Role of the SUMO Protease Ulp1 in Cell Cycle Progression

描述(申请人提供)：细胞利用相扑的动态添加和移除，相扑是一种小的泛素样修饰物来调节蛋白质功能。相扑蛋白修饰存在于酵母、人类，可能还有所有真核生物中。在人类中，相扑动力学的失调在某些形式的白血病和前列腺癌中起着作用。此外，参与癌症发病机制的几个基因产物受相扑的添加和移除的调节。成熟的、接合能力强的相扑底物以及脱氨基底物的生产依赖于ULP家族的蛋白酶。哺乳动物细胞至少有7个类ULP分子。ULP家族的创始成员是酵母Ulp1和Ulp2蛋白，这是Hochstrasser实验室发现的两种相扑蛋白酶。缺乏Ulp1p介导的脱氨基作用会导致芽期酵母有丝分裂停滞和细胞死亡。尽管酵母中已知的苏糖化蛋白的数量越来越多，但对于哪种底物Ulp1必须去苏糖化才能确保细胞周期的正常进行，我们知之甚少。由于Ulp1p定位于核孔复合体，我们推测这种相扑蛋白水解酶可能有助于控制穿越核膜的重要细胞周期调节因子。这个项目的主要目标是确定进化上保守的与Ulp1p相互作用的蛋白质，这些蛋白质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、遗传学和生化方法。具体地说，1)在有丝分裂过程中需要Ulp1p功能的确切时间将通过细胞生物学技术来确定。2)使用ulp1突变体，将从遗传上分离ULP1相互作用元件并对其进行鉴定。3)分析了一种新型的能结合相扑的Ulp1相互作用元件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研究类似情况和同源蛋白奠定框架。公共卫生相关性：表达缺陷相扑酶(Ulp1)的发芽酵母细胞表现出异常的有丝分裂和细胞周期进程改变。在人类中，这些现象与自然流产、衰老和癌症有关。研究ulp1突变体有助于我们确定一些相关的分子。

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.