Cell culture system for modeling oxidative stress

生物系统中的氧化应激可由有害活性氧分子的过量产生或这些分子一旦形成就无法解毒引起，并可导致细胞损伤。细胞中自然产生的还原和氧化状态之间的斗争通常被称为“氧化还原”状态。正常氧化还原状态的干扰可通过增加活性氧（ROS）的产生（如过氧化物和氧自由基）引起毒性作用，导致细胞的基本成分（包括DNA、膜和蛋白质）受损。尽管主流观点认为活性氧对细胞成分造成非特异性损伤，但新的证据表明，活性氧可以靶向特异性蛋白质，导致其活性发生变化。低水平的活性氧产生于细胞膜和称为线粒体的特殊细胞器，可以触发氧化还原信号事件。这些事件随后会导致细胞核中基因表达的增加，并激活保护性抗氧化反应，或者，如果ROS水平高，则启动程序性细胞死亡。二硫键是氧化应激过程中蛋白质之间形成的一种化学键。最近对酵母和细菌的研究表明，在特定的氧化感应蛋白中形成二硫键导致它们的激活。新的证据表明，类似的二硫键控制激活系统也可能发生在哺乳动物细胞中。细胞培养模型是理解氧化应激如何激活氧化还原信号传导过程的关键。通过在高或低氧水平下培养动物源性细胞，可以模拟组织中ROS的生理波动。此外，被称为细胞因子的炎症因子的加入也会引起细胞内ROS的产生并引发细胞死亡。氧化应激细胞培养模型的发展和从这些细胞中分离二硫键结合蛋白可以深入了解细胞氧化还原状态如何影响正常和疾病相关的信号传导过程。

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.