Cell Biology

Death Throes in Living Color

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Science  05 Oct 2007:
Vol. 318, Issue 5847, pp. 19
DOI: 10.1126/science.318.5847.19c

Mitochondria—the tiny double-membrane-bounded organelles that provide healthy cells with a ready supply of energy—also play a key role in the triggering of programmed cell death or apoptosis. Sun et al. have combined light microscopy and three-dimensional electron microscopic tomography to record in detail the structural changes in mitochondria in cells that have been stimulated to undergo apoptosis. One of the first events observed after stimulation was a rearrangement of sub-mitochondrial morphology: The inner mitochondrial membrane changed from an organized arrangement of folded membrane cristae into a vesicular patchwork, which was accompanied by the release of several mitochondrial proteins into the cytosol. However, one key mitochondrial protein involved in the apoptosis pathway, cytochrome c, was released efficiently independently of and before this remodeling. Swelling of the mitochondria occurred after the collapse of the membrane potential and was accompanied by a dissolution of the intramitochondrial structure. This generation of a composite time-course overview of morphological changes within single cells should help to dissect a variety of nonsynchronous cellular events. — SMH

Nat. Cell Biol. 9, 1057 (2007).

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