Role of non-genomic regulation of mitochondrial trifunctional protein in NAFLD

线粒体三功能蛋白的非基因组调控在 NAFLD 中的作用

• 批准号: 10045515
• 负责人: JAMAL A IBDAH
• 金额: --
• 依托单位: HARRY S. TRUMAN MEMORIAL VA HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10045515
• 关键词: Acetylation; Address; Adenoviruses; Aging; Animals; Biochemical; Complex; Core Facility; Cultured Cells; Data; Defect; Deposition; Development; Disease; Dose; Fatty Acids; Fatty Liver; Fatty acid glycerol esters; Fibrosis; Future; Gene Expression; Gene Proteins; Health; Hepatocyte; Histologic; Histology; Hormones; Human; In Vitro; Inflammation; Knowledge; Lead; Link; Liver; Liver Failure; Liver Mitochondria; Liver diseases; Lysine; Measurement; Measures; Military Personnel; Missouri; Mitochondria; Molecular; Mouse Protein; Multienzyme Complexes; Mus; Neonatal; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathogenicity; Pathologic; Patients; Play; Population; Prevalence; Primary Malignant Neoplasm of Liver; Primary carcinoma of the liver cells; Proteins; Proteomics; Public Health; Regulation; Reporting; Role; Sampling; Severity of illness; Sirtuins; Site; Steatohepatitis; Sudden Death; Testing; Therapeutic; Thyroid Gland; Thyroid Hormones; Time; Triiodothyronine; Universities; Veterans; Work; effective therapy; fatty acid oxidation; human data; human subject; human tissue; imaging study; improved; in vivo; inflammatory marker; insight; long chain fatty acid; military veteran; mitochondrial dysfunction; mouse model; new therapeutic target; non-alcoholic fatty liver disease; non-genomic; nonalcoholic steatohepatitis; novel; overexpression; patient population; protein complex; protein expression; receptor; response; treatment strategy

Nonalcoholic fatty liver disease (NAFLD) is characterized by increased deposition of fat in the liver that may progress to inflammation, hepatocellular carcinoma, and liver failure. NAFLD is closely linked to type 2 diabetes mellitus and obesity. It remains a major public health problem with little progress made on its treatment. Disturbingly, NAFLD appears to be more common in the military and Veteran population compared with the general US population. Thus, efforts to understand the underlying mechanisms that contribute to NAFLD will provide valuable insight into developing therapeutic options for our Veteran population. Mitochondrial dysfunction plays a crucial role in the development of NAFLD, however, little is known about how to treat mitochondrial dysfunction and rescue the associated NAFLD. Mitochondrial trifunctional protein (MTP) is the major enzymatic complex in mitochondrial fatty acid oxidation (FAO) that consists of 4 α and 4β subunits carrying three enzymatic activities breaks down fatty acids in the mitochondria. A key unanswered question is whether regulation of MTP modulates NAFLD. In a reported mouse model with an MTP defect, mice heterozygous for the defect (MTP+/-) develop mitochondrial dysfunction and are susceptible to NAFLD. Determining the mechanisms involved in regulating MTP in this mouse model is critical to the understanding of the role of mitochondria in development and rescue of NAFLD. The hypothesis in this application is that increasing the assembly of the MTP complex increases its stability, which leads to improvement in mitochondrial fatty acid oxidation (FAO) and rescue of NAFLD. The proposal in this application is that both the NAD+-dependent SIRT3 and the triiodothyronine (T3) hormone improve MTP stability by nongenomic mechanisms through enhancement of the MTP complex assembly. The preliminary data strongly support the hypothesis. First, mitochondrial FAO, MTP and SIRT3 levels were reduced in liver samples obtained from human subjects with NAFLD. Second, overexpression of SIRT3 in the MTP+/- mice reduced the acetylation of MTP compared to controls, increased mitochondrial FAO, and reduced steatosis and inflammatory markers in the liver. Third, in vitro studies in cultured cells demonstrate that MTP stability and its levels were increased by T3 treatment. To examine this hypothesis, we will use human liver samples obtained from a Veteran patient population and the MTP mouse model to conduct ex vivo, in vivo, and in vitro studies towards the following specific aims: 1) To define the relationship between hepatic MTP-α levels, SIRT3 levels, mitochondrial FAO and disease severity in human liver samples obtained from Veteran population. 2) To determine the underlying mechanisms of increased MTP levels by SIRT3 overexpression in mice. 3) To test whether T3 rescues NAFLD in the MTP mouse model and whether it improves hepatic mitochondrial FAO by increasing MTP stability through interaction with mitochondrial shortened thyroid receptors. This is the first study to examine regulation of MTP by SIRT3 and T3, and how that impacts mitochondrial FAO and NAFLD. This proposal addresses key unanswered questions and knowledge gaps in the field that impact a significant health problem in our Veteran population. Identifying the mechanisms by which SIRT3 and T3 regulate MTP will have important implications and will hold promise for future discovery of novel treatments for NAFLD, an increasingly common disease in Veterans with limited therapeutic options.

非酒精性脂肪肝 (NAFLD) 的特点是肝脏中脂肪沉积增加， 炎症、肝细胞癌和肝衰竭的进展与 2 型密切相关。 糖尿病和肥胖症仍然是一个主要的公共卫生问题，但其进展甚微。 令人不安的是，与军人和退伍军人相比，NAFLD 似乎更常见。 因此，努力了解有助于理解的潜在机制。 NAFLD 将为我们的退伍军人群体开发治疗方案提供宝贵的见解。 线粒体功能障碍在 NAFLD 的发展中起着至关重要的作用，然而，人们对线粒体功能障碍如何发生知之甚少。 治疗线粒体功能障碍并挽救相关的线粒体三功能蛋白（MTP）。 是线粒体脂肪酸氧化 (FAO) 中的主要酶复合物，由 4 个 α 和 4β 亚基组成 携带三种酶活性可分解线粒体中的脂肪酸。 在报道的具有 MTP 缺陷的小鼠模型中，MTP 的调节是否会调节 NAFLD。 缺陷杂合子 (MTP+/-) 会导致线粒体功能障碍，并且容易患 NAFLD。 确定该小鼠模型中调节 MTP 的机制对于理解 线粒体在 NAFLD 的发展和挽救中的作用 本申请中的假设是： 增加 MTP 复合体的组装可提高其稳定性，从而改善 线粒体脂肪酸氧化（FAO）和 NAFLD 的挽救在本申请中是两者的建议。 NAD+ 依赖性 SIRT3 和三碘甲状腺原氨酸 (T3) 激素通过非基因组提高 MTP 稳定性 通过增强 MTP 复合体组装的机制初步数据有力地支持了这一点。 首先，从肝脏样本中获取的线粒体FAO、MTP和SIRT3水平降低。 其次，MTP+/- 小鼠中 SIRT3 的过度表达降低了 NAFLD 的乙酰化。 与对照组相比，MTP增加了线粒体FAO，并减少了脂肪变性和炎症标志物 第三，培养细胞的体外研究表明，MTP 稳定性及其水平增加。 为了验证这一假设，我们将使用从退伍军人患者身上获取的人类肝脏样本。 群体和 MTP 小鼠模型，针对以下方面进行离体、体内和体外研究 具体目标： 1) 明确肝脏 MTP-α 水平、SIRT3 水平、线粒体 FAO 之间的关系 2) 确定潜在的原因。 SIRT3 过表达在小鼠中增加 MTP 水平的机制 3) 测试 T3 是否可以挽救 NAFLD。 在 MTP 小鼠模型中，以及它是否通过增加 MTP 稳定性来改善肝线粒体FAO 通过与线粒体缩短的甲状腺受体相互作用这是第一项检查调节的研究。 SIRT3 和 T3 对 MTP 的影响，以及它如何影响线粒体 FAO 和 NAFLD 该提案解决了关键问题。 该领域未解答的问题和知识差距影响了我们退伍军人的重大健康问题 确定 SIRT3 和 T3 调节 MTP 的机制将具有重要意义。 并将有望在未来发现 NAFLD 这种日益常见的疾病的新疗法 治疗选择有限的退伍军人。