Structure-based biochemical understanding of Sestrins in aging and metabolism

 描述（由申请人提供）：衰老是细胞和身体功能逐渐衰退的过程。许多人类疾病，如癌症、II型糖尿病、神经退行性疾病，都与衰老直接或间接相关。因此，衰老和年龄相关疾病会显著影响日常生活质量，尤其是在老年人群体中。Sestrin（Sesn）是一个应激诱导基因家族，在DNA损伤、氧化应激、缺氧和未折叠蛋白应激等多种环境胁迫下表达上调。Sesn在减少活性氧（ROS）和抑制mTOR复合物1（mTORC 1）方面具有两种重要的生物活性，这两者都可以减轻衰老及其相关的病理学。事实上，在许多模型动物中，包括蠕虫、苍蝇和小鼠，Sestrin家族蛋白被证明是代谢稳态的关键调节剂，可减轻各种年龄和肥胖相关的病理。这些结果表明Sestrin是进化上保守的抗衰老分子。然而，由于Sestrin的这些抗衰老活性的生物化学基础一直难以捉摸，我们无法利用Sestrin的有益活性来减缓衰老和延长健康寿命。基于我们最近通过X射线晶体学确定的人Sestrin 2的3D分子结构，我们首次提出揭示Sestrin蛋白抗衰老活性的生化机制。在目的1中，我们将揭示hSesn 2的抗氧化功能的生化基础，使用结构导向突变和随后的体外和体内氧化还原活性测定。在目标2中，使用目标1研究产生的突变hSesn2蛋白，我们将研究突变的残基和活性位点是否对抑制培养的哺乳动物细胞和完整动物（果蝇）组织中的mTORC 1很重要。最后，在目标3中，将用野生型和突变体hSesn 2重建表现出不同加速老化表型的dSesn无效突变体果蝇，以测试突变的关键残基是否对于hSesn 2的抗老化生理作用在功能上重要。 Sesn。成功完成拟议的研究将使我们能够阐明hSesn2在抑制衰老和控制代谢方面的生理功能的结构基础。从拟议的研究中获得的结构和机制信息不仅揭示了Sesns的抗氧化和mTOR抑制活性的机制，而且还能够开发新的小分子，可以增强Sesns的催化活性或增加Sesn的稳定性。这些分子将在未来开发，可能用于扩展健康寿命和改善晚年生活质量。

 DESCRIPTION (provided by applicant): Aging is a process of gradual decline in cellular and bodily function. Many human diseases, such as cancers, type II diabetes, neurodegenerative diseases, are either directly or indirectly associated with aging. Therefore, aging and age-associated disease can significantly influence on the quality of daily life especially within the elderly age group. Sestrin (Sesn) is a stress-inducible gene family that can be upregulated by a variety of environmental stresses including DNA damage, oxidative stresses, hypoxia and unfolded protein stresses. Sesn has two important biological activities in reducing reactive oxygen species (ROS) and suppressing mTOR complex 1 (mTORC1), both of which may attenuate aging and its associated pathologies. Indeed, in many model animals, including worms, flies and mice, Sestrin-family proteins were shown to be a critical regulator of metabolic homeostasis that attenuates diverse age- and obesity-associated pathologies. These results suggest Sestrins to be evolutionarily conserved anti-aging molecules. However, because the biochemical basis for these anti-aging activities of Sestrins has been elusive, we were unable to harness Sestrins' beneficial activities for attenuation of aging and extension of healthspan. Based on the 3D molecular structure of human Sestrin2, which we have recently determined through X-ray crystallography, here we propose to uncover the biochemical mechanisms underlying the anti-aging activity of Sestrin proteins for the first time. In Aim 1, we will revealthe biochemical basis underlying hSesn2's antioxidant function using structure-guided mutagenesis and subsequent in vitro and in vivo assays of its redox activity. In Aim 2, using the mutant hSesn2 proteins generated from Aim 1 research, we will examine whether the mutated residues and active sites are important for suppressing mTORC1 in cultured mammalian cells and in tissues of an intact animal (Drosophila). Finally in Aim 3, dSesn-null mutant flies, which exhibit diverse accelerated aging phenotypes, will be reconstituted with wild-type and mutant hSesn2 to test if the mutated key residue(s) are functionally important for anti-aging physiological roles of Sesn. Successful completion of the proposed research will allow us to elucidate the structural basis for the physiological function of hSesn2 in suppressing aging and controlling metabolism. The structural and mechanistic information obtained from the proposed study not only reveals the mechanisms underlying Sesns' antioxidant and mTOR-inhibiting activities, but also enables development of novel small molecules that can either enhance the catalytic activity of Sesns or increase Sesn stability. These molecules, which will be developed in future, may be used to pharmacologically expand healthspan and improve the quality-of-life in the later ages.