National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R01 GM138854
米国
引用
ジャーナル: Nat Commun / 年: 2024 タイトル: HURP facilitates spindle assembly by stabilizing microtubules and working synergistically with TPX2. 著者: Venecia Alexandria Valdez / Meisheng Ma / Bernardo Gouveia / Rui Zhang / Sabine Petry / 要旨: 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 ...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.