Limits...
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.

Show MeSH

Related in: MedlinePlus

KLP10A localizes to the meiosis I spindle and chromosomes. (A) KLP10A (green) in fixed (top) or live (bottom) klp10A-gfp/ncd–monomeric RFP oocytes localizes to the meiosis I spindle, the unusual pole bodies (arrows), and chromosome centromeres (arrowheads). NCD (red) is present throughout the spindle but not at the pole bodies or centromeres. DNA, blue. (B) The pole bodies in live klp10A-gfp oocytes change in number and position over time. Time is given in hours and minutes. (C) KLP10A associates with nascent meiosis I spindle poles and centromeres early during spindle assembly. Accumulation of KLP10A around the germinal vesicle at nuclear envelope breakdown and formation of foci in the germinal vesicle (green arrowhead; left), KLP10A foci at the chromosomes (green arrowheads), poles (arrows) of the microtubule arrays that form around each bivalent chromosome during spindle assembly (center; Sköld et al., 2005), and KLP10A on the meiosis I spindle, pole bodies (arrows), and centromeres (arrowheads; right). Bars, 10 μm (C, four images at left, 20 μm).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2234233&req=5

fig1: KLP10A localizes to the meiosis I spindle and chromosomes. (A) KLP10A (green) in fixed (top) or live (bottom) klp10A-gfp/ncd–monomeric RFP oocytes localizes to the meiosis I spindle, the unusual pole bodies (arrows), and chromosome centromeres (arrowheads). NCD (red) is present throughout the spindle but not at the pole bodies or centromeres. DNA, blue. (B) The pole bodies in live klp10A-gfp oocytes change in number and position over time. Time is given in hours and minutes. (C) KLP10A associates with nascent meiosis I spindle poles and centromeres early during spindle assembly. Accumulation of KLP10A around the germinal vesicle at nuclear envelope breakdown and formation of foci in the germinal vesicle (green arrowhead; left), KLP10A foci at the chromosomes (green arrowheads), poles (arrows) of the microtubule arrays that form around each bivalent chromosome during spindle assembly (center; Sköld et al., 2005), and KLP10A on the meiosis I spindle, pole bodies (arrows), and centromeres (arrowheads; right). Bars, 10 μm (C, four images at left, 20 μm).

Mentions: Metaphase I spindles in fixed or live wild-type klp10A-gfp oocytes showed bright fluorescently labeled bodies at their poles (Fig. 1 A, arrows). Thick spindle fibers that terminated at bars or discs on the meiotic chromosomes (Fig. 1 A, arrowheads) were also fluorescently labeled and were especially prominent in fixed oocytes. At least some of these are probably kinetochore fibers interacting with kinetochores based on their bundled appearance and labeling by KLP10A of disclike structures on the chromosomes, but they could include other spindle microtubules. The most unusual of the fluorescently labeled structures were the bodies at the anastral spindle poles, which were attached to the poles or near the poles. These bodies have been observed previously (Wilson and Borisy, 1998) and were reported to contain the Msps and D-TAAC centrosomal proteins (Cullen and Ohkura, 2001) but have not previously been reported to contain microtubule motors. KLP10A binding to the meiosis I spindle, pole bodies, and meiotic chromosome centromeres was confirmed by staining wild-type oocytes with KLP10A antibodies (Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200711031/DC1).


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

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

KLP10A localizes to the meiosis I spindle and chromosomes. (A) KLP10A (green) in fixed (top) or live (bottom) klp10A-gfp/ncd–monomeric RFP oocytes localizes to the meiosis I spindle, the unusual pole bodies (arrows), and chromosome centromeres (arrowheads). NCD (red) is present throughout the spindle but not at the pole bodies or centromeres. DNA, blue. (B) The pole bodies in live klp10A-gfp oocytes change in number and position over time. Time is given in hours and minutes. (C) KLP10A associates with nascent meiosis I spindle poles and centromeres early during spindle assembly. Accumulation of KLP10A around the germinal vesicle at nuclear envelope breakdown and formation of foci in the germinal vesicle (green arrowhead; left), KLP10A foci at the chromosomes (green arrowheads), poles (arrows) of the microtubule arrays that form around each bivalent chromosome during spindle assembly (center; Sköld et al., 2005), and KLP10A on the meiosis I spindle, pole bodies (arrows), and centromeres (arrowheads; right). Bars, 10 μm (C, four images at left, 20 μm).
© Copyright Policy
Related In: Results  -  Collection

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

fig1: KLP10A localizes to the meiosis I spindle and chromosomes. (A) KLP10A (green) in fixed (top) or live (bottom) klp10A-gfp/ncd–monomeric RFP oocytes localizes to the meiosis I spindle, the unusual pole bodies (arrows), and chromosome centromeres (arrowheads). NCD (red) is present throughout the spindle but not at the pole bodies or centromeres. DNA, blue. (B) The pole bodies in live klp10A-gfp oocytes change in number and position over time. Time is given in hours and minutes. (C) KLP10A associates with nascent meiosis I spindle poles and centromeres early during spindle assembly. Accumulation of KLP10A around the germinal vesicle at nuclear envelope breakdown and formation of foci in the germinal vesicle (green arrowhead; left), KLP10A foci at the chromosomes (green arrowheads), poles (arrows) of the microtubule arrays that form around each bivalent chromosome during spindle assembly (center; Sköld et al., 2005), and KLP10A on the meiosis I spindle, pole bodies (arrows), and centromeres (arrowheads; right). Bars, 10 μm (C, four images at left, 20 μm).
Mentions: Metaphase I spindles in fixed or live wild-type klp10A-gfp oocytes showed bright fluorescently labeled bodies at their poles (Fig. 1 A, arrows). Thick spindle fibers that terminated at bars or discs on the meiotic chromosomes (Fig. 1 A, arrowheads) were also fluorescently labeled and were especially prominent in fixed oocytes. At least some of these are probably kinetochore fibers interacting with kinetochores based on their bundled appearance and labeling by KLP10A of disclike structures on the chromosomes, but they could include other spindle microtubules. The most unusual of the fluorescently labeled structures were the bodies at the anastral spindle poles, which were attached to the poles or near the poles. These bodies have been observed previously (Wilson and Borisy, 1998) and were reported to contain the Msps and D-TAAC centrosomal proteins (Cullen and Ohkura, 2001) but have not previously been reported to contain microtubule motors. KLP10A binding to the meiosis I spindle, pole bodies, and meiotic chromosome centromeres was confirmed by staining wild-type oocytes with KLP10A antibodies (Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200711031/DC1).

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