AI Article Synopsis
- Most vertebrate spindles utilize branching microtubule nucleation, where new microtubules form alongside existing ones.
- The study highlights the role of hepatoma up-regulated protein (HURP) in this process, showing it is essential for RanGTP-induced microtubule branching in Xenopus egg extract.
- HURP stabilizes the microtubule structure and shifts its function toward facilitating branching by localizing to TPX2 condensates, which are crucial for spindle assembly, supported by high-resolution cryo-EM imaging of HURP on microtubules.
Article Abstract
In vertebrate spindles, most microtubules are formed via branching microtubule nucleation, whereby microtubules nucleate along the side of pre-existing microtubules. Hepatoma up-regulated protein (HURP) is a microtubule-associated protein that has been implicated in spindle assembly, but its mode of action is yet to be defined. In this study, we show that HURP is necessary for RanGTP-induced branching microtubule nucleation in Xenopus egg extract. Specifically, HURP stabilizes the microtubule lattice to promote microtubule formation from γ-TuRC. This function is shifted to promote branching microtubule nucleation through enhanced localization to TPX2 condensates, which form the core of the branch site on microtubules. Lastly, we provide a high-resolution cryo-EM structure of HURP on the microtubule, revealing how HURP binding stabilizes the microtubule lattice. We propose a model in which HURP stabilizes microtubules during their formation, and TPX2 preferentially enriches HURP to microtubules to promote branching microtubule nucleation and thus spindle assembly.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11549357 | PMC |
| http://dx.doi.org/10.1038/s41467-024-53630-6 | DOI Listing |
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