Small molecule approach to activate human SIRT5

摘要 “伟大的七个”人类sirtuin在包括dna在内的各种细胞过程中发挥着关键作用。 修复、基因沉默、线粒体生物发生、胰岛素分泌和细胞凋亡。它们监管着广泛的 蛋白质和酶通过其依赖NAD的脱乙酰酶活性而成为靶标。Sirtuins也被认为是 调节低卡路里摄入的有益效果，以延长从酵母到其他生物的寿命 哺乳动物。模拟卡路里限制以刺激sirtuin活性的小分子是有吸引力的治疗方法 预防与年龄相关的疾病，如心血管疾病、糖尿病和神经退行性疾病。一点儿 已知的是一种线粒体sirtuins，SIRT5。SIRT5已经成为维护 心脏健康和应激时神经元的存活，并以特定上下文的方式发挥肿瘤抑制因子的功能。 关于SIRT5是否已经从脱乙酰酶进化而来，因为它的弱 催化活性，特别是在体外测试中。我们首次鉴定了一种SIRT5选择性变构 激活剂，烟酰胺核苷(NR)。通过不同的合成方法可以提高SIRT5脱乙酰基的效率 多肽底物及其内源同源底物。然而，SIRT5的脱酰基酶活性是 对NR的激活不敏感。激活机制将从三个具体目标进行进一步探讨。在目标1中，我们的 将致力于阐明不同NR敏感性所需的结构决定因素和 变构结合部位的鉴定。在目标2中，目标参与和激活SIRT5以应对 在细胞背景下的激活剂治疗将被调查。在目标3中，几个系列的SIRT5激活剂将被 基于我们的初步筛选、构效关系分析和对接研究 化学策略和酶策略的结合。从拟议的研究中获得的知识不仅将 澄清我们对SIRT5生物学功能的理解，也导致新陈代谢治疗的新方法 疾病和与年龄相关的疾病。

ABSTRACT The “magnificent seven” human sirtuins play critical roles in various cellular processes including DNA repair, gene silencing, mitochondrial biogenesis, insulin secretion and apoptosis. They regulate a wide array of protein and enzyme targets through their NAD+-dependent deacetylase activities. Sirtuins are also thought to mediate the beneficial effects of low calorie intake to extend longevity in diverse organisms from yeast to mammals. Small molecules mimicking calorie restriction to stimulate sirtuin activity are attractive therapeutics against age-related disorders such as cardiovascular diseases, diabetes and neurodegenerative diseases. Little is known about one of the mitochondrial sirtuins, SIRT5. SIRT5 has emerged as a critical player in maintaining cardiac health and neuronal viability upon stress, and functions as tumor suppressor in a context specific manner. Much has been debated about whether SIRT5 has evolved away from being a deacetylase because of its weak catalytic activity, especially in the in vitro testing. We have, for the first time, identified a SIRT5-selective allosteric activator, nicotinamide riboside (NR). It can increase SIRT5 deacetylation efficiency with different synthetic peptide substrates as well as its endogenous cognate substrate. However, the deacylase activity of SIRT5 is insensitive to NR activation. Mechanism of activation will be further explored in three specific aims. In aim 1, our effort will be directed at the elucidation of structural determinants required for the differential NR sensitivities and the identification of allosteric binding site. In aim 2, target engagement and activation of SIRT5 in response to activator treatment in the cellular context will be investigated. In aim 3, several series of SIRT5 activators will be synthesized based on our initial screening, structure-activity relationship analysis and docking studies using a combination of chemical and enzymatic strategies. The knowledge gained in the proposed study will not only clarify our understanding of the biological functions of SIRT5, but also lead to new therapeutics for metabolic disorders and age-related diseases.