Defining the Mechanisms of genotype-dependent responses to caloric restriction

描述（由申请人提供）：热量限制已被证明可以延长从酵母到小鼠的生物体的寿命，最近有报道称可以降低恒河猴的年龄相关死亡率和疾病。目前正在积极开发模拟热量限制效果的药物，希望它们能被证明对人类各种与年龄有关的疾病有治疗作用。尽管这种热量限制模拟物具有潜在的益处，但在衰老相关研究中常用的每种模式生物中都有实例表明，特定的基因型变化可以阻断热量限制的长寿益处。一些遗传变异甚至会因热量限制而缩短寿命。然而，人们对这种依赖基因型的热量限制反应的机制知之甚少，目前也无法预测遗传异质群体（例如人类）中的个体将如何对热量限制做出反应。获得这样的理解是至关重要的热量限制模拟之前，可以应用于改善人类健康。该提案的目标是首先在芽殖酵母酿酒酵母中在全基因组范围内解决这个问题，其次将这些发现扩展到线虫秀丽隐杆线虫，第三开始鉴定和测试与酵母和线虫研究中鉴定的因子相对应的人类功能变体。这将通过确定1500个单基因缺失突变体对热量限制的复制寿命响应，定义对热量限制异常响应的遗传变体，并表征解释这些效应的分子机制来实现。将确定异常响应变体的线虫同源物，并对这些变体的子集进行实验，以确定在这两种差异很大的真核生物中，哪些基因型依赖的热量限制响应是保守的。还将鉴定人类同源物，并且在它们与酵母突变互补的情况下，将测试已知序列变体在对热量限制的响应中的功能意义。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.