Adaptation to Extracellular Acidosis by pH-Sensing eIF5A

项目摘要 蛋白质合成的全系统重构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 重塑和替代翻译机器）通常主导转录控制和mRNA 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期间。细胞外的酸化 环境（细胞外酸中毒）作为厌氧代谢的结果， 肿瘤的我们和其他人已经表明，细胞外酸中毒诱导癌细胞休眠，这是一个谜。 表型涉及缺血耐受性和癌症对放疗和化疗的抗性。一个重要 问题仍然是：什么是感知机制和资产，使翻译适应 在细胞响应细胞外pH值的变化。使用我们新开发的，公正的，生物活性- 基于MATRIX平台，我在这个基金申请中介绍了“酸性蛋白质合成机制”。之间 有趣的是，由MATRIX鉴定的酸中毒富集翻译因子eIF 5A是唯一一个可以被 可以追溯到最后一个普遍的共同祖先，据信它完全依赖于厌氧 新陈代谢.我将提供证据证明eIF 5A作为一种pH传感传感器，对细胞的生长至关重要。 促进酸中毒诱导的肿瘤细胞休眠的专门蛋白质合成机制。我将揭示独一无二的 来源于人癌细胞系的酸中毒特异性生物标志物。根据这些初步数据，我 假设eIF 5A是一种pH传感传感器，通过以下途径驱动肿瘤细胞适应酸中毒 翻译组重编程。我们计划测试这个假设与以下具体目标：1-发现 适应性酸中毒特异性翻译组; 2-表征eif 5A在细胞适应酸中毒中的作用。 细胞外酸中毒是一种常见的，但在很大程度上未探索的刺激观察到的一系列病理设置， 包括癌性肿瘤微环境。该建议是创新的，因为它将发现：1-细胞外 pH敏感蛋白质合成机制，2-一个重要的功能，在酸中毒的人类癌细胞的古代 eIF 5A，3-癌细胞对细胞外pH值变化的应答翻译组，4-酸中毒组- 可用于诊断和/或诊断实验性和非实验性中的酸中毒状态的特异性蛋白质标记物， 人临床样品;和5-参与缺血耐受性和抵抗性的细胞休眠机制 来支持抗癌治疗

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.