Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, McGovern Institute for Brain Research, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China.
Biol Cell. 2024 Sep;116(9):e2400064. doi: 10.1111/boc.202400064. Epub 2024 Jul 19.
Microtubules serve as integral components in cellular operations such as cell division, intracellular trafficking, and cellular architecture. Composed of tubulin protein subunits, these hollow tubular structures have been increasingly elucidated through advanced cryo-electron microscopy (Cryo-EM), which has unveiled the presence of microtubule inner proteins (MIPs) within the microtubular lumen.
In the present investigation, we employ a synergistic approach incorporating high-pressure freezing, cryo-focused ion beam milling, and Cryo-electron tomography (Cryo-ET) to interrogate the in situ architecture of microtubules in Caenorhabditis elegans larvae. Our Cryo-ET assessments across neuronal cilia and diverse tissue types consistently demonstrate the formation of annular configurations within the microtubular lumen.
In concert with recently characterized MIPs, our in situ observations within a living organism corroborate the hypothesis that intricate luminal assemblages exist within microtubule scaffolds. These findings necessitate further exploration into the molecular constituents and functional ramifications of these internal microtubular configurations in both cellular physiology and pathophysiology.
微管作为细胞操作的基本组成部分，如细胞分裂、细胞内运输和细胞结构。这些中空管状结构由微管蛋白亚基组成，通过先进的冷冻电子显微镜（Cryo-EM）得到了越来越多的阐明，揭示了微管内腔中存在微管内蛋白（MIPs）。
在本研究中，我们采用了一种协同方法，结合高压冷冻、冷冻聚焦离子束铣削和冷冻电子断层扫描（Cryo-ET），来研究秀丽隐杆线虫幼虫中微管的原位结构。我们对神经元纤毛和不同组织类型的 Cryo-ET 评估一致表明，在微管内腔中形成了环状结构。
与最近表征的 MIPs 一致，我们在活体生物体内的原位观察证实了这样一种假设，即在微管支架内存在复杂的内腔组装。这些发现需要进一步探索这些内部微管结构在细胞生理学和病理生理学中的分子组成和功能影响。
