Related Experiment Video
Updated: Oct 10, 2026

Single Plane Illumination Module and Micro-capillary Approach for a Wide-field Microscope
Published on: August 15, 2014
Superoxide radical-initiated apoptotic signalling pathway in selenite-treated HepG(2) cells: mitochondria serve as
1Department of Community, Occupational, and Family Medicine, Faculty of Medicine, National University of Singapore, Singapore. cofshm@nus.edu.sg
Abstract:
The exact role of superoxide radicals (O(2)(*)(-)) in apoptosis is still a matter of debate. The main objective of the present study is to evaluate the apoptotic signalling pathway initiated by O(2)(*)(-). The reductive reaction of sodium selenite with glutathione was used as the intracellular O(2)(*)(-)-generating system. When cells were exposed to 5 to 25 microM selenite, a temporal pattern of apoptotic events was observed following the elevation of O(2)(*)(-), in which cytochrome c release and mitochondrial depolarization preceded caspase-3 activation and DNA fragmentation. The simultaneous treatment with N-acetylcysteine and 4-hydroxy-2,2,6, 6-tetramethylpiperidine-N-oxyl markedly reduced O(2)(*)(-) level and suppressed the mitochondrial changes and the downstream apoptotic events. Moreover, pretreatment with cyclosporin A plus trifluoperazine, two mitochondrial permeability transition (MPT) inhibitors, was capable of attenuating O(2)(*)(-)-mediated cytochrome c release and mitochondrial depolarization, and subsequently inhibiting apoptosis. Thus, the present results provide convincing evidence that O(2)(*)(-) generated from the reductive reaction of selenite with GSH is capable of triggering a mitochondria-dependent apoptotic pathway. Such knowledge may not only help to obtain a better understanding of the apoptotic effect of selenite per se, but of the role of O(2)(*)(-) in initiation and execution of apoptosis.
Related Concept Videos
Electron Transport Chain: Complex I and II
ROS generation is regulated and maintained at moderate levels necessary...
Cellular Injury V: Apoptosis and Autophagy
The Intrinsic Apoptotic Pathway
Overview of Cell Death
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...
Phagocytosis of Apoptotic Cells
Normal cells contain receptors that prevent them from being recognized by phagocytes.
The Extrinsic Apoptotic Pathway