Insulin-Regulated MAP Kinase Pathways

描述（由申请人提供）：丝裂原活化蛋白激酶（MAPKs）是信号通路的通用元件。ERK2长期以来一直被用作定义mapk及其级联特性的原型。ERK2和/或ERK1不仅是胚胎发生、分化和增殖所必需的，而且也是分化细胞中发生的事件所必需的，例如膜通透性、长期增强和转录的变化。ERK1/2功能失调或其他不适当的功能导致从心-面-皮综合征到多囊肾病到癌症等疾病。我们建议研究ERK1/2，必不可少的，无处不在的信号蛋白，如何在不同的信号转导过程中特异性地起作用。我们将定义引导ERK1/2到作用位点的配体依赖性调节机制，并确定这些位点的功能。ERK1/2的一个重要作用部位是细胞核。刺激诱导的磷酸化ERK1/2核易位是多种转录反应和细胞程序变化所必需的。我们将阐明ERK1/2核进出口的潜在机制。我们已经证明磷酸化ERK1/2的核易位只发生在对一个配体子集的响应中。我们将研究这种特异性是如何实现的。我们还发现配体刺激ERK1/2与特定基因的结合。我们将确定这是如何发生的，它是如何被调节的，以及ERK1/2在这些位点上的配体特异性作用。ERK1/2与特定复合物的结合也控制着它们的配体选择性激活和定位到核外的作用位点。我们将确定cAMP对ERK1/2通路的差异调控是如何响应生长因子的。我们将分析与细胞骨架蛋白和我们在筛选中鉴定的选择性识别磷酸化ERK2的相互作用物的蛋白质的复合物。我们将研究这些蛋白相互作用的结构基础，激酶与这些蛋白复合物的底物和作用，以及这些蛋白对ERK1/2定位的影响。目标是确定配体特异性输出，并在特定输出的背景下获得ERK1/2底物。最后，研究钙调磷酸酶（PP2B）和磷酸蛋白磷酸酶2A （PP2A）在ERK1/2配体特异性调控和功能中的作用。提出的实验将确定ERK1/2通路中配体/过程特异性的机制。

DESCRIPTION (provided by applicant): Mitogen-activated protein kinases (MAPKs) are universal elements of signaling pathways. ERK2 has long served as a prototype to define properties of MAPKs and their cascades. ERK2 and/or ERK1 are required not only for embryogenesis, differentiation, and proliferation, but also for events in differentiated cells, e.g., changes in membrane permeability, long term potentiation, and transcription. The misregulated or otherwise inappropriate functions of ERK1/2 contribute to diseases ranging from cardio-facio-cutaneous syndrome to polycystic kidney disease to cancer. We propose studies to discover how ERK1/2, essential, ubiquitous signaling proteins, act with specificity in different signal transduction processes. We will define ligand-dependent regulatory mechanisms that direct ERK1/2 to sites of action and determine functions at these sites. An essential site of action of ERK1/2 is the nucleus. The stimulus-induced nuclear translocation of phosphorylated ERK1/2 is required for several transcriptional responses and changes in cell programs. We will elucidate the underlying mechanisms of the nuclear import and export of ERK1/2. We have demonstrated that the nuclear translocation of phosphorylated ERK1/2 occurs only in response to a subset of ligands. We will examine how this specificity is achieved. We have also found that ligands stimulate the association of ERK1/2 with specific genes. We will determine how this occurs, how it is regulated, and the ligand-specific actions of ERK1/2 at these sites. Association of ERK1/2 with specific complexes controls their ligand-selective activation and localization to sites of action outside the nucleus as well. We will determine how cAMP differentially regulates the ERK1/2 pathway in response to growth factors. We will analyze complexes with cytoskeletal proteins and proteins we identified in a screen for interactors that selectively recognize phosphorylated ERK2. The structural basis for the interactions, the substrates and actions of the kinases in complex with these proteins, and the effects of these proteins on localization of ERK1/2 will be examined. The goals are to identify ligand-specific outputs and to have access to ERK1/2 substrates in the context of a specific output. Finally, the actions of calcineurin (PP2B) and phosphoprotein phosphatase 2A (PP2A) in ligand-specific regulation and function of ERK1/2 will be studied. The experiments proposed will determine mechanisms underlying ligand/process specificity in the ERK1/2 pathway.