期刊
CURRENT BIOLOGY
卷 16, 期 19, 页码 1944-1949出版社
CELL PRESS
DOI: 10.1016/j.cub.2006.08.029
关键词
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资金
- NCRR NIH HHS [RR00592] Funding Source: Medline
Katanin is a heterodimer that exhibits ATP-dependent microtubule-severing activity in vitro [1, 2]. In Xenopus egg extracts, katanin activity correlates with the addition of cyclin B/cdc2, suggesting a role for microtubule severing in the disassembly of long interphase microtubules as the cell prepares for mitosis [3, 4]. However, studies from plant cells [5, 6], cultured neurons [7], and nematode embryos [8, 9] suggest that katanin could be required for the organization or postnucleation processing of microtubules, rather than the dissolution of microtubule structures. Here we re-examine katanin's role by studying acentrosomal female meiotic spindles in C. elegans embryos. In mutant embryos lacking katanin, microtubules form around meiotic chromatin but do not organize into bipolar spindles [8, 9]. By using electron tomography, we found that katanin converts long microtubule polymers into shorter microtubule fragments near meiotic chromatin. We further show that turning on katanin during mitosis also creates a large pool of short microtubules near the centrosome. Furthermore, the identification of katanin-dependent microtubule lattice defects supports a mechanism involving an initial perforation of the protofilament wall. Taken together, our data suggest that katanin is used during meiotic spindle assembly to increase polymer number from a relatively inefficient chromatin-based microtubule nucleation pathway.
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