Mitotic spindle poles are organized by structural and motor proteins in addition to centrosomes.
Mitotic spindle poles are organized by structural and motor proteins in addition to centrosomes.
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DOI：
10.1083/jcb.138.5.1055
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发表时间：
1997-09-08
期刊：
影响因子：
--
通讯作者：
Compton DA
中科院分区：
文献类型：
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作者：
Gaglio T;Dionne MA;Compton DA
在脊椎动物体细胞中，微管集中在有丝分裂的纺锤体极中被认为是它们从中心体成核的结果。相反，这个简单的观点，在这篇文章中，我们表明，识别轻中间链的细胞质动力蛋白（70.1）的抗体破坏了集中组织微管负端和定位的核有丝分裂器蛋白质在纺锤体两极注射到培养的细胞在中期，尽管存在中心体。检查这种动力蛋白特异性抗体在体外使用无细胞系统进行有丝分裂星形细胞组装和在体内注射到培养的细胞后的效果表明，除了其对细胞质动力蛋白的直接作用外，这种抗体降低了动力蛋白与微管结合的效率，这表明抗体干扰了动力蛋白和动力蛋白在纺锤体/星形细胞组装过程中与微管的合作结合。这些结果表明，微管负端集中到主轴极在脊椎动物体细胞通过一种机制，涉及到中心体和结构和微管马达蛋白的贡献。此外，这些发现，连同最近的观察，即在从非洲爪蟾卵制备的提取物中，细胞质动力蛋白是形成和维持无中心体纺锤体极所必需的（Heald，R.，R.图尔内比兹布兰克河Sandaltzopoulos，P. Becker，A. Hyman和E.卡森提1996.自然（伦敦）。382：420-425）证明了在中心体和无中心体纺锤体中存在将游离微管负末端集中的共同机制。我们讨论了这些意见的背景下，搜索捕获的重点模型主轴组装。
The focusing of microtubules into mitotic spindle poles in vertebrate somatic cells has been assumed to be the consequence of their nucleation from centrosomes. Contrary to this simple view, in this article we show that an antibody recognizing the light intermediate chain of cytoplasmic dynein (70.1) disrupts both the focused organization of microtubule minus ends and the localization of the nuclear mitotic apparatus protein at spindle poles when injected into cultured cells during metaphase, despite the presence of centrosomes. Examination of the effects of this dynein-specific antibody both in vitro using a cell-free system for mitotic aster assembly and in vivo after injection into cultured cells reveals that in addition to its direct effect on cytoplasmic dynein this antibody reduces the efficiency with which dynactin associates with microtubules, indicating that the antibody perturbs the cooperative binding of dynein and dynactin to microtubules during spindle/aster assembly. These results indicate that microtubule minus ends are focused into spindle poles in vertebrate somatic cells through a mechanism that involves contributions from both centrosomes and structural and microtubule motor proteins. Furthermore, these findings, together with the recent observation that cytoplasmic dynein is required for the formation and maintenance of acentrosomal spindle poles in extracts prepared from Xenopus eggs (Heald, R., R. Tournebize, T. Blank, R. Sandaltzopoulos, P. Becker, A. Hyman, and E. Karsenti. 1996. Nature (Lond.). 382: 420–425) demonstrate that there is a common mechanism for focusing free microtubule minus ends in both centrosomal and acentrosomal spindles. We discuss these observations in the context of a search-capture-focus model for spindle assembly.