Kinetochore-driven outgrowth of microtubules is a central contributor to kinetochore fiber maturation in crane-fly spermatocytes.
Kinetochore-driven outgrowth of microtubules is a central contributor to kinetochore fiber maturation in crane-fly spermatocytes.
复制标题
着丝粒驱动的微管生长是鹤蝇精母细胞着丝粒纤维成熟的主要贡献者。
DOI：
10.1091/mbc.e14-01-0008
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发表时间：
2014
影响因子：
3.3
通讯作者：
Oldenbourg,Rudolf
中科院分区：
文献类型：
--
作者：
LaFountainJr,JamesR;Oldenbourg,Rudolf
我们用液晶偏振光成像技术记录了活的鹤蝇精母细胞中单个动粒(K-)纤维的生活史，从早期早期的新生K-纤维到中期的完全成熟的K-纤维，直到后期开始。由于延迟性增加而增加的图像亮度揭示了在K纤维形成过程中微管被添加的位置。对实验产生的只有一个中心体的双极纺锤体以及规则的双着丝体纺锤体的分析表明，微管添加发生在K纤维的动粒近端，添加的聚合物向极扩张，导致中期细胞的K纤维粗壮。这些结果与K纤维形成的模型不兼容，在K纤维形成模型中，微管仅通过重复地“搜索和捕获”中心体微管和末端而添加到新生纤维中。我们的解释是，中心体微管的捕获--当部署时--仅限于新生K纤维的建立的早期阶段，然后K纤维通过动粒驱动的外延生长成熟。当不使用中心体微管的动粒捕获时，K纤维的极端从它们的动心向外生长，通常会聚在一起形成一个无中心体的极点。
We use liquid crystal polarized light imaging to record the life histories of single kinetochore (K-) fibers in living crane-fly spermatocytes, from their origins as nascent K-fibers in early prometaphase to their fully matured form at metaphase, just before anaphase onset. Increased image brightness due to increased retardance reveals where microtubules are added during K-fiber formation. Analysis of experimentally generated bipolar spindles with only one centrosome, as well as of regular, bicentrosomal spindles, reveals that microtubule addition occurs at the kinetochore-proximal ends of K-fibers, and added polymer expands poleward, giving rise to the robust K-fibers of metaphase cells. These results are not compatible with a model for K-fiber formation in which microtubules are added to nascent fibers solely by repetitive “search and capture” of centrosomal microtubule plus ends. Our interpretation is that capture of centrosomal microtubules—when deployed—is limited to early stages in establishment of nascent K-fibers, which then mature through kinetochore-driven outgrowth. When kinetochore capture of centrosomal microtubules is not used, the polar ends of K-fibers grow outward from their kinetochores and usually converge to make a centrosome-free pole.