Metabolic and Bioenergetic Control in Mitochondrial Diseases

项目摘要 线粒体疾病包括一组异质的遗传性遗传性疾病， 线粒体或核DNA的突变，导致线粒体能量和代谢的失败， 功能由于这种线粒体故障，高能量需求的组织，如脑、骨骼、 肌肉、肝脏、肾脏、内分泌和呼吸系统受到严重影响。目前可用的疗法 但仍然缺乏有效的治疗方法。因此，有迫切的医疗需要，以确定 治疗线粒体疾病的新靶点。确定特定的靶点和药物， 通过电子传递链的不同复合物增加和拯救线粒体生物能量学 对治疗线粒体疾病具有治疗价值。一个例子是转录激活 辅激活因子PGC-1α是线粒体生物合成的主要成分，可挽救由线粒体生物合成引起的生物能量缺陷。 通过线粒体疾病的突变或小鼠模型，并改善临床症状。使用化学 和全基因组CRISPR编辑筛选在跨线粒体胞质杂交细胞携带一个突变， 线粒体编码的复合物I亚基，我们已经确定Brd 4（Bromodomain蛋白4）作为潜在的靶点 来治疗线粒体疾病溴结构域抑制或Brd 4缺失增强氧化磷酸化 活性并挽救由线粒体复合物I的遗传抑制引起的生物能量缺陷， 在高能量需求下促进细胞存活。然而，布罗莫结构域如何 抑制控制线粒体生物能量学，并且在体内模型中对线粒体疾病的影响是 未知本基金申请的主要目的是鉴定和分析 由此布罗莫结构域抑制激活线粒体能量学功能，以及它是否挽救了 线粒体疾病的症状在体内小鼠模型。研究重点集中在三个核心领域。 目的：1）Brd 4如何控制线粒体基因表达程序的分子和功能分析， trans-mitochondrial cybrid细胞。（具体目标1），2）细胞、代谢和生物能量分析， 胞质杂交细胞系和线粒体疾病患者来源的成纤维细胞中的溴结构域抑制（特异性目的 2)和，3）通过布罗莫结构域抑制剂的体内和离体代谢、能量和存活分析， 线粒体疾病小鼠模型（具体目标3）。这些研究的结果将确定新的 溴结构域抑制和Brd 4拯救丧失的分子机制和调控成分 由线粒体电子传递链缺陷引起的生物能量缺陷。由于线粒体生物能量 失败是线粒体疾病的标志，我们的研究可能会转化为潜在的治疗方法。

Project Summary Mitochondrial diseases comprise a heterogeneous group of genetic inherited disorders resulting from mutations in mitochondrial or nuclear DNA that cause failures in mitochondrial energetic and metabolic function. As a consequence of this mitochondrial failure, high energy demanding tissues such as brain, skeletal muscle, liver, kidney, endocrine and respiratory systems are severely affected. Current available therapies remain supportive but an effective cure is still missing. Therefore, there is an urgent medical need to identify new therapeutic targets to treat mitochondrial diseases. Identification of specific targets and drugs that increase and rescue mitochondrial bioenergetics through different complexes of the electron transport chain can be of therapeutic value to treat mitochondrial diseases. An example is activation of the transcriptional coactivator PGC-1α, a major component of mitochondrial biogenesis, that rescue bioenergetic defects caused by mutations or mouse models of mitochondrial diseases and ameliorates clinical symptoms. Using a chemical and genome-wide CRISPR editing screens in trans-mitochondrial cybrids cell carrying a mutation in a mitochondrial encoded complex I subunit, we have identified Brd4 (Bromodomain protein 4) as potential target to treat mitochondrial diseases. Bromodomain inhibition or loss-of-Brd4 enhances oxidative phosphorylation activity and rescues the bioenergetic defects caused by genetic inhibition of mitochondrial complex I and promotes cell survival under high energetic demands. However, the precise mechanisms of how bromodomain inhibition controls mitochondrial bioenergetics and the effects on mitochondrial disease in in vivo models are unknown. The major goal of this grant application is to identify and analyze the molecular mechanisms whereby bromodomain inhibition activates mitochondrial energetics function and whether it rescues mitochondrial disease symptoms in in vivo mouse models. The research strategy is focused on three central aims: 1) Molecular and functional analysis of how Brd4 controls mitochondrial gene expression programs in trans-mitochondrial cybrid cells. (Specific Aim 1), 2) Cellular, metabolic and bioenergetic analysis mediated by bromodomain inhibition in cybrid cell lines and mitochondrial disease patient derived fibroblasts (Specific Aim 2) and, 3) In vivo and Ex vivo metabolic, energetic and survival analysis by bromodomain inhibitors in mitochondrial disease mouse models (Specific Aim 3). The outcomes from these studies will identify novel molecular mechanisms and regulatory components by which bromodomain inhibition and loss of Brd4 rescue bioenergetic defects caused by mitochondrial electron transfer chain defects. Since mitochondrial bioenergetic failure is a hallmark of mitochondrial diseases, our studies may translate into potential therapies.