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 该项目的总体目标是揭示mTOR（雷帕霉素的哺乳动物靶标）的作用。 在正常和心力衰竭（HF）条件下，p53通路及其与p53的关系。心肌mTOR 活动，而增加在早期阶段的压力超负荷肥大，最终降低 当代偿性肥大转变为失代偿时，以明显的HF结束。我们假设 因此，mTOR及其下游底物是该过程的中心。为了证明这一点，我们 因此产生了mTOR（mTOR-cKO）缺陷的诱导型和心脏特异性小鼠模型。 我们发现，一旦mTOR缺失，小鼠就会出现心脏扩张表型，并迅速发展为 死亡自噬和凋亡的标志物显著增加;重要的是， p53基因在mTOR KO小鼠的心脏中显著积累;此外， 心肌中活性4 E-BP 1的积累，4 E-BP 1是mTOR通路的下游成员， 负性控制去磷酸化形式的mRNA翻译和TORC-1的主要底物， 两种mTOR激酶多蛋白复合物之一。我们发现， 去磷酸化的4 E-BP 1是多种病因的HF的特征，因此可能代表一种常见的 这种状态下的机制。我们还发现，在小鼠中删除4 E-BP 1决定了一个非常重要的基因， 在心脏mTOR KO的情况下，心脏功能和存活率显著改善。换句 在细胞系统中，4 E-BP显示出调节p53蛋白水平。该项目的具体目标 因此，1）确定细胞凋亡和自噬在mTOR缺陷型HF中的相对作用， 特别是关键基因p53的作用和2）确定4 E-BP在mTOR依赖性HF中的作用 以及4 E-BPs与p53之间的相互调控。这些任务将通过 mTOR-cKO小鼠与Atg 5品系的杂交实验，Atg 5是一种对 自噬或Nix，一种对细胞凋亡至关重要的基因，被删除。此外，p53的作用将通过以下方式进行评估： 将我们的模型与带有p53-floxed等位基因的小鼠进行杂交。基因表达和蛋白质组学研究将是 目的是鉴定mTOR-cKO HF的关键基因。4 E-BP的参与 调节心脏功能以及p53水平将通过将mTOR-cKO与双 4 E-BP 1/4 E-BP 2基因敲除小鼠体内表达，研究p53在4 E-BP 1基因表达调控中的作用。 我们的研究结果将评估mTOR/4 E-BP 1和p53的相对和相互作用， 控制正常和患病心脏的心脏功能，开辟干扰的可能性 这些分子用于治疗目的。