Pair of proteins repairs cellular highway system
The microtubules that help transport materials around cells are constantly being dismantled when no longer required and rebuilt in new places where they are needed. This is especially important in nerve cells, which are very long and so rely on long-distance transport of nutrients and information for survival. Because problems with these microtubule ‘highways’ can lead to nervous system disorders, it is important to understand how cells build and maintain microtubules so that doctors can intervene when this cellular infrastructure deteriorates.
IRP researchers, led by Antonina Roll-Mecak, Ph.D., examined two proteins — spastin and katanin — that are defective in patients with neurological conditions linked to defective microtubules. The scientists discovered that these proteins remodel microtubule highways by removing old segments and replacing them with newer and stronger ones. The IRP team further showed that this repair reinforces microtubules and quickly increases the number of highways available for transport by promoting the growth of new ones where the cell needs them.
Spastin and katanin are known to be defective in a group of inherited neurological disorders called hereditary spastic paraplegias, as well as in microcephaly patients who have abnormally small or underdeveloped brains. Identifying the true role of these proteins — the rejuvenation of cellular microtubule highways — advances our understanding of what goes wrong in hereditary spastic paraplegias and microcephaly and creates the opportunity to find medicines that harness spastin and katanin in order to preserve good cellular health and repair the damage done by neurodegenerative diseases.
Vemu, A, Szczesna, E, Zehr, EA, Spector JO, Grigorieff NG, Deaconescu AM, Roll-Mecak A. (2018). Severing enzymes amplify microtubule arrays through lattice GTP-tubulin incorporation. Science. 361(6404). ppi: eaau1504. doi: 10.1126.