Synergistic toxicity of reactive oxygen species

过氧化氢是一种生物特异性毒素，与常见的有机或无机分子呈惰性， 但在足够的浓度下，几乎在接触时杀死任何类型的细胞， 以产生高活性氧化物质（芬顿反应）。染色体DNA是 HP中毒的主要细胞目标，尽管致命的染色体损伤的性质是 仍然未知。更令人困惑的是，惠普竟然是一个令人惊讶的选择生物- 武器，由于杀伤浓度比生理浓度高1,000倍， 虽然HP在特定细胞区室中的积累是有问题的， 小尺寸和不带电的性质有利于通过膜的扩散。然而，我们的免疫系统 细胞以某种方式使用这些低得多的HP浓度来有效地杀死入侵的微生物， 不明确的机制。值得注意的是，HP毒性与其他简单分子协同作用，如 一氧化氮（NO）或氰化物（CN）。我们假设我们的免疫细胞使用的是 HP浓度不足以通过积聚增效剂分子来杀死细菌（对于 例如，NO）在高[HP]不累积的隔室中。但 HP毒性增强背后的代谢机制，被认为可以提高细胞内 游离铁，是不符合最新的结果，而不可挽回的机制， 染色体损伤仍不清楚。我们最近对HP + CN联合毒性的研究 发现了这一现象的新方面，如铁从细胞内库招募 直接作用于DNA，或者是灾难性的染色体断裂， 杀人我们建议研究HP + NO的联合毒性，有三个具体目标：1）这种毒性的性质 协同毒性和NO作用的靶点; 2） 灾难性的染色体断裂; 3）饥饿休克作为HP的代谢增强剂 毒性我们的方法与以前的工作的主要区别是强调 DNA和染色体损伤，对遗传范围的显著扩大和对检测 增强芬顿能力的具体方法我们在这个项目中的长期目标是了解 一方面是灾难性的染色体断裂背后的机制， 另一方面负责HP毒性的增强。

Hydrogen peroxide is a bio-specific toxin, inert with common organic or inorganic molecules, but in sufficient concentrations killing any type of cells almost on contact, using cellular iron to produce highly-reactive oxidizing species (Fenton's reaction). Chromosomal DNA is the main cellular target of HP poisoning, although the nature of lethal chromosomal damage is still unknown. Even more confusingly, HP turns out to be a surprising choice for a bio- weapon, as the killing concentrations are 1,000-fold higher than the physiological ones, while accumulation of HP in a particular cellular compartment is problematic, because its small size and uncharged nature facilitates diffusion through membranes. Yet, our immune cells somehow use these much lower HP concentrations to efficiently kill invading microbes, by unclear mechanisms. Remarkably, HP toxicity is synergized by other simple molecules, like nitric oxide (NO) or cyanide (CN). We hypothesize that our immune cells use otherwise insufficient HP concentrations to kill bacteria by accumulating potentiator molecules (for example, NO) in the compartments where high [HP] does not accumulate. However, the metabolic mechanisms behind potentiated HP toxicity, thought to elevate the intracellular free iron, are inconsistent with the newest results, while the mechanisms of irreparable chromosomal damage remain mostly unclear. Our recent studies of HP+CN co-toxicity uncovered new aspects of the phenomenon, like iron recruitment from intracellular depots directly to DNA, or catastrophic chromosome fragmentation, which is responsible for the cell killing. We propose to study HP+NO co-toxicity with three specific aims: 1) the nature of this synergistic toxicity and the targets of NO action; 2) the DNA mechanisms behind the catastrophic chromosomal fragmentation; 3) hunger shock as a metabolic potentiator of HP toxicity. The major difference of our approach from the previous work is the emphasis on DNA and chromosome damage, on the significantly expanded genetic scope and on testing specific ways to enhance Fenton. Our long-term goals in this project are to understand the mechanisms behind the catastrophic chromosome fragmentation on the one hand, and those responsible for potentiation of HP toxicity on the other.