The Sir2-p53-IGF link in mammalian life-span control

我们已经产生了一个转基因小鼠，其中过表达的短亚型的肿瘤抑制基因， p53（p44）导致健康和生命的过早丧失。我们打算描绘分子机制， 其增加的p44表达加速了该动物模型中的正常衰老过程。在特定 目的1，我们测试的假设，p44-p53比例的变化可以调节哺乳动物的寿命。 在这个目的中，我们描述了小鼠和人正常衰老过程中p44的表达 （实验1.1）并使用RNAi确定其在全长p53的背景下与衰老速率的相关性 实验1.2）和动物中p44缺陷型p53等位基因（实验1.3）以操纵p44 程度.在《特定目的2》中，我们检验了p53通过偶联调节小鼠寿命的假设。 Sir 2和IGF-1通路。在这个目的中，我们提出了一系列的生化实验来阐明 p44可能干扰p53和Sir 2之间相互作用的分子机制，包括 改变p53与其已知结合配偶体的相互作用（实验2.1）; 翻译修饰，包括磷酸化和乙酰化/脱乙酰化（实验2.2）; 改变p53的亚细胞定位（实验2.3）;以及，干扰p53的组装或功能。 依赖性转录复合物（实验2.4）。如果p53是Sir 2a和IGF信号之间的联系， 鼠标，然后p44解开链接，这个链接如何正常运作的线索在于为什么它是非- 当p44过量时起作用。最后，在具体目标3中，我们检验了Igf-1 受体是p44改变哺乳动物健康和寿命的主要下游效应物。在这 目的是，我们利用小鼠遗传学的力量来确定在细胞中改变的Igf-1受体， p44纯合转基因小鼠的组织，是介导这种疾病中健康和生命损失的关键成分。 哺乳动物系统由于该基因是IGF-1信号转导的关键第一步，因此本研究重点关注 p53和信号通路的相互作用，在寿命决定中起着重要作用， 生物，如C. elegans和D.黑腹菌

We have generated a transgenic mouse in which over-expression of the short isoform of the tumor suppressor p53 (p44) results in the premature loss of health and life. We intend to delineate the molecular mechanism by which increased p44 expression accelerates the process of normal aging in this animal model. In SPECIFIC AIM 1, we test the hypothesis that a change in the p44-to-p53 ratio can modulate mammalian longevity. In this Aim, we characterize the expression of p44 during normal aging in both mouse and human (Experiment 1.1) and determine its relevance in the context of full-length p53 to the rate of aging using RNAi in cells (Experiments 1.2) and a p44-deficient p53 allele in animals (Experiment 1.3) to manipulate p44 levels. In SPECIFIC AIM 2, we test the hypothesis thatp53 modulates life-span in the mouse by coupling the Sir2 and IGF-1 pathways. In this Aim, we propose a series of biochemical experiments to elucidate the molecular mechanism by which p44 might interfere with the interaction between p53 and Sir2, including altering the interaction of p53 with its known binding partners (Experiment 2.1); altering p53 post- translational modifications, including phosphorylation and acetylation/deacetylation (Experiment 2.2); altering p53 sub-cellular localization (Experiment 2.3); and, interfering with the assembly or function of p53- dependent transcription complexes (Experiment 2.4). If p53 is the link between Sir2a and IGF signaling in the mouse, then p44 uncouples the link, and the clues to how this link functions normally lie in why it is non- functional when p44 is in excess. Finally, in SPECIFIC AIM 3, we test the hypothesis that the Igf-1 receptor is theprincipal downstream effector by which p44 alters mammalian health- and life-span. In this aim, we exploit the power of mouse genetics to determine if the Igf-1 receptor, which is altered in cells and tissues ofp44 homozygous transgenic mice, is the key component mediating the loss of health and life in this mammalian system. Because this gene is the critical first step in IGF-1 signal transduction, this Aim focuses on the interactionof p53 and the signalingpathway that plays a major role in life-span determination in lower organisms, such as C. elegans and D. melanogaster.