Molecular mechanism of mTORC1-dependent translation and ribosome biogenesis

mTORC1依赖性翻译和核糖体生物发生的分子机制

• 批准号: 8887569
• 负责人: Ken Inoki
• 金额: $ 29.02万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8887569
• 关键词: 5' Untranslated Regions; Ablation; Address; Animal Model; Antineoplastic Agents; Binding; Biochemistry; Biogenesis; Biological; Cell Proliferation; Cell physiology; Clinical Trials; Complex; Couples; Data; Defect; Development; Genes; Genetic Translation; Goals; Growth Factor; High-Throughput RNA Sequencing; Indium; Lead; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of prostate; Mediating; Messenger RNA; Metastatic Prostate Cancer; Modeling; Molecular; Molecular Biology; Mus; Nutrient; PTEN gene; Phosphorylation; Phosphotransferases; Play; Production; Prostate; Protein Biosynthesis; Protein Kinase; Proteins; Proteomics; Pyrimidine; RNA; RNA Recognition Motif; Regulation; Ribosomes; Role; Signal Pathway; Signal Transduction; Site; Staging; Testing; Tissues; Translation Initiation; Translations; Tumor Suppressor Proteins; Untranslated Regions; cancer cell; cancer therapy; cancer type; cell growth; cell growth regulation; in vivo; inhibitor/antagonist; insight; mTOR protein; migration; mouse model; new therapeutic target; novel; novel therapeutic intervention; prostate cancer cell line; public health relevance; response; scaffold; tumor; tumor progression; uncontrolled cell growth

 DESCRIPTION (provided by applicant): The mammalian target of rapamycin complex 1 (mTORC1) is an evolutionarily conserved multi- protein kinase complex that couples nutrient and growth factor sensing to regulate a wide array of essential cellular processes. mTORC1 stimulates protein synthesis and ribosome biogenesis, which are vital cellular processes that regulate cell growth and proliferation. Hyperactivation of mTORC1 signaling is found in many types of cancer cells and leads to aberrant increases in protein synthesis and uncontrolled cell proliferation. Despite the positive roles of mTORC1 in enhancing general cap- dependent translation through eIF4E activation, recent studies reveal mTORC1 preferentially stimulates a subset of mRNAs, including those that encode proteins required for translation, and cell growth, proliferation, and invasion. Interestingly, these mRNAs possess pyrimidine-enriched sequences (PES) such as 5'TOP in their 5'UTRs that are thought to play important roles in their expression. However, the molecular mechanisms by which mTORC1 primarily facilitates the translation of a subset of those mRNAs remain elusive. We have discovered a novel mTORC1 substrate, LARP1 that directly interacts with the PES in the 5'UTRs of 5' TOP mRNAs. Our preliminary data suggest that LARP1 functions not only as a molecular switch to regulate PES- containing mRNA translation in response to mTOR activity, but also as a regulator for mTORC1 to phosphorylate 4EBP1 and S6K1 on translationally-competent mRNAs. Knockdown of LARP1 significantly reduces translation of mRNAs that interact with LARP1 and dramatically inhibits ribosome biogenesis and cell proliferation in various cancer cells. We propose that LARP1 is an atypical mTORC1 substrate that regulates the translation of specific PES mRNAs and enhances their mTORC1-dependent translation. We will explore the molecular mechanisms by which mTORC1- dependent phosphorylation of LARP1 contributes to the translation of its interacting mRNAs. Second, we will determine the functional importance of the 5'UTR PES motif enriched in LARP1-bound mRNAs. Finally, we will explore the in vivo functions of LARP1 as well as pathophysiological role of LARP1 in PI3K-Akt-mTORC1-mediated cancer development in animal models. We will accomplish our goals by exploiting a multifaceted but integrated approach combining biochemistry, molecular biology, proteomics, high-throughput RNA sequencing, and mouse models. By elucidating the molecular mechanisms of mTORC1-LARP1-depenent translation, our proposed studies will provide new insights into the regulations of mTORC1-mediated translation and lead to new therapeutic approaches for cancer that target downstream effectors of mTORC1 activity.

 描述(申请人提供)：雷帕霉素复合体的哺乳动物靶标1(MTORC1)是一种进化上保守的多蛋白激酶复合体，它结合营养和生长因子感知来调节广泛的基本细胞过程。MTORC1刺激蛋白质合成和核糖体生物合成，这是调节细胞生长和增殖的重要细胞过程。在许多类型的癌细胞中发现mTORC1信号的过度激活，并导致蛋白质合成异常增加和细胞不受控制的增殖。尽管mTORC1通过激活eIF4E在促进一般的帽依赖翻译方面发挥了积极作用，但最近的研究表明，mTORC1优先刺激mRNAs的一个子集，包括那些编码翻译所需蛋白质的mRNAs，以及细胞的生长、增殖和侵袭。有趣的是，这些mRNAs在其5‘端非编码区中具有嘧啶丰富序列(PES)，如5’端，被认为在其表达中起着重要作用。然而，mTORC1主要促进这些mRNAs子集翻译的分子机制仍然难以捉摸。我们发现了一种新的mTORC1底物LARP1，它直接与5‘顶部mRNAs的5’UTRs相互作用。我们的初步数据表明，LARP1不仅作为分子开关来调节mTOR活性反应中含有PES的mRNA的翻译，而且还作为mTORC1的调节因子，使4EBP1和S6K1在具有翻译能力的mRNAs上磷酸化。LARP1基因的敲除显著减少了与LARP1相互作用的mRNAs的翻译，并显著抑制了各种癌细胞中核糖体的生物发生和细胞增殖。我们认为LARP1是一种非典型的mTORC1底物，它调节特定PES mRNAs的翻译并增强其mTORC1依赖的翻译。我们将探索依赖mTORC1的LARP1磷酸化有助于其相互作用的mRNAs翻译的分子机制。其次，我们将确定富含LARP1结合mRNAs的5‘UTRPES基序的功能重要性。最后，我们将探讨LARP1的体内功能以及在PI3K-Akt-mTORC1介导的动物模型中的病理生理作用。我们将通过利用生物化学、分子生物学、蛋白质组学、高通量RNA测序和小鼠模型相结合的多方面但集成的方法来实现我们的目标。通过阐明mTORC1-LARP1依赖翻译的分子机制，我们拟议的研究将为mTORC1介导的翻译调控提供新的见解，并引导针对mTORC1活性下游效应的新的癌症治疗方法。