TY - JOUR
T1 - Spindle Fusion Requires Dynein-Mediated Sliding of Oppositely Oriented Microtubules
AU - Gatlin, Jesse C.
AU - Matov, Alexandre
AU - Groen, Aaron C.
AU - Needleman, Daniel J.
AU - Maresca, Thomas J.
AU - Danuser, Gaudenz
AU - Mitchison, Timothy J.
AU - Salmon, E. D.
N1 - Funding Information:
We thank L. Cameron (Dana-Farber Cancer Institute), A. Joglekar (University of North Carolina at Chapel Hill), and S. Dumont (Harvard Medical School) for helpful discussions, comments, and critical reading of the manuscript, as well as other members of the Salmon Laboratory and the Cell Division Group. We also thank K. Vaughan (University of Notre Dame) for the generous gift of anti-dynein intermediate chain antibody. A special thanks goes to H. Luther and M. Peterson (Marine Biological Laboratories) for help with acquiring necessary equipment. This work was supported by National Institute of General Medicine grants to J.C.G. (F32GM080049), E.D.S. (GM24364), and G.D. (GM60678). T.J.M. was funded by the National Cancer Institute (CA078048-09).
PY - 2009/2/24
Y1 - 2009/2/24
N2 - 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.
AB - 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.
KW - CELLBIO
UR - http://www.scopus.com/inward/record.url?scp=60349102244&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=60349102244&partnerID=8YFLogxK
U2 - 10.1016/j.cub.2009.01.055
DO - 10.1016/j.cub.2009.01.055
M3 - Article
C2 - 19230671
AN - SCOPUS:60349102244
SN - 0960-9822
VL - 19
SP - 287
EP - 296
JO - Current Biology
JF - Current Biology
IS - 4
ER -