Mechanisms of Aging in C. elegans

描述(申请人提供)：这项建议是关于衰老的内在机制，这是内在的，并总是发生在正常的衰老过程中。内在机制包括一个内部时钟，它规定了正常衰老过程中的寿命。除了损伤积累，最近在线虫体内发现了另一种内在衰老的机制，称为发育漂移。在年轻人体内建立了发育途径，以引导不同组织的形成。这些发育途径的关键调节因子在老年时会出现异常表达，导致下游基因表达的级联变化，对组织功能产生不利影响，并限制寿命。发育漂移在概念上是新奇的，因为它提出了老年蠕虫与具有损害积累的幼虫不同。相反，老虫有与生俱来的程序性差异，这使得它们更容易退化和死亡。这项提案使用线虫作为模型系统，因为它的两周寿命很短，而且遗传工具功能强大。DNA微阵列实验已经被用来定义衰老的分子特征，其中包括1254个在幼虫和老年虫之间表达不同的基因。七个转录因子此前已被确定为可能导致这些年龄相关变化的候选因子。所有七种转录因子都是不同组织发育的关键调节因子，如肠道和皮肤。这项提议将使用芯片序列实验来确定这些转录因子是否直接导致其下游基因的表达随着年龄的变化而变化。使用自动细胞谱系分析仪将表达GFP的蠕虫图像数字化的表达实验将被用于从单个细胞中提取准确的表达数据。这些数据将显示这七种转录因子的表达如何随着年龄的变化而变化。转基因蠕虫将被设计成将老虫转化为幼虫；具体地说，七种衰老调节因子在老虫中的表达将被改变，以类似于幼虫的表达，然后将使用寿命实验来测试将蠕虫转换为年轻状态是否有益。发育漂移假说的一个关键预测是，老年的变化应该类似于发育过程中发生的变化。这将通过找出在衰老过程中转录因子直接下游的基因网络是否与其在发育过程中的下游网络相同来进行测试。

DESCRIPTION (provided by applicant): This proposal is about intrinsic mechanisms of aging, which are inherent and always occur during the normal aging process. Intrinsic mechanisms involve an internal clock that specifies lifespan during normal aging. Besides damage accumulation, another mechanism for intrinsic aging has recently been found in C. elegans termed developmental drift. Developmental pathways are established in the young adult to guide the formation of different tissues. Key regulators of these developmental pathways become aberrantly expressed in old age, leading to a cascade of changes in expression of downstream genes that has detrimental effects on tissue function and that limits lifespan. Developmental drift is conceptually novel because it proposes that that old worms are not the same as young worms with damage accumulation. Rather, old worms have inherent, programmed differences that make them more susceptible to degeneration and death. This proposal uses C. elegans as a model system because of its short two week lifespan and powerful genetic tools. DNA microarray experiments have been used to define a molecular signature for aging that includes 1254 genes that differ in expression between young and old worms. Seven transcription factors have previously been identified as candidates that may be responsible for these age-related changes. All seven transcription factors are key regulators of development in diverse tissues, such as the intestine and the skin. This proposal will use ChIP SEQ experiments to determine whether these transcription factors are directly responsible for causing expression of their downstream genes to change with age. Expression experiments using an automatic cell lineage analyzer to digitize images of GFP-expressing worms will be used to extract precise expression data from individual cells. These data will show how expression of the seven transcription factors changes with age. Transgenic worms will be engineered to convert old worms into young worms; specifically, expression of the seven aging regulators in old worms will be altered to resemble expression found in young worms, and then lifespan experiments will be used to test whether converting worms to their younger state is beneficial. A key prediction of the developmental drift hypothesis is that changes in old age should resemble changes that occur during development. This will be tested by finding out if the network of genes directly downstream of a transcription factor during aging are the same as its downstream network during development.