Wednesday, October 19, 2011

Divide to Survive

Mitochondria are critical cellular sources of energy in the form of ATP within metazoan cells. During cell division, it is imperative that each daughter cell receive a competent complement of mitochondria—for which the mitochondria need to be separated by a fi ssion process. Fission is promoted by a large GTPase, DRP1, itself a target of a mitotic kinase cyclin B–CDK1. Kashatus et al. asked how mitochondrial fission is linked to cell division in human tissue culture cells. They found that, during mitosis, another mitotic kinase, Aurora A, phosphorylates a Ras-like GTPase, RALA, which localizes to the mitochondria, in turn recruiting its effector RALBP1 and DRP1. Interfering with this process by reducing the amounts of RALA or RALBP1 impaired mitochondrial fission at mitosis and led to improper segregation of mitochondria to daughter cells during cytokinesis. Under these circumstances, cell numbers and levels of ATP were reduced. This coordination of mitochondrial fission and segregation during cell division is thus a key factor in maintaining cellular health.



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