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

描述（由申请人提供）：饮食限制（DR），或在没有营养不良的情况下限制食物摄入，已知可以预防几种与年龄相关的疾病，并延长许多生物（包括哺乳动物）的寿命。然而，这一令人着迷的现象背后的细胞和分子机制仍然知之甚少。我们最近发现了秀丽隐杆线虫自噬过程在DR诱导的寿命延长中的关键作用（Hansen et al., PLoS Genetics, 2008）。自噬是细胞成分降解和循环利用的一种保守途径。具体来说，我们发现自噬在DR的诱导下被诱导，这种诱导依赖于FOXA转录因子PHA-4，这是一种已知的DR诱导长寿的调节因子。因此，我们和其他人发现，这些动物长寿需要几个在自噬中起作用的基因。虽然这些研究建立了自噬与DR长寿反应之间的重要联系，但没有解决DR如何在细胞和分子水平上诱导自噬以延长生物体的寿命。特别是，目前尚不清楚自噬过程如何促进组织衰老，哪些组织是关键的，以及哪些信号机制参与选择细胞成分作为响应DR的降解的cargo。本应用程序的目标是使用遗传和生化方法来表征在哪些组织自噬转换被诱导影响成年秀丽隐杆线虫遭受DR的寿命。以及确定对寿命有影响的自噬的新调节因子。具体而言，在Aim 1中，我们将使用TEM等成像技术并开发新的荧光报告器来检测衰老蠕虫不同组织中的自噬事件<以及细胞质货物>的身份。在目标2中，我们将研究组织自噬基因在哪些功能中调节寿命，例如，通过组织特异性的过表达实验。最后，在Aim 3中，我们将描述自噬通过DR增加寿命的遗传要求，并寻找新的自噬调节剂，包括生物化学和遗传筛选中自噬货物识别的重要因素。在这些研究中，我们将把DR长寿模型与其他同样依赖自噬来延长寿命的长寿途径进行比较，包括daf-2/胰岛素/IG-1信号通路。像DR一样，自噬在许多疾病中起着关键作用，包括与年龄相关的疾病，如癌症和神经变性。了解秀丽隐杆线虫等多细胞生物中自噬的调控以及自噬与DR之间的保守机制，不仅可能为研究衰老提供新的重要见解，还可能有助于开发此类年龄相关疾病的治疗方法。

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.