Ras/ERK control of cell fates

描述（由申请人提供）：ras刺激的Raf-MEK-ERK激酶级联被反复用于控制正常和异常动物发育的许多方面。这种常见的信号级联如何引发特定的反应仍然知之甚少。ERK被认为磷酸化多个靶点，这些靶点可能因细胞类型而异，并与ERK无关的因子联合作用以引起适当的反应。然而，体内不同ERK靶点的相对重要性，以及ERK如何选择适合特定组织或环境的靶点，以及最终控制细胞反应的更下游的基因调控网络，仍然知之甚少。我们正在简单的模式生物秀丽隐杆线虫中研究这个问题，其中Ras-ERK指定了排泄管、P12外胚层、外阴等组织的命运。ERK在这三种组织中的一个“一般”靶点是elk1相关的Ets转录因子LIN-1。我们已经发现了另外两个潜在的一般靶点，BTB/锌指蛋白EOR-1和新的（但保守的）蛋白EOR-2。在目标1中，我们将结合蛋白质相互作用研究、蠕虫遗传学和DNA结合分析来确定EOR-1和EOR-2如何与LIN-1合作，控制下游对Ras/ERK的反应。在Aim 2中，我们将重点关注Ras/ERK如何促进一种特定的细胞命运，即排泄管的命运，排泄管是蠕虫原始肾脏系统的重要组成部分。我们将测试两个候选管道特异性Ras-ERK靶点的作用，一个Nkx5/ hmx家族同源结构域蛋白和一个保守的bromodomain蛋白，以了解它们如何促进组织对Ras-ERK的适当反应。最后，我们将继续我们基于rnai的筛选，以确定对排泄管命运重要的其他基因。这些研究将有助于回答Ras-ERK信号通路如何在不同细胞类型中引发不同的生物学反应的问题。我们将要研究的所有候选ERK靶点在人类中都是保守的。由于我们将要研究的几种蛋白质是人类癌症的致病因子，这些研究可能会提出治疗这些癌症的策略。排泄管细胞发育的控制也可能是理解人类肾脏发育和功能障碍的一个简单模型。

DESCRIPTION (provided by applicant): The Ras-stimulated Raf-MEK-ERK kinase cascade is used over and over again to control many aspects of normal, and abnormal, animal development. How this common signaling cascade elicits specific responses is still poorly understood. ERK is thought to phosphorylate multiple targets that may differ among cell types and that act combinatorially with ERK-independent factors to elicit the appropriate response. However, the relative importance of different ERK targets in vivo and how ERK chooses targets appropriate for a given tissue or circumstance is still poorly understood, as are the more downstream gene regulatory networks that ultimately control cellular responses. We are studying this problem in the simple model organism C. elegans, where Ras-ERK specifies the fates of the excretory duct, P12 ectoblast, vulva and other tissues. One "general" target of ERK in all three tissues is the Elk1-related Ets transcription factor LIN-1. We've discovered two other potential general targets, the BTB/Zinc finger protein EOR-1 and the novel (but conserved) protein EOR-2. In Aim 1 we will use a combination of protein interaction studies, worm genetics and DNA binding assays to determine how EOR-1 and EOR-2 cooperate with LIN-1 to control downstream responses to Ras/ERK. In Aim 2 we will focus on how Ras/ERK promotes one specific cell fate, that of the excretory duct, an essential component of the worm's primitive renal system. We will test the roles of two candidate duct-specific Ras-ERK targets, an Nkx5/Hmx-family homeodomain protein and a conserved bromodomain protein, to understand how they promote tissue-appropriate responses to Ras-ERK. Finally we will continue our RNAi-based screens to identify additional genes that are important for the excretory duct fate. These studies will help to answer the question of how the commonly used Ras-ERK signaling pathway elicits different biological responses in different cell types. All of the candidate ERK targets we'll study are conserved in humans. Since several proteins we'll study are causative agents in human cancers, these studies may suggest strategies for treating those cancers. The control of excretory duct cell development also may be a simple model relevant for understanding kidney development and malfunction in humans. Public Health Relevance: These studies will help to answer the question of how a commonly used signaling pathway elicits different biological responses in different cell types. Since several proteins we'll study are causative agents in human cancers and developmental syndromes, these studies may suggest strategies for treating those disorders.