Metformin-Regulated Mitochondrial Peptides and their Effects on Aging

二甲双胍在模式生物中具有延长健康和寿命的作用，是一种候选疗法 人类的衰老。二甲双胍的确切作用机制尚不清楚，但线粒体是 显然，一个关键的二甲双胍靶点涉及呼吸链功能的调节，归因于抑制 Complex-1以及其他线粒体在分裂、活性氧产生等方面的作用 描述了线粒体DNA中存在多个小开放阅读框(SmORF)， 编码一类新的线粒体衍生多肽(MDP)。这些MDP有不同的细胞活动， 通常导致新陈代谢、细胞保护和健康寿命的改善。我们还展示了 这些MDP中的线粒体单核苷酸多态(MtSNPs)改变了它们的活性并增加了它们的活性 与衰老有关的疾病的风险。最近，我们开发了一种新的生物信息学方法来评估 整个线粒体smORFome的表达称为MDPseq。使用MDPSeq，我们可以演示 MDP在疾病状态和衰老过程中表达的深刻变化。我们重新分析了 多个公开可用的人类和小鼠二甲双胍治疗和观察的RNAseq数据集 MDP smORF RNA转录水平的戏剧性变化。在最有效地合成MDP之后 在几个体外系统中，我们发现了一些由二甲双胍调节的，并将它们与二甲双胍进行比较 候选的二甲双胍诱导的MDP以二甲双胍仿制的方式发挥作用。其中一位MDP，名叫 二甲双胍刺激的线粒体衍生多肽(Ms.MDP)具有与二甲双胍相似的葡萄糖活性 代谢、线粒体功能和AMPK信号转导。Ms.MDP siRNA减少部分二甲双胍 行为。当给喂高脂饮食的小鼠服用MDP时，MDP显著减缓了体重的增加和 显著降低血糖、丙氨酸氨基转移酶、天冬氨酸氨基转移酶和多种炎症细胞因子--类似地--或者更有效地-- 而不是二甲双胍。因此，我们假设二甲双胍的一个关键机制是MDP调节，并且这些 二甲双胍调节的MDP介导了二甲双胍的一些功能。我们进一步假设MDP是 关键参与了二甲双胍的抗衰老作用，它反过来又可能有助于定义 将对二甲双胍有反应，并可能作为增强健康寿命的替代疗法。我们的特定 其目的如下：1：鉴定肝脏中受MDP调控的人mdp smORF RNA转录本 以及决定临床对二甲双胍疗效的线粒体DNA变异体 人类群体。2：比较衰老和二甲双胍对小鼠MDP表达特征的影响。3： 在不同细胞类型的体外实验中，表征二甲双胍调节的MDP的衰老相关效应，以及4： 探讨二甲双胍长期给药的体内机制和治疗潜力。 调节衰老小鼠的MDP。总之，这些研究将定义一个全新的方向 了解二甲双胍延缓衰老的作用，将建立新的生物标志物以及 互补/替代的抗衰老方法。

Metformin has healthspan and lifespan enhancing effects in model organisms and is a candidate therapy for aging in humans. The exact mechanism of action of metformin is poorly understood, but the mitochondrion is clearly a critical metformin target involving modulation of respiratory-chain function attributed to inhibition of Complex-1 as well as other mitochondrial actions on fission, reactive oxygen species production, etc. Our lab described the presence of multiple small open reading frames (smORFs) within mitochondrial DNA that encode a novel class of mitochondrial-derived peptides (MDPs). These MDPs have diverse cellular actions, often leading to improved metabolism, cytoprotection, and healthspan. We also demonstrated that mitochondrial single nucleotide polymorphisms (mtSNPs) within these MDPs change their activity and increase risk of aging-related diseases. Recently, we developed a novel bioinformatic approach to assess changes in the expression of the entire mitochondrial smORFome called MDPseq. Using MDPSeq, we can demonstrate profound changes in the expression of MDPs in disease states as well as during aging. We re-analyzed multiple publicly available RNAseq datasets of humans and mice treated with metformin and observed dramatic changes in the MDP smORF RNA transcript levels. After synthesizing the MDPs most potently regulated by metformin and comparing them to metformin in several in vitro systems, we identified a number of candidate metformin-induced MDPs that act in a metformin-mimetic fashion. One of these MDPs, named Metformin-stimulated Mitochondrial-Derived Peptide (Ms.MDP), has similar activity to metformin on glucose metabolism, mitochondrial function, and AMPK signaling. Ms.MDP siRNA diminishes some of metformin actions. When administered to mice fed a high-fat diet, Ms.MDP significantly attenuated weight-gain and dramatically reduced blood sugar, ALT, AST, and multiple inflammatory cytokines similarly – or more potently – than metformin. Thus, we hypothesize that a key mechanism of metformin is MDP regulation, and that these metformin-regulated MDPs mediate some of the functions of metformin. We further hypothesize that MDPs are crucially involved in the anti-aging effects of metformin, which in turn can potentially help define individuals that will respond to metformin and possibly serve as alternative healthspan-enhancing treatments. Our specific aims to test this are as follows: 1: Identify human MDP smORF RNA transcripts in liver that are regulated by metformin, and mitochondrial DNA variants that determine the clinical response to metformin in several large human cohorts. 2: Compare the effects of aging and metformin on the MDP expression signature in mice. 3: Characterize the aging-related effects of metformin-regulated MDPs in vitro, in various cell types, and 4: Examine the in vivo mechanisms and therapeutic potential of chronic administration of promising metformin- regulated MDPs in aged mice. Together, these studies will define a completely novel direction in understanding the actions of metformin on delaying aging, and will establish novel biomarkers as well as complementary/alternative anti-aging approaches.