Age-dependent regulation of clearance and signaling pathways

描述(由申请人提供)：随着我们年龄的增长，细胞缺陷会累积并促进有机体的衰老。在年轻个体中，保守的清除途径通过平衡新的生产和消除旧的成分来维持细胞的动态平衡。在年轻人中，营养/生长信号通路(即胰岛素和胰岛素样生长因子，IR/IGF)与下游成分如自噬和泛素-蛋白酶体系统(UPS)之间存在协调调节。这种平衡对于健康的衰老至关重要。通常情况下，上游信号通路会导致关键清除成分的表达谱发生变化，从而发生调控失调。这种脱节似乎在一定程度上是代谢综合征和II型糖尿病等疾病背后的分子基础。这些疾病的频率正在增加，并随着年龄的增长而加速，是帕金森和阿尔茨海默氏症等疾病的已知风险因素。我的研究重点是宏自噬(自噬)及其与神经元老化和蛋白质聚集体清除的作用。我们已经发现，自噬基因的表达随年龄的增长而下降，通过提高成年中枢神经系统中限速基因(即Atg8a)的信息水平，我们可以增加果蝇的总清除量和寿命超过50%。我们还发现，IR信号的缺陷对果蝇的寿命有深刻的影响，并增强了老化神经组织的自噬。其他清除途径，如UPS，随着年龄的增长显示出深刻的功能变化，也在一定程度上受到代谢信号的控制。这一设想的假设是，信号通路(如IR、TOR)和清除通路(如UPS、自噬)中的关键成分的表达谱会随着年龄的变化而改变。这种调控上的脱节反过来又会限制有效去除细胞损伤所需的因子的产生。一旦确定了其mRNA谱随年龄变化的基因，我们将使用果蝇遗传/转基因技术优先操纵它们的表达谱至更年轻的模式，并单独评估它们的“抗衰老”特性。对于特定的目标1，我们将使用下一代测序、微阵列和qRT-PCR技术来确定年轻和老年神经和肌肉组织的转录组谱。在具体目标2中，我们将使用果蝇遗传/转基因技术来改变选定基因的表达谱，并表征它们对年龄相关表型的影响。具体目标3将涉及描述不同年龄果蝇的转录组特征，这些果蝇具有IR/IGF或自噬基因的特定突变或转基因改变。特定目标4将扩大转录组图谱的分析范围，以包括来自老年哺乳动物组织的样本。这项提议的目的是阐明清除途径在细胞衰老中的作用，并确定可能对人类衰老和神经退行性疾病产生深远影响的保守基因。

DESCRIPTION (provided by applicant): As we age cellular defects accumulate and promote aging of an organism. Conserved clearance pathways, in young individuals maintain cellular homeostasis, through balancing new production with the elimination of old components. In the young there is coordinated regulation between nutritional/growth signaling pathways (i.e. Insulin and Insulin-like Growth Factor, IR/IGF) with downstream components such as autophagy and the ubiquitin-proteasome system (UPS). This balance is essential for healthy aging. Often dysregulation occurs with upstream signaling pathways leading to altered expression profiles of key clearance components. This disconnect appears in part to be the molecular underpinnings behind diseases like metabolic syndrome and type-II diabetes. These disorders are increasing in frequency, accelerate with age and are known risk factors for disorders such as Parkinson and Alzheimer's diseases. My research has focused on macroautophagy (autophagy) and its role with neuronal aging and the clearance of protein aggregates. We have found there is an age-dependent decline in autophagy gene expression and by enhancing message levels of rate-limiting genes (i.e. Atg8a) in the adult CNS we can increase aggregate clearance and the Drosophila lifespan by over 50%. We have also found that defects in the IR signaling have a profound effect on fly longevity and enhance autophagy in aging neural tissues. Other clearance pathways, such as UPS show a profound functional change with age, and are also partly under the control of metabolic signaling. The hypothesis of this proposal is that expression profiles of key components in signaling (i.e. IR, TOR) and clearance (i.e. UPS, autophagy) pathways will be altered with age. This regulatory disconnect, in turn will limit the production of factors required for the effective removal of cellular damage. Once genes are identified that have age-dependent changes to their mRNA profiles; we will use Drosophila genetic/transgenic techniques to preferentially manipulate their expression profiles to a more "youthful" pattern and individually assess their "anti-aging" properties. For Specific Aim 1 we will use Next Generation Sequencing, Microarray and qRT-PCR techniques to determine the transcriptome profiles of young and old neural and muscle tissues. In Specific Aim 2 we will use Drosophila genetic/transgenic technique to alter the expression profiles of select genes and characterize their effect on age-dependent phenotypes. Specific Aim 3 will involve characterizing transcriptome profiles from flies at different ages that have specific mutations or transgenic alterations to IR/IGF or autophagy genes. Specific Aim 4 will extend the analysis of transcriptome profiles to include samples from aged mammalian tissues. The goal of this proposal is to clarify the role that clearance pathways have in cellular aging and to identify conserved genes that could have a profound effect on human aging and neurodegenerative disorders.