MOLECULAR GENETICS OF AGING IN C ELEGANS

这项建议的重点是扩大和深化我们对线虫线虫长寿(Age)突变体预期寿命延长的机制的理解。这些突变体揭示了寿命延长和应对压力能力增强之间的密切关系。这些年龄突变体中最被理解的一类是那些也会影响Dauer发育和成年生存，导致预期寿命增加两倍或更多的人。该途径中的突变体，如AGE-1/daf 23(磷脂酰肌醇3‘激酶或PI3K)和daf-2明显参与信号转导。我们假设，这一途径的正常功能是产生一个信号级联反应，以响应外源压力。当改变时(如在AGE-1或daf-2突变体中发生)，细胞内的激酶级联被破坏，从而导致各种下游效应分子的活性改变，从而导致对压力的反应增强和寿命延长。与这一预期一致，使用候选基因方法，我们已经确定了一种新的基因(TKR-1)，当过度表达时，它可以延长生命。TKR-1与以前发现的“老年基因”的不同之处在于：(1)它不是通过突变来鉴定的；(2)过度表达会延长寿命。这笔赠款的目的是测试和扩展这一假设，即TKR-1和其他老年致病基因(AGE-1、DAF-2和其他)在相同或相互关联的信号转导途径中发挥作用，这些信号转导途径决定了这些蠕虫对压力的反应能力，以及延长生命的主要机制是通过增强对压力的抵抗力。为了实现这些目标，我们将结合遗传、分子和候选基因的方法，利用线虫强大的遗传学和几乎完成的基因组序列。我们提出了一套互补的方法来实现这些目标：TKR-1的分子表征和TKR-1下游靶标的遗传和分子表征。

The focus of this proposal is to extend and deepen our understanding of the mechanisms underlying the increased life expectancy of long-lived (Age) mutants in the nematode Caenorhabditis elegans. These mutants have revealed the intimate relationship between increased longevity and an increased ability to respond to stress. The best understood class of these Age mutants are those which also affect dauer development and adult survival, resulting in two-fold or more increases in life expectancy. Mutants in this pathway, such as age-1/daf 23 (phosphatidyl inositol 3' kinase or PI3K) and daf-2 are clearly involved in signal transduction. We hypothesize that a normal function of this pathway is to produce a signal cascade in response to exogenous stress. When altered (such as occurs in age-1 or daf-2 mutants), there is a disruption of an intracellular kinase cascade which leads to altered activity of a variety of downstream effector molecules that result in an increased response to stress and increased longevity. Consistent with this expectation, using candidate-gene approaches, we have identified a novel gene (tkr-1) that extends life when over expressed. tkr-1 differs from the previously identified "gerontogenes" in that 1) it was not identified by mutation and (2) over expression leads to extended longevity. The Aims of this grant are focused on testing and extending the hypothesis that tkr-1 and other gerontogenes (age-1, daf-2, and others) function in the same or interlocking signal-transduction pathways that determine the ability of these worms to respond to stress and that a major mechanism of life extension is through increased resistance to stress. To accomplish these Aims, we will combine genetic, molecular and candidate-gene approaches, taking advantage both of the powerful genetics, as well as the almost completed genomic sequence, of C. elegans. We propose complementary sets of approaches to achieve these objectives: Molecular characterization of tkr-1 and genetic and molecular characterization of downstream targets of tkr-1.