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Curr Biol
2009 Feb 24;194:287-96. doi: 10.1016/j.cub.2009.01.055.
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Spindle fusion requires dynein-mediated sliding of oppositely oriented microtubules.
Gatlin JC
,
Matov A
,
Groen AC
,
Needleman DJ
,
Maresca TJ
,
Danuser G
,
Mitchison TJ
,
Salmon ED
.
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BACKGROUND: Bipolar spindle assembly is critical for achieving accurate segregation of chromosomes. In the absence of centrosomes, meiotic spindles achieve bipolarity by a combination of chromosome-initiated microtubule nucleation and stabilization and motor-driven organization of microtubules. Once assembled, the spindle structure is maintained on a relatively long time scale despite the high turnover of the microtubules that comprise it. To study the underlying mechanisms responsible for spindle assembly and steady-state maintenance, we used microneedle manipulation of preassembled spindles in Xenopus egg extracts.
RESULTS: When two meiotic spindles were brought close enough together, they interacted, creating an interconnected microtubule structure with supernumerary poles. Without exception, the perturbed system eventually re-established bipolarity, forming a single spindle of normal shape and size. Bipolar spindle fusion was blocked when cytoplasmic dynein function was perturbed, suggesting a critical role for the motor in this process. The fusion of Eg5-inhibited monopoles also required dynein function but only occurred if the initial interpolar separation was less than twice the microtubule radius of a typical monopole.
CONCLUSIONS: Our experiments uniquely illustrate the architectural plasticity of the spindle and reveal a robust ability of the system to attain a bipolar morphology. We hypothesize that a major mechanism driving spindle fusion is dynein-mediated sliding of oppositely oriented microtubules, a novel function for the motor, and posit that this same mechanism might also be involved in normal spindle assembly and homeostasis.
Brown,
Xenopus tropicalis egg extracts provide insight into scaling of the mitotic spindle.
2007, Pubmed,
Xenbase
Brown,
Xenopus tropicalis egg extracts provide insight into scaling of the mitotic spindle.
2007,
Pubmed
,
Xenbase
Burbank,
A new method reveals microtubule minus ends throughout the meiotic spindle.
2006,
Pubmed
,
Xenbase
Burbank,
Slide-and-cluster models for spindle assembly.
2007,
Pubmed
,
Xenbase
Chakravarty,
A mechanistic model for the organization of microtubule asters by motor and non-motor proteins in a mammalian mitotic extract.
2004,
Pubmed
Church,
Micromanipulated bivalents can trigger mini-spindle formation in Drosophila melanogaster spermatocyte cytoplasm.
1986,
Pubmed
Desai,
The use of Xenopus egg extracts to study mitotic spindle assembly and function in vitro.
1999,
Pubmed
,
Xenbase
Gaetz,
Dynein/dynactin regulate metaphase spindle length by targeting depolymerizing activities to spindle poles.
2004,
Pubmed
,
Xenbase
Gaetz,
Examining how the spatial organization of chromatin signals influences metaphase spindle assembly.
2006,
Pubmed
,
Xenbase
Groen,
XRHAMM functions in ran-dependent microtubule nucleation and pole formation during anastral spindle assembly.
2004,
Pubmed
,
Xenbase
Groen,
A novel small-molecule inhibitor reveals a possible role of kinesin-5 in anastral spindle-pole assembly.
2008,
Pubmed
,
Xenbase
Han,
The Aspergillus cytoplasmic dynein heavy chain and NUDF localize to microtubule ends and affect microtubule dynamics.
2001,
Pubmed
Heald,
Self-organization of microtubules into bipolar spindles around artificial chromosomes in Xenopus egg extracts.
1996,
Pubmed
,
Xenbase
Heald,
Spindle assembly in Xenopus egg extracts: respective roles of centrosomes and microtubule self-organization.
1997,
Pubmed
,
Xenbase
Kaláb,
Analysis of a RanGTP-regulated gradient in mitotic somatic cells.
2006,
Pubmed
,
Xenbase
Kapitein,
The bipolar mitotic kinesin Eg5 moves on both microtubules that it crosslinks.
2005,
Pubmed
,
Xenbase
Kapoor,
Eg5 is static in bipolar spindles relative to tubulin: evidence for a static spindle matrix.
2001,
Pubmed
,
Xenbase
Kapoor,
Probing spindle assembly mechanisms with monastrol, a small molecule inhibitor of the mitotic kinesin, Eg5.
2000,
Pubmed
,
Xenbase
Khodjakov,
Minus-end capture of preformed kinetochore fibers contributes to spindle morphogenesis.
2003,
Pubmed
Lee,
The role of the lissencephaly protein Pac1 during nuclear migration in budding yeast.
2003,
Pubmed
Mahoney,
Making microtubules and mitotic spindles in cells without functional centrosomes.
2006,
Pubmed
Maiato,
Kinetochore-driven formation of kinetochore fibers contributes to spindle assembly during animal mitosis.
2004,
Pubmed
Mayer,
Small molecule inhibitor of mitotic spindle bipolarity identified in a phenotype-based screen.
1999,
Pubmed
,
Xenbase
Merdes,
Formation of spindle poles by dynein/dynactin-dependent transport of NuMA.
2000,
Pubmed
Mitchison,
Bipolarization and poleward flux correlate during Xenopus extract spindle assembly.
2004,
Pubmed
,
Xenbase
Mitchison,
Roles of polymerization dynamics, opposed motors, and a tensile element in governing the length of Xenopus extract meiotic spindles.
2005,
Pubmed
,
Xenbase
Miyamoto,
The kinesin Eg5 drives poleward microtubule flux in Xenopus laevis egg extract spindles.
2004,
Pubmed
,
Xenbase
Murray,
Cell cycle extracts.
1991,
Pubmed
Nédélec,
Computer simulations reveal motor properties generating stable antiparallel microtubule interactions.
2002,
Pubmed
,
Xenbase
O'Connell,
Cooperative mechanisms of mitotic spindle formation.
2007,
Pubmed
Paschal,
Retrograde transport by the microtubule-associated protein MAP 1C.
,
Pubmed
Pfarr,
Cytoplasmic dynein is localized to kinetochores during mitosis.
1990,
Pubmed
Ross,
Processive bidirectional motion of dynein-dynactin complexes in vitro.
2006,
Pubmed
Savoian,
Mitosis in primary cultures of Drosophila melanogaster larval neuroblasts.
2002,
Pubmed
Sharp,
Antagonistic microtubule-sliding motors position mitotic centrosomes in Drosophila early embryos.
1999,
Pubmed
Shimizu,
Comparison of the motile and enzymatic properties of two microtubule minus-end-directed motors, ncd and cytoplasmic dynein.
1995,
Pubmed
Shirasu-Hiza,
Eg5 causes elongation of meiotic spindles when flux-associated microtubule depolymerization is blocked.
2004,
Pubmed
,
Xenbase
Tirnauer,
EB1-microtubule interactions in Xenopus egg extracts: role of EB1 in microtubule stabilization and mechanisms of targeting to microtubules.
2002,
Pubmed
,
Xenbase
Torosantucci,
Localized RanGTP accumulation promotes microtubule nucleation at kinetochores in somatic mammalian cells.
2008,
Pubmed
Tulu,
Peripheral, non-centrosome-associated microtubules contribute to spindle formation in centrosome-containing cells.
2003,
Pubmed
Tulu,
Molecular requirements for kinetochore-associated microtubule formation in mammalian cells.
2006,
Pubmed
Uteng,
Poleward transport of Eg5 by dynein-dynactin in Xenopus laevis egg extract spindles.
2008,
Pubmed
,
Xenbase
Vaughan,
Cytoplasmic dynein intermediate chain phosphorylation regulates binding to dynactin.
2001,
Pubmed
Vaughan,
Colocalization of cytoplasmic dynein with dynactin and CLIP-170 at microtubule distal ends.
1999,
Pubmed
Verde,
Taxol-induced microtubule asters in mitotic extracts of Xenopus eggs: requirement for phosphorylated factors and cytoplasmic dynein.
1991,
Pubmed
,
Xenbase
Walczak,
XCTK2: a kinesin-related protein that promotes mitotic spindle assembly in Xenopus laevis egg extracts.
1997,
Pubmed
,
Xenbase
Walczak,
Mechanisms of mitotic spindle assembly and function.
2008,
Pubmed
,
Xenbase
Wilde,
Ran stimulates spindle assembly by altering microtubule dynamics and the balance of motor activities.
2001,
Pubmed
,
Xenbase
Wühr,
Evidence for an upper limit to mitotic spindle length.
2008,
Pubmed
,
Xenbase
Yang,
Architectural dynamics of the meiotic spindle revealed by single-fluorophore imaging.
2007,
Pubmed
,
Xenbase
