Regulation of the ERK signaling pathway by K63-linked polyubiquitination

项目总结/摘要 本申请的总体目标是阐明Lys 63（K63）-连接的多泛素化的机制。 细胞外信号调节激酶ERK 1和ERK 2，并确定这种新的翻译后调节激酶的贡献。 肿瘤发生的修饰。ERK 1和ERK 2具有高度的结构和功能， 相似之处，是丝裂原活化蛋白激酶（MAPK）级联的下游效应物， 细胞行为和细胞命运决定响应于广泛的细胞内信号。ERK信号 是哺乳动物细胞中主要的促有丝分裂途径。它在大部分人中异常上调， 由于上游信号传导组分突变的流行和ERK的再激活， 也是对靶向这些上游成分的药物产生耐药性的最常见机制。发展中 一种适用于由过度活跃的ERK途径驱动的广泛肿瘤的疗法， 克服耐药性仍然是癌症研究中的主要挑战。为了应对这一挑战 需要全面了解ERK是如何在MAPK中特异性和有效地激活的 级联。目前对ERK激活的认识主要局限于其上游磷酸化。 激酶MEK。在我们的初步研究中，我们发现ERK与K63连接的多聚泛素链缀合， 并且这种翻译后修饰与ERK激活相关。此外，我们还确定了 三部分基序蛋白TRIM 15作为泛素连接酶，肿瘤抑制因子CYLD作为去泛素化酶， DUB酶，可以动态调节ERK泛素化。在这里，我们将测试中心假设， ERK的K63泛素化对于这些激酶的特异性和有效激活以及调节异常是至关重要的。 这种翻译后修饰有助于肿瘤的发病机制和治疗抗性。我们 提出三个具体目标。首先，我们将描述TRIM 15和CYLD在K63泛素化中的作用， 并定义了它们与ERK的相互作用是如何被促有丝分裂刺激所调节的。第二，我们将阐明 K63泛素化在ERK激活中的作用及机制。第三，我们将确定 TRIM 15和CYLD在肿瘤发生和治疗抗性中的作用总的来说，这些目标将解决 ERK生物学和致癌信号的基本问题，并将提供有价值的信息， 开发针对由过度活跃的ERK驱动的过多人类肿瘤的有效疗法 信号通路

PROJECT SUMMARY/ABSTRACT The overall goal of this application is to elucidate the mechanism of Lys63 (K63)-linked polyubiquitination of extracellular signal-regulated kinases ERK1 and ERK2, and to determine the contribution of this novel post-translational modification to tumorigenesis. ERK1 and ERK2, which share high structural and functional similarities, are downstream effectors of a mitogen-activated protein kinase (MAPK) cascade that dictates cellular behavior and cell fate decisions in response to a wide range of intracellular signals. The ERK signaling pathway is the primary mitogenic pathway in mammalian cells. It is aberrantly upregulated in a large fraction of human tumors due to prevalence of mutations in the upstream signaling components, and reactivation of ERK is also the most common mechanism for resistance to drugs that target these upstream components. Developing a therapy that is applicable for the wide range of tumors driven by a hyperactive ERK pathway and that can circumvent drug resistance remains a major challenge in cancer research. To contend with this challenge requires a comprehensive understanding of how ERK is specifically and efficiently activated within the MAPK cascade. The current knowledge of ERK activation is largely limited to their phosphorylation by the upstream kinase MEK. In our preliminary studies, we have found that ERK is conjugated to K63-linked polyubiquitin chains, and that this post-translational modification correlates with ERK activation. Furthermore, we have identified the tripartite-motif protein TRIM15 as a ubiquitin ligase, and the tumor suppressor CYLD as a deubiquitinating enzyme (DUB), that may dynamically regulate ERK ubiquitination. Here we will test the central hypothesis that K63 ubiquitination of ERK is critical for the specific and efficient activation of these kinases and that dysregulation of this post-translational modification contributes to the pathogenesis and therapeutic resistance of tumors. We propose three specific aims. First, we will characterize the role of TRIM15 and CYLD in K63 ubiquitination of ERK and define how their interactions with ERK are regulated by mitogenic stimuli. Second, we will elucidate the function and mechanism of K63 ubiquitination in the activation of ERK. Third, we will determine the role of TRIM15 and CYLD in tumorigenesis and therapeutic resistance. Collectively, these aims will address fundamental issues in ERK biology and oncogenic signaling, and will provide valuable information for the development of effective therapies for the plethora of human tumors that are driven by a hyperactive ERK signaling pathway.