MOLECULAR GENETICS OF AGING IN C ELEGANS

本提案的重点是扩展和加深我们对秀丽隐杆线虫长寿命（Age）突变体预期寿命增加的机制的理解。这些突变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容易理解的一类是那些也会影响儿童发育和成人生存的突变体，它们会导致预期寿命增加两倍或更多。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显然参与信号转导。我们假设这个通路的正常功能是产生一个信号级联反应来应对外源压力。当发生改变时（例如发生在age-1或daf-2突变体中），细胞内激酶级联被破坏，导致各种下游效应分子的活性改变，从而增加对压力的反应和延长寿命。与这一预期一致，使用候选基因方法，我们已经确定了一个新基因（tkr-1），当过度表达时延长寿命。Tkr-1与先前发现的“老年基因”的不同之处在于：1)它不是通过突变发现的；2)过表达导致寿命延长。该基金的目的是测试和扩展tkr1和其他老年基因（age-1， daf-2等）在相同或互锁的信号转导途径中起作用的假设，这些信号转导途径决定了这些蠕虫对压力的反应能力，并且延长寿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，我们将结合遗传学，分子和候选基因方法，利用强大的遗传学和几乎完整的秀丽隐杆线虫基因组序列。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下游靶点的遗传和分子表征。

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.