Microtubules are critical components of a cell’s skeleton, playing essential roles in cell shape, transport, and division. For cells to maintain proper microtubule organization and perform these functions effectively, they must control microtubule assembly. This process, known as microtubule nucleation, is primarily driven by the γ-tubulin ring complex (γTuRC). However, the detailed mechanisms by which γTuRC regulates microtubule formation were not well understood, despite being linked to various diseases such as cancer and neurodegenerative disorders.
Our project aimed to uncover how γTuRC activates and controls microtubule nucleation at the molecular level. Recent advances, including determining the human γTuRC structure in high resolution and developing advanced microscopy techniques, provided a unique opportunity to tackle this challenge. We used a combination of biochemistry, structural analysis, and microscopy to investigate γTuRC’s regulation, focusing on understanding how the complex transitions from an inactive to an active state to initiate microtubule formation.
The study made significant progress by solving the high-resolution structure of γTuRC during microtubule nucleation. We discovered that γTuRC undergoes a dramatic structural change, forming a precise template for microtubule growth with a direct interaction with the microtubule itself. This finding challenged traditional models and suggested that microtubules play an active role in stabilizing their own nucleation process, providing new insights into how cells regulate microtubule organization.
We also explored the regulation of microtubule dynamics during cell division, specifically mitosis. During this process, γTuRC localizes at specific regions known as spindle poles, where it nucleates microtubules and caps their ends to stabilize them. However, these microtubules must also undergo controlled disassembly for proper chromosome separation. Our experiments demonstrated that γTuRC shields microtubule ends from depolymerization by a protein called KIF2A. Furthermore, we found that a second protein, spastin, works together with KIF2A to sever microtubules, allowing for controlled disassembly necessary for cell division.
These results significantly advance our understanding of how microtubule organization is maintained in cells and how imbalances in these processes can contribute to diseases like cancer, where errors in cell division lead to chromosomal instability. Moreover, since microtubule regulation is crucial in neurons for growth and synaptic function, the findings also hold potential for developing new strategies to treat neurodegenerative diseases such as Alzheimer’s and Huntington’s by targeting microtubule stability.
The project’s findings have been shared widely to maximize their impact. Key results were published in leading scientific journals, with our structural study of γTuRC featured in Science and earlier work on KIF2A published in the Journal of Cell Biology. The research was also presented at international conferences, facilitating engagement with experts and fostering new collaborations. In addition, we leveraged social media to disseminate our findings through the lab's Twitter account, making the research accessible to a broader audience.
In summary, our work has not only advanced the scientific understanding of microtubule regulation but also opened new avenues for potential medical applications in cancer treatment and neurobiology. By shedding light on the mechanisms controlling microtubule dynamics, the research lays a foundation for future therapeutic developments targeting the cytoskeleton.
