Editors' ChoiceCell Biology

Many Mitochondria

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Science's STKE  09 Apr 2002:
Vol. 2002, Issue 127, pp. tw128
DOI: 10.1126/stke.2002.127.tw128

Mitochondria have critical roles in important signaling processes. However, it has been unclear whether the mitochondria are actually multiple individual organelles or a continuous network more like the endoplasmic reticulum. This morphology, of course, has substantial implications for how mitochondria contribute to signaling processes. For example, a continuous network might allow calcium signals to be rapidly distributed in the cell, whereas if discrete organelles exist, some might be depolarized to promote apoptosis, while others continued to provide energy in the form of ATP. Collins et al. present evidence from microscopy of multiple cell types that the mitochondria are present as distinct organelles. They do not show rapid recovery in experiments monitoring fluorescence recovery after photobleaching (FRAP) of a mitochondrial marker. Studies with fluorescent indicators that respond to mitochondrial membrane potential also indicated that individual mitochondria can function independently. The authors emphasize that mitochondrial morphology itself is regulated and will reflect the status or recent history of the cell, perhaps explaining to some extent the disparate interpretations of mitochondrial morphology that can be found in the literature.

T. J. Collins, M. J. Berridge, P. Lipp, M. D. Bootman, Mitochondria are morphologically and functionally heterogeneous within cells. EMBO J. 21, 1616-1627 (2002). [Abstract] [Full Text]