Metformin-Regulated Mitochondrial Peptides and their Effects on Aging

代谢物在模式生物中具有延长健康寿命和寿命的作用，并且是治疗糖尿病的候选疗法。 人类的衰老二甲双胍的确切作用机制尚不清楚，但二甲双胍是一种有效的药物。 显然，二甲双胍是一个关键的靶点，涉及调节归因于抑制 复合物-1以及其他线粒体对裂变、活性氧产生等的作用。 描述了线粒体DNA中存在多个小的开放阅读框（smORF）， 编码一类新的尿道衍生肽（MDP）。这些MDP具有不同的细胞行为， 通常导致改善的新陈代谢、细胞保护和健康寿命。我们还证明了 这些MDP中的线粒体单核苷酸多态性（mtSNPs）改变它们的活性并增加它们的表达。 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，我们可以证明 在疾病状态以及衰老过程中MDP表达的深刻变化。我们重新分析了 接受二甲双胍治疗的人和小鼠的多个公开可用的RNAseq数据集， MDP smORF RNA转录水平的显著变化。在最有效地合成MDP之后， 通过二甲双胍的调节，并在几个体外系统中将它们与二甲双胍进行比较，我们确定了一些 候选二甲双胍诱导的MDP，其以二甲双胍模拟方式起作用。其中一个名为 二甲双胍刺激的线粒体衍生肽（Ms.MDP）与二甲双胍对葡萄糖的活性相似 代谢、线粒体功能和AMPK信号传导。Ms.MDP siRNA减少了一些二甲双胍 行动当给予喂食高脂饮食的小鼠时，MDP女士显著减弱了体重增加， 显著降低血糖，ALT，AST和多种炎症细胞因子类似-或更有效- 比二甲双胍更好因此，我们假设二甲双胍的一个关键机制是MDP调节， 二甲双胍调节的MDP介导二甲双胍的一些功能。我们进一步假设MDP是 关键参与二甲双胍的抗衰老作用，这反过来又可能有助于定义 将对二甲双胍有反应，并可能作为替代的健康增强治疗。我们的具体 目的是测试这一点如下：1：鉴定人MDP smORF RNA转录物在肝脏中的调节， 二甲双胍和线粒体DNA变异，决定了二甲双胍的临床反应，在几个大的 人类队列2：比较衰老和二甲双胍对小鼠中MDP表达特征的影响。第三章： 表征二甲双胍调节的MDP在体外、各种细胞类型和4： 研究有前景的二甲双胍长期给药的体内机制和治疗潜力- 调节老年小鼠的MDP。总之，这些研究将确定一个全新的方向， 了解二甲双胍对延缓衰老的作用，并将建立新的生物标志物， 补充/替代抗衰老方法。

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.