Researchers at the Centre for Genomic Regulation (CRG) have discovered how proteins work in tandem to regulate 'treadmilling', a mechanism used by the network of microtubules inside cells to ensure proper cell division. Researchers at the Centre for Genomic Regulation (CRG) have discovered how proteins work in tandem to regulate 'treadmilling', a mechanism used by the network of microtubules inside cells to ensure proper cell division.

 

For the spindle to function properly, cells rely on microtubules to 'treadmill'. This involves one end of the microtubule (known as the minus end) to lose components while the other (the plus end) adds components. The effect is like that of a treadmill conveyor belt, where the microtubules appear to be moving continuously without changing their overall length. Treadmilling is crucial for cell division. "The most likely theory is that treadmilling helps the cell regulate its attachments to chromosomes by maintaining tension. Because microtubules are often growing from their plus ends, this tension can be provided by constant shrinking from the minus ends.

 

Three proteins were found to be critical for regulating treadmilling: KIF2A, a protein belonging to a larger family of proteins that dismantles microtubules, the γ-tubulin ring complex (γ-TuRC), a scaffold for microtubules to grow from, and spastin, an enzyme that acts like a scissor cutting microtubules. The family of proteins that dismantle microtubules usually nibble on microtubules at both ends. Before KIF2A can nibble a minus end, it needs to overcome yTuRC, which acts like a safety cap. The researchers found that the correct control of treadmilling requires the coordinated action of all three proteins. While the study does not directly translate into therapeutic avenues, it adds another piece to the intricate puzzle of cellular function and division.