Mitochondria are recognized as signaling organelles because, under stress, mitochondria can trigger various signaling pathways to coordinate the cell's response. The specific pathway(s) engaged by mitochondria in response to mitochondrial energy defects in vivo and in high-energy tissues like the heart are not fully understood. Here, we investigated cardiac pathways activated in response to mitochondrial energy dysfunction by studying mice with cardiomyocyte-specific loss of the mitochondrial phosphate carrier (SLC25A3), an established model that develops cardiomyopathy as a result of defective mitochondrial ATP synthesis. Mitochondrial energy dysfunction induced a striking pattern of acylome remodeling, with significantly increased post-translational acetylation and malonylation. Mass spectrometry-based proteomics further revealed that energy dysfunction-induced remodeling of the acetylome and malonylome preferentially impacts mitochondrial proteins. Acetylation and malonylation modified a highly interconnected interactome of mitochondrial proteins, and both modifications were present on the enzyme isocitrate dehydrogenase 2 (IDH2). Intriguingly, IDH2 activity was enhanced in SLC25A3-deleted mitochondria, and further study of IDH2 sites targeted by both acetylation and malonylation revealed that these modifications can have site-specific and distinct functional effects. Finally, we uncovered a novel crosstalk between the two modifications, whereby mitochondrial energy dysfunction-induced acetylation of sirtuin 5 (SIRT5), inhibited its function. Because SIRT5 is a mitochondrial deacylase with demalonylase activity, this finding suggests that acetylation can modulate the malonylome. Together, our results position acylations as an arm of the mitochondrial response to energy dysfunction and suggest a mechanism by which focal disruption to the energy production machinery can have an expanded impact on global mitochondrial function.

中文翻译：

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线粒体磷酸盐载体 SLC25A3 的缺失诱导心脏线粒体蛋白 acylome 的重塑

线粒体被认为是信号细胞器，因为在压力下，线粒体可以触发各种信号通路来协调细胞的反应。线粒体响应体内和心脏等高能量组织中的线粒体能量缺陷的特定途径尚不完全清楚。在这里，我们通过研究心肌细胞特异性线粒体磷酸盐载体 (SLC25A3) 缺失的小鼠，研究了响应线粒体能量功能障碍而激活的心脏通路，这是一种由于线粒体 ATP 合成缺陷而发展为心肌病的既定模型。线粒体能量功能障碍引起了惊人的淀粉样重塑模式，翻译后乙酰化和丙二酰化显着增加。基于质谱的蛋白质组学进一步揭示了能量功能障碍诱导的乙酰组和丙二酰组的重塑优先影响线粒体蛋白。乙酰化和丙二酰化修饰了线粒体蛋白的高度相互关联的相互作用组，这两种修饰都存在于异柠檬酸脱氢酶 2 (IDH2) 上。有趣的是，SLC25A3 缺失的线粒体中 IDH2 活性增强，对乙酰化和丙二酰化靶向 IDH2 位点的进一步研究表明，这些修饰可以具有位点特异性和独特的功能效应。最后，我们发现了两种修饰之间的新串扰，线粒体能量功能障碍诱导的 sirtuin 5 (SIRT5) 乙酰化抑制了其功能。因为 SIRT5 是一种具有脱丙二酰酶活性的线粒体脱酰基酶，这一发现表明乙酰化可以调节丙二醛。总之，我们的结果将酰化定位为线粒体对能量功能障碍的反应的一个分支，并提出了一种机制，通过这种机制，对能量生产机制的局部破坏可以对全球线粒体功能产生更大的影响。