Lucas Jessica R
Department of Biology, University of Wisconsin-Oshkosh, Oshkosh, Wisconsin, USA.
Cytoskeleton (Hoboken). 2021 Jul;78(7):361-371. doi: 10.1002/cm.21689. Epub 2021 Oct 14.
Microtubule arrays drastically reorganize during the cell cycle to facilitate specific events. Many cells contain a centrosome that dictates the assembly and organization of microtubule arrays. However, plant cells and many others do not contain centrosomes or discrete microtubule organizing centers. In plants, microtubules nucleate and polymerize from gamma-tubulin-containing complexes in the interphase cell cortex. During plant cell division, microtubules nucleate near nuclei to form the mitotic spindle and plant-specific phragmoplast required for cytokinesis. Therefore, during the plant cell cycle, microtubule nucleation shifts from cell cortex to the perinuclear region. While it is unclear how this shift occurs, previous studies observed microtubules that appeared to extend from nuclei into the cortex as cells transitioned into interphase in small cells. These data led to the hypothesis that microtubule nucleation complexes move from the nuclear surface to the cortex at the transition from cytokinesis into interphase. Here we document GFP labeled microtubules in living plant cells during the transition from cytokinesis to interphase. We observed apparent groups of microtubules spanning between the nucleus and cell cortex in large, vacuolated epidermal leaf cells. We also observed microtubules in the cell cortex that appeared separate from perinuclear-associated microtubules. While these cortical microtubules were not always seen, when present they were apparent before cytokinesis was complete and/or before nuclear-associated microtubules were obvious. These data add to and deepen the knowledge of microtubule reorganization at this cell cycle transition.
微管阵列在细胞周期中会发生剧烈重组，以促进特定事件的发生。许多细胞含有一个中心体，它决定了微管阵列的组装和组织。然而，植物细胞和许多其他细胞不含中心体或离散的微管组织中心。在植物中，微管在间期细胞皮层中从含γ-微管蛋白的复合物中起始并聚合。在植物细胞分裂期间，微管在细胞核附近起始，形成有丝分裂纺锤体和胞质分裂所需的植物特有的成膜体。因此，在植物细胞周期中，微管起始从细胞皮层转移到核周区域。虽然尚不清楚这种转移是如何发生的，但先前的研究观察到，在小细胞进入间期时，微管似乎从细胞核延伸到皮层。这些数据导致了这样的假设，即在从胞质分裂到间期的转变过程中，微管起始复合物从核表面移动到皮层。在这里，我们记录了活植物细胞在从胞质分裂到间期转变过程中绿色荧光蛋白标记的微管。我们在大的、有液泡的表皮叶细胞中观察到明显的微管群横跨细胞核和细胞皮层。我们还在细胞皮层中观察到微管，它们似乎与核周相关微管分开。虽然这些皮层微管并不总是能看到，但当它们存在时，在胞质分裂完成之前和/或核相关微管明显之前就很明显了。这些数据增加并深化了对这个细胞周期转变过程中微管重组的认识。
