Defining the Mechanisms of genotype-dependent responses to caloric restriction

描述(由申请人提供)：卡路里限制已被证明可以延长从酵母到老鼠的生物体的寿命，最近有报道称，限制卡路里可以降低恒河猴的年龄相关死亡率和疾病。模仿卡路里限制效果的药物正在积极开发，希望它们能证明它们对人类各种与年龄相关的疾病具有治疗作用。尽管这种卡路里限制模拟有潜在的好处，但在与衰老相关的研究中常用的每个模式生物中都有例子表明，特定的基因变化可以阻止卡路里限制对长寿的好处。一些基因变异甚至会因为卡路里限制而缩短寿命。然而，人们对这种依赖于基因型的卡路里限制反应的机制知之甚少，而且目前还没有办法预测遗传异质性群体(如人类)中的个体将如何对卡路里限制做出反应。在卡路里限制模拟应用于改善人类健康之前，获得这样的理解是至关重要的。这项建议的目标是首先在萌芽酵母中解决基因组范围内的这个问题，其次将这些发现扩展到线虫，第三开始鉴定和测试与酵母和线虫研究中确定的因素相对应的人类功能变异。这将通过确定1500个单基因缺失突变体对卡路里限制的复制寿命反应，定义对卡路里限制异常反应的遗传变异，并表征导致这些影响的分子机制来实现。将确定异常反应变异体的线虫同源物，并将在这些变异体的子集上进行实验，以确定在这两个差异很大的真核生物中，哪些对卡路里限制的基因型相关反应是保守的。还将鉴定人类同源物，在它们补充酵母突变的情况下，将测试已知的序列变体在热量限制反应中的功能意义。通过这种方式，我们将开始深入了解基因型和对热量限制的反应之间的相互作用，以及这种相互作用背后的分子机制。

DESCRIPTION (provided by applicant): Caloric restriction has been shown to increase life span in organisms from yeast to mice and was recently reported to reduce age-related mortality and disease in the rhesus monkey. Drugs that mimic the effects of caloric restriction are actively being developed in the hopes that they will prove therapeutic toward a variety of age-related diseases in people. Despite the potential benefits of such caloric restriction mimetics, there are examples in each of the model organisms commonly used in aging-related research demonstrating that specific genotypic changes can block the longevity benefits of caloric restriction. Some genetic variants even have their life span shortened by caloric restriction. Little is known about the mechanisms underlying such genotype-dependent responses to caloric restriction, however, and there is currently no way of predicting how individuals in a genetically heterogenous population (such as humans) will respond to caloric restriction. Obtaining such an understanding is critically important before caloric restriction mimetics can be applied to improve human health. The goal of this proposal is first to address this question on a genome-wide scale in the budding yeast Saccharomyces cerevisiae, second to extend these findings to the nematode Caenorhabditis elegans, and third to begin identification and testing of human functional variants corresponding to factors identified fron the yeast and nematode studies. This will be accomplished by determining the replicative life span response of 1500 single- gene deletion mutants to caloric restriction, defining genetic variants that respond abnormally to caloric restriction, and characterizing the molecular mechanisms accounting for these effects. Nematode homologs of abnormally responding variants will be identified and experiments will be performed on a subset of these variants to determine which genotype-dependent responses to caloric restriction are conserved across these two widely divergent eukaryotes. Human homologs will also be identified and, in cases where they complement the yeast mutation, known sequence variants will be tested for functional significance in the response to caloric restriction. In this way, we will begin to gain insight into the interplay between genotype and the response to caloric restriction as well as the molecular mechanism that underlie this interplay.