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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.

真核细胞是一个高度区室化的结构，其被细胞的结构细分为不同的功能区域。存在膜结合和无膜细胞器。这些后一个隔间也被称为生物分子缩合物。虽然这些无膜结构中的大多数已经被鉴定出来只是最近才发现冷凝物的形成对于电解槽中的许多基本过程是重要的。它因此，至关重要的是，我们要全面了解凝析油的潜在机制形成和它们在细胞中的生物活性的性质。我们一直在通过研究一种特定冷凝物的生物学来解决这些更广泛的问题，处理主体，或P主体。这种细胞质颗粒是高度保守的，并包含有- 抑制参与这些转录物加工的mRNA和蛋白质。我们在过去15年的努力一直致力于更好地了解这些颗粒在体内的生理作用，真核细胞在前一个赠款期间的研究通过确定一个潜在的作用进一步加深了这种理解在微管动力学调节中的P体。具体来说，我们发现一种独特的P体亚型当微管网络的完整性被破坏时，颗粒被诱导。此外，我们的初步数据表明，这些颗粒可能参与编码微管蛋白的TUB mRNA的特异性周转单体。本提案中的实验分为两个目标：（1）定义装配这些新颗粒的途径和（2）确定它们的生物活性是如何调节的。目标1中的研究将专门测试一个模型，该模型提出这些新颗粒的形成是由于选择被募集到TUB mRNA的P体成分。有趣的是，我们发现后一种衰变 in S.酿酒酵母表现出微管蛋白自动调节的特征，这一过程已经研究了几十年，哺乳动物然而，负责这种mRNA周转的衰变机制尚未确定。因此，这里的研究可以为微管蛋白生物学中一个长期存在的问题提供解决方案。在目标2中，将研究生物分子凝聚物的生物活性是如何被特定的成分控制的这种结构。我们将具体讨论一个关于P-机构在以下方面的作用的关键问题： mRNA稳定性主要的问题是P体是腐烂的场所还是居民的长期储存场所 mRNA。这里的实验将测试一个模型，该模型提出P体可以在这些不同的活性，并且从一种状态到另一种状态的转变由颗粒的蛋白质成分控制，比如Hrr 25蛋白激酶。最后，我们将评估P体衰变机器是便携式的可能性并被招募来选择作为降级目标的消息。总之，这项工作的完成应为我们提供了一个保守的生物分子的多样性和生理作用更好的理解真核细胞中的冷凝物。