Mechanisms of Aging in C elegans

描述（由申请人提供）：我们使用线虫，秀丽隐杆线虫，作为衰老的模型系统，因为它具有较短的寿命，强大的遗传工具包和许多已知的突变体可以延长寿命。我们的目标是识别年老动物和年轻动物中表达差异的基因，然后用这些基因作为分子标记来解剖衰老的机制。我们使用DMA微阵列进行全基因组筛选，以寻找在年老蠕虫、处于虚弱状态和两种寿命改变的胰岛素样信号突变体中改变表达的基因。通过结合这些DNA微阵列实验的表达结果，我们确定了一组733个核心基因，这些基因在不同的衰老实验中表现出一致的表达变化。有趣的是，我们发现年龄调节基因受GATA转录回路的调控，其中包括elt-3和egr-1 GATA转录因子。Elt-3（+）和egr-1（+）都能促进长寿，因为RNAi处理任何一个基因都会抑制daf-2突变体的长寿表型。此外，在正常衰老过程中，这两个基因的表达都会减少，并导致下游衰老靶基因的改变。从大量的衰老调控基因中，我们产生了一组GFP衰老报告基因，这将使我们能够在分子水平上研究衰老的过程。在具体的目标1中，我们将使用GFP衰老标记物的表达水平作为衰老的分子钟，使我们能够研究衰老机制，例如在不同组织中是否存在类似的衰老效应，以及GFP衰老标记物是否可以预测蠕虫在世时的剩余寿命。在具体的目标2中，我们将分析控制下游衰老标志物表达的elt-3和egr-1 GATA基因的功能。特别是，我们将测试是否可以通过减少或增加这两种衰老调节因子的表达来加速或减缓衰老的速度。在具体的目标3中，我们将研究elt-3/egr-1 GATA转录网络的上游控制，如胰岛素样信号通路的调节。此外，我们将确定该转录网络中与年龄相关的变化是由于外部因素（如细胞损伤）还是由于内在遗传途径（在发育过程中首先调节elt-3，并可能在衰老过程中继续调节elt-3）。

DESCRIPTION (provided by applicant): We are using the nematode, C. elegans, as a model system for aging because it has a short lifespan, a powerful genetic toolkit and many mutants are already known to lengthen lifespan. Our goal is to identify genes that are differentially expressed in old versus young animals, and then to use these genes as molecular markers to dissect apart mechanisms of aging. We used DMA microarray to perform genome-wide screens for genes that change expression in old worms, in the dauer state and in two insulin-like signaling mutants with altered lifespans. By combining the expression results from these DNA microarray experiments, we identified a core set of 733 genes that show consistent changes in expression across different aging experiments. Interestingly, we discovered that the age-regulated genes are regulated by a GATA transcriptional circuit involving the elt-3 and egr-1 GATA transcription factors. Elt-3(+) and egr-1 (+) both promote longevity since RNAi treatment of either gene suppresses the longevity phenotype of daf-2 mutants Furthermore, expression of both genes decrease during normal aging, and causes changes in downstream aging target genes. From the large set of aging-regulated genes, we have generated a set of GFP aging reporter genes that will allow us to examine the process of aging at the molecular level. In specific aim 1, we will use expression levels of the GFP aging markers as molecular clocks for aging, allowing us to study aging mechanisms such as whether there is a similar effect of aging in different tissues, and whether the GFP aging markers can predict the remaining life spans of worms while they are still alive. In specific aim 2, we will analyze the functions of the elt-3 and egr-1 GATA genes that control expression of the downstream aging markers. In particular, we will test whether we can either speed up or slow down the rate of aging by decreasing or increasing expression of these two aging regulators. In specific aim 3, we will examine upstream control of the elt-3/egr-1 GATA transcriptional network, such as regulation by the insulin-like signaling pathway. In addition, we will determine whether age-related changes in this transcriptional network are due to extrinsic factors such as cellular damage or to an intrinsic genetic pathway that first regulates elt-3 during development and that might continue to regulate elt-3 during aging.