Translation control of stress response and innate immunity

项目摘要 这个项目的长期目标是了解信使核糖核酸的翻译调控机制是如何控制的。 生理和病理条件下的细胞应激反应。感兴趣的具体途径是 整合应激反应，包括使α亚单位磷酸化的应激反应蛋白。 EIF2，以减弱一般的翻译启动。最近，我们发现ISR抑制了mRNA的翻译 通过另一种翻译抑制物4E-BP的诱导。同时，这样的条件 矛盾地刺激转录因子的翻译，如ATF4，由于调节性的存在 位于主要ATF4开放阅读框架之前的上游开放阅读框架(UORF)。压力反应成绩单如何 逃避翻译抑制，甚至经历更活跃的表达，是应激细胞的主要原因之一 仍然知之甚少的概念问题。我们对果蝇的初步研究将我们带到了一个 对这个问题的一些新见解：包括我们的发现：(1)ISR增强先天免疫反应 对细菌感染和抗菌肽具有5‘UTRs，可以逃避由 ISR信号，(2)先前意想不到的因素调节ISR的激活，以及(3)ATF6也具有 5‘非编码区，刺激主要的ORF翻译以应对压力。在这里，我提议用果蝇来 调查潜在的监管机制，并确定新确定的ISR监管因素 影响果蝇的先天免疫反应、炎症和寿命。我们将补充分子 以遗传学为基础的方法和基因组工具，如核糖体图谱和基于结构的建模研究。 我们将追求三个具体目标：(1)我们将确定ISR信号如何增强先天免疫 响应，主要集中在抗微生物多肽转录物通过 一种非常规的机制来逃避与ISR信号相关的翻译抑制。(2)通过 表征了我们已经确定的新型ISR调节子，我们计划确定uORF如何包含 当一般的mRNA翻译被抑制时，转录本增加它们的翻译，并检查它们是如何 影响与ISR调节异常相关的表型。(3)我们将检验ATF6是另一个假设 在ISR过程中在mRNA翻译水平上调节以调节其转录的转录因子 回应。值得注意的是，这一通路的损伤或过度刺激是各种神经退行性变的基础。 以及人类的新陈代谢紊乱。因此，更好地了解监管机制不仅会 推进我们对应激状态下细胞基因表达调控的概念性理解，但也可能促使 为治疗目的调节ISR信号的新策略的开发。

Project Summary The long-term goal of this project is to understand how mRNA translational regulatory mechanisms control cellular stress response under physiological and pathological conditions. The specific pathway of interest is the Integrated Stress Response (ISR), which involves stress-responsive kinases that phosphorylate the α subunit of eIF2 to attenuate general translational initiation. More recently, we discovered that ISR inhibits mRNA translation through the induction of yet another translational inhibitor 4E-BP. At the same time, such conditions paradoxically stimulate the translation of transcription factors such as ATF4, due to the presence of regulatory upstream Open Reading Frames (uORFs) that precede the main ATF4 ORF. How stress responsive transcripts evade translational inhibition, or even undergo more active expression, in stressed cells is one of the major conceptual questions that remains poorly understood. Our preliminary studies using Drosophila have led us to a number of new insights to this question: These include our findings that (1) ISR boosts innate immune response to bacterial infection and anti-microbial peptides have 5’UTRs that can evade translational inhibition imposed by ISR signaling, (2) that previously unexpected factors regulate the activation of ISR, and (3) that ATF6 also has a 5’UTR that stimulates the main ORF translation in response to stress. Here I propose to use Drosophila to investigate the underlying regulatory mechanisms and determine how the newly identified ISR regulatory factors affect innate immune response, inflammation, and lifespan of Drosophila. We will supplement the molecular genetics-based approach with genomic tools such as ribosome profiling and structure-based modeling studies. Three Specific Aims will be pursued: (1) We will determine how ISR signaling enhances innate immune response, mainly focusing on the idea that anti-microbial peptide transcripts undergo mRNA translation through an unconventional mechanism to evade translational inhibition associated with ISR signaling. (2) Through the characterization of the novel ISR regulators that we have identified, we plan to determine how uORF containing transcripts increase their translation when general mRNA translation is suppressed, and examine how they affect phenotypes associated with abnormal ISR regulation. (3) We will test the hypothesis that ATF6 is another transcription factor that is regulated at the level of mRNA translation during ISR to mediate its transcriptional response. Notably, impairment or excessive stimulation of this pathway underlies various neurodegenerative and metabolic disorders in humans. Therefore, a better understanding of the regulatory mechanisms will not only advance our conceptual understanding of gene expression regulation in cells under stress but also may prompt the development of new strategies to modulate ISR signaling for therapeutic purposes.