Adaptation to Extracellular Acidosis by pH-Sensing eIF5A

项目摘要 全系统蛋白质合成重塑是细胞应激适应的重要组成部分。最近， 重要的研究支持这样的观察，即全球翻译适应(例如，翻译效率 重塑和替代翻译机制)通常比转录控制和信使核糖核酸 控制蛋白质输出的水平。这种现象在进化、发展、 分化，特别是在细胞适应生理刺激的过程中。胞外酸化 环境(细胞外酸中毒)是厌氧代谢的结果，常见于 肿瘤。我们和其他人已经证明，细胞外酸中毒导致癌细胞休眠，这是一个谜 表型与缺血耐受和癌症对放化疗的耐受有关。一个重要的 问题仍然是：实现翻译适应的感知机制和资产是什么 在细胞内对细胞外pH的变化做出反应。利用我们新开发的，不偏不倚的生物活动- 基于MATRIX平台，我在这项资助计划中介绍了“酸性蛋白质合成设备”。在这些人中 有趣的是，由Matrix，eIF5A确定的富含酸中毒的翻译因子是唯一可以 可以追溯到最后一个通用的共同祖先，它被认为完全依赖于厌氧 新陈代谢。我将提供证据证明eIF5A作为一种pH传感传感器运行，这对 专门的蛋白质合成机制，促进酸中毒诱导的肿瘤细胞休眠。我将揭晓独一无二的 来自人类癌细胞系的酸中毒特异性生物标记物。根据这些初步数据，我 假设eIF5A是一种pH敏感转导，通过 翻译机重新编程。我们计划通过以下具体目标来检验这一假设：1-发现 适应性的，酸中毒特异性的翻译组；2-表征eif5A在细胞对酸中毒适应中的作用。 细胞外酸中毒是一种常见但在很大程度上未被探索的刺激，在一系列病理环境中观察到， 包括癌变的肿瘤微环境。这项提议是创新的，因为它将发现：1-细胞外 PH值敏感的蛋白质合成机制2--酸性人类癌细胞中的一项重要功能 EIF5A，3-癌细胞对细胞外pH变化的翻译组，酸中毒的4组(S)- 可用于诊断和/或预测实验性和慢性酸中毒状态的特定蛋白质标记物 人类临床样本；5.细胞休眠与缺血耐受和抵抗有关的机制 以维持抗癌治疗。

Project Summary System-wide remodeling of protein synthesis is an important component of cellular stress adaptation. Recent, important studies support the observation that global translational adaptations (e.g. translation efficiency remodeling and alternative translation machineries) often predominate over transcriptional control and mRNA levels in controlling protein output. This phenomenon has been observed during evolution, development, differentiation, and especially during cellular adaptations to physiological stimuli. Acidification of the extracellular environment (extracellular acidosis) as a consequence of anaerobic metabolism is frequently observed in tumors. We, and others, have shown that extracellular acidosis induces cancer cell dormancy, an enigmatic phenotype involved in ischemic tolerance and cancer resistance to radiation and chemotherapy. An important question remains regarding: what are the sensing mechanisms and assets that enable translational adaptations in cells responding to variations in extracellular pH. Using our newly-developed, unbiased, biological activity- based MATRIX platform, I introduce in this grant proposal the “Acidotic Protein Synthesis Machinery”. Amongst the acidosis-enriched translation factors identified by MATRIX, eIF5A is, interestingly, the only one that can be traced back to the last universal common ancestor, which is believed to have relied exclusively on anaerobic metabolism. I will provide evidence that eIF5A operates as a pH-sensing transducer that is essential for the specialized protein synthesis machinery that facilitates acidosis-induced tumor cell dormancy. I will reveal unique acidosis-specific biomarkers derived from human cancer cell lines. Based on these preliminary data, I hypothesize that eIF5A is a pH-sensing transducer that drives tumor cell adaptation to acidosis via translatome reprogramming. We plan to test this hypothesis with the following specific aims: 1- Uncovering the adaptive, acidosis-specific translatome; 2- Characterize the role of eif5A in cellular adaptation to acidosis. Extracellular acidosis is a frequent but largely unexplored stimulus observed in an array of pathological settings, including cancerous tumor microenvironments. The proposal is innovative as it will discover: 1- an extracellular pH-sensing protein synthesis machinery, 2- an essential function in acidotic human cancer cells for the ancient eIF5A, 3- the translatome of cancer cells responding to variations in extracellular pH, 4- panel(s) of acidosis- specific protein markers that can be used to diagnose and/or prognose the acidotic state in experimental and human clinical samples; and 5- mechanisms of cellular dormancy involved in ischemic tolerance and resistance to mainstay anti-cancer therapy.