Mechanisms of longevity in the naked mole rat: high molecular weight hyaluronan and stable epigenome.

摘要：项目2的长期目标是了解导致长寿的分子机制 以及长寿哺乳动物的抗癌能力，然后将这些策略移植到人类身上。这个 裸鼠是最长寿的啮齿动物，最长寿命为32岁。此外，NMR是 对癌症和其他与年龄相关的疾病具有高度抵抗力。由于NMR与短命的实验室有关 啮齿动物是研究长寿的理想模型。我们发现了一种新的癌症机制-- 高相对分子质量透明质酸(HMW-HA)在核磁共振中的抗性 鼹鼠组织。透明质酸是一种多聚糖胺多聚糖，是由 透明质酸合成酶2基因(HAS2)。从核磁共振细胞中耗尽HMW-HA使其容易形成肿瘤。在……里面 在目前的资金周期中，我们产生了表达裸鼠HAS2的转基因小鼠(nmrHAS2小鼠)。我们的 初步结果表明，nmrHAS2小鼠的寿命更长，健康状况也更好。这些老鼠是 抵抗骨关节炎，并改善造血干细胞的维护。重要的是，我们发现 在nmrHAS2小鼠中，由于非常高的透明质酸酶(HA降解)，HMW-HA水平仅略有升高 小鼠组织中的活性与裸鼠相比。人体组织中也有类似的高透明质酸酶 活动。因此，我们提出使用小分子来下调透明质酸酶是一种很有前途的策略。 提高内源性HMW-HA水平，减轻与年龄相关的疾病，具有翻译潜力。 我们设计了一种高通量筛选透明质酸酶抑制剂的策略，并确定了第一个 可上调HMW-HA水平的化合物。在寻找其他促进核磁共振健康和 长寿，我们发现NMRS有更稳定的表观基因组，其特征是对iPSC的抗性 重新编程和组蛋白修饰的具体差异。基于这些发现，我们未来的目标是 集中在我们在核磁共振中发现的两种长寿机制，即HMW-HA和稳定的表观基因组。 我们的目标是：(1)完成寿命研究，并表征癌症的易感性、组织病理学、基因组 NmrHAS2小鼠的稳定性(项目3)、新陈代谢和甲基化年龄(项目4)。(2)表现出高水平 大量筛选透明质酸酶抑制剂，并测试这些化合物对健康、健身和年龄的影响。 小鼠的相关病理变化。(3)确定影响核磁共振表观基因组稳定性的分子机制。我们 将识别在核磁共振中有差异调节的特定组蛋白修饰酶，并操纵它们 以稳定小鼠的表观基因组。我们将与项目1合作，确定SIRT6在核磁共振中的角色 表观基因组稳定性，并与项目3一起研究核磁共振和小鼠的基因组和甲基组稳定性 表观遗传干预后的细胞。拟议的研究将确定输出长寿的策略 在裸色鼹鼠身上发现的机制与其他物种的关系。

SUMMARY: The long-term goal of Project 2 is to understand the molecular mechanisms responsible for longevity and cancer resistance of long-lived mammalian species and then translate these strategies to humans. The naked mole rat (NMR) is the longest-lived rodent, with a maximum lifespan of 32 years. Moreover, NMRs are highly resistant to cancer and other age-related diseases. Since NMRs are related to the short-lived laboratory rodents, they represent an ideal model for studies of longevity. We identified a novel mechanism of cancer- resistance in the NMR which is mediated by abundant high molecular weight hyaluronan (HMW-HA) in naked mole rat tissues. HA is a polymer glycosaminoglycan, and a component of the extracellular matrix produced by hyaluronan synthase 2 gene (HAS2). Depleting HMW-HA from NMR cells make them prone to form tumors. In the current funding cycle, we generated transgenic mice expressing naked mole rat HAS2 (nmrHAS2 mice). Our preliminary results suggest that nmrHAS2 mice have a longer lifespan and improved fitness. These mice are resistant to osteoarthritis and have improved hematopoietic stem cell maintenance. Importantly, we found that HMW-HA levels were only modestly elevated in nmrHAS2 mice due to very high hyaluronidase (HA-degrading) activity in the mouse tissues compared to the naked mole rat. Human tissues have similarly high hyaluronidase activity. We therefore propose that downregulating hyaluronidases using small molecules is a promising strategy to increase endogenous HMW-HA levels and alleviate age-related diseases, which has translational potential. We designed a strategy for a high throughput screen for hyaluronidase inhibitors and identified the first compounds that upregulate HMW-HA levels. In search for additional mechanisms that promote NMR health and longevity, we found that NMRs have more stable epigenomes characterized by resistance to iPSC reprogramming and specific differences in histone modifications. Based on these findings, our future objectives are focused on two longevity mechanisms we identified in the NMR, namely HMW-HA and a stable epigenome. Our aims are: (1) Complete the lifespan study and characterize cancer susceptibility, tissue pathology, genome stability (with Project 3), metabolism, and methylation age (with Project 4) of nmrHAS2 mice. (2) Perform a high throughput screen for hyaluronidase inhibitors and test the effect of these compounds on health, fitness and age- related pathologies in mice. (3) Determine molecular mechanisms responsible for NMR epigenome stability. We will identify specific histone modifying enzymes that are differentially regulated in the NMR, and manipulate them to stabilize the mouse epigenome. We will collaborate with Project 1 to determine the role of SIRT6 in NMR epigenome stability, and with Project 3 to investigate genome and methylome stability in the NMR and mouse cells after epigenetic interventions. The proposed research will identify strategies for exporting the longevity mechanisms found in the naked mole rat to other species.