Mitochondrial Movements
May Shed Light
On ALS, Other Diseases

Watching the movements of mitochondria, the energy-producing miniature organs (organelles) inside cells, under a variety of conditions has just gotten easier, thanks to a new set of laboratory tools developed by Jeff Lichtman at Harvard University and colleagues.

Mitochondria are particularly vital in nerve and muscle cells, which require a constant energy supply, and abnormalities of mitochondria play a role in mitochondrial myopathies, Friedreich’s ataxia, some types of Charcot-Marie-Tooth disease and probably other neuromuscular disorders. Deficient transport of mitochondria up and down nerve fibers is suspected of contributing to nerve cell loss in amyotrophic lateral sclerosis (ALS).

In the July issue of Nature Methods, Lichtman describes how the group developed and bred mice with fluorescent proteins that light up only the mitochondria. These “MitoMice” allow researchers to take time-lapse photographs of moving mitochondria in living animals.

Already, they say, they’ve learned a lot from experimenting with these mice. For one thing, they now know that, under normal circumstances, more mitochondria are moving away from the nerve cell body (anterograde transport) than are moving back toward it (retrograde transport) at any given time. This suggests, they say, that some portion of the organelles are destroyed before they head back to the nerve cell.

The researchers have already begun using the MitoMice to study nerve injuries, and they say the mice can also be used to study diseases.