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A microtubule-destabilizing kinesin motor regulates spindle length and anchoring in oocytes.

Zou J, Hallen MA, Yankel CD, Endow SA - J. Cell Biol. (2008)

Bottom Line: We frequently observe the pole bodies attached to cortical microtubules, indicating that KLP10A could mediate spindle anchoring to the cortex via cortical microtubules.A dominant-negative klp10A mutant shows both reoriented and shorter oocyte spindles, implying that, unexpectedly, KLP10A may stabilize rather than destabilize microtubules, regulating spindle length and positioning the oocyte spindle.By altering microtubule dynamics, KLP10A could promote spindle reorientation upon oocyte activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.

ABSTRACT
The kinesin-13 motor, KLP10A, destabilizes microtubules at their minus ends in mitosis and binds to polymerizing plus ends in interphase, regulating spindle and microtubule dynamics. Little is known about kinesin-13 motors in meiosis. In this study, we report that KLP10A localizes to the unusual pole bodies of anastral Drosophila melanogaster oocyte meiosis I spindles as well as spindle fibers, centromeres, and cortical microtubules. We frequently observe the pole bodies attached to cortical microtubules, indicating that KLP10A could mediate spindle anchoring to the cortex via cortical microtubules. Oocytes treated with drugs that suppress microtubule dynamics exhibit spindles that are reoriented more vertically to the cortex than untreated controls. A dominant-negative klp10A mutant shows both reoriented and shorter oocyte spindles, implying that, unexpectedly, KLP10A may stabilize rather than destabilize microtubules, regulating spindle length and positioning the oocyte spindle. By altering microtubule dynamics, KLP10A could promote spindle reorientation upon oocyte activation.

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Microtubule-destabilizing/stabilizing drugs affect meiosis I spindle length and orientation. (A and C) Spindle length and pole depth from the chorion were estimated from z sections (0.5-μm steps) of fixed whole-mount klp10A-gfp (A) or klp10A NT–-gfp oocytes (C) either untreated or treated with colchicine or taxol. Mean ± SEM (error bars). (B) Schematic diagram illustrating the effects of colchicine and taxol on spindle length, angle, and depth relative to the cortex in klp10A-gfp oocytes. Both drugs cause the spindle to move deeper into the oocyte and orient more vertically to the cortex.
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fig3: Microtubule-destabilizing/stabilizing drugs affect meiosis I spindle length and orientation. (A and C) Spindle length and pole depth from the chorion were estimated from z sections (0.5-μm steps) of fixed whole-mount klp10A-gfp (A) or klp10A NT–-gfp oocytes (C) either untreated or treated with colchicine or taxol. Mean ± SEM (error bars). (B) Schematic diagram illustrating the effects of colchicine and taxol on spindle length, angle, and depth relative to the cortex in klp10A-gfp oocytes. Both drugs cause the spindle to move deeper into the oocyte and orient more vertically to the cortex.

Mentions: Colchicine also resulted in highly abnormal meiosis I spindles that were much shorter (7.81 ± 0.53 μm; n = 34) than those of untreated klp10A-gfp females (16.1 ± 0.57 μm; n = 19; Figs. 2 B and 3 A). The spindles were deeper in the oocyte and more vertical in angle (θ = 45.6 ± 3.8°; n = 34) than untreated oocytes (θ = 8.3 ± 1.5°; n = 19; Fig. 3, A and B); spindles before activation are almost parallel to the dorsal surface. Oocytes from females treated with the microtubule-stabilizing drug, taxol, did not show an overall change in meiosis I spindle length (15.7 ± 0.64 μm; n = 38) compared with untreated oocytes. The spindle poles showed brighter KLP10A-GFP fluorescence than untreated controls (Fig. 2 B, arrows), and spindles showed small changes in depth and angle. Both were less pronounced than with colchicine (Fig. 3, A and B) and were presumably caused by the suppression of microtubule dynamics.


A microtubule-destabilizing kinesin motor regulates spindle length and anchoring in oocytes.

Zou J, Hallen MA, Yankel CD, Endow SA - J. Cell Biol. (2008)

Microtubule-destabilizing/stabilizing drugs affect meiosis I spindle length and orientation. (A and C) Spindle length and pole depth from the chorion were estimated from z sections (0.5-μm steps) of fixed whole-mount klp10A-gfp (A) or klp10A NT–-gfp oocytes (C) either untreated or treated with colchicine or taxol. Mean ± SEM (error bars). (B) Schematic diagram illustrating the effects of colchicine and taxol on spindle length, angle, and depth relative to the cortex in klp10A-gfp oocytes. Both drugs cause the spindle to move deeper into the oocyte and orient more vertically to the cortex.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2234233&req=5

fig3: Microtubule-destabilizing/stabilizing drugs affect meiosis I spindle length and orientation. (A and C) Spindle length and pole depth from the chorion were estimated from z sections (0.5-μm steps) of fixed whole-mount klp10A-gfp (A) or klp10A NT–-gfp oocytes (C) either untreated or treated with colchicine or taxol. Mean ± SEM (error bars). (B) Schematic diagram illustrating the effects of colchicine and taxol on spindle length, angle, and depth relative to the cortex in klp10A-gfp oocytes. Both drugs cause the spindle to move deeper into the oocyte and orient more vertically to the cortex.
Mentions: Colchicine also resulted in highly abnormal meiosis I spindles that were much shorter (7.81 ± 0.53 μm; n = 34) than those of untreated klp10A-gfp females (16.1 ± 0.57 μm; n = 19; Figs. 2 B and 3 A). The spindles were deeper in the oocyte and more vertical in angle (θ = 45.6 ± 3.8°; n = 34) than untreated oocytes (θ = 8.3 ± 1.5°; n = 19; Fig. 3, A and B); spindles before activation are almost parallel to the dorsal surface. Oocytes from females treated with the microtubule-stabilizing drug, taxol, did not show an overall change in meiosis I spindle length (15.7 ± 0.64 μm; n = 38) compared with untreated oocytes. The spindle poles showed brighter KLP10A-GFP fluorescence than untreated controls (Fig. 2 B, arrows), and spindles showed small changes in depth and angle. Both were less pronounced than with colchicine (Fig. 3, A and B) and were presumably caused by the suppression of microtubule dynamics.

Bottom Line: We frequently observe the pole bodies attached to cortical microtubules, indicating that KLP10A could mediate spindle anchoring to the cortex via cortical microtubules.A dominant-negative klp10A mutant shows both reoriented and shorter oocyte spindles, implying that, unexpectedly, KLP10A may stabilize rather than destabilize microtubules, regulating spindle length and positioning the oocyte spindle.By altering microtubule dynamics, KLP10A could promote spindle reorientation upon oocyte activation.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.

ABSTRACT
The kinesin-13 motor, KLP10A, destabilizes microtubules at their minus ends in mitosis and binds to polymerizing plus ends in interphase, regulating spindle and microtubule dynamics. Little is known about kinesin-13 motors in meiosis. In this study, we report that KLP10A localizes to the unusual pole bodies of anastral Drosophila melanogaster oocyte meiosis I spindles as well as spindle fibers, centromeres, and cortical microtubules. We frequently observe the pole bodies attached to cortical microtubules, indicating that KLP10A could mediate spindle anchoring to the cortex via cortical microtubules. Oocytes treated with drugs that suppress microtubule dynamics exhibit spindles that are reoriented more vertically to the cortex than untreated controls. A dominant-negative klp10A mutant shows both reoriented and shorter oocyte spindles, implying that, unexpectedly, KLP10A may stabilize rather than destabilize microtubules, regulating spindle length and positioning the oocyte spindle. By altering microtubule dynamics, KLP10A could promote spindle reorientation upon oocyte activation.

Show MeSH
Related in: MedlinePlus