Role of the SUMO Protease Ulp1 in Cell Cycle Progression

描述（由申请人提供）：细胞利用SUMO的动态添加和去除，SUMO是一种小的泛素样调节剂来调节蛋白质功能。SUMO蛋白修饰存在于酵母、人类和可能所有真核生物中。在人类中，SUMO动力学的失调在某些形式的白血病和前列腺癌中起作用。此外，一些参与癌症发病的基因产物受到SUMO的添加和去除的调节。生产成熟的，偶联能力SUMO以及去氧基化底物取决于Ulp家族的蛋白酶。哺乳动物细胞至少有7个ulp样分子。Ulp家族的创始成员是酵母Ulp1和Ulp2蛋白，这两种SUMO蛋白酶是在Hochstrasser实验室发现的。在出芽酵母中，Ulp1p介导的去氧基化缺失导致有丝分裂阻滞和细胞死亡。尽管酵母中已知的苏酰化蛋白越来越多，但对于Ulp1必须对哪些底物进行苏酰化以确保适当的细胞周期进程知之甚少。由于Ulp1p定位于核孔复合体，我们假设这种SUMO蛋白酶可能有助于控制重要的细胞周期调节因子在核膜上的转运。该项目的主要目标是鉴定与Ulp1p相互作用的进化保守蛋白，这些蛋白可能对细胞分裂周期很重要。为了实现这一目标，将使用细胞生物学、遗传学和生物化学方法。具体来说，1)在有丝分裂过程中需要Ulp1p功能的确切时间将使用细胞生物学技术确定。2)利用ulp1突变体对ulp1相互作用体进行分离和鉴定。3)分析一种可以结合SUMO的新型Ulp1相互作用子Hex3的功能。特别是，我们的研究旨在了解Ulp1p的功能作用，并为未来在哺乳动物癌症模型中类似情况和同源蛋白的研究奠定框架。公共卫生相关性：表达有缺陷的SUMO蛋白酶（Ulp1）的出芽酵母细胞表现出异常的有丝分裂和改变的细胞周期进程。在人类中，这些现象与自然流产、衰老和癌症有关。对ulp1突变体的研究帮助我们确定了一些致病分子。

DESCRIPTION (provided by applicant): Cells utilize the dynamic addition and removal of SUMO, a small ubiquitin-like modifier to modulate protein function. SUMO protein modification exist in yeast, humans and possibly all eukaryotes. In humans, dysregulation of SUMO dynamics plays a role in certain forms of leukemia and prostate cancer. Furthermore, several gene products that are involved in cancer pathogenesis are regulated by the addition and removal of SUMO. Production of mature, conjugation competent SUMO as well as desumoylation substrates depends on proteases of the Ulp family. Mammalian cells have at least 7 Ulp-like molecules. The founding members of the Ulp family are the yeast Ulp1 and Ulp2 proteins, two SUMO proteases that were identified in the Hochstrasser lab. Absence of Ulp1p mediated desumoylation leads to mitotic arrest and cell death in budding yeast. Despite a growing number of known sumoylated proteins in yeast, little is known about which individual substrates Ulp1 must desumoylate in order to ensure proper cell cycle progression. Since Ulp1p localizes to the nuclear pore complex we hypothesize that this SUMO protease may help to control important cell cycle regulators in transit across the nuclear envelope. The main goal of this project is to identify evolutionarily conserved proteins that interact with Ulp1p and may be important for the cell division cycle. To achieve this goal cell biological, genetic, and biochemical approaches will be used. Specifically, 1) the exact time at which Ulp1p function is required during mitosis will be determined using cell biological techniques. 2) Using a ulp1 mutant ULP1 interactors will be isolated genetically and characterized. 3) The function of a novel Ulp1 interactor that can bind SUMO, Hex3, will be analyzed. In particular, our studies are designed to understand the functional roles of Ulp1p and to lay the framework for future studies of similar situations and homologous proteins in mammalian cancer models. PUBLIC HEALTH RELEVANCE: Budding yeast cells expressing a defective SUMO protease enzyme (Ulp1) exhibit aberrant mitosis and altered cell cycle progression. In humans these phenomena are linked to spontaneous abortions, ageing and cancer. Studying the ulp1 mutant has helped us to identify some of the responsible molecules.