Mitoribosome protein translation signaling and survival mechanisms

摘要 线粒体功能缺陷会在应激条件下导致细胞损伤和死亡。在有机体 线粒体水平功能障碍发生在由基因突变引起的线粒体疾病中， 神经退行性变，在衰老过程中程度较轻，损害脆弱的组织，如大脑和骨骼 肌肉。线粒体突变会导致能量代谢障碍，包括还原/氧化 导致组织损伤并最终死亡的失衡和炎症。线粒体缺陷细胞 依赖糖酵解产生能量，与线粒体疾病患者类似，容易患上 压力条件。造成这种细胞损伤的机制以及线粒体缺陷细胞是如何 保护免受损害和死亡在很大程度上是未知的。这一点很重要，因为没有治愈的方法 线粒体疾病和功能障碍是衰老或神经退化的标志之一。 在遗传和化学高通量筛查中，我们的实验室已经确定了抗生素的子集，包括 四环素，靶向有丝分裂糖体蛋白翻译，拯救细胞死亡和细胞内的炎症 以及线粒体疾病的小鼠模型。四环素促进细胞存活依赖于抑制 内质网应激和不依赖转录因子ATF4的未折叠蛋白反应(UPR)。这个 四环素诱导的有丝分裂停滞/分裂保护细胞和细胞死亡的机制 线粒体疾病的小鼠临床前模型尚不清楚。我们假设一种信号机制 在线粒体缺陷细胞的背景下，在停滞/分裂的有丝分裂体启动促进细胞存活 人类疾病的突变。这个应用程序的主要目标是识别信令和蜂窝 由停滞和分裂的有丝分裂体引起的机制，促进细胞存活并决定 在线粒体疾病的细胞和小鼠模型中的疗效。我们建议1)确定初始的 线粒体疾病中促进存活的部分停滞/分裂的有丝分裂体的信号机制 突变细胞，专注于MALSU分裂因子和与有丝分裂体相关的额外蛋白质；2)至 分析停滞/分裂的有丝分裂体下游促进线粒体存活的成分 疾病突变细胞，集中在将停滞/分裂的有丝分裂体与内质网应激IRE1a和内质网应激联系起来的成分 UPR反应和3)分析四环素类似物对线粒体复合体Ndufs4KO小鼠的影响 I缺陷小鼠模型，重点研究四环素类药物对小鼠适合性、存活率的影响及其对有丝分裂体的调节作用 Ndufs4KO小鼠的信号/内质网应激与脑和骨骼肌免疫炎症的抑制。这个 此应用程序的结果将决定由 线粒体疾病突变条件下的停滞/分裂的有丝分裂体。这些机制将 促进我们对有丝分裂体蛋白翻译和保护细胞的信号机制的理解 线粒体失调和疾病背景下的损害。

Abstract Defective mitochondrial function causes cellular damage and death under stress conditions. At the organismal level mitochondrial dysfunction occurs in mitochondrial diseases caused by genetic mutations, neurodegeneration, and with less severity during aging, damaging vulnerable tissues such as brain and skeletal muscle. Mitochondrial mutations cause failures that disrupt energy metabolism, including reductive/oxidative imbalances and inflammation that lead to tissue damage and eventually death. Mitochondrial defective cells depend on glycolysis for energy generation and, similar to mitochondrial disease patients, are vulnerable to stress conditions. The mechanisms that cause this cell damage and how mitochondrial defective cells can be protected against damage and death are largely unknown. This is important because there are no cures for mitochondrial diseases, and dysfunctional mitochondria is one of the hallmarks of aging or neurodegeneration. In genetic and chemical high throughput screens our laboratory has identified a subset of antibiotics, including tetracyclines, that target the mitoribosome protein translation, and rescue cell death and inflammation in cellular and mouse models of mitochondrial diseases. Tetracyclines-promoted cell survival depends on suppression of ER stress and Unfolded Protein Response (UPR) that is independent of the transcription factor ATF4. The mechanisms of how tetracycline-induced mitoribosome stalling/splitting protect against cell death in cellular and mouse pre-clinical models of mitochondrial diseases is unknown. We hypothesize that a signaling mechanism initiated at the stalled/split mitoribosome promotes cell survival in the context of mitochondrial defective cells and human disease mutations. The main goal of this application is to identify the signaling and cellular mechanisms caused by stalled and split mitoribosomes that promote cell survival and determine the efficacy in cellular and mouse models of mitochondrial diseases. We propose 1) to determine the initial signaling mechanism at the partial stalled/split mitoribosome that promotes survival in mitochondrial disease mutant cells, focusing on MALSU splitting factor and additional proteins associated at the mitoribosome; 2) to analyze the components downstream of the stalled/split mitoribosome that promote survival in mitochondrial disease mutant cells, focusing on components that link the stalled/split mitoribosome to ER stress IRE1a and UPR responses and 3) to analyze the effects of tetracycline analogs in Ndufs4 KO mice, a mitochondrial complex I deficient mouse model, focusing on the effects tetracyclines on fitness, survival and modulation of mitoribosome signaling/ER stress and suppression of brain and skeletal muscle immune inflammation in Ndufs4 KO mice. The outcomes of this application will determine the regulatory and signaling mechanisms that are initiated by the stalled/split mitoribosome in conditions of defective mitochondrial disease mutations. These mechanisms will advance our understanding of mitoribosome protein translation and signaling mechanisms that protect cell damage in the context of mitochondrial dysregulation and diseases.