Myocyte specific regulation of metabolism and the response to biomechanical force

描述(由申请人提供)： 研究和相关其他项目信息6.项目摘要/摘要心脏肥厚是心脏对各种外部刺激的反应，包括高血压、瓣膜心脏病和心肌梗塞，是心力衰竭最常见的先兆。在这一过程中，脂肪酸氧化的平行损伤和葡萄糖利用的增加都会发生，主要受PPAR家族转录因子的调节。在心肌肥厚的发展过程中，调节PPAR转录因子活性降低的机制(S)目前尚不清楚。在这个提案中，我们将首先确定心肌特异性肌肉环指-1(MuRF1)泛素化PPAR-复合体的机制(S)，以其蛋白酶体依赖的降解为目标。这些发现随后将使用我们建立的MuRF1-/-和MuRF1心脏转基因小鼠品系在体内得到证实。MuRF1的表达在PPAR调节的脂肪酸和葡萄糖氧化中的作用将通过检测灌流有放射性标记的脂肪酸和葡萄糖的分离工作心脏制剂的氧化代谢产物来确定。在本研究的第二个目的中，我们将确定在心肌肥厚过程中调节心脏MuRF1增加的信号通路，重点是NF-B、FOXO和FAK/MAPK信号通路。然后，我们将确定压力超负荷如何影响心肌肥厚中MuRF1和PPAR-的活性和定位，以阐明MuRF1相互作用和调节PPAR-或PPAR-复合体的其他成分的机制。最后，我们将通过将心肌细胞的机械拉伸与MuRF1的增加联系起来，阐明压力超负荷导致脂肪酸和葡萄糖氧化变化的具体机制。在特定的目标三中，我们将展示Stretch通过转录上调MuRF1水平以及通过拉伸诱导MuRF1从肌节移位到细胞质和胞核来增加MuRF1活性的机制。然后，我们将确定MuRF1如何在机械拉伸过程中与核PPAR相互作用，通过特定目的#1(MuRF1泛素化PPAR-并随后由蛋白酶体降解)和特定目的#2(Stretch如何通过核因子-kB和FOXO信号通路调节MuRF1水平)中确定的机制来调节脂肪酸和葡萄糖的氧化。这些研究将首次确定来自各种心脏病理的机械应激如何通过Titin相关的泛素连接酶MuRF1导致脂肪酸和葡萄糖氧化的特征性变化。。

DESCRIPTION (provided by applicant): RESEARCH & RELATED Other Project Information 6. Project Summary/Abstract The development of cardiac hypertrophy, the most common precursor to heart failure, is a response of the heart to a wide range of extrinsic stimuli, including hypertension, valvular heart disease, and myocardial infarction. Parallel impairment in fatty acid oxidation and an increase in glucose utilization occur during this process, regulated primarily by the peroxisome proliferator-activated receptor (PPAR) family of transcription factors. The mechanism(s) that regulates this decrease in PPAR transcription factor activity during the development of cardiac hypertrophy is presently unknown. In this proposal, we will first identify the mechanism(s) by which the cardiac specific Muscle Ring Finger-1 (MuRF1) ubiquitinates the PPAR- complex, targeting its proteasome-dependent degradation. These findings will then be confirmed in vivo using our established MuRF1 -/- and MuRF1 cardiac transgenic mouse lines. The role of MuRF1 expression on PPAR-regulated fatty acid and glucose oxidation will then be determined by detecting oxidation metabolites from isolated working heart preparations perfused with radio-labeled fatty acid and glucose. In the second aim of this study, we will determine the signaling pathways which regulate increases in cardiac MuRF1 during cardiac hypertrophy, focusing on NF-B, FOXO, and FAK/MAPK signaling pathways. We will then determine how pressure overload affects MuRF1 and PPAR- activity and localization in cardiac hypertrophy, to elucidate the mechanisms by which MuRF1 interacts and regulates PPAR-, or other components of the PPAR- complex. Lastly, we will elucidate specific mechanisms by which pressure overload induces changes in fatty acid and glucose oxidation by linking the mechanical stretch of cardiomyocytes to increases in MuRF1. In specific aim three, we will demonstrate the mechanisms by which stretch increases MuRF1 activity by its up-regulation of MuRF1 levels transcriptionally and through the stretch-induced translocation of MuRF1 from the sarcomere into the cytoplasm and nucleus. We will then determine how MuRF1 interacts with nuclear PPAR- during mechanical stretch to regulate fatty acid and glucose oxidation through the mechanisms identified in specific aim #1 (MuRF1 ubiquitination of PPAR- and subsequent degradation by the proteasome) and specific aim #2 (how stretch regulates MuRF1 levels through NF- kB and FOXO signaling pathway). These studies will identify for the first time how mechanical stress from a variety of cardiac pathologies leads to characteristic changes in fatty acid and glucose oxidation through the titin-associated ubiquitin ligase MuRF1. .