Biological complexity:cell division controls of mitochondria (Introduction)

by David Turell , Thursday, March 25, 2021, 14:33 (1121 days ago) @ David Turell

Amazing action within the cell as it divides mitochondria:

https://www.nature.com/articles/d41586-021-00511-3?WT.ec_id=NATURE-20210325&utm_sou...

"Using cutting-edge light-microscopy technology, the authors report evidence that these actin waves have a role in mitochondrial partitioning during mitosis of human cells. Like chromosomal partitioning, mitochondrial inheritance depends on dynamic processes orchestrated by the cytoskeleton — yet it turns out that these partitioning events occur in a completely different way.

"The authors describe three modes of interaction between mitochondria and actin during mitosis. Previous work5 suggested that the myosin motor protein Myo19 dynamically tethers mitochondria to an actin network and maintains the distribution of mitochondria throughout the cytoplasm. First, Moore and colleagues observed this process in greater detail than had been reported previously, and found that it is independent of the presence of actin waves. Second, within a wave, mitochondria are encased by what looks like clouds of actin filaments that seem to immobilize the organelles. And third, sometimes these clouds ‘opened’, to be followed by an astonishing burst of mitochondrial movement. The organelles were propelled by the rapid growth (polymerization) of actin filaments. This generated what looks like a comet tail made of actin. These mitochondrial movements were rapid, randomly oriented, and covered substantial distances in the cell.

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"The authors present stunning images of twin actin tails emanating from the front of mitochondria and extending behind the organelle, similar to the contrails left in the sky by twin-engine aircraft. The comet tails that Moore and colleagues observed were often slightly twisted.

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"The authors fed their experimental data into computer models, and the results suggest that the actin waves trigger bursts of movement driven by comet tails that randomly distribute mitochondria during cell division. This activity promotes organelle dispersion, and ensures that the burden of damaged mitochondria is evenly split between the two daughter cells of the mitotic division.

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"A previous study reported that revolving actin waves regulate the balance between the division and fusion of mitochondria during the interphase stage of the cell cycle, which precedes mitosis. It will be important to discover whether mitochondrial movement, interconnectivity and dispersion are processes that mutually affect each other.

"Certain types of cell divide asymmetrically and generate daughter cells with different fates. During the division of a stem cell, the older mitochondria in the dividing cell are preferentially partitioned to the daughter cell that is destined to differentiate, whereas the younger and ‘fitter’ mitochondria are apportioned to the daughter cell that maintains stem-cell properties. One can predict, therefore, that mitochondria mixing is suppressed in these cells and that other, as yet unknown, mechanisms ensure the asymmetric inheritance of mitochondria. Clearly, mitochondrial research will yield many more surprises in the future.

Comment: As the complexity is explored at sub-microscopic levels the evidence for a required designer grows. View the article to see the figures of the processes.