Mechanisms of Aging in C. elegans

描述（由申请人提供）：该提案涉及老化的内在机制，这些机制是固有的，并且总是在正常老化过程中发生。内在机制涉及一个内部时钟，它规定了正常老化期间的寿命。除了损伤积累外，最近还发现了C.被称为发育漂移。发育途径在年轻的成年人中建立，以指导不同组织的形成。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。发育漂变在概念上是新颖的，因为它提出了老年蠕虫与具有损伤积累的年轻蠕虫不同。相反，老年蠕虫具有内在的、程序化的差异，使它们更容易退化和死亡。该方案使用C。秀丽隐杆线虫作为模式系统，因为它只有短短两周的寿命和强大的遗传工具。DNA微阵列实验已经被用来定义衰老的分子特征，包括1254个在年轻和年老蠕虫之间表达不同的基因。七个转录因子先前已被确定为可能负责这些年龄相关的变化的候选人。所有七种转录因子都是不同组织（如肠和皮肤）发育的关键调节因子。该提案将使用ChIP SEQ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年龄变化。使用自动细胞谱系分析仪对表达GFP的蠕虫的图像进行分析的表达实验将用于从单个细胞中提取精确的表达数据。这些数据将显示七种转录因子的表达如何随年龄变化。转基因蠕虫将被设计成将老蠕虫转化为年轻蠕虫;具体来说，老蠕虫中七种衰老调节因子的表达将被改变，以类似于年轻蠕虫中发现的表达，然后使用寿命实验来测试将蠕虫转化为年轻状态是否有益。发展漂移假说的一个关键预测是，老年的变化应该类似于发展过程中发生的变化。这将通过发现在衰老过程中直接位于转录因子下游的基因网络是否与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.