Mechanisms of the programmed cell death of post-embryonic neurons

 描述(申请人提供)：神经元的程序性细胞死亡(PCD)是通过消除陈旧的神经元来建立功能性中枢神经系统(CNS)的非常重要的发育事件。在变态发育过程中，脊椎动物和无脊椎动物的某些幼虫神经元选择性地经历PCD。因此，这种发育控制的神经元PCD的破坏导致成年中枢神经系统的异常形成。哺乳动物的青春期类似于两栖动物和昆虫的变态，在此期间中枢神经系统也发生了广泛的神经元修饰。这种过渡性中枢神经系统是青少年情绪和心理不稳定的原因之一。然而，什么类型的幼年神经元被选择性地注定要死亡，以及这种选择是如何进行的，目前还不清楚。果蝇是解决这些问题的一个很好的模型系统，因为有先进的神经遗传学工具可用。为了了解神经元PCD在苍蝇变态过程中的意义和机制，我们提出了两个具体的目标：(1)通过鉴定死亡神经元的神经化学表型，建立第一个全面的神经解剖学图谱。由于分化神经元的功能由它们所承载的神经化学递质决定，这一目标将决定哪些类型(功能)的幼年神经元被编程死亡。除了28个幼虫神经元外，我们不知道其他300个注定死亡的神经元的神经化学特性。为此，我们将开发一种新的在体细胞死亡标记，以方便地检测死亡神经元。死亡神经元的鉴定将通过使用特定的Gal4驱动程序来完成。(2)确定果蝇中枢神经系统中的一个关键的凋亡基因GRIM在多大程度上对神经元性PCD起作用，并了解GRIM的表达是如何被调控的。我们将使用一种新的基因组工程工具CRISPR来产生报告基因与GRIM的连锁。这些研究将使我们了解在变态过程中如何诱导凋亡基因的表达。在这些工作中，我们希望培养本科生和研究生，并针对每个具体目标发表一篇研究论文。我们提出的对果蝇的研究将为深入了解神经元PCD在哺乳动物青春期中的作用提供依据。

 DESCRIPTION (provided by applicant): Programmed cell death (PCD) of neurons is very important developmental event to establish functional central nervous system (CNS) via eliminating obsolete neurons. During metamorphic development, certain larval neurons selectively undergo PCD in both vertebrates and invertebrates. Thus, disruption of such developmentally controlled neuronal PCD results in the aberrant formation of adult CNS. Puberty in mammals is comparable to metamorphosis in amphibians and insects, and extensive neuronal modifications in the CNS take place during this period as well. Such a transitional CNS is a causative reason why teens are emotionally and psychologically unstable. However, it is not well understood what types of juvenile neurons are selectively fated to die, and how such selection is made. Drosophila is an excellent model system to tackle these questions, as sophisticated neuro-genetic tools are available. To understand the significance and mechanisms of neuronal PCD during fly metamorphosis, we propose two specific aims in this proposal: (1) we will establish the first comprehensive neuroanatomical map of dying neurons by identifying their neurochemical phenotypes. Since functions of differentiated neurons are dictated by the neurochemical transmitters they bear, this aim will determine which types (functions) of juvenile neurons are programmed to die. Except for 28 larval neurons, we do not know the neurochemical identities of other ~300 doomed neurons. For this aim, we will develop a new in vivo cell death marker to conveniently detect dying neurons. Identification of dying neurons will be done by using specific gal4 drivers. (2) We propose to determine to what extent grim, a critical apoptotic gene in Drosophila CNS, plays a role in the neuronal PCD and to understand how grim expression is regulated. We will employ a novel genome engineering tool, CRISPR, to generate knock-in of grim with reporter genes. These studies will allow us to understand how apoptotic gene expression is induced during metamorphosis. Throughout these works, we expect to train both undergraduate and graduate students and to publish one research paper from each specific aim. Our proposed studies in Drosophila will provide an insight into the role of neuronal PCD during puberty in mammals.