Regulation of Cellular Proliferation by Novel Mitochondrial-Encoded Tumor Suppressors

摘要 蜂窝舱通过动态双向通信网络在不同的 细胞器。在这里，我们专注于线粒体和细胞核之间的通讯，每个细胞器 拥有自己的基因组。线粒体和核基因组已经共同进化了十多亿年 可能需要密切沟通和交叉监管。然而，鉴于线粒体已知是 受1000多种核编码蛋白调控，但目前尚无已知的线粒体编码因子 它主动地与核进行交流和调节。我们最近发现了一种新的基因，编码在 并命名为MOTS-c(十二S核糖核酸型内的线粒体开放阅读框架)。MOTS-C是一种 小的16个氨基酸的多肽，部分通过主营养传感器AMPK调节代谢平衡 (腺苷一磷酸活化蛋白激酶)。我们最近报道，mots-c可以转位到 核反应代谢应激，与染色质结合，调节核基因表达。此外，我们的 采用多管齐下的方法进行初步研究，包括单细胞RNA-seq、生物信息学(包括机器 学习)，染色质免疫沉淀(芯片)和定量聚合酶链式反应(QPCR)，以及细胞分选，显示 Mots-c可以调节细胞增殖；mots-c靶向于p53/p21途径和核糖体过程。 考虑到线粒体在细胞增殖过程中的重要代谢作用(29)，一个关键的问题 线粒体编码的因子是如何与细胞核沟通以协调 在增殖过程中，新陈代谢随基因表达而转移。值得注意的是，快速分裂的癌细胞具有无法检测到的水平。 MOTS-C或核转位缺陷，提示MOTS-C失去有丝分裂-核通讯。 总而言之，癌症可能是一种遗传病，在这种疾病中，我们的两个基因组以双向中断的状态存在 通讯/调节，并可能作为一个独特的模型，开始了解MOTS-c在细胞中的作用 扩散。因为mots-c的表达/功能失调，而mots-c可以负性调节。 细胞周期/增殖，我们假设mots-c是一种线粒体编码的肿瘤抑制因子，这是同类中的第一种。 要确定，它直接调节细胞核以协调细胞新陈代谢和增殖。我们提出三个建议 旨在检验这一假说。首先，我们将把MOTS-c定性为一种肿瘤抑制因子，它在 分子、细胞、基因水平。第二，我们将全面绘制依赖MOTS-C的功能核 使用多种互补基因组学方法的基因组图谱，包括单细胞RNA-SEQ、ATAC-SEQ (染色质可及性)，以及使用芯片序列的基因组足迹。来自每种基因组方法的数据将是 集成使用包括机器学习在内的尖端计算方法来破译消息(S)MOTS- C递送到核基因组，以调节癌细胞的增殖和生存。最后，我们将确定MOTS如何- C介导的核内通讯对正常细胞增殖和抗应激能力的差异调节 和使用癌症小鼠模型的恶性细胞。 如果成功，我们预计我们的研究将对(I)基础研究产生广泛和持久的影响，因为 线粒体编码的肿瘤抑制因子的范式转换概念，协调细胞代谢和 增殖和(2)通过揭示线粒体DNA作为新药物靶点的来源(目前在那里 没有FDA批准的基于线粒体基因组的药物)。

ABSTRACT Cellular compartments are coordinated through a dynamic bidirectional communication network amongst various organelles. Here, we focus on the communication between mitochondria and the nucleus, organelles that each possess their own genomes. The mitochondrial and nuclear genomes have co-evolved for over a billion years and have likely required close communication and cross-regulation. However, whereas mitochondria are known to be regulated by over 1,000 nuclear-encoded proteins, but there is currently no known mitochondrial-encoded factor that actively communicates to and regulates the nucleus. We have recently identified a novel gene encoded within the mitochondrial DNA and named it MOTS-c (Mitochondrial ORF within the Twelve S rRNA type-c). MOTS-c is a small 16 amino acid peptide that regulates metabolic homeostasis, in part, via the master nutrient sensor AMPK (adenosine monophosphate-activated protein kinase). We recently reported that MOTS-c can translocate into the nucleus in response to metabolic stress to bind to chromatin and regulate nuclear gene expression. Further, our preliminary study using a multi-pronged approach, including single cell RNA-seq, bioinformatics (including machine learning), chromatin immunoprecipitation (ChIP) coupled with quantitative PCR (qPCR), and cell sorting, showed that MOTS-c can regulate cellular proliferation; MOTS-c targeted the p53/p21 pathway and ribosomal processes. Considering the important metabolic role of mitochondria in cellular proliferation processes (29), a critical question that remains largely enigmatic is how mitochondrial-encoded factors communicate to the nucleus to coordinate the metabolic shift with gene expression during proliferation. Notably, rapidly dividing cancer cells had undetectable levels of MOTS-c or nuclear-translocation deficiency, suggesting loss of mito-nuclear communication by MOTS-c. Together, cancer may be a genetic disease in which our two genomes exist in a state of disrupted bi-directional communication/regulation, and may serve as a unique model to start understanding the role of MOTS-c in cellular proliferation. Because MOTS-c expression/function was dysregulated and that MOTS-c can negatively regulate cell cycle/proliferation, we hypothesize that MOTS-c is a mitochondrial-encoded tumor suppressor, the first of its kind to be identified, that directly regulates the nucleus to coordinate cellular metabolism with proliferation. We propose three aims to test this hypothesis. First, we will characterize MOTS-c as a tumor suppressor that regulates cell proliferation at the molecular, cellular, genetic level. Second, we will comprehensively map the MOTS-c-dependent functional nuclear genomic landscape using multiple complimentary genomics approach, including single cell RNA-seq, ATAC-seq (chromatin accessibility), and genomic footprinting using ChIP-seq. The data from each genomic approach will be integrated using cutting-edge computational methods, including machine learning, to decipher the message(s) MOTS- c delivers to the nuclear genome to regulate cancer cell proliferation and survival. Lastly, we will determine how MOTS- c-mediated communication to the nucleus can differentially regulate cellular proliferation and stress resistance in normal and malignant cells using mouse models of cancer. If successful, we predict that our study will have broad and lasting impact on (i) basic research by introducing the paradigm-shifting concept of mitochondrial-encoded tumor suppressors that coordinate cellular metabolism and proliferation and (ii) therapeutic development by revealing mtDNA as a source of novel drug targets (currently there are no FDA-approved drugs based on the mitochondrial genome).