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Mitochondrial Fission, Fusion, and Stress

Mitochondrial Dynamics Mitochondria—the powerhouses of the cell—are autonomous organelles with their own genomes. Within cells, mitochondria are remarkably dynamic, continually moving around the cytoplasm and undergoing fusion and fission reactions. Youle and van der Bliek (p. 1062) review the importance of mitochondrial fusion and fission in cellular responses to stress, interference with which are likely to play an important role in a variety of diseases including Parkinson's disease. In their Perspective, Hoppins and Nunnari explain that the endoplasmic reticulum is an active participant in mitochondrial division and discuss how mitochondrial dynamics and cell death are linked. Mitochondrial fission and fusion play critical roles in maintaining functional mitochondria when cells experience metabolic or environmental stresses. Fusion helps mitigate stress by mixing the contents of partially damaged mitochondria as a form of complementation. Fission is needed to create new mitochondria, but it also contributes to quality control by enabling the removal of damaged mitochondria and can facilitate apoptosis during high levels of cellular stress. Disruptions in these processes affect normal development, and they have been implicated in neurodegenerative diseases, such as Parkinson’s.