Regulatory functions of the SUMO system in ribosome biogenesis and mitosis

SUMO 系统在核糖体生物合成和有丝分裂中的调节功能

• 批准号: 72128078
• 负责人: Professor Dr. Stefan Müller
• 金额: --
• 依托单位: Institut für Biochemie II
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/72128078?language=en
• 关键词: Regulatory; functions; SUMO; system; ribosome

The reversible post-translational modification of proteins by the ubiquitin-like SUMO modifier controls key cellular pathways. The alteration of a given substrate between modification and demodification can determine its spatial distribution or regulate the assembly or disassembly of protein complexes. SUMO-specific proteases of the SENP family accurately govern the state of modification by catalyzing the deconjugation of SUMO from target proteins. The further characterization of SENP family members is thus of major importance to gain novel insights into SUMO function. In this proposal we concentrate on the role of SENP3 in ribosome biogenesis (Part I) and the involvement of SENP3 and SENP6 in the control of mitotic processes (Part II).Our previous work uncovered a regulatory role of SENP3 in the nucleolar steps of ribosome biogenesis and showed that this function is linked to nucleophosmin (NPM1). In the first funding period we now identified and characterized a novel SENP3-associated complex comprised of PELP1, TEX10 and WDR18 and demonstrate that this complex is involved in maturation and nucleolar release of the large ribosomal subunit. We found that PELP1 is dynamically modified by SUMO2/3 in a SENP3-controlled process and we provide evidence that the SUMO system determines the nucleolar partitioning of PELP1. We propose a model where the balanced sumoylation-desumoylation controls the dynamic association of the PELP1-WDR18-TEX10 complex with 60S pre-ribosomal particles and hypothesize that loss of SENP3 induces the premature release of the complex from these structures.In part I of the project we will challenge this hypothesis and ask the following questions:1. How does sumoylation affect composition and dynamics of ribosomal particles?2. How are AAA-ATPases involved in SUMO-dependent remodelling of pre-ribosomes?3. How do c-myc and p14ARF control SENP3 and the nucleolar SUMO system?Previous work by our group and others has also determined an important role of the mammalian SUMO system in the control of mitotic functions. Depletion of SENP3 by siRNA prevents mitotic arrest of cells upon addition of spindle poisons indicating that SENP3 functions in the spindle assembly checkpoint (SAC). We could define Borealin, a component of the chromosomal passenger complex (CPC), as a first mitotic substrate of SENP3. In the first funding period we gained new insight into mitotic regulation of SENP3 and revealed an interconnection of SENP3 with the mitotic kinase Plk1. We additionally observed that depletion of SENP6, which exerts specificity for SUMO2/3-chains, also affects SAC activity. Moreover, we identified the SAC component MAD1 as a SENP6-sensitive target of SUMO2/3.In part II the new funding period we will now concentrate on the following questions:1. How are SENP3 and PLK1 functionally connected?2. Is Mad1 a substrate for the SUMO-dependent degradation pathway?3. What is the role of SUMO2/3-chains in the control of MAD1 activity and recognitionby SENP6?

泛素样SUMO修饰剂对蛋白质的可逆翻译后修饰控制着关键的细胞通路。给定底物在修饰和去修饰之间的改变可以决定其空间分布或调节蛋白质复合物的组装或分解。SENP家族的SUMO特异性蛋白酶通过催化SUMO与靶蛋白的解缀合来精确地控制修饰状态。因此，SENP家族成员的进一步表征对于获得SUMO功能的新见解具有重要意义。在这个建议中，我们集中在SENP 3在核糖体生物合成中的作用（第一部分）和SENP 3和SENP 6在有丝分裂过程的控制中的参与（第二部分）。我们以前的工作揭示了SENP 3在核糖体生物合成的核仁步骤中的调节作用，并表明这种功能与核磷蛋白（NPM 1）有关。在第一个资助期内，我们鉴定并表征了一种由PELP 1、TEX 10和WDR 18组成的新型SENP 3相关复合物，并证明该复合物参与了核糖体大亚基的成熟和核仁释放。我们发现，PELP 1是动态修改SUMO 2/3在SENP 3控制的过程中，我们提供的证据表明，SUMO系统决定的核仁分区PELP 1。我们提出了一个模型，其中平衡的sumoylation-desumoylation控制的PELP 1-WDR 18-TEX 10复合物与60 S前核糖体颗粒的动态关联，并假设SENP 3的损失诱导复合物从这些structure.In项目的第一部分，我们将挑战这个假设，并提出以下问题：1。类小泛素化如何影响核糖体颗粒的组成和动力学？2. AAA-ATP酶如何参与SUMO依赖的前核糖体重塑？3. c-myc和p14 ARF如何控制SENP 3和核仁SUMO系统？我们小组和其他人以前的工作也确定了哺乳动物SUMO系统在有丝分裂功能控制中的重要作用。siRNA对SENP 3的消耗阻止了在添加纺锤体毒物后细胞的有丝分裂停滞，表明SENP 3在纺锤体组装检查点（SAC）中起作用。我们可以定义Borealin，染色体乘客复合物（CPC）的一个组成部分，作为SENP 3的第一个有丝分裂底物。在第一个资助期，我们对SENP 3的有丝分裂调控有了新的认识，并揭示了SENP 3与有丝分裂激酶Plk 1的相互联系。我们还观察到，SENP 6的耗竭，发挥特异性的SUMO 2/3链，也影响SAC的活性。此外，我们确定SAC组件MAD 1作为SUMO 2/3的SENP 6敏感目标。在第II部分新的资助期，我们现在将集中在以下问题：1。SENP 3和PLK 1在功能上是如何连接的？2. Mad 1是SUMO依赖性降解途径的底物吗？3. SUMO 2/3-链在SENP 6控制MAD 1活性和抑制中的作用是什么？