A multicomponent assembly pathway contributes to the formation of acentrosomal microtubule arrays in interphase Drosophila cells
A multicomponent assembly pathway contributes to the formation of acentrosomal microtubule arrays in interphase Drosophila cells
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DOI：
10.1091/mbc.e07-10-1069
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发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Rogers, Stephen L.
中科院分区：
文献类型：
--
作者：
Rogers, Gregory C.;Rusan, Nasser M.;Rogers, Stephen L.
在动物细胞中，中心体形成微管，形成极化阵列来组织细胞质。然而，果蝇呈现出一个有趣的悖论，当中心体缺陷的突变动物发育成可存活的成年动物时。为了理解这种差异，我们使用活细胞成像、电子显微镜和RNAi相结合的方法，分析了培养和体内果蝇细胞中中心体和微管的行为。动物细胞中中心体功能周期的规范模型表明，中心体在整个细胞周期中充当微管组织中心。出乎意料的是，我们发现许多果蝇细胞类型显示出一个改变的周期，其中功能中心体仅在细胞分裂期间存在。在有丝分裂结束时，中心体解体产生含有中心粒的间期细胞，中心粒缺乏微管成核活性。此外，稳态间相微管水平不会因编码消耗两种γ -微管蛋白而改变。然而，γ -微管蛋白RNAi在解聚后延迟微管再生，这表明它可能与另一途径部分冗余地起作用。因此，我们检测了额外的微管成核因子，发现迷你纺锤体、CLIP-190、EB1或动力蛋白RNAi也会延迟微管的再生；令人惊讶的是，当我们消耗γ -微管蛋白时，这种情况并没有进一步延长。综上所述，这些结果修正了我们对中心体功能周期的看法，并揭示了在果蝇中建立间期微管阵列的多组分无丝胞体微管组装途径。
In animal cells, centrosomes nucleate microtubules that form polarized arrays to organize the cytoplasm. Drosophila presents an interesting paradox however, as centrosome-deficient mutant animals develop into viable adults. To understand this discrepancy, we analyzed behaviors of centrosomes and microtubules in Drosophila cells, in culture and in vivo, using a combination of live-cell imaging, electron microscopy, and RNAi. The canonical model of the cycle of centrosome function in animal cells states that centrosomes act as microtubule-organizing centers throughout the cell cycle. Unexpectedly, we found that many Drosophila cell-types display an altered cycle, in which functional centrosomes are only present during cell division. On mitotic exit, centrosomes disassemble producing interphase cells containing centrioles that lack microtubule-nucleating activity. Furthermore, steady-state interphase microtubule levels are not changed by codepleting both gamma-tubulins. However, gamma-tubulin RNAi delays microtubule regrowth after depolymerization, suggesting that it may function partially redundantly with another pathway. Therefore, we examined additional microtubule nucleating factors and found that Mini-spindles, CLIP-190, EB1, or dynein RNAi also delayed microtubule regrowth; surprisingly, this was not further prolonged when we codepleted gamma-tubulins. Taken together, these results modify our view of the cycle of centrosome function and reveal a multi-component acentrosomal microtubule assembly pathway to establish interphase microtubule arrays in Drosophila.