DROSOPHILA NEURONAL TEMPORAL IDENTITY

描述(申请人提供)：为了揭示神经元的惊人多样性是如何通过出生顺序/时间相关的细胞命运指定而产生的，我们提议在相对简单的生物--果蝇--中使用复杂的遗传工具来研究神经元时间认同的机制。从遗传镶嵌屏幕上，我们已经确定了果蝇Chinmo BTB-锌指蛋白，特别是它通过神经发生的梯度，作为一种新的机制赋予神经元时间同一性。我们进一步证明，Chinmo梯度的建立涉及携带1.7kb长5‘UTR的Chinmo消息的差异翻译。在这个方案中，我们将(1)研究Chinmo功能在指定神经元时间同一性方面的共性，(2)研究chinmo 5‘非编码区依赖的翻译控制以追溯Chinmo控制的神经元时间细胞命运规范的起源，以及(3)筛选可能在Chinmo通路内起作用或独立操作以控制神经元时间同一性的额外基因。这项研究包括对Chinmo功能的彻底分析和对时间认同基因的系统识别，有望为控制出生顺序/时间依赖性神经元多样化的机制提供重要见解，这是大脑中的一个关键发育过程。 与公共健康相关：大脑由数量巨大的不同类型的神经元组成。这些神经元相互作用，形成复杂的大脑回路，构成行为和身体重要功能协调的基础。先天性和发育障碍会干扰神经元多样性的形成，对大脑功能造成严重后果。此外，关于大脑中导致这种多样性的干细胞的知识可能会为退行性疾病期间或损伤后的干预提供强大的临床方法。这个项目的目标是了解脑干细胞如何根据神经元出生的顺序(时间同一性)产生神经元多样性。为了解决这个问题，我们使用了一个强大的模型系统--果蝇，在这个系统中，控制时间同一性的基因可以有效地分离出来。我们在这个系统中的研究已经分离出一个基因，称为chinmo(按时间顺序不适当的形态发生)，在这一过程中发挥核心作用。在这个项目中，我们将通过(A)确定它是否是一个通用的时间同一性基因，或者是否有其他基因也可以完成这一功能，(B)确定Chinmo的功能机制，以及(C)寻找可能与Chinmo一起发挥作用的其他细胞身份基因，或者以不依赖于Chinmo的方式来赋予时间同一性，从而阐明Chinmo的功能机制。我们预计，拟议的研究将对我们理解神经元多样性是如何产生的，这种神经元多样性是如何在干细胞中编码的，以及如何操纵这些干细胞以产生特定的神经元群体产生根本性的影响。

DESCRIPTION (provided by applicant): To unravel how the astonishing diversity of neurons is derived through birth order/timing-dependent cell fate specification, we propose to use sophisticated genetic tools in a relatively simple organism, the fruit fly Drosophila, to study the mechanisms of neuronal temporal identity. From a genetic mosaic screen, we have identified the Drosophila Chinmo BTB-zinc finger protein, and in particular its gradients through neurogenesis, as a novel mechanism conferring neuronal temporal identity. We have further demonstrated that the establishment of the Chinmo gradient involves the differential translation of chinmo messages carrying a 1.7kb-long 5'UTR. In this proposal, we will (1) examine the generality of Chinmo function in specifying neuronal temporal identity, (2) investigate the chinmo 5'UTR-dependent translational control for tracing back the origin for Chinmo-governed neuronal temporal cell fate specifications, and (3) screen for additional genes that may act within the Chinmo pathway or operate independently to control neuronal temporal identity. This study, including thorough analysis of Chinmo function and systematical identification of temporal identity genes, promises to provide major insights into the mechanisms governing birth order/timing-dependent neuronal diversification, a crucial developmental process in the brain. PUBLIC HEALTH RELEVANCE: The brain is composed of a monumental number of different types of neurons. These neurons interact with each other forming the complex brain circuits that underlie behavior and the coordination of the vital functions of the body. Congenital and developmental disorders that interfere with the formation of neuronal diversity have drastic consequences for brain function. Further, knowledge about the stem cells that in the brain give rise to this diversity may provide powerful clinical approaches for interventions during degenerative disorders or after injury. The goal of this project is to understand how brain stem cells give rise to neuronal diversity according to the order in which neurons are born (temporal identity). To address this question we are using a powerful model system, the fruit fly Drosophila, in which the genes controlling temporal identity can be isolated in an efficient manner. Our studies in this system have isolated a gene, called chinmo (chronologically inappropriate morphogenesis) with central roles in this process. In this project we will elucidate the mechanisms of Chinmo function by (a) determining if it is a universal temporal identity gene, or whether there are other genes that also can fulfill this function, (b) determining the mechanisms by which Chinmo functions, and (c) searching for other cell identity genes that may function with Chinmo, or in a Chinmo-independent fashion to confer temporal identity. We expect that the studies proposed will have a fundamental impact in our understanding of how neuronal diversity is generated, how this neuronal diversity is encoded in stem cells, and how these stem cells can be manipulated in order to generate particular neuron populations.