SUMO-dependent Regulation of Ubiquitin Ligases in Genomic Stability

泛素和小泛素样修饰物（SUMO）在基因组中具有重要而独特的作用 稳定性和对环境毒素的反应。泛素和SUMO通过E3连接酶共价连接， 靶蛋白，动态调节细胞的蛋白质组。泛素和SUMO通路功能障碍结果 基因不稳定性和癌症易感性。我们最近发现了针对相扑的E3 泛素连接酶家族（STUbLs），其泛素化并将SUMO化的蛋白质靶向蛋白酶体， 降解这种意料之外的现象需要对相扑功能谱进行修正。这 修订后的提案建立在我们的发现基础上，并增加了新的数据，直接将STUbL机制与 癌症和基因组稳定性。我们已经确定了裂变酵母基因组不稳定性的主要介质 STUbL突变体，我们将通过这些研究来表征STUbL的细胞和分子机制。 目标的裂变酵母的结果将为人类和小鼠的研究提供一个框架。 STUBL目标。值得注意的是，这些目标将STUbL作用机制置于细胞的交叉点， 生长/凋亡途径、基因组稳定性和肿瘤发生。我们的两个具体目标侧重于定义 STUbL在体外和体内发挥作用的分子机制。在目标1中，我们将检验以下假设： STUbLs通过控制关键SUMO的命运，充当细胞凋亡与DNA修复途径的看门人 共轭在目标2中，我们将讨论我们的总体假设，即STUBL是细胞的主密钥， 通过特定的和可定义的蛋白质相互作用界面的基因组稳定性。为了实现我们的目标，我们将 将强大酵母遗传学与尖端结构分析、MudPIT质谱法 生物化学和哺乳动物细胞生物学。预期的结果将提供关键的机械见解， 包括RNF 4在内的STUbLs的基因组稳定作用，并可能为RNF 4- 与人类疾病有关。此外，对STUbL函数的详细理解应该会产生一般的 对遗传毒性应激反应的影响。

Ubiquitin and the small ubiquitin-like modifier (SUMO), have critical but classically distinct roles in genome stability and responses to environmental toxins. Ubiquitin and SUMO are covalently attached by E3 ligases to target proteins, to regulate the cell's proteome dynamically. Ubiquitin and SUMO pathway dysfunction results in genetic instability and cancer predispositions in humans. We recently discovered the SUMO-targeted E3 ubiquitin ligase family (STUbLs), which ubiquitinate and target sumoylated proteins to the proteasome for degradation. This unanticipated phenomenon requires a revision to the spectrum of SUMO functions. This revised proposal builds upon our discovery and adds new data that directly connects the STUbL mechanism to cancer and genomic stability. We have identified the main mediators of genomic instability in fission yeast STUbL mutants and we will characterize the cellular and molecular mechanisms of STUbLs through these targets. Results from fission yeast will provide a framework for studies conducted on the human and mouse STUbL targets. Notably, these targets place the STUbL mechanism of action at the intersection of cell growth/apoptotic pathways, genomic stability and oncogenesis. Our two Specific Aims focus on defining the molecular mechanisms of STUbL function both in vitro and in vivo. In Aim 1, we will test the hypothesis that STUbLs act as gatekeepers for apoptosis versus DNA repair pathways, by controlling the fates of key SUMO conjugates. In Aim 2, we will address our overall hypothesis that STUbLs are cellular master keys, controlling genome stability through specific and definable protein interaction interfaces. To attain our Aims we will integrate powerful yeast genetics with cutting-edge structural analyses, MudPIT mass spectrometry, biochemistry and mammalian cell biology. The expected results will provide critical mechanistic insights into the genome stabilizing roles of STUbLs including RNF4, and may suggest therapeutic strategies for RNF4- linked human diseases. Additionally, a detailed understanding of STUbL function should yield general implications for responses to genotoxic stress.