Misorientation and reduced stretching of aligned sister kinetochores promote chromosome missegregation in EB1- or APC-depleted cells
Misorientation and reduced stretching of aligned sister kinetochores promote chromosome missegregation in EB1- or APC-depleted cells
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DOI：
10.1038/sj.emboj.7601168
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发表时间：
2006-06-21
期刊：
影响因子：
11.4
通讯作者：
Sorger, P. K.
中科院分区：
文献类型：
--
作者：
Draviam, V. M.;Shapiro, I.;Sorger, P. K.
染色体和纺锤体微管（MT）之间稳定但动态的连接的正确形成对于精确的染色体分离是必不可少的。然而，动粒结合MT和检查点监测这种结合的分子机制仍然知之甚少。在本文中，我们分析了六个kinetochore-bound MT相关蛋白（kMAPs）的功能，使用RNAi，活细胞显微镜和定量图像分析。我们发现，RNA干扰介导的两种kMAP（大肠腺瘤性息肉病蛋白（APC）及其结合伴侣EB 1）的缺失在影响中期板配对姐妹染色单体的运动和方向而不干扰动粒- MT附着本身方面是不寻常的。定量分析表明，即使在分裂后期的染色体丢失（CIN）是零星的，在中期的错误取向表型是均匀的染色单体对。然而，由APC或EB 1耗尽产生的动粒功能的错误被纺锤体检查点检测得很差，即使它们导致染色体错误分离。我们认为，EB 1或APC功能受损会产生纺锤体检查点不可见的病变，从而促进低水平的CIN，预期会促进非整倍体和可能的肿瘤发生。
The correct formation of stable but dynamic links between chromosomes and spindle microtubules ( MTs) is essential for accurate chromosome segregation. However, the molecular mechanisms by which kinetochores bind MTs and checkpoints monitor this binding remain poorly understood. In this paper, we analyze the functions of six kinetochore-bound MT-associated proteins ( kMAPs) using RNAi, live-cell microscopy and quantitative image analysis. We find that RNAi-mediated depletion of two kMAPs, the adenomatous polyposis coli protein ( APC) and its binding partner, EB1, are unusual in affecting the movement and orientation of paired sister chromatids at the metaphase plate without perturbing kinetochore - MT attachment per se. Quantitative analysis shows that misorientation phenotypes in metaphase are uniform across chromatid pairs even though chromosomal loss ( CIN) during anaphase is sporadic. However, errors in kinetochore function generated by APC or EB1 depletion are detected poorly if at all by the spindle checkpoint, even though they cause chromosome missegregation. We propose that impaired EB1 or APC function generates lesions invisible to the spindle checkpoint and thereby promotes low levels of CIN expected to fuel aneuploidy and possibly tumorigenesis.