Reactive Sulfur Species: Challenging the Reactive Oxygen Species Paradigm

该研究将利用生物化学和细胞技术来研究生理相关氧水平下细胞中活性硫（RSS）的代谢和生化途径。氧的衍生物形成活性氧（ROS），这是生物学上最相关的氧化剂和大多数抗氧化剂的目标，被认为可以改善人体健康。然而，天然和合成抗氧化剂要么治疗价值有限，要么其活性似乎不依赖于ROS。这项研究提出，许多假定的活性氧的作用可以用活性硫来更好地解释。这一假设建立在首席研究员最近的工作基础上，并基于以下观察：硫和氧在化学和生物学上都是相似的，细胞抗氧化途径有效地代谢过氧化物，“抗氧化”健康食品影响过氧化物，许多活性氧测定不能区分活性氧和过氧化物，因此高估了活性氧，大多数实验是在室内空气中进行的，氧气水平比细胞内的水平高很多倍，这人为地增加了活性氧并消耗了过氧化物。在本研究项目中，将更详细地研究典型抗氧化途径的过饱和度代谢，并详细研究抗氧化保健食品“营养保健品”对细胞过饱和度的影响。这些结果将对基础生物学以及人类健康和营养产生广泛的影响。本研究将培养1名研究生、1名博士后和数名本科生。在资深教师的指导下，坚实的博士后指导计划将确保未来在任何专业环境中取得成功。来自活性氧（ROS）的氧化剂、抗氧化剂和氧化应激涉及内源性信号系统，并与几乎所有器官系统的病理生理状况相关。主要来自首席研究员实验室的工作表明，由于活性氧的化学相似性、半胱氨酸介导的信号系统（过氧化氢~二硫化氢）的互换性、无法分析区分这两者以及在超生理氧张力（室内空气）下进行的实验优势，活性氧的许多作用可以由活性硫（RSS）介导。该研究将表明，典型的ROS抗氧化途径独立于ROS影响RSS代谢，并确定这些催化机制，将通过营养和合成抗氧化剂检查RSS代谢，并将表明在“生理氧”环境中进行实验时，细胞RSS代谢大大增强和多样化。抗氧化剂、抗氧化途径抑制剂、硫化氢清除剂和转基因细胞的组合将用于操纵和理解RSS代谢，在缓冲液和生理氧浓度下的细胞中测量，使用特定的荧光团、安培电极和质谱法。本研究将为生理相关条件下RSS在细胞信号传导和稳态中的作用提供生化和生理基础。这些结果将扩大我们对RSS在健康和疾病中的理解，并在生物学和生物医学研究中开辟新的领域。它还将为一名博士后、一名研究生和众多本科生提供培训，为他们在生物医学科学领域的职业生涯做好准备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed research will use biochemical and cellular techniques to examine metabolism and biochemical pathways of reactive sulfur species (RSS) in cells under physiologically relevant oxygen levels. Derivatives of oxygen form reactive oxygen species (ROS), the most biologically relevant oxidant and the target of most antioxidants, which are thought to improve human health. Natural and synthetic antioxidants, however, have either had limited therapeutic value or their activity appears independent of ROS. This research proposes that many of the assumed actions of reactive oxygen species are better explained by reactive sulfur species. This hypothesis builds upon recent work by the principal researcher, and is based on the following observations: sulfur and oxygen are chemically and biologically similar, cellular antioxidant pathways efficiently metabolize RSS, ‘antioxidant’ health foods affect RSS, many ROS assays cannot distinguish between ROS and RSS and thereby overestimate ROS, and most experiments are performed in room air where oxygen levels are many times greater than the levels within cells, which artificially increases ROS and depletes RSS. In this research project, RSS metabolism by canonical antioxidant pathways will be examined in greater detail and the effects of antioxidant health food ‘nutraceuticals’ on cellular RSS will be examined in detail. The results will have broad implications for basic biology as well as for human health and nutrition. This research will help train one graduate student, one postdoctoral fellow, and several undergraduate students. A solid postdoctoral mentoring program guided by senior faculty will ensure future success in any professional setting.Oxidants, antioxidants, and oxidative stress from reactive oxygen species (ROS) are implicated in endogenous signaling systems and associated with pathophysiological conditions in virtually all organ systems. Work, mainly from the principal investigator’s laboratory, has shown that many of the effects attributed to ROS can be mediated by reactive sulfur species (RSS) due to their chemical similarity, interchangeability in cysteine-mediated signaling systems (hydrogen peroxide ~ hydrogen disulfide), inability to analytically distinguish between the two, and the preponderance of experiments performed under supra-physiological oxygen tensions (room air). The proposed research will show that canonical ROS antioxidant pathways affect RSS metabolism independent of ROS and identify these catalytic mechanisms, will examine RSS metabolism by nutraceutical and synthetic antioxidants, and will show that cellular RSS metabolism is greatly enhanced and diversified when experiments are conducted in ‘physioxic’ environments. Combinations of antioxidants, antioxidant pathway inhibitors, hydrogen sulfide scavengers, and genetically altered cells will be used to manipulate and understand RSS metabolism, measured in buffer and in cells under physiological oxygen concentrations, using specific fluorophores, amperometric electrodes, and mass spectrometry. The proposed research will provide the biochemical and physiological basis for the role of RSS in cell signaling and homeostasis under physiologically relevant conditions. These results will broaden our understanding of RSS in health and disease and open novel areas in biological and biomedical research. It will also provide training for one postdoctoral fellow, one graduate student, and numerous undergraduate students, preparing them for professional careers in the biomedical sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.