Role of mTOR, a Component of the Akt Pathway, in Regulating Cardiac Function

mTOR（Akt 通路的一个组成部分）在调节心脏功能中的作用

• 批准号: 8386980
• 负责人: Kirk U Knowlton
• 金额: $ 35.99万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8386980
• 关键词: Address; Aerobic; Affect; Alleles; Animals; Antineoplastic Agents; Apoptosis; Apoptotic; Autophagocytosis; Breeding; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cardiotoxicity; Cardiovascular Physiology; Cardiovascular system; Cell Death; Cells; Cessation of life; Characteristics; Data; Dilated Cardiomyopathy; Dobutamine; Dominant-Negative Mutation; Etiology; Event; Gene Chips; Gene Expression; Generations; Genes; Genetic Models; Genetic Translation; Goals; Growth; Heart; Heart failure; Homeostasis; Homologous Gene; Hypertrophy; IGFBP2 gene; Knock-out; Knockout Mice; Lead; Mediating; Messenger RNA; Mitochondria; Modeling; Molecular; Multiprotein Complexes; Mus; Myocardial; Myocardium; Natural History; Pathogenesis; Pathologic; Pathway interactions; Phase; Phenotype; Phosphotransferases; Physiological; Play; Process; Protein Biosynthesis; Protein Synthesis Inhibition; Protein p53; Proteins; Proteomics; Proto-Oncogene Proteins c-akt; Regulator Genes; Relative (related person); Reporting; Research; Role; Signal Transduction; Stress; Syndrome; System; TP53 gene; Tamoxifen; Therapeutic; Training; Translating; Tumor Suppressor Genes; Tumor Suppressor Proteins; Up-Regulation; base; cancer therapy; carcinogenesis; improved; knockout animal; mTOR protein; member; mouse model; mutant; novel therapeutics; pressure; protein degradation; research study

PROJECT SUMMARY The overall aim of this project is to uncover the role of the mTOR (mammalian target of rapamycin) pathway and its relationship to p53 during normal and heart failure (HF) conditions. Myocardial mTOR activity, while increased in the early phases of pressure overload hypertrophy, eventually decreases when compensated hypertrophy switches to decompensation, ending in frank HF. We hypothesized therefore that mTOR and its downstream substrates are central in this process. For proving this, we therefore generated an inducible and cardiac-specific mouse model defective in mTOR (mTOR-cKO). We found that upon loss of mTOR, mice developed dilated heart phenotype that progressed rapidly to death. Markers of autophagy and apoptosis increased significantly; importantly, the tumor suppressor gene p53 significantly accumulated in the heart of mTOR KO mice; moreover, there was a remarkable myocardial accumulation of active 4E-BP1, a downstream member of the mTOR pathway which negatively controls mRNA translation in its dephosphorylated form and a major substrate of TORC-1, one of the two mTOR kinase multiprotein complexes. We found that acumulation of dephosphorylated 4E-BP1 is a feature of HF of diverse etiologies, and thus might represent a common mechanism underlying this state. We also found that deleting 4E-BP1 in mice determines a very significant improvement of cardiac function and survival in the context of cardiac mTOR KO. In other cellular systems, 4E-BPs were shown to regulate p53 protein levels. The specific aims of this project therefore are 1) to determine the relative role of apoptosis and autophagy in mTOR-defective HF and in particular the role of the key gene p53 and 2) determine the role of 4E-BPs in mTOR-dependent HF as well as the reciprocal control between 4E-BPs and p53. These tasks will be accomplished through cross-breeding experiments of mTOR-cKO mice with strains in which Atg5, a gene critical for autophagy, or Nix, a gene critical for apoptosis, are deleted. Also, the role of p53 will be assessed by crossing our model with mice with p53-floxed alleles. Gene expression and proteomic studies will be conducted with the aim to identify genes critical for mTOR-cKO HF. The involvement of 4E-BPs in regulating cardiac function as well as p53 levels will be addressed by crossing mTOR-cKO with double 4E-BP1/4E-BP2 KO mice and by studying the role of p53 in regulating 4E-BP1 expression. Results of our research will assess the relative and reciprocal role of mTOR/4E-BP1 and p53 in controlling cardiac function in the normal and diseased heart, opening the possibility to interfere with these molecules for therapeutic purposes.

项目摘要 该项目的总体目的是揭示MTOR的作用（雷帕霉素的哺乳动物靶标） 在正常和心力衰竭（HF）条件下，途径及其与p53的关系。心肌mtor 活性，而在压力超负荷肥大的早期阶段增加，最终减少 当补偿肥大切换到代偿性的交换时，以弗兰克·HF（Frank HF）结束。我们假设 因此，MTOR及其下游基板在此过程中至关重要。为了证明这一点，我们 因此，在MTOR（mTOR-CKO）中产生了可诱导和心脏特异性小鼠模型。 我们发现，在MTOR失去后，小鼠发生了扩张的心脏表型，迅速发展为 死亡。自噬和凋亡的标记显着增加。重要的是，肿瘤抑制剂 基因p53显着积累了MTOR KO小鼠的心脏。而且，还有一个了不起的 Active 4E-BP1的心肌积累，MTOR途径的下游成员 负面控制其去磷酸化形式的mRNA翻译和torc-1的主要底物， 两个MTOR激酶多蛋白复合物之一。我们发现 去磷酸化的4e-bp1是不同病因的HF的特征，因此可能代表一个常见 该状态的基础机制。我们还发现，在小鼠中删除4e-bp1可以决定 在心脏MTOR KO的背景下，心脏功能和生存的显着改善。在其他 细胞系统显示4E-BPS调节p53蛋白水平。该项目的具体目的 因此，是1）确定凋亡和自噬在MTOR缺陷HF和 特别是关键基因p53和2）确定4E-BP在mTOR依赖性HF中的作用 以及4E-BP和p53之间的相互控制。这些任务将通过 MTOR-CKO小鼠的交叉繁殖实验，其中ATG5是一种至关重要的基因 删除了自噬或NIX是至关重要的基因。此外，p53的作用将由 用p53-氯氟等位基因将模型越过我们的模型。基因表达和蛋白质组学研究将是 旨在确定对MTOR-CKO HF至关重要的基因进行进行。 4e-bps参与 通过将MTOR-CKO与双重交叉来解决心脏功能以及p53水平 4E-BP1/4E-BP2 KO小鼠和通过研究p53在调节4E-BP1表达中的作用。 我们的研究结果将评估MTOR/4E-BP1和p53在 控制正常和患病心脏的心脏功能，打开了干扰的可能性 这些分子用于治疗目的。