UBAP2L and the Cellular Stress Response

项目总结/摘要 从机制上理解细胞如何快速响应并在环境压力下生存， 深入了解人类疾病的治疗和预防-其中许多是压力表现在 不同的形式。降低细胞能量需求，同时快速而精确地调节 基因表达对于处于压力下的细胞是一个特殊的挑战。动态亚细胞区室， 对压力的反应可能有助于细胞的综合压力反应。应激颗粒（SG）和 加工体（PB）是由RNA组成的应激反应性临时细胞质区室， 和蛋白质。蛋白质合成的抑制将信使RNA（mRNA）从翻译机器中释放出来， 提供用于液-液相分离（LLPS）的底物，其产生SG。PB，虽然经常 组成性存在，通过增加大小和数量来响应翻译的关闭。虽然SG 受到了广泛的关注，一些证据表明，它们有助于细胞存活， 但是，人们对PB了解较少。最近的一些研究集中在一种新的蛋白质上， 相关蛋白2样（UBAP 2L）作为通过LLPS组装SG的关键组分。有趣的是， 最近发现，UBAP 2L不仅定位于SGs并有助于其形成，而且似乎 调节SG和PB的物理连接。通常，应力导致形成附接有PB的SG。 我们的初步数据表明，在缺乏UBAP 2L的情况下，具有附着PB的SG的形成受损， 而UBAP 2L的过表达导致混合颗粒，其由通常仅在以下任一种中发现的蛋白质组成： SG或PB。此外，我们发现敲除UBAP 2L降低了基础翻译水平，这表明 UBAP 2L可以调节翻译。这一假设已被其他证明UBAP 2L的人证实。 增强必需蛋白质合成基因的翻译。我们建议1。通过以下方式确定机制 其中UBAP 2L在应激时有助于形成具有附接的PB的SG; 2.确定 UBAP 2L特异性调节TOP-mRNAs（一类必需的mRNAs）翻译的机制 蛋白质合成）以及这种调节在压力下如何变化。此外，我们的协同目标将 这使我们能够确定UBAP 2L在RNA颗粒相互作用中的作用与 翻译调控，或者蛋白质的不同区域是否有助于这些不同的作用。这项建议 研究了UBAP 2L的新作用，并有望为理解应激反应做出重要贡献。 和蛋白质生物学成功完成此提案将产生对UBAP 2L的机械理解 因此，在推进治疗中可能是重要的，特别是对于 治疗以异常RNA颗粒组装或分解为特征的疾病。

Project Summary/Abstract Mechanistically understanding how cells rapidly respond to and survive environmental stresses is crucial for gaining insight into treatment and prevention of human diseases – many of which are stress manifest in different forms. Decreasing cellular energy requirements while simultaneously rapidly, yet precisely, regulating gene expression is a particular challenge for cells under stress. Dynamic subcellular compartments that respond to stress may contribute to the cell’s integrated stress response. Stress granules (SGs) and processing bodies (PBs) are both stress-responsive temporary cytoplasmic compartments comprised of RNA and proteins. Inhibition of protein synthesis frees messenger RNA (mRNA) from the translation machinery, providing substrate for Liquid-Liquid Phase Separation (LLPS), which gives rise to SGs. PBs, while often constitutively present, respond to the shut-down of translation by increasing in size and number. While SGs have received much attention and several lines of evidence suggest they contribute to cell survival under stress, less is understood about PBs. A few recent studies have converged on a new protein, Ubiquitin Associated Protein 2-like (UBAP2L) as a critical component of SG assembly via LLPS. Interestingly, we have recently discovered that not only does UBAP2L localize to SGs and contribute to their formation, but it appears to regulate physical linkage of SGs and PBs. Typically, stress causes the formation of SGs with PBs attached. Our preliminary data show that in the absence of UBAP2L, formation of SGs with attached PBs is impaired, while overexpression of UBAP2L results in mixed granules consisting of proteins typically found only either in SGs or PBs. Additionally, we found that knockout of UBAP2L reduces basal translation levels, suggesting that UBAP2L may modulate translation. This hypothesis has been confirmed by others who demonstrate UBAP2L enhances translation of essential protein synthesis genes. We propose to 1. Determine the mechanism by which UBAP2L contributes to the formation of SGs with attached PBs, upon stress; 2. Determine the mechanism by which UBAP2L specifically modulates translation of TOP-mRNAs (a class of mRNAs essential to protein synthesis) and how this modulation changes under stress. Additionally, our synergistic aims will allow us to determine if there is a connection between UBAP2L’s role in RNA granule interaction and translation regulation, or if different regions of the protein contribute to these distinct roles. This proposal investigates novel roles of UBAP2L and promises important contributions to understanding the stress response and protein biology. Successful completion of this proposal will yield a mechanistic understanding of UBAP2L’s contribution to the stress response and therefore may be important in advancing therapeutics, particularly for treatment of diseases characterized by abnormal RNA granule assembly or disassembly.