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

描述（由申请人提供）：已知饮食限制（DR）或限制食物摄入而不营养不良可预防几种与年龄相关的疾病，并延长许多生物体（包括哺乳动物）的寿命。然而，这种迷人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C.秀丽线虫（汉森等人，PLoS Genetics，2008）。自噬是细胞成分降解和再循环的保守途径。具体地说，我们发现自噬是响应于DR而诱导的，并且这种诱导依赖于FOXA转录因子PHA-4，这是一种已知的DR诱导寿命的调节因子。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，但这些研究并没有解决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，它仍然是未知的自噬过程如何有助于生物体老化的组织是至关重要的，以及什么信号机制参与选择细胞成分作为货物降解响应DR。本申请的目标是使用遗传和生化方法来表征组织自噬翻转诱导影响寿命在成年C。elegans遭受DR，以及确定新的自噬调节因子对寿命的影响。具体来说，在目标1中，我们将使用TEM等成像技术并开发新的荧光报告分子来检测<as well as the identity of the cytoplasmic cargo>老化蠕虫不同组织中的自噬事件。在目标2中，我们将研究自噬基因在哪些组织中起调节寿命的作用，例如，通过组织特异性过度表达实验。最后，在目标3中，我们将描述自噬的遗传要求，以通过DR增加寿命，并寻找新的自噬调节剂，包括在生化和遗传筛选中对自噬货物识别重要的因素。在这些研究中，我们将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。 与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。了解自噬的调控以及自噬和DR在多细胞生物中的保守机制，如C。秀丽线虫可能不仅为衰老提供新的重要见解，而且还有助于开发此类与年龄有关的疾病的治疗方法。 公共卫生相关性：美国老年人口正在迅速增长，与年龄有关的疾病构成了我们社会的主要健康问题。然而，衰老和年龄相关疾病的细胞和分子基础知之甚少。这项提议旨在确定自噬-一种具有主要生物功能的细胞质降解过程-如何调节生物体衰老。这项拟议的研究与公共卫生有关，因为要研究的机制是进化保守的，研究结果可能最终提供治疗衰老相关疾病的疗法。

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. PUBLIC HEALTH RELEVANCE: The US population of elderly people is rapidly growing and age-related diseases constitute a major health issue in our society. However, the cellular and molecular basis of aging and age-related disorders is poorly understood. This proposal aims to determine how autophagy - a cellular process of cytoplasmic degradation with major biological functions - modulates organismal aging. The proposed research has relevance to public health, because the mechanisms to be investigated are evolutionary conserved and the findings might ultimately provide therapies to treat aging-related diseases.