Cell culture system for modeling oxidative stress

生物系统中的氧化应激可由有害的活性氧分子的过度产生或这些分子一旦形成就无法解毒引起，并可能导致细胞损伤。在细胞中自然出现的还原和氧化条件之间的斗争通常被称为氧化还原状态。正常氧化还原状态下的氧化还原障碍可以通过增加活性氧物种(ROS)的产生而导致毒性效应，如过氧化氢和氧自由基，导致细胞的基本成分包括DNA、膜和蛋白质的损害。尽管流行的观点认为ROS会对细胞成分造成非特异性的损害，新的证据表明，ROS可以靶向特定的蛋白质，导致其活性的改变。在细胞膜和称为线粒体的特殊细胞器中产生的低水平的ROS，可以触发氧化还原信号事件。这些事件随后可以导致细胞核中基因表达增加，或者激活保护性抗氧化反应，或者，如果ROS水平较高，启动细胞程序性死亡。二硫键是氧化应激过程中蛋白质之间形成的一种化学键。最近在酵母和细菌中的研究表明，在特定的氧化剂感应蛋白中形成二硫键导致了它们的激活。新的证据表明，哺乳动物细胞中也可能存在类似的二硫键控制的激活系统。细胞培养模型是理解氧化应激如何激活氧化还原信号过程的关键。通过在高或低氧水平下培养动物来源的细胞，有可能模拟组织中发生的ROS的生理波动。此外，添加称为细胞因子的炎症因子也可以导致细胞内ROS的产生并触发细胞死亡。发展氧化应激的细胞培养模型并从这些细胞中分离二硫键结合蛋白可以深入了解细胞的氧化还原状态如何影响正常和疾病相关的信号传递过程。

Oxidative stress in a biological system can be caused by the overproduction of harmful reactive oxygen molecules or the inability to detoxify these molecules once formed, and can result in cellular damage.  The struggle between the reducing and oxidizing conditions that naturally arise in cells is often referred to as the "redox" state.  Disturbances in the normal redox state can cause toxic effects through the increased production of reactive oxygen species (ROS), such as peroxides and oxygen free radicals, leading to damage of essential components of the cell including DNA, membranes and proteins.  Although the prevailing opinion has been that ROS cause non-specific damage to cellular components, new evidence suggests that ROS can target specific proteins leading to a change in their activity.  Low levels of ROS, produced at the cell membrane and in specialized organelles called mitochondria, can trigger redox signaling events.  These events can then lead to increased gene expression in the nucleus and either activation of a protective anti-oxidant response or, if the levels of ROS are high, the initiation of programmed cell death.  Disulfide bonds are a type of chemical linkage formed between proteins during oxidative stress.  Recent studies in yeast and bacteria have shown that the formation of disulfide bonds within specific oxidant sensing proteins leads to their activation.  New evidence suggests that a similar disulfide-bond controlled activation system may also occur in mammalian cells.  Cell culture models are key to understanding how oxidative stress can activate redox signaling processes.  By culturing animal-derived cells in the presence of either high or low oxygen levels, it is possible to mimic the physiological fluctuations of ROS that occur in tissues.  In addition, addition of inflammatory factors called cytokines can also cause the production of ROS within cells and trigger cell death.  The development of cell culture models of oxidative stress and the isolation of disulfide bonded proteins from these cells can provide insight into how the cellular redox state influences both normal and disease-associated signaling processes.