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Side view of a network of microtubule inside the axon of a neuron. Red blobs represent linker proteins that attach two microtubules together at at a point.
Microtubule Modifications lead to Neuron Stability
Axons, the long projections on neurons, are made stronger by a unique modification of the common molecular building block of the cell skeleton, microtubules. The finding, which may help guide the search for treatments for neurodegenerative diseases, was reported in the April 10 issue of Neuron by researchers at the University of Illinois at Chicago College of Medicine.
"Except for neurons, cells’ microtubules are in constant dynamic flux — being taking apart and rebuilt," says Scott Brady, professor and head of anatomy and cell biology at UIC and principal investigator on the study. But only neurons grow so long, he said, and once created they must endure throughout a person’s life, as much as 80 to 100 years. Brady had been able to show some time ago that the neuron’s stability depended on a modification of tubulin.
Yuyu Song, a former graduate student in Brady’s lab used a variety of methods to determine the nature of the modification and where it occurs.She found that tubulin is modified by the chemical bonding of polyamines, positively charged molecules, at sites that might otherwise be chinks where tubulin could be broken down, causing the microtubules to fall apart. She was also able to show that the enzyme transglutaminase was responsible for adding the protective polyamines.