Akt, cellular senescence, and lifespan

寿命和能量代谢之间的耦合被很好地记录下来，并且限制卡路里 表明可以延长多种生物体的寿命。线虫和苍蝇的遗传学研究 表明通过PI3K及其下游效应因子丝氨酸/苏氨酸损伤胰岛素信号 蛋白激酶Akt与能量新陈代谢下降和寿命延长有关。在线虫中， 决定寿命的胰岛素信号的最远端效应物是叉头转录因子DAF- 16，Akt通过磷酸化使其失活。因此，Akt活性降低会增加DAF-16活性 从而延长寿命。另一个保守的Akt下游效应因子，雷帕霉素的靶标 (Tor)，最近被认为与线虫和苍蝇的寿命调节有关。然而， Pisk/Akt信号通路在哺乳动物长寿中的作用尚未得到深入研究。 特别是，没有现有的遗传学证据支持这一途径在哺乳动物寿命中发挥作用。 这可能部分归因于该途径与一系列过程的关联，包括，细胞凋亡， 葡萄糖代谢和分化，这使评估其在调节哺乳动物中的作用变得复杂 长寿。我们的长期目标是确定Akt是否能够调节寿命和对氧化的敏感性 对小鼠的压力。小鼠有三种Akt亚型，由不同的基因(akt1、Akt2和akt3)编码。我们 建议利用我们的基因工程Akt缺陷小鼠的可用性 实验室。这些动物缺乏单独的AKT基因，无论是单独的还是组合的。他们提供了极好的 检测Akt活性及其个体Akt亚型贡献的遗传模型 长寿和氧化应激依赖的衰老和衰老。在细胞层面，我们将扩展我们的 初步观察发现，来自Akt(基因敲除)KO小鼠的细胞表现出较低的基础水平 细胞内活性氧(ROS)高于野生型，而细胞表达 激活Akt会产生更高的ROS水平。这些更改与 包括能量代谢和氧气消耗。我们将阐明Akt活性的机制 调节细胞内ROS的丰度，以及Akt在调节细胞衰老中的作用。在 生物体水平上，我们将确定部分消融是否会造成个体Akt活性的丧失 亚型，单独或组合，足以延长正常寿命，并赋予抗氧化性 老鼠的压力。

The coupling between lifespan and energy metabolism is well documented, and caloric restriction was shown to extend the lifespan of a wide spectrum of organisms. Genetics studies in nematodes and flies showed that impaired insulin signaling through PI3K and its downstream effector, the serine/threonine kinase, Akt, is associated with a decline in energy metabolism and an extended lifespan. In C. elegans, the most distal effector of insulin signaling that determines lifespan is the forkhead transcription factor, DAF- 16, which is inactivated by Akt via phosphorylation. Thus, reduced Akt activity increases DAF-16 activity and thereby increases lifespan. Another conserved downstream effector of Akt, the target of rapamycin (TOR), was recently implicated in the regulation of lifespan both in nematodes and flies. However, the contribution of the PISK/Akt signaling pathway to longevity in mammals has not been thoroughly explored. In particular, there is no extant genetic evidence supporting a role for this pathway in mammalian lifespan. This may be due, in part, to the association of this pathway with an array of processes including, apoptosis, glucose metabolism, and differentiation, which complicate evaluating its role in modulating mammalian longevity. Our long-term goal is to determine whether Akt can regulate lifespan and sensitivityto oxidative stress in mice. The mouse has three Akt isoforms encoded by distinct genes (aktl, akt2, and akt3). We propose to take advantage of the availability of genetically engineered Akt-deficient mice generated in our laboratory. These animals lack individual akt genes, alone and in combination. They provide excellent genetic models for examination of the contributions of Akt activity and individual Akt isoforms to longevity and oxidative-stress-dependent aging and senescence. At the cellular level, we will expand on our initial observations that cells derived from Akt (knockout) KO mice exhibit lower basal levels of intracellular reactive oxygen species (ROS) than their wild-type counterparts, whereas cells expressing activated Akt generate higher ROS levels. These changes are associated with corresponding changes in both energy metabolism and oxygen consumption. We will elucidate the mechanisms whereby Akt activity regulates intracellular ROS abundance and the role of Akt in the regulation of cellular senescence. At the organism level, we will determine whether partial ablation of Akt activity caused by the loss of individual isoforms, alone or in combination, is sufficient to extend normal lifespan and confer resistance to oxidative stress in the mouse.