Acylations: a novel pathway in the response to mitochondrial energy dysfunction

作为细胞新陈代谢的重要调节者，线粒体激活了各种应激反应途径。 (例如，衰老)和功能障碍(例如，未折叠的蛋白质)。然而，对体内途径知之甚少。 线粒体用来传递受损的能量产生。线粒体能量障碍是一个标志 一系列影响高能量需求组织的退行性疾病，从而了解 线粒体对能量功能障碍的反应和体内细胞对能量危机的直接反应是至关重要的 用于设计有针对性的战略，以改善这些疾病。在这里，我们将利用In的独特模式 我们通过诱导心肌线粒体缺失而导致的体内线粒体能量损伤 磷酸盐载体(SLC25A3)在成年小鼠心肌细胞中的表达。该模型提供了一种新的建模系统 高能量需求的终末分化组织中的线粒体能量损伤。有趣的是， 尽管这些小鼠表现出心脏病，但SLC25A3缺乏并不符合标准 线粒体能量障碍途径，如AMPK和ROS信号，也没有表现出细胞死亡或纤维化 有缺陷的心脏。相反，成人心脏中SLC25A3的缺失会导致线粒体特异性的显著增加 蛋白质酰化，特别是乙酰化和丙二酸化。酰化反应是动态的后翻译 源自代谢中间体的修饰，可被sirtuin脱脂酶去除。重要的是 酰化具有将新陈代谢与蛋白质功能调节联系起来的潜力，而改变的酰化是 与疾病的发病机制有关。我们的初步数据表明，特别是在两方面 酰基组--乙酰基组和丙二酸组--是对线粒体能量的响应而改变的 功能障碍。虽然众所周知，酰基组调节线粒体新陈代谢，但我们的工作表明， 相反的情况也是可能的：线粒体能量障碍指导着酰基组的重塑。我们假设 酰基组修饰代表了线粒体的内在机制，以协调细胞对 能量压力。将SLC25A3缺失小鼠与细胞生物学、生物化学、蛋白质组学和 创新的体内基因治疗方法，我们将1)确定SLC25A3缺失的机制- 介导的酰化重塑，2)定义酰化如何调节线粒体渗透性转换孔 细胞死亡途径，以及3)确定异常酰化对线粒体的生理影响 能量受损的心脏。拟议的研究将为线粒体之间的联系提供新的见解 生物能量学与酰化重塑和定位酰化作为线粒体应激反应的一个臂 这是在线粒体能量功能障碍时激活的。归根结底，识别调控途径 线粒体功能障碍将促进针对线粒体能量的新疗法的开发 疾病中的功能障碍。

As critical regulators of cellular metabolism, mitochondria activate various pathways in response to stressors (e.g., aging) and dysfunction (e.g., unfolded proteins). However, little is known about the in vivo pathways mitochondria use to communicate impaired energy production. Mitochondrial energy dysfunction is a hallmark of a range of degenerative diseases affecting tissues with high energy demands, thus understanding how mitochondria respond to energy dysfunction and direct the cellular response to energetic crisis in vivo is critical for the design of targeted strategies to ameliorate these diseases. Here, we will leverage a unique model of in vivo mitochondrial energy impairment that we engineered by inducible deletion of the cardiac mitochondrial phosphate carrier (SLC25A3) in adult mouse cardiomyocytes. This model offers a novel system to model mitochondrial energy impairment in a terminally differentiated tissue with high energy demands. Intriguingly, despite the cardiac disease exhibited by these mice, SLC25A3 deficiency does not engage canonical mitochondrial energy dysfunction pathways like AMPK and ROS signaling, nor is cell death or fibrosis exhibited by deficient hearts. Instead, loss of SLC25A3 in adult hearts causes a striking increase in mitochondria-specific protein acylations, particularly acetylation and malonylation. Acylations are dynamic post-translational modifications derived from metabolic intermediates and subject to removal by sirtuin deacylases. Importantly, acylations harbor the potential to link metabolism to protein functional regulation, while altered acylation is associated with disease pathogenesis. Our preliminary data suggest that, in particular, two aspects of the acylome—the acetylome and the malonylome—are remodeled in response to mitochondrial energy dysfunction. While the acylome is well known to regulate mitochondrial metabolism, our work suggests that the converse is also possible: that mitochondrial energy dysfunction directs acylome remodeling. We hypothesize that acylome modifications represent a mitochondria-intrinsic mechanism to coordinate the cellular response to energy stress. Using the SLC25A3 deletion mice together with cell biology, biochemistry, proteomics, and innovative in vivo gene therapy approaches, we will 1) identify the mechanisms underlying SLC25A3 deletion- mediated acylome remodeling, 2) define how acylations regulate the mitochondrial permeability transition pore cell death pathway, and 3) determine the physiological impact of aberrant acylations on the mitochondrial energy-impaired heart. The proposed studies will provide novel insight on the link between mitochondrial bioenergetics and acylome remodeling and position acylations as an arm of the mitochondrial stress response that is activated upon mitochondrial energy dysfunction. Ultimately, identification of pathways regulating mitochondrial dysfunction will facilitate the development of new therapies targeting mitochondrial energy dysfunction in disease.