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

6.项目摘要/摘要 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 仍然不为人知。我们发现，最有力的寿命延长之一来自于抑制IFG-1， 线虫真核细胞翻译起始因子4G的同源基因--正向调节因子 翻译。以前的研究已经分析了总mRNA表达的变化，以调查原因 在许多不同的遗传和环境条件下，寿命会发生变化。然而，其他研究 已经显示出转录组和蛋白质组之间的巨大差异。我使用了转换状态数组 分析(TSAA)，这解释了转录后处理，以调查直接 通过抑制IFG-1的表达来调节翻译。大量差异翻译的mRNA被 发现和本体论分析表明，上调的基因包括应激反应基因和衰老 对衰老有积极调节作用的基因。初步的序列分析表明， 优先维持的表达包含已知调节翻译的保守特征。QRT- 聚合酶链式反应和定量质谱学证实了TSAA的结果。假设：除了减少 全局翻译速率，抑制IFG-1导致相关mRNA的优先翻译 以mRNA组成为基础的应激反应和躯体维持。50的上位性筛选 翻译增强的应激反应基因显示了最大限度延长寿命所需的10个基因 当IFG-1被抑制时。我打算a)直接确定翻译更改和过度表达的影响 对于这七个基因，使用体内报告构建，b)分析已知或新的顺式- 调控元件和分离与差异翻译的mRNAs相关的microRNAs(MiRNAs)，以及c) 描述miRNA和顺式调控元件在条件之间的作用以及它们的作用 在寿命调节方面。

6. Project Summary / Abstract 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 preferrentially 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.