Kinetochore dynein generates a poleward pulling force to facilitate congression and full chromosome alignment.
For proper chromosome segregation, all kinetochores must achieve bipolar microtubule (MT) attachment and subsequently align at the spindle equator before anaphase onset. The MT minus end-directed motor dynein/dynactin binds kinetochores in prometaphase and has long been implicated in chromosome congression. Unfortunately, inactivation of dynein usually disturbs spindle organization, thus hampering evaluation of its kinetochore roles. Here we specifically eliminated kinetochore dynein/dynactin by RNAi-mediated depletion of ZW10, a protein essential for kinetochore localization of the motor. Time-lapse microscopy indicated markedly-reduced congression efficiency, though congressing chromosomes displayed similar velocities as in control cells. Moreover, cells frequently failed to achieve full chromosome alignment, despite their normal spindles. Confocal microcopy revealed that the misaligned kinetochores were monooriented or unattached and mostly lying outside the spindle, suggesting a difficulty to capture MTs from the opposite pole. Kinetochores on monoastral spindles were dispersed farther away from the pole and exhibited only mild oscillation. Furthermore, inactivating dynein by other means generated similar phenotypes. Therefore, kinetochore dynein produces on monooriented kinetochores a poleward pulling force, which may contribute to efficient bipolar attachment by facilitating their proper microtubule captures to promote congression as well as full chromosome alignment.
Li
Yan
Y
Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Yu
Wei
W
Liang
Yun
Y
Zhu
Xueliang
X
D000705:Anaphase / Q000235:genetics / Q000502:physiology; D002460:Cell Line; D048750:Cell Nucleus Division / Q000235:genetics / Q000502:physiology*; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology; D000072159:Dynactin Complex; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000502:physiology; D018386:Kinetochores / Q000378:metabolism*; D008677:Metaphase / Q000235:genetics / Q000502:physiology; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000502:physiology; D008870:Microtubules / Q000378:metabolism / Q000502:physiology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology; D034622:RNA Interference; D008941:Spindle Apparatus / Q000235:genetics / Q000502:physiology; D014404:Tubulin / Q000378:metabolism
D000072159:Dynactin Complex; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D014404:Tubulin; C413695:ZWINT protein, human; D004398:Dyneins