Proteasome Function During Aging in Extraordinarily Long-Lived Naked Mole-Rats

描述(申请人提供)：受损或错误折叠的蛋白质通常发生在老化过程中。事实上，蛋白质功能障碍是许多与年龄相关的疾病的一个关键特征。因此，维持蛋白质质量控制可能是持续健康和延长寿命的核心。最长寿的啮齿动物，裸鼠[NMRS]，在其32年寿命的大部分时间里都保持着蛋白质的稳定和强健的健康。NMRS还表现出对环境应激源的显著抗性，并有效地保持蛋白质质量。自噬和蛋白酶体介导的降解[PMD]在细胞内蛋白质质量控制中都起着关键作用。我们在这里重点介绍PMD，因为它是清除氧化损伤蛋白质的关键因素，据报道，它会随着年龄的增长而下降。我们假设，在衰老过程中，NMRS在有丝分裂(如肝脏)、终末分化(脑、肌肉)和免疫反应(脾)组织中保持高效的PMD，这是由于蛋白酶体[PR]的固有特性和/或细胞内保护环境。我们在以下特定的目标中解决这一问题：目的1.评估PRS的结构和功能，特别是免疫蛋白酶体[IMPR]在衰老和体内氧化应激反应中的特定功能差异中的作用。我们假设NMRS的PRS非常适合有效地应对氧化应激，并预测这在一定程度上是由于IMPR的更丰富。我们将测量与年龄相关的和氧化应激诱导的PrS结构、功能容量和在不同组织中的细胞内分布的变化。我们的初步数据显示，核磁共振中ChTL和TL活性的比率是小鼠肝脏的2-5倍，并且PRS组装的多样性更高。我们希望在其他组织中发现类似的趋势，特别是在对药物诱导的氧化应激的反应中，并预测IMPR在保存PMD疗效方面的新作用。目的2.确定不同物种间的群体能力差异是否与群体的内在特性和/或细胞内环境有关。在这里，我们介绍了一种新的概念，即在核磁共振中基于胞浆的PRSS保护。我们假设热休克蛋白[HSPs]在PMD中起关键作用，尤其是在氧化应激下。我们的初步数据表明，热休克蛋白对NMRS中的PRS特异性抑制剂具有抵抗力。我们评估了在衰老和药物诱导的氧化应激过程中，几个核磁共振组织中“抵抗体”的分子组成和功能。“抵抗体”是保护PRSS免受抑制/应激的蛋白质组装。我们预计，核磁共振PRSS普遍受到抗性小体的很好保护。我们展望了旨在提高PMD疗效的耐药激发药物或干预措施的未来发展。这些研究使用了一种异常长寿的啮齿动物，以获得对使提升的PRS功能稳定和维持的机制有新的见解。了解这些将有助于阻止许多与年龄相关的疾病，这些疾病与PR介导的降解不足和老年人受损蛋白质的积累有关。

DESCRIPTION (provided by applicant): The accrual of damaged or misfolded proteins commonly occurs during aging. Indeed, protein dysfunction is a key feature of many age-associated diseases. As such maintenance of protein quality control may be central to sustained healthspan and extended longevity. The longest-lived rodents, naked mole-rats [NMRs], maintain proteostasis and robust health for most of their 32-year lifespan. NMRs also show marked resistance to environmental stressors, and efficiently preserve protein quality. Both autophagy and proteasome-mediated degradation [PMD] play critical roles in intracellular protein quality control. We focus here on PMD for it is a key player in the removal of oxidatively damaged proteins and reportedly declines with age. We hypothesize that NMRs maintain highly efficient PMD in mitotic (e.g., liver), terminally-differentiated (brain, muscle) and immune-responsive (spleen) tissues during aging and that this is due to intrinsic properties of the proteasome [PRS] and/or a cytoprotective intracellular milieu. We address this in the following specific aims: Aim 1. To evaluate PRS structure and function, and in particular the role of the immunoproteasome [IMPR], in specific differences in PRS functional capacity, both during aging and in response to in vivo oxidative stressors. We hypothesize that the PRSs of NMRs are well-suited to effectively respond to oxidative stress and predict that this is due, in part, to the greter abundance of IMPRs. We will measure both age-related and oxidative stress-induced changes in PRS structure, functional capacity, and intracellular distribution in the various tissues. Our preliminary data reveal 2-5-fold higher rates of ChTL and TL activities, and higher diversity of PRS assemblies in NMR than in mouse livers. We expect to find similar trends in other tissues, especially in response to drug-induced oxidative stress, and predict a new role of IMPRs in preserving the efficacy of PMD. Aim 2. To determine whether interspecies differences in PRS capacity are due to intrinsic properties of the PRS and/or the intracellular environment. Here we introduce a novel concept of cytosolic-based protection of the PRSs in NMR. We hypothesize that heat shock proteins [HSPs] play a key role in PMD, especially under oxidative stress. Our preliminary data suggest that HSPs confer resistance to PRS specific inhibitors in NMRs. We assess the molecular composition and function of the "resistasome", the protein assembly that protects PRSs from inhibition/stress, in several NMR tissues during aging and drug-induced oxidative stress. We expect that NMR PRSs are universally well-protected by the resistasome. We envision future development of resistasome-inspired drugs or interventions aimed at boosting PMD efficacy. These studies use an unusually long-lived rodent to gain novel insights into mechanisms enabling the stability and maintenance of elevated PRS function. Understanding these will help foil the many age-related diseases linked to inadequate PRS-mediated degradation and the accrual of damaged proteins in the elderly.