A new UGA study published in the journal Nature has identified an enzyme that keeps the nervous system’s traffic flowing in the right direction, which could eventually lead to new treatments for conditions such as Alzheimer’s and Parkinson’s diseases.
“There was no medical or any other applied science drive for this project; it was purely curiosity about how transport inside cells works,” said study co-author Jacek Gaertig, professor of cellular biology. “But it looks like we have identified an important enzyme that acts in the nervous system.”
He said that cells contain a network of microtubules that are made of protein and serve as tracks for shuttling materials from one part of the cell to another. The traffic signs on this microtubule network are chemical additions such as acetylation marks.
Acetylation marks were discovered in 1983, and researchers recently determined their role in regulating the binding of the motor proteins that shuttle materials along microtubules. What has been unclear for more than 25 years, however, was the cellular process by which these marks are formed.
Through a series of studies using the microscopic protozoan Tetrahymena, the nematode C. elegans, zebrafish and human cancer cells, Gaertig and his colleagues revealed that a protein known as MEC-17 is the traffic engineer in charge of microtubule acetylation.
MEC-17 acts as an enzyme to catalyze the acetylation reaction on microtubules and is involved in the sensation of touch in nematodes. Its depletion in zebrafish results in neuromuscular defects. Importantly, previous research has shown that the levels of acetylation marks on microtubules are altered in human neurodegenerative diseases.
Gaertig said it is now possible for drug manufacturers to search for compounds that block or enhance the enzyme’s activity.
Graduate student Shilpa Akella and postdoctoral associate Dorota Wloga studied the enzyme in the protozoan and in vitro, while Jihyun Kim and Natalia Starostina showed how it worked in the nematode and found that the enzyme is active in cancer cells. The lab of Georgia Cancer Coalition Distinguished Scholar Scott Dougan deduced its role in zebrafish, and Sally Lyons-Abbott and Naomi Morrissette at the University of California biochemically purified microtubules marked by MEC-17.