An analysis of the regulation and functions of a novel family of membraneless organelles in eukaryotic cells

真核细胞新型无膜细胞器家族的调控和功能分析

基本信息

批准号：
10736346
负责人：
Paul K Herman
金额：
$ 33.26万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2027-04-30
项目状态：
未结题

项目摘要

The eukaryotic cell is a highly compartmentalized structure that is subdivided into distinct functional areas by the presence of both membrane-bound and membraneless organelles. These latter compartments have also been referred to as biomolecular condensates. Although most of these membraneless structures have been identified only recently, condensate formation has been found to be important for many essential processes in the cell. It is therefore critical that we develop a thorough understanding of the mechanisms underlying condensate formation and the nature of their biological activities in the cell. We have been addressing these broader issues by studying the biology of one particular condensate, the Processing body, or P-body. This cytoplasmic granule is highly conserved and contains translationally- repressed mRNAs and proteins involved in the processing of these transcripts. Our efforts over the past 15 years have been focused on developing a better understanding of the physiological roles of these granules in the eukaryotic cell. Studies during the prior grant period furthered this understanding by identifying a potential role for P-bodies in the regulation of microtubule dynamics. Specifically, we found that a distinct subtype of P-body granule was induced when the integrity of the microtubule network was disrupted. Moreover, our preliminary data suggest that these granules may be involved in the specific turnover of the TUB mRNAs that encode tubulin monomers. The experiments in this proposal are organized into two aims that will (1) define the assembly pathway for these novel granules and (2) determine how their biological activities are regulated. The studies in Aim 1 will specifically test a model proposing that these novel granules form as a result of select P-body components being recruited to the TUB mRNAs. Interestingly, we have found that this latter decay in S. cerevisiae exhibits the hallmarks of tubulin autoregulation, a process that has been studied for decades in mammals. However, the decay machinery responsible for this mRNA turnover has not yet been identified. Therefore, the studies here could provide resolution for a long-standing question in tubulin biology. In Aim 2, we will examine how the biological activity of a biomolecular condensate can be controlled by specific constituents of that structure. We will specifically address a key question concerning the role of P-bodies with respect to mRNA stability. The primary issue is whether P-bodies are sites of decay or long-term storage for the resident mRNAs. The experiments here will test a model proposing that P-bodies can alternate between these different activities and that the transition from one state to the other is controlled by protein constituents of the granule, like the Hrr25 protein kinase. Finally, we will assess the possibility that the P-body decay machinery is portable and recruited to select messages that are targeted for degradation. In all, the completion of this work should provide us with a better understanding of the diversity and physiological roles of a conserved biomolecular condensate in eukaryotic cells.

真核细胞是一种高度分隔的结构，由膜结合和无膜细胞器的存在。这些后一个隔室也是称为生物分子冷凝物。尽管已经确定了这些无膜结构的大多数直到最近，才发现凝结物的形成对于细胞中的许多基本过程都很重要。它因此，至关重要的是我们对冷凝水的机制有透彻的理解细胞中其生物活性的形成及其性质。我们一直在研究一种特定的冷凝物的生物学，以解决这些更广泛的问题，加工体或P体。该细胞质颗粒是高度保守的，并包含翻译抑制了参与这些转录本处理的mRNA和蛋白质。我们过去15年的努力一直专注于更好地了解这些颗粒在真核细胞。上一批赠款期间的研究通过确定潜在角色进一步理解对于微管动力学调节中的P-体。具体而言，我们发现P体的独特亚型当微管网络的完整性中断时，诱导颗粒。而且，我们的初步数据表明，这些颗粒可能与编码小管蛋白的浴缸mRNA的特定周转有关单体。该提案中的实验分为两个目标，将（1）定义组装这些新型颗粒的途径和（2）确定如何调节其生物学活性。 AIM 1中的研究将专门测试一个模型，该模型提出这些新型颗粒是由于选择被招募到浴缸mRNA的P体分。有趣的是，我们发现后一个腐烂在酿酒酵母中哺乳动物。但是，尚未确定负责此mRNA离职的衰减机械。因此，这里的研究可以为小管蛋白生物学的长期问题提供解决方案。在AIM 2中，我们将研究如何通过特定成分来控制生物分子冷凝物的生物学活性那个结构。我们将专门解决有关P-体在 mRNA稳定性。主要问题是P-体是居民的衰减或长期存储的地点 mrnas。这里的实验将测试一个模型，该模型表明P体可以在这些不同的不同活动以及从一个状态到另一个状态的过渡由颗粒的蛋白质成分控制，像HRR25蛋白激酶一样。最后，我们将评估P体衰减机械是便携式的可能性并招募以选择针对退化的消息。总之，这项工作的完成应该为我们提供对保守生物分子的多样性和生理作用的更好理解真核细胞中的凝结。