Lifespan extension by differential translation mediated by eIF-4G in C. elegans

描述(申请人提供)：尽管抑制翻译启动延长了从酵母到哺乳动物的寿命，但其机制仍不清楚。我们发现，最有效的寿命延长之一来自于抑制IFG-1，IFG-1是线虫真核细胞翻译起始因子(EIF)-4G的同源基因，IFG-1是一种正向调节翻译的因子。以前的研究已经分析了总mRNA表达的变化，以探讨在一些不同的遗传和环境条件下寿命变化的原因。然而，其他研究表明，转录组和蛋白质组之间存在很大的差异。我使用翻译状态阵列分析(TSAA)，它解释了转录后处理，以研究通过抑制IFG-1表达而直接调节翻译时的变化。发现了大量差异翻译的mRNAs，本体论分析表明，上调的基因包括应激反应基因和衰老基因，它们是衰老的正向调节基因。初步的序列分析表明，优先保持表达的基因包含已知的调节翻译的保守特征。QRT-PCR和定量质谱学证实了TSAA的结果。假设：除了降低整体的翻译速率外，抑制IFG-1还导致与应激反应和基于mRNA组成的躯体维持相关的mRNA的优先翻译。对50个翻译增强的应激反应基因的上位性筛选显示，当IFG-1被抑制时，最大限度延长寿命所需的10个基因。我打算a)使用体内报告结构直接确定这七个基因的翻译变化和过度表达的影响，b)分析已知或新的顺式调节元件的序列，并分离与差异翻译的mRNAs相关的microRNAs(MiRNAs)，以及c)表征miRNA和顺式调节元件在不同条件之间的作用以及它们在寿命调节7中的作用。 与公共卫生相关：禁止翻译延长了不同物种的寿命。线虫等简单的模式生物提供了强大的工具来揭示决定翻译抑制的有益影响的生物学机制。利用线虫，我将研究如何通过线虫真核翻译起始因子4G的同源抑制翻译起始后转录后加工。鉴于取消翻译管制在糖尿病、癌症和神经变性等与年龄相关的疾病中所起的作用，这项研究对人类健康具有重要意义。

DESCRIPTION (provided by applicant): Although inhibition of translation initiation extends lifespan from yeast to mammals, the mechanism remains unknown. We showed that one of the most robust lifespan extension comes from suppression of ifg-1, the C. elegans ortholog of eukaryotic translation initiation factor (eIF)-4G, a factor that positively regulates translation. Previous studies have analyzed changes in total mRNA expression to investigate causes of lifespan changes under a number of different genetic and environmental conditions. However, other studies have shown large discrepancies between the transcriptome and proteome. I used translation state array analysis (TSAA), which accounts for post-transcriptional processing, to investigate changes upon direct modulation of translation by inhibiting ifg-1 expression. A large number of differentially translated mRNAs were found and ontological analysis revealed that upregulated genes included stress response genes and aging genes that are positive regulators of aging. Preliminary sequence analysis suggests that genes with preferentially maintained expression contain conserved characteristics known to modulate translation. qRT- PCR and quantitative mass spectroscopy corroborate TSAA results. Hypothesis: in addition to reducing global rates of translation, suppression of ifg-1 results in preferential translation of mRNA associated with stress response and somatic maintenance based on mRNA composition. An epistasis screen of 50 translationally enhanced stress response genes showed 10 that are required for maximal lifespan extension when ifg-1 is inhibited. I intend to a) directly determine translation changes and the impact of overexpression for these seven genes using in vivo reporter constructs, b) analyze sequences for known or novel cis- regulatory elements and isolate microRNAs (miRNAs) associated with differentially translated mRNAs, and c) characterize the miRNA and cis-regulatory elements for their effects between conditions as well as their roles in lifespan modulation 7. PUBLIC HEALTH RELEVANCE: Inhibition of translation extends lifespan across species. Simple model organisms like the nematode C. elegans provide powerful tools to uncover biological mechanisms that determine the beneficial effects of translation inhibition. Using C. elegans, I will examine how post-transcriptional processing is remodeled upon inhibition of translation initiation through the C. elegans ortholog of eukaryotic translation initiation factor 4G. Given the role played by deregulation of translation in age-related diseases including diabetes, cancer and neurodegeneration, this research has important implications for human health.