WASHINGTON, D.C. April 8, 2013 A team of researchers, led by Marc Freeman, PhD, an early career scientist with the Howard Hughes Medical Institute and associate professor of neurobiology at the University of Massachusetts Medical School have discovered a gene in the fruit fly Drosophila melanogaster that, when mutant, blocks the self-destruction of damaged axons, which could hold clues to treating motor neuron diseases, such as amyotrophic lateral sclerosis (ALS).
A neuron has a very distinctive form a bush of dendrites that receive signals, an incredibly long axon, which is like a long tail, and "a little dot" between them that is the cell body, housing the genetic headquarters. Every part of the neuron is required for it to transmit messages. "If anything breaks along any part of the neuron, the cell unplugs from the circuit and no longer functions," explained Dr. Freeman, who presented this research at the Genetics Society of America's 54th Annual Drosophila Research Conference in Washington, D.C.
Once the long tail-like axon is damaged, it shrivels away, basically self-destructing, and resulting in neurons that no longer operate. This catastrophic damage can happen in several ways: from inflammation, a neurodegenerative disease, a metabolic disorder such as diabetes, toxin exposure, or tumor growth. Such axon loss is thought to be a primary factor that leads to functional loss in patients with neurological disorders it is equivalent to going into an electrical circuit and randomly cutting wires.
The study of axon destruction in response to damage goes back to British neurophysiologist Augustus Waller, who in 1850 described how an axon separated from the cell body and cut off from its nutrient supply breaks apart and is dismantled by scavenger cells. "The idea that this process, called Wallerian degeneration, was a passive wasting away of the axon held for 150 years," Dr. Freeman said.
Then in the late 1980s,
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Genetics Society of America