【摘要】 线粒体对于细胞钙信号和活性氧信号转导有重要的调控作用.超氧炫是新近发现的单个线粒体超氧阴离子短时程爆发现象,反映了活性氧生成动力学的一种新形式.线粒体钙信号作为重要的细胞功能调控信号,能否及如何调控超氧炫尚待深入研究.本研究对HeLa细胞进行高胞外钙和离子霉素刺激,或用皂苷穿孔细胞质膜后置于高钙细胞内液中,两种方法均显著增加了超氧炫发生的频率.其中,穿孔细胞胞浆高钙诱导的超氧炫依赖于线粒体钙单向转运体,表明超氧炫由线粒体基质内高钙信号所诱发.重要的是,离子霉素诱导的超氧炫发生频率与线粒体稳态钙水平线性相关,而与瞬态线粒体钙无相关性,提示钙离子对超氧炫的调控是一个多步骤、相对缓慢的过程.综上,线粒体基质的稳态高钙是超氧炫的重要调控因子.更多还原

【Abstract】 The mitochondria play an essential role in both intracellular calcium signaling and reactive oxygen species(ROS)signaling. As a newly discovered universal and fundamental mitochondrial phenomenon, superoxide flashes reflect transient bursts of superoxide formation in the matrix of single mitochondria. Whether and how the superoxide flash activity is regulated by mitochondrial calcium remain largely unknown. In this study, it is demonstrated that elevating mitochondrial calcium either by the calcium ionophore ionomycin or by increasing the bathing calcium in saponin-permeabilized cells effectively augmented the superoxide flash incidence. Inhibition of the mitochondrial calcium uniporter activity abolished the flash response in the permeabilized cells. Quantitatively, the superoxide flash incidence linearly correlated with the steady-state mitochondrial calcium level, with 1.7-fold increase in flash incidence per 1.0 F/F0of Rhod-2. In contrast, large mitochondrial calcium transients(e.g. Rhod-2 peak: F/F0~3.8,duration ~2 min) in the absence of steady-state elevations failed to increase the flash activity. These results indicate that mitochondrial calcium is a potent regulator of superoxide flashes, but its mechanism of action likely involves a multi-step, slow onset process.更多还原