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J Cell Sci. 2002 Feb 1;115(Pt 3):485-97.

Menadione-induced apoptosis: roles of cytosolic Ca(2+) elevations and the mitochondrial permeability transition pore.

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1
Medical Research Council Secretory Control Research Group, Physiological Laboratory, University of Liverpool L69 3BX, UK.

Abstract

In normal pancreatic acinar cells, the oxidant menadione evokes repetitive cytosolic Ca(2+) spikes, partial mitochondrial depolarisation, cytochrome c release and apoptosis. The physiological agonists acetylcholine and cholecystokinin also evoke cytosolic Ca(2+) spikes but do not depolarise mitochondria and fail to induce apoptosis. Ca(2+) spikes induced by low agonist concentrations are confined to the apical secretory pole of the cell by the buffering action of perigranular mitochondria. Menadione prevents mitochondrial Ca(2+) uptake, which permits rapid spread of Ca(2+) throughout the cell. Menadione-induced mitochondrial depolarisation is due to induction of the permeability transition pore. Blockade of the permeability transition pore with bongkrekic acid prevents activation of caspase 9 and 3. In contrast, the combination of antimycin A and acetylcholine does not cause apoptosis but elicits a global cytosolic Ca(2+) rise and mitochondrial depolarisation without induction of the permeability transition pore. Increasing the cytosolic Ca(2+) buffering power by BAPTA prevents cytosolic Ca(2+) spiking, blocks the menadione-elicited mitochondrial depolarisation and blocks menadione-induced apoptosis. These results suggest a twin-track model in which both intracellular release of Ca(2+) and induction of the permeability transition pore are required for initiation of apoptosis.

PMID:
11861756
[Indexed for MEDLINE]
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