期刊
JOURNAL OF CELL BIOLOGY
卷 162, 期 3, 页码 377-382出版社
ROCKEFELLER UNIV PRESS
DOI: 10.1083/jcb.200301088
关键词
kinetochore; fluorescent speckle microscopy; mitosis; centromere; anaphase
类别
资金
- NIGMS NIH HHS [GM24364, R01 GM024364, R37 GM024364, GM39565, R37 GM039565, R01 GM039565, GM606780, R01 GM060678] Funding Source: Medline
Microtubule plus ends dynamically attach to kinetochores on mitotic chromosomes. We directly imaged this dynamic interface using high resolution fluorescent speckle microscopy and direct labeling of kinetochores in Xenopus extract spindles. During metaphase, kinetochores were stationary and under tension while plus end polymerization and poleward microtubule flux (flux) occurred at velocities varying from 1.5-2.5 mum/min. Because kinetochore microtubules polymerize at metaphase kinetochores, the primary source of kinetochore tension must be the spindle forces that produce flux and not a kinetochore-based mechanism. We infer that the kinetochore resists translocation of kinetochore microtubules through their attachment sites, and that the polymerization state of the kinetochore acts a slip-clutch mechanism that prevents detachment at high tension. At anaphase onset, kinetochores switched to depolymerization of microtubule plus ends, resulting in chromosome-to-pole rates transiently greater than flux. Kinetochores switched from persistent depolymerization to persistent polymerization and back again during anaphase, bistability exhibited by kinetochores in vertebrate tissue cells. These results provide the most complete description of spindle microtubule poleward flux to date, with important implications for the microtubule-kinetochore interface and for how flux regulates kinetochore function.
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