Superoxide constitutes a major signal of mitochondrial superoxide flash.

Xing Zhang, Zhanglong Huang, Tingting Hou, Jiejia Xu, Yanru Wang, Wei Shang, Tao Ye, Heping Cheng, Feng Gao, Xianhua Wang

Department of Physiology, The Fourth Military Medical University, Xi'an 710032, China.

Life sciences 2013 Aug 6

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Mitochondrial flashes detected with an N- and C-terminal circularly-permuted yellow fluorescent protein (cpYFP) have been thought to represent transient and quantal bursts of superoxide production under physiological, stressful and pathophysiological conditions. However, the superoxide nature of the cpYFP-flash has been challenged, considering the pH-sensitivity of cpYFP and the distinctive regulation of the flash versus the basal production of mitochondrial reactive oxygen species (ROS). Thus, the aim of the study is to further determine the origin of mitochondrial flashes. We investigated the origin of the flashes using the widely-used pH-insensitive ROS indicators, mitoSOX, an indicator for superoxide, and 2, 7-dichlorodihydrofluorescein diacetate (DCF), an indicator for H2O2 and other oxidants. Robust, quantal, and stochastic mitochondrial flashes were detected with either mitoSOX or DCF in several cell-types and in mitochondria isolated from the heart. Both mitoSOX-flashes and DCF-flashes showed similar incidence and kinetics to those of cpYFP-flashes, and were equally sensitive to mitochondria-targeted antioxidants. Furthermore, they were markedly decreased by inhibitors or an uncoupler of the mitochondrial electron transport chain, as is the case with cpYFP-flashes. The involvement of the mitochondrial permeability transition pore in DCF-flashes was evidenced by the coincidental loss of mitochondrial membrane potential and matrix-enriched rhod-2, as well as by their sensitivity to cyclosporine A. These data indicate that all the three types of mitochondrial flashes stem from the common physiological process of bursting superoxide and ensuing H2O2 production in the matrix of single mitochondrion. © 2013.

Citation

Xing Zhang, Zhanglong Huang, Tingting Hou, Jiejia Xu, Yanru Wang, Wei Shang, Tao Ye, Heping Cheng, Feng Gao, Xianhua Wang. Superoxide constitutes a major signal of mitochondrial superoxide flash. Life sciences. 2013 Aug 6;93(4):178-86