Age-dependent regulation of clearance and signaling pathways

描述（由申请人提供）：随着年龄的增长，细胞缺陷会积累并促进生物体的衰老。在年轻个体中，保守的清除途径通过平衡新的产生与旧组分的消除来维持细胞内稳态。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）与下游组分（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老龄化至关重要。通常，上游信号传导途径发生失调，导致关键清除组分的表达谱改变。这种脱节似乎部分是代谢综合征和II型糖尿病等疾病背后的分子基础。这些疾病的发生频率增加，随着年龄的增长而加速，并且是帕金森病和阿尔茨海默病等疾病的已知风险因素。我的研究主要集中在自噬（macroautophagy）及其在神经元衰老和蛋白质聚集体清除中的作用。我们已经发现自噬基因表达存在年龄依赖性下降，并且通过提高成年CNS中限速基因（即Atg 8a）的信息水平，我们可以增加聚集体清除率和果蝇寿命超过50%。我们还发现IR信号传导的缺陷对果蝇寿命有深远的影响，并增强了衰老神经组织中的自噬。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，也部分受到代谢信号的控制。该建议的假设是，信号传导（即IR，TOR）和清除（即UPS，自噬）途径中的关键组分的表达谱将随着年龄而改变。这种监管脱节反过来又会限制有效消除细胞损伤所需的因子的产生。一旦基因被确定，具有年龄依赖性的变化，他们的mRNA谱，我们将使用果蝇遗传/转基因技术，优先操纵他们的表达谱更“年轻”的模式，并单独评估其“抗衰老”的属性。对于特定目标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择基因的表达谱，并表征其对年龄依赖性表型的影响。具体目标3将涉及表征不同年龄的果蝇的转录组谱，这些果蝇具有IR/IGF或自噬基因的特定突变或转基因改变。具体目标4将扩展转录组谱分析，以包括来自老年哺乳动物组织的样本。该提案的目标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。 公共卫生相关性：控制衰老的细胞过程是高度保守的，在蠕虫、苍蝇和人类之间有着惊人的相似之处。通过确定哪些基因对健康衰老至关重要以及它们如何受到调节，我们将更好地了解控制人类衰老和神经退行性变的细胞过程。这种理解将作为预防或治疗II型糖尿病、代谢综合征和阿尔茨海默病等疾病的基础。

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. PUBLIC HEALTH RELEVANCE: The cellular processes that control aging are highly conserved and share striking similarities between worms, flies and humans. By identifying which genes are critical for healthy aging and how they are regulated, we will better understanding the cellular processes that control human aging and neurodegeneration. This understanding will serve as the basis for the prevention or treatment of disorders such as type-II diabetes, metabolic syndrome and Alzheimer's disease.