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Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes
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Cyclin B3 controls anaphase onset independent of spindle assembly checkpoint in meiotic oocytes

Teng Zhang1, Shu-Tao Qi, Lin Huang

  • 1a Institute of Reproductive Sciences; College of Animal Science and Technology; Qingdao Agricultural University ; Qingdao , China.

Cell Cycle (Georgetown, Tex.)
|July 1, 2015
PubMed

Insights

Cyclin B3 depletion halts the metaphase-anaphase transition in oocytes by activating APC/C(cdc20), independent of the spindle assembly checkpoint (SAC). This finding clarifies cyclin B3

Area of Science:

  • Cellular and Molecular Biology
  • Reproductive Biology
  • Cell Cycle Regulation

Background:

  • Cyclin B3 is an understudied member of the cyclin family.
  • Its precise role in cell division, particularly meiosis, remains largely unknown.

Purpose of the Study:

  • To investigate the function of cyclin B3 in meiotic oocytes.
  • To determine the mechanism by which cyclin B3 regulates the metaphase-anaphase transition.

Main Methods:

  • Depletion of cyclin B3 in meiotic oocytes.
  • Assessment of metaphase-anaphase transition.
  • Analysis of spindle assembly checkpoint (SAC) activity, including Bub3, BubR1, Mad2, and cdc20.
  • Evaluation of securin RNA interference (RNAi).

Main Results:

  • Cyclin B3 depletion inhibited the metaphase-anaphase transition, evidenced by sustained metaphase I (MI) spindles and cyclin B1 expression.
  • This inhibition was independent of SAC activity, as Bub3 and BubR1 were absent from kinetochores in arrested cells.
  • Mad2 knockdown and cdc20 overexpression did not rescue the MI arrest, but securin RNAi did.

Conclusions:

  • Cyclin B3 controls the metaphase-anaphase transition in meiotic oocytes.
  • It achieves this by activating the anaphase-promoting complex/cyclosome (APC/C) complexed with cdc20.
  • This regulatory process operates independently of spindle assembly checkpoint (SAC) signaling.
Keywords:
Cyclin B3SACanaphase initiationmeiosisoocyte

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