The School of Human Nutrition, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Canada.
Redox Biol. 2021 Sep;45:102044. doi: 10.1016/j.redox.2021.102044. Epub 2021 Jun 16.
The chief ROS formed by mitochondria are superoxide (O) and hydrogen peroxide (HO). Superoxide is converted rapidly to HO and therefore the latter is the chief ROS emitted by mitochondria into the cell. Once considered an unavoidable by-product of aerobic respiration, HO is now regarded as a central mitokine used in mitochondrial redox signaling. However, it has been postulated that O can also serve as a signal in mammalian cells. Progress in understanding the role of mitochondrial HO in signaling is due to significant advances in the development of methods and technologies for its detection. Unfortunately, the development of techniques to selectively measure basal O changes has been met with more significant hurdles due to its short half-life and the lack of specific probes. The development of sensitive techniques for the selective and real time measure of O and HO has come on two fronts: development of genetically encoded fluorescent proteins and small molecule reporters. In 2015, I published a detailed comprehensive review on the state of knowledge for mitochondrial ROS production and how it is controlled, which included an in-depth discussion of the up-to-date methods utilized for the detection of both superoxide (O) and HO. In the article, I presented the challenges associated with utilizing these probes and their significance in advancing our collective understanding of ROS signaling. Since then, many other authors in the field of Redox Biology have published articles on the challenges and developments detecting O and HO in various organisms [1-3]. There has been significant advances in this state of knowledge, including the development of novel genetically encoded fluorescent HO probes, several O sensors, and the establishment of a toolkit of inhibitors and substrates for the interrogation of mitochondrial HO production and the antioxidant defenses utilized to maintain the cellular HO steady-state. Here, I provide an update on these methods and their implementation in furthering our understanding of how mitochondria serve as cell ROS stabilizing devices for HO signaling.
线粒体产生的主要活性氧（ROS）是超氧阴离子（O）和过氧化氢（HO）。超氧阴离子迅速转化为 HO，因此后者是线粒体向细胞中释放的主要 ROS。HO 曾一度被认为是有氧呼吸的一种不可避免的副产物，但现在被认为是线粒体氧化还原信号传递中重要的线粒体衍生因子。然而，有人提出 O 也可以作为哺乳动物细胞中的信号分子。对线粒体 HO 在信号传递中的作用的理解的进展，得益于用于其检测的方法和技术的显著进步。不幸的是，由于其半衰期短且缺乏特异性探针，用于选择性测量基础 O 变化的技术的发展遇到了更大的障碍。用于选择性和实时测量 O 和 HO 的灵敏技术的发展有两个方面：遗传编码荧光蛋白和小分子报告物的发展。2015 年，我发表了一篇关于线粒体 ROS 产生及其调控的详细综述，其中包括对用于检测超氧阴离子（O）和 HO 的最新方法的深入讨论。在文章中，我提出了利用这些探针的挑战及其在推进我们对 ROS 信号的集体理解方面的意义。此后，氧化还原生物学领域的许多其他作者发表了关于在各种生物体中检测 O 和 HO 的挑战和发展的文章[1-3]。在这方面的知识已经取得了重大进展，包括新型遗传编码 HO 荧光探针、几种 O 传感器的开发，以及用于探究线粒体 HO 产生和抗氧化防御以维持细胞 HO 稳态的工具包的建立。在这里，我提供了这些方法的最新信息，以及它们在进一步理解线粒体如何作为细胞 ROS 稳定装置以实现 HO 信号传递方面的应用。
