SUMO-dependent Regulation of Ubiquitin Ligases in Genomic Stability

泛素和小泛素样修饰物(SUMO)在基因组中具有关键但经典的截然不同的作用 稳定性和对环境毒素的反应。泛素和相扑通过E3连接酶共价连接到 靶蛋白，以动态调节细胞的蛋白质组。泛素和相扑通路功能障碍的结果 在人类的遗传不稳定性和癌症易感性方面。我们最近发现了以相扑为目标的E3 泛素连接酶家族(STUbls)，泛素化和靶向蛋白酶体的苏莫化蛋白，用于 退化。这种意想不到的现象需要对相扑函数的频谱进行修改。这 修订后的提案建立在我们发现的基础上，并添加了直接将STUbL机制连接到 癌症与基因组稳定性。我们已经确定了裂解酵母基因组不稳定性的主要介体 STUbL突变体，我们将通过这些来表征STUbL的细胞和分子机制 目标。来自裂解酵母的结果将为在人类和老鼠身上进行的研究提供一个框架 STUbL目标。值得注意的是，这些目标将STUbL操作机制放置在cell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集中在定义 STUbL在体外和体内作用的分子机制。在目标1中，我们将检验假设 STUbL通过控制关键相扑的命运，扮演着细胞凋亡与DNA修复途径之间的守门人角色 共轭关系。在目标2中，我们将解决我们的总体假设，即STUbL是细胞主密钥，控制 通过特定和可定义的蛋白质相互作用界面实现基因组稳定性。为了实现我们的目标，我们将 将强大的酵母遗传学与尖端结构分析、MudPIT质谱仪、 生物化学和哺乳动物细胞生物学。预期结果将提供关键的机械洞察 包括RNF4在内的STUbL的基因组稳定作用，并可能为RNF4- 相互关联的人类疾病。此外，对STUbL函数的详细理解应该会得出一般的结论 对基因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.