Autophagy and dietary restriction mechanisms in the C. elegans model of aging

描述(申请人提供)：饮食限制(DR)，即在没有营养不良的情况下限制食物摄入量，已知可以预防几种与年龄相关的疾病，并延长许多生物体的寿命，包括哺乳动物。然而，这种令人着迷的现象背后的细胞和分子机制仍然知之甚少。我们最近确定了自噬过程在线虫博士诱导的寿命延长中的关键作用(Hansen等人，PLoS Genetics，2008)。自噬是一种保守的途径，通过它细胞成分被降解和循环。具体地说，我们发现自噬是对DR的反应而诱导的，这种诱导依赖于FOXA转录因子PHA-4，它是DR诱导寿命的已知调节因子。因此，我们和其他人发现，这些动物长寿需要几个具有自噬功能的基因。虽然在自噬和对DR的长寿反应之间建立了重要的联系，但这些研究没有解决DR如何在细胞和分子水平上诱导自噬来延长生物体的寿命。特别是，目前尚不清楚自噬过程是如何促进组织衰老的，因为哪些组织是关键的，以及什么信号机制参与了选择细胞成分作为降解货物以响应DR。这项应用的目标是使用遗传和生化方法来表征哪些组织自噬翻转被诱导影响成年线虫的寿命，以及识别新的自噬调节因子对寿命的影响。具体地说，在目标1中，我们将使用像电子显微镜这样的成像技术，并开发新的荧光报告程序来检测自噬事件以及老化蠕虫不同组织中细胞质货物的身份。在目标2中，我们将检查自噬基因在哪些组织中发挥调节寿命的功能，例如，通过组织特异性的过度表达实验。最后，在目标3中，我们将描述通过DR延长寿命的自噬的遗传要求，并寻找新的自噬调节器，包括在生化和遗传筛选中识别自噬货物的重要因素。在这些研究中，我们将把DR长寿模型与类似地依赖自噬来延长寿命的其他长寿途径进行比较，包括daf-2/胰岛素/IG-1信号途径。像DR一样，自噬在许多疾病中发挥着关键作用，包括癌症和神经退化等与年龄相关的疾病。了解自噬的调节以及线虫等多细胞生物体中自噬和DR之间的保守机制可能不仅为研究衰老提供新的重要见解，而且有助于开发此类与年龄相关的疾病的治疗方法。

DESCRIPTION (provided by applicant): Dietary restriction (DR), or limited food intake without malnutrition, is known to protect against several age- related disorders and extends lifespan in many organisms, including mammals. However, the cellular and molecular mechanisms underlying this fascinating phenomenon remain poorly understood. We recently identified a critical role for the process of autophagy in the lifespan extension induced by DR in C. elegans (Hansen et al., PLoS Genetics, 2008). Autophagy is a conserved pathway by which cellular components are degraded and recycled. Specifically, we found that autophagy is induced in response to DR, and this induction is dependent on the FOXA transcription factor PHA-4, a known regulator of DR-induced longevity. Accordingly, we and others have found that several genes with functions in autophagy are required for these animals to live long. While establishing an important link between autophagy and the longevity response to DR, these studies did not address how DR induces autophagy at the cellular and molecular level to extend the lifespan of the organism. In particular, it remains unknown how the autophagy process contributes to organismal aging in terms of which tissues are critical, and what signaling machinery is engaged to select cellular components as cargo for degradation in response to DR. The goal of this application is to use genetic and biochemical approaches to characterize in which tissues autophagic turn-over is induced to affect longevity in adult C. elegans subjected to DR, as well as to identify novel regulators of autophagy with effects on longevity. Specifically, in Aim 1, we will use imaging techniques like TEM and develop new fluorescent reporters to detect autophagic events <as well as the identity of the cytoplasmic cargo> in different tissues of aging worms. In Aim 2, we will examine in which tissues autophagy genes functions to modulate longevity, e.g., by tissue-specific, over-expression experiments. Finally, in Aim 3, we will characterize the genetic requirements for autophagy to increase lifespan by DR, and search for new modulators of autophagy, including factors important for autophagic cargo recognition in biochemical and genetic screens. Throughout these studies we will compare the DR longevity model to other longevity pathways that similarly rely on autophagy to extend lifespan, including the daf-2/insulin/IG-1 signaling pathway. Like DR, autophagy plays critical roles in many diseases, including age-related disorders like cancer and neurodegeneration. Understanding the regulation of autophagy and the conserved mechanisms linking autophagy and DR in multicellular organisms like C. elegans are likely to provide new important insights not only into aging but also help developing treatments for such age-related diseases.