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

描述（由申请人提供）：尽管抑制翻译起始可延长从酵母到哺乳动物的寿命，但其机制仍未知。我们发现，最强大的寿命延长来自ifg-1的抑制，C。真核生物翻译起始因子（eIF）-4G的直向同源物，该因子正调控翻译。以前的研究分析了总mRNA表达的变化，以研究在许多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差异。我使用翻译状态阵列分析（TSAA），它占转录后处理，研究通过抑制ifg-1表达直接调节翻译后的变化。大量的差异翻译的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基因，是老化的正调控因子。初步的序列分析表明，优先维持表达的基因含有已知调节翻译的保守特征。qRT-PCR和定量质谱证实了TSAA结果。假设：除了降低整体翻译速率之外，IFG-1的抑制导致与应激反应和基于mRNA组成的体细胞维持相关的mRNA的优先翻译。一项对50个应激反应基因的上位性筛选显示，当ifg-1被抑制时，10个基因是最大限度延长寿命所必需的。我打算a）使用体内报告构建体直接确定这七个基因的翻译变化和过表达的影响，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mRNA相关的微小RNA（miRNA），以及c）表征miRNA和顺式调节元件在条件之间的作用以及它们在寿命调节中的作用7。 公共卫生相关性：抑制翻译延长了物种的寿命。简单的模式生物如线虫C.线虫提供了强有力的工具来揭示决定翻译抑制有益效果的生物学机制。利用C.对于秀丽隐杆线虫，我将研究转录后加工在通过C.真核生物翻译起始因子4G的同源物。鉴于翻译失调在糖尿病、癌症和神经退行性疾病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.