Small molecule approach to activate human SIRT5

摘要 “七大”人类沉默调节蛋白在包括 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。他们监管范围广泛 蛋白质和酶通过其 NAD 依赖性脱乙酰酶活性来靶向。 Sirtuins 也被认为 介导低热量摄入的有益影响，以延长从酵母到多种生物体的寿命 哺乳动物。模拟热量限制以刺激沉默调节蛋白活性的小分子是有吸引力的治疗方法 对抗年龄相关疾病，如心血管疾病、糖尿病和神经退行性疾病。小 已知一种线粒体去乙酰化酶 SIRT5。 SIRT5 已成为维护 心脏健康和神经元在压力下的活力，并以特定的方式发挥肿瘤抑制作用。 关于 SIRT5 是否由于其较弱的功能而不再是一种脱乙酰酶，一直存在很多争论。 催化活性，特别是在体外测试中。我们首次鉴定出 SIRT5 选择性变构 激活剂，烟酰胺核苷（NR）。它可以提高 SIRT5 与不同合成物的脱乙酰效率 肽底物及其内源性同源底物。然而，SIRT5 的脱酰酶活性是 对 NR 激活不敏感。激活机制将在三个具体目标上进一步探索。在目标 1 中，我们的 我们将努力阐明不同的 NR 敏感性所需的结构决定因素和 变构结合位点的鉴定。在目标 2 中，目标参与并激活 SIRT5 以响应 将研究细胞环境中的激活剂治疗。在目标 3 中，将推出多个系列的 SIRT5 激活剂 基于我们的初步筛选、构效关系分析和对接研究，使用 化学和酶促策略的结合。在拟议的研究中获得的知识不仅 阐明我们对 SIRT5 生物学功能的理解，同时也带来新的代谢疗法 失调和与年龄有关的疾病。

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.