Abstract
Kif2a is a member of the Kinesin-13 microtubule depolymerases. Here, we report the expression, subcellular localization and functions of Kif2a during mouse oocyte meiotic maturation. Immunoblotting analysis showed that Kif2a was gradually increased form GV to the M I stages, and then decreased slightly at the M II stage. Confocal microscopy identified that Kif2a localized to the meiotic spindle, especially concentrated at the spindle poles and inner centromeres in metaphase and translocated to the midbody at telophase. Kif2a depletion by siRNA microinjection generated severely defective spindles and misaligned chromosomes, reduced microtubule depolymerization, which led to significant pro-M I/M Iarrest and failure of first polar body (PB1) extrusion. Kif2a-depleted oocytes were also defective in spindle pole localization of γ-tubulin and showed spindle assembly checkpoint (SAC) protein Bub3 at the kinetochores even after 10 hr extended culture. These results demonstrate that Kif2a may act as a microtubule depolymerase, regulating microtubule dynamics, spindle assembly and chromosome congression, and thus cell cycle progression during mouse oocyte meiotic maturation.
Highlights
Kif2a is a member of the Kinesin-13 microtubule depolymerases
The formation of meiotic spindles relies on concerted actions of multiple microtubule organizing centers (MTOCs), microtubule depolymerases such as the kinesin-13 family of proteins, and of microtubule-associated proteins (MAPs)[5,6]
We found that the expression level of Kif2a was gradually increased form GV to the M I stages, and decreased slightly at the M II stage and localized to both spindle microtubules and centromeres, concentrated at spindle poles, and was required for spindle assembly, spindle pole formation, chromosome segregation and the first polar body extrusion during mouse oocyte meiotic maturation
Summary
Kif2a is a member of the Kinesin-13 microtubule depolymerases. Here, we report the expression, subcellular localization and functions of Kif2a during mouse oocyte meiotic maturation. Kif2a-depleted oocytes were defective in spindle pole localization of γ-tubulin and showed spindle assembly checkpoint (SAC) protein Bub[3] at the kinetochores even after 10 hr extended culture. These results demonstrate that Kif2a may act as a microtubule depolymerase, regulating microtubule dynamics, spindle assembly and chromosome congression, and cell cycle progression during mouse oocyte meiotic maturation. Mammals have three members of the kinesin-13 family, including Kif2a, Kif2b, and MCAK/Kif2c These proteins localize to different components of the spindle, and their concerted action controls many processes, such as bipolar spindle organization, kinetochore-microtubule capture, and chromosome movement in mitosis[16].
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