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

6.项目概要/摘要 虽然抑制翻译起始可以延长从酵母到哺乳动物的寿命， 仍然未知。我们发现，最有效的寿命延长来自ifg-1的抑制， 梭真核生物翻译起始因子（eIF）-4G的直系同源物，一种正调节 翻译.以前的研究分析了总mRNA表达的变化，以调查 寿命在许多不同的遗传和环境条件下发生变化。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。我用了转换状态数组 TSAA分析（TSAA），它解释了转录后加工，以调查直接 通过抑制IFG-1表达调节翻译。大量的差异翻译的mRNA， 发现和本体论分析显示，上调的基因包括应激反应基因和衰老基因， 这些基因是衰老的积极调节因子。初步的序列分析表明， 优选维持的表达含有已知调节翻译的保守特征。qRT-的 PCR和定量质谱证实了TSAA结果。假设：除了减少 在总体翻译速率方面，ifg-1的抑制导致mRNA相关的优先翻译。 与应激反应和基于mRNA组成的体细胞维持有关。50的上位性筛选 增强应激反应基因显示10个是最大限度延长寿命所必需的 当IFG-1被抑制时。我打算a）直接确定翻译变化和过表达的影响 对于这七个基因，使用体内报告构建体，B）分析已知或新的顺式- 调节元件和与差异翻译的mRNA相关的分离的微小RNA（miRNA），和c） 表征miRNA和顺式调控元件在条件之间的作用以及它们的作用 在寿命调制中。

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.