培训环境。

Nervous system function relies upon patterned development of neurons and controlled establishment of synaptic connections. Axons of developing neurons are guided by instructive cues to their appropriate target areas, where they then select their correct synaptic partners. The molecular and cellular mechanisms by which this occurs are incompletely understood. In this Discovery Grant we will use genetic studies in the fruit fly Drosophila to understand how axons are guided by these cues and how they distinguish appropriate targets from inappropriate ones. This is a central issue in developmental neurobiology, and one for which Drosophila is ideally suited as a model system. Despite past successes, forward genetic screening in Drosophila can be limited by technical challenges and by genetic redundancies that obscure the detection of mutant phenotypes. Such limitations have undoubtedly left many genes and molecular pathways remaining to be described. In an alternative and innovative approach, we have used a gene misexpression system to identify genes and molecular pathways that can influence axon guidance. We recently reported the results of a screen in which we identified 42 candidates capable of influencing axon guidance, causing a range of effects from misprojections of axon subsets to severe nervous system disorganization. In this Discovery Grant, our overall hypothesis is that characterization of genes found in our screen will reveal new molecular pathways controlling axon guidance. We propose three main research Aims. First, we will unequivocally identify the genes responsible for observed misexpression phenotypes, and thereby discover molecules with the potential to act in axon guidance (Aim 1). Second, we will determine whether these genes are expressed in developing neurons and we will use loss-of-function approaches in vivo to determine if these genes are required for axon guidance (Aim 2). Finally, we will investigate the mechanisms by which selected genes affect axon guidance (Aim 3). Our overall goal is to explain at a molecular level the principles upon which nervous systems are organized during development, and to provide a world-class training environment for graduate students in neuroscience.