How does a millimeter-sized cell find its center?
How does a millimeter-sized cell find its center?
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DOI：
10.4161/cc.8.8.8150
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发表时间：
2009-04-15
期刊：
影响因子：
--
通讯作者：
Mitchison TJ
中科院分区：
文献类型：
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作者：
Wühr M;Dumont S;Groen AC;Needleman DJ;Mitchison TJ
微管在真核细胞的核定中心或有丝分裂中起核心作用。然而，尽管通常使用微管进行定心，但物理机制可能差异很大，并取决于细胞大小和细胞类型。在小的分裂酵母细胞中，细胞核可以通过生长的微管撞击细胞边界时产生的推力而居中。这种机制在较大的细胞中可能是不可能的，因为微管可以承受的压缩力受到屈曲的限制，因此最大力随着微管长度而减小。在一个研究充分的中型细胞中，C。在线虫的受精卵中，中心体由皮层附着的马达控制，马达拉动微管。这种机制被广泛认为是一般较大的细胞。然而，在一个非常大的细胞，两栖动物受精卵的经典实验的重新评估，反对这种普遍性。在这些大的卵中，由于星形微管太短而不能到达相反的细胞边界，因此不能通过皮层牵拉来调节紫苑从它们所接触的细胞边界的一部分移开。一个世纪前，Herlant和Brachet发现单个卵内的多个紫苑相对于细胞边界中心，但也相对于彼此。在这里，我们总结了目前的理解微管组织在非洲爪蟾受精卵的第一个细胞周期，讨论如何微管紫苑向这个非常大的细胞的中心，以及如何多个紫苑形状和位置相对于彼此。
Microtubules play a central role in centering the nucleus or mitotic in eukaryotic cells. However, despite common use of microtubules for centring, physical mechanisms can vary greatly, and depend on cell size and cell type. In the small fission yeast cells, the nucleus can be centered by pushing forces that are generated when growing microtubules hit the cell boundary. This mechanism may not be possible in larger cells, because the compressive force that microtubules can sustain are limited by buckling, so maximal force decreases with microtubule length. In a well-studied intermediate sized cell, the C. elegans fertilized egg, centrosomes are centered by cortex-attached motors that pull on microtubules. This mechanism is widely assumed to be general for larger cells. However, re-evaluation of classic experiments in a very large cell, the fertilized amphibian egg, argues against such generality. In these large eggs, movement of asters away from a part of the cell boundary that they are touching cannot be mediated by cortical pulling, because the astral microtubules are too short to reach the opposite cell boundary. A century ago, Herlant and Brachet discovered that multiple asters within a single egg center relative to the cell boundary, but also relative to each other. Here, we summarize current understanding of microtubule organization during the first cell cycle in a fertilized Xenopus egg, discuss how microtubule asters move towards the center of this very large cell, and how multiple asters shape and position themselves relative to each other.