A role of reactive oxygen species in apoptotic activation of volume-sensitive Cl(-) channel.
Apoptotic volume decrease is a pivotal event triggering a cell to undergo apoptosis and is induced by ionic effluxes resulting mainly from increased K(+) and Cl(-) conductances. Here, we demonstrate that in human epithelia HeLa cells both mitochondrion- and death receptor-mediated apoptosis inducers [staurosporine and Fas ligand or tumor necrosis factor (TNF)-alpha] rapidly activate Cl(-) currents that show properties phenotypical of volume-sensitive outwardly rectifying Cl(-) channel currents, including outward rectification, voltage-dependent inactivation gating at large positive potentials, inhibition by osmotic shrinkage, sensitivity to classic Cl(-) channel blockers, and dependence on cytosolic ATP. Staurosporine, but not Fas ligand or TNF-alpha, rapidly (within 30 min) increased the intracellular level of reactive oxygen species (ROS). A ROS scavenger and an NAD(P)H oxidase inhibitor blocked the current activation by staurosporine but not by Fas ligand or TNF-alpha. A ROS scavenger also inhibited apoptotic volume decrease, caspase-3 activation, and apoptotic cell death induced by staurosporine. Thus, it is concluded that an apoptosis-triggering anion conductance is carried by the volume-sensitive outwardly rectifying Cl(-) channel and that the channel activation on apoptotic stimulation with staurosporine, but not with Fas ligand or TNF-alpha, is mediated by ROS.
Shimizu
Takahiro
T
Department of Cell Physiology, National Institute for Physiological Sciences, and Japan Science and Technology Agency, Okazaki 444-8585, Japan.
Numata
Tomohiro
T
Okada
Yasunobu
Y
D017209:Apoptosis / Q000187:drug effects; D018118:Chloride Channels / Q000378:metabolism*; D053222:Fas Ligand Protein; D006367:HeLa Cells; D006801:Humans; D008562:Membrane Glycoproteins / Q000494:pharmacology; D017382:Reactive Oxygen Species; D019311:Staurosporine / Q000494:pharmacology
D018118:Chloride Channels; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D019311:Staurosporine