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: 8113127
• 负责人: YINGJIE CHEN
• 金额: $ 22.65万
• 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 2012-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8113127
• 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; 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激活的蛋白激酶（AMPK）负调节雷帕霉素的哺乳动物靶标（MTOR），这是转化机械和细胞生长的主调节剂。最近，我们证明了由AMPK12基因缺乏症（AMPK12 - / - ）引起的渐进性左心室（LV）肥大和心力衰竭（HF）加剧，这与P70S6KTHR389，MTSTREAM AFFFERS的MTORC 1（MTORC 1（MTORC）1（MTORC）1（MTORC 1）相关。我们还发现，用AICAR或二甲双胍激活AMPK，或在组成型活性AMPK12的过表达，都显着减弱了心肌肥大和P-P-P70S6KTHR389体外。但是，AMPK12丢失的机制导致MTORC1/P-P70S6K THR389信号通路的激活增加尚不清楚。 DNA损伤诱导的转录本4（DDIT4）是一种新型的应激响应基因，在几种肿瘤衍生的细胞系中对MTORC1途径负面调节。尽管没有发表过研究DDIT4心脏中的DDIT4的研究，但使用全局微阵列分析，我们发现AMPK12 - / - 小鼠的心肌DDIT4表达降低。这些发现表明，DDIT4可以提供基本联系，通过该联系，AMPK12 - / - 引起MTORC1的激活，从而在压力条件下加剧LV肥大。因此，提出了研究以确定新型的MTORC1抑制剂DDIT4是否有助于衰减TAC后小鼠TAC诱导的LV肥大和HF，以及AMPK12促进的分子机制促进了心脏对血液动力超负荷的适应。我们的中心假设是DDIT4通过衰减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至少通过DDIT4部分部分调节MTORC1信号。我们计划通过追求以下两个具体目标来检验中心假设：i）确定DDIT4对心肌MTORC1信号传导，LV肥大和HF的总体影响。我们的工作假设是DDIT4基因缺乏（DDIT4 - / - ）将扩大当心脏暴露于收缩期过载时发生的MTOR信号通路和LV肥大的激活； ii）确定AMPK减弱MTORC1/P70S6K激活和心肌肌细胞肥大的分子机制。我们的工作假设是，DDIT4对于衰减病理LV肥大的AMPK起着至关重要的作用。该项目具有创新性，因为以前没有研究检查了DDIT4对LV肥大和HF的影响。使用与TAC结合的DDIT4 - / - 小鼠将使我们能够破译DDIT4在临床相关条件下衰减心肌细胞肥大中的作用。该项目具有重要意义，因为获得的知识将使人们更好地了解介导心室肥大和HF的分子机制，这可能为制定特定干预措施治疗这些疾病提供了基础。 公共卫生相关性：DNA损伤诱导的转录本4（DDIT4）是一种新型的应激响应基因，对肿瘤细胞系中的MTOR途径负面调节。但是，尚未研究DDIT4对心室肥大和功能障碍的影响。使用全局微阵列分析，我们最近发现AMPK12 KO小鼠的心肌DDIT4的表达降低了，一种变化可以解释AMPK12小鼠中心肌MTOR信号传导和心室肥大的激活，响应于慢性应激超负荷。提出了研究以确定新型MTOR抑制DDIT4是否在减轻心室肥大和心力衰竭的发展方面具有重要作用。