Regulation of the novel mTOR suppressor DDIT4 in the failing heart

新型 mTOR 抑制剂 DDIT4 在衰竭心脏中的调节

• 批准号: 8244427
• 负责人: YINGJIE CHEN
• 金额: $ 18.88万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8244427
• 关键词: 5' -AMP-activated protein kinase; 70-kDa Ribosomal Protein S6 Kinases; Attenuated; Cardiac Myocytes; Cartoons; Cell Line; Chronic; Chronic stress; Complex; DNA Damage; Development; Disease; Fibrosis; Figs - dietary; Foundations; Functional disorder; Genes; Heart; Heart failure; Hypertrophy; In Vitro; Intervention; Knowledge; Lead; Left; Left Ventricular Hypertrophy; Link; Mediating; Metformin; Molecular; Mouse Strains; Mus; Myocardial; Pathway interactions; Phenylephrine; Physiological; Play; Proteins; Publishing; Regulation; Relative (related person); Role; Signal Pathway; Signal Transduction; Stress; TSC1 gene; TSC2 gene; Testing; Transcript; Tumor Cell Line; Tumor-Derived; Ventricular; Ventricular Dysfunction; Work; base; cell growth; clinically relevant; constriction; hemodynamics; human FRAP1 protein; innovation; insight; mTOR protein; novel; overexpression; public health relevance; response; tumor; ventricular hypertrophy

DESCRIPTION (provided by applicant): AMP-activated protein kinase (AMPK) negatively regulates mammalian target of rapamycin (mTOR), the master regulator of translational machinery and cell growth. Recently, we demonstrated that the progressive left ventricular (LV) hypertrophy and heart failure (HF) caused by transverse aortic constriction (TAC) is exacerbated in mice with AMPK12 gene deficiency (AMPK12-/-), and this was associated with increased p- p70S6KThr389, a downstream target of mTOR complex 1 (mTORC1). We also found that activation of AMPK with AICAR or metformin, or overexpression of constitutively active AMPK12, all significantly attenuated cardiac myocyte hypertrophy and p-p70S6KThr389 in vitro. However, the mechanism by which loss of AMPK12 causes increased activation of the mTORC1/p-p70S6k Thr389 signaling pathway after TAC is not clear. DNA-damage-inducible transcript 4 (DDIT4) is a novel stress-responsive gene that negatively regulates the mTORC1 pathway in several tumor-derived cell lines. Although no published studies examining DDIT4 in the heart are available, using global microarray profiling we found that AMPK12-/- mice have decreased expression of myocardial DDIT4. These findings suggest that DDIT4 could provide the essential link by which AMPK12-/- causes activation of the mTORC1 and thereby exacerbates LV hypertrophy during stress conditions. Consequently, studies are proposed to determine whether the novel mTORC1 suppressor DDIT4 is instrumental in attenuating TAC-induced LV hypertrophy and HF in mice after TAC, and the molecular mechanisms by which AMPK12 facilitates adaptation of the heart to hemodynamic overload. Our central hypothesis is that DDIT4 attenuates chronic TAC-induced cardiac myocyte hypertrophy by attenuating the mTORC1 signaling pathway. We also hypothesize that AMPK regulates mTORC1 signaling at least partially through DDIT4. We plan to test our central hypothesis by pursuing the following two Specific Aims: i) Identify the overall impact of DDIT4 on myocardial mTORC1 signaling, LV hypertrophy and HF. Our working hypothesis is that DDIT4 gene deficiency (DDIT4-/-) will amplify activation of the mTOR signaling pathway and LV hypertrophy that occurs when hearts are exposed to systolic overload; ii) Determine the molecular mechanism by which AMPK attenuates mTORC1/p70s6k activation and cardiac myocyte hypertrophy. Our working hypothesis is that DDIT4 plays an essential role for AMPK to attenuate pathological LV hypertrophy. The project is innovative as no previous studies have examined the influence of DDIT4 on LV hypertrophy and HF. Using DDIT4-/- mice combined with TAC will allow us to decipher the role of DDIT4 in attenuating cardiac myocyte hypertrophy under clinically relevant conditions. This project is significant as the knowledge obtained will lead to a better understanding of the molecular mechanisms mediating ventricular hypertrophy and HF, which may provide the basis for developing specific interventions to treat these diseases. PUBLIC HEALTH RELEVANCE: DNA-damage-inducible transcript 4 (DDIT4) is a novel stress-responsive gene that negatively regulate the mTOR pathway in tumor cell lines. However, the effect of DDIT4 on ventricular hypertrophy and dysfunction has not been studied. Using global microarray profiling we recently found that AMPK12 KO mice have decreased expression of myocardial DDIT4, a change may explain the enhanced activation of myocardial mTOR signaling and ventricular hypertrophy in AMPK12 mice in response to chronic stress overload. Studies are proposed to determine whether the novel mTOR suppressor DDIT4 is instrumental in attenuating the development of ventricular hypertrophy and heart failure.

描述（由申请人提供）：AMP 激活蛋白激酶（AMPK）负向调节哺乳动物雷帕霉素靶点（mTOR），雷帕霉素靶点是翻译机制和细胞生长的主要调节因子。最近，我们证明，在 AMPK12 基因缺陷（AMPK12-/-）小鼠中，由主动脉横缩（TAC）引起的进行性左心室（LV）肥厚和心力衰竭（HF）加剧，这与 p- 增加有关。 p70S6KThr389，mTOR 复合物 1 (mTORC1) 的下游靶标。我们还发现，用 AICAR 或二甲双胍激活 AMPK，或过表达组成型活性 AMPK12，均能在体外显着减弱心肌细胞肥大和 p-p70S6KThr389。然而，TAC 后 AMPK12 缺失导致 mTORC1/p-p70S6k Thr389 信号通路激活增加的机制尚不清楚。 DNA 损伤诱导转录物 4 (DDIT4) 是一种新型应激反应基因，在多种肿瘤来源的细胞系中负向调节 mTORC1 通路。尽管没有已发表的研究检查心脏中的 DDIT4，但使用全局微阵列分析我们发现 AMPK12-/- 小鼠心肌 DDIT4 的表达降低。这些发现表明，DDIT4 可以提供 AMPK12-/- 引起 mTORC1 激活的重要联系，从而在应激条件下加剧左室肥厚。因此，拟进行研究以确定新型 mTORC1 抑制剂 DDIT4 是否有助于减轻 TAC 后小鼠 TAC 诱导的左室肥厚和心力衰竭，以及 AMPK12 促进心脏适应血流动力学超负荷的分子机制。我们的中心假设是 DDIT4 通过减弱 mTORC1 信号通路来减弱慢性 TAC 诱导的心肌细胞肥大。我们还假设 AMPK 至少部分通过 DDIT4 调节 mTORC1 信号传导。我们计划通过追求以下两个具体目标来检验我们的中心假设：i) 确定 DDIT4 对心肌 mTORC1 信号传导、左心室肥厚和心力衰竭的总体影响。我们的工作假设是，DDIT4 基因缺陷 (DDIT4-/-) 将放大 mTOR 信号通路的激活和心脏收缩超负荷时发生的左心室肥厚； ii) 确定 AMPK 减弱 mTORC1/p70s6k 激活和心肌细胞肥大的分子机制。我们的工作假设是 DDIT4 在 AMPK 减轻病理性左室肥厚方面发挥着重要作用。该项目具有创新性，因为之前没有研究探讨 DDIT4 对左心室肥厚和心力衰竭的影响。使用 DDIT4-/- 小鼠与 TAC 相结合将使我们能够破译 DDIT4 在临床相关条件下减轻心肌细胞肥大的作用。该项目意义重大，因为所获得的知识将有助于更好地了解介导心室肥厚和心力衰竭的分子机制，这可能为开发治疗这些疾病的具体干预措施提供基础。 公共健康相关性：DNA 损伤诱导转录物 4 (DDIT4) 是一种新型应激反应基因，可负向调节肿瘤细胞系中的 mTOR 通路。然而，DDIT4对心室肥厚和功能障碍的影响尚未研究。使用全局微阵列分析，我们最近发现 AMPK12 KO 小鼠心肌 DDIT4 的表达降低，这一变化可以解释 AMPK12 小鼠响应慢性应激超负荷时心肌 mTOR 信号传导增强和心室肥大的激活。拟开展研究以确定新型 mTOR 抑制剂 DDIT4 是否有助于减轻心室肥厚和心力衰竭的发展。